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aa9c1f13a1
(A <setcc1> B) logicalop (A <setcc2> B) -> (A <setcc3> B) or true or false Where setcc[123] is one of the 6 setcc instructions, and logicalop is one of: And, Or, Xor git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7828 91177308-0d34-0410-b5e6-96231b3b80d8
1908 lines
74 KiB
C++
1908 lines
74 KiB
C++
//===- InstructionCombining.cpp - Combine multiple instructions -----------===//
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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 1, %X
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// %Z = add int 1, %Y
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// into:
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// %Z = add int 2, %X
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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 cannonicalizations 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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// N. This list is incomplete
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Scalar.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/Instructions.h"
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#include "llvm/Pass.h"
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#include "llvm/Constants.h"
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#include "llvm/ConstantHandling.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/GlobalVariable.h"
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#include "llvm/Support/InstIterator.h"
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#include "llvm/Support/InstVisitor.h"
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#include "llvm/Support/CallSite.h"
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#include "Support/Statistic.h"
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#include <algorithm>
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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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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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void AddUsesToWorkList(Instruction &I) {
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// The instruction was simplified, add all users of the instruction to
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// the work lists because they might get more simplified now...
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//
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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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// 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.setPreservesCFG();
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}
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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(BinaryOperator &I);
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Instruction *visitShiftInst(ShiftInst &I);
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Instruction *visitCastInst(CastInst &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 *visitLoadInst(LoadInst &LI);
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Instruction *visitBranchInst(BranchInst &BI);
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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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bool transformConstExprCastCall(CallSite CS);
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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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void 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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}
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public:
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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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AddUsesToWorkList(I); // Add all modified instrs to worklist
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I.replaceAllUsesWith(V);
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return &I;
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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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};
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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 -> Constant, 1 -> Other, 2 -> Argument, 2 -> Unary, 3 -> 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 2;
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return 3;
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}
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if (isa<Argument>(V)) return 2;
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return isa<Constant>(V) ? 0 : 1;
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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->use_size() == 1 || isa<Constant>(V);
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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(cast<BinaryOperator>(V));
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// Constants can be considered to be negated values if they can be folded...
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if (Constant *C = dyn_cast<Constant>(V))
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return ConstantExpr::get(Instruction::Sub,
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Constant::getNullValue(V->getType()), 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(cast<BinaryOperator>(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::get(Instruction::Xor,
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ConstantIntegral::getAllOnesValue(C->getType()),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.
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//
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static inline Value *dyn_castFoldableMul(Value *V) {
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if (V->use_size() == 1 && 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 (isa<Constant>(I->getOperand(1)))
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return I->getOperand(0);
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return 0;
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}
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// dyn_castMaskingAnd - If this value is an And instruction masking a value with
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// a constant, return the constant being anded with.
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//
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template<class ValueType>
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static inline Constant *dyn_castMaskingAnd(ValueType *V) {
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if (Instruction *I = dyn_cast<Instruction>(V))
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if (I->getOpcode() == Instruction::And)
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return dyn_cast<Constant>(I->getOperand(1));
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// If this is a constant, it acts just like we were masking with it.
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return dyn_cast<Constant>(V);
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}
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// Log2 - Calculate the log base 2 for the specified value if it is exactly a
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// power of 2.
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static unsigned Log2(uint64_t Val) {
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assert(Val > 1 && "Values 0 and 1 should be handled elsewhere!");
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unsigned Count = 0;
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while (Val != 1) {
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if (Val & 1) return 0; // Multiple bits set?
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Val >>= 1;
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++Count;
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}
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return Count;
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}
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/// AssociativeOpt - Perform an optimization on an associative operator. This
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/// function is designed to check a chain of associative operators for a
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/// potential to apply a certain optimization. Since the optimization may be
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/// applicable if the expression was reassociated, this checks the chain, then
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/// reassociates the expression as necessary to expose the optimization
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/// opportunity. This makes use of a special Functor, which must define
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/// 'shouldApply' and 'apply' methods.
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///
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template<typename Functor>
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Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) {
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unsigned Opcode = Root.getOpcode();
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Value *LHS = Root.getOperand(0);
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// Quick check, see if the immediate LHS matches...
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if (F.shouldApply(LHS))
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return F.apply(Root);
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// Otherwise, if the LHS is not of the same opcode as the root, return.
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Instruction *LHSI = dyn_cast<Instruction>(LHS);
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while (LHSI && LHSI->getOpcode() == Opcode && LHSI->use_size() == 1) {
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// Should we apply this transform to the RHS?
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bool ShouldApply = F.shouldApply(LHSI->getOperand(1));
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// If not to the RHS, check to see if we should apply to the LHS...
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if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) {
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cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS
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ShouldApply = true;
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}
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// If the functor wants to apply the optimization to the RHS of LHSI,
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// reassociate the expression from ((? op A) op B) to (? op (A op B))
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if (ShouldApply) {
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BasicBlock *BB = Root.getParent();
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// All of the instructions have a single use and have no side-effects,
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// because of this, we can pull them all into the current basic block.
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if (LHSI->getParent() != BB) {
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// Move all of the instructions from root to LHSI into the current
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// block.
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Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
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Instruction *LastUse = &Root;
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while (TmpLHSI->getParent() == BB) {
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LastUse = TmpLHSI;
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TmpLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
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}
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// Loop over all of the instructions in other blocks, moving them into
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// the current one.
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Value *TmpLHS = TmpLHSI;
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do {
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TmpLHSI = cast<Instruction>(TmpLHS);
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// Remove from current block...
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TmpLHSI->getParent()->getInstList().remove(TmpLHSI);
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// Insert before the last instruction...
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BB->getInstList().insert(LastUse, TmpLHSI);
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TmpLHS = TmpLHSI->getOperand(0);
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} while (TmpLHSI != LHSI);
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}
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// Now all of the instructions are in the current basic block, go ahead
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// and perform the reassociation.
