mirror of
https://github.com/c64scene-ar/llvm-6502.git
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65314 91177308-0d34-0410-b5e6-96231b3b80d8
12653 lines
507 KiB
C++
12653 lines
507 KiB
C++
//===- InstructionCombining.cpp - Combine multiple instructions -----------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// InstructionCombining - Combine instructions to form fewer, simple
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// instructions. This pass does not modify the CFG. This pass is where
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// algebraic simplification happens.
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//
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// This pass combines things like:
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// %Y = add i32 %X, 1
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// %Z = add i32 %Y, 1
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// into:
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// %Z = add i32 %X, 2
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//
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// This is a simple worklist driven algorithm.
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//
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// This pass guarantees that the following canonicalizations are performed on
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// the program:
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// 1. If a binary operator has a constant operand, it is moved to the RHS
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// 2. Bitwise operators with constant operands are always grouped so that
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// shifts are performed first, then or's, then and's, then xor's.
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// 3. Compare instructions are converted from <,>,<=,>= to ==,!= if possible
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// 4. All cmp instructions on boolean values are replaced with logical ops
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// 5. add X, X is represented as (X*2) => (X << 1)
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// 6. Multiplies with a power-of-two constant argument are transformed into
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// shifts.
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// ... etc.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "instcombine"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/IntrinsicInst.h"
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#include "llvm/Pass.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/GlobalVariable.h"
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#include "llvm/Analysis/ConstantFolding.h"
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#include "llvm/Analysis/ValueTracking.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include "llvm/Support/CallSite.h"
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#include "llvm/Support/ConstantRange.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/GetElementPtrTypeIterator.h"
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#include "llvm/Support/InstVisitor.h"
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#include "llvm/Support/MathExtras.h"
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#include "llvm/Support/PatternMatch.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/ADT/STLExtras.h"
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#include <algorithm>
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#include <climits>
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#include <sstream>
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using namespace llvm;
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using namespace llvm::PatternMatch;
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STATISTIC(NumCombined , "Number of insts combined");
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STATISTIC(NumConstProp, "Number of constant folds");
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STATISTIC(NumDeadInst , "Number of dead inst eliminated");
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STATISTIC(NumDeadStore, "Number of dead stores eliminated");
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STATISTIC(NumSunkInst , "Number of instructions sunk");
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namespace {
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class VISIBILITY_HIDDEN InstCombiner
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: public FunctionPass,
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public InstVisitor<InstCombiner, Instruction*> {
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// Worklist of all of the instructions that need to be simplified.
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SmallVector<Instruction*, 256> Worklist;
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DenseMap<Instruction*, unsigned> WorklistMap;
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TargetData *TD;
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bool MustPreserveLCSSA;
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public:
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static char ID; // Pass identification, replacement for typeid
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InstCombiner() : FunctionPass(&ID) {}
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/// AddToWorkList - Add the specified instruction to the worklist if it
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/// isn't already in it.
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void AddToWorkList(Instruction *I) {
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if (WorklistMap.insert(std::make_pair(I, Worklist.size())).second)
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Worklist.push_back(I);
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}
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// RemoveFromWorkList - remove I from the worklist if it exists.
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void RemoveFromWorkList(Instruction *I) {
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DenseMap<Instruction*, unsigned>::iterator It = WorklistMap.find(I);
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if (It == WorklistMap.end()) return; // Not in worklist.
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// Don't bother moving everything down, just null out the slot.
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Worklist[It->second] = 0;
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WorklistMap.erase(It);
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}
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Instruction *RemoveOneFromWorkList() {
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Instruction *I = Worklist.back();
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Worklist.pop_back();
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WorklistMap.erase(I);
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return I;
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}
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/// AddUsersToWorkList - When an instruction is simplified, add all users of
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/// the instruction to the work lists because they might get more simplified
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/// now.
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///
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void AddUsersToWorkList(Value &I) {
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for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
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UI != UE; ++UI)
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AddToWorkList(cast<Instruction>(*UI));
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}
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/// AddUsesToWorkList - When an instruction is simplified, add operands to
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/// the work lists because they might get more simplified now.
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///
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void AddUsesToWorkList(Instruction &I) {
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for (User::op_iterator i = I.op_begin(), e = I.op_end(); i != e; ++i)
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if (Instruction *Op = dyn_cast<Instruction>(*i))
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AddToWorkList(Op);
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}
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/// AddSoonDeadInstToWorklist - The specified instruction is about to become
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/// dead. Add all of its operands to the worklist, turning them into
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/// undef's to reduce the number of uses of those instructions.
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///
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/// Return the specified operand before it is turned into an undef.
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///
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Value *AddSoonDeadInstToWorklist(Instruction &I, unsigned op) {
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Value *R = I.getOperand(op);
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for (User::op_iterator i = I.op_begin(), e = I.op_end(); i != e; ++i)
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if (Instruction *Op = dyn_cast<Instruction>(*i)) {
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AddToWorkList(Op);
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// Set the operand to undef to drop the use.
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*i = UndefValue::get(Op->getType());
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}
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return R;
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}
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public:
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virtual bool runOnFunction(Function &F);
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bool DoOneIteration(Function &F, unsigned ItNum);
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.addRequired<TargetData>();
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AU.addPreservedID(LCSSAID);
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AU.setPreservesCFG();
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}
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TargetData &getTargetData() const { return *TD; }
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// Visitation implementation - Implement instruction combining for different
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// instruction types. The semantics are as follows:
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// Return Value:
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// null - No change was made
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// I - Change was made, I is still valid, I may be dead though
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// otherwise - Change was made, replace I with returned instruction
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//
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Instruction *visitAdd(BinaryOperator &I);
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Instruction *visitSub(BinaryOperator &I);
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Instruction *visitMul(BinaryOperator &I);
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Instruction *visitURem(BinaryOperator &I);
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Instruction *visitSRem(BinaryOperator &I);
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Instruction *visitFRem(BinaryOperator &I);
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bool SimplifyDivRemOfSelect(BinaryOperator &I);
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Instruction *commonRemTransforms(BinaryOperator &I);
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Instruction *commonIRemTransforms(BinaryOperator &I);
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Instruction *commonDivTransforms(BinaryOperator &I);
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Instruction *commonIDivTransforms(BinaryOperator &I);
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Instruction *visitUDiv(BinaryOperator &I);
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Instruction *visitSDiv(BinaryOperator &I);
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Instruction *visitFDiv(BinaryOperator &I);
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Instruction *FoldAndOfICmps(Instruction &I, ICmpInst *LHS, ICmpInst *RHS);
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Instruction *visitAnd(BinaryOperator &I);
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Instruction *FoldOrOfICmps(Instruction &I, ICmpInst *LHS, ICmpInst *RHS);
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Instruction *FoldOrWithConstants(BinaryOperator &I, Value *Op,
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Value *A, Value *B, Value *C);
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Instruction *visitOr (BinaryOperator &I);
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Instruction *visitXor(BinaryOperator &I);
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Instruction *visitShl(BinaryOperator &I);
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Instruction *visitAShr(BinaryOperator &I);
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Instruction *visitLShr(BinaryOperator &I);
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Instruction *commonShiftTransforms(BinaryOperator &I);
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Instruction *FoldFCmp_IntToFP_Cst(FCmpInst &I, Instruction *LHSI,
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Constant *RHSC);
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Instruction *visitFCmpInst(FCmpInst &I);
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Instruction *visitICmpInst(ICmpInst &I);
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Instruction *visitICmpInstWithCastAndCast(ICmpInst &ICI);
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Instruction *visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
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Instruction *LHS,
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ConstantInt *RHS);
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Instruction *FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
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ConstantInt *DivRHS);
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Instruction *FoldGEPICmp(User *GEPLHS, Value *RHS,
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ICmpInst::Predicate Cond, Instruction &I);
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Instruction *FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
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BinaryOperator &I);
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Instruction *commonCastTransforms(CastInst &CI);
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Instruction *commonIntCastTransforms(CastInst &CI);
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Instruction *commonPointerCastTransforms(CastInst &CI);
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Instruction *visitTrunc(TruncInst &CI);
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Instruction *visitZExt(ZExtInst &CI);
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Instruction *visitSExt(SExtInst &CI);
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Instruction *visitFPTrunc(FPTruncInst &CI);
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Instruction *visitFPExt(CastInst &CI);
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Instruction *visitFPToUI(FPToUIInst &FI);
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Instruction *visitFPToSI(FPToSIInst &FI);
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Instruction *visitUIToFP(CastInst &CI);
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Instruction *visitSIToFP(CastInst &CI);
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Instruction *visitPtrToInt(CastInst &CI);
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Instruction *visitIntToPtr(IntToPtrInst &CI);
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Instruction *visitBitCast(BitCastInst &CI);
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Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
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Instruction *FI);
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Instruction *visitSelectInst(SelectInst &SI);
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Instruction *visitSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI);
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Instruction *visitCallInst(CallInst &CI);
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Instruction *visitInvokeInst(InvokeInst &II);
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Instruction *visitPHINode(PHINode &PN);
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Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
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Instruction *visitAllocationInst(AllocationInst &AI);
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Instruction *visitFreeInst(FreeInst &FI);
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Instruction *visitLoadInst(LoadInst &LI);
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Instruction *visitStoreInst(StoreInst &SI);
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Instruction *visitBranchInst(BranchInst &BI);
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Instruction *visitSwitchInst(SwitchInst &SI);
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Instruction *visitInsertElementInst(InsertElementInst &IE);
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Instruction *visitExtractElementInst(ExtractElementInst &EI);
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Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI);
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Instruction *visitExtractValueInst(ExtractValueInst &EV);
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// visitInstruction - Specify what to return for unhandled instructions...
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Instruction *visitInstruction(Instruction &I) { return 0; }
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private:
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Instruction *visitCallSite(CallSite CS);
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bool transformConstExprCastCall(CallSite CS);
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Instruction *transformCallThroughTrampoline(CallSite CS);
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Instruction *transformZExtICmp(ICmpInst *ICI, Instruction &CI,
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bool DoXform = true);
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bool WillNotOverflowSignedAdd(Value *LHS, Value *RHS);
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public:
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// InsertNewInstBefore - insert an instruction New before instruction Old
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// in the program. Add the new instruction to the worklist.
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//
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Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
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assert(New && New->getParent() == 0 &&
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"New instruction already inserted into a basic block!");
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BasicBlock *BB = Old.getParent();
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BB->getInstList().insert(&Old, New); // Insert inst
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AddToWorkList(New);
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return New;
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}
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/// InsertCastBefore - Insert a cast of V to TY before the instruction POS.
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/// This also adds the cast to the worklist. Finally, this returns the
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/// cast.
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Value *InsertCastBefore(Instruction::CastOps opc, Value *V, const Type *Ty,
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Instruction &Pos) {
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if (V->getType() == Ty) return V;
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if (Constant *CV = dyn_cast<Constant>(V))
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return ConstantExpr::getCast(opc, CV, Ty);
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Instruction *C = CastInst::Create(opc, V, Ty, V->getName(), &Pos);
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AddToWorkList(C);
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return C;
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}
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Value *InsertBitCastBefore(Value *V, const Type *Ty, Instruction &Pos) {
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return InsertCastBefore(Instruction::BitCast, V, Ty, Pos);
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}
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// ReplaceInstUsesWith - This method is to be used when an instruction is
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// found to be dead, replacable with another preexisting expression. Here
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// we add all uses of I to the worklist, replace all uses of I with the new
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// value, then return I, so that the inst combiner will know that I was
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// modified.
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//
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Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
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AddUsersToWorkList(I); // Add all modified instrs to worklist
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if (&I != V) {
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I.replaceAllUsesWith(V);
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return &I;
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} else {
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// If we are replacing the instruction with itself, this must be in a
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// segment of unreachable code, so just clobber the instruction.
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I.replaceAllUsesWith(UndefValue::get(I.getType()));
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return &I;
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}
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}
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// EraseInstFromFunction - When dealing with an instruction that has side
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// effects or produces a void value, we can't rely on DCE to delete the
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// instruction. Instead, visit methods should return the value returned by
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// this function.
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Instruction *EraseInstFromFunction(Instruction &I) {
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assert(I.use_empty() && "Cannot erase instruction that is used!");
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AddUsesToWorkList(I);
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RemoveFromWorkList(&I);
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I.eraseFromParent();
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return 0; // Don't do anything with FI
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}
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void ComputeMaskedBits(Value *V, const APInt &Mask, APInt &KnownZero,
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APInt &KnownOne, unsigned Depth = 0) const {
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return llvm::ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD, Depth);
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}
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bool MaskedValueIsZero(Value *V, const APInt &Mask,
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unsigned Depth = 0) const {
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return llvm::MaskedValueIsZero(V, Mask, TD, Depth);
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}
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unsigned ComputeNumSignBits(Value *Op, unsigned Depth = 0) const {
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return llvm::ComputeNumSignBits(Op, TD, Depth);
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}
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private:
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/// SimplifyCommutative - This performs a few simplifications for
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/// commutative operators.
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bool SimplifyCommutative(BinaryOperator &I);
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/// SimplifyCompare - This reorders the operands of a CmpInst to get them in
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/// most-complex to least-complex order.
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bool SimplifyCompare(CmpInst &I);
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/// SimplifyDemandedUseBits - Attempts to replace V with a simpler value
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/// based on the demanded bits.
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Value *SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
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APInt& KnownZero, APInt& KnownOne,
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unsigned Depth);
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bool SimplifyDemandedBits(Use &U, APInt DemandedMask,
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APInt& KnownZero, APInt& KnownOne,
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unsigned Depth=0);
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/// SimplifyDemandedInstructionBits - Inst is an integer instruction that
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/// SimplifyDemandedBits knows about. See if the instruction has any
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/// properties that allow us to simplify its operands.
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bool SimplifyDemandedInstructionBits(Instruction &Inst);
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Value *SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
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APInt& UndefElts, unsigned Depth = 0);
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// FoldOpIntoPhi - Given a binary operator or cast instruction which has a
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// PHI node as operand #0, see if we can fold the instruction into the PHI
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// (which is only possible if all operands to the PHI are constants).
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Instruction *FoldOpIntoPhi(Instruction &I);
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// FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
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// operator and they all are only used by the PHI, PHI together their
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// inputs, and do the operation once, to the result of the PHI.
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Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
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Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN);
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Instruction *FoldPHIArgGEPIntoPHI(PHINode &PN);
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Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS,
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ConstantInt *AndRHS, BinaryOperator &TheAnd);
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Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask,
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bool isSub, Instruction &I);
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Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
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bool isSigned, bool Inside, Instruction &IB);
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Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocationInst &AI);
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Instruction *MatchBSwap(BinaryOperator &I);
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bool SimplifyStoreAtEndOfBlock(StoreInst &SI);
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Instruction *SimplifyMemTransfer(MemIntrinsic *MI);
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Instruction *SimplifyMemSet(MemSetInst *MI);
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|
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Value *EvaluateInDifferentType(Value *V, const Type *Ty, bool isSigned);
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|
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bool CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
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unsigned CastOpc, int &NumCastsRemoved);
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unsigned GetOrEnforceKnownAlignment(Value *V,
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unsigned PrefAlign = 0);
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};
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}
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char InstCombiner::ID = 0;
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static RegisterPass<InstCombiner>
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X("instcombine", "Combine redundant instructions");
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// getComplexity: Assign a complexity or rank value to LLVM Values...
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// 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst
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static unsigned getComplexity(Value *V) {
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if (isa<Instruction>(V)) {
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if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V))
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return 3;
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return 4;
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}
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if (isa<Argument>(V)) return 3;
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return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
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}
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// isOnlyUse - Return true if this instruction will be deleted if we stop using
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// it.
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static bool isOnlyUse(Value *V) {
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return V->hasOneUse() || isa<Constant>(V);
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}
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// getPromotedType - Return the specified type promoted as it would be to pass
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// though a va_arg area...
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static const Type *getPromotedType(const Type *Ty) {
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if (const IntegerType* ITy = dyn_cast<IntegerType>(Ty)) {
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if (ITy->getBitWidth() < 32)
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return Type::Int32Ty;
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}
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return Ty;
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}
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/// getBitCastOperand - If the specified operand is a CastInst, a constant
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/// expression bitcast, or a GetElementPtrInst with all zero indices, return the
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/// operand value, otherwise return null.
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static Value *getBitCastOperand(Value *V) {
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if (BitCastInst *I = dyn_cast<BitCastInst>(V))
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// BitCastInst?
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return I->getOperand(0);
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else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V)) {
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// GetElementPtrInst?
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if (GEP->hasAllZeroIndices())
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return GEP->getOperand(0);
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} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
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if (CE->getOpcode() == Instruction::BitCast)
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// BitCast ConstantExp?
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return CE->getOperand(0);
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else if (CE->getOpcode() == Instruction::GetElementPtr) {
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// GetElementPtr ConstantExp?
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for (User::op_iterator I = CE->op_begin() + 1, E = CE->op_end();
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I != E; ++I) {
|
|
ConstantInt *CI = dyn_cast<ConstantInt>(I);
|
|
if (!CI || !CI->isZero())
|
|
// Any non-zero indices? Not cast-like.
|
|
return 0;
|
|
}
|
|
// All-zero indices? This is just like casting.
|
|
return CE->getOperand(0);
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/// This function is a wrapper around CastInst::isEliminableCastPair. It
|
|
/// simply extracts arguments and returns what that function returns.
|
|
static Instruction::CastOps
|
|
isEliminableCastPair(
|
|
const CastInst *CI, ///< The first cast instruction
|
|
unsigned opcode, ///< The opcode of the second cast instruction
|
|
const Type *DstTy, ///< The target type for the second cast instruction
|
|
TargetData *TD ///< The target data for pointer size
|
|
) {
|
|
|
|
const Type *SrcTy = CI->getOperand(0)->getType(); // A from above
|
|
const Type *MidTy = CI->getType(); // B from above
|
|
|
|
// Get the opcodes of the two Cast instructions
|
|
Instruction::CastOps firstOp = Instruction::CastOps(CI->getOpcode());
|
|
Instruction::CastOps secondOp = Instruction::CastOps(opcode);
|
|
|
|
return Instruction::CastOps(
|
|
CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy,
|
|
DstTy, TD->getIntPtrType()));
|
|
}
|
|
|
|
/// ValueRequiresCast - Return true if the cast from "V to Ty" actually results
|
|
/// in any code being generated. It does not require codegen if V is simple
|
|
/// enough or if the cast can be folded into other casts.
|
|
static bool ValueRequiresCast(Instruction::CastOps opcode, const Value *V,
|
|
const Type *Ty, TargetData *TD) {
|
|
if (V->getType() == Ty || isa<Constant>(V)) return false;
|
|
|
|
// If this is another cast that can be eliminated, it isn't codegen either.
|
|
if (const CastInst *CI = dyn_cast<CastInst>(V))
|
|
if (isEliminableCastPair(CI, opcode, Ty, TD))
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
// SimplifyCommutative - This performs a few simplifications for commutative
|
|
// operators:
|
|
//
|
|
// 1. Order operands such that they are listed from right (least complex) to
|
|
// left (most complex). This puts constants before unary operators before
|
|
// binary operators.
|
|
//
|
|
// 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
|
|
// 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
|
|
//
|
|
bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
|
|
bool Changed = false;
|
|
if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
|
|
Changed = !I.swapOperands();
|
|
|
|
if (!I.isAssociative()) return Changed;
|
|
Instruction::BinaryOps Opcode = I.getOpcode();
|
|
if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
|
|
if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
|
|
if (isa<Constant>(I.getOperand(1))) {
|
|
Constant *Folded = ConstantExpr::get(I.getOpcode(),
|
|
cast<Constant>(I.getOperand(1)),
|
|
cast<Constant>(Op->getOperand(1)));
|
|
I.setOperand(0, Op->getOperand(0));
|
|
I.setOperand(1, Folded);
|
|
return true;
|
|
} else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
|
|
if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
|
|
isOnlyUse(Op) && isOnlyUse(Op1)) {
|
|
Constant *C1 = cast<Constant>(Op->getOperand(1));
|
|
Constant *C2 = cast<Constant>(Op1->getOperand(1));
|
|
|
|
// Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
|
|
Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
|
|
Instruction *New = BinaryOperator::Create(Opcode, Op->getOperand(0),
|
|
Op1->getOperand(0),
|
|
Op1->getName(), &I);
|
|
AddToWorkList(New);
|
|
I.setOperand(0, New);
|
|
I.setOperand(1, Folded);
|
|
return true;
|
|
}
|
|
}
|
|
return Changed;
|
|
}
|
|
|
|
/// SimplifyCompare - For a CmpInst this function just orders the operands
|
|
/// so that theyare listed from right (least complex) to left (most complex).
|
|
/// This puts constants before unary operators before binary operators.
|
|
bool InstCombiner::SimplifyCompare(CmpInst &I) {
|
|
if (getComplexity(I.getOperand(0)) >= getComplexity(I.getOperand(1)))
|
|
return false;
|
|
I.swapOperands();
|
|
// Compare instructions are not associative so there's nothing else we can do.
|
|
return true;
|
|
}
|
|
|
|
// dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
|
|
// if the LHS is a constant zero (which is the 'negate' form).
|
|
//
|
|
static inline Value *dyn_castNegVal(Value *V) {
|
|
if (BinaryOperator::isNeg(V))
|
|
return BinaryOperator::getNegArgument(V);
|
|
|
|
// Constants can be considered to be negated values if they can be folded.
|
|
if (ConstantInt *C = dyn_cast<ConstantInt>(V))
|
|
return ConstantExpr::getNeg(C);
|
|
|
|
if (ConstantVector *C = dyn_cast<ConstantVector>(V))
|
|
if (C->getType()->getElementType()->isInteger())
|
|
return ConstantExpr::getNeg(C);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static inline Value *dyn_castNotVal(Value *V) {
|
|
if (BinaryOperator::isNot(V))
|
|
return BinaryOperator::getNotArgument(V);
|
|
|
|
// Constants can be considered to be not'ed values...
|
|
if (ConstantInt *C = dyn_cast<ConstantInt>(V))
|
|
return ConstantInt::get(~C->getValue());
|
|
return 0;
|
|
}
|
|
|
|
// dyn_castFoldableMul - If this value is a multiply that can be folded into
|
|
// other computations (because it has a constant operand), return the
|
|
// non-constant operand of the multiply, and set CST to point to the multiplier.
|
|
// Otherwise, return null.
|
|
//
|
|
static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
|
|
if (V->hasOneUse() && V->getType()->isInteger())
|
|
if (Instruction *I = dyn_cast<Instruction>(V)) {
|
|
if (I->getOpcode() == Instruction::Mul)
|
|
if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
|
|
return I->getOperand(0);
|
|
if (I->getOpcode() == Instruction::Shl)
|
|
if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
|
|
// The multiplier is really 1 << CST.
|
|
uint32_t BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
|
|
uint32_t CSTVal = CST->getLimitedValue(BitWidth);
|
|
CST = ConstantInt::get(APInt(BitWidth, 1).shl(CSTVal));
|
|
return I->getOperand(0);
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/// dyn_castGetElementPtr - If this is a getelementptr instruction or constant
|
|
/// expression, return it.
|
|
static User *dyn_castGetElementPtr(Value *V) {
|
|
if (isa<GetElementPtrInst>(V)) return cast<User>(V);
|
|
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
|
|
if (CE->getOpcode() == Instruction::GetElementPtr)
|
|
return cast<User>(V);
|
|
return false;
|
|
}
|
|
|
|
/// getOpcode - If this is an Instruction or a ConstantExpr, return the
|
|
/// opcode value. Otherwise return UserOp1.
|
|
static unsigned getOpcode(const Value *V) {
|
|
if (const Instruction *I = dyn_cast<Instruction>(V))
|
|
return I->getOpcode();
|
|
if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
|
|
return CE->getOpcode();
|
|
// Use UserOp1 to mean there's no opcode.
|
|
return Instruction::UserOp1;
|
|
}
|
|
|
|
/// AddOne - Add one to a ConstantInt
|
|
static ConstantInt *AddOne(ConstantInt *C) {
|
|
APInt Val(C->getValue());
|
|
return ConstantInt::get(++Val);
|
|
}
|
|
/// SubOne - Subtract one from a ConstantInt
|
|
static ConstantInt *SubOne(ConstantInt *C) {
|
|
APInt Val(C->getValue());
|
|
return ConstantInt::get(--Val);
|
|
}
|
|
/// Add - Add two ConstantInts together
|
|
static ConstantInt *Add(ConstantInt *C1, ConstantInt *C2) {
|
|
return ConstantInt::get(C1->getValue() + C2->getValue());
|
|
}
|
|
/// And - Bitwise AND two ConstantInts together
|
|
static ConstantInt *And(ConstantInt *C1, ConstantInt *C2) {
|
|
return ConstantInt::get(C1->getValue() & C2->getValue());
|
|
}
|
|
/// Subtract - Subtract one ConstantInt from another
|
|
static ConstantInt *Subtract(ConstantInt *C1, ConstantInt *C2) {
|
|
return ConstantInt::get(C1->getValue() - C2->getValue());
|
|
}
|
|
/// Multiply - Multiply two ConstantInts together
|
|
static ConstantInt *Multiply(ConstantInt *C1, ConstantInt *C2) {
|
|
return ConstantInt::get(C1->getValue() * C2->getValue());
|
|
}
|
|
/// MultiplyOverflows - True if the multiply can not be expressed in an int
|
|
/// this size.
|
|
static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) {
|
|
uint32_t W = C1->getBitWidth();
|
|
APInt LHSExt = C1->getValue(), RHSExt = C2->getValue();
|
|
if (sign) {
|
|
LHSExt.sext(W * 2);
|
|
RHSExt.sext(W * 2);
|
|
} else {
|
|
LHSExt.zext(W * 2);
|
|
RHSExt.zext(W * 2);
|
|
}
|
|
|
|
APInt MulExt = LHSExt * RHSExt;
|
|
|
|
if (sign) {
|
|
APInt Min = APInt::getSignedMinValue(W).sext(W * 2);
|
|
APInt Max = APInt::getSignedMaxValue(W).sext(W * 2);
|
|
return MulExt.slt(Min) || MulExt.sgt(Max);
|
|
} else
|
|
return MulExt.ugt(APInt::getLowBitsSet(W * 2, W));
|
|
}
|
|
|
|
|
|
/// ShrinkDemandedConstant - Check to see if the specified operand of the
|
|
/// specified instruction is a constant integer. If so, check to see if there
|
|
/// are any bits set in the constant that are not demanded. If so, shrink the
|
|
/// constant and return true.
|
|
static bool ShrinkDemandedConstant(Instruction *I, unsigned OpNo,
|
|
APInt Demanded) {
|
|
assert(I && "No instruction?");
|
|
assert(OpNo < I->getNumOperands() && "Operand index too large");
|
|
|
|
// If the operand is not a constant integer, nothing to do.
|
|
ConstantInt *OpC = dyn_cast<ConstantInt>(I->getOperand(OpNo));
|
|
if (!OpC) return false;
|
|
|
|
// If there are no bits set that aren't demanded, nothing to do.
|
|
Demanded.zextOrTrunc(OpC->getValue().getBitWidth());
|
|
if ((~Demanded & OpC->getValue()) == 0)
|
|
return false;
|
|
|
|
// This instruction is producing bits that are not demanded. Shrink the RHS.
|
|
Demanded &= OpC->getValue();
|
|
I->setOperand(OpNo, ConstantInt::get(Demanded));
|
|
return true;
|
|
}
|
|
|
|
// ComputeSignedMinMaxValuesFromKnownBits - Given a signed integer type and a
|
|
// set of known zero and one bits, compute the maximum and minimum values that
|
|
// could have the specified known zero and known one bits, returning them in
|
|
// min/max.
|
|
static void ComputeSignedMinMaxValuesFromKnownBits(const Type *Ty,
|
|
const APInt& KnownZero,
|
|
const APInt& KnownOne,
|
|
APInt& Min, APInt& Max) {
|
|
uint32_t BitWidth = cast<IntegerType>(Ty)->getBitWidth();
|
|
assert(KnownZero.getBitWidth() == BitWidth &&
|
|
KnownOne.getBitWidth() == BitWidth &&
|
|
Min.getBitWidth() == BitWidth && Max.getBitWidth() == BitWidth &&
|
|
"Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth.");
|
|
APInt UnknownBits = ~(KnownZero|KnownOne);
|
|
|
|
// The minimum value is when all unknown bits are zeros, EXCEPT for the sign
|
|
// bit if it is unknown.
|
|
Min = KnownOne;
|
|
Max = KnownOne|UnknownBits;
|
|
|
|
if (UnknownBits[BitWidth-1]) { // Sign bit is unknown
|
|
Min.set(BitWidth-1);
|
|
Max.clear(BitWidth-1);
|
|
}
|
|
}
|
|
|
|
// ComputeUnsignedMinMaxValuesFromKnownBits - Given an unsigned integer type and
|
|
// a set of known zero and one bits, compute the maximum and minimum values that
|
|
// could have the specified known zero and known one bits, returning them in
|
|
// min/max.
|
|
static void ComputeUnsignedMinMaxValuesFromKnownBits(const Type *Ty,
|
|
const APInt &KnownZero,
|
|
const APInt &KnownOne,
|
|
APInt &Min, APInt &Max) {
|
|
uint32_t BitWidth = cast<IntegerType>(Ty)->getBitWidth(); BitWidth = BitWidth;
|
|
assert(KnownZero.getBitWidth() == BitWidth &&
|
|
KnownOne.getBitWidth() == BitWidth &&
|
|
Min.getBitWidth() == BitWidth && Max.getBitWidth() &&
|
|
"Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth.");
|
|
APInt UnknownBits = ~(KnownZero|KnownOne);
|
|
|
|
// The minimum value is when the unknown bits are all zeros.
|
|
Min = KnownOne;
|
|
// The maximum value is when the unknown bits are all ones.
|
|
Max = KnownOne|UnknownBits;
|
|
}
|
|
|
|
/// SimplifyDemandedInstructionBits - Inst is an integer instruction that
|
|
/// SimplifyDemandedBits knows about. See if the instruction has any
|
|
/// properties that allow us to simplify its operands.
|
|
bool InstCombiner::SimplifyDemandedInstructionBits(Instruction &Inst) {
|
|
unsigned BitWidth = cast<IntegerType>(Inst.getType())->getBitWidth();
|
|
APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
|
|
APInt DemandedMask(APInt::getAllOnesValue(BitWidth));
|
|
|
|
Value *V = SimplifyDemandedUseBits(&Inst, DemandedMask,
|
|
KnownZero, KnownOne, 0);
|
|
if (V == 0) return false;
|
|
if (V == &Inst) return true;
|
|
ReplaceInstUsesWith(Inst, V);
|
|
return true;
|
|
}
|
|
|
|
/// SimplifyDemandedBits - This form of SimplifyDemandedBits simplifies the
|
|
/// specified instruction operand if possible, updating it in place. It returns
|
|
/// true if it made any change and false otherwise.
|
|
bool InstCombiner::SimplifyDemandedBits(Use &U, APInt DemandedMask,
|
|
APInt &KnownZero, APInt &KnownOne,
|
|
unsigned Depth) {
|
|
Value *NewVal = SimplifyDemandedUseBits(U.get(), DemandedMask,
|
|
KnownZero, KnownOne, Depth);
|
|
if (NewVal == 0) return false;
|
|
U.set(NewVal);
|
|
return true;
|
|
}
|
|
|
|
|
|
/// SimplifyDemandedUseBits - This function attempts to replace V with a simpler
|
|
/// value based on the demanded bits. When this function is called, it is known
|
|
/// that only the bits set in DemandedMask of the result of V are ever used
|
|
/// downstream. Consequently, depending on the mask and V, it may be possible
|
|
/// to replace V with a constant or one of its operands. In such cases, this
|
|
/// function does the replacement and returns true. In all other cases, it
|
|
/// returns false after analyzing the expression and setting KnownOne and known
|
|
/// to be one in the expression. KnownZero contains all the bits that are known
|
|
/// to be zero in the expression. These are provided to potentially allow the
|
|
/// caller (which might recursively be SimplifyDemandedBits itself) to simplify
|
|
/// the expression. KnownOne and KnownZero always follow the invariant that
|
|
/// KnownOne & KnownZero == 0. That is, a bit can't be both 1 and 0. Note that
|
|
/// the bits in KnownOne and KnownZero may only be accurate for those bits set
|
|
/// in DemandedMask. Note also that the bitwidth of V, DemandedMask, KnownZero
|
|
/// and KnownOne must all be the same.
|
|
///
|
|
/// This returns null if it did not change anything and it permits no
|
|
/// simplification. This returns V itself if it did some simplification of V's
|
|
/// operands based on the information about what bits are demanded. This returns
|
|
/// some other non-null value if it found out that V is equal to another value
|
|
/// in the context where the specified bits are demanded, but not for all users.
|
|
Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
|
|
APInt &KnownZero, APInt &KnownOne,
|
|
unsigned Depth) {
|
|
assert(V != 0 && "Null pointer of Value???");
|
|
assert(Depth <= 6 && "Limit Search Depth");
|
|
uint32_t BitWidth = DemandedMask.getBitWidth();
|
|
const IntegerType *VTy = cast<IntegerType>(V->getType());
|
|
assert(VTy->getBitWidth() == BitWidth &&
|
|
KnownZero.getBitWidth() == BitWidth &&
|
|
KnownOne.getBitWidth() == BitWidth &&
|
|
"Value *V, DemandedMask, KnownZero and KnownOne \
|
|
must have same BitWidth");
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
|
|
// We know all of the bits for a constant!
|
|
KnownOne = CI->getValue() & DemandedMask;
|
|
KnownZero = ~KnownOne & DemandedMask;
|
|
return 0;
|
|
}
|
|
|
|
KnownZero.clear();
|
|
KnownOne.clear();
|
|
if (DemandedMask == 0) { // Not demanding any bits from V.
|
|
if (isa<UndefValue>(V))
|
|
return 0;
|
|
return UndefValue::get(VTy);
|
|
}
|
|
|
|
if (Depth == 6) // Limit search depth.
|
|
return 0;
|
|
|
|
Instruction *I = dyn_cast<Instruction>(V);
|
|
if (!I) return 0; // Only analyze instructions.
|
|
|
|
APInt LHSKnownZero(BitWidth, 0), LHSKnownOne(BitWidth, 0);
|
|
APInt &RHSKnownZero = KnownZero, &RHSKnownOne = KnownOne;
|
|
|
|
// If there are multiple uses of this value and we aren't at the root, then
|
|
// we can't do any simplifications of the operands, because DemandedMask
|
|
// only reflects the bits demanded by *one* of the users.
|
|
if (Depth != 0 && !I->hasOneUse()) {
|
|
// Despite the fact that we can't simplify this instruction in all User's
|
|
// context, we can at least compute the knownzero/knownone bits, and we can
|
|
// do simplifications that apply to *just* the one user if we know that
|
|
// this instruction has a simpler value in that context.
|
|
if (I->getOpcode() == Instruction::And) {
|
|
// If either the LHS or the RHS are Zero, the result is zero.
|
|
ComputeMaskedBits(I->getOperand(1), DemandedMask,
|
|
RHSKnownZero, RHSKnownOne, Depth+1);
|
|
ComputeMaskedBits(I->getOperand(0), DemandedMask & ~RHSKnownZero,
|
|
LHSKnownZero, LHSKnownOne, Depth+1);
|
|
|
|
// If all of the demanded bits are known 1 on one side, return the other.
|
|
// These bits cannot contribute to the result of the 'and' in this
|
|
// context.
|
|
if ((DemandedMask & ~LHSKnownZero & RHSKnownOne) ==
|
|
(DemandedMask & ~LHSKnownZero))
|
|
return I->getOperand(0);
|
|
if ((DemandedMask & ~RHSKnownZero & LHSKnownOne) ==
|
|
(DemandedMask & ~RHSKnownZero))
|
|
return I->getOperand(1);
|
|
|
|
// If all of the demanded bits in the inputs are known zeros, return zero.
|
|
if ((DemandedMask & (RHSKnownZero|LHSKnownZero)) == DemandedMask)
|
|
return Constant::getNullValue(VTy);
|
|
|
|
} else if (I->getOpcode() == Instruction::Or) {
|
|
// We can simplify (X|Y) -> X or Y in the user's context if we know that
|
|
// only bits from X or Y are demanded.
|
|
|
|
// If either the LHS or the RHS are One, the result is One.
|
|
ComputeMaskedBits(I->getOperand(1), DemandedMask,
|
|
RHSKnownZero, RHSKnownOne, Depth+1);
|
|
ComputeMaskedBits(I->getOperand(0), DemandedMask & ~RHSKnownOne,
|
|
LHSKnownZero, LHSKnownOne, Depth+1);
|
|
|
|
// If all of the demanded bits are known zero on one side, return the
|
|
// other. These bits cannot contribute to the result of the 'or' in this
|
|
// context.
|
|
if ((DemandedMask & ~LHSKnownOne & RHSKnownZero) ==
|
|
(DemandedMask & ~LHSKnownOne))
|
|
return I->getOperand(0);
|
|
if ((DemandedMask & ~RHSKnownOne & LHSKnownZero) ==
|
|
(DemandedMask & ~RHSKnownOne))
|
|
return I->getOperand(1);
|
|
|
|
// If all of the potentially set bits on one side are known to be set on
|
|
// the other side, just use the 'other' side.
|
|
if ((DemandedMask & (~RHSKnownZero) & LHSKnownOne) ==
|
|
(DemandedMask & (~RHSKnownZero)))
|
|
return I->getOperand(0);
|
|
if ((DemandedMask & (~LHSKnownZero) & RHSKnownOne) ==
|
|
(DemandedMask & (~LHSKnownZero)))
|
|
return I->getOperand(1);
|
|
}
|
|
|
|
// Compute the KnownZero/KnownOne bits to simplify things downstream.
|
|
ComputeMaskedBits(I, DemandedMask, KnownZero, KnownOne, Depth);
|
|
return 0;
|
|
}
|
|
|
|
// If this is the root being simplified, allow it to have multiple uses,
|
|
// just set the DemandedMask to all bits so that we can try to simplify the
|
|
// operands. This allows visitTruncInst (for example) to simplify the
|
|
// operand of a trunc without duplicating all the logic below.
|
|
if (Depth == 0 && !V->hasOneUse())
|
|
DemandedMask = APInt::getAllOnesValue(BitWidth);
|
|
|
|
switch (I->getOpcode()) {
|
|
default:
|
|
ComputeMaskedBits(I, DemandedMask, RHSKnownZero, RHSKnownOne, Depth);
|
|
break;
|
|
case Instruction::And:
|
|
// If either the LHS or the RHS are Zero, the result is zero.
|
|
if (SimplifyDemandedBits(I->getOperandUse(1), DemandedMask,
|
|
RHSKnownZero, RHSKnownOne, Depth+1) ||
|
|
SimplifyDemandedBits(I->getOperandUse(0), DemandedMask & ~RHSKnownZero,
|
|
LHSKnownZero, LHSKnownOne, Depth+1))
|
|
return I;
|
|
assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
|
|
assert(!(LHSKnownZero & LHSKnownOne) && "Bits known to be one AND zero?");
|
|
|
|
// If all of the demanded bits are known 1 on one side, return the other.
|
|
// These bits cannot contribute to the result of the 'and'.
|
|
if ((DemandedMask & ~LHSKnownZero & RHSKnownOne) ==
|
|
(DemandedMask & ~LHSKnownZero))
|
|
return I->getOperand(0);
|
|
if ((DemandedMask & ~RHSKnownZero & LHSKnownOne) ==
|
|
(DemandedMask & ~RHSKnownZero))
|
|
return I->getOperand(1);
|
|
|
|
// If all of the demanded bits in the inputs are known zeros, return zero.
|
|
if ((DemandedMask & (RHSKnownZero|LHSKnownZero)) == DemandedMask)
|
|
return Constant::getNullValue(VTy);
|
|
|
|
// If the RHS is a constant, see if we can simplify it.
|
|
if (ShrinkDemandedConstant(I, 1, DemandedMask & ~LHSKnownZero))
|
|
return I;
|
|
|
|
// Output known-1 bits are only known if set in both the LHS & RHS.
|
|
RHSKnownOne &= LHSKnownOne;
|
|
// Output known-0 are known to be clear if zero in either the LHS | RHS.
|
|
RHSKnownZero |= LHSKnownZero;
|
|
break;
|
|
case Instruction::Or:
|
|
// If either the LHS or the RHS are One, the result is One.
|
|
if (SimplifyDemandedBits(I->getOperandUse(1), DemandedMask,
|
|
RHSKnownZero, RHSKnownOne, Depth+1) ||
|
|
SimplifyDemandedBits(I->getOperandUse(0), DemandedMask & ~RHSKnownOne,
|
|
LHSKnownZero, LHSKnownOne, Depth+1))
|
|
return I;
|
|
assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
|
|
assert(!(LHSKnownZero & LHSKnownOne) && "Bits known to be one AND zero?");
|
|
|
|
// If all of the demanded bits are known zero on one side, return the other.
|
|
// These bits cannot contribute to the result of the 'or'.
|
|
if ((DemandedMask & ~LHSKnownOne & RHSKnownZero) ==
|
|
(DemandedMask & ~LHSKnownOne))
|
|
return I->getOperand(0);
|
|
if ((DemandedMask & ~RHSKnownOne & LHSKnownZero) ==
|
|
(DemandedMask & ~RHSKnownOne))
|
|
return I->getOperand(1);
|
|
|
|
// If all of the potentially set bits on one side are known to be set on
|
|
// the other side, just use the 'other' side.
|
|
if ((DemandedMask & (~RHSKnownZero) & LHSKnownOne) ==
|
|
(DemandedMask & (~RHSKnownZero)))
|
|
return I->getOperand(0);
|
|
if ((DemandedMask & (~LHSKnownZero) & RHSKnownOne) ==
|
|
(DemandedMask & (~LHSKnownZero)))
|
|
return I->getOperand(1);
|
|
|
|
// If the RHS is a constant, see if we can simplify it.
|
|
if (ShrinkDemandedConstant(I, 1, DemandedMask))
|
|
return I;
|
|
|
|
// Output known-0 bits are only known if clear in both the LHS & RHS.
|
|
RHSKnownZero &= LHSKnownZero;
|
|
// Output known-1 are known to be set if set in either the LHS | RHS.
|
|
RHSKnownOne |= LHSKnownOne;
|
|
break;
|
|
case Instruction::Xor: {
|
|
if (SimplifyDemandedBits(I->getOperandUse(1), DemandedMask,
|
|
RHSKnownZero, RHSKnownOne, Depth+1) ||
|
|
SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
|
|
LHSKnownZero, LHSKnownOne, Depth+1))
|
|
return I;
|
|
assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
|
|
assert(!(LHSKnownZero & LHSKnownOne) && "Bits known to be one AND zero?");
|
|
|
|
// If all of the demanded bits are known zero on one side, return the other.
|
|
// These bits cannot contribute to the result of the 'xor'.
|
|
if ((DemandedMask & RHSKnownZero) == DemandedMask)
|
|
return I->getOperand(0);
|
|
if ((DemandedMask & LHSKnownZero) == DemandedMask)
|
|
return I->getOperand(1);
|
|
|
|
// Output known-0 bits are known if clear or set in both the LHS & RHS.
|
|
APInt KnownZeroOut = (RHSKnownZero & LHSKnownZero) |
|
|
(RHSKnownOne & LHSKnownOne);
|
|
// Output known-1 are known to be set if set in only one of the LHS, RHS.
|
|
APInt KnownOneOut = (RHSKnownZero & LHSKnownOne) |
|
|
(RHSKnownOne & LHSKnownZero);
|
|
|
|
// If all of the demanded bits are known to be zero on one side or the
|
|
// other, turn this into an *inclusive* or.
|
|
// e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
|
|
if ((DemandedMask & ~RHSKnownZero & ~LHSKnownZero) == 0) {
|
|
Instruction *Or =
|
|
BinaryOperator::CreateOr(I->getOperand(0), I->getOperand(1),
|
|
I->getName());
|
|
return InsertNewInstBefore(Or, *I);
|
|
}
|
|
|
|
// If all of the demanded bits on one side are known, and all of the set
|
|
// bits on that side are also known to be set on the other side, turn this
|
|
// into an AND, as we know the bits will be cleared.
|
|
// e.g. (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
|
|
if ((DemandedMask & (RHSKnownZero|RHSKnownOne)) == DemandedMask) {
|
|
// all known
|
|
if ((RHSKnownOne & LHSKnownOne) == RHSKnownOne) {
|
|
Constant *AndC = ConstantInt::get(~RHSKnownOne & DemandedMask);
|
|
Instruction *And =
|
|
BinaryOperator::CreateAnd(I->getOperand(0), AndC, "tmp");
|
|
return InsertNewInstBefore(And, *I);
|
|
}
|
|
}
|
|
|
|
// If the RHS is a constant, see if we can simplify it.
|
|
// FIXME: for XOR, we prefer to force bits to 1 if they will make a -1.
|
|
if (ShrinkDemandedConstant(I, 1, DemandedMask))
|
|
return I;
|
|
|
|
RHSKnownZero = KnownZeroOut;
|
|
RHSKnownOne = KnownOneOut;
|
|
break;
|
|
}
|
|
case Instruction::Select:
|
|
if (SimplifyDemandedBits(I->getOperandUse(2), DemandedMask,
|
|
RHSKnownZero, RHSKnownOne, Depth+1) ||
|
|
SimplifyDemandedBits(I->getOperandUse(1), DemandedMask,
|
|
LHSKnownZero, LHSKnownOne, Depth+1))
|
|
return I;
|
|
assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
|
|
assert(!(LHSKnownZero & LHSKnownOne) && "Bits known to be one AND zero?");
|
|
|
|
// If the operands are constants, see if we can simplify them.
|
|
if (ShrinkDemandedConstant(I, 1, DemandedMask) ||
|
|
ShrinkDemandedConstant(I, 2, DemandedMask))
|
|
return I;
|
|
|
|
// Only known if known in both the LHS and RHS.
|
|
RHSKnownOne &= LHSKnownOne;
|
|
RHSKnownZero &= LHSKnownZero;
|
|
break;
|
|
case Instruction::Trunc: {
|
|
unsigned truncBf = I->getOperand(0)->getType()->getPrimitiveSizeInBits();
|
|
DemandedMask.zext(truncBf);
|
|
RHSKnownZero.zext(truncBf);
|
|
RHSKnownOne.zext(truncBf);
|
|
if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
|
|
RHSKnownZero, RHSKnownOne, Depth+1))
|
|
return I;
|
|
DemandedMask.trunc(BitWidth);
|
|
RHSKnownZero.trunc(BitWidth);
|
|
RHSKnownOne.trunc(BitWidth);
|
|
assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
|
|
break;
|
|
}
|
|
case Instruction::BitCast:
|
|
if (!I->getOperand(0)->getType()->isInteger())
|
|
return false; // vector->int or fp->int?
|
|
if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
|
|
RHSKnownZero, RHSKnownOne, Depth+1))
|
|
return I;
|
|
assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
|
|
break;
|
|
case Instruction::ZExt: {
|
|
// Compute the bits in the result that are not present in the input.
|
|
unsigned SrcBitWidth =I->getOperand(0)->getType()->getPrimitiveSizeInBits();
|
|
|
|
DemandedMask.trunc(SrcBitWidth);
|
|
RHSKnownZero.trunc(SrcBitWidth);
|
|
RHSKnownOne.trunc(SrcBitWidth);
|
|
if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
|
|
RHSKnownZero, RHSKnownOne, Depth+1))
|
|
return I;
|
|
DemandedMask.zext(BitWidth);
|
|
RHSKnownZero.zext(BitWidth);
|
|
RHSKnownOne.zext(BitWidth);
|
|
assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
|
|
// The top bits are known to be zero.
|
|
RHSKnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth);
|
|
break;
|
|
}
|
|
case Instruction::SExt: {
|
|
// Compute the bits in the result that are not present in the input.
|
|
unsigned SrcBitWidth =I->getOperand(0)->getType()->getPrimitiveSizeInBits();
|
|
|
|
APInt InputDemandedBits = DemandedMask &
|
|
APInt::getLowBitsSet(BitWidth, SrcBitWidth);
|
|
|
|
APInt NewBits(APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth));
|
|
// If any of the sign extended bits are demanded, we know that the sign
|
|
// bit is demanded.
|
|
if ((NewBits & DemandedMask) != 0)
|
|
InputDemandedBits.set(SrcBitWidth-1);
|
|
|
|
InputDemandedBits.trunc(SrcBitWidth);
|
|
RHSKnownZero.trunc(SrcBitWidth);
|
|
RHSKnownOne.trunc(SrcBitWidth);
|
|
if (SimplifyDemandedBits(I->getOperandUse(0), InputDemandedBits,
|
|
RHSKnownZero, RHSKnownOne, Depth+1))
|
|
return I;
|
|
InputDemandedBits.zext(BitWidth);
|
|
RHSKnownZero.zext(BitWidth);
|
|
RHSKnownOne.zext(BitWidth);
|
|
assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
|
|
|
|
// If the sign bit of the input is known set or clear, then we know the
|
|
// top bits of the result.
|
|
|
|
// If the input sign bit is known zero, or if the NewBits are not demanded
|
|
// convert this into a zero extension.
|
|
if (RHSKnownZero[SrcBitWidth-1] || (NewBits & ~DemandedMask) == NewBits) {
|
|
// Convert to ZExt cast
|
|
CastInst *NewCast = new ZExtInst(I->getOperand(0), VTy, I->getName());
|
|
return InsertNewInstBefore(NewCast, *I);
|
|
} else if (RHSKnownOne[SrcBitWidth-1]) { // Input sign bit known set
|
|
RHSKnownOne |= NewBits;
|
|
}
|
|
break;
|
|
}
|
|
case Instruction::Add: {
|
|
// Figure out what the input bits are. If the top bits of the and result
|
|
// are not demanded, then the add doesn't demand them from its input
|
|
// either.
|
|
unsigned NLZ = DemandedMask.countLeadingZeros();
|
|
|
|
// If there is a constant on the RHS, there are a variety of xformations
|
|
// we can do.
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
|
|
// If null, this should be simplified elsewhere. Some of the xforms here
|
|
// won't work if the RHS is zero.
|
|
if (RHS->isZero())
|
|
break;
|
|
|
|
// If the top bit of the output is demanded, demand everything from the
|
|
// input. Otherwise, we demand all the input bits except NLZ top bits.
|
|
APInt InDemandedBits(APInt::getLowBitsSet(BitWidth, BitWidth - NLZ));
|
|
|
|
// Find information about known zero/one bits in the input.
|
|
if (SimplifyDemandedBits(I->getOperandUse(0), InDemandedBits,
|
|
LHSKnownZero, LHSKnownOne, Depth+1))
|
|
return I;
|
|
|
|
// If the RHS of the add has bits set that can't affect the input, reduce
|
|
// the constant.
|
|
if (ShrinkDemandedConstant(I, 1, InDemandedBits))
|
|
return I;
|
|
|
|
// Avoid excess work.
|
|
if (LHSKnownZero == 0 && LHSKnownOne == 0)
|
|
break;
|
|
|
|
// Turn it into OR if input bits are zero.
|
|
if ((LHSKnownZero & RHS->getValue()) == RHS->getValue()) {
|
|
Instruction *Or =
|
|
BinaryOperator::CreateOr(I->getOperand(0), I->getOperand(1),
|
|
I->getName());
|
|
return InsertNewInstBefore(Or, *I);
|
|
}
|
|
|
|
// We can say something about the output known-zero and known-one bits,
|
|
// depending on potential carries from the input constant and the
|
|
// unknowns. For example if the LHS is known to have at most the 0x0F0F0
|
|
// bits set and the RHS constant is 0x01001, then we know we have a known
|
|
// one mask of 0x00001 and a known zero mask of 0xE0F0E.
|
|
|
|
// To compute this, we first compute the potential carry bits. These are
|
|
// the bits which may be modified. I'm not aware of a better way to do
|
|
// this scan.
|
|
const APInt &RHSVal = RHS->getValue();
|
|
APInt CarryBits((~LHSKnownZero + RHSVal) ^ (~LHSKnownZero ^ RHSVal));
|
|
|
|
// Now that we know which bits have carries, compute the known-1/0 sets.
|
|
|
|
// Bits are known one if they are known zero in one operand and one in the
|
|
// other, and there is no input carry.
|
|
RHSKnownOne = ((LHSKnownZero & RHSVal) |
|
|
(LHSKnownOne & ~RHSVal)) & ~CarryBits;
|
|
|
|
// Bits are known zero if they are known zero in both operands and there
|
|
// is no input carry.
|
|
RHSKnownZero = LHSKnownZero & ~RHSVal & ~CarryBits;
|
|
} else {
|
|
// If the high-bits of this ADD are not demanded, then it does not demand
|
|
// the high bits of its LHS or RHS.
|
|
if (DemandedMask[BitWidth-1] == 0) {
|
|
// Right fill the mask of bits for this ADD to demand the most
|
|
// significant bit and all those below it.
|
|
APInt DemandedFromOps(APInt::getLowBitsSet(BitWidth, BitWidth-NLZ));
|
|
if (SimplifyDemandedBits(I->getOperandUse(0), DemandedFromOps,
|
|
LHSKnownZero, LHSKnownOne, Depth+1) ||
|
|
SimplifyDemandedBits(I->getOperandUse(1), DemandedFromOps,
|
|
LHSKnownZero, LHSKnownOne, Depth+1))
|
|
return I;
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
case Instruction::Sub:
|
|
// If the high-bits of this SUB are not demanded, then it does not demand
|
|
// the high bits of its LHS or RHS.
|
|
if (DemandedMask[BitWidth-1] == 0) {
|
|
// Right fill the mask of bits for this SUB to demand the most
|
|
// significant bit and all those below it.
|
|
uint32_t NLZ = DemandedMask.countLeadingZeros();
|
|
APInt DemandedFromOps(APInt::getLowBitsSet(BitWidth, BitWidth-NLZ));
|
|
if (SimplifyDemandedBits(I->getOperandUse(0), DemandedFromOps,
|
|
LHSKnownZero, LHSKnownOne, Depth+1) ||
|
|
SimplifyDemandedBits(I->getOperandUse(1), DemandedFromOps,
|
|
LHSKnownZero, LHSKnownOne, Depth+1))
|
|
return I;
|
|
}
|
|
// Otherwise just hand the sub off to ComputeMaskedBits to fill in
|
|
// the known zeros and ones.
|
|
ComputeMaskedBits(V, DemandedMask, RHSKnownZero, RHSKnownOne, Depth);
|
|
break;
|
|
case Instruction::Shl:
|
|
if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
|
|
uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
|
|
APInt DemandedMaskIn(DemandedMask.lshr(ShiftAmt));
|
|
if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMaskIn,
|
|
RHSKnownZero, RHSKnownOne, Depth+1))
|
|
return I;
|
|
assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
|
|
RHSKnownZero <<= ShiftAmt;
|
|
RHSKnownOne <<= ShiftAmt;
|
|
// low bits known zero.
|
|
if (ShiftAmt)
|
|
RHSKnownZero |= APInt::getLowBitsSet(BitWidth, ShiftAmt);
|
|
}
|
|
break;
|
|
case Instruction::LShr:
|
|
// For a logical shift right
|
|
if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
|
|
uint64_t ShiftAmt = SA->getLimitedValue(BitWidth);
|
|
|
|
// Unsigned shift right.
|
|
APInt DemandedMaskIn(DemandedMask.shl(ShiftAmt));
|
|
if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMaskIn,
|
|
RHSKnownZero, RHSKnownOne, Depth+1))
|
|
return I;
|
|
assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
|
|
RHSKnownZero = APIntOps::lshr(RHSKnownZero, ShiftAmt);
|
|
RHSKnownOne = APIntOps::lshr(RHSKnownOne, ShiftAmt);
|
|
if (ShiftAmt) {
|
|
// Compute the new bits that are at the top now.
|
|
APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt));
|
|
RHSKnownZero |= HighBits; // high bits known zero.
|
|
}
|
|
}
|
|
break;
|
|
case Instruction::AShr:
|
|
// If this is an arithmetic shift right and only the low-bit is set, we can
|
|
// always convert this into a logical shr, even if the shift amount is
|
|
// variable. The low bit of the shift cannot be an input sign bit unless
|
|
// the shift amount is >= the size of the datatype, which is undefined.
|
|
if (DemandedMask == 1) {
|
|
// Perform the logical shift right.
|
|
Instruction *NewVal = BinaryOperator::CreateLShr(
|
|
I->getOperand(0), I->getOperand(1), I->getName());
|
|
return InsertNewInstBefore(NewVal, *I);
|
|
}
|
|
|
|
// If the sign bit is the only bit demanded by this ashr, then there is no
|
|
// need to do it, the shift doesn't change the high bit.
|
|
if (DemandedMask.isSignBit())
|
|
return I->getOperand(0);
|
|
|
|
if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
|
|
uint32_t ShiftAmt = SA->getLimitedValue(BitWidth);
|
|
|
|
// Signed shift right.
|
|
APInt DemandedMaskIn(DemandedMask.shl(ShiftAmt));
|
|
// If any of the "high bits" are demanded, we should set the sign bit as
|
|
// demanded.
|
|
if (DemandedMask.countLeadingZeros() <= ShiftAmt)
|
|
DemandedMaskIn.set(BitWidth-1);
|
|
if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMaskIn,
|
|
RHSKnownZero, RHSKnownOne, Depth+1))
|
|
return I;
|
|
assert(!(RHSKnownZero & RHSKnownOne) && "Bits known to be one AND zero?");
|
|
// Compute the new bits that are at the top now.
|
|
APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt));
|
|
RHSKnownZero = APIntOps::lshr(RHSKnownZero, ShiftAmt);
|
|
RHSKnownOne = APIntOps::lshr(RHSKnownOne, ShiftAmt);
|
|
|
|
// Handle the sign bits.
|
|
APInt SignBit(APInt::getSignBit(BitWidth));
|
|
// Adjust to where it is now in the mask.
|
|
SignBit = APIntOps::lshr(SignBit, ShiftAmt);
|
|
|
|
// If the input sign bit is known to be zero, or if none of the top bits
|
|
// are demanded, turn this into an unsigned shift right.
|
|
if (BitWidth <= ShiftAmt || RHSKnownZero[BitWidth-ShiftAmt-1] ||
|
|
(HighBits & ~DemandedMask) == HighBits) {
|
|
// Perform the logical shift right.
|
|
Instruction *NewVal = BinaryOperator::CreateLShr(
|
|
I->getOperand(0), SA, I->getName());
|
|
return InsertNewInstBefore(NewVal, *I);
|
|
} else if ((RHSKnownOne & SignBit) != 0) { // New bits are known one.
|
|
RHSKnownOne |= HighBits;
|
|
}
|
|
}
|
|
break;
|
|
case Instruction::SRem:
|
|
if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) {
|
|
APInt RA = Rem->getValue().abs();
|
|
if (RA.isPowerOf2()) {
|
|
if (DemandedMask.ule(RA)) // srem won't affect demanded bits
|
|
return I->getOperand(0);
|
|
|
|
APInt LowBits = RA - 1;
|
|
APInt Mask2 = LowBits | APInt::getSignBit(BitWidth);
|
|
if (SimplifyDemandedBits(I->getOperandUse(0), Mask2,
|
|
LHSKnownZero, LHSKnownOne, Depth+1))
|
|
return I;
|
|
|
|
if (LHSKnownZero[BitWidth-1] || ((LHSKnownZero & LowBits) == LowBits))
|
|
LHSKnownZero |= ~LowBits;
|
|
|
|
KnownZero |= LHSKnownZero & DemandedMask;
|
|
|
|
assert(!(KnownZero & KnownOne) && "Bits known to be one AND zero?");
|
|
}
|
|
}
|
|
break;
|
|
case Instruction::URem: {
|
|
APInt KnownZero2(BitWidth, 0), KnownOne2(BitWidth, 0);
|
|
APInt AllOnes = APInt::getAllOnesValue(BitWidth);
|
|
if (SimplifyDemandedBits(I->getOperandUse(0), AllOnes,
|
|
KnownZero2, KnownOne2, Depth+1) ||
|
|
SimplifyDemandedBits(I->getOperandUse(1), AllOnes,
|
|
KnownZero2, KnownOne2, Depth+1))
|
|
return I;
|
|
|
|
unsigned Leaders = KnownZero2.countLeadingOnes();
|
|
Leaders = std::max(Leaders,
|
|
KnownZero2.countLeadingOnes());
|
|
KnownZero = APInt::getHighBitsSet(BitWidth, Leaders) & DemandedMask;
|
|
break;
|
|
}
|
|
case Instruction::Call:
|
|
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
|
|
switch (II->getIntrinsicID()) {
|
|
default: break;
|
|
case Intrinsic::bswap: {
|
|
// If the only bits demanded come from one byte of the bswap result,
|
|
// just shift the input byte into position to eliminate the bswap.
|
|
unsigned NLZ = DemandedMask.countLeadingZeros();
|
|
unsigned NTZ = DemandedMask.countTrailingZeros();
|
|
|
|
// Round NTZ down to the next byte. If we have 11 trailing zeros, then
|
|
// we need all the bits down to bit 8. Likewise, round NLZ. If we
|
|
// have 14 leading zeros, round to 8.
|
|
NLZ &= ~7;
|
|
NTZ &= ~7;
|
|
// If we need exactly one byte, we can do this transformation.
|
|
if (BitWidth-NLZ-NTZ == 8) {
|
|
unsigned ResultBit = NTZ;
|
|
unsigned InputBit = BitWidth-NTZ-8;
|
|
|
|
// Replace this with either a left or right shift to get the byte into
|
|
// the right place.
|
|
Instruction *NewVal;
|
|
if (InputBit > ResultBit)
|
|
NewVal = BinaryOperator::CreateLShr(I->getOperand(1),
|
|
ConstantInt::get(I->getType(), InputBit-ResultBit));
|
|
else
|
|
NewVal = BinaryOperator::CreateShl(I->getOperand(1),
|
|
ConstantInt::get(I->getType(), ResultBit-InputBit));
|
|
NewVal->takeName(I);
|
|
return InsertNewInstBefore(NewVal, *I);
|
|
}
|
|
|
|
// TODO: Could compute known zero/one bits based on the input.
