| //===- InstructionCombining.cpp - Combine multiple instructions -----------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // InstructionCombining - Combine instructions to form fewer, simple |
| // instructions. This pass does not modify the CFG. This pass is where |
| // algebraic simplification happens. |
| // |
| // This pass combines things like: |
| // %Y = add i32 %X, 1 |
| // %Z = add i32 %Y, 1 |
| // into: |
| // %Z = add i32 %X, 2 |
| // |
| // This is a simple worklist driven algorithm. |
| // |
| // This pass guarantees that the following canonicalizations are performed on |
| // the program: |
| // 1. If a binary operator has a constant operand, it is moved to the RHS |
| // 2. Bitwise operators with constant operands are always grouped so that |
| // shifts are performed first, then or's, then and's, then xor's. |
| // 3. Compare instructions are converted from <,>,<=,>= to ==,!= if possible |
| // 4. All cmp instructions on boolean values are replaced with logical ops |
| // 5. add X, X is represented as (X*2) => (X << 1) |
| // 6. Multiplies with a power-of-two constant argument are transformed into |
| // shifts. |
| // ... etc. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #define DEBUG_TYPE "instcombine" |
| #include "llvm/Transforms/Scalar.h" |
| #include "llvm/IntrinsicInst.h" |
| #include "llvm/Pass.h" |
| #include "llvm/DerivedTypes.h" |
| #include "llvm/GlobalVariable.h" |
| #include "llvm/Analysis/ConstantFolding.h" |
| #include "llvm/Analysis/ValueTracking.h" |
| #include "llvm/Target/TargetData.h" |
| #include "llvm/Transforms/Utils/BasicBlockUtils.h" |
| #include "llvm/Transforms/Utils/Local.h" |
| #include "llvm/Support/CallSite.h" |
| #include "llvm/Support/ConstantRange.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/GetElementPtrTypeIterator.h" |
| #include "llvm/Support/InstVisitor.h" |
| #include "llvm/Support/MathExtras.h" |
| #include "llvm/Support/PatternMatch.h" |
| #include "llvm/Support/Compiler.h" |
| #include "llvm/ADT/DenseMap.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/ADT/SmallPtrSet.h" |
| #include "llvm/ADT/Statistic.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include <algorithm> |
| #include <climits> |
| #include <sstream> |
| using namespace llvm; |
| using namespace llvm::PatternMatch; |
| |
| STATISTIC(NumCombined , "Number of insts combined"); |
| STATISTIC(NumConstProp, "Number of constant folds"); |
| STATISTIC(NumDeadInst , "Number of dead inst eliminated"); |
| STATISTIC(NumDeadStore, "Number of dead stores eliminated"); |
| STATISTIC(NumSunkInst , "Number of instructions sunk"); |
| |
| namespace { |
| class VISIBILITY_HIDDEN InstCombiner |
| : public FunctionPass, |
| public InstVisitor<InstCombiner, Instruction*> { |
| // Worklist of all of the instructions that need to be simplified. |
| SmallVector<Instruction*, 256> Worklist; |
| DenseMap<Instruction*, unsigned> WorklistMap; |
| TargetData *TD; |
| bool MustPreserveLCSSA; |
| public: |
| static char ID; // Pass identification, replacement for typeid |
| InstCombiner() : FunctionPass(&ID) {} |
| |
| /// AddToWorkList - Add the specified instruction to the worklist if it |
| /// isn't already in it. |
| void AddToWorkList(Instruction *I) { |
| if (WorklistMap.insert(std::make_pair(I, Worklist.size())).second) |
| Worklist.push_back(I); |
| } |
| |
| // RemoveFromWorkList - remove I from the worklist if it exists. |
| void RemoveFromWorkList(Instruction *I) { |
| DenseMap<Instruction*, unsigned>::iterator It = WorklistMap.find(I); |
| if (It == WorklistMap.end()) return; // Not in worklist. |
| |
| // Don't bother moving everything down, just null out the slot. |
| Worklist[It->second] = 0; |
| |
| WorklistMap.erase(It); |
| } |
| |
| Instruction *RemoveOneFromWorkList() { |
| Instruction *I = Worklist.back(); |
| Worklist.pop_back(); |
| WorklistMap.erase(I); |
| return I; |
| } |
| |
| |
| /// AddUsersToWorkList - When an instruction is simplified, add all users of |
| /// the instruction to the work lists because they might get more simplified |
| /// now. |
| /// |
| void AddUsersToWorkList(Value &I) { |
| for (Value::use_iterator UI = I.use_begin(), UE = I.use_end(); |
| UI != UE; ++UI) |
| AddToWorkList(cast<Instruction>(*UI)); |
| } |
| |
| /// AddUsesToWorkList - When an instruction is simplified, add operands to |
| /// the work lists because they might get more simplified now. |
| /// |
| void AddUsesToWorkList(Instruction &I) { |
| for (User::op_iterator i = I.op_begin(), e = I.op_end(); i != e; ++i) |
| if (Instruction *Op = dyn_cast<Instruction>(*i)) |
| AddToWorkList(Op); |
| } |
| |
| /// AddSoonDeadInstToWorklist - The specified instruction is about to become |
| /// dead. Add all of its operands to the worklist, turning them into |
| /// undef's to reduce the number of uses of those instructions. |
| /// |
| /// Return the specified operand before it is turned into an undef. |
| /// |
| Value *AddSoonDeadInstToWorklist(Instruction &I, unsigned op) { |
| Value *R = I.getOperand(op); |
| |
| for (User::op_iterator i = I.op_begin(), e = I.op_end(); i != e; ++i) |
| if (Instruction *Op = dyn_cast<Instruction>(*i)) { |
| AddToWorkList(Op); |
| // Set the operand to undef to drop the use. |
| *i = UndefValue::get(Op->getType()); |
| } |
| |
| return R; |
| } |
| |
| public: |
| virtual bool runOnFunction(Function &F); |
| |
| bool DoOneIteration(Function &F, unsigned ItNum); |
| |
| virtual void getAnalysisUsage(AnalysisUsage &AU) const { |
| AU.addRequired<TargetData>(); |
| AU.addPreservedID(LCSSAID); |
| AU.setPreservesCFG(); |
| } |
| |
| TargetData &getTargetData() const { return *TD; } |
| |
| // Visitation implementation - Implement instruction combining for different |
| // instruction types. The semantics are as follows: |
| // Return Value: |
| // null - No change was made |
| // I - Change was made, I is still valid, I may be dead though |
| // otherwise - Change was made, replace I with returned instruction |
| // |
| Instruction *visitAdd(BinaryOperator &I); |
| Instruction *visitSub(BinaryOperator &I); |
| Instruction *visitMul(BinaryOperator &I); |
| Instruction *visitURem(BinaryOperator &I); |
| Instruction *visitSRem(BinaryOperator &I); |
| Instruction *visitFRem(BinaryOperator &I); |
| bool SimplifyDivRemOfSelect(BinaryOperator &I); |
| Instruction *commonRemTransforms(BinaryOperator &I); |
| Instruction *commonIRemTransforms(BinaryOperator &I); |
| Instruction *commonDivTransforms(BinaryOperator &I); |
| Instruction *commonIDivTransforms(BinaryOperator &I); |
| Instruction *visitUDiv(BinaryOperator &I); |
| Instruction *visitSDiv(BinaryOperator &I); |
| Instruction *visitFDiv(BinaryOperator &I); |
| Instruction *FoldAndOfICmps(Instruction &I, ICmpInst *LHS, ICmpInst *RHS); |
| Instruction *visitAnd(BinaryOperator &I); |
| Instruction *FoldOrOfICmps(Instruction &I, ICmpInst *LHS, ICmpInst *RHS); |
| Instruction *FoldOrWithConstants(BinaryOperator &I, Value *Op, |
| Value *A, Value *B, Value *C); |
| Instruction *visitOr (BinaryOperator &I); |
| Instruction *visitXor(BinaryOperator &I); |
| Instruction *visitShl(BinaryOperator &I); |
| Instruction *visitAShr(BinaryOperator &I); |
| Instruction *visitLShr(BinaryOperator &I); |
| Instruction *commonShiftTransforms(BinaryOperator &I); |
| Instruction *FoldFCmp_IntToFP_Cst(FCmpInst &I, Instruction *LHSI, |
| Constant *RHSC); |
| Instruction *visitFCmpInst(FCmpInst &I); |
| Instruction *visitICmpInst(ICmpInst &I); |
| Instruction *visitICmpInstWithCastAndCast(ICmpInst &ICI); |
| Instruction *visitICmpInstWithInstAndIntCst(ICmpInst &ICI, |
| Instruction *LHS, |
| ConstantInt *RHS); |
| Instruction *FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI, |
| ConstantInt *DivRHS); |
| |
| Instruction *FoldGEPICmp(User *GEPLHS, Value *RHS, |
| ICmpInst::Predicate Cond, Instruction &I); |
| Instruction *FoldShiftByConstant(Value *Op0, ConstantInt *Op1, |
| BinaryOperator &I); |
| Instruction *commonCastTransforms(CastInst &CI); |
| Instruction *commonIntCastTransforms(CastInst &CI); |
| Instruction *commonPointerCastTransforms(CastInst &CI); |
| Instruction *visitTrunc(TruncInst &CI); |
| Instruction *visitZExt(ZExtInst &CI); |
| Instruction *visitSExt(SExtInst &CI); |
| Instruction *visitFPTrunc(FPTruncInst &CI); |
| Instruction *visitFPExt(CastInst &CI); |
| Instruction *visitFPToUI(FPToUIInst &FI); |
| Instruction *visitFPToSI(FPToSIInst &FI); |
| Instruction *visitUIToFP(CastInst &CI); |
| Instruction *visitSIToFP(CastInst &CI); |
| Instruction *visitPtrToInt(CastInst &CI); |
| Instruction *visitIntToPtr(IntToPtrInst &CI); |
| Instruction *visitBitCast(BitCastInst &CI); |
| Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI, |
| Instruction *FI); |
| Instruction *visitSelectInst(SelectInst &SI); |
| Instruction *visitSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI); |
| Instruction *visitCallInst(CallInst &CI); |
| Instruction *visitInvokeInst(InvokeInst &II); |
| Instruction *visitPHINode(PHINode &PN); |
| Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP); |
| Instruction *visitAllocationInst(AllocationInst &AI); |
| Instruction *visitFreeInst(FreeInst &FI); |
| Instruction *visitLoadInst(LoadInst &LI); |
| Instruction *visitStoreInst(StoreInst &SI); |
| Instruction *visitBranchInst(BranchInst &BI); |
| Instruction *visitSwitchInst(SwitchInst &SI); |
| Instruction *visitInsertElementInst(InsertElementInst &IE); |
| Instruction *visitExtractElementInst(ExtractElementInst &EI); |
| Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI); |
| Instruction *visitExtractValueInst(ExtractValueInst &EV); |
| |
| // visitInstruction - Specify what to return for unhandled instructions... |
| Instruction *visitInstruction(Instruction &I) { return 0; } |
| |
| private: |
| Instruction *visitCallSite(CallSite CS); |
| bool transformConstExprCastCall(CallSite CS); |
| Instruction *transformCallThroughTrampoline(CallSite CS); |
| Instruction *transformZExtICmp(ICmpInst *ICI, Instruction &CI, |
| bool DoXform = true); |
| bool WillNotOverflowSignedAdd(Value *LHS, Value *RHS); |
| |
| public: |
| // InsertNewInstBefore - insert an instruction New before instruction Old |
| // in the program. Add the new instruction to the worklist. |
| // |
| Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) { |
| assert(New && New->getParent() == 0 && |
| "New instruction already inserted into a basic block!"); |
| BasicBlock *BB = Old.getParent(); |
| BB->getInstList().insert(&Old, New); // Insert inst |
| AddToWorkList(New); |
| return New; |
| } |
| |
| /// InsertCastBefore - Insert a cast of V to TY before the instruction POS. |
| /// This also adds the cast to the worklist. Finally, this returns the |
| /// cast. |
| Value *InsertCastBefore(Instruction::CastOps opc, Value *V, const Type *Ty, |
| Instruction &Pos) { |
| if (V->getType() == Ty) return V; |
| |
| if (Constant *CV = dyn_cast<Constant>(V)) |
| return ConstantExpr::getCast(opc, CV, Ty); |
| |
| Instruction *C = CastInst::Create(opc, V, Ty, V->getName(), &Pos); |
| AddToWorkList(C); |
| return C; |
| } |
| |
| Value *InsertBitCastBefore(Value *V, const Type *Ty, Instruction &Pos) { |
| return InsertCastBefore(Instruction::BitCast, V, Ty, Pos); |
| } |
| |
| |
| // ReplaceInstUsesWith - This method is to be used when an instruction is |
| // found to be dead, replacable with another preexisting expression. Here |
| // we add all uses of I to the worklist, replace all uses of I with the new |
| // value, then return I, so that the inst combiner will know that I was |
| // modified. |
| // |
| Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) { |
| AddUsersToWorkList(I); // Add all modified instrs to worklist |
| if (&I != V) { |
| I.replaceAllUsesWith(V); |
| return &I; |
| } else { |
| // If we are replacing the instruction with itself, this must be in a |
| // segment of unreachable code, so just clobber the instruction. |
| I.replaceAllUsesWith(UndefValue::get(I.getType())); |
| return &I; |
| } |
| } |
| |
| // UpdateValueUsesWith - This method is to be used when an value is |
| // found to be replacable with another preexisting expression or was |
| // updated. Here we add all uses of I to the worklist, replace all uses of |
| // I with the new value (unless the instruction was just updated), then |
| // return true, so that the inst combiner will know that I was modified. |
| // |
| bool UpdateValueUsesWith(Value *Old, Value *New) { |
| AddUsersToWorkList(*Old); // Add all modified instrs to worklist |
| if (Old != New) |
| Old->replaceAllUsesWith(New); |
| if (Instruction *I = dyn_cast<Instruction>(Old)) |
| AddToWorkList(I); |
| if (Instruction *I = dyn_cast<Instruction>(New)) |
| AddToWorkList(I); |
| return true; |
| } |
| |
| // EraseInstFromFunction - When dealing with an instruction that has side |
| // effects or produces a void value, we can't rely on DCE to delete the |
| // instruction. Instead, visit methods should return the value returned by |
| // this function. |
| Instruction *EraseInstFromFunction(Instruction &I) { |
| assert(I.use_empty() && "Cannot erase instruction that is used!"); |
| AddUsesToWorkList(I); |
| RemoveFromWorkList(&I); |
| I.eraseFromParent(); |
| return 0; // Don't do anything with FI |
| } |
| |
| void ComputeMaskedBits(Value *V, const APInt &Mask, APInt &KnownZero, |
| APInt &KnownOne, unsigned Depth = 0) const { |
| return llvm::ComputeMaskedBits(V, Mask, KnownZero, KnownOne, TD, Depth); |
| } |
| |
| bool MaskedValueIsZero(Value *V, const APInt &Mask, |
| unsigned Depth = 0) const { |
| return llvm::MaskedValueIsZero(V, Mask, TD, Depth); |
| } |
| unsigned ComputeNumSignBits(Value *Op, unsigned Depth = 0) const { |
| return llvm::ComputeNumSignBits(Op, TD, Depth); |
| } |
| |
| private: |
| |
| /// SimplifyCommutative - This performs a few simplifications for |
| /// commutative operators. |
| bool SimplifyCommutative(BinaryOperator &I); |
| |
| /// SimplifyCompare - This reorders the operands of a CmpInst to get them in |
| /// most-complex to least-complex order. |
| bool SimplifyCompare(CmpInst &I); |
| |
| /// SimplifyDemandedBits - Attempts to replace V with a simpler value based |
| /// on the demanded bits. |
| bool SimplifyDemandedBits(Value *V, APInt DemandedMask, |
| APInt& KnownZero, APInt& KnownOne, |
| unsigned Depth = 0); |
| |
| Value *SimplifyDemandedVectorElts(Value *V, uint64_t DemandedElts, |
| uint64_t &UndefElts, unsigned Depth = 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 *FoldOpIntoPhi(Instruction &I); |
| |
| // 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 *FoldPHIArgOpIntoPHI(PHINode &PN); |
| Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN); |
| Instruction *FoldPHIArgGEPIntoPHI(PHINode &PN); |
| |
| |
| Instruction *OptAndOp(Instruction *Op, ConstantInt *OpRHS, |
| ConstantInt *AndRHS, BinaryOperator &TheAnd); |
| |
| Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask, |
| bool isSub, Instruction &I); |
| Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi, |
| bool isSigned, bool Inside, Instruction &IB); |
| Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocationInst &AI); |
| Instruction *MatchBSwap(BinaryOperator &I); |
| bool SimplifyStoreAtEndOfBlock(StoreInst &SI); |
| Instruction *SimplifyMemTransfer(MemIntrinsic *MI); |
| Instruction *SimplifyMemSet(MemSetInst *MI); |
| |
| |
| Value *EvaluateInDifferentType(Value *V, const Type *Ty, bool isSigned); |
| |
| bool CanEvaluateInDifferentType(Value *V, const IntegerType *Ty, |
| unsigned CastOpc, |
| int &NumCastsRemoved); |
| unsigned GetOrEnforceKnownAlignment(Value *V, |
| unsigned PrefAlign = 0); |
| |
| }; |
| } |
| |
| char InstCombiner::ID = 0; |
| static RegisterPass<InstCombiner> |
| X("instcombine", "Combine redundant instructions"); |
| |
| // getComplexity: Assign a complexity or rank value to LLVM Values... |
| // 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst |
| static unsigned getComplexity(Value *V) { |
| if (isa<Instruction>(V)) { |
| if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V)) |
| return 3; |
| return 4; |
| } |
| if (isa<Argument>(V)) return 3; |
| return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2; |
| } |
| |
| // isOnlyUse - Return true if this instruction will be deleted if we stop using |
| // it. |
| static bool isOnlyUse(Value *V) { |
| return V->hasOneUse() || isa<Constant>(V); |
| } |
| |
| // getPromotedType - Return the specified type promoted as it would be to pass |
| // though a va_arg area... |
| static const Type *getPromotedType(const Type *Ty) { |
| if (const IntegerType* ITy = dyn_cast<IntegerType>(Ty)) { |
| if (ITy->getBitWidth() < 32) |
| return Type::Int32Ty; |
| } |
| return Ty; |
| } |
| |
| /// getBitCastOperand - If the specified operand is a CastInst, a constant |
| /// expression bitcast, or a GetElementPtrInst with all zero indices, return the |
| /// operand value, otherwise return null. |
| static Value *getBitCastOperand(Value *V) { |
| if (BitCastInst *I = dyn_cast<BitCastInst>(V)) |
| // BitCastInst? |
| return I->getOperand(0); |
| else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V)) { |
| // GetElementPtrInst? |
| if (GEP->hasAllZeroIndices()) |
| return GEP->getOperand(0); |
| } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { |
| if (CE->getOpcode() == Instruction::BitCast) |
| // BitCast ConstantExp? |
| return CE->getOperand(0); |
| else if (CE->getOpcode() == Instruction::GetElementPtr) { |
| // GetElementPtr ConstantExp? |
| for (User::op_iterator I = CE->op_begin() + 1, E = CE->op_end(); |
| I != E; ++I) { |
| ConstantInt *CI = dyn_cast<ConstantInt>(I); |
| if (!CI || !CI->isZero()) |
| // Any non-zero indices? Not cast-like. |
| return 0; |
| } |
| // All-zero indices? This is just like casting. |
| return CE->getOperand(0); |
| } |
| } |
| return 0; |
| } |
| |
| /// This function is a wrapper around CastInst::isEliminableCastPair. It |
| /// simply extracts arguments and returns what that function returns. |
| static Instruction::CastOps |
| isEliminableCastPair( |
| const CastInst *CI, ///< The first cast instruction |
| unsigned opcode, ///< The opcode of the second cast instruction |
| const Type *DstTy, ///< The target type for the second cast instruction |
| TargetData *TD ///< The target data for pointer size |
| ) { |
| |
| const Type *SrcTy = CI->getOperand(0)->getType(); // A from above |
| const Type *MidTy = CI->getType(); // B from above |
| |
| // Get the opcodes of the two Cast instructions |
| Instruction::CastOps firstOp = Instruction::CastOps(CI->getOpcode()); |
| Instruction::CastOps secondOp = Instruction::CastOps(opcode); |
| |
| return Instruction::CastOps( |
| CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, |
| DstTy, TD->getIntPtrType())); |
| } |
| |
| /// ValueRequiresCast - Return true if the cast from "V to Ty" actually results |
| /// in any code being generated. It does not require codegen if V is simple |
| /// enough or if the cast can be folded into other casts. |
| static bool ValueRequiresCast(Instruction::CastOps opcode, const Value *V, |
| const Type *Ty, TargetData *TD) { |
| if (V->getType() == Ty || isa<Constant>(V)) return false; |
| |
| // If this is another cast that can be eliminated, it isn't codegen either. |
| if (const CastInst *CI = dyn_cast<CastInst>(V)) |