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Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0));
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// First move the selected RHS to the LHS of the root...
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Root.setOperand(0, LHSI->getOperand(1));
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// Make what used to be the LHS of the root be the user of the root...
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Value *ExtraOperand = TmpLHSI->getOperand(1);
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Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
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TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
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BB->getInstList().remove(&Root); // Remove root from the BB
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BB->getInstList().insert(TmpLHSI, &Root); // Insert root before TmpLHSI
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// Now propagate the ExtraOperand down the chain of instructions until we
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// get to LHSI.
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while (TmpLHSI != LHSI) {
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Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0));
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Value *NextOp = NextLHSI->getOperand(1);
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NextLHSI->setOperand(1, ExtraOperand);
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TmpLHSI = NextLHSI;
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ExtraOperand = NextOp;
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}
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// Now that the instructions are reassociated, have the functor perform
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// the transformation...
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return F.apply(Root);
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}
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LHSI = dyn_cast<Instruction>(LHSI->getOperand(0));
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}
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return 0;
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}
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// AddRHS - Implements: X + X --> X << 1
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struct AddRHS {
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Value *RHS;
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AddRHS(Value *rhs) : RHS(rhs) {}
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bool shouldApply(Value *LHS) const { return LHS == RHS; }
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Instruction *apply(BinaryOperator &Add) const {
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return new ShiftInst(Instruction::Shl, Add.getOperand(0),
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ConstantInt::get(Type::UByteTy, 1));
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}
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};
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// AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2)
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// iff C1&C2 == 0
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struct AddMaskingAnd {
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Constant *C2;
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AddMaskingAnd(Constant *c) : C2(c) {}
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bool shouldApply(Value *LHS) const {
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if (Constant *C1 = dyn_castMaskingAnd(LHS))
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return ConstantExpr::get(Instruction::And, C1, C2)->isNullValue();
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return false;
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}
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Instruction *apply(BinaryOperator &Add) const {
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return BinaryOperator::create(Instruction::Or, Add.getOperand(0),
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Add.getOperand(1));
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}
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};
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Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
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bool Changed = SimplifyCommutative(I);
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Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
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// X + 0 --> X
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if (RHS == Constant::getNullValue(I.getType()))
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return ReplaceInstUsesWith(I, LHS);
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// X + X --> X << 1
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if (I.getType()->isInteger())
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if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
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// -A + B --> B - A
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if (Value *V = dyn_castNegVal(LHS))
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return BinaryOperator::create(Instruction::Sub, RHS, V);
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// A + -B --> A - B
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if (!isa<Constant>(RHS))
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if (Value *V = dyn_castNegVal(RHS))
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return BinaryOperator::create(Instruction::Sub, LHS, V);
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// X*C + X --> X * (C+1)
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if (dyn_castFoldableMul(LHS) == RHS) {
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Constant *CP1 =
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ConstantExpr::get(Instruction::Add,
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cast<Constant>(cast<Instruction>(LHS)->getOperand(1)),
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ConstantInt::get(I.getType(), 1));
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return BinaryOperator::create(Instruction::Mul, RHS, CP1);
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}
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// X + X*C --> X * (C+1)
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if (dyn_castFoldableMul(RHS) == LHS) {
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Constant *CP1 =
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ConstantExpr::get(Instruction::Add,
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cast<Constant>(cast<Instruction>(RHS)->getOperand(1)),
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ConstantInt::get(I.getType(), 1));
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return BinaryOperator::create(Instruction::Mul, LHS, CP1);
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}
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// (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0
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if (Constant *C2 = dyn_castMaskingAnd(RHS))
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if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R;
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return Changed ? &I : 0;
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}
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// isSignBit - Return true if the value represented by the constant only has the
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// highest order bit set.
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static bool isSignBit(ConstantInt *CI) {
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unsigned NumBits = CI->getType()->getPrimitiveSize()*8;
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return (CI->getRawValue() & ~(-1LL << NumBits)) == (1ULL << (NumBits-1));
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}
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|
|
|
static unsigned getTypeSizeInBits(const Type *Ty) {
|
|
return Ty == Type::BoolTy ? 1 : Ty->getPrimitiveSize()*8;
|
|
}
|
|
|
|
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::create(Instruction::Add, Op0, V);
|
|
|
|
// Replace (-1 - A) with (~A)...
|
|
if (ConstantInt *C = dyn_cast<ConstantInt>(Op0))
|
|
if (C->isAllOnesValue())
|
|
return BinaryOperator::createNot(Op1);
|
|
|
|
if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1))
|
|
if (Op1I->use_size() == 1) {
|
|
// Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
|
|
// is not used by anyone else...