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
ComputeMaskedBits(V, DemandedMask, RHSKnownZero, RHSKnownOne, Depth);
|
|
break;
|
|
}
|
|
|
|
// If the client is only demanding bits that we know, return the known
|
|
// constant.
|
|
if ((DemandedMask & (RHSKnownZero|RHSKnownOne)) == DemandedMask)
|
|
return ConstantInt::get(RHSKnownOne);
|
|
return false;
|
|
}
|
|
|
|
|
|
/// SimplifyDemandedVectorElts - The specified value produces a vector with
|
|
/// any number of elements. DemandedElts contains the set of elements that are
|
|
/// actually used by the caller. This method analyzes which elements of the
|
|
/// operand are undef and returns that information in UndefElts.
|
|
///
|
|
/// If the information about demanded elements can be used to simplify the
|
|
/// operation, the operation is simplified, then the resultant value is
|
|
/// returned. This returns null if no change was made.
|
|
Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
|
|
APInt& UndefElts,
|
|
unsigned Depth) {
|
|
unsigned VWidth = cast<VectorType>(V->getType())->getNumElements();
|
|
APInt EltMask(APInt::getAllOnesValue(VWidth));
|
|
assert((DemandedElts & ~EltMask) == 0 && "Invalid DemandedElts!");
|
|
|
|
if (isa<UndefValue>(V)) {
|
|
// If the entire vector is undefined, just return this info.
|
|
UndefElts = EltMask;
|
|
return 0;
|
|
} else if (DemandedElts == 0) { // If nothing is demanded, provide undef.
|
|
UndefElts = EltMask;
|
|
return UndefValue::get(V->getType());
|
|
}
|
|
|
|
UndefElts = 0;
|
|
if (ConstantVector *CP = dyn_cast<ConstantVector>(V)) {
|
|
const Type *EltTy = cast<VectorType>(V->getType())->getElementType();
|
|
Constant *Undef = UndefValue::get(EltTy);
|
|
|
|
std::vector<Constant*> Elts;
|
|
for (unsigned i = 0; i != VWidth; ++i)
|
|
if (!DemandedElts[i]) { // If not demanded, set to undef.
|
|
Elts.push_back(Undef);
|
|
UndefElts.set(i);
|
|
} else if (isa<UndefValue>(CP->getOperand(i))) { // Already undef.
|
|
Elts.push_back(Undef);
|
|
UndefElts.set(i);
|
|
} else { // Otherwise, defined.
|
|
Elts.push_back(CP->getOperand(i));
|
|
}
|
|
|
|
// If we changed the constant, return it.
|
|
Constant *NewCP = ConstantVector::get(Elts);
|
|
return NewCP != CP ? NewCP : 0;
|
|
} else if (isa<ConstantAggregateZero>(V)) {
|
|
// Simplify the CAZ to a ConstantVector where the non-demanded elements are
|
|
// set to undef.
|
|
|
|
// Check if this is identity. If so, return 0 since we are not simplifying
|
|
// anything.
|
|
if (DemandedElts == ((1ULL << VWidth) -1))
|
|
return 0;
|
|
|
|
const Type *EltTy = cast<VectorType>(V->getType())->getElementType();
|
|
Constant *Zero = Constant::getNullValue(EltTy);
|
|
Constant *Undef = UndefValue::get(EltTy);
|
|
std::vector<Constant*> Elts;
|
|
for (unsigned i = 0; i != VWidth; ++i) {
|
|
Constant *Elt = DemandedElts[i] ? Zero : Undef;
|
|
Elts.push_back(Elt);
|
|
}
|
|
UndefElts = DemandedElts ^ EltMask;
|
|
return ConstantVector::get(Elts);
|
|
}
|
|
|
|
// Limit search depth.
|
|
if (Depth == 10)
|
|
return false;
|
|
|
|
// If multiple users are using the root value, procede with
|
|
// simplification conservatively assuming that all elements
|
|
// are needed.
|
|
if (!V->hasOneUse()) {
|
|
// Quit if we find multiple users of a non-root value though.
|
|
// They'll be handled when it's their turn to be visited by
|
|
// the main instcombine process.
|
|
if (Depth != 0)
|
|
// TODO: Just compute the UndefElts information recursively.
|
|
return false;
|
|
|
|
// Conservatively assume that all elements are needed.
|
|
DemandedElts = EltMask;
|
|
}
|
|
|
|
Instruction *I = dyn_cast<Instruction>(V);
|
|
if (!I) return false; // Only analyze instructions.
|
|
|
|
bool MadeChange = false;
|
|
APInt UndefElts2(VWidth, 0);
|
|
Value *TmpV;
|
|
switch (I->getOpcode()) {
|
|
default: break;
|
|
|
|
case Instruction::InsertElement: {
|
|
// If this is a variable index, we don't know which element it overwrites.
|
|
// demand exactly the same input as we produce.
|
|
ConstantInt *Idx = dyn_cast<ConstantInt>(I->getOperand(2));
|
|
if (Idx == 0) {
|
|
// Note that we can't propagate undef elt info, because we don't know
|
|
// which elt is getting updated.
|
|
TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts,
|
|
UndefElts2, Depth+1);
|
|
if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
|
|
break;
|
|
}
|
|
|
|
// If this is inserting an element that isn't demanded, remove this
|
|
// insertelement.
|
|
unsigned IdxNo = Idx->getZExtValue();
|
|
if (IdxNo >= VWidth || !DemandedElts[IdxNo])
|
|
return AddSoonDeadInstToWorklist(*I, 0);
|
|
|
|
// Otherwise, the element inserted overwrites whatever was there, so the
|
|
// input demanded set is simpler than the output set.
|
|
APInt DemandedElts2 = DemandedElts;
|
|
DemandedElts2.clear(IdxNo);
|
|
TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts2,
|
|
UndefElts, Depth+1);
|
|
if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
|
|
|
|
// The inserted element is defined.
|
|
UndefElts.clear(IdxNo);
|
|
break;
|
|
}
|
|
case Instruction::ShuffleVector: {
|
|
ShuffleVectorInst *Shuffle = cast<ShuffleVectorInst>(I);
|
|
uint64_t LHSVWidth =
|
|
cast<VectorType>(Shuffle->getOperand(0)->getType())->getNumElements();
|
|
APInt LeftDemanded(LHSVWidth, 0), RightDemanded(LHSVWidth, 0);
|
|
for (unsigned i = 0; i < VWidth; i++) {
|
|
if (DemandedElts[i]) {
|
|
unsigned MaskVal = Shuffle->getMaskValue(i);
|
|
if (MaskVal != -1u) {
|
|
assert(MaskVal < LHSVWidth * 2 &&
|
|
"shufflevector mask index out of range!");
|
|
if (MaskVal < LHSVWidth)
|
|
LeftDemanded.set(MaskVal);
|
|
else
|
|
RightDemanded.set(MaskVal - LHSVWidth);
|
|
}
|
|
}
|
|
}
|
|
|
|
APInt UndefElts4(LHSVWidth, 0);
|
|
TmpV = SimplifyDemandedVectorElts(I->getOperand(0), LeftDemanded,
|
|
UndefElts4, Depth+1);
|
|
if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
|
|
|
|
APInt UndefElts3(LHSVWidth, 0);
|
|
TmpV = SimplifyDemandedVectorElts(I->getOperand(1), RightDemanded,
|
|
UndefElts3, Depth+1);
|
|
if (TmpV) { I->setOperand(1, TmpV); MadeChange = true; }
|
|
|
|
bool NewUndefElts = false;
|
|
for (unsigned i = 0; i < VWidth; i++) {
|
|
unsigned MaskVal = Shuffle->getMaskValue(i);
|
|
if (MaskVal == -1u) {
|
|
UndefElts.set(i);
|
|
} else if (MaskVal < LHSVWidth) {
|
|
if (UndefElts4[MaskVal]) {
|
|
NewUndefElts = true;
|
|
UndefElts.set(i);
|
|
}
|
|
} else {
|
|
if (UndefElts3[MaskVal - LHSVWidth]) {
|
|
NewUndefElts = true;
|
|
UndefElts.set(i);
|
|
}
|
|
}
|
|
}
|
|
|
|
if (NewUndefElts) {
|
|
// Add additional discovered undefs.
|
|
std::vector<Constant*> Elts;
|
|
for (unsigned i = 0; i < VWidth; ++i) {
|
|
if (UndefElts[i])
|
|
Elts.push_back(UndefValue::get(Type::Int32Ty));
|
|
else
|
|
Elts.push_back(ConstantInt::get(Type::Int32Ty,
|
|
Shuffle->getMaskValue(i)));
|
|
}
|
|
I->setOperand(2, ConstantVector::get(Elts));
|
|
MadeChange = true;
|
|
}
|
|
break;
|
|
}
|
|
case Instruction::BitCast: {
|
|
// Vector->vector casts only.
|
|
const VectorType *VTy = dyn_cast<VectorType>(I->getOperand(0)->getType());
|
|
if (!VTy) break;
|
|
unsigned InVWidth = VTy->getNumElements();
|
|
APInt InputDemandedElts(InVWidth, 0);
|
|
unsigned Ratio;
|
|
|
|
if (VWidth == InVWidth) {
|
|
// If we are converting from <4 x i32> -> <4 x f32>, we demand the same
|
|
// elements as are demanded of us.
|
|
Ratio = 1;
|
|
InputDemandedElts = DemandedElts;
|
|
} else if (VWidth > InVWidth) {
|
|
// Untested so far.
|
|
break;
|
|
|
|
// If there are more elements in the result than there are in the source,
|
|
// then an input element is live if any of the corresponding output
|
|
// elements are live.
|
|
Ratio = VWidth/InVWidth;
|
|
for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx) {
|
|
if (DemandedElts[OutIdx])
|
|
InputDemandedElts.set(OutIdx/Ratio);
|
|
}
|
|
} else {
|
|
// Untested so far.
|
|
break;
|
|
|
|
// If there are more elements in the source than there are in the result,
|
|
// then an input element is live if the corresponding output element is
|
|
// live.
|
|
Ratio = InVWidth/VWidth;
|
|
for (unsigned InIdx = 0; InIdx != InVWidth; ++InIdx)
|
|
if (DemandedElts[InIdx/Ratio])
|
|
InputDemandedElts.set(InIdx);
|
|
}
|
|
|
|
// div/rem demand all inputs, because they don't want divide by zero.
|
|
TmpV = SimplifyDemandedVectorElts(I->getOperand(0), InputDemandedElts,
|
|
UndefElts2, Depth+1);
|
|
if (TmpV) {
|
|
I->setOperand(0, TmpV);
|
|
MadeChange = true;
|
|
}
|
|
|
|
UndefElts = UndefElts2;
|
|
if (VWidth > InVWidth) {
|
|
assert(0 && "Unimp");
|
|
// If there are more elements in the result than there are in the source,
|
|
// then an output element is undef if the corresponding input element is
|
|
// undef.
|
|
for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx)
|
|
if (UndefElts2[OutIdx/Ratio])
|
|
UndefElts.set(OutIdx);
|
|
} else if (VWidth < InVWidth) {
|
|
assert(0 && "Unimp");
|
|
// If there are more elements in the source than there are in the result,
|
|
// then a result element is undef if all of the corresponding input
|
|
// elements are undef.
|
|
UndefElts = ~0ULL >> (64-VWidth); // Start out all undef.
|
|
for (unsigned InIdx = 0; InIdx != InVWidth; ++InIdx)
|
|
if (!UndefElts2[InIdx]) // Not undef?
|
|
UndefElts.clear(InIdx/Ratio); // Clear undef bit.
|
|
}
|
|
break;
|
|
}
|
|
case Instruction::And:
|
|
case Instruction::Or:
|
|
case Instruction::Xor:
|
|
case Instruction::Add:
|
|
case Instruction::Sub:
|
|
case Instruction::Mul:
|
|
// div/rem demand all inputs, because they don't want divide by zero.
|
|
TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts,
|
|
UndefElts, Depth+1);
|
|
if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; }
|
|
TmpV = SimplifyDemandedVectorElts(I->getOperand(1), DemandedElts,
|
|
UndefElts2, Depth+1);
|
|
if (TmpV) { I->setOperand(1, TmpV); MadeChange = true; }
|
|
|
|
// Output elements are undefined if both are undefined. Consider things
|
|
// like undef&0. The result is known zero, not undef.
|
|
UndefElts &= UndefElts2;
|
|
break;
|
|
|
|
case Instruction::Call: {
|
|
IntrinsicInst *II = dyn_cast<IntrinsicInst>(I);
|
|
if (!II) break;
|
|
switch (II->getIntrinsicID()) {
|
|
default: break;
|
|
|
|
// Binary vector operations that work column-wise. A dest element is a
|
|
// function of the corresponding input elements from the two inputs.
|
|
case Intrinsic::x86_sse_sub_ss:
|
|
case Intrinsic::x86_sse_mul_ss:
|
|
case Intrinsic::x86_sse_min_ss:
|
|
case Intrinsic::x86_sse_max_ss:
|
|
case Intrinsic::x86_sse2_sub_sd:
|
|
case Intrinsic::x86_sse2_mul_sd:
|
|
case Intrinsic::x86_sse2_min_sd:
|
|
case Intrinsic::x86_sse2_max_sd:
|
|
TmpV = SimplifyDemandedVectorElts(II->getOperand(1), DemandedElts,
|
|
UndefElts, Depth+1);
|
|
if (TmpV) { II->setOperand(1, TmpV); MadeChange = true; }
|
|
TmpV = SimplifyDemandedVectorElts(II->getOperand(2), DemandedElts,
|
|
UndefElts2, Depth+1);
|
|
if (TmpV) { II->setOperand(2, TmpV); MadeChange = true; }
|
|
|
|
// If only the low elt is demanded and this is a scalarizable intrinsic,
|
|
// scalarize it now.
|
|
if (DemandedElts == 1) {
|
|
switch (II->getIntrinsicID()) {
|
|
default: break;
|
|
case Intrinsic::x86_sse_sub_ss:
|
|
case Intrinsic::x86_sse_mul_ss:
|
|
case Intrinsic::x86_sse2_sub_sd:
|
|
case Intrinsic::x86_sse2_mul_sd:
|
|
// TODO: Lower MIN/MAX/ABS/etc
|
|
Value *LHS = II->getOperand(1);
|
|
Value *RHS = II->getOperand(2);
|
|
// Extract the element as scalars.
|
|
LHS = InsertNewInstBefore(new ExtractElementInst(LHS, 0U,"tmp"), *II);
|
|
RHS = InsertNewInstBefore(new ExtractElementInst(RHS, 0U,"tmp"), *II);
|
|
|
|
switch (II->getIntrinsicID()) {
|
|
default: assert(0 && "Case stmts out of sync!");
|
|
case Intrinsic::x86_sse_sub_ss:
|
|
case Intrinsic::x86_sse2_sub_sd:
|
|
TmpV = InsertNewInstBefore(BinaryOperator::CreateSub(LHS, RHS,
|
|
II->getName()), *II);
|
|
break;
|
|
case Intrinsic::x86_sse_mul_ss:
|
|
case Intrinsic::x86_sse2_mul_sd:
|
|
TmpV = InsertNewInstBefore(BinaryOperator::CreateMul(LHS, RHS,
|
|
II->getName()), *II);
|
|
break;
|
|
}
|
|
|
|
Instruction *New =
|
|
InsertElementInst::Create(UndefValue::get(II->getType()), TmpV, 0U,
|
|
II->getName());
|
|
InsertNewInstBefore(New, *II);
|
|
AddSoonDeadInstToWorklist(*II, 0);
|
|
return New;
|
|
}
|
|
}
|
|
|
|
// Output elements are undefined if both are undefined. Consider things
|
|
// like undef&0. The result is known zero, not undef.
|
|
UndefElts &= UndefElts2;
|
|
break;
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
return MadeChange ? I : 0;
|
|
}
|
|
|
|
|
|
/// AssociativeOpt - Perform an optimization on an associative operator. This
|
|
/// function is designed to check a chain of associative operators for a
|
|
/// potential to apply a certain optimization. Since the optimization may be
|
|
/// applicable if the expression was reassociated, this checks the chain, then
|
|
/// reassociates the expression as necessary to expose the optimization
|
|
/// opportunity. This makes use of a special Functor, which must define
|
|
/// 'shouldApply' and 'apply' methods.
|
|
///
|
|
template<typename Functor>
|
|
static Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
|
|
unsigned Opcode = Root.getOpcode();
|
|
Value *LHS = Root.getOperand(0);
|
|
|
|
// Quick check, see if the immediate LHS matches...
|
|
if (F.shouldApply(LHS))
|
|
return F.apply(Root);
|
|
|
|
// Otherwise, if the LHS is not of the same opcode as the root, return.
|
|
Instruction *LHSI = dyn_cast<Instruction>(LHS);
|
|
while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) {
|
|
// Should we apply this transform to the RHS?
|
|
bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
|
|
|
|
// If not to the RHS, check to see if we should apply to the LHS...
|
|
if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
|
|
cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
|
|
ShouldApply = true;
|
|
}
|
|
|
|
// If the functor wants to apply the optimization to the RHS of LHSI,
|
|
// reassociate the expression from ((? op A) op B) to (? op (A op B))
|
|
if (ShouldApply) {
|
|
// Now all of the instructions are in the current basic block, go ahead
|
|
// and perform the reassociation.
|
|
Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
|
|
|
|
// First move the selected RHS to the LHS of the root...
|
|
Root.setOperand(0, LHSI->getOperand(1));
|
|
|
|
// Make what used to be the LHS of the root be the user of the root...
|
|
Value *ExtraOperand = TmpLHSI->getOperand(1);
|
|
if (&Root == TmpLHSI) {
|
|
Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
|
|
return 0;
|
|
}
|
|
Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
|
|
TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
|
|
BasicBlock::iterator ARI = &Root; ++ARI;
|
|
TmpLHSI->moveBefore(ARI); // Move TmpLHSI to after Root
|
|
ARI = Root;
|
|
|
|
// Now propagate the ExtraOperand down the chain of instructions until we
|
|
// get to LHSI.
|
|
while (TmpLHSI != LHSI) {
|
|
Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
|
|
// Move the instruction to immediately before the chain we are
|
|
// constructing to avoid breaking dominance properties.
|
|
NextLHSI->moveBefore(ARI);
|
|
ARI = NextLHSI;
|
|
|
|
Value *NextOp = NextLHSI->getOperand(1);
|
|
NextLHSI->setOperand(1, ExtraOperand);
|
|
TmpLHSI = NextLHSI;
|
|
ExtraOperand = NextOp;
|
|
}
|
|
|
|
// Now that the instructions are reassociated, have the functor perform
|
|
// the transformation...
|
|
return F.apply(Root);
|
|
}
|
|
|
|
LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
namespace {
|
|
|
|
// AddRHS - Implements: X + X --> X << 1
|
|
struct AddRHS {
|
|
Value *RHS;
|
|
AddRHS(Value *rhs) : RHS(rhs) {}
|
|
bool shouldApply(Value *LHS) const { return LHS == RHS; }
|
|
Instruction *apply(BinaryOperator &Add) const {
|
|
return BinaryOperator::CreateShl(Add.getOperand(0),
|
|
ConstantInt::get(Add.getType(), 1));
|
|
}
|
|
};
|
|
|
|
// AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
|
|
// iff C1&C2 == 0
|
|
struct AddMaskingAnd {
|
|
Constant *C2;
|
|
AddMaskingAnd(Constant *c) : C2(c) {}
|
|
bool shouldApply(Value *LHS) const {
|
|
ConstantInt *C1;
|
|
return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) &&
|
|
ConstantExpr::getAnd(C1, C2)->isNullValue();
|
|
}
|
|
Instruction *apply(BinaryOperator &Add) const {
|
|
return BinaryOperator::CreateOr(Add.getOperand(0), Add.getOperand(1));
|
|
}
|
|
};
|
|
|
|
}
|
|
|
|
static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
|
|
InstCombiner *IC) {
|
|
if (CastInst *CI = dyn_cast<CastInst>(&I)) {
|
|
return IC->InsertCastBefore(CI->getOpcode(), SO, I.getType(), I);
|
|
}
|
|
|
|
// Figure out if the constant is the left or the right argument.
|
|
bool ConstIsRHS = isa<Constant>(I.getOperand(1));
|
|
Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
|
|
|
|
if (Constant *SOC = dyn_cast<Constant>(SO)) {
|
|
if (ConstIsRHS)
|
|
return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
|
|
return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
|
|
}
|
|
|
|
Value *Op0 = SO, *Op1 = ConstOperand;
|
|
if (!ConstIsRHS)
|
|
std::swap(Op0, Op1);
|
|
Instruction *New;
|
|
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
|
|
New = BinaryOperator::Create(BO->getOpcode(), Op0, Op1,SO->getName()+".op");
|
|
else if (CmpInst *CI = dyn_cast<CmpInst>(&I))
|
|
New = CmpInst::Create(CI->getOpcode(), CI->getPredicate(), Op0, Op1,
|
|
SO->getName()+".cmp");
|
|
else {
|
|
assert(0 && "Unknown binary instruction type!");
|
|
abort();
|
|
}
|
|
return IC->InsertNewInstBefore(New, I);
|
|
}
|
|
|
|
// FoldOpIntoSelect - Given an instruction with a select as one operand and a
|
|
// constant as the other operand, try to fold the binary operator into the
|
|
// select arguments. This also works for Cast instructions, which obviously do
|
|
// not have a second operand.
|
|
static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
|
|
InstCombiner *IC) {
|
|
// Don't modify shared select instructions
|
|
if (!SI->hasOneUse()) return 0;
|
|
Value *TV = SI->getOperand(1);
|
|
Value *FV = SI->getOperand(2);
|
|
|
|
if (isa<Constant>(TV) || isa<Constant>(FV)) {
|
|
// Bool selects with constant operands can be folded to logical ops.
|
|
if (SI->getType() == Type::Int1Ty) return 0;
|
|
|
|
Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
|
|
Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
|
|
|
|
return SelectInst::Create(SI->getCondition(), SelectTrueVal,
|
|
SelectFalseVal);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
|
|
/// FoldOpIntoPhi - Given a binary operator or cast instruction which has a PHI
|
|
/// node as operand #0, see if we can fold the instruction into the PHI (which
|
|
/// is only possible if all operands to the PHI are constants).
|
|
Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
|
|
PHINode *PN = cast<PHINode>(I.getOperand(0));
|
|
unsigned NumPHIValues = PN->getNumIncomingValues();
|
|
if (!PN->hasOneUse() || NumPHIValues == 0) return 0;
|
|
|
|
// Check to see if all of the operands of the PHI are constants. If there is
|
|
// one non-constant value, remember the BB it is. If there is more than one
|
|
// or if *it* is a PHI, bail out.
|
|
BasicBlock *NonConstBB = 0;
|
|
for (unsigned i = 0; i != NumPHIValues; ++i)
|
|
if (!isa<Constant>(PN->getIncomingValue(i))) {
|
|
if (NonConstBB) return 0; // More than one non-const value.
|
|
if (isa<PHINode>(PN->getIncomingValue(i))) return 0; // Itself a phi.
|
|
NonConstBB = PN->getIncomingBlock(i);
|
|
|
|
// If the incoming non-constant value is in I's block, we have an infinite
|
|
// loop.
|
|
if (NonConstBB == I.getParent())
|
|
return 0;
|
|
}
|
|
|
|
// If there is exactly one non-constant value, we can insert a copy of the
|
|
// operation in that block. However, if this is a critical edge, we would be
|
|
// inserting the computation one some other paths (e.g. inside a loop). Only
|
|
// do this if the pred block is unconditionally branching into the phi block.
|
|
if (NonConstBB) {
|
|
BranchInst *BI = dyn_cast<BranchInst>(NonConstBB->getTerminator());
|
|
if (!BI || !BI->isUnconditional()) return 0;
|
|
}
|
|
|
|
// Okay, we can do the transformation: create the new PHI node.
|
|
PHINode *NewPN = PHINode::Create(I.getType(), "");
|
|
NewPN->reserveOperandSpace(PN->getNumOperands()/2);
|
|
InsertNewInstBefore(NewPN, *PN);
|
|
NewPN->takeName(PN);
|
|
|
|
// Next, add all of the operands to the PHI.
|
|
if (I.getNumOperands() == 2) {
|
|
Constant *C = cast<Constant>(I.getOperand(1));
|
|
for (unsigned i = 0; i != NumPHIValues; ++i) {
|
|
Value *InV = 0;
|
|
if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
|
|
if (CmpInst *CI = dyn_cast<CmpInst>(&I))
|
|
InV = ConstantExpr::getCompare(CI->getPredicate(), InC, C);
|
|
else
|
|
InV = ConstantExpr::get(I.getOpcode(), InC, C);
|
|
} else {
|
|
assert(PN->getIncomingBlock(i) == NonConstBB);
|
|
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
|
|
InV = BinaryOperator::Create(BO->getOpcode(),
|
|
PN->getIncomingValue(i), C, "phitmp",
|
|
NonConstBB->getTerminator());
|
|
else if (CmpInst *CI = dyn_cast<CmpInst>(&I))
|
|
InV = CmpInst::Create(CI->getOpcode(),
|
|
CI->getPredicate(),
|
|
PN->getIncomingValue(i), C, "phitmp",
|
|
NonConstBB->getTerminator());
|
|
else
|
|
assert(0 && "Unknown binop!");
|
|
|
|
AddToWorkList(cast<Instruction>(InV));
|
|
}
|
|
NewPN->addIncoming(InV, PN->getIncomingBlock(i));
|
|
}
|
|
} else {
|
|
CastInst *CI = cast<CastInst>(&I);
|
|
const Type *RetTy = CI->getType();
|
|
for (unsigned i = 0; i != NumPHIValues; ++i) {
|
|
Value *InV;
|
|
if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
|
|
InV = ConstantExpr::getCast(CI->getOpcode(), InC, RetTy);
|
|
} else {
|
|
assert(PN->getIncomingBlock(i) == NonConstBB);
|
|
InV = CastInst::Create(CI->getOpcode(), PN->getIncomingValue(i),
|
|
I.getType(), "phitmp",
|
|
NonConstBB->getTerminator());
|
|
AddToWorkList(cast<Instruction>(InV));
|
|
}
|
|
NewPN->addIncoming(InV, PN->getIncomingBlock(i));
|
|
}
|
|
}
|
|
return ReplaceInstUsesWith(I, NewPN);
|
|
}
|
|
|
|
|
|
/// WillNotOverflowSignedAdd - Return true if we can prove that:
|
|
/// (sext (add LHS, RHS)) === (add (sext LHS), (sext RHS))
|
|
/// This basically requires proving that the add in the original type would not
|
|
/// overflow to change the sign bit or have a carry out.
|
|
bool InstCombiner::WillNotOverflowSignedAdd(Value *LHS, Value *RHS) {
|
|
// There are different heuristics we can use for this. Here are some simple
|
|
// ones.
|
|
|
|
// Add has the property that adding any two 2's complement numbers can only
|
|
// have one carry bit which can change a sign. As such, if LHS and RHS each
|
|
// have at least two sign bits, we know that the addition of the two values will
|
|
// sign extend fine.
|
|
if (ComputeNumSignBits(LHS) > 1 && ComputeNumSignBits(RHS) > 1)
|
|
return true;
|
|
|
|
|
|
// If one of the operands only has one non-zero bit, and if the other operand
|
|
// has a known-zero bit in a more significant place than it (not including the
|
|
// sign bit) the ripple may go up to and fill the zero, but won't change the
|
|
// sign. For example, (X & ~4) + 1.
|
|
|
|
// TODO: Implement.
|
|
|
|
return false;
|
|
}
|
|
|
|
|
|
Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
|
|
bool Changed = SimplifyCommutative(I);
|
|
Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
|
|
|
|
if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
|
|
// X + undef -> undef
|
|
if (isa<UndefValue>(RHS))
|
|
return ReplaceInstUsesWith(I, RHS);
|
|
|
|
// X + 0 --> X
|
|
if (!I.getType()->isFPOrFPVector()) { // NOTE: -0 + +0 = +0.
|
|
if (RHSC->isNullValue())
|
|
return ReplaceInstUsesWith(I, LHS);
|
|
} else if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
|
|
if (CFP->isExactlyValue(ConstantFP::getNegativeZero
|
|
(I.getType())->getValueAPF()))
|
|
return ReplaceInstUsesWith(I, LHS);
|
|
}
|
|
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
|
|
// X + (signbit) --> X ^ signbit
|
|
const APInt& Val = CI->getValue();
|
|
uint32_t BitWidth = Val.getBitWidth();
|
|
if (Val == APInt::getSignBit(BitWidth))
|
|
return BinaryOperator::CreateXor(LHS, RHS);
|
|
|
|
// See if SimplifyDemandedBits can simplify this. This handles stuff like
|
|
// (X & 254)+1 -> (X&254)|1
|
|
if (!isa<VectorType>(I.getType()) && SimplifyDemandedInstructionBits(I))
|
|
return &I;
|
|
|
|
// zext(i1) - 1 -> select i1, 0, -1
|
|
if (ZExtInst *ZI = dyn_cast<ZExtInst>(LHS))
|
|
if (CI->isAllOnesValue() &&
|
|
ZI->getOperand(0)->getType() == Type::Int1Ty)
|
|
return SelectInst::Create(ZI->getOperand(0),
|
|
Constant::getNullValue(I.getType()),
|
|
ConstantInt::getAllOnesValue(I.getType()));
|
|
}
|
|
|
|
if (isa<PHINode>(LHS))
|
|
if (Instruction *NV = FoldOpIntoPhi(I))
|
|
return NV;
|
|
|
|
ConstantInt *XorRHS = 0;
|
|
Value *XorLHS = 0;
|
|
if (isa<ConstantInt>(RHSC) &&
|
|
match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
|
|
uint32_t TySizeBits = I.getType()->getPrimitiveSizeInBits();
|
|
const APInt& RHSVal = cast<ConstantInt>(RHSC)->getValue();
|
|
|
|
uint32_t Size = TySizeBits / 2;
|
|
APInt C0080Val(APInt(TySizeBits, 1ULL).shl(Size - 1));
|
|
APInt CFF80Val(-C0080Val);
|
|
do {
|
|
if (TySizeBits > Size) {
|
|
// If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext.
|
|
// If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext.
|
|
if ((RHSVal == CFF80Val && XorRHS->getValue() == C0080Val) ||
|
|
(RHSVal == C0080Val && XorRHS->getValue() == CFF80Val)) {
|
|
// This is a sign extend if the top bits are known zero.
|
|
if (!MaskedValueIsZero(XorLHS,
|
|
APInt::getHighBitsSet(TySizeBits, TySizeBits - Size)))
|
|
Size = 0; // Not a sign ext, but can't be any others either.
|
|
break;
|
|
}
|
|
}
|
|
Size >>= 1;
|
|
C0080Val = APIntOps::lshr(C0080Val, Size);
|
|
CFF80Val = APIntOps::ashr(CFF80Val, Size);
|
|
} while (Size >= 1);
|
|
|
|
// FIXME: This shouldn't be necessary. When the backends can handle types
|
|
// with funny bit widths then this switch statement should be removed. It
|
|
// is just here to get the size of the "middle" type back up to something
|
|
// that the back ends can handle.
|
|
const Type *MiddleType = 0;
|
|
switch (Size) {
|
|
default: break;
|
|
case 32: MiddleType = Type::Int32Ty; break;
|
|
case 16: MiddleType = Type::Int16Ty; break;
|
|
case 8: MiddleType = Type::Int8Ty; break;
|
|
}
|
|
if (MiddleType) {
|
|
Instruction *NewTrunc = new TruncInst(XorLHS, MiddleType, "sext");
|
|
InsertNewInstBefore(NewTrunc, I);
|
|
return new SExtInst(NewTrunc, I.getType(), I.getName());
|
|
}
|
|
}
|
|
}
|
|
|
|
if (I.getType() == Type::Int1Ty)
|
|
return BinaryOperator::CreateXor(LHS, RHS);
|
|
|
|
// X + X --> X << 1
|
|
if (I.getType()->isInteger()) {
|
|
if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
|
|
|
|
if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
|
|
if (RHSI->getOpcode() == Instruction::Sub)
|
|
if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B
|
|
return ReplaceInstUsesWith(I, RHSI->getOperand(0));
|
|
}
|
|
if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) {
|
|
if (LHSI->getOpcode() == Instruction::Sub)
|
|
if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B
|
|
return ReplaceInstUsesWith(I, LHSI->getOperand(0));
|
|
}
|
|
}
|
|
|
|
// -A + B --> B - A
|
|
// -A + -B --> -(A + B)
|
|
if (Value *LHSV = dyn_castNegVal(LHS)) {
|
|
if (LHS->getType()->isIntOrIntVector()) {
|
|
if (Value *RHSV = dyn_castNegVal(RHS)) {
|
|
Instruction *NewAdd = BinaryOperator::CreateAdd(LHSV, RHSV, "sum");
|
|
InsertNewInstBefore(NewAdd, I);
|
|
return BinaryOperator::CreateNeg(NewAdd);
|
|
}
|
|
}
|
|
|
|
return BinaryOperator::CreateSub(RHS, LHSV);
|
|
}
|
|
|
|
// A + -B --> A - B
|
|
if (!isa<Constant>(RHS))
|
|
if (Value *V = dyn_castNegVal(RHS))
|
|
return BinaryOperator::CreateSub(LHS, V);
|
|
|
|
|
|
ConstantInt *C2;
|
|
if (Value *X = dyn_castFoldableMul(LHS, C2)) {
|
|
if (X == RHS) // X*C + X --> X * (C+1)
|
|
return BinaryOperator::CreateMul(RHS, AddOne(C2));
|
|
|
|
// X*C1 + X*C2 --> X * (C1+C2)
|
|
ConstantInt *C1;
|
|
if (X == dyn_castFoldableMul(RHS, C1))
|
|
return BinaryOperator::CreateMul(X, Add(C1, C2));
|
|
}
|
|
|
|
// X + X*C --> X * (C+1)
|
|
if (dyn_castFoldableMul(RHS, C2) == LHS)
|
|
return BinaryOperator::CreateMul(LHS, AddOne(C2));
|
|
|
|
// X + ~X --> -1 since ~X = -X-1
|
|
if (dyn_castNotVal(LHS) == RHS || dyn_castNotVal(RHS) == LHS)
|
|
return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
|
|
|
|
|
|
// (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
|
|
if (match(RHS, m_And(m_Value(), m_ConstantInt(C2))))
|
|
if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2)))
|
|
return R;
|
|
|
|
// A+B --> A|B iff A and B have no bits set in common.
|
|
if (const IntegerType *IT = dyn_cast<IntegerType>(I.getType())) {
|
|
APInt Mask = APInt::getAllOnesValue(IT->getBitWidth());
|
|
APInt LHSKnownOne(IT->getBitWidth(), 0);
|
|
APInt LHSKnownZero(IT->getBitWidth(), 0);
|
|
ComputeMaskedBits(LHS, Mask, LHSKnownZero, LHSKnownOne);
|
|
if (LHSKnownZero != 0) {
|
|
APInt RHSKnownOne(IT->getBitWidth(), 0);
|
|
APInt RHSKnownZero(IT->getBitWidth(), 0);
|
|
ComputeMaskedBits(RHS, Mask, RHSKnownZero, RHSKnownOne);
|
|
|
|
// No bits in common -> bitwise or.
|
|
if ((LHSKnownZero|RHSKnownZero).isAllOnesValue())
|
|
return BinaryOperator::CreateOr(LHS, RHS);
|
|
}
|
|
}
|
|
|
|
// W*X + Y*Z --> W * (X+Z) iff W == Y
|
|
if (I.getType()->isIntOrIntVector()) {
|
|
Value *W, *X, *Y, *Z;
|
|
if (match(LHS, m_Mul(m_Value(W), m_Value(X))) &&
|
|
match(RHS, m_Mul(m_Value(Y), m_Value(Z)))) {
|
|
if (W != Y) {
|
|
if (W == Z) {
|
|
std::swap(Y, Z);
|
|
} else if (Y == X) {
|
|
std::swap(W, X);
|
|
} else if (X == Z) {
|
|
std::swap(Y, Z);
|
|
std::swap(W, X);
|
|
}
|
|
}
|
|
|
|
if (W == Y) {
|
|
Value *NewAdd = InsertNewInstBefore(BinaryOperator::CreateAdd(X, Z,
|
|
LHS->getName()), I);
|
|
return BinaryOperator::CreateMul(W, NewAdd);
|
|
}
|
|
}
|
|
}
|
|
|
|
if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
|
|
Value *X = 0;
|
|
if (match(LHS, m_Not(m_Value(X)))) // ~X + C --> (C-1) - X
|
|
return BinaryOperator::CreateSub(SubOne(CRHS), X);
|
|
|
|
// (X & FF00) + xx00 -> (X+xx00) & FF00
|
|
if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
|
|
Constant *Anded = And(CRHS, C2);
|
|
if (Anded == CRHS) {
|
|
// See if all bits from the first bit set in the Add RHS up are included
|
|
// in the mask. First, get the rightmost bit.
|
|
const APInt& AddRHSV = CRHS->getValue();
|
|
|
|
// Form a mask of all bits from the lowest bit added through the top.
|
|
APInt AddRHSHighBits(~((AddRHSV & -AddRHSV)-1));
|
|
|
|
// See if the and mask includes all of these bits.
|
|
APInt AddRHSHighBitsAnd(AddRHSHighBits & C2->getValue());
|
|
|
|
if (AddRHSHighBits == AddRHSHighBitsAnd) {
|
|
// Okay, the xform is safe. Insert the new add pronto.
|
|
Value *NewAdd = InsertNewInstBefore(BinaryOperator::CreateAdd(X, CRHS,
|
|
LHS->getName()), I);
|
|
return BinaryOperator::CreateAnd(NewAdd, C2);
|
|
}
|
|
}
|
|
}
|
|
|
|
// Try to fold constant add into select arguments.
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
|
|
if (Instruction *R = FoldOpIntoSelect(I, SI, this))
|
|
return R;
|
|
}
|
|
|
|
// add (cast *A to intptrtype) B ->
|
|
// cast (GEP (cast *A to sbyte*) B) --> intptrtype
|
|
{
|
|
CastInst *CI = dyn_cast<CastInst>(LHS);
|
|
Value *Other = RHS;
|
|
if (!CI) {
|
|
CI = dyn_cast<CastInst>(RHS);
|
|
Other = LHS;
|
|
}
|
|
if (CI && CI->getType()->isSized() &&
|
|
(CI->getType()->getPrimitiveSizeInBits() ==
|
|
TD->getIntPtrType()->getPrimitiveSizeInBits())
|
|
&& isa<PointerType>(CI->getOperand(0)->getType())) {
|
|
unsigned AS =
|
|
cast<PointerType>(CI->getOperand(0)->getType())->getAddressSpace();
|
|
Value *I2 = InsertBitCastBefore(CI->getOperand(0),
|
|
PointerType::get(Type::Int8Ty, AS), I);
|
|
I2 = InsertNewInstBefore(GetElementPtrInst::Create(I2, Other, "ctg2"), I);
|
|
return new PtrToIntInst(I2, CI->getType());
|
|
}
|
|
}
|
|
|
|
// add (select X 0 (sub n A)) A --> select X A n
|
|
{
|
|
SelectInst *SI = dyn_cast<SelectInst>(LHS);
|
|
Value *A = RHS;
|
|
if (!SI) {
|
|
SI = dyn_cast<SelectInst>(RHS);
|
|
A = LHS;
|
|
}
|
|
if (SI && SI->hasOneUse()) {
|
|
Value *TV = SI->getTrueValue();
|
|
Value *FV = SI->getFalseValue();
|
|
Value *N;
|
|
|
|
// Can we fold the add into the argument of the select?
|
|
// We check both true and false select arguments for a matching subtract.
|
|
if (match(FV, m_Zero()) && match(TV, m_Sub(m_Value(N), m_Specific(A))))
|
|
// Fold the add into the true select value.
|
|
return SelectInst::Create(SI->getCondition(), N, A);
|
|
if (match(TV, m_Zero()) && match(FV, m_Sub(m_Value(N), m_Specific(A))))
|
|
// Fold the add into the false select value.
|
|
return SelectInst::Create(SI->getCondition(), A, N);
|
|
}
|
|
}
|
|
|
|
// Check for X+0.0. Simplify it to X if we know X is not -0.0.
|
|
if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS))
|
|
if (CFP->getValueAPF().isPosZero() && CannotBeNegativeZero(LHS))
|
|
return ReplaceInstUsesWith(I, LHS);
|
|
|
|
// Check for (add (sext x), y), see if we can merge this into an
|
|
// integer add followed by a sext.
|
|
if (SExtInst *LHSConv = dyn_cast<SExtInst>(LHS)) {
|
|
// (add (sext x), cst) --> (sext (add x, cst'))
|
|
if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
|
|
Constant *CI =
|
|
ConstantExpr::getTrunc(RHSC, LHSConv->getOperand(0)->getType());
|
|
if (LHSConv->hasOneUse() &&
|
|
ConstantExpr::getSExt(CI, I.getType()) == RHSC &&
|
|
WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) {
|
|
// Insert the new, smaller add.
|
|
Instruction *NewAdd = BinaryOperator::CreateAdd(LHSConv->getOperand(0),
|
|
CI, "addconv");
|
|
InsertNewInstBefore(NewAdd, I);
|
|
return new SExtInst(NewAdd, I.getType());
|
|
}
|
|
}
|
|
|
|
// (add (sext x), (sext y)) --> (sext (add int x, y))
|
|
if (SExtInst *RHSConv = dyn_cast<SExtInst>(RHS)) {
|
|
// Only do this if x/y have the same type, if at last one of them has a
|
|
// single use (so we don't increase the number of sexts), and if the
|
|
// integer add will not overflow.
|
|
if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&&
|
|
(LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
|
|
WillNotOverflowSignedAdd(LHSConv->getOperand(0),
|
|
RHSConv->getOperand(0))) {
|
|
// Insert the new integer add.
|
|
Instruction *NewAdd = BinaryOperator::CreateAdd(LHSConv->getOperand(0),
|
|
RHSConv->getOperand(0),
|
|
"addconv");
|
|
InsertNewInstBefore(NewAdd, I);
|
|
return new SExtInst(NewAdd, I.getType());
|
|
}
|
|
}
|
|
}
|
|
|
|
// Check for (add double (sitofp x), y), see if we can merge this into an
|
|
// integer add followed by a promotion.
|
|
if (SIToFPInst *LHSConv = dyn_cast<SIToFPInst>(LHS)) {
|
|
// (add double (sitofp x), fpcst) --> (sitofp (add int x, intcst))
|
|
// ... if the constant fits in the integer value. This is useful for things
|
|
// like (double)(x & 1234) + 4.0 -> (double)((X & 1234)+4) which no longer
|
|
// requires a constant pool load, and generally allows the add to be better
|
|
// instcombined.
|
|
if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS)) {
|
|
Constant *CI =
|
|
ConstantExpr::getFPToSI(CFP, LHSConv->getOperand(0)->getType());
|
|
if (LHSConv->hasOneUse() &&
|
|
ConstantExpr::getSIToFP(CI, I.getType()) == CFP &&
|
|
WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) {
|
|
// Insert the new integer add.
|
|
Instruction *NewAdd = BinaryOperator::CreateAdd(LHSConv->getOperand(0),
|
|
CI, "addconv");
|
|
InsertNewInstBefore(NewAdd, I);
|
|
return new SIToFPInst(NewAdd, I.getType());
|
|
}
|
|
}
|
|
|
|
// (add double (sitofp x), (sitofp y)) --> (sitofp (add int x, y))
|
|
if (SIToFPInst *RHSConv = dyn_cast<SIToFPInst>(RHS)) {
|
|
// Only do this if x/y have the same type, if at last one of them has a
|
|
// single use (so we don't increase the number of int->fp conversions),
|
|
// and if the integer add will not overflow.
|
|
if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&&
|
|
(LHSConv->hasOneUse() || RHSConv->hasOneUse()) &&
|
|
WillNotOverflowSignedAdd(LHSConv->getOperand(0),
|
|
RHSConv->getOperand(0))) {
|
|
// Insert the new integer add.
|
|
Instruction *NewAdd = BinaryOperator::CreateAdd(LHSConv->getOperand(0),
|
|
RHSConv->getOperand(0),
|
|
"addconv");
|
|
InsertNewInstBefore(NewAdd, I);
|
|
return new SIToFPInst(NewAdd, I.getType());
|
|
}
|
|
}
|
|
}
|
|
|
|
return Changed ? &I : 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitSub(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
if (Op0 == Op1 && // sub X, X -> 0
|
|
!I.getType()->isFPOrFPVector())
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
|
|
// If this is a 'B = x-(-A)', change to B = x+A...
|
|
if (Value *V = dyn_castNegVal(Op1))
|
|
return BinaryOperator::CreateAdd(Op0, V);
|
|
|
|
if (isa<UndefValue>(Op0))
|
|
return ReplaceInstUsesWith(I, Op0); // undef - X -> undef
|
|
if (isa<UndefValue>(Op1))
|
|
return ReplaceInstUsesWith(I, Op1); // X - undef -> undef
|
|
|
|
if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
|
|
// Replace (-1 - A) with (~A)...
|
|
if (C->isAllOnesValue())
|
|
return BinaryOperator::CreateNot(Op1);
|
|
|
|
// C - ~X == X + (1+C)
|
|
Value *X = 0;
|
|
if (match(Op1, m_Not(m_Value(X))))
|
|
return BinaryOperator::CreateAdd(X, AddOne(C));
|
|
|
|
// -(X >>u 31) -> (X >>s 31)
|
|
// -(X >>s 31) -> (X >>u 31)
|
|
if (C->isZero()) {
|
|
if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op1)) {
|
|
if (SI->getOpcode() == Instruction::LShr) {
|
|
if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
|
|
// Check to see if we are shifting out everything but the sign bit.
|
|
if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
|
|
SI->getType()->getPrimitiveSizeInBits()-1) {
|
|
// Ok, the transformation is safe. Insert AShr.
|
|
return BinaryOperator::Create(Instruction::AShr,
|
|
SI->getOperand(0), CU, SI->getName());
|
|
}
|
|
}
|
|
}
|
|
else if (SI->getOpcode() == Instruction::AShr) {
|
|
if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) {
|
|
// Check to see if we are shifting out everything but the sign bit.
|
|
if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) ==
|
|
SI->getType()->getPrimitiveSizeInBits()-1) {
|
|
// Ok, the transformation is safe. Insert LShr.
|
|
return BinaryOperator::CreateLShr(
|
|
SI->getOperand(0), CU, SI->getName());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Try to fold constant sub into select arguments.
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
|
|
if (Instruction *R = FoldOpIntoSelect(I, SI, this))
|
|
return R;
|
|
}
|
|
|
|
if (I.getType() == Type::Int1Ty)
|
|
return BinaryOperator::CreateXor(Op0, Op1);
|
|
|
|
if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
|
|
if (Op1I->getOpcode() == Instruction::Add &&
|
|
!Op0->getType()->isFPOrFPVector()) {
|
|
if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y
|
|
return BinaryOperator::CreateNeg(Op1I->getOperand(1), I.getName());
|
|
else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y
|
|
return BinaryOperator::CreateNeg(Op1I->getOperand(0), I.getName());
|
|
else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) {
|
|
if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1)))
|
|
// C1-(X+C2) --> (C1-C2)-X
|
|
return BinaryOperator::CreateSub(Subtract(CI1, CI2),
|
|
Op1I->getOperand(0));
|
|
}
|
|
}
|
|
|
|
if (Op1I->hasOneUse()) {
|
|
// Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
|
|
// is not used by anyone else...
|
|
//
|
|
if (Op1I->getOpcode() == Instruction::Sub &&
|
|
!Op1I->getType()->isFPOrFPVector()) {
|
|
// Swap the two operands of the subexpr...
|
|
Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
|
|
Op1I->setOperand(0, IIOp1);
|
|
Op1I->setOperand(1, IIOp0);
|
|
|
|
// Create the new top level add instruction...
|
|
return BinaryOperator::CreateAdd(Op0, Op1);
|
|
}
|
|
|
|
// Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
|
|
//
|
|
if (Op1I->getOpcode() == Instruction::And &&
|
|
(Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
|
|
Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
|
|
|
|
Value *NewNot =
|
|
InsertNewInstBefore(BinaryOperator::CreateNot(OtherOp, "B.not"), I);
|
|
return BinaryOperator::CreateAnd(Op0, NewNot);
|
|
}
|
|
|
|
// 0 - (X sdiv C) -> (X sdiv -C)
|
|
if (Op1I->getOpcode() == Instruction::SDiv)
|
|
if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
|
|
if (CSI->isZero())
|
|
if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
|
|
return BinaryOperator::CreateSDiv(Op1I->getOperand(0),
|
|
ConstantExpr::getNeg(DivRHS));
|
|
|
|
// X - X*C --> X * (1-C)
|
|
ConstantInt *C2 = 0;
|
|
if (dyn_castFoldableMul(Op1I, C2) == Op0) {
|
|
Constant *CP1 = Subtract(ConstantInt::get(I.getType(), 1), C2);
|
|
return BinaryOperator::CreateMul(Op0, CP1);
|
|
}
|
|
}
|
|
}
|
|
|
|
if (!Op0->getType()->isFPOrFPVector())
|
|
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
|
|
if (Op0I->getOpcode() == Instruction::Add) {
|
|
if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X
|
|
return ReplaceInstUsesWith(I, Op0I->getOperand(1));
|
|
else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X
|
|
return ReplaceInstUsesWith(I, Op0I->getOperand(0));
|
|
} else if (Op0I->getOpcode() == Instruction::Sub) {
|
|
if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y
|
|
return BinaryOperator::CreateNeg(Op0I->getOperand(1), I.getName());
|
|
}
|
|
}
|
|
|
|
ConstantInt *C1;
|
|
if (Value *X = dyn_castFoldableMul(Op0, C1)) {
|
|
if (X == Op1) // X*C - X --> X * (C-1)
|
|
return BinaryOperator::CreateMul(Op1, SubOne(C1));
|
|
|
|
ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
|
|
if (X == dyn_castFoldableMul(Op1, C2))
|
|
return BinaryOperator::CreateMul(X, Subtract(C1, C2));
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/// isSignBitCheck - Given an exploded icmp instruction, return true if the
|
|
/// comparison only checks the sign bit. If it only checks the sign bit, set
|
|
/// TrueIfSigned if the result of the comparison is true when the input value is
|
|
/// signed.
|
|
static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS,
|
|
bool &TrueIfSigned) {
|
|
switch (pred) {
|
|
case ICmpInst::ICMP_SLT: // True if LHS s< 0
|
|
TrueIfSigned = true;
|
|
return RHS->isZero();
|
|
case ICmpInst::ICMP_SLE: // True if LHS s<= RHS and RHS == -1
|
|
TrueIfSigned = true;
|
|
return RHS->isAllOnesValue();
|
|
case ICmpInst::ICMP_SGT: // True if LHS s> -1
|
|
TrueIfSigned = false;
|
|
return RHS->isAllOnesValue();
|
|
case ICmpInst::ICMP_UGT:
|
|
// True if LHS u> RHS and RHS == high-bit-mask - 1
|
|
TrueIfSigned = true;
|
|
return RHS->getValue() ==
|
|
APInt::getSignedMaxValue(RHS->getType()->getPrimitiveSizeInBits());
|
|
case ICmpInst::ICMP_UGE:
|
|
// True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc)
|
|
TrueIfSigned = true;
|
|
return RHS->getValue().isSignBit();
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
|
|
Instruction *InstCombiner::visitMul(BinaryOperator &I) {
|
|
bool Changed = SimplifyCommutative(I);
|
|
Value *Op0 = I.getOperand(0);
|
|
|
|
if (isa<UndefValue>(I.getOperand(1))) // undef * X -> 0
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
|
|
// Simplify mul instructions with a constant RHS...
|
|
if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
|
|
|
|
// ((X << C1)*C2) == (X * (C2 << C1))
|
|
if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op0))
|
|
if (SI->getOpcode() == Instruction::Shl)
|
|
if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
|
|
return BinaryOperator::CreateMul(SI->getOperand(0),
|
|
ConstantExpr::getShl(CI, ShOp));
|
|
|
|
if (CI->isZero())
|
|
return ReplaceInstUsesWith(I, Op1); // X * 0 == 0
|
|
if (CI->equalsInt(1)) // X * 1 == X
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
if (CI->isAllOnesValue()) // X * -1 == 0 - X
|
|
return BinaryOperator::CreateNeg(Op0, I.getName());
|
|
|
|
const APInt& Val = cast<ConstantInt>(CI)->getValue();
|
|
if (Val.isPowerOf2()) { // Replace X*(2^C) with X << C
|
|
return BinaryOperator::CreateShl(Op0,
|
|
ConstantInt::get(Op0->getType(), Val.logBase2()));
|
|
}
|
|
} else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) {
|
|
if (Op1F->isNullValue())
|
|
return ReplaceInstUsesWith(I, Op1);
|
|
|
|
// "In IEEE floating point, x*1 is not equivalent to x for nans. However,
|
|
// ANSI says we can drop signals, so we can do this anyway." (from GCC)
|
|
if (Op1F->isExactlyValue(1.0))
|
|
return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
|
|
} else if (isa<VectorType>(Op1->getType())) {
|
|
if (isa<ConstantAggregateZero>(Op1))
|
|
return ReplaceInstUsesWith(I, Op1);
|
|
|
|
if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1)) {
|
|
if (Op1V->isAllOnesValue()) // X * -1 == 0 - X
|
|
return BinaryOperator::CreateNeg(Op0, I.getName());
|
|
|
|
// As above, vector X*splat(1.0) -> X in all defined cases.
|
|
if (Constant *Splat = Op1V->getSplatValue()) {
|
|
if (ConstantFP *F = dyn_cast<ConstantFP>(Splat))
|
|
if (F->isExactlyValue(1.0))
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(Splat))
|
|
if (CI->equalsInt(1))
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
}
|
|
}
|
|
}
|
|
|
|
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0))
|
|
if (Op0I->getOpcode() == Instruction::Add && Op0I->hasOneUse() &&
|
|
isa<ConstantInt>(Op0I->getOperand(1)) && isa<ConstantInt>(Op1)) {
|
|
// Canonicalize (X+C1)*C2 -> X*C2+C1*C2.
|
|
Instruction *Add = BinaryOperator::CreateMul(Op0I->getOperand(0),
|
|
Op1, "tmp");
|
|
InsertNewInstBefore(Add, I);
|
|
Value *C1C2 = ConstantExpr::getMul(Op1,
|
|
cast<Constant>(Op0I->getOperand(1)));
|
|
return BinaryOperator::CreateAdd(Add, C1C2);
|
|
|
|
}
|
|
|
|
// Try to fold constant mul into select arguments.
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
|
|
if (Instruction *R = FoldOpIntoSelect(I, SI, this))
|
|
return R;
|
|
|
|
if (isa<PHINode>(Op0))
|
|
if (Instruction *NV = FoldOpIntoPhi(I))
|
|
return NV;
|
|
}
|
|
|
|
if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
|
|
if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
|
|
return BinaryOperator::CreateMul(Op0v, Op1v);
|
|
|
|
// (X / Y) * Y = X - (X % Y)
|
|
// (X / Y) * -Y = (X % Y) - X
|
|
{
|
|
Value *Op1 = I.getOperand(1);
|
|
BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0);
|
|
if (!BO ||
|
|
(BO->getOpcode() != Instruction::UDiv &&
|
|
BO->getOpcode() != Instruction::SDiv)) {
|
|
Op1 = Op0;
|
|
BO = dyn_cast<BinaryOperator>(I.getOperand(1));
|
|
}
|
|
Value *Neg = dyn_castNegVal(Op1);
|
|
if (BO && BO->hasOneUse() &&
|
|
(BO->getOperand(1) == Op1 || BO->getOperand(1) == Neg) &&
|
|
(BO->getOpcode() == Instruction::UDiv ||
|
|
BO->getOpcode() == Instruction::SDiv)) {
|
|
Value *Op0BO = BO->getOperand(0), *Op1BO = BO->getOperand(1);
|
|
|
|
Instruction *Rem;
|
|
if (BO->getOpcode() == Instruction::UDiv)
|
|
Rem = BinaryOperator::CreateURem(Op0BO, Op1BO);
|
|
else
|
|
Rem = BinaryOperator::CreateSRem(Op0BO, Op1BO);
|
|
|
|
InsertNewInstBefore(Rem, I);
|
|
Rem->takeName(BO);
|
|
|
|
if (Op1BO == Op1)
|
|
return BinaryOperator::CreateSub(Op0BO, Rem);
|
|
else
|
|
return BinaryOperator::CreateSub(Rem, Op0BO);
|
|
}
|
|
}
|
|
|
|
if (I.getType() == Type::Int1Ty)
|
|
return BinaryOperator::CreateAnd(Op0, I.getOperand(1));
|
|
|
|
// If one of the operands of the multiply is a cast from a boolean value, then
|
|
// we know the bool is either zero or one, so this is a 'masking' multiply.
|
|
// See if we can simplify things based on how the boolean was originally
|
|
// formed.
|
|
CastInst *BoolCast = 0;
|
|
if (ZExtInst *CI = dyn_cast<ZExtInst>(Op0))
|
|
if (CI->getOperand(0)->getType() == Type::Int1Ty)
|
|
BoolCast = CI;
|
|
if (!BoolCast)
|
|
if (ZExtInst *CI = dyn_cast<ZExtInst>(I.getOperand(1)))
|
|
if (CI->getOperand(0)->getType() == Type::Int1Ty)
|
|
BoolCast = CI;
|
|
if (BoolCast) {
|
|
if (ICmpInst *SCI = dyn_cast<ICmpInst>(BoolCast->getOperand(0))) {
|
|
Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
|
|
const Type *SCOpTy = SCIOp0->getType();
|
|
bool TIS = false;
|
|
|
|
// If the icmp is true iff the sign bit of X is set, then convert this
|
|
// multiply into a shift/and combination.
|
|
if (isa<ConstantInt>(SCIOp1) &&
|
|
isSignBitCheck(SCI->getPredicate(), cast<ConstantInt>(SCIOp1), TIS) &&
|
|
TIS) {
|
|
// Shift the X value right to turn it into "all signbits".
|
|
Constant *Amt = ConstantInt::get(SCIOp0->getType(),
|
|
SCOpTy->getPrimitiveSizeInBits()-1);
|
|
Value *V =
|
|
InsertNewInstBefore(
|
|
BinaryOperator::Create(Instruction::AShr, SCIOp0, Amt,
|
|
BoolCast->getOperand(0)->getName()+
|
|
".mask"), I);
|
|
|
|
// If the multiply type is not the same as the source type, sign extend
|
|
// or truncate to the multiply type.
|
|
if (I.getType() != V->getType()) {
|
|
uint32_t SrcBits = V->getType()->getPrimitiveSizeInBits();
|
|
uint32_t DstBits = I.getType()->getPrimitiveSizeInBits();
|
|
Instruction::CastOps opcode =
|
|
(SrcBits == DstBits ? Instruction::BitCast :
|
|
(SrcBits < DstBits ? Instruction::SExt : Instruction::Trunc));
|
|
V = InsertCastBefore(opcode, V, I.getType(), I);
|
|
}
|
|
|
|
Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
|
|
return BinaryOperator::CreateAnd(V, OtherOp);
|
|
}
|
|
}
|
|
}
|
|
|
|
return Changed ? &I : 0;
|
|
}
|
|
|
|
/// SimplifyDivRemOfSelect - Try to fold a divide or remainder of a select
|
|
/// instruction.
|
|
bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) {
|
|
SelectInst *SI = cast<SelectInst>(I.getOperand(1));
|
|
|
|
// div/rem X, (Cond ? 0 : Y) -> div/rem X, Y
|
|
int NonNullOperand = -1;
|
|
if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
|
|
if (ST->isNullValue())
|
|
NonNullOperand = 2;
|
|
// div/rem X, (Cond ? Y : 0) -> div/rem X, Y
|
|
if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
|
|
if (ST->isNullValue())
|
|
NonNullOperand = 1;
|
|
|
|
if (NonNullOperand == -1)
|
|
return false;
|
|
|
|
Value *SelectCond = SI->getOperand(0);
|
|
|
|
// Change the div/rem to use 'Y' instead of the select.
|
|
I.setOperand(1, SI->getOperand(NonNullOperand));
|
|
|
|
// Okay, we know we replace the operand of the div/rem with 'Y' with no
|
|
// problem. However, the select, or the condition of the select may have
|
|
// multiple uses. Based on our knowledge that the operand must be non-zero,
|
|
// propagate the known value for the select into other uses of it, and
|
|
// propagate a known value of the condition into its other users.
|
|
|
|
// If the select and condition only have a single use, don't bother with this,
|
|
// early exit.
|
|
if (SI->use_empty() && SelectCond->hasOneUse())
|
|
return true;
|
|
|
|
// Scan the current block backward, looking for other uses of SI.
|
|
BasicBlock::iterator BBI = &I, BBFront = I.getParent()->begin();
|
|
|
|
while (BBI != BBFront) {
|
|
--BBI;
|
|
// If we found a call to a function, we can't assume it will return, so
|
|
// information from below it cannot be propagated above it.
|
|
if (isa<CallInst>(BBI) && !isa<IntrinsicInst>(BBI))
|
|
break;
|
|
|
|
// Replace uses of the select or its condition with the known values.
|
|
for (Instruction::op_iterator I = BBI->op_begin(), E = BBI->op_end();
|
|
I != E; ++I) {
|
|
if (*I == SI) {
|
|
*I = SI->getOperand(NonNullOperand);
|
|
AddToWorkList(BBI);
|
|
} else if (*I == SelectCond) {
|
|
*I = NonNullOperand == 1 ? ConstantInt::getTrue() :
|
|
ConstantInt::getFalse();
|
|
AddToWorkList(BBI);
|
|
}
|
|
}
|
|
|
|
// If we past the instruction, quit looking for it.
|
|
if (&*BBI == SI)
|
|
SI = 0;
|
|
if (&*BBI == SelectCond)
|
|
SelectCond = 0;
|
|
|
|
// If we ran out of things to eliminate, break out of the loop.
|
|
if (SelectCond == 0 && SI == 0)
|
|
break;
|
|
|
|
}
|
|
return true;
|
|
}
|
|
|
|
|
|
/// This function implements the transforms on div instructions that work
|
|
/// regardless of the kind of div instruction it is (udiv, sdiv, or fdiv). It is
|
|
/// used by the visitors to those instructions.
|
|
/// @brief Transforms common to all three div instructions
|
|
Instruction *InstCombiner::commonDivTransforms(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
// undef / X -> 0 for integer.
|
|
// undef / X -> undef for FP (the undef could be a snan).
|
|
if (isa<UndefValue>(Op0)) {
|
|
if (Op0->getType()->isFPOrFPVector())
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
}
|
|
|
|
// X / undef -> undef
|
|
if (isa<UndefValue>(Op1))
|
|
return ReplaceInstUsesWith(I, Op1);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/// This function implements the transforms common to both integer division
|
|
/// instructions (udiv and sdiv). It is called by the visitors to those integer
|
|
/// division instructions.
|
|
/// @brief Common integer divide transforms
|
|
Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
// (sdiv X, X) --> 1 (udiv X, X) --> 1
|
|
if (Op0 == Op1) {
|
|
if (const VectorType *Ty = dyn_cast<VectorType>(I.getType())) {
|
|
ConstantInt *CI = ConstantInt::get(Ty->getElementType(), 1);
|
|
std::vector<Constant*> Elts(Ty->getNumElements(), CI);
|
|
return ReplaceInstUsesWith(I, ConstantVector::get(Elts));
|
|
}
|
|
|
|
ConstantInt *CI = ConstantInt::get(I.getType(), 1);
|
|
return ReplaceInstUsesWith(I, CI);
|
|
}
|
|
|
|
if (Instruction *Common = commonDivTransforms(I))
|
|
return Common;
|
|
|
|
// Handle cases involving: [su]div X, (select Cond, Y, Z)
|
|
// This does not apply for fdiv.
|
|
if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
|
|
return &I;
|
|
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
|
|
// div X, 1 == X
|
|
if (RHS->equalsInt(1))
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
|
|
// (X / C1) / C2 -> X / (C1*C2)
|
|
if (Instruction *LHS = dyn_cast<Instruction>(Op0))
|
|
if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode())
|
|
if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
|
|
if (MultiplyOverflows(RHS, LHSRHS, I.getOpcode()==Instruction::SDiv))
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
else
|
|
return BinaryOperator::Create(I.getOpcode(), LHS->getOperand(0),
|
|
Multiply(RHS, LHSRHS));
|
|
}
|
|
|
|
if (!RHS->isZero()) { // avoid X udiv 0
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
|
|
if (Instruction *R = FoldOpIntoSelect(I, SI, this))
|
|
return R;
|
|
if (isa<PHINode>(Op0))
|
|
if (Instruction *NV = FoldOpIntoPhi(I))
|
|
return NV;
|
|
}
|
|
}
|
|
|
|
// 0 / X == 0, we don't need to preserve faults!
|
|
if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0))
|
|
if (LHS->equalsInt(0))
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
|
|
// It can't be division by zero, hence it must be division by one.
|
|
if (I.getType() == Type::Int1Ty)
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
|
|
if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1)) {
|
|
if (ConstantInt *X = cast_or_null<ConstantInt>(Op1V->getSplatValue()))
|
|
// div X, 1 == X
|
|
if (X->isOne())
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
// Handle the integer div common cases
|
|
if (Instruction *Common = commonIDivTransforms(I))
|
|
return Common;
|
|
|
|
if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) {
|
|
// X udiv C^2 -> X >> C
|
|
// Check to see if this is an unsigned division with an exact power of 2,
|
|
// if so, convert to a right shift.
|
|
if (C->getValue().isPowerOf2()) // 0 not included in isPowerOf2
|
|
return BinaryOperator::CreateLShr(Op0,
|
|
ConstantInt::get(Op0->getType(), C->getValue().logBase2()));
|
|
|
|
// X udiv C, where C >= signbit
|
|
if (C->getValue().isNegative()) {
|
|
Value *IC = InsertNewInstBefore(new ICmpInst(ICmpInst::ICMP_ULT, Op0, C),
|
|
I);
|
|
return SelectInst::Create(IC, Constant::getNullValue(I.getType()),
|
|
ConstantInt::get(I.getType(), 1));
|
|
}
|
|
}
|
|
|
|
// X udiv (C1 << N), where C1 is "1<<C2" --> X >> (N+C2)
|
|
if (BinaryOperator *RHSI = dyn_cast<BinaryOperator>(I.getOperand(1))) {
|
|
if (RHSI->getOpcode() == Instruction::Shl &&
|
|
isa<ConstantInt>(RHSI->getOperand(0))) {
|
|
const APInt& C1 = cast<ConstantInt>(RHSI->getOperand(0))->getValue();
|
|
if (C1.isPowerOf2()) {
|
|
Value *N = RHSI->getOperand(1);
|
|
const Type *NTy = N->getType();
|
|
if (uint32_t C2 = C1.logBase2()) {
|
|
Constant *C2V = ConstantInt::get(NTy, C2);
|
|
N = InsertNewInstBefore(BinaryOperator::CreateAdd(N, C2V, "tmp"), I);
|
|
}
|
|
return BinaryOperator::CreateLShr(Op0, N);
|
|
}
|
|
}
|
|
}
|
|
|
|
// udiv X, (Select Cond, C1, C2) --> Select Cond, (shr X, C1), (shr X, C2)
|
|
// where C1&C2 are powers of two.
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
|
|
if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
|
|
if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
|
|
const APInt &TVA = STO->getValue(), &FVA = SFO->getValue();
|
|
if (TVA.isPowerOf2() && FVA.isPowerOf2()) {
|
|
// Compute the shift amounts
|
|
uint32_t TSA = TVA.logBase2(), FSA = FVA.logBase2();
|
|
// Construct the "on true" case of the select
|
|
Constant *TC = ConstantInt::get(Op0->getType(), TSA);
|
|
Instruction *TSI = BinaryOperator::CreateLShr(
|
|
Op0, TC, SI->getName()+".t");
|
|
TSI = InsertNewInstBefore(TSI, I);
|
|
|
|
// Construct the "on false" case of the select
|
|
Constant *FC = ConstantInt::get(Op0->getType(), FSA);
|
|
Instruction *FSI = BinaryOperator::CreateLShr(
|
|
Op0, FC, SI->getName()+".f");
|
|
FSI = InsertNewInstBefore(FSI, I);
|
|
|
|
// construct the select instruction and return it.
|
|
return SelectInst::Create(SI->getOperand(0), TSI, FSI, SI->getName());
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
// Handle the integer div common cases
|
|
if (Instruction *Common = commonIDivTransforms(I))
|
|
return Common;
|
|
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
|
|
// sdiv X, -1 == -X
|
|
if (RHS->isAllOnesValue())
|
|
return BinaryOperator::CreateNeg(Op0);
|
|
}
|
|
|
|
// If the sign bits of both operands are zero (i.e. we can prove they are
|
|
// unsigned inputs), turn this into a udiv.
|
|
if (I.getType()->isInteger()) {
|
|
APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
|
|
if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
|
|
// X sdiv Y -> X udiv Y, iff X and Y don't have sign bit set
|
|
return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitFDiv(BinaryOperator &I) {
|
|
return commonDivTransforms(I);
|
|
}
|
|
|
|
/// This function implements the transforms on rem instructions that work
|
|
/// regardless of the kind of rem instruction it is (urem, srem, or frem). It
|
|
/// is used by the visitors to those instructions.
|
|
/// @brief Transforms common to all three rem instructions
|
|
Instruction *InstCombiner::commonRemTransforms(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
if (isa<UndefValue>(Op0)) { // undef % X -> 0
|
|
if (I.getType()->isFPOrFPVector())
|
|
return ReplaceInstUsesWith(I, Op0); // X % undef -> undef (could be SNaN)
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
}
|
|
if (isa<UndefValue>(Op1))
|
|
return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
|
|
|
|
// Handle cases involving: rem X, (select Cond, Y, Z)
|
|
if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
|
|
return &I;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/// This function implements the transforms common to both integer remainder
|
|
/// instructions (urem and srem). It is called by the visitors to those integer
|
|
/// remainder instructions.
|
|
/// @brief Common integer remainder transforms
|
|
Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
if (Instruction *common = commonRemTransforms(I))
|
|
return common;
|
|
|
|
// 0 % X == 0 for integer, we don't need to preserve faults!
|
|
if (Constant *LHS = dyn_cast<Constant>(Op0))
|
|
if (LHS->isNullValue())
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
|
|
// X % 0 == undef, we don't need to preserve faults!
|
|
if (RHS->equalsInt(0))
|
|
return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
|
|
|
|
if (RHS->equalsInt(1)) // X % 1 == 0
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
|
|
if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) {
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op0I)) {
|
|
if (Instruction *R = FoldOpIntoSelect(I, SI, this))
|
|
return R;
|
|
} else if (isa<PHINode>(Op0I)) {
|
|
if (Instruction *NV = FoldOpIntoPhi(I))
|
|
return NV;
|
|
}
|
|
|
|
// See if we can fold away this rem instruction.
|
|
if (SimplifyDemandedInstructionBits(I))
|
|
return &I;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitURem(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
if (Instruction *common = commonIRemTransforms(I))
|
|
return common;
|
|
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
|
|
// X urem C^2 -> X and C
|
|
// Check to see if this is an unsigned remainder with an exact power of 2,
|
|
// if so, convert to a bitwise and.
|
|
if (ConstantInt *C = dyn_cast<ConstantInt>(RHS))
|
|
if (C->getValue().isPowerOf2())
|
|
return BinaryOperator::CreateAnd(Op0, SubOne(C));
|
|
}
|
|
|
|
if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) {
|
|
// Turn A % (C << N), where C is 2^k, into A & ((C << N)-1)
|
|
if (RHSI->getOpcode() == Instruction::Shl &&
|
|
isa<ConstantInt>(RHSI->getOperand(0))) {
|
|
if (cast<ConstantInt>(RHSI->getOperand(0))->getValue().isPowerOf2()) {
|
|
Constant *N1 = ConstantInt::getAllOnesValue(I.getType());
|
|
Value *Add = InsertNewInstBefore(BinaryOperator::CreateAdd(RHSI, N1,
|
|
"tmp"), I);
|
|
return BinaryOperator::CreateAnd(Op0, Add);
|
|
}
|
|
}
|
|
}
|
|
|
|
// urem X, (select Cond, 2^C1, 2^C2) --> select Cond, (and X, C1), (and X, C2)
|
|
// where C1&C2 are powers of two.
