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5931c54e85
Match a bunch of idioms for sign extensions, implementing InstCombine/signext.ll git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23428 91177308-0d34-0410-b5e6-96231b3b80d8
5851 lines
239 KiB
C++
5851 lines
239 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 was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source 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 algebraic
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// simplification happens.
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//
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// This pass combines things like:
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// %Y = add int %X, 1
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// %Z = add int %Y, 1
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// into:
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// %Z = add int %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. SetCC instructions are converted from <,>,<=,>= to ==,!= if possible
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// 4. All SetCC 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/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/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/ADT/DepthFirstIterator.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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using namespace llvm;
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using namespace llvm::PatternMatch;
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namespace {
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Statistic<> NumCombined ("instcombine", "Number of insts combined");
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Statistic<> NumConstProp("instcombine", "Number of constant folds");
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Statistic<> NumDeadInst ("instcombine", "Number of dead inst eliminated");
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Statistic<> NumSunkInst ("instcombine", "Number of instructions sunk");
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class InstCombiner : 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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std::vector<Instruction*> WorkList;
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TargetData *TD;
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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(Instruction &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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WorkList.push_back(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 (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
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if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i)))
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WorkList.push_back(Op);
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}
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// removeFromWorkList - remove all instances of I from the worklist.
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void removeFromWorkList(Instruction *I);
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public:
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virtual bool runOnFunction(Function &F);
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.addRequired<TargetData>();
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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 *visitDiv(BinaryOperator &I);
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Instruction *visitRem(BinaryOperator &I);
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Instruction *visitAnd(BinaryOperator &I);
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Instruction *visitOr (BinaryOperator &I);
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Instruction *visitXor(BinaryOperator &I);
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Instruction *visitSetCondInst(SetCondInst &I);
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Instruction *visitSetCondInstWithCastAndCast(SetCondInst &SCI);
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Instruction *FoldGEPSetCC(User *GEPLHS, Value *RHS,
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Instruction::BinaryOps Cond, Instruction &I);
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Instruction *visitShiftInst(ShiftInst &I);
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Instruction *visitCastInst(CastInst &CI);
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Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI,
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Instruction *FI);
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Instruction *visitSelectInst(SelectInst &CI);
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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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// 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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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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WorkList.push_back(New); // Add to worklist
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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(Value *V, const Type *Ty, Instruction &Pos) {
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if (V->getType() == Ty) return V;
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Instruction *C = new CastInst(V, Ty, V->getName(), &Pos);
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WorkList.push_back(C);
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return C;
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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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private:
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/// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
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/// InsertBefore instruction. This is specialized a bit to avoid inserting
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/// casts that are known to not do anything...
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///
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Value *InsertOperandCastBefore(Value *V, const Type *DestTy,
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Instruction *InsertBefore);
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// SimplifyCommutative - This performs a few simplifications for commutative
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// operators.
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bool SimplifyCommutative(BinaryOperator &I);
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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 *OptAndOp(Instruction *Op, ConstantIntegral *OpRHS,
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ConstantIntegral *AndRHS, BinaryOperator &TheAnd);
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Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantIntegral *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 Inside, Instruction &IB);
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};
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RegisterOpt<InstCombiner> X("instcombine", "Combine redundant instructions");
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}
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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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switch (Ty->getTypeID()) {
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case Type::SByteTyID:
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case Type::ShortTyID: return Type::IntTy;
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case Type::UByteTyID:
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case Type::UShortTyID: return Type::UIntTy;
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case Type::FloatTyID: return Type::DoubleTy;
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default: return Ty;
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}
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}
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/// isCast - If the specified operand is a CastInst or a constant expr cast,
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/// return the operand value, otherwise return null.
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static Value *isCast(Value *V) {
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if (CastInst *I = dyn_cast<CastInst>(V))
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return I->getOperand(0);
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else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
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if (CE->getOpcode() == Instruction::Cast)
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return CE->getOperand(0);
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return 0;
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}
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// SimplifyCommutative - This performs a few simplifications for commutative
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// operators:
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//
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// 1. Order operands such that they are listed from right (least complex) to
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// left (most complex). This puts constants before unary operators before
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// binary operators.
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//
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// 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2))
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// 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
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//
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bool InstCombiner::SimplifyCommutative(BinaryOperator &I) {
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bool Changed = false;
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if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
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Changed = !I.swapOperands();
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if (!I.isAssociative()) return Changed;
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Instruction::BinaryOps Opcode = I.getOpcode();
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if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0)))
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if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) {
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if (isa<Constant>(I.getOperand(1))) {
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Constant *Folded = ConstantExpr::get(I.getOpcode(),
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cast<Constant>(I.getOperand(1)),
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cast<Constant>(Op->getOperand(1)));
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I.setOperand(0, Op->getOperand(0));
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I.setOperand(1, Folded);
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return true;
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} else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1)))
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if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) &&
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isOnlyUse(Op) && isOnlyUse(Op1)) {
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Constant *C1 = cast<Constant>(Op->getOperand(1));
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Constant *C2 = cast<Constant>(Op1->getOperand(1));
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// Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2))
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Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2);
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Instruction *New = BinaryOperator::create(Opcode, Op->getOperand(0),
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Op1->getOperand(0),
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Op1->getName(), &I);
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WorkList.push_back(New);
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I.setOperand(0, New);
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I.setOperand(1, Folded);
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return true;
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}
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}
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return Changed;
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}
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// dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
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// if the LHS is a constant zero (which is the 'negate' form).
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//
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static inline Value *dyn_castNegVal(Value *V) {
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if (BinaryOperator::isNeg(V))
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return BinaryOperator::getNegArgument(V);
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// Constants can be considered to be negated values if they can be folded.
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if (ConstantInt *C = dyn_cast<ConstantInt>(V))
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return ConstantExpr::getNeg(C);
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return 0;
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}
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static inline Value *dyn_castNotVal(Value *V) {
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if (BinaryOperator::isNot(V))
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return BinaryOperator::getNotArgument(V);
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// Constants can be considered to be not'ed values...
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if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(V))
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return ConstantExpr::getNot(C);
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return 0;
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}
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// dyn_castFoldableMul - If this value is a multiply that can be folded into
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// other computations (because it has a constant operand), return the
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// non-constant operand of the multiply, and set CST to point to the multiplier.
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// Otherwise, return null.
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//
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static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) {
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if (V->hasOneUse() && V->getType()->isInteger())
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if (Instruction *I = dyn_cast<Instruction>(V)) {
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if (I->getOpcode() == Instruction::Mul)
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if ((CST = dyn_cast<ConstantInt>(I->getOperand(1))))
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return I->getOperand(0);
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if (I->getOpcode() == Instruction::Shl)
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if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) {
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// The multiplier is really 1 << CST.
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Constant *One = ConstantInt::get(V->getType(), 1);
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CST = cast<ConstantInt>(ConstantExpr::getShl(One, CST));
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return I->getOperand(0);
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}
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}
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return 0;
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}
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/// dyn_castGetElementPtr - If this is a getelementptr instruction or constant
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/// expression, return it.
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static User *dyn_castGetElementPtr(Value *V) {
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if (isa<GetElementPtrInst>(V)) return cast<User>(V);
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if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
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if (CE->getOpcode() == Instruction::GetElementPtr)
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return cast<User>(V);
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return false;
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}
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// AddOne, SubOne - Add or subtract a constant one from an integer constant...
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static ConstantInt *AddOne(ConstantInt *C) {
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return cast<ConstantInt>(ConstantExpr::getAdd(C,
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ConstantInt::get(C->getType(), 1)));
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}
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static ConstantInt *SubOne(ConstantInt *C) {
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return cast<ConstantInt>(ConstantExpr::getSub(C,
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ConstantInt::get(C->getType(), 1)));
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}
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/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
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/// this predicate to simplify operations downstream. V and Mask are known to
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/// be the same type.
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static bool MaskedValueIsZero(Value *V, ConstantIntegral *Mask) {
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// Note, we cannot consider 'undef' to be "IsZero" here. The problem is that
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// we cannot optimize based on the assumption that it is zero without changing
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// to to an explicit zero. If we don't change it to zero, other code could
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// optimized based on the contradictory assumption that it is non-zero.
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// Because instcombine aggressively folds operations with undef args anyway,
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// this won't lose us code quality.
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if (Mask->isNullValue())
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return true;
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if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V))
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return ConstantExpr::getAnd(CI, Mask)->isNullValue();
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if (Instruction *I = dyn_cast<Instruction>(V)) {
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switch (I->getOpcode()) {
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case Instruction::And:
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// (X & C1) & C2 == 0 iff C1 & C2 == 0.
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if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(I->getOperand(1)))
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if (ConstantExpr::getAnd(CI, Mask)->isNullValue())
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return true;
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break;
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case Instruction::Or:
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// If the LHS and the RHS are MaskedValueIsZero, the result is also zero.
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return MaskedValueIsZero(I->getOperand(1), Mask) &&
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MaskedValueIsZero(I->getOperand(0), Mask);
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case Instruction::Select:
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// If the T and F values are MaskedValueIsZero, the result is also zero.
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return MaskedValueIsZero(I->getOperand(2), Mask) &&
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MaskedValueIsZero(I->getOperand(1), Mask);
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case Instruction::Cast: {
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const Type *SrcTy = I->getOperand(0)->getType();
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if (SrcTy == Type::BoolTy)
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return (Mask->getRawValue() & 1) == 0;
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if (SrcTy->isInteger()) {
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// (cast <ty> X to int) & C2 == 0 iff <ty> could not have contained C2.
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if (SrcTy->isUnsigned() && // Only handle zero ext.
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ConstantExpr::getCast(Mask, SrcTy)->isNullValue())
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return true;
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// If this is a noop cast, recurse.
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if ((SrcTy->isSigned() && SrcTy->getUnsignedVersion() == I->getType())||
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SrcTy->getSignedVersion() == I->getType()) {
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Constant *NewMask =
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ConstantExpr::getCast(Mask, I->getOperand(0)->getType());
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return MaskedValueIsZero(I->getOperand(0),
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cast<ConstantIntegral>(NewMask));
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}
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}
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break;
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}
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case Instruction::Shl:
|
|
// (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0
|
|
if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
|
|
return MaskedValueIsZero(I->getOperand(0),
|
|
cast<ConstantIntegral>(ConstantExpr::getUShr(Mask, SA)));
|
|
break;
|
|
case Instruction::Shr:
|
|
// (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
|
|
if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
|
|
if (I->getType()->isUnsigned()) {
|
|
Constant *C1 = ConstantIntegral::getAllOnesValue(I->getType());
|
|
C1 = ConstantExpr::getShr(C1, SA);
|
|
C1 = ConstantExpr::getAnd(C1, Mask);
|
|
if (C1->isNullValue())
|
|
return true;
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
// isTrueWhenEqual - Return true if the specified setcondinst instruction is
|
|
// true when both operands are equal...
|
|
//
|
|
static bool isTrueWhenEqual(Instruction &I) {
|
|
return I.getOpcode() == Instruction::SetEQ ||
|
|
I.getOpcode() == Instruction::SetGE ||
|
|
I.getOpcode() == Instruction::SetLE;
|
|
}
|
|
|
|
/// 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>
|
|
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) {
|
|
BasicBlock *BB = Root.getParent();
|
|
|
|
// 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
|
|
TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
|
|
BasicBlock::iterator ARI = &Root; ++ARI;
|
|
BB->getInstList().insert(ARI, TmpLHSI); // 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->getParent()->getInstList().remove(NextLHSI);
|
|
BB->getInstList().insert(ARI, NextLHSI);
|
|
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;
|
|
}
|
|
|
|
|
|
// 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 new ShiftInst(Instruction::Shl, Add.getOperand(0),
|
|
ConstantInt::get(Type::UByteTy, 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 (isa<CastInst>(I)) {
|
|
if (Constant *SOC = dyn_cast<Constant>(SO))
|
|
return ConstantExpr::getCast(SOC, I.getType());
|
|
|
|
return IC->InsertNewInstBefore(new CastInst(SO, I.getType(),
|
|
SO->getName() + ".cast"), 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 (ShiftInst *SI = dyn_cast<ShiftInst>(&I))
|
|
New = new ShiftInst(SI->getOpcode(), Op0, Op1, SO->getName()+".sh");
|
|
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::BoolTy) return 0;
|
|
|
|
Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
|
|
Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
|
|
|
|
return new SelectInst(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 ||
|
|
!isa<Constant>(PN->getIncomingValue(0))) return 0;
|
|
|
|
// Check to see if all of the operands of the PHI are constants. If not, we
|
|
// cannot do the transformation.
|
|
for (unsigned i = 1; i != NumPHIValues; ++i)
|
|
if (!isa<Constant>(PN->getIncomingValue(i)))
|
|
return 0;
|
|
|
|
// Okay, we can do the transformation: create the new PHI node.
|
|
PHINode *NewPN = new PHINode(I.getType(), I.getName());
|
|
I.setName("");
|
|
NewPN->reserveOperandSpace(PN->getNumOperands()/2);
|
|
InsertNewInstBefore(NewPN, *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) {
|
|
Constant *InV = cast<Constant>(PN->getIncomingValue(i));
|
|
NewPN->addIncoming(ConstantExpr::get(I.getOpcode(), InV, C),
|
|
PN->getIncomingBlock(i));
|
|
}
|
|
} else {
|
|
assert(isa<CastInst>(I) && "Unary op should be a cast!");
|
|
const Type *RetTy = I.getType();
|
|
for (unsigned i = 0; i != NumPHIValues; ++i) {
|
|
Constant *InV = cast<Constant>(PN->getIncomingValue(i));
|
|
NewPN->addIncoming(ConstantExpr::getCast(InV, RetTy),
|
|
PN->getIncomingBlock(i));
|
|
}
|
|
}
|
|
return ReplaceInstUsesWith(I, NewPN);
|
|
}
|
|
|
|
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()->isFloatingPoint() && // -0 + +0 = +0, so it's not a noop
|
|
RHSC->isNullValue())
|
|
return ReplaceInstUsesWith(I, LHS);
|
|
|
|
// X + (signbit) --> X ^ signbit
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
|
|
unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
|
|
uint64_t Val = CI->getRawValue() & (1ULL << NumBits)-1;
|
|
if (Val == (1ULL << (NumBits-1)))
|
|
return BinaryOperator::createXor(LHS, RHS);
|
|
}
|
|
|
|
if (isa<PHINode>(LHS))
|
|
if (Instruction *NV = FoldOpIntoPhi(I))
|
|
return NV;
|
|
|
|
ConstantInt *XorRHS;
|
|
Value *XorLHS;
|
|
if (match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) {
|
|
unsigned TySizeBits = I.getType()->getPrimitiveSizeInBits();
|
|
int64_t RHSSExt = cast<ConstantInt>(RHSC)->getSExtValue();
|
|
uint64_t RHSZExt = cast<ConstantInt>(RHSC)->getZExtValue();
|
|
|
|
uint64_t C0080Val = 1ULL << 31;
|
|
int64_t CFF80Val = -C0080Val;
|
|
unsigned Size = 32;
|
|
do {
|
|
if (TySizeBits > Size) {
|
|
bool Found = false;
|
|
// 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 (RHSSExt == CFF80Val) {
|
|
if (XorRHS->getZExtValue() == C0080Val)
|
|
Found = true;
|
|
} else if (RHSZExt == C0080Val) {
|
|
if (XorRHS->getSExtValue() == CFF80Val)
|
|
Found = true;
|
|
}
|
|
if (Found) {
|
|
// This is a sign extend if the top bits are known zero.
|
|
Constant *Mask = ConstantInt::getAllOnesValue(XorLHS->getType());
|
|
Mask = ConstantExpr::getShl(Mask,
|
|
ConstantInt::get(Type::UByteTy, 64-TySizeBits-Size));
|
|
if (!MaskedValueIsZero(XorLHS, cast<ConstantInt>(Mask)))
|
|
Size = 0; // Not a sign ext, but can't be any others either.
|
|
goto FoundSExt;
|
|
}
|
|
}
|
|
Size >>= 1;
|
|
C0080Val >>= Size;
|
|
CFF80Val >>= Size;
|
|
} while (Size >= 8);
|
|
|
|
FoundSExt:
|
|
const Type *MiddleType = 0;
|
|
switch (Size) {
|
|
default: break;
|
|
case 32: MiddleType = Type::IntTy; break;
|
|
case 16: MiddleType = Type::ShortTy; break;
|
|
case 8: MiddleType = Type::SByteTy; break;
|
|
}
|
|
if (MiddleType) {
|
|
Instruction *NewTrunc = new CastInst(XorLHS, MiddleType, "sext");
|
|
InsertNewInstBefore(NewTrunc, I);
|
|
return new CastInst(NewTrunc, I.getType());
|
|
}
|
|
}
|
|
}
|
|
|
|
// 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
|
|
if (Value *V = dyn_castNegVal(LHS))
|
|
return BinaryOperator::createSub(RHS, V);
|
|
|
|
// 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, ConstantExpr::getAdd(C1, C2));
|
|
}
|
|
|
|
// X + X*C --> X * (C+1)
|
|
if (dyn_castFoldableMul(RHS, C2) == LHS)
|
|
return BinaryOperator::createMul(LHS, AddOne(C2));
|
|
|
|
|
|
// (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;
|
|
|
|
if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
|
|
Value *X;
|
|
if (match(LHS, m_Not(m_Value(X)))) { // ~X + C --> (C-1) - X
|
|
Constant *C= ConstantExpr::getSub(CRHS, ConstantInt::get(I.getType(), 1));
|
|
return BinaryOperator::createSub(C, X);
|
|
}
|
|
|
|
// (X & FF00) + xx00 -> (X+xx00) & FF00
|
|
if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) {
|
|
Constant *Anded = ConstantExpr::getAnd(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.
|
|
uint64_t AddRHSV = CRHS->getRawValue();
|
|
|
|
// Form a mask of all bits from the lowest bit added through the top.
|
|
uint64_t AddRHSHighBits = ~((AddRHSV & -AddRHSV)-1);
|
|
AddRHSHighBits &= ~0ULL >> (64-C2->getType()->getPrimitiveSizeInBits());
|
|
|
|
// See if the and mask includes all of these bits.
|
|
uint64_t AddRHSHighBitsAnd = AddRHSHighBits & C2->getRawValue();
|
|
|
|
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;
|
|
}
|
|
|
|
return Changed ? &I : 0;
|
|
}
|
|
|
|
// isSignBit - Return true if the value represented by the constant only has the
|
|
// highest order bit set.
|
|
static bool isSignBit(ConstantInt *CI) {
|
|
unsigned NumBits = CI->getType()->getPrimitiveSizeInBits();
|
|
return (CI->getRawValue() & (~0ULL >> (64-NumBits))) == (1ULL << (NumBits-1));
|
|
}
|
|
|
|
/// RemoveNoopCast - Strip off nonconverting casts from the value.
|
|
///
|
|
static Value *RemoveNoopCast(Value *V) {
|
|
if (CastInst *CI = dyn_cast<CastInst>(V)) {
|
|
const Type *CTy = CI->getType();
|
|
const Type *OpTy = CI->getOperand(0)->getType();
|
|
if (CTy->isInteger() && OpTy->isInteger()) {
|
|
if (CTy->getPrimitiveSizeInBits() == OpTy->getPrimitiveSizeInBits())
|
|
return RemoveNoopCast(CI->getOperand(0));
|
|
} else if (isa<PointerType>(CTy) && isa<PointerType>(OpTy))
|
|
return RemoveNoopCast(CI->getOperand(0));
|
|
}
|
|
return V;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitSub(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
if (Op0 == Op1) // sub X, X -> 0
|
|
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,
|
|
ConstantExpr::getAdd(C, ConstantInt::get(I.getType(), 1)));
|
|
// -((uint)X >> 31) -> ((int)X >> 31)
|
|
// -((int)X >> 31) -> ((uint)X >> 31)
|
|
if (C->isNullValue()) {
|
|
Value *NoopCastedRHS = RemoveNoopCast(Op1);
|
|
if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS))
|
|
if (SI->getOpcode() == Instruction::Shr)
|
|
if (ConstantUInt *CU = dyn_cast<ConstantUInt>(SI->getOperand(1))) {
|
|
const Type *NewTy;
|
|
if (SI->getType()->isSigned())
|
|
NewTy = SI->getType()->getUnsignedVersion();
|
|
else
|
|
NewTy = SI->getType()->getSignedVersion();
|
|
// Check to see if we are shifting out everything but the sign bit.
|
|
if (CU->getValue() == SI->getType()->getPrimitiveSizeInBits()-1) {
|
|
// Ok, the transformation is safe. Insert a cast of the incoming
|
|
// value, then the new shift, then the new cast.