|
|
//
|
|
if (Op1I->getOpcode() == Instruction::Sub) {
|
|
// 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::create(Instruction::Add, 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);
|
|
|
|
Instruction *NewNot = BinaryOperator::createNot(OtherOp, "B.not", &I);
|
|
return BinaryOperator::create(Instruction::And, Op0, NewNot);
|
|
}
|
|
|
|
// X - X*C --> X * (1-C)
|
|
if (dyn_castFoldableMul(Op1I) == Op0) {
|
|
Constant *CP1 =
|
|
ConstantExpr::get(Instruction::Sub,
|
|
ConstantInt::get(I.getType(), 1),
|
|
cast<Constant>(cast<Instruction>(Op1)->getOperand(1)));
|
|
assert(CP1 && "Couldn't constant fold 1-C?");
|
|
return BinaryOperator::create(Instruction::Mul, Op0, CP1);
|
|
}
|
|
}
|
|
|
|
// X*C - X --> X * (C-1)
|
|
if (dyn_castFoldableMul(Op0) == Op1) {
|
|
Constant *CP1 =
|
|
ConstantExpr::get(Instruction::Sub,
|
|
cast<Constant>(cast<Instruction>(Op0)->getOperand(1)),
|
|
ConstantInt::get(I.getType(), 1));
|
|
assert(CP1 && "Couldn't constant fold C - 1?");
|
|
return BinaryOperator::create(Instruction::Mul, Op1, CP1);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitMul(BinaryOperator &I) {
|
|
bool Changed = SimplifyCommutative(I);
|
|
Value *Op0 = I.getOperand(0);
|
|
|
|
// 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::create(Instruction::Mul, SI->getOperand(0),
|
|
*CI << *ShOp);
|
|
|
|
const Type *Ty = CI->getType();
|
|
int64_t Val = (int64_t)cast<ConstantInt>(CI)->getRawValue();
|
|
switch (Val) {
|
|
case -1: // X * -1 -> -X
|
|
return BinaryOperator::createNeg(Op0, I.getName());
|
|
case 0:
|
|
return ReplaceInstUsesWith(I, Op1); // Eliminate 'mul double %X, 0'
|
|
case 1:
|
|
return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul int %X, 1'
|
|
}
|
|
|
|
if (uint64_t C = Log2(Val)) // Replace X*(2^C) with X << C
|
|
return new ShiftInst(Instruction::Shl, Op0,
|
|
ConstantUInt::get(Type::UByteTy, C));
|
|
} else {
|
|
ConstantFP *Op1F = 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'
|
|
}
|
|
}
|
|
|
|
if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
|
|
if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
|
|
return BinaryOperator::create(Instruction::Mul, Op0v, Op1v);
|
|
|
|
return Changed ? &I : 0;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
|
|
// div X, 1 == X
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) {
|
|
if (RHS->equalsInt(1))
|
|
return ReplaceInstUsesWith(I, I.getOperand(0));
|
|
|
|
// 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 (uint64_t C = Log2(Val))
|
|
return new ShiftInst(Instruction::Shr, I.getOperand(0),
|
|
ConstantUInt::get(Type::UByteTy, C));
|
|
}
|
|
|
|
// 0 / X == 0, we don't need to preserve faults!
|
|
if (ConstantInt *LHS = dyn_cast<ConstantInt>(I.getOperand(0)))
|
|
if (LHS->equalsInt(0))
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
Instruction *InstCombiner::visitRem(BinaryOperator &I) {
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) {
|
|
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 (Log2(Val))
|
|
return BinaryOperator::create(Instruction::And, I.getOperand(0),
|
|
ConstantUInt::get(I.getType(), Val-1));
|
|
}
|
|
|
|
// 0 % X == 0, we don't need to preserve faults!
|
|
if (ConstantInt *LHS = dyn_cast<ConstantInt>(I.getOperand(0)))
|
|
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()->getPrimitiveSize()*8;
|
|
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()->getPrimitiveSize()*8;
|
|
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()->getPrimitiveSize()*8;
|
|
int64_t Val = -1; // All ones
|
|
Val <<= TypeBits-1; // Shift over to the right spot
|
|
return CS->getValue() == Val+1;
|
|
}
|
|
|
|
/// 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!");
|
|
}
|
|
|
|
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);
|
|
}
|
|
};
|
|
|
|
|
|
|
|
Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
|
|
bool Changed = SimplifyCommutative(I);
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
// and X, X = X and X, 0 == 0
|
|
if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
|
|
return ReplaceInstUsesWith(I, Op1);
|
|
|
|
// and X, -1 == X
|
|
if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
|
|
if (RHS->isAllOnesValue())
|
|
return ReplaceInstUsesWith(I, Op0);
|
|
|
|
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
|
|
Value *X = Op0I->getOperand(0);
|
|
if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
|
|
if (Op0I->getOpcode() == Instruction::Xor) {
|
|
if ((*RHS & *Op0CI)->isNullValue()) {
|
|
// (X ^ C1) & C2 --> (X & C2) iff (C1&C2) == 0
|
|
return BinaryOperator::create(Instruction::And, X, RHS);
|
|
} else if (isOnlyUse(Op0)) {
|
|
// (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
|
|
std::string Op0Name = Op0I->getName(); Op0I->setName("");
|
|
Instruction *And = BinaryOperator::create(Instruction::And,
|
|
X, RHS, Op0Name);
|
|
InsertNewInstBefore(And, I);
|
|
return BinaryOperator::create(Instruction::Xor, And, *RHS & *Op0CI);
|
|
}
|
|
} else if (Op0I->getOpcode() == Instruction::Or) {
|
|
// (X | C1) & C2 --> X & C2 iff C1 & C1 == 0
|
|
if ((*RHS & *Op0CI)->isNullValue())
|
|
return BinaryOperator::create(Instruction::And, X, RHS);
|
|
|
|
Constant *Together = *RHS & *Op0CI;
|
|
if (Together == RHS) // (X | C) & C --> C
|
|
return ReplaceInstUsesWith(I, RHS);
|
|
|
|
if (isOnlyUse(Op0)) {
|
|
if (Together != Op0CI) {
|
|
// (X | C1) & C2 --> (X | (C1&C2)) & C2
|
|
std::string Op0Name = Op0I->getName(); Op0I->setName("");
|
|
Instruction *Or = BinaryOperator::create(Instruction::Or, X,
|
|
Together, Op0Name);
|
|
InsertNewInstBefore(Or, I);
|
|