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) {
|
|
if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1)))
|
|
if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) {
|
|
// STO == 0 and SFO == 0 handled above.
|
|
if ((STO->getValue().isPowerOf2()) &&
|
|
(SFO->getValue().isPowerOf2())) {
|
|
Value *TrueAnd = InsertNewInstBefore(
|
|
BinaryOperator::CreateAnd(Op0, SubOne(STO), SI->getName()+".t"), I);
|
|
Value *FalseAnd = InsertNewInstBefore(
|
|
BinaryOperator::CreateAnd(Op0, SubOne(SFO), SI->getName()+".f"), I);
|
|
return SelectInst::Create(SI->getOperand(0), TrueAnd, FalseAnd);
|
|
}
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
// Handle the integer rem common cases
|
|
if (Instruction *common = commonIRemTransforms(I))
|
|
return common;
|
|
|
|
if (Value *RHSNeg = dyn_castNegVal(Op1))
|
|
if (!isa<Constant>(RHSNeg) ||
|
|
(isa<ConstantInt>(RHSNeg) &&
|
|
cast<ConstantInt>(RHSNeg)->getValue().isStrictlyPositive())) {
|
|
// X % -Y -> X % Y
|
|
AddUsesToWorkList(I);
|
|
I.setOperand(1, RHSNeg);
|
|
return &I;
|
|
}
|
|
|
|
// If the sign bits of both operands are zero (i.e. we can prove they are
|
|
// unsigned inputs), turn this into a urem.
|
|
if (I.getType()->isInteger()) {
|
|
APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
|
|
if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
|
|
// X srem Y -> X urem Y, iff X and Y don't have sign bit set
|
|
return BinaryOperator::CreateURem(Op0, Op1, I.getName());
|
|
}
|
|
}
|
|
|
|
// If it's a constant vector, flip any negative values positive.
|
|
if (ConstantVector *RHSV = dyn_cast<ConstantVector>(Op1)) {
|
|
unsigned VWidth = RHSV->getNumOperands();
|
|
|
|
bool hasNegative = false;
|
|
for (unsigned i = 0; !hasNegative && i != VWidth; ++i)
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i)))
|
|
if (RHS->getValue().isNegative())
|
|
hasNegative = true;
|
|
|
|
if (hasNegative) {
|
|
std::vector<Constant *> Elts(VWidth);
|
|
for (unsigned i = 0; i != VWidth; ++i) {
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i))) {
|
|
if (RHS->getValue().isNegative())
|
|
Elts[i] = cast<ConstantInt>(ConstantExpr::getNeg(RHS));
|
|
else
|
|
Elts[i] = RHS;
|
|
}
|
|
}
|
|
|
|
Constant *NewRHSV = ConstantVector::get(Elts);
|
|
if (NewRHSV != RHSV) {
|
|
AddUsesToWorkList(I);
|
|
I.setOperand(1, NewRHSV);
|
|
return &I;
|
|
}
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitFRem(BinaryOperator &I) {
|
|
return commonRemTransforms(I);
|
|
}
|
|
|
|
// isOneBitSet - Return true if there is exactly one bit set in the specified
|
|
// constant.
|
|
static bool isOneBitSet(const ConstantInt *CI) {
|
|
return CI->getValue().isPowerOf2();
|
|
}
|
|
|
|
// isHighOnes - Return true if the constant is of the form 1+0+.
|
|
// This is the same as lowones(~X).
|
|
static bool isHighOnes(const ConstantInt *CI) {
|
|
return (~CI->getValue() + 1).isPowerOf2();
|
|
}
|
|
|
|
/// getICmpCode - Encode a icmp predicate into a three bit mask. These bits
|
|
/// are carefully arranged to allow folding of expressions such as:
|
|
///
|
|
/// (A < B) | (A > B) --> (A != B)
|
|
///
|
|
/// Note that this is only valid if the first and second predicates have the
|
|
/// same sign. Is illegal to do: (A u< B) | (A s> B)
|
|
///
|
|
/// Three bits are used to represent the condition, as follows:
|
|
/// 0 A > B
|
|
/// 1 A == B
|
|
/// 2 A < B
|
|
///
|
|
/// <=> Value Definition
|
|
/// 000 0 Always false
|
|
/// 001 1 A > B
|
|
/// 010 2 A == B
|
|
/// 011 3 A >= B
|
|
/// 100 4 A < B
|
|
/// 101 5 A != B
|
|
/// 110 6 A <= B
|
|
/// 111 7 Always true
|
|
///
|
|
static unsigned getICmpCode(const ICmpInst *ICI) {
|
|
switch (ICI->getPredicate()) {
|
|
// False -> 0
|
|
case ICmpInst::ICMP_UGT: return 1; // 001
|
|
case ICmpInst::ICMP_SGT: return 1; // 001
|
|
case ICmpInst::ICMP_EQ: return 2; // 010
|
|
case ICmpInst::ICMP_UGE: return 3; // 011
|
|
case ICmpInst::ICMP_SGE: return 3; // 011
|
|
case ICmpInst::ICMP_ULT: return 4; // 100
|
|
case ICmpInst::ICMP_SLT: return 4; // 100
|
|
case ICmpInst::ICMP_NE: return 5; // 101
|
|
case ICmpInst::ICMP_ULE: return 6; // 110
|
|
case ICmpInst::ICMP_SLE: return 6; // 110
|
|
// True -> 7
|
|
default:
|
|
assert(0 && "Invalid ICmp predicate!");
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/// getFCmpCode - Similar to getICmpCode but for FCmpInst. This encodes a fcmp
|
|
/// predicate into a three bit mask. It also returns whether it is an ordered
|
|
/// predicate by reference.
|
|
static unsigned getFCmpCode(FCmpInst::Predicate CC, bool &isOrdered) {
|
|
isOrdered = false;
|
|
switch (CC) {
|
|
case FCmpInst::FCMP_ORD: isOrdered = true; return 0; // 000
|
|
case FCmpInst::FCMP_UNO: return 0; // 000
|
|
case FCmpInst::FCMP_OGT: isOrdered = true; return 1; // 001
|
|
case FCmpInst::FCMP_UGT: return 1; // 001
|
|
case FCmpInst::FCMP_OEQ: isOrdered = true; return 2; // 010
|
|
case FCmpInst::FCMP_UEQ: return 2; // 010
|
|
case FCmpInst::FCMP_OGE: isOrdered = true; return 3; // 011
|
|
case FCmpInst::FCMP_UGE: return 3; // 011
|
|
case FCmpInst::FCMP_OLT: isOrdered = true; return 4; // 100
|
|
case FCmpInst::FCMP_ULT: return 4; // 100
|
|
case FCmpInst::FCMP_ONE: isOrdered = true; return 5; // 101
|
|
case FCmpInst::FCMP_UNE: return 5; // 101
|
|
case FCmpInst::FCMP_OLE: isOrdered = true; return 6; // 110
|
|
case FCmpInst::FCMP_ULE: return 6; // 110
|
|
// True -> 7
|
|
default:
|
|
// Not expecting FCMP_FALSE and FCMP_TRUE;
|
|
assert(0 && "Unexpected FCmp predicate!");
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/// getICmpValue - This is the complement of getICmpCode, which turns an
|
|
/// opcode and two operands into either a constant true or false, or a brand
|
|
/// new ICmp instruction. The sign is passed in to determine which kind
|
|
/// of predicate to use in the new icmp instruction.
|
|
static Value *getICmpValue(bool sign, unsigned code, Value *LHS, Value *RHS) {
|
|
switch (code) {
|
|
default: assert(0 && "Illegal ICmp code!");
|
|
case 0: return ConstantInt::getFalse();
|
|
case 1:
|
|
if (sign)
|
|
return new ICmpInst(ICmpInst::ICMP_SGT, LHS, RHS);
|
|
else
|
|
return new ICmpInst(ICmpInst::ICMP_UGT, LHS, RHS);
|
|
case 2: return new ICmpInst(ICmpInst::ICMP_EQ, LHS, RHS);
|
|
case 3:
|
|
if (sign)
|
|
return new ICmpInst(ICmpInst::ICMP_SGE, LHS, RHS);
|
|
else
|
|
return new ICmpInst(ICmpInst::ICMP_UGE, LHS, RHS);
|
|
case 4:
|
|
if (sign)
|
|
return new ICmpInst(ICmpInst::ICMP_SLT, LHS, RHS);
|
|
else
|
|
return new ICmpInst(ICmpInst::ICMP_ULT, LHS, RHS);
|
|
case 5: return new ICmpInst(ICmpInst::ICMP_NE, LHS, RHS);
|
|
case 6:
|
|
if (sign)
|
|
return new ICmpInst(ICmpInst::ICMP_SLE, LHS, RHS);
|
|
else
|
|
return new ICmpInst(ICmpInst::ICMP_ULE, LHS, RHS);
|
|
case 7: return ConstantInt::getTrue();
|
|
}
|
|
}
|
|
|
|
/// getFCmpValue - This is the complement of getFCmpCode, which turns an
|
|
/// opcode and two operands into either a FCmp instruction. isordered is passed
|
|
/// in to determine which kind of predicate to use in the new fcmp instruction.
|
|
static Value *getFCmpValue(bool isordered, unsigned code,
|
|
Value *LHS, Value *RHS) {
|
|
switch (code) {
|
|
default: assert(0 && "Illegal FCmp code!");
|
|
case 0:
|
|
if (isordered)
|
|
return new FCmpInst(FCmpInst::FCMP_ORD, LHS, RHS);
|
|
else
|
|
return new FCmpInst(FCmpInst::FCMP_UNO, LHS, RHS);
|
|
case 1:
|
|
if (isordered)
|
|
return new FCmpInst(FCmpInst::FCMP_OGT, LHS, RHS);
|
|
else
|
|
return new FCmpInst(FCmpInst::FCMP_UGT, LHS, RHS);
|
|
case 2:
|
|
if (isordered)
|
|
return new FCmpInst(FCmpInst::FCMP_OEQ, LHS, RHS);
|
|
else
|
|
return new FCmpInst(FCmpInst::FCMP_UEQ, LHS, RHS);
|
|
case 3:
|
|
if (isordered)
|
|
return new FCmpInst(FCmpInst::FCMP_OGE, LHS, RHS);
|
|
else
|
|
return new FCmpInst(FCmpInst::FCMP_UGE, LHS, RHS);
|
|
case 4:
|
|
if (isordered)
|
|
return new FCmpInst(FCmpInst::FCMP_OLT, LHS, RHS);
|
|
else
|
|
return new FCmpInst(FCmpInst::FCMP_ULT, LHS, RHS);
|
|
case 5:
|
|
if (isordered)
|
|
return new FCmpInst(FCmpInst::FCMP_ONE, LHS, RHS);
|
|
else
|
|
return new FCmpInst(FCmpInst::FCMP_UNE, LHS, RHS);
|
|
case 6:
|
|
if (isordered)
|
|
return new FCmpInst(FCmpInst::FCMP_OLE, LHS, RHS);
|
|
else
|
|
return new FCmpInst(FCmpInst::FCMP_ULE, LHS, RHS);
|
|
case 7: return ConstantInt::getTrue();
|
|
}
|
|
}
|
|
|
|
/// PredicatesFoldable - Return true if both predicates match sign or if at
|
|
/// least one of them is an equality comparison (which is signless).
|
|
static bool PredicatesFoldable(ICmpInst::Predicate p1, ICmpInst::Predicate p2) {
|
|
return (ICmpInst::isSignedPredicate(p1) == ICmpInst::isSignedPredicate(p2)) ||
|
|
(ICmpInst::isSignedPredicate(p1) && ICmpInst::isEquality(p2)) ||
|
|
(ICmpInst::isSignedPredicate(p2) && ICmpInst::isEquality(p1));
|
|
}
|
|
|
|
namespace {
|
|
// FoldICmpLogical - Implements (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
|
|
struct FoldICmpLogical {
|
|
InstCombiner &IC;
|
|
Value *LHS, *RHS;
|
|
ICmpInst::Predicate pred;
|
|
FoldICmpLogical(InstCombiner &ic, ICmpInst *ICI)
|
|
: IC(ic), LHS(ICI->getOperand(0)), RHS(ICI->getOperand(1)),
|
|
pred(ICI->getPredicate()) {}
|
|
bool shouldApply(Value *V) const {
|
|
if (ICmpInst *ICI = dyn_cast<ICmpInst>(V))
|
|
if (PredicatesFoldable(pred, ICI->getPredicate()))
|
|
return ((ICI->getOperand(0) == LHS && ICI->getOperand(1) == RHS) ||
|
|
(ICI->getOperand(0) == RHS && ICI->getOperand(1) == LHS));
|
|
return false;
|
|
}
|
|
Instruction *apply(Instruction &Log) const {
|
|
ICmpInst *ICI = cast<ICmpInst>(Log.getOperand(0));
|
|
if (ICI->getOperand(0) != LHS) {
|
|
assert(ICI->getOperand(1) == LHS);
|
|
ICI->swapOperands(); // Swap the LHS and RHS of the ICmp
|
|
}
|
|
|
|
ICmpInst *RHSICI = cast<ICmpInst>(Log.getOperand(1));
|
|
unsigned LHSCode = getICmpCode(ICI);
|
|
unsigned RHSCode = getICmpCode(RHSICI);
|
|
unsigned Code;
|
|
switch (Log.getOpcode()) {
|
|
case Instruction::And: Code = LHSCode & RHSCode; break;
|
|
case Instruction::Or: Code = LHSCode | RHSCode; break;
|
|
case Instruction::Xor: Code = LHSCode ^ RHSCode; break;
|
|
default: assert(0 && "Illegal logical opcode!"); return 0;
|
|
}
|
|
|
|
bool isSigned = ICmpInst::isSignedPredicate(RHSICI->getPredicate()) ||
|
|
ICmpInst::isSignedPredicate(ICI->getPredicate());
|
|
|
|
Value *RV = getICmpValue(isSigned, Code, LHS, RHS);
|
|
if (Instruction *I = dyn_cast<Instruction>(RV))
|
|
return I;
|
|
// Otherwise, it's a constant boolean value...
|
|
return IC.ReplaceInstUsesWith(Log, RV);
|
|
}
|
|
};
|
|
} // end anonymous namespace
|
|
|
|
// OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
|
|
// the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
|
|
// guaranteed to be a binary operator.
|
|
Instruction *InstCombiner::OptAndOp(Instruction *Op,
|
|
ConstantInt *OpRHS,
|
|
ConstantInt *AndRHS,
|
|
BinaryOperator &TheAnd) {
|
|
Value *X = Op->getOperand(0);
|
|
Constant *Together = 0;
|
|
if (!Op->isShift())
|
|
Together = And(AndRHS, OpRHS);
|
|
|
|
switch (Op->getOpcode()) {
|
|
case Instruction::Xor:
|
|
if (Op->hasOneUse()) {
|
|
// (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
|
|
Instruction *And = BinaryOperator::CreateAnd(X, AndRHS);
|
|
InsertNewInstBefore(And, TheAnd);
|
|
And->takeName(Op);
|
|
return BinaryOperator::CreateXor(And, Together);
|
|
}
|
|
break;
|
|
case Instruction::Or:
|
|
if (Together == AndRHS) // (X | C) & C --> C
|
|
return ReplaceInstUsesWith(TheAnd, AndRHS);
|
|
|
|
if (Op->hasOneUse() && Together != OpRHS) {
|
|
// (X | C1) & C2 --> (X | (C1&C2)) & C2
|
|
Instruction *Or = BinaryOperator::CreateOr(X, Together);
|
|
InsertNewInstBefore(Or, TheAnd);
|
|
Or->takeName(Op);
|
|
return BinaryOperator::CreateAnd(Or, AndRHS);
|
|
}
|
|
break;
|
|
case Instruction::Add:
|
|
if (Op->hasOneUse()) {
|
|
// Adding a one to a single bit bit-field should be turned into an XOR
|
|
// of the bit. First thing to check is to see if this AND is with a
|
|
// single bit constant.
|
|
const APInt& AndRHSV = cast<ConstantInt>(AndRHS)->getValue();
|
|
|
|
// If there is only one bit set...
|
|
if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
|
|
// Ok, at this point, we know that we are masking the result of the
|
|
// ADD down to exactly one bit. If the constant we are adding has
|
|
// no bits set below this bit, then we can eliminate the ADD.
|
|
const APInt& AddRHS = cast<ConstantInt>(OpRHS)->getValue();
|
|
|
|
// Check to see if any bits below the one bit set in AndRHSV are set.
|
|
if ((AddRHS & (AndRHSV-1)) == 0) {
|
|
// If not, the only thing that can effect the output of the AND is
|
|
// the bit specified by AndRHSV. If that bit is set, the effect of
|
|
// the XOR is to toggle the bit. If it is clear, then the ADD has
|
|
// no effect.
|
|
if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop
|
|
TheAnd.setOperand(0, X);
|
|
return &TheAnd;
|
|
} else {
|
|
// Pull the XOR out of the AND.
|
|
Instruction *NewAnd = BinaryOperator::CreateAnd(X, AndRHS);
|
|
InsertNewInstBefore(NewAnd, TheAnd);
|
|
NewAnd->takeName(Op);
|
|
return BinaryOperator::CreateXor(NewAnd, AndRHS);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
break;
|
|
|
|
case Instruction::Shl: {
|
|
// We know that the AND will not produce any of the bits shifted in, so if
|
|
// the anded constant includes them, clear them now!
|
|
//
|
|
uint32_t BitWidth = AndRHS->getType()->getBitWidth();
|
|
uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
|
|
APInt ShlMask(APInt::getHighBitsSet(BitWidth, BitWidth-OpRHSVal));
|
|
ConstantInt *CI = ConstantInt::get(AndRHS->getValue() & ShlMask);
|
|
|
|
if (CI->getValue() == ShlMask) {
|
|
// Masking out bits that the shift already masks
|
|
return ReplaceInstUsesWith(TheAnd, Op); // No need for the and.
|
|
} else if (CI != AndRHS) { // Reducing bits set in and.
|
|
TheAnd.setOperand(1, CI);
|
|
return &TheAnd;
|
|
}
|
|
break;
|
|
}
|
|
case Instruction::LShr:
|
|
{
|
|
// We know that the AND will not produce any of the bits shifted in, so if
|
|
// the anded constant includes them, clear them now! This only applies to
|
|
// unsigned shifts, because a signed shr may bring in set bits!
|
|
//
|
|
uint32_t BitWidth = AndRHS->getType()->getBitWidth();
|
|
uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
|
|
APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
|
|
ConstantInt *CI = ConstantInt::get(AndRHS->getValue() & ShrMask);
|
|
|
|
if (CI->getValue() == ShrMask) {
|
|
// Masking out bits that the shift already masks.
|
|
return ReplaceInstUsesWith(TheAnd, Op);
|
|
} else if (CI != AndRHS) {
|
|
TheAnd.setOperand(1, CI); // Reduce bits set in and cst.
|
|
return &TheAnd;
|
|
}
|
|
break;
|
|
}
|
|
case Instruction::AShr:
|
|
// Signed shr.
|
|
// See if this is shifting in some sign extension, then masking it out
|
|
// with an and.
|
|
if (Op->hasOneUse()) {
|
|
uint32_t BitWidth = AndRHS->getType()->getBitWidth();
|
|
uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth);
|
|
APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal));
|
|
Constant *C = ConstantInt::get(AndRHS->getValue() & ShrMask);
|
|
if (C == AndRHS) { // Masking out bits shifted in.
|
|
// (Val ashr C1) & C2 -> (Val lshr C1) & C2
|
|
// Make the argument unsigned.
|
|
Value *ShVal = Op->getOperand(0);
|
|
ShVal = InsertNewInstBefore(
|
|
BinaryOperator::CreateLShr(ShVal, OpRHS,
|
|
Op->getName()), TheAnd);
|
|
return BinaryOperator::CreateAnd(ShVal, AndRHS, TheAnd.getName());
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
|
|
/// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is
|
|
/// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient
|
|
/// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. isSigned indicates
|
|
/// whether to treat the V, Lo and HI as signed or not. IB is the location to
|
|
/// insert new instructions.
|
|
Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
|
|
bool isSigned, bool Inside,
|
|
Instruction &IB) {
|
|
assert(cast<ConstantInt>(ConstantExpr::getICmp((isSigned ?
|
|
ICmpInst::ICMP_SLE:ICmpInst::ICMP_ULE), Lo, Hi))->getZExtValue() &&
|
|
"Lo is not <= Hi in range emission code!");
|
|
|
|
if (Inside) {
|
|
if (Lo == Hi) // Trivially false.
|
|
return new ICmpInst(ICmpInst::ICMP_NE, V, V);
|
|
|
|
// V >= Min && V < Hi --> V < Hi
|
|
if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
|
|
ICmpInst::Predicate pred = (isSigned ?
|
|
ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT);
|
|
return new ICmpInst(pred, V, Hi);
|
|
}
|
|
|
|
// Emit V-Lo <u Hi-Lo
|
|
Constant *NegLo = ConstantExpr::getNeg(Lo);
|
|
Instruction *Add = BinaryOperator::CreateAdd(V, NegLo, V->getName()+".off");
|
|
InsertNewInstBefore(Add, IB);
|
|
Constant *UpperBound = ConstantExpr::getAdd(NegLo, Hi);
|
|
return new ICmpInst(ICmpInst::ICMP_ULT, Add, UpperBound);
|
|
}
|
|
|
|
if (Lo == Hi) // Trivially true.
|
|
return new ICmpInst(ICmpInst::ICMP_EQ, V, V);
|
|
|
|
// V < Min || V >= Hi -> V > Hi-1
|
|
Hi = SubOne(cast<ConstantInt>(Hi));
|
|
if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) {
|
|
ICmpInst::Predicate pred = (isSigned ?
|
|
ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT);
|
|
return new ICmpInst(pred, V, Hi);
|
|
}
|
|
|
|
// Emit V-Lo >u Hi-1-Lo
|
|
// Note that Hi has already had one subtracted from it, above.
|
|
ConstantInt *NegLo = cast<ConstantInt>(ConstantExpr::getNeg(Lo));
|
|
Instruction *Add = BinaryOperator::CreateAdd(V, NegLo, V->getName()+".off");
|
|
InsertNewInstBefore(Add, IB);
|
|
Constant *LowerBound = ConstantExpr::getAdd(NegLo, Hi);
|
|
return new ICmpInst(ICmpInst::ICMP_UGT, Add, LowerBound);
|
|
}
|
|
|
|
// isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with
|
|
// any number of 0s on either side. The 1s are allowed to wrap from LSB to
|
|
// MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is
|
|
// not, since all 1s are not contiguous.
|
|
static bool isRunOfOnes(ConstantInt *Val, uint32_t &MB, uint32_t &ME) {
|
|
const APInt& V = Val->getValue();
|
|
uint32_t BitWidth = Val->getType()->getBitWidth();
|
|
if (!APIntOps::isShiftedMask(BitWidth, V)) return false;
|
|
|
|
// look for the first zero bit after the run of ones
|
|
MB = BitWidth - ((V - 1) ^ V).countLeadingZeros();
|
|
// look for the first non-zero bit
|
|
ME = V.getActiveBits();
|
|
return true;
|
|
}
|
|
|
|
/// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask,
|
|
/// where isSub determines whether the operator is a sub. If we can fold one of
|
|
/// the following xforms:
|
|
///
|
|
/// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
|
|
/// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
|
|
/// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
|
|
///
|
|
/// return (A +/- B).
|
|
///
|
|
Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
|
|
ConstantInt *Mask, bool isSub,
|
|
Instruction &I) {
|
|
Instruction *LHSI = dyn_cast<Instruction>(LHS);
|
|
if (!LHSI || LHSI->getNumOperands() != 2 ||
|
|
!isa<ConstantInt>(LHSI->getOperand(1))) return 0;
|
|
|
|
ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
|
|
|
|
switch (LHSI->getOpcode()) {
|
|
default: return 0;
|
|
case Instruction::And:
|
|
if (And(N, Mask) == Mask) {
|
|
// If the AndRHS is a power of two minus one (0+1+), this is simple.
|
|
if ((Mask->getValue().countLeadingZeros() +
|
|
Mask->getValue().countPopulation()) ==
|
|
Mask->getValue().getBitWidth())
|
|
break;
|
|
|
|
// Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
|
|
// part, we don't need any explicit masks to take them out of A. If that
|
|
// is all N is, ignore it.
|
|
uint32_t MB = 0, ME = 0;
|
|
if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
|
|
uint32_t BitWidth = cast<IntegerType>(RHS->getType())->getBitWidth();
|
|
APInt Mask(APInt::getLowBitsSet(BitWidth, MB-1));
|
|
if (MaskedValueIsZero(RHS, Mask))
|
|
break;
|
|
}
|
|
}
|
|
return 0;
|
|
case Instruction::Or:
|
|
case Instruction::Xor:
|
|
// If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
|
|
if ((Mask->getValue().countLeadingZeros() +
|
|
Mask->getValue().countPopulation()) == Mask->getValue().getBitWidth()
|
|
&& And(N, Mask)->isZero())
|
|
break;
|
|
return 0;
|
|
}
|
|
|
|
Instruction *New;
|
|
if (isSub)
|
|
New = BinaryOperator::CreateSub(LHSI->getOperand(0), RHS, "fold");
|
|
else
|
|
New = BinaryOperator::CreateAdd(LHSI->getOperand(0), RHS, "fold");
|
|
return InsertNewInstBefore(New, I);
|
|
}
|
|
|
|
/// FoldAndOfICmps - Fold (icmp)&(icmp) if possible.
|
|
Instruction *InstCombiner::FoldAndOfICmps(Instruction &I,
|
|
ICmpInst *LHS, ICmpInst *RHS) {
|
|
Value *Val, *Val2;
|
|
ConstantInt *LHSCst, *RHSCst;
|
|
ICmpInst::Predicate LHSCC, RHSCC;
|
|
|
|
// This only handles icmp of constants: (icmp1 A, C1) & (icmp2 B, C2).
|
|
if (!match(LHS, m_ICmp(LHSCC, m_Value(Val), m_ConstantInt(LHSCst))) ||
|
|
!match(RHS, m_ICmp(RHSCC, m_Value(Val2), m_ConstantInt(RHSCst))))
|
|
return 0;
|
|
|
|
// (icmp ult A, C) & (icmp ult B, C) --> (icmp ult (A|B), C)
|
|
// where C is a power of 2
|
|
if (LHSCst == RHSCst && LHSCC == RHSCC && LHSCC == ICmpInst::ICMP_ULT &&
|
|
LHSCst->getValue().isPowerOf2()) {
|
|
Instruction *NewOr = BinaryOperator::CreateOr(Val, Val2);
|
|
InsertNewInstBefore(NewOr, I);
|
|
return new ICmpInst(LHSCC, NewOr, LHSCst);
|
|
}
|
|
|
|
// From here on, we only handle:
|
|
// (icmp1 A, C1) & (icmp2 A, C2) --> something simpler.
|
|
if (Val != Val2) return 0;
|
|
|
|
// ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere.
|
|
if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE ||
|
|
RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE ||
|
|
LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE ||
|
|
RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE)
|
|
return 0;
|
|
|
|
// We can't fold (ugt x, C) & (sgt x, C2).
|
|
if (!PredicatesFoldable(LHSCC, RHSCC))
|
|
return 0;
|
|
|
|
// Ensure that the larger constant is on the RHS.
|
|
bool ShouldSwap;
|
|
if (ICmpInst::isSignedPredicate(LHSCC) ||
|
|
(ICmpInst::isEquality(LHSCC) &&
|
|
ICmpInst::isSignedPredicate(RHSCC)))
|
|
ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue());
|
|
else
|
|
ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue());
|
|
|
|
if (ShouldSwap) {
|
|
std::swap(LHS, RHS);
|
|
std::swap(LHSCst, RHSCst);
|
|
std::swap(LHSCC, RHSCC);
|
|
}
|
|
|
|
// At this point, we know we have have two icmp instructions
|
|
// comparing a value against two constants and and'ing the result
|
|
// together. Because of the above check, we know that we only have
|
|
// icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know
|
|
// (from the FoldICmpLogical check above), that the two constants
|
|
// are not equal and that the larger constant is on the RHS
|
|
assert(LHSCst != RHSCst && "Compares not folded above?");
|
|
|
|
switch (LHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case ICmpInst::ICMP_EQ:
|
|
switch (RHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case ICmpInst::ICMP_EQ: // (X == 13 & X == 15) -> false
|
|
case ICmpInst::ICMP_UGT: // (X == 13 & X > 15) -> false
|
|
case ICmpInst::ICMP_SGT: // (X == 13 & X > 15) -> false
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
case ICmpInst::ICMP_NE: // (X == 13 & X != 15) -> X == 13
|
|
case ICmpInst::ICMP_ULT: // (X == 13 & X < 15) -> X == 13
|
|
case ICmpInst::ICMP_SLT: // (X == 13 & X < 15) -> X == 13
|
|
return ReplaceInstUsesWith(I, LHS);
|
|
}
|
|
case ICmpInst::ICMP_NE:
|
|
switch (RHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case ICmpInst::ICMP_ULT:
|
|
if (LHSCst == SubOne(RHSCst)) // (X != 13 & X u< 14) -> X < 13
|
|
return new ICmpInst(ICmpInst::ICMP_ULT, Val, LHSCst);
|
|
break; // (X != 13 & X u< 15) -> no change
|
|
case ICmpInst::ICMP_SLT:
|
|
if (LHSCst == SubOne(RHSCst)) // (X != 13 & X s< 14) -> X < 13
|
|
return new ICmpInst(ICmpInst::ICMP_SLT, Val, LHSCst);
|
|
break; // (X != 13 & X s< 15) -> no change
|
|
case ICmpInst::ICMP_EQ: // (X != 13 & X == 15) -> X == 15
|
|
case ICmpInst::ICMP_UGT: // (X != 13 & X u> 15) -> X u> 15
|
|
case ICmpInst::ICMP_SGT: // (X != 13 & X s> 15) -> X s> 15
|
|
return ReplaceInstUsesWith(I, RHS);
|
|
case ICmpInst::ICMP_NE:
|
|
if (LHSCst == SubOne(RHSCst)){// (X != 13 & X != 14) -> X-13 >u 1
|
|
Constant *AddCST = ConstantExpr::getNeg(LHSCst);
|
|
Instruction *Add = BinaryOperator::CreateAdd(Val, AddCST,
|
|
Val->getName()+".off");
|
|
InsertNewInstBefore(Add, I);
|
|
return new ICmpInst(ICmpInst::ICMP_UGT, Add,
|
|
ConstantInt::get(Add->getType(), 1));
|
|
}
|
|
break; // (X != 13 & X != 15) -> no change
|
|
}
|
|
break;
|
|
case ICmpInst::ICMP_ULT:
|
|
switch (RHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case ICmpInst::ICMP_EQ: // (X u< 13 & X == 15) -> false
|
|
case ICmpInst::ICMP_UGT: // (X u< 13 & X u> 15) -> false
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
case ICmpInst::ICMP_SGT: // (X u< 13 & X s> 15) -> no change
|
|
break;
|
|
case ICmpInst::ICMP_NE: // (X u< 13 & X != 15) -> X u< 13
|
|
case ICmpInst::ICMP_ULT: // (X u< 13 & X u< 15) -> X u< 13
|
|
return ReplaceInstUsesWith(I, LHS);
|
|
case ICmpInst::ICMP_SLT: // (X u< 13 & X s< 15) -> no change
|
|
break;
|
|
}
|
|
break;
|
|
case ICmpInst::ICMP_SLT:
|
|
switch (RHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case ICmpInst::ICMP_EQ: // (X s< 13 & X == 15) -> false
|
|
case ICmpInst::ICMP_SGT: // (X s< 13 & X s> 15) -> false
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
case ICmpInst::ICMP_UGT: // (X s< 13 & X u> 15) -> no change
|
|
break;
|
|
case ICmpInst::ICMP_NE: // (X s< 13 & X != 15) -> X < 13
|
|
case ICmpInst::ICMP_SLT: // (X s< 13 & X s< 15) -> X < 13
|
|
return ReplaceInstUsesWith(I, LHS);
|
|
case ICmpInst::ICMP_ULT: // (X s< 13 & X u< 15) -> no change
|
|
break;
|
|
}
|
|
break;
|
|
case ICmpInst::ICMP_UGT:
|
|
switch (RHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case ICmpInst::ICMP_EQ: // (X u> 13 & X == 15) -> X == 15
|
|
case ICmpInst::ICMP_UGT: // (X u> 13 & X u> 15) -> X u> 15
|
|
return ReplaceInstUsesWith(I, RHS);
|
|
case ICmpInst::ICMP_SGT: // (X u> 13 & X s> 15) -> no change
|
|
break;
|
|
case ICmpInst::ICMP_NE:
|
|
if (RHSCst == AddOne(LHSCst)) // (X u> 13 & X != 14) -> X u> 14
|
|
return new ICmpInst(LHSCC, Val, RHSCst);
|
|
break; // (X u> 13 & X != 15) -> no change
|
|
case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) -> (X-14) <u 1
|
|
return InsertRangeTest(Val, AddOne(LHSCst), RHSCst, false, true, I);
|
|
case ICmpInst::ICMP_SLT: // (X u> 13 & X s< 15) -> no change
|
|
break;
|
|
}
|
|
break;
|
|
case ICmpInst::ICMP_SGT:
|
|
switch (RHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case ICmpInst::ICMP_EQ: // (X s> 13 & X == 15) -> X == 15
|
|
case ICmpInst::ICMP_SGT: // (X s> 13 & X s> 15) -> X s> 15
|
|
return ReplaceInstUsesWith(I, RHS);
|
|
case ICmpInst::ICMP_UGT: // (X s> 13 & X u> 15) -> no change
|
|
break;
|
|
case ICmpInst::ICMP_NE:
|
|
if (RHSCst == AddOne(LHSCst)) // (X s> 13 & X != 14) -> X s> 14
|
|
return new ICmpInst(LHSCC, Val, RHSCst);
|
|
break; // (X s> 13 & X != 15) -> no change
|
|
case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) -> (X-14) s< 1
|
|
return InsertRangeTest(Val, AddOne(LHSCst), RHSCst, true, true, I);
|
|
case ICmpInst::ICMP_ULT: // (X s> 13 & X u< 15) -> no change
|
|
break;
|
|
}
|
|
break;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
|
|
bool Changed = SimplifyCommutative(I);
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
if (isa<UndefValue>(Op1)) // X & undef -> 0
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
|
|
// and X, X = X
|
|
if (Op0 == Op1)
|
|
return ReplaceInstUsesWith(I, Op1);
|
|
|
|
// See if we can simplify any instructions used by the instruction whose sole
|
|
// purpose is to compute bits we don't care about.
|
|
if (!isa<VectorType>(I.getType())) {
|
|
if (SimplifyDemandedInstructionBits(I))
|
|
return &I;
|
|
} else {
|
|
if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1)) {
|
|
if (CP->isAllOnesValue()) // X & <-1,-1> -> X
|
|
return ReplaceInstUsesWith(I, I.getOperand(0));
|
|
} else if (isa<ConstantAggregateZero>(Op1)) {
|
|
return ReplaceInstUsesWith(I, Op1); // X & <0,0> -> <0,0>
|
|
}
|
|
}
|
|
|
|
if (ConstantInt *AndRHS = dyn_cast<ConstantInt>(Op1)) {
|
|
const APInt& AndRHSMask = AndRHS->getValue();
|
|
APInt NotAndRHS(~AndRHSMask);
|
|
|
|
// Optimize a variety of ((val OP C1) & C2) combinations...
|
|
if (isa<BinaryOperator>(Op0)) {
|
|
Instruction *Op0I = cast<Instruction>(Op0);
|
|
Value *Op0LHS = Op0I->getOperand(0);
|
|
Value *Op0RHS = Op0I->getOperand(1);
|
|
switch (Op0I->getOpcode()) {
|
|
case Instruction::Xor:
|
|
case Instruction::Or:
|
|
// If the mask is only needed on one incoming arm, push it up.
|
|
if (Op0I->hasOneUse()) {
|
|
if (MaskedValueIsZero(Op0LHS, NotAndRHS)) {
|
|
// Not masking anything out for the LHS, move to RHS.
|
|
Instruction *NewRHS = BinaryOperator::CreateAnd(Op0RHS, AndRHS,
|
|
Op0RHS->getName()+".masked");
|
|
InsertNewInstBefore(NewRHS, I);
|
|
return BinaryOperator::Create(
|
|
cast<BinaryOperator>(Op0I)->getOpcode(), Op0LHS, NewRHS);
|
|
}
|
|
if (!isa<Constant>(Op0RHS) &&
|
|
MaskedValueIsZero(Op0RHS, NotAndRHS)) {
|
|
// Not masking anything out for the RHS, move to LHS.
|
|
Instruction *NewLHS = BinaryOperator::CreateAnd(Op0LHS, AndRHS,
|
|
Op0LHS->getName()+".masked");
|
|
InsertNewInstBefore(NewLHS, I);
|
|
return BinaryOperator::Create(
|
|
cast<BinaryOperator>(Op0I)->getOpcode(), NewLHS, Op0RHS);
|
|
}
|
|
}
|
|
|
|
break;
|
|
case Instruction::Add:
|
|
// ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
|
|
// ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
|
|
// ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
|
|
if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
|
|
return BinaryOperator::CreateAnd(V, AndRHS);
|
|
if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
|
|
return BinaryOperator::CreateAnd(V, AndRHS); // Add commutes
|
|
break;
|
|
|
|
case Instruction::Sub:
|
|
// ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
|
|
// ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
|
|
// ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
|
|
if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
|
|
return BinaryOperator::CreateAnd(V, AndRHS);
|
|
|
|
// (A - N) & AndRHS -> -N & AndRHS iff A&AndRHS==0 and AndRHS
|
|
// has 1's for all bits that the subtraction with A might affect.
|
|
if (Op0I->hasOneUse()) {
|
|
uint32_t BitWidth = AndRHSMask.getBitWidth();
|
|
uint32_t Zeros = AndRHSMask.countLeadingZeros();
|
|
APInt Mask = APInt::getLowBitsSet(BitWidth, BitWidth - Zeros);
|
|
|
|
ConstantInt *A = dyn_cast<ConstantInt>(Op0LHS);
|
|
if (!(A && A->isZero()) && // avoid infinite recursion.
|
|
MaskedValueIsZero(Op0LHS, Mask)) {
|
|
Instruction *NewNeg = BinaryOperator::CreateNeg(Op0RHS);
|
|
InsertNewInstBefore(NewNeg, I);
|
|
return BinaryOperator::CreateAnd(NewNeg, AndRHS);
|
|
}
|
|
}
|
|
break;
|
|
|
|
case Instruction::Shl:
|
|
case Instruction::LShr:
|
|
// (1 << x) & 1 --> zext(x == 0)
|
|
// (1 >> x) & 1 --> zext(x == 0)
|
|
if (AndRHSMask == 1 && Op0LHS == AndRHS) {
|
|
Instruction *NewICmp = new ICmpInst(ICmpInst::ICMP_EQ, Op0RHS,
|
|
Constant::getNullValue(I.getType()));
|
|
InsertNewInstBefore(NewICmp, I);
|
|
return new ZExtInst(NewICmp, I.getType());
|
|
}
|
|
break;
|
|
}
|
|
|
|
if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
|
|
if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
|
|
return Res;
|
|
} else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
|
|
// If this is an integer truncation or change from signed-to-unsigned, and
|
|
// if the source is an and/or with immediate, transform it. This
|
|
// frequently occurs for bitfield accesses.
|
|
if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) {
|
|
if ((isa<TruncInst>(CI) || isa<BitCastInst>(CI)) &&
|
|
CastOp->getNumOperands() == 2)
|
|
if (ConstantInt *AndCI = dyn_cast<ConstantInt>(CastOp->getOperand(1))) {
|
|
if (CastOp->getOpcode() == Instruction::And) {
|
|
// Change: and (cast (and X, C1) to T), C2
|
|
// into : and (cast X to T), trunc_or_bitcast(C1)&C2
|
|
// This will fold the two constants together, which may allow
|
|
// other simplifications.
|
|
Instruction *NewCast = CastInst::CreateTruncOrBitCast(
|
|
CastOp->getOperand(0), I.getType(),
|
|
CastOp->getName()+".shrunk");
|
|
NewCast = InsertNewInstBefore(NewCast, I);
|
|
// trunc_or_bitcast(C1)&C2
|
|
Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType());
|
|
C3 = ConstantExpr::getAnd(C3, AndRHS);
|
|
return BinaryOperator::CreateAnd(NewCast, C3);
|
|
} else if (CastOp->getOpcode() == Instruction::Or) {
|
|
// Change: and (cast (or X, C1) to T), C2
|
|
// into : trunc(C1)&C2 iff trunc(C1)&C2 == C2
|
|
Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType());
|
|
if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS) // trunc(C1)&C2
|
|
return ReplaceInstUsesWith(I, AndRHS);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Try to fold constant and into select arguments.
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
|
|
if (Instruction *R = FoldOpIntoSelect(I, SI, this))
|
|
return R;
|
|
if (isa<PHINode>(Op0))
|
|
if (Instruction *NV = FoldOpIntoPhi(I))
|
|
return NV;
|
|
}
|
|
|
|
Value *Op0NotVal = dyn_castNotVal(Op0);
|
|
Value *Op1NotVal = dyn_castNotVal(Op1);
|
|
|
|
if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
|
|
// (~A & ~B) == (~(A | B)) - De Morgan's Law
|
|
if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
|
|
Instruction *Or = BinaryOperator::CreateOr(Op0NotVal, Op1NotVal,
|
|
I.getName()+".demorgan");
|
|
InsertNewInstBefore(Or, I);
|
|
return BinaryOperator::CreateNot(Or);
|
|
}
|
|
|
|
{
|
|
Value *A = 0, *B = 0, *C = 0, *D = 0;
|
|
if (match(Op0, m_Or(m_Value(A), m_Value(B)))) {
|
|
if (A == Op1 || B == Op1) // (A | ?) & A --> A
|
|
return ReplaceInstUsesWith(I, Op1);
|
|
|
|
// (A|B) & ~(A&B) -> A^B
|
|
if (match(Op1, m_Not(m_And(m_Value(C), m_Value(D))))) {
|
|
if ((A == C && B == D) || (A == D && B == C))
|
|
return BinaryOperator::CreateXor(A, B);
|
|
}
|
|
}
|
|
|
|
if (match(Op1, m_Or(m_Value(A), m_Value(B)))) {
|
|
if (A == Op0 || B == Op0) // A & (A | ?) --> A
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
|
|
// ~(A&B) & (A|B) -> A^B
|
|
if (match(Op0, m_Not(m_And(m_Value(C), m_Value(D))))) {
|
|
if ((A == C && B == D) || (A == D && B == C))
|
|
return BinaryOperator::CreateXor(A, B);
|
|
}
|
|
}
|
|
|
|
if (Op0->hasOneUse() &&
|
|
match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
|
|
if (A == Op1) { // (A^B)&A -> A&(A^B)
|
|
I.swapOperands(); // Simplify below
|
|
std::swap(Op0, Op1);
|
|
} else if (B == Op1) { // (A^B)&B -> B&(B^A)
|
|
cast<BinaryOperator>(Op0)->swapOperands();
|
|
I.swapOperands(); // Simplify below
|
|
std::swap(Op0, Op1);
|
|
}
|
|
}
|
|
|
|
if (Op1->hasOneUse() &&
|
|
match(Op1, m_Xor(m_Value(A), m_Value(B)))) {
|
|
if (B == Op0) { // B&(A^B) -> B&(B^A)
|
|
cast<BinaryOperator>(Op1)->swapOperands();
|
|
std::swap(A, B);
|
|
}
|
|
if (A == Op0) { // A&(A^B) -> A & ~B
|
|
Instruction *NotB = BinaryOperator::CreateNot(B, "tmp");
|
|
InsertNewInstBefore(NotB, I);
|
|
return BinaryOperator::CreateAnd(A, NotB);
|
|
}
|
|
}
|
|
|
|
// (A&((~A)|B)) -> A&B
|
|
if (match(Op0, m_Or(m_Not(m_Specific(Op1)), m_Value(A))) ||
|
|
match(Op0, m_Or(m_Value(A), m_Not(m_Specific(Op1)))))
|
|
return BinaryOperator::CreateAnd(A, Op1);
|
|
if (match(Op1, m_Or(m_Not(m_Specific(Op0)), m_Value(A))) ||
|
|
match(Op1, m_Or(m_Value(A), m_Not(m_Specific(Op0)))))
|
|
return BinaryOperator::CreateAnd(A, Op0);
|
|
}
|
|
|
|
if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1)) {
|
|
// (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B)
|
|
if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
|
|
return R;
|
|
|
|
if (ICmpInst *LHS = dyn_cast<ICmpInst>(Op0))
|
|
if (Instruction *Res = FoldAndOfICmps(I, LHS, RHS))
|
|
return Res;
|
|
}
|
|
|
|
// fold (and (cast A), (cast B)) -> (cast (and A, B))
|
|
if (CastInst *Op0C = dyn_cast<CastInst>(Op0))
|
|
if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
|
|
if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind ?
|
|
const Type *SrcTy = Op0C->getOperand(0)->getType();
|
|
if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
|
|
// Only do this if the casts both really cause code to be generated.
|
|
ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
|
|
I.getType(), TD) &&
|
|
ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
|
|
I.getType(), TD)) {
|
|
Instruction *NewOp = BinaryOperator::CreateAnd(Op0C->getOperand(0),
|
|
Op1C->getOperand(0),
|
|
I.getName());
|
|
InsertNewInstBefore(NewOp, I);
|
|
return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
|
|
}
|
|
}
|
|
|
|
// (X >> Z) & (Y >> Z) -> (X&Y) >> Z for all shifts.
|
|
if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
|
|
if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
|
|
if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
|
|
SI0->getOperand(1) == SI1->getOperand(1) &&
|
|
(SI0->hasOneUse() || SI1->hasOneUse())) {
|
|
Instruction *NewOp =
|
|
InsertNewInstBefore(BinaryOperator::CreateAnd(SI0->getOperand(0),
|
|
SI1->getOperand(0),
|
|
SI0->getName()), I);
|
|
return BinaryOperator::Create(SI1->getOpcode(), NewOp,
|
|
SI1->getOperand(1));
|
|
}
|
|
}
|
|
|
|
// If and'ing two fcmp, try combine them into one.
|
|
if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) {
|
|
if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1))) {
|
|
if (LHS->getPredicate() == FCmpInst::FCMP_ORD &&
|
|
RHS->getPredicate() == FCmpInst::FCMP_ORD) {
|
|
// (fcmp ord x, c) & (fcmp ord y, c) -> (fcmp ord x, y)
|
|
if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
|
|
if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
|
|
// If either of the constants are nans, then the whole thing returns
|
|
// false.
|
|
if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
return new FCmpInst(FCmpInst::FCMP_ORD, LHS->getOperand(0),
|
|
RHS->getOperand(0));
|
|
}
|
|
} else {
|
|
Value *Op0LHS, *Op0RHS, *Op1LHS, *Op1RHS;
|
|
FCmpInst::Predicate Op0CC, Op1CC;
|
|
if (match(Op0, m_FCmp(Op0CC, m_Value(Op0LHS), m_Value(Op0RHS))) &&
|
|
match(Op1, m_FCmp(Op1CC, m_Value(Op1LHS), m_Value(Op1RHS)))) {
|
|
if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) {
|
|
// Swap RHS operands to match LHS.
|
|
Op1CC = FCmpInst::getSwappedPredicate(Op1CC);
|
|
std::swap(Op1LHS, Op1RHS);
|
|
}
|
|
if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) {
|
|
// Simplify (fcmp cc0 x, y) & (fcmp cc1 x, y).
|
|
if (Op0CC == Op1CC)
|
|
return new FCmpInst((FCmpInst::Predicate)Op0CC, Op0LHS, Op0RHS);
|
|
else if (Op0CC == FCmpInst::FCMP_FALSE ||
|
|
Op1CC == FCmpInst::FCMP_FALSE)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
else if (Op0CC == FCmpInst::FCMP_TRUE)
|
|
return ReplaceInstUsesWith(I, Op1);
|
|
else if (Op1CC == FCmpInst::FCMP_TRUE)
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
bool Op0Ordered;
|
|
bool Op1Ordered;
|
|
unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered);
|
|
unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered);
|
|
if (Op1Pred == 0) {
|
|
std::swap(Op0, Op1);
|
|
std::swap(Op0Pred, Op1Pred);
|
|
std::swap(Op0Ordered, Op1Ordered);
|
|
}
|
|
if (Op0Pred == 0) {
|
|
// uno && ueq -> uno && (uno || eq) -> ueq
|
|
// ord && olt -> ord && (ord && lt) -> olt
|
|
if (Op0Ordered == Op1Ordered)
|
|
return ReplaceInstUsesWith(I, Op1);
|
|
// uno && oeq -> uno && (ord && eq) -> false
|
|
// uno && ord -> false
|
|
if (!Op0Ordered)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
// ord && ueq -> ord && (uno || eq) -> oeq
|
|
return cast<Instruction>(getFCmpValue(true, Op1Pred,
|
|
Op0LHS, Op0RHS));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return Changed ? &I : 0;
|
|
}
|
|
|
|
/// CollectBSwapParts - Analyze the specified subexpression and see if it is
|
|
/// capable of providing pieces of a bswap. The subexpression provides pieces
|
|
/// of a bswap if it is proven that each of the non-zero bytes in the output of
|
|
/// the expression came from the corresponding "byte swapped" byte in some other
|
|
/// value. For example, if the current subexpression is "(shl i32 %X, 24)" then
|
|
/// we know that the expression deposits the low byte of %X into the high byte
|
|
/// of the bswap result and that all other bytes are zero. This expression is
|
|
/// accepted, the high byte of ByteValues is set to X to indicate a correct
|
|
/// match.
|
|
///
|
|
/// This function returns true if the match was unsuccessful and false if so.
|
|
/// On entry to the function the "OverallLeftShift" is a signed integer value
|
|
/// indicating the number of bytes that the subexpression is later shifted. For
|
|
/// example, if the expression is later right shifted by 16 bits, the
|
|
/// OverallLeftShift value would be -2 on entry. This is used to specify which
|
|
/// byte of ByteValues is actually being set.
|
|
///
|
|
/// Similarly, ByteMask is a bitmask where a bit is clear if its corresponding
|
|
/// byte is masked to zero by a user. For example, in (X & 255), X will be
|
|
/// processed with a bytemask of 1. Because bytemask is 32-bits, this limits
|
|
/// this function to working on up to 32-byte (256 bit) values. ByteMask is
|
|
/// always in the local (OverallLeftShift) coordinate space.
|
|
///
|
|
static bool CollectBSwapParts(Value *V, int OverallLeftShift, uint32_t ByteMask,
|
|
SmallVector<Value*, 8> &ByteValues) {
|
|
if (Instruction *I = dyn_cast<Instruction>(V)) {
|
|
// If this is an or instruction, it may be an inner node of the bswap.
|
|
if (I->getOpcode() == Instruction::Or) {
|
|
return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
|
|
ByteValues) ||
|
|
CollectBSwapParts(I->getOperand(1), OverallLeftShift, ByteMask,
|
|
ByteValues);
|
|
}
|
|
|
|
// If this is a logical shift by a constant multiple of 8, recurse with
|
|
// OverallLeftShift and ByteMask adjusted.
|
|
if (I->isLogicalShift() && isa<ConstantInt>(I->getOperand(1))) {
|
|
unsigned ShAmt =
|
|
cast<ConstantInt>(I->getOperand(1))->getLimitedValue(~0U);
|
|
// Ensure the shift amount is defined and of a byte value.
|
|
if ((ShAmt & 7) || (ShAmt > 8*ByteValues.size()))
|
|
return true;
|
|
|
|
unsigned ByteShift = ShAmt >> 3;
|
|
if (I->getOpcode() == Instruction::Shl) {
|
|
// X << 2 -> collect(X, +2)
|
|
OverallLeftShift += ByteShift;
|
|
ByteMask >>= ByteShift;
|
|
} else {
|
|
// X >>u 2 -> collect(X, -2)
|
|
OverallLeftShift -= ByteShift;
|
|
ByteMask <<= ByteShift;
|
|
ByteMask &= (~0U >> (32-ByteValues.size()));
|
|
}
|
|
|
|
if (OverallLeftShift >= (int)ByteValues.size()) return true;
|
|
if (OverallLeftShift <= -(int)ByteValues.size()) return true;
|
|
|
|
return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
|
|
ByteValues);
|
|
}
|
|
|
|
// If this is a logical 'and' with a mask that clears bytes, clear the
|
|
// corresponding bytes in ByteMask.
|
|
if (I->getOpcode() == Instruction::And &&
|
|
isa<ConstantInt>(I->getOperand(1))) {
|
|
// Scan every byte of the and mask, seeing if the byte is either 0 or 255.
|
|
unsigned NumBytes = ByteValues.size();
|
|
APInt Byte(I->getType()->getPrimitiveSizeInBits(), 255);
|
|
const APInt &AndMask = cast<ConstantInt>(I->getOperand(1))->getValue();
|
|
|
|
for (unsigned i = 0; i != NumBytes; ++i, Byte <<= 8) {
|
|
// If this byte is masked out by a later operation, we don't care what
|
|
// the and mask is.
|
|
if ((ByteMask & (1 << i)) == 0)
|
|
continue;
|
|
|
|
// If the AndMask is all zeros for this byte, clear the bit.
|
|
APInt MaskB = AndMask & Byte;
|
|
if (MaskB == 0) {
|
|
ByteMask &= ~(1U << i);
|
|
continue;
|
|
}
|
|
|
|
// If the AndMask is not all ones for this byte, it's not a bytezap.
|
|
if (MaskB != Byte)
|
|
return true;
|
|
|
|
// Otherwise, this byte is kept.
|
|
}
|
|
|
|
return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask,
|
|
ByteValues);
|
|
}
|
|
}
|
|
|
|
// Okay, we got to something that isn't a shift, 'or' or 'and'. This must be
|
|
// the input value to the bswap. Some observations: 1) if more than one byte
|
|
// is demanded from this input, then it could not be successfully assembled
|
|
// into a byteswap. At least one of the two bytes would not be aligned with
|
|
// their ultimate destination.
|
|
if (!isPowerOf2_32(ByteMask)) return true;
|
|
unsigned InputByteNo = CountTrailingZeros_32(ByteMask);
|
|
|
|
// 2) The input and ultimate destinations must line up: if byte 3 of an i32
|
|
// is demanded, it needs to go into byte 0 of the result. This means that the
|
|
// byte needs to be shifted until it lands in the right byte bucket. The
|
|
// shift amount depends on the position: if the byte is coming from the high
|
|
// part of the value (e.g. byte 3) then it must be shifted right. If from the
|
|
// low part, it must be shifted left.
|
|
unsigned DestByteNo = InputByteNo + OverallLeftShift;
|
|
if (InputByteNo < ByteValues.size()/2) {
|
|
if (ByteValues.size()-1-DestByteNo != InputByteNo)
|
|
return true;
|
|
} else {
|
|
if (ByteValues.size()-1-DestByteNo != InputByteNo)
|
|
return true;
|
|
}
|
|
|
|
// If the destination byte value is already defined, the values are or'd
|
|
// together, which isn't a bswap (unless it's an or of the same bits).
|
|
if (ByteValues[DestByteNo] && ByteValues[DestByteNo] != V)
|
|
return true;
|
|
ByteValues[DestByteNo] = V;
|
|
return false;
|
|
}
|
|
|
|
/// MatchBSwap - Given an OR instruction, check to see if this is a bswap idiom.
|
|
/// If so, insert the new bswap intrinsic and return it.
|
|
Instruction *InstCombiner::MatchBSwap(BinaryOperator &I) {
|
|
const IntegerType *ITy = dyn_cast<IntegerType>(I.getType());
|
|
if (!ITy || ITy->getBitWidth() % 16 ||
|
|
// ByteMask only allows up to 32-byte values.
|
|
ITy->getBitWidth() > 32*8)
|
|
return 0; // Can only bswap pairs of bytes. Can't do vectors.
|
|
|
|
/// ByteValues - For each byte of the result, we keep track of which value
|
|
/// defines each byte.
|
|
SmallVector<Value*, 8> ByteValues;
|
|
ByteValues.resize(ITy->getBitWidth()/8);
|
|
|
|
// Try to find all the pieces corresponding to the bswap.
|
|
uint32_t ByteMask = ~0U >> (32-ByteValues.size());
|
|
if (CollectBSwapParts(&I, 0, ByteMask, ByteValues))
|
|
return 0;
|
|
|
|
// Check to see if all of the bytes come from the same value.
|
|
Value *V = ByteValues[0];
|
|
if (V == 0) return 0; // Didn't find a byte? Must be zero.
|
|
|
|
// Check to make sure that all of the bytes come from the same value.
|
|
for (unsigned i = 1, e = ByteValues.size(); i != e; ++i)
|
|
if (ByteValues[i] != V)
|
|
return 0;
|
|
const Type *Tys[] = { ITy };
|
|
Module *M = I.getParent()->getParent()->getParent();
|
|
Function *F = Intrinsic::getDeclaration(M, Intrinsic::bswap, Tys, 1);
|
|
return CallInst::Create(F, V);
|
|
}
|
|
|
|
/// MatchSelectFromAndOr - We have an expression of the form (A&C)|(B&D). Check
|
|
/// If A is (cond?-1:0) and either B or D is ~(cond?-1,0) or (cond?0,-1), then
|
|
/// we can simplify this expression to "cond ? C : D or B".
|
|
static Instruction *MatchSelectFromAndOr(Value *A, Value *B,
|
|
Value *C, Value *D) {
|
|
// If A is not a select of -1/0, this cannot match.
|
|
Value *Cond = 0;
|
|
if (!match(A, m_SelectCst<-1, 0>(m_Value(Cond))))
|
|
return 0;
|
|
|
|
// ((cond?-1:0)&C) | (B&(cond?0:-1)) -> cond ? C : B.
|
|
if (match(D, m_SelectCst<0, -1>(m_Specific(Cond))))
|
|
return SelectInst::Create(Cond, C, B);
|
|
if (match(D, m_Not(m_SelectCst<-1, 0>(m_Specific(Cond)))))
|
|
return SelectInst::Create(Cond, C, B);
|
|
// ((cond?-1:0)&C) | ((cond?0:-1)&D) -> cond ? C : D.
|
|
if (match(B, m_SelectCst<0, -1>(m_Specific(Cond))))
|
|
return SelectInst::Create(Cond, C, D);
|
|
if (match(B, m_Not(m_SelectCst<-1, 0>(m_Specific(Cond)))))
|
|
return SelectInst::Create(Cond, C, D);
|
|
return 0;
|
|
}
|
|
|
|
/// FoldOrOfICmps - Fold (icmp)|(icmp) if possible.
|
|
Instruction *InstCombiner::FoldOrOfICmps(Instruction &I,
|
|
ICmpInst *LHS, ICmpInst *RHS) {
|
|
Value *Val, *Val2;
|
|
ConstantInt *LHSCst, *RHSCst;
|
|
ICmpInst::Predicate LHSCC, RHSCC;
|
|
|
|
// This only handles icmp of constants: (icmp1 A, C1) | (icmp2 B, C2).
|
|
if (!match(LHS, m_ICmp(LHSCC, m_Value(Val), m_ConstantInt(LHSCst))) ||
|
|
!match(RHS, m_ICmp(RHSCC, m_Value(Val2), m_ConstantInt(RHSCst))))
|
|
return 0;
|
|
|
|
// From here on, we only handle:
|
|
// (icmp1 A, C1) | (icmp2 A, C2) --> something simpler.
|
|
if (Val != Val2) return 0;
|
|
|
|
// ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere.
|
|
if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE ||
|
|
RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE ||
|
|
LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE ||
|
|
RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE)
|
|
return 0;
|
|
|
|
// We can't fold (ugt x, C) | (sgt x, C2).
|
|
if (!PredicatesFoldable(LHSCC, RHSCC))
|
|
return 0;
|
|
|
|
// Ensure that the larger constant is on the RHS.
|
|
bool ShouldSwap;
|
|
if (ICmpInst::isSignedPredicate(LHSCC) ||
|
|
(ICmpInst::isEquality(LHSCC) &&
|
|
ICmpInst::isSignedPredicate(RHSCC)))
|
|
ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue());
|
|
else
|
|
ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue());
|
|
|
|
if (ShouldSwap) {
|
|
std::swap(LHS, RHS);
|
|
std::swap(LHSCst, RHSCst);
|
|
std::swap(LHSCC, RHSCC);
|
|
}
|
|
|
|
// At this point, we know we have have two icmp instructions
|
|
// comparing a value against two constants and or'ing the result
|
|
// together. Because of the above check, we know that we only have
|
|
// ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the
|
|
// FoldICmpLogical check above), that the two constants are not
|
|
// equal.
|
|
assert(LHSCst != RHSCst && "Compares not folded above?");
|
|
|
|
switch (LHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case ICmpInst::ICMP_EQ:
|
|
switch (RHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case ICmpInst::ICMP_EQ:
|
|
if (LHSCst == SubOne(RHSCst)) { // (X == 13 | X == 14) -> X-13 <u 2
|
|
Constant *AddCST = ConstantExpr::getNeg(LHSCst);
|
|
Instruction *Add = BinaryOperator::CreateAdd(Val, AddCST,
|
|
Val->getName()+".off");
|
|
InsertNewInstBefore(Add, I);
|
|
AddCST = Subtract(AddOne(RHSCst), LHSCst);
|
|
return new ICmpInst(ICmpInst::ICMP_ULT, Add, AddCST);
|
|
}
|
|
break; // (X == 13 | X == 15) -> no change
|
|
case ICmpInst::ICMP_UGT: // (X == 13 | X u> 14) -> no change
|
|
case ICmpInst::ICMP_SGT: // (X == 13 | X s> 14) -> no change
|
|
break;
|
|
case ICmpInst::ICMP_NE: // (X == 13 | X != 15) -> X != 15
|
|
case ICmpInst::ICMP_ULT: // (X == 13 | X u< 15) -> X u< 15
|
|
case ICmpInst::ICMP_SLT: // (X == 13 | X s< 15) -> X s< 15
|
|
return ReplaceInstUsesWith(I, RHS);
|
|
}
|
|
break;
|
|
case ICmpInst::ICMP_NE:
|
|
switch (RHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case ICmpInst::ICMP_EQ: // (X != 13 | X == 15) -> X != 13
|
|
case ICmpInst::ICMP_UGT: // (X != 13 | X u> 15) -> X != 13
|
|
case ICmpInst::ICMP_SGT: // (X != 13 | X s> 15) -> X != 13
|
|
return ReplaceInstUsesWith(I, LHS);
|
|
case ICmpInst::ICMP_NE: // (X != 13 | X != 15) -> true
|
|
case ICmpInst::ICMP_ULT: // (X != 13 | X u< 15) -> true
|
|
case ICmpInst::ICMP_SLT: // (X != 13 | X s< 15) -> true
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
}
|
|
break;
|
|
case ICmpInst::ICMP_ULT:
|
|
switch (RHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change
|
|
break;
|
|
case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) -> (X-13) u> 2
|
|
// If RHSCst is [us]MAXINT, it is always false. Not handling
|
|
// this can cause overflow.
|
|
if (RHSCst->isMaxValue(false))
|
|
return ReplaceInstUsesWith(I, LHS);
|
|
return InsertRangeTest(Val, LHSCst, AddOne(RHSCst), false, false, I);
|
|
case ICmpInst::ICMP_SGT: // (X u< 13 | X s> 15) -> no change
|
|
break;
|
|
case ICmpInst::ICMP_NE: // (X u< 13 | X != 15) -> X != 15
|
|
case ICmpInst::ICMP_ULT: // (X u< 13 | X u< 15) -> X u< 15
|
|
return ReplaceInstUsesWith(I, RHS);
|
|
case ICmpInst::ICMP_SLT: // (X u< 13 | X s< 15) -> no change
|
|
break;
|
|
}
|
|
break;
|
|
case ICmpInst::ICMP_SLT:
|
|
switch (RHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case ICmpInst::ICMP_EQ: // (X s< 13 | X == 14) -> no change
|
|
break;
|
|
case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) -> (X-13) s> 2
|
|
// If RHSCst is [us]MAXINT, it is always false. Not handling
|
|
// this can cause overflow.
|
|
if (RHSCst->isMaxValue(true))
|
|
return ReplaceInstUsesWith(I, LHS);
|
|
return InsertRangeTest(Val, LHSCst, AddOne(RHSCst), true, false, I);
|
|
case ICmpInst::ICMP_UGT: // (X s< 13 | X u> 15) -> no change
|
|
break;
|
|
case ICmpInst::ICMP_NE: // (X s< 13 | X != 15) -> X != 15
|
|
case ICmpInst::ICMP_SLT: // (X s< 13 | X s< 15) -> X s< 15
|
|
return ReplaceInstUsesWith(I, RHS);
|
|
case ICmpInst::ICMP_ULT: // (X s< 13 | X u< 15) -> no change
|
|
break;
|
|
}
|
|
break;
|
|
case ICmpInst::ICMP_UGT:
|
|
switch (RHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case ICmpInst::ICMP_EQ: // (X u> 13 | X == 15) -> X u> 13
|
|
case ICmpInst::ICMP_UGT: // (X u> 13 | X u> 15) -> X u> 13
|
|
return ReplaceInstUsesWith(I, LHS);
|
|
case ICmpInst::ICMP_SGT: // (X u> 13 | X s> 15) -> no change
|
|
break;
|
|
case ICmpInst::ICMP_NE: // (X u> 13 | X != 15) -> true
|
|
case ICmpInst::ICMP_ULT: // (X u> 13 | X u< 15) -> true
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
case ICmpInst::ICMP_SLT: // (X u> 13 | X s< 15) -> no change
|
|
break;
|
|
}
|
|
break;
|
|
case ICmpInst::ICMP_SGT:
|
|
switch (RHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case ICmpInst::ICMP_EQ: // (X s> 13 | X == 15) -> X > 13
|
|
case ICmpInst::ICMP_SGT: // (X s> 13 | X s> 15) -> X > 13
|
|
return ReplaceInstUsesWith(I, LHS);
|
|
case ICmpInst::ICMP_UGT: // (X s> 13 | X u> 15) -> no change
|
|
break;
|
|
case ICmpInst::ICMP_NE: // (X s> 13 | X != 15) -> true
|
|
case ICmpInst::ICMP_SLT: // (X s> 13 | X s< 15) -> true
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
case ICmpInst::ICMP_ULT: // (X s> 13 | X u< 15) -> no change
|
|
break;
|
|
}
|
|
break;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/// FoldOrWithConstants - This helper function folds:
|
|
///
|
|
/// ((A | B) & C1) | (B & C2)
|
|
///
|
|
/// into:
|
|
///
|
|
/// (A & C1) | B
|
|
///
|
|
/// when the XOR of the two constants is "all ones" (-1).
|
|
Instruction *InstCombiner::FoldOrWithConstants(BinaryOperator &I, Value *Op,
|
|
Value *A, Value *B, Value *C) {
|
|
ConstantInt *CI1 = dyn_cast<ConstantInt>(C);
|
|
if (!CI1) return 0;
|
|
|
|
Value *V1 = 0;
|
|
ConstantInt *CI2 = 0;
|
|
if (!match(Op, m_And(m_Value(V1), m_ConstantInt(CI2)))) return 0;
|
|
|
|
APInt Xor = CI1->getValue() ^ CI2->getValue();
|
|
if (!Xor.isAllOnesValue()) return 0;
|
|
|
|
if (V1 == A || V1 == B) {
|
|
Instruction *NewOp =
|
|
InsertNewInstBefore(BinaryOperator::CreateAnd((V1 == A) ? B : A, CI1), I);
|
|
return BinaryOperator::CreateOr(NewOp, V1);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitOr(BinaryOperator &I) {
|
|
bool Changed = SimplifyCommutative(I);
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
if (isa<UndefValue>(Op1)) // X | undef -> -1
|
|
return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
|
|
|
|
// or X, X = X
|
|
if (Op0 == Op1)
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
|
|
// See if we can simplify any instructions used by the instruction whose sole
|
|
// purpose is to compute bits we don't care about.
|
|
if (!isa<VectorType>(I.getType())) {
|
|
if (SimplifyDemandedInstructionBits(I))
|
|
return &I;
|
|
} else if (isa<ConstantAggregateZero>(Op1)) {
|
|
return ReplaceInstUsesWith(I, Op0); // X | <0,0> -> X
|
|
} else if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1)) {
|
|
if (CP->isAllOnesValue()) // X | <-1,-1> -> <-1,-1>
|
|
return ReplaceInstUsesWith(I, I.getOperand(1));
|
|
}
|
|
|
|
|
|
|
|
// or X, -1 == -1
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
|
|
ConstantInt *C1 = 0; Value *X = 0;
|
|
// (X & C1) | C2 --> (X | C2) & (C1|C2)
|
|
if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
|
|
Instruction *Or = BinaryOperator::CreateOr(X, RHS);
|
|
InsertNewInstBefore(Or, I);
|
|
Or->takeName(Op0);
|
|
return BinaryOperator::CreateAnd(Or,
|
|
ConstantInt::get(RHS->getValue() | C1->getValue()));
|
|
}
|
|
|
|
// (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
|
|
if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
|
|
Instruction *Or = BinaryOperator::CreateOr(X, RHS);
|
|
InsertNewInstBefore(Or, I);
|
|
Or->takeName(Op0);
|
|
return BinaryOperator::CreateXor(Or,
|
|
ConstantInt::get(C1->getValue() & ~RHS->getValue()));
|
|
}
|
|
|
|
// Try to fold constant and into select arguments.
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
|
|
if (Instruction *R = FoldOpIntoSelect(I, SI, this))
|
|
return R;
|
|
if (isa<PHINode>(Op0))
|
|
if (Instruction *NV = FoldOpIntoPhi(I))
|
|
return NV;
|
|
}
|
|
|
|
Value *A = 0, *B = 0;
|
|
ConstantInt *C1 = 0, *C2 = 0;
|
|
|
|
if (match(Op0, m_And(m_Value(A), m_Value(B))))
|
|
if (A == Op1 || B == Op1) // (A & ?) | A --> A
|
|
return ReplaceInstUsesWith(I, Op1);
|
|
if (match(Op1, m_And(m_Value(A), m_Value(B))))
|
|
if (A == Op0 || B == Op0) // A | (A & ?) --> A
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
|
|
// (A | B) | C and A | (B | C) -> bswap if possible.
|
|
// (A >> B) | (C << D) and (A << B) | (B >> C) -> bswap if possible.
|
|
if (match(Op0, m_Or(m_Value(), m_Value())) ||
|
|
match(Op1, m_Or(m_Value(), m_Value())) ||
|
|
(match(Op0, m_Shift(m_Value(), m_Value())) &&
|
|
match(Op1, m_Shift(m_Value(), m_Value())))) {
|
|
if (Instruction *BSwap = MatchBSwap(I))
|
|
return BSwap;
|
|
}
|
|
|
|
// (X^C)|Y -> (X|Y)^C iff Y&C == 0
|
|
if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
|
|
MaskedValueIsZero(Op1, C1->getValue())) {
|
|
Instruction *NOr = BinaryOperator::CreateOr(A, Op1);
|
|
InsertNewInstBefore(NOr, I);
|
|
NOr->takeName(Op0);
|
|
return BinaryOperator::CreateXor(NOr, C1);
|
|
}
|
|
|
|
// Y|(X^C) -> (X|Y)^C iff Y&C == 0
|
|
if (Op1->hasOneUse() && match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) &&
|
|
MaskedValueIsZero(Op0, C1->getValue())) {
|
|
Instruction *NOr = BinaryOperator::CreateOr(A, Op0);
|
|
InsertNewInstBefore(NOr, I);
|
|
NOr->takeName(Op0);
|
|
return BinaryOperator::CreateXor(NOr, C1);
|
|
}
|
|
|
|
// (A & C)|(B & D)
|
|
Value *C = 0, *D = 0;
|
|
if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
|
|
match(Op1, m_And(m_Value(B), m_Value(D)))) {
|
|
Value *V1 = 0, *V2 = 0, *V3 = 0;
|
|
C1 = dyn_cast<ConstantInt>(C);
|
|
C2 = dyn_cast<ConstantInt>(D);
|
|
if (C1 && C2) { // (A & C1)|(B & C2)
|
|
// If we have: ((V + N) & C1) | (V & C2)
|
|
// .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
|
|
// replace with V+N.
|
|
if (C1->getValue() == ~C2->getValue()) {
|
|
if ((C2->getValue() & (C2->getValue()+1)) == 0 && // C2 == 0+1+
|
|
match(A, m_Add(m_Value(V1), m_Value(V2)))) {
|
|
// Add commutes, try both ways.
|
|
if (V1 == B && MaskedValueIsZero(V2, C2->getValue()))
|
|
return ReplaceInstUsesWith(I, A);
|
|
if (V2 == B && MaskedValueIsZero(V1, C2->getValue()))
|
|
return ReplaceInstUsesWith(I, A);
|
|
}
|
|
// Or commutes, try both ways.
|
|
if ((C1->getValue() & (C1->getValue()+1)) == 0 &&
|
|
match(B, m_Add(m_Value(V1), m_Value(V2)))) {
|
|
// Add commutes, try both ways.
|
|
if (V1 == A && MaskedValueIsZero(V2, C1->getValue()))
|
|
return ReplaceInstUsesWith(I, B);
|
|
if (V2 == A && MaskedValueIsZero(V1, C1->getValue()))
|
|
return ReplaceInstUsesWith(I, B);
|
|
}
|
|
}
|
|
V1 = 0; V2 = 0; V3 = 0;
|
|
}
|
|
|
|
// Check to see if we have any common things being and'ed. If so, find the
|
|
// terms for V1 & (V2|V3).
|
|
if (isOnlyUse(Op0) || isOnlyUse(Op1)) {
|
|
if (A == B) // (A & C)|(A & D) == A & (C|D)
|
|
V1 = A, V2 = C, V3 = D;
|
|
else if (A == D) // (A & C)|(B & A) == A & (B|C)
|
|
V1 = A, V2 = B, V3 = C;
|
|
else if (C == B) // (A & C)|(C & D) == C & (A|D)
|
|
V1 = C, V2 = A, V3 = D;
|
|
else if (C == D) // (A & C)|(B & C) == C & (A|B)
|
|
V1 = C, V2 = A, V3 = B;
|
|
|
|
if (V1) {
|
|
Value *Or =
|
|
InsertNewInstBefore(BinaryOperator::CreateOr(V2, V3, "tmp"), I);
|
|
return BinaryOperator::CreateAnd(V1, Or);
|
|
}
|
|
}
|
|
|
|
// (A & (C0?-1:0)) | (B & ~(C0?-1:0)) -> C0 ? A : B, and commuted variants
|
|
if (Instruction *Match = MatchSelectFromAndOr(A, B, C, D))
|
|
return Match;
|
|
if (Instruction *Match = MatchSelectFromAndOr(B, A, D, C))
|
|
return Match;
|
|
if (Instruction *Match = MatchSelectFromAndOr(C, B, A, D))
|
|
return Match;
|
|
if (Instruction *Match = MatchSelectFromAndOr(D, A, B, C))
|
|
return Match;
|
|
|
|
// ((A&~B)|(~A&B)) -> A^B
|
|
if ((match(C, m_Not(m_Specific(D))) &&
|
|
match(B, m_Not(m_Specific(A)))))
|
|
return BinaryOperator::CreateXor(A, D);
|
|
// ((~B&A)|(~A&B)) -> A^B
|
|
if ((match(A, m_Not(m_Specific(D))) &&
|
|
match(B, m_Not(m_Specific(C)))))
|
|
return BinaryOperator::CreateXor(C, D);
|
|
// ((A&~B)|(B&~A)) -> A^B
|
|
if ((match(C, m_Not(m_Specific(B))) &&
|
|
match(D, m_Not(m_Specific(A)))))
|
|
return BinaryOperator::CreateXor(A, B);
|
|
// ((~B&A)|(B&~A)) -> A^B
|
|
if ((match(A, m_Not(m_Specific(B))) &&
|
|
match(D, m_Not(m_Specific(C)))))
|
|
return BinaryOperator::CreateXor(C, B);
|
|
}
|
|
|
|
// (X >> Z) | (Y >> Z) -> (X|Y) >> Z for all shifts.
|
|
if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) {
|
|
if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0))
|
|
if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() &&
|
|
SI0->getOperand(1) == SI1->getOperand(1) &&
|
|
(SI0->hasOneUse() || SI1->hasOneUse())) {
|
|
Instruction *NewOp =
|
|
InsertNewInstBefore(BinaryOperator::CreateOr(SI0->getOperand(0),
|
|
SI1->getOperand(0),
|
|
SI0->getName()), I);
|
|
return BinaryOperator::Create(SI1->getOpcode(), NewOp,
|
|
SI1->getOperand(1));
|
|
}
|
|
}
|
|
|
|
// ((A|B)&1)|(B&-2) -> (A&1) | B
|
|
if (match(Op0, m_And(m_Or(m_Value(A), m_Value(B)), m_Value(C))) ||
|
|
match(Op0, m_And(m_Value(C), m_Or(m_Value(A), m_Value(B))))) {
|
|
Instruction *Ret = FoldOrWithConstants(I, Op1, A, B, C);
|
|
if (Ret) return Ret;
|
|
}
|
|
// (B&-2)|((A|B)&1) -> (A&1) | B
|
|
if (match(Op1, m_And(m_Or(m_Value(A), m_Value(B)), m_Value(C))) ||
|
|
match(Op1, m_And(m_Value(C), m_Or(m_Value(A), m_Value(B))))) {
|
|
Instruction *Ret = FoldOrWithConstants(I, Op0, A, B, C);
|
|
if (Ret) return Ret;
|
|
}
|
|
|
|
if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
|
|
if (A == Op1) // ~A | A == -1
|
|
return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
|
|
} else {
|
|
A = 0;
|
|
}
|
|
// Note, A is still live here!
|
|
if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B
|
|
if (Op0 == B)
|
|
return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
|
|
|
|
// (~A | ~B) == (~(A & B)) - De Morgan's Law
|
|
if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) {
|
|
Value *And = InsertNewInstBefore(BinaryOperator::CreateAnd(A, B,
|
|
I.getName()+".demorgan"), I);
|
|
return BinaryOperator::CreateNot(And);
|
|
}
|
|
}
|
|
|
|
// (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B)
|
|
if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1))) {
|
|
if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
|
|
return R;
|
|
|
|
if (ICmpInst *LHS = dyn_cast<ICmpInst>(I.getOperand(0)))
|
|
if (Instruction *Res = FoldOrOfICmps(I, LHS, RHS))
|
|
return Res;
|
|
}
|
|
|
|
// fold (or (cast A), (cast B)) -> (cast (or A, B))
|
|
if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
|
|
if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
|
|
if (Op0C->getOpcode() == Op1C->getOpcode()) {// same cast kind ?
|
|
if (!isa<ICmpInst>(Op0C->getOperand(0)) ||
|
|
!isa<ICmpInst>(Op1C->getOperand(0))) {
|
|
const Type *SrcTy = Op0C->getOperand(0)->getType();
|
|
if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
|
|
// Only do this if the casts both really cause code to be
|
|
// generated.
|
|
ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
|
|
I.getType(), TD) &&
|
|
ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
|
|
I.getType(), TD)) {
|
|
Instruction *NewOp = BinaryOperator::CreateOr(Op0C->getOperand(0),
|
|
Op1C->getOperand(0),
|
|
I.getName());
|
|
InsertNewInstBefore(NewOp, I);
|
|
return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
// (fcmp uno x, c) | (fcmp uno y, c) -> (fcmp uno x, y)
|
|
if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) {
|
|
if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1))) {
|
|
if (LHS->getPredicate() == FCmpInst::FCMP_UNO &&
|
|
RHS->getPredicate() == FCmpInst::FCMP_UNO &&
|
|
LHS->getOperand(0)->getType() == RHS->getOperand(0)->getType()) {
|
|
if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1)))
|
|
if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) {
|
|
// If either of the constants are nans, then the whole thing returns
|
|
// true.
|
|
if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN())
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
|
|
// Otherwise, no need to compare the two constants, compare the
|
|
// rest.
|
|
return new FCmpInst(FCmpInst::FCMP_UNO, LHS->getOperand(0),
|
|
RHS->getOperand(0));
|
|
}
|
|
} else {
|
|
Value *Op0LHS, *Op0RHS, *Op1LHS, *Op1RHS;
|
|
FCmpInst::Predicate Op0CC, Op1CC;
|
|
if (match(Op0, m_FCmp(Op0CC, m_Value(Op0LHS), m_Value(Op0RHS))) &&
|
|
match(Op1, m_FCmp(Op1CC, m_Value(Op1LHS), m_Value(Op1RHS)))) {
|
|
if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) {
|
|
// Swap RHS operands to match LHS.
|
|
Op1CC = FCmpInst::getSwappedPredicate(Op1CC);
|
|
std::swap(Op1LHS, Op1RHS);
|
|
}
|
|
if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) {
|
|
// Simplify (fcmp cc0 x, y) | (fcmp cc1 x, y).
|
|
if (Op0CC == Op1CC)
|
|
return new FCmpInst((FCmpInst::Predicate)Op0CC, Op0LHS, Op0RHS);
|
|
else if (Op0CC == FCmpInst::FCMP_TRUE ||
|
|
Op1CC == FCmpInst::FCMP_TRUE)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
else if (Op0CC == FCmpInst::FCMP_FALSE)
|
|
return ReplaceInstUsesWith(I, Op1);
|
|
else if (Op1CC == FCmpInst::FCMP_FALSE)
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
bool Op0Ordered;
|
|
bool Op1Ordered;
|
|
unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered);
|
|
unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered);
|
|
if (Op0Ordered == Op1Ordered) {
|
|
// If both are ordered or unordered, return a new fcmp with
|
|
// or'ed predicates.
|
|
Value *RV = getFCmpValue(Op0Ordered, Op0Pred|Op1Pred,
|
|
Op0LHS, Op0RHS);
|
|
if (Instruction *I = dyn_cast<Instruction>(RV))
|
|
return I;
|
|
// Otherwise, it's a constant boolean value...
|
|
return ReplaceInstUsesWith(I, RV);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return Changed ? &I : 0;
|
|
}
|
|
|
|
namespace {
|
|
|
|
// XorSelf - Implements: X ^ X --> 0
|
|
struct XorSelf {
|
|
Value *RHS;
|
|
XorSelf(Value *rhs) : RHS(rhs) {}
|
|
bool shouldApply(Value *LHS) const { return LHS == RHS; }
|
|
Instruction *apply(BinaryOperator &Xor) const {
|
|
return &Xor;
|
|
}
|
|
};
|
|
|
|
}
|
|
|
|
Instruction *InstCombiner::visitXor(BinaryOperator &I) {
|
|
bool Changed = SimplifyCommutative(I);
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
if (isa<UndefValue>(Op1)) {
|
|
if (isa<UndefValue>(Op0))
|
|
// Handle undef ^ undef -> 0 special case. This is a common
|
|
// idiom (misuse).