|
|
Instruction *FirstCast = new CastInst(SI->getOperand(0), NewTy,
|
|
SI->getOperand(0)->getName());
|
|
Value *InV = InsertNewInstBefore(FirstCast, I);
|
|
Instruction *NewShift = new ShiftInst(Instruction::Shr, FirstCast,
|
|
CU, SI->getName());
|
|
if (NewShift->getType() == I.getType())
|
|
return NewShift;
|
|
else {
|
|
InV = InsertNewInstBefore(NewShift, I);
|
|
return new CastInst(NewShift, I.getType());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// 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 (isa<PHINode>(Op0))
|
|
if (Instruction *NV = FoldOpIntoPhi(I))
|
|
return NV;
|
|
}
|
|
|
|
if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
|
|
if (Op1I->getOpcode() == Instruction::Add &&
|
|
!Op0->getType()->isFloatingPoint()) {
|
|
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(ConstantExpr::getSub(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()->isFloatingPoint()) {
|
|
// 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);
|
|
}
|
|
|
|
// -(X sdiv C) -> (X sdiv -C)
|
|
if (Op1I->getOpcode() == Instruction::Div)
|
|
if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
|
|
if (CSI->isNullValue())
|
|
if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1)))
|
|
return BinaryOperator::createDiv(Op1I->getOperand(0),
|
|
ConstantExpr::getNeg(DivRHS));
|
|
|
|
// X - X*C --> X * (1-C)
|
|
ConstantInt *C2 = 0;
|
|
if (dyn_castFoldableMul(Op1I, C2) == Op0) {
|
|
Constant *CP1 =
|
|
ConstantExpr::getSub(ConstantInt::get(I.getType(), 1), C2);
|
|
return BinaryOperator::createMul(Op0, CP1);
|
|
}
|
|
}
|
|
}
|
|
|
|
if (!Op0->getType()->isFloatingPoint())
|
|
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)
|
|
Constant *CP1 = ConstantExpr::getSub(C1, ConstantInt::get(I.getType(),1));
|
|
return BinaryOperator::createMul(Op1, CP1);
|
|
}
|
|
|
|
ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2)
|
|
if (X == dyn_castFoldableMul(Op1, C2))
|
|
return BinaryOperator::createMul(Op1, ConstantExpr::getSub(C1, C2));
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/// isSignBitCheck - Given an exploded setcc instruction, return true if it is
|
|
/// really just returns true if the most significant (sign) bit is set.
|
|
static bool isSignBitCheck(unsigned Opcode, Value *LHS, ConstantInt *RHS) {
|
|
if (RHS->getType()->isSigned()) {
|
|
// True if source is LHS < 0 or LHS <= -1
|
|
return Opcode == Instruction::SetLT && RHS->isNullValue() ||
|
|
Opcode == Instruction::SetLE && RHS->isAllOnesValue();
|
|
} else {
|
|
ConstantUInt *RHSC = cast<ConstantUInt>(RHS);
|
|
// True if source is LHS > 127 or LHS >= 128, where the constants depend on
|
|
// the size of the integer type.
|
|
if (Opcode == Instruction::SetGE)
|
|
return RHSC->getValue() ==
|
|
1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1);
|
|
if (Opcode == Instruction::SetGT)
|
|
return RHSC->getValue() ==
|
|
(1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1))-1;
|
|
}
|
|
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 (ShiftInst *SI = dyn_cast<ShiftInst>(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->isNullValue())
|
|
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());
|
|
|
|
int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue();
|
|
if (isPowerOf2_64(Val)) { // Replace X*(2^C) with X << C
|
|
uint64_t C = Log2_64(Val);
|
|
return new ShiftInst(Instruction::Shl, Op0,
|
|
ConstantUInt::get(Type::UByteTy, C));
|
|
}
|
|
} 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->getValue() == 1.0)
|
|
return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
|
|
}
|
|
|
|
// 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);
|
|
|
|
// 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 (CastInst *CI = dyn_cast<CastInst>(I.getOperand(0)))
|
|
if (CI->getOperand(0)->getType() == Type::BoolTy)
|
|
BoolCast = CI;
|
|
if (!BoolCast)
|
|
if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(1)))
|
|
if (CI->getOperand(0)->getType() == Type::BoolTy)
|
|
BoolCast = CI;
|
|
if (BoolCast) {
|
|
if (SetCondInst *SCI = dyn_cast<SetCondInst>(BoolCast->getOperand(0))) {
|
|
Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1);
|
|
const Type *SCOpTy = SCIOp0->getType();
|
|
|
|
// If the setcc 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->getOpcode(), SCIOp0, cast<ConstantInt>(SCIOp1))) {
|
|
// Shift the X value right to turn it into "all signbits".
|
|
Constant *Amt = ConstantUInt::get(Type::UByteTy,
|
|
SCOpTy->getPrimitiveSizeInBits()-1);
|
|
if (SCIOp0->getType()->isUnsigned()) {
|
|
const Type *NewTy = SCIOp0->getType()->getSignedVersion();
|
|
SCIOp0 = InsertNewInstBefore(new CastInst(SCIOp0, NewTy,
|
|
SCIOp0->getName()), I);
|
|
}
|
|
|
|
Value *V =
|
|
InsertNewInstBefore(new ShiftInst(Instruction::Shr, 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())
|
|
V = InsertNewInstBefore(new CastInst(V, I.getType(), V->getName()),I);
|
|
|
|
Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0;
|
|
return BinaryOperator::createAnd(V, OtherOp);
|
|
}
|
|
}
|
|
}
|
|
|
|
return Changed ? &I : 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
if (isa<UndefValue>(Op0)) // undef / X -> 0
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
if (isa<UndefValue>(Op1))
|
|
return ReplaceInstUsesWith(I, Op1); // X / undef -> undef
|
|
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
|
|
// div X, 1 == X
|
|
if (RHS->equalsInt(1))
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
|
|
// div X, -1 == -X
|
|
if (RHS->isAllOnesValue())
|
|
return BinaryOperator::createNeg(Op0);
|
|
|
|
if (Instruction *LHS = dyn_cast<Instruction>(Op0))
|
|
if (LHS->getOpcode() == Instruction::Div)
|
|
if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
|
|
// (X / C1) / C2 -> X / (C1*C2)
|
|
return BinaryOperator::createDiv(LHS->getOperand(0),
|
|
ConstantExpr::getMul(RHS, LHSRHS));
|
|
}
|
|
|
|
// Check to see if this is an unsigned division with an exact power of 2,
|
|
// if so, convert to a right shift.
|
|
if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
|
|
if (uint64_t Val = C->getValue()) // Don't break X / 0
|
|
if (isPowerOf2_64(Val)) {
|
|
uint64_t C = Log2_64(Val);
|
|
return new ShiftInst(Instruction::Shr, Op0,
|
|
ConstantUInt::get(Type::UByteTy, C));
|
|
}
|
|
|
|
// -X/C -> X/-C
|
|
if (RHS->getType()->isSigned())
|
|
if (Value *LHSNeg = dyn_castNegVal(Op0))
|
|
return BinaryOperator::createDiv(LHSNeg, ConstantExpr::getNeg(RHS));
|
|
|
|
if (!RHS->isNullValue()) {
|
|
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 this is 'udiv X, (Cond ? C1, C2)' where C1&C2 are powers of two,
|
|
// transform this into: '(Cond ? (udiv X, C1) : (udiv X, C2))'.
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
|
|
if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
|
|
if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
|
|
if (STO->getValue() == 0) { // Couldn't be this argument.
|
|
I.setOperand(1, SFO);
|
|
return &I;
|
|
} else if (SFO->getValue() == 0) {
|
|
I.setOperand(1, STO);
|
|
return &I;
|
|
}
|
|
|
|
uint64_t TVA = STO->getValue(), FVA = SFO->getValue();
|
|
if (isPowerOf2_64(TVA) && isPowerOf2_64(FVA)) {
|
|
unsigned TSA = Log2_64(TVA), FSA = Log2_64(FVA);
|
|
Constant *TC = ConstantUInt::get(Type::UByteTy, TSA);
|
|
Instruction *TSI = new ShiftInst(Instruction::Shr, Op0,
|
|
TC, SI->getName()+".t");
|
|
TSI = InsertNewInstBefore(TSI, I);
|
|
|
|
Constant *FC = ConstantUInt::get(Type::UByteTy, FSA);
|
|
Instruction *FSI = new ShiftInst(Instruction::Shr, Op0,
|
|
FC, SI->getName()+".f");
|
|
FSI = InsertNewInstBefore(FSI, I);
|
|
return new SelectInst(SI->getOperand(0), TSI, FSI);
|
|
}
|
|
}
|
|
|
|
// 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()));
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
Instruction *InstCombiner::visitRem(BinaryOperator &I) {
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
if (I.getType()->isSigned())
|
|
if (Value *RHSNeg = dyn_castNegVal(Op1))
|
|
if (!isa<ConstantSInt>(RHSNeg) ||
|
|
cast<ConstantSInt>(RHSNeg)->getValue() > 0) {
|
|
// X % -Y -> X % Y
|
|
AddUsesToWorkList(I);
|
|
I.setOperand(1, RHSNeg);
|
|
return &I;
|
|
}
|
|
|
|
if (isa<UndefValue>(Op0)) // undef % X -> 0
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
if (isa<UndefValue>(Op1))
|
|
return ReplaceInstUsesWith(I, Op1); // X % undef -> undef
|
|
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
|
|
if (RHS->equalsInt(1)) // X % 1 == 0
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
|
|
// Check to see if this is an unsigned remainder with an exact power of 2,
|
|
// if so, convert to a bitwise and.
|
|
if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
|
|
if (uint64_t Val = C->getValue()) // Don't break X % 0 (divide by zero)
|
|
if (!(Val & (Val-1))) // Power of 2
|
|
return BinaryOperator::createAnd(Op0,
|
|
ConstantUInt::get(I.getType(), Val-1));
|
|
|
|
if (!RHS->isNullValue()) {
|
|
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 this is 'urem X, (Cond ? C1, C2)' where C1&C2 are powers of two,
|
|
// transform this into: '(Cond ? (urem X, C1) : (urem X, C2))'.
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
|
|
if (ConstantUInt *STO = dyn_cast<ConstantUInt>(SI->getOperand(1)))
|
|
if (ConstantUInt *SFO = dyn_cast<ConstantUInt>(SI->getOperand(2))) {
|
|
if (STO->getValue() == 0) { // Couldn't be this argument.
|
|
I.setOperand(1, SFO);
|
|
return &I;
|
|
} else if (SFO->getValue() == 0) {
|
|
I.setOperand(1, STO);
|
|
return &I;
|
|
}
|
|
|
|
if (!(STO->getValue() & (STO->getValue()-1)) &&
|
|
!(SFO->getValue() & (SFO->getValue()-1))) {
|
|
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 new SelectInst(SI->getOperand(0), TrueAnd, FalseAnd);
|
|
}
|
|
}
|
|
|
|
// 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()));
|
|
|
|
return 0;
|
|
}
|
|
|
|
// isMaxValueMinusOne - return true if this is Max-1
|
|
static bool isMaxValueMinusOne(const ConstantInt *C) {
|
|
if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) {
|
|
// Calculate -1 casted to the right type...
|
|
unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
|
|
uint64_t Val = ~0ULL; // All ones
|
|
Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
|
|
return CU->getValue() == Val-1;
|
|
}
|
|
|
|
const ConstantSInt *CS = cast<ConstantSInt>(C);
|
|
|
|
// Calculate 0111111111..11111
|
|
unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
|
|
int64_t Val = INT64_MAX; // All ones
|
|
Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
|
|
return CS->getValue() == Val-1;
|
|
}
|
|
|
|
// isMinValuePlusOne - return true if this is Min+1
|
|
static bool isMinValuePlusOne(const ConstantInt *C) {
|
|
if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
|
|
return CU->getValue() == 1;
|
|
|
|
const ConstantSInt *CS = cast<ConstantSInt>(C);
|
|
|
|
// Calculate 1111111111000000000000
|
|
unsigned TypeBits = C->getType()->getPrimitiveSizeInBits();
|
|
int64_t Val = -1; // All ones
|
|
Val <<= TypeBits-1; // Shift over to the right spot
|
|
return CS->getValue() == Val+1;
|
|
}
|
|
|
|
// isOneBitSet - Return true if there is exactly one bit set in the specified
|
|
// constant.
|
|
static bool isOneBitSet(const ConstantInt *CI) {
|
|
uint64_t V = CI->getRawValue();
|
|
return V && (V & (V-1)) == 0;
|
|
}
|
|
|
|
#if 0 // Currently unused
|
|
// isLowOnes - Return true if the constant is of the form 0+1+.
|
|
static bool isLowOnes(const ConstantInt *CI) {
|
|
uint64_t V = CI->getRawValue();
|
|
|
|
// There won't be bits set in parts that the type doesn't contain.
|
|
V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
|
|
|
|
uint64_t U = V+1; // If it is low ones, this should be a power of two.
|
|
return U && V && (U & V) == 0;
|
|
}
|
|
#endif
|
|
|
|
// 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) {
|
|
uint64_t V = ~CI->getRawValue();
|
|
if (~V == 0) return false; // 0's does not match "1+"
|
|
|
|
// There won't be bits set in parts that the type doesn't contain.
|
|
V &= ConstantInt::getAllOnesValue(CI->getType())->getRawValue();
|
|
|
|
uint64_t U = V+1; // If it is low ones, this should be a power of two.
|
|
return U && V && (U & V) == 0;
|
|
}
|
|
|
|
|
|
/// getSetCondCode - Encode a setcc opcode into a three bit mask. These bits
|
|
/// are carefully arranged to allow folding of expressions such as:
|
|
///
|
|
/// (A < B) | (A > B) --> (A != B)
|
|
///
|
|
/// Bit value '4' represents that the comparison is true if A > B, bit value '2'
|
|
/// represents that the comparison is true if A == B, and bit value '1' is true
|
|
/// if A < B.
|
|
///
|
|
static unsigned getSetCondCode(const SetCondInst *SCI) {
|
|
switch (SCI->getOpcode()) {
|
|
// False -> 0
|
|
case Instruction::SetGT: return 1;
|
|
case Instruction::SetEQ: return 2;
|
|
case Instruction::SetGE: return 3;
|
|
case Instruction::SetLT: return 4;
|
|
case Instruction::SetNE: return 5;
|
|
case Instruction::SetLE: return 6;
|
|
// True -> 7
|
|
default:
|
|
assert(0 && "Invalid SetCC opcode!");
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/// getSetCCValue - This is the complement of getSetCondCode, which turns an
|
|
/// opcode and two operands into either a constant true or false, or a brand new
|
|
/// SetCC instruction.
|
|
static Value *getSetCCValue(unsigned Opcode, Value *LHS, Value *RHS) {
|
|
switch (Opcode) {
|
|
case 0: return ConstantBool::False;
|
|
case 1: return new SetCondInst(Instruction::SetGT, LHS, RHS);
|
|
case 2: return new SetCondInst(Instruction::SetEQ, LHS, RHS);
|
|
case 3: return new SetCondInst(Instruction::SetGE, LHS, RHS);
|
|
case 4: return new SetCondInst(Instruction::SetLT, LHS, RHS);
|
|
case 5: return new SetCondInst(Instruction::SetNE, LHS, RHS);
|
|
case 6: return new SetCondInst(Instruction::SetLE, LHS, RHS);
|
|
case 7: return ConstantBool::True;
|
|
default: assert(0 && "Illegal SetCCCode!"); return 0;
|
|
}
|
|
}
|
|
|
|
// FoldSetCCLogical - Implements (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
|
|
struct FoldSetCCLogical {
|
|
InstCombiner &IC;
|
|
Value *LHS, *RHS;
|
|
FoldSetCCLogical(InstCombiner &ic, SetCondInst *SCI)
|
|
: IC(ic), LHS(SCI->getOperand(0)), RHS(SCI->getOperand(1)) {}
|
|
bool shouldApply(Value *V) const {
|
|
if (SetCondInst *SCI = dyn_cast<SetCondInst>(V))
|
|
return (SCI->getOperand(0) == LHS && SCI->getOperand(1) == RHS ||
|
|
SCI->getOperand(0) == RHS && SCI->getOperand(1) == LHS);
|
|
return false;
|
|
}
|
|
Instruction *apply(BinaryOperator &Log) const {
|
|
SetCondInst *SCI = cast<SetCondInst>(Log.getOperand(0));
|
|
if (SCI->getOperand(0) != LHS) {
|
|
assert(SCI->getOperand(1) == LHS);
|
|
SCI->swapOperands(); // Swap the LHS and RHS of the SetCC
|
|
}
|
|
|
|
unsigned LHSCode = getSetCondCode(SCI);
|
|
unsigned RHSCode = getSetCondCode(cast<SetCondInst>(Log.getOperand(1)));
|
|
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;
|
|
}
|
|
|
|
Value *RV = getSetCCValue(Code, LHS, RHS);
|
|
if (Instruction *I = dyn_cast<Instruction>(RV))
|
|
return I;
|
|
// Otherwise, it's a constant boolean value...
|
|
return IC.ReplaceInstUsesWith(Log, RV);
|
|
}
|
|
};
|
|
|
|
// 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 either a shift instruction or a binary operator.
|
|
Instruction *InstCombiner::OptAndOp(Instruction *Op,
|
|
ConstantIntegral *OpRHS,
|
|
ConstantIntegral *AndRHS,
|
|
BinaryOperator &TheAnd) {
|
|
Value *X = Op->getOperand(0);
|
|
Constant *Together = 0;
|
|
if (!isa<ShiftInst>(Op))
|
|
Together = ConstantExpr::getAnd(AndRHS, OpRHS);
|
|
|
|
switch (Op->getOpcode()) {
|
|
case Instruction::Xor:
|
|
if (Op->hasOneUse()) {
|
|
// (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
|
|
std::string OpName = Op->getName(); Op->setName("");
|
|
Instruction *And = BinaryOperator::createAnd(X, AndRHS, OpName);
|
|
InsertNewInstBefore(And, TheAnd);
|
|
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
|
|
std::string Op0Name = Op->getName(); Op->setName("");
|
|
Instruction *Or = BinaryOperator::createOr(X, Together, Op0Name);
|
|
InsertNewInstBefore(Or, TheAnd);
|
|
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.
|
|
uint64_t AndRHSV = cast<ConstantInt>(AndRHS)->getRawValue();
|
|
|
|
// Clear bits that are not part of the constant.
|
|
AndRHSV &= ~0ULL >> (64-AndRHS->getType()->getPrimitiveSizeInBits());
|
|
|
|
// 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.
|
|
uint64_t AddRHS = cast<ConstantInt>(OpRHS)->getRawValue();
|
|
|
|
// 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 {
|
|
std::string Name = Op->getName(); Op->setName("");
|
|
// Pull the XOR out of the AND.
|
|
Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS, Name);
|
|
InsertNewInstBefore(NewAnd, TheAnd);
|
|
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!
|
|
//
|
|
Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
|
|
Constant *ShlMask = ConstantExpr::getShl(AllOne, OpRHS);
|
|
Constant *CI = ConstantExpr::getAnd(AndRHS, ShlMask);
|
|
|
|
if (CI == 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::Shr:
|
|
// 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!
|
|
//
|
|
if (AndRHS->getType()->isUnsigned()) {
|
|
Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
|
|
Constant *ShrMask = ConstantExpr::getShr(AllOne, OpRHS);
|
|
Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
|
|
|
|
if (CI == 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;
|
|
}
|
|
} else { // Signed shr.
|
|
// See if this is shifting in some sign extension, then masking it out
|
|
// with an and.
|
|
if (Op->hasOneUse()) {
|
|
Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType());
|
|
Constant *ShrMask = ConstantExpr::getUShr(AllOne, OpRHS);
|
|
Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask);
|
|
if (CI == AndRHS) { // Masking out bits shifted in.
|
|
// Make the argument unsigned.
|
|
Value *ShVal = Op->getOperand(0);
|
|
ShVal = InsertCastBefore(ShVal,
|
|
ShVal->getType()->getUnsignedVersion(),
|
|
TheAnd);
|
|
ShVal = InsertNewInstBefore(new ShiftInst(Instruction::Shr, ShVal,
|
|
OpRHS, Op->getName()),
|
|
TheAnd);
|
|
Value *AndRHS2 = ConstantExpr::getCast(AndRHS, ShVal->getType());
|
|
ShVal = InsertNewInstBefore(BinaryOperator::createAnd(ShVal, AndRHS2,
|
|
TheAnd.getName()),
|
|
TheAnd);
|
|
return new CastInst(ShVal, Op->getType());
|
|
}
|
|
}
|
|
}
|
|
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. IB is the location to
|
|
/// insert new instructions.
|
|
Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
|
|
bool Inside, Instruction &IB) {
|
|
assert(cast<ConstantBool>(ConstantExpr::getSetLE(Lo, Hi))->getValue() &&
|
|
"Lo is not <= Hi in range emission code!");
|
|
if (Inside) {
|
|
if (Lo == Hi) // Trivially false.