| if (isEliminableCastPair(CI, opcode, Ty, TD)) |
| return false; |
| return true; |
| } |
| |
| // SimplifyCommutative - This performs a few simplifications for commutative |
| // operators: |
| // |
| // 1. Order operands such that they are listed from right (least complex) to |
| // left (most complex). This puts constants before unary operators before |
| // binary operators. |
| // |
| // 2. Transform: (op (op V, C1), C2) ==> (op V, (op C1, C2)) |
| // 3. Transform: (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2)) |
| // |
| bool InstCombiner::SimplifyCommutative(BinaryOperator &I) { |
| bool Changed = false; |
| if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1))) |
| Changed = !I.swapOperands(); |
| |
| if (!I.isAssociative()) return Changed; |
| Instruction::BinaryOps Opcode = I.getOpcode(); |
| if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0))) |
| if (Op->getOpcode() == Opcode && isa<Constant>(Op->getOperand(1))) { |
| if (isa<Constant>(I.getOperand(1))) { |
| Constant *Folded = ConstantExpr::get(I.getOpcode(), |
| cast<Constant>(I.getOperand(1)), |
| cast<Constant>(Op->getOperand(1))); |
| I.setOperand(0, Op->getOperand(0)); |
| I.setOperand(1, Folded); |
| return true; |
| } else if (BinaryOperator *Op1=dyn_cast<BinaryOperator>(I.getOperand(1))) |
| if (Op1->getOpcode() == Opcode && isa<Constant>(Op1->getOperand(1)) && |
| isOnlyUse(Op) && isOnlyUse(Op1)) { |
| Constant *C1 = cast<Constant>(Op->getOperand(1)); |
| Constant *C2 = cast<Constant>(Op1->getOperand(1)); |
| |
| // Fold (op (op V1, C1), (op V2, C2)) ==> (op (op V1, V2), (op C1,C2)) |
| Constant *Folded = ConstantExpr::get(I.getOpcode(), C1, C2); |
| Instruction *New = BinaryOperator::Create(Opcode, Op->getOperand(0), |
| Op1->getOperand(0), |
| Op1->getName(), &I); |
| AddToWorkList(New); |
| I.setOperand(0, New); |
| I.setOperand(1, Folded); |
| return true; |
| } |
| } |
| return Changed; |
| } |
| |
| /// SimplifyCompare - For a CmpInst this function just orders the operands |
| /// so that theyare listed from right (least complex) to left (most complex). |
| /// This puts constants before unary operators before binary operators. |
| bool InstCombiner::SimplifyCompare(CmpInst &I) { |
| if (getComplexity(I.getOperand(0)) >= getComplexity(I.getOperand(1))) |
| return false; |
| I.swapOperands(); |
| // Compare instructions are not associative so there's nothing else we can do. |
| return true; |
| } |
| |
| // dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction |
| // if the LHS is a constant zero (which is the 'negate' form). |
| // |
| static inline Value *dyn_castNegVal(Value *V) { |
| if (BinaryOperator::isNeg(V)) |
| return BinaryOperator::getNegArgument(V); |
| |
| // Constants can be considered to be negated values if they can be folded. |
| if (ConstantInt *C = dyn_cast<ConstantInt>(V)) |
| return ConstantExpr::getNeg(C); |
| |
| if (ConstantVector *C = dyn_cast<ConstantVector>(V)) |
| if (C->getType()->getElementType()->isInteger()) |
| return ConstantExpr::getNeg(C); |
| |
| return 0; |
| } |
| |
| static inline Value *dyn_castNotVal(Value *V) { |
| if (BinaryOperator::isNot(V)) |
| return BinaryOperator::getNotArgument(V); |
| |
| // Constants can be considered to be not'ed values... |
| if (ConstantInt *C = dyn_cast<ConstantInt>(V)) |
| return ConstantInt::get(~C->getValue()); |
| return 0; |
| } |
| |
| // dyn_castFoldableMul - If this value is a multiply that can be folded into |
| // other computations (because it has a constant operand), return the |
| // non-constant operand of the multiply, and set CST to point to the multiplier. |
| // Otherwise, return null. |
| // |
| static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) { |
| if (V->hasOneUse() && V->getType()->isInteger()) |
| if (Instruction *I = dyn_cast<Instruction>(V)) { |
| if (I->getOpcode() == Instruction::Mul) |
| if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) |
| return I->getOperand(0); |
| if (I->getOpcode() == Instruction::Shl) |
| if ((CST = dyn_cast<ConstantInt>(I->getOperand(1)))) { |
| // The multiplier is really 1 << CST. |
| uint32_t BitWidth = cast<IntegerType>(V->getType())->getBitWidth(); |
| uint32_t CSTVal = CST->getLimitedValue(BitWidth); |
| CST = ConstantInt::get(APInt(BitWidth, 1).shl(CSTVal)); |
| return I->getOperand(0); |
| } |
| } |
| return 0; |
| } |
| |
| /// dyn_castGetElementPtr - If this is a getelementptr instruction or constant |
| /// expression, return it. |
| static User *dyn_castGetElementPtr(Value *V) { |
| if (isa<GetElementPtrInst>(V)) return cast<User>(V); |
| if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) |
| if (CE->getOpcode() == Instruction::GetElementPtr) |
| return cast<User>(V); |
| return false; |
| } |
| |
| /// getOpcode - If this is an Instruction or a ConstantExpr, return the |
| /// opcode value. Otherwise return UserOp1. |
| static unsigned getOpcode(const Value *V) { |
| if (const Instruction *I = dyn_cast<Instruction>(V)) |
| return I->getOpcode(); |
| if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) |
| return CE->getOpcode(); |
| // Use UserOp1 to mean there's no opcode. |
| return Instruction::UserOp1; |
| } |
| |
| /// AddOne - Add one to a ConstantInt |
| static ConstantInt *AddOne(ConstantInt *C) { |
| APInt Val(C->getValue()); |
| return ConstantInt::get(++Val); |
| } |
| /// SubOne - Subtract one from a ConstantInt |
| static ConstantInt *SubOne(ConstantInt *C) { |
| APInt Val(C->getValue()); |
| return ConstantInt::get(--Val); |
| } |
| /// Add - Add two ConstantInts together |
| static ConstantInt *Add(ConstantInt *C1, ConstantInt *C2) { |
| return ConstantInt::get(C1->getValue() + C2->getValue()); |
| } |
| /// And - Bitwise AND two ConstantInts together |
| static ConstantInt *And(ConstantInt *C1, ConstantInt *C2) { |
| return ConstantInt::get(C1->getValue() & C2->getValue()); |
| } |
| /// Subtract - Subtract one ConstantInt from another |
| static ConstantInt *Subtract(ConstantInt *C1, ConstantInt *C2) { |
| return ConstantInt::get(C1->getValue() - C2->getValue()); |
| } |
| /// Multiply - Multiply two ConstantInts together |
| static ConstantInt *Multiply(ConstantInt *C1, ConstantInt *C2) { |
| return ConstantInt::get(C1->getValue() * C2->getValue()); |
| } |
| /// MultiplyOverflows - True if the multiply can not be expressed in an int |
| /// this size. |
| static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) { |
| uint32_t W = C1->getBitWidth(); |
| APInt LHSExt = C1->getValue(), RHSExt = C2->getValue(); |
| if (sign) { |
| LHSExt.sext(W * 2); |
| RHSExt.sext(W * 2); |
| } else { |
| LHSExt.zext(W * 2); |
| RHSExt.zext(W * 2); |
| } |
| |
| APInt MulExt = LHSExt * RHSExt; |
| |
| if (sign) { |
| APInt Min = APInt::getSignedMinValue(W).sext(W * 2); |
| APInt Max = APInt::getSignedMaxValue(W).sext(W * 2); |
| return MulExt.slt(Min) || MulExt.sgt(Max); |
| } else |
| return MulExt.ugt(APInt::getLowBitsSet(W * 2, W)); |
| } |
| |
| |
| /// ShrinkDemandedConstant - Check to see if the specified operand of the |
| /// specified instruction is a constant integer. If so, check to see if there |
| /// are any bits set in the constant that are not demanded. If so, shrink the |
| /// constant and return true. |
| static bool ShrinkDemandedConstant(Instruction *I, unsigned OpNo, |
| APInt Demanded) { |
| assert(I && "No instruction?"); |
| assert(OpNo < I->getNumOperands() && "Operand index too large"); |
| |
| // If the operand is not a constant integer, nothing to do. |
| ConstantInt *OpC = dyn_cast<ConstantInt>(I->getOperand(OpNo)); |
| if (!OpC) return false; |
| |
| // If there are no bits set that aren't demanded, nothing to do. |
| Demanded.zextOrTrunc(OpC->getValue().getBitWidth()); |
| if ((~Demanded & OpC->getValue()) == 0) |
| return false; |
| |
| // This instruction is producing bits that are not demanded. Shrink the RHS. |
| Demanded &= OpC->getValue(); |
| I->setOperand(OpNo, ConstantInt::get(Demanded)); |
| return true; |
| } |
| |
| // ComputeSignedMinMaxValuesFromKnownBits - Given a signed integer type and a |
| // set of known zero and one bits, compute the maximum and minimum values that |
| // could have the specified known zero and known one bits, returning them in |
| // min/max. |
| static void ComputeSignedMinMaxValuesFromKnownBits(const Type *Ty, |
| const APInt& KnownZero, |
| const APInt& KnownOne, |
| APInt& Min, APInt& Max) { |
| uint32_t BitWidth = cast<IntegerType>(Ty)->getBitWidth(); |
| assert(KnownZero.getBitWidth() == BitWidth && |
| KnownOne.getBitWidth() == BitWidth && |
| Min.getBitWidth() == BitWidth && Max.getBitWidth() == BitWidth && |
| "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth."); |
| APInt UnknownBits = ~(KnownZero|KnownOne); |
| |
| // The minimum value is when all unknown bits are zeros, EXCEPT for the sign |
| // bit if it is unknown. |
| Min = KnownOne; |
| Max = KnownOne|UnknownBits; |
| |
| if (UnknownBits[BitWidth-1]) { // Sign bit is unknown |
| Min.set(BitWidth-1); |
| Max.clear(BitWidth-1); |
| } |
| } |
| |
| // ComputeUnsignedMinMaxValuesFromKnownBits - Given an unsigned integer type and |
| // a set of known zero and one bits, compute the maximum and minimum values that |
| // could have the specified known zero and known one bits, returning them in |
| // min/max. |
| static void ComputeUnsignedMinMaxValuesFromKnownBits(const Type *Ty, |
| const APInt &KnownZero, |
| const APInt &KnownOne, |
| APInt &Min, APInt &Max) { |
| uint32_t BitWidth = cast<IntegerType>(Ty)->getBitWidth(); BitWidth = BitWidth; |
| assert(KnownZero.getBitWidth() == BitWidth && |
| KnownOne.getBitWidth() == BitWidth && |
| Min.getBitWidth() == BitWidth && Max.getBitWidth() && |
| "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth."); |
| APInt UnknownBits = ~(KnownZero|KnownOne); |
| |
| // The minimum value is when the unknown bits are all zeros. |
| Min = KnownOne; |
| // The maximum value is when the unknown bits are all ones. |
| Max = KnownOne|UnknownBits; |
| } |
| |
| /// SimplifyDemandedBits - This function attempts to replace V with a simpler |
| /// value based on the demanded bits. When this function is called, it is known |
| /// that only the bits set in DemandedMask of the result of V are ever used |
| /// downstream. Consequently, depending on the mask and V, it may be possible |
| /// to replace V with a constant or one of its operands. In such cases, this |
| /// function does the replacement and returns true. In all other cases, it |
| /// returns false after analyzing the expression and setting KnownOne and known |
| /// to be one in the expression. KnownZero contains all the bits that are known |
| /// to be zero in the expression. These are provided to potentially allow the |
| /// caller (which might recursively be SimplifyDemandedBits itself) to simplify |
| /// the expression. KnownOne and KnownZero always follow the invariant that |
| /// KnownOne & KnownZero == 0. That is, a bit can't be both 1 and 0. Note that |
| /// the bits in KnownOne and KnownZero may only be accurate for those bits set |
| /// in DemandedMask. Note also that the bitwidth of V, DemandedMask, KnownZero |
| /// and KnownOne must all be the same. |
| bool InstCombiner::SimplifyDemandedBits(Value *V, APInt DemandedMask, |
| APInt& KnownZero, APInt& KnownOne, |
| unsigned Depth) { |
| assert(V != 0 && "Null pointer of Value???"); |
| assert(Depth <= 6 && "Limit Search Depth"); |
| uint32_t BitWidth = DemandedMask.getBitWidth(); |
| const IntegerType *VTy = cast<IntegerType>(V->getType()); |
| assert(VTy->getBitWidth() == BitWidth && |
| KnownZero.getBitWidth() == BitWidth && |
| KnownOne.getBitWidth() == BitWidth && |
| "Value *V, DemandedMask, KnownZero and KnownOne \ |
| must have same BitWidth"); |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) { |
| // We know all of the bits for a constant! |
| KnownOne = CI->getValue() & DemandedMask; |
| KnownZero = ~KnownOne & DemandedMask; |
| return false; |
| } |
| |
| KnownZero.clear(); |
| KnownOne.clear(); |
| if (!V->hasOneUse()) { // Other users may use these bits. |
| if (Depth != 0) { // Not at the root. |
| // Just compute the KnownZero/KnownOne bits to simplify things downstream. |
| ComputeMaskedBits(V, DemandedMask, KnownZero, KnownOne, Depth); |
| return false; |
| } |
| // If this is the root being simplified, allow it to have multiple uses, |
| // just set the DemandedMask to all bits. |
| DemandedMask = APInt::getAllOnesValue(BitWidth); |
| } else if (DemandedMask == 0) { // Not demanding any bits from V. |
| if (V != UndefValue::get(VTy)) |
| return UpdateValueUsesWith(V, UndefValue::get(VTy)); |
| return false; |
| } else if (Depth == 6) { // Limit search depth. |
| return false; |
| } |
| |
| Instruction *I = dyn_cast<Instruction>(V); |
| if (!I) return false; // Only analyze instructions. |
| |
| APInt LHSKnownZero(BitWidth, 0), LHSKnownOne(BitWidth, 0); |
| APInt &RHSKnownZero = KnownZero, &RHSKnownOne = KnownOne; |
| switch (I->getOpcode()) { |
| default: |
| ComputeMaskedBits(V, DemandedMask, RHSKnownZero, RHSKnownOne, Depth); |
| break; |
| case Instruction::And: |
| // If either the LHS or the RHS are Zero, the result is zero. |
| if (SimplifyDemandedBits(I->getOperand(1), DemandedMask, |
| RHSKnownZero, RHSKnownOne, Depth+1)) |
| return true; |
| assert((RHSKnownZero & RHSKnownOne) == 0 && |
| "Bits known to be one AND zero?"); |
| |
| // If something is known zero on the RHS, the bits aren't demanded on the |
| // LHS. |
| if (SimplifyDemandedBits(I->getOperand(0), DemandedMask & ~RHSKnownZero, |
| LHSKnownZero, LHSKnownOne, Depth+1)) |
| return true; |
| assert((LHSKnownZero & LHSKnownOne) == 0 && |
| "Bits known to be one AND zero?"); |
| |
| // If all of the demanded bits are known 1 on one side, return the other. |
| // These bits cannot contribute to the result of the 'and'. |
| if ((DemandedMask & ~LHSKnownZero & RHSKnownOne) == |
| (DemandedMask & ~LHSKnownZero)) |
| return UpdateValueUsesWith(I, I->getOperand(0)); |
| if ((DemandedMask & ~RHSKnownZero & LHSKnownOne) == |
| (DemandedMask & ~RHSKnownZero)) |
| return UpdateValueUsesWith(I, I->getOperand(1)); |
| |
| // If all of the demanded bits in the inputs are known zeros, return zero. |
| if ((DemandedMask & (RHSKnownZero|LHSKnownZero)) == DemandedMask) |
| return UpdateValueUsesWith(I, Constant::getNullValue(VTy)); |
| |
| // If the RHS is a constant, see if we can simplify it. |
| if (ShrinkDemandedConstant(I, 1, DemandedMask & ~LHSKnownZero)) |
| return UpdateValueUsesWith(I, I); |
| |
| // Output known-1 bits are only known if set in both the LHS & RHS. |
| RHSKnownOne &= LHSKnownOne; |
| // Output known-0 are known to be clear if zero in either the LHS | RHS. |
| RHSKnownZero |= LHSKnownZero; |
| break; |
| case Instruction::Or: |
| // If either the LHS or the RHS are One, the result is One. |
| if (SimplifyDemandedBits(I->getOperand(1), DemandedMask, |
| RHSKnownZero, RHSKnownOne, Depth+1)) |
| return true; |
| assert((RHSKnownZero & RHSKnownOne) == 0 && |
| "Bits known to be one AND zero?"); |
| // If something is known one on the RHS, the bits aren't demanded on the |
| // LHS. |
| if (SimplifyDemandedBits(I->getOperand(0), DemandedMask & ~RHSKnownOne, |
| LHSKnownZero, LHSKnownOne, Depth+1)) |
| return true; |
| assert((LHSKnownZero & LHSKnownOne) == 0 && |
| "Bits known to be one AND zero?"); |
| |
| // If all of the demanded bits are known zero on one side, return the other. |
| // These bits cannot contribute to the result of the 'or'. |
| if ((DemandedMask & ~LHSKnownOne & RHSKnownZero) == |
| (DemandedMask & ~LHSKnownOne)) |
| return UpdateValueUsesWith(I, I->getOperand(0)); |
| if ((DemandedMask & ~RHSKnownOne & LHSKnownZero) == |
| (DemandedMask & ~RHSKnownOne)) |
| return UpdateValueUsesWith(I, I->getOperand(1)); |
| |
| // If all of the potentially set bits on one side are known to be set on |
| // the other side, just use the 'other' side. |
| if ((DemandedMask & (~RHSKnownZero) & LHSKnownOne) == |
| (DemandedMask & (~RHSKnownZero))) |
| return UpdateValueUsesWith(I, I->getOperand(0)); |
| if ((DemandedMask & (~LHSKnownZero) & RHSKnownOne) == |
| (DemandedMask & (~LHSKnownZero))) |
| return UpdateValueUsesWith(I, I->getOperand(1)); |
| |
| // If the RHS is a constant, see if we can simplify it. |
| if (ShrinkDemandedConstant(I, 1, DemandedMask)) |
| return UpdateValueUsesWith(I, I); |
| |
| // Output known-0 bits are only known if clear in both the LHS & RHS. |
| RHSKnownZero &= LHSKnownZero; |
| // Output known-1 are known to be set if set in either the LHS | RHS. |
| RHSKnownOne |= LHSKnownOne; |
| break; |
| case Instruction::Xor: { |
| if (SimplifyDemandedBits(I->getOperand(1), DemandedMask, |
| RHSKnownZero, RHSKnownOne, Depth+1)) |
| return true; |
| assert((RHSKnownZero & RHSKnownOne) == 0 && |
| "Bits known to be one AND zero?"); |
| if (SimplifyDemandedBits(I->getOperand(0), DemandedMask, |
| LHSKnownZero, LHSKnownOne, Depth+1)) |
| return true; |
| assert((LHSKnownZero & LHSKnownOne) == 0 && |
| "Bits known to be one AND zero?"); |
| |
| // If all of the demanded bits are known zero on one side, return the other. |
| // These bits cannot contribute to the result of the 'xor'. |
| if ((DemandedMask & RHSKnownZero) == DemandedMask) |
| return UpdateValueUsesWith(I, I->getOperand(0)); |
| if ((DemandedMask & LHSKnownZero) == DemandedMask) |
| return UpdateValueUsesWith(I, I->getOperand(1)); |
| |
| // Output known-0 bits are known if clear or set in both the LHS & RHS. |
| APInt KnownZeroOut = (RHSKnownZero & LHSKnownZero) | |
| (RHSKnownOne & LHSKnownOne); |
| // Output known-1 are known to be set if set in only one of the LHS, RHS. |
| APInt KnownOneOut = (RHSKnownZero & LHSKnownOne) | |
| (RHSKnownOne & LHSKnownZero); |
| |
| // If all of the demanded bits are known to be zero on one side or the |
| // other, turn this into an *inclusive* or. |
| // e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0 |
| if ((DemandedMask & ~RHSKnownZero & ~LHSKnownZero) == 0) { |
| Instruction *Or = |
| BinaryOperator::CreateOr(I->getOperand(0), I->getOperand(1), |
| I->getName()); |
| InsertNewInstBefore(Or, *I); |
| return UpdateValueUsesWith(I, Or); |
| } |
| |
| // If all of the demanded bits on one side are known, and all of the set |
| // bits on that side are also known to be set on the other side, turn this |
| // into an AND, as we know the bits will be cleared. |
| // e.g. (X | C1) ^ C2 --> (X | C1) & ~C2 iff (C1&C2) == C2 |
| if ((DemandedMask & (RHSKnownZero|RHSKnownOne)) == DemandedMask) { |
| // all known |
| if ((RHSKnownOne & LHSKnownOne) == RHSKnownOne) { |
| Constant *AndC = ConstantInt::get(~RHSKnownOne & DemandedMask); |
| Instruction *And = |
| BinaryOperator::CreateAnd(I->getOperand(0), AndC, "tmp"); |
| InsertNewInstBefore(And, *I); |
| return UpdateValueUsesWith(I, And); |
| } |
| } |
| |
| // If the RHS is a constant, see if we can simplify it. |
| // FIXME: for XOR, we prefer to force bits to 1 if they will make a -1. |
| if (ShrinkDemandedConstant(I, 1, DemandedMask)) |
| return UpdateValueUsesWith(I, I); |
| |
| RHSKnownZero = KnownZeroOut; |
| RHSKnownOne = KnownOneOut; |
| break; |
| } |
| case Instruction::Select: |
| if (SimplifyDemandedBits(I->getOperand(2), DemandedMask, |
| RHSKnownZero, RHSKnownOne, Depth+1)) |
| return true; |