return BinaryOperator::create(Instruction::And, Or, RHS);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
Value *Op0NotVal = dyn_castNotVal(Op0);
|
|
Value *Op1NotVal = dyn_castNotVal(Op1);
|
|
|
|
// (~A & ~B) == (~(A | B)) - Demorgan's Law
|
|
if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
|
|
Instruction *Or = BinaryOperator::create(Instruction::Or, Op0NotVal,
|
|
Op1NotVal,I.getName()+".demorgan");
|
|
InsertNewInstBefore(Or, I);
|
|
return BinaryOperator::createNot(Or);
|
|
}
|
|
|
|
if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
|
|
// (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;
|
|
}
|
|
|
|
|
|
|
|
Instruction *InstCombiner::visitOr(BinaryOperator &I) {
|
|
bool Changed = SimplifyCommutative(I);
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
// 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 (RHS->isAllOnesValue())
|
|
return ReplaceInstUsesWith(I, Op1);
|
|
|
|
if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) {
|
|
// (X & C1) | C2 --> (X | C2) & (C1|C2)
|
|
if (Op0I->getOpcode() == Instruction::And && isOnlyUse(Op0))
|
|
if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
|
|
std::string Op0Name = Op0I->getName(); Op0I->setName("");
|
|
Instruction *Or = BinaryOperator::create(Instruction::Or,
|
|
Op0I->getOperand(0), RHS,
|
|
Op0Name);
|
|
InsertNewInstBefore(Or, I);
|
|
return BinaryOperator::create(Instruction::And, Or, *RHS | *Op0CI);
|
|
}
|
|
|
|
// (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
|
|
if (Op0I->getOpcode() == Instruction::Xor && isOnlyUse(Op0))
|
|
if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
|
|
std::string Op0Name = Op0I->getName(); Op0I->setName("");
|
|
Instruction *Or = BinaryOperator::create(Instruction::Or,
|
|
Op0I->getOperand(0), RHS,
|
|
Op0Name);
|
|
InsertNewInstBefore(Or, I);
|
|
return BinaryOperator::create(Instruction::Xor, Or, *Op0CI & *~*RHS);
|
|
}
|
|
}
|
|
}
|
|
|
|
// (A & C1)|(A & C2) == A & (C1|C2)
|
|
if (Instruction *LHS = dyn_cast<BinaryOperator>(Op0))
|
|
if (Instruction *RHS = dyn_cast<BinaryOperator>(Op1))
|
|
if (LHS->getOperand(0) == RHS->getOperand(0))
|
|
if (Constant *C0 = dyn_castMaskingAnd(LHS))
|
|
if (Constant *C1 = dyn_castMaskingAnd(RHS))
|
|
return BinaryOperator::create(Instruction::And, LHS->getOperand(0),
|
|
*C0 | *C1);
|
|
|
|
Value *Op0NotVal = dyn_castNotVal(Op0);
|
|
Value *Op1NotVal = dyn_castNotVal(Op1);
|
|
|
|
if (Op1 == Op0NotVal) // ~A | A == -1
|
|
return ReplaceInstUsesWith(I,
|
|
ConstantIntegral::getAllOnesValue(I.getType()));
|
|
|
|
if (Op0 == Op1NotVal) // A | ~A == -1
|
|
return ReplaceInstUsesWith(I,
|
|
ConstantIntegral::getAllOnesValue(I.getType()));
|
|
|
|
// (~A | ~B) == (~(A & B)) - Demorgan's Law
|
|
if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
|
|
Instruction *And = BinaryOperator::create(Instruction::And, Op0NotVal,
|
|
Op1NotVal,I.getName()+".demorgan",
|
|
&I);
|
|
WorkList.push_back(And);
|
|
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;
|
|
|
|
return Changed ? &I : 0;
|
|
}
|
|
|
|
|
|
|
|
Instruction *InstCombiner::visitXor(BinaryOperator &I) {
|
|
bool Changed = SimplifyCommutative(I);
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
// xor X, X = 0
|
|
if (Op0 == Op1)
|
|
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->use_size() == 1)
|
|
return new SetCondInst(SCI->getInverseCondition(),
|
|
SCI->getOperand(0), SCI->getOperand(1));
|
|
|
|
if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
|
|
if (Op0I->getOpcode() == Instruction::And) {
|
|
// (X & C1) ^ C2 --> (X & C1) | C2 iff (C1&C2) == 0
|
|
if ((*RHS & *Op0CI)->isNullValue())
|
|
return BinaryOperator::create(Instruction::Or, Op0, RHS);
|
|
} else if (Op0I->getOpcode() == Instruction::Or) {
|
|
// (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2
|
|
if ((*RHS & *Op0CI) == RHS)
|
|
return BinaryOperator::create(Instruction::And, Op0, ~*RHS);
|
|
}
|
|
}
|
|
}
|
|
|
|
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);
|
|
}
|
|
|
|
if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
|
|
if (Op0I->getOpcode() == Instruction::Or && Op0I->use_size() == 1) {
|
|
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 = BinaryOperator::createNot(Op1, Op1->getName()+".not", &I);
|
|
WorkList.push_back(cast<Instruction>(NotB));
|
|
return BinaryOperator::create(Instruction::And, Op0I->getOperand(0),
|
|
NotB);
|
|
}
|
|
}
|
|
|
|
// (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1^C2 == 0
|
|
if (Constant *C1 = dyn_castMaskingAnd(Op0))
|
|
if (Constant *C2 = dyn_castMaskingAnd(Op1))
|
|
if (ConstantExpr::get(Instruction::And, C1, C2)->isNullValue())
|
|
return BinaryOperator::create(Instruction::Or, 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;
|
|
}
|
|
|
|
// AddOne, SubOne - Add or subtract a constant one from an integer constant...
|
|
static Constant *AddOne(ConstantInt *C) {
|
|
Constant *Result = ConstantExpr::get(Instruction::Add, C,
|
|
ConstantInt::get(C->getType(), 1));
|
|
assert(Result && "Constant folding integer addition failed!");
|
|
return Result;
|
|
}
|
|
static Constant *SubOne(ConstantInt *C) {
|
|
Constant *Result = ConstantExpr::get(Instruction::Sub, C,
|
|
ConstantInt::get(C->getType(), 1));
|
|
assert(Result && "Constant folding integer addition failed!");
|
|
return Result;
|
|
}
|
|
|
|
// 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;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitSetCondInst(BinaryOperator &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)));
|
|
|
|
// setcc <global/alloca*>, 0 - Global/Stack value addresses are never null!