|
|
return new SetCondInst(Instruction::SetNE, V, V);
|
|
if (cast<ConstantIntegral>(Lo)->isMinValue())
|
|
return new SetCondInst(Instruction::SetLT, V, Hi);
|
|
|
|
Constant *AddCST = ConstantExpr::getNeg(Lo);
|
|
Instruction *Add = BinaryOperator::createAdd(V, AddCST,V->getName()+".off");
|
|
InsertNewInstBefore(Add, IB);
|
|
// Convert to unsigned for the comparison.
|
|
const Type *UnsType = Add->getType()->getUnsignedVersion();
|
|
Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
|
|
AddCST = ConstantExpr::getAdd(AddCST, Hi);
|
|
AddCST = ConstantExpr::getCast(AddCST, UnsType);
|
|
return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
|
|
}
|
|
|
|
if (Lo == Hi) // Trivially true.
|
|
return new SetCondInst(Instruction::SetEQ, V, V);
|
|
|
|
Hi = SubOne(cast<ConstantInt>(Hi));
|
|
if (cast<ConstantIntegral>(Lo)->isMinValue()) // V < 0 || V >= Hi ->'V > Hi-1'
|
|
return new SetCondInst(Instruction::SetGT, V, Hi);
|
|
|
|
// Emit X-Lo > Hi-Lo-1
|
|
Constant *AddCST = ConstantExpr::getNeg(Lo);
|
|
Instruction *Add = BinaryOperator::createAdd(V, AddCST, V->getName()+".off");
|
|
InsertNewInstBefore(Add, IB);
|
|
// Convert to unsigned for the comparison.
|
|
const Type *UnsType = Add->getType()->getUnsignedVersion();
|
|
Value *OffsetVal = InsertCastBefore(Add, UnsType, IB);
|
|
AddCST = ConstantExpr::getAdd(AddCST, Hi);
|
|
AddCST = ConstantExpr::getCast(AddCST, UnsType);
|
|
return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
|
|
}
|
|
|
|
// 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(ConstantIntegral *Val, unsigned &MB, unsigned &ME) {
|
|
uint64_t V = Val->getRawValue();
|
|
if (!isShiftedMask_64(V)) return false;
|
|
|
|
// look for the first zero bit after the run of ones
|
|
MB = 64-CountLeadingZeros_64((V - 1) ^ V);
|
|
// look for the first non-zero bit
|
|
ME = 64-CountLeadingZeros_64(V);
|
|
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,
|
|
ConstantIntegral *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 (ConstantExpr::getAnd(N, Mask) == Mask) {
|
|
// If the AndRHS is a power of two minus one (0+1+), this is simple.
|
|
if ((Mask->getRawValue() & Mask->getRawValue()+1) == 0)
|
|
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.
|
|
unsigned MB, ME;
|
|
if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
|
|
Constant *Mask = ConstantInt::getAllOnesValue(RHS->getType());
|
|
Mask = ConstantExpr::getUShr(Mask,
|
|
ConstantInt::get(Type::UByteTy,
|
|
(64-MB+1)));
|
|
if (MaskedValueIsZero(RHS, cast<ConstantIntegral>(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->getRawValue() & Mask->getRawValue()+1) == 0 &&
|
|
ConstantExpr::getAnd(N, Mask)->isNullValue())
|
|
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);
|
|
}
|
|
|
|
|
|
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);
|
|
|
|
if (ConstantIntegral *AndRHS = dyn_cast<ConstantIntegral>(Op1)) {
|
|
// and X, -1 == X
|
|
if (AndRHS->isAllOnesValue())
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
|
|
if (MaskedValueIsZero(Op0, AndRHS)) // LHS & RHS == 0
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
|
|
// If the mask is not masking out any bits, there is no reason to do the
|
|
// and in the first place.
|
|
ConstantIntegral *NotAndRHS =
|
|
cast<ConstantIntegral>(ConstantExpr::getNot(AndRHS));
|
|
if (MaskedValueIsZero(Op0, NotAndRHS))
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
|
|
// Optimize a variety of ((val OP C1) & C2) combinations...
|
|
if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(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:
|
|
// (X ^ V) & C2 --> (X & C2) iff (V & C2) == 0
|
|
// (X | V) & C2 --> (X & C2) iff (V & C2) == 0
|
|
if (MaskedValueIsZero(Op0LHS, AndRHS))
|
|
return BinaryOperator::createAnd(Op0RHS, AndRHS);
|
|
if (MaskedValueIsZero(Op0RHS, AndRHS))
|
|
return BinaryOperator::createAnd(Op0LHS, AndRHS);
|
|
|
|
// 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>(NotAndRHS) &&
|
|
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::And:
|
|
// (X & V) & C2 --> 0 iff (V & C2) == 0
|
|
if (MaskedValueIsZero(Op0LHS, AndRHS) ||
|
|
MaskedValueIsZero(Op0RHS, AndRHS))
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
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);
|
|
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)) {
|
|
const Type *SrcTy = CI->getOperand(0)->getType();
|
|
|
|
// 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 (SrcTy->getPrimitiveSizeInBits() >=
|
|
I.getType()->getPrimitiveSizeInBits() &&
|
|
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(C1)&C2
|
|
// This will folds the two ands together, which may allow other
|
|
// simplifications.
|
|
Instruction *NewCast =
|
|
new CastInst(CastOp->getOperand(0), I.getType(),
|
|
CastOp->getName()+".shrunk");
|
|
NewCast = InsertNewInstBefore(NewCast, I);
|
|
|
|
Constant *C3=ConstantExpr::getCast(AndCI, I.getType());//trunc(C1)
|
|
C3 = ConstantExpr::getAnd(C3, AndRHS); // trunc(C1)&C2
|
|
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::getCast(AndCI, I.getType());//trunc(C1)
|
|
if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS) // trunc(C1)&C2
|
|
return ReplaceInstUsesWith(I, AndRHS);
|
|
}
|
|
}
|
|
|
|
|
|
// If this is an integer sign or zero extension instruction.
|
|
if (SrcTy->isIntegral() &&
|
|
SrcTy->getPrimitiveSizeInBits() <
|
|
CI->getType()->getPrimitiveSizeInBits()) {
|
|
|
|
if (SrcTy->isUnsigned()) {
|
|
// See if this and is clearing out bits that are known to be zero
|
|
// anyway (due to the zero extension).
|
|
Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
|
|
Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
|
|
Constant *Result = ConstantExpr::getAnd(Mask, AndRHS);
|
|
if (Result == Mask) // The "and" isn't doing anything, remove it.
|
|
return ReplaceInstUsesWith(I, CI);
|
|
if (Result != AndRHS) { // Reduce the and RHS constant.
|
|
I.setOperand(1, Result);
|
|
return &I;
|
|
}
|
|
|
|
} else {
|
|
if (CI->hasOneUse() && SrcTy->isInteger()) {
|
|
// We can only do this if all of the sign bits brought in are masked
|
|
// out. Compute this by first getting 0000011111, then inverting
|
|
// it.
|
|
Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
|
|
Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
|
|
Mask = ConstantExpr::getNot(Mask); // 1's in the new bits.
|
|
if (ConstantExpr::getAnd(Mask, AndRHS)->isNullValue()) {
|
|
// If the and is clearing all of the sign bits, change this to a
|
|
// zero extension cast. To do this, cast the cast input to
|
|
// unsigned, then to the requested size.
|
|
Value *CastOp = CI->getOperand(0);
|
|
Instruction *NC =
|
|
new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
|
|
CI->getName()+".uns");
|
|
NC = InsertNewInstBefore(NC, I);
|
|
// Finally, insert a replacement for CI.
|
|
NC = new CastInst(NC, CI->getType(), CI->getName());
|
|
CI->setName("");
|
|
NC = InsertNewInstBefore(NC, I);
|
|
WorkList.push_back(CI); // Delete CI later.
|
|
I.setOperand(0, NC);
|
|
return &I; // The AND operand was modified.
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// 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);
|
|
}
|
|
|
|
if (SetCondInst *RHS = dyn_cast<SetCondInst>(Op1)) {
|
|
// (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B)
|
|
if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
|
|
return R;
|
|
|
|
Value *LHSVal, *RHSVal;
|
|
ConstantInt *LHSCst, *RHSCst;
|
|
Instruction::BinaryOps LHSCC, RHSCC;
|
|
if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
|
|
if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
|
|
if (LHSVal == RHSVal && // Found (X setcc C1) & (X setcc C2)
|
|
// Set[GL]E X, CST is folded to Set[GL]T elsewhere.
|
|
LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
|
|
RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
|
|
// Ensure that the larger constant is on the RHS.
|
|
Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
|
|
SetCondInst *LHS = cast<SetCondInst>(Op0);
|
|
if (cast<ConstantBool>(Cmp)->getValue()) {
|
|
std::swap(LHS, RHS);
|
|
std::swap(LHSCst, RHSCst);
|
|
std::swap(LHSCC, RHSCC);
|
|
}
|
|
|
|
// At this point, we know we have have two setcc instructions
|
|
// comparing a value against two constants and and'ing the result
|
|
// together. Because of the above check, we know that we only have
|
|
// SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
|
|
// FoldSetCCLogical 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 Instruction::SetEQ:
|
|
switch (RHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case Instruction::SetEQ: // (X == 13 & X == 15) -> false
|
|
case Instruction::SetGT: // (X == 13 & X > 15) -> false
|
|
return ReplaceInstUsesWith(I, ConstantBool::False);
|
|
case Instruction::SetNE: // (X == 13 & X != 15) -> X == 13
|
|
case Instruction::SetLT: // (X == 13 & X < 15) -> X == 13
|
|
return ReplaceInstUsesWith(I, LHS);
|
|
}
|
|
case Instruction::SetNE:
|
|
switch (RHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case Instruction::SetLT:
|
|
if (LHSCst == SubOne(RHSCst)) // (X != 13 & X < 14) -> X < 13
|
|
return new SetCondInst(Instruction::SetLT, LHSVal, LHSCst);
|
|
break; // (X != 13 & X < 15) -> no change
|
|
case Instruction::SetEQ: // (X != 13 & X == 15) -> X == 15
|
|
case Instruction::SetGT: // (X != 13 & X > 15) -> X > 15
|
|
return ReplaceInstUsesWith(I, RHS);
|
|
case Instruction::SetNE:
|
|
if (LHSCst == SubOne(RHSCst)) {// (X != 13 & X != 14) -> X-13 >u 1
|
|
Constant *AddCST = ConstantExpr::getNeg(LHSCst);
|
|
Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
|
|
LHSVal->getName()+".off");
|
|
InsertNewInstBefore(Add, I);
|
|
const Type *UnsType = Add->getType()->getUnsignedVersion();
|
|
Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
|
|
AddCST = ConstantExpr::getSub(RHSCst, LHSCst);
|
|
AddCST = ConstantExpr::getCast(AddCST, UnsType);
|
|
return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
|
|
}
|
|
break; // (X != 13 & X != 15) -> no change
|
|
}
|
|
break;
|
|
case Instruction::SetLT:
|
|
switch (RHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case Instruction::SetEQ: // (X < 13 & X == 15) -> false
|
|
case Instruction::SetGT: // (X < 13 & X > 15) -> false
|
|
return ReplaceInstUsesWith(I, ConstantBool::False);
|
|
case Instruction::SetNE: // (X < 13 & X != 15) -> X < 13
|
|
case Instruction::SetLT: // (X < 13 & X < 15) -> X < 13
|
|
return ReplaceInstUsesWith(I, LHS);
|
|
}
|
|
case Instruction::SetGT:
|
|
switch (RHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case Instruction::SetEQ: // (X > 13 & X == 15) -> X > 13
|
|
return ReplaceInstUsesWith(I, LHS);
|
|
case Instruction::SetGT: // (X > 13 & X > 15) -> X > 15
|
|
return ReplaceInstUsesWith(I, RHS);
|
|
case Instruction::SetNE:
|
|
if (RHSCst == AddOne(LHSCst)) // (X > 13 & X != 14) -> X > 14
|
|
return new SetCondInst(Instruction::SetGT, LHSVal, RHSCst);
|
|
break; // (X > 13 & X != 15) -> no change
|
|
case Instruction::SetLT: // (X > 13 & X < 15) -> (X-14) <u 1
|
|
return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true, I);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return Changed ? &I : 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitOr(BinaryOperator &I) {
|
|
bool Changed = SimplifyCommutative(I);
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
if (isa<UndefValue>(Op1))
|
|
return ReplaceInstUsesWith(I, // X | undef -> -1
|
|
ConstantIntegral::getAllOnesValue(I.getType()));
|
|
|
|
// or X, X = X or X, 0 == X
|
|
if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
|
|
// or X, -1 == -1
|
|
if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
|
|
// If X is known to only contain bits that already exist in RHS, just
|
|
// replace this instruction with RHS directly.
|
|
if (MaskedValueIsZero(Op0,
|
|
cast<ConstantIntegral>(ConstantExpr::getNot(RHS))))
|
|
return ReplaceInstUsesWith(I, RHS);
|
|
|
|
ConstantInt *C1; Value *X;
|
|
// (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, Op0->getName());
|
|
Op0->setName("");
|
|
InsertNewInstBefore(Or, I);
|
|
return BinaryOperator::createAnd(Or, ConstantExpr::getOr(RHS, C1));
|
|
}
|
|
|
|
// (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
|
|
if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) {
|
|
std::string Op0Name = Op0->getName(); Op0->setName("");
|
|
Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name);
|
|
InsertNewInstBefore(Or, I);
|
|
return BinaryOperator::createXor(Or,
|
|
ConstantExpr::getAnd(C1, ConstantExpr::getNot(RHS)));
|
|
}
|
|
|
|
// 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, *B; ConstantInt *C1, *C2;
|
|
|
|
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);
|
|
|
|
// (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)) {
|
|
Instruction *NOr = BinaryOperator::createOr(A, Op1, Op0->getName());
|
|
Op0->setName("");
|
|
return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), 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)) {
|
|
Instruction *NOr = BinaryOperator::createOr(A, Op0, Op1->getName());
|
|
Op0->setName("");
|
|
return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1);
|
|
}
|
|
|
|
// (A & C1)|(B & C2)
|
|
if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
|
|
match(Op1, m_And(m_Value(B), m_ConstantInt(C2)))) {
|
|
|
|
if (A == B) // (A & C1)|(A & C2) == A & (C1|C2)
|
|
return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, 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 == ConstantExpr::getNot(C2)) {
|
|
Value *V1, *V2;
|
|
if ((C2->getRawValue() & (C2->getRawValue()+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))
|
|
return ReplaceInstUsesWith(I, A);
|
|
if (V2 == B && MaskedValueIsZero(V1, C2))
|
|
return ReplaceInstUsesWith(I, A);
|
|
}
|
|
// Or commutes, try both ways.
|
|
if ((C1->getRawValue() & (C1->getRawValue()+1)) == 0 &&
|
|
match(B, m_Add(m_Value(V1), m_Value(V2)))) {
|
|
// Add commutes, try both ways.
|
|
if (V1 == A && MaskedValueIsZero(V2, C1))
|
|
return ReplaceInstUsesWith(I, B);
|
|
if (V2 == A && MaskedValueIsZero(V1, C1))
|
|
return ReplaceInstUsesWith(I, B);
|
|
}
|
|
}
|
|
}
|
|
|
|
if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
|
|
if (A == Op1) // ~A | A == -1
|
|
return ReplaceInstUsesWith(I,
|
|
ConstantIntegral::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,
|
|
ConstantIntegral::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);
|
|
}
|
|
}
|
|
|
|
// (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B)
|
|
if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1))) {
|
|
if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
|
|
return R;
|
|
|
|
Value *LHSVal, *RHSVal;
|
|
ConstantInt *LHSCst, *RHSCst;
|
|
Instruction::BinaryOps LHSCC, RHSCC;
|
|
if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst))))
|
|
if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst))))
|
|
if (LHSVal == RHSVal && // Found (X setcc C1) | (X setcc C2)
|
|
// Set[GL]E X, CST is folded to Set[GL]T elsewhere.
|
|
LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE &&
|
|
RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) {
|
|
// Ensure that the larger constant is on the RHS.
|
|
Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst);
|
|
SetCondInst *LHS = cast<SetCondInst>(Op0);
|
|
if (cast<ConstantBool>(Cmp)->getValue()) {
|
|
std::swap(LHS, RHS);
|
|
std::swap(LHSCst, RHSCst);
|
|
std::swap(LHSCC, RHSCC);
|
|
}
|
|
|
|
// At this point, we know we have have two setcc instructions
|
|
// comparing a value against two constants and or'ing the result
|
|
// together. Because of the above check, we know that we only have
|
|
// SetEQ, SetNE, SetLT, and SetGT here. We also know (from the
|
|
// FoldSetCCLogical 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 Instruction::SetEQ:
|
|
switch (RHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case Instruction::SetEQ:
|
|
if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2
|
|
Constant *AddCST = ConstantExpr::getNeg(LHSCst);
|
|
Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST,
|
|
LHSVal->getName()+".off");
|
|
InsertNewInstBefore(Add, I);
|
|
const Type *UnsType = Add->getType()->getUnsignedVersion();
|
|
Value *OffsetVal = InsertCastBefore(Add, UnsType, I);
|
|
AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst);
|
|
AddCST = ConstantExpr::getCast(AddCST, UnsType);
|
|
return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST);
|
|
}
|
|
break; // (X == 13 | X == 15) -> no change
|
|
|
|
case Instruction::SetGT: // (X == 13 | X > 14) -> no change
|
|
break;
|
|
case Instruction::SetNE: // (X == 13 | X != 15) -> X != 15
|
|
case Instruction::SetLT: // (X == 13 | X < 15) -> X < 15
|
|
return ReplaceInstUsesWith(I, RHS);
|
|
}
|
|
break;
|
|
case Instruction::SetNE:
|
|
switch (RHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case Instruction::SetEQ: // (X != 13 | X == 15) -> X != 13
|
|
case Instruction::SetGT: // (X != 13 | X > 15) -> X != 13
|
|
return ReplaceInstUsesWith(I, LHS);
|
|
case Instruction::SetNE: // (X != 13 | X != 15) -> true
|
|
case Instruction::SetLT: // (X != 13 | X < 15) -> true
|
|
return ReplaceInstUsesWith(I, ConstantBool::True);
|
|
}
|
|
break;
|
|
case Instruction::SetLT:
|
|
switch (RHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case Instruction::SetEQ: // (X < 13 | X == 14) -> no change
|
|
break;
|
|
case Instruction::SetGT: // (X < 13 | X > 15) -> (X-13) > 2
|
|
return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false, I);
|
|
case Instruction::SetNE: // (X < 13 | X != 15) -> X != 15
|
|
case Instruction::SetLT: // (X < 13 | X < 15) -> X < 15
|
|
return ReplaceInstUsesWith(I, RHS);
|
|
}
|
|
break;
|
|
case Instruction::SetGT:
|
|
switch (RHSCC) {
|
|
default: assert(0 && "Unknown integer condition code!");
|
|
case Instruction::SetEQ: // (X > 13 | X == 15) -> X > 13
|
|
case Instruction::SetGT: // (X > 13 | X > 15) -> X > 13
|
|
return ReplaceInstUsesWith(I, LHS);
|
|
case Instruction::SetNE: // (X > 13 | X != 15) -> true
|
|
case Instruction::SetLT: // (X > 13 | X < 15) -> true
|
|
return ReplaceInstUsesWith(I, ConstantBool::True);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return Changed ? &I : 0;
|
|
}
|
|
|
|
// 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))
|
|
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?");
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
}
|
|
|
|
if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
|
|
// xor X, 0 == X
|
|
if (RHS->isNullValue())
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
|
|
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
|
|
// xor (setcc A, B), true = not (setcc A, B) = setncc A, B
|
|
if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I))
|
|
if (RHS == ConstantBool::True && SCI->hasOneUse())
|
|
return new SetCondInst(SCI->getInverseCondition(),
|
|
SCI->getOperand(0), SCI->getOperand(1));
|
|
|
|
// ~(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);
|
|
}
|
|
|
|
// ~(~X & Y) --> (X | ~Y)
|
|
if (Op0I->getOpcode() == Instruction::And && RHS->isAllOnesValue()) {
|
|
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);
|
|
return BinaryOperator::createOr(Op0NotVal, NotY);
|
|
}
|
|
}
|
|
|
|
if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
|
|
switch (Op0I->getOpcode()) {
|
|
case 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));
|
|
}
|
|
break;
|
|
case Instruction::And:
|
|
// (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0
|
|
if (ConstantExpr::getAnd(RHS, Op0CI)->isNullValue())
|
|
return BinaryOperator::createOr(Op0, RHS);
|
|
break;
|
|
case Instruction::Or:
|
|
// (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
|
|
if (ConstantExpr::getAnd(RHS, Op0CI) == RHS)
|
|
return BinaryOperator::createAnd(Op0, ConstantExpr::getNot(RHS));
|
|
break;
|
|
default: break;
|
|
}
|
|
}
|
|
|
|
// 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,
|
|
ConstantIntegral::getAllOnesValue(I.getType()));
|
|
|
|
if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
|
|
if (X == Op0)
|
|
return ReplaceInstUsesWith(I,
|
|
ConstantIntegral::getAllOnesValue(I.getType()));
|
|
|
|
if (Instruction *Op1I = dyn_cast<Instruction>(Op1))
|
|
if (Op1I->getOpcode() == Instruction::Or) {
|
|
if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B
|
|
cast<BinaryOperator>(Op1I)->swapOperands();
|
|
I.swapOperands();
|
|
std::swap(Op0, Op1);
|
|
} else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B
|
|
I.swapOperands();
|
|
std::swap(Op0, Op1);
|
|
}
|
|
} else if (Op1I->getOpcode() == Instruction::Xor) {
|
|
if (Op0 == Op1I->getOperand(0)) // A^(A^B) == B
|
|
return ReplaceInstUsesWith(I, Op1I->getOperand(1));
|
|
else if (Op0 == Op1I->getOperand(1)) // A^(B^A) == B
|
|
return ReplaceInstUsesWith(I, Op1I->getOperand(0));
|
|
}
|
|
|
|
if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
|
|
if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) {
|
|
if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B
|
|
cast<BinaryOperator>(Op0I)->swapOperands();
|
|
if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B
|
|
Value *NotB = InsertNewInstBefore(BinaryOperator::createNot(Op1,
|
|
Op1->getName()+".not"), I);
|
|
return BinaryOperator::createAnd(Op0I->getOperand(0), NotB);
|
|
}
|
|
} else if (Op0I->getOpcode() == Instruction::Xor) {
|
|
if (Op1 == Op0I->getOperand(0)) // (A^B)^A == B
|
|
return ReplaceInstUsesWith(I, Op0I->getOperand(1));
|
|
else if (Op1 == Op0I->getOperand(1)) // (B^A)^A == B
|
|
return ReplaceInstUsesWith(I, Op0I->getOperand(0));
|
|
}
|
|
|
|
// (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
|
|
Value *A, *B; ConstantInt *C1, *C2;
|
|
if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) &&
|
|
match(Op1, m_And(m_Value(B), m_ConstantInt(C2))) &&
|
|
ConstantExpr::getAnd(C1, C2)->isNullValue())
|
|
return BinaryOperator::createOr(Op0, Op1);
|
|
|
|
// (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B)
|
|
if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1)))
|
|
if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS)))
|
|
return R;
|
|
|
|
return Changed ? &I : 0;
|
|
}
|
|
|
|
/// MulWithOverflow - Compute Result = In1*In2, returning true if the result
|
|
/// overflowed for this type.