| if (SimplifyDemandedBits(I->getOperand(1), DemandedMask, |
| LHSKnownZero, LHSKnownOne, Depth+1)) |
| return true; |
| assert((RHSKnownZero & RHSKnownOne) == 0 && |
| "Bits known to be one AND zero?"); |
| assert((LHSKnownZero & LHSKnownOne) == 0 && |
| "Bits known to be one AND zero?"); |
| |
| // If the operands are constants, see if we can simplify them. |
| if (ShrinkDemandedConstant(I, 1, DemandedMask)) |
| return UpdateValueUsesWith(I, I); |
| if (ShrinkDemandedConstant(I, 2, DemandedMask)) |
| return UpdateValueUsesWith(I, I); |
| |
| // Only known if known in both the LHS and RHS. |
| RHSKnownOne &= LHSKnownOne; |
| RHSKnownZero &= LHSKnownZero; |
| break; |
| case Instruction::Trunc: { |
| uint32_t truncBf = |
| cast<IntegerType>(I->getOperand(0)->getType())->getBitWidth(); |
| DemandedMask.zext(truncBf); |
| RHSKnownZero.zext(truncBf); |
| RHSKnownOne.zext(truncBf); |
| if (SimplifyDemandedBits(I->getOperand(0), DemandedMask, |
| RHSKnownZero, RHSKnownOne, Depth+1)) |
| return true; |
| DemandedMask.trunc(BitWidth); |
| RHSKnownZero.trunc(BitWidth); |
| RHSKnownOne.trunc(BitWidth); |
| assert((RHSKnownZero & RHSKnownOne) == 0 && |
| "Bits known to be one AND zero?"); |
| break; |
| } |
| case Instruction::BitCast: |
| if (!I->getOperand(0)->getType()->isInteger()) |
| return false; |
| |
| if (SimplifyDemandedBits(I->getOperand(0), DemandedMask, |
| RHSKnownZero, RHSKnownOne, Depth+1)) |
| return true; |
| assert((RHSKnownZero & RHSKnownOne) == 0 && |
| "Bits known to be one AND zero?"); |
| break; |
| case Instruction::ZExt: { |
| // Compute the bits in the result that are not present in the input. |
| const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType()); |
| uint32_t SrcBitWidth = SrcTy->getBitWidth(); |
| |
| DemandedMask.trunc(SrcBitWidth); |
| RHSKnownZero.trunc(SrcBitWidth); |
| RHSKnownOne.trunc(SrcBitWidth); |
| if (SimplifyDemandedBits(I->getOperand(0), DemandedMask, |
| RHSKnownZero, RHSKnownOne, Depth+1)) |
| return true; |
| DemandedMask.zext(BitWidth); |
| RHSKnownZero.zext(BitWidth); |
| RHSKnownOne.zext(BitWidth); |
| assert((RHSKnownZero & RHSKnownOne) == 0 && |
| "Bits known to be one AND zero?"); |
| // The top bits are known to be zero. |
| RHSKnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth); |
| break; |
| } |
| case Instruction::SExt: { |
| // Compute the bits in the result that are not present in the input. |
| const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType()); |
| uint32_t SrcBitWidth = SrcTy->getBitWidth(); |
| |
| APInt InputDemandedBits = DemandedMask & |
| APInt::getLowBitsSet(BitWidth, SrcBitWidth); |
| |
| APInt NewBits(APInt::getHighBitsSet(BitWidth, BitWidth - SrcBitWidth)); |
| // If any of the sign extended bits are demanded, we know that the sign |
| // bit is demanded. |
| if ((NewBits & DemandedMask) != 0) |
| InputDemandedBits.set(SrcBitWidth-1); |
| |
| InputDemandedBits.trunc(SrcBitWidth); |
| RHSKnownZero.trunc(SrcBitWidth); |
| RHSKnownOne.trunc(SrcBitWidth); |
| if (SimplifyDemandedBits(I->getOperand(0), InputDemandedBits, |
| RHSKnownZero, RHSKnownOne, Depth+1)) |
| return true; |
| InputDemandedBits.zext(BitWidth); |
| RHSKnownZero.zext(BitWidth); |
| RHSKnownOne.zext(BitWidth); |
| assert((RHSKnownZero & RHSKnownOne) == 0 && |
| "Bits known to be one AND zero?"); |
| |
| // If the sign bit of the input is known set or clear, then we know the |
| // top bits of the result. |
| |
| // If the input sign bit is known zero, or if the NewBits are not demanded |
| // convert this into a zero extension. |
| if (RHSKnownZero[SrcBitWidth-1] || (NewBits & ~DemandedMask) == NewBits) |
| { |
| // Convert to ZExt cast |
| CastInst *NewCast = new ZExtInst(I->getOperand(0), VTy, I->getName(), I); |
| return UpdateValueUsesWith(I, NewCast); |
| } else if (RHSKnownOne[SrcBitWidth-1]) { // Input sign bit known set |
| RHSKnownOne |= NewBits; |
| } |
| break; |
| } |
| case Instruction::Add: { |
| // Figure out what the input bits are. If the top bits of the and result |
| // are not demanded, then the add doesn't demand them from its input |
| // either. |
| uint32_t NLZ = DemandedMask.countLeadingZeros(); |
| |
| // If there is a constant on the RHS, there are a variety of xformations |
| // we can do. |
| if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| // If null, this should be simplified elsewhere. Some of the xforms here |
| // won't work if the RHS is zero. |
| if (RHS->isZero()) |
| break; |
| |
| // If the top bit of the output is demanded, demand everything from the |
| // input. Otherwise, we demand all the input bits except NLZ top bits. |
| APInt InDemandedBits(APInt::getLowBitsSet(BitWidth, BitWidth - NLZ)); |
| |
| // Find information about known zero/one bits in the input. |
| if (SimplifyDemandedBits(I->getOperand(0), InDemandedBits, |
| LHSKnownZero, LHSKnownOne, Depth+1)) |
| return true; |
| |
| // If the RHS of the add has bits set that can't affect the input, reduce |
| // the constant. |
| if (ShrinkDemandedConstant(I, 1, InDemandedBits)) |
| return UpdateValueUsesWith(I, I); |
| |
| // Avoid excess work. |
| if (LHSKnownZero == 0 && LHSKnownOne == 0) |
| break; |
| |
| // Turn it into OR if input bits are zero. |
| if ((LHSKnownZero & RHS->getValue()) == RHS->getValue()) { |
| Instruction *Or = |
| BinaryOperator::CreateOr(I->getOperand(0), I->getOperand(1), |
| I->getName()); |
| InsertNewInstBefore(Or, *I); |
| return UpdateValueUsesWith(I, Or); |
| } |
| |
| // We can say something about the output known-zero and known-one bits, |
| // depending on potential carries from the input constant and the |
| // unknowns. For example if the LHS is known to have at most the 0x0F0F0 |
| // bits set and the RHS constant is 0x01001, then we know we have a known |
| // one mask of 0x00001 and a known zero mask of 0xE0F0E. |
| |
| // To compute this, we first compute the potential carry bits. These are |
| // the bits which may be modified. I'm not aware of a better way to do |
| // this scan. |
| const APInt& RHSVal = RHS->getValue(); |
| APInt CarryBits((~LHSKnownZero + RHSVal) ^ (~LHSKnownZero ^ RHSVal)); |
| |
| // Now that we know which bits have carries, compute the known-1/0 sets. |
| |
| // Bits are known one if they are known zero in one operand and one in the |
| // other, and there is no input carry. |
| RHSKnownOne = ((LHSKnownZero & RHSVal) | |
| (LHSKnownOne & ~RHSVal)) & ~CarryBits; |
| |
| // Bits are known zero if they are known zero in both operands and there |
| // is no input carry. |
| RHSKnownZero = LHSKnownZero & ~RHSVal & ~CarryBits; |
| } else { |
| // If the high-bits of this ADD are not demanded, then it does not demand |
| // the high bits of its LHS or RHS. |
| if (DemandedMask[BitWidth-1] == 0) { |
| // Right fill the mask of bits for this ADD to demand the most |
| // significant bit and all those below it. |
| APInt DemandedFromOps(APInt::getLowBitsSet(BitWidth, BitWidth-NLZ)); |
| if (SimplifyDemandedBits(I->getOperand(0), DemandedFromOps, |
| LHSKnownZero, LHSKnownOne, Depth+1)) |
| return true; |
| if (SimplifyDemandedBits(I->getOperand(1), DemandedFromOps, |
| LHSKnownZero, LHSKnownOne, Depth+1)) |
| return true; |
| } |
| } |
| break; |
| } |
| case Instruction::Sub: |
| // If the high-bits of this SUB are not demanded, then it does not demand |
| // the high bits of its LHS or RHS. |
| if (DemandedMask[BitWidth-1] == 0) { |
| // Right fill the mask of bits for this SUB to demand the most |
| // significant bit and all those below it. |
| uint32_t NLZ = DemandedMask.countLeadingZeros(); |
| APInt DemandedFromOps(APInt::getLowBitsSet(BitWidth, BitWidth-NLZ)); |
| if (SimplifyDemandedBits(I->getOperand(0), DemandedFromOps, |
| LHSKnownZero, LHSKnownOne, Depth+1)) |
| return true; |
| if (SimplifyDemandedBits(I->getOperand(1), DemandedFromOps, |
| LHSKnownZero, LHSKnownOne, Depth+1)) |
| return true; |
| } |
| // Otherwise just hand the sub off to ComputeMaskedBits to fill in |
| // the known zeros and ones. |
| ComputeMaskedBits(V, DemandedMask, RHSKnownZero, RHSKnownOne, Depth); |
| break; |
| case Instruction::Shl: |
| if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| uint64_t ShiftAmt = SA->getLimitedValue(BitWidth); |
| APInt DemandedMaskIn(DemandedMask.lshr(ShiftAmt)); |
| if (SimplifyDemandedBits(I->getOperand(0), DemandedMaskIn, |
| RHSKnownZero, RHSKnownOne, Depth+1)) |
| return true; |
| assert((RHSKnownZero & RHSKnownOne) == 0 && |
| "Bits known to be one AND zero?"); |
| RHSKnownZero <<= ShiftAmt; |
| RHSKnownOne <<= ShiftAmt; |
| // low bits known zero. |
| if (ShiftAmt) |
| RHSKnownZero |= APInt::getLowBitsSet(BitWidth, ShiftAmt); |
| } |
| break; |
| case Instruction::LShr: |
| // For a logical shift right |
| if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| uint64_t ShiftAmt = SA->getLimitedValue(BitWidth); |
| |
| // Unsigned shift right. |
| APInt DemandedMaskIn(DemandedMask.shl(ShiftAmt)); |
| if (SimplifyDemandedBits(I->getOperand(0), DemandedMaskIn, |
| RHSKnownZero, RHSKnownOne, Depth+1)) |
| return true; |
| assert((RHSKnownZero & RHSKnownOne) == 0 && |
| "Bits known to be one AND zero?"); |
| RHSKnownZero = APIntOps::lshr(RHSKnownZero, ShiftAmt); |
| RHSKnownOne = APIntOps::lshr(RHSKnownOne, ShiftAmt); |
| if (ShiftAmt) { |
| // Compute the new bits that are at the top now. |
| APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt)); |
| RHSKnownZero |= HighBits; // high bits known zero. |
| } |
| } |
| break; |
| case Instruction::AShr: |
| // If this is an arithmetic shift right and only the low-bit is set, we can |
| // always convert this into a logical shr, even if the shift amount is |
| // variable. The low bit of the shift cannot be an input sign bit unless |
| // the shift amount is >= the size of the datatype, which is undefined. |
| if (DemandedMask == 1) { |
| // Perform the logical shift right. |
| Value *NewVal = BinaryOperator::CreateLShr( |
| I->getOperand(0), I->getOperand(1), I->getName()); |
| InsertNewInstBefore(cast<Instruction>(NewVal), *I); |
| return UpdateValueUsesWith(I, NewVal); |
| } |
| |
| // If the sign bit is the only bit demanded by this ashr, then there is no |
| // need to do it, the shift doesn't change the high bit. |
| if (DemandedMask.isSignBit()) |
| return UpdateValueUsesWith(I, I->getOperand(0)); |
| |
| if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| uint32_t ShiftAmt = SA->getLimitedValue(BitWidth); |
| |
| // Signed shift right. |
| APInt DemandedMaskIn(DemandedMask.shl(ShiftAmt)); |
| // If any of the "high bits" are demanded, we should set the sign bit as |
| // demanded. |
| if (DemandedMask.countLeadingZeros() <= ShiftAmt) |
| DemandedMaskIn.set(BitWidth-1); |
| if (SimplifyDemandedBits(I->getOperand(0), |
| DemandedMaskIn, |
| RHSKnownZero, RHSKnownOne, Depth+1)) |
| return true; |
| assert((RHSKnownZero & RHSKnownOne) == 0 && |
| "Bits known to be one AND zero?"); |
| // Compute the new bits that are at the top now. |
| APInt HighBits(APInt::getHighBitsSet(BitWidth, ShiftAmt)); |
| RHSKnownZero = APIntOps::lshr(RHSKnownZero, ShiftAmt); |
| RHSKnownOne = APIntOps::lshr(RHSKnownOne, ShiftAmt); |
| |
| // Handle the sign bits. |
| APInt SignBit(APInt::getSignBit(BitWidth)); |
| // Adjust to where it is now in the mask. |
| SignBit = APIntOps::lshr(SignBit, ShiftAmt); |
| |
| // If the input sign bit is known to be zero, or if none of the top bits |
| // are demanded, turn this into an unsigned shift right. |
| if (BitWidth <= ShiftAmt || RHSKnownZero[BitWidth-ShiftAmt-1] || |
| (HighBits & ~DemandedMask) == HighBits) { |
| // Perform the logical shift right. |
| Value *NewVal = BinaryOperator::CreateLShr( |
| I->getOperand(0), SA, I->getName()); |
| InsertNewInstBefore(cast<Instruction>(NewVal), *I); |
| return UpdateValueUsesWith(I, NewVal); |
| } else if ((RHSKnownOne & SignBit) != 0) { // New bits are known one. |
| RHSKnownOne |= HighBits; |
| } |
| } |
| break; |
| case Instruction::SRem: |
| if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| APInt RA = Rem->getValue().abs(); |
| if (RA.isPowerOf2()) { |
| if (DemandedMask.ule(RA)) // srem won't affect demanded bits |
| return UpdateValueUsesWith(I, I->getOperand(0)); |
| |
| APInt LowBits = RA - 1; |
| APInt Mask2 = LowBits | APInt::getSignBit(BitWidth); |
| if (SimplifyDemandedBits(I->getOperand(0), Mask2, |
| LHSKnownZero, LHSKnownOne, Depth+1)) |
| return true; |
| |
| if (LHSKnownZero[BitWidth-1] || ((LHSKnownZero & LowBits) == LowBits)) |
| LHSKnownZero |= ~LowBits; |
| |
| KnownZero |= LHSKnownZero & DemandedMask; |
| |
| assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?"); |
| } |
| } |
| break; |
| case Instruction::URem: { |
| APInt KnownZero2(BitWidth, 0), KnownOne2(BitWidth, 0); |
| APInt AllOnes = APInt::getAllOnesValue(BitWidth); |
| if (SimplifyDemandedBits(I->getOperand(0), AllOnes, |
| KnownZero2, KnownOne2, Depth+1)) |
| return true; |
| |
| uint32_t Leaders = KnownZero2.countLeadingOnes(); |
| if (SimplifyDemandedBits(I->getOperand(1), AllOnes, |
| KnownZero2, KnownOne2, Depth+1)) |
| return true; |
| |
| Leaders = std::max(Leaders, |
| KnownZero2.countLeadingOnes()); |
| KnownZero = APInt::getHighBitsSet(BitWidth, Leaders) & DemandedMask; |
| break; |
| } |
| case Instruction::Call: |
| if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) { |
| switch (II->getIntrinsicID()) { |
| default: break; |
| case Intrinsic::bswap: { |
| // If the only bits demanded come from one byte of the bswap result, |
| // just shift the input byte into position to eliminate the bswap. |
| unsigned NLZ = DemandedMask.countLeadingZeros(); |
| unsigned NTZ = DemandedMask.countTrailingZeros(); |
| |
| // Round NTZ down to the next byte. If we have 11 trailing zeros, then |
| // we need all the bits down to bit 8. Likewise, round NLZ. If we |
| // have 14 leading zeros, round to 8. |
| NLZ &= ~7; |
| NTZ &= ~7; |
| // If we need exactly one byte, we can do this transformation. |
| if (BitWidth-NLZ-NTZ == 8) { |
| unsigned ResultBit = NTZ; |
| unsigned InputBit = BitWidth-NTZ-8; |
| |
| // Replace this with either a left or right shift to get the byte into |
| // the right place. |
| Instruction *NewVal; |
| if (InputBit > ResultBit) |
| NewVal = BinaryOperator::CreateLShr(I->getOperand(1), |
| ConstantInt::get(I->getType(), InputBit-ResultBit)); |
| else |
| NewVal = BinaryOperator::CreateShl(I->getOperand(1), |
| ConstantInt::get(I->getType(), ResultBit-InputBit)); |
| NewVal->takeName(I); |
| InsertNewInstBefore(NewVal, *I); |
| return UpdateValueUsesWith(I, NewVal); |
| } |
| |
| // TODO: Could compute known zero/one bits based on the input. |
| break; |
| } |
| } |
| } |
| ComputeMaskedBits(V, DemandedMask, RHSKnownZero, RHSKnownOne, Depth); |
| break; |
| } |
| |
| // If the client is only demanding bits that we know, return the known |
| // constant. |
| if ((DemandedMask & (RHSKnownZero|RHSKnownOne)) == DemandedMask) |
| return UpdateValueUsesWith(I, ConstantInt::get(RHSKnownOne)); |
| return false; |
| } |
| |
| |
| /// SimplifyDemandedVectorElts - The specified value produces a vector with |
| /// 64 or fewer elements. DemandedElts contains the set of elements that are |
| /// actually used by the caller. This method analyzes which elements of the |
| /// operand are undef and returns that information in UndefElts. |
| /// |
| /// If the information about demanded elements can be used to simplify the |
| /// operation, the operation is simplified, then the resultant value is |
| /// returned. This returns null if no change was made. |
| Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, uint64_t DemandedElts, |
| uint64_t &UndefElts, |
| unsigned Depth) { |
| unsigned VWidth = cast<VectorType>(V->getType())->getNumElements(); |
| assert(VWidth <= 64 && "Vector too wide to analyze!"); |
| uint64_t EltMask = ~0ULL >> (64-VWidth); |
| assert((DemandedElts & ~EltMask) == 0 && "Invalid DemandedElts!"); |
| |
| if (isa<UndefValue>(V)) { |
| // If the entire vector is undefined, just return this info. |
| UndefElts = EltMask; |
| return 0; |
| } else if (DemandedElts == 0) { // If nothing is demanded, provide undef. |
| UndefElts = EltMask; |
| return UndefValue::get(V->getType()); |
| } |
| |
| UndefElts = 0; |
| if (ConstantVector *CP = dyn_cast<ConstantVector>(V)) { |
| const Type *EltTy = cast<VectorType>(V->getType())->getElementType(); |
| Constant *Undef = UndefValue::get(EltTy); |
| |
| std::vector<Constant*> Elts; |
| for (unsigned i = 0; i != VWidth; ++i) |
| if (!(DemandedElts & (1ULL << i))) { // If not demanded, set to undef. |
| Elts.push_back(Undef); |
| UndefElts |= (1ULL << i); |
| } else if (isa<UndefValue>(CP->getOperand(i))) { // Already undef. |
| Elts.push_back(Undef); |
| UndefElts |= (1ULL << i); |
| } else { // Otherwise, defined. |
| Elts.push_back(CP->getOperand(i)); |
| } |
| |
| // If we changed the constant, return it. |
| Constant *NewCP = ConstantVector::get(Elts); |
| return NewCP != CP ? NewCP : 0; |
| } else if (isa<ConstantAggregateZero>(V)) { |
| // Simplify the CAZ to a ConstantVector where the non-demanded elements are |
| // set to undef. |
| |
| // Check if this is identity. If so, return 0 since we are not simplifying |
| // anything. |
| if (DemandedElts == ((1ULL << VWidth) -1)) |
| return 0; |
| |
| const Type *EltTy = cast<VectorType>(V->getType())->getElementType(); |
| Constant *Zero = Constant::getNullValue(EltTy); |
| Constant *Undef = UndefValue::get(EltTy); |
| std::vector<Constant*> Elts; |
| for (unsigned i = 0; i != VWidth; ++i) |
| Elts.push_back((DemandedElts & (1ULL << i)) ? Zero : Undef); |
| UndefElts = DemandedElts ^ EltMask; |
| return ConstantVector::get(Elts); |
| } |
| |
| // Limit search depth. |
| if (Depth == 10) |
| return false; |
| |
| // If multiple users are using the root value, procede with |
| // simplification conservatively assuming that all elements |
| // are needed. |
| if (!V->hasOneUse()) { |
| // Quit if we find multiple users of a non-root value though. |
| // They'll be handled when it's their turn to be visited by |
| // the main instcombine process. |
| if (Depth != 0) |
| // TODO: Just compute the UndefElts information recursively. |
| return false; |
| |
| // Conservatively assume that all elements are needed. |
| DemandedElts = EltMask; |
| } |
| |
| Instruction *I = dyn_cast<Instruction>(V); |
| if (!I) return false; // Only analyze instructions. |
| |
| bool MadeChange = false; |
| uint64_t UndefElts2; |
| Value *TmpV; |
| switch (I->getOpcode()) { |
| default: break; |
| |
| case Instruction::InsertElement: { |
| // If this is a variable index, we don't know which element it overwrites. |
| // demand exactly the same input as we produce. |
| ConstantInt *Idx = dyn_cast<ConstantInt>(I->getOperand(2)); |
| if (Idx == 0) { |
| // Note that we can't propagate undef elt info, because we don't know |
| // which elt is getting updated. |
| TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts, |
| UndefElts2, Depth+1); |
| if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; } |
| break; |
| } |
| |
| // If this is inserting an element that isn't demanded, remove this |
| // insertelement. |
| unsigned IdxNo = Idx->getZExtValue(); |
| if (IdxNo >= VWidth || (DemandedElts & (1ULL << IdxNo)) == 0) |
| return AddSoonDeadInstToWorklist(*I, 0); |
| |