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef
|
|
}
|
|
|
|
// xor X, X = 0, even if X is nested in a sequence of Xor's.
|
|
if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) {
|
|
assert(Result == &I && "AssociativeOpt didn't work?"); Result=Result;
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
}
|
|
|
|
// See if we can simplify any instructions used by the instruction whose sole
|
|
// purpose is to compute bits we don't care about.
|
|
if (!isa<VectorType>(I.getType())) {
|
|
if (SimplifyDemandedInstructionBits(I))
|
|
return &I;
|
|
} else if (isa<ConstantAggregateZero>(Op1)) {
|
|
return ReplaceInstUsesWith(I, Op0); // X ^ <0,0> -> X
|
|
}
|
|
|
|
// Is this a ~ operation?
|
|
if (Value *NotOp = dyn_castNotVal(&I)) {
|
|
// ~(~X & Y) --> (X | ~Y) - De Morgan's Law
|
|
// ~(~X | Y) === (X & ~Y) - De Morgan's Law
|
|
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(NotOp)) {
|
|
if (Op0I->getOpcode() == Instruction::And ||
|
|
Op0I->getOpcode() == Instruction::Or) {
|
|
if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands();
|
|
if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) {
|
|
Instruction *NotY =
|
|
BinaryOperator::CreateNot(Op0I->getOperand(1),
|
|
Op0I->getOperand(1)->getName()+".not");
|
|
InsertNewInstBefore(NotY, I);
|
|
if (Op0I->getOpcode() == Instruction::And)
|
|
return BinaryOperator::CreateOr(Op0NotVal, NotY);
|
|
else
|
|
return BinaryOperator::CreateAnd(Op0NotVal, NotY);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
|
|
if (RHS == ConstantInt::getTrue() && Op0->hasOneUse()) {
|
|
// xor (cmp A, B), true = not (cmp A, B) = !cmp A, B
|
|
if (ICmpInst *ICI = dyn_cast<ICmpInst>(Op0))
|
|
return new ICmpInst(ICI->getInversePredicate(),
|
|
ICI->getOperand(0), ICI->getOperand(1));
|
|
|
|
if (FCmpInst *FCI = dyn_cast<FCmpInst>(Op0))
|
|
return new FCmpInst(FCI->getInversePredicate(),
|
|
FCI->getOperand(0), FCI->getOperand(1));
|
|
}
|
|
|
|
// fold (xor(zext(cmp)), 1) and (xor(sext(cmp)), -1) to ext(!cmp).
|
|
if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
|
|
if (CmpInst *CI = dyn_cast<CmpInst>(Op0C->getOperand(0))) {
|
|
if (CI->hasOneUse() && Op0C->hasOneUse()) {
|
|
Instruction::CastOps Opcode = Op0C->getOpcode();
|
|
if (Opcode == Instruction::ZExt || Opcode == Instruction::SExt) {
|
|
if (RHS == ConstantExpr::getCast(Opcode, ConstantInt::getTrue(),
|
|
Op0C->getDestTy())) {
|
|
Instruction *NewCI = InsertNewInstBefore(CmpInst::Create(
|
|
CI->getOpcode(), CI->getInversePredicate(),
|
|
CI->getOperand(0), CI->getOperand(1)), I);
|
|
NewCI->takeName(CI);
|
|
return CastInst::Create(Opcode, NewCI, Op0C->getType());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
|
|
// ~(c-X) == X-c-1 == X+(-c-1)
|
|
if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())
|
|
if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) {
|
|
Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
|
|
Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C,
|
|
ConstantInt::get(I.getType(), 1));
|
|
return BinaryOperator::CreateAdd(Op0I->getOperand(1), ConstantRHS);
|
|
}
|
|
|
|
if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
|
|
if (Op0I->getOpcode() == Instruction::Add) {
|
|
// ~(X-c) --> (-c-1)-X
|
|
if (RHS->isAllOnesValue()) {
|
|
Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
|
|
return BinaryOperator::CreateSub(
|
|
ConstantExpr::getSub(NegOp0CI,
|
|
ConstantInt::get(I.getType(), 1)),
|
|
Op0I->getOperand(0));
|
|
} else if (RHS->getValue().isSignBit()) {
|
|
// (X + C) ^ signbit -> (X + C + signbit)
|
|
Constant *C = ConstantInt::get(RHS->getValue() + Op0CI->getValue());
|
|
return BinaryOperator::CreateAdd(Op0I->getOperand(0), C);
|
|
|
|
}
|
|
} else if (Op0I->getOpcode() == Instruction::Or) {
|
|
// (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0
|
|
if (MaskedValueIsZero(Op0I->getOperand(0), Op0CI->getValue())) {
|
|
Constant *NewRHS = ConstantExpr::getOr(Op0CI, RHS);
|
|
// Anything in both C1 and C2 is known to be zero, remove it from
|
|
// NewRHS.
|
|
Constant *CommonBits = And(Op0CI, RHS);
|
|
NewRHS = ConstantExpr::getAnd(NewRHS,
|
|
ConstantExpr::getNot(CommonBits));
|
|
AddToWorkList(Op0I);
|
|
I.setOperand(0, Op0I->getOperand(0));
|
|
I.setOperand(1, NewRHS);
|
|
return &I;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Try to fold constant and into select arguments.
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
|
|
if (Instruction *R = FoldOpIntoSelect(I, SI, this))
|
|
return R;
|
|
if (isa<PHINode>(Op0))
|
|
if (Instruction *NV = FoldOpIntoPhi(I))
|
|
return NV;
|
|
}
|
|
|
|
if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
|
|
if (X == Op1)
|
|
return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
|
|
|
|
if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
|
|
if (X == Op0)
|
|
return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));
|
|
|
|
|
|
BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1);
|
|
if (Op1I) {
|
|
Value *A, *B;
|
|
if (match(Op1I, m_Or(m_Value(A), m_Value(B)))) {
|
|
if (A == Op0) { // B^(B|A) == (A|B)^B
|
|
Op1I->swapOperands();
|
|
I.swapOperands();
|
|
std::swap(Op0, Op1);
|
|
} else if (B == Op0) { // B^(A|B) == (A|B)^B
|
|
I.swapOperands(); // Simplified below.
|
|
std::swap(Op0, Op1);
|
|
}
|
|
} else if (match(Op1I, m_Xor(m_Specific(Op0), m_Value(B)))) {
|
|
return ReplaceInstUsesWith(I, B); // A^(A^B) == B
|
|
} else if (match(Op1I, m_Xor(m_Value(A), m_Specific(Op0)))) {
|
|
return ReplaceInstUsesWith(I, A); // A^(B^A) == B
|
|
} else if (match(Op1I, m_And(m_Value(A), m_Value(B))) && Op1I->hasOneUse()){
|
|
if (A == Op0) { // A^(A&B) -> A^(B&A)
|
|
Op1I->swapOperands();
|
|
std::swap(A, B);
|
|
}
|
|
if (B == Op0) { // A^(B&A) -> (B&A)^A
|
|
I.swapOperands(); // Simplified below.
|
|
std::swap(Op0, Op1);
|
|
}
|
|
}
|
|
}
|
|
|
|
BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0);
|
|
if (Op0I) {
|
|
Value *A, *B;
|
|
if (match(Op0I, m_Or(m_Value(A), m_Value(B))) && Op0I->hasOneUse()) {
|
|
if (A == Op1) // (B|A)^B == (A|B)^B
|
|
std::swap(A, B);
|
|
if (B == Op1) { // (A|B)^B == A & ~B
|
|
Instruction *NotB =
|
|
InsertNewInstBefore(BinaryOperator::CreateNot(Op1, "tmp"), I);
|
|
return BinaryOperator::CreateAnd(A, NotB);
|
|
}
|
|
} else if (match(Op0I, m_Xor(m_Specific(Op1), m_Value(B)))) {
|
|
return ReplaceInstUsesWith(I, B); // (A^B)^A == B
|
|
} else if (match(Op0I, m_Xor(m_Value(A), m_Specific(Op1)))) {
|
|
return ReplaceInstUsesWith(I, A); // (B^A)^A == B
|
|
} else if (match(Op0I, m_And(m_Value(A), m_Value(B))) && Op0I->hasOneUse()){
|
|
if (A == Op1) // (A&B)^A -> (B&A)^A
|
|
std::swap(A, B);
|
|
if (B == Op1 && // (B&A)^A == ~B & A
|
|
!isa<ConstantInt>(Op1)) { // Canonical form is (B&C)^C
|
|
Instruction *N =
|
|
InsertNewInstBefore(BinaryOperator::CreateNot(A, "tmp"), I);
|
|
return BinaryOperator::CreateAnd(N, Op1);
|
|
}
|
|
}
|
|
}
|
|
|
|
// (X >> Z) ^ (Y >> Z) -> (X^Y) >> Z for all shifts.
|
|
if (Op0I && Op1I && Op0I->isShift() &&
|
|
Op0I->getOpcode() == Op1I->getOpcode() &&
|
|
Op0I->getOperand(1) == Op1I->getOperand(1) &&
|
|
(Op1I->hasOneUse() || Op1I->hasOneUse())) {
|
|
Instruction *NewOp =
|
|
InsertNewInstBefore(BinaryOperator::CreateXor(Op0I->getOperand(0),
|
|
Op1I->getOperand(0),
|
|
Op0I->getName()), I);
|
|
return BinaryOperator::Create(Op1I->getOpcode(), NewOp,
|
|
Op1I->getOperand(1));
|
|
}
|
|
|
|
if (Op0I && Op1I) {
|
|
Value *A, *B, *C, *D;
|
|
// (A & B)^(A | B) -> A ^ B
|
|
if (match(Op0I, m_And(m_Value(A), m_Value(B))) &&
|
|
match(Op1I, m_Or(m_Value(C), m_Value(D)))) {
|
|
if ((A == C && B == D) || (A == D && B == C))
|
|
return BinaryOperator::CreateXor(A, B);
|
|
}
|
|
// (A | B)^(A & B) -> A ^ B
|
|
if (match(Op0I, m_Or(m_Value(A), m_Value(B))) &&
|
|
match(Op1I, m_And(m_Value(C), m_Value(D)))) {
|
|
if ((A == C && B == D) || (A == D && B == C))
|
|
return BinaryOperator::CreateXor(A, B);
|
|
}
|
|
|
|
// (A & B)^(C & D)
|
|
if ((Op0I->hasOneUse() || Op1I->hasOneUse()) &&
|
|
match(Op0I, m_And(m_Value(A), m_Value(B))) &&
|
|
match(Op1I, m_And(m_Value(C), m_Value(D)))) {
|
|
// (X & Y)^(X & Y) -> (Y^Z) & X
|
|
Value *X = 0, *Y = 0, *Z = 0;
|
|
if (A == C)
|
|
X = A, Y = B, Z = D;
|
|
else if (A == D)
|
|
X = A, Y = B, Z = C;
|
|
else if (B == C)
|
|
X = B, Y = A, Z = D;
|
|
else if (B == D)
|
|
X = B, Y = A, Z = C;
|
|
|
|
if (X) {
|
|
Instruction *NewOp =
|
|
InsertNewInstBefore(BinaryOperator::CreateXor(Y, Z, Op0->getName()), I);
|
|
return BinaryOperator::CreateAnd(NewOp, X);
|
|
}
|
|
}
|
|
}
|
|
|
|
// (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B)
|
|
if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1)))
|
|
if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS)))
|
|
return R;
|
|
|
|
// fold (xor (cast A), (cast B)) -> (cast (xor A, B))
|
|
if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) {
|
|
if (CastInst *Op1C = dyn_cast<CastInst>(Op1))
|
|
if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind?
|
|
const Type *SrcTy = Op0C->getOperand(0)->getType();
|
|
if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() &&
|
|
// Only do this if the casts both really cause code to be generated.
|
|
ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0),
|
|
I.getType(), TD) &&
|
|
ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0),
|
|
I.getType(), TD)) {
|
|
Instruction *NewOp = BinaryOperator::CreateXor(Op0C->getOperand(0),
|
|
Op1C->getOperand(0),
|
|
I.getName());
|
|
InsertNewInstBefore(NewOp, I);
|
|
return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType());
|
|
}
|
|
}
|
|
}
|
|
|
|
return Changed ? &I : 0;
|
|
}
|
|
|
|
/// AddWithOverflow - Compute Result = In1+In2, returning true if the result
|
|
/// overflowed for this type.
|
|
static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
|
|
ConstantInt *In2, bool IsSigned = false) {
|
|
Result = cast<ConstantInt>(Add(In1, In2));
|
|
|
|
if (IsSigned)
|
|
if (In2->getValue().isNegative())
|
|
return Result->getValue().sgt(In1->getValue());
|
|
else
|
|
return Result->getValue().slt(In1->getValue());
|
|
else
|
|
return Result->getValue().ult(In1->getValue());
|
|
}
|
|
|
|
/// SubWithOverflow - Compute Result = In1-In2, returning true if the result
|
|
/// overflowed for this type.
|
|
static bool SubWithOverflow(ConstantInt *&Result, ConstantInt *In1,
|
|
ConstantInt *In2, bool IsSigned = false) {
|
|
Result = cast<ConstantInt>(Subtract(In1, In2));
|
|
|
|
if (IsSigned)
|
|
if (In2->getValue().isNegative())
|
|
return Result->getValue().slt(In1->getValue());
|
|
else
|
|
return Result->getValue().sgt(In1->getValue());
|
|
else
|
|
return Result->getValue().ugt(In1->getValue());
|
|
}
|
|
|
|
/// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the
|
|
/// code necessary to compute the offset from the base pointer (without adding
|
|
/// in the base pointer). Return the result as a signed integer of intptr size.
|
|
static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) {
|
|
TargetData &TD = IC.getTargetData();
|
|
gep_type_iterator GTI = gep_type_begin(GEP);
|
|
const Type *IntPtrTy = TD.getIntPtrType();
|
|
Value *Result = Constant::getNullValue(IntPtrTy);
|
|
|
|
// Build a mask for high order bits.
|
|
unsigned IntPtrWidth = TD.getPointerSizeInBits();
|
|
uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
|
|
|
|
for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end(); i != e;
|
|
++i, ++GTI) {
|
|
Value *Op = *i;
|
|
uint64_t Size = TD.getTypePaddedSize(GTI.getIndexedType()) & PtrSizeMask;
|
|
if (ConstantInt *OpC = dyn_cast<ConstantInt>(Op)) {
|
|
if (OpC->isZero()) continue;
|
|
|
|
// Handle a struct index, which adds its field offset to the pointer.
|
|
if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
|
|
Size = TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
|
|
|
|
if (ConstantInt *RC = dyn_cast<ConstantInt>(Result))
|
|
Result = ConstantInt::get(RC->getValue() + APInt(IntPtrWidth, Size));
|
|
else
|
|
Result = IC.InsertNewInstBefore(
|
|
BinaryOperator::CreateAdd(Result,
|
|
ConstantInt::get(IntPtrTy, Size),
|
|
GEP->getName()+".offs"), I);
|
|
continue;
|
|
}
|
|
|
|
Constant *Scale = ConstantInt::get(IntPtrTy, Size);
|
|
Constant *OC = ConstantExpr::getIntegerCast(OpC, IntPtrTy, true /*SExt*/);
|
|
Scale = ConstantExpr::getMul(OC, Scale);
|
|
if (Constant *RC = dyn_cast<Constant>(Result))
|
|
Result = ConstantExpr::getAdd(RC, Scale);
|
|
else {
|
|
// Emit an add instruction.
|
|
Result = IC.InsertNewInstBefore(
|
|
BinaryOperator::CreateAdd(Result, Scale,
|
|
GEP->getName()+".offs"), I);
|
|
}
|
|
continue;
|
|
}
|
|
// Convert to correct type.
|
|
if (Op->getType() != IntPtrTy) {
|
|
if (Constant *OpC = dyn_cast<Constant>(Op))
|
|
Op = ConstantExpr::getSExt(OpC, IntPtrTy);
|
|
else
|
|
Op = IC.InsertNewInstBefore(new SExtInst(Op, IntPtrTy,
|
|
Op->getName()+".c"), I);
|
|
}
|
|
if (Size != 1) {
|
|
Constant *Scale = ConstantInt::get(IntPtrTy, Size);
|
|
if (Constant *OpC = dyn_cast<Constant>(Op))
|
|
Op = ConstantExpr::getMul(OpC, Scale);
|
|
else // We'll let instcombine(mul) convert this to a shl if possible.
|
|
Op = IC.InsertNewInstBefore(BinaryOperator::CreateMul(Op, Scale,
|
|
GEP->getName()+".idx"), I);
|
|
}
|
|
|
|
// Emit an add instruction.
|
|
if (isa<Constant>(Op) && isa<Constant>(Result))
|
|
Result = ConstantExpr::getAdd(cast<Constant>(Op),
|
|
cast<Constant>(Result));
|
|
else
|
|
Result = IC.InsertNewInstBefore(BinaryOperator::CreateAdd(Op, Result,
|
|
GEP->getName()+".offs"), I);
|
|
}
|
|
return Result;
|
|
}
|
|
|
|
|
|
/// EvaluateGEPOffsetExpression - Return an value that can be used to compare of
|
|
/// the *offset* implied by GEP to zero. For example, if we have &A[i], we want
|
|
/// to return 'i' for "icmp ne i, 0". Note that, in general, indices can be
|
|
/// complex, and scales are involved. The above expression would also be legal
|
|
/// to codegen as "icmp ne (i*4), 0" (assuming A is a pointer to i32). This
|
|
/// later form is less amenable to optimization though, and we are allowed to
|
|
/// generate the first by knowing that pointer arithmetic doesn't overflow.
|
|
///
|
|
/// If we can't emit an optimized form for this expression, this returns null.
|
|
///
|
|
static Value *EvaluateGEPOffsetExpression(User *GEP, Instruction &I,
|
|
InstCombiner &IC) {
|
|
TargetData &TD = IC.getTargetData();
|
|
gep_type_iterator GTI = gep_type_begin(GEP);
|
|
|
|
// Check to see if this gep only has a single variable index. If so, and if
|
|
// any constant indices are a multiple of its scale, then we can compute this
|
|
// in terms of the scale of the variable index. For example, if the GEP
|
|
// implies an offset of "12 + i*4", then we can codegen this as "3 + i",
|
|
// because the expression will cross zero at the same point.
|
|
unsigned i, e = GEP->getNumOperands();
|
|
int64_t Offset = 0;
|
|
for (i = 1; i != e; ++i, ++GTI) {
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
|
|
// Compute the aggregate offset of constant indices.
|
|
if (CI->isZero()) continue;
|
|
|
|
// Handle a struct index, which adds its field offset to the pointer.
|
|
if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
|
|
Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
|
|
} else {
|
|
uint64_t Size = TD.getTypePaddedSize(GTI.getIndexedType());
|
|
Offset += Size*CI->getSExtValue();
|
|
}
|
|
} else {
|
|
// Found our variable index.
|
|
break;
|
|
}
|
|
}
|
|
|
|
// If there are no variable indices, we must have a constant offset, just
|
|
// evaluate it the general way.
|
|
if (i == e) return 0;
|
|
|
|
Value *VariableIdx = GEP->getOperand(i);
|
|
// Determine the scale factor of the variable element. For example, this is
|
|
// 4 if the variable index is into an array of i32.
|
|
uint64_t VariableScale = TD.getTypePaddedSize(GTI.getIndexedType());
|
|
|
|
// Verify that there are no other variable indices. If so, emit the hard way.
|
|
for (++i, ++GTI; i != e; ++i, ++GTI) {
|
|
ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i));
|
|
if (!CI) return 0;
|
|
|
|
// Compute the aggregate offset of constant indices.
|
|
if (CI->isZero()) continue;
|
|
|
|
// Handle a struct index, which adds its field offset to the pointer.
|
|
if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
|
|
Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue());
|
|
} else {
|
|
uint64_t Size = TD.getTypePaddedSize(GTI.getIndexedType());
|
|
Offset += Size*CI->getSExtValue();
|
|
}
|
|
}
|
|
|
|
// Okay, we know we have a single variable index, which must be a
|
|
// pointer/array/vector index. If there is no offset, life is simple, return
|
|
// the index.
|
|
unsigned IntPtrWidth = TD.getPointerSizeInBits();
|
|
if (Offset == 0) {
|
|
// Cast to intptrty in case a truncation occurs. If an extension is needed,
|
|
// we don't need to bother extending: the extension won't affect where the
|
|
// computation crosses zero.
|
|
if (VariableIdx->getType()->getPrimitiveSizeInBits() > IntPtrWidth)
|
|
VariableIdx = new TruncInst(VariableIdx, TD.getIntPtrType(),
|
|
VariableIdx->getNameStart(), &I);
|
|
return VariableIdx;
|
|
}
|
|
|
|
// Otherwise, there is an index. The computation we will do will be modulo
|
|
// the pointer size, so get it.
|
|
uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth);
|
|
|
|
Offset &= PtrSizeMask;
|
|
VariableScale &= PtrSizeMask;
|
|
|
|
// To do this transformation, any constant index must be a multiple of the
|
|
// variable scale factor. For example, we can evaluate "12 + 4*i" as "3 + i",
|
|
// but we can't evaluate "10 + 3*i" in terms of i. Check that the offset is a
|
|
// multiple of the variable scale.
|
|
int64_t NewOffs = Offset / (int64_t)VariableScale;
|
|
if (Offset != NewOffs*(int64_t)VariableScale)
|
|
return 0;
|
|
|
|
// Okay, we can do this evaluation. Start by converting the index to intptr.
|
|
const Type *IntPtrTy = TD.getIntPtrType();
|
|
if (VariableIdx->getType() != IntPtrTy)
|
|
VariableIdx = CastInst::CreateIntegerCast(VariableIdx, IntPtrTy,
|
|
true /*SExt*/,
|
|
VariableIdx->getNameStart(), &I);
|
|
Constant *OffsetVal = ConstantInt::get(IntPtrTy, NewOffs);
|
|
return BinaryOperator::CreateAdd(VariableIdx, OffsetVal, "offset", &I);
|
|
}
|
|
|
|
|
|
/// FoldGEPICmp - Fold comparisons between a GEP instruction and something
|
|
/// else. At this point we know that the GEP is on the LHS of the comparison.
|
|
Instruction *InstCombiner::FoldGEPICmp(User *GEPLHS, Value *RHS,
|
|
ICmpInst::Predicate Cond,
|
|
Instruction &I) {
|
|
assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!");
|
|
|
|
// Look through bitcasts.
|
|
if (BitCastInst *BCI = dyn_cast<BitCastInst>(RHS))
|
|
RHS = BCI->getOperand(0);
|
|
|
|
Value *PtrBase = GEPLHS->getOperand(0);
|
|
if (PtrBase == RHS) {
|
|
// ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
|
|
// This transformation (ignoring the base and scales) is valid because we
|
|
// know pointers can't overflow. See if we can output an optimized form.
|
|
Value *Offset = EvaluateGEPOffsetExpression(GEPLHS, I, *this);
|
|
|
|
// If not, synthesize the offset the hard way.
|
|
if (Offset == 0)
|
|
Offset = EmitGEPOffset(GEPLHS, I, *this);
|
|
return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset,
|
|
Constant::getNullValue(Offset->getType()));
|
|
} else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) {
|
|
// If the base pointers are different, but the indices are the same, just
|
|
// compare the base pointer.
|
|
if (PtrBase != GEPRHS->getOperand(0)) {
|
|
bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands();
|
|
IndicesTheSame &= GEPLHS->getOperand(0)->getType() ==
|
|
GEPRHS->getOperand(0)->getType();
|
|
if (IndicesTheSame)
|
|
for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
|
|
if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
|
|
IndicesTheSame = false;
|
|
break;
|
|
}
|
|
|
|
// If all indices are the same, just compare the base pointers.
|
|
if (IndicesTheSame)
|
|
return new ICmpInst(ICmpInst::getSignedPredicate(Cond),
|
|
GEPLHS->getOperand(0), GEPRHS->getOperand(0));
|
|
|
|
// Otherwise, the base pointers are different and the indices are
|
|
// different, bail out.
|
|
return 0;
|
|
}
|
|
|
|
// If one of the GEPs has all zero indices, recurse.
|
|
bool AllZeros = true;
|
|
for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i)
|
|
if (!isa<Constant>(GEPLHS->getOperand(i)) ||
|
|
!cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) {
|
|
AllZeros = false;
|
|
break;
|
|
}
|
|
if (AllZeros)
|
|
return FoldGEPICmp(GEPRHS, GEPLHS->getOperand(0),
|
|
ICmpInst::getSwappedPredicate(Cond), I);
|
|
|
|
// If the other GEP has all zero indices, recurse.
|
|
AllZeros = true;
|
|
for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
|
|
if (!isa<Constant>(GEPRHS->getOperand(i)) ||
|
|
!cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) {
|
|
AllZeros = false;
|
|
break;
|
|
}
|
|
if (AllZeros)
|
|
return FoldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I);
|
|
|
|
if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) {
|
|
// If the GEPs only differ by one index, compare it.
|
|
unsigned NumDifferences = 0; // Keep track of # differences.
|
|
unsigned DiffOperand = 0; // The operand that differs.
|
|
for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i)
|
|
if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) {
|
|
if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() !=
|
|
GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) {
|
|
// Irreconcilable differences.
|
|
NumDifferences = 2;
|
|
break;
|
|
} else {
|
|
if (NumDifferences++) break;
|
|
DiffOperand = i;
|
|
}
|
|
}
|
|
|
|
if (NumDifferences == 0) // SAME GEP?
|
|
return ReplaceInstUsesWith(I, // No comparison is needed here.
|
|
ConstantInt::get(Type::Int1Ty,
|
|
ICmpInst::isTrueWhenEqual(Cond)));
|
|
|
|
else if (NumDifferences == 1) {
|
|
Value *LHSV = GEPLHS->getOperand(DiffOperand);
|
|
Value *RHSV = GEPRHS->getOperand(DiffOperand);
|
|
// Make sure we do a signed comparison here.
|
|
return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV);
|
|
}
|
|
}
|
|
|
|
// Only lower this if the icmp is the only user of the GEP or if we expect
|
|
// the result to fold to a constant!
|
|
if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) &&
|
|
(isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) {
|
|
// ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2)
|
|
Value *L = EmitGEPOffset(GEPLHS, I, *this);
|
|
Value *R = EmitGEPOffset(GEPRHS, I, *this);
|
|
return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R);
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/// FoldFCmp_IntToFP_Cst - Fold fcmp ([us]itofp x, cst) if possible.
|
|
///
|
|
Instruction *InstCombiner::FoldFCmp_IntToFP_Cst(FCmpInst &I,
|
|
Instruction *LHSI,
|
|
Constant *RHSC) {
|
|
if (!isa<ConstantFP>(RHSC)) return 0;
|
|
const APFloat &RHS = cast<ConstantFP>(RHSC)->getValueAPF();
|
|
|
|
// Get the width of the mantissa. We don't want to hack on conversions that
|
|
// might lose information from the integer, e.g. "i64 -> float"
|
|
int MantissaWidth = LHSI->getType()->getFPMantissaWidth();
|
|
if (MantissaWidth == -1) return 0; // Unknown.
|
|
|
|
// Check to see that the input is converted from an integer type that is small
|
|
// enough that preserves all bits. TODO: check here for "known" sign bits.
|
|
// This would allow us to handle (fptosi (x >>s 62) to float) if x is i64 f.e.
|
|
unsigned InputSize = LHSI->getOperand(0)->getType()->getPrimitiveSizeInBits();
|
|
|
|
// If this is a uitofp instruction, we need an extra bit to hold the sign.
|
|
bool LHSUnsigned = isa<UIToFPInst>(LHSI);
|
|
if (LHSUnsigned)
|
|
++InputSize;
|
|
|
|
// If the conversion would lose info, don't hack on this.
|
|
if ((int)InputSize > MantissaWidth)
|
|
return 0;
|
|
|
|
// Otherwise, we can potentially simplify the comparison. We know that it
|
|
// will always come through as an integer value and we know the constant is
|
|
// not a NAN (it would have been previously simplified).
|
|
assert(!RHS.isNaN() && "NaN comparison not already folded!");
|
|
|
|
ICmpInst::Predicate Pred;
|
|
switch (I.getPredicate()) {
|
|
default: assert(0 && "Unexpected predicate!");
|
|
case FCmpInst::FCMP_UEQ:
|
|
case FCmpInst::FCMP_OEQ:
|
|
Pred = ICmpInst::ICMP_EQ;
|
|
break;
|
|
case FCmpInst::FCMP_UGT:
|
|
case FCmpInst::FCMP_OGT:
|
|
Pred = LHSUnsigned ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_SGT;
|
|
break;
|
|
case FCmpInst::FCMP_UGE:
|
|
case FCmpInst::FCMP_OGE:
|
|
Pred = LHSUnsigned ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_SGE;
|
|
break;
|
|
case FCmpInst::FCMP_ULT:
|
|
case FCmpInst::FCMP_OLT:
|
|
Pred = LHSUnsigned ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_SLT;
|
|
break;
|
|
case FCmpInst::FCMP_ULE:
|
|
case FCmpInst::FCMP_OLE:
|
|
Pred = LHSUnsigned ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_SLE;
|
|
break;
|
|
case FCmpInst::FCMP_UNE:
|
|
case FCmpInst::FCMP_ONE:
|
|
Pred = ICmpInst::ICMP_NE;
|
|
break;
|
|
case FCmpInst::FCMP_ORD:
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
case FCmpInst::FCMP_UNO:
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
}
|
|
|
|
const IntegerType *IntTy = cast<IntegerType>(LHSI->getOperand(0)->getType());
|
|
|
|
// Now we know that the APFloat is a normal number, zero or inf.
|
|
|
|
// See if the FP constant is too large for the integer. For example,
|
|
// comparing an i8 to 300.0.
|
|
unsigned IntWidth = IntTy->getPrimitiveSizeInBits();
|
|
|
|
if (!LHSUnsigned) {
|
|
// If the RHS value is > SignedMax, fold the comparison. This handles +INF
|
|
// and large values.
|
|
APFloat SMax(RHS.getSemantics(), APFloat::fcZero, false);
|
|
SMax.convertFromAPInt(APInt::getSignedMaxValue(IntWidth), true,
|
|
APFloat::rmNearestTiesToEven);
|
|
if (SMax.compare(RHS) == APFloat::cmpLessThan) { // smax < 13123.0
|
|
if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SLT ||
|
|
Pred == ICmpInst::ICMP_SLE)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
}
|
|
} else {
|
|
// If the RHS value is > UnsignedMax, fold the comparison. This handles
|
|
// +INF and large values.
|
|
APFloat UMax(RHS.getSemantics(), APFloat::fcZero, false);
|
|
UMax.convertFromAPInt(APInt::getMaxValue(IntWidth), false,
|
|
APFloat::rmNearestTiesToEven);
|
|
if (UMax.compare(RHS) == APFloat::cmpLessThan) { // umax < 13123.0
|
|
if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_ULT ||
|
|
Pred == ICmpInst::ICMP_ULE)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
}
|
|
}
|
|
|
|
if (!LHSUnsigned) {
|
|
// See if the RHS value is < SignedMin.
|
|
APFloat SMin(RHS.getSemantics(), APFloat::fcZero, false);
|
|
SMin.convertFromAPInt(APInt::getSignedMinValue(IntWidth), true,
|
|
APFloat::rmNearestTiesToEven);
|
|
if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // smin > 12312.0
|
|
if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT ||
|
|
Pred == ICmpInst::ICMP_SGE)
|
|
return ReplaceInstUsesWith(I,ConstantInt::getTrue());
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
}
|
|
}
|
|
|
|
// Okay, now we know that the FP constant fits in the range [SMIN, SMAX] or
|
|
// [0, UMAX], but it may still be fractional. See if it is fractional by
|
|
// casting the FP value to the integer value and back, checking for equality.
|
|
// Don't do this for zero, because -0.0 is not fractional.
|
|
Constant *RHSInt = ConstantExpr::getFPToSI(RHSC, IntTy);
|
|
if (!RHS.isZero() &&
|
|
ConstantExpr::getSIToFP(RHSInt, RHSC->getType()) != RHSC) {
|
|
// If we had a comparison against a fractional value, we have to adjust the
|
|
// compare predicate and sometimes the value. RHSC is rounded towards zero
|
|
// at this point.
|
|
switch (Pred) {
|
|
default: assert(0 && "Unexpected integer comparison!");
|
|
case ICmpInst::ICMP_NE: // (float)int != 4.4 --> true
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
case ICmpInst::ICMP_EQ: // (float)int == 4.4 --> false
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
case ICmpInst::ICMP_ULE:
|
|
// (float)int <= 4.4 --> int <= 4
|
|
// (float)int <= -4.4 --> false
|
|
if (RHS.isNegative())
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
break;
|
|
case ICmpInst::ICMP_SLE:
|
|
// (float)int <= 4.4 --> int <= 4
|
|
// (float)int <= -4.4 --> int < -4
|
|
if (RHS.isNegative())
|
|
Pred = ICmpInst::ICMP_SLT;
|
|
break;
|
|
case ICmpInst::ICMP_ULT:
|
|
// (float)int < -4.4 --> false
|
|
// (float)int < 4.4 --> int <= 4
|
|
if (RHS.isNegative())
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
Pred = ICmpInst::ICMP_ULE;
|
|
break;
|
|
case ICmpInst::ICMP_SLT:
|
|
// (float)int < -4.4 --> int < -4
|
|
// (float)int < 4.4 --> int <= 4
|
|
if (!RHS.isNegative())
|
|
Pred = ICmpInst::ICMP_SLE;
|
|
break;
|
|
case ICmpInst::ICMP_UGT:
|
|
// (float)int > 4.4 --> int > 4
|
|
// (float)int > -4.4 --> true
|
|
if (RHS.isNegative())
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
break;
|
|
case ICmpInst::ICMP_SGT:
|
|
// (float)int > 4.4 --> int > 4
|
|
// (float)int > -4.4 --> int >= -4
|
|
if (RHS.isNegative())
|
|
Pred = ICmpInst::ICMP_SGE;
|
|
break;
|
|
case ICmpInst::ICMP_UGE:
|
|
// (float)int >= -4.4 --> true
|
|
// (float)int >= 4.4 --> int > 4
|
|
if (!RHS.isNegative())
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
Pred = ICmpInst::ICMP_UGT;
|
|
break;
|
|
case ICmpInst::ICMP_SGE:
|
|
// (float)int >= -4.4 --> int >= -4
|
|
// (float)int >= 4.4 --> int > 4
|
|
if (!RHS.isNegative())
|
|
Pred = ICmpInst::ICMP_SGT;
|
|
break;
|
|
}
|
|
}
|
|
|
|
// Lower this FP comparison into an appropriate integer version of the
|
|
// comparison.
|
|
return new ICmpInst(Pred, LHSI->getOperand(0), RHSInt);
|
|
}
|
|
|
|
Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
|
|
bool Changed = SimplifyCompare(I);
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
// Fold trivial predicates.
|
|
if (I.getPredicate() == FCmpInst::FCMP_FALSE)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
if (I.getPredicate() == FCmpInst::FCMP_TRUE)
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
|
|
// Simplify 'fcmp pred X, X'
|
|
if (Op0 == Op1) {
|
|
switch (I.getPredicate()) {
|
|
default: assert(0 && "Unknown predicate!");
|
|
case FCmpInst::FCMP_UEQ: // True if unordered or equal
|
|
case FCmpInst::FCMP_UGE: // True if unordered, greater than, or equal
|
|
case FCmpInst::FCMP_ULE: // True if unordered, less than, or equal
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
case FCmpInst::FCMP_OGT: // True if ordered and greater than
|
|
case FCmpInst::FCMP_OLT: // True if ordered and less than
|
|
case FCmpInst::FCMP_ONE: // True if ordered and operands are unequal
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
|
|
case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y)
|
|
case FCmpInst::FCMP_ULT: // True if unordered or less than
|
|
case FCmpInst::FCMP_UGT: // True if unordered or greater than
|
|
case FCmpInst::FCMP_UNE: // True if unordered or not equal
|
|
// Canonicalize these to be 'fcmp uno %X, 0.0'.
|
|
I.setPredicate(FCmpInst::FCMP_UNO);
|
|
I.setOperand(1, Constant::getNullValue(Op0->getType()));
|
|
return &I;
|
|
|
|
case FCmpInst::FCMP_ORD: // True if ordered (no nans)
|
|
case FCmpInst::FCMP_OEQ: // True if ordered and equal
|
|
case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal
|
|
case FCmpInst::FCMP_OLE: // True if ordered and less than or equal
|
|
// Canonicalize these to be 'fcmp ord %X, 0.0'.
|
|
I.setPredicate(FCmpInst::FCMP_ORD);
|
|
I.setOperand(1, Constant::getNullValue(Op0->getType()));
|
|
return &I;
|
|
}
|
|
}
|
|
|
|
if (isa<UndefValue>(Op1)) // fcmp pred X, undef -> undef
|
|
return ReplaceInstUsesWith(I, UndefValue::get(Type::Int1Ty));
|
|
|
|
// Handle fcmp with constant RHS
|
|
if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
|
|
// If the constant is a nan, see if we can fold the comparison based on it.
|
|
if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) {
|
|
if (CFP->getValueAPF().isNaN()) {
|
|
if (FCmpInst::isOrdered(I.getPredicate())) // True if ordered and...
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
assert(FCmpInst::isUnordered(I.getPredicate()) &&
|
|
"Comparison must be either ordered or unordered!");
|
|
// True if unordered.
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
}
|
|
}
|
|
|
|
if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
|
|
switch (LHSI->getOpcode()) {
|
|
case Instruction::PHI:
|
|
// Only fold fcmp into the PHI if the phi and fcmp are in the same
|
|
// block. If in the same block, we're encouraging jump threading. If
|
|
// not, we are just pessimizing the code by making an i1 phi.
|
|
if (LHSI->getParent() == I.getParent())
|
|
if (Instruction *NV = FoldOpIntoPhi(I))
|
|
return NV;
|
|
break;
|
|
case Instruction::SIToFP:
|
|
case Instruction::UIToFP:
|
|
if (Instruction *NV = FoldFCmp_IntToFP_Cst(I, LHSI, RHSC))
|
|
return NV;
|
|
break;
|
|
case Instruction::Select:
|
|
// If either operand of the select is a constant, we can fold the
|
|
// comparison into the select arms, which will cause one to be
|
|
// constant folded and the select turned into a bitwise or.
|
|
Value *Op1 = 0, *Op2 = 0;
|
|
if (LHSI->hasOneUse()) {
|
|
if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
|
|
// Fold the known value into the constant operand.
|
|
Op1 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
|
|
// Insert a new FCmp of the other select operand.
|
|
Op2 = InsertNewInstBefore(new FCmpInst(I.getPredicate(),
|
|
LHSI->getOperand(2), RHSC,
|
|
I.getName()), I);
|
|
} else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
|
|
// Fold the known value into the constant operand.
|
|
Op2 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC);
|
|
// Insert a new FCmp of the other select operand.
|
|
Op1 = InsertNewInstBefore(new FCmpInst(I.getPredicate(),
|
|
LHSI->getOperand(1), RHSC,
|
|
I.getName()), I);
|
|
}
|
|
}
|
|
|
|
if (Op1)
|
|
return SelectInst::Create(LHSI->getOperand(0), Op1, Op2);
|
|
break;
|
|
}
|
|
}
|
|
|
|
return Changed ? &I : 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
|
|
bool Changed = SimplifyCompare(I);
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
const Type *Ty = Op0->getType();
|
|
|
|
// icmp X, X
|
|
if (Op0 == Op1)
|
|
return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
|
|
I.isTrueWhenEqual()));
|
|
|
|
if (isa<UndefValue>(Op1)) // X icmp undef -> undef
|
|
return ReplaceInstUsesWith(I, UndefValue::get(Type::Int1Ty));
|
|
|
|
// icmp <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
|
|
// addresses never equal each other! We already know that Op0 != Op1.
|
|
if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) ||
|
|
isa<ConstantPointerNull>(Op0)) &&
|
|
(isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) ||
|
|
isa<ConstantPointerNull>(Op1)))
|
|
return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
|
|
!I.isTrueWhenEqual()));
|
|
|
|
// icmp's with boolean values can always be turned into bitwise operations
|
|
if (Ty == Type::Int1Ty) {
|
|
switch (I.getPredicate()) {
|
|
default: assert(0 && "Invalid icmp instruction!");
|
|
case ICmpInst::ICMP_EQ: { // icmp eq i1 A, B -> ~(A^B)
|
|
Instruction *Xor = BinaryOperator::CreateXor(Op0, Op1, I.getName()+"tmp");
|
|
InsertNewInstBefore(Xor, I);
|
|
return BinaryOperator::CreateNot(Xor);
|
|
}
|
|
case ICmpInst::ICMP_NE: // icmp eq i1 A, B -> A^B
|
|
return BinaryOperator::CreateXor(Op0, Op1);
|
|
|
|
case ICmpInst::ICMP_UGT:
|
|
std::swap(Op0, Op1); // Change icmp ugt -> icmp ult
|
|
// FALL THROUGH
|
|
case ICmpInst::ICMP_ULT:{ // icmp ult i1 A, B -> ~A & B
|
|
Instruction *Not = BinaryOperator::CreateNot(Op0, I.getName()+"tmp");
|
|
InsertNewInstBefore(Not, I);
|
|
return BinaryOperator::CreateAnd(Not, Op1);
|
|
}
|
|
case ICmpInst::ICMP_SGT:
|
|
std::swap(Op0, Op1); // Change icmp sgt -> icmp slt
|
|
// FALL THROUGH
|
|
case ICmpInst::ICMP_SLT: { // icmp slt i1 A, B -> A & ~B
|
|
Instruction *Not = BinaryOperator::CreateNot(Op1, I.getName()+"tmp");
|
|
InsertNewInstBefore(Not, I);
|
|
return BinaryOperator::CreateAnd(Not, Op0);
|
|
}
|
|
case ICmpInst::ICMP_UGE:
|
|
std::swap(Op0, Op1); // Change icmp uge -> icmp ule
|
|
// FALL THROUGH
|
|
case ICmpInst::ICMP_ULE: { // icmp ule i1 A, B -> ~A | B
|
|
Instruction *Not = BinaryOperator::CreateNot(Op0, I.getName()+"tmp");
|
|
InsertNewInstBefore(Not, I);
|
|
return BinaryOperator::CreateOr(Not, Op1);
|
|
}
|
|
case ICmpInst::ICMP_SGE:
|
|
std::swap(Op0, Op1); // Change icmp sge -> icmp sle
|
|
// FALL THROUGH
|
|
case ICmpInst::ICMP_SLE: { // icmp sle i1 A, B -> A | ~B
|
|
Instruction *Not = BinaryOperator::CreateNot(Op1, I.getName()+"tmp");
|
|
InsertNewInstBefore(Not, I);
|
|
return BinaryOperator::CreateOr(Not, Op0);
|
|
}
|
|
}
|
|
}
|
|
|
|
// See if we are doing a comparison with a constant.
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
|
|
Value *A, *B;
|
|
|
|
// (icmp ne/eq (sub A B) 0) -> (icmp ne/eq A, B)
|
|
if (I.isEquality() && CI->isNullValue() &&
|
|
match(Op0, m_Sub(m_Value(A), m_Value(B)))) {
|
|
// (icmp cond A B) if cond is equality
|
|
return new ICmpInst(I.getPredicate(), A, B);
|
|
}
|
|
|
|
// If we have an icmp le or icmp ge instruction, turn it into the
|
|
// appropriate icmp lt or icmp gt instruction. This allows us to rely on
|
|
// them being folded in the code below.
|
|
switch (I.getPredicate()) {
|
|
default: break;
|
|
case ICmpInst::ICMP_ULE:
|
|
if (CI->isMaxValue(false)) // A <=u MAX -> TRUE
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
return new ICmpInst(ICmpInst::ICMP_ULT, Op0, AddOne(CI));
|
|
case ICmpInst::ICMP_SLE:
|
|
if (CI->isMaxValue(true)) // A <=s MAX -> TRUE
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
return new ICmpInst(ICmpInst::ICMP_SLT, Op0, AddOne(CI));
|
|
case ICmpInst::ICMP_UGE:
|
|
if (CI->isMinValue(false)) // A >=u MIN -> TRUE
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
return new ICmpInst( ICmpInst::ICMP_UGT, Op0, SubOne(CI));
|
|
case ICmpInst::ICMP_SGE:
|
|
if (CI->isMinValue(true)) // A >=s MIN -> TRUE
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
return new ICmpInst(ICmpInst::ICMP_SGT, Op0, SubOne(CI));
|
|
}
|
|
|
|
// See if we can fold the comparison based on range information we can get
|
|
// by checking whether bits are known to be zero or one in the input.
|
|
uint32_t BitWidth = cast<IntegerType>(Ty)->getBitWidth();
|
|
APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
|
|
|
|
// If this comparison is a normal comparison, it demands all
|
|
// bits, if it is a sign bit comparison, it only demands the sign bit.
|
|
bool UnusedBit;
|
|
bool isSignBit = isSignBitCheck(I.getPredicate(), CI, UnusedBit);
|
|
|
|
if (SimplifyDemandedBits(I.getOperandUse(0),
|
|
isSignBit ? APInt::getSignBit(BitWidth)
|
|
: APInt::getAllOnesValue(BitWidth),
|
|
KnownZero, KnownOne, 0))
|
|
return &I;
|
|
|
|
// Given the known and unknown bits, compute a range that the LHS could be
|
|
// in. Compute the Min, Max and RHS values based on the known bits. For the
|
|
// EQ and NE we use unsigned values.
|
|
APInt Min(BitWidth, 0), Max(BitWidth, 0);
|
|
if (ICmpInst::isSignedPredicate(I.getPredicate()))
|
|
ComputeSignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne, Min, Max);
|
|
else
|
|
ComputeUnsignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne,Min,Max);
|
|
|
|
// If Min and Max are known to be the same, then SimplifyDemandedBits
|
|
// figured out that the LHS is a constant. Just constant fold this now so
|
|
// that code below can assume that Min != Max.
|
|
if (Min == Max)
|
|
return ReplaceInstUsesWith(I, ConstantExpr::getICmp(I.getPredicate(),
|
|
ConstantInt::get(Min),
|
|
CI));
|
|
|
|
// Based on the range information we know about the LHS, see if we can
|
|
// simplify this comparison. For example, (x&4) < 8 is always true.
|
|
const APInt &RHSVal = CI->getValue();
|
|
switch (I.getPredicate()) { // LE/GE have been folded already.
|
|
default: assert(0 && "Unknown icmp opcode!");
|
|
case ICmpInst::ICMP_EQ:
|
|
if (Max.ult(RHSVal) || Min.ugt(RHSVal))
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
break;
|
|
case ICmpInst::ICMP_NE:
|
|
if (Max.ult(RHSVal) || Min.ugt(RHSVal))
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
break;
|
|
case ICmpInst::ICMP_ULT:
|
|
if (Max.ult(RHSVal)) // A <u C -> true iff max(A) < C
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
if (Min.uge(RHSVal)) // A <u C -> false iff min(A) >= C
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
if (RHSVal == Max) // A <u MAX -> A != MAX
|
|
return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
|
|
if (RHSVal == Min+1) // A <u MIN+1 -> A == MIN
|
|
return new ICmpInst(ICmpInst::ICMP_EQ, Op0, SubOne(CI));
|
|
|
|
// (x <u 2147483648) -> (x >s -1) -> true if sign bit clear
|
|
if (CI->isMinValue(true))
|
|
return new ICmpInst(ICmpInst::ICMP_SGT, Op0,
|
|
ConstantInt::getAllOnesValue(Op0->getType()));
|
|
break;
|
|
case ICmpInst::ICMP_UGT:
|
|
if (Min.ugt(RHSVal)) // A >u C -> true iff min(A) > C
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
if (Max.ule(RHSVal)) // A >u C -> false iff max(A) <= C
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
|
|
if (RHSVal == Min) // A >u MIN -> A != MIN
|
|
return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
|
|
if (RHSVal == Max-1) // A >u MAX-1 -> A == MAX
|
|
return new ICmpInst(ICmpInst::ICMP_EQ, Op0, AddOne(CI));
|
|
|
|
// (x >u 2147483647) -> (x <s 0) -> true if sign bit set
|
|
if (CI->isMaxValue(true))
|
|
return new ICmpInst(ICmpInst::ICMP_SLT, Op0,
|
|
ConstantInt::getNullValue(Op0->getType()));
|
|
break;
|
|
case ICmpInst::ICMP_SLT:
|
|
if (Max.slt(RHSVal)) // A <s C -> true iff max(A) < C
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
if (Min.sge(RHSVal)) // A <s C -> false iff min(A) >= C
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
if (RHSVal == Max) // A <s MAX -> A != MAX
|
|
return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
|
|
if (RHSVal == Min+1) // A <s MIN+1 -> A == MIN
|
|
return new ICmpInst(ICmpInst::ICMP_EQ, Op0, SubOne(CI));
|
|
break;
|
|
case ICmpInst::ICMP_SGT:
|
|
if (Min.sgt(RHSVal)) // A >s C -> true iff min(A) > C
|
|
return ReplaceInstUsesWith(I, ConstantInt::getTrue());
|
|
if (Max.sle(RHSVal)) // A >s C -> false iff max(A) <= C
|
|
return ReplaceInstUsesWith(I, ConstantInt::getFalse());
|
|
|
|
if (RHSVal == Min) // A >s MIN -> A != MIN
|
|
return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1);
|
|
if (RHSVal == Max-1) // A >s MAX-1 -> A == MAX
|
|
return new ICmpInst(ICmpInst::ICMP_EQ, Op0, AddOne(CI));
|
|
break;
|
|
}
|
|
}
|
|
|
|
// Test if the ICmpInst instruction is used exclusively by a select as
|
|
// part of a minimum or maximum operation. If so, refrain from doing
|
|
// any other folding. This helps out other analyses which understand
|
|
// non-obfuscated minimum and maximum idioms, such as ScalarEvolution
|
|
// and CodeGen. And in this case, at least one of the comparison
|
|
// operands has at least one user besides the compare (the select),
|
|
// which would often largely negate the benefit of folding anyway.
|
|
if (I.hasOneUse())
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(*I.use_begin()))
|
|
if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) ||
|
|
(SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1))
|
|
return 0;
|
|
|
|
// See if we are doing a comparison between a constant and an instruction that
|
|
// can be folded into the comparison.
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
|
|
// Since the RHS is a ConstantInt (CI), if the left hand side is an
|
|
// instruction, see if that instruction also has constants so that the
|
|
// instruction can be folded into the icmp
|
|
if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
|
|
if (Instruction *Res = visitICmpInstWithInstAndIntCst(I, LHSI, CI))
|
|
return Res;
|
|
}
|
|
|
|
// Handle icmp with constant (but not simple integer constant) RHS
|
|
if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
|
|
if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
|
|
switch (LHSI->getOpcode()) {
|
|
case Instruction::GetElementPtr:
|
|
if (RHSC->isNullValue()) {
|
|
// icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null
|
|
bool isAllZeros = true;
|
|
for (unsigned i = 1, e = LHSI->getNumOperands(); i != e; ++i)
|
|
if (!isa<Constant>(LHSI->getOperand(i)) ||
|
|
!cast<Constant>(LHSI->getOperand(i))->isNullValue()) {
|
|
isAllZeros = false;
|
|
break;
|
|
}
|
|
if (isAllZeros)
|
|
return new ICmpInst(I.getPredicate(), LHSI->getOperand(0),
|
|
Constant::getNullValue(LHSI->getOperand(0)->getType()));
|
|
}
|
|
break;
|
|
|
|
case Instruction::PHI:
|
|
// Only fold icmp into the PHI if the phi and fcmp are in the same
|
|
// block. If in the same block, we're encouraging jump threading. If
|
|
// not, we are just pessimizing the code by making an i1 phi.
|
|
if (LHSI->getParent() == I.getParent())
|
|
if (Instruction *NV = FoldOpIntoPhi(I))
|
|
return NV;
|
|
break;
|
|
case Instruction::Select: {
|
|
// If either operand of the select is a constant, we can fold the
|
|
// comparison into the select arms, which will cause one to be
|
|
// constant folded and the select turned into a bitwise or.
|
|
Value *Op1 = 0, *Op2 = 0;
|
|
if (LHSI->hasOneUse()) {
|
|
if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) {
|
|
// Fold the known value into the constant operand.
|
|
Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
|
|
// Insert a new ICmp of the other select operand.
|
|
Op2 = InsertNewInstBefore(new ICmpInst(I.getPredicate(),
|
|
LHSI->getOperand(2), RHSC,
|
|
I.getName()), I);
|
|
} else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) {
|
|
// Fold the known value into the constant operand.
|
|
Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC);
|
|
// Insert a new ICmp of the other select operand.
|
|
Op1 = InsertNewInstBefore(new ICmpInst(I.getPredicate(),
|
|
LHSI->getOperand(1), RHSC,
|
|
I.getName()), I);
|
|
}
|
|
}
|
|
|
|
if (Op1)
|
|
return SelectInst::Create(LHSI->getOperand(0), Op1, Op2);
|
|
break;
|
|
}
|
|
case Instruction::Malloc:
|
|
// If we have (malloc != null), and if the malloc has a single use, we
|
|
// can assume it is successful and remove the malloc.
|
|
if (LHSI->hasOneUse() && isa<ConstantPointerNull>(RHSC)) {
|
|
AddToWorkList(LHSI);
|
|
return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
|
|
!I.isTrueWhenEqual()));
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
|
|
// If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now.
|
|
if (User *GEP = dyn_castGetElementPtr(Op0))
|
|
if (Instruction *NI = FoldGEPICmp(GEP, Op1, I.getPredicate(), I))
|
|
return NI;
|
|
if (User *GEP = dyn_castGetElementPtr(Op1))
|
|
if (Instruction *NI = FoldGEPICmp(GEP, Op0,
|
|
ICmpInst::getSwappedPredicate(I.getPredicate()), I))
|
|
return NI;
|
|
|
|
// Test to see if the operands of the icmp are casted versions of other
|
|
// values. If the ptr->ptr cast can be stripped off both arguments, we do so
|
|
// now.
|
|
if (BitCastInst *CI = dyn_cast<BitCastInst>(Op0)) {
|
|
if (isa<PointerType>(Op0->getType()) &&
|
|
(isa<Constant>(Op1) || isa<BitCastInst>(Op1))) {
|
|
// We keep moving the cast from the left operand over to the right
|
|
// operand, where it can often be eliminated completely.
|
|
Op0 = CI->getOperand(0);
|
|
|
|
// If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast
|
|
// so eliminate it as well.
|
|
if (BitCastInst *CI2 = dyn_cast<BitCastInst>(Op1))
|
|
Op1 = CI2->getOperand(0);
|
|
|
|
// If Op1 is a constant, we can fold the cast into the constant.
|
|
if (Op0->getType() != Op1->getType()) {
|
|
if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
|
|
Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType());
|
|
} else {
|
|
// Otherwise, cast the RHS right before the icmp
|
|
Op1 = InsertBitCastBefore(Op1, Op0->getType(), I);
|
|
}
|
|
}
|
|
return new ICmpInst(I.getPredicate(), Op0, Op1);
|
|
}
|
|
}
|
|
|
|
if (isa<CastInst>(Op0)) {
|
|
// Handle the special case of: icmp (cast bool to X), <cst>
|
|
// This comes up when you have code like
|
|
// int X = A < B;
|
|
// if (X) ...
|
|
// For generality, we handle any zero-extension of any operand comparison
|
|
// with a constant or another cast from the same type.
|
|
if (isa<ConstantInt>(Op1) || isa<CastInst>(Op1))
|
|
if (Instruction *R = visitICmpInstWithCastAndCast(I))
|
|
return R;
|
|
}
|
|
|
|
// See if it's the same type of instruction on the left and right.
|
|
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
|
|
if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
|
|
if (Op0I->getOpcode() == Op1I->getOpcode() && Op0I->hasOneUse() &&
|
|
Op1I->hasOneUse() && Op0I->getOperand(1) == Op1I->getOperand(1)) {
|
|
switch (Op0I->getOpcode()) {
|
|
default: break;
|
|
case Instruction::Add:
|
|
case Instruction::Sub:
|
|
case Instruction::Xor:
|
|
if (I.isEquality()) // a+x icmp eq/ne b+x --> a icmp b
|
|
return new ICmpInst(I.getPredicate(), Op0I->getOperand(0),
|
|
Op1I->getOperand(0));
|
|
// icmp u/s (a ^ signbit), (b ^ signbit) --> icmp s/u a, b
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
|
|
if (CI->getValue().isSignBit()) {
|
|
ICmpInst::Predicate Pred = I.isSignedPredicate()
|
|
? I.getUnsignedPredicate()
|
|
: I.getSignedPredicate();
|
|
return new ICmpInst(Pred, Op0I->getOperand(0),
|
|
Op1I->getOperand(0));
|
|
}
|
|
|
|
if (CI->getValue().isMaxSignedValue()) {
|
|
ICmpInst::Predicate Pred = I.isSignedPredicate()
|
|
? I.getUnsignedPredicate()
|
|
: I.getSignedPredicate();
|
|
Pred = I.getSwappedPredicate(Pred);
|
|
return new ICmpInst(Pred, Op0I->getOperand(0),
|
|
Op1I->getOperand(0));
|
|
}
|
|
}
|
|
break;
|
|
case Instruction::Mul:
|
|
if (!I.isEquality())
|
|
break;
|
|
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
|
|
// a * Cst icmp eq/ne b * Cst --> a & Mask icmp b & Mask
|
|
// Mask = -1 >> count-trailing-zeros(Cst).
|
|
if (!CI->isZero() && !CI->isOne()) {
|
|
const APInt &AP = CI->getValue();
|
|
ConstantInt *Mask = ConstantInt::get(
|
|
APInt::getLowBitsSet(AP.getBitWidth(),
|
|
AP.getBitWidth() -
|
|
AP.countTrailingZeros()));
|
|
Instruction *And1 = BinaryOperator::CreateAnd(Op0I->getOperand(0),
|
|
Mask);
|
|
Instruction *And2 = BinaryOperator::CreateAnd(Op1I->getOperand(0),
|
|
Mask);
|
|
InsertNewInstBefore(And1, I);
|
|
InsertNewInstBefore(And2, I);
|
|
return new ICmpInst(I.getPredicate(), And1, And2);
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// ~x < ~y --> y < x
|
|
{ Value *A, *B;
|
|
if (match(Op0, m_Not(m_Value(A))) &&
|
|
match(Op1, m_Not(m_Value(B))))
|
|
return new ICmpInst(I.getPredicate(), B, A);
|
|
}
|
|
|
|
if (I.isEquality()) {
|
|
Value *A, *B, *C, *D;
|
|
|
|
// -x == -y --> x == y
|
|
if (match(Op0, m_Neg(m_Value(A))) &&
|
|
match(Op1, m_Neg(m_Value(B))))
|
|
return new ICmpInst(I.getPredicate(), A, B);
|
|
|
|
if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
|
|
if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0
|
|
Value *OtherVal = A == Op1 ? B : A;
|
|
return new ICmpInst(I.getPredicate(), OtherVal,
|
|
Constant::getNullValue(A->getType()));
|
|
}
|
|
|
|
if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) {
|
|
// A^c1 == C^c2 --> A == C^(c1^c2)
|
|
ConstantInt *C1, *C2;
|
|
if (match(B, m_ConstantInt(C1)) &&
|
|
match(D, m_ConstantInt(C2)) && Op1->hasOneUse()) {
|
|
Constant *NC = ConstantInt::get(C1->getValue() ^ C2->getValue());
|
|
Instruction *Xor = BinaryOperator::CreateXor(C, NC, "tmp");
|
|
return new ICmpInst(I.getPredicate(), A,
|
|
InsertNewInstBefore(Xor, I));
|
|
}
|
|
|
|
// A^B == A^D -> B == D
|
|
if (A == C) return new ICmpInst(I.getPredicate(), B, D);
|
|
if (A == D) return new ICmpInst(I.getPredicate(), B, C);
|
|
if (B == C) return new ICmpInst(I.getPredicate(), A, D);
|
|
if (B == D) return new ICmpInst(I.getPredicate(), A, C);
|
|
}
|
|
}
|
|
|
|
if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
|
|
(A == Op0 || B == Op0)) {
|
|
// A == (A^B) -> B == 0
|
|
Value *OtherVal = A == Op0 ? B : A;
|
|
return new ICmpInst(I.getPredicate(), OtherVal,
|
|
Constant::getNullValue(A->getType()));
|
|
}
|
|
|
|
// (A-B) == A -> B == 0
|
|
if (match(Op0, m_Sub(m_Specific(Op1), m_Value(B))))
|
|
return new ICmpInst(I.getPredicate(), B,
|
|
Constant::getNullValue(B->getType()));
|
|
|
|
// A == (A-B) -> B == 0
|
|
if (match(Op1, m_Sub(m_Specific(Op0), m_Value(B))))
|
|
return new ICmpInst(I.getPredicate(), B,
|
|
Constant::getNullValue(B->getType()));
|
|
|
|
// (X&Z) == (Y&Z) -> (X^Y) & Z == 0
|
|
if (Op0->hasOneUse() && Op1->hasOneUse() &&
|
|
match(Op0, m_And(m_Value(A), m_Value(B))) &&
|
|
match(Op1, m_And(m_Value(C), m_Value(D)))) {
|
|
Value *X = 0, *Y = 0, *Z = 0;
|
|
|
|
if (A == C) {
|
|
X = B; Y = D; Z = A;
|
|
} else if (A == D) {
|
|
X = B; Y = C; Z = A;
|
|
} else if (B == C) {
|
|
X = A; Y = D; Z = B;
|
|
} else if (B == D) {
|
|
X = A; Y = C; Z = B;
|
|
}
|
|
|
|
if (X) { // Build (X^Y) & Z
|
|
Op1 = InsertNewInstBefore(BinaryOperator::CreateXor(X, Y, "tmp"), I);
|
|
Op1 = InsertNewInstBefore(BinaryOperator::CreateAnd(Op1, Z, "tmp"), I);
|
|
I.setOperand(0, Op1);
|
|
I.setOperand(1, Constant::getNullValue(Op1->getType()));
|
|
return &I;
|
|
}
|
|
}
|
|
}
|
|
return Changed ? &I : 0;
|
|
}
|
|
|
|
|
|
/// FoldICmpDivCst - Fold "icmp pred, ([su]div X, DivRHS), CmpRHS" where DivRHS
|
|
/// and CmpRHS are both known to be integer constants.
|
|
Instruction *InstCombiner::FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
|
|
ConstantInt *DivRHS) {
|
|
ConstantInt *CmpRHS = cast<ConstantInt>(ICI.getOperand(1));
|
|
const APInt &CmpRHSV = CmpRHS->getValue();
|
|
|
|
// FIXME: If the operand types don't match the type of the divide
|
|
// then don't attempt this transform. The code below doesn't have the
|
|
// logic to deal with a signed divide and an unsigned compare (and
|
|
// vice versa). This is because (x /s C1) <s C2 produces different
|
|
// results than (x /s C1) <u C2 or (x /u C1) <s C2 or even
|
|
// (x /u C1) <u C2. Simply casting the operands and result won't
|
|
// work. :( The if statement below tests that condition and bails
|
|
// if it finds it.
|
|
bool DivIsSigned = DivI->getOpcode() == Instruction::SDiv;
|
|
if (!ICI.isEquality() && DivIsSigned != ICI.isSignedPredicate())
|
|
return 0;
|
|
if (DivRHS->isZero())
|
|
return 0; // The ProdOV computation fails on divide by zero.
|
|
if (DivIsSigned && DivRHS->isAllOnesValue())
|
|
return 0; // The overflow computation also screws up here
|
|
if (DivRHS->isOne())
|
|
return 0; // Not worth bothering, and eliminates some funny cases
|
|
// with INT_MIN.
|
|
|
|
// Compute Prod = CI * DivRHS. We are essentially solving an equation
|
|
// of form X/C1=C2. We solve for X by multiplying C1 (DivRHS) and
|
|
// C2 (CI). By solving for X we can turn this into a range check
|
|
// instead of computing a divide.
|
|
ConstantInt *Prod = Multiply(CmpRHS, DivRHS);
|
|
|
|
// Determine if the product overflows by seeing if the product is
|
|
// not equal to the divide. Make sure we do the same kind of divide
|
|
// as in the LHS instruction that we're folding.
|
|
bool ProdOV = (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS) :
|
|
ConstantExpr::getUDiv(Prod, DivRHS)) != CmpRHS;
|
|
|
|
// Get the ICmp opcode
|
|
ICmpInst::Predicate Pred = ICI.getPredicate();
|
|
|
|
// Figure out the interval that is being checked. For example, a comparison
|
|
// like "X /u 5 == 0" is really checking that X is in the interval [0, 5).
|
|
// Compute this interval based on the constants involved and the signedness of
|
|
// the compare/divide. This computes a half-open interval, keeping track of
|
|
// whether either value in the interval overflows. After analysis each
|
|
// overflow variable is set to 0 if it's corresponding bound variable is valid
|
|
// -1 if overflowed off the bottom end, or +1 if overflowed off the top end.
|
|
int LoOverflow = 0, HiOverflow = 0;
|
|
ConstantInt *LoBound = 0, *HiBound = 0;
|
|
|
|
if (!DivIsSigned) { // udiv
|
|
// e.g. X/5 op 3 --> [15, 20)
|
|
LoBound = Prod;
|
|
HiOverflow = LoOverflow = ProdOV;
|
|
if (!HiOverflow)
|
|
HiOverflow = AddWithOverflow(HiBound, LoBound, DivRHS, false);
|
|
} else if (DivRHS->getValue().isStrictlyPositive()) { // Divisor is > 0.
|
|
if (CmpRHSV == 0) { // (X / pos) op 0
|
|
// Can't overflow. e.g. X/2 op 0 --> [-1, 2)
|
|
LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
|
|
HiBound = DivRHS;
|
|
} else if (CmpRHSV.isStrictlyPositive()) { // (X / pos) op pos
|
|
LoBound = Prod; // e.g. X/5 op 3 --> [15, 20)
|
|
HiOverflow = LoOverflow = ProdOV;
|
|
if (!HiOverflow)
|
|
HiOverflow = AddWithOverflow(HiBound, Prod, DivRHS, true);
|
|
} else { // (X / pos) op neg
|
|
// e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14)
|
|
HiBound = AddOne(Prod);
|
|
LoOverflow = HiOverflow = ProdOV ? -1 : 0;
|
|
if (!LoOverflow) {
|
|
ConstantInt* DivNeg = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
|
|
LoOverflow = AddWithOverflow(LoBound, HiBound, DivNeg,
|
|
true) ? -1 : 0;
|
|
}
|
|
}
|
|
} else if (DivRHS->getValue().isNegative()) { // Divisor is < 0.