|
|
static bool MulWithOverflow(ConstantInt *&Result, ConstantInt *In1,
|
|
ConstantInt *In2) {
|
|
Result = cast<ConstantInt>(ConstantExpr::getMul(In1, In2));
|
|
return !In2->isNullValue() && ConstantExpr::getDiv(Result, In2) != In1;
|
|
}
|
|
|
|
static bool isPositive(ConstantInt *C) {
|
|
return cast<ConstantSInt>(C)->getValue() >= 0;
|
|
}
|
|
|
|
/// AddWithOverflow - Compute Result = In1+In2, returning true if the result
|
|
/// overflowed for this type.
|
|
static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1,
|
|
ConstantInt *In2) {
|
|
Result = cast<ConstantInt>(ConstantExpr::getAdd(In1, In2));
|
|
|
|
if (In1->getType()->isUnsigned())
|
|
return cast<ConstantUInt>(Result)->getValue() <
|
|
cast<ConstantUInt>(In1)->getValue();
|
|
if (isPositive(In1) != isPositive(In2))
|
|
return false;
|
|
if (isPositive(In1))
|
|
return cast<ConstantSInt>(Result)->getValue() <
|
|
cast<ConstantSInt>(In1)->getValue();
|
|
return cast<ConstantSInt>(Result)->getValue() >
|
|
cast<ConstantSInt>(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 *UIntPtrTy = TD.getIntPtrType();
|
|
const Type *SIntPtrTy = UIntPtrTy->getSignedVersion();
|
|
Value *Result = Constant::getNullValue(SIntPtrTy);
|
|
|
|
// Build a mask for high order bits.
|
|
uint64_t PtrSizeMask = ~0ULL;
|
|
PtrSizeMask >>= 64-(TD.getPointerSize()*8);
|
|
|
|
for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
|
|
Value *Op = GEP->getOperand(i);
|
|
uint64_t Size = TD.getTypeSize(GTI.getIndexedType()) & PtrSizeMask;
|
|
Constant *Scale = ConstantExpr::getCast(ConstantUInt::get(UIntPtrTy, Size),
|
|
SIntPtrTy);
|
|
if (Constant *OpC = dyn_cast<Constant>(Op)) {
|
|
if (!OpC->isNullValue()) {
|
|
OpC = ConstantExpr::getCast(OpC, SIntPtrTy);
|
|
Scale = ConstantExpr::getMul(OpC, 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);
|
|
}
|
|
}
|
|
} else {
|
|
// Convert to correct type.
|
|
Op = IC.InsertNewInstBefore(new CastInst(Op, SIntPtrTy,
|
|
Op->getName()+".c"), I);
|
|
if (Size != 1)
|
|
// 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.
|
|
Result = IC.InsertNewInstBefore(BinaryOperator::createAdd(Op, Result,
|
|
GEP->getName()+".offs"), I);
|
|
}
|
|
}
|
|
return Result;
|
|
}
|
|
|
|
/// FoldGEPSetCC - 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::FoldGEPSetCC(User *GEPLHS, Value *RHS,
|
|
Instruction::BinaryOps Cond,
|
|
Instruction &I) {
|
|
assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!");
|
|
|
|
if (CastInst *CI = dyn_cast<CastInst>(RHS))
|
|
if (isa<PointerType>(CI->getOperand(0)->getType()))
|
|
RHS = CI->getOperand(0);
|
|
|
|
Value *PtrBase = GEPLHS->getOperand(0);
|
|
if (PtrBase == RHS) {
|
|
// As an optimization, we don't actually have to compute the actual value of
|
|
// OFFSET if this is a seteq or setne comparison, just return whether each
|
|
// index is zero or not.
|
|
if (Cond == Instruction::SetEQ || Cond == Instruction::SetNE) {
|
|
Instruction *InVal = 0;
|
|
gep_type_iterator GTI = gep_type_begin(GEPLHS);
|
|
for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i, ++GTI) {
|
|
bool EmitIt = true;
|
|
if (Constant *C = dyn_cast<Constant>(GEPLHS->getOperand(i))) {
|
|
if (isa<UndefValue>(C)) // undef index -> undef.
|
|
return ReplaceInstUsesWith(I, UndefValue::get(I.getType()));
|
|
if (C->isNullValue())
|
|
EmitIt = false;
|
|
else if (TD->getTypeSize(GTI.getIndexedType()) == 0) {
|
|
EmitIt = false; // This is indexing into a zero sized array?
|
|
} else if (isa<ConstantInt>(C))
|
|
return ReplaceInstUsesWith(I, // No comparison is needed here.
|
|
ConstantBool::get(Cond == Instruction::SetNE));
|
|
}
|
|
|
|
if (EmitIt) {
|
|
Instruction *Comp =
|
|
new SetCondInst(Cond, GEPLHS->getOperand(i),
|
|
Constant::getNullValue(GEPLHS->getOperand(i)->getType()));
|
|
if (InVal == 0)
|
|
InVal = Comp;
|
|
else {
|
|
InVal = InsertNewInstBefore(InVal, I);
|
|
InsertNewInstBefore(Comp, I);
|
|
if (Cond == Instruction::SetNE) // True if any are unequal
|
|
InVal = BinaryOperator::createOr(InVal, Comp);
|
|
else // True if all are equal
|
|
InVal = BinaryOperator::createAnd(InVal, Comp);
|
|
}
|
|
}
|
|
}
|
|
|
|
if (InVal)
|
|
return InVal;
|
|
else
|
|
ReplaceInstUsesWith(I, // No comparison is needed here, all indexes = 0
|
|
ConstantBool::get(Cond == Instruction::SetEQ));
|
|
}
|
|
|
|
// Only lower this if the setcc is the only user of the GEP or if we expect
|
|
// the result to fold to a constant!
|
|
if (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) {
|
|
// ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0).
|
|
Value *Offset = EmitGEPOffset(GEPLHS, I, *this);
|
|
return new SetCondInst(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 SetCondInst(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 FoldGEPSetCC(GEPRHS, GEPLHS->getOperand(0),
|
|
SetCondInst::getSwappedCondition(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 FoldGEPSetCC(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.
|
|
ConstantBool::get(Cond == Instruction::SetEQ));
|
|
else if (NumDifferences == 1) {
|
|
Value *LHSV = GEPLHS->getOperand(DiffOperand);
|
|
Value *RHSV = GEPRHS->getOperand(DiffOperand);
|
|
|
|
// Convert the operands to signed values to make sure to perform a
|
|
// signed comparison.
|
|
const Type *NewTy = LHSV->getType()->getSignedVersion();
|
|
if (LHSV->getType() != NewTy)
|
|
LHSV = InsertNewInstBefore(new CastInst(LHSV, NewTy,
|
|
LHSV->getName()), I);
|
|
if (RHSV->getType() != NewTy)
|
|
RHSV = InsertNewInstBefore(new CastInst(RHSV, NewTy,
|
|
RHSV->getName()), I);
|
|
return new SetCondInst(Cond, LHSV, RHSV);
|
|
}
|
|
}
|
|
|
|
// Only lower this if the setcc 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 SetCondInst(Cond, L, R);
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
|
|
Instruction *InstCombiner::visitSetCondInst(SetCondInst &I) {
|
|
bool Changed = SimplifyCommutative(I);
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
const Type *Ty = Op0->getType();
|
|
|
|
// setcc X, X
|
|
if (Op0 == Op1)
|
|
return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I)));
|
|
|
|
if (isa<UndefValue>(Op1)) // X setcc undef -> undef
|
|
return ReplaceInstUsesWith(I, UndefValue::get(Type::BoolTy));
|
|
|
|
// setcc <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, ConstantBool::get(!isTrueWhenEqual(I)));
|
|
|
|
// setcc's with boolean values can always be turned into bitwise operations
|
|
if (Ty == Type::BoolTy) {
|
|
switch (I.getOpcode()) {
|
|
default: assert(0 && "Invalid setcc instruction!");
|
|
case Instruction::SetEQ: { // seteq bool %A, %B -> ~(A^B)
|
|
Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp");
|
|
InsertNewInstBefore(Xor, I);
|
|
return BinaryOperator::createNot(Xor);
|
|
}
|
|
case Instruction::SetNE:
|
|
return BinaryOperator::createXor(Op0, Op1);
|
|
|
|
case Instruction::SetGT:
|
|
std::swap(Op0, Op1); // Change setgt -> setlt
|
|
// FALL THROUGH
|
|
case Instruction::SetLT: { // setlt bool A, B -> ~X & Y
|
|
Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
|
|
InsertNewInstBefore(Not, I);
|
|
return BinaryOperator::createAnd(Not, Op1);
|
|
}
|
|
case Instruction::SetGE:
|
|
std::swap(Op0, Op1); // Change setge -> setle
|
|
// FALL THROUGH
|
|
case Instruction::SetLE: { // setle bool %A, %B -> ~A | B
|
|
Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
|
|
InsertNewInstBefore(Not, I);
|
|
return BinaryOperator::createOr(Not, Op1);
|
|
}
|
|
}
|
|
}
|
|
|
|
// 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)) {
|
|
// Check to see if we are comparing against the minimum or maximum value...
|
|
if (CI->isMinValue()) {
|
|
if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
|
|
return ReplaceInstUsesWith(I, ConstantBool::False);
|
|
if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
|
|
return ReplaceInstUsesWith(I, ConstantBool::True);
|
|
if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
|
|
return BinaryOperator::createSetEQ(Op0, Op1);
|
|
if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
|
|
return BinaryOperator::createSetNE(Op0, Op1);
|
|
|
|
} else if (CI->isMaxValue()) {
|
|
if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
|
|
return ReplaceInstUsesWith(I, ConstantBool::False);
|
|
if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
|
|
return ReplaceInstUsesWith(I, ConstantBool::True);
|
|
if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
|
|
return BinaryOperator::createSetEQ(Op0, Op1);
|
|
if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
|
|
return BinaryOperator::createSetNE(Op0, Op1);
|
|
|
|
// Comparing against a value really close to min or max?
|
|
} else if (isMinValuePlusOne(CI)) {
|
|
if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
|
|
return BinaryOperator::createSetEQ(Op0, SubOne(CI));
|
|
if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
|
|
return BinaryOperator::createSetNE(Op0, SubOne(CI));
|
|
|
|
} else if (isMaxValueMinusOne(CI)) {
|
|
if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
|
|
return BinaryOperator::createSetEQ(Op0, AddOne(CI));
|
|
if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
|
|
return BinaryOperator::createSetNE(Op0, AddOne(CI));
|
|
}
|
|
|
|
// If we still have a setle or setge instruction, turn it into the
|
|
// appropriate setlt or setgt instruction. Since the border cases have
|
|
// already been handled above, this requires little checking.
|
|
//
|
|
if (I.getOpcode() == Instruction::SetLE)
|
|
return BinaryOperator::createSetLT(Op0, AddOne(CI));
|
|
if (I.getOpcode() == Instruction::SetGE)
|
|
return BinaryOperator::createSetGT(Op0, SubOne(CI));
|
|
|
|
if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
|
|
switch (LHSI->getOpcode()) {
|
|
case Instruction::And:
|
|
if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) &&
|
|
LHSI->getOperand(0)->hasOneUse()) {
|
|
// 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.
|
|
ShiftInst *Shift = dyn_cast<ShiftInst>(LHSI->getOperand(0));
|
|
ConstantUInt *ShAmt;
|
|
ShAmt = Shift ? dyn_cast<ConstantUInt>(Shift->getOperand(1)) : 0;
|
|
ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1));
|
|
const Type *Ty = LHSI->getType();
|
|
|
|
// 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->getOpcode() != Instruction::Shr ||
|
|
Shift->getType()->isUnsigned();
|
|
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.
|
|
int ShAmtVal = Ty->getPrimitiveSizeInBits()-ShAmt->getValue();
|
|
if (ShAmtVal < 0) ShAmtVal = 0; // Out of range shift.
|
|
|
|
Constant *OShAmt = ConstantUInt::get(Type::UByteTy, ShAmtVal);
|
|
Constant *ShVal =
|
|
ConstantExpr::getShl(ConstantInt::getAllOnesValue(Ty), OShAmt);
|
|
if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())
|
|
CanFold = true;
|
|
}
|
|
|
|
if (CanFold) {
|
|
Constant *NewCst;
|
|
if (Shift->getOpcode() == Instruction::Shl)
|
|
NewCst = ConstantExpr::getUShr(CI, ShAmt);
|
|
else
|
|
NewCst = ConstantExpr::getShl(CI, ShAmt);
|
|
|
|
// Check to see if we are shifting out any of the bits being
|
|
// compared.
|
|
if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){
|
|
// 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 (I.getOpcode() == Instruction::SetEQ)
|
|
return ReplaceInstUsesWith(I, ConstantBool::False);
|
|
if (I.getOpcode() == Instruction::SetNE)
|
|
return ReplaceInstUsesWith(I, ConstantBool::True);
|
|
} else {
|
|
I.setOperand(1, NewCst);
|
|
Constant *NewAndCST;
|
|
if (Shift->getOpcode() == Instruction::Shl)
|
|
NewAndCST = ConstantExpr::getUShr(AndCST, ShAmt);
|
|
else
|
|
NewAndCST = ConstantExpr::getShl(AndCST, ShAmt);
|
|
LHSI->setOperand(1, NewAndCST);
|
|
LHSI->setOperand(0, Shift->getOperand(0));
|
|
WorkList.push_back(Shift); // Shift is dead.
|
|
AddUsesToWorkList(I);
|
|
return &I;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
break;
|
|
|
|
case Instruction::Shl: // (setcc (shl X, ShAmt), CI)
|
|
if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
|
|
switch (I.getOpcode()) {
|
|
default: break;
|
|
case Instruction::SetEQ:
|
|
case Instruction::SetNE: {
|
|
unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
|
|
|
|
// 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->getValue() >= TypeBits)
|
|
break;
|
|
|
|
// If we are comparing against bits always shifted out, the
|
|
// comparison cannot succeed.
|
|
Constant *Comp =
|
|
ConstantExpr::getShl(ConstantExpr::getShr(CI, ShAmt), ShAmt);
|
|
if (Comp != CI) {// Comparing against a bit that we know is zero.
|
|
bool IsSetNE = I.getOpcode() == Instruction::SetNE;
|
|
Constant *Cst = ConstantBool::get(IsSetNE);
|
|
return ReplaceInstUsesWith(I, Cst);
|
|
}
|
|
|
|
if (LHSI->hasOneUse()) {
|
|
// Otherwise strength reduce the shift into an and.
|
|
unsigned ShAmtVal = (unsigned)ShAmt->getValue();
|
|
uint64_t Val = (1ULL << (TypeBits-ShAmtVal))-1;
|
|
|
|
Constant *Mask;
|
|
if (CI->getType()->isUnsigned()) {
|
|
Mask = ConstantUInt::get(CI->getType(), Val);
|
|
} else if (ShAmtVal != 0) {
|
|
Mask = ConstantSInt::get(CI->getType(), Val);
|
|
} else {
|
|
Mask = ConstantInt::getAllOnesValue(CI->getType());
|
|
}
|
|
|
|
Instruction *AndI =
|
|
BinaryOperator::createAnd(LHSI->getOperand(0),
|
|
Mask, LHSI->getName()+".mask");
|
|
Value *And = InsertNewInstBefore(AndI, I);
|
|
return new SetCondInst(I.getOpcode(), And,
|
|
ConstantExpr::getUShr(CI, ShAmt));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
break;
|
|
|
|
case Instruction::Shr: // (setcc (shr X, ShAmt), CI)
|
|
if (ConstantUInt *ShAmt = dyn_cast<ConstantUInt>(LHSI->getOperand(1))) {
|
|
switch (I.getOpcode()) {
|
|
default: break;
|
|
case Instruction::SetEQ:
|
|
case Instruction::SetNE: {
|
|
|
|
// Check that the shift amount is in range. If not, don't perform
|
|
// undefined shifts. When the shift is visited it will be
|
|
// simplified.
|
|
unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
|
|
if (ShAmt->getValue() >= TypeBits)
|
|
break;
|
|
|
|
// If we are comparing against bits always shifted out, the
|
|
// comparison cannot succeed.
|
|
Constant *Comp =
|
|
ConstantExpr::getShr(ConstantExpr::getShl(CI, ShAmt), ShAmt);
|
|
|
|
if (Comp != CI) {// Comparing against a bit that we know is zero.
|
|
bool IsSetNE = I.getOpcode() == Instruction::SetNE;
|
|
Constant *Cst = ConstantBool::get(IsSetNE);
|
|
return ReplaceInstUsesWith(I, Cst);
|
|
}
|
|
|
|
if (LHSI->hasOneUse() || CI->isNullValue()) {
|
|
unsigned ShAmtVal = (unsigned)ShAmt->getValue();
|
|
|
|
// Otherwise strength reduce the shift into an and.
|
|
uint64_t Val = ~0ULL; // All ones.
|
|
Val <<= ShAmtVal; // Shift over to the right spot.
|
|
|
|
Constant *Mask;
|
|
if (CI->getType()->isUnsigned()) {
|
|
Val &= ~0ULL >> (64-TypeBits);
|
|
Mask = ConstantUInt::get(CI->getType(), Val);
|
|
} else {
|
|
Mask = ConstantSInt::get(CI->getType(), Val);
|
|
}
|
|
|
|
Instruction *AndI =
|
|
BinaryOperator::createAnd(LHSI->getOperand(0),
|
|
Mask, LHSI->getName()+".mask");
|
|
Value *And = InsertNewInstBefore(AndI, I);
|
|
return new SetCondInst(I.getOpcode(), And,
|
|
ConstantExpr::getShl(CI, ShAmt));
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
break;
|
|
|
|
case Instruction::Div:
|
|
// Fold: (div X, C1) op C2 -> range check
|
|
if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) {
|
|
// 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.
|
|
bool LoOverflow = false, HiOverflow = 0;
|
|
ConstantInt *LoBound = 0, *HiBound = 0;
|
|
|
|
ConstantInt *Prod;
|
|
bool ProdOV = MulWithOverflow(Prod, CI, DivRHS);
|
|
|
|
Instruction::BinaryOps Opcode = I.getOpcode();
|
|
|
|
if (DivRHS->isNullValue()) { // Don't hack on divide by zeros.