| // Otherwise, the element inserted overwrites whatever was there, so the |
| // input demanded set is simpler than the output set. |
| TmpV = SimplifyDemandedVectorElts(I->getOperand(0), |
| DemandedElts & ~(1ULL << IdxNo), |
| UndefElts, Depth+1); |
| if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; } |
| |
| // The inserted element is defined. |
| UndefElts &= ~(1ULL << IdxNo); |
| break; |
| } |
| case Instruction::ShuffleVector: { |
| ShuffleVectorInst *Shuffle = cast<ShuffleVectorInst>(I); |
| uint64_t LHSVWidth = |
| cast<VectorType>(Shuffle->getOperand(0)->getType())->getNumElements(); |
| uint64_t LeftDemanded = 0, RightDemanded = 0; |
| for (unsigned i = 0; i < VWidth; i++) { |
| if (DemandedElts & (1ULL << i)) { |
| unsigned MaskVal = Shuffle->getMaskValue(i); |
| if (MaskVal != -1u) { |
| assert(MaskVal < LHSVWidth * 2 && |
| "shufflevector mask index out of range!"); |
| if (MaskVal < LHSVWidth) |
| LeftDemanded |= 1ULL << MaskVal; |
| else |
| RightDemanded |= 1ULL << (MaskVal - LHSVWidth); |
| } |
| } |
| } |
| |
| TmpV = SimplifyDemandedVectorElts(I->getOperand(0), LeftDemanded, |
| UndefElts2, Depth+1); |
| if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; } |
| |
| uint64_t UndefElts3; |
| TmpV = SimplifyDemandedVectorElts(I->getOperand(1), RightDemanded, |
| UndefElts3, Depth+1); |
| if (TmpV) { I->setOperand(1, TmpV); MadeChange = true; } |
| |
| bool NewUndefElts = false; |
| for (unsigned i = 0; i < VWidth; i++) { |
| unsigned MaskVal = Shuffle->getMaskValue(i); |
| if (MaskVal == -1u) { |
| uint64_t NewBit = 1ULL << i; |
| UndefElts |= NewBit; |
| } else if (MaskVal < LHSVWidth) { |
| uint64_t NewBit = ((UndefElts2 >> MaskVal) & 1) << i; |
| NewUndefElts |= NewBit; |
| UndefElts |= NewBit; |
| } else { |
| uint64_t NewBit = ((UndefElts3 >> (MaskVal - LHSVWidth)) & 1) << i; |
| NewUndefElts |= NewBit; |
| UndefElts |= NewBit; |
| } |
| } |
| |
| if (NewUndefElts) { |
| // Add additional discovered undefs. |
| std::vector<Constant*> Elts; |
| for (unsigned i = 0; i < VWidth; ++i) { |
| if (UndefElts & (1ULL << i)) |
| Elts.push_back(UndefValue::get(Type::Int32Ty)); |
| else |
| Elts.push_back(ConstantInt::get(Type::Int32Ty, |
| Shuffle->getMaskValue(i))); |
| } |
| I->setOperand(2, ConstantVector::get(Elts)); |
| MadeChange = true; |
| } |
| break; |
| } |
| case Instruction::BitCast: { |
| // Vector->vector casts only. |
| const VectorType *VTy = dyn_cast<VectorType>(I->getOperand(0)->getType()); |
| if (!VTy) break; |
| unsigned InVWidth = VTy->getNumElements(); |
| uint64_t InputDemandedElts = 0; |
| unsigned Ratio; |
| |
| if (VWidth == InVWidth) { |
| // If we are converting from <4 x i32> -> <4 x f32>, we demand the same |
| // elements as are demanded of us. |
| Ratio = 1; |
| InputDemandedElts = DemandedElts; |
| } else if (VWidth > InVWidth) { |
| // Untested so far. |
| break; |
| |
| // If there are more elements in the result than there are in the source, |
| // then an input element is live if any of the corresponding output |
| // elements are live. |
| Ratio = VWidth/InVWidth; |
| for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx) { |
| if (DemandedElts & (1ULL << OutIdx)) |
| InputDemandedElts |= 1ULL << (OutIdx/Ratio); |
| } |
| } else { |
| // Untested so far. |
| break; |
| |
| // If there are more elements in the source than there are in the result, |
| // then an input element is live if the corresponding output element is |
| // live. |
| Ratio = InVWidth/VWidth; |
| for (unsigned InIdx = 0; InIdx != InVWidth; ++InIdx) |
| if (DemandedElts & (1ULL << InIdx/Ratio)) |
| InputDemandedElts |= 1ULL << InIdx; |
| } |
| |
| // div/rem demand all inputs, because they don't want divide by zero. |
| TmpV = SimplifyDemandedVectorElts(I->getOperand(0), InputDemandedElts, |
| UndefElts2, Depth+1); |
| if (TmpV) { |
| I->setOperand(0, TmpV); |
| MadeChange = true; |
| } |
| |
| UndefElts = UndefElts2; |
| if (VWidth > InVWidth) { |
| assert(0 && "Unimp"); |
| // If there are more elements in the result than there are in the source, |
| // then an output element is undef if the corresponding input element is |
| // undef. |
| for (unsigned OutIdx = 0; OutIdx != VWidth; ++OutIdx) |
| if (UndefElts2 & (1ULL << (OutIdx/Ratio))) |
| UndefElts |= 1ULL << OutIdx; |
| } else if (VWidth < InVWidth) { |
| assert(0 && "Unimp"); |
| // If there are more elements in the source than there are in the result, |
| // then a result element is undef if all of the corresponding input |
| // elements are undef. |
| UndefElts = ~0ULL >> (64-VWidth); // Start out all undef. |
| for (unsigned InIdx = 0; InIdx != InVWidth; ++InIdx) |
| if ((UndefElts2 & (1ULL << InIdx)) == 0) // Not undef? |
| UndefElts &= ~(1ULL << (InIdx/Ratio)); // Clear undef bit. |
| } |
| break; |
| } |
| case Instruction::And: |
| case Instruction::Or: |
| case Instruction::Xor: |
| case Instruction::Add: |
| case Instruction::Sub: |
| case Instruction::Mul: |
| // div/rem demand all inputs, because they don't want divide by zero. |
| TmpV = SimplifyDemandedVectorElts(I->getOperand(0), DemandedElts, |
| UndefElts, Depth+1); |
| if (TmpV) { I->setOperand(0, TmpV); MadeChange = true; } |
| TmpV = SimplifyDemandedVectorElts(I->getOperand(1), DemandedElts, |
| UndefElts2, Depth+1); |
| if (TmpV) { I->setOperand(1, TmpV); MadeChange = true; } |
| |
| // Output elements are undefined if both are undefined. Consider things |
| // like undef&0. The result is known zero, not undef. |
| UndefElts &= UndefElts2; |
| break; |
| |
| case Instruction::Call: { |
| IntrinsicInst *II = dyn_cast<IntrinsicInst>(I); |
| if (!II) break; |
| switch (II->getIntrinsicID()) { |
| default: break; |
| |
| // Binary vector operations that work column-wise. A dest element is a |
| // function of the corresponding input elements from the two inputs. |
| case Intrinsic::x86_sse_sub_ss: |
| case Intrinsic::x86_sse_mul_ss: |
| case Intrinsic::x86_sse_min_ss: |
| case Intrinsic::x86_sse_max_ss: |
| case Intrinsic::x86_sse2_sub_sd: |
| case Intrinsic::x86_sse2_mul_sd: |
| case Intrinsic::x86_sse2_min_sd: |
| case Intrinsic::x86_sse2_max_sd: |
| TmpV = SimplifyDemandedVectorElts(II->getOperand(1), DemandedElts, |
| UndefElts, Depth+1); |
| if (TmpV) { II->setOperand(1, TmpV); MadeChange = true; } |
| TmpV = SimplifyDemandedVectorElts(II->getOperand(2), DemandedElts, |
| UndefElts2, Depth+1); |
| if (TmpV) { II->setOperand(2, TmpV); MadeChange = true; } |
| |
| // If only the low elt is demanded and this is a scalarizable intrinsic, |
| // scalarize it now. |
| if (DemandedElts == 1) { |
| switch (II->getIntrinsicID()) { |
| default: break; |
| case Intrinsic::x86_sse_sub_ss: |
| case Intrinsic::x86_sse_mul_ss: |
| case Intrinsic::x86_sse2_sub_sd: |
| case Intrinsic::x86_sse2_mul_sd: |
| // TODO: Lower MIN/MAX/ABS/etc |
| Value *LHS = II->getOperand(1); |
| Value *RHS = II->getOperand(2); |
| // Extract the element as scalars. |
| LHS = InsertNewInstBefore(new ExtractElementInst(LHS, 0U,"tmp"), *II); |
| RHS = InsertNewInstBefore(new ExtractElementInst(RHS, 0U,"tmp"), *II); |
| |
| switch (II->getIntrinsicID()) { |
| default: assert(0 && "Case stmts out of sync!"); |
| case Intrinsic::x86_sse_sub_ss: |
| case Intrinsic::x86_sse2_sub_sd: |
| TmpV = InsertNewInstBefore(BinaryOperator::CreateSub(LHS, RHS, |
| II->getName()), *II); |
| break; |
| case Intrinsic::x86_sse_mul_ss: |
| case Intrinsic::x86_sse2_mul_sd: |
| TmpV = InsertNewInstBefore(BinaryOperator::CreateMul(LHS, RHS, |
| II->getName()), *II); |
| break; |
| } |
| |
| Instruction *New = |
| InsertElementInst::Create(UndefValue::get(II->getType()), TmpV, 0U, |
| II->getName()); |
| InsertNewInstBefore(New, *II); |
| AddSoonDeadInstToWorklist(*II, 0); |
| return New; |
| } |
| } |
| |
| // Output elements are undefined if both are undefined. Consider things |
| // like undef&0. The result is known zero, not undef. |
| UndefElts &= UndefElts2; |
| break; |
| } |
| break; |
| } |
| } |
| return MadeChange ? I : 0; |
| } |
| |
| |
| /// AssociativeOpt - Perform an optimization on an associative operator. This |
| /// function is designed to check a chain of associative operators for a |
| /// potential to apply a certain optimization. Since the optimization may be |
| /// applicable if the expression was reassociated, this checks the chain, then |
| /// reassociates the expression as necessary to expose the optimization |
| /// opportunity. This makes use of a special Functor, which must define |
| /// 'shouldApply' and 'apply' methods. |
| /// |
| template<typename Functor> |
| static Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) { |
| unsigned Opcode = Root.getOpcode(); |
| Value *LHS = Root.getOperand(0); |
| |
| // Quick check, see if the immediate LHS matches... |
| if (F.shouldApply(LHS)) |
| return F.apply(Root); |
| |
| // Otherwise, if the LHS is not of the same opcode as the root, return. |
| Instruction *LHSI = dyn_cast<Instruction>(LHS); |
| while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) { |
| // Should we apply this transform to the RHS? |
| bool ShouldApply = F.shouldApply(LHSI->getOperand(1)); |
| |
| // If not to the RHS, check to see if we should apply to the LHS... |
| if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) { |
| cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS |
| ShouldApply = true; |
| } |
| |
| // If the functor wants to apply the optimization to the RHS of LHSI, |
| // reassociate the expression from ((? op A) op B) to (? op (A op B)) |
| if (ShouldApply) { |
| // Now all of the instructions are in the current basic block, go ahead |
| // and perform the reassociation. |
| Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0)); |
| |
| // First move the selected RHS to the LHS of the root... |
| Root.setOperand(0, LHSI->getOperand(1)); |
| |
| // Make what used to be the LHS of the root be the user of the root... |
| Value *ExtraOperand = TmpLHSI->getOperand(1); |
| if (&Root == TmpLHSI) { |
| Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType())); |
| return 0; |
| } |
| Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI |
| TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root |
| BasicBlock::iterator ARI = &Root; ++ARI; |
| TmpLHSI->moveBefore(ARI); // Move TmpLHSI to after Root |
| ARI = Root; |
| |
| // Now propagate the ExtraOperand down the chain of instructions until we |
| // get to LHSI. |
| while (TmpLHSI != LHSI) { |
| Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0)); |
| // Move the instruction to immediately before the chain we are |
| // constructing to avoid breaking dominance properties. |
| NextLHSI->moveBefore(ARI); |
| ARI = NextLHSI; |
| |
| Value *NextOp = NextLHSI->getOperand(1); |
| NextLHSI->setOperand(1, ExtraOperand); |
| TmpLHSI = NextLHSI; |
| ExtraOperand = NextOp; |
| } |
| |
| // Now that the instructions are reassociated, have the functor perform |
| // the transformation... |
| return F.apply(Root); |
| } |
| |
| LHSI = dyn_cast<Instruction>(LHSI->getOperand(0)); |
| } |
| return 0; |
| } |
| |
| namespace { |
| |
| // AddRHS - Implements: X + X --> X << 1 |
| struct AddRHS { |
| Value *RHS; |
| AddRHS(Value *rhs) : RHS(rhs) {} |
| bool shouldApply(Value *LHS) const { return LHS == RHS; } |
| Instruction *apply(BinaryOperator &Add) const { |
| return BinaryOperator::CreateShl(Add.getOperand(0), |
| ConstantInt::get(Add.getType(), 1)); |
| } |
| }; |
| |
| // AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2) |
| // iff C1&C2 == 0 |
| struct AddMaskingAnd { |
| Constant *C2; |
| AddMaskingAnd(Constant *c) : C2(c) {} |
| bool shouldApply(Value *LHS) const { |
| ConstantInt *C1; |
| return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) && |
| ConstantExpr::getAnd(C1, C2)->isNullValue(); |
| } |
| Instruction *apply(BinaryOperator &Add) const { |
| return BinaryOperator::CreateOr(Add.getOperand(0), Add.getOperand(1)); |
| } |
| }; |
| |
| } |
| |
| static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO, |
| InstCombiner *IC) { |
| if (CastInst *CI = dyn_cast<CastInst>(&I)) { |
| return IC->InsertCastBefore(CI->getOpcode(), SO, I.getType(), I); |
| } |
| |
| // Figure out if the constant is the left or the right argument. |
| bool ConstIsRHS = isa<Constant>(I.getOperand(1)); |
| Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS)); |
| |
| if (Constant *SOC = dyn_cast<Constant>(SO)) { |
| if (ConstIsRHS) |
| return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand); |
| return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC); |
| } |
| |
| Value *Op0 = SO, *Op1 = ConstOperand; |
| if (!ConstIsRHS) |
| std::swap(Op0, Op1); |
| Instruction *New; |
| if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I)) |
| New = BinaryOperator::Create(BO->getOpcode(), Op0, Op1,SO->getName()+".op"); |
| else if (CmpInst *CI = dyn_cast<CmpInst>(&I)) |
| New = CmpInst::Create(CI->getOpcode(), CI->getPredicate(), Op0, Op1, |
| SO->getName()+".cmp"); |
| else { |
| assert(0 && "Unknown binary instruction type!"); |
| abort(); |
| } |
| return IC->InsertNewInstBefore(New, I); |
| } |
| |
| // FoldOpIntoSelect - Given an instruction with a select as one operand and a |
| // constant as the other operand, try to fold the binary operator into the |
| // select arguments. This also works for Cast instructions, which obviously do |
| // not have a second operand. |
| static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI, |
| InstCombiner *IC) { |
| // Don't modify shared select instructions |
| if (!SI->hasOneUse()) return 0; |
| Value *TV = SI->getOperand(1); |
| Value *FV = SI->getOperand(2); |
| |
| if (isa<Constant>(TV) || isa<Constant>(FV)) { |
| // Bool selects with constant operands can be folded to logical ops. |
| if (SI->getType() == Type::Int1Ty) return 0; |
| |
| Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC); |
| Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC); |
| |
| return SelectInst::Create(SI->getCondition(), SelectTrueVal, |
| SelectFalseVal); |
| } |
| return 0; |
| } |
| |
| |
| /// FoldOpIntoPhi - Given a binary operator or cast instruction which has a PHI |
| /// node as operand #0, see if we can fold the instruction into the PHI (which |
| /// is only possible if all operands to the PHI are constants). |
| Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) { |
| PHINode *PN = cast<PHINode>(I.getOperand(0)); |
| unsigned NumPHIValues = PN->getNumIncomingValues(); |
| if (!PN->hasOneUse() || NumPHIValues == 0) return 0; |
| |
| // Check to see if all of the operands of the PHI are constants. If there is |
| // one non-constant value, remember the BB it is. If there is more than one |
| // or if *it* is a PHI, bail out. |
| BasicBlock *NonConstBB = 0; |
| for (unsigned i = 0; i != NumPHIValues; ++i) |
| if (!isa<Constant>(PN->getIncomingValue(i))) { |
| if (NonConstBB) return 0; // More than one non-const value. |
| if (isa<PHINode>(PN->getIncomingValue(i))) return 0; // Itself a phi. |
| NonConstBB = PN->getIncomingBlock(i); |
| |
| // If the incoming non-constant value is in I's block, we have an infinite |
| // loop. |
| if (NonConstBB == I.getParent()) |
| return 0; |
| } |
| |
| // If there is exactly one non-constant value, we can insert a copy of the |
| // operation in that block. However, if this is a critical edge, we would be |
| // inserting the computation one some other paths (e.g. inside a loop). Only |
| // do this if the pred block is unconditionally branching into the phi block. |
| if (NonConstBB) { |
| BranchInst *BI = dyn_cast<BranchInst>(NonConstBB->getTerminator()); |
| if (!BI || !BI->isUnconditional()) return 0; |
| } |
| |
| // Okay, we can do the transformation: create the new PHI node. |
| PHINode *NewPN = PHINode::Create(I.getType(), ""); |
| NewPN->reserveOperandSpace(PN->getNumOperands()/2); |
| InsertNewInstBefore(NewPN, *PN); |
| NewPN->takeName(PN); |
| |
| // Next, add all of the operands to the PHI. |
| if (I.getNumOperands() == 2) { |
| Constant *C = cast<Constant>(I.getOperand(1)); |
| for (unsigned i = 0; i != NumPHIValues; ++i) { |
| Value *InV = 0; |
| if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) { |
| if (CmpInst *CI = dyn_cast<CmpInst>(&I)) |
| InV = ConstantExpr::getCompare(CI->getPredicate(), InC, C); |
| else |
| InV = ConstantExpr::get(I.getOpcode(), InC, C); |
| } else { |
| assert(PN->getIncomingBlock(i) == NonConstBB); |
| if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I)) |
| InV = BinaryOperator::Create(BO->getOpcode(), |
| PN->getIncomingValue(i), C, "phitmp", |
| NonConstBB->getTerminator()); |
| else if (CmpInst *CI = dyn_cast<CmpInst>(&I)) |
| InV = CmpInst::Create(CI->getOpcode(), |
| CI->getPredicate(), |
| PN->getIncomingValue(i), C, "phitmp", |
| NonConstBB->getTerminator()); |
| else |
| assert(0 && "Unknown binop!"); |
| |
| AddToWorkList(cast<Instruction>(InV)); |
| } |
| NewPN->addIncoming(InV, PN->getIncomingBlock(i)); |
| } |
| } else { |
| CastInst *CI = cast<CastInst>(&I); |
| const Type *RetTy = CI->getType(); |
| for (unsigned i = 0; i != NumPHIValues; ++i) { |
| Value *InV; |
| if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) { |
| InV = ConstantExpr::getCast(CI->getOpcode(), InC, RetTy); |
| } else { |
| assert(PN->getIncomingBlock(i) == NonConstBB); |
| InV = CastInst::Create(CI->getOpcode(), PN->getIncomingValue(i), |
| I.getType(), "phitmp", |
| NonConstBB->getTerminator()); |
| AddToWorkList(cast<Instruction>(InV)); |
| } |
| NewPN->addIncoming(InV, PN->getIncomingBlock(i)); |
| } |
| } |
| return ReplaceInstUsesWith(I, NewPN); |
| } |
| |
| |
| /// WillNotOverflowSignedAdd - Return true if we can prove that: |
| /// (sext (add LHS, RHS)) === (add (sext LHS), (sext RHS)) |
| /// This basically requires proving that the add in the original type would not |
| /// overflow to change the sign bit or have a carry out. |
| bool InstCombiner::WillNotOverflowSignedAdd(Value *LHS, Value *RHS) { |
| // There are different heuristics we can use for this. Here are some simple |
| // ones. |
| |
| // Add has the property that adding any two 2's complement numbers can only |
| // have one carry bit which can change a sign. As such, if LHS and RHS each |
| // have at least two sign bits, we know that the addition of the two values will |
| // sign extend fine. |
| if (ComputeNumSignBits(LHS) > 1 && ComputeNumSignBits(RHS) > 1) |
| return true; |
| |
| |
| // If one of the operands only has one non-zero bit, and if the other operand |
| // has a known-zero bit in a more significant place than it (not including the |
| // sign bit) the ripple may go up to and fill the zero, but won't change the |
| // sign. For example, (X & ~4) + 1. |
| |
| // TODO: Implement. |
| |
| return false; |
| } |
| |
| |
| Instruction *InstCombiner::visitAdd(BinaryOperator &I) { |
| bool Changed = SimplifyCommutative(I); |
| Value *LHS = I.getOperand(0), *RHS = I.getOperand(1); |
| |
| if (Constant *RHSC = dyn_cast<Constant>(RHS)) { |
| // X + undef -> undef |
| if (isa<UndefValue>(RHS)) |
| return ReplaceInstUsesWith(I, RHS); |
| |
| // X + 0 --> X |
| if (!I.getType()->isFPOrFPVector()) { // NOTE: -0 + +0 = +0. |
| if (RHSC->isNullValue()) |
| return ReplaceInstUsesWith(I, LHS); |
| } else if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) { |
| if (CFP->isExactlyValue(ConstantFP::getNegativeZero |