|
|
if (CmpRHSV == 0) { // (X / neg) op 0
|
|
// e.g. X/-5 op 0 --> [-4, 5)
|
|
LoBound = AddOne(DivRHS);
|
|
HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
|
|
if (HiBound == DivRHS) { // -INTMIN = INTMIN
|
|
HiOverflow = 1; // [INTMIN+1, overflow)
|
|
HiBound = 0; // e.g. X/INTMIN = 0 --> X > INTMIN
|
|
}
|
|
} else if (CmpRHSV.isStrictlyPositive()) { // (X / neg) op pos
|
|
// e.g. X/-5 op 3 --> [-19, -14)
|
|
HiBound = AddOne(Prod);
|
|
HiOverflow = LoOverflow = ProdOV ? -1 : 0;
|
|
if (!LoOverflow)
|
|
LoOverflow = AddWithOverflow(LoBound, HiBound, DivRHS, true) ? -1 : 0;
|
|
} else { // (X / neg) op neg
|
|
LoBound = Prod; // e.g. X/-5 op -3 --> [15, 20)
|
|
LoOverflow = HiOverflow = ProdOV;
|
|
if (!HiOverflow)
|
|
HiOverflow = SubWithOverflow(HiBound, Prod, DivRHS, true);
|
|
}
|
|
|
|
// Dividing by a negative swaps the condition. LT <-> GT
|
|
Pred = ICmpInst::getSwappedPredicate(Pred);
|
|
}
|
|
|
|
Value *X = DivI->getOperand(0);
|
|
switch (Pred) {
|
|
default: assert(0 && "Unhandled icmp opcode!");
|
|
case ICmpInst::ICMP_EQ:
|
|
if (LoOverflow && HiOverflow)
|
|
return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
|
|
else if (HiOverflow)
|
|
return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
|
|
ICmpInst::ICMP_UGE, X, LoBound);
|
|
else if (LoOverflow)
|
|
return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
|
|
ICmpInst::ICMP_ULT, X, HiBound);
|
|
else
|
|
return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, true, ICI);
|
|
case ICmpInst::ICMP_NE:
|
|
if (LoOverflow && HiOverflow)
|
|
return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
|
|
else if (HiOverflow)
|
|
return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT :
|
|
ICmpInst::ICMP_ULT, X, LoBound);
|
|
else if (LoOverflow)
|
|
return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE :
|
|
ICmpInst::ICMP_UGE, X, HiBound);
|
|
else
|
|
return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, false, ICI);
|
|
case ICmpInst::ICMP_ULT:
|
|
case ICmpInst::ICMP_SLT:
|
|
if (LoOverflow == +1) // Low bound is greater than input range.
|
|
return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
|
|
if (LoOverflow == -1) // Low bound is less than input range.
|
|
return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
|
|
return new ICmpInst(Pred, X, LoBound);
|
|
case ICmpInst::ICMP_UGT:
|
|
case ICmpInst::ICMP_SGT:
|
|
if (HiOverflow == +1) // High bound greater than input range.
|
|
return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
|
|
else if (HiOverflow == -1) // High bound less than input range.
|
|
return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
|
|
if (Pred == ICmpInst::ICMP_UGT)
|
|
return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound);
|
|
else
|
|
return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound);
|
|
}
|
|
}
|
|
|
|
|
|
/// visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)".
|
|
///
|
|
Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
|
|
Instruction *LHSI,
|
|
ConstantInt *RHS) {
|
|
const APInt &RHSV = RHS->getValue();
|
|
|
|
switch (LHSI->getOpcode()) {
|
|
case Instruction::Trunc:
|
|
if (ICI.isEquality() && LHSI->hasOneUse()) {
|
|
// Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all
|
|
// of the high bits truncated out of x are known.
|
|
unsigned DstBits = LHSI->getType()->getPrimitiveSizeInBits(),
|
|
SrcBits = LHSI->getOperand(0)->getType()->getPrimitiveSizeInBits();
|
|
APInt Mask(APInt::getHighBitsSet(SrcBits, SrcBits-DstBits));
|
|
APInt KnownZero(SrcBits, 0), KnownOne(SrcBits, 0);
|
|
ComputeMaskedBits(LHSI->getOperand(0), Mask, KnownZero, KnownOne);
|
|
|
|
// If all the high bits are known, we can do this xform.
|
|
if ((KnownZero|KnownOne).countLeadingOnes() >= SrcBits-DstBits) {
|
|
// Pull in the high bits from known-ones set.
|
|
APInt NewRHS(RHS->getValue());
|
|
NewRHS.zext(SrcBits);
|
|
NewRHS |= KnownOne;
|
|
return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
|
|
ConstantInt::get(NewRHS));
|
|
}
|
|
}
|
|
break;
|
|
|
|
case Instruction::Xor: // (icmp pred (xor X, XorCST), CI)
|
|
if (ConstantInt *XorCST = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
|
|
// If this is a comparison that tests the signbit (X < 0) or (x > -1),
|
|
// fold the xor.
|
|
if ((ICI.getPredicate() == ICmpInst::ICMP_SLT && RHSV == 0) ||
|
|
(ICI.getPredicate() == ICmpInst::ICMP_SGT && RHSV.isAllOnesValue())) {
|
|
Value *CompareVal = LHSI->getOperand(0);
|
|
|
|
// If the sign bit of the XorCST is not set, there is no change to
|
|
// the operation, just stop using the Xor.
|
|
if (!XorCST->getValue().isNegative()) {
|
|
ICI.setOperand(0, CompareVal);
|
|
AddToWorkList(LHSI);
|
|
return &ICI;
|
|
}
|
|
|
|
// Was the old condition true if the operand is positive?
|
|
bool isTrueIfPositive = ICI.getPredicate() == ICmpInst::ICMP_SGT;
|
|
|
|
// If so, the new one isn't.
|
|
isTrueIfPositive ^= true;
|
|
|
|
if (isTrueIfPositive)
|
|
return new ICmpInst(ICmpInst::ICMP_SGT, CompareVal, SubOne(RHS));
|
|
else
|
|
return new ICmpInst(ICmpInst::ICMP_SLT, CompareVal, AddOne(RHS));
|
|
}
|
|
|
|
if (LHSI->hasOneUse()) {
|
|
// (icmp u/s (xor A SignBit), C) -> (icmp s/u A, (xor C SignBit))
|
|
if (!ICI.isEquality() && XorCST->getValue().isSignBit()) {
|
|
const APInt &SignBit = XorCST->getValue();
|
|
ICmpInst::Predicate Pred = ICI.isSignedPredicate()
|
|
? ICI.getUnsignedPredicate()
|
|
: ICI.getSignedPredicate();
|
|
return new ICmpInst(Pred, LHSI->getOperand(0),
|
|
ConstantInt::get(RHSV ^ SignBit));
|
|
}
|
|
|
|
// (icmp u/s (xor A ~SignBit), C) -> (icmp s/u (xor C ~SignBit), A)
|
|
if (!ICI.isEquality() && XorCST->getValue().isMaxSignedValue()) {
|
|
const APInt &NotSignBit = XorCST->getValue();
|
|
ICmpInst::Predicate Pred = ICI.isSignedPredicate()
|
|
? ICI.getUnsignedPredicate()
|
|
: ICI.getSignedPredicate();
|
|
Pred = ICI.getSwappedPredicate(Pred);
|
|
return new ICmpInst(Pred, LHSI->getOperand(0),
|
|
ConstantInt::get(RHSV ^ NotSignBit));
|
|
}
|
|
}
|
|
}
|
|
break;
|
|
case Instruction::And: // (icmp pred (and X, AndCST), RHS)
|
|
if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
|
|
LHSI->getOperand(0)->hasOneUse()) {
|
|
ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
|
|
|
|
// If the LHS is an AND of a truncating cast, we can widen the
|
|
// and/compare to be the input width without changing the value
|
|
// produced, eliminating a cast.
|
|
if (TruncInst *Cast = dyn_cast<TruncInst>(LHSI->getOperand(0))) {
|
|
// We can do this transformation if either the AND constant does not
|
|
// have its sign bit set or if it is an equality comparison.
|
|
// Extending a relational comparison when we're checking the sign
|
|
// bit would not work.
|
|
if (Cast->hasOneUse() &&
|
|
(ICI.isEquality() ||
|
|
(AndCST->getValue().isNonNegative() && RHSV.isNonNegative()))) {
|
|
uint32_t BitWidth =
|
|
cast<IntegerType>(Cast->getOperand(0)->getType())->getBitWidth();
|
|
APInt NewCST = AndCST->getValue();
|
|
NewCST.zext(BitWidth);
|
|
APInt NewCI = RHSV;
|
|
NewCI.zext(BitWidth);
|
|
Instruction *NewAnd =
|
|
BinaryOperator::CreateAnd(Cast->getOperand(0),
|
|
ConstantInt::get(NewCST),LHSI->getName());
|
|
InsertNewInstBefore(NewAnd, ICI);
|
|
return new ICmpInst(ICI.getPredicate(), NewAnd,
|
|
ConstantInt::get(NewCI));
|
|
}
|
|
}
|
|
|
|
// If this is: (X >> C1) & C2 != C3 (where any shift and any compare
|
|
// could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
|
|
// happens a LOT in code produced by the C front-end, for bitfield
|
|
// access.
|
|
BinaryOperator *Shift = dyn_cast<BinaryOperator>(LHSI->getOperand(0));
|
|
if (Shift && !Shift->isShift())
|
|
Shift = 0;
|
|
|
|
ConstantInt *ShAmt;
|
|
ShAmt = Shift ? dyn_cast<ConstantInt>(Shift->getOperand(1)) : 0;
|
|
const Type *Ty = Shift ? Shift->getType() : 0; // Type of the shift.
|
|
const Type *AndTy = AndCST->getType(); // Type of the and.
|
|
|
|
// We can fold this as long as we can't shift unknown bits
|
|
// into the mask. This can only happen with signed shift
|
|
// rights, as they sign-extend.
|
|
if (ShAmt) {
|
|
bool CanFold = Shift->isLogicalShift();
|
|
if (!CanFold) {
|
|
// To test for the bad case of the signed shr, see if any
|
|
// of the bits shifted in could be tested after the mask.
|
|
uint32_t TyBits = Ty->getPrimitiveSizeInBits();
|
|
int ShAmtVal = TyBits - ShAmt->getLimitedValue(TyBits);
|
|
|
|
uint32_t BitWidth = AndTy->getPrimitiveSizeInBits();
|
|
if ((APInt::getHighBitsSet(BitWidth, BitWidth-ShAmtVal) &
|
|
AndCST->getValue()) == 0)
|
|
CanFold = true;
|
|
}
|
|
|
|
if (CanFold) {
|
|
Constant *NewCst;
|
|
if (Shift->getOpcode() == Instruction::Shl)
|
|
NewCst = ConstantExpr::getLShr(RHS, ShAmt);
|
|
else
|
|
NewCst = ConstantExpr::getShl(RHS, ShAmt);
|
|
|
|
// Check to see if we are shifting out any of the bits being
|
|
// compared.
|
|
if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != RHS) {
|
|
// If we shifted bits out, the fold is not going to work out.
|
|
// As a special case, check to see if this means that the
|
|
// result is always true or false now.
|
|
if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
|
|
return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
|
|
if (ICI.getPredicate() == ICmpInst::ICMP_NE)
|
|
return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
|
|
} else {
|
|
ICI.setOperand(1, NewCst);
|
|
Constant *NewAndCST;
|
|
if (Shift->getOpcode() == Instruction::Shl)
|
|
NewAndCST = ConstantExpr::getLShr(AndCST, ShAmt);
|
|
else
|
|
NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
|
|
LHSI->setOperand(1, NewAndCST);
|
|
LHSI->setOperand(0, Shift->getOperand(0));
|
|
AddToWorkList(Shift); // Shift is dead.
|
|
AddUsesToWorkList(ICI);
|
|
return &ICI;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Turn ((X >> Y) & C) == 0 into (X & (C << Y)) == 0. The later is
|
|
// preferable because it allows the C<<Y expression to be hoisted out
|
|
// of a loop if Y is invariant and X is not.
|
|
if (Shift && Shift->hasOneUse() && RHSV == 0 &&
|
|
ICI.isEquality() && !Shift->isArithmeticShift() &&
|
|
isa<Instruction>(Shift->getOperand(0))) {
|
|
// Compute C << Y.
|
|
Value *NS;
|
|
if (Shift->getOpcode() == Instruction::LShr) {
|
|
NS = BinaryOperator::CreateShl(AndCST,
|
|
Shift->getOperand(1), "tmp");
|
|
} else {
|
|
// Insert a logical shift.
|
|
NS = BinaryOperator::CreateLShr(AndCST,
|
|
Shift->getOperand(1), "tmp");
|
|
}
|
|
InsertNewInstBefore(cast<Instruction>(NS), ICI);
|
|
|
|
// Compute X & (C << Y).
|
|
Instruction *NewAnd =
|
|
BinaryOperator::CreateAnd(Shift->getOperand(0), NS, LHSI->getName());
|
|
InsertNewInstBefore(NewAnd, ICI);
|
|
|
|
ICI.setOperand(0, NewAnd);
|
|
return &ICI;
|
|
}
|
|
}
|
|
break;
|
|
|
|
case Instruction::Shl: { // (icmp pred (shl X, ShAmt), CI)
|
|
ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
|
|
if (!ShAmt) break;
|
|
|
|
uint32_t TypeBits = RHSV.getBitWidth();
|
|
|
|
// Check that the shift amount is in range. If not, don't perform
|
|
// undefined shifts. When the shift is visited it will be
|
|
// simplified.
|
|
if (ShAmt->uge(TypeBits))
|
|
break;
|
|
|
|
if (ICI.isEquality()) {
|
|
// If we are comparing against bits always shifted out, the
|
|
// comparison cannot succeed.
|
|
Constant *Comp =
|
|
ConstantExpr::getShl(ConstantExpr::getLShr(RHS, ShAmt), ShAmt);
|
|
if (Comp != RHS) {// Comparing against a bit that we know is zero.
|
|
bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
|
|
Constant *Cst = ConstantInt::get(Type::Int1Ty, IsICMP_NE);
|
|
return ReplaceInstUsesWith(ICI, Cst);
|
|
}
|
|
|
|
if (LHSI->hasOneUse()) {
|
|
// Otherwise strength reduce the shift into an and.
|
|
uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
|
|
Constant *Mask =
|
|
ConstantInt::get(APInt::getLowBitsSet(TypeBits, TypeBits-ShAmtVal));
|
|
|
|
Instruction *AndI =
|
|
BinaryOperator::CreateAnd(LHSI->getOperand(0),
|
|
Mask, LHSI->getName()+".mask");
|
|
Value *And = InsertNewInstBefore(AndI, ICI);
|
|
return new ICmpInst(ICI.getPredicate(), And,
|
|
ConstantInt::get(RHSV.lshr(ShAmtVal)));
|
|
}
|
|
}
|
|
|
|
// Otherwise, if this is a comparison of the sign bit, simplify to and/test.
|
|
bool TrueIfSigned = false;
|
|
if (LHSI->hasOneUse() &&
|
|
isSignBitCheck(ICI.getPredicate(), RHS, TrueIfSigned)) {
|
|
// (X << 31) <s 0 --> (X&1) != 0
|
|
Constant *Mask = ConstantInt::get(APInt(TypeBits, 1) <<
|
|
(TypeBits-ShAmt->getZExtValue()-1));
|
|
Instruction *AndI =
|
|
BinaryOperator::CreateAnd(LHSI->getOperand(0),
|
|
Mask, LHSI->getName()+".mask");
|
|
Value *And = InsertNewInstBefore(AndI, ICI);
|
|
|
|
return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ,
|
|
And, Constant::getNullValue(And->getType()));
|
|
}
|
|
break;
|
|
}
|
|
|
|
case Instruction::LShr: // (icmp pred (shr X, ShAmt), CI)
|
|
case Instruction::AShr: {
|
|
// Only handle equality comparisons of shift-by-constant.
|
|
ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1));
|
|
if (!ShAmt || !ICI.isEquality()) break;
|
|
|
|
// Check that the shift amount is in range. If not, don't perform
|
|
// undefined shifts. When the shift is visited it will be
|
|
// simplified.
|
|
uint32_t TypeBits = RHSV.getBitWidth();
|
|
if (ShAmt->uge(TypeBits))
|
|
break;
|
|
|
|
uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits);
|
|
|
|
// If we are comparing against bits always shifted out, the
|
|
// comparison cannot succeed.
|
|
APInt Comp = RHSV << ShAmtVal;
|
|
if (LHSI->getOpcode() == Instruction::LShr)
|
|
Comp = Comp.lshr(ShAmtVal);
|
|
else
|
|
Comp = Comp.ashr(ShAmtVal);
|
|
|
|
if (Comp != RHSV) { // Comparing against a bit that we know is zero.
|
|
bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
|
|
Constant *Cst = ConstantInt::get(Type::Int1Ty, IsICMP_NE);
|
|
return ReplaceInstUsesWith(ICI, Cst);
|
|
}
|
|
|
|
// Otherwise, check to see if the bits shifted out are known to be zero.
|
|
// If so, we can compare against the unshifted value:
|
|
// (X & 4) >> 1 == 2 --> (X & 4) == 4.
|
|
if (LHSI->hasOneUse() &&
|
|
MaskedValueIsZero(LHSI->getOperand(0),
|
|
APInt::getLowBitsSet(Comp.getBitWidth(), ShAmtVal))) {
|
|
return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0),
|
|
ConstantExpr::getShl(RHS, ShAmt));
|
|
}
|
|
|
|
if (LHSI->hasOneUse()) {
|
|
// Otherwise strength reduce the shift into an and.
|
|
APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
|
|
Constant *Mask = ConstantInt::get(Val);
|
|
|
|
Instruction *AndI =
|
|
BinaryOperator::CreateAnd(LHSI->getOperand(0),
|
|
Mask, LHSI->getName()+".mask");
|
|
Value *And = InsertNewInstBefore(AndI, ICI);
|
|
return new ICmpInst(ICI.getPredicate(), And,
|
|
ConstantExpr::getShl(RHS, ShAmt));
|
|
}
|
|
break;
|
|
}
|
|
|
|
case Instruction::SDiv:
|
|
case Instruction::UDiv:
|
|
// Fold: icmp pred ([us]div X, C1), C2 -> range test
|
|
// Fold this div into the comparison, producing a range check.
|
|
// Determine, based on the divide type, what the range is being
|
|
// checked. If there is an overflow on the low or high side, remember
|
|
// it, otherwise compute the range [low, hi) bounding the new value.
|
|
// See: InsertRangeTest above for the kinds of replacements possible.
|
|
if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1)))
|
|
if (Instruction *R = FoldICmpDivCst(ICI, cast<BinaryOperator>(LHSI),
|
|
DivRHS))
|
|
return R;
|
|
break;
|
|
|
|
case Instruction::Add:
|
|
// Fold: icmp pred (add, X, C1), C2
|
|
|
|
if (!ICI.isEquality()) {
|
|
ConstantInt *LHSC = dyn_cast<ConstantInt>(LHSI->getOperand(1));
|
|
if (!LHSC) break;
|
|
const APInt &LHSV = LHSC->getValue();
|
|
|
|
ConstantRange CR = ICI.makeConstantRange(ICI.getPredicate(), RHSV)
|
|
.subtract(LHSV);
|
|
|
|
if (ICI.isSignedPredicate()) {
|
|
if (CR.getLower().isSignBit()) {
|
|
return new ICmpInst(ICmpInst::ICMP_SLT, LHSI->getOperand(0),
|
|
ConstantInt::get(CR.getUpper()));
|
|
} else if (CR.getUpper().isSignBit()) {
|
|
return new ICmpInst(ICmpInst::ICMP_SGE, LHSI->getOperand(0),
|
|
ConstantInt::get(CR.getLower()));
|
|
}
|
|
} else {
|
|
if (CR.getLower().isMinValue()) {
|
|
return new ICmpInst(ICmpInst::ICMP_ULT, LHSI->getOperand(0),
|
|
ConstantInt::get(CR.getUpper()));
|
|
} else if (CR.getUpper().isMinValue()) {
|
|
return new ICmpInst(ICmpInst::ICMP_UGE, LHSI->getOperand(0),
|
|
ConstantInt::get(CR.getLower()));
|
|
}
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
|
|
// Simplify icmp_eq and icmp_ne instructions with integer constant RHS.
|
|
if (ICI.isEquality()) {
|
|
bool isICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
|
|
|
|
// If the first operand is (add|sub|and|or|xor|rem) with a constant, and
|
|
// the second operand is a constant, simplify a bit.
|
|
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(LHSI)) {
|
|
switch (BO->getOpcode()) {
|
|
case Instruction::SRem:
|
|
// If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
|
|
if (RHSV == 0 && isa<ConstantInt>(BO->getOperand(1)) &&BO->hasOneUse()){
|
|
const APInt &V = cast<ConstantInt>(BO->getOperand(1))->getValue();
|
|
if (V.sgt(APInt(V.getBitWidth(), 1)) && V.isPowerOf2()) {
|
|
Instruction *NewRem =
|
|
BinaryOperator::CreateURem(BO->getOperand(0), BO->getOperand(1),
|
|
BO->getName());
|
|
InsertNewInstBefore(NewRem, ICI);
|
|
return new ICmpInst(ICI.getPredicate(), NewRem,
|
|
Constant::getNullValue(BO->getType()));
|
|
}
|
|
}
|
|
break;
|
|
case Instruction::Add:
|
|
// Replace ((add A, B) != C) with (A != C-B) if B & C are constants.
|
|
if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) {
|
|
if (BO->hasOneUse())
|
|
return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
|
|
Subtract(RHS, BOp1C));
|
|
} else if (RHSV == 0) {
|
|
// Replace ((add A, B) != 0) with (A != -B) if A or B is
|
|
// efficiently invertible, or if the add has just this one use.
|
|
Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
|
|
|
|
if (Value *NegVal = dyn_castNegVal(BOp1))
|
|
return new ICmpInst(ICI.getPredicate(), BOp0, NegVal);
|
|
else if (Value *NegVal = dyn_castNegVal(BOp0))
|
|
return new ICmpInst(ICI.getPredicate(), NegVal, BOp1);
|
|
else if (BO->hasOneUse()) {
|
|
Instruction *Neg = BinaryOperator::CreateNeg(BOp1);
|
|
InsertNewInstBefore(Neg, ICI);
|
|
Neg->takeName(BO);
|
|
return new ICmpInst(ICI.getPredicate(), BOp0, Neg);
|
|
}
|
|
}
|
|
break;
|
|
case Instruction::Xor:
|
|
// For the xor case, we can xor two constants together, eliminating
|
|
// the explicit xor.
|
|
if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
|
|
return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
|
|
ConstantExpr::getXor(RHS, BOC));
|
|
|
|
// FALLTHROUGH
|
|
case Instruction::Sub:
|
|
// Replace (([sub|xor] A, B) != 0) with (A != B)
|
|
if (RHSV == 0)
|
|
return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
|
|
BO->getOperand(1));
|
|
break;
|
|
|
|
case Instruction::Or:
|
|
// If bits are being or'd in that are not present in the constant we
|
|
// are comparing against, then the comparison could never succeed!
|
|
if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
|
|
Constant *NotCI = ConstantExpr::getNot(RHS);
|
|
if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
|
|
return ReplaceInstUsesWith(ICI, ConstantInt::get(Type::Int1Ty,
|
|
isICMP_NE));
|
|
}
|
|
break;
|
|
|
|
case Instruction::And:
|
|
if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) {
|
|
// If bits are being compared against that are and'd out, then the
|
|
// comparison can never succeed!
|
|
if ((RHSV & ~BOC->getValue()) != 0)
|
|
return ReplaceInstUsesWith(ICI, ConstantInt::get(Type::Int1Ty,
|
|
isICMP_NE));
|
|
|
|
// If we have ((X & C) == C), turn it into ((X & C) != 0).
|
|
if (RHS == BOC && RHSV.isPowerOf2())
|
|
return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ :
|
|
ICmpInst::ICMP_NE, LHSI,
|
|
Constant::getNullValue(RHS->getType()));
|
|
|
|
// Replace (and X, (1 << size(X)-1) != 0) with x s< 0
|
|
if (BOC->getValue().isSignBit()) {
|
|
Value *X = BO->getOperand(0);
|
|
Constant *Zero = Constant::getNullValue(X->getType());
|
|
ICmpInst::Predicate pred = isICMP_NE ?
|
|
ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
|
|
return new ICmpInst(pred, X, Zero);
|
|
}
|
|
|
|
// ((X & ~7) == 0) --> X < 8
|
|
if (RHSV == 0 && isHighOnes(BOC)) {
|
|
Value *X = BO->getOperand(0);
|
|
Constant *NegX = ConstantExpr::getNeg(BOC);
|
|
ICmpInst::Predicate pred = isICMP_NE ?
|
|
ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
|
|
return new ICmpInst(pred, X, NegX);
|
|
}
|
|
}
|
|
default: break;
|
|
}
|
|
} else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(LHSI)) {
|
|
// Handle icmp {eq|ne} <intrinsic>, intcst.
|
|
if (II->getIntrinsicID() == Intrinsic::bswap) {
|
|
AddToWorkList(II);
|
|
ICI.setOperand(0, II->getOperand(1));
|
|
ICI.setOperand(1, ConstantInt::get(RHSV.byteSwap()));
|
|
return &ICI;
|
|
}
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/// visitICmpInstWithCastAndCast - Handle icmp (cast x to y), (cast/cst).
|
|
/// We only handle extending casts so far.
|
|
///
|
|
Instruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) {
|
|
const CastInst *LHSCI = cast<CastInst>(ICI.getOperand(0));
|
|
Value *LHSCIOp = LHSCI->getOperand(0);
|
|
const Type *SrcTy = LHSCIOp->getType();
|
|
const Type *DestTy = LHSCI->getType();
|
|
Value *RHSCIOp;
|
|
|
|
// Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the
|
|
// integer type is the same size as the pointer type.
|
|
if (LHSCI->getOpcode() == Instruction::PtrToInt &&
|
|
getTargetData().getPointerSizeInBits() ==
|
|
cast<IntegerType>(DestTy)->getBitWidth()) {
|
|
Value *RHSOp = 0;
|
|
if (Constant *RHSC = dyn_cast<Constant>(ICI.getOperand(1))) {
|
|
RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy);
|
|
} else if (PtrToIntInst *RHSC = dyn_cast<PtrToIntInst>(ICI.getOperand(1))) {
|
|
RHSOp = RHSC->getOperand(0);
|
|
// If the pointer types don't match, insert a bitcast.
|
|
if (LHSCIOp->getType() != RHSOp->getType())
|
|
RHSOp = InsertBitCastBefore(RHSOp, LHSCIOp->getType(), ICI);
|
|
}
|
|
|
|
if (RHSOp)
|
|
return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSOp);
|
|
}
|
|
|
|
// The code below only handles extension cast instructions, so far.
|
|
// Enforce this.
|
|
if (LHSCI->getOpcode() != Instruction::ZExt &&
|
|
LHSCI->getOpcode() != Instruction::SExt)
|
|
return 0;
|
|
|
|
bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt;
|
|
bool isSignedCmp = ICI.isSignedPredicate();
|
|
|
|
if (CastInst *CI = dyn_cast<CastInst>(ICI.getOperand(1))) {
|
|
// Not an extension from the same type?
|
|
RHSCIOp = CI->getOperand(0);
|
|
if (RHSCIOp->getType() != LHSCIOp->getType())
|
|
return 0;
|
|
|
|
// If the signedness of the two casts doesn't agree (i.e. one is a sext
|
|
// and the other is a zext), then we can't handle this.
|
|
if (CI->getOpcode() != LHSCI->getOpcode())
|
|
return 0;
|
|
|
|
// Deal with equality cases early.
|
|
if (ICI.isEquality())
|
|
return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
|
|
|
|
// A signed comparison of sign extended values simplifies into a
|
|
// signed comparison.
|
|
if (isSignedCmp && isSignedExt)
|
|
return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp);
|
|
|
|
// The other three cases all fold into an unsigned comparison.
|
|
return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, RHSCIOp);
|
|
}
|
|
|
|
// If we aren't dealing with a constant on the RHS, exit early
|
|
ConstantInt *CI = dyn_cast<ConstantInt>(ICI.getOperand(1));
|
|
if (!CI)
|
|
return 0;
|
|
|
|
// Compute the constant that would happen if we truncated to SrcTy then
|
|
// reextended to DestTy.
|
|
Constant *Res1 = ConstantExpr::getTrunc(CI, SrcTy);
|
|
Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(), Res1, DestTy);
|
|
|
|
// If the re-extended constant didn't change...
|
|
if (Res2 == CI) {
|
|
// Make sure that sign of the Cmp and the sign of the Cast are the same.
|
|
// For example, we might have:
|
|
// %A = sext short %X to uint
|
|
// %B = icmp ugt uint %A, 1330
|
|
// It is incorrect to transform this into
|
|
// %B = icmp ugt short %X, 1330
|
|
// because %A may have negative value.
|
|
//
|
|
// However, we allow this when the compare is EQ/NE, because they are
|
|
// signless.
|
|
if (isSignedExt == isSignedCmp || ICI.isEquality())
|
|
return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1);
|
|
return 0;
|
|
}
|
|
|
|
// The re-extended constant changed so the constant cannot be represented
|
|
// in the shorter type. Consequently, we cannot emit a simple comparison.
|
|
|
|
// First, handle some easy cases. We know the result cannot be equal at this
|
|
// point so handle the ICI.isEquality() cases
|
|
if (ICI.getPredicate() == ICmpInst::ICMP_EQ)
|
|
return ReplaceInstUsesWith(ICI, ConstantInt::getFalse());
|
|
if (ICI.getPredicate() == ICmpInst::ICMP_NE)
|
|
return ReplaceInstUsesWith(ICI, ConstantInt::getTrue());
|
|
|
|
// Evaluate the comparison for LT (we invert for GT below). LE and GE cases
|
|
// should have been folded away previously and not enter in here.
|
|
Value *Result;
|
|
if (isSignedCmp) {
|
|
// We're performing a signed comparison.
|
|
if (cast<ConstantInt>(CI)->getValue().isNegative())
|
|
Result = ConstantInt::getFalse(); // X < (small) --> false
|
|
else
|
|
Result = ConstantInt::getTrue(); // X < (large) --> true
|
|
} else {
|
|
// We're performing an unsigned comparison.
|
|
if (isSignedExt) {
|
|
// We're performing an unsigned comp with a sign extended value.
|
|
// This is true if the input is >= 0. [aka >s -1]
|
|
Constant *NegOne = ConstantInt::getAllOnesValue(SrcTy);
|
|
Result = InsertNewInstBefore(new ICmpInst(ICmpInst::ICMP_SGT, LHSCIOp,
|
|
NegOne, ICI.getName()), ICI);
|
|
} else {
|
|
// Unsigned extend & unsigned compare -> always true.
|
|
Result = ConstantInt::getTrue();
|
|
}
|
|
}
|
|
|
|
// Finally, return the value computed.
|
|
if (ICI.getPredicate() == ICmpInst::ICMP_ULT ||
|
|
ICI.getPredicate() == ICmpInst::ICMP_SLT)
|
|
return ReplaceInstUsesWith(ICI, Result);
|
|
|
|
assert((ICI.getPredicate()==ICmpInst::ICMP_UGT ||
|
|
ICI.getPredicate()==ICmpInst::ICMP_SGT) &&
|
|
"ICmp should be folded!");
|
|
if (Constant *CI = dyn_cast<Constant>(Result))
|
|
return ReplaceInstUsesWith(ICI, ConstantExpr::getNot(CI));
|
|
return BinaryOperator::CreateNot(Result);
|
|
}
|
|
|
|
Instruction *InstCombiner::visitShl(BinaryOperator &I) {
|
|
return commonShiftTransforms(I);
|
|
}
|
|
|
|
Instruction *InstCombiner::visitLShr(BinaryOperator &I) {
|
|
return commonShiftTransforms(I);
|
|
}
|
|
|
|
Instruction *InstCombiner::visitAShr(BinaryOperator &I) {
|
|
if (Instruction *R = commonShiftTransforms(I))
|
|
return R;
|
|
|
|
Value *Op0 = I.getOperand(0);
|
|
|
|
// ashr int -1, X = -1 (for any arithmetic shift rights of ~0)
|
|
if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0))
|
|
if (CSI->isAllOnesValue())
|
|
return ReplaceInstUsesWith(I, CSI);
|
|
|
|
// See if we can turn a signed shr into an unsigned shr.
|
|
if (!isa<VectorType>(I.getType()) &&
|
|
MaskedValueIsZero(Op0,
|
|
APInt::getSignBit(I.getType()->getPrimitiveSizeInBits())))
|
|
return BinaryOperator::CreateLShr(Op0, I.getOperand(1));
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::commonShiftTransforms(BinaryOperator &I) {
|
|
assert(I.getOperand(1)->getType() == I.getOperand(0)->getType());
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
// shl X, 0 == X and shr X, 0 == X
|
|
// shl 0, X == 0 and shr 0, X == 0
|
|
if (Op1 == Constant::getNullValue(Op1->getType()) ||
|
|
Op0 == Constant::getNullValue(Op0->getType()))
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
|
|
if (isa<UndefValue>(Op0)) {
|
|
if (I.getOpcode() == Instruction::AShr) // undef >>s X -> undef
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
else // undef << X -> 0, undef >>u X -> 0
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
}
|
|
if (isa<UndefValue>(Op1)) {
|
|
if (I.getOpcode() == Instruction::AShr) // X >>s undef -> X
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
else // X << undef, X >>u undef -> 0
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
}
|
|
|
|
// Try to fold constant and into select arguments.
|
|
if (isa<Constant>(Op0))
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
|
|
if (Instruction *R = FoldOpIntoSelect(I, SI, this))
|
|
return R;
|
|
|
|
if (ConstantInt *CUI = dyn_cast<ConstantInt>(Op1))
|
|
if (Instruction *Res = FoldShiftByConstant(Op0, CUI, I))
|
|
return Res;
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1,
|
|
BinaryOperator &I) {
|
|
bool isLeftShift = I.getOpcode() == Instruction::Shl;
|
|
|
|
// See if we can simplify any instructions used by the instruction whose sole
|
|
// purpose is to compute bits we don't care about.
|
|
uint32_t TypeBits = Op0->getType()->getPrimitiveSizeInBits();
|
|
if (SimplifyDemandedInstructionBits(I))
|
|
return &I;
|
|
|
|
// shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
|
|
// of a signed value.
|
|
//
|
|
if (Op1->uge(TypeBits)) {
|
|
if (I.getOpcode() != Instruction::AShr)
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
|
|
else {
|
|
I.setOperand(1, ConstantInt::get(I.getType(), TypeBits-1));
|
|
return &I;
|
|
}
|
|
}
|
|
|
|
// ((X*C1) << C2) == (X * (C1 << C2))
|
|
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0))
|
|
if (BO->getOpcode() == Instruction::Mul && isLeftShift)
|
|
if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1)))
|
|
return BinaryOperator::CreateMul(BO->getOperand(0),
|
|
ConstantExpr::getShl(BOOp, Op1));
|
|
|
|
// Try to fold constant and into select arguments.
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
|
|
if (Instruction *R = FoldOpIntoSelect(I, SI, this))
|
|
return R;
|
|
if (isa<PHINode>(Op0))
|
|
if (Instruction *NV = FoldOpIntoPhi(I))
|
|
return NV;
|
|
|
|
// Fold shift2(trunc(shift1(x,c1)), c2) -> trunc(shift2(shift1(x,c1),c2))
|
|
if (TruncInst *TI = dyn_cast<TruncInst>(Op0)) {
|
|
Instruction *TrOp = dyn_cast<Instruction>(TI->getOperand(0));
|
|
// If 'shift2' is an ashr, we would have to get the sign bit into a funny
|
|
// place. Don't try to do this transformation in this case. Also, we
|
|
// require that the input operand is a shift-by-constant so that we have
|
|
// confidence that the shifts will get folded together. We could do this
|
|
// xform in more cases, but it is unlikely to be profitable.
|
|
if (TrOp && I.isLogicalShift() && TrOp->isShift() &&
|
|
isa<ConstantInt>(TrOp->getOperand(1))) {
|
|
// Okay, we'll do this xform. Make the shift of shift.
|
|
Constant *ShAmt = ConstantExpr::getZExt(Op1, TrOp->getType());
|
|
Instruction *NSh = BinaryOperator::Create(I.getOpcode(), TrOp, ShAmt,
|
|
I.getName());
|
|
InsertNewInstBefore(NSh, I); // (shift2 (shift1 & 0x00FF), c2)
|
|
|
|
// For logical shifts, the truncation has the effect of making the high
|
|
// part of the register be zeros. Emulate this by inserting an AND to
|
|
// clear the top bits as needed. This 'and' will usually be zapped by
|
|
// other xforms later if dead.
|
|
unsigned SrcSize = TrOp->getType()->getPrimitiveSizeInBits();
|
|
unsigned DstSize = TI->getType()->getPrimitiveSizeInBits();
|
|
APInt MaskV(APInt::getLowBitsSet(SrcSize, DstSize));
|
|
|
|
// The mask we constructed says what the trunc would do if occurring
|
|
// between the shifts. We want to know the effect *after* the second
|
|
// shift. We know that it is a logical shift by a constant, so adjust the
|
|
// mask as appropriate.
|
|
if (I.getOpcode() == Instruction::Shl)
|
|
MaskV <<= Op1->getZExtValue();
|
|
else {
|
|
assert(I.getOpcode() == Instruction::LShr && "Unknown logical shift");
|
|
MaskV = MaskV.lshr(Op1->getZExtValue());
|
|
}
|
|
|
|
Instruction *And = BinaryOperator::CreateAnd(NSh, ConstantInt::get(MaskV),
|
|
TI->getName());
|
|
InsertNewInstBefore(And, I); // shift1 & 0x00FF
|
|
|
|
// Return the value truncated to the interesting size.
|
|
return new TruncInst(And, I.getType());
|
|
}
|
|
}
|
|
|
|
if (Op0->hasOneUse()) {
|
|
if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
|
|
// Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
|
|
Value *V1, *V2;
|
|
ConstantInt *CC;
|
|
switch (Op0BO->getOpcode()) {
|
|
default: break;
|
|
case Instruction::Add:
|
|
case Instruction::And:
|
|
case Instruction::Or:
|
|
case Instruction::Xor: {
|
|
// These operators commute.
|
|
// Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C)
|
|
if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
|
|
match(Op0BO->getOperand(1), m_Shr(m_Value(V1), m_Specific(Op1)))){
|
|
Instruction *YS = BinaryOperator::CreateShl(
|
|
Op0BO->getOperand(0), Op1,
|
|
Op0BO->getName());
|
|
InsertNewInstBefore(YS, I); // (Y << C)
|
|
Instruction *X =
|
|
BinaryOperator::Create(Op0BO->getOpcode(), YS, V1,
|
|
Op0BO->getOperand(1)->getName());
|
|
InsertNewInstBefore(X, I); // (X + (Y << C))
|
|
uint32_t Op1Val = Op1->getLimitedValue(TypeBits);
|
|
return BinaryOperator::CreateAnd(X, ConstantInt::get(
|
|
APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
|
|
}
|
|
|
|
// Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
|
|
Value *Op0BOOp1 = Op0BO->getOperand(1);
|
|
if (isLeftShift && Op0BOOp1->hasOneUse() &&
|
|
match(Op0BOOp1,
|
|
m_And(m_Shr(m_Value(V1), m_Specific(Op1)),
|
|
m_ConstantInt(CC))) &&
|
|
cast<BinaryOperator>(Op0BOOp1)->getOperand(0)->hasOneUse()) {
|
|
Instruction *YS = BinaryOperator::CreateShl(
|
|
Op0BO->getOperand(0), Op1,
|
|
Op0BO->getName());
|
|
InsertNewInstBefore(YS, I); // (Y << C)
|
|
Instruction *XM =
|
|
BinaryOperator::CreateAnd(V1, ConstantExpr::getShl(CC, Op1),
|
|
V1->getName()+".mask");
|
|
InsertNewInstBefore(XM, I); // X & (CC << C)
|
|
|
|
return BinaryOperator::Create(Op0BO->getOpcode(), YS, XM);
|
|
}
|
|
}
|
|
|
|
// FALL THROUGH.
|
|
case Instruction::Sub: {
|
|
// Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
|
|
if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
|
|
match(Op0BO->getOperand(0), m_Shr(m_Value(V1), m_Specific(Op1)))){
|
|
Instruction *YS = BinaryOperator::CreateShl(
|
|
Op0BO->getOperand(1), Op1,
|
|
Op0BO->getName());
|
|
InsertNewInstBefore(YS, I); // (Y << C)
|
|
Instruction *X =
|
|
BinaryOperator::Create(Op0BO->getOpcode(), V1, YS,
|
|
Op0BO->getOperand(0)->getName());
|
|
InsertNewInstBefore(X, I); // (X + (Y << C))
|
|
uint32_t Op1Val = Op1->getLimitedValue(TypeBits);
|
|
return BinaryOperator::CreateAnd(X, ConstantInt::get(
|
|
APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val)));
|
|
}
|
|
|
|
// Turn (((X >> C)&CC) + Y) << C -> (X + (Y << C)) & (CC << C)
|
|
if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
|
|
match(Op0BO->getOperand(0),
|
|
m_And(m_Shr(m_Value(V1), m_Value(V2)),
|
|
m_ConstantInt(CC))) && V2 == Op1 &&
|
|
cast<BinaryOperator>(Op0BO->getOperand(0))
|
|
->getOperand(0)->hasOneUse()) {
|
|
Instruction *YS = BinaryOperator::CreateShl(
|
|
Op0BO->getOperand(1), Op1,
|
|
Op0BO->getName());
|
|
InsertNewInstBefore(YS, I); // (Y << C)
|
|
Instruction *XM =
|
|
BinaryOperator::CreateAnd(V1, ConstantExpr::getShl(CC, Op1),
|
|
V1->getName()+".mask");
|
|
InsertNewInstBefore(XM, I); // X & (CC << C)
|
|
|
|
return BinaryOperator::Create(Op0BO->getOpcode(), XM, YS);
|
|
}
|
|
|
|
break;
|
|
}
|
|
}
|
|
|
|
|
|
// If the operand is an bitwise operator with a constant RHS, and the
|
|
// shift is the only use, we can pull it out of the shift.
|
|
if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
|
|
bool isValid = true; // Valid only for And, Or, Xor
|
|
bool highBitSet = false; // Transform if high bit of constant set?
|
|
|
|
switch (Op0BO->getOpcode()) {
|
|
default: isValid = false; break; // Do not perform transform!
|
|
case Instruction::Add:
|
|
isValid = isLeftShift;
|
|
break;
|
|
case Instruction::Or:
|
|
case Instruction::Xor:
|
|
highBitSet = false;
|
|
break;
|
|
case Instruction::And:
|
|
highBitSet = true;
|
|
break;
|
|
}
|
|
|
|
// If this is a signed shift right, and the high bit is modified
|
|
// by the logical operation, do not perform the transformation.
|
|
// The highBitSet boolean indicates the value of the high bit of
|
|
// the constant which would cause it to be modified for this
|
|
// operation.
|
|
//
|
|
if (isValid && I.getOpcode() == Instruction::AShr)
|
|
isValid = Op0C->getValue()[TypeBits-1] == highBitSet;
|
|
|
|
if (isValid) {
|
|
Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, Op1);
|
|
|
|
Instruction *NewShift =
|
|
BinaryOperator::Create(I.getOpcode(), Op0BO->getOperand(0), Op1);
|
|
InsertNewInstBefore(NewShift, I);
|
|
NewShift->takeName(Op0BO);
|
|
|
|
return BinaryOperator::Create(Op0BO->getOpcode(), NewShift,
|
|
NewRHS);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Find out if this is a shift of a shift by a constant.
|
|
BinaryOperator *ShiftOp = dyn_cast<BinaryOperator>(Op0);
|
|
if (ShiftOp && !ShiftOp->isShift())
|
|
ShiftOp = 0;
|
|
|
|
if (ShiftOp && isa<ConstantInt>(ShiftOp->getOperand(1))) {
|
|
ConstantInt *ShiftAmt1C = cast<ConstantInt>(ShiftOp->getOperand(1));
|
|
uint32_t ShiftAmt1 = ShiftAmt1C->getLimitedValue(TypeBits);
|
|
uint32_t ShiftAmt2 = Op1->getLimitedValue(TypeBits);
|
|
assert(ShiftAmt2 != 0 && "Should have been simplified earlier");
|
|
if (ShiftAmt1 == 0) return 0; // Will be simplified in the future.
|
|
Value *X = ShiftOp->getOperand(0);
|
|
|
|
uint32_t AmtSum = ShiftAmt1+ShiftAmt2; // Fold into one big shift.
|
|
if (AmtSum > TypeBits)
|
|
AmtSum = TypeBits;
|
|
|
|
const IntegerType *Ty = cast<IntegerType>(I.getType());
|
|
|
|
// Check for (X << c1) << c2 and (X >> c1) >> c2
|
|
if (I.getOpcode() == ShiftOp->getOpcode()) {
|
|
return BinaryOperator::Create(I.getOpcode(), X,
|
|
ConstantInt::get(Ty, AmtSum));
|
|
} else if (ShiftOp->getOpcode() == Instruction::LShr &&
|
|
I.getOpcode() == Instruction::AShr) {
|
|
// ((X >>u C1) >>s C2) -> (X >>u (C1+C2)) since C1 != 0.
|
|
return BinaryOperator::CreateLShr(X, ConstantInt::get(Ty, AmtSum));
|
|
} else if (ShiftOp->getOpcode() == Instruction::AShr &&
|
|
I.getOpcode() == Instruction::LShr) {
|
|
// ((X >>s C1) >>u C2) -> ((X >>s (C1+C2)) & mask) since C1 != 0.
|
|
Instruction *Shift =
|
|
BinaryOperator::CreateAShr(X, ConstantInt::get(Ty, AmtSum));
|
|
InsertNewInstBefore(Shift, I);
|
|
|
|
APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
|
|
return BinaryOperator::CreateAnd(Shift, ConstantInt::get(Mask));
|
|
}
|
|
|
|
// Okay, if we get here, one shift must be left, and the other shift must be
|
|
// right. See if the amounts are equal.
|
|
if (ShiftAmt1 == ShiftAmt2) {
|
|
// If we have ((X >>? C) << C), turn this into X & (-1 << C).
|
|
if (I.getOpcode() == Instruction::Shl) {
|
|
APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt1));
|
|
return BinaryOperator::CreateAnd(X, ConstantInt::get(Mask));
|
|
}
|
|
// If we have ((X << C) >>u C), turn this into X & (-1 >>u C).
|
|
if (I.getOpcode() == Instruction::LShr) {
|
|
APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt1));
|
|
return BinaryOperator::CreateAnd(X, ConstantInt::get(Mask));
|
|
}
|
|
// We can simplify ((X << C) >>s C) into a trunc + sext.
|
|
// NOTE: we could do this for any C, but that would make 'unusual' integer
|
|
// types. For now, just stick to ones well-supported by the code
|
|
// generators.
|
|
const Type *SExtType = 0;
|
|
switch (Ty->getBitWidth() - ShiftAmt1) {
|
|
case 1 :
|
|
case 8 :
|
|
case 16 :
|
|
case 32 :
|
|
case 64 :
|
|
case 128:
|
|
SExtType = IntegerType::get(Ty->getBitWidth() - ShiftAmt1);
|
|
break;
|
|
default: break;
|
|
}
|
|
if (SExtType) {
|
|
Instruction *NewTrunc = new TruncInst(X, SExtType, "sext");
|
|
InsertNewInstBefore(NewTrunc, I);
|
|
return new SExtInst(NewTrunc, Ty);
|
|
}
|
|
// Otherwise, we can't handle it yet.
|
|
} else if (ShiftAmt1 < ShiftAmt2) {
|
|
uint32_t ShiftDiff = ShiftAmt2-ShiftAmt1;
|
|
|
|
// (X >>? C1) << C2 --> X << (C2-C1) & (-1 << C2)
|
|
if (I.getOpcode() == Instruction::Shl) {
|
|
assert(ShiftOp->getOpcode() == Instruction::LShr ||
|
|
ShiftOp->getOpcode() == Instruction::AShr);
|
|
Instruction *Shift =
|
|
BinaryOperator::CreateShl(X, ConstantInt::get(Ty, ShiftDiff));
|
|
InsertNewInstBefore(Shift, I);
|
|
|
|
APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt2));
|
|
return BinaryOperator::CreateAnd(Shift, ConstantInt::get(Mask));
|
|
}
|
|
|
|
// (X << C1) >>u C2 --> X >>u (C2-C1) & (-1 >> C2)
|
|
if (I.getOpcode() == Instruction::LShr) {
|
|
assert(ShiftOp->getOpcode() == Instruction::Shl);
|
|
Instruction *Shift =
|
|
BinaryOperator::CreateLShr(X, ConstantInt::get(Ty, ShiftDiff));
|
|
InsertNewInstBefore(Shift, I);
|
|
|
|
APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
|
|
return BinaryOperator::CreateAnd(Shift, ConstantInt::get(Mask));
|
|
}
|
|
|
|
// We can't handle (X << C1) >>s C2, it shifts arbitrary bits in.
|
|
} else {
|
|
assert(ShiftAmt2 < ShiftAmt1);
|
|
uint32_t ShiftDiff = ShiftAmt1-ShiftAmt2;
|
|
|
|
// (X >>? C1) << C2 --> X >>? (C1-C2) & (-1 << C2)
|
|
if (I.getOpcode() == Instruction::Shl) {
|
|
assert(ShiftOp->getOpcode() == Instruction::LShr ||
|
|
ShiftOp->getOpcode() == Instruction::AShr);
|
|
Instruction *Shift =
|
|
BinaryOperator::Create(ShiftOp->getOpcode(), X,
|
|
ConstantInt::get(Ty, ShiftDiff));
|
|
InsertNewInstBefore(Shift, I);
|
|
|
|
APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt2));
|
|
return BinaryOperator::CreateAnd(Shift, ConstantInt::get(Mask));
|
|
}
|
|
|
|
// (X << C1) >>u C2 --> X << (C1-C2) & (-1 >> C2)
|
|
if (I.getOpcode() == Instruction::LShr) {
|
|
assert(ShiftOp->getOpcode() == Instruction::Shl);
|
|
Instruction *Shift =
|
|
BinaryOperator::CreateShl(X, ConstantInt::get(Ty, ShiftDiff));
|
|
InsertNewInstBefore(Shift, I);
|
|
|
|
APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2));
|
|
return BinaryOperator::CreateAnd(Shift, ConstantInt::get(Mask));
|
|
}
|
|
|
|
// We can't handle (X << C1) >>a C2, it shifts arbitrary bits in.
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
|
|
/// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear
|
|
/// expression. If so, decompose it, returning some value X, such that Val is
|
|
/// X*Scale+Offset.
|
|
///
|
|
static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale,
|
|
int &Offset) {
|
|
assert(Val->getType() == Type::Int32Ty && "Unexpected allocation size type!");
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) {
|
|
Offset = CI->getZExtValue();
|
|
Scale = 0;
|
|
return ConstantInt::get(Type::Int32Ty, 0);
|
|
} else if (BinaryOperator *I = dyn_cast<BinaryOperator>(Val)) {
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
|
|
if (I->getOpcode() == Instruction::Shl) {
|
|
// This is a value scaled by '1 << the shift amt'.
|
|
Scale = 1U << RHS->getZExtValue();
|
|
Offset = 0;
|
|
return I->getOperand(0);
|
|
} else if (I->getOpcode() == Instruction::Mul) {
|
|
// This value is scaled by 'RHS'.
|
|
Scale = RHS->getZExtValue();
|
|
Offset = 0;
|
|
return I->getOperand(0);
|
|
} else if (I->getOpcode() == Instruction::Add) {
|
|
// We have X+C. Check to see if we really have (X*C2)+C1,
|
|
// where C1 is divisible by C2.
|
|
unsigned SubScale;
|
|
Value *SubVal =
|
|
DecomposeSimpleLinearExpr(I->getOperand(0), SubScale, Offset);
|
|
Offset += RHS->getZExtValue();
|
|
Scale = SubScale;
|
|
return SubVal;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Otherwise, we can't look past this.
|
|
Scale = 1;
|
|
Offset = 0;
|
|
return Val;
|
|
}
|
|
|
|
|
|
/// PromoteCastOfAllocation - If we find a cast of an allocation instruction,
|
|
/// try to eliminate the cast by moving the type information into the alloc.
|
|
Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI,
|
|
AllocationInst &AI) {
|
|
const PointerType *PTy = cast<PointerType>(CI.getType());
|
|
|
|
// Remove any uses of AI that are dead.
|
|
assert(!CI.use_empty() && "Dead instructions should be removed earlier!");
|
|
|
|
for (Value::use_iterator UI = AI.use_begin(), E = AI.use_end(); UI != E; ) {
|
|
Instruction *User = cast<Instruction>(*UI++);
|
|
if (isInstructionTriviallyDead(User)) {
|
|
while (UI != E && *UI == User)
|
|
++UI; // If this instruction uses AI more than once, don't break UI.
|
|
|
|
++NumDeadInst;
|
|
DOUT << "IC: DCE: " << *User;
|
|
EraseInstFromFunction(*User);
|
|
}
|
|
}
|
|
|
|
// Get the type really allocated and the type casted to.
|
|
const Type *AllocElTy = AI.getAllocatedType();
|
|
const Type *CastElTy = PTy->getElementType();
|
|
if (!AllocElTy->isSized() || !CastElTy->isSized()) return 0;
|
|
|
|
unsigned AllocElTyAlign = TD->getABITypeAlignment(AllocElTy);
|
|
unsigned CastElTyAlign = TD->getABITypeAlignment(CastElTy);
|
|
if (CastElTyAlign < AllocElTyAlign) return 0;
|
|
|
|
// If the allocation has multiple uses, only promote it if we are strictly
|
|
// increasing the alignment of the resultant allocation. If we keep it the
|
|
// same, we open the door to infinite loops of various kinds.
|
|
if (!AI.hasOneUse() && CastElTyAlign == AllocElTyAlign) return 0;
|
|
|
|
uint64_t AllocElTySize = TD->getTypePaddedSize(AllocElTy);
|
|
uint64_t CastElTySize = TD->getTypePaddedSize(CastElTy);
|
|
if (CastElTySize == 0 || AllocElTySize == 0) return 0;
|
|
|
|
// See if we can satisfy the modulus by pulling a scale out of the array
|
|
// size argument.
|
|
unsigned ArraySizeScale;
|
|
int ArrayOffset;
|
|
Value *NumElements = // See if the array size is a decomposable linear expr.
|
|
DecomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset);
|
|
|
|
// If we can now satisfy the modulus, by using a non-1 scale, we really can
|
|
// do the xform.
|
|
if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 ||
|
|
(AllocElTySize*ArrayOffset ) % CastElTySize != 0) return 0;
|
|
|
|
unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize;
|
|
Value *Amt = 0;
|
|
if (Scale == 1) {
|
|
Amt = NumElements;
|
|
} else {
|
|
// If the allocation size is constant, form a constant mul expression
|
|
Amt = ConstantInt::get(Type::Int32Ty, Scale);
|
|
if (isa<ConstantInt>(NumElements))
|
|
Amt = Multiply(cast<ConstantInt>(NumElements), cast<ConstantInt>(Amt));
|
|
// otherwise multiply the amount and the number of elements
|
|
else if (Scale != 1) {
|
|
Instruction *Tmp = BinaryOperator::CreateMul(Amt, NumElements, "tmp");
|
|
Amt = InsertNewInstBefore(Tmp, AI);
|
|
}
|
|
}
|
|
|
|
if (int Offset = (AllocElTySize*ArrayOffset)/CastElTySize) {
|
|
Value *Off = ConstantInt::get(Type::Int32Ty, Offset, true);
|
|
Instruction *Tmp = BinaryOperator::CreateAdd(Amt, Off, "tmp");
|
|
Amt = InsertNewInstBefore(Tmp, AI);
|
|
}
|
|
|
|
AllocationInst *New;
|
|
if (isa<MallocInst>(AI))
|
|
New = new MallocInst(CastElTy, Amt, AI.getAlignment());
|
|
else
|
|
New = new AllocaInst(CastElTy, Amt, AI.getAlignment());
|
|
InsertNewInstBefore(New, AI);
|
|
New->takeName(&AI);
|
|
|
|
// If the allocation has multiple uses, insert a cast and change all things
|
|
// that used it to use the new cast. This will also hack on CI, but it will
|
|
// die soon.
|
|
if (!AI.hasOneUse()) {
|
|
AddUsesToWorkList(AI);
|
|
// New is the allocation instruction, pointer typed. AI is the original
|
|
// allocation instruction, also pointer typed. Thus, cast to use is BitCast.
|
|
CastInst *NewCast = new BitCastInst(New, AI.getType(), "tmpcast");
|
|
InsertNewInstBefore(NewCast, AI);
|
|
AI.replaceAllUsesWith(NewCast);
|
|
}
|
|
return ReplaceInstUsesWith(CI, New);
|
|
}
|
|
|
|
/// CanEvaluateInDifferentType - Return true if we can take the specified value
|
|
/// and return it as type Ty without inserting any new casts and without
|
|
/// changing the computed value. This is used by code that tries to decide
|
|
/// whether promoting or shrinking integer operations to wider or smaller types
|
|
/// will allow us to eliminate a truncate or extend.
|
|
///
|
|
/// This is a truncation operation if Ty is smaller than V->getType(), or an
|
|
/// extension operation if Ty is larger.
|
|
///
|
|
/// If CastOpc is a truncation, then Ty will be a type smaller than V. We
|
|
/// should return true if trunc(V) can be computed by computing V in the smaller
|
|
/// type. If V is an instruction, then trunc(inst(x,y)) can be computed as
|
|
/// inst(trunc(x),trunc(y)), which only makes sense if x and y can be
|
|
/// efficiently truncated.
|
|
///
|
|
/// If CastOpc is a sext or zext, we are asking if the low bits of the value can
|
|
/// bit computed in a larger type, which is then and'd or sext_in_reg'd to get
|
|
/// the final result.
|
|
bool InstCombiner::CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
|
|
unsigned CastOpc,
|
|
int &NumCastsRemoved){
|
|
// We can always evaluate constants in another type.
|
|
if (isa<ConstantInt>(V))
|
|
return true;
|
|
|
|
Instruction *I = dyn_cast<Instruction>(V);
|
|
if (!I) return false;
|
|
|
|
const IntegerType *OrigTy = cast<IntegerType>(V->getType());
|
|
|
|
// If this is an extension or truncate, we can often eliminate it.
|
|
if (isa<TruncInst>(I) || isa<ZExtInst>(I) || isa<SExtInst>(I)) {
|
|
// If this is a cast from the destination type, we can trivially eliminate
|
|
// it, and this will remove a cast overall.
|
|
if (I->getOperand(0)->getType() == Ty) {
|
|
// If the first operand is itself a cast, and is eliminable, do not count
|
|
// this as an eliminable cast. We would prefer to eliminate those two
|
|
// casts first.
|
|
if (!isa<CastInst>(I->getOperand(0)) && I->hasOneUse())
|
|
++NumCastsRemoved;
|
|
return true;
|
|
}
|
|
}
|
|
|
|
// We can't extend or shrink something that has multiple uses: doing so would
|
|
// require duplicating the instruction in general, which isn't profitable.
|
|
if (!I->hasOneUse()) return false;
|
|
|
|
unsigned Opc = I->getOpcode();
|
|
switch (Opc) {
|
|
case Instruction::Add:
|
|
case Instruction::Sub:
|
|
case Instruction::Mul:
|
|
case Instruction::And:
|
|
case Instruction::Or:
|
|
case Instruction::Xor:
|
|
// These operators can all arbitrarily be extended or truncated.
|
|
return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
|
|
NumCastsRemoved) &&
|
|
CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
|
|
NumCastsRemoved);
|
|
|
|
case Instruction::Shl:
|
|
// If we are truncating the result of this SHL, and if it's a shift of a
|
|
// constant amount, we can always perform a SHL in a smaller type.
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
|
|
uint32_t BitWidth = Ty->getBitWidth();
|
|
if (BitWidth < OrigTy->getBitWidth() &&
|
|
CI->getLimitedValue(BitWidth) < BitWidth)
|
|
return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
|
|
NumCastsRemoved);
|
|
}
|
|
break;
|
|
case Instruction::LShr:
|
|
// If this is a truncate of a logical shr, we can truncate it to a smaller
|
|
// lshr iff we know that the bits we would otherwise be shifting in are
|
|
// already zeros.
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
|
|
uint32_t OrigBitWidth = OrigTy->getBitWidth();
|
|
uint32_t BitWidth = Ty->getBitWidth();
|
|
if (BitWidth < OrigBitWidth &&
|
|
MaskedValueIsZero(I->getOperand(0),
|
|
APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) &&
|
|
CI->getLimitedValue(BitWidth) < BitWidth) {
|
|
return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
|
|
NumCastsRemoved);
|
|
}
|
|
}
|
|
break;
|
|
case Instruction::ZExt:
|
|
case Instruction::SExt:
|
|
case Instruction::Trunc:
|
|
// If this is the same kind of case as our original (e.g. zext+zext), we
|
|
// can safely replace it. Note that replacing it does not reduce the number
|
|
// of casts in the input.
|
|
if (Opc == CastOpc)
|
|
return true;
|
|
|
|
// sext (zext ty1), ty2 -> zext ty2
|
|
if (CastOpc == Instruction::SExt && Opc == Instruction::ZExt)
|
|
return true;
|
|
break;
|
|
case Instruction::Select: {
|
|
SelectInst *SI = cast<SelectInst>(I);
|
|
return CanEvaluateInDifferentType(SI->getTrueValue(), Ty, CastOpc,
|
|
NumCastsRemoved) &&
|
|
CanEvaluateInDifferentType(SI->getFalseValue(), Ty, CastOpc,
|
|
NumCastsRemoved);
|
|
}
|
|
case Instruction::PHI: {
|
|
// We can change a phi if we can change all operands.
|
|
PHINode *PN = cast<PHINode>(I);
|
|
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
|
|
if (!CanEvaluateInDifferentType(PN->getIncomingValue(i), Ty, CastOpc,
|
|
NumCastsRemoved))
|
|
return false;
|
|
return true;
|
|
}
|
|
default:
|
|
// TODO: Can handle more cases here.
|
|
break;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/// EvaluateInDifferentType - Given an expression that
|
|
/// CanEvaluateInDifferentType returns true for, actually insert the code to
|
|
/// evaluate the expression.
|
|
Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty,
|
|
bool isSigned) {
|
|
if (Constant *C = dyn_cast<Constant>(V))
|
|
return ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/);
|
|
|
|
// Otherwise, it must be an instruction.
|
|
Instruction *I = cast<Instruction>(V);
|
|
Instruction *Res = 0;
|
|
unsigned Opc = I->getOpcode();
|
|
switch (Opc) {
|
|
case Instruction::Add:
|
|
case Instruction::Sub:
|
|
case Instruction::Mul:
|
|
case Instruction::And:
|
|
case Instruction::Or:
|
|
case Instruction::Xor:
|
|
case Instruction::AShr:
|
|
case Instruction::LShr:
|
|
case Instruction::Shl: {
|
|
Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned);
|
|
Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
|
|
Res = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS);
|
|
break;
|
|
}
|
|
case Instruction::Trunc:
|
|
case Instruction::ZExt:
|
|
case Instruction::SExt:
|
|
// If the source type of the cast is the type we're trying for then we can
|
|
// just return the source. There's no need to insert it because it is not
|
|
// new.
|
|
if (I->getOperand(0)->getType() == Ty)
|
|
return I->getOperand(0);
|
|
|
|
// Otherwise, must be the same type of cast, so just reinsert a new one.
|
|
Res = CastInst::Create(cast<CastInst>(I)->getOpcode(), I->getOperand(0),
|
|
Ty);
|
|
break;
|
|
case Instruction::Select: {
|
|
Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
|
|
Value *False = EvaluateInDifferentType(I->getOperand(2), Ty, isSigned);
|
|
Res = SelectInst::Create(I->getOperand(0), True, False);
|
|
break;
|
|
}
|
|
case Instruction::PHI: {
|
|
PHINode *OPN = cast<PHINode>(I);
|
|
PHINode *NPN = PHINode::Create(Ty);
|
|
for (unsigned i = 0, e = OPN->getNumIncomingValues(); i != e; ++i) {
|
|
Value *V =EvaluateInDifferentType(OPN->getIncomingValue(i), Ty, isSigned);
|
|
NPN->addIncoming(V, OPN->getIncomingBlock(i));
|
|
}
|
|
Res = NPN;
|
|
break;
|
|
}
|
|
default:
|
|
// TODO: Can handle more cases here.
|
|
assert(0 && "Unreachable!");
|
|
break;
|
|
}
|
|
|
|
Res->takeName(I);
|
|
return InsertNewInstBefore(Res, *I);
|
|
}
|
|
|
|
/// @brief Implement the transforms common to all CastInst visitors.
|
|
Instruction *InstCombiner::commonCastTransforms(CastInst &CI) {
|
|
Value *Src = CI.getOperand(0);
|
|
|
|
// Many cases of "cast of a cast" are eliminable. If it's eliminable we just
|
|
// eliminate it now.
|
|
if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
|
|
if (Instruction::CastOps opc =
|
|
isEliminableCastPair(CSrc, CI.getOpcode(), CI.getType(), TD)) {
|
|
// The first cast (CSrc) is eliminable so we need to fix up or replace
|
|
// the second cast (CI). CSrc will then have a good chance of being dead.
|
|
return CastInst::Create(opc, CSrc->getOperand(0), CI.getType());
|
|
}
|
|
}
|
|
|
|
// If we are casting a select then fold the cast into the select
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Src))
|
|
if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
|
|
return NV;
|
|
|
|
// If we are casting a PHI then fold the cast into the PHI
|
|
if (isa<PHINode>(Src))
|
|
if (Instruction *NV = FoldOpIntoPhi(CI))
|
|
return NV;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/// FindElementAtOffset - Given a type and a constant offset, determine whether
|
|
/// or not there is a sequence of GEP indices into the type that will land us at
|
|
/// the specified offset. If so, fill them into NewIndices and return the
|
|
/// resultant element type, otherwise return null.
|
|
static const Type *FindElementAtOffset(const Type *Ty, int64_t Offset,
|
|
SmallVectorImpl<Value*> &NewIndices,
|
|
const TargetData *TD) {
|
|
if (!Ty->isSized()) return 0;
|
|
|
|
// Start with the index over the outer type. Note that the type size
|
|
// might be zero (even if the offset isn't zero) if the indexed type
|
|
// is something like [0 x {int, int}]
|
|
const Type *IntPtrTy = TD->getIntPtrType();
|
|
int64_t FirstIdx = 0;
|
|
if (int64_t TySize = TD->getTypePaddedSize(Ty)) {
|
|
FirstIdx = Offset/TySize;
|
|
Offset -= FirstIdx*TySize;
|
|
|
|
// Handle hosts where % returns negative instead of values [0..TySize).
|
|
if (Offset < 0) {
|
|
--FirstIdx;
|
|
Offset += TySize;
|
|
assert(Offset >= 0);
|
|
}
|
|
assert((uint64_t)Offset < (uint64_t)TySize && "Out of range offset");
|
|
}
|
|
|
|
NewIndices.push_back(ConstantInt::get(IntPtrTy, FirstIdx));
|
|
|
|
// Index into the types. If we fail, set OrigBase to null.
|
|
while (Offset) {
|
|
// Indexing into tail padding between struct/array elements.
|
|
if (uint64_t(Offset*8) >= TD->getTypeSizeInBits(Ty))
|
|
return 0;
|
|
|
|
if (const StructType *STy = dyn_cast<StructType>(Ty)) {
|
|
const StructLayout *SL = TD->getStructLayout(STy);
|
|
assert(Offset < (int64_t)SL->getSizeInBytes() &&
|
|
"Offset must stay within the indexed type");
|
|
|
|
unsigned Elt = SL->getElementContainingOffset(Offset);
|
|
NewIndices.push_back(ConstantInt::get(Type::Int32Ty, Elt));
|
|
|
|
Offset -= SL->getElementOffset(Elt);
|
|
Ty = STy->getElementType(Elt);
|
|
} else if (const ArrayType *AT = dyn_cast<ArrayType>(Ty)) {
|
|
uint64_t EltSize = TD->getTypePaddedSize(AT->getElementType());
|
|
assert(EltSize && "Cannot index into a zero-sized array");
|
|
NewIndices.push_back(ConstantInt::get(IntPtrTy,Offset/EltSize));
|
|
Offset %= EltSize;
|
|
Ty = AT->getElementType();
|
|
} else {
|
|
// Otherwise, we can't index into the middle of this atomic type, bail.