|
|
} else if (LHSI->getType()->isUnsigned()) { // udiv
|
|
LoBound = Prod;
|
|
LoOverflow = ProdOV;
|
|
HiOverflow = ProdOV || AddWithOverflow(HiBound, LoBound, DivRHS);
|
|
} else if (isPositive(DivRHS)) { // Divisor is > 0.
|
|
if (CI->isNullValue()) { // (X / pos) op 0
|
|
// Can't overflow.
|
|
LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS)));
|
|
HiBound = DivRHS;
|
|
} else if (isPositive(CI)) { // (X / pos) op pos
|
|
LoBound = Prod;
|
|
LoOverflow = ProdOV;
|
|
HiOverflow = ProdOV || AddWithOverflow(HiBound, Prod, DivRHS);
|
|
} else { // (X / pos) op neg
|
|
Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS));
|
|
LoOverflow = AddWithOverflow(LoBound, Prod,
|
|
cast<ConstantInt>(DivRHSH));
|
|
HiBound = Prod;
|
|
HiOverflow = ProdOV;
|
|
}
|
|
} else { // Divisor is < 0.
|
|
if (CI->isNullValue()) { // (X / neg) op 0
|
|
LoBound = AddOne(DivRHS);
|
|
HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS));
|
|
if (HiBound == DivRHS)
|
|
LoBound = 0; // - INTMIN = INTMIN
|
|
} else if (isPositive(CI)) { // (X / neg) op pos
|
|
HiOverflow = LoOverflow = ProdOV;
|
|
if (!LoOverflow)
|
|
LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS));
|
|
HiBound = AddOne(Prod);
|
|
} else { // (X / neg) op neg
|
|
LoBound = Prod;
|
|
LoOverflow = HiOverflow = ProdOV;
|
|
HiBound = cast<ConstantInt>(ConstantExpr::getSub(Prod, DivRHS));
|
|
}
|
|
|
|
// Dividing by a negate swaps the condition.
|
|
Opcode = SetCondInst::getSwappedCondition(Opcode);
|
|
}
|
|
|
|
if (LoBound) {
|
|
Value *X = LHSI->getOperand(0);
|
|
switch (Opcode) {
|
|
default: assert(0 && "Unhandled setcc opcode!");
|
|
case Instruction::SetEQ:
|
|
if (LoOverflow && HiOverflow)
|
|
return ReplaceInstUsesWith(I, ConstantBool::False);
|
|
else if (HiOverflow)
|
|
return new SetCondInst(Instruction::SetGE, X, LoBound);
|
|
else if (LoOverflow)
|
|
return new SetCondInst(Instruction::SetLT, X, HiBound);
|
|
else
|
|
return InsertRangeTest(X, LoBound, HiBound, true, I);
|
|
case Instruction::SetNE:
|
|
if (LoOverflow && HiOverflow)
|
|
return ReplaceInstUsesWith(I, ConstantBool::True);
|
|
else if (HiOverflow)
|
|
return new SetCondInst(Instruction::SetLT, X, LoBound);
|
|
else if (LoOverflow)
|
|
return new SetCondInst(Instruction::SetGE, X, HiBound);
|
|
else
|
|
return InsertRangeTest(X, LoBound, HiBound, false, I);
|
|
case Instruction::SetLT:
|
|
if (LoOverflow)
|
|
return ReplaceInstUsesWith(I, ConstantBool::False);
|
|
return new SetCondInst(Instruction::SetLT, X, LoBound);
|
|
case Instruction::SetGT:
|
|
if (HiOverflow)
|
|
return ReplaceInstUsesWith(I, ConstantBool::False);
|
|
return new SetCondInst(Instruction::SetGE, X, HiBound);
|
|
}
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
|
|
// Simplify seteq and setne instructions...
|
|
if (I.getOpcode() == Instruction::SetEQ ||
|
|
I.getOpcode() == Instruction::SetNE) {
|
|
bool isSetNE = I.getOpcode() == Instruction::SetNE;
|
|
|
|
// If the first operand is (and|or|xor) with a constant, and the second
|
|
// operand is a constant, simplify a bit.
|
|
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) {
|
|
switch (BO->getOpcode()) {
|
|
case Instruction::Rem:
|
|
// If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
|
|
if (CI->isNullValue() && isa<ConstantSInt>(BO->getOperand(1)) &&
|
|
BO->hasOneUse() &&
|
|
cast<ConstantSInt>(BO->getOperand(1))->getValue() > 1) {
|
|
int64_t V = cast<ConstantSInt>(BO->getOperand(1))->getValue();
|
|
if (isPowerOf2_64(V)) {
|
|
unsigned L2 = Log2_64(V);
|
|
const Type *UTy = BO->getType()->getUnsignedVersion();
|
|
Value *NewX = InsertNewInstBefore(new CastInst(BO->getOperand(0),
|
|
UTy, "tmp"), I);
|
|
Constant *RHSCst = ConstantUInt::get(UTy, 1ULL << L2);
|
|
Value *NewRem =InsertNewInstBefore(BinaryOperator::createRem(NewX,
|
|
RHSCst, BO->getName()), I);
|
|
return BinaryOperator::create(I.getOpcode(), NewRem,
|
|
Constant::getNullValue(UTy));
|
|
}
|
|
}
|
|
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 SetCondInst(I.getOpcode(), BO->getOperand(0),
|
|
ConstantExpr::getSub(CI, BOp1C));
|
|
} else if (CI->isNullValue()) {
|
|
// 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 SetCondInst(I.getOpcode(), BOp0, NegVal);
|
|
else if (Value *NegVal = dyn_castNegVal(BOp0))
|
|
return new SetCondInst(I.getOpcode(), NegVal, BOp1);
|
|
else if (BO->hasOneUse()) {
|
|
Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName());
|
|
BO->setName("");
|
|
InsertNewInstBefore(Neg, I);
|
|
return new SetCondInst(I.getOpcode(), 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 BinaryOperator::create(I.getOpcode(), BO->getOperand(0),
|
|
ConstantExpr::getXor(CI, BOC));
|
|
|
|
// FALLTHROUGH
|
|
case Instruction::Sub:
|
|
// Replace (([sub|xor] A, B) != 0) with (A != B)
|
|
if (CI->isNullValue())
|
|
return new SetCondInst(I.getOpcode(), 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(CI);
|
|
if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue())
|
|
return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
|
|
}
|
|
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 (!ConstantExpr::getAnd(CI,
|
|
ConstantExpr::getNot(BOC))->isNullValue())
|
|
return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
|
|
|
|
// If we have ((X & C) == C), turn it into ((X & C) != 0).
|
|
if (CI == BOC && isOneBitSet(CI))
|
|
return new SetCondInst(isSetNE ? Instruction::SetEQ :
|
|
Instruction::SetNE, Op0,
|
|
Constant::getNullValue(CI->getType()));
|
|
|
|
// Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X
|
|
// to be a signed value as appropriate.
|
|
if (isSignBit(BOC)) {
|
|
Value *X = BO->getOperand(0);
|
|
// If 'X' is not signed, insert a cast now...
|
|
if (!BOC->getType()->isSigned()) {
|
|
const Type *DestTy = BOC->getType()->getSignedVersion();
|
|
X = InsertCastBefore(X, DestTy, I);
|
|
}
|
|
return new SetCondInst(isSetNE ? Instruction::SetLT :
|
|
Instruction::SetGE, X,
|
|
Constant::getNullValue(X->getType()));
|
|
}
|
|
|
|
// ((X & ~7) == 0) --> X < 8
|
|
if (CI->isNullValue() && isHighOnes(BOC)) {
|
|
Value *X = BO->getOperand(0);
|
|
Constant *NegX = ConstantExpr::getNeg(BOC);
|
|
|
|
// If 'X' is signed, insert a cast now.
|
|
if (NegX->getType()->isSigned()) {
|
|
const Type *DestTy = NegX->getType()->getUnsignedVersion();
|
|
X = InsertCastBefore(X, DestTy, I);
|
|
NegX = ConstantExpr::getCast(NegX, DestTy);
|
|
}
|
|
|
|
return new SetCondInst(isSetNE ? Instruction::SetGE :
|
|
Instruction::SetLT, X, NegX);
|
|
}
|
|
|
|
}
|
|
default: break;
|
|
}
|
|
}
|
|
} else { // Not a SetEQ/SetNE
|
|
// If the LHS is a cast from an integral value of the same size,
|
|
if (CastInst *Cast = dyn_cast<CastInst>(Op0)) {
|
|
Value *CastOp = Cast->getOperand(0);
|
|
const Type *SrcTy = CastOp->getType();
|
|
unsigned SrcTySize = SrcTy->getPrimitiveSizeInBits();
|
|
if (SrcTy != Cast->getType() && SrcTy->isInteger() &&
|
|
SrcTySize == Cast->getType()->getPrimitiveSizeInBits()) {
|
|
assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) &&
|
|
"Source and destination signednesses should differ!");
|
|
if (Cast->getType()->isSigned()) {
|
|
// If this is a signed comparison, check for comparisons in the
|
|
// vicinity of zero.
|
|
if (I.getOpcode() == Instruction::SetLT && CI->isNullValue())
|
|
// X < 0 => x > 127
|
|
return BinaryOperator::createSetGT(CastOp,
|
|
ConstantUInt::get(SrcTy, (1ULL << (SrcTySize-1))-1));
|
|
else if (I.getOpcode() == Instruction::SetGT &&
|
|
cast<ConstantSInt>(CI)->getValue() == -1)
|
|
// X > -1 => x < 128
|
|
return BinaryOperator::createSetLT(CastOp,
|
|
ConstantUInt::get(SrcTy, 1ULL << (SrcTySize-1)));
|
|
} else {
|
|
ConstantUInt *CUI = cast<ConstantUInt>(CI);
|
|
if (I.getOpcode() == Instruction::SetLT &&
|
|
CUI->getValue() == 1ULL << (SrcTySize-1))
|
|
// X < 128 => X > -1
|
|
return BinaryOperator::createSetGT(CastOp,
|
|
ConstantSInt::get(SrcTy, -1));
|
|
else if (I.getOpcode() == Instruction::SetGT &&
|
|
CUI->getValue() == (1ULL << (SrcTySize-1))-1)
|
|
// X > 127 => X < 0
|
|
return BinaryOperator::createSetLT(CastOp,
|
|
Constant::getNullValue(SrcTy));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Handle setcc with constant RHS's that can be integer, FP or pointer.
|
|
if (Constant *RHSC = dyn_cast<Constant>(Op1)) {
|
|
if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
|
|
switch (LHSI->getOpcode()) {
|
|
case Instruction::GetElementPtr:
|
|
if (RHSC->isNullValue()) {
|
|
// Transform setcc GEP P, int 0, int 0, int 0, null -> setcc 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 SetCondInst(I.getOpcode(), LHSI->getOperand(0),
|
|
Constant::getNullValue(LHSI->getOperand(0)->getType()));
|
|
}
|
|
break;
|
|
|
|
case Instruction::PHI:
|
|
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::get(I.getOpcode(), C, RHSC);
|
|
// Insert a new SetCC of the other select operand.
|
|
Op2 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
|
|
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::get(I.getOpcode(), C, RHSC);
|
|
// Insert a new SetCC of the other select operand.
|
|
Op1 = InsertNewInstBefore(new SetCondInst(I.getOpcode(),
|
|
LHSI->getOperand(1), RHSC,
|
|
I.getName()), I);
|
|
}
|
|
}
|
|
|
|
if (Op1)
|
|
return new SelectInst(LHSI->getOperand(0), Op1, Op2);
|
|
break;
|
|
}
|
|
}
|
|
|
|
// If we can optimize a 'setcc GEP, P' or 'setcc P, GEP', do so now.
|
|
if (User *GEP = dyn_castGetElementPtr(Op0))
|
|
if (Instruction *NI = FoldGEPSetCC(GEP, Op1, I.getOpcode(), I))
|
|
return NI;
|
|
if (User *GEP = dyn_castGetElementPtr(Op1))
|
|
if (Instruction *NI = FoldGEPSetCC(GEP, Op0,
|
|
SetCondInst::getSwappedCondition(I.getOpcode()), I))
|
|
return NI;
|
|
|
|
// Test to see if the operands of the setcc are casted versions of other
|
|
// values. If the cast can be stripped off both arguments, we do so now.
|
|
if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
|
|
Value *CastOp0 = CI->getOperand(0);
|
|
if (CastOp0->getType()->isLosslesslyConvertibleTo(CI->getType()) &&
|
|
(isa<Constant>(Op1) || isa<CastInst>(Op1)) &&
|
|
(I.getOpcode() == Instruction::SetEQ ||
|
|
I.getOpcode() == Instruction::SetNE)) {
|
|
// We keep moving the cast from the left operand over to the right
|
|
// operand, where it can often be eliminated completely.
|
|
Op0 = CastOp0;
|
|
|
|
// If operand #1 is a cast instruction, see if we can eliminate it as
|
|
// well.
|
|
if (CastInst *CI2 = dyn_cast<CastInst>(Op1))
|
|
if (CI2->getOperand(0)->getType()->isLosslesslyConvertibleTo(
|
|
Op0->getType()))
|
|
Op1 = CI2->getOperand(0);
|
|
|
|
// If Op1 is a constant, we can fold the cast into the constant.
|
|
if (Op1->getType() != Op0->getType())
|
|
if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
|
|
Op1 = ConstantExpr::getCast(Op1C, Op0->getType());
|
|
} else {
|
|
// Otherwise, cast the RHS right before the setcc
|
|
Op1 = new CastInst(Op1, Op0->getType(), Op1->getName());
|
|
InsertNewInstBefore(cast<Instruction>(Op1), I);
|
|
}
|
|
return BinaryOperator::create(I.getOpcode(), Op0, Op1);
|
|
}
|
|
|
|
// Handle the special case of: setcc (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 = visitSetCondInstWithCastAndCast(I))
|
|
return R;
|
|
}
|
|
return Changed ? &I : 0;
|
|
}
|
|
|
|
// visitSetCondInstWithCastAndCast - Handle setcond (cast x to y), (cast/cst).
|
|
// We only handle extending casts so far.
|
|
//
|
|
Instruction *InstCombiner::visitSetCondInstWithCastAndCast(SetCondInst &SCI) {
|
|
Value *LHSCIOp = cast<CastInst>(SCI.getOperand(0))->getOperand(0);
|
|
const Type *SrcTy = LHSCIOp->getType();
|
|
const Type *DestTy = SCI.getOperand(0)->getType();
|
|
Value *RHSCIOp;
|
|
|
|
if (!DestTy->isIntegral() || !SrcTy->isIntegral())
|
|
return 0;
|
|
|
|
unsigned SrcBits = SrcTy->getPrimitiveSizeInBits();
|
|
unsigned DestBits = DestTy->getPrimitiveSizeInBits();
|
|
if (SrcBits >= DestBits) return 0; // Only handle extending cast.
|
|
|
|
// Is this a sign or zero extension?
|
|
bool isSignSrc = SrcTy->isSigned();
|
|
bool isSignDest = DestTy->isSigned();
|
|
|
|
if (CastInst *CI = dyn_cast<CastInst>(SCI.getOperand(1))) {
|
|
// Not an extension from the same type?
|
|
RHSCIOp = CI->getOperand(0);
|
|
if (RHSCIOp->getType() != LHSCIOp->getType()) return 0;
|
|
} else if (ConstantInt *CI = dyn_cast<ConstantInt>(SCI.getOperand(1))) {
|
|
// Compute the constant that would happen if we truncated to SrcTy then
|
|
// reextended to DestTy.
|
|
Constant *Res = ConstantExpr::getCast(CI, SrcTy);
|
|
|
|
if (ConstantExpr::getCast(Res, DestTy) == CI) {
|
|
RHSCIOp = Res;
|
|
} else {
|
|
// If the value cannot be represented in the shorter type, we cannot emit
|
|
// a simple comparison.
|
|
if (SCI.getOpcode() == Instruction::SetEQ)
|
|
return ReplaceInstUsesWith(SCI, ConstantBool::False);
|
|
if (SCI.getOpcode() == Instruction::SetNE)
|
|
return ReplaceInstUsesWith(SCI, ConstantBool::True);
|
|
|
|
// Evaluate the comparison for LT.
|
|
Value *Result;
|
|
if (DestTy->isSigned()) {
|
|
// We're performing a signed comparison.
|
|
if (isSignSrc) {
|
|
// Signed extend and signed comparison.
|
|
if (cast<ConstantSInt>(CI)->getValue() < 0) // X < (small) --> false
|
|
Result = ConstantBool::False;
|
|
else
|
|
Result = ConstantBool::True; // X < (large) --> true
|
|
} else {
|
|
// Unsigned extend and signed comparison.
|
|
if (cast<ConstantSInt>(CI)->getValue() < 0)
|
|
Result = ConstantBool::False;
|
|
else
|
|
Result = ConstantBool::True;
|
|
}
|
|
} else {
|
|
// We're performing an unsigned comparison.
|
|
if (!isSignSrc) {
|
|
// Unsigned extend & compare -> always true.
|
|
Result = ConstantBool::True;
|
|
} else {
|
|
// We're performing an unsigned comp with a sign extended value.
|
|
// This is true if the input is >= 0. [aka >s -1]
|
|
Constant *NegOne = ConstantIntegral::getAllOnesValue(SrcTy);
|
|
Result = InsertNewInstBefore(BinaryOperator::createSetGT(LHSCIOp,
|
|
NegOne, SCI.getName()), SCI);
|
|
}
|
|
}
|
|
|
|
// Finally, return the value computed.
|
|
if (SCI.getOpcode() == Instruction::SetLT) {
|
|
return ReplaceInstUsesWith(SCI, Result);
|
|
} else {
|
|
assert(SCI.getOpcode()==Instruction::SetGT &&"SetCC should be folded!");
|
|
if (Constant *CI = dyn_cast<Constant>(Result))
|
|
return ReplaceInstUsesWith(SCI, ConstantExpr::getNot(CI));
|
|
else
|
|
return BinaryOperator::createNot(Result);
|
|
}
|
|
}
|
|
} else {
|
|
return 0;
|
|
}
|
|
|
|
// Okay, just insert a compare of the reduced operands now!
|
|
return BinaryOperator::create(SCI.getOpcode(), LHSCIOp, RHSCIOp);
|
|
}
|
|
|
|
Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
|
|
assert(I.getOperand(1)->getType() == Type::UByteTy);
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
bool isLeftShift = I.getOpcode() == Instruction::Shl;
|
|
|
|
// shl X, 0 == X and shr X, 0 == X
|
|
// shl 0, X == 0 and shr 0, X == 0
|
|
if (Op1 == Constant::getNullValue(Type::UByteTy) ||
|
|
Op0 == Constant::getNullValue(Op0->getType()))
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
|
|
if (isa<UndefValue>(Op0)) { // undef >>s X -> undef
|
|
if (!isLeftShift && I.getType()->isSigned())
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
else // undef << X -> 0 AND undef >>u X -> 0
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
}
|
|
if (isa<UndefValue>(Op1)) {
|
|
if (isLeftShift || I.getType()->isUnsigned())// X << undef, X >>u undef -> 0
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
else
|
|
return ReplaceInstUsesWith(I, Op0); // X >>s undef -> X
|
|
}
|
|
|
|
// shr int -1, X = -1 (for any arithmetic shift rights of ~0)
|
|
if (!isLeftShift)
|
|
if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
|
|
if (CSI->isAllOnesValue())
|
|
return ReplaceInstUsesWith(I, CSI);
|
|
|
|
// 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;
|
|
|
|
// See if we can turn a signed shr into an unsigned shr.
|
|
if (!isLeftShift && I.getType()->isSigned()) {
|
|
if (MaskedValueIsZero(Op0, ConstantInt::getMinValue(I.getType()))) {
|
|
Value *V = InsertCastBefore(Op0, I.getType()->getUnsignedVersion(), I);
|
|
V = InsertNewInstBefore(new ShiftInst(Instruction::Shr, V, Op1,
|
|
I.getName()), I);
|
|
return new CastInst(V, I.getType());
|
|
}
|
|
}
|
|
|
|
if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) {
|
|
// shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr
|
|
// of a signed value.
|
|
//
|
|
unsigned TypeBits = Op0->getType()->getPrimitiveSizeInBits();
|
|
if (CUI->getValue() >= TypeBits) {
|
|
if (!Op0->getType()->isSigned() || isLeftShift)
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
|
|
else {
|
|
I.setOperand(1, ConstantUInt::get(Type::UByteTy, 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, CUI));
|
|
|
|
// 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 (Op0->hasOneUse()) {
|
|
// If this is a SHL of a sign-extending cast, see if we can turn the input
|
|
// into a zero extending cast (a simple strength reduction).