| (I.getType())->getValueAPF())) |
| return ReplaceInstUsesWith(I, LHS); |
| } |
| |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) { |
| // X + (signbit) --> X ^ signbit |
| const APInt& Val = CI->getValue(); |
| uint32_t BitWidth = Val.getBitWidth(); |
| if (Val == APInt::getSignBit(BitWidth)) |
| return BinaryOperator::CreateXor(LHS, RHS); |
| |
| // See if SimplifyDemandedBits can simplify this. This handles stuff like |
| // (X & 254)+1 -> (X&254)|1 |
| if (!isa<VectorType>(I.getType())) { |
| APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0); |
| if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(BitWidth), |
| KnownZero, KnownOne)) |
| return &I; |
| } |
| |
| // zext(i1) - 1 -> select i1, 0, -1 |
| if (ZExtInst *ZI = dyn_cast<ZExtInst>(LHS)) |
| if (CI->isAllOnesValue() && |
| ZI->getOperand(0)->getType() == Type::Int1Ty) |
| return SelectInst::Create(ZI->getOperand(0), |
| Constant::getNullValue(I.getType()), |
| ConstantInt::getAllOnesValue(I.getType())); |
| } |
| |
| if (isa<PHINode>(LHS)) |
| if (Instruction *NV = FoldOpIntoPhi(I)) |
| return NV; |
| |
| ConstantInt *XorRHS = 0; |
| Value *XorLHS = 0; |
| if (isa<ConstantInt>(RHSC) && |
| match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) { |
| uint32_t TySizeBits = I.getType()->getPrimitiveSizeInBits(); |
| const APInt& RHSVal = cast<ConstantInt>(RHSC)->getValue(); |
| |
| uint32_t Size = TySizeBits / 2; |
| APInt C0080Val(APInt(TySizeBits, 1ULL).shl(Size - 1)); |
| APInt CFF80Val(-C0080Val); |
| do { |
| if (TySizeBits > Size) { |
| // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext. |
| // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext. |
| if ((RHSVal == CFF80Val && XorRHS->getValue() == C0080Val) || |
| (RHSVal == C0080Val && XorRHS->getValue() == CFF80Val)) { |
| // This is a sign extend if the top bits are known zero. |
| if (!MaskedValueIsZero(XorLHS, |
| APInt::getHighBitsSet(TySizeBits, TySizeBits - Size))) |
| Size = 0; // Not a sign ext, but can't be any others either. |
| break; |
| } |
| } |
| Size >>= 1; |
| C0080Val = APIntOps::lshr(C0080Val, Size); |
| CFF80Val = APIntOps::ashr(CFF80Val, Size); |
| } while (Size >= 1); |
| |
| // FIXME: This shouldn't be necessary. When the backends can handle types |
| // with funny bit widths then this switch statement should be removed. It |
| // is just here to get the size of the "middle" type back up to something |
| // that the back ends can handle. |
| const Type *MiddleType = 0; |
| switch (Size) { |
| default: break; |
| case 32: MiddleType = Type::Int32Ty; break; |
| case 16: MiddleType = Type::Int16Ty; break; |
| case 8: MiddleType = Type::Int8Ty; break; |
| } |
| if (MiddleType) { |
| Instruction *NewTrunc = new TruncInst(XorLHS, MiddleType, "sext"); |
| InsertNewInstBefore(NewTrunc, I); |
| return new SExtInst(NewTrunc, I.getType(), I.getName()); |
| } |
| } |
| } |
| |
| if (I.getType() == Type::Int1Ty) |
| return BinaryOperator::CreateXor(LHS, RHS); |
| |
| // X + X --> X << 1 |
| if (I.getType()->isInteger()) { |
| if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result; |
| |
| if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) { |
| if (RHSI->getOpcode() == Instruction::Sub) |
| if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B |
| return ReplaceInstUsesWith(I, RHSI->getOperand(0)); |
| } |
| if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) { |
| if (LHSI->getOpcode() == Instruction::Sub) |
| if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B |
| return ReplaceInstUsesWith(I, LHSI->getOperand(0)); |
| } |
| } |
| |
| // -A + B --> B - A |
| // -A + -B --> -(A + B) |
| if (Value *LHSV = dyn_castNegVal(LHS)) { |
| if (LHS->getType()->isIntOrIntVector()) { |
| if (Value *RHSV = dyn_castNegVal(RHS)) { |
| Instruction *NewAdd = BinaryOperator::CreateAdd(LHSV, RHSV, "sum"); |
| InsertNewInstBefore(NewAdd, I); |
| return BinaryOperator::CreateNeg(NewAdd); |
| } |
| } |
| |
| return BinaryOperator::CreateSub(RHS, LHSV); |
| } |
| |
| // A + -B --> A - B |
| if (!isa<Constant>(RHS)) |
| if (Value *V = dyn_castNegVal(RHS)) |
| return BinaryOperator::CreateSub(LHS, V); |
| |
| |
| ConstantInt *C2; |
| if (Value *X = dyn_castFoldableMul(LHS, C2)) { |
| if (X == RHS) // X*C + X --> X * (C+1) |
| return BinaryOperator::CreateMul(RHS, AddOne(C2)); |
| |
| // X*C1 + X*C2 --> X * (C1+C2) |
| ConstantInt *C1; |
| if (X == dyn_castFoldableMul(RHS, C1)) |
| return BinaryOperator::CreateMul(X, Add(C1, C2)); |
| } |
| |
| // X + X*C --> X * (C+1) |
| if (dyn_castFoldableMul(RHS, C2) == LHS) |
| return BinaryOperator::CreateMul(LHS, AddOne(C2)); |
| |
| // X + ~X --> -1 since ~X = -X-1 |
| if (dyn_castNotVal(LHS) == RHS || dyn_castNotVal(RHS) == LHS) |
| return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType())); |
| |
| |
| // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0 |
| if (match(RHS, m_And(m_Value(), m_ConstantInt(C2)))) |
| if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) |
| return R; |
| |
| // A+B --> A|B iff A and B have no bits set in common. |
| if (const IntegerType *IT = dyn_cast<IntegerType>(I.getType())) { |
| APInt Mask = APInt::getAllOnesValue(IT->getBitWidth()); |
| APInt LHSKnownOne(IT->getBitWidth(), 0); |
| APInt LHSKnownZero(IT->getBitWidth(), 0); |
| ComputeMaskedBits(LHS, Mask, LHSKnownZero, LHSKnownOne); |
| if (LHSKnownZero != 0) { |
| APInt RHSKnownOne(IT->getBitWidth(), 0); |
| APInt RHSKnownZero(IT->getBitWidth(), 0); |
| ComputeMaskedBits(RHS, Mask, RHSKnownZero, RHSKnownOne); |
| |
| // No bits in common -> bitwise or. |
| if ((LHSKnownZero|RHSKnownZero).isAllOnesValue()) |
| return BinaryOperator::CreateOr(LHS, RHS); |
| } |
| } |
| |
| // W*X + Y*Z --> W * (X+Z) iff W == Y |
| if (I.getType()->isIntOrIntVector()) { |
| Value *W, *X, *Y, *Z; |
| if (match(LHS, m_Mul(m_Value(W), m_Value(X))) && |
| match(RHS, m_Mul(m_Value(Y), m_Value(Z)))) { |
| if (W != Y) { |
| if (W == Z) { |
| std::swap(Y, Z); |
| } else if (Y == X) { |
| std::swap(W, X); |
| } else if (X == Z) { |
| std::swap(Y, Z); |
| std::swap(W, X); |
| } |
| } |
| |
| if (W == Y) { |
| Value *NewAdd = InsertNewInstBefore(BinaryOperator::CreateAdd(X, Z, |
| LHS->getName()), I); |
| return BinaryOperator::CreateMul(W, NewAdd); |
| } |
| } |
| } |
| |
| if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) { |
| Value *X = 0; |
| if (match(LHS, m_Not(m_Value(X)))) // ~X + C --> (C-1) - X |
| return BinaryOperator::CreateSub(SubOne(CRHS), X); |
| |
| // (X & FF00) + xx00 -> (X+xx00) & FF00 |
| if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) { |
| Constant *Anded = And(CRHS, C2); |
| if (Anded == CRHS) { |
| // See if all bits from the first bit set in the Add RHS up are included |
| // in the mask. First, get the rightmost bit. |
| const APInt& AddRHSV = CRHS->getValue(); |
| |
| // Form a mask of all bits from the lowest bit added through the top. |
| APInt AddRHSHighBits(~((AddRHSV & -AddRHSV)-1)); |
| |
| // See if the and mask includes all of these bits. |
| APInt AddRHSHighBitsAnd(AddRHSHighBits & C2->getValue()); |
| |
| if (AddRHSHighBits == AddRHSHighBitsAnd) { |
| // Okay, the xform is safe. Insert the new add pronto. |
| Value *NewAdd = InsertNewInstBefore(BinaryOperator::CreateAdd(X, CRHS, |
| LHS->getName()), I); |
| return BinaryOperator::CreateAnd(NewAdd, C2); |
| } |
| } |
| } |
| |
| // Try to fold constant add into select arguments. |
| if (SelectInst *SI = dyn_cast<SelectInst>(LHS)) |
| if (Instruction *R = FoldOpIntoSelect(I, SI, this)) |
| return R; |
| } |
| |
| // add (cast *A to intptrtype) B -> |
| // cast (GEP (cast *A to sbyte*) B) --> intptrtype |
| { |
| CastInst *CI = dyn_cast<CastInst>(LHS); |
| Value *Other = RHS; |
| if (!CI) { |
| CI = dyn_cast<CastInst>(RHS); |
| Other = LHS; |
| } |
| if (CI && CI->getType()->isSized() && |
| (CI->getType()->getPrimitiveSizeInBits() == |
| TD->getIntPtrType()->getPrimitiveSizeInBits()) |
| && isa<PointerType>(CI->getOperand(0)->getType())) { |
| unsigned AS = |
| cast<PointerType>(CI->getOperand(0)->getType())->getAddressSpace(); |
| Value *I2 = InsertBitCastBefore(CI->getOperand(0), |
| PointerType::get(Type::Int8Ty, AS), I); |
| I2 = InsertNewInstBefore(GetElementPtrInst::Create(I2, Other, "ctg2"), I); |
| return new PtrToIntInst(I2, CI->getType()); |
| } |
| } |
| |
| // add (select X 0 (sub n A)) A --> select X A n |
| { |
| SelectInst *SI = dyn_cast<SelectInst>(LHS); |
| Value *A = RHS; |
| if (!SI) { |
| SI = dyn_cast<SelectInst>(RHS); |
| A = LHS; |
| } |
| if (SI && SI->hasOneUse()) { |
| Value *TV = SI->getTrueValue(); |
| Value *FV = SI->getFalseValue(); |
| Value *N; |
| |
| // Can we fold the add into the argument of the select? |
| // We check both true and false select arguments for a matching subtract. |
| if (match(FV, m_Zero()) && match(TV, m_Sub(m_Value(N), m_Specific(A)))) |
| // Fold the add into the true select value. |
| return SelectInst::Create(SI->getCondition(), N, A); |
| if (match(TV, m_Zero()) && match(FV, m_Sub(m_Value(N), m_Specific(A)))) |
| // Fold the add into the false select value. |
| return SelectInst::Create(SI->getCondition(), A, N); |
| } |
| } |
| |
| // Check for X+0.0. Simplify it to X if we know X is not -0.0. |
| if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS)) |
| if (CFP->getValueAPF().isPosZero() && CannotBeNegativeZero(LHS)) |
| return ReplaceInstUsesWith(I, LHS); |
| |
| // Check for (add (sext x), y), see if we can merge this into an |
| // integer add followed by a sext. |
| if (SExtInst *LHSConv = dyn_cast<SExtInst>(LHS)) { |
| // (add (sext x), cst) --> (sext (add x, cst')) |
| if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) { |
| Constant *CI = |
| ConstantExpr::getTrunc(RHSC, LHSConv->getOperand(0)->getType()); |
| if (LHSConv->hasOneUse() && |
| ConstantExpr::getSExt(CI, I.getType()) == RHSC && |
| WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) { |
| // Insert the new, smaller add. |
| Instruction *NewAdd = BinaryOperator::CreateAdd(LHSConv->getOperand(0), |
| CI, "addconv"); |
| InsertNewInstBefore(NewAdd, I); |
| return new SExtInst(NewAdd, I.getType()); |
| } |
| } |
| |
| // (add (sext x), (sext y)) --> (sext (add int x, y)) |
| if (SExtInst *RHSConv = dyn_cast<SExtInst>(RHS)) { |
| // Only do this if x/y have the same type, if at last one of them has a |
| // single use (so we don't increase the number of sexts), and if the |
| // integer add will not overflow. |
| if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&& |
| (LHSConv->hasOneUse() || RHSConv->hasOneUse()) && |
| WillNotOverflowSignedAdd(LHSConv->getOperand(0), |
| RHSConv->getOperand(0))) { |
| // Insert the new integer add. |
| Instruction *NewAdd = BinaryOperator::CreateAdd(LHSConv->getOperand(0), |
| RHSConv->getOperand(0), |
| "addconv"); |
| InsertNewInstBefore(NewAdd, I); |
| return new SExtInst(NewAdd, I.getType()); |
| } |
| } |
| } |
| |
| // Check for (add double (sitofp x), y), see if we can merge this into an |
| // integer add followed by a promotion. |
| if (SIToFPInst *LHSConv = dyn_cast<SIToFPInst>(LHS)) { |
| // (add double (sitofp x), fpcst) --> (sitofp (add int x, intcst)) |
| // ... if the constant fits in the integer value. This is useful for things |
| // like (double)(x & 1234) + 4.0 -> (double)((X & 1234)+4) which no longer |
| // requires a constant pool load, and generally allows the add to be better |
| // instcombined. |
| if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHS)) { |
| Constant *CI = |
| ConstantExpr::getFPToSI(CFP, LHSConv->getOperand(0)->getType()); |
| if (LHSConv->hasOneUse() && |
| ConstantExpr::getSIToFP(CI, I.getType()) == CFP && |
| WillNotOverflowSignedAdd(LHSConv->getOperand(0), CI)) { |
| // Insert the new integer add. |
| Instruction *NewAdd = BinaryOperator::CreateAdd(LHSConv->getOperand(0), |
| CI, "addconv"); |
| InsertNewInstBefore(NewAdd, I); |
| return new SIToFPInst(NewAdd, I.getType()); |
| } |
| } |
| |
| // (add double (sitofp x), (sitofp y)) --> (sitofp (add int x, y)) |
| if (SIToFPInst *RHSConv = dyn_cast<SIToFPInst>(RHS)) { |
| // Only do this if x/y have the same type, if at last one of them has a |
| // single use (so we don't increase the number of int->fp conversions), |
| // and if the integer add will not overflow. |
| if (LHSConv->getOperand(0)->getType()==RHSConv->getOperand(0)->getType()&& |
| (LHSConv->hasOneUse() || RHSConv->hasOneUse()) && |
| WillNotOverflowSignedAdd(LHSConv->getOperand(0), |
| RHSConv->getOperand(0))) { |
| // Insert the new integer add. |
| Instruction *NewAdd = BinaryOperator::CreateAdd(LHSConv->getOperand(0), |
| RHSConv->getOperand(0), |
| "addconv"); |
| InsertNewInstBefore(NewAdd, I); |
| return new SIToFPInst(NewAdd, I.getType()); |
| } |
| } |
| } |
| |
| return Changed ? &I : 0; |
| } |
| |
| Instruction *InstCombiner::visitSub(BinaryOperator &I) { |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| if (Op0 == Op1 && // sub X, X -> 0 |
| !I.getType()->isFPOrFPVector()) |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| |
| // If this is a 'B = x-(-A)', change to B = x+A... |
| if (Value *V = dyn_castNegVal(Op1)) |
| return BinaryOperator::CreateAdd(Op0, V); |
| |
| if (isa<UndefValue>(Op0)) |
| return ReplaceInstUsesWith(I, Op0); // undef - X -> undef |
| if (isa<UndefValue>(Op1)) |
| return ReplaceInstUsesWith(I, Op1); // X - undef -> undef |
| |
| if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) { |
| // Replace (-1 - A) with (~A)... |
| if (C->isAllOnesValue()) |
| return BinaryOperator::CreateNot(Op1); |
| |
| // C - ~X == X + (1+C) |
| Value *X = 0; |
| if (match(Op1, m_Not(m_Value(X)))) |
| return BinaryOperator::CreateAdd(X, AddOne(C)); |
| |
| // -(X >>u 31) -> (X >>s 31) |
| // -(X >>s 31) -> (X >>u 31) |
| if (C->isZero()) { |
| if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op1)) { |
| if (SI->getOpcode() == Instruction::LShr) { |
| if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) { |
| // Check to see if we are shifting out everything but the sign bit. |
| if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) == |
| SI->getType()->getPrimitiveSizeInBits()-1) { |
| // Ok, the transformation is safe. Insert AShr. |
| return BinaryOperator::Create(Instruction::AShr, |
| SI->getOperand(0), CU, SI->getName()); |
| } |
| } |
| } |
| else if (SI->getOpcode() == Instruction::AShr) { |
| if (ConstantInt *CU = dyn_cast<ConstantInt>(SI->getOperand(1))) { |
| // Check to see if we are shifting out everything but the sign bit. |
| if (CU->getLimitedValue(SI->getType()->getPrimitiveSizeInBits()) == |
| SI->getType()->getPrimitiveSizeInBits()-1) { |
| // Ok, the transformation is safe. Insert LShr. |
| return BinaryOperator::CreateLShr( |
| SI->getOperand(0), CU, SI->getName()); |
| } |
| } |
| } |
| } |
| } |
| |
| // Try to fold constant sub into select arguments. |
| if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) |
| if (Instruction *R = FoldOpIntoSelect(I, SI, this)) |
| return R; |
| } |
| |
| if (I.getType() == Type::Int1Ty) |
| return BinaryOperator::CreateXor(Op0, Op1); |
| |
| if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) { |
| if (Op1I->getOpcode() == Instruction::Add && |
| !Op0->getType()->isFPOrFPVector()) { |
| if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y |
| return BinaryOperator::CreateNeg(Op1I->getOperand(1), I.getName()); |
| else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y |
| return BinaryOperator::CreateNeg(Op1I->getOperand(0), I.getName()); |
| else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) { |
| if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1))) |
| // C1-(X+C2) --> (C1-C2)-X |
| return BinaryOperator::CreateSub(Subtract(CI1, CI2), |
| Op1I->getOperand(0)); |
| } |
| } |
| |
| if (Op1I->hasOneUse()) { |
| // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression |
| // is not used by anyone else... |
| // |
| if (Op1I->getOpcode() == Instruction::Sub && |
| !Op1I->getType()->isFPOrFPVector()) { |
| // Swap the two operands of the subexpr... |
| Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1); |
| Op1I->setOperand(0, IIOp1); |
| Op1I->setOperand(1, IIOp0); |
| |
| // Create the new top level add instruction... |
| return BinaryOperator::CreateAdd(Op0, Op1); |
| } |
| |
| // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)... |
| // |
| if (Op1I->getOpcode() == Instruction::And && |
| (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) { |
| Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0); |
| |
| Value *NewNot = |
| InsertNewInstBefore(BinaryOperator::CreateNot(OtherOp, "B.not"), I); |
| return BinaryOperator::CreateAnd(Op0, NewNot); |
| } |
| |
| // 0 - (X sdiv C) -> (X sdiv -C) |
| if (Op1I->getOpcode() == Instruction::SDiv) |
| if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0)) |
| if (CSI->isZero()) |
| if (Constant *DivRHS = dyn_cast<Constant>(Op1I->getOperand(1))) |
| return BinaryOperator::CreateSDiv(Op1I->getOperand(0), |
| ConstantExpr::getNeg(DivRHS)); |
| |
| // X - X*C --> X * (1-C) |
| ConstantInt *C2 = 0; |
| if (dyn_castFoldableMul(Op1I, C2) == Op0) { |
| Constant *CP1 = Subtract(ConstantInt::get(I.getType(), 1), C2); |
| return BinaryOperator::CreateMul(Op0, CP1); |
| } |
| } |
| } |
| |
| if (!Op0->getType()->isFPOrFPVector()) |
| if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) { |
| if (Op0I->getOpcode() == Instruction::Add) { |
| if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X |
| return ReplaceInstUsesWith(I, Op0I->getOperand(1)); |
| else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X |
| return ReplaceInstUsesWith(I, Op0I->getOperand(0)); |
| } else if (Op0I->getOpcode() == Instruction::Sub) { |
| if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y |
| return BinaryOperator::CreateNeg(Op0I->getOperand(1), I.getName()); |
| } |
| } |
| |
| ConstantInt *C1; |
| if (Value *X = dyn_castFoldableMul(Op0, C1)) { |
| if (X == Op1) // X*C - X --> X * (C-1) |
| return BinaryOperator::CreateMul(Op1, SubOne(C1)); |
| |
| ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2) |
| if (X == dyn_castFoldableMul(Op1, C2)) |
| return BinaryOperator::CreateMul(X, Subtract(C1, C2)); |
| } |
| return 0; |
| } |
| |
| /// isSignBitCheck - Given an exploded icmp instruction, return true if the |
| /// comparison only checks the sign bit. If it only checks the sign bit, set |
| /// TrueIfSigned if the result of the comparison is true when the input value is |
| /// signed. |
| static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS, |
| bool &TrueIfSigned) { |
| switch (pred) { |
| case ICmpInst::ICMP_SLT: // True if LHS s< 0 |
| TrueIfSigned = true; |
| return RHS->isZero(); |
| case ICmpInst::ICMP_SLE: // True if LHS s<= RHS and RHS == -1 |
| TrueIfSigned = true; |
| return RHS->isAllOnesValue(); |
| case ICmpInst::ICMP_SGT: // True if LHS s> -1 |
| TrueIfSigned = false; |
| return RHS->isAllOnesValue(); |
| case ICmpInst::ICMP_UGT: |
| // True if LHS u> RHS and RHS == high-bit-mask - 1 |
| TrueIfSigned = true; |
| return RHS->getValue() == |
| APInt::getSignedMaxValue(RHS->getType()->getPrimitiveSizeInBits()); |
| case ICmpInst::ICMP_UGE: |
| // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc) |
| TrueIfSigned = true; |
| return RHS->getValue().isSignBit(); |
| default: |
| return false; |
| } |
| } |
| |