|
|
if (isa<ConstantPointerNull>(Op1) &&
|
|
(isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0)))
|
|
return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I)));
|
|
|
|
|
|
// setcc's with boolean values can always be turned into bitwise operations
|
|
if (Ty == Type::BoolTy) {
|
|
// If this is <, >, or !=, we can change this into a simple xor instruction
|
|
if (!isTrueWhenEqual(I))
|
|
return BinaryOperator::create(Instruction::Xor, Op0, Op1, I.getName());
|
|
|
|
// Otherwise we need to make a temporary intermediate instruction and insert
|
|
// it into the instruction stream. This is what we are after:
|
|
//
|
|
// seteq bool %A, %B -> ~(A^B)
|
|
// setle bool %A, %B -> ~A | B
|
|
// setge bool %A, %B -> A | ~B
|
|
//
|
|
if (I.getOpcode() == Instruction::SetEQ) { // seteq case
|
|
Instruction *Xor = BinaryOperator::create(Instruction::Xor, Op0, Op1,
|
|
I.getName()+"tmp");
|
|
InsertNewInstBefore(Xor, I);
|
|
return BinaryOperator::createNot(Xor, I.getName());
|
|
}
|
|
|
|
// Handle the setXe cases...
|
|
assert(I.getOpcode() == Instruction::SetGE ||
|
|
I.getOpcode() == Instruction::SetLE);
|
|
|
|
if (I.getOpcode() == Instruction::SetGE)
|
|
std::swap(Op0, Op1); // Change setge -> setle
|
|
|
|
// Now we just have the SetLE case.
|
|
Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
|
|
InsertNewInstBefore(Not, I);
|
|
return BinaryOperator::create(Instruction::Or, Not, Op1, I.getName());
|
|
}
|
|
|
|
// Check to see if we are doing one of many comparisons against constant
|
|
// integers at the end of their ranges...
|
|
//
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
|
|
// 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::Add:
|
|
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->use_size() == 1) {
|
|
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),
|
|
*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)))
|
|
if (!(*BOC & *~*CI)->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 (!(*CI & *~*BOC)->isNullValue())
|
|
return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE));
|
|
|
|
// 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;
|
|
switch (BOC->getType()->getPrimitiveID()) {
|
|
case Type::UByteTyID: DestTy = Type::SByteTy; break;
|
|
case Type::UShortTyID: DestTy = Type::ShortTy; break;
|
|
case Type::UIntTyID: DestTy = Type::IntTy; break;
|
|
case Type::ULongTyID: DestTy = Type::LongTy; break;
|
|
default: assert(0 && "Invalid unsigned integer type!"); abort();
|
|
}
|
|
CastInst *NewCI = new CastInst(X,DestTy,X->getName()+".signed");
|
|
InsertNewInstBefore(NewCI, I);
|
|
X = NewCI;
|
|
}
|
|
return new SetCondInst(isSetNE ? Instruction::SetLT :
|
|
Instruction::SetGE, X,
|
|
Constant::getNullValue(X->getType()));
|
|
}
|
|
}
|
|
default: break;
|
|
}
|
|
}
|
|
}
|
|
|
|
// 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::create(Instruction::SetEQ, Op0,Op1, I.getName());
|
|
if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
|
|
return BinaryOperator::create(Instruction::SetNE, Op0,Op1, I.getName());
|
|
|
|
} 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::create(Instruction::SetEQ, Op0,Op1, I.getName());
|
|
if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
|
|
return BinaryOperator::create(Instruction::SetNE, Op0,Op1, I.getName());
|
|
|
|
// 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::create(Instruction::SetEQ, Op0,
|
|
SubOne(CI), I.getName());
|
|
if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
|
|
return BinaryOperator::create(Instruction::SetNE, Op0,
|
|
SubOne(CI), I.getName());
|
|
|
|
} else if (isMaxValueMinusOne(CI)) {
|
|
if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
|
|
return BinaryOperator::create(Instruction::SetEQ, Op0,
|
|
AddOne(CI), I.getName());
|
|
if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
|
|
return BinaryOperator::create(Instruction::SetNE, Op0,
|
|
AddOne(CI), I.getName());
|
|
}
|
|
}
|
|
|
|
return Changed ? &I : 0;
|
|
}
|
|
|
|
|
|
|
|
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);
|
|
|
|
// 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);
|
|
|
|
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()->getPrimitiveSize()*8;
|
|
if (CUI->getValue() >= TypeBits &&
|
|
(!Op0->getType()->isSigned() || isLeftShift))
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
|
|
|
|
// ((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::create(Instruction::Mul, BO->getOperand(0),
|
|
*BOOp << *CUI);
|
|
|
|
|
|
// 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 (Op0->use_size() == 1)
|
|
if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0))
|
|
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::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 =
|
|
ConstantFoldShiftInstruction(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 = ShiftAmt1C->getValue();
|
|
unsigned ShiftAmt2 = 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...
|
|
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::getShift(Instruction::Shl, C, ShiftAmt1C);
|
|
else
|
|
C = ConstantExpr::getShift(Instruction::Shr, C, ShiftAmt1C);
|
|
|
|
Instruction *Mask =
|
|
BinaryOperator::create(Instruction::And, 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));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
// 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) {
|
|
|
|
// 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;
|
|
|
|
// Allow free casting and conversion of sizes as long as the sign doesn't
|
|
// change...