|
|
if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
|
|
const Type *SrcTy = CI->getOperand(0)->getType();
|
|
if (isLeftShift && SrcTy->isInteger() && SrcTy->isSigned() &&
|
|
SrcTy->getPrimitiveSizeInBits() <
|
|
CI->getType()->getPrimitiveSizeInBits()) {
|
|
// We can change it to a zero extension if we are shifting out all of
|
|
// the sign extended bits. To check this, form a mask of all of the
|
|
// sign extend bits, then shift them left and see if we have anything
|
|
// left.
|
|
Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy); // 1111
|
|
Mask = ConstantExpr::getZeroExtend(Mask, CI->getType()); // 00001111
|
|
Mask = ConstantExpr::getNot(Mask); // 1's in the sign bits: 11110000
|
|
if (ConstantExpr::getShl(Mask, CUI)->isNullValue()) {
|
|
// If the shift is nuking all of the sign bits, change this to a
|
|
// zero extension cast. To do this, cast the cast input to
|
|
// unsigned, then to the requested size.
|
|
Value *CastOp = CI->getOperand(0);
|
|
Instruction *NC =
|
|
new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
|
|
CI->getName()+".uns");
|
|
NC = InsertNewInstBefore(NC, I);
|
|
// Finally, insert a replacement for CI.
|
|
NC = new CastInst(NC, CI->getType(), CI->getName());
|
|
CI->setName("");
|
|
NC = InsertNewInstBefore(NC, I);
|
|
WorkList.push_back(CI); // Delete CI later.
|
|
I.setOperand(0, NC);
|
|
return &I; // The SHL operand was modified.
|
|
}
|
|
}
|
|
}
|
|
|
|
if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) {
|
|
// Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C)
|
|
Value *V1, *V2, *V3;
|
|
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_ConstantInt(CC))) && CC == CUI) {
|
|
Instruction *YS = new ShiftInst(Instruction::Shl,
|
|
Op0BO->getOperand(0), CUI,
|
|
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))
|
|
Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
|
|
C2 = ConstantExpr::getShl(C2, CUI);
|
|
return BinaryOperator::createAnd(X, C2);
|
|
}
|
|
|
|
// Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C))
|
|
if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() &&
|
|
match(Op0BO->getOperand(1),
|
|
m_And(m_Shr(m_Value(V1), m_Value(V2)),
|
|
m_ConstantInt(CC))) && V2 == CUI &&
|
|
cast<BinaryOperator>(Op0BO->getOperand(1))->getOperand(0)->hasOneUse()) {
|
|
Instruction *YS = new ShiftInst(Instruction::Shl,
|
|
Op0BO->getOperand(0), CUI,
|
|
Op0BO->getName());
|
|
InsertNewInstBefore(YS, I); // (Y << C)
|
|
Instruction *XM =
|
|
BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, CUI),
|
|
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_ConstantInt(CC))) && CC == CUI) {
|
|
Instruction *YS = new ShiftInst(Instruction::Shl,
|
|
Op0BO->getOperand(1), CUI,
|
|
Op0BO->getName());
|
|
InsertNewInstBefore(YS, I); // (Y << C)
|
|
Instruction *X = BinaryOperator::create(Op0BO->getOpcode(), YS,
|
|
V1,
|
|
Op0BO->getOperand(0)->getName());
|
|
InsertNewInstBefore(X, I); // (X + (Y << C))
|
|
Constant *C2 = ConstantInt::getAllOnesValue(X->getType());
|
|
C2 = ConstantExpr::getShl(C2, CUI);
|
|
return BinaryOperator::createAnd(X, C2);
|
|
}
|
|
|
|
if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() &&
|
|
match(Op0BO->getOperand(0),
|
|
m_And(m_Shr(m_Value(V1), m_Value(V2)),
|
|
m_ConstantInt(CC))) && V2 == CUI &&
|
|
cast<BinaryOperator>(Op0BO->getOperand(0))->getOperand(0)->hasOneUse()) {
|
|
Instruction *YS = new ShiftInst(Instruction::Shl,
|
|
Op0BO->getOperand(1), CUI,
|
|
Op0BO->getName());
|
|
InsertNewInstBefore(YS, I); // (Y << C)
|
|
Instruction *XM =
|
|
BinaryOperator::createAnd(V1, ConstantExpr::getShl(CC, CUI),
|
|
V1->getName()+".mask");
|
|
InsertNewInstBefore(XM, I); // X & (CC << C)
|
|
|
|
return BinaryOperator::create(Op0BO->getOpcode(), YS, XM);
|
|
}
|
|
|
|
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 && !isLeftShift && !I.getType()->isUnsigned()) {
|
|
uint64_t Val = Op0C->getRawValue();
|
|
isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet;
|
|
}
|
|
|
|
if (isValid) {
|
|
Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, CUI);
|
|
|
|
Instruction *NewShift =
|
|
new ShiftInst(I.getOpcode(), Op0BO->getOperand(0), CUI,
|
|
Op0BO->getName());
|
|
Op0BO->setName("");
|
|
InsertNewInstBefore(NewShift, I);
|
|
|
|
return BinaryOperator::create(Op0BO->getOpcode(), NewShift,
|
|
NewRHS);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// If this is a shift of a shift, see if we can fold the two together...
|
|
if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0))
|
|
if (ConstantUInt *ShiftAmt1C =
|
|
dyn_cast<ConstantUInt>(Op0SI->getOperand(1))) {
|
|
unsigned ShiftAmt1 = (unsigned)ShiftAmt1C->getValue();
|
|
unsigned ShiftAmt2 = (unsigned)CUI->getValue();
|
|
|
|
// Check for (A << c1) << c2 and (A >> c1) >> c2
|
|
if (I.getOpcode() == Op0SI->getOpcode()) {
|
|
unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift...
|
|
if (Op0->getType()->getPrimitiveSizeInBits() < Amt)
|
|
Amt = Op0->getType()->getPrimitiveSizeInBits();
|
|
return new ShiftInst(I.getOpcode(), Op0SI->getOperand(0),
|
|
ConstantUInt::get(Type::UByteTy, Amt));
|
|
}
|
|
|
|
// Check for (A << c1) >> c2 or visaversa. If we are dealing with
|
|
// signed types, we can only support the (A >> c1) << c2 configuration,
|
|
// because it can not turn an arbitrary bit of A into a sign bit.
|
|
if (I.getType()->isUnsigned() || isLeftShift) {
|
|
// Calculate bitmask for what gets shifted off the edge...
|
|
Constant *C = ConstantIntegral::getAllOnesValue(I.getType());
|
|
if (isLeftShift)
|
|
C = ConstantExpr::getShl(C, ShiftAmt1C);
|
|
else
|
|
C = ConstantExpr::getShr(C, ShiftAmt1C);
|
|
|
|
Instruction *Mask =
|
|
BinaryOperator::createAnd(Op0SI->getOperand(0), C,
|
|
Op0SI->getOperand(0)->getName()+".mask");
|
|
InsertNewInstBefore(Mask, I);
|
|
|
|
// Figure out what flavor of shift we should use...
|
|
if (ShiftAmt1 == ShiftAmt2)
|
|
return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2
|
|
else if (ShiftAmt1 < ShiftAmt2) {
|
|
return new ShiftInst(I.getOpcode(), Mask,
|
|
ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1));
|
|
} else {
|
|
return new ShiftInst(Op0SI->getOpcode(), Mask,
|
|
ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
|
|
}
|
|
} else {
|
|
// We can handle signed (X << C1) >> C2 if it's a sign extend. In
|
|
// this case, C1 == C2 and C1 is 8, 16, or 32.
|
|
if (ShiftAmt1 == ShiftAmt2) {
|
|
const Type *SExtType = 0;
|
|
switch (ShiftAmt1) {
|
|
case 8 : SExtType = Type::SByteTy; break;
|
|
case 16: SExtType = Type::ShortTy; break;
|
|
case 32: SExtType = Type::IntTy; break;
|
|
}
|
|
|
|
if (SExtType) {
|
|
Instruction *NewTrunc = new CastInst(Op0SI->getOperand(0),
|
|
SExtType, "sext");
|
|
InsertNewInstBefore(NewTrunc, I);
|
|
return new CastInst(NewTrunc, I.getType());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
enum CastType {
|
|
Noop = 0,
|
|
Truncate = 1,
|
|
Signext = 2,
|
|
Zeroext = 3
|
|
};
|
|
|
|
/// getCastType - In the future, we will split the cast instruction into these
|
|
/// various types. Until then, we have to do the analysis here.
|
|
static CastType getCastType(const Type *Src, const Type *Dest) {
|
|
assert(Src->isIntegral() && Dest->isIntegral() &&
|
|
"Only works on integral types!");
|
|
unsigned SrcSize = Src->getPrimitiveSizeInBits();
|
|
unsigned DestSize = Dest->getPrimitiveSizeInBits();
|
|
|
|
if (SrcSize == DestSize) return Noop;
|
|
if (SrcSize > DestSize) return Truncate;
|
|
if (Src->isSigned()) return Signext;
|
|
return Zeroext;
|
|
}
|
|
|
|
|
|
// isEliminableCastOfCast - Return true if it is valid to eliminate the CI
|
|
// instruction.
|
|
//
|
|
static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
|
|
const Type *DstTy, TargetData *TD) {
|
|
|
|
// It is legal to eliminate the instruction if casting A->B->A if the sizes
|
|
// are identical and the bits don't get reinterpreted (for example
|
|
// int->float->int would not be allowed).
|
|
if (SrcTy == DstTy && SrcTy->isLosslesslyConvertibleTo(MidTy))
|
|
return true;
|
|
|
|
// If we are casting between pointer and integer types, treat pointers as
|
|
// integers of the appropriate size for the code below.
|
|
if (isa<PointerType>(SrcTy)) SrcTy = TD->getIntPtrType();
|
|
if (isa<PointerType>(MidTy)) MidTy = TD->getIntPtrType();
|
|
if (isa<PointerType>(DstTy)) DstTy = TD->getIntPtrType();
|
|
|
|
// Allow free casting and conversion of sizes as long as the sign doesn't
|
|
// change...
|
|
if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
|
|
CastType FirstCast = getCastType(SrcTy, MidTy);
|
|
CastType SecondCast = getCastType(MidTy, DstTy);
|
|
|
|
// Capture the effect of these two casts. If the result is a legal cast,
|
|
// the CastType is stored here, otherwise a special code is used.
|
|
static const unsigned CastResult[] = {
|
|
// First cast is noop
|
|
0, 1, 2, 3,
|
|
// First cast is a truncate
|
|
1, 1, 4, 4, // trunc->extend is not safe to eliminate
|
|
// First cast is a sign ext
|
|
2, 5, 2, 4, // signext->zeroext never ok
|
|
// First cast is a zero ext
|
|
3, 5, 3, 3,
|
|
};
|
|
|
|
unsigned Result = CastResult[FirstCast*4+SecondCast];
|
|
switch (Result) {
|
|
default: assert(0 && "Illegal table value!");
|
|
case 0:
|
|
case 1:
|
|
case 2:
|
|
case 3:
|
|
// FIXME: in the future, when LLVM has explicit sign/zeroextends and
|
|
// truncates, we could eliminate more casts.
|
|
return (unsigned)getCastType(SrcTy, DstTy) == Result;
|
|
case 4:
|
|
return false; // Not possible to eliminate this here.
|
|
case 5:
|
|
// Sign or zero extend followed by truncate is always ok if the result
|
|
// is a truncate or noop.
|
|
CastType ResultCast = getCastType(SrcTy, DstTy);
|
|
if (ResultCast == Noop || ResultCast == Truncate)
|
|
return true;
|
|
// Otherwise we are still growing the value, we are only safe if the
|
|
// result will match the sign/zeroextendness of the result.
|
|
return ResultCast == FirstCast;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
static bool ValueRequiresCast(const Value *V, const Type *Ty, TargetData *TD) {
|
|
if (V->getType() == Ty || isa<Constant>(V)) return false;
|
|
if (const CastInst *CI = dyn_cast<CastInst>(V))
|
|
if (isEliminableCastOfCast(CI->getOperand(0)->getType(), CI->getType(), Ty,
|
|
TD))
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
/// InsertOperandCastBefore - This inserts a cast of V to DestTy before the
|
|
/// InsertBefore instruction. This is specialized a bit to avoid inserting
|
|
/// casts that are known to not do anything...
|
|
///
|
|
Value *InstCombiner::InsertOperandCastBefore(Value *V, const Type *DestTy,
|
|
Instruction *InsertBefore) {
|
|
if (V->getType() == DestTy) return V;
|
|
if (Constant *C = dyn_cast<Constant>(V))
|
|
return ConstantExpr::getCast(C, DestTy);
|
|
|
|
CastInst *CI = new CastInst(V, DestTy, V->getName());
|
|
InsertNewInstBefore(CI, *InsertBefore);
|
|
return CI;
|
|
}
|
|
|
|
// CastInst simplification
|
|
//
|
|
Instruction *InstCombiner::visitCastInst(CastInst &CI) {
|
|
Value *Src = CI.getOperand(0);
|
|
|
|
// If the user is casting a value to the same type, eliminate this cast
|
|
// instruction...
|
|
if (CI.getType() == Src->getType())
|
|
return ReplaceInstUsesWith(CI, Src);
|
|
|
|
if (isa<UndefValue>(Src)) // cast undef -> undef
|
|
return ReplaceInstUsesWith(CI, UndefValue::get(CI.getType()));
|
|
|
|
// If casting the result of another cast instruction, try to eliminate this
|
|
// one!
|
|
//
|
|
if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
|
|
Value *A = CSrc->getOperand(0);
|
|
if (isEliminableCastOfCast(A->getType(), CSrc->getType(),
|
|
CI.getType(), TD)) {
|
|
// This instruction now refers directly to the cast's src operand. This
|
|
// has a good chance of making CSrc dead.
|
|
CI.setOperand(0, CSrc->getOperand(0));
|
|
return &CI;
|
|
}
|
|
|
|
// If this is an A->B->A cast, and we are dealing with integral types, try
|
|
// to convert this into a logical 'and' instruction.
|
|
//
|
|
if (A->getType()->isInteger() &&
|
|
CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
|
|
CSrc->getType()->isUnsigned() && // B->A cast must zero extend
|
|
CSrc->getType()->getPrimitiveSizeInBits() <
|
|
CI.getType()->getPrimitiveSizeInBits()&&
|
|
A->getType()->getPrimitiveSizeInBits() ==
|
|
CI.getType()->getPrimitiveSizeInBits()) {
|
|
assert(CSrc->getType() != Type::ULongTy &&
|
|
"Cannot have type bigger than ulong!");
|
|
uint64_t AndValue = ~0ULL>>(64-CSrc->getType()->getPrimitiveSizeInBits());
|
|
Constant *AndOp = ConstantUInt::get(A->getType()->getUnsignedVersion(),
|
|
AndValue);
|
|
AndOp = ConstantExpr::getCast(AndOp, A->getType());
|
|
Instruction *And = BinaryOperator::createAnd(CSrc->getOperand(0), AndOp);
|
|
if (And->getType() != CI.getType()) {
|
|
And->setName(CSrc->getName()+".mask");
|
|
InsertNewInstBefore(And, CI);
|
|
And = new CastInst(And, CI.getType());
|
|
}
|
|
return And;
|
|
}
|
|
}
|
|
|
|
// If this is a cast to bool, turn it into the appropriate setne instruction.
|
|
if (CI.getType() == Type::BoolTy)
|
|
return BinaryOperator::createSetNE(CI.getOperand(0),
|
|
Constant::getNullValue(CI.getOperand(0)->getType()));
|
|
|
|
// If casting the result of a getelementptr instruction with no offset, turn
|
|
// this into a cast of the original pointer!
|
|
//
|
|
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
|
|
bool AllZeroOperands = true;
|
|
for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
|
|
if (!isa<Constant>(GEP->getOperand(i)) ||
|
|
!cast<Constant>(GEP->getOperand(i))->isNullValue()) {
|
|
AllZeroOperands = false;
|
|
break;
|
|
}
|
|
if (AllZeroOperands) {
|
|
CI.setOperand(0, GEP->getOperand(0));
|
|
return &CI;
|
|
}
|
|
}
|
|
|
|
// 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 (AI->hasOneUse() && !AI->isArrayAllocation())
|
|
if (const PointerType *PTy = dyn_cast<PointerType>(CI.getType())) {
|
|
// 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()) {
|
|
uint64_t AllocElTySize = TD->getTypeSize(AllocElTy);
|
|
uint64_t CastElTySize = TD->getTypeSize(CastElTy);
|
|
|
|
// If the allocation is for an even multiple of the cast type size
|
|
if (CastElTySize && (AllocElTySize % CastElTySize == 0)) {
|
|
Value *Amt = ConstantUInt::get(Type::UIntTy,
|
|
AllocElTySize/CastElTySize);
|
|
std::string Name = AI->getName(); AI->setName("");
|
|
AllocationInst *New;
|
|
if (isa<MallocInst>(AI))
|
|
New = new MallocInst(CastElTy, Amt, Name);
|
|
else
|
|
New = new AllocaInst(CastElTy, Amt, Name);
|
|
InsertNewInstBefore(New, *AI);
|
|
return ReplaceInstUsesWith(CI, New);
|
|
}
|
|
}
|
|
}
|
|
|
|
if (SelectInst *SI = dyn_cast<SelectInst>(Src))
|
|
if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
|
|
return NV;
|
|
if (isa<PHINode>(Src))
|
|
if (Instruction *NV = FoldOpIntoPhi(CI))
|
|
return NV;
|
|
|
|
// If the source value is an instruction with only this use, we can attempt to
|
|
// propagate the cast into the instruction. Also, only handle integral types
|
|
// for now.
|
|
if (Instruction *SrcI = dyn_cast<Instruction>(Src))
|
|
if (SrcI->hasOneUse() && Src->getType()->isIntegral() &&
|
|
CI.getType()->isInteger()) { // Don't mess with casts to bool here
|
|
const Type *DestTy = CI.getType();
|
|
unsigned SrcBitSize = Src->getType()->getPrimitiveSizeInBits();
|
|
unsigned DestBitSize = DestTy->getPrimitiveSizeInBits();
|
|
|
|
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, or just changing the sign, 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(Op1, DestTy,TD) ||
|
|
!ValueRequiresCast(Op0, DestTy, TD)) {
|
|
Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
|
|
Value *Op1c = InsertOperandCastBefore(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 (SrcBitSize == 1 && SrcI->getOpcode() == Instruction::Xor &&
|
|
Op1 == ConstantBool::True &&
|
|
(!Op0->hasOneUse() || !isa<SetCondInst>(Op0))) {
|
|
Value *New = InsertOperandCastBefore(Op0, DestTy, &CI);
|
|
return BinaryOperator::createXor(New,
|
|
ConstantInt::get(CI.getType(), 1));
|
|
}
|
|
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
|
|
// mush 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))) {
|
|
Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
|
|
return new ShiftInst(Instruction::Shl, Op0c, Op1);
|
|
}
|
|
break;
|
|
case Instruction::Shr:
|
|
// 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 && Src->getType()->isSigned() &&
|
|
isa<ConstantInt>(Op1)) {
|
|
unsigned ShiftAmt = cast<ConstantUInt>(Op1)->getValue();
|
|
if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) {
|
|
// Convert to unsigned.
|
|
Value *N1 = InsertOperandCastBefore(Op0,
|
|
Op0->getType()->getUnsignedVersion(), &CI);
|
|
// Insert the new shift, which is now unsigned.
|
|
N1 = InsertNewInstBefore(new ShiftInst(Instruction::Shr, N1,
|
|
Op1, Src->getName()), CI);
|
|
return new CastInst(N1, CI.getType());
|
|
}
|
|
}
|
|
break;
|
|
|
|
case Instruction::SetNE:
|
|
if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
|
|
if (Op1C->getRawValue() == 0) {
|
|
// If the input only has the low bit set, simplify directly.
|
|
Constant *Not1 =
|
|
ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
|
|
// cast (X != 0) to int --> X if X&~1 == 0
|
|
if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
|
|
if (CI.getType() == Op0->getType())
|
|
return ReplaceInstUsesWith(CI, Op0);
|
|
else
|
|
return new CastInst(Op0, CI.getType());
|
|
}
|
|
|
|
// If the input is an and with a single bit, shift then simplify.
|
|
ConstantInt *AndRHS;
|
|
if (match(Op0, m_And(m_Value(), m_ConstantInt(AndRHS))))
|
|
if (AndRHS->getRawValue() &&
|
|
(AndRHS->getRawValue() & (AndRHS->getRawValue()-1)) == 0) {
|
|
unsigned ShiftAmt = Log2_64(AndRHS->getRawValue());
|
|
// Perform an unsigned shr by shiftamt. Convert input to
|
|
// unsigned if it is signed.
|
|
Value *In = Op0;
|
|
if (In->getType()->isSigned())
|
|
In = InsertNewInstBefore(new CastInst(In,
|
|
In->getType()->getUnsignedVersion(), In->getName()),CI);
|
|
// Insert the shift to put the result in the low bit.