| Instruction *InstCombiner::visitMul(BinaryOperator &I) { |
| bool Changed = SimplifyCommutative(I); |
| Value *Op0 = I.getOperand(0); |
| |
| if (isa<UndefValue>(I.getOperand(1))) // undef * X -> 0 |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| |
| // Simplify mul instructions with a constant RHS... |
| if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) { |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { |
| |
| // ((X << C1)*C2) == (X * (C2 << C1)) |
| if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op0)) |
| if (SI->getOpcode() == Instruction::Shl) |
| if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1))) |
| return BinaryOperator::CreateMul(SI->getOperand(0), |
| ConstantExpr::getShl(CI, ShOp)); |
| |
| if (CI->isZero()) |
| return ReplaceInstUsesWith(I, Op1); // X * 0 == 0 |
| if (CI->equalsInt(1)) // X * 1 == X |
| return ReplaceInstUsesWith(I, Op0); |
| if (CI->isAllOnesValue()) // X * -1 == 0 - X |
| return BinaryOperator::CreateNeg(Op0, I.getName()); |
| |
| const APInt& Val = cast<ConstantInt>(CI)->getValue(); |
| if (Val.isPowerOf2()) { // Replace X*(2^C) with X << C |
| return BinaryOperator::CreateShl(Op0, |
| ConstantInt::get(Op0->getType(), Val.logBase2())); |
| } |
| } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) { |
| if (Op1F->isNullValue()) |
| return ReplaceInstUsesWith(I, Op1); |
| |
| // "In IEEE floating point, x*1 is not equivalent to x for nans. However, |
| // ANSI says we can drop signals, so we can do this anyway." (from GCC) |
| if (Op1F->isExactlyValue(1.0)) |
| return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0' |
| } else if (isa<VectorType>(Op1->getType())) { |
| if (isa<ConstantAggregateZero>(Op1)) |
| return ReplaceInstUsesWith(I, Op1); |
| |
| if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1)) { |
| if (Op1V->isAllOnesValue()) // X * -1 == 0 - X |
| return BinaryOperator::CreateNeg(Op0, I.getName()); |
| |
| // As above, vector X*splat(1.0) -> X in all defined cases. |
| if (Constant *Splat = Op1V->getSplatValue()) { |
| if (ConstantFP *F = dyn_cast<ConstantFP>(Splat)) |
| if (F->isExactlyValue(1.0)) |
| return ReplaceInstUsesWith(I, Op0); |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(Splat)) |
| if (CI->equalsInt(1)) |
| return ReplaceInstUsesWith(I, Op0); |
| } |
| } |
| } |
| |
| if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) |
| if (Op0I->getOpcode() == Instruction::Add && Op0I->hasOneUse() && |
| isa<ConstantInt>(Op0I->getOperand(1)) && isa<ConstantInt>(Op1)) { |
| // Canonicalize (X+C1)*C2 -> X*C2+C1*C2. |
| Instruction *Add = BinaryOperator::CreateMul(Op0I->getOperand(0), |
| Op1, "tmp"); |
| InsertNewInstBefore(Add, I); |
| Value *C1C2 = ConstantExpr::getMul(Op1, |
| cast<Constant>(Op0I->getOperand(1))); |
| return BinaryOperator::CreateAdd(Add, C1C2); |
| |
| } |
| |
| // Try to fold constant mul into select arguments. |
| if (SelectInst *SI = dyn_cast<SelectInst>(Op0)) |
| if (Instruction *R = FoldOpIntoSelect(I, SI, this)) |
| return R; |
| |
| if (isa<PHINode>(Op0)) |
| if (Instruction *NV = FoldOpIntoPhi(I)) |
| return NV; |
| } |
| |
| if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y |
| if (Value *Op1v = dyn_castNegVal(I.getOperand(1))) |
| return BinaryOperator::CreateMul(Op0v, Op1v); |
| |
| // (X / Y) * Y = X - (X % Y) |
| // (X / Y) * -Y = (X % Y) - X |
| { |
| Value *Op1 = I.getOperand(1); |
| BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0); |
| if (!BO || |
| (BO->getOpcode() != Instruction::UDiv && |
| BO->getOpcode() != Instruction::SDiv)) { |
| Op1 = Op0; |
| BO = dyn_cast<BinaryOperator>(I.getOperand(1)); |
| } |
| Value *Neg = dyn_castNegVal(Op1); |
| if (BO && BO->hasOneUse() && |
| (BO->getOperand(1) == Op1 || BO->getOperand(1) == Neg) && |
| (BO->getOpcode() == Instruction::UDiv || |
| BO->getOpcode() == Instruction::SDiv)) { |
| Value *Op0BO = BO->getOperand(0), *Op1BO = BO->getOperand(1); |
| |
| Instruction *Rem; |
| if (BO->getOpcode() == Instruction::UDiv) |
| Rem = BinaryOperator::CreateURem(Op0BO, Op1BO); |
| else |
| Rem = BinaryOperator::CreateSRem(Op0BO, Op1BO); |
| |
| InsertNewInstBefore(Rem, I); |
| Rem->takeName(BO); |
| |
| if (Op1BO == Op1) |
| return BinaryOperator::CreateSub(Op0BO, Rem); |
| else |
| return BinaryOperator::CreateSub(Rem, Op0BO); |
| } |
| } |
| |
| if (I.getType() == Type::Int1Ty) |
| return BinaryOperator::CreateAnd(Op0, I.getOperand(1)); |
| |
| // If one of the operands of the multiply is a cast from a boolean value, then |
| // we know the bool is either zero or one, so this is a 'masking' multiply. |
| // See if we can simplify things based on how the boolean was originally |
| // formed. |
| CastInst *BoolCast = 0; |
| if (ZExtInst *CI = dyn_cast<ZExtInst>(Op0)) |
| if (CI->getOperand(0)->getType() == Type::Int1Ty) |
| BoolCast = CI; |
| if (!BoolCast) |
| if (ZExtInst *CI = dyn_cast<ZExtInst>(I.getOperand(1))) |
| if (CI->getOperand(0)->getType() == Type::Int1Ty) |
| BoolCast = CI; |
| if (BoolCast) { |
| if (ICmpInst *SCI = dyn_cast<ICmpInst>(BoolCast->getOperand(0))) { |
| Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1); |
| const Type *SCOpTy = SCIOp0->getType(); |
| bool TIS = false; |
| |
| // If the icmp is true iff the sign bit of X is set, then convert this |
| // multiply into a shift/and combination. |
| if (isa<ConstantInt>(SCIOp1) && |
| isSignBitCheck(SCI->getPredicate(), cast<ConstantInt>(SCIOp1), TIS) && |
| TIS) { |
| // Shift the X value right to turn it into "all signbits". |
| Constant *Amt = ConstantInt::get(SCIOp0->getType(), |
| SCOpTy->getPrimitiveSizeInBits()-1); |
| Value *V = |
| InsertNewInstBefore( |
| BinaryOperator::Create(Instruction::AShr, SCIOp0, Amt, |
| BoolCast->getOperand(0)->getName()+ |
| ".mask"), I); |
| |
| // If the multiply type is not the same as the source type, sign extend |
| // or truncate to the multiply type. |
| if (I.getType() != V->getType()) { |
| uint32_t SrcBits = V->getType()->getPrimitiveSizeInBits(); |
| uint32_t DstBits = I.getType()->getPrimitiveSizeInBits(); |
| Instruction::CastOps opcode = |
| (SrcBits == DstBits ? Instruction::BitCast : |
| (SrcBits < DstBits ? Instruction::SExt : Instruction::Trunc)); |
| V = InsertCastBefore(opcode, V, I.getType(), I); |
| } |
| |
| Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0; |
| return BinaryOperator::CreateAnd(V, OtherOp); |
| } |
| } |
| } |
| |
| return Changed ? &I : 0; |
| } |
| |
| /// SimplifyDivRemOfSelect - Try to fold a divide or remainder of a select |
| /// instruction. |
| bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) { |
| SelectInst *SI = cast<SelectInst>(I.getOperand(1)); |
| |
| // div/rem X, (Cond ? 0 : Y) -> div/rem X, Y |
| int NonNullOperand = -1; |
| if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1))) |
| if (ST->isNullValue()) |
| NonNullOperand = 2; |
| // div/rem X, (Cond ? Y : 0) -> div/rem X, Y |
| if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2))) |
| if (ST->isNullValue()) |
| NonNullOperand = 1; |
| |
| if (NonNullOperand == -1) |
| return false; |
| |
| Value *SelectCond = SI->getOperand(0); |
| |
| // Change the div/rem to use 'Y' instead of the select. |
| I.setOperand(1, SI->getOperand(NonNullOperand)); |
| |
| // Okay, we know we replace the operand of the div/rem with 'Y' with no |
| // problem. However, the select, or the condition of the select may have |
| // multiple uses. Based on our knowledge that the operand must be non-zero, |
| // propagate the known value for the select into other uses of it, and |
| // propagate a known value of the condition into its other users. |
| |
| // If the select and condition only have a single use, don't bother with this, |
| // early exit. |
| if (SI->use_empty() && SelectCond->hasOneUse()) |
| return true; |
| |
| // Scan the current block backward, looking for other uses of SI. |
| BasicBlock::iterator BBI = &I, BBFront = I.getParent()->begin(); |
| |
| while (BBI != BBFront) { |
| --BBI; |
| // If we found a call to a function, we can't assume it will return, so |
| // information from below it cannot be propagated above it. |
| if (isa<CallInst>(BBI) && !isa<IntrinsicInst>(BBI)) |
| break; |
| |
| // Replace uses of the select or its condition with the known values. |
| for (Instruction::op_iterator I = BBI->op_begin(), E = BBI->op_end(); |
| I != E; ++I) { |
| if (*I == SI) { |
| *I = SI->getOperand(NonNullOperand); |
| AddToWorkList(BBI); |
| } else if (*I == SelectCond) { |
| *I = NonNullOperand == 1 ? ConstantInt::getTrue() : |
| ConstantInt::getFalse(); |
| AddToWorkList(BBI); |
| } |
| } |
| |
| // If we past the instruction, quit looking for it. |
| if (&*BBI == SI) |
| SI = 0; |
| if (&*BBI == SelectCond) |
| SelectCond = 0; |
| |
| // If we ran out of things to eliminate, break out of the loop. |
| if (SelectCond == 0 && SI == 0) |
| break; |
| |
| } |
| return true; |
| } |
| |
| |
| /// This function implements the transforms on div instructions that work |
| /// regardless of the kind of div instruction it is (udiv, sdiv, or fdiv). It is |
| /// used by the visitors to those instructions. |
| /// @brief Transforms common to all three div instructions |
| Instruction *InstCombiner::commonDivTransforms(BinaryOperator &I) { |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| // undef / X -> 0 for integer. |
| // undef / X -> undef for FP (the undef could be a snan). |
| if (isa<UndefValue>(Op0)) { |
| if (Op0->getType()->isFPOrFPVector()) |
| return ReplaceInstUsesWith(I, Op0); |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| } |
| |
| // X / undef -> undef |
| if (isa<UndefValue>(Op1)) |
| return ReplaceInstUsesWith(I, Op1); |
| |
| return 0; |
| } |
| |
| /// This function implements the transforms common to both integer division |
| /// instructions (udiv and sdiv). It is called by the visitors to those integer |
| /// division instructions. |
| /// @brief Common integer divide transforms |
| Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) { |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| // (sdiv X, X) --> 1 (udiv X, X) --> 1 |
| if (Op0 == Op1) { |
| if (const VectorType *Ty = dyn_cast<VectorType>(I.getType())) { |
| ConstantInt *CI = ConstantInt::get(Ty->getElementType(), 1); |
| std::vector<Constant*> Elts(Ty->getNumElements(), CI); |
| return ReplaceInstUsesWith(I, ConstantVector::get(Elts)); |
| } |
| |
| ConstantInt *CI = ConstantInt::get(I.getType(), 1); |
| return ReplaceInstUsesWith(I, CI); |
| } |
| |
| if (Instruction *Common = commonDivTransforms(I)) |
| return Common; |
| |
| // Handle cases involving: [su]div X, (select Cond, Y, Z) |
| // This does not apply for fdiv. |
| if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I)) |
| return &I; |
| |
| if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) { |
| // div X, 1 == X |
| if (RHS->equalsInt(1)) |
| return ReplaceInstUsesWith(I, Op0); |
| |
| // (X / C1) / C2 -> X / (C1*C2) |
| if (Instruction *LHS = dyn_cast<Instruction>(Op0)) |
| if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode()) |
| if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) { |
| if (MultiplyOverflows(RHS, LHSRHS, I.getOpcode()==Instruction::SDiv)) |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| else |
| return BinaryOperator::Create(I.getOpcode(), LHS->getOperand(0), |
| Multiply(RHS, LHSRHS)); |
| } |
| |
| if (!RHS->isZero()) { // avoid X udiv 0 |
| if (SelectInst *SI = dyn_cast<SelectInst>(Op0)) |
| if (Instruction *R = FoldOpIntoSelect(I, SI, this)) |
| return R; |
| if (isa<PHINode>(Op0)) |
| if (Instruction *NV = FoldOpIntoPhi(I)) |
| return NV; |
| } |
| } |
| |
| // 0 / X == 0, we don't need to preserve faults! |
| if (ConstantInt *LHS = dyn_cast<ConstantInt>(Op0)) |
| if (LHS->equalsInt(0)) |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| |
| // It can't be division by zero, hence it must be division by one. |
| if (I.getType() == Type::Int1Ty) |
| return ReplaceInstUsesWith(I, Op0); |
| |
| if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1)) { |
| if (ConstantInt *X = cast_or_null<ConstantInt>(Op1V->getSplatValue())) |
| // div X, 1 == X |
| if (X->isOne()) |
| return ReplaceInstUsesWith(I, Op0); |
| } |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitUDiv(BinaryOperator &I) { |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| // Handle the integer div common cases |
| if (Instruction *Common = commonIDivTransforms(I)) |
| return Common; |
| |
| if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) { |
| // X udiv C^2 -> X >> C |
| // Check to see if this is an unsigned division with an exact power of 2, |
| // if so, convert to a right shift. |
| if (C->getValue().isPowerOf2()) // 0 not included in isPowerOf2 |
| return BinaryOperator::CreateLShr(Op0, |
| ConstantInt::get(Op0->getType(), C->getValue().logBase2())); |
| |
| // X udiv C, where C >= signbit |
| if (C->getValue().isNegative()) { |
| Value *IC = InsertNewInstBefore(new ICmpInst(ICmpInst::ICMP_ULT, Op0, C), |
| I); |
| return SelectInst::Create(IC, Constant::getNullValue(I.getType()), |
| ConstantInt::get(I.getType(), 1)); |
| } |
| } |
| |
| // X udiv (C1 << N), where C1 is "1<<C2" --> X >> (N+C2) |
| if (BinaryOperator *RHSI = dyn_cast<BinaryOperator>(I.getOperand(1))) { |
| if (RHSI->getOpcode() == Instruction::Shl && |
| isa<ConstantInt>(RHSI->getOperand(0))) { |
| const APInt& C1 = cast<ConstantInt>(RHSI->getOperand(0))->getValue(); |
| if (C1.isPowerOf2()) { |
| Value *N = RHSI->getOperand(1); |
| const Type *NTy = N->getType(); |
| if (uint32_t C2 = C1.logBase2()) { |
| Constant *C2V = ConstantInt::get(NTy, C2); |
| N = InsertNewInstBefore(BinaryOperator::CreateAdd(N, C2V, "tmp"), I); |
| } |
| return BinaryOperator::CreateLShr(Op0, N); |
| } |
| } |
| } |
| |
| // udiv X, (Select Cond, C1, C2) --> Select Cond, (shr X, C1), (shr X, C2) |
| // where C1&C2 are powers of two. |
| if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) |
| if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1))) |
| if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) { |
| const APInt &TVA = STO->getValue(), &FVA = SFO->getValue(); |
| if (TVA.isPowerOf2() && FVA.isPowerOf2()) { |
| // Compute the shift amounts |
| uint32_t TSA = TVA.logBase2(), FSA = FVA.logBase2(); |
| // Construct the "on true" case of the select |
| Constant *TC = ConstantInt::get(Op0->getType(), TSA); |
| Instruction *TSI = BinaryOperator::CreateLShr( |
| Op0, TC, SI->getName()+".t"); |
| TSI = InsertNewInstBefore(TSI, I); |
| |
| // Construct the "on false" case of the select |
| Constant *FC = ConstantInt::get(Op0->getType(), FSA); |
| Instruction *FSI = BinaryOperator::CreateLShr( |
| Op0, FC, SI->getName()+".f"); |
| FSI = InsertNewInstBefore(FSI, I); |
| |
| // construct the select instruction and return it. |
| return SelectInst::Create(SI->getOperand(0), TSI, FSI, SI->getName()); |
| } |
| } |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitSDiv(BinaryOperator &I) { |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| // Handle the integer div common cases |
| if (Instruction *Common = commonIDivTransforms(I)) |
| return Common; |
| |
| if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) { |
| // sdiv X, -1 == -X |
| if (RHS->isAllOnesValue()) |
| return BinaryOperator::CreateNeg(Op0); |
| } |
| |
| // If the sign bits of both operands are zero (i.e. we can prove they are |
| // unsigned inputs), turn this into a udiv. |
| if (I.getType()->isInteger()) { |
| APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits())); |
| if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) { |
| // X sdiv Y -> X udiv Y, iff X and Y don't have sign bit set |
| return BinaryOperator::CreateUDiv(Op0, Op1, I.getName()); |
| } |
| } |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitFDiv(BinaryOperator &I) { |
| return commonDivTransforms(I); |
| } |
| |
| /// This function implements the transforms on rem instructions that work |
| /// regardless of the kind of rem instruction it is (urem, srem, or frem). It |
| /// is used by the visitors to those instructions. |
| /// @brief Transforms common to all three rem instructions |
| Instruction *InstCombiner::commonRemTransforms(BinaryOperator &I) { |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| // 0 % X == 0 for integer, we don't need to preserve faults! |
| if (Constant *LHS = dyn_cast<Constant>(Op0)) |
| if (LHS->isNullValue()) |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| |
| if (isa<UndefValue>(Op0)) { // undef % X -> 0 |
| if (I.getType()->isFPOrFPVector()) |
| return ReplaceInstUsesWith(I, Op0); // X % undef -> undef (could be SNaN) |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| } |
| if (isa<UndefValue>(Op1)) |
| return ReplaceInstUsesWith(I, Op1); // X % undef -> undef |
| |
| // Handle cases involving: rem X, (select Cond, Y, Z) |
| if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I)) |
| return &I; |
| |
| return 0; |
| } |
| |
| /// This function implements the transforms common to both integer remainder |
| /// instructions (urem and srem). It is called by the visitors to those integer |
| /// remainder instructions. |
| /// @brief Common integer remainder transforms |
| Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) { |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| if (Instruction *common = commonRemTransforms(I)) |
| return common; |
| |
| if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) { |
| // X % 0 == undef, we don't need to preserve faults! |
| if (RHS->equalsInt(0)) |
| return ReplaceInstUsesWith(I, UndefValue::get(I.getType())); |
| |
| if (RHS->equalsInt(1)) // X % 1 == 0 |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| |
| if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) { |
| if (SelectInst *SI = dyn_cast<SelectInst>(Op0I)) { |
| if (Instruction *R = FoldOpIntoSelect(I, SI, this)) |
| return R; |
| } else if (isa<PHINode>(Op0I)) { |
| if (Instruction *NV = FoldOpIntoPhi(I)) |
| return NV; |
| } |
| |
| // See if we can fold away this rem instruction. |
| uint32_t BitWidth = cast<IntegerType>(I.getType())->getBitWidth(); |
| APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0); |
| if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(BitWidth), |
| KnownZero, KnownOne)) |
| return &I; |
| } |
| } |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitURem(BinaryOperator &I) { |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| if (Instruction *common = commonIRemTransforms(I)) |
| return common; |
| |
| if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) { |
| // X urem C^2 -> X and C |
| // Check to see if this is an unsigned remainder with an exact power of 2, |
| // if so, convert to a bitwise and. |
| if (ConstantInt *C = dyn_cast<ConstantInt>(RHS)) |
| if (C->getValue().isPowerOf2()) |
| return BinaryOperator::CreateAnd(Op0, SubOne(C)); |
| } |
| |
| if (Instruction *RHSI = dyn_cast<Instruction>(I.getOperand(1))) { |
| // Turn A % (C << N), where C is 2^k, into A & ((C << N)-1) |
| if (RHSI->getOpcode() == Instruction::Shl && |
| isa<ConstantInt>(RHSI->getOperand(0))) { |
| if (cast<ConstantInt>(RHSI->getOperand(0))->getValue().isPowerOf2()) { |
| Constant *N1 = ConstantInt::getAllOnesValue(I.getType()); |
| Value *Add = InsertNewInstBefore(BinaryOperator::CreateAdd(RHSI, N1, |
| "tmp"), I); |