|
|
if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
|
|
unsigned SrcSize = SrcTy->getPrimitiveSize();
|
|
unsigned MidSize = MidTy->getPrimitiveSize();
|
|
unsigned DstSize = DstTy->getPrimitiveSize();
|
|
|
|
// Cases where we are monotonically decreasing the size of the type are
|
|
// always ok, regardless of what sign changes are going on.
|
|
//
|
|
if (SrcSize >= MidSize && MidSize >= DstSize)
|
|
return true;
|
|
|
|
// Cases where the source and destination type are the same, but the middle
|
|
// type is bigger are noops.
|
|
//
|
|
if (SrcSize == DstSize && MidSize > SrcSize)
|
|
return true;
|
|
|
|
// If we are monotonically growing, things are more complex.
|
|
//
|
|
if (SrcSize <= MidSize && MidSize <= DstSize) {
|
|
// We have eight combinations of signedness to worry about. Here's the
|
|
// table:
|
|
static const int SignTable[8] = {
|
|
// CODE, SrcSigned, MidSigned, DstSigned, Comment
|
|
1, // U U U Always ok
|
|
1, // U U S Always ok
|
|
3, // U S U Ok iff SrcSize != MidSize
|
|
3, // U S S Ok iff SrcSize != MidSize
|
|
0, // S U U Never ok
|
|
2, // S U S Ok iff MidSize == DstSize
|
|
1, // S S U Always ok
|
|
1, // S S S Always ok
|
|
};
|
|
|
|
// Choose an action based on the current entry of the signtable that this
|
|
// cast of cast refers to...
|
|
unsigned Row = SrcTy->isSigned()*4+MidTy->isSigned()*2+DstTy->isSigned();
|
|
switch (SignTable[Row]) {
|
|
case 0: return false; // Never ok
|
|
case 1: return true; // Always ok
|
|
case 2: return MidSize == DstSize; // Ok iff MidSize == DstSize
|
|
case 3: // Ok iff SrcSize != MidSize
|
|
return SrcSize != MidSize || SrcTy == Type::BoolTy;
|
|
default: assert(0 && "Bad entry in sign table!");
|
|
}
|
|
}
|
|
}
|
|
|
|
// Otherwise, we cannot succeed. Specifically we do not want to allow things
|
|
// like: short -> ushort -> uint, because this can create wrong results if
|
|
// the input short is negative!
|
|
//
|
|
return false;
|
|
}
|
|
|
|
static bool ValueRequiresCast(const Value *V, const Type *Ty) {
|
|
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))
|
|
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 casting the result of another cast instruction, try to eliminate this
|
|
// one!
|
|
//
|
|
if (CastInst *CSrc = dyn_cast<CastInst>(Src)) {
|
|
if (isEliminableCastOfCast(CSrc->getOperand(0)->getType(),
|
|
CSrc->getType(), CI.getType())) {
|
|
// 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 (CSrc->getOperand(0)->getType() == CI.getType() &&
|
|
CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
|
|
CI.getType()->isUnsigned() && CSrc->getType()->isUnsigned() &&
|
|
CSrc->getType()->getPrimitiveSize() < CI.getType()->getPrimitiveSize()){
|
|
assert(CSrc->getType() != Type::ULongTy &&
|
|
"Cannot have type bigger than ulong!");
|
|
uint64_t AndValue = (1ULL << CSrc->getType()->getPrimitiveSize()*8)-1;
|
|
Constant *AndOp = ConstantUInt::get(CI.getType(), AndValue);
|
|
return BinaryOperator::create(Instruction::And, CSrc->getOperand(0),
|
|
AndOp);
|
|
}
|
|
}
|
|
|
|
// 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 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->use_size() == 1 && Src->getType()->isIntegral() &&
|
|
CI.getType()->isInteger()) { // Don't mess with casts to bool here
|
|
const Type *DestTy = CI.getType();
|
|
unsigned SrcBitSize = getTypeSizeInBits(Src->getType());
|
|
unsigned DestBitSize = getTypeSizeInBits(DestTy);
|
|
|
|
Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0;
|
|
Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0;
|
|
|
|
switch (SrcI->getOpcode()) {
|
|
case Instruction::Add:
|
|
case Instruction::Mul:
|
|
case Instruction::And:
|
|
case Instruction::Or:
|
|
case Instruction::Xor:
|
|
// If we are discarding information, 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) ||
|
|
!ValueRequiresCast(Op0, DestTy)) {
|
|
Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI);
|
|
Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI);
|
|
return BinaryOperator::create(cast<BinaryOperator>(SrcI)
|
|
->getOpcode(), Op0c, Op1c);
|
|
}
|
|
}
|
|
break;
|
|
case Instruction::Shl:
|
|
// Allow changing the sign of the source operand. Do not allow changing
|
|
// the size of the shift, UNLESS the shift amount is a constant. We
|
|
// 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;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
// CallInst simplification
|
|
//
|
|
Instruction *InstCombiner::visitCallInst(CallInst &CI) {
|
|
if (transformConstExprCastCall(&CI)) return 0;
|
|
return 0;
|
|
}
|
|
|
|
// InvokeInst simplification
|
|
//
|
|
Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) {
|
|
if (transformConstExprCastCall(&II)) return 0;
|
|
return 0;
|
|
}
|
|
|
|
// getPromotedType - Return the specified type promoted as it would be to pass
|
|
// though a va_arg area...