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
return Ty;
|
|
}
|
|
|
|
/// @brief Implement the transforms for cast of pointer (bitcast/ptrtoint)
|
|
Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) {
|
|
Value *Src = CI.getOperand(0);
|
|
|
|
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
|
|
// If casting the result of a getelementptr instruction with no offset, turn
|
|
// this into a cast of the original pointer!
|
|
if (GEP->hasAllZeroIndices()) {
|
|
// Changing the cast operand is usually not a good idea but it is safe
|
|
// here because the pointer operand is being replaced with another
|
|
// pointer operand so the opcode doesn't need to change.
|
|
AddToWorkList(GEP);
|
|
CI.setOperand(0, GEP->getOperand(0));
|
|
return &CI;
|
|
}
|
|
|
|
// If the GEP has a single use, and the base pointer is a bitcast, and the
|
|
// GEP computes a constant offset, see if we can convert these three
|
|
// instructions into fewer. This typically happens with unions and other
|
|
// non-type-safe code.
|
|
if (GEP->hasOneUse() && isa<BitCastInst>(GEP->getOperand(0))) {
|
|
if (GEP->hasAllConstantIndices()) {
|
|
// We are guaranteed to get a constant from EmitGEPOffset.
|
|
ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(GEP, CI, *this));
|
|
int64_t Offset = OffsetV->getSExtValue();
|
|
|
|
// Get the base pointer input of the bitcast, and the type it points to.
|
|
Value *OrigBase = cast<BitCastInst>(GEP->getOperand(0))->getOperand(0);
|
|
const Type *GEPIdxTy =
|
|
cast<PointerType>(OrigBase->getType())->getElementType();
|
|
SmallVector<Value*, 8> NewIndices;
|
|
if (FindElementAtOffset(GEPIdxTy, Offset, NewIndices, TD)) {
|
|
// If we were able to index down into an element, create the GEP
|
|
// and bitcast the result. This eliminates one bitcast, potentially
|
|
// two.
|
|
Instruction *NGEP = GetElementPtrInst::Create(OrigBase,
|
|
NewIndices.begin(),
|
|
NewIndices.end(), "");
|
|
InsertNewInstBefore(NGEP, CI);
|
|
NGEP->takeName(GEP);
|
|
|
|
if (isa<BitCastInst>(CI))
|
|
return new BitCastInst(NGEP, CI.getType());
|
|
assert(isa<PtrToIntInst>(CI));
|
|
return new PtrToIntInst(NGEP, CI.getType());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return commonCastTransforms(CI);
|
|
}
|
|
|
|
|
|
/// Only the TRUNC, ZEXT, SEXT, and BITCAST can both operand and result as
|
|
/// integer types. This function implements the common transforms for all those
|
|
/// cases.
|
|
/// @brief Implement the transforms common to CastInst with integer operands
|
|
Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) {
|
|
if (Instruction *Result = commonCastTransforms(CI))
|
|
return Result;
|
|
|
|
Value *Src = CI.getOperand(0);
|
|
const Type *SrcTy = Src->getType();
|
|
const Type *DestTy = CI.getType();
|
|
uint32_t SrcBitSize = SrcTy->getPrimitiveSizeInBits();
|
|
uint32_t DestBitSize = DestTy->getPrimitiveSizeInBits();
|
|
|
|
// See if we can simplify any instructions used by the LHS whose sole
|
|
// purpose is to compute bits we don't care about.
|
|
if (SimplifyDemandedInstructionBits(CI))
|
|
return &CI;
|
|
|
|
// If the source isn't an instruction or has more than one use then we
|
|
// can't do anything more.
|
|
Instruction *SrcI = dyn_cast<Instruction>(Src);
|
|
if (!SrcI || !Src->hasOneUse())
|
|
return 0;
|
|
|
|
// Attempt to propagate the cast into the instruction for int->int casts.
|
|
int NumCastsRemoved = 0;
|
|
if (!isa<BitCastInst>(CI) &&
|
|
CanEvaluateInDifferentType(SrcI, cast<IntegerType>(DestTy),
|
|
CI.getOpcode(), NumCastsRemoved)) {
|
|
// If this cast is a truncate, evaluting in a different type always
|
|
// eliminates the cast, so it is always a win. If this is a zero-extension,
|
|
// we need to do an AND to maintain the clear top-part of the computation,
|
|
// so we require that the input have eliminated at least one cast. If this
|
|
// is a sign extension, we insert two new casts (to do the extension) so we
|
|
// require that two casts have been eliminated.
|
|
bool DoXForm = false;
|
|
bool JustReplace = false;
|
|
switch (CI.getOpcode()) {
|
|
default:
|
|
// All the others use floating point so we shouldn't actually
|
|
// get here because of the check above.
|
|
assert(0 && "Unknown cast type");
|
|
case Instruction::Trunc:
|
|
DoXForm = true;
|
|
break;
|
|
case Instruction::ZExt: {
|
|
DoXForm = NumCastsRemoved >= 1;
|
|
if (!DoXForm && 0) {
|
|
// If it's unnecessary to issue an AND to clear the high bits, it's
|
|
// always profitable to do this xform.
|
|
Value *TryRes = EvaluateInDifferentType(SrcI, DestTy, false);
|
|
APInt Mask(APInt::getBitsSet(DestBitSize, SrcBitSize, DestBitSize));
|
|
if (MaskedValueIsZero(TryRes, Mask))
|
|
return ReplaceInstUsesWith(CI, TryRes);
|
|
|
|
if (Instruction *TryI = dyn_cast<Instruction>(TryRes))
|
|
if (TryI->use_empty())
|
|
EraseInstFromFunction(*TryI);
|
|
}
|
|
break;
|
|
}
|
|
case Instruction::SExt: {
|
|
DoXForm = NumCastsRemoved >= 2;
|
|
if (!DoXForm && !isa<TruncInst>(SrcI) && 0) {
|
|
// If we do not have to emit the truncate + sext pair, then it's always
|
|
// profitable to do this xform.
|
|
//
|
|
// It's not safe to eliminate the trunc + sext pair if one of the
|
|
// eliminated cast is a truncate. e.g.
|
|
// t2 = trunc i32 t1 to i16
|
|
// t3 = sext i16 t2 to i32
|
|
// !=
|
|
// i32 t1
|
|
Value *TryRes = EvaluateInDifferentType(SrcI, DestTy, true);
|
|
unsigned NumSignBits = ComputeNumSignBits(TryRes);
|
|
if (NumSignBits > (DestBitSize - SrcBitSize))
|
|
return ReplaceInstUsesWith(CI, TryRes);
|
|
|
|
if (Instruction *TryI = dyn_cast<Instruction>(TryRes))
|
|
if (TryI->use_empty())
|
|
EraseInstFromFunction(*TryI);
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (DoXForm) {
|
|
DOUT << "ICE: EvaluateInDifferentType converting expression type to avoid"
|
|
<< " cast: " << CI;
|
|
Value *Res = EvaluateInDifferentType(SrcI, DestTy,
|
|
CI.getOpcode() == Instruction::SExt);
|
|
if (JustReplace)
|
|
// Just replace this cast with the result.
|
|
return ReplaceInstUsesWith(CI, Res);
|
|
|
|
assert(Res->getType() == DestTy);
|
|
switch (CI.getOpcode()) {
|
|
default: assert(0 && "Unknown cast type!");
|
|
case Instruction::Trunc:
|
|
case Instruction::BitCast:
|
|
// Just replace this cast with the result.
|
|
return ReplaceInstUsesWith(CI, Res);
|
|
case Instruction::ZExt: {
|
|
assert(SrcBitSize < DestBitSize && "Not a zext?");
|
|
|
|
// If the high bits are already zero, just replace this cast with the
|
|
// result.
|
|
APInt Mask(APInt::getBitsSet(DestBitSize, SrcBitSize, DestBitSize));
|
|
if (MaskedValueIsZero(Res, Mask))
|
|
return ReplaceInstUsesWith(CI, Res);
|
|
|
|
// We need to emit an AND to clear the high bits.
|
|
Constant *C = ConstantInt::get(APInt::getLowBitsSet(DestBitSize,
|
|
SrcBitSize));
|
|
return BinaryOperator::CreateAnd(Res, C);
|
|
}
|
|
case Instruction::SExt: {
|
|
// If the high bits are already filled with sign bit, just replace this
|
|
// cast with the result.
|
|
unsigned NumSignBits = ComputeNumSignBits(Res);
|
|
if (NumSignBits > (DestBitSize - SrcBitSize))
|
|
return ReplaceInstUsesWith(CI, Res);
|
|
|
|
// We need to emit a cast to truncate, then a cast to sext.
|
|
return CastInst::Create(Instruction::SExt,
|
|
InsertCastBefore(Instruction::Trunc, Res, Src->getType(),
|
|
CI), DestTy);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
|
|
Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
|
|
|
|
switch (SrcI->getOpcode()) {
|
|
case Instruction::Add:
|
|
case Instruction::Mul:
|
|
case Instruction::And:
|
|
case Instruction::Or:
|
|
case Instruction::Xor:
|
|
// If we are discarding information, rewrite.
|
|
if (DestBitSize <= SrcBitSize && DestBitSize != 1) {
|
|
// Don't insert two casts if they cannot be eliminated. We allow
|
|
// two casts to be inserted if the sizes are the same. This could
|
|
// only be converting signedness, which is a noop.
|
|
if (DestBitSize == SrcBitSize ||
|
|
!ValueRequiresCast(CI.getOpcode(), Op1, DestTy,TD) ||
|
|
!ValueRequiresCast(CI.getOpcode(), Op0, DestTy, TD)) {
|
|
Instruction::CastOps opcode = CI.getOpcode();
|
|
Value *Op0c = InsertCastBefore(opcode, Op0, DestTy, *SrcI);
|
|
Value *Op1c = InsertCastBefore(opcode, Op1, DestTy, *SrcI);
|
|
return BinaryOperator::Create(
|
|
cast<BinaryOperator>(SrcI)->getOpcode(), Op0c, Op1c);
|
|
}
|
|
}
|
|
|
|
// cast (xor bool X, true) to int --> xor (cast bool X to int), 1
|
|
if (isa<ZExtInst>(CI) && SrcBitSize == 1 &&
|
|
SrcI->getOpcode() == Instruction::Xor &&
|
|
Op1 == ConstantInt::getTrue() &&
|
|
(!Op0->hasOneUse() || !isa<CmpInst>(Op0))) {
|
|
Value *New = InsertCastBefore(Instruction::ZExt, Op0, DestTy, CI);
|
|
return BinaryOperator::CreateXor(New, ConstantInt::get(CI.getType(), 1));
|
|
}
|
|
break;
|
|
case Instruction::SDiv:
|
|
case Instruction::UDiv:
|
|
case Instruction::SRem:
|
|
case Instruction::URem:
|
|
// If we are just changing the sign, rewrite.
|
|
if (DestBitSize == SrcBitSize) {
|
|
// Don't insert two casts if they cannot be eliminated. We allow
|
|
// two casts to be inserted if the sizes are the same. This could
|
|
// only be converting signedness, which is a noop.
|
|
if (!ValueRequiresCast(CI.getOpcode(), Op1, DestTy, TD) ||
|
|
!ValueRequiresCast(CI.getOpcode(), Op0, DestTy, TD)) {
|
|
Value *Op0c = InsertCastBefore(Instruction::BitCast,
|
|
Op0, DestTy, *SrcI);
|
|
Value *Op1c = InsertCastBefore(Instruction::BitCast,
|
|
Op1, DestTy, *SrcI);
|
|
return BinaryOperator::Create(
|
|
cast<BinaryOperator>(SrcI)->getOpcode(), Op0c, Op1c);
|
|
}
|
|
}
|
|
break;
|
|
|
|
case Instruction::Shl:
|
|
// Allow changing the sign of the source operand. Do not allow
|
|
// changing the size of the shift, UNLESS the shift amount is a
|
|
// constant. We must not change variable sized shifts to a smaller
|
|
// size, because it is undefined to shift more bits out than exist
|
|
// in the value.
|
|
if (DestBitSize == SrcBitSize ||
|
|
(DestBitSize < SrcBitSize && isa<Constant>(Op1))) {
|
|
Instruction::CastOps opcode = (DestBitSize == SrcBitSize ?
|
|
Instruction::BitCast : Instruction::Trunc);
|
|
Value *Op0c = InsertCastBefore(opcode, Op0, DestTy, *SrcI);
|
|
Value *Op1c = InsertCastBefore(opcode, Op1, DestTy, *SrcI);
|
|
return BinaryOperator::CreateShl(Op0c, Op1c);
|
|
}
|
|
break;
|
|
case Instruction::AShr:
|
|
// If this is a signed shr, and if all bits shifted in are about to be
|
|
// truncated off, turn it into an unsigned shr to allow greater
|
|
// simplifications.
|
|
if (DestBitSize < SrcBitSize &&
|
|
isa<ConstantInt>(Op1)) {
|
|
uint32_t ShiftAmt = cast<ConstantInt>(Op1)->getLimitedValue(SrcBitSize);
|
|
if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) {
|
|
// Insert the new logical shift right.
|
|
return BinaryOperator::CreateLShr(Op0, Op1);
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
|
|
if (Instruction *Result = commonIntCastTransforms(CI))
|
|
return Result;
|
|
|
|
Value *Src = CI.getOperand(0);
|
|
const Type *Ty = CI.getType();
|
|
uint32_t DestBitWidth = Ty->getPrimitiveSizeInBits();
|
|
uint32_t SrcBitWidth = cast<IntegerType>(Src->getType())->getBitWidth();
|
|
|
|
if (Instruction *SrcI = dyn_cast<Instruction>(Src)) {
|
|
switch (SrcI->getOpcode()) {
|
|
default: break;
|
|
case Instruction::LShr:
|
|
// We can shrink lshr to something smaller if we know the bits shifted in
|
|
// are already zeros.
|
|
if (ConstantInt *ShAmtV = dyn_cast<ConstantInt>(SrcI->getOperand(1))) {
|
|
uint32_t ShAmt = ShAmtV->getLimitedValue(SrcBitWidth);
|
|
|
|
// Get a mask for the bits shifting in.
|
|
APInt Mask(APInt::getLowBitsSet(SrcBitWidth, ShAmt).shl(DestBitWidth));
|
|
Value* SrcIOp0 = SrcI->getOperand(0);
|
|
if (SrcI->hasOneUse() && MaskedValueIsZero(SrcIOp0, Mask)) {
|
|
if (ShAmt >= DestBitWidth) // All zeros.
|
|
return ReplaceInstUsesWith(CI, Constant::getNullValue(Ty));
|
|
|
|
// Okay, we can shrink this. Truncate the input, then return a new
|
|
// shift.
|
|
Value *V1 = InsertCastBefore(Instruction::Trunc, SrcIOp0, Ty, CI);
|
|
Value *V2 = InsertCastBefore(Instruction::Trunc, SrcI->getOperand(1),
|
|
Ty, CI);
|
|
return BinaryOperator::CreateLShr(V1, V2);
|
|
}
|
|
} else { // This is a variable shr.
|
|
|
|
// Turn 'trunc (lshr X, Y) to bool' into '(X & (1 << Y)) != 0'. This is
|
|
// more LLVM instructions, but allows '1 << Y' to be hoisted if
|
|
// loop-invariant and CSE'd.
|
|
if (CI.getType() == Type::Int1Ty && SrcI->hasOneUse()) {
|
|
Value *One = ConstantInt::get(SrcI->getType(), 1);
|
|
|
|
Value *V = InsertNewInstBefore(
|
|
BinaryOperator::CreateShl(One, SrcI->getOperand(1),
|
|
"tmp"), CI);
|
|
V = InsertNewInstBefore(BinaryOperator::CreateAnd(V,
|
|
SrcI->getOperand(0),
|
|
"tmp"), CI);
|
|
Value *Zero = Constant::getNullValue(V->getType());
|
|
return new ICmpInst(ICmpInst::ICMP_NE, V, Zero);
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/// transformZExtICmp - Transform (zext icmp) to bitwise / integer operations
|
|
/// in order to eliminate the icmp.
|
|
Instruction *InstCombiner::transformZExtICmp(ICmpInst *ICI, Instruction &CI,
|
|
bool DoXform) {
|
|
// If we are just checking for a icmp eq of a single bit and zext'ing it
|
|
// to an integer, then shift the bit to the appropriate place and then
|
|
// cast to integer to avoid the comparison.
|
|
if (ConstantInt *Op1C = dyn_cast<ConstantInt>(ICI->getOperand(1))) {
|
|
const APInt &Op1CV = Op1C->getValue();
|
|
|
|
// zext (x <s 0) to i32 --> x>>u31 true if signbit set.
|
|
// zext (x >s -1) to i32 --> (x>>u31)^1 true if signbit clear.
|
|
if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV == 0) ||
|
|
(ICI->getPredicate() == ICmpInst::ICMP_SGT &&Op1CV.isAllOnesValue())) {
|
|
if (!DoXform) return ICI;
|
|
|
|
Value *In = ICI->getOperand(0);
|
|
Value *Sh = ConstantInt::get(In->getType(),
|
|
In->getType()->getPrimitiveSizeInBits()-1);
|
|
In = InsertNewInstBefore(BinaryOperator::CreateLShr(In, Sh,
|
|
In->getName()+".lobit"),
|
|
CI);
|
|
if (In->getType() != CI.getType())
|
|
In = CastInst::CreateIntegerCast(In, CI.getType(),
|
|
false/*ZExt*/, "tmp", &CI);
|
|
|
|
if (ICI->getPredicate() == ICmpInst::ICMP_SGT) {
|
|
Constant *One = ConstantInt::get(In->getType(), 1);
|
|
In = InsertNewInstBefore(BinaryOperator::CreateXor(In, One,
|
|
In->getName()+".not"),
|
|
CI);
|
|
}
|
|
|
|
return ReplaceInstUsesWith(CI, In);
|
|
}
|
|
|
|
|
|
|
|
// zext (X == 0) to i32 --> X^1 iff X has only the low bit set.
|
|
// zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
|
|
// zext (X == 1) to i32 --> X iff X has only the low bit set.
|
|
// zext (X == 2) to i32 --> X>>1 iff X has only the 2nd bit set.
|
|
// zext (X != 0) to i32 --> X iff X has only the low bit set.
|
|
// zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set.
|
|
// zext (X != 1) to i32 --> X^1 iff X has only the low bit set.
|
|
// zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set.
|
|
if ((Op1CV == 0 || Op1CV.isPowerOf2()) &&
|
|
// This only works for EQ and NE
|
|
ICI->isEquality()) {
|
|
// If Op1C some other power of two, convert:
|
|
uint32_t BitWidth = Op1C->getType()->getBitWidth();
|
|
APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
|
|
APInt TypeMask(APInt::getAllOnesValue(BitWidth));
|
|
ComputeMaskedBits(ICI->getOperand(0), TypeMask, KnownZero, KnownOne);
|
|
|
|
APInt KnownZeroMask(~KnownZero);
|
|
if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1?
|
|
if (!DoXform) return ICI;
|
|
|
|
bool isNE = ICI->getPredicate() == ICmpInst::ICMP_NE;
|
|
if (Op1CV != 0 && (Op1CV != KnownZeroMask)) {
|
|
// (X&4) == 2 --> false
|
|
// (X&4) != 2 --> true
|
|
Constant *Res = ConstantInt::get(Type::Int1Ty, isNE);
|
|
Res = ConstantExpr::getZExt(Res, CI.getType());
|
|
return ReplaceInstUsesWith(CI, Res);
|
|
}
|
|
|
|
uint32_t ShiftAmt = KnownZeroMask.logBase2();
|
|
Value *In = ICI->getOperand(0);
|
|
if (ShiftAmt) {
|
|
// Perform a logical shr by shiftamt.
|
|
// Insert the shift to put the result in the low bit.
|
|
In = InsertNewInstBefore(BinaryOperator::CreateLShr(In,
|
|
ConstantInt::get(In->getType(), ShiftAmt),
|
|
In->getName()+".lobit"), CI);
|
|
}
|
|
|
|
if ((Op1CV != 0) == isNE) { // Toggle the low bit.
|
|
Constant *One = ConstantInt::get(In->getType(), 1);
|
|
In = BinaryOperator::CreateXor(In, One, "tmp");
|
|
InsertNewInstBefore(cast<Instruction>(In), CI);
|
|
}
|
|
|
|
if (CI.getType() == In->getType())
|
|
return ReplaceInstUsesWith(CI, In);
|
|
else
|
|
return CastInst::CreateIntegerCast(In, CI.getType(), false/*ZExt*/);
|
|
}
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitZExt(ZExtInst &CI) {
|
|
// If one of the common conversion will work ..
|
|
if (Instruction *Result = commonIntCastTransforms(CI))
|
|
return Result;
|
|
|
|
Value *Src = CI.getOperand(0);
|
|
|
|
// If this is a TRUNC followed by a ZEXT then we are dealing with integral
|
|
// types and if the sizes are just right we can convert this into a logical
|
|
// 'and' which will be much cheaper than the pair of casts.
|
|
if (TruncInst *CSrc = dyn_cast<TruncInst>(Src)) { // A->B->C cast
|
|
// Get the sizes of the types involved. We know that the intermediate type
|
|
// will be smaller than A or C, but don't know the relation between A and C.
|
|
Value *A = CSrc->getOperand(0);
|
|
unsigned SrcSize = A->getType()->getPrimitiveSizeInBits();
|
|
unsigned MidSize = CSrc->getType()->getPrimitiveSizeInBits();
|
|
unsigned DstSize = CI.getType()->getPrimitiveSizeInBits();
|
|
// If we're actually extending zero bits, then if
|
|
// SrcSize < DstSize: zext(a & mask)
|
|
// SrcSize == DstSize: a & mask
|
|
// SrcSize > DstSize: trunc(a) & mask
|
|
if (SrcSize < DstSize) {
|
|
APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
|
|
Constant *AndConst = ConstantInt::get(AndValue);
|
|
Instruction *And =
|
|
BinaryOperator::CreateAnd(A, AndConst, CSrc->getName()+".mask");
|
|
InsertNewInstBefore(And, CI);
|
|
return new ZExtInst(And, CI.getType());
|
|
} else if (SrcSize == DstSize) {
|
|
APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize));
|
|
return BinaryOperator::CreateAnd(A, ConstantInt::get(AndValue));
|
|
} else if (SrcSize > DstSize) {
|
|
Instruction *Trunc = new TruncInst(A, CI.getType(), "tmp");
|
|
InsertNewInstBefore(Trunc, CI);
|
|
APInt AndValue(APInt::getLowBitsSet(DstSize, MidSize));
|
|
return BinaryOperator::CreateAnd(Trunc, ConstantInt::get(AndValue));
|
|
}
|
|
}
|
|
|
|
if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src))
|
|
return transformZExtICmp(ICI, CI);
|
|
|
|
BinaryOperator *SrcI = dyn_cast<BinaryOperator>(Src);
|
|
if (SrcI && SrcI->getOpcode() == Instruction::Or) {
|
|
// zext (or icmp, icmp) --> or (zext icmp), (zext icmp) if at least one
|
|
// of the (zext icmp) will be transformed.
|
|
ICmpInst *LHS = dyn_cast<ICmpInst>(SrcI->getOperand(0));
|
|
ICmpInst *RHS = dyn_cast<ICmpInst>(SrcI->getOperand(1));
|
|
if (LHS && RHS && LHS->hasOneUse() && RHS->hasOneUse() &&
|
|
(transformZExtICmp(LHS, CI, false) ||
|
|
transformZExtICmp(RHS, CI, false))) {
|
|
Value *LCast = InsertCastBefore(Instruction::ZExt, LHS, CI.getType(), CI);
|
|
Value *RCast = InsertCastBefore(Instruction::ZExt, RHS, CI.getType(), CI);
|
|
return BinaryOperator::Create(Instruction::Or, LCast, RCast);
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitSExt(SExtInst &CI) {
|
|
if (Instruction *I = commonIntCastTransforms(CI))
|
|
return I;
|
|
|
|
Value *Src = CI.getOperand(0);
|
|
|
|
// Canonicalize sign-extend from i1 to a select.
|
|
if (Src->getType() == Type::Int1Ty)
|
|
return SelectInst::Create(Src,
|
|
ConstantInt::getAllOnesValue(CI.getType()),
|
|
Constant::getNullValue(CI.getType()));
|
|
|
|
// See if the value being truncated is already sign extended. If so, just
|
|
// eliminate the trunc/sext pair.
|
|
if (getOpcode(Src) == Instruction::Trunc) {
|
|
Value *Op = cast<User>(Src)->getOperand(0);
|
|
unsigned OpBits = cast<IntegerType>(Op->getType())->getBitWidth();
|
|
unsigned MidBits = cast<IntegerType>(Src->getType())->getBitWidth();
|
|
unsigned DestBits = cast<IntegerType>(CI.getType())->getBitWidth();
|
|
unsigned NumSignBits = ComputeNumSignBits(Op);
|
|
|
|
if (OpBits == DestBits) {
|
|
// Op is i32, Mid is i8, and Dest is i32. If Op has more than 24 sign
|
|
// bits, it is already ready.
|
|
if (NumSignBits > DestBits-MidBits)
|
|
return ReplaceInstUsesWith(CI, Op);
|
|
} else if (OpBits < DestBits) {
|
|
// Op is i32, Mid is i8, and Dest is i64. If Op has more than 24 sign
|
|
// bits, just sext from i32.
|
|
if (NumSignBits > OpBits-MidBits)
|
|
return new SExtInst(Op, CI.getType(), "tmp");
|
|
} else {
|
|
// Op is i64, Mid is i8, and Dest is i32. If Op has more than 56 sign
|
|
// bits, just truncate to i32.
|
|
if (NumSignBits > OpBits-MidBits)
|
|
return new TruncInst(Op, CI.getType(), "tmp");
|
|
}
|
|
}
|
|
|
|
// If the input is a shl/ashr pair of a same constant, then this is a sign
|
|
// extension from a smaller value. If we could trust arbitrary bitwidth
|
|
// integers, we could turn this into a truncate to the smaller bit and then
|
|
// use a sext for the whole extension. Since we don't, look deeper and check
|
|
// for a truncate. If the source and dest are the same type, eliminate the
|
|
// trunc and extend and just do shifts. For example, turn:
|
|
// %a = trunc i32 %i to i8
|
|
// %b = shl i8 %a, 6
|
|
// %c = ashr i8 %b, 6
|
|
// %d = sext i8 %c to i32
|
|
// into:
|
|
// %a = shl i32 %i, 30
|
|
// %d = ashr i32 %a, 30
|
|
Value *A = 0;
|
|
ConstantInt *BA = 0, *CA = 0;
|
|
if (match(Src, m_AShr(m_Shl(m_Value(A), m_ConstantInt(BA)),
|
|
m_ConstantInt(CA))) &&
|
|
BA == CA && isa<TruncInst>(A)) {
|
|
Value *I = cast<TruncInst>(A)->getOperand(0);
|
|
if (I->getType() == CI.getType()) {
|
|
unsigned MidSize = Src->getType()->getPrimitiveSizeInBits();
|
|
unsigned SrcDstSize = CI.getType()->getPrimitiveSizeInBits();
|
|
unsigned ShAmt = CA->getZExtValue()+SrcDstSize-MidSize;
|
|
Constant *ShAmtV = ConstantInt::get(CI.getType(), ShAmt);
|
|
I = InsertNewInstBefore(BinaryOperator::CreateShl(I, ShAmtV,
|
|
CI.getName()), CI);
|
|
return BinaryOperator::CreateAShr(I, ShAmtV);
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/// FitsInFPType - Return a Constant* for the specified FP constant if it fits
|
|
/// in the specified FP type without changing its value.
|
|
static Constant *FitsInFPType(ConstantFP *CFP, const fltSemantics &Sem) {
|
|
bool losesInfo;
|
|
APFloat F = CFP->getValueAPF();
|
|
(void)F.convert(Sem, APFloat::rmNearestTiesToEven, &losesInfo);
|
|
if (!losesInfo)
|
|
return ConstantFP::get(F);
|
|
return 0;
|
|
}
|
|
|
|
/// LookThroughFPExtensions - If this is an fp extension instruction, look
|
|
/// through it until we get the source value.
|
|
static Value *LookThroughFPExtensions(Value *V) {
|
|
if (Instruction *I = dyn_cast<Instruction>(V))
|
|
if (I->getOpcode() == Instruction::FPExt)
|
|
return LookThroughFPExtensions(I->getOperand(0));
|
|
|
|
// If this value is a constant, return the constant in the smallest FP type
|
|
// that can accurately represent it. This allows us to turn
|
|
// (float)((double)X+2.0) into x+2.0f.
|
|
if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) {
|
|
if (CFP->getType() == Type::PPC_FP128Ty)
|
|
return V; // No constant folding of this.
|
|
// See if the value can be truncated to float and then reextended.
|
|
if (Value *V = FitsInFPType(CFP, APFloat::IEEEsingle))
|
|
return V;
|
|
if (CFP->getType() == Type::DoubleTy)
|
|
return V; // Won't shrink.
|
|
if (Value *V = FitsInFPType(CFP, APFloat::IEEEdouble))
|
|
return V;
|
|
// Don't try to shrink to various long double types.
|
|
}
|
|
|
|
return V;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitFPTrunc(FPTruncInst &CI) {
|
|
if (Instruction *I = commonCastTransforms(CI))
|
|
return I;
|
|
|
|
// If we have fptrunc(add (fpextend x), (fpextend y)), where x and y are
|
|
// smaller than the destination type, we can eliminate the truncate by doing
|
|
// the add as the smaller type. This applies to add/sub/mul/div as well as
|
|
// many builtins (sqrt, etc).
|
|
BinaryOperator *OpI = dyn_cast<BinaryOperator>(CI.getOperand(0));
|
|
if (OpI && OpI->hasOneUse()) {
|
|
switch (OpI->getOpcode()) {
|
|
default: break;
|
|
case Instruction::Add:
|
|
case Instruction::Sub:
|
|
case Instruction::Mul:
|
|
case Instruction::FDiv:
|
|
case Instruction::FRem:
|
|
const Type *SrcTy = OpI->getType();
|
|
Value *LHSTrunc = LookThroughFPExtensions(OpI->getOperand(0));
|
|
Value *RHSTrunc = LookThroughFPExtensions(OpI->getOperand(1));
|
|
if (LHSTrunc->getType() != SrcTy &&
|
|
RHSTrunc->getType() != SrcTy) {
|
|
unsigned DstSize = CI.getType()->getPrimitiveSizeInBits();
|
|
// If the source types were both smaller than the destination type of
|
|
// the cast, do this xform.
|
|
if (LHSTrunc->getType()->getPrimitiveSizeInBits() <= DstSize &&
|
|
RHSTrunc->getType()->getPrimitiveSizeInBits() <= DstSize) {
|
|
LHSTrunc = InsertCastBefore(Instruction::FPExt, LHSTrunc,
|
|
CI.getType(), CI);
|
|
RHSTrunc = InsertCastBefore(Instruction::FPExt, RHSTrunc,
|
|
CI.getType(), CI);
|
|
return BinaryOperator::Create(OpI->getOpcode(), LHSTrunc, RHSTrunc);
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitFPExt(CastInst &CI) {
|
|
return commonCastTransforms(CI);
|
|
}
|
|
|
|
Instruction *InstCombiner::visitFPToUI(FPToUIInst &FI) {
|
|
Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
|
|
if (OpI == 0)
|
|
return commonCastTransforms(FI);
|
|
|
|
// fptoui(uitofp(X)) --> X
|
|
// fptoui(sitofp(X)) --> X
|
|
// This is safe if the intermediate type has enough bits in its mantissa to
|
|
// accurately represent all values of X. For example, do not do this with
|
|
// i64->float->i64. This is also safe for sitofp case, because any negative
|
|
// 'X' value would cause an undefined result for the fptoui.
|
|
if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) &&
|
|
OpI->getOperand(0)->getType() == FI.getType() &&
|
|
(int)FI.getType()->getPrimitiveSizeInBits() < /*extra bit for sign */
|
|
OpI->getType()->getFPMantissaWidth())
|
|
return ReplaceInstUsesWith(FI, OpI->getOperand(0));
|
|
|
|
return commonCastTransforms(FI);
|
|
}
|
|
|
|
Instruction *InstCombiner::visitFPToSI(FPToSIInst &FI) {
|
|
Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0));
|
|
if (OpI == 0)
|
|
return commonCastTransforms(FI);
|
|
|
|
// fptosi(sitofp(X)) --> X
|
|
// fptosi(uitofp(X)) --> X
|
|
// This is safe if the intermediate type has enough bits in its mantissa to
|
|
// accurately represent all values of X. For example, do not do this with
|
|
// i64->float->i64. This is also safe for sitofp case, because any negative
|
|
// 'X' value would cause an undefined result for the fptoui.
|
|
if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) &&
|
|
OpI->getOperand(0)->getType() == FI.getType() &&
|
|
(int)FI.getType()->getPrimitiveSizeInBits() <=
|
|
OpI->getType()->getFPMantissaWidth())
|
|
return ReplaceInstUsesWith(FI, OpI->getOperand(0));
|
|
|
|
return commonCastTransforms(FI);
|
|
}
|
|
|
|
Instruction *InstCombiner::visitUIToFP(CastInst &CI) {
|
|
return commonCastTransforms(CI);
|
|
}
|
|
|
|
Instruction *InstCombiner::visitSIToFP(CastInst &CI) {
|
|
return commonCastTransforms(CI);
|
|
}
|
|
|
|
Instruction *InstCombiner::visitPtrToInt(CastInst &CI) {
|
|
return commonPointerCastTransforms(CI);
|
|
}
|
|
|
|
Instruction *InstCombiner::visitIntToPtr(IntToPtrInst &CI) {
|
|
if (Instruction *I = commonCastTransforms(CI))
|
|
return I;
|
|
|
|
const Type *DestPointee = cast<PointerType>(CI.getType())->getElementType();
|
|
if (!DestPointee->isSized()) return 0;
|
|
|
|
// If this is inttoptr(add (ptrtoint x), cst), try to turn this into a GEP.
|
|
ConstantInt *Cst;
|
|
Value *X;
|
|
if (match(CI.getOperand(0), m_Add(m_Cast<PtrToIntInst>(m_Value(X)),
|
|
m_ConstantInt(Cst)))) {
|
|
// If the source and destination operands have the same type, see if this
|
|
// is a single-index GEP.
|
|
if (X->getType() == CI.getType()) {
|
|
// Get the size of the pointee type.
|
|
uint64_t Size = TD->getTypePaddedSize(DestPointee);
|
|
|
|
// Convert the constant to intptr type.
|
|
APInt Offset = Cst->getValue();
|
|
Offset.sextOrTrunc(TD->getPointerSizeInBits());
|
|
|
|
// If Offset is evenly divisible by Size, we can do this xform.
|
|
if (Size && !APIntOps::srem(Offset, APInt(Offset.getBitWidth(), Size))){
|
|
Offset = APIntOps::sdiv(Offset, APInt(Offset.getBitWidth(), Size));
|
|
return GetElementPtrInst::Create(X, ConstantInt::get(Offset));
|
|
}
|
|
}
|
|
// TODO: Could handle other cases, e.g. where add is indexing into field of
|
|
// struct etc.
|
|
} else if (CI.getOperand(0)->hasOneUse() &&
|
|
match(CI.getOperand(0), m_Add(m_Value(X), m_ConstantInt(Cst)))) {
|
|
// Otherwise, if this is inttoptr(add x, cst), try to turn this into an
|
|
// "inttoptr+GEP" instead of "add+intptr".
|
|
|
|
// Get the size of the pointee type.
|
|
uint64_t Size = TD->getTypePaddedSize(DestPointee);
|
|
|
|
// Convert the constant to intptr type.
|
|
APInt Offset = Cst->getValue();
|
|
Offset.sextOrTrunc(TD->getPointerSizeInBits());
|
|
|
|
// If Offset is evenly divisible by Size, we can do this xform.
|
|
if (Size && !APIntOps::srem(Offset, APInt(Offset.getBitWidth(), Size))){
|
|
Offset = APIntOps::sdiv(Offset, APInt(Offset.getBitWidth(), Size));
|
|
|
|
Instruction *P = InsertNewInstBefore(new IntToPtrInst(X, CI.getType(),
|
|
"tmp"), CI);
|
|
return GetElementPtrInst::Create(P, ConstantInt::get(Offset), "tmp");
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
|
|
// If the operands are integer typed then apply the integer transforms,
|
|
// otherwise just apply the common ones.
|
|
Value *Src = CI.getOperand(0);
|
|
const Type *SrcTy = Src->getType();
|
|
const Type *DestTy = CI.getType();
|
|
|
|
if (SrcTy->isInteger() && DestTy->isInteger()) {
|
|
if (Instruction *Result = commonIntCastTransforms(CI))
|
|
return Result;
|
|
} else if (isa<PointerType>(SrcTy)) {
|
|
if (Instruction *I = commonPointerCastTransforms(CI))
|
|
return I;
|
|
} else {
|
|
if (Instruction *Result = commonCastTransforms(CI))
|
|
return Result;
|
|
}
|
|
|
|
|
|
// Get rid of casts from one type to the same type. These are useless and can
|
|
// be replaced by the operand.
|
|
if (DestTy == Src->getType())
|
|
return ReplaceInstUsesWith(CI, Src);
|
|
|
|
if (const PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) {
|
|
const PointerType *SrcPTy = cast<PointerType>(SrcTy);
|
|
const Type *DstElTy = DstPTy->getElementType();
|
|
const Type *SrcElTy = SrcPTy->getElementType();
|
|
|
|
// If the address spaces don't match, don't eliminate the bitcast, which is
|
|
// required for changing types.
|
|
if (SrcPTy->getAddressSpace() != DstPTy->getAddressSpace())
|
|
return 0;
|
|
|
|
// If we are casting a malloc or alloca to a pointer to a type of the same
|
|
// size, rewrite the allocation instruction to allocate the "right" type.
|
|
if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))
|
|
if (Instruction *V = PromoteCastOfAllocation(CI, *AI))
|
|
return V;
|
|
|
|
// If the source and destination are pointers, and this cast is equivalent
|
|
// to a getelementptr X, 0, 0, 0... turn it into the appropriate gep.
|
|
// This can enhance SROA and other transforms that want type-safe pointers.
|
|
Constant *ZeroUInt = Constant::getNullValue(Type::Int32Ty);
|
|
unsigned NumZeros = 0;
|
|
while (SrcElTy != DstElTy &&
|
|
isa<CompositeType>(SrcElTy) && !isa<PointerType>(SrcElTy) &&
|
|
SrcElTy->getNumContainedTypes() /* not "{}" */) {
|
|
SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(ZeroUInt);
|
|
++NumZeros;
|
|
}
|
|
|
|
// If we found a path from the src to dest, create the getelementptr now.
|
|
if (SrcElTy == DstElTy) {
|
|
SmallVector<Value*, 8> Idxs(NumZeros+1, ZeroUInt);
|
|
return GetElementPtrInst::Create(Src, Idxs.begin(), Idxs.end(), "",
|
|
((Instruction*) NULL));
|
|
}
|
|
}
|
|
|
|
if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) {
|
|
if (SVI->hasOneUse()) {
|
|
// Okay, we have (bitconvert (shuffle ..)). Check to see if this is
|
|
// a bitconvert to a vector with the same # elts.
|
|
if (isa<VectorType>(DestTy) &&
|
|
cast<VectorType>(DestTy)->getNumElements() ==
|
|
SVI->getType()->getNumElements() &&
|
|
SVI->getType()->getNumElements() ==
|
|
cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements()) {
|
|
CastInst *Tmp;
|
|
// If either of the operands is a cast from CI.getType(), then
|
|
// evaluating the shuffle in the casted destination's type will allow
|
|
// us to eliminate at least one cast.
|
|
if (((Tmp = dyn_cast<CastInst>(SVI->getOperand(0))) &&
|
|
Tmp->getOperand(0)->getType() == DestTy) ||
|
|
((Tmp = dyn_cast<CastInst>(SVI->getOperand(1))) &&
|
|
Tmp->getOperand(0)->getType() == DestTy)) {
|
|
Value *LHS = InsertCastBefore(Instruction::BitCast,
|
|
SVI->getOperand(0), DestTy, CI);
|
|
Value *RHS = InsertCastBefore(Instruction::BitCast,
|
|
SVI->getOperand(1), DestTy, CI);
|
|
// Return a new shuffle vector. Use the same element ID's, as we
|
|
// know the vector types match #elts.
|
|
return new ShuffleVectorInst(LHS, RHS, SVI->getOperand(2));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/// GetSelectFoldableOperands - We want to turn code that looks like this:
|
|
/// %C = or %A, %B
|
|
/// %D = select %cond, %C, %A
|
|
/// into:
|
|
/// %C = select %cond, %B, 0
|
|
/// %D = or %A, %C
|
|
///
|
|
/// Assuming that the specified instruction is an operand to the select, return
|
|
/// a bitmask indicating which operands of this instruction are foldable if they
|
|
/// equal the other incoming value of the select.
|
|
///
|
|
static unsigned GetSelectFoldableOperands(Instruction *I) {
|
|
switch (I->getOpcode()) {
|
|
case Instruction::Add:
|
|
case Instruction::Mul:
|
|
case Instruction::And:
|
|
case Instruction::Or:
|
|
case Instruction::Xor:
|
|
return 3; // Can fold through either operand.
|
|
case Instruction::Sub: // Can only fold on the amount subtracted.
|
|
case Instruction::Shl: // Can only fold on the shift amount.
|
|
case Instruction::LShr:
|
|
case Instruction::AShr:
|
|
return 1;
|
|
default:
|
|
return 0; // Cannot fold
|
|
}
|
|
}
|
|
|
|
/// GetSelectFoldableConstant - For the same transformation as the previous
|
|
/// function, return the identity constant that goes into the select.
|
|
static Constant *GetSelectFoldableConstant(Instruction *I) {
|
|
switch (I->getOpcode()) {
|
|
default: assert(0 && "This cannot happen!"); abort();
|
|
case Instruction::Add:
|
|
case Instruction::Sub:
|
|
case Instruction::Or:
|
|
case Instruction::Xor:
|
|
case Instruction::Shl:
|
|
case Instruction::LShr:
|
|
case Instruction::AShr:
|
|
return Constant::getNullValue(I->getType());
|
|
case Instruction::And:
|
|
return Constant::getAllOnesValue(I->getType());
|
|
case Instruction::Mul:
|
|
return ConstantInt::get(I->getType(), 1);
|
|
}
|
|
}
|
|
|
|
/// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
|
|
/// have the same opcode and only one use each. Try to simplify this.
|
|
Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
|
|
Instruction *FI) {
|
|
if (TI->getNumOperands() == 1) {
|
|
// If this is a non-volatile load or a cast from the same type,
|
|
// merge.
|
|
if (TI->isCast()) {
|
|
if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
|
|
return 0;
|
|
} else {
|
|
return 0; // unknown unary op.
|
|
}
|
|
|
|
// Fold this by inserting a select from the input values.
|
|
SelectInst *NewSI = SelectInst::Create(SI.getCondition(), TI->getOperand(0),
|
|
FI->getOperand(0), SI.getName()+".v");
|
|
InsertNewInstBefore(NewSI, SI);
|
|
return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI,
|
|
TI->getType());
|
|
}
|
|
|
|
// Only handle binary operators here.
|
|
if (!isa<BinaryOperator>(TI))
|
|
return 0;
|
|
|
|
// Figure out if the operations have any operands in common.
|
|
Value *MatchOp, *OtherOpT, *OtherOpF;
|
|
bool MatchIsOpZero;
|
|
if (TI->getOperand(0) == FI->getOperand(0)) {
|
|
MatchOp = TI->getOperand(0);
|
|
OtherOpT = TI->getOperand(1);
|
|
OtherOpF = FI->getOperand(1);
|
|
MatchIsOpZero = true;
|
|
} else if (TI->getOperand(1) == FI->getOperand(1)) {
|
|
MatchOp = TI->getOperand(1);
|
|
OtherOpT = TI->getOperand(0);
|
|
OtherOpF = FI->getOperand(0);
|
|
MatchIsOpZero = false;
|
|
} else if (!TI->isCommutative()) {
|
|
return 0;
|
|
} else if (TI->getOperand(0) == FI->getOperand(1)) {
|
|
MatchOp = TI->getOperand(0);
|
|
OtherOpT = TI->getOperand(1);
|
|
OtherOpF = FI->getOperand(0);
|
|
MatchIsOpZero = true;
|
|
} else if (TI->getOperand(1) == FI->getOperand(0)) {
|
|
MatchOp = TI->getOperand(1);
|
|
OtherOpT = TI->getOperand(0);
|
|
OtherOpF = FI->getOperand(1);
|
|
MatchIsOpZero = true;
|
|
} else {
|
|
return 0;
|
|
}
|
|
|
|
// If we reach here, they do have operations in common.
|
|
SelectInst *NewSI = SelectInst::Create(SI.getCondition(), OtherOpT,
|
|
OtherOpF, SI.getName()+".v");
|
|
InsertNewInstBefore(NewSI, SI);
|
|
|
|
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
|
|
if (MatchIsOpZero)
|
|
return BinaryOperator::Create(BO->getOpcode(), MatchOp, NewSI);
|
|
else
|
|
return BinaryOperator::Create(BO->getOpcode(), NewSI, MatchOp);
|
|
}
|
|
assert(0 && "Shouldn't get here");
|
|
return 0;
|
|
}
|
|
|
|
/// visitSelectInstWithICmp - Visit a SelectInst that has an
|
|
/// ICmpInst as its first operand.
|
|
///
|
|
Instruction *InstCombiner::visitSelectInstWithICmp(SelectInst &SI,
|
|
ICmpInst *ICI) {
|
|
bool Changed = false;
|
|
ICmpInst::Predicate Pred = ICI->getPredicate();
|
|
Value *CmpLHS = ICI->getOperand(0);
|
|
Value *CmpRHS = ICI->getOperand(1);
|
|
Value *TrueVal = SI.getTrueValue();
|
|
Value *FalseVal = SI.getFalseValue();
|
|
|
|
// Check cases where the comparison is with a constant that
|
|
// can be adjusted to fit the min/max idiom. We may edit ICI in
|
|
// place here, so make sure the select is the only user.
|
|
if (ICI->hasOneUse())
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(CmpRHS)) {
|
|
switch (Pred) {
|
|
default: break;
|
|
case ICmpInst::ICMP_ULT:
|
|
case ICmpInst::ICMP_SLT: {
|
|
// X < MIN ? T : F --> F
|
|
if (CI->isMinValue(Pred == ICmpInst::ICMP_SLT))
|
|
return ReplaceInstUsesWith(SI, FalseVal);
|
|
// X < C ? X : C-1 --> X > C-1 ? C-1 : X
|
|
Constant *AdjustedRHS = SubOne(CI);
|
|
if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
|
|
(CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
|
|
Pred = ICmpInst::getSwappedPredicate(Pred);
|
|
CmpRHS = AdjustedRHS;
|
|
std::swap(FalseVal, TrueVal);
|
|
ICI->setPredicate(Pred);
|
|
ICI->setOperand(1, CmpRHS);
|
|
SI.setOperand(1, TrueVal);
|
|
SI.setOperand(2, FalseVal);
|
|
Changed = true;
|
|
}
|
|
break;
|
|
}
|
|
case ICmpInst::ICMP_UGT:
|
|
case ICmpInst::ICMP_SGT: {
|
|
// X > MAX ? T : F --> F
|
|
if (CI->isMaxValue(Pred == ICmpInst::ICMP_SGT))
|
|
return ReplaceInstUsesWith(SI, FalseVal);
|
|
// X > C ? X : C+1 --> X < C+1 ? C+1 : X
|
|
Constant *AdjustedRHS = AddOne(CI);
|
|
if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
|
|
(CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
|
|
Pred = ICmpInst::getSwappedPredicate(Pred);
|
|
CmpRHS = AdjustedRHS;
|
|
std::swap(FalseVal, TrueVal);
|
|
ICI->setPredicate(Pred);
|
|
ICI->setOperand(1, CmpRHS);
|
|
SI.setOperand(1, TrueVal);
|
|
SI.setOperand(2, FalseVal);
|
|
Changed = true;
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
|
|
// (x <s 0) ? -1 : 0 -> ashr x, 31 -> all ones if signed
|
|
// (x >s -1) ? -1 : 0 -> ashr x, 31 -> all ones if not signed
|
|
CmpInst::Predicate Pred = CmpInst::BAD_ICMP_PREDICATE;
|
|
if (match(TrueVal, m_ConstantInt<-1>()) &&
|
|
match(FalseVal, m_ConstantInt<0>()))
|
|
Pred = ICI->getPredicate();
|
|
else if (match(TrueVal, m_ConstantInt<0>()) &&
|
|
match(FalseVal, m_ConstantInt<-1>()))
|
|
Pred = CmpInst::getInversePredicate(ICI->getPredicate());
|
|
|
|
if (Pred != CmpInst::BAD_ICMP_PREDICATE) {
|
|
// If we are just checking for a icmp eq of a single bit and zext'ing it
|
|
// to an integer, then shift the bit to the appropriate place and then
|
|
// cast to integer to avoid the comparison.
|
|
const APInt &Op1CV = CI->getValue();
|
|
|
|
// sext (x <s 0) to i32 --> x>>s31 true if signbit set.
|
|
// sext (x >s -1) to i32 --> (x>>s31)^-1 true if signbit clear.
|
|
if ((Pred == ICmpInst::ICMP_SLT && Op1CV == 0) ||
|
|
(Pred == ICmpInst::ICMP_SGT && Op1CV.isAllOnesValue())) {
|
|
Value *In = ICI->getOperand(0);
|
|
Value *Sh = ConstantInt::get(In->getType(),
|
|
In->getType()->getPrimitiveSizeInBits()-1);
|
|
In = InsertNewInstBefore(BinaryOperator::CreateAShr(In, Sh,
|
|
In->getName()+".lobit"),
|
|
*ICI);
|
|
if (In->getType() != SI.getType())
|
|
In = CastInst::CreateIntegerCast(In, SI.getType(),
|
|
true/*SExt*/, "tmp", ICI);
|
|
|
|
if (Pred == ICmpInst::ICMP_SGT)
|
|
In = InsertNewInstBefore(BinaryOperator::CreateNot(In,
|
|
In->getName()+".not"), *ICI);
|
|
|
|
return ReplaceInstUsesWith(SI, In);
|
|
}
|
|
}
|
|
}
|
|
|
|
if (CmpLHS == TrueVal && CmpRHS == FalseVal) {
|
|
// Transform (X == Y) ? X : Y -> Y
|
|
if (Pred == ICmpInst::ICMP_EQ)
|
|
return ReplaceInstUsesWith(SI, FalseVal);
|
|
// Transform (X != Y) ? X : Y -> X
|
|
if (Pred == ICmpInst::ICMP_NE)
|
|
return ReplaceInstUsesWith(SI, TrueVal);
|
|
/// NOTE: if we wanted to, this is where to detect integer MIN/MAX
|
|
|
|
} else if (CmpLHS == FalseVal && CmpRHS == TrueVal) {
|
|
// Transform (X == Y) ? Y : X -> X
|
|
if (Pred == ICmpInst::ICMP_EQ)
|
|
return ReplaceInstUsesWith(SI, FalseVal);
|
|
// Transform (X != Y) ? Y : X -> Y
|
|
if (Pred == ICmpInst::ICMP_NE)
|
|
return ReplaceInstUsesWith(SI, TrueVal);
|
|
/// NOTE: if we wanted to, this is where to detect integer MIN/MAX
|
|
}
|
|
|
|
/// NOTE: if we wanted to, this is where to detect integer ABS
|
|
|
|
return Changed ? &SI : 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
|
|
Value *CondVal = SI.getCondition();
|
|
Value *TrueVal = SI.getTrueValue();
|
|
Value *FalseVal = SI.getFalseValue();
|
|
|
|
// select true, X, Y -> X
|
|
// select false, X, Y -> Y
|
|
if (ConstantInt *C = dyn_cast<ConstantInt>(CondVal))
|
|
return ReplaceInstUsesWith(SI, C->getZExtValue() ? TrueVal : FalseVal);
|
|
|
|
// select C, X, X -> X
|
|
if (TrueVal == FalseVal)
|
|
return ReplaceInstUsesWith(SI, TrueVal);
|
|
|
|
if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
|
|
return ReplaceInstUsesWith(SI, FalseVal);
|
|
if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
|
|
return ReplaceInstUsesWith(SI, TrueVal);
|
|
if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
|
|
if (isa<Constant>(TrueVal))
|
|
return ReplaceInstUsesWith(SI, TrueVal);
|
|
else
|
|
return ReplaceInstUsesWith(SI, FalseVal);
|
|
}
|
|
|
|
if (SI.getType() == Type::Int1Ty) {
|
|
if (ConstantInt *C = dyn_cast<ConstantInt>(TrueVal)) {
|
|
if (C->getZExtValue()) {
|
|
// Change: A = select B, true, C --> A = or B, C
|
|
return BinaryOperator::CreateOr(CondVal, FalseVal);
|
|
} else {
|
|
// Change: A = select B, false, C --> A = and !B, C
|
|
Value *NotCond =
|
|
InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
|
|
"not."+CondVal->getName()), SI);
|
|
return BinaryOperator::CreateAnd(NotCond, FalseVal);
|
|
}
|
|
} else if (ConstantInt *C = dyn_cast<ConstantInt>(FalseVal)) {
|
|
if (C->getZExtValue() == false) {
|
|
// Change: A = select B, C, false --> A = and B, C
|
|
return BinaryOperator::CreateAnd(CondVal, TrueVal);
|
|
} else {
|
|
// Change: A = select B, C, true --> A = or !B, C
|
|
Value *NotCond =
|
|
InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
|
|
"not."+CondVal->getName()), SI);
|
|
return BinaryOperator::CreateOr(NotCond, TrueVal);
|
|
}
|
|
}
|
|
|
|
// select a, b, a -> a&b
|
|
// select a, a, b -> a|b
|
|
if (CondVal == TrueVal)
|
|
return BinaryOperator::CreateOr(CondVal, FalseVal);
|
|
else if (CondVal == FalseVal)
|
|
return BinaryOperator::CreateAnd(CondVal, TrueVal);
|
|
}
|
|
|
|
// Selecting between two integer constants?
|
|
if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
|
|
if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
|
|
// select C, 1, 0 -> zext C to int
|
|
if (FalseValC->isZero() && TrueValC->getValue() == 1) {
|
|
return CastInst::Create(Instruction::ZExt, CondVal, SI.getType());
|
|
} else if (TrueValC->isZero() && FalseValC->getValue() == 1) {
|
|
// select C, 0, 1 -> zext !C to int
|
|
Value *NotCond =
|
|
InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
|
|
"not."+CondVal->getName()), SI);
|
|
return CastInst::Create(Instruction::ZExt, NotCond, SI.getType());
|
|
}
|
|
|
|
if (ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition())) {
|
|
|
|
// (x <s 0) ? -1 : 0 -> ashr x, 31
|
|
if (TrueValC->isAllOnesValue() && FalseValC->isZero())
|
|
if (ConstantInt *CmpCst = dyn_cast<ConstantInt>(IC->getOperand(1))) {
|
|
if (IC->getPredicate() == ICmpInst::ICMP_SLT && CmpCst->isZero()) {
|
|
// The comparison constant and the result are not neccessarily the
|
|
// same width. Make an all-ones value by inserting a AShr.
|
|
Value *X = IC->getOperand(0);
|
|
uint32_t Bits = X->getType()->getPrimitiveSizeInBits();
|
|
Constant *ShAmt = ConstantInt::get(X->getType(), Bits-1);
|
|
Instruction *SRA = BinaryOperator::Create(Instruction::AShr, X,
|
|
ShAmt, "ones");
|
|
InsertNewInstBefore(SRA, SI);
|
|
|
|
// Then cast to the appropriate width.
|
|
return CastInst::CreateIntegerCast(SRA, SI.getType(), true);
|
|
}
|
|
}
|
|
|
|
|
|
// If one of the constants is zero (we know they can't both be) and we
|
|
// have an icmp instruction with zero, and we have an 'and' with the
|
|
// non-constant value, eliminate this whole mess. This corresponds to
|
|
// cases like this: ((X & 27) ? 27 : 0)
|
|
if (TrueValC->isZero() || FalseValC->isZero())
|
|
if (IC->isEquality() && isa<ConstantInt>(IC->getOperand(1)) &&
|
|
cast<Constant>(IC->getOperand(1))->isNullValue())
|
|
if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
|
|
if (ICA->getOpcode() == Instruction::And &&
|
|
isa<ConstantInt>(ICA->getOperand(1)) &&
|
|
(ICA->getOperand(1) == TrueValC ||
|
|
ICA->getOperand(1) == FalseValC) &&
|
|
isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
|
|
// Okay, now we know that everything is set up, we just don't
|
|
// know whether we have a icmp_ne or icmp_eq and whether the
|
|
// true or false val is the zero.
|
|
bool ShouldNotVal = !TrueValC->isZero();
|
|
ShouldNotVal ^= IC->getPredicate() == ICmpInst::ICMP_NE;
|
|
Value *V = ICA;
|
|
if (ShouldNotVal)
|
|
V = InsertNewInstBefore(BinaryOperator::Create(
|
|
Instruction::Xor, V, ICA->getOperand(1)), SI);
|
|
return ReplaceInstUsesWith(SI, V);
|
|
}
|
|
}
|
|
}
|
|
|
|
// See if we are selecting two values based on a comparison of the two values.
|
|
if (FCmpInst *FCI = dyn_cast<FCmpInst>(CondVal)) {
|
|
if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) {
|
|
// Transform (X == Y) ? X : Y -> Y
|
|
if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
|
|
// This is not safe in general for floating point:
|
|
// consider X== -0, Y== +0.
|
|
// It becomes safe if either operand is a nonzero constant.
|
|
ConstantFP *CFPt, *CFPf;
|
|
if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
|
|
!CFPt->getValueAPF().isZero()) ||
|
|
((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
|
|
!CFPf->getValueAPF().isZero()))
|
|
return ReplaceInstUsesWith(SI, FalseVal);
|
|
}
|
|
// Transform (X != Y) ? X : Y -> X
|
|
if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
|
|
return ReplaceInstUsesWith(SI, TrueVal);
|
|
// NOTE: if we wanted to, this is where to detect MIN/MAX
|
|
|
|
} else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){
|
|
// Transform (X == Y) ? Y : X -> X
|
|
if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
|
|
// This is not safe in general for floating point:
|
|
// consider X== -0, Y== +0.
|
|
// It becomes safe if either operand is a nonzero constant.
|
|
ConstantFP *CFPt, *CFPf;
|
|
if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
|
|
!CFPt->getValueAPF().isZero()) ||
|
|
((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
|
|
!CFPf->getValueAPF().isZero()))
|
|
return ReplaceInstUsesWith(SI, FalseVal);
|
|
}
|
|
// Transform (X != Y) ? Y : X -> Y
|
|
if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
|
|
return ReplaceInstUsesWith(SI, TrueVal);
|
|
// NOTE: if we wanted to, this is where to detect MIN/MAX
|
|
}
|
|
// NOTE: if we wanted to, this is where to detect ABS
|
|
}
|
|
|
|
// See if we are selecting two values based on a comparison of the two values.
|
|
if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal))
|
|
if (Instruction *Result = visitSelectInstWithICmp(SI, ICI))
|
|
return Result;
|
|
|
|
if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
|
|
if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
|
|
if (TI->hasOneUse() && FI->hasOneUse()) {
|
|
Instruction *AddOp = 0, *SubOp = 0;
|
|
|
|
// Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
|
|
if (TI->getOpcode() == FI->getOpcode())
|
|
if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
|
|
return IV;
|
|
|
|
// Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
|
|
// even legal for FP.
|
|
if (TI->getOpcode() == Instruction::Sub &&
|
|
FI->getOpcode() == Instruction::Add) {
|
|
AddOp = FI; SubOp = TI;
|
|
} else if (FI->getOpcode() == Instruction::Sub &&
|
|
TI->getOpcode() == Instruction::Add) {
|
|
AddOp = TI; SubOp = FI;
|
|
}
|
|
|
|
if (AddOp) {
|
|
Value *OtherAddOp = 0;
|
|
if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
|
|
OtherAddOp = AddOp->getOperand(1);
|
|
} else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
|
|
OtherAddOp = AddOp->getOperand(0);
|
|
}
|
|
|
|
if (OtherAddOp) {
|
|
// So at this point we know we have (Y -> OtherAddOp):
|
|
// select C, (add X, Y), (sub X, Z)
|
|
Value *NegVal; // Compute -Z
|
|
if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
|
|
NegVal = ConstantExpr::getNeg(C);
|
|
} else {
|
|
NegVal = InsertNewInstBefore(
|
|
BinaryOperator::CreateNeg(SubOp->getOperand(1), "tmp"), SI);
|
|
}
|
|
|
|
Value *NewTrueOp = OtherAddOp;
|
|
Value *NewFalseOp = NegVal;
|
|
if (AddOp != TI)
|
|
std::swap(NewTrueOp, NewFalseOp);
|
|
Instruction *NewSel =
|
|
SelectInst::Create(CondVal, NewTrueOp,
|
|
NewFalseOp, SI.getName() + ".p");
|
|
|
|
NewSel = InsertNewInstBefore(NewSel, SI);
|
|
return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel);
|
|
}
|
|
}
|
|
}
|
|
|
|
// See if we can fold the select into one of our operands.
|
|
if (SI.getType()->isInteger()) {
|
|
// See the comment above GetSelectFoldableOperands for a description of the
|
|
// transformation we are doing here.
|
|
if (Instruction *TVI = dyn_cast<Instruction>(TrueVal))
|
|
if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
|
|
!isa<Constant>(FalseVal))
|
|
if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
|
|
unsigned OpToFold = 0;
|
|
if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
|
|
OpToFold = 1;
|
|
} else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
|
|
OpToFold = 2;
|
|
}
|
|
|
|
if (OpToFold) {
|
|
Constant *C = GetSelectFoldableConstant(TVI);
|
|
Instruction *NewSel =
|
|
SelectInst::Create(SI.getCondition(),
|
|
TVI->getOperand(2-OpToFold), C);
|
|
InsertNewInstBefore(NewSel, SI);
|
|
NewSel->takeName(TVI);
|
|
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
|
|
return BinaryOperator::Create(BO->getOpcode(), FalseVal, NewSel);
|
|
else {
|
|
assert(0 && "Unknown instruction!!");
|
|
}
|
|
}
|
|
}
|
|
|
|
if (Instruction *FVI = dyn_cast<Instruction>(FalseVal))
|
|
if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
|
|
!isa<Constant>(TrueVal))
|
|
if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
|
|
unsigned OpToFold = 0;
|
|
if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
|
|
OpToFold = 1;
|
|
} else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
|
|
OpToFold = 2;
|
|
}
|
|
|
|
if (OpToFold) {
|
|
Constant *C = GetSelectFoldableConstant(FVI);
|
|
Instruction *NewSel =
|
|
SelectInst::Create(SI.getCondition(), C,
|
|
FVI->getOperand(2-OpToFold));
|
|
InsertNewInstBefore(NewSel, SI);
|
|
NewSel->takeName(FVI);
|
|
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
|
|
return BinaryOperator::Create(BO->getOpcode(), TrueVal, NewSel);
|
|
else
|
|
assert(0 && "Unknown instruction!!");
|
|
}
|
|
}
|
|
}
|
|
|
|
if (BinaryOperator::isNot(CondVal)) {
|
|
SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
|
|
SI.setOperand(1, FalseVal);
|
|
SI.setOperand(2, TrueVal);
|
|
return &SI;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/// EnforceKnownAlignment - If the specified pointer points to an object that
|
|
/// we control, modify the object's alignment to PrefAlign. This isn't
|
|
/// often possible though. If alignment is important, a more reliable approach
|
|
/// is to simply align all global variables and allocation instructions to
|
|
/// their preferred alignment from the beginning.
|
|
///
|
|
static unsigned EnforceKnownAlignment(Value *V,
|
|
unsigned Align, unsigned PrefAlign) {
|
|
|
|
User *U = dyn_cast<User>(V);
|
|
if (!U) return Align;
|
|
|
|
switch (getOpcode(U)) {
|
|
default: break;
|
|
case Instruction::BitCast:
|
|
return EnforceKnownAlignment(U->getOperand(0), Align, PrefAlign);
|
|
case Instruction::GetElementPtr: {
|
|
// If all indexes are zero, it is just the alignment of the base pointer.
|
|
bool AllZeroOperands = true;
|
|
for (User::op_iterator i = U->op_begin() + 1, e = U->op_end(); i != e; ++i)
|
|
if (!isa<Constant>(*i) ||
|
|
!cast<Constant>(*i)->isNullValue()) {
|
|
AllZeroOperands = false;
|
|
break;
|
|
}
|
|
|
|
if (AllZeroOperands) {
|
|
// Treat this like a bitcast.
|
|
return EnforceKnownAlignment(U->getOperand(0), Align, PrefAlign);
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
|
|
// If there is a large requested alignment and we can, bump up the alignment
|
|
// of the global.
|
|
if (!GV->isDeclaration()) {
|
|
if (GV->getAlignment() >= PrefAlign)
|
|
Align = GV->getAlignment();
|
|
else {
|
|
GV->setAlignment(PrefAlign);
|
|
Align = PrefAlign;
|
|
}
|
|
}
|
|
} else if (AllocationInst *AI = dyn_cast<AllocationInst>(V)) {
|
|
// If there is a requested alignment and if this is an alloca, round up. We
|
|
// don't do this for malloc, because some systems can't respect the request.
|
|
if (isa<AllocaInst>(AI)) {
|
|
if (AI->getAlignment() >= PrefAlign)
|
|
Align = AI->getAlignment();
|
|
else {
|
|
AI->setAlignment(PrefAlign);
|
|
Align = PrefAlign;
|
|
}
|
|
}
|
|
}
|
|
|
|
return Align;
|
|
}
|
|
|
|
/// GetOrEnforceKnownAlignment - If the specified pointer has an alignment that
|
|
/// we can determine, return it, otherwise return 0. If PrefAlign is specified,
|
|
/// and it is more than the alignment of the ultimate object, see if we can
|
|
/// increase the alignment of the ultimate object, making this check succeed.
|
|
unsigned InstCombiner::GetOrEnforceKnownAlignment(Value *V,
|
|
unsigned PrefAlign) {
|
|
unsigned BitWidth = TD ? TD->getTypeSizeInBits(V->getType()) :
|
|
sizeof(PrefAlign) * CHAR_BIT;
|
|
APInt Mask = APInt::getAllOnesValue(BitWidth);
|
|
APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
|
|
ComputeMaskedBits(V, Mask, KnownZero, KnownOne);
|
|
unsigned TrailZ = KnownZero.countTrailingOnes();
|
|
unsigned Align = 1u << std::min(BitWidth - 1, TrailZ);
|
|
|
|
if (PrefAlign > Align)
|
|
Align = EnforceKnownAlignment(V, Align, PrefAlign);
|
|
|
|
// We don't need to make any adjustment.
|
|
return Align;
|
|
}
|
|
|
|
Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
|
|
unsigned DstAlign = GetOrEnforceKnownAlignment(MI->getOperand(1));
|
|
unsigned SrcAlign = GetOrEnforceKnownAlignment(MI->getOperand(2));
|
|
unsigned MinAlign = std::min(DstAlign, SrcAlign);
|
|
unsigned CopyAlign = MI->getAlignment()->getZExtValue();
|
|
|
|
if (CopyAlign < MinAlign) {
|
|
MI->setAlignment(ConstantInt::get(Type::Int32Ty, MinAlign));
|
|
return MI;
|
|
}
|
|
|
|
// If MemCpyInst length is 1/2/4/8 bytes then replace memcpy with
|
|
// load/store.
|
|
ConstantInt *MemOpLength = dyn_cast<ConstantInt>(MI->getOperand(3));
|
|
if (MemOpLength == 0) return 0;
|
|
|
|
// Source and destination pointer types are always "i8*" for intrinsic. See
|
|
// if the size is something we can handle with a single primitive load/store.
|
|
// A single load+store correctly handles overlapping memory in the memmove
|
|
// case.
|
|
unsigned Size = MemOpLength->getZExtValue();
|
|
if (Size == 0) return MI; // Delete this mem transfer.
|
|
|
|
if (Size > 8 || (Size&(Size-1)))
|
|
return 0; // If not 1/2/4/8 bytes, exit.
|
|
|
|
// Use an integer load+store unless we can find something better.
|
|
Type *NewPtrTy = PointerType::getUnqual(IntegerType::get(Size<<3));
|
|
|
|
// Memcpy forces the use of i8* for the source and destination. That means
|
|
// that if you're using memcpy to move one double around, you'll get a cast
|
|
// from double* to i8*. We'd much rather use a double load+store rather than
|
|
// an i64 load+store, here because this improves the odds that the source or
|
|
// dest address will be promotable. See if we can find a better type than the
|
|
// integer datatype.
|
|
if (Value *Op = getBitCastOperand(MI->getOperand(1))) {
|
|
const Type *SrcETy = cast<PointerType>(Op->getType())->getElementType();
|
|
if (SrcETy->isSized() && TD->getTypeStoreSize(SrcETy) == Size) {
|
|
// The SrcETy might be something like {{{double}}} or [1 x double]. Rip
|
|
// down through these levels if so.
|
|
while (!SrcETy->isSingleValueType()) {
|
|
if (const StructType *STy = dyn_cast<StructType>(SrcETy)) {
|
|
if (STy->getNumElements() == 1)
|
|
SrcETy = STy->getElementType(0);
|
|
else
|
|
break;
|
|
} else if (const ArrayType *ATy = dyn_cast<ArrayType>(SrcETy)) {
|
|
if (ATy->getNumElements() == 1)
|
|
SrcETy = ATy->getElementType();
|
|
else
|
|
break;
|
|
} else
|
|
break;
|
|
}
|
|
|
|
if (SrcETy->isSingleValueType())
|
|
NewPtrTy = PointerType::getUnqual(SrcETy);
|
|
}
|
|
}
|
|
|
|
|
|
// If the memcpy/memmove provides better alignment info than we can
|
|
// infer, use it.
|
|
SrcAlign = std::max(SrcAlign, CopyAlign);
|
|
DstAlign = std::max(DstAlign, CopyAlign);
|
|
|
|
Value *Src = InsertBitCastBefore(MI->getOperand(2), NewPtrTy, *MI);
|
|
Value *Dest = InsertBitCastBefore(MI->getOperand(1), NewPtrTy, *MI);
|
|
Instruction *L = new LoadInst(Src, "tmp", false, SrcAlign);
|
|
InsertNewInstBefore(L, *MI);
|
|
InsertNewInstBefore(new StoreInst(L, Dest, false, DstAlign), *MI);
|
|
|
|
// Set the size of the copy to 0, it will be deleted on the next iteration.
|
|
MI->setOperand(3, Constant::getNullValue(MemOpLength->getType()));
|
|
return MI;
|
|
}
|
|
|
|
Instruction *InstCombiner::SimplifyMemSet(MemSetInst *MI) {
|
|
unsigned Alignment = GetOrEnforceKnownAlignment(MI->getDest());
|
|
if (MI->getAlignment()->getZExtValue() < Alignment) {
|
|
MI->setAlignment(ConstantInt::get(Type::Int32Ty, Alignment));
|
|
return MI;
|
|
}
|
|
|
|
// Extract the length and alignment and fill if they are constant.
|
|
ConstantInt *LenC = dyn_cast<ConstantInt>(MI->getLength());
|
|
ConstantInt *FillC = dyn_cast<ConstantInt>(MI->getValue());
|
|
if (!LenC || !FillC || FillC->getType() != Type::Int8Ty)
|
|
return 0;
|
|
uint64_t Len = LenC->getZExtValue();
|
|
Alignment = MI->getAlignment()->getZExtValue();
|
|
|
|
// If the length is zero, this is a no-op
|
|
if (Len == 0) return MI; // memset(d,c,0,a) -> noop
|
|
|
|
// memset(s,c,n) -> store s, c (for n=1,2,4,8)
|
|
if (Len <= 8 && isPowerOf2_32((uint32_t)Len)) {
|
|
const Type *ITy = IntegerType::get(Len*8); // n=1 -> i8.
|
|
|
|
Value *Dest = MI->getDest();
|
|
Dest = InsertBitCastBefore(Dest, PointerType::getUnqual(ITy), *MI);
|
|
|
|
// Alignment 0 is identity for alignment 1 for memset, but not store.
|
|
if (Alignment == 0) Alignment = 1;
|
|
|
|
// Extract the fill value and store.
|
|
uint64_t Fill = FillC->getZExtValue()*0x0101010101010101ULL;
|
|
InsertNewInstBefore(new StoreInst(ConstantInt::get(ITy, Fill), Dest, false,
|
|
Alignment), *MI);
|
|
|
|
// Set the size of the copy to 0, it will be deleted on the next iteration.
|
|
MI->setLength(Constant::getNullValue(LenC->getType()));
|
|
return MI;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
/// visitCallInst - CallInst simplification. This mostly only handles folding
|
|
/// of intrinsic instructions. For normal calls, it allows visitCallSite to do
|
|
/// the heavy lifting.
|
|
///
|
|
Instruction *InstCombiner::visitCallInst(CallInst &CI) {
|
|
IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI);
|
|
if (!II) return visitCallSite(&CI);
|
|
|
|
// Intrinsics cannot occur in an invoke, so handle them here instead of in
|
|
// visitCallSite.
|
|
if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) {
|
|
bool Changed = false;
|
|
|
|
// memmove/cpy/set of zero bytes is a noop.
|
|
if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
|
|
if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
|
|
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
|
|
if (CI->getZExtValue() == 1) {
|
|
// Replace the instruction with just byte operations. We would
|
|
// transform other cases to loads/stores, but we don't know if
|
|
// alignment is sufficient.
|
|
}
|
|
}
|
|
|
|
// If we have a memmove and the source operation is a constant global,
|
|
// then the source and dest pointers can't alias, so we can change this
|
|
// into a call to memcpy.
|
|
if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI)) {
|
|
if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource()))
|
|
if (GVSrc->isConstant()) {
|
|
Module *M = CI.getParent()->getParent()->getParent();
|
|
Intrinsic::ID MemCpyID = Intrinsic::memcpy;
|
|
const Type *Tys[1];
|
|
Tys[0] = CI.getOperand(3)->getType();
|
|
CI.setOperand(0,
|
|
Intrinsic::getDeclaration(M, MemCpyID, Tys, 1));
|
|
Changed = true;
|
|
}
|
|
|
|
// memmove(x,x,size) -> noop.
|
|
if (MMI->getSource() == MMI->getDest())
|
|
return EraseInstFromFunction(CI);
|
|
}
|
|
|
|
// If we can determine a pointer alignment that is bigger than currently
|
|
// set, update the alignment.