| return BinaryOperator::CreateAnd(Op0, Add); |
| } |
| } |
| } |
| |
| // urem X, (select Cond, 2^C1, 2^C2) --> select Cond, (and X, C1), (and X, C2) |
| // where C1&C2 are powers of two. |
| if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) { |
| if (ConstantInt *STO = dyn_cast<ConstantInt>(SI->getOperand(1))) |
| if (ConstantInt *SFO = dyn_cast<ConstantInt>(SI->getOperand(2))) { |
| // STO == 0 and SFO == 0 handled above. |
| if ((STO->getValue().isPowerOf2()) && |
| (SFO->getValue().isPowerOf2())) { |
| Value *TrueAnd = InsertNewInstBefore( |
| BinaryOperator::CreateAnd(Op0, SubOne(STO), SI->getName()+".t"), I); |
| Value *FalseAnd = InsertNewInstBefore( |
| BinaryOperator::CreateAnd(Op0, SubOne(SFO), SI->getName()+".f"), I); |
| return SelectInst::Create(SI->getOperand(0), TrueAnd, FalseAnd); |
| } |
| } |
| } |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitSRem(BinaryOperator &I) { |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| // Handle the integer rem common cases |
| if (Instruction *common = commonIRemTransforms(I)) |
| return common; |
| |
| if (Value *RHSNeg = dyn_castNegVal(Op1)) |
| if (!isa<Constant>(RHSNeg) || |
| (isa<ConstantInt>(RHSNeg) && |
| cast<ConstantInt>(RHSNeg)->getValue().isStrictlyPositive())) { |
| // X % -Y -> X % Y |
| AddUsesToWorkList(I); |
| I.setOperand(1, RHSNeg); |
| return &I; |
| } |
| |
| // If the sign bits of both operands are zero (i.e. we can prove they are |
| // unsigned inputs), turn this into a urem. |
| if (I.getType()->isInteger()) { |
| APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits())); |
| if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) { |
| // X srem Y -> X urem Y, iff X and Y don't have sign bit set |
| return BinaryOperator::CreateURem(Op0, Op1, I.getName()); |
| } |
| } |
| |
| // If it's a constant vector, flip any negative values positive. |
| if (ConstantVector *RHSV = dyn_cast<ConstantVector>(Op1)) { |
| unsigned VWidth = RHSV->getNumOperands(); |
| |
| bool hasNegative = false; |
| for (unsigned i = 0; !hasNegative && i != VWidth; ++i) |
| if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i))) |
| if (RHS->getValue().isNegative()) |
| hasNegative = true; |
| |
| if (hasNegative) { |
| std::vector<Constant *> Elts(VWidth); |
| for (unsigned i = 0; i != VWidth; ++i) { |
| if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i))) { |
| if (RHS->getValue().isNegative()) |
| Elts[i] = cast<ConstantInt>(ConstantExpr::getNeg(RHS)); |
| else |
| Elts[i] = RHS; |
| } |
| } |
| |
| Constant *NewRHSV = ConstantVector::get(Elts); |
| if (NewRHSV != RHSV) { |
| AddUsesToWorkList(I); |
| I.setOperand(1, NewRHSV); |
| return &I; |
| } |
| } |
| } |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitFRem(BinaryOperator &I) { |
| return commonRemTransforms(I); |
| } |
| |
| // isOneBitSet - Return true if there is exactly one bit set in the specified |
| // constant. |
| static bool isOneBitSet(const ConstantInt *CI) { |
| return CI->getValue().isPowerOf2(); |
| } |
| |
| // isHighOnes - Return true if the constant is of the form 1+0+. |
| // This is the same as lowones(~X). |
| static bool isHighOnes(const ConstantInt *CI) { |
| return (~CI->getValue() + 1).isPowerOf2(); |
| } |
| |
| /// getICmpCode - Encode a icmp predicate into a three bit mask. These bits |
| /// are carefully arranged to allow folding of expressions such as: |
| /// |
| /// (A < B) | (A > B) --> (A != B) |
| /// |
| /// Note that this is only valid if the first and second predicates have the |
| /// same sign. Is illegal to do: (A u< B) | (A s> B) |
| /// |
| /// Three bits are used to represent the condition, as follows: |
| /// 0 A > B |
| /// 1 A == B |
| /// 2 A < B |
| /// |
| /// <=> Value Definition |
| /// 000 0 Always false |
| /// 001 1 A > B |
| /// 010 2 A == B |
| /// 011 3 A >= B |
| /// 100 4 A < B |
| /// 101 5 A != B |
| /// 110 6 A <= B |
| /// 111 7 Always true |
| /// |
| static unsigned getICmpCode(const ICmpInst *ICI) { |
| switch (ICI->getPredicate()) { |
| // False -> 0 |
| case ICmpInst::ICMP_UGT: return 1; // 001 |
| case ICmpInst::ICMP_SGT: return 1; // 001 |
| case ICmpInst::ICMP_EQ: return 2; // 010 |
| case ICmpInst::ICMP_UGE: return 3; // 011 |
| case ICmpInst::ICMP_SGE: return 3; // 011 |
| case ICmpInst::ICMP_ULT: return 4; // 100 |
| case ICmpInst::ICMP_SLT: return 4; // 100 |
| case ICmpInst::ICMP_NE: return 5; // 101 |
| case ICmpInst::ICMP_ULE: return 6; // 110 |
| case ICmpInst::ICMP_SLE: return 6; // 110 |
| // True -> 7 |
| default: |
| assert(0 && "Invalid ICmp predicate!"); |
| return 0; |
| } |
| } |
| |
| /// getFCmpCode - Similar to getICmpCode but for FCmpInst. This encodes a fcmp |
| /// predicate into a three bit mask. It also returns whether it is an ordered |
| /// predicate by reference. |
| static unsigned getFCmpCode(FCmpInst::Predicate CC, bool &isOrdered) { |
| isOrdered = false; |
| switch (CC) { |
| case FCmpInst::FCMP_ORD: isOrdered = true; return 0; // 000 |
| case FCmpInst::FCMP_UNO: return 0; // 000 |
| case FCmpInst::FCMP_OGT: isOrdered = true; return 1; // 001 |
| case FCmpInst::FCMP_UGT: return 1; // 001 |
| case FCmpInst::FCMP_OEQ: isOrdered = true; return 2; // 010 |
| case FCmpInst::FCMP_UEQ: return 2; // 010 |
| case FCmpInst::FCMP_OGE: isOrdered = true; return 3; // 011 |
| case FCmpInst::FCMP_UGE: return 3; // 011 |
| case FCmpInst::FCMP_OLT: isOrdered = true; return 4; // 100 |
| case FCmpInst::FCMP_ULT: return 4; // 100 |
| case FCmpInst::FCMP_ONE: isOrdered = true; return 5; // 101 |
| case FCmpInst::FCMP_UNE: return 5; // 101 |
| case FCmpInst::FCMP_OLE: isOrdered = true; return 6; // 110 |
| case FCmpInst::FCMP_ULE: return 6; // 110 |
| // True -> 7 |
| default: |
| // Not expecting FCMP_FALSE and FCMP_TRUE; |
| assert(0 && "Unexpected FCmp predicate!"); |
| return 0; |
| } |
| } |
| |
| /// getICmpValue - This is the complement of getICmpCode, which turns an |
| /// opcode and two operands into either a constant true or false, or a brand |
| /// new ICmp instruction. The sign is passed in to determine which kind |
| /// of predicate to use in the new icmp instruction. |
| static Value *getICmpValue(bool sign, unsigned code, Value *LHS, Value *RHS) { |
| switch (code) { |
| default: assert(0 && "Illegal ICmp code!"); |
| case 0: return ConstantInt::getFalse(); |
| case 1: |
| if (sign) |
| return new ICmpInst(ICmpInst::ICMP_SGT, LHS, RHS); |
| else |
| return new ICmpInst(ICmpInst::ICMP_UGT, LHS, RHS); |
| case 2: return new ICmpInst(ICmpInst::ICMP_EQ, LHS, RHS); |
| case 3: |
| if (sign) |
| return new ICmpInst(ICmpInst::ICMP_SGE, LHS, RHS); |
| else |
| return new ICmpInst(ICmpInst::ICMP_UGE, LHS, RHS); |
| case 4: |
| if (sign) |
| return new ICmpInst(ICmpInst::ICMP_SLT, LHS, RHS); |
| else |
| return new ICmpInst(ICmpInst::ICMP_ULT, LHS, RHS); |
| case 5: return new ICmpInst(ICmpInst::ICMP_NE, LHS, RHS); |
| case 6: |
| if (sign) |
| return new ICmpInst(ICmpInst::ICMP_SLE, LHS, RHS); |
| else |
| return new ICmpInst(ICmpInst::ICMP_ULE, LHS, RHS); |
| case 7: return ConstantInt::getTrue(); |
| } |
| } |
| |
| /// getFCmpValue - This is the complement of getFCmpCode, which turns an |
| /// opcode and two operands into either a FCmp instruction. isordered is passed |
| /// in to determine which kind of predicate to use in the new fcmp instruction. |
| static Value *getFCmpValue(bool isordered, unsigned code, |
| Value *LHS, Value *RHS) { |
| switch (code) { |
| default: assert(0 && "Illegal FCmp code!"); |
| case 0: |
| if (isordered) |
| return new FCmpInst(FCmpInst::FCMP_ORD, LHS, RHS); |
| else |
| return new FCmpInst(FCmpInst::FCMP_UNO, LHS, RHS); |
| case 1: |
| if (isordered) |
| return new FCmpInst(FCmpInst::FCMP_OGT, LHS, RHS); |
| else |
| return new FCmpInst(FCmpInst::FCMP_UGT, LHS, RHS); |
| case 2: |
| if (isordered) |
| return new FCmpInst(FCmpInst::FCMP_OEQ, LHS, RHS); |
| else |
| return new FCmpInst(FCmpInst::FCMP_UEQ, LHS, RHS); |
| case 3: |
| if (isordered) |
| return new FCmpInst(FCmpInst::FCMP_OGE, LHS, RHS); |
| else |
| return new FCmpInst(FCmpInst::FCMP_UGE, LHS, RHS); |
| case 4: |
| if (isordered) |
| return new FCmpInst(FCmpInst::FCMP_OLT, LHS, RHS); |
| else |
| return new FCmpInst(FCmpInst::FCMP_ULT, LHS, RHS); |
| case 5: |
| if (isordered) |
| return new FCmpInst(FCmpInst::FCMP_ONE, LHS, RHS); |
| else |
| return new FCmpInst(FCmpInst::FCMP_UNE, LHS, RHS); |
| case 6: |
| if (isordered) |
| return new FCmpInst(FCmpInst::FCMP_OLE, LHS, RHS); |
| else |
| return new FCmpInst(FCmpInst::FCMP_ULE, LHS, RHS); |
| case 7: return ConstantInt::getTrue(); |
| } |
| } |
| |
| /// PredicatesFoldable - Return true if both predicates match sign or if at |
| /// least one of them is an equality comparison (which is signless). |
| static bool PredicatesFoldable(ICmpInst::Predicate p1, ICmpInst::Predicate p2) { |
| return (ICmpInst::isSignedPredicate(p1) == ICmpInst::isSignedPredicate(p2)) || |
| (ICmpInst::isSignedPredicate(p1) && ICmpInst::isEquality(p2)) || |
| (ICmpInst::isSignedPredicate(p2) && ICmpInst::isEquality(p1)); |
| } |
| |
| namespace { |
| // FoldICmpLogical - Implements (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B) |
| struct FoldICmpLogical { |
| InstCombiner &IC; |
| Value *LHS, *RHS; |
| ICmpInst::Predicate pred; |
| FoldICmpLogical(InstCombiner &ic, ICmpInst *ICI) |
| : IC(ic), LHS(ICI->getOperand(0)), RHS(ICI->getOperand(1)), |
| pred(ICI->getPredicate()) {} |
| bool shouldApply(Value *V) const { |
| if (ICmpInst *ICI = dyn_cast<ICmpInst>(V)) |
| if (PredicatesFoldable(pred, ICI->getPredicate())) |
| return ((ICI->getOperand(0) == LHS && ICI->getOperand(1) == RHS) || |
| (ICI->getOperand(0) == RHS && ICI->getOperand(1) == LHS)); |
| return false; |
| } |
| Instruction *apply(Instruction &Log) const { |
| ICmpInst *ICI = cast<ICmpInst>(Log.getOperand(0)); |
| if (ICI->getOperand(0) != LHS) { |
| assert(ICI->getOperand(1) == LHS); |
| ICI->swapOperands(); // Swap the LHS and RHS of the ICmp |
| } |
| |
| ICmpInst *RHSICI = cast<ICmpInst>(Log.getOperand(1)); |
| unsigned LHSCode = getICmpCode(ICI); |
| unsigned RHSCode = getICmpCode(RHSICI); |
| unsigned Code; |
| switch (Log.getOpcode()) { |
| case Instruction::And: Code = LHSCode & RHSCode; break; |
| case Instruction::Or: Code = LHSCode | RHSCode; break; |
| case Instruction::Xor: Code = LHSCode ^ RHSCode; break; |
| default: assert(0 && "Illegal logical opcode!"); return 0; |
| } |
| |
| bool isSigned = ICmpInst::isSignedPredicate(RHSICI->getPredicate()) || |
| ICmpInst::isSignedPredicate(ICI->getPredicate()); |
| |
| Value *RV = getICmpValue(isSigned, Code, LHS, RHS); |
| if (Instruction *I = dyn_cast<Instruction>(RV)) |
| return I; |
| // Otherwise, it's a constant boolean value... |
| return IC.ReplaceInstUsesWith(Log, RV); |
| } |
| }; |
| } // end anonymous namespace |
| |
| // OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where |
| // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is |
| // guaranteed to be a binary operator. |
| Instruction *InstCombiner::OptAndOp(Instruction *Op, |
| ConstantInt *OpRHS, |
| ConstantInt *AndRHS, |
| BinaryOperator &TheAnd) { |
| Value *X = Op->getOperand(0); |
| Constant *Together = 0; |
| if (!Op->isShift()) |
| Together = And(AndRHS, OpRHS); |
| |
| switch (Op->getOpcode()) { |
| case Instruction::Xor: |
| if (Op->hasOneUse()) { |
| // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2) |
| Instruction *And = BinaryOperator::CreateAnd(X, AndRHS); |
| InsertNewInstBefore(And, TheAnd); |
| And->takeName(Op); |
| return BinaryOperator::CreateXor(And, Together); |
| } |
| break; |
| case Instruction::Or: |
| if (Together == AndRHS) // (X | C) & C --> C |
| return ReplaceInstUsesWith(TheAnd, AndRHS); |
| |
| if (Op->hasOneUse() && Together != OpRHS) { |
| // (X | C1) & C2 --> (X | (C1&C2)) & C2 |
| Instruction *Or = BinaryOperator::CreateOr(X, Together); |
| InsertNewInstBefore(Or, TheAnd); |
| Or->takeName(Op); |
| return BinaryOperator::CreateAnd(Or, AndRHS); |
| } |
| break; |
| case Instruction::Add: |
| if (Op->hasOneUse()) { |
| // Adding a one to a single bit bit-field should be turned into an XOR |
| // of the bit. First thing to check is to see if this AND is with a |
| // single bit constant. |
| const APInt& AndRHSV = cast<ConstantInt>(AndRHS)->getValue(); |
| |
| // If there is only one bit set... |
| if (isOneBitSet(cast<ConstantInt>(AndRHS))) { |
| // Ok, at this point, we know that we are masking the result of the |
| // ADD down to exactly one bit. If the constant we are adding has |
| // no bits set below this bit, then we can eliminate the ADD. |
| const APInt& AddRHS = cast<ConstantInt>(OpRHS)->getValue(); |
| |
| // Check to see if any bits below the one bit set in AndRHSV are set. |
| if ((AddRHS & (AndRHSV-1)) == 0) { |
| // If not, the only thing that can effect the output of the AND is |
| // the bit specified by AndRHSV. If that bit is set, the effect of |
| // the XOR is to toggle the bit. If it is clear, then the ADD has |
| // no effect. |
| if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop |
| TheAnd.setOperand(0, X); |
| return &TheAnd; |
| } else { |
| // Pull the XOR out of the AND. |
| Instruction *NewAnd = BinaryOperator::CreateAnd(X, AndRHS); |
| InsertNewInstBefore(NewAnd, TheAnd); |
| NewAnd->takeName(Op); |
| return BinaryOperator::CreateXor(NewAnd, AndRHS); |
| } |
| } |
| } |
| } |
| break; |
| |
| case Instruction::Shl: { |
| // We know that the AND will not produce any of the bits shifted in, so if |
| // the anded constant includes them, clear them now! |
| // |
| uint32_t BitWidth = AndRHS->getType()->getBitWidth(); |
| uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth); |
| APInt ShlMask(APInt::getHighBitsSet(BitWidth, BitWidth-OpRHSVal)); |
| ConstantInt *CI = ConstantInt::get(AndRHS->getValue() & ShlMask); |
| |
| if (CI->getValue() == ShlMask) { |
| // Masking out bits that the shift already masks |
| return ReplaceInstUsesWith(TheAnd, Op); // No need for the and. |
| } else if (CI != AndRHS) { // Reducing bits set in and. |
| TheAnd.setOperand(1, CI); |
| return &TheAnd; |
| } |
| break; |
| } |
| case Instruction::LShr: |
| { |
| // We know that the AND will not produce any of the bits shifted in, so if |
| // the anded constant includes them, clear them now! This only applies to |
| // unsigned shifts, because a signed shr may bring in set bits! |
| // |
| uint32_t BitWidth = AndRHS->getType()->getBitWidth(); |
| uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth); |
| APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal)); |
| ConstantInt *CI = ConstantInt::get(AndRHS->getValue() & ShrMask); |
| |
| if (CI->getValue() == ShrMask) { |
| // Masking out bits that the shift already masks. |
| return ReplaceInstUsesWith(TheAnd, Op); |
| } else if (CI != AndRHS) { |
| TheAnd.setOperand(1, CI); // Reduce bits set in and cst. |
| return &TheAnd; |
| } |
| break; |
| } |
| case Instruction::AShr: |
| // Signed shr. |
| // See if this is shifting in some sign extension, then masking it out |
| // with an and. |
| if (Op->hasOneUse()) { |
| uint32_t BitWidth = AndRHS->getType()->getBitWidth(); |
| uint32_t OpRHSVal = OpRHS->getLimitedValue(BitWidth); |
| APInt ShrMask(APInt::getLowBitsSet(BitWidth, BitWidth - OpRHSVal)); |
| Constant *C = ConstantInt::get(AndRHS->getValue() & ShrMask); |
| if (C == AndRHS) { // Masking out bits shifted in. |
| // (Val ashr C1) & C2 -> (Val lshr C1) & C2 |
| // Make the argument unsigned. |
| Value *ShVal = Op->getOperand(0); |
| ShVal = InsertNewInstBefore( |
| BinaryOperator::CreateLShr(ShVal, OpRHS, |
| Op->getName()), TheAnd); |
| return BinaryOperator::CreateAnd(ShVal, AndRHS, TheAnd.getName()); |
| } |
| } |
| break; |
| } |
| return 0; |
| } |
| |
| |
| /// InsertRangeTest - Emit a computation of: (V >= Lo && V < Hi) if Inside is |
| /// true, otherwise (V < Lo || V >= Hi). In pratice, we emit the more efficient |
| /// (V-Lo) <u Hi-Lo. This method expects that Lo <= Hi. isSigned indicates |
| /// whether to treat the V, Lo and HI as signed or not. IB is the location to |
| /// insert new instructions. |
| Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi, |
| bool isSigned, bool Inside, |
| Instruction &IB) { |
| assert(cast<ConstantInt>(ConstantExpr::getICmp((isSigned ? |
| ICmpInst::ICMP_SLE:ICmpInst::ICMP_ULE), Lo, Hi))->getZExtValue() && |
| "Lo is not <= Hi in range emission code!"); |
| |
| if (Inside) { |
| if (Lo == Hi) // Trivially false. |
| return new ICmpInst(ICmpInst::ICMP_NE, V, V); |
| |
| // V >= Min && V < Hi --> V < Hi |
| if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) { |
| ICmpInst::Predicate pred = (isSigned ? |
| ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT); |
| return new ICmpInst(pred, V, Hi); |
| } |
| |
| // Emit V-Lo <u Hi-Lo |
| Constant *NegLo = ConstantExpr::getNeg(Lo); |
| Instruction *Add = BinaryOperator::CreateAdd(V, NegLo, V->getName()+".off"); |
| InsertNewInstBefore(Add, IB); |
| Constant *UpperBound = ConstantExpr::getAdd(NegLo, Hi); |
| return new ICmpInst(ICmpInst::ICMP_ULT, Add, UpperBound); |
| } |
| |
| if (Lo == Hi) // Trivially true. |
| return new ICmpInst(ICmpInst::ICMP_EQ, V, V); |
| |
| // V < Min || V >= Hi -> V > Hi-1 |
| Hi = SubOne(cast<ConstantInt>(Hi)); |
| if (cast<ConstantInt>(Lo)->isMinValue(isSigned)) { |
| ICmpInst::Predicate pred = (isSigned ? |
| ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT); |
| return new ICmpInst(pred, V, Hi); |
| } |
| |
| // Emit V-Lo >u Hi-1-Lo |
| // Note that Hi has already had one subtracted from it, above. |
| ConstantInt *NegLo = cast<ConstantInt>(ConstantExpr::getNeg(Lo)); |
| Instruction *Add = BinaryOperator::CreateAdd(V, NegLo, V->getName()+".off"); |
| InsertNewInstBefore(Add, IB); |
| Constant *LowerBound = ConstantExpr::getAdd(NegLo, Hi); |
| return new ICmpInst(ICmpInst::ICMP_UGT, Add, LowerBound); |
| } |
| |
| // isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with |
| // any number of 0s on either side. The 1s are allowed to wrap from LSB to |
| // MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is |
| // not, since all 1s are not contiguous. |
| static bool isRunOfOnes(ConstantInt *Val, uint32_t &MB, uint32_t &ME) { |
| const APInt& V = Val->getValue(); |
| uint32_t BitWidth = Val->getType()->getBitWidth(); |
| if (!APIntOps::isShiftedMask(BitWidth, V)) return false; |
| |
| // look for the first zero bit after the run of ones |
| MB = BitWidth - ((V - 1) ^ V).countLeadingZeros(); |
| // look for the first non-zero bit |
| ME = V.getActiveBits(); |
| return true; |
| } |
| |
| /// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask, |
| /// where isSub determines whether the operator is a sub. If we can fold one of |
| /// the following xforms: |
| /// |
| /// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask |
| /// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0 |
| /// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0 |
| /// |
| /// return (A +/- B). |
| /// |
| Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS, |
| ConstantInt *Mask, bool isSub, |
| Instruction &I) { |
| Instruction *LHSI = dyn_cast<Instruction>(LHS); |
| if (!LHSI || LHSI->getNumOperands() != 2 || |
| !isa<ConstantInt>(LHSI->getOperand(1))) return 0; |
| |
| ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1)); |