|
|
static const Type *getPromotedType(const Type *Ty) {
|
|
switch (Ty->getPrimitiveID()) {
|
|
case Type::SByteTyID:
|
|
case Type::ShortTyID: return Type::IntTy;
|
|
case Type::UByteTyID:
|
|
case Type::UShortTyID: return Type::UIntTy;
|
|
case Type::FloatTyID: return Type::DoubleTy;
|
|
default: return Ty;
|
|
}
|
|
}
|
|
|
|
// 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<ConstantPointerRef>(CE->getOperand(0)))
|
|
return false;
|
|
ConstantPointerRef *CPR = cast<ConstantPointerRef>(CE->getOperand(0));
|
|
if (!isa<Function>(CPR->getValue())) return false;
|
|
Function *Callee = cast<Function>(CPR->getValue());
|
|
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();
|
|
|
|
if (Callee->isExternal() &&
|
|
!OldRetTy->isLosslesslyConvertibleTo(FT->getReturnType()))
|
|
return false; // Cannot transform this return value...
|
|
|
|
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 {
|
|
Instruction *Cast = new CastInst(*AI, ParamTy, "tmp");
|
|
InsertNewInstBefore(Cast, *Caller);
|
|
Args.push_back(Cast);
|
|
}
|
|
}
|
|
|
|
// 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->getExceptionalDest(),
|
|
Args, Caller->getName(), Caller);
|
|
} else {
|
|
NC = new CallInst(Callee, Args, Caller->getName(), Caller);
|
|
}
|
|
|
|
// 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");
|
|
InsertNewInstBefore(NC, *Caller);
|
|
AddUsesToWorkList(*Caller);
|
|
} else {
|
|
NV = Constant::getNullValue(Caller->getType());
|
|
}
|
|
}
|
|
|
|
if (Caller->getType() != Type::VoidTy && !Caller->use_empty())
|
|
Caller->replaceAllUsesWith(NV);
|
|
Caller->getParent()->getInstList().erase(Caller);
|
|
removeFromWorkList(Caller);
|
|
return true;
|
|
}
|
|
|
|
|
|
|
|
// PHINode simplification
|
|
//
|
|
Instruction *InstCombiner::visitPHINode(PHINode &PN) {
|
|
// If the PHI node only has one incoming value, eliminate the PHI node...
|
|
if (PN.getNumIncomingValues() == 1)
|
|
return ReplaceInstUsesWith(PN, PN.getIncomingValue(0));
|
|
|
|
// Otherwise if all of the incoming values are the same for the PHI, replace
|
|
// the PHI node with the incoming value.
|
|
//
|
|
Value *InVal = 0;
|
|
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
|
|
if (PN.getIncomingValue(i) != &PN) // Not the PHI node itself...
|
|
if (InVal && PN.getIncomingValue(i) != InVal)
|
|
return 0; // Not the same, bail out.
|
|
else
|
|
InVal = PN.getIncomingValue(i);
|
|
|
|
// The only case that could cause InVal to be null is if we have a PHI node
|
|
// that only has entries for itself. In this case, there is no entry into the
|
|
// loop, so kill the PHI.
|
|
//
|
|
if (InVal == 0) InVal = Constant::getNullValue(PN.getType());
|
|
|
|
// All of the incoming values are the same, replace the PHI node now.
|
|
return ReplaceInstUsesWith(PN, InVal);
|
|
}
|
|
|
|
|
|
Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
|
|
// Is it 'getelementptr %P, long 0' or 'getelementptr %P'
|
|
// If so, eliminate the noop.
|
|
if ((GEP.getNumOperands() == 2 &&
|
|
GEP.getOperand(1) == Constant::getNullValue(Type::LongTy)) ||
|
|
GEP.getNumOperands() == 1)
|
|
return ReplaceInstUsesWith(GEP, GEP.getOperand(0));
|
|
|
|
// 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.
|
|
//
|
|
if (GetElementPtrInst *Src = dyn_cast<GetElementPtrInst>(GEP.getOperand(0))) {
|
|
std::vector<Value *> Indices;
|
|
|
|
// Can we combine the two pointer arithmetics offsets?
|
|
if (Src->getNumOperands() == 2 && isa<Constant>(Src->getOperand(1)) &&
|
|
isa<Constant>(GEP.getOperand(1))) {
|
|
// Replace: gep (gep %P, long C1), long C2, ...
|
|
// With: gep %P, long (C1+C2), ...
|
|
Value *Sum = ConstantExpr::get(Instruction::Add,
|
|
cast<Constant>(Src->getOperand(1)),
|
|
cast<Constant>(GEP.getOperand(1)));
|
|
assert(Sum && "Constant folding of longs failed!?");
|
|
GEP.setOperand(0, Src->getOperand(0));
|
|
GEP.setOperand(1, Sum);
|
|
AddUsesToWorkList(*Src); // Reduce use count of Src
|
|
return &GEP;
|
|
} else if (Src->getNumOperands() == 2) {
|
|
// Replace: gep (gep %P, long B), long A, ...
|
|
// With: T = long A+B; gep %P, T, ...
|
|
//
|
|
Value *Sum = BinaryOperator::create(Instruction::Add, Src->getOperand(1),
|
|
GEP.getOperand(1),
|
|
Src->getName()+".sum", &GEP);
|
|
GEP.setOperand(0, Src->getOperand(0));
|
|
GEP.setOperand(1, Sum);
|
|
WorkList.push_back(cast<Instruction>(Sum));
|
|
return &GEP;
|
|
} else if (*GEP.idx_begin() == Constant::getNullValue(Type::LongTy) &&
|
|
Src->getNumOperands() != 1) {
|
|
// Otherwise we can do the fold if the first index of the GEP is a zero
|
|
Indices.insert(Indices.end(), Src->idx_begin(), Src->idx_end());
|
|
Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
|
|
} else if (Src->getOperand(Src->getNumOperands()-1) ==
|
|
Constant::getNullValue(Type::LongTy)) {
|
|
// If the src gep ends with a constant array index, merge this get into
|
|
// it, even if we have a non-zero array index.