|
|
if (isa<MemCpyInst>(MI) || isa<MemMoveInst>(MI)) {
|
|
if (Instruction *I = SimplifyMemTransfer(MI))
|
|
return I;
|
|
} else if (MemSetInst *MSI = dyn_cast<MemSetInst>(MI)) {
|
|
if (Instruction *I = SimplifyMemSet(MSI))
|
|
return I;
|
|
}
|
|
|
|
if (Changed) return II;
|
|
}
|
|
|
|
switch (II->getIntrinsicID()) {
|
|
default: break;
|
|
case Intrinsic::bswap:
|
|
// bswap(bswap(x)) -> x
|
|
if (IntrinsicInst *Operand = dyn_cast<IntrinsicInst>(II->getOperand(1)))
|
|
if (Operand->getIntrinsicID() == Intrinsic::bswap)
|
|
return ReplaceInstUsesWith(CI, Operand->getOperand(1));
|
|
break;
|
|
case Intrinsic::ppc_altivec_lvx:
|
|
case Intrinsic::ppc_altivec_lvxl:
|
|
case Intrinsic::x86_sse_loadu_ps:
|
|
case Intrinsic::x86_sse2_loadu_pd:
|
|
case Intrinsic::x86_sse2_loadu_dq:
|
|
// Turn PPC lvx -> load if the pointer is known aligned.
|
|
// Turn X86 loadups -> load if the pointer is known aligned.
|
|
if (GetOrEnforceKnownAlignment(II->getOperand(1), 16) >= 16) {
|
|
Value *Ptr = InsertBitCastBefore(II->getOperand(1),
|
|
PointerType::getUnqual(II->getType()),
|
|
CI);
|
|
return new LoadInst(Ptr);
|
|
}
|
|
break;
|
|
case Intrinsic::ppc_altivec_stvx:
|
|
case Intrinsic::ppc_altivec_stvxl:
|
|
// Turn stvx -> store if the pointer is known aligned.
|
|
if (GetOrEnforceKnownAlignment(II->getOperand(2), 16) >= 16) {
|
|
const Type *OpPtrTy =
|
|
PointerType::getUnqual(II->getOperand(1)->getType());
|
|
Value *Ptr = InsertBitCastBefore(II->getOperand(2), OpPtrTy, CI);
|
|
return new StoreInst(II->getOperand(1), Ptr);
|
|
}
|
|
break;
|
|
case Intrinsic::x86_sse_storeu_ps:
|
|
case Intrinsic::x86_sse2_storeu_pd:
|
|
case Intrinsic::x86_sse2_storeu_dq:
|
|
// Turn X86 storeu -> store if the pointer is known aligned.
|
|
if (GetOrEnforceKnownAlignment(II->getOperand(1), 16) >= 16) {
|
|
const Type *OpPtrTy =
|
|
PointerType::getUnqual(II->getOperand(2)->getType());
|
|
Value *Ptr = InsertBitCastBefore(II->getOperand(1), OpPtrTy, CI);
|
|
return new StoreInst(II->getOperand(2), Ptr);
|
|
}
|
|
break;
|
|
|
|
case Intrinsic::x86_sse_cvttss2si: {
|
|
// These intrinsics only demands the 0th element of its input vector. If
|
|
// we can simplify the input based on that, do so now.
|
|
unsigned VWidth =
|
|
cast<VectorType>(II->getOperand(1)->getType())->getNumElements();
|
|
APInt DemandedElts(VWidth, 1);
|
|
APInt UndefElts(VWidth, 0);
|
|
if (Value *V = SimplifyDemandedVectorElts(II->getOperand(1), DemandedElts,
|
|
UndefElts)) {
|
|
II->setOperand(1, V);
|
|
return II;
|
|
}
|
|
break;
|
|
}
|
|
|
|
case Intrinsic::ppc_altivec_vperm:
|
|
// Turn vperm(V1,V2,mask) -> shuffle(V1,V2,mask) if mask is a constant.
|
|
if (ConstantVector *Mask = dyn_cast<ConstantVector>(II->getOperand(3))) {
|
|
assert(Mask->getNumOperands() == 16 && "Bad type for intrinsic!");
|
|
|
|
// Check that all of the elements are integer constants or undefs.
|
|
bool AllEltsOk = true;
|
|
for (unsigned i = 0; i != 16; ++i) {
|
|
if (!isa<ConstantInt>(Mask->getOperand(i)) &&
|
|
!isa<UndefValue>(Mask->getOperand(i))) {
|
|
AllEltsOk = false;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (AllEltsOk) {
|
|
// Cast the input vectors to byte vectors.
|
|
Value *Op0 =InsertBitCastBefore(II->getOperand(1),Mask->getType(),CI);
|
|
Value *Op1 =InsertBitCastBefore(II->getOperand(2),Mask->getType(),CI);
|
|
Value *Result = UndefValue::get(Op0->getType());
|
|
|
|
// Only extract each element once.
|
|
Value *ExtractedElts[32];
|
|
memset(ExtractedElts, 0, sizeof(ExtractedElts));
|
|
|
|
for (unsigned i = 0; i != 16; ++i) {
|
|
if (isa<UndefValue>(Mask->getOperand(i)))
|
|
continue;
|
|
unsigned Idx=cast<ConstantInt>(Mask->getOperand(i))->getZExtValue();
|
|
Idx &= 31; // Match the hardware behavior.
|
|
|
|
if (ExtractedElts[Idx] == 0) {
|
|
Instruction *Elt =
|
|
new ExtractElementInst(Idx < 16 ? Op0 : Op1, Idx&15, "tmp");
|
|
InsertNewInstBefore(Elt, CI);
|
|
ExtractedElts[Idx] = Elt;
|
|
}
|
|
|
|
// Insert this value into the result vector.
|
|
Result = InsertElementInst::Create(Result, ExtractedElts[Idx],
|
|
i, "tmp");
|
|
InsertNewInstBefore(cast<Instruction>(Result), CI);
|
|
}
|
|
return CastInst::Create(Instruction::BitCast, Result, CI.getType());
|
|
}
|
|
}
|
|
break;
|
|
|
|
case Intrinsic::stackrestore: {
|
|
// If the save is right next to the restore, remove the restore. This can
|
|
// happen when variable allocas are DCE'd.
|
|
if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getOperand(1))) {
|
|
if (SS->getIntrinsicID() == Intrinsic::stacksave) {
|
|
BasicBlock::iterator BI = SS;
|
|
if (&*++BI == II)
|
|
return EraseInstFromFunction(CI);
|
|
}
|
|
}
|
|
|
|
// Scan down this block to see if there is another stack restore in the
|
|
// same block without an intervening call/alloca.
|
|
BasicBlock::iterator BI = II;
|
|
TerminatorInst *TI = II->getParent()->getTerminator();
|
|
bool CannotRemove = false;
|
|
for (++BI; &*BI != TI; ++BI) {
|
|
if (isa<AllocaInst>(BI)) {
|
|
CannotRemove = true;
|
|
break;
|
|
}
|
|
if (CallInst *BCI = dyn_cast<CallInst>(BI)) {
|
|
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(BCI)) {
|
|
// If there is a stackrestore below this one, remove this one.
|
|
if (II->getIntrinsicID() == Intrinsic::stackrestore)
|
|
return EraseInstFromFunction(CI);
|
|
// Otherwise, ignore the intrinsic.
|
|
} else {
|
|
// If we found a non-intrinsic call, we can't remove the stack
|
|
// restore.
|
|
CannotRemove = true;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
// If the stack restore is in a return/unwind block and if there are no
|
|
// allocas or calls between the restore and the return, nuke the restore.
|
|
if (!CannotRemove && (isa<ReturnInst>(TI) || isa<UnwindInst>(TI)))
|
|
return EraseInstFromFunction(CI);
|
|
break;
|
|
}
|
|
}
|
|
|
|
return visitCallSite(II);
|
|
}
|
|
|
|
// InvokeInst simplification
|
|
//
|
|
Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
|
|
return visitCallSite(&II);
|
|
}
|
|
|
|
/// isSafeToEliminateVarargsCast - If this cast does not affect the value
|
|
/// passed through the varargs area, we can eliminate the use of the cast.
|
|
static bool isSafeToEliminateVarargsCast(const CallSite CS,
|
|
const CastInst * const CI,
|
|
const TargetData * const TD,
|
|
const int ix) {
|
|
if (!CI->isLosslessCast())
|
|
return false;
|
|
|
|
// The size of ByVal arguments is derived from the type, so we
|
|
// can't change to a type with a different size. If the size were
|
|
// passed explicitly we could avoid this check.
|
|
if (!CS.paramHasAttr(ix, Attribute::ByVal))
|
|
return true;
|
|
|
|
const Type* SrcTy =
|
|
cast<PointerType>(CI->getOperand(0)->getType())->getElementType();
|
|
const Type* DstTy = cast<PointerType>(CI->getType())->getElementType();
|
|
if (!SrcTy->isSized() || !DstTy->isSized())
|
|
return false;
|
|
if (TD->getTypePaddedSize(SrcTy) != TD->getTypePaddedSize(DstTy))
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
// visitCallSite - Improvements for call and invoke instructions.
|
|
//
|
|
Instruction *InstCombiner::visitCallSite(CallSite CS) {
|
|
bool Changed = false;
|
|
|
|
// If the callee is a constexpr cast of a function, attempt to move the cast
|
|
// to the arguments of the call/invoke.
|
|
if (transformConstExprCastCall(CS)) return 0;
|
|
|
|
Value *Callee = CS.getCalledValue();
|
|
|
|
if (Function *CalleeF = dyn_cast<Function>(Callee))
|
|
if (CalleeF->getCallingConv() != CS.getCallingConv()) {
|
|
Instruction *OldCall = CS.getInstruction();
|
|
// If the call and callee calling conventions don't match, this call must
|
|
// be unreachable, as the call is undefined.
|
|
new StoreInst(ConstantInt::getTrue(),
|
|
UndefValue::get(PointerType::getUnqual(Type::Int1Ty)),
|
|
OldCall);
|
|
if (!OldCall->use_empty())
|
|
OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType()));
|
|
if (isa<CallInst>(OldCall)) // Not worth removing an invoke here.
|
|
return EraseInstFromFunction(*OldCall);
|
|
return 0;
|
|
}
|
|
|
|
if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
|
|
// This instruction is not reachable, just remove it. We insert a store to
|
|
// undef so that we know that this code is not reachable, despite the fact
|
|
// that we can't modify the CFG here.
|
|
new StoreInst(ConstantInt::getTrue(),
|
|
UndefValue::get(PointerType::getUnqual(Type::Int1Ty)),
|
|
CS.getInstruction());
|
|
|
|
if (!CS.getInstruction()->use_empty())
|
|
CS.getInstruction()->
|
|
replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType()));
|
|
|
|
if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
|
|
// Don't break the CFG, insert a dummy cond branch.
|
|
BranchInst::Create(II->getNormalDest(), II->getUnwindDest(),
|
|
ConstantInt::getTrue(), II);
|
|
}
|
|
return EraseInstFromFunction(*CS.getInstruction());
|
|
}
|
|
|
|
if (BitCastInst *BC = dyn_cast<BitCastInst>(Callee))
|
|
if (IntrinsicInst *In = dyn_cast<IntrinsicInst>(BC->getOperand(0)))
|
|
if (In->getIntrinsicID() == Intrinsic::init_trampoline)
|
|
return transformCallThroughTrampoline(CS);
|
|
|
|
const PointerType *PTy = cast<PointerType>(Callee->getType());
|
|
const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
|
|
if (FTy->isVarArg()) {
|
|
int ix = FTy->getNumParams() + (isa<InvokeInst>(Callee) ? 3 : 1);
|
|
// See if we can optimize any arguments passed through the varargs area of
|
|
// the call.
|
|
for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(),
|
|
E = CS.arg_end(); I != E; ++I, ++ix) {
|
|
CastInst *CI = dyn_cast<CastInst>(*I);
|
|
if (CI && isSafeToEliminateVarargsCast(CS, CI, TD, ix)) {
|
|
*I = CI->getOperand(0);
|
|
Changed = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (isa<InlineAsm>(Callee) && !CS.doesNotThrow()) {
|
|
// Inline asm calls cannot throw - mark them 'nounwind'.
|
|
CS.setDoesNotThrow();
|
|
Changed = true;
|
|
}
|
|
|
|
return Changed ? CS.getInstruction() : 0;
|
|
}
|
|
|
|
// transformConstExprCastCall - If the callee is a constexpr cast of a function,
|
|
// attempt to move the cast to the arguments of the call/invoke.
|
|
//
|
|
bool InstCombiner::transformConstExprCastCall(CallSite CS) {
|
|
if (!isa<ConstantExpr>(CS.getCalledValue())) return false;
|
|
ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue());
|
|
if (CE->getOpcode() != Instruction::BitCast ||
|
|
!isa<Function>(CE->getOperand(0)))
|
|
return false;
|
|
Function *Callee = cast<Function>(CE->getOperand(0));
|
|
Instruction *Caller = CS.getInstruction();
|
|
const AttrListPtr &CallerPAL = CS.getAttributes();
|
|
|
|
// Okay, this is a cast from a function to a different type. Unless doing so
|
|
// would cause a type conversion of one of our arguments, change this call to
|
|
// be a direct call with arguments casted to the appropriate types.
|
|
//
|
|
const FunctionType *FT = Callee->getFunctionType();
|
|
const Type *OldRetTy = Caller->getType();
|
|
const Type *NewRetTy = FT->getReturnType();
|
|
|
|
if (isa<StructType>(NewRetTy))
|
|
return false; // TODO: Handle multiple return values.
|
|
|
|
// Check to see if we are changing the return type...
|
|
if (OldRetTy != NewRetTy) {
|
|
if (Callee->isDeclaration() &&
|
|
// Conversion is ok if changing from one pointer type to another or from
|
|
// a pointer to an integer of the same size.
|
|
!((isa<PointerType>(OldRetTy) || OldRetTy == TD->getIntPtrType()) &&
|
|
(isa<PointerType>(NewRetTy) || NewRetTy == TD->getIntPtrType())))
|
|
return false; // Cannot transform this return value.
|
|
|
|
if (!Caller->use_empty() &&
|
|
// void -> non-void is handled specially
|
|
NewRetTy != Type::VoidTy && !CastInst::isCastable(NewRetTy, OldRetTy))
|
|
return false; // Cannot transform this return value.
|
|
|
|
if (!CallerPAL.isEmpty() && !Caller->use_empty()) {
|
|
Attributes RAttrs = CallerPAL.getRetAttributes();
|
|
if (RAttrs & Attribute::typeIncompatible(NewRetTy))
|
|
return false; // Attribute not compatible with transformed value.
|
|
}
|
|
|
|
// If the callsite is an invoke instruction, and the return value is used by
|
|
// a PHI node in a successor, we cannot change the return type of the call
|
|
// because there is no place to put the cast instruction (without breaking
|
|
// the critical edge). Bail out in this case.
|
|
if (!Caller->use_empty())
|
|
if (InvokeInst *II = dyn_cast<InvokeInst>(Caller))
|
|
for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
|
|
UI != E; ++UI)
|
|
if (PHINode *PN = dyn_cast<PHINode>(*UI))
|
|
if (PN->getParent() == II->getNormalDest() ||
|
|
PN->getParent() == II->getUnwindDest())
|
|
return false;
|
|
}
|
|
|
|
unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin());
|
|
unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs);
|
|
|
|
CallSite::arg_iterator AI = CS.arg_begin();
|
|
for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) {
|
|
const Type *ParamTy = FT->getParamType(i);
|
|
const Type *ActTy = (*AI)->getType();
|
|
|
|
if (!CastInst::isCastable(ActTy, ParamTy))
|
|
return false; // Cannot transform this parameter value.
|
|
|
|
if (CallerPAL.getParamAttributes(i + 1)
|
|
& Attribute::typeIncompatible(ParamTy))
|
|
return false; // Attribute not compatible with transformed value.
|
|
|
|
// Converting from one pointer type to another or between a pointer and an
|
|
// integer of the same size is safe even if we do not have a body.
|
|
bool isConvertible = ActTy == ParamTy ||
|
|
((isa<PointerType>(ParamTy) || ParamTy == TD->getIntPtrType()) &&
|
|
(isa<PointerType>(ActTy) || ActTy == TD->getIntPtrType()));
|
|
if (Callee->isDeclaration() && !isConvertible) return false;
|
|
}
|
|
|
|
if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
|
|
Callee->isDeclaration())
|
|
return false; // Do not delete arguments unless we have a function body.
|
|
|
|
if (FT->getNumParams() < NumActualArgs && FT->isVarArg() &&
|
|
!CallerPAL.isEmpty())
|
|
// In this case we have more arguments than the new function type, but we
|
|
// won't be dropping them. Check that these extra arguments have attributes
|
|
// that are compatible with being a vararg call argument.
|
|
for (unsigned i = CallerPAL.getNumSlots(); i; --i) {
|
|
if (CallerPAL.getSlot(i - 1).Index <= FT->getNumParams())
|
|
break;
|
|
Attributes PAttrs = CallerPAL.getSlot(i - 1).Attrs;
|
|
if (PAttrs & Attribute::VarArgsIncompatible)
|
|
return false;
|
|
}
|
|
|
|
// Okay, we decided that this is a safe thing to do: go ahead and start
|
|
// inserting cast instructions as necessary...
|
|
std::vector<Value*> Args;
|
|
Args.reserve(NumActualArgs);
|
|
SmallVector<AttributeWithIndex, 8> attrVec;
|
|
attrVec.reserve(NumCommonArgs);
|
|
|
|
// Get any return attributes.
|
|
Attributes RAttrs = CallerPAL.getRetAttributes();
|
|
|
|
// If the return value is not being used, the type may not be compatible
|
|
// with the existing attributes. Wipe out any problematic attributes.
|
|
RAttrs &= ~Attribute::typeIncompatible(NewRetTy);
|
|
|
|
// Add the new return attributes.
|
|
if (RAttrs)
|
|
attrVec.push_back(AttributeWithIndex::get(0, RAttrs));
|
|
|
|
AI = CS.arg_begin();
|
|
for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) {
|
|
const Type *ParamTy = FT->getParamType(i);
|
|
if ((*AI)->getType() == ParamTy) {
|
|
Args.push_back(*AI);
|
|
} else {
|
|
Instruction::CastOps opcode = CastInst::getCastOpcode(*AI,
|
|
false, ParamTy, false);
|
|
CastInst *NewCast = CastInst::Create(opcode, *AI, ParamTy, "tmp");
|
|
Args.push_back(InsertNewInstBefore(NewCast, *Caller));
|
|
}
|
|
|
|
// Add any parameter attributes.
|
|
if (Attributes PAttrs = CallerPAL.getParamAttributes(i + 1))
|
|
attrVec.push_back(AttributeWithIndex::get(i + 1, PAttrs));
|
|
}
|
|
|
|
// If the function takes more arguments than the call was taking, add them
|
|
// now...
|
|
for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i)
|
|
Args.push_back(Constant::getNullValue(FT->getParamType(i)));
|
|
|
|
// If we are removing arguments to the function, emit an obnoxious warning...
|
|
if (FT->getNumParams() < NumActualArgs) {
|
|
if (!FT->isVarArg()) {
|
|
cerr << "WARNING: While resolving call to function '"
|
|
<< Callee->getName() << "' arguments were dropped!\n";
|
|
} else {
|
|
// Add all of the arguments in their promoted form to the arg list...
|
|
for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) {
|
|
const Type *PTy = getPromotedType((*AI)->getType());
|
|
if (PTy != (*AI)->getType()) {
|
|
// Must promote to pass through va_arg area!
|
|
Instruction::CastOps opcode = CastInst::getCastOpcode(*AI, false,
|
|
PTy, false);
|
|
Instruction *Cast = CastInst::Create(opcode, *AI, PTy, "tmp");
|
|
InsertNewInstBefore(Cast, *Caller);
|
|
Args.push_back(Cast);
|
|
} else {
|
|
Args.push_back(*AI);
|
|
}
|
|
|
|
// Add any parameter attributes.
|
|
if (Attributes PAttrs = CallerPAL.getParamAttributes(i + 1))
|
|
attrVec.push_back(AttributeWithIndex::get(i + 1, PAttrs));
|
|
}
|
|
}
|
|
}
|
|
|
|
if (Attributes FnAttrs = CallerPAL.getFnAttributes())
|
|
attrVec.push_back(AttributeWithIndex::get(~0, FnAttrs));
|
|
|
|
if (NewRetTy == Type::VoidTy)
|
|
Caller->setName(""); // Void type should not have a name.
|
|
|
|
const AttrListPtr &NewCallerPAL = AttrListPtr::get(attrVec.begin(),attrVec.end());
|
|
|
|
Instruction *NC;
|
|
if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
|
|
NC = InvokeInst::Create(Callee, II->getNormalDest(), II->getUnwindDest(),
|
|
Args.begin(), Args.end(),
|
|
Caller->getName(), Caller);
|
|
cast<InvokeInst>(NC)->setCallingConv(II->getCallingConv());
|
|
cast<InvokeInst>(NC)->setAttributes(NewCallerPAL);
|
|
} else {
|
|
NC = CallInst::Create(Callee, Args.begin(), Args.end(),
|
|
Caller->getName(), Caller);
|
|
CallInst *CI = cast<CallInst>(Caller);
|
|
if (CI->isTailCall())
|
|
cast<CallInst>(NC)->setTailCall();
|
|
cast<CallInst>(NC)->setCallingConv(CI->getCallingConv());
|
|
cast<CallInst>(NC)->setAttributes(NewCallerPAL);
|
|
}
|
|
|
|
// Insert a cast of the return type as necessary.
|
|
Value *NV = NC;
|
|
if (OldRetTy != NV->getType() && !Caller->use_empty()) {
|
|
if (NV->getType() != Type::VoidTy) {
|
|
Instruction::CastOps opcode = CastInst::getCastOpcode(NC, false,
|
|
OldRetTy, false);
|
|
NV = NC = CastInst::Create(opcode, NC, OldRetTy, "tmp");
|
|
|
|
// If this is an invoke instruction, we should insert it after the first
|
|
// non-phi, instruction in the normal successor block.
|
|
if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
|
|
BasicBlock::iterator I = II->getNormalDest()->getFirstNonPHI();
|
|
InsertNewInstBefore(NC, *I);
|
|
} else {
|
|
// Otherwise, it's a call, just insert cast right after the call instr
|
|
InsertNewInstBefore(NC, *Caller);
|
|
}
|
|
AddUsersToWorkList(*Caller);
|
|
} else {
|
|
NV = UndefValue::get(Caller->getType());
|
|
}
|
|
}
|
|
|
|
if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
|
|
Caller->replaceAllUsesWith(NV);
|
|
Caller->eraseFromParent();
|
|
RemoveFromWorkList(Caller);
|
|
return true;
|
|
}
|
|
|
|
// transformCallThroughTrampoline - Turn a call to a function created by the
|
|
// init_trampoline intrinsic into a direct call to the underlying function.
|
|
//
|
|
Instruction *InstCombiner::transformCallThroughTrampoline(CallSite CS) {
|
|
Value *Callee = CS.getCalledValue();
|
|
const PointerType *PTy = cast<PointerType>(Callee->getType());
|
|
const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
|
|
const AttrListPtr &Attrs = CS.getAttributes();
|
|
|
|
// If the call already has the 'nest' attribute somewhere then give up -
|
|
// otherwise 'nest' would occur twice after splicing in the chain.
|
|
if (Attrs.hasAttrSomewhere(Attribute::Nest))
|
|
return 0;
|
|
|
|
IntrinsicInst *Tramp =
|
|
cast<IntrinsicInst>(cast<BitCastInst>(Callee)->getOperand(0));
|
|
|
|
Function *NestF = cast<Function>(Tramp->getOperand(2)->stripPointerCasts());
|
|
const PointerType *NestFPTy = cast<PointerType>(NestF->getType());
|
|
const FunctionType *NestFTy = cast<FunctionType>(NestFPTy->getElementType());
|
|
|
|
const AttrListPtr &NestAttrs = NestF->getAttributes();
|
|
if (!NestAttrs.isEmpty()) {
|
|
unsigned NestIdx = 1;
|
|
const Type *NestTy = 0;
|
|
Attributes NestAttr = Attribute::None;
|
|
|
|
// Look for a parameter marked with the 'nest' attribute.
|
|
for (FunctionType::param_iterator I = NestFTy->param_begin(),
|
|
E = NestFTy->param_end(); I != E; ++NestIdx, ++I)
|
|
if (NestAttrs.paramHasAttr(NestIdx, Attribute::Nest)) {
|
|
// Record the parameter type and any other attributes.
|
|
NestTy = *I;
|
|
NestAttr = NestAttrs.getParamAttributes(NestIdx);
|
|
break;
|
|
}
|
|
|
|
if (NestTy) {
|
|
Instruction *Caller = CS.getInstruction();
|
|
std::vector<Value*> NewArgs;
|
|
NewArgs.reserve(unsigned(CS.arg_end()-CS.arg_begin())+1);
|
|
|
|
SmallVector<AttributeWithIndex, 8> NewAttrs;
|
|
NewAttrs.reserve(Attrs.getNumSlots() + 1);
|
|
|
|
// Insert the nest argument into the call argument list, which may
|
|
// mean appending it. Likewise for attributes.
|
|
|
|
// Add any result attributes.
|
|
if (Attributes Attr = Attrs.getRetAttributes())
|
|
NewAttrs.push_back(AttributeWithIndex::get(0, Attr));
|
|
|
|
{
|
|
unsigned Idx = 1;
|
|
CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
|
|
do {
|
|
if (Idx == NestIdx) {
|
|
// Add the chain argument and attributes.
|
|
Value *NestVal = Tramp->getOperand(3);
|
|
if (NestVal->getType() != NestTy)
|
|
NestVal = new BitCastInst(NestVal, NestTy, "nest", Caller);
|
|
NewArgs.push_back(NestVal);
|
|
NewAttrs.push_back(AttributeWithIndex::get(NestIdx, NestAttr));
|
|
}
|
|
|
|
if (I == E)
|
|
break;
|
|
|
|
// Add the original argument and attributes.
|
|
NewArgs.push_back(*I);
|
|
if (Attributes Attr = Attrs.getParamAttributes(Idx))
|
|
NewAttrs.push_back
|
|
(AttributeWithIndex::get(Idx + (Idx >= NestIdx), Attr));
|
|
|
|
++Idx, ++I;
|
|
} while (1);
|
|
}
|
|
|
|
// Add any function attributes.
|
|
if (Attributes Attr = Attrs.getFnAttributes())
|
|
NewAttrs.push_back(AttributeWithIndex::get(~0, Attr));
|
|
|
|
// The trampoline may have been bitcast to a bogus type (FTy).
|
|
// Handle this by synthesizing a new function type, equal to FTy
|
|
// with the chain parameter inserted.
|
|
|
|
std::vector<const Type*> NewTypes;
|
|
NewTypes.reserve(FTy->getNumParams()+1);
|
|
|
|
// Insert the chain's type into the list of parameter types, which may
|
|
// mean appending it.
|
|
{
|
|
unsigned Idx = 1;
|
|
FunctionType::param_iterator I = FTy->param_begin(),
|
|
E = FTy->param_end();
|
|
|
|
do {
|
|
if (Idx == NestIdx)
|
|
// Add the chain's type.
|
|
NewTypes.push_back(NestTy);
|
|
|
|
if (I == E)
|
|
break;
|
|
|
|
// Add the original type.
|
|
NewTypes.push_back(*I);
|
|
|
|
++Idx, ++I;
|
|
} while (1);
|
|
}
|
|
|
|
// Replace the trampoline call with a direct call. Let the generic
|
|
// code sort out any function type mismatches.
|
|
FunctionType *NewFTy =
|
|
FunctionType::get(FTy->getReturnType(), NewTypes, FTy->isVarArg());
|
|
Constant *NewCallee = NestF->getType() == PointerType::getUnqual(NewFTy) ?
|
|
NestF : ConstantExpr::getBitCast(NestF, PointerType::getUnqual(NewFTy));
|
|
const AttrListPtr &NewPAL = AttrListPtr::get(NewAttrs.begin(),NewAttrs.end());
|
|
|
|
Instruction *NewCaller;
|
|
if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
|
|
NewCaller = InvokeInst::Create(NewCallee,
|
|
II->getNormalDest(), II->getUnwindDest(),
|
|
NewArgs.begin(), NewArgs.end(),
|
|
Caller->getName(), Caller);
|
|
cast<InvokeInst>(NewCaller)->setCallingConv(II->getCallingConv());
|
|
cast<InvokeInst>(NewCaller)->setAttributes(NewPAL);
|
|
} else {
|
|
NewCaller = CallInst::Create(NewCallee, NewArgs.begin(), NewArgs.end(),
|
|
Caller->getName(), Caller);
|
|
if (cast<CallInst>(Caller)->isTailCall())
|
|
cast<CallInst>(NewCaller)->setTailCall();
|
|
cast<CallInst>(NewCaller)->
|
|
setCallingConv(cast<CallInst>(Caller)->getCallingConv());
|
|
cast<CallInst>(NewCaller)->setAttributes(NewPAL);
|
|
}
|
|
if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
|
|
Caller->replaceAllUsesWith(NewCaller);
|
|
Caller->eraseFromParent();
|
|
RemoveFromWorkList(Caller);
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
// Replace the trampoline call with a direct call. Since there is no 'nest'
|
|
// parameter, there is no need to adjust the argument list. Let the generic
|
|
// code sort out any function type mismatches.
|
|
Constant *NewCallee =
|
|
NestF->getType() == PTy ? NestF : ConstantExpr::getBitCast(NestF, PTy);
|
|
CS.setCalledFunction(NewCallee);
|
|
return CS.getInstruction();
|
|
}
|
|
|
|
/// FoldPHIArgBinOpIntoPHI - If we have something like phi [add (a,b), add(c,d)]
|
|
/// and if a/b/c/d and the add's all have a single use, turn this into two phi's
|
|
/// and a single binop.
|
|
Instruction *InstCombiner::FoldPHIArgBinOpIntoPHI(PHINode &PN) {
|
|
Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
|
|
assert(isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst));
|
|
unsigned Opc = FirstInst->getOpcode();
|
|
Value *LHSVal = FirstInst->getOperand(0);
|
|
Value *RHSVal = FirstInst->getOperand(1);
|
|
|
|
const Type *LHSType = LHSVal->getType();
|
|
const Type *RHSType = RHSVal->getType();
|
|
|
|
// Scan to see if all operands are the same opcode, all have one use, and all
|
|
// kill their operands (i.e. the operands have one use).
|
|
for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) {
|
|
Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i));
|
|
if (!I || I->getOpcode() != Opc || !I->hasOneUse() ||
|
|
// Verify type of the LHS matches so we don't fold cmp's of different
|
|
// types or GEP's with different index types.
|
|
I->getOperand(0)->getType() != LHSType ||
|
|
I->getOperand(1)->getType() != RHSType)
|
|
return 0;
|
|
|
|
// If they are CmpInst instructions, check their predicates
|
|
if (Opc == Instruction::ICmp || Opc == Instruction::FCmp)
|
|
if (cast<CmpInst>(I)->getPredicate() !=
|
|
cast<CmpInst>(FirstInst)->getPredicate())
|
|
return 0;
|
|
|
|
// Keep track of which operand needs a phi node.
|
|
if (I->getOperand(0) != LHSVal) LHSVal = 0;
|
|
if (I->getOperand(1) != RHSVal) RHSVal = 0;
|
|
}
|
|
|
|
// Otherwise, this is safe to transform!
|
|
|
|
Value *InLHS = FirstInst->getOperand(0);
|
|
Value *InRHS = FirstInst->getOperand(1);
|
|
PHINode *NewLHS = 0, *NewRHS = 0;
|
|
if (LHSVal == 0) {
|
|
NewLHS = PHINode::Create(LHSType,
|
|
FirstInst->getOperand(0)->getName() + ".pn");
|
|
NewLHS->reserveOperandSpace(PN.getNumOperands()/2);
|
|
NewLHS->addIncoming(InLHS, PN.getIncomingBlock(0));
|
|
InsertNewInstBefore(NewLHS, PN);
|
|
LHSVal = NewLHS;
|
|
}
|
|
|
|
if (RHSVal == 0) {
|
|
NewRHS = PHINode::Create(RHSType,
|
|
FirstInst->getOperand(1)->getName() + ".pn");
|
|
NewRHS->reserveOperandSpace(PN.getNumOperands()/2);
|
|
NewRHS->addIncoming(InRHS, PN.getIncomingBlock(0));
|
|
InsertNewInstBefore(NewRHS, PN);
|
|
RHSVal = NewRHS;
|
|
}
|
|
|
|
// Add all operands to the new PHIs.
|
|
if (NewLHS || NewRHS) {
|
|
for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
|
|
Instruction *InInst = cast<Instruction>(PN.getIncomingValue(i));
|
|
if (NewLHS) {
|
|
Value *NewInLHS = InInst->getOperand(0);
|
|
NewLHS->addIncoming(NewInLHS, PN.getIncomingBlock(i));
|
|
}
|
|
if (NewRHS) {
|
|
Value *NewInRHS = InInst->getOperand(1);
|
|
NewRHS->addIncoming(NewInRHS, PN.getIncomingBlock(i));
|
|
}
|
|
}
|
|
}
|
|
|
|
if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
|
|
return BinaryOperator::Create(BinOp->getOpcode(), LHSVal, RHSVal);
|
|
CmpInst *CIOp = cast<CmpInst>(FirstInst);
|
|
return CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(), LHSVal,
|
|
RHSVal);
|
|
}
|
|
|
|
Instruction *InstCombiner::FoldPHIArgGEPIntoPHI(PHINode &PN) {
|
|
GetElementPtrInst *FirstInst =cast<GetElementPtrInst>(PN.getIncomingValue(0));
|
|
|
|
SmallVector<Value*, 16> FixedOperands(FirstInst->op_begin(),
|
|
FirstInst->op_end());
|
|
// This is true if all GEP bases are allocas and if all indices into them are
|
|
// constants.
|
|
bool AllBasePointersAreAllocas = true;
|
|
|
|
// Scan to see if all operands are the same opcode, all have one use, and all
|
|
// kill their operands (i.e. the operands have one use).
|
|
for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) {
|
|
GetElementPtrInst *GEP= dyn_cast<GetElementPtrInst>(PN.getIncomingValue(i));
|
|
if (!GEP || !GEP->hasOneUse() || GEP->getType() != FirstInst->getType() ||
|
|
GEP->getNumOperands() != FirstInst->getNumOperands())
|
|
return 0;
|
|
|
|
// Keep track of whether or not all GEPs are of alloca pointers.
|
|
if (AllBasePointersAreAllocas &&
|
|
(!isa<AllocaInst>(GEP->getOperand(0)) ||
|
|
!GEP->hasAllConstantIndices()))
|
|
AllBasePointersAreAllocas = false;
|
|
|
|
// Compare the operand lists.
|
|
for (unsigned op = 0, e = FirstInst->getNumOperands(); op != e; ++op) {
|
|
if (FirstInst->getOperand(op) == GEP->getOperand(op))
|
|
continue;
|
|
|
|
// Don't merge two GEPs when two operands differ (introducing phi nodes)
|
|
// if one of the PHIs has a constant for the index. The index may be
|
|
// substantially cheaper to compute for the constants, so making it a
|
|
// variable index could pessimize the path. This also handles the case
|
|
// for struct indices, which must always be constant.
|
|
if (isa<ConstantInt>(FirstInst->getOperand(op)) ||
|
|
isa<ConstantInt>(GEP->getOperand(op)))
|
|
return 0;
|
|
|
|
if (FirstInst->getOperand(op)->getType() !=GEP->getOperand(op)->getType())
|
|
return 0;
|
|
FixedOperands[op] = 0; // Needs a PHI.
|
|
}
|
|
}
|
|
|
|
// If all of the base pointers of the PHI'd GEPs are from allocas, don't
|
|
// bother doing this transformation. At best, this will just save a bit of
|
|
// offset calculation, but all the predecessors will have to materialize the
|
|
// stack address into a register anyway. We'd actually rather *clone* the
|
|
// load up into the predecessors so that we have a load of a gep of an alloca,
|
|
// which can usually all be folded into the load.
|
|
if (AllBasePointersAreAllocas)
|
|
return 0;
|
|
|
|
// Otherwise, this is safe to transform. Insert PHI nodes for each operand
|
|
// that is variable.
|
|
SmallVector<PHINode*, 16> OperandPhis(FixedOperands.size());
|
|
|
|
bool HasAnyPHIs = false;
|
|
for (unsigned i = 0, e = FixedOperands.size(); i != e; ++i) {
|
|
if (FixedOperands[i]) continue; // operand doesn't need a phi.
|
|
Value *FirstOp = FirstInst->getOperand(i);
|
|
PHINode *NewPN = PHINode::Create(FirstOp->getType(),
|
|
FirstOp->getName()+".pn");
|
|
InsertNewInstBefore(NewPN, PN);
|
|
|
|
NewPN->reserveOperandSpace(e);
|
|
NewPN->addIncoming(FirstOp, PN.getIncomingBlock(0));
|
|
OperandPhis[i] = NewPN;
|
|
FixedOperands[i] = NewPN;
|
|
HasAnyPHIs = true;
|
|
}
|
|
|
|
|
|
// Add all operands to the new PHIs.
|
|
if (HasAnyPHIs) {
|
|
for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
|
|
GetElementPtrInst *InGEP =cast<GetElementPtrInst>(PN.getIncomingValue(i));
|
|
BasicBlock *InBB = PN.getIncomingBlock(i);
|
|
|
|
for (unsigned op = 0, e = OperandPhis.size(); op != e; ++op)
|
|
if (PHINode *OpPhi = OperandPhis[op])
|
|
OpPhi->addIncoming(InGEP->getOperand(op), InBB);
|
|
}
|
|
}
|
|
|
|
Value *Base = FixedOperands[0];
|
|
return GetElementPtrInst::Create(Base, FixedOperands.begin()+1,
|
|
FixedOperands.end());
|
|
}
|
|
|
|
|
|
/// isSafeAndProfitableToSinkLoad - Return true if we know that it is safe to
|
|
/// sink the load out of the block that defines it. This means that it must be
|
|
/// obvious the value of the load is not changed from the point of the load to
|
|
/// the end of the block it is in.
|
|
///
|
|
/// Finally, it is safe, but not profitable, to sink a load targetting a
|
|
/// non-address-taken alloca. Doing so will cause us to not promote the alloca
|
|
/// to a register.
|
|
static bool isSafeAndProfitableToSinkLoad(LoadInst *L) {
|
|
BasicBlock::iterator BBI = L, E = L->getParent()->end();
|
|
|
|
for (++BBI; BBI != E; ++BBI)
|
|
if (BBI->mayWriteToMemory())
|
|
return false;
|
|
|
|
// Check for non-address taken alloca. If not address-taken already, it isn't
|
|
// profitable to do this xform.
|
|
if (AllocaInst *AI = dyn_cast<AllocaInst>(L->getOperand(0))) {
|
|
bool isAddressTaken = false;
|
|
for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
|
|
UI != E; ++UI) {
|
|
if (isa<LoadInst>(UI)) continue;
|
|
if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
|
|
// If storing TO the alloca, then the address isn't taken.
|
|
if (SI->getOperand(1) == AI) continue;
|
|
}
|
|
isAddressTaken = true;
|
|
break;
|
|
}
|
|
|
|
if (!isAddressTaken && AI->isStaticAlloca())
|
|
return false;
|
|
}
|
|
|
|
// If this load is a load from a GEP with a constant offset from an alloca,
|
|
// then we don't want to sink it. In its present form, it will be
|
|
// load [constant stack offset]. Sinking it will cause us to have to
|
|
// materialize the stack addresses in each predecessor in a register only to
|
|
// do a shared load from register in the successor.
|
|
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(L->getOperand(0)))
|
|
if (AllocaInst *AI = dyn_cast<AllocaInst>(GEP->getOperand(0)))
|
|
if (AI->isStaticAlloca() && GEP->hasAllConstantIndices())
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
|
|
// FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary"
|
|
// operator and they all are only used by the PHI, PHI together their
|
|
// inputs, and do the operation once, to the result of the PHI.
|
|
Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
|
|
Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0));
|
|
|
|
// Scan the instruction, looking for input operations that can be folded away.
|
|
// If all input operands to the phi are the same instruction (e.g. a cast from
|
|
// the same type or "+42") we can pull the operation through the PHI, reducing
|
|
// code size and simplifying code.
|
|
Constant *ConstantOp = 0;
|
|
const Type *CastSrcTy = 0;
|
|
bool isVolatile = false;
|
|
if (isa<CastInst>(FirstInst)) {
|
|
CastSrcTy = FirstInst->getOperand(0)->getType();
|
|
} else if (isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst)) {
|
|
// Can fold binop, compare or shift here if the RHS is a constant,
|
|
// otherwise call FoldPHIArgBinOpIntoPHI.
|
|
ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
|
|
if (ConstantOp == 0)
|
|
return FoldPHIArgBinOpIntoPHI(PN);
|
|
} else if (LoadInst *LI = dyn_cast<LoadInst>(FirstInst)) {
|
|
isVolatile = LI->isVolatile();
|
|
// We can't sink the load if the loaded value could be modified between the
|
|
// load and the PHI.
|
|
if (LI->getParent() != PN.getIncomingBlock(0) ||
|
|
!isSafeAndProfitableToSinkLoad(LI))
|
|
return 0;
|
|
|
|
// If the PHI is of volatile loads and the load block has multiple
|
|
// successors, sinking it would remove a load of the volatile value from
|
|
// the path through the other successor.
|
|
if (isVolatile &&
|
|
LI->getParent()->getTerminator()->getNumSuccessors() != 1)
|
|
return 0;
|
|
|
|
} else if (isa<GetElementPtrInst>(FirstInst)) {
|
|
return FoldPHIArgGEPIntoPHI(PN);
|
|
} else {
|
|
return 0; // Cannot fold this operation.
|
|
}
|
|
|
|
// Check to see if all arguments are the same operation.
|
|
for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
|
|
if (!isa<Instruction>(PN.getIncomingValue(i))) return 0;
|
|
Instruction *I = cast<Instruction>(PN.getIncomingValue(i));
|
|
if (!I->hasOneUse() || !I->isSameOperationAs(FirstInst))
|
|
return 0;
|
|
if (CastSrcTy) {
|
|
if (I->getOperand(0)->getType() != CastSrcTy)
|
|
return 0; // Cast operation must match.
|
|
} else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
|
|
// We can't sink the load if the loaded value could be modified between
|
|
// the load and the PHI.
|
|
if (LI->isVolatile() != isVolatile ||
|
|
LI->getParent() != PN.getIncomingBlock(i) ||
|
|
!isSafeAndProfitableToSinkLoad(LI))
|
|
return 0;
|
|
|
|
// If the PHI is of volatile loads and the load block has multiple
|
|
// successors, sinking it would remove a load of the volatile value from
|
|
// the path through the other successor.
|
|
if (isVolatile &&
|
|
LI->getParent()->getTerminator()->getNumSuccessors() != 1)
|
|
return 0;
|
|
|
|
} else if (I->getOperand(1) != ConstantOp) {
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
// Okay, they are all the same operation. Create a new PHI node of the
|
|
// correct type, and PHI together all of the LHS's of the instructions.
|
|
PHINode *NewPN = PHINode::Create(FirstInst->getOperand(0)->getType(),
|
|
PN.getName()+".in");
|
|
NewPN->reserveOperandSpace(PN.getNumOperands()/2);
|
|
|
|
Value *InVal = FirstInst->getOperand(0);
|
|
NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
|
|
|
|
// Add all operands to the new PHI.
|
|
for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
|
|
Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0);
|
|
if (NewInVal != InVal)
|
|
InVal = 0;
|
|
NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
|
|
}
|
|
|
|
Value *PhiVal;
|
|
if (InVal) {
|
|
// The new PHI unions all of the same values together. This is really
|
|
// common, so we handle it intelligently here for compile-time speed.
|
|
PhiVal = InVal;
|
|
delete NewPN;
|
|
} else {
|
|
InsertNewInstBefore(NewPN, PN);
|
|
PhiVal = NewPN;
|
|
}
|
|
|
|
// Insert and return the new operation.
|
|
if (CastInst* FirstCI = dyn_cast<CastInst>(FirstInst))
|
|
return CastInst::Create(FirstCI->getOpcode(), PhiVal, PN.getType());
|
|
if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
|
|
return BinaryOperator::Create(BinOp->getOpcode(), PhiVal, ConstantOp);
|
|
if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst))
|
|
return CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(),
|
|
PhiVal, ConstantOp);
|
|
assert(isa<LoadInst>(FirstInst) && "Unknown operation");
|
|
|
|
// If this was a volatile load that we are merging, make sure to loop through
|
|
// and mark all the input loads as non-volatile. If we don't do this, we will
|
|
// insert a new volatile load and the old ones will not be deletable.
|
|
if (isVolatile)
|
|
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
|
|
cast<LoadInst>(PN.getIncomingValue(i))->setVolatile(false);
|
|
|
|
return new LoadInst(PhiVal, "", isVolatile);
|
|
}
|
|
|
|
/// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
|
|
/// that is dead.
|
|
static bool DeadPHICycle(PHINode *PN,
|
|
SmallPtrSet<PHINode*, 16> &PotentiallyDeadPHIs) {
|
|
if (PN->use_empty()) return true;
|
|
if (!PN->hasOneUse()) return false;
|
|
|
|
// Remember this node, and if we find the cycle, return.
|
|
if (!PotentiallyDeadPHIs.insert(PN))
|
|
return true;
|
|
|
|
// Don't scan crazily complex things.
|
|
if (PotentiallyDeadPHIs.size() == 16)
|
|
return false;
|
|
|
|
if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
|
|
return DeadPHICycle(PU, PotentiallyDeadPHIs);
|
|
|
|
return false;
|
|
}
|
|
|
|
/// PHIsEqualValue - Return true if this phi node is always equal to
|
|
/// NonPhiInVal. This happens with mutually cyclic phi nodes like:
|
|
/// z = some value; x = phi (y, z); y = phi (x, z)
|
|
static bool PHIsEqualValue(PHINode *PN, Value *NonPhiInVal,
|
|
SmallPtrSet<PHINode*, 16> &ValueEqualPHIs) {
|
|
// See if we already saw this PHI node.
|
|
if (!ValueEqualPHIs.insert(PN))
|
|
return true;
|
|
|
|
// Don't scan crazily complex things.
|
|
if (ValueEqualPHIs.size() == 16)
|
|
return false;
|
|
|
|
// Scan the operands to see if they are either phi nodes or are equal to
|
|
// the value.
|
|
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
|
|
Value *Op = PN->getIncomingValue(i);
|
|
if (PHINode *OpPN = dyn_cast<PHINode>(Op)) {
|
|
if (!PHIsEqualValue(OpPN, NonPhiInVal, ValueEqualPHIs))
|
|
return false;
|
|
} else if (Op != NonPhiInVal)
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
|
|
// PHINode simplification
|
|
//
|
|
Instruction *InstCombiner::visitPHINode(PHINode &PN) {
|
|
// If LCSSA is around, don't mess with Phi nodes
|
|
if (MustPreserveLCSSA) return 0;
|
|
|
|
if (Value *V = PN.hasConstantValue())
|
|
return ReplaceInstUsesWith(PN, V);
|
|
|
|
// If all PHI operands are the same operation, pull them through the PHI,
|
|
// reducing code size.
|
|
if (isa<Instruction>(PN.getIncomingValue(0)) &&
|
|
isa<Instruction>(PN.getIncomingValue(1)) &&
|
|
cast<Instruction>(PN.getIncomingValue(0))->getOpcode() ==
|
|
cast<Instruction>(PN.getIncomingValue(1))->getOpcode() &&
|
|
// FIXME: The hasOneUse check will fail for PHIs that use the value more
|
|
// than themselves more than once.
|
|
PN.getIncomingValue(0)->hasOneUse())
|
|
if (Instruction *Result = FoldPHIArgOpIntoPHI(PN))
|
|
return Result;
|
|
|
|
// If this is a trivial cycle in the PHI node graph, remove it. Basically, if
|
|
// this PHI only has a single use (a PHI), and if that PHI only has one use (a
|
|
// PHI)... break the cycle.
|
|
if (PN.hasOneUse()) {
|
|
Instruction *PHIUser = cast<Instruction>(PN.use_back());
|
|
if (PHINode *PU = dyn_cast<PHINode>(PHIUser)) {
|
|
SmallPtrSet<PHINode*, 16> PotentiallyDeadPHIs;
|
|
PotentiallyDeadPHIs.insert(&PN);
|
|
if (DeadPHICycle(PU, PotentiallyDeadPHIs))
|
|
return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
|
|
}
|
|
|
|
// If this phi has a single use, and if that use just computes a value for
|
|
// the next iteration of a loop, delete the phi. This occurs with unused
|
|
// induction variables, e.g. "for (int j = 0; ; ++j);". Detecting this
|
|
// common case here is good because the only other things that catch this
|
|
// are induction variable analysis (sometimes) and ADCE, which is only run
|
|
// late.
|
|
if (PHIUser->hasOneUse() &&
|
|
(isa<BinaryOperator>(PHIUser) || isa<GetElementPtrInst>(PHIUser)) &&
|
|
PHIUser->use_back() == &PN) {
|
|
return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
|
|
}
|
|
}
|
|
|
|
// We sometimes end up with phi cycles that non-obviously end up being the
|
|
// same value, for example:
|
|
// z = some value; x = phi (y, z); y = phi (x, z)
|
|
// where the phi nodes don't necessarily need to be in the same block. Do a
|
|
// quick check to see if the PHI node only contains a single non-phi value, if
|
|
// so, scan to see if the phi cycle is actually equal to that value.
|
|
{
|
|
unsigned InValNo = 0, NumOperandVals = PN.getNumIncomingValues();
|
|
// Scan for the first non-phi operand.
|
|
while (InValNo != NumOperandVals &&
|
|
isa<PHINode>(PN.getIncomingValue(InValNo)))
|
|
++InValNo;
|
|
|
|
if (InValNo != NumOperandVals) {
|
|
Value *NonPhiInVal = PN.getOperand(InValNo);
|
|
|
|
// Scan the rest of the operands to see if there are any conflicts, if so
|
|
// there is no need to recursively scan other phis.
|
|
for (++InValNo; InValNo != NumOperandVals; ++InValNo) {
|
|
Value *OpVal = PN.getIncomingValue(InValNo);
|
|
if (OpVal != NonPhiInVal && !isa<PHINode>(OpVal))
|
|
break;
|
|
}
|
|
|
|
// If we scanned over all operands, then we have one unique value plus
|
|
// phi values. Scan PHI nodes to see if they all merge in each other or
|
|
// the value.
|
|
if (InValNo == NumOperandVals) {
|
|
SmallPtrSet<PHINode*, 16> ValueEqualPHIs;
|
|
if (PHIsEqualValue(&PN, NonPhiInVal, ValueEqualPHIs))
|
|
return ReplaceInstUsesWith(PN, NonPhiInVal);
|
|
}
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static Value *InsertCastToIntPtrTy(Value *V, const Type *DTy,
|
|
Instruction *InsertPoint,
|
|
InstCombiner *IC) {
|
|
unsigned PtrSize = DTy->getPrimitiveSizeInBits();
|
|
unsigned VTySize = V->getType()->getPrimitiveSizeInBits();
|
|
// We must cast correctly to the pointer type. Ensure that we
|
|
// sign extend the integer value if it is smaller as this is
|
|
// used for address computation.
|
|
Instruction::CastOps opcode =
|
|
(VTySize < PtrSize ? Instruction::SExt :
|
|
(VTySize == PtrSize ? Instruction::BitCast : Instruction::Trunc));
|
|
return IC->InsertCastBefore(opcode, V, DTy, *InsertPoint);
|
|
}
|
|
|
|
|
|
Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
|
|
Value *PtrOp = GEP.getOperand(0);
|
|
// Is it 'getelementptr %P, i32 0' or 'getelementptr %P'
|
|
// If so, eliminate the noop.
|
|
if (GEP.getNumOperands() == 1)
|
|
return ReplaceInstUsesWith(GEP, PtrOp);
|
|
|
|
if (isa<UndefValue>(GEP.getOperand(0)))
|
|
return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType()));
|
|
|
|
bool HasZeroPointerIndex = false;
|
|
if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1)))
|
|
HasZeroPointerIndex = C->isNullValue();
|
|
|
|
if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
|
|
return ReplaceInstUsesWith(GEP, PtrOp);
|
|
|
|
// Eliminate unneeded casts for indices.
|
|
bool MadeChange = false;
|
|
|
|
gep_type_iterator GTI = gep_type_begin(GEP);
|
|
for (User::op_iterator i = GEP.op_begin() + 1, e = GEP.op_end();
|
|
i != e; ++i, ++GTI) {
|
|
if (isa<SequentialType>(*GTI)) {
|
|
if (CastInst *CI = dyn_cast<CastInst>(*i)) {
|
|
if (CI->getOpcode() == Instruction::ZExt ||
|
|
CI->getOpcode() == Instruction::SExt) {
|
|
const Type *SrcTy = CI->getOperand(0)->getType();
|
|
// We can eliminate a cast from i32 to i64 iff the target
|
|
// is a 32-bit pointer target.
|
|
if (SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) {
|
|
MadeChange = true;
|
|
*i = CI->getOperand(0);
|
|
}
|
|
}
|
|
}
|
|
// If we are using a wider index than needed for this platform, shrink it
|
|
// to what we need. If narrower, sign-extend it to what we need.
|
|
// If the incoming value needs a cast instruction,
|
|
// insert it. This explicit cast can make subsequent optimizations more
|
|
// obvious.
|
|
Value *Op = *i;
|
|
if (TD->getTypeSizeInBits(Op->getType()) > TD->getPointerSizeInBits()) {
|
|
if (Constant *C = dyn_cast<Constant>(Op)) {
|
|
*i = ConstantExpr::getTrunc(C, TD->getIntPtrType());
|
|
MadeChange = true;
|
|
} else {
|
|
Op = InsertCastBefore(Instruction::Trunc, Op, TD->getIntPtrType(),
|
|
GEP);
|
|
*i = Op;
|
|
MadeChange = true;
|
|
}
|
|
} else if (TD->getTypeSizeInBits(Op->getType()) < TD->getPointerSizeInBits()) {
|
|
if (Constant *C = dyn_cast<Constant>(Op)) {
|
|
*i = ConstantExpr::getSExt(C, TD->getIntPtrType());
|
|
MadeChange = true;
|
|
} else {
|
|
Op = InsertCastBefore(Instruction::SExt, Op, TD->getIntPtrType(),
|
|
GEP);
|
|
*i = Op;
|
|
MadeChange = true;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
if (MadeChange) return &GEP;
|
|
|
|
// Combine Indices - If the source pointer to this getelementptr instruction
|
|
// is a getelementptr instruction, combine the indices of the two
|
|
// getelementptr instructions into a single instruction.
|
|
//
|
|
SmallVector<Value*, 8> SrcGEPOperands;
|
|
if (User *Src = dyn_castGetElementPtr(PtrOp))
|
|
SrcGEPOperands.append(Src->op_begin(), Src->op_end());
|
|
|
|
if (!SrcGEPOperands.empty()) {
|
|
// Note that if our source is a gep chain itself that we wait for that
|
|
// chain to be resolved before we perform this transformation. This
|
|
// avoids us creating a TON of code in some cases.
|
|
//
|
|
if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
|
|
cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
|
|
return 0; // Wait until our source is folded to completion.
|
|
|
|
SmallVector<Value*, 8> Indices;
|
|
|
|
// Find out whether the last index in the source GEP is a sequential idx.
|
|
bool EndsWithSequential = false;
|
|
for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)),
|
|
E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I)
|
|
EndsWithSequential = !isa<StructType>(*I);
|
|
|
|
// Can we combine the two pointer arithmetics offsets?
|
|
if (EndsWithSequential) {
|
|
// Replace: gep (gep %P, long B), long A, ...
|
|
// With: T = long A+B; gep %P, T, ...
|
|
//
|
|
Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1);
|
|
if (SO1 == Constant::getNullValue(SO1->getType())) {
|
|
Sum = GO1;
|
|
} else if (GO1 == Constant::getNullValue(GO1->getType())) {
|
|
Sum = SO1;
|
|
} else {
|
|
// If they aren't the same type, convert both to an integer of the
|
|
// target's pointer size.
|
|
if (SO1->getType() != GO1->getType()) {
|
|
if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
|
|
SO1 = ConstantExpr::getIntegerCast(SO1C, GO1->getType(), true);
|
|
} else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
|
|
GO1 = ConstantExpr::getIntegerCast(GO1C, SO1->getType(), true);
|
|
} else {
|
|
unsigned PS = TD->getPointerSizeInBits();
|
|
if (TD->getTypeSizeInBits(SO1->getType()) == PS) {
|
|
// Convert GO1 to SO1's type.
|
|
GO1 = InsertCastToIntPtrTy(GO1, SO1->getType(), &GEP, this);
|
|
|
|
} else if (TD->getTypeSizeInBits(GO1->getType()) == PS) {
|
|
// Convert SO1 to GO1's type.
|
|
SO1 = InsertCastToIntPtrTy(SO1, GO1->getType(), &GEP, this);
|
|
} else {
|
|
const Type *PT = TD->getIntPtrType();
|
|
SO1 = InsertCastToIntPtrTy(SO1, PT, &GEP, this);
|
|
GO1 = InsertCastToIntPtrTy(GO1, PT, &GEP, this);
|
|
}
|
|
}
|
|
}
|
|
if (isa<Constant>(SO1) && isa<Constant>(GO1))
|
|
Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1));
|
|
else {
|
|
Sum = BinaryOperator::CreateAdd(SO1, GO1, PtrOp->getName()+".sum");
|
|
InsertNewInstBefore(cast<Instruction>(Sum), GEP);
|
|
}
|
|
}
|
|
|
|
// Recycle the GEP we already have if possible.
|
|
if (SrcGEPOperands.size() == 2) {
|
|
GEP.setOperand(0, SrcGEPOperands[0]);
|
|
GEP.setOperand(1, Sum);
|
|
return &GEP;
|
|
} else {
|
|
Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
|
|
SrcGEPOperands.end()-1);
|
|
Indices.push_back(Sum);
|
|
Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end());
|
|
}
|
|
} else if (isa<Constant>(*GEP.idx_begin()) &&
|
|
cast<Constant>(*GEP.idx_begin())->isNullValue() &&
|
|
SrcGEPOperands.size() != 1) {
|
|
// Otherwise we can do the fold if the first index of the GEP is a zero
|
|
Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
|
|
SrcGEPOperands.end());
|
|
Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
|
|
}
|
|
|
|
if (!Indices.empty())
|
|
return GetElementPtrInst::Create(SrcGEPOperands[0], Indices.begin(),
|
|
Indices.end(), GEP.getName());
|
|
|
|
} else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) {
|
|
// GEP of global variable. If all of the indices for this GEP are
|
|
// constants, we can promote this to a constexpr instead of an instruction.
|
|
|
|
// Scan for nonconstants...
|
|
SmallVector<Constant*, 8> Indices;
|
|
User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
|
|
for (; I != E && isa<Constant>(*I); ++I)
|
|
Indices.push_back(cast<Constant>(*I));
|
|
|
|
if (I == E) { // If they are all constants...
|
|
Constant *CE = ConstantExpr::getGetElementPtr(GV,
|
|
&Indices[0],Indices.size());
|
|
|
|
// Replace all uses of the GEP with the new constexpr...
|
|
return ReplaceInstUsesWith(GEP, CE);
|
|
}
|
|
} else if (Value *X = getBitCastOperand(PtrOp)) { // Is the operand a cast?
|
|
if (!isa<PointerType>(X->getType())) {
|
|
// Not interesting. Source pointer must be a cast from pointer.
|
|
} else if (HasZeroPointerIndex) {
|
|
// transform: GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ...
|
|
// into : GEP [10 x i8]* X, i32 0, ...
|
|
//
|
|
// This occurs when the program declares an array extern like "int X[];"
|
|
//
|
|
const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
|
|
const PointerType *XTy = cast<PointerType>(X->getType());
|
|
if (const ArrayType *XATy =
|
|
dyn_cast<ArrayType>(XTy->getElementType()))
|
|
if (const ArrayType *CATy =
|
|
dyn_cast<ArrayType>(CPTy->getElementType()))
|
|
if (CATy->getElementType() == XATy->getElementType()) {
|
|
// At this point, we know that the cast source type is a pointer
|
|
// to an array of the same type as the destination pointer
|
|
// array. Because the array type is never stepped over (there
|
|
// is a leading zero) we can fold the cast into this GEP.
|
|
GEP.setOperand(0, X);
|
|
return &GEP;
|
|
}
|
|
} else if (GEP.getNumOperands() == 2) {
|
|
// Transform things like:
|
|
// %t = getelementptr i32* bitcast ([2 x i32]* %str to i32*), i32 %V
|
|
// into: %t1 = getelementptr [2 x i32]* %str, i32 0, i32 %V; bitcast
|
|
const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
|
|
const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
|
|
if (isa<ArrayType>(SrcElTy) &&
|
|
TD->getTypePaddedSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
|
|
TD->getTypePaddedSize(ResElTy)) {
|
|
Value *Idx[2];
|
|
Idx[0] = Constant::getNullValue(Type::Int32Ty);
|
|
Idx[1] = GEP.getOperand(1);
|
|
Value *V = InsertNewInstBefore(
|
|
GetElementPtrInst::Create(X, Idx, Idx + 2, GEP.getName()), GEP);
|
|
// V and GEP are both pointer types --> BitCast
|
|
return new BitCastInst(V, GEP.getType());
|
|
}
|
|
|
|
// Transform things like:
|
|
// getelementptr i8* bitcast ([100 x double]* X to i8*), i32 %tmp
|
|
// (where tmp = 8*tmp2) into:
|
|
// getelementptr [100 x double]* %arr, i32 0, i32 %tmp2; bitcast
|
|
|
|
if (isa<ArrayType>(SrcElTy) && ResElTy == Type::Int8Ty) {
|
|
uint64_t ArrayEltSize =
|
|
TD->getTypePaddedSize(cast<ArrayType>(SrcElTy)->getElementType());
|
|
|
|
// Check to see if "tmp" is a scale by a multiple of ArrayEltSize. We
|
|
// allow either a mul, shift, or constant here.
|
|
Value *NewIdx = 0;
|
|
ConstantInt *Scale = 0;
|
|
if (ArrayEltSize == 1) {
|
|
NewIdx = GEP.getOperand(1);
|
|
Scale = ConstantInt::get(NewIdx->getType(), 1);
|
|
} else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) {
|
|
NewIdx = ConstantInt::get(CI->getType(), 1);
|
|
Scale = CI;
|
|
} else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){
|
|
if (Inst->getOpcode() == Instruction::Shl &&
|
|
isa<ConstantInt>(Inst->getOperand(1))) {
|
|
ConstantInt *ShAmt = cast<ConstantInt>(Inst->getOperand(1));
|
|
uint32_t ShAmtVal = ShAmt->getLimitedValue(64);
|
|
Scale = ConstantInt::get(Inst->getType(), 1ULL << ShAmtVal);
|
|
NewIdx = Inst->getOperand(0);
|
|
} else if (Inst->getOpcode() == Instruction::Mul &&
|
|
isa<ConstantInt>(Inst->getOperand(1))) {
|
|
Scale = cast<ConstantInt>(Inst->getOperand(1));
|
|
NewIdx = Inst->getOperand(0);
|
|
}
|
|
}
|
|
|
|
// If the index will be to exactly the right offset with the scale taken
|
|
// out, perform the transformation. Note, we don't know whether Scale is
|
|
// signed or not. We'll use unsigned version of division/modulo
|
|
// operation after making sure Scale doesn't have the sign bit set.
|
|
if (Scale && Scale->getSExtValue() >= 0LL &&
|
|
Scale->getZExtValue() % ArrayEltSize == 0) {
|
|
Scale = ConstantInt::get(Scale->getType(),
|
|
Scale->getZExtValue() / ArrayEltSize);
|
|
if (Scale->getZExtValue() != 1) {
|
|
Constant *C = ConstantExpr::getIntegerCast(Scale, NewIdx->getType(),
|
|
false /*ZExt*/);
|
|
Instruction *Sc = BinaryOperator::CreateMul(NewIdx, C, "idxscale");
|
|
NewIdx = InsertNewInstBefore(Sc, GEP);
|
|
}
|
|
|
|
// Insert the new GEP instruction.
|
|
Value *Idx[2];
|
|
Idx[0] = Constant::getNullValue(Type::Int32Ty);
|
|
Idx[1] = NewIdx;
|
|
Instruction *NewGEP =
|
|
GetElementPtrInst::Create(X, Idx, Idx + 2, GEP.getName());
|
|
NewGEP = InsertNewInstBefore(NewGEP, GEP);
|
|
// The NewGEP must be pointer typed, so must the old one -> BitCast
|
|
return new BitCastInst(NewGEP, GEP.getType());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// See if we can simplify:
|
|
/// X = bitcast A to B*
|
|
/// Y = gep X, <...constant indices...>
|
|
/// into a gep of the original struct. This is important for SROA and alias
|
|
/// analysis of unions. If "A" is also a bitcast, wait for A/X to be merged.
|
|
if (BitCastInst *BCI = dyn_cast<BitCastInst>(PtrOp)) {
|
|
if (!isa<BitCastInst>(BCI->getOperand(0)) && GEP.hasAllConstantIndices()) {
|
|
// Determine how much the GEP moves the pointer. We are guaranteed to get
|
|
// a constant back from EmitGEPOffset.
|
|
ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(&GEP, GEP, *this));
|
|
int64_t Offset = OffsetV->getSExtValue();
|
|
|
|
// If this GEP instruction doesn't move the pointer, just replace the GEP
|
|
// with a bitcast of the real input to the dest type.
|
|
if (Offset == 0) {
|
|
// If the bitcast is of an allocation, and the allocation will be
|
|
// converted to match the type of the cast, don't touch this.
|
|
if (isa<AllocationInst>(BCI->getOperand(0))) {
|
|
// See if the bitcast simplifies, if so, don't nuke this GEP yet.
|
|
if (Instruction *I = visitBitCast(*BCI)) {
|
|
if (I != BCI) {
|
|
I->takeName(BCI);
|
|
BCI->getParent()->getInstList().insert(BCI, I);
|
|
ReplaceInstUsesWith(*BCI, I);
|
|
}
|
|
return &GEP;
|
|
}
|
|
}
|
|
return new BitCastInst(BCI->getOperand(0), GEP.getType());
|
|
}
|
|
|
|
// Otherwise, if the offset is non-zero, we need to find out if there is a
|
|
// field at Offset in 'A's type. If so, we can pull the cast through the
|
|
// GEP.
|
|
SmallVector<Value*, 8> NewIndices;
|
|
const Type *InTy =
|
|
cast<PointerType>(BCI->getOperand(0)->getType())->getElementType();
|
|
if (FindElementAtOffset(InTy, Offset, NewIndices, TD)) {
|
|
Instruction *NGEP =
|
|
GetElementPtrInst::Create(BCI->getOperand(0), NewIndices.begin(),
|
|
NewIndices.end());
|
|
if (NGEP->getType() == GEP.getType()) return NGEP;
|
|
InsertNewInstBefore(NGEP, GEP);
|
|
NGEP->takeName(&GEP);
|
|
return new BitCastInst(NGEP, GEP.getType());
|
|
}
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
|
|
// Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
|
|
if (AI.isArrayAllocation()) { // Check C != 1
|
|
if (const ConstantInt *C = dyn_cast<ConstantInt>(AI.getArraySize())) {
|
|
const Type *NewTy =
|
|
ArrayType::get(AI.getAllocatedType(), C->getZExtValue());
|
|
AllocationInst *New = 0;
|
|
|
|
// Create and insert the replacement instruction...
|
|
if (isa<MallocInst>(AI))
|
|
New = new MallocInst(NewTy, 0, AI.getAlignment(), AI.getName());
|
|
else {
|
|
assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
|
|
New = new AllocaInst(NewTy, 0, AI.getAlignment(), AI.getName());
|
|
}
|
|
|
|
InsertNewInstBefore(New, AI);
|
|
|
|
// Scan to the end of the allocation instructions, to skip over a block of
|
|
// allocas if possible...
|
|
//
|
|
BasicBlock::iterator It = New;
|
|
while (isa<AllocationInst>(*It)) ++It;
|
|
|
|
// Now that I is pointing to the first non-allocation-inst in the block,
|
|
// insert our getelementptr instruction...
|
|
//
|
|
Value *NullIdx = Constant::getNullValue(Type::Int32Ty);
|
|
Value *Idx[2];
|
|
Idx[0] = NullIdx;
|
|
Idx[1] = NullIdx;
|
|
Value *V = GetElementPtrInst::Create(New, Idx, Idx + 2,
|
|
New->getName()+".sub", It);
|
|
|
|
// Now make everything use the getelementptr instead of the original
|
|
// allocation.
|
|
return ReplaceInstUsesWith(AI, V);
|
|
} else if (isa<UndefValue>(AI.getArraySize())) {
|
|
return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
|
|
}
|
|
}
|
|
|
|
if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized()) {
|
|
// If alloca'ing a zero byte object, replace the alloca with a null pointer.
|
|
// Note that we only do this for alloca's, because malloc should allocate and
|
|
// return a unique pointer, even for a zero byte allocation.
|
|
if (TD->getTypePaddedSize(AI.getAllocatedType()) == 0)
|
|
return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
|
|
|
|
// If the alignment is 0 (unspecified), assign it the preferred alignment.
|
|
if (AI.getAlignment() == 0)
|
|
AI.setAlignment(TD->getPrefTypeAlignment(AI.getAllocatedType()));
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
|
|
Value *Op = FI.getOperand(0);
|
|
|
|
// free undef -> unreachable.
|
|
if (isa<UndefValue>(Op)) {
|
|
// Insert a new store to null because we cannot modify the CFG here.
|
|
new StoreInst(ConstantInt::getTrue(),
|
|
UndefValue::get(PointerType::getUnqual(Type::Int1Ty)), &FI);
|
|
return EraseInstFromFunction(FI);
|
|
}
|
|
|
|
// If we have 'free null' delete the instruction. This can happen in stl code
|
|
// when lots of inlining happens.
|
|
if (isa<ConstantPointerNull>(Op))
|
|
return EraseInstFromFunction(FI);
|
|
|
|
// Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
|
|
if (BitCastInst *CI = dyn_cast<BitCastInst>(Op)) {
|
|
FI.setOperand(0, CI->getOperand(0));
|
|
return &FI;
|
|
}
|
|
|
|
// Change free (gep X, 0,0,0,0) into free(X)
|
|
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) {
|
|
if (GEPI->hasAllZeroIndices()) {
|
|
AddToWorkList(GEPI);
|
|
FI.setOperand(0, GEPI->getOperand(0));
|
|
return &FI;
|
|
}
|
|
}
|
|
|
|
// Change free(malloc) into nothing, if the malloc has a single use.
|
|
if (MallocInst *MI = dyn_cast<MallocInst>(Op))
|
|
if (MI->hasOneUse()) {
|
|
EraseInstFromFunction(FI);
|
|
return EraseInstFromFunction(*MI);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
/// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
|
|
static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI,
|
|
const TargetData *TD) {
|
|
User *CI = cast<User>(LI.getOperand(0));
|
|
Value *CastOp = CI->getOperand(0);
|
|
|
|
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(CI)) {
|
|
// Instead of loading constant c string, use corresponding integer value
|
|
// directly if string length is small enough.
|
|
std::string Str;
|
|
if (GetConstantStringInfo(CE->getOperand(0), Str) && !Str.empty()) {
|
|
unsigned len = Str.length();
|
|
const Type *Ty = cast<PointerType>(CE->getType())->getElementType();
|
|
unsigned numBits = Ty->getPrimitiveSizeInBits();
|
|
// Replace LI with immediate integer store.