|
|
In = InsertNewInstBefore(new ShiftInst(Instruction::Shr, In,
|
|
ConstantInt::get(Type::UByteTy, ShiftAmt),
|
|
In->getName()+".lobit"), CI);
|
|
if (CI.getType() == In->getType())
|
|
return ReplaceInstUsesWith(CI, In);
|
|
else
|
|
return new CastInst(In, CI.getType());
|
|
}
|
|
}
|
|
}
|
|
break;
|
|
case Instruction::SetEQ:
|
|
// We if we are just checking for a seteq of a single bit and casting it
|
|
// to an integer. If so, shift the bit to the appropriate place then
|
|
// cast to integer to avoid the comparison.
|
|
if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
|
|
// Is Op1C a power of two or zero?
|
|
if ((Op1C->getRawValue() & Op1C->getRawValue()-1) == 0) {
|
|
// cast (X == 1) to int -> X iff X has only the low bit set.
|
|
if (Op1C->getRawValue() == 1) {
|
|
Constant *Not1 =
|
|
ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
|
|
if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
|
|
if (CI.getType() == Op0->getType())
|
|
return ReplaceInstUsesWith(CI, Op0);
|
|
else
|
|
return new CastInst(Op0, CI.getType());
|
|
}
|
|
}
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
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::Shr:
|
|
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:
|
|
return Constant::getNullValue(I->getType());
|
|
case Instruction::Shl:
|
|
case Instruction::Shr:
|
|
return Constant::getNullValue(Type::UByteTy);
|
|
case Instruction::And:
|
|
return ConstantInt::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->getOpcode() == Instruction::Cast) {
|
|
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 = new SelectInst(SI.getCondition(), TI->getOperand(0),
|
|
FI->getOperand(0), SI.getName()+".v");
|
|
InsertNewInstBefore(NewSI, SI);
|
|
return new CastInst(NewSI, TI->getType());
|
|
}
|
|
|
|
// Only handle binary operators here.
|
|
if (!isa<ShiftInst>(TI) && !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 = new SelectInst(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);
|
|
} else {
|
|
if (MatchIsOpZero)
|
|
return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), MatchOp, NewSI);
|
|
else
|
|
return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), NewSI, MatchOp);
|
|
}
|
|
}
|
|
|
|
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 (ConstantBool *C = dyn_cast<ConstantBool>(CondVal))
|
|
if (C == ConstantBool::True)
|
|
return ReplaceInstUsesWith(SI, TrueVal);
|
|
else {
|
|
assert(C == ConstantBool::False);
|
|
return ReplaceInstUsesWith(SI, 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::BoolTy)
|
|
if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) {
|
|
if (C == ConstantBool::True) {
|
|
// 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 (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) {
|
|
if (C == ConstantBool::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);
|
|
}
|
|
}
|
|
|
|
// Selecting between two integer constants?
|
|
if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
|
|
if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
|
|
// select C, 1, 0 -> cast C to int
|
|
if (FalseValC->isNullValue() && TrueValC->getRawValue() == 1) {
|
|
return new CastInst(CondVal, SI.getType());
|
|
} else if (TrueValC->isNullValue() && FalseValC->getRawValue() == 1) {
|
|
// select C, 0, 1 -> cast !C to int
|
|
Value *NotCond =
|
|
InsertNewInstBefore(BinaryOperator::createNot(CondVal,
|
|
"not."+CondVal->getName()), SI);
|
|
return new CastInst(NotCond, SI.getType());
|
|
}
|
|
|
|
// If one of the constants is zero (we know they can't both be) and we
|
|
// have a setcc 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->isNullValue() || FalseValC->isNullValue())
|
|
if (Instruction *IC = dyn_cast<Instruction>(SI.getCondition()))
|
|
if ((IC->getOpcode() == Instruction::SetEQ ||
|
|
IC->getOpcode() == Instruction::SetNE) &&
|
|
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 setne or seteq and whether the true or
|
|
// false val is the zero.
|
|
bool ShouldNotVal = !TrueValC->isNullValue();
|
|
ShouldNotVal ^= IC->getOpcode() == Instruction::SetNE;
|
|
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 (SetCondInst *SCI = dyn_cast<SetCondInst>(CondVal)) {
|
|
if (SCI->getOperand(0) == TrueVal && SCI->getOperand(1) == FalseVal) {
|
|
// Transform (X == Y) ? X : Y -> Y
|
|
if (SCI->getOpcode() == Instruction::SetEQ)
|
|
return ReplaceInstUsesWith(SI, FalseVal);
|
|
// Transform (X != Y) ? X : Y -> X
|
|
if (SCI->getOpcode() == Instruction::SetNE)
|
|
return ReplaceInstUsesWith(SI, TrueVal);
|
|
// NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
|
|
|
|
} else if (SCI->getOperand(0) == FalseVal && SCI->getOperand(1) == TrueVal){
|
|
// Transform (X == Y) ? Y : X -> X
|
|
if (SCI->getOpcode() == Instruction::SetEQ)
|
|
return ReplaceInstUsesWith(SI, FalseVal);
|
|
// Transform (X != Y) ? Y : X -> Y
|
|
if (SCI->getOpcode() == Instruction::SetNE)
|
|
return ReplaceInstUsesWith(SI, TrueVal);
|
|
// NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc.
|
|
}
|
|
}
|
|
|
|
if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
|
|
if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
|
|
if (TI->hasOneUse() && FI->hasOneUse()) {
|
|
bool isInverse = false;
|
|
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:
|
|
// select C, (add X, Y), (sub X, ?)
|
|
// We can do the transform profitably if either 'Y' = '?' or '?' is
|
|
// a constant.
|
|
if (SubOp->getOperand(1) == AddOp ||
|
|
isa<Constant>(SubOp->getOperand(1))) {
|
|
Value *NegVal;
|
|
if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
|
|
NegVal = ConstantExpr::getNeg(C);
|
|
} else {
|
|
NegVal = InsertNewInstBefore(
|
|
BinaryOperator::createNeg(SubOp->getOperand(1)), SI);
|
|
}
|
|
|
|
Value *NewTrueOp = OtherAddOp;
|
|
Value *NewFalseOp = NegVal;
|
|
if (AddOp != TI)
|
|
std::swap(NewTrueOp, NewFalseOp);
|
|
Instruction *NewSel =
|
|
new SelectInst(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);
|
|
std::string Name = TVI->getName(); TVI->setName("");
|
|
Instruction *NewSel =
|
|
new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C,
|
|
Name);
|
|
InsertNewInstBefore(NewSel, SI);
|
|
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
|
|
return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel);
|
|
else if (ShiftInst *SI = dyn_cast<ShiftInst>(TVI))
|
|
return new ShiftInst(SI->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);
|
|
std::string Name = FVI->getName(); FVI->setName("");
|
|
Instruction *NewSel =
|
|
new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold),
|
|
Name);
|
|
InsertNewInstBefore(NewSel, SI);
|
|
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
|
|
return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel);
|
|
else if (ShiftInst *SI = dyn_cast<ShiftInst>(FVI))
|
|
return new ShiftInst(SI->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;
|
|
}
|
|
|
|
|
|
// CallInst simplification
|
|
//
|
|
Instruction *InstCombiner::visitCallInst(CallInst &CI) {
|
|
// Intrinsics cannot occur in an invoke, so handle them here instead of in
|
|
// visitCallSite.
|
|
if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(&CI)) {
|
|
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);
|
|
|
|
// FIXME: Increase alignment here.
|
|
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
|
|
if (CI->getRawValue() == 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();
|
|
Function *MemCpy = M->getOrInsertFunction("llvm.memcpy",
|
|
CI.getCalledFunction()->getFunctionType());
|
|
CI.setOperand(0, MemCpy);
|
|
Changed = true;
|
|
}
|
|
|
|
if (Changed) return &CI;
|
|
} else if (DbgStopPointInst *SPI = dyn_cast<DbgStopPointInst>(&CI)) {
|
|
// If this stoppoint is at the same source location as the previous
|
|
// stoppoint in the chain, it is not needed.
|
|
if (DbgStopPointInst *PrevSPI =
|
|
dyn_cast<DbgStopPointInst>(SPI->getChain()))
|
|
if (SPI->getLineNo() == PrevSPI->getLineNo() &&
|
|
SPI->getColNo() == PrevSPI->getColNo()) {
|
|
SPI->replaceAllUsesWith(PrevSPI);
|
|
return EraseInstFromFunction(CI);
|
|
}
|
|
}
|
|
|
|
return visitCallSite(&CI);
|
|
}
|
|
|
|
// InvokeInst simplification
|
|
//
|
|
Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
|
|
return visitCallSite(&II);
|
|
}
|
|
|
|
// 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(ConstantBool::True,
|
|
UndefValue::get(PointerType::get(Type::BoolTy)), 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(ConstantBool::True,
|
|
UndefValue::get(PointerType::get(Type::BoolTy)),
|
|
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.
|
|
new BranchInst(II->getNormalDest(), II->getUnwindDest(),
|
|
ConstantBool::True, II);
|
|
}
|
|
return EraseInstFromFunction(*CS.getInstruction());
|
|
}
|
|
|
|
const PointerType *PTy = cast<PointerType>(Callee->getType());
|
|
const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
|
|
if (FTy->isVarArg()) {
|
|
// 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)
|
|
if (CastInst *CI = dyn_cast<CastInst>(*I)) {
|
|
// If this cast does not effect the value passed through the varargs
|
|
// area, we can eliminate the use of the cast.
|
|
Value *Op = CI->getOperand(0);
|
|
if (CI->getType()->isLosslesslyConvertibleTo(Op->getType())) {
|
|
*I = Op;
|
|
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::Cast || !isa<Function>(CE->getOperand(0)))
|
|
return false;
|
|
Function *Callee = cast<Function>(CE->getOperand(0));
|
|
Instruction *Caller = CS.getInstruction();
|
|
|
|
// 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();
|
|
|
|
// Check to see if we are changing the return type...
|
|
if (OldRetTy != FT->getReturnType()) {
|
|
if (Callee->isExternal() &&
|
|
!OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()) &&
|
|
!Caller->use_empty())
|
|
return false; // Cannot transform this return 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);
|
|
bool isConvertible = (*AI)->getType()->isLosslesslyConvertibleTo(ParamTy);
|
|
if (Callee->isExternal() && !isConvertible) return false;
|
|
}
|
|
|
|
if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() &&
|
|
Callee->isExternal())
|
|
return false; // Do not delete arguments unless we have a function body...
|
|
|
|
// 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);
|
|
|
|
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 {
|
|
Args.push_back(InsertNewInstBefore(new CastInst(*AI, ParamTy, "tmp"),
|
|
*Caller));
|
|
}
|
|
}
|
|
|
|
// 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()) {
|
|
std::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 *Cast = new CastInst(*AI, PTy, "tmp");
|
|
InsertNewInstBefore(Cast, *Caller);
|
|
Args.push_back(Cast);
|
|
} else {
|
|
Args.push_back(*AI);
|
|
}
|
|
}
|
|
}
|
|
|
|
if (FT->getReturnType() == Type::VoidTy)
|
|
Caller->setName(""); // Void type should not have a name...
|
|
|
|
Instruction *NC;
|
|
if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) {
|
|
NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(),
|
|
Args, Caller->getName(), Caller);
|
|
cast<InvokeInst>(II)->setCallingConv(II->getCallingConv());
|
|
} else {
|
|
NC = new CallInst(Callee, Args, Caller->getName(), Caller);
|
|
if (cast<CallInst>(Caller)->isTailCall())
|
|
cast<CallInst>(NC)->setTailCall();
|
|
cast<CallInst>(NC)->setCallingConv(cast<CallInst>(Caller)->getCallingConv());
|
|
}
|
|
|
|
// Insert a cast of the return type as necessary...
|
|
Value *NV = NC;
|
|
if (Caller->getType() != NV->getType() && !Caller->use_empty()) {
|
|
if (NV->getType() != Type::VoidTy) {
|
|
NV = NC = new CastInst(NC, Caller->getType(), "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()->begin();
|
|
while (isa<PHINode>(I)) ++I;
|
|
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->getParent()->getInstList().erase(Caller);
|
|
removeFromWorkList(Caller);
|
|
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;
|
|
if (isa<CastInst>(FirstInst)) {
|
|
CastSrcTy = FirstInst->getOperand(0)->getType();
|
|
} else if (isa<BinaryOperator>(FirstInst) || isa<ShiftInst>(FirstInst)) {
|
|
// Can fold binop or shift if the RHS is a constant.
|
|
ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1));
|
|
if (ConstantOp == 0) return 0;
|
|
} 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->getOpcode() != FirstInst->getOpcode())
|
|
return 0;
|
|
if (CastSrcTy) {
|
|
if (I->getOperand(0)->getType() != CastSrcTy)
|
|
return 0; // Cast operation must match.
|
|
} 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 = new PHINode(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 (isa<CastInst>(FirstInst))
|
|
return new CastInst(PhiVal, PN.getType());
|
|
else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst))
|
|
return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp);
|
|
else
|
|
return new ShiftInst(cast<ShiftInst>(FirstInst)->getOpcode(),
|
|
PhiVal, ConstantOp);
|
|
}
|
|
|
|
/// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle
|
|
/// that is dead.
|
|
static bool DeadPHICycle(PHINode *PN, std::set<PHINode*> &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).second)
|
|
return true;
|
|
|
|
if (PHINode *PU = dyn_cast<PHINode>(PN->use_back()))
|
|
return DeadPHICycle(PU, PotentiallyDeadPHIs);
|
|
|
|
return false;
|
|
}
|
|
|
|
// PHINode simplification
|
|
//
|
|
Instruction *InstCombiner::visitPHINode(PHINode &PN) {
|
|
if (Value *V = PN.hasConstantValue())
|
|
return ReplaceInstUsesWith(PN, V);
|
|
|
|
// If the only user of this instruction is a cast instruction, and all of the
|
|
// incoming values are constants, change this PHI to merge together the casted
|
|
// constants.
|
|
if (PN.hasOneUse())
|
|
if (CastInst *CI = dyn_cast<CastInst>(PN.use_back()))
|
|
if (CI->getType() != PN.getType()) { // noop casts will be folded
|
|
bool AllConstant = true;
|
|
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
|
|
if (!isa<Constant>(PN.getIncomingValue(i))) {
|
|
AllConstant = false;
|
|
break;
|
|
}
|
|
if (AllConstant) {
|
|
// Make a new PHI with all casted values.
|
|
PHINode *New = new PHINode(CI->getType(), PN.getName(), &PN);
|
|
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
|
|
Constant *OldArg = cast<Constant>(PN.getIncomingValue(i));
|
|
New->addIncoming(ConstantExpr::getCast(OldArg, New->getType()),
|
|
PN.getIncomingBlock(i));
|
|
}
|
|
|
|
// Update the cast instruction.
|
|
CI->setOperand(0, New);
|
|
WorkList.push_back(CI); // revisit the cast instruction to fold.
|
|
WorkList.push_back(New); // Make sure to revisit the new Phi
|
|
return &PN; // PN is now dead!
|
|
}
|
|
}
|
|
|
|
// If all PHI operands are the same operation, pull them through the PHI,
|
|
// reducing code size.
|
|
if (isa<Instruction>(PN.getIncomingValue(0)) &&
|
|
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())
|
|
if (PHINode *PU = dyn_cast<PHINode>(PN.use_back())) {
|
|
std::set<PHINode*> PotentiallyDeadPHIs;
|
|
PotentiallyDeadPHIs.insert(&PN);
|
|
if (DeadPHICycle(PU, PotentiallyDeadPHIs))
|
|
return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy,
|
|
Instruction *InsertPoint,
|
|
InstCombiner *IC) {
|
|
unsigned PS = IC->getTargetData().getPointerSize();
|
|
const Type *VTy = V->getType();
|
|
if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS)
|
|
// We must insert a cast to ensure we sign-extend.
|
|
V = IC->InsertNewInstBefore(new CastInst(V, VTy->getSignedVersion(),
|
|
V->getName()), *InsertPoint);
|
|
return IC->InsertNewInstBefore(new CastInst(V, DTy, V->getName()),
|
|
*InsertPoint);
|
|
}
|
|
|
|
|
|
Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
|
|
Value *PtrOp = GEP.getOperand(0);
|
|
// Is it 'getelementptr %P, long 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 (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI)
|
|
if (isa<SequentialType>(*GTI)) {
|
|
if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
|
|
Value *Src = CI->getOperand(0);
|
|
const Type *SrcTy = Src->getType();
|
|
const Type *DestTy = CI->getType();
|
|
if (Src->getType()->isInteger()) {
|
|
if (SrcTy->getPrimitiveSizeInBits() ==
|
|
DestTy->getPrimitiveSizeInBits()) {
|
|
// We can always eliminate a cast from ulong or long to the other.
|
|
// We can always eliminate a cast from uint to int or the other on
|
|
// 32-bit pointer platforms.
|
|
if (DestTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()){
|
|
MadeChange = true;
|
|
GEP.setOperand(i, Src);
|
|
}
|
|
} else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
|
|
SrcTy->getPrimitiveSize() == 4) {
|
|
// We can always eliminate a cast from int to [u]long. We can
|
|
// eliminate a cast from uint to [u]long iff the target is a 32-bit
|
|
// pointer target.
|
|
if (SrcTy->isSigned() ||
|
|
SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) {
|
|
MadeChange = true;
|
|
GEP.setOperand(i, Src);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
// If we are using a wider index than needed for this platform, shrink 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 = GEP.getOperand(i);
|
|
if (Op->getType()->getPrimitiveSize() > TD->getPointerSize())
|
|
if (Constant *C = dyn_cast<Constant>(Op)) {
|
|
GEP.setOperand(i, ConstantExpr::getCast(C,
|
|
TD->getIntPtrType()->getSignedVersion()));
|
|
MadeChange = true;
|
|
} else {
|
|
Op = InsertNewInstBefore(new CastInst(Op, TD->getIntPtrType(),
|
|
Op->getName()), GEP);
|
|
GEP.setOperand(i, Op);
|
|
MadeChange = true;
|
|
}
|
|
|
|
// If this is a constant idx, make sure to canonicalize it to be a signed
|
|
// operand, otherwise CSE and other optimizations are pessimized.
|
|
if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op)) {
|
|
GEP.setOperand(i, ConstantExpr::getCast(CUI,
|
|
CUI->getType()->getSignedVersion()));
|
|
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.
|
|
//
|
|
std::vector<Value*> SrcGEPOperands;
|
|
if (User *Src = dyn_castGetElementPtr(PtrOp))
|
|
SrcGEPOperands.assign(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.
|
|
|
|
std::vector<Value *> 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::getCast(SO1C, GO1->getType());
|
|
} else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
|
|
GO1 = ConstantExpr::getCast(GO1C, SO1->getType());
|
|
} else {
|
|
unsigned PS = TD->getPointerSize();
|
|
if (SO1->getType()->getPrimitiveSize() == PS) {
|
|
// Convert GO1 to SO1's type.
|
|
GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this);
|
|
|
|
} else if (GO1->getType()->getPrimitiveSize() == PS) {
|
|
// Convert SO1 to GO1's type.
|
|
SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this);
|
|
} else {
|
|
const Type *PT = TD->getIntPtrType();
|
|
SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this);
|
|
GO1 = InsertSignExtendToPtrTy(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 new GetElementPtrInst(SrcGEPOperands[0], Indices, 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...
|
|
std::vector<Constant*> 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);
|
|
|
|
// Replace all uses of the GEP with the new constexpr...
|
|
return ReplaceInstUsesWith(GEP, CE);
|
|
}
|
|
} else if (Value *X = isCast(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 (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ...
|
|
// into : GEP [10 x ubyte]* X, long 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 ubyte* cast ([2 x int]* %str to uint*), uint %V
|
|
// into: %t1 = getelementptr [2 x int*]* %str, int 0, uint %V; cast
|
|
const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType();
|
|
const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
|
|
if (isa<ArrayType>(SrcElTy) &&
|
|
TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
|
|
TD->getTypeSize(ResElTy)) {
|
|
Value *V = InsertNewInstBefore(
|
|
new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
|
|
GEP.getOperand(1), GEP.getName()), GEP);
|
|
return new CastInst(V, GEP.getType());
|
|
}
|
|
|
|
// Transform things like:
|
|
// getelementptr sbyte* cast ([100 x double]* X to sbyte*), int %tmp
|
|
// (where tmp = 8*tmp2) into:
|
|
// getelementptr [100 x double]* %arr, int 0, int %tmp.2
|
|
|
|
if (isa<ArrayType>(SrcElTy) &&
|
|
(ResElTy == Type::SByteTy || ResElTy == Type::UByteTy)) {
|
|
uint64_t ArrayEltSize =
|
|
TD->getTypeSize(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))) {
|
|
unsigned ShAmt =cast<ConstantUInt>(Inst->getOperand(1))->getValue();
|
|
if (Inst->getType()->isSigned())
|
|
Scale = ConstantSInt::get(Inst->getType(), 1ULL << ShAmt);
|
|
else
|
|
Scale = ConstantUInt::get(Inst->getType(), 1ULL << ShAmt);
|
|
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.