|
|
Indices.insert(Indices.end(), Src->idx_begin(), Src->idx_end()-1);
|
|
Indices.insert(Indices.end(), GEP.idx_begin(), GEP.idx_end());
|
|
}
|
|
|
|
if (!Indices.empty())
|
|
return new GetElementPtrInst(Src->getOperand(0), Indices, GEP.getName());
|
|
|
|
} else if (GlobalValue *GV = dyn_cast<GlobalValue>(GEP.getOperand(0))) {
|
|
// 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(ConstantPointerRef::get(GV), Indices);
|
|
|
|
// Replace all uses of the GEP with the new constexpr...
|
|
return ReplaceInstUsesWith(GEP, CE);
|
|
}
|
|
}
|
|
|
|
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(), &AI);
|
|
else {
|
|
assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
|
|
New = new AllocaInst(NewTy, 0, AI.getName(), &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...
|
|
//
|
|
std::vector<Value*> Idx(2, Constant::getNullValue(Type::LongTy));
|
|
Value *V = new GetElementPtrInst(New, Idx, New->getName()+".sub", It);
|
|
|
|
// Now make everything use the getelementptr instead of the original
|
|
// allocation.
|
|
ReplaceInstUsesWith(AI, V);
|
|
return &AI;
|
|
}
|
|
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(Type::LongTy))
|
|
return 0; // Do not allow stepping over the value!
|
|
|
|
// Loop over all of the operands, tracking down which value we are
|
|
// addressing...
|
|
for (unsigned i = 2, e = CE->getNumOperands(); i != e; ++i)
|
|
if (ConstantUInt *CU = dyn_cast<ConstantUInt>(CE->getOperand(i))) {
|
|
ConstantStruct *CS = cast<ConstantStruct>(C);
|
|
if (CU->getValue() >= CS->getValues().size()) return 0;
|
|
C = cast<Constant>(CS->getValues()[CU->getValue()]);
|
|
} else if (ConstantSInt *CS = dyn_cast<ConstantSInt>(CE->getOperand(i))) {
|
|
ConstantArray *CA = cast<ConstantArray>(C);
|
|
if ((uint64_t)CS->getValue() >= CA->getValues().size()) return 0;
|
|
C = cast<Constant>(CA->getValues()[CS->getValue()]);
|
|
} else
|
|
return 0;
|
|
return C;
|
|
}
|
|
|
|
Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
|
|
Value *Op = LI.getOperand(0);
|
|
if (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(Op))
|
|
Op = CPR->getValue();
|
|
|
|
// 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 (ConstantPointerRef *G=dyn_cast<ConstantPointerRef>(CE->getOperand(0)))
|
|
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(G->getValue()))
|
|
if (GV->isConstant() && !GV->isExternal())
|
|
if (Constant *V = GetGEPGlobalInitializer(GV->getInitializer(), CE))
|
|
return ReplaceInstUsesWith(LI, V);
|
|
return 0;
|
|
}
|
|
|
|
|
|
Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
|
|
// Change br (not X), label True, label False to: br X, label False, True
|
|
if (BI.isConditional() && !isa<Constant>(BI.getCondition()))
|
|
if (Value *V = dyn_castNotVal(BI.getCondition())) {
|
|
BasicBlock *TrueDest = BI.getSuccessor(0);
|
|
BasicBlock *FalseDest = BI.getSuccessor(1);
|
|
// Swap Destinations and condition...
|
|
BI.setCondition(V);
|
|
BI.setSuccessor(0, FalseDest);
|
|
BI.setSuccessor(1, TrueDest);
|
|
return &BI;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
|
|
void InstCombiner::removeFromWorkList(Instruction *I) {
|
|
WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
|
|
WorkList.end());
|
|
}
|
|
|
|
bool InstCombiner::runOnFunction(Function &F) {
|
|
bool Changed = false;
|
|
|
|
WorkList.insert(WorkList.end(), inst_begin(F), inst_end(F));
|
|
|
|
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...
|
|
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
|
|
if (Instruction *Op = dyn_cast<Instruction>(I->getOperand(i)))
|
|
WorkList.push_back(Op);
|
|
|
|
++NumDeadInst;
|
|
BasicBlock::iterator BBI = I;
|
|
if (dceInstruction(BBI)) {
|
|
removeFromWorkList(I);
|
|
continue;
|
|
}
|
|
}
|
|
|
|
// Instruction isn't dead, see if we can constant propagate it...
|
|
if (Constant *C = ConstantFoldInstruction(I)) {
|
|
// Add operands to the worklist...
|
|
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
|
|
if (Instruction *Op = dyn_cast<Instruction>(I->getOperand(i)))
|
|
WorkList.push_back(Op);
|
|
ReplaceInstUsesWith(*I, C);
|
|
|
|
++NumConstProp;
|
|
BasicBlock::iterator BBI = I;
|
|
if (dceInstruction(BBI)) {
|
|
removeFromWorkList(I);
|
|
continue;
|
|
}
|
|
}
|
|
|
|
// 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) {
|
|
// Instructions can end up on the worklist more than once. Make sure
|
|
// we do not process an instruction that has been deleted.
|
|
removeFromWorkList(I);
|
|
ReplaceInstWithInst(I, Result);
|
|
} else {
|
|
BasicBlock::iterator II = I;
|
|
|
|
// If the instruction was modified, it's possible that it is now dead.
|
|
// if so, remove it.
|
|
if (dceInstruction(II)) {
|
|
// Instructions may end up in the worklist more than once. Erase them
|
|
// all.
|
|
removeFromWorkList(I);
|
|
Result = 0;
|
|
}
|
|
}
|
|
|
|
if (Result) {
|
|
WorkList.push_back(Result);
|
|
AddUsesToWorkList(*Result);
|
|
}
|
|
Changed = true;
|
|
}
|
|
}
|
|
|
|
return Changed;
|
|
}
|
|
|
|
Pass *createInstructionCombiningPass() {
|
|
return new InstCombiner();
|
|
}
|