|
|
if ((numBits >> 3) == len + 1) {
|
|
APInt StrVal(numBits, 0);
|
|
APInt SingleChar(numBits, 0);
|
|
if (TD->isLittleEndian()) {
|
|
for (signed i = len-1; i >= 0; i--) {
|
|
SingleChar = (uint64_t) Str[i] & UCHAR_MAX;
|
|
StrVal = (StrVal << 8) | SingleChar;
|
|
}
|
|
} else {
|
|
for (unsigned i = 0; i < len; i++) {
|
|
SingleChar = (uint64_t) Str[i] & UCHAR_MAX;
|
|
StrVal = (StrVal << 8) | SingleChar;
|
|
}
|
|
// Append NULL at the end.
|
|
SingleChar = 0;
|
|
StrVal = (StrVal << 8) | SingleChar;
|
|
}
|
|
Value *NL = ConstantInt::get(StrVal);
|
|
return IC.ReplaceInstUsesWith(LI, NL);
|
|
}
|
|
}
|
|
}
|
|
|
|
const PointerType *DestTy = cast<PointerType>(CI->getType());
|
|
const Type *DestPTy = DestTy->getElementType();
|
|
if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
|
|
|
|
// If the address spaces don't match, don't eliminate the cast.
|
|
if (DestTy->getAddressSpace() != SrcTy->getAddressSpace())
|
|
return 0;
|
|
|
|
const Type *SrcPTy = SrcTy->getElementType();
|
|
|
|
if (DestPTy->isInteger() || isa<PointerType>(DestPTy) ||
|
|
isa<VectorType>(DestPTy)) {
|
|
// If the source is an array, the code below will not succeed. Check to
|
|
// see if a trivial 'gep P, 0, 0' will help matters. Only do this for
|
|
// constants.
|
|
if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
|
|
if (Constant *CSrc = dyn_cast<Constant>(CastOp))
|
|
if (ASrcTy->getNumElements() != 0) {
|
|
Value *Idxs[2];
|
|
Idxs[0] = Idxs[1] = Constant::getNullValue(Type::Int32Ty);
|
|
CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs, 2);
|
|
SrcTy = cast<PointerType>(CastOp->getType());
|
|
SrcPTy = SrcTy->getElementType();
|
|
}
|
|
|
|
if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy) ||
|
|
isa<VectorType>(SrcPTy)) &&
|
|
// Do not allow turning this into a load of an integer, which is then
|
|
// casted to a pointer, this pessimizes pointer analysis a lot.
|
|
(isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) &&
|
|
IC.getTargetData().getTypeSizeInBits(SrcPTy) ==
|
|
IC.getTargetData().getTypeSizeInBits(DestPTy)) {
|
|
|
|
// Okay, we are casting from one integer or pointer type to another of
|
|
// the same size. Instead of casting the pointer before the load, cast
|
|
// the result of the loaded value.
|
|
Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CastOp,
|
|
CI->getName(),
|
|
LI.isVolatile()),LI);
|
|
// Now cast the result of the load.
|
|
return new BitCastInst(NewLoad, LI.getType());
|
|
}
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/// isSafeToLoadUnconditionally - Return true if we know that executing a load
|
|
/// from this value cannot trap. If it is not obviously safe to load from the
|
|
/// specified pointer, we do a quick local scan of the basic block containing
|
|
/// ScanFrom, to determine if the address is already accessed.
|
|
static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
|
|
// If it is an alloca it is always safe to load from.
|
|
if (isa<AllocaInst>(V)) return true;
|
|
|
|
// If it is a global variable it is mostly safe to load from.
|
|
if (const GlobalValue *GV = dyn_cast<GlobalVariable>(V))
|
|
// Don't try to evaluate aliases. External weak GV can be null.
|
|
return !isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage();
|
|
|
|
// Otherwise, be a little bit agressive by scanning the local block where we
|
|
// want to check to see if the pointer is already being loaded or stored
|
|
// from/to. If so, the previous load or store would have already trapped,
|
|
// so there is no harm doing an extra load (also, CSE will later eliminate
|
|
// the load entirely).
|
|
BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
|
|
|
|
while (BBI != E) {
|
|
--BBI;
|
|
|
|
// If we see a free or a call (which might do a free) the pointer could be
|
|
// marked invalid.
|
|
if (isa<FreeInst>(BBI) || isa<CallInst>(BBI))
|
|
return false;
|
|
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
|
|
if (LI->getOperand(0) == V) return true;
|
|
} else if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) {
|
|
if (SI->getOperand(1) == V) return true;
|
|
}
|
|
|
|
}
|
|
return false;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
|
|
Value *Op = LI.getOperand(0);
|
|
|
|
// Attempt to improve the alignment.
|
|
unsigned KnownAlign =
|
|
GetOrEnforceKnownAlignment(Op, TD->getPrefTypeAlignment(LI.getType()));
|
|
if (KnownAlign >
|
|
(LI.getAlignment() == 0 ? TD->getABITypeAlignment(LI.getType()) :
|
|
LI.getAlignment()))
|
|
LI.setAlignment(KnownAlign);
|
|
|
|
// load (cast X) --> cast (load X) iff safe
|
|
if (isa<CastInst>(Op))
|
|
if (Instruction *Res = InstCombineLoadCast(*this, LI, TD))
|
|
return Res;
|
|
|
|
// None of the following transforms are legal for volatile loads.
|
|
if (LI.isVolatile()) return 0;
|
|
|
|
// Do really simple store-to-load forwarding and load CSE, to catch cases
|
|
// where there are several consequtive memory accesses to the same location,
|
|
// separated by a few arithmetic operations.
|
|
BasicBlock::iterator BBI = &LI;
|
|
if (Value *AvailableVal = FindAvailableLoadedValue(Op, LI.getParent(), BBI,6))
|
|
return ReplaceInstUsesWith(LI, AvailableVal);
|
|
|
|
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) {
|
|
const Value *GEPI0 = GEPI->getOperand(0);
|
|
// TODO: Consider a target hook for valid address spaces for this xform.
|
|
if (isa<ConstantPointerNull>(GEPI0) &&
|
|
cast<PointerType>(GEPI0->getType())->getAddressSpace() == 0) {
|
|
// Insert a new store to null instruction before the load to indicate
|
|
// that this code is not reachable. We do this instead of inserting
|
|
// an unreachable instruction directly because we cannot modify the
|
|
// CFG.
|
|
new StoreInst(UndefValue::get(LI.getType()),
|
|
Constant::getNullValue(Op->getType()), &LI);
|
|
return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
|
|
}
|
|
}
|
|
|
|
if (Constant *C = dyn_cast<Constant>(Op)) {
|
|
// load null/undef -> undef
|
|
// TODO: Consider a target hook for valid address spaces for this xform.
|
|
if (isa<UndefValue>(C) || (C->isNullValue() &&
|
|
cast<PointerType>(Op->getType())->getAddressSpace() == 0)) {
|
|
// Insert a new store to null instruction before the load to indicate that
|
|
// this code is not reachable. We do this instead of inserting an
|
|
// unreachable instruction directly because we cannot modify the CFG.
|
|
new StoreInst(UndefValue::get(LI.getType()),
|
|
Constant::getNullValue(Op->getType()), &LI);
|
|
return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
|
|
}
|
|
|
|
// Instcombine load (constant global) into the value loaded.
|
|
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
|
|
if (GV->isConstant() && !GV->isDeclaration())
|
|
return ReplaceInstUsesWith(LI, GV->getInitializer());
|
|
|
|
// Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded.
|
|
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op)) {
|
|
if (CE->getOpcode() == Instruction::GetElementPtr) {
|
|
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
|
|
if (GV->isConstant() && !GV->isDeclaration())
|
|
if (Constant *V =
|
|
ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE))
|
|
return ReplaceInstUsesWith(LI, V);
|
|
if (CE->getOperand(0)->isNullValue()) {
|
|
// Insert a new store to null instruction before the load to indicate
|
|
// that this code is not reachable. We do this instead of inserting
|
|
// an unreachable instruction directly because we cannot modify the
|
|
// CFG.
|
|
new StoreInst(UndefValue::get(LI.getType()),
|
|
Constant::getNullValue(Op->getType()), &LI);
|
|
return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
|
|
}
|
|
|
|
} else if (CE->isCast()) {
|
|
if (Instruction *Res = InstCombineLoadCast(*this, LI, TD))
|
|
return Res;
|
|
}
|
|
}
|
|
}
|
|
|
|
// If this load comes from anywhere in a constant global, and if the global
|
|
// is all undef or zero, we know what it loads.
|
|
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op->getUnderlyingObject())){
|
|
if (GV->isConstant() && GV->hasInitializer()) {
|
|
if (GV->getInitializer()->isNullValue())
|
|
return ReplaceInstUsesWith(LI, Constant::getNullValue(LI.getType()));
|
|
else if (isa<UndefValue>(GV->getInitializer()))
|
|
return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType()));
|
|
}
|
|
}
|
|
|
|
if (Op->hasOneUse()) {
|
|
// Change select and PHI nodes to select values instead of addresses: this
|
|
// helps alias analysis out a lot, allows many others simplifications, and
|
|
// exposes redundancy in the code.
|
|
//
|
|
// Note that we cannot do the transformation unless we know that the
|
|
// introduced loads cannot trap! Something like this is valid as long as
|
|
// the condition is always false: load (select bool %C, int* null, int* %G),
|
|
// but it would not be valid if we transformed it to load from null
|
|
// unconditionally.
|
|
//
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
|
|
// load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2).
|
|
if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) &&
|
|
isSafeToLoadUnconditionally(SI->getOperand(2), SI)) {
|
|
Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1),
|
|
SI->getOperand(1)->getName()+".val"), LI);
|
|
Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2),
|
|
SI->getOperand(2)->getName()+".val"), LI);
|
|
return SelectInst::Create(SI->getCondition(), V1, V2);
|
|
}
|
|
|
|
// load (select (cond, null, P)) -> load P
|
|
if (Constant *C = dyn_cast<Constant>(SI->getOperand(1)))
|
|
if (C->isNullValue()) {
|
|
LI.setOperand(0, SI->getOperand(2));
|
|
return &LI;
|
|
}
|
|
|
|
// load (select (cond, P, null)) -> load P
|
|
if (Constant *C = dyn_cast<Constant>(SI->getOperand(2)))
|
|
if (C->isNullValue()) {
|
|
LI.setOperand(0, SI->getOperand(1));
|
|
return &LI;
|
|
}
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/// InstCombineStoreToCast - Fold store V, (cast P) -> store (cast V), P
|
|
/// when possible. This makes it generally easy to do alias analysis and/or
|
|
/// SROA/mem2reg of the memory object.
|
|
static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) {
|
|
User *CI = cast<User>(SI.getOperand(1));
|
|
Value *CastOp = CI->getOperand(0);
|
|
|
|
const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
|
|
const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType());
|
|
if (SrcTy == 0) return 0;
|
|
|
|
const Type *SrcPTy = SrcTy->getElementType();
|
|
|
|
if (!DestPTy->isInteger() && !isa<PointerType>(DestPTy))
|
|
return 0;
|
|
|
|
/// NewGEPIndices - If SrcPTy is an aggregate type, we can emit a "noop gep"
|
|
/// to its first element. This allows us to handle things like:
|
|
/// store i32 xxx, (bitcast {foo*, float}* %P to i32*)
|
|
/// on 32-bit hosts.
|
|
SmallVector<Value*, 4> NewGEPIndices;
|
|
|
|
// If the source is an array, the code below will not succeed. Check to
|
|
// see if a trivial 'gep P, 0, 0' will help matters. Only do this for
|
|
// constants.
|
|
if (isa<ArrayType>(SrcPTy) || isa<StructType>(SrcPTy)) {
|
|
// Index through pointer.
|
|
Constant *Zero = Constant::getNullValue(Type::Int32Ty);
|
|
NewGEPIndices.push_back(Zero);
|
|
|
|
while (1) {
|
|
if (const StructType *STy = dyn_cast<StructType>(SrcPTy)) {
|
|
if (!STy->getNumElements()) /* Struct can be empty {} */
|
|
break;
|
|
NewGEPIndices.push_back(Zero);
|
|
SrcPTy = STy->getElementType(0);
|
|
} else if (const ArrayType *ATy = dyn_cast<ArrayType>(SrcPTy)) {
|
|
NewGEPIndices.push_back(Zero);
|
|
SrcPTy = ATy->getElementType();
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
|
|
SrcTy = PointerType::get(SrcPTy, SrcTy->getAddressSpace());
|
|
}
|
|
|
|
if (!SrcPTy->isInteger() && !isa<PointerType>(SrcPTy))
|
|
return 0;
|
|
|
|
// If the pointers point into different address spaces or if they point to
|
|
// values with different sizes, we can't do the transformation.
|
|
if (SrcTy->getAddressSpace() !=
|
|
cast<PointerType>(CI->getType())->getAddressSpace() ||
|
|
IC.getTargetData().getTypeSizeInBits(SrcPTy) !=
|
|
IC.getTargetData().getTypeSizeInBits(DestPTy))
|
|
return 0;
|
|
|
|
// Okay, we are casting from one integer or pointer type to another of
|
|
// the same size. Instead of casting the pointer before
|
|
// the store, cast the value to be stored.
|
|
Value *NewCast;
|
|
Value *SIOp0 = SI.getOperand(0);
|
|
Instruction::CastOps opcode = Instruction::BitCast;
|
|
const Type* CastSrcTy = SIOp0->getType();
|
|
const Type* CastDstTy = SrcPTy;
|
|
if (isa<PointerType>(CastDstTy)) {
|
|
if (CastSrcTy->isInteger())
|
|
opcode = Instruction::IntToPtr;
|
|
} else if (isa<IntegerType>(CastDstTy)) {
|
|
if (isa<PointerType>(SIOp0->getType()))
|
|
opcode = Instruction::PtrToInt;
|
|
}
|
|
|
|
// SIOp0 is a pointer to aggregate and this is a store to the first field,
|
|
// emit a GEP to index into its first field.
|
|
if (!NewGEPIndices.empty()) {
|
|
if (Constant *C = dyn_cast<Constant>(CastOp))
|
|
CastOp = ConstantExpr::getGetElementPtr(C, &NewGEPIndices[0],
|
|
NewGEPIndices.size());
|
|
else
|
|
CastOp = IC.InsertNewInstBefore(
|
|
GetElementPtrInst::Create(CastOp, NewGEPIndices.begin(),
|
|
NewGEPIndices.end()), SI);
|
|
}
|
|
|
|
if (Constant *C = dyn_cast<Constant>(SIOp0))
|
|
NewCast = ConstantExpr::getCast(opcode, C, CastDstTy);
|
|
else
|
|
NewCast = IC.InsertNewInstBefore(
|
|
CastInst::Create(opcode, SIOp0, CastDstTy, SIOp0->getName()+".c"),
|
|
SI);
|
|
return new StoreInst(NewCast, CastOp);
|
|
}
|
|
|
|
/// equivalentAddressValues - Test if A and B will obviously have the same
|
|
/// value. This includes recognizing that %t0 and %t1 will have the same
|
|
/// value in code like this:
|
|
/// %t0 = getelementptr @a, 0, 3
|
|
/// store i32 0, i32* %t0
|
|
/// %t1 = getelementptr @a, 0, 3
|
|
/// %t2 = load i32* %t1
|
|
///
|
|
static bool equivalentAddressValues(Value *A, Value *B) {
|
|
// Test if the values are trivially equivalent.
|
|
if (A == B) return true;
|
|
|
|
// Test if the values come form identical arithmetic instructions.
|
|
if (isa<BinaryOperator>(A) ||
|
|
isa<CastInst>(A) ||
|
|
isa<PHINode>(A) ||
|
|
isa<GetElementPtrInst>(A))
|
|
if (Instruction *BI = dyn_cast<Instruction>(B))
|
|
if (cast<Instruction>(A)->isIdenticalTo(BI))
|
|
return true;
|
|
|
|
// Otherwise they may not be equivalent.
|
|
return false;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
|
|
Value *Val = SI.getOperand(0);
|
|
Value *Ptr = SI.getOperand(1);
|
|
|
|
if (isa<UndefValue>(Ptr)) { // store X, undef -> noop (even if volatile)
|
|
EraseInstFromFunction(SI);
|
|
++NumCombined;
|
|
return 0;
|
|
}
|
|
|
|
// If the RHS is an alloca with a single use, zapify the store, making the
|
|
// alloca dead.
|
|
if (Ptr->hasOneUse() && !SI.isVolatile()) {
|
|
if (isa<AllocaInst>(Ptr)) {
|
|
EraseInstFromFunction(SI);
|
|
++NumCombined;
|
|
return 0;
|
|
}
|
|
|
|
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr))
|
|
if (isa<AllocaInst>(GEP->getOperand(0)) &&
|
|
GEP->getOperand(0)->hasOneUse()) {
|
|
EraseInstFromFunction(SI);
|
|
++NumCombined;
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
// Attempt to improve the alignment.
|
|
unsigned KnownAlign =
|
|
GetOrEnforceKnownAlignment(Ptr, TD->getPrefTypeAlignment(Val->getType()));
|
|
if (KnownAlign >
|
|
(SI.getAlignment() == 0 ? TD->getABITypeAlignment(Val->getType()) :
|
|
SI.getAlignment()))
|
|
SI.setAlignment(KnownAlign);
|
|
|
|
// Do really simple DSE, to catch cases where there are several consequtive
|
|
// stores to the same location, separated by a few arithmetic operations. This
|
|
// situation often occurs with bitfield accesses.
|
|
BasicBlock::iterator BBI = &SI;
|
|
for (unsigned ScanInsts = 6; BBI != SI.getParent()->begin() && ScanInsts;
|
|
--ScanInsts) {
|
|
--BBI;
|
|
|
|
if (StoreInst *PrevSI = dyn_cast<StoreInst>(BBI)) {
|
|
// Prev store isn't volatile, and stores to the same location?
|
|
if (!PrevSI->isVolatile() &&equivalentAddressValues(PrevSI->getOperand(1),
|
|
SI.getOperand(1))) {
|
|
++NumDeadStore;
|
|
++BBI;
|
|
EraseInstFromFunction(*PrevSI);
|
|
continue;
|
|
}
|
|
break;
|
|
}
|
|
|
|
// If this is a load, we have to stop. However, if the loaded value is from
|
|
// the pointer we're loading and is producing the pointer we're storing,
|
|
// then *this* store is dead (X = load P; store X -> P).
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
|
|
if (LI == Val && equivalentAddressValues(LI->getOperand(0), Ptr) &&
|
|
!SI.isVolatile()) {
|
|
EraseInstFromFunction(SI);
|
|
++NumCombined;
|
|
return 0;
|
|
}
|
|
// Otherwise, this is a load from some other location. Stores before it
|
|
// may not be dead.
|
|
break;
|
|
}
|
|
|
|
// Don't skip over loads or things that can modify memory.
|
|
if (BBI->mayWriteToMemory() || BBI->mayReadFromMemory())
|
|
break;
|
|
}
|
|
|
|
|
|
if (SI.isVolatile()) return 0; // Don't hack volatile stores.
|
|
|
|
// store X, null -> turns into 'unreachable' in SimplifyCFG
|
|
if (isa<ConstantPointerNull>(Ptr)) {
|
|
if (!isa<UndefValue>(Val)) {
|
|
SI.setOperand(0, UndefValue::get(Val->getType()));
|
|
if (Instruction *U = dyn_cast<Instruction>(Val))
|
|
AddToWorkList(U); // Dropped a use.
|
|
++NumCombined;
|
|
}
|
|
return 0; // Do not modify these!
|
|
}
|
|
|
|
// store undef, Ptr -> noop
|
|
if (isa<UndefValue>(Val)) {
|
|
EraseInstFromFunction(SI);
|
|
++NumCombined;
|
|
return 0;
|
|
}
|
|
|
|
// If the pointer destination is a cast, see if we can fold the cast into the
|
|
// source instead.
|
|
if (isa<CastInst>(Ptr))
|
|
if (Instruction *Res = InstCombineStoreToCast(*this, SI))
|
|
return Res;
|
|
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
|
|
if (CE->isCast())
|
|
if (Instruction *Res = InstCombineStoreToCast(*this, SI))
|
|
return Res;
|
|
|
|
|
|
// If this store is the last instruction in the basic block, and if the block
|
|
// ends with an unconditional branch, try to move it to the successor block.
|
|
BBI = &SI; ++BBI;
|
|
if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
|
|
if (BI->isUnconditional())
|
|
if (SimplifyStoreAtEndOfBlock(SI))
|
|
return 0; // xform done!
|
|
|
|
return 0;
|
|
}
|
|
|
|
/// SimplifyStoreAtEndOfBlock - Turn things like:
|
|
/// if () { *P = v1; } else { *P = v2 }
|
|
/// into a phi node with a store in the successor.
|
|
///
|
|
/// Simplify things like:
|
|
/// *P = v1; if () { *P = v2; }
|
|
/// into a phi node with a store in the successor.
|
|
///
|
|
bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) {
|
|
BasicBlock *StoreBB = SI.getParent();
|
|
|
|
// Check to see if the successor block has exactly two incoming edges. If
|
|
// so, see if the other predecessor contains a store to the same location.
|
|
// if so, insert a PHI node (if needed) and move the stores down.
|
|
BasicBlock *DestBB = StoreBB->getTerminator()->getSuccessor(0);
|
|
|
|
// Determine whether Dest has exactly two predecessors and, if so, compute
|
|
// the other predecessor.
|
|
pred_iterator PI = pred_begin(DestBB);
|
|
BasicBlock *OtherBB = 0;
|
|
if (*PI != StoreBB)
|
|
OtherBB = *PI;
|
|
++PI;
|
|
if (PI == pred_end(DestBB))
|
|
return false;
|
|
|
|
if (*PI != StoreBB) {
|
|
if (OtherBB)
|
|
return false;
|
|
OtherBB = *PI;
|
|
}
|
|
if (++PI != pred_end(DestBB))
|
|
return false;
|
|
|
|
// Bail out if all the relevant blocks aren't distinct (this can happen,
|
|
// for example, if SI is in an infinite loop)
|
|
if (StoreBB == DestBB || OtherBB == DestBB)
|
|
return false;
|
|
|
|
// Verify that the other block ends in a branch and is not otherwise empty.
|
|
BasicBlock::iterator BBI = OtherBB->getTerminator();
|
|
BranchInst *OtherBr = dyn_cast<BranchInst>(BBI);
|
|
if (!OtherBr || BBI == OtherBB->begin())
|
|
return false;
|
|
|
|
// If the other block ends in an unconditional branch, check for the 'if then
|
|
// else' case. there is an instruction before the branch.
|
|
StoreInst *OtherStore = 0;
|
|
if (OtherBr->isUnconditional()) {
|
|
// If this isn't a store, or isn't a store to the same location, bail out.
|
|
--BBI;
|
|
OtherStore = dyn_cast<StoreInst>(BBI);
|
|
if (!OtherStore || OtherStore->getOperand(1) != SI.getOperand(1))
|
|
return false;
|
|
} else {
|
|
// Otherwise, the other block ended with a conditional branch. If one of the
|
|
// destinations is StoreBB, then we have the if/then case.
|
|
if (OtherBr->getSuccessor(0) != StoreBB &&
|
|
OtherBr->getSuccessor(1) != StoreBB)
|
|
return false;
|
|
|
|
// Okay, we know that OtherBr now goes to Dest and StoreBB, so this is an
|
|
// if/then triangle. See if there is a store to the same ptr as SI that
|
|
// lives in OtherBB.
|
|
for (;; --BBI) {
|
|
// Check to see if we find the matching store.
|
|
if ((OtherStore = dyn_cast<StoreInst>(BBI))) {
|
|
if (OtherStore->getOperand(1) != SI.getOperand(1))
|
|
return false;
|
|
break;
|
|
}
|
|
// If we find something that may be using or overwriting the stored
|
|
// value, or if we run out of instructions, we can't do the xform.
|
|
if (BBI->mayReadFromMemory() || BBI->mayWriteToMemory() ||
|
|
BBI == OtherBB->begin())
|
|
return false;
|
|
}
|
|
|
|
// In order to eliminate the store in OtherBr, we have to
|
|
// make sure nothing reads or overwrites the stored value in
|
|
// StoreBB.
|
|
for (BasicBlock::iterator I = StoreBB->begin(); &*I != &SI; ++I) {
|
|
// FIXME: This should really be AA driven.
|
|
if (I->mayReadFromMemory() || I->mayWriteToMemory())
|
|
return false;
|
|
}
|
|
}
|
|
|
|
// Insert a PHI node now if we need it.
|
|
Value *MergedVal = OtherStore->getOperand(0);
|
|
if (MergedVal != SI.getOperand(0)) {
|
|
PHINode *PN = PHINode::Create(MergedVal->getType(), "storemerge");
|
|
PN->reserveOperandSpace(2);
|
|
PN->addIncoming(SI.getOperand(0), SI.getParent());
|
|
PN->addIncoming(OtherStore->getOperand(0), OtherBB);
|
|
MergedVal = InsertNewInstBefore(PN, DestBB->front());
|
|
}
|
|
|
|
// Advance to a place where it is safe to insert the new store and
|
|
// insert it.
|
|
BBI = DestBB->getFirstNonPHI();
|
|
InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
|
|
OtherStore->isVolatile()), *BBI);
|
|
|
|
// Nuke the old stores.
|
|
EraseInstFromFunction(SI);
|
|
EraseInstFromFunction(*OtherStore);
|
|
++NumCombined;
|
|
return true;
|
|
}
|
|
|
|
|
|
Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
|
|
// Change br (not X), label True, label False to: br X, label False, True
|
|
Value *X = 0;
|
|
BasicBlock *TrueDest;
|
|
BasicBlock *FalseDest;
|
|
if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
|
|
!isa<Constant>(X)) {
|
|
// Swap Destinations and condition...
|
|
BI.setCondition(X);
|
|
BI.setSuccessor(0, FalseDest);
|
|
BI.setSuccessor(1, TrueDest);
|
|
return &BI;
|
|
}
|
|
|
|
// Cannonicalize fcmp_one -> fcmp_oeq
|
|
FCmpInst::Predicate FPred; Value *Y;
|
|
if (match(&BI, m_Br(m_FCmp(FPred, m_Value(X), m_Value(Y)),
|
|
TrueDest, FalseDest)))
|
|
if ((FPred == FCmpInst::FCMP_ONE || FPred == FCmpInst::FCMP_OLE ||
|
|
FPred == FCmpInst::FCMP_OGE) && BI.getCondition()->hasOneUse()) {
|
|
FCmpInst *I = cast<FCmpInst>(BI.getCondition());
|
|
FCmpInst::Predicate NewPred = FCmpInst::getInversePredicate(FPred);
|
|
Instruction *NewSCC = new FCmpInst(NewPred, X, Y, "", I);
|
|
NewSCC->takeName(I);
|
|
// Swap Destinations and condition...
|
|
BI.setCondition(NewSCC);
|
|
BI.setSuccessor(0, FalseDest);
|
|
BI.setSuccessor(1, TrueDest);
|
|
RemoveFromWorkList(I);
|
|
I->eraseFromParent();
|
|
AddToWorkList(NewSCC);
|
|
return &BI;
|
|
}
|
|
|
|
// Cannonicalize icmp_ne -> icmp_eq
|
|
ICmpInst::Predicate IPred;
|
|
if (match(&BI, m_Br(m_ICmp(IPred, m_Value(X), m_Value(Y)),
|
|
TrueDest, FalseDest)))
|
|
if ((IPred == ICmpInst::ICMP_NE || IPred == ICmpInst::ICMP_ULE ||
|
|
IPred == ICmpInst::ICMP_SLE || IPred == ICmpInst::ICMP_UGE ||
|
|
IPred == ICmpInst::ICMP_SGE) && BI.getCondition()->hasOneUse()) {
|
|
ICmpInst *I = cast<ICmpInst>(BI.getCondition());
|
|
ICmpInst::Predicate NewPred = ICmpInst::getInversePredicate(IPred);
|
|
Instruction *NewSCC = new ICmpInst(NewPred, X, Y, "", I);
|
|
NewSCC->takeName(I);
|
|
// Swap Destinations and condition...
|
|
BI.setCondition(NewSCC);
|
|
BI.setSuccessor(0, FalseDest);
|
|
BI.setSuccessor(1, TrueDest);
|
|
RemoveFromWorkList(I);
|
|
I->eraseFromParent();;
|
|
AddToWorkList(NewSCC);
|
|
return &BI;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
|
|
Value *Cond = SI.getCondition();
|
|
if (Instruction *I = dyn_cast<Instruction>(Cond)) {
|
|
if (I->getOpcode() == Instruction::Add)
|
|
if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
|
|
// change 'switch (X+4) case 1:' into 'switch (X) case -3'
|
|
for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2)
|
|
SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)),
|
|
AddRHS));
|
|
SI.setOperand(0, I->getOperand(0));
|
|
AddToWorkList(I);
|
|
return &SI;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitExtractValueInst(ExtractValueInst &EV) {
|
|
Value *Agg = EV.getAggregateOperand();
|
|
|
|
if (!EV.hasIndices())
|
|
return ReplaceInstUsesWith(EV, Agg);
|
|
|
|
if (Constant *C = dyn_cast<Constant>(Agg)) {
|
|
if (isa<UndefValue>(C))
|
|
return ReplaceInstUsesWith(EV, UndefValue::get(EV.getType()));
|
|
|
|
if (isa<ConstantAggregateZero>(C))
|
|
return ReplaceInstUsesWith(EV, Constant::getNullValue(EV.getType()));
|
|
|
|
if (isa<ConstantArray>(C) || isa<ConstantStruct>(C)) {
|
|
// Extract the element indexed by the first index out of the constant
|
|
Value *V = C->getOperand(*EV.idx_begin());
|
|
if (EV.getNumIndices() > 1)
|
|
// Extract the remaining indices out of the constant indexed by the
|
|
// first index
|
|
return ExtractValueInst::Create(V, EV.idx_begin() + 1, EV.idx_end());
|
|
else
|
|
return ReplaceInstUsesWith(EV, V);
|
|
}
|
|
return 0; // Can't handle other constants
|
|
}
|
|
if (InsertValueInst *IV = dyn_cast<InsertValueInst>(Agg)) {
|
|
// We're extracting from an insertvalue instruction, compare the indices
|
|
const unsigned *exti, *exte, *insi, *inse;
|
|
for (exti = EV.idx_begin(), insi = IV->idx_begin(),
|
|
exte = EV.idx_end(), inse = IV->idx_end();
|
|
exti != exte && insi != inse;
|
|
++exti, ++insi) {
|
|
if (*insi != *exti)
|
|
// The insert and extract both reference distinctly different elements.
|
|
// This means the extract is not influenced by the insert, and we can
|
|
// replace the aggregate operand of the extract with the aggregate
|
|
// operand of the insert. i.e., replace
|
|
// %I = insertvalue { i32, { i32 } } %A, { i32 } { i32 42 }, 1
|
|
// %E = extractvalue { i32, { i32 } } %I, 0
|
|
// with
|
|
// %E = extractvalue { i32, { i32 } } %A, 0
|
|
return ExtractValueInst::Create(IV->getAggregateOperand(),
|
|
EV.idx_begin(), EV.idx_end());
|
|
}
|
|
if (exti == exte && insi == inse)
|
|
// Both iterators are at the end: Index lists are identical. Replace
|
|
// %B = insertvalue { i32, { i32 } } %A, i32 42, 1, 0
|
|
// %C = extractvalue { i32, { i32 } } %B, 1, 0
|
|
// with "i32 42"
|
|
return ReplaceInstUsesWith(EV, IV->getInsertedValueOperand());
|
|
if (exti == exte) {
|
|
// The extract list is a prefix of the insert list. i.e. replace
|
|
// %I = insertvalue { i32, { i32 } } %A, i32 42, 1, 0
|
|
// %E = extractvalue { i32, { i32 } } %I, 1
|
|
// with
|
|
// %X = extractvalue { i32, { i32 } } %A, 1
|
|
// %E = insertvalue { i32 } %X, i32 42, 0
|
|
// by switching the order of the insert and extract (though the
|
|
// insertvalue should be left in, since it may have other uses).
|
|
Value *NewEV = InsertNewInstBefore(
|
|
ExtractValueInst::Create(IV->getAggregateOperand(),
|
|
EV.idx_begin(), EV.idx_end()),
|
|
EV);
|
|
return InsertValueInst::Create(NewEV, IV->getInsertedValueOperand(),
|
|
insi, inse);
|
|
}
|
|
if (insi == inse)
|
|
// The insert list is a prefix of the extract list
|
|
// We can simply remove the common indices from the extract and make it
|
|
// operate on the inserted value instead of the insertvalue result.
|
|
// i.e., replace
|
|
// %I = insertvalue { i32, { i32 } } %A, { i32 } { i32 42 }, 1
|
|
// %E = extractvalue { i32, { i32 } } %I, 1, 0
|
|
// with
|
|
// %E extractvalue { i32 } { i32 42 }, 0
|
|
return ExtractValueInst::Create(IV->getInsertedValueOperand(),
|
|
exti, exte);
|
|
}
|
|
// Can't simplify extracts from other values. Note that nested extracts are
|
|
// already simplified implicitely by the above (extract ( extract (insert) )
|
|
// will be translated into extract ( insert ( extract ) ) first and then just
|
|
// the value inserted, if appropriate).
|
|
return 0;
|
|
}
|
|
|
|
/// CheapToScalarize - Return true if the value is cheaper to scalarize than it
|
|
/// is to leave as a vector operation.
|
|
static bool CheapToScalarize(Value *V, bool isConstant) {
|
|
if (isa<ConstantAggregateZero>(V))
|
|
return true;
|
|
if (ConstantVector *C = dyn_cast<ConstantVector>(V)) {
|
|
if (isConstant) return true;
|
|
// If all elts are the same, we can extract.
|
|
Constant *Op0 = C->getOperand(0);
|
|
for (unsigned i = 1; i < C->getNumOperands(); ++i)
|
|
if (C->getOperand(i) != Op0)
|
|
return false;
|
|
return true;
|
|
}
|
|
Instruction *I = dyn_cast<Instruction>(V);
|
|
if (!I) return false;
|
|
|
|
// Insert element gets simplified to the inserted element or is deleted if
|
|
// this is constant idx extract element and its a constant idx insertelt.
|
|
if (I->getOpcode() == Instruction::InsertElement && isConstant &&
|
|
isa<ConstantInt>(I->getOperand(2)))
|
|
return true;
|
|
if (I->getOpcode() == Instruction::Load && I->hasOneUse())
|
|
return true;
|
|
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I))
|
|
if (BO->hasOneUse() &&
|
|
(CheapToScalarize(BO->getOperand(0), isConstant) ||
|
|
CheapToScalarize(BO->getOperand(1), isConstant)))
|
|
return true;
|
|
if (CmpInst *CI = dyn_cast<CmpInst>(I))
|
|
if (CI->hasOneUse() &&
|
|
(CheapToScalarize(CI->getOperand(0), isConstant) ||
|
|
CheapToScalarize(CI->getOperand(1), isConstant)))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/// Read and decode a shufflevector mask.
|
|
///
|
|
/// It turns undef elements into values that are larger than the number of
|
|
/// elements in the input.
|
|
static std::vector<unsigned> getShuffleMask(const ShuffleVectorInst *SVI) {
|
|
unsigned NElts = SVI->getType()->getNumElements();
|
|
if (isa<ConstantAggregateZero>(SVI->getOperand(2)))
|
|
return std::vector<unsigned>(NElts, 0);
|
|
if (isa<UndefValue>(SVI->getOperand(2)))
|
|
return std::vector<unsigned>(NElts, 2*NElts);
|
|
|
|
std::vector<unsigned> Result;
|
|
const ConstantVector *CP = cast<ConstantVector>(SVI->getOperand(2));
|
|
for (User::const_op_iterator i = CP->op_begin(), e = CP->op_end(); i!=e; ++i)
|
|
if (isa<UndefValue>(*i))
|
|
Result.push_back(NElts*2); // undef -> 8
|
|
else
|
|
Result.push_back(cast<ConstantInt>(*i)->getZExtValue());
|
|
return Result;
|
|
}
|
|
|
|
/// FindScalarElement - Given a vector and an element number, see if the scalar
|
|
/// value is already around as a register, for example if it were inserted then
|
|
/// extracted from the vector.
|
|
static Value *FindScalarElement(Value *V, unsigned EltNo) {
|
|
assert(isa<VectorType>(V->getType()) && "Not looking at a vector?");
|
|
const VectorType *PTy = cast<VectorType>(V->getType());
|
|
unsigned Width = PTy->getNumElements();
|
|
if (EltNo >= Width) // Out of range access.
|
|
return UndefValue::get(PTy->getElementType());
|
|
|
|
if (isa<UndefValue>(V))
|
|
return UndefValue::get(PTy->getElementType());
|
|
else if (isa<ConstantAggregateZero>(V))
|
|
return Constant::getNullValue(PTy->getElementType());
|
|
else if (ConstantVector *CP = dyn_cast<ConstantVector>(V))
|
|
return CP->getOperand(EltNo);
|
|
else if (InsertElementInst *III = dyn_cast<InsertElementInst>(V)) {
|
|
// If this is an insert to a variable element, we don't know what it is.
|
|
if (!isa<ConstantInt>(III->getOperand(2)))
|
|
return 0;
|
|
unsigned IIElt = cast<ConstantInt>(III->getOperand(2))->getZExtValue();
|
|
|
|
// If this is an insert to the element we are looking for, return the
|
|
// inserted value.
|
|
if (EltNo == IIElt)
|
|
return III->getOperand(1);
|
|
|
|
// Otherwise, the insertelement doesn't modify the value, recurse on its
|
|
// vector input.
|
|
return FindScalarElement(III->getOperand(0), EltNo);
|
|
} else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(V)) {
|
|
unsigned LHSWidth =
|
|
cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements();
|
|
unsigned InEl = getShuffleMask(SVI)[EltNo];
|
|
if (InEl < LHSWidth)
|
|
return FindScalarElement(SVI->getOperand(0), InEl);
|
|
else if (InEl < LHSWidth*2)
|
|
return FindScalarElement(SVI->getOperand(1), InEl - LHSWidth);
|
|
else
|
|
return UndefValue::get(PTy->getElementType());
|
|
}
|
|
|
|
// Otherwise, we don't know.
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
|
|
// If vector val is undef, replace extract with scalar undef.
|
|
if (isa<UndefValue>(EI.getOperand(0)))
|
|
return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
|
|
|
|
// If vector val is constant 0, replace extract with scalar 0.
|
|
if (isa<ConstantAggregateZero>(EI.getOperand(0)))
|
|
return ReplaceInstUsesWith(EI, Constant::getNullValue(EI.getType()));
|
|
|
|
if (ConstantVector *C = dyn_cast<ConstantVector>(EI.getOperand(0))) {
|
|
// If vector val is constant with all elements the same, replace EI with
|
|
// that element. When the elements are not identical, we cannot replace yet
|
|
// (we do that below, but only when the index is constant).
|
|
Constant *op0 = C->getOperand(0);
|
|
for (unsigned i = 1; i < C->getNumOperands(); ++i)
|
|
if (C->getOperand(i) != op0) {
|
|
op0 = 0;
|
|
break;
|
|
}
|
|
if (op0)
|
|
return ReplaceInstUsesWith(EI, op0);
|
|
}
|
|
|
|
// If extracting a specified index from the vector, see if we can recursively
|
|
// find a previously computed scalar that was inserted into the vector.
|
|
if (ConstantInt *IdxC = dyn_cast<ConstantInt>(EI.getOperand(1))) {
|
|
unsigned IndexVal = IdxC->getZExtValue();
|
|
unsigned VectorWidth =
|
|
cast<VectorType>(EI.getOperand(0)->getType())->getNumElements();
|
|
|
|
// If this is extracting an invalid index, turn this into undef, to avoid
|
|
// crashing the code below.
|
|
if (IndexVal >= VectorWidth)
|
|
return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
|
|
|
|
// This instruction only demands the single element from the input vector.
|
|
// If the input vector has a single use, simplify it based on this use
|
|
// property.
|
|
if (EI.getOperand(0)->hasOneUse() && VectorWidth != 1) {
|
|
APInt UndefElts(VectorWidth, 0);
|
|
APInt DemandedMask(VectorWidth, 1 << IndexVal);
|
|
if (Value *V = SimplifyDemandedVectorElts(EI.getOperand(0),
|
|
DemandedMask, UndefElts)) {
|
|
EI.setOperand(0, V);
|
|
return &EI;
|
|
}
|
|
}
|
|
|
|
if (Value *Elt = FindScalarElement(EI.getOperand(0), IndexVal))
|
|
return ReplaceInstUsesWith(EI, Elt);
|
|
|
|
// If the this extractelement is directly using a bitcast from a vector of
|
|
// the same number of elements, see if we can find the source element from
|
|
// it. In this case, we will end up needing to bitcast the scalars.
|
|
if (BitCastInst *BCI = dyn_cast<BitCastInst>(EI.getOperand(0))) {
|
|
if (const VectorType *VT =
|
|
dyn_cast<VectorType>(BCI->getOperand(0)->getType()))
|
|
if (VT->getNumElements() == VectorWidth)
|
|
if (Value *Elt = FindScalarElement(BCI->getOperand(0), IndexVal))
|
|
return new BitCastInst(Elt, EI.getType());
|
|
}
|
|
}
|
|
|
|
if (Instruction *I = dyn_cast<Instruction>(EI.getOperand(0))) {
|
|
if (I->hasOneUse()) {
|
|
// Push extractelement into predecessor operation if legal and
|
|
// profitable to do so
|
|
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
|
|
bool isConstantElt = isa<ConstantInt>(EI.getOperand(1));
|
|
if (CheapToScalarize(BO, isConstantElt)) {
|
|
ExtractElementInst *newEI0 =
|
|
new ExtractElementInst(BO->getOperand(0), EI.getOperand(1),
|
|
EI.getName()+".lhs");
|
|
ExtractElementInst *newEI1 =
|
|
new ExtractElementInst(BO->getOperand(1), EI.getOperand(1),
|
|
EI.getName()+".rhs");
|
|
InsertNewInstBefore(newEI0, EI);
|
|
InsertNewInstBefore(newEI1, EI);
|
|
return BinaryOperator::Create(BO->getOpcode(), newEI0, newEI1);
|
|
}
|
|
} else if (isa<LoadInst>(I)) {
|
|
unsigned AS =
|
|
cast<PointerType>(I->getOperand(0)->getType())->getAddressSpace();
|
|
Value *Ptr = InsertBitCastBefore(I->getOperand(0),
|
|
PointerType::get(EI.getType(), AS),EI);
|
|
GetElementPtrInst *GEP =
|
|
GetElementPtrInst::Create(Ptr, EI.getOperand(1), I->getName()+".gep");
|
|
InsertNewInstBefore(GEP, EI);
|
|
return new LoadInst(GEP);
|
|
}
|
|
}
|
|
if (InsertElementInst *IE = dyn_cast<InsertElementInst>(I)) {
|
|
// Extracting the inserted element?
|
|
if (IE->getOperand(2) == EI.getOperand(1))
|
|
return ReplaceInstUsesWith(EI, IE->getOperand(1));
|
|
// If the inserted and extracted elements are constants, they must not
|
|
// be the same value, extract from the pre-inserted value instead.
|
|
if (isa<Constant>(IE->getOperand(2)) &&
|
|
isa<Constant>(EI.getOperand(1))) {
|
|
AddUsesToWorkList(EI);
|
|
EI.setOperand(0, IE->getOperand(0));
|
|
return &EI;
|
|
}
|
|
} else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I)) {
|
|
// If this is extracting an element from a shufflevector, figure out where
|
|
// it came from and extract from the appropriate input element instead.
|
|
if (ConstantInt *Elt = dyn_cast<ConstantInt>(EI.getOperand(1))) {
|
|
unsigned SrcIdx = getShuffleMask(SVI)[Elt->getZExtValue()];
|
|
Value *Src;
|
|
unsigned LHSWidth =
|
|
cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements();
|
|
|
|
if (SrcIdx < LHSWidth)
|
|
Src = SVI->getOperand(0);
|
|
else if (SrcIdx < LHSWidth*2) {
|
|
SrcIdx -= LHSWidth;
|
|
Src = SVI->getOperand(1);
|
|
} else {
|
|
return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
|
|
}
|
|
return new ExtractElementInst(Src, SrcIdx);
|
|
}
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/// CollectSingleShuffleElements - If V is a shuffle of values that ONLY returns
|
|
/// elements from either LHS or RHS, return the shuffle mask and true.
|
|
/// Otherwise, return false.
|
|
static bool CollectSingleShuffleElements(Value *V, Value *LHS, Value *RHS,
|
|
std::vector<Constant*> &Mask) {
|
|
assert(V->getType() == LHS->getType() && V->getType() == RHS->getType() &&
|
|
"Invalid CollectSingleShuffleElements");
|
|
unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
|
|
|
|
if (isa<UndefValue>(V)) {
|
|
Mask.assign(NumElts, UndefValue::get(Type::Int32Ty));
|
|
return true;
|
|
} else if (V == LHS) {
|
|
for (unsigned i = 0; i != NumElts; ++i)
|
|
Mask.push_back(ConstantInt::get(Type::Int32Ty, i));
|
|
return true;
|
|
} else if (V == RHS) {
|
|
for (unsigned i = 0; i != NumElts; ++i)
|
|
Mask.push_back(ConstantInt::get(Type::Int32Ty, i+NumElts));
|
|
return true;
|
|
} else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
|
|
// If this is an insert of an extract from some other vector, include it.
|
|
Value *VecOp = IEI->getOperand(0);
|
|
Value *ScalarOp = IEI->getOperand(1);
|
|
Value *IdxOp = IEI->getOperand(2);
|
|
|
|
if (!isa<ConstantInt>(IdxOp))
|
|
return false;
|
|
unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
|
|
|
|
if (isa<UndefValue>(ScalarOp)) { // inserting undef into vector.
|
|
// Okay, we can handle this if the vector we are insertinting into is
|
|
// transitively ok.
|
|
if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
|
|
// If so, update the mask to reflect the inserted undef.
|
|
Mask[InsertedIdx] = UndefValue::get(Type::Int32Ty);
|
|
return true;
|
|
}
|
|
} else if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)){
|
|
if (isa<ConstantInt>(EI->getOperand(1)) &&
|
|
EI->getOperand(0)->getType() == V->getType()) {
|
|
unsigned ExtractedIdx =
|
|
cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
|
|
|
|
// This must be extracting from either LHS or RHS.
|
|
if (EI->getOperand(0) == LHS || EI->getOperand(0) == RHS) {
|
|
// Okay, we can handle this if the vector we are insertinting into is
|
|
// transitively ok.
|
|
if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
|
|
// If so, update the mask to reflect the inserted value.
|
|
if (EI->getOperand(0) == LHS) {
|
|
Mask[InsertedIdx % NumElts] =
|
|
ConstantInt::get(Type::Int32Ty, ExtractedIdx);
|
|
} else {
|
|
assert(EI->getOperand(0) == RHS);
|
|
Mask[InsertedIdx % NumElts] =
|
|
ConstantInt::get(Type::Int32Ty, ExtractedIdx+NumElts);
|
|
|
|
}
|
|
return true;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
// TODO: Handle shufflevector here!
|
|
|
|
return false;
|
|
}
|
|
|
|
/// CollectShuffleElements - We are building a shuffle of V, using RHS as the
|
|
/// RHS of the shuffle instruction, if it is not null. Return a shuffle mask
|
|
/// that computes V and the LHS value of the shuffle.
|
|
static Value *CollectShuffleElements(Value *V, std::vector<Constant*> &Mask,
|
|
Value *&RHS) {
|
|
assert(isa<VectorType>(V->getType()) &&
|
|
(RHS == 0 || V->getType() == RHS->getType()) &&
|
|
"Invalid shuffle!");
|
|
unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
|
|
|
|
if (isa<UndefValue>(V)) {
|
|
Mask.assign(NumElts, UndefValue::get(Type::Int32Ty));
|
|
return V;
|
|
} else if (isa<ConstantAggregateZero>(V)) {
|
|
Mask.assign(NumElts, ConstantInt::get(Type::Int32Ty, 0));
|
|
return V;
|
|
} else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
|
|
// If this is an insert of an extract from some other vector, include it.
|
|
Value *VecOp = IEI->getOperand(0);
|
|
Value *ScalarOp = IEI->getOperand(1);
|
|
Value *IdxOp = IEI->getOperand(2);
|
|
|
|
if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
|
|
if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
|
|
EI->getOperand(0)->getType() == V->getType()) {
|
|
unsigned ExtractedIdx =
|
|
cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
|
|
unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
|
|
|
|
// Either the extracted from or inserted into vector must be RHSVec,
|
|
// otherwise we'd end up with a shuffle of three inputs.
|
|
if (EI->getOperand(0) == RHS || RHS == 0) {
|
|
RHS = EI->getOperand(0);
|
|
Value *V = CollectShuffleElements(VecOp, Mask, RHS);
|
|
Mask[InsertedIdx % NumElts] =
|
|
ConstantInt::get(Type::Int32Ty, NumElts+ExtractedIdx);
|
|
return V;
|
|
}
|
|
|
|
if (VecOp == RHS) {
|
|
Value *V = CollectShuffleElements(EI->getOperand(0), Mask, RHS);
|
|
// Everything but the extracted element is replaced with the RHS.
|
|
for (unsigned i = 0; i != NumElts; ++i) {
|
|
if (i != InsertedIdx)
|
|
Mask[i] = ConstantInt::get(Type::Int32Ty, NumElts+i);
|
|
}
|
|
return V;
|
|
}
|
|
|
|
// If this insertelement is a chain that comes from exactly these two
|
|
// vectors, return the vector and the effective shuffle.
|
|
if (CollectSingleShuffleElements(IEI, EI->getOperand(0), RHS, Mask))
|
|
return EI->getOperand(0);
|
|
|
|
}
|
|
}
|
|
}
|
|
// TODO: Handle shufflevector here!
|
|
|
|
// Otherwise, can't do anything fancy. Return an identity vector.
|
|
for (unsigned i = 0; i != NumElts; ++i)
|
|
Mask.push_back(ConstantInt::get(Type::Int32Ty, i));
|
|
return V;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
|
|
Value *VecOp = IE.getOperand(0);
|
|
Value *ScalarOp = IE.getOperand(1);
|
|
Value *IdxOp = IE.getOperand(2);
|
|
|
|
// Inserting an undef or into an undefined place, remove this.
|
|
if (isa<UndefValue>(ScalarOp) || isa<UndefValue>(IdxOp))
|
|
ReplaceInstUsesWith(IE, VecOp);
|
|
|
|
// If the inserted element was extracted from some other vector, and if the
|
|
// indexes are constant, try to turn this into a shufflevector operation.
|
|
if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
|
|
if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
|
|
EI->getOperand(0)->getType() == IE.getType()) {
|
|
unsigned NumVectorElts = IE.getType()->getNumElements();
|
|
unsigned ExtractedIdx =
|
|
cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
|
|
unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
|
|
|
|
if (ExtractedIdx >= NumVectorElts) // Out of range extract.
|
|
return ReplaceInstUsesWith(IE, VecOp);
|
|
|
|
if (InsertedIdx >= NumVectorElts) // Out of range insert.
|
|
return ReplaceInstUsesWith(IE, UndefValue::get(IE.getType()));
|
|
|
|
// If we are extracting a value from a vector, then inserting it right
|
|
// back into the same place, just use the input vector.
|
|
if (EI->getOperand(0) == VecOp && ExtractedIdx == InsertedIdx)
|
|
return ReplaceInstUsesWith(IE, VecOp);
|
|
|
|
// We could theoretically do this for ANY input. However, doing so could
|
|
// turn chains of insertelement instructions into a chain of shufflevector
|
|
// instructions, and right now we do not merge shufflevectors. As such,
|
|
// only do this in a situation where it is clear that there is benefit.
|
|
if (isa<UndefValue>(VecOp) || isa<ConstantAggregateZero>(VecOp)) {
|
|
// Turn this into shuffle(EIOp0, VecOp, Mask). The result has all of
|
|
// the values of VecOp, except then one read from EIOp0.
|
|
// Build a new shuffle mask.
|
|
std::vector<Constant*> Mask;
|
|
if (isa<UndefValue>(VecOp))
|
|
Mask.assign(NumVectorElts, UndefValue::get(Type::Int32Ty));
|
|
else {
|
|
assert(isa<ConstantAggregateZero>(VecOp) && "Unknown thing");
|
|
Mask.assign(NumVectorElts, ConstantInt::get(Type::Int32Ty,
|
|
NumVectorElts));
|
|
}
|
|
Mask[InsertedIdx] = ConstantInt::get(Type::Int32Ty, ExtractedIdx);
|
|
return new ShuffleVectorInst(EI->getOperand(0), VecOp,
|
|
ConstantVector::get(Mask));
|
|
}
|
|
|
|
// If this insertelement isn't used by some other insertelement, turn it
|
|
// (and any insertelements it points to), into one big shuffle.
|
|
if (!IE.hasOneUse() || !isa<InsertElementInst>(IE.use_back())) {
|
|
std::vector<Constant*> Mask;
|
|
Value *RHS = 0;
|
|
Value *LHS = CollectShuffleElements(&IE, Mask, RHS);
|
|
if (RHS == 0) RHS = UndefValue::get(LHS->getType());
|
|
// We now have a shuffle of LHS, RHS, Mask.
|
|
return new ShuffleVectorInst(LHS, RHS, ConstantVector::get(Mask));
|
|
}
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
|
|
Value *LHS = SVI.getOperand(0);
|
|
Value *RHS = SVI.getOperand(1);
|
|
std::vector<unsigned> Mask = getShuffleMask(&SVI);
|
|
|
|
bool MadeChange = false;
|
|
|
|
// Undefined shuffle mask -> undefined value.
|
|
if (isa<UndefValue>(SVI.getOperand(2)))
|
|
return ReplaceInstUsesWith(SVI, UndefValue::get(SVI.getType()));
|
|
|
|
unsigned VWidth = cast<VectorType>(SVI.getType())->getNumElements();
|
|
|
|
if (VWidth != cast<VectorType>(LHS->getType())->getNumElements())
|
|
return 0;
|
|
|
|
APInt UndefElts(VWidth, 0);
|
|
APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
|
|
if (SimplifyDemandedVectorElts(&SVI, AllOnesEltMask, UndefElts)) {
|
|
LHS = SVI.getOperand(0);
|
|
RHS = SVI.getOperand(1);
|
|
MadeChange = true;
|
|
}
|
|
|
|
// Canonicalize shuffle(x ,x,mask) -> shuffle(x, undef,mask')
|
|
// Canonicalize shuffle(undef,x,mask) -> shuffle(x, undef,mask').
|
|
if (LHS == RHS || isa<UndefValue>(LHS)) {
|
|
if (isa<UndefValue>(LHS) && LHS == RHS) {
|
|
// shuffle(undef,undef,mask) -> undef.
|
|
return ReplaceInstUsesWith(SVI, LHS);
|
|
}
|
|
|
|
// Remap any references to RHS to use LHS.
|
|
std::vector<Constant*> Elts;
|
|
for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
|
|
if (Mask[i] >= 2*e)
|
|
Elts.push_back(UndefValue::get(Type::Int32Ty));
|
|
else {
|
|
if ((Mask[i] >= e && isa<UndefValue>(RHS)) ||
|
|
(Mask[i] < e && isa<UndefValue>(LHS))) {
|
|
Mask[i] = 2*e; // Turn into undef.
|
|
Elts.push_back(UndefValue::get(Type::Int32Ty));
|
|
} else {
|
|
Mask[i] = Mask[i] % e; // Force to LHS.
|
|
Elts.push_back(ConstantInt::get(Type::Int32Ty, Mask[i]));
|
|
}
|
|
}
|
|
}
|
|
SVI.setOperand(0, SVI.getOperand(1));
|
|
SVI.setOperand(1, UndefValue::get(RHS->getType()));
|
|
SVI.setOperand(2, ConstantVector::get(Elts));
|
|
LHS = SVI.getOperand(0);
|
|
RHS = SVI.getOperand(1);
|
|
MadeChange = true;
|
|
}
|
|
|
|
// Analyze the shuffle, are the LHS or RHS and identity shuffles?
|
|
bool isLHSID = true, isRHSID = true;
|
|
|
|
for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
|
|
if (Mask[i] >= e*2) continue; // Ignore undef values.
|
|
// Is this an identity shuffle of the LHS value?
|
|
isLHSID &= (Mask[i] == i);
|
|
|
|
// Is this an identity shuffle of the RHS value?
|
|
isRHSID &= (Mask[i]-e == i);
|
|
}
|
|
|
|
// Eliminate identity shuffles.
|
|
if (isLHSID) return ReplaceInstUsesWith(SVI, LHS);
|
|
if (isRHSID) return ReplaceInstUsesWith(SVI, RHS);
|
|
|
|
// If the LHS is a shufflevector itself, see if we can combine it with this
|
|
// one without producing an unusual shuffle. Here we are really conservative:
|
|
// we are absolutely afraid of producing a shuffle mask not in the input
|
|
// program, because the code gen may not be smart enough to turn a merged
|
|
// shuffle into two specific shuffles: it may produce worse code. As such,
|
|
// we only merge two shuffles if the result is one of the two input shuffle
|
|
// masks. In this case, merging the shuffles just removes one instruction,
|
|
// which we know is safe. This is good for things like turning:
|
|
// (splat(splat)) -> splat.
|
|
if (ShuffleVectorInst *LHSSVI = dyn_cast<ShuffleVectorInst>(LHS)) {
|
|
if (isa<UndefValue>(RHS)) {
|
|
std::vector<unsigned> LHSMask = getShuffleMask(LHSSVI);
|
|
|
|
std::vector<unsigned> NewMask;
|
|
for (unsigned i = 0, e = Mask.size(); i != e; ++i)
|
|
if (Mask[i] >= 2*e)
|
|
NewMask.push_back(2*e);
|
|
else
|
|
NewMask.push_back(LHSMask[Mask[i]]);
|
|
|
|
// If the result mask is equal to the src shuffle or this shuffle mask, do
|
|
// the replacement.
|
|
if (NewMask == LHSMask || NewMask == Mask) {
|
|
unsigned LHSInNElts =
|
|
cast<VectorType>(LHSSVI->getOperand(0)->getType())->getNumElements();
|
|
std::vector<Constant*> Elts;
|
|
for (unsigned i = 0, e = NewMask.size(); i != e; ++i) {
|
|
if (NewMask[i] >= LHSInNElts*2) {
|
|
Elts.push_back(UndefValue::get(Type::Int32Ty));
|
|
} else {
|
|
Elts.push_back(ConstantInt::get(Type::Int32Ty, NewMask[i]));
|
|
}
|
|
}
|
|
return new ShuffleVectorInst(LHSSVI->getOperand(0),
|
|
LHSSVI->getOperand(1),
|
|
ConstantVector::get(Elts));
|
|
}
|
|
}
|
|
}
|
|
|
|
return MadeChange ? &SVI : 0;
|
|
}
|
|
|
|
|
|
|
|
|
|
/// TryToSinkInstruction - Try to move the specified instruction from its
|
|
/// current block into the beginning of DestBlock, which can only happen if it's
|
|
/// safe to move the instruction past all of the instructions between it and the
|
|
/// end of its block.
|
|
static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
|
|
assert(I->hasOneUse() && "Invariants didn't hold!");
|
|
|
|
// Cannot move control-flow-involving, volatile loads, vaarg, etc.
|
|
if (isa<PHINode>(I) || I->mayWriteToMemory() || isa<TerminatorInst>(I))
|
|
return false;
|
|
|
|
// Do not sink alloca instructions out of the entry block.
|
|
if (isa<AllocaInst>(I) && I->getParent() ==
|
|
&DestBlock->getParent()->getEntryBlock())
|
|
return false;
|
|
|
|
// We can only sink load instructions if there is nothing between the load and
|
|
// the end of block that could change the value.
|
|
if (I->mayReadFromMemory()) {
|
|
for (BasicBlock::iterator Scan = I, E = I->getParent()->end();
|
|
Scan != E; ++Scan)
|
|
if (Scan->mayWriteToMemory())
|
|
return false;
|
|
}
|
|
|
|
BasicBlock::iterator InsertPos = DestBlock->getFirstNonPHI();
|
|
|
|
I->moveBefore(InsertPos);
|
|
++NumSunkInst;
|
|
return true;
|
|
}
|
|
|
|
|
|
/// AddReachableCodeToWorklist - Walk the function in depth-first order, adding
|
|
/// all reachable code to the worklist.
|
|
///
|
|
/// This has a couple of tricks to make the code faster and more powerful. In
|
|
/// particular, we constant fold and DCE instructions as we go, to avoid adding
|
|
/// them to the worklist (this significantly speeds up instcombine on code where
|
|
/// many instructions are dead or constant). Additionally, if we find a branch
|
|
/// whose condition is a known constant, we only visit the reachable successors.
|
|
///
|
|
static void AddReachableCodeToWorklist(BasicBlock *BB,
|
|
SmallPtrSet<BasicBlock*, 64> &Visited,
|
|
InstCombiner &IC,
|
|
const TargetData *TD) {
|
|
SmallVector<BasicBlock*, 256> Worklist;
|
|
Worklist.push_back(BB);
|
|
|
|
while (!Worklist.empty()) {
|
|
BB = Worklist.back();
|
|
Worklist.pop_back();
|
|
|
|
// We have now visited this block! If we've already been here, ignore it.
|
|
if (!Visited.insert(BB)) continue;
|
|
|
|
DbgInfoIntrinsic *DBI_Prev = NULL;
|
|
for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
|
|
Instruction *Inst = BBI++;
|
|
|
|
// DCE instruction if trivially dead.
|
|
if (isInstructionTriviallyDead(Inst)) {
|
|
++NumDeadInst;
|
|
DOUT << "IC: DCE: " << *Inst;
|
|
Inst->eraseFromParent();
|
|
continue;
|
|
}
|
|
|
|
// ConstantProp instruction if trivially constant.
|
|
if (Constant *C = ConstantFoldInstruction(Inst, TD)) {
|
|
DOUT << "IC: ConstFold to: " << *C << " from: " << *Inst;
|
|
Inst->replaceAllUsesWith(C);
|
|
++NumConstProp;
|
|
Inst->eraseFromParent();
|
|
continue;
|
|
}
|
|
|
|
// If there are two consecutive llvm.dbg.stoppoint calls then
|
|
// it is likely that the optimizer deleted code in between these
|
|
// two intrinsics.
|
|
DbgInfoIntrinsic *DBI_Next = dyn_cast<DbgInfoIntrinsic>(Inst);
|
|
if (DBI_Next) {
|
|
if (DBI_Prev
|
|
&& DBI_Prev->getIntrinsicID() == llvm::Intrinsic::dbg_stoppoint
|
|
&& DBI_Next->getIntrinsicID() == llvm::Intrinsic::dbg_stoppoint) {
|
|
IC.RemoveFromWorkList(DBI_Prev);
|
|
DBI_Prev->eraseFromParent();
|
|
}
|
|
DBI_Prev = DBI_Next;
|
|
} else {
|
|
DBI_Prev = 0;
|
|
}
|
|
|
|
IC.AddToWorkList(Inst);
|
|
}
|
|
|
|
// Recursively visit successors. If this is a branch or switch on a
|
|
// constant, only visit the reachable successor.
|
|
TerminatorInst *TI = BB->getTerminator();
|
|
if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
|
|
if (BI->isConditional() && isa<ConstantInt>(BI->getCondition())) {
|
|
bool CondVal = cast<ConstantInt>(BI->getCondition())->getZExtValue();
|
|
BasicBlock *ReachableBB = BI->getSuccessor(!CondVal);
|
|
Worklist.push_back(ReachableBB);
|
|
continue;
|
|
}
|
|
} else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
|
|
if (ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition())) {
|
|
// See if this is an explicit destination.
|
|
for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i)
|
|
if (SI->getCaseValue(i) == Cond) {
|
|
BasicBlock *ReachableBB = SI->getSuccessor(i);
|
|
Worklist.push_back(ReachableBB);
|
|
continue;
|
|
}
|
|
|
|
// Otherwise it is the default destination.
|
|
Worklist.push_back(SI->getSuccessor(0));
|
|
continue;
|
|
}
|
|
}
|
|
|
|
for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
|
|
Worklist.push_back(TI->getSuccessor(i));
|
|
}
|
|
}
|
|
|
|
bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
|
|
bool Changed = false;
|
|
TD = &getAnalysis<TargetData>();
|
|
|
|
DEBUG(DOUT << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
|
|
<< F.getNameStr() << "\n");
|
|
|
|
{
|
|
// Do a depth-first traversal of the function, populate the worklist with
|
|
// the reachable instructions. Ignore blocks that are not reachable. Keep
|
|
// track of which blocks we visit.
|
|
SmallPtrSet<BasicBlock*, 64> Visited;
|
|
AddReachableCodeToWorklist(F.begin(), Visited, *this, TD);
|
|
|
|
// Do a quick scan over the function. If we find any blocks that are
|
|
// unreachable, remove any instructions inside of them. This prevents
|
|
// the instcombine code from having to deal with some bad special cases.
|
|
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
|
|
if (!Visited.count(BB)) {
|
|
Instruction *Term = BB->getTerminator();
|
|
while (Term != BB->begin()) { // Remove instrs bottom-up
|
|
BasicBlock::iterator I = Term; --I;
|
|
|
|
DOUT << "IC: DCE: " << *I;
|
|
++NumDeadInst;
|
|
|
|
if (!I->use_empty())
|
|
I->replaceAllUsesWith(UndefValue::get(I->getType()));
|
|
I->eraseFromParent();
|
|
Changed = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
while (!Worklist.empty()) {
|
|
Instruction *I = RemoveOneFromWorkList();
|
|
if (I == 0) continue; // skip null values.
|
|
|
|
// Check to see if we can DCE the instruction.
|
|
if (isInstructionTriviallyDead(I)) {
|
|
// Add operands to the worklist.
|
|
if (I->getNumOperands() < 4)
|
|
AddUsesToWorkList(*I);
|
|
++NumDeadInst;
|
|
|
|
DOUT << "IC: DCE: " << *I;
|
|
|
|
I->eraseFromParent();
|
|
RemoveFromWorkList(I);
|
|
Changed = true;
|
|
continue;
|
|
}
|
|
|
|
// Instruction isn't dead, see if we can constant propagate it.
|
|
if (Constant *C = ConstantFoldInstruction(I, TD)) {
|
|
DOUT << "IC: ConstFold to: " << *C << " from: " << *I;
|
|
|
|
// Add operands to the worklist.
|
|
AddUsesToWorkList(*I);
|
|
ReplaceInstUsesWith(*I, C);
|
|
|
|
++NumConstProp;
|
|
I->eraseFromParent();
|
|
RemoveFromWorkList(I);
|
|
Changed = true;
|
|
continue;
|
|
}
|
|
|
|
if (TD && I->getType()->getTypeID() == Type::VoidTyID) {
|
|
// See if we can constant fold its operands.
|
|
for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i)
|
|
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(i))
|
|
if (Constant *NewC = ConstantFoldConstantExpression(CE, TD))
|
|
if (NewC != CE) {
|
|
i->set(NewC);
|
|
Changed = true;
|
|
}
|
|
}
|
|
|
|
// See if we can trivially sink this instruction to a successor basic block.
|
|
if (I->hasOneUse()) {
|
|
BasicBlock *BB = I->getParent();
|
|
BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent();
|
|
if (UserParent != BB) {
|
|
bool UserIsSuccessor = false;
|
|
// See if the user is one of our successors.
|
|
for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
|
|
if (*SI == UserParent) {
|
|
UserIsSuccessor = true;
|
|
break;
|
|
}
|
|
|
|
// If the user is one of our immediate successors, and if that successor
|
|
// only has us as a predecessors (we'd have to split the critical edge
|
|
// otherwise), we can keep going.
|
|
if (UserIsSuccessor && !isa<PHINode>(I->use_back()) &&
|
|
next(pred_begin(UserParent)) == pred_end(UserParent))
|
|
// Okay, the CFG is simple enough, try to sink this instruction.
|
|
Changed |= TryToSinkInstruction(I, UserParent);
|
|
}
|
|
}
|
|
|
|
// Now that we have an instruction, try combining it to simplify it...
|
|
#ifndef NDEBUG
|
|
std::string OrigI;
|
|
#endif
|
|
DEBUG(std::ostringstream SS; I->print(SS); OrigI = SS.str(););
|
|
if (Instruction *Result = visit(*I)) {
|
|
++NumCombined;
|
|
// Should we replace the old instruction with a new one?
|
|
if (Result != I) {
|
|
DOUT << "IC: Old = " << *I
|
|
<< " New = " << *Result;
|
|
|
|
// Everything uses the new instruction now.
|
|
I->replaceAllUsesWith(Result);
|
|
|
|
// Push the new instruction and any users onto the worklist.
|
|
AddToWorkList(Result);
|
|
AddUsersToWorkList(*Result);
|
|
|
|
// Move the name to the new instruction first.
|
|
Result->takeName(I);
|
|
|
|
// Insert the new instruction into the basic block...
|
|
BasicBlock *InstParent = I->getParent();
|
|
BasicBlock::iterator InsertPos = I;
|
|
|
|
if (!isa<PHINode>(Result)) // If combining a PHI, don't insert
|
|
while (isa<PHINode>(InsertPos)) // middle of a block of PHIs.
|
|
++InsertPos;
|
|
|
|
InstParent->getInstList().insert(InsertPos, Result);
|
|
|
|
// Make sure that we reprocess all operands now that we reduced their
|
|
// use counts.
|
|
AddUsesToWorkList(*I);
|
|
|
|
// Instructions can end up on the worklist more than once. Make sure
|
|
// we do not process an instruction that has been deleted.
|
|
RemoveFromWorkList(I);
|
|
|
|
// Erase the old instruction.
|
|
InstParent->getInstList().erase(I);
|
|
} else {
|
|
#ifndef NDEBUG
|
|
DOUT << "IC: Mod = " << OrigI
|
|
<< " New = " << *I;
|
|
#endif
|
|
|
|
// If the instruction was modified, it's possible that it is now dead.
|
|
// if so, remove it.
|
|
if (isInstructionTriviallyDead(I)) {
|
|
// Make sure we process all operands now that we are reducing their
|
|
// use counts.
|
|
AddUsesToWorkList(*I);
|
|
|
|
// Instructions may end up in the worklist more than once. Erase all
|
|
// occurrences of this instruction.
|
|
RemoveFromWorkList(I);
|
|
I->eraseFromParent();
|
|
} else {
|
|
AddToWorkList(I);
|
|
AddUsersToWorkList(*I);
|
|
}
|
|
}
|
|
Changed = true;
|
|
}
|
|
}
|
|
|
|
assert(WorklistMap.empty() && "Worklist empty, but map not?");
|
|
|
|
// Do an explicit clear, this shrinks the map if needed.
|
|
WorklistMap.clear();
|
|
return Changed;
|
|
}
|
|
|
|
|
|
bool InstCombiner::runOnFunction(Function &F) {
|
|
MustPreserveLCSSA = mustPreserveAnalysisID(LCSSAID);
|
|
|
|
bool EverMadeChange = false;
|
|
|
|
// Iterate while there is work to do.
|
|
unsigned Iteration = 0;
|
|
while (DoOneIteration(F, Iteration++))
|
|
EverMadeChange = true;
|
|
return EverMadeChange;
|
|
}
|
|
|
|
FunctionPass *llvm::createInstructionCombiningPass() {
|
|
return new InstCombiner();
|
|
}
|