|
|
if (Scale && Scale->getRawValue() % ArrayEltSize == 0) {
|
|
if (ConstantSInt *C = dyn_cast<ConstantSInt>(Scale))
|
|
Scale = ConstantSInt::get(C->getType(),
|
|
(int64_t)C->getRawValue() /
|
|
(int64_t)ArrayEltSize);
|
|
else
|
|
Scale = ConstantUInt::get(Scale->getType(),
|
|
Scale->getRawValue() / ArrayEltSize);
|
|
if (Scale->getRawValue() != 1) {
|
|
Constant *C = ConstantExpr::getCast(Scale, NewIdx->getType());
|
|
Instruction *Sc = BinaryOperator::createMul(NewIdx, C, "idxscale");
|
|
NewIdx = InsertNewInstBefore(Sc, GEP);
|
|
}
|
|
|
|
// Insert the new GEP instruction.
|
|
Instruction *Idx =
|
|
new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy),
|
|
NewIdx, GEP.getName());
|
|
Idx = InsertNewInstBefore(Idx, GEP);
|
|
return new CastInst(Idx, 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 ConstantUInt *C = dyn_cast<ConstantUInt>(AI.getArraySize())) {
|
|
const Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getValue());
|
|
AllocationInst *New = 0;
|
|
|
|
// Create and insert the replacement instruction...
|
|
if (isa<MallocInst>(AI))
|
|
New = new MallocInst(NewTy, 0, AI.getName());
|
|
else {
|
|
assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
|
|
New = new AllocaInst(NewTy, 0, 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::IntTy);
|
|
Value *V = new GetElementPtrInst(New, NullIdx, NullIdx,
|
|
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 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 (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() &&
|
|
TD->getTypeSize(AI.getAllocatedType()) == 0)
|
|
return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitFreeInst(FreeInst &FI) {
|
|
Value *Op = FI.getOperand(0);
|
|
|
|
// Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X
|
|
if (CastInst *CI = dyn_cast<CastInst>(Op))
|
|
if (isa<PointerType>(CI->getOperand(0)->getType())) {
|
|
FI.setOperand(0, CI->getOperand(0));
|
|
return &FI;
|
|
}
|
|
|
|
// free undef -> unreachable.
|
|
if (isa<UndefValue>(Op)) {
|
|
// Insert a new store to null because we cannot modify the CFG here.
|
|
new StoreInst(ConstantBool::True,
|
|
UndefValue::get(PointerType::get(Type::BoolTy)), &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);
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
/// GetGEPGlobalInitializer - Given a constant, and a getelementptr
|
|
/// constantexpr, return the constant value being addressed by the constant
|
|
/// expression, or null if something is funny.
|
|
///
|
|
static Constant *GetGEPGlobalInitializer(Constant *C, ConstantExpr *CE) {
|
|
if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType()))
|
|
return 0; // Do not allow stepping over the value!
|
|
|
|
// Loop over all of the operands, tracking down which value we are
|
|
// addressing...
|
|
gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
|
|
for (++I; I != E; ++I)
|
|
if (const StructType *STy = dyn_cast<StructType>(*I)) {
|
|
ConstantUInt *CU = cast<ConstantUInt>(I.getOperand());
|
|
assert(CU->getValue() < STy->getNumElements() &&
|
|
"Struct index out of range!");
|
|
unsigned El = (unsigned)CU->getValue();
|
|
if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
|
|
C = CS->getOperand(El);
|
|
} else if (isa<ConstantAggregateZero>(C)) {
|
|
C = Constant::getNullValue(STy->getElementType(El));
|
|
} else if (isa<UndefValue>(C)) {
|
|
C = UndefValue::get(STy->getElementType(El));
|
|
} else {
|
|
return 0;
|
|
}
|
|
} else if (ConstantInt *CI = dyn_cast<ConstantInt>(I.getOperand())) {
|
|
const ArrayType *ATy = cast<ArrayType>(*I);
|
|
if ((uint64_t)CI->getRawValue() >= ATy->getNumElements()) return 0;
|
|
if (ConstantArray *CA = dyn_cast<ConstantArray>(C))
|
|
C = CA->getOperand((unsigned)CI->getRawValue());
|
|
else if (isa<ConstantAggregateZero>(C))
|
|
C = Constant::getNullValue(ATy->getElementType());
|
|
else if (isa<UndefValue>(C))
|
|
C = UndefValue::get(ATy->getElementType());
|
|
else
|
|
return 0;
|
|
} else {
|
|
return 0;
|
|
}
|
|
return C;
|
|
}
|
|
|
|
/// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
|
|
static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) {
|
|
User *CI = cast<User>(LI.getOperand(0));
|
|
Value *CastOp = CI->getOperand(0);
|
|
|
|
const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
|
|
if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
|
|
const Type *SrcPTy = SrcTy->getElementType();
|
|
|
|
if (DestPTy->isInteger() || isa<PointerType>(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) {
|
|
std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
|
|
CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
|
|
SrcTy = cast<PointerType>(CastOp->getType());
|
|
SrcPTy = SrcTy->getElementType();
|
|
}
|
|
|
|
if ((SrcPTy->isInteger() || isa<PointerType>(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().getTypeSize(SrcPTy) ==
|
|
IC.getTargetData().getTypeSize(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 CastInst(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 or global variable, it is always safe to load from.
|
|
if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true;
|
|
|
|
// 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 (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);
|
|
|
|
// load (cast X) --> cast (load X) iff safe
|
|
if (CastInst *CI = dyn_cast<CastInst>(Op))
|
|
if (Instruction *Res = InstCombineLoadCast(*this, LI))
|
|
return Res;
|
|
|
|
// None of the following transforms are legal for volatile loads.
|
|
if (LI.isVolatile()) return 0;
|
|
|
|
if (&LI.getParent()->front() != &LI) {
|
|
BasicBlock::iterator BBI = &LI; --BBI;
|
|
// If the instruction immediately before this is a store to the same
|
|
// address, do a simple form of store->load forwarding.
|
|
if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
|
|
if (SI->getOperand(1) == LI.getOperand(0))
|
|
return ReplaceInstUsesWith(LI, SI->getOperand(0));
|
|
if (LoadInst *LIB = dyn_cast<LoadInst>(BBI))
|
|
if (LIB->getOperand(0) == LI.getOperand(0))
|
|
return ReplaceInstUsesWith(LI, LIB);
|
|
}
|
|
|
|
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op))
|
|
if (isa<ConstantPointerNull>(GEPI->getOperand(0)) ||
|
|
isa<UndefValue>(GEPI->getOperand(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
|
|
if ((C->isNullValue() || isa<UndefValue>(C))) {
|
|
// 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->isExternal())
|
|
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->isExternal())
|
|
if (Constant *V = GetGEPGlobalInitializer(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->getOpcode() == Instruction::Cast) {
|
|
if (Instruction *Res = InstCombineLoadCast(*this, LI))
|
|
return Res;
|
|
}
|
|
}
|
|
|
|
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 new SelectInst(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;
|
|
}
|
|
|
|
} else if (PHINode *PN = dyn_cast<PHINode>(Op)) {
|
|
// load (phi (&V1, &V2, &V3)) --> phi(load &V1, load &V2, load &V3)
|
|
bool Safe = PN->getParent() == LI.getParent();
|
|
|
|
// Scan all of the instructions between the PHI and the load to make
|
|
// sure there are no instructions that might possibly alter the value
|
|
// loaded from the PHI.
|
|
if (Safe) {
|
|
BasicBlock::iterator I = &LI;
|
|
for (--I; !isa<PHINode>(I); --I)
|
|
if (isa<StoreInst>(I) || isa<CallInst>(I)) {
|
|
Safe = false;
|
|
break;
|
|
}
|
|
}
|
|
|
|
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e && Safe; ++i)
|
|
if (!isSafeToLoadUnconditionally(PN->getIncomingValue(i),
|
|
PN->getIncomingBlock(i)->getTerminator()))
|
|
Safe = false;
|
|
|
|
if (Safe) {
|
|
// Create the PHI.
|
|
PHINode *NewPN = new PHINode(LI.getType(), PN->getName());
|
|
InsertNewInstBefore(NewPN, *PN);
|
|
std::map<BasicBlock*,Value*> LoadMap; // Don't insert duplicate loads
|
|
|
|
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
|
|
BasicBlock *BB = PN->getIncomingBlock(i);
|
|
Value *&TheLoad = LoadMap[BB];
|
|
if (TheLoad == 0) {
|
|
Value *InVal = PN->getIncomingValue(i);
|
|
TheLoad = InsertNewInstBefore(new LoadInst(InVal,
|
|
InVal->getName()+".val"),
|
|
*BB->getTerminator());
|
|
}
|
|
NewPN->addIncoming(TheLoad, BB);
|
|
}
|
|
return ReplaceInstUsesWith(LI, NewPN);
|
|
}
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/// InstCombineStoreToCast - Fold 'store V, (cast P)' -> store (cast V), P'
|
|
/// when possible.
|
|
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();
|
|
if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) {
|
|
const Type *SrcPTy = SrcTy->getElementType();
|
|
|
|
if (DestPTy->isInteger() || isa<PointerType>(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) {
|
|
std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy));
|
|
CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs);
|
|
SrcTy = cast<PointerType>(CastOp->getType());
|
|
SrcPTy = SrcTy->getElementType();
|
|
}
|
|
|
|
if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
|
|
IC.getTargetData().getTypeSize(SrcPTy) ==
|
|
IC.getTargetData().getTypeSize(DestPTy)) {
|
|
|
|
// 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;
|
|
if (Constant *C = dyn_cast<Constant>(SI.getOperand(0)))
|
|
NewCast = ConstantExpr::getCast(C, SrcPTy);
|
|
else
|
|
NewCast = IC.InsertNewInstBefore(new CastInst(SI.getOperand(0),
|
|
SrcPTy,
|
|
SI.getOperand(0)->getName()+".c"), SI);
|
|
|
|
return new StoreInst(NewCast, CastOp);
|
|
}
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
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)
|
|
removeFromWorkList(&SI);
|
|
SI.eraseFromParent();
|
|
++NumCombined;
|
|
return 0;
|
|
}
|
|
|
|
if (SI.isVolatile()) return 0; // Don't hack volatile loads.
|
|
|
|
// 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))
|
|
WorkList.push_back(U); // Dropped a use.
|
|
++NumCombined;
|
|
}
|
|
return 0; // Do not modify these!
|
|
}
|
|
|
|
// store undef, Ptr -> noop
|
|
if (isa<UndefValue>(Val)) {
|
|
removeFromWorkList(&SI);
|
|
SI.eraseFromParent();
|
|
++NumCombined;
|
|
return 0;
|
|
}
|
|
|
|
// If the pointer destination is a cast, see if we can fold the cast into the
|
|
// source instead.
|
|
if (CastInst *CI = dyn_cast<CastInst>(Ptr))
|
|
if (Instruction *Res = InstCombineStoreToCast(*this, SI))
|
|
return Res;
|
|
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr))
|
|
if (CE->getOpcode() == Instruction::Cast)
|
|
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.
|
|
BasicBlock::iterator BBI = &SI; ++BBI;
|
|
if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
|
|
if (BI->isUnconditional()) {
|
|
// 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 *Dest = BI->getSuccessor(0);
|
|
|
|
pred_iterator PI = pred_begin(Dest);
|
|
BasicBlock *Other = 0;
|
|
if (*PI != BI->getParent())
|
|
Other = *PI;
|
|
++PI;
|
|
if (PI != pred_end(Dest)) {
|
|
if (*PI != BI->getParent())
|
|
if (Other)
|
|
Other = 0;
|
|
else
|
|
Other = *PI;
|
|
if (++PI != pred_end(Dest))
|
|
Other = 0;
|
|
}
|
|
if (Other) { // If only one other pred...
|
|
BBI = Other->getTerminator();
|
|
// Make sure this other block ends in an unconditional branch and that
|
|
// there is an instruction before the branch.
|
|
if (isa<BranchInst>(BBI) && cast<BranchInst>(BBI)->isUnconditional() &&
|
|
BBI != Other->begin()) {
|
|
--BBI;
|
|
StoreInst *OtherStore = dyn_cast<StoreInst>(BBI);
|
|
|
|
// If this instruction is a store to the same location.
|
|
if (OtherStore && OtherStore->getOperand(1) == SI.getOperand(1)) {
|
|
// Okay, we know we can perform this transformation. Insert a PHI
|
|
// node now if we need it.
|
|
Value *MergedVal = OtherStore->getOperand(0);
|
|
if (MergedVal != SI.getOperand(0)) {
|
|
PHINode *PN = new PHINode(MergedVal->getType(), "storemerge");
|
|
PN->reserveOperandSpace(2);
|
|
PN->addIncoming(SI.getOperand(0), SI.getParent());
|
|
PN->addIncoming(OtherStore->getOperand(0), Other);
|
|
MergedVal = InsertNewInstBefore(PN, Dest->front());
|
|
}
|
|
|
|
// Advance to a place where it is safe to insert the new store and
|
|
// insert it.
|
|
BBI = Dest->begin();
|
|
while (isa<PHINode>(BBI)) ++BBI;
|
|
InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1),
|
|
OtherStore->isVolatile()), *BBI);
|
|
|
|
// Nuke the old stores.
|
|
removeFromWorkList(&SI);
|
|
removeFromWorkList(OtherStore);
|
|
SI.eraseFromParent();
|
|
OtherStore->eraseFromParent();
|
|
++NumCombined;
|
|
return 0;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
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 setne -> seteq
|
|
Instruction::BinaryOps Op; Value *Y;
|
|
if (match(&BI, m_Br(m_SetCond(Op, m_Value(X), m_Value(Y)),
|
|
TrueDest, FalseDest)))
|
|
if ((Op == Instruction::SetNE || Op == Instruction::SetLE ||
|
|
Op == Instruction::SetGE) && BI.getCondition()->hasOneUse()) {
|
|
SetCondInst *I = cast<SetCondInst>(BI.getCondition());
|
|
std::string Name = I->getName(); I->setName("");
|
|
Instruction::BinaryOps NewOpcode = SetCondInst::getInverseCondition(Op);
|
|
Value *NewSCC = BinaryOperator::create(NewOpcode, X, Y, Name, I);
|
|
// Swap Destinations and condition...
|
|
BI.setCondition(NewSCC);
|
|
BI.setSuccessor(0, FalseDest);
|
|
BI.setSuccessor(1, TrueDest);
|
|
removeFromWorkList(I);
|
|
I->getParent()->getInstList().erase(I);
|
|
WorkList.push_back(cast<Instruction>(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));
|
|
WorkList.push_back(I);
|
|
return &SI;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
|
|
void InstCombiner::removeFromWorkList(Instruction *I) {
|
|
WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
|
|
WorkList.end());
|
|
}
|
|
|
|
|
|
/// 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 instructions.
|
|
if (isa<PHINode>(I) || isa<InvokeInst>(I) || isa<CallInst>(I)) return false;
|
|
|
|
// Do not sink alloca instructions out of the entry block.
|
|
if (isa<AllocaInst>(I) && I->getParent() == &DestBlock->getParent()->front())
|
|
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 (LoadInst *LI = dyn_cast<LoadInst>(I)) {
|
|
if (LI->isVolatile()) return false; // Don't sink volatile loads.
|
|
|
|
for (BasicBlock::iterator Scan = LI, E = LI->getParent()->end();
|
|
Scan != E; ++Scan)
|
|
if (Scan->mayWriteToMemory())
|
|
return false;
|
|
}
|
|
|
|
BasicBlock::iterator InsertPos = DestBlock->begin();
|
|
while (isa<PHINode>(InsertPos)) ++InsertPos;
|
|
|
|
I->moveBefore(InsertPos);
|
|
++NumSunkInst;
|
|
return true;
|
|
}
|
|
|
|
bool InstCombiner::runOnFunction(Function &F) {
|
|
bool Changed = false;
|
|
TD = &getAnalysis<TargetData>();
|
|
|
|
{
|
|
// Populate the worklist with the reachable instructions.
|
|
std::set<BasicBlock*> Visited;
|
|
for (df_ext_iterator<BasicBlock*> BB = df_ext_begin(&F.front(), Visited),
|
|
E = df_ext_end(&F.front(), Visited); BB != E; ++BB)
|
|
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
|
|
WorkList.push_back(I);
|
|
|
|
// 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;
|
|
|
|
DEBUG(std::cerr << "IC: DCE: " << *I);
|
|
++NumDeadInst;
|
|
|
|
if (!I->use_empty())
|
|
I->replaceAllUsesWith(UndefValue::get(I->getType()));
|
|
I->eraseFromParent();
|
|
}
|
|
}
|
|
}
|
|
|
|
while (!WorkList.empty()) {
|
|
Instruction *I = WorkList.back(); // Get an instruction from the worklist
|
|
WorkList.pop_back();
|
|
|
|
// Check to see if we can DCE or ConstantPropagate the instruction...
|
|
// Check to see if we can DIE the instruction...
|
|
if (isInstructionTriviallyDead(I)) {
|
|
// Add operands to the worklist...
|
|
if (I->getNumOperands() < 4)
|
|
AddUsesToWorkList(*I);
|
|
++NumDeadInst;
|
|
|
|
DEBUG(std::cerr << "IC: DCE: " << *I);
|
|
|
|
I->eraseFromParent();
|
|
removeFromWorkList(I);
|
|
continue;
|
|
}
|
|
|
|
// Instruction isn't dead, see if we can constant propagate it...
|
|
if (Constant *C = ConstantFoldInstruction(I)) {
|
|
Value* Ptr = I->getOperand(0);
|
|
if (isa<GetElementPtrInst>(I) &&
|
|
cast<Constant>(Ptr)->isNullValue() &&
|
|
!isa<ConstantPointerNull>(C) &&
|
|
cast<PointerType>(Ptr->getType())->getElementType()->isSized()) {
|
|
// If this is a constant expr gep that is effectively computing an
|
|
// "offsetof", fold it into 'cast int X to T*' instead of 'gep 0, 0, 12'
|
|
bool isFoldableGEP = true;
|
|
for (unsigned i = 1, e = I->getNumOperands(); i != e; ++i)
|
|
if (!isa<ConstantInt>(I->getOperand(i)))
|
|
isFoldableGEP = false;
|
|
if (isFoldableGEP) {
|
|
uint64_t Offset = TD->getIndexedOffset(Ptr->getType(),
|
|
std::vector<Value*>(I->op_begin()+1, I->op_end()));
|
|
C = ConstantUInt::get(Type::ULongTy, Offset);
|
|
C = ConstantExpr::getCast(C, TD->getIntPtrType());
|
|
C = ConstantExpr::getCast(C, I->getType());
|
|
}
|
|
}
|
|
|
|
DEBUG(std::cerr << "IC: ConstFold to: " << *C << " from: " << *I);
|
|
|
|
// Add operands to the worklist...
|
|
AddUsesToWorkList(*I);
|
|
ReplaceInstUsesWith(*I, C);
|
|
|
|
++NumConstProp;
|
|
I->getParent()->getInstList().erase(I);
|
|
removeFromWorkList(I);
|
|
continue;
|
|
}
|
|
|
|
// 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...
|
|
if (Instruction *Result = visit(*I)) {
|
|
++NumCombined;
|
|
// Should we replace the old instruction with a new one?
|
|
if (Result != I) {
|
|
DEBUG(std::cerr << "IC: Old = " << *I
|
|
<< " New = " << *Result);
|
|
|
|
// Everything uses the new instruction now.
|
|
I->replaceAllUsesWith(Result);
|
|
|
|
// Push the new instruction and any users onto the worklist.
|
|
WorkList.push_back(Result);
|
|
AddUsersToWorkList(*Result);
|
|
|
|
// Move the name to the new instruction first...
|
|
std::string OldName = I->getName(); I->setName("");
|
|
Result->setName(OldName);
|
|
|
|
// 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.
|
|
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
|
|
if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
|
|
WorkList.push_back(OpI);
|
|
|
|
// 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 {
|
|
DEBUG(std::cerr << "IC: MOD = " << *I);
|
|
|
|
// 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.
|
|
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
|
|
if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i)))
|
|
WorkList.push_back(OpI);
|
|
|
|
// Instructions may end up in the worklist more than once. Erase all
|
|
// occurrances of this instruction.
|
|
removeFromWorkList(I);
|
|
I->eraseFromParent();
|
|
} else {
|
|
WorkList.push_back(Result);
|
|
AddUsersToWorkList(*Result);
|
|
}
|
|
}
|
|
Changed = true;
|
|
}
|
|
}
|
|
|
|
return Changed;
|
|
}
|
|
|
|
FunctionPass *llvm::createInstructionCombiningPass() {
|
|
return new InstCombiner();
|
|
}
|
|
|