| |
| switch (LHSI->getOpcode()) { |
| default: return 0; |
| case Instruction::And: |
| if (And(N, Mask) == Mask) { |
| // If the AndRHS is a power of two minus one (0+1+), this is simple. |
| if ((Mask->getValue().countLeadingZeros() + |
| Mask->getValue().countPopulation()) == |
| Mask->getValue().getBitWidth()) |
| break; |
| |
| // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+ |
| // part, we don't need any explicit masks to take them out of A. If that |
| // is all N is, ignore it. |
| uint32_t MB = 0, ME = 0; |
| if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive |
| uint32_t BitWidth = cast<IntegerType>(RHS->getType())->getBitWidth(); |
| APInt Mask(APInt::getLowBitsSet(BitWidth, MB-1)); |
| if (MaskedValueIsZero(RHS, Mask)) |
| break; |
| } |
| } |
| return 0; |
| case Instruction::Or: |
| case Instruction::Xor: |
| // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0 |
| if ((Mask->getValue().countLeadingZeros() + |
| Mask->getValue().countPopulation()) == Mask->getValue().getBitWidth() |
| && And(N, Mask)->isZero()) |
| break; |
| return 0; |
| } |
| |
| Instruction *New; |
| if (isSub) |
| New = BinaryOperator::CreateSub(LHSI->getOperand(0), RHS, "fold"); |
| else |
| New = BinaryOperator::CreateAdd(LHSI->getOperand(0), RHS, "fold"); |
| return InsertNewInstBefore(New, I); |
| } |
| |
| /// FoldAndOfICmps - Fold (icmp)&(icmp) if possible. |
| Instruction *InstCombiner::FoldAndOfICmps(Instruction &I, |
| ICmpInst *LHS, ICmpInst *RHS) { |
| Value *Val, *Val2; |
| ConstantInt *LHSCst, *RHSCst; |
| ICmpInst::Predicate LHSCC, RHSCC; |
| |
| // This only handles icmp of constants: (icmp1 A, C1) & (icmp2 B, C2). |
| if (!match(LHS, m_ICmp(LHSCC, m_Value(Val), m_ConstantInt(LHSCst))) || |
| !match(RHS, m_ICmp(RHSCC, m_Value(Val2), m_ConstantInt(RHSCst)))) |
| return 0; |
| |
| // (icmp ult A, C) & (icmp ult B, C) --> (icmp ult (A|B), C) |
| // where C is a power of 2 |
| if (LHSCst == RHSCst && LHSCC == RHSCC && LHSCC == ICmpInst::ICMP_ULT && |
| LHSCst->getValue().isPowerOf2()) { |
| Instruction *NewOr = BinaryOperator::CreateOr(Val, Val2); |
| InsertNewInstBefore(NewOr, I); |
| return new ICmpInst(LHSCC, NewOr, LHSCst); |
| } |
| |
| // From here on, we only handle: |
| // (icmp1 A, C1) & (icmp2 A, C2) --> something simpler. |
| if (Val != Val2) return 0; |
| |
| // ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere. |
| if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE || |
| RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE || |
| LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE || |
| RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE) |
| return 0; |
| |
| // We can't fold (ugt x, C) & (sgt x, C2). |
| if (!PredicatesFoldable(LHSCC, RHSCC)) |
| return 0; |
| |
| // Ensure that the larger constant is on the RHS. |
| bool ShouldSwap; |
| if (ICmpInst::isSignedPredicate(LHSCC) || |
| (ICmpInst::isEquality(LHSCC) && |
| ICmpInst::isSignedPredicate(RHSCC))) |
| ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue()); |
| else |
| ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue()); |
| |
| if (ShouldSwap) { |
| std::swap(LHS, RHS); |
| std::swap(LHSCst, RHSCst); |
| std::swap(LHSCC, RHSCC); |
| } |
| |
| // At this point, we know we have have two icmp instructions |
| // comparing a value against two constants and and'ing the result |
| // together. Because of the above check, we know that we only have |
| // icmp eq, icmp ne, icmp [su]lt, and icmp [SU]gt here. We also know |
| // (from the FoldICmpLogical check above), that the two constants |
| // are not equal and that the larger constant is on the RHS |
| assert(LHSCst != RHSCst && "Compares not folded above?"); |
| |
| switch (LHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case ICmpInst::ICMP_EQ: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case ICmpInst::ICMP_EQ: // (X == 13 & X == 15) -> false |
| case ICmpInst::ICMP_UGT: // (X == 13 & X > 15) -> false |
| case ICmpInst::ICMP_SGT: // (X == 13 & X > 15) -> false |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| case ICmpInst::ICMP_NE: // (X == 13 & X != 15) -> X == 13 |
| case ICmpInst::ICMP_ULT: // (X == 13 & X < 15) -> X == 13 |
| case ICmpInst::ICMP_SLT: // (X == 13 & X < 15) -> X == 13 |
| return ReplaceInstUsesWith(I, LHS); |
| } |
| case ICmpInst::ICMP_NE: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case ICmpInst::ICMP_ULT: |
| if (LHSCst == SubOne(RHSCst)) // (X != 13 & X u< 14) -> X < 13 |
| return new ICmpInst(ICmpInst::ICMP_ULT, Val, LHSCst); |
| break; // (X != 13 & X u< 15) -> no change |
| case ICmpInst::ICMP_SLT: |
| if (LHSCst == SubOne(RHSCst)) // (X != 13 & X s< 14) -> X < 13 |
| return new ICmpInst(ICmpInst::ICMP_SLT, Val, LHSCst); |
| break; // (X != 13 & X s< 15) -> no change |
| case ICmpInst::ICMP_EQ: // (X != 13 & X == 15) -> X == 15 |
| case ICmpInst::ICMP_UGT: // (X != 13 & X u> 15) -> X u> 15 |
| case ICmpInst::ICMP_SGT: // (X != 13 & X s> 15) -> X s> 15 |
| return ReplaceInstUsesWith(I, RHS); |
| case ICmpInst::ICMP_NE: |
| if (LHSCst == SubOne(RHSCst)){// (X != 13 & X != 14) -> X-13 >u 1 |
| Constant *AddCST = ConstantExpr::getNeg(LHSCst); |
| Instruction *Add = BinaryOperator::CreateAdd(Val, AddCST, |
| Val->getName()+".off"); |
| InsertNewInstBefore(Add, I); |
| return new ICmpInst(ICmpInst::ICMP_UGT, Add, |
| ConstantInt::get(Add->getType(), 1)); |
| } |
| break; // (X != 13 & X != 15) -> no change |
| } |
| break; |
| case ICmpInst::ICMP_ULT: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case ICmpInst::ICMP_EQ: // (X u< 13 & X == 15) -> false |
| case ICmpInst::ICMP_UGT: // (X u< 13 & X u> 15) -> false |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| case ICmpInst::ICMP_SGT: // (X u< 13 & X s> 15) -> no change |
| break; |
| case ICmpInst::ICMP_NE: // (X u< 13 & X != 15) -> X u< 13 |
| case ICmpInst::ICMP_ULT: // (X u< 13 & X u< 15) -> X u< 13 |
| return ReplaceInstUsesWith(I, LHS); |
| case ICmpInst::ICMP_SLT: // (X u< 13 & X s< 15) -> no change |
| break; |
| } |
| break; |
| case ICmpInst::ICMP_SLT: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case ICmpInst::ICMP_EQ: // (X s< 13 & X == 15) -> false |
| case ICmpInst::ICMP_SGT: // (X s< 13 & X s> 15) -> false |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| case ICmpInst::ICMP_UGT: // (X s< 13 & X u> 15) -> no change |
| break; |
| case ICmpInst::ICMP_NE: // (X s< 13 & X != 15) -> X < 13 |
| case ICmpInst::ICMP_SLT: // (X s< 13 & X s< 15) -> X < 13 |
| return ReplaceInstUsesWith(I, LHS); |
| case ICmpInst::ICMP_ULT: // (X s< 13 & X u< 15) -> no change |
| break; |
| } |
| break; |
| case ICmpInst::ICMP_UGT: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case ICmpInst::ICMP_EQ: // (X u> 13 & X == 15) -> X == 15 |
| case ICmpInst::ICMP_UGT: // (X u> 13 & X u> 15) -> X u> 15 |
| return ReplaceInstUsesWith(I, RHS); |
| case ICmpInst::ICMP_SGT: // (X u> 13 & X s> 15) -> no change |
| break; |
| case ICmpInst::ICMP_NE: |
| if (RHSCst == AddOne(LHSCst)) // (X u> 13 & X != 14) -> X u> 14 |
| return new ICmpInst(LHSCC, Val, RHSCst); |
| break; // (X u> 13 & X != 15) -> no change |
| case ICmpInst::ICMP_ULT: // (X u> 13 & X u< 15) -> (X-14) <u 1 |
| return InsertRangeTest(Val, AddOne(LHSCst), RHSCst, false, true, I); |
| case ICmpInst::ICMP_SLT: // (X u> 13 & X s< 15) -> no change |
| break; |
| } |
| break; |
| case ICmpInst::ICMP_SGT: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case ICmpInst::ICMP_EQ: // (X s> 13 & X == 15) -> X == 15 |
| case ICmpInst::ICMP_SGT: // (X s> 13 & X s> 15) -> X s> 15 |
| return ReplaceInstUsesWith(I, RHS); |
| case ICmpInst::ICMP_UGT: // (X s> 13 & X u> 15) -> no change |
| break; |
| case ICmpInst::ICMP_NE: |
| if (RHSCst == AddOne(LHSCst)) // (X s> 13 & X != 14) -> X s> 14 |
| return new ICmpInst(LHSCC, Val, RHSCst); |
| break; // (X s> 13 & X != 15) -> no change |
| case ICmpInst::ICMP_SLT: // (X s> 13 & X s< 15) -> (X-14) s< 1 |
| return InsertRangeTest(Val, AddOne(LHSCst), RHSCst, true, true, I); |
| case ICmpInst::ICMP_ULT: // (X s> 13 & X u< 15) -> no change |
| break; |
| } |
| break; |
| } |
| |
| return 0; |
| } |
| |
| |
| Instruction *InstCombiner::visitAnd(BinaryOperator &I) { |
| bool Changed = SimplifyCommutative(I); |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| if (isa<UndefValue>(Op1)) // X & undef -> 0 |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| |
| // and X, X = X |
| if (Op0 == Op1) |
| return ReplaceInstUsesWith(I, Op1); |
| |
| // See if we can simplify any instructions used by the instruction whose sole |
| // purpose is to compute bits we don't care about. |
| if (!isa<VectorType>(I.getType())) { |
| uint32_t BitWidth = cast<IntegerType>(I.getType())->getBitWidth(); |
| APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0); |
| if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(BitWidth), |
| KnownZero, KnownOne)) |
| return &I; |
| } else { |
| if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1)) { |
| if (CP->isAllOnesValue()) // X & <-1,-1> -> X |
| return ReplaceInstUsesWith(I, I.getOperand(0)); |
| } else if (isa<ConstantAggregateZero>(Op1)) { |
| return ReplaceInstUsesWith(I, Op1); // X & <0,0> -> <0,0> |
| } |
| } |
| |
| if (ConstantInt *AndRHS = dyn_cast<ConstantInt>(Op1)) { |
| const APInt& AndRHSMask = AndRHS->getValue(); |
| APInt NotAndRHS(~AndRHSMask); |
| |
| // Optimize a variety of ((val OP C1) & C2) combinations... |
| if (isa<BinaryOperator>(Op0)) { |
| Instruction *Op0I = cast<Instruction>(Op0); |
| Value *Op0LHS = Op0I->getOperand(0); |
| Value *Op0RHS = Op0I->getOperand(1); |
| switch (Op0I->getOpcode()) { |
| case Instruction::Xor: |
| case Instruction::Or: |
| // If the mask is only needed on one incoming arm, push it up. |
| if (Op0I->hasOneUse()) { |
| if (MaskedValueIsZero(Op0LHS, NotAndRHS)) { |
| // Not masking anything out for the LHS, move to RHS. |
| Instruction *NewRHS = BinaryOperator::CreateAnd(Op0RHS, AndRHS, |
| Op0RHS->getName()+".masked"); |
| InsertNewInstBefore(NewRHS, I); |
| return BinaryOperator::Create( |
| cast<BinaryOperator>(Op0I)->getOpcode(), Op0LHS, NewRHS); |
| } |
| if (!isa<Constant>(Op0RHS) && |
| MaskedValueIsZero(Op0RHS, NotAndRHS)) { |
| // Not masking anything out for the RHS, move to LHS. |
| Instruction *NewLHS = BinaryOperator::CreateAnd(Op0LHS, AndRHS, |
| Op0LHS->getName()+".masked"); |
| InsertNewInstBefore(NewLHS, I); |
| return BinaryOperator::Create( |
| cast<BinaryOperator>(Op0I)->getOpcode(), NewLHS, Op0RHS); |
| } |
| } |
| |
| break; |
| case Instruction::Add: |
| // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS. |
| // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0 |
| // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0 |
| if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I)) |
| return BinaryOperator::CreateAnd(V, AndRHS); |
| if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I)) |
| return BinaryOperator::CreateAnd(V, AndRHS); // Add commutes |
| break; |
| |
| case Instruction::Sub: |
| // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS. |
| // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0 |
| // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0 |
| if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I)) |
| return BinaryOperator::CreateAnd(V, AndRHS); |
| |
| // (A - N) & AndRHS -> -N & AndRHS iff A&AndRHS==0 and AndRHS |
| // has 1's for all bits that the subtraction with A might affect. |
| if (Op0I->hasOneUse()) { |
| uint32_t BitWidth = AndRHSMask.getBitWidth(); |
| uint32_t Zeros = AndRHSMask.countLeadingZeros(); |
| APInt Mask = APInt::getLowBitsSet(BitWidth, BitWidth - Zeros); |
| |
| ConstantInt *A = dyn_cast<ConstantInt>(Op0LHS); |
| if (!(A && A->isZero()) && // avoid infinite recursion. |
| MaskedValueIsZero(Op0LHS, Mask)) { |
| Instruction *NewNeg = BinaryOperator::CreateNeg(Op0RHS); |
| InsertNewInstBefore(NewNeg, I); |
| return BinaryOperator::CreateAnd(NewNeg, AndRHS); |
| } |
| } |
| break; |
| |
| case Instruction::Shl: |
| case Instruction::LShr: |
| // (1 << x) & 1 --> zext(x == 0) |
| // (1 >> x) & 1 --> zext(x == 0) |
| if (AndRHSMask == 1 && Op0LHS == AndRHS) { |
| Instruction *NewICmp = new ICmpInst(ICmpInst::ICMP_EQ, Op0RHS, |
| Constant::getNullValue(I.getType())); |
| InsertNewInstBefore(NewICmp, I); |
| return new ZExtInst(NewICmp, I.getType()); |
| } |
| break; |
| } |
| |
| if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) |
| if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I)) |
| return Res; |
| } else if (CastInst *CI = dyn_cast<CastInst>(Op0)) { |
| // If this is an integer truncation or change from signed-to-unsigned, and |
| // if the source is an and/or with immediate, transform it. This |
| // frequently occurs for bitfield accesses. |
| if (Instruction *CastOp = dyn_cast<Instruction>(CI->getOperand(0))) { |
| if ((isa<TruncInst>(CI) || isa<BitCastInst>(CI)) && |
| CastOp->getNumOperands() == 2) |
| if (ConstantInt *AndCI = dyn_cast<ConstantInt>(CastOp->getOperand(1))) { |
| if (CastOp->getOpcode() == Instruction::And) { |
| // Change: and (cast (and X, C1) to T), C2 |
| // into : and (cast X to T), trunc_or_bitcast(C1)&C2 |
| // This will fold the two constants together, which may allow |
| // other simplifications. |
| Instruction *NewCast = CastInst::CreateTruncOrBitCast( |
| CastOp->getOperand(0), I.getType(), |
| CastOp->getName()+".shrunk"); |
| NewCast = InsertNewInstBefore(NewCast, I); |
| // trunc_or_bitcast(C1)&C2 |
| Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType()); |
| C3 = ConstantExpr::getAnd(C3, AndRHS); |
| return BinaryOperator::CreateAnd(NewCast, C3); |
| } else if (CastOp->getOpcode() == Instruction::Or) { |
| // Change: and (cast (or X, C1) to T), C2 |
| // into : trunc(C1)&C2 iff trunc(C1)&C2 == C2 |
| Constant *C3 = ConstantExpr::getTruncOrBitCast(AndCI,I.getType()); |
| if (ConstantExpr::getAnd(C3, AndRHS) == AndRHS) // trunc(C1)&C2 |
| return ReplaceInstUsesWith(I, AndRHS); |
| } |
| } |
| } |
| } |
| |
| // Try to fold constant and into select arguments. |
| if (SelectInst *SI = dyn_cast<SelectInst>(Op0)) |
| if (Instruction *R = FoldOpIntoSelect(I, SI, this)) |
| return R; |
| if (isa<PHINode>(Op0)) |
| if (Instruction *NV = FoldOpIntoPhi(I)) |
| return NV; |
| } |
| |
| Value *Op0NotVal = dyn_castNotVal(Op0); |
| Value *Op1NotVal = dyn_castNotVal(Op1); |
| |
| if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0 |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| |
| // (~A & ~B) == (~(A | B)) - De Morgan's Law |
| if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) { |
| Instruction *Or = BinaryOperator::CreateOr(Op0NotVal, Op1NotVal, |
| I.getName()+".demorgan"); |
| InsertNewInstBefore(Or, I); |
| return BinaryOperator::CreateNot(Or); |
| } |
| |
| { |
| Value *A = 0, *B = 0, *C = 0, *D = 0; |
| if (match(Op0, m_Or(m_Value(A), m_Value(B)))) { |
| if (A == Op1 || B == Op1) // (A | ?) & A --> A |
| return ReplaceInstUsesWith(I, Op1); |
| |
| // (A|B) & ~(A&B) -> A^B |
| if (match(Op1, m_Not(m_And(m_Value(C), m_Value(D))))) { |
| if ((A == C && B == D) || (A == D && B == C)) |
| return BinaryOperator::CreateXor(A, B); |
| } |
| } |
| |
| if (match(Op1, m_Or(m_Value(A), m_Value(B)))) { |
| if (A == Op0 || B == Op0) // A & (A | ?) --> A |
| return ReplaceInstUsesWith(I, Op0); |
| |
| // ~(A&B) & (A|B) -> A^B |
| if (match(Op0, m_Not(m_And(m_Value(C), m_Value(D))))) { |
| if ((A == C && B == D) || (A == D && B == C)) |
| return BinaryOperator::CreateXor(A, B); |
| } |
| } |
| |
| if (Op0->hasOneUse() && |
| match(Op0, m_Xor(m_Value(A), m_Value(B)))) { |
| if (A == Op1) { // (A^B)&A -> A&(A^B) |
| I.swapOperands(); // Simplify below |
| std::swap(Op0, Op1); |
| } else if (B == Op1) { // (A^B)&B -> B&(B^A) |
| cast<BinaryOperator>(Op0)->swapOperands(); |
| I.swapOperands(); // Simplify below |
| std::swap(Op0, Op1); |
| } |
| } |
| |
| if (Op1->hasOneUse() && |
| match(Op1, m_Xor(m_Value(A), m_Value(B)))) { |
| if (B == Op0) { // B&(A^B) -> B&(B^A) |
| cast<BinaryOperator>(Op1)->swapOperands(); |
| std::swap(A, B); |
| } |
| if (A == Op0) { // A&(A^B) -> A & ~B |
| Instruction *NotB = BinaryOperator::CreateNot(B, "tmp"); |
| InsertNewInstBefore(NotB, I); |
| return BinaryOperator::CreateAnd(A, NotB); |
| } |
| } |
| |
| // (A&((~A)|B)) -> A&B |
| if (match(Op0, m_Or(m_Not(m_Specific(Op1)), m_Value(A))) || |
| match(Op0, m_Or(m_Value(A), m_Not(m_Specific(Op1))))) |
| return BinaryOperator::CreateAnd(A, Op1); |
| if (match(Op1, m_Or(m_Not(m_Specific(Op0)), m_Value(A))) || |
| match(Op1, m_Or(m_Value(A), m_Not(m_Specific(Op0))))) |
| return BinaryOperator::CreateAnd(A, Op0); |
| } |
| |
| if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1)) { |
| // (icmp1 A, B) & (icmp2 A, B) --> (icmp3 A, B) |
| if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS))) |
| return R; |
| |
| if (ICmpInst *LHS = dyn_cast<ICmpInst>(Op0)) |
| if (Instruction *Res = FoldAndOfICmps(I, LHS, RHS)) |
| return Res; |
| } |
| |
| // fold (and (cast A), (cast B)) -> (cast (and A, B)) |
| if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) |
| if (CastInst *Op1C = dyn_cast<CastInst>(Op1)) |
| if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind ? |
| const Type *SrcTy = Op0C->getOperand(0)->getType(); |
| if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() && |
| // Only do this if the casts both really cause code to be generated. |
| ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0), |
| I.getType(), TD) && |
| ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0), |
| I.getType(), TD)) { |
| Instruction *NewOp = BinaryOperator::CreateAnd(Op0C->getOperand(0), |
| Op1C->getOperand(0), |
| I.getName()); |
| InsertNewInstBefore(NewOp, I); |
| return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType()); |
| } |
| } |
| |
| // (X >> Z) & (Y >> Z) -> (X&Y) >> Z for all shifts. |
| if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) { |
| if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0)) |
| if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() && |
| SI0->getOperand(1) == SI1->getOperand(1) && |
| (SI0->hasOneUse() || SI1->hasOneUse())) { |
| Instruction *NewOp = |
| InsertNewInstBefore(BinaryOperator::CreateAnd(SI0->getOperand(0), |
| SI1->getOperand(0), |
| SI0->getName()), I); |
| return BinaryOperator::Create(SI1->getOpcode(), NewOp, |
| SI1->getOperand(1)); |
| } |
| } |
| |
| // If and'ing two fcmp, try combine them into one. |
| if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) { |
| if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1))) { |
| if (LHS->getPredicate() == FCmpInst::FCMP_ORD && |
| RHS->getPredicate() == FCmpInst::FCMP_ORD) { |
| // (fcmp ord x, c) & (fcmp ord y, c) -> (fcmp ord x, y) |
| if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1))) |
| if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) { |
| // If either of the constants are nans, then the whole thing returns |
| // false. |
| if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN()) |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| return new FCmpInst(FCmpInst::FCMP_ORD, LHS->getOperand(0), |
| RHS->getOperand(0)); |
| } |
| } else { |
| Value *Op0LHS, *Op0RHS, *Op1LHS, *Op1RHS; |
| FCmpInst::Predicate Op0CC, Op1CC; |
| if (match(Op0, m_FCmp(Op0CC, m_Value(Op0LHS), m_Value(Op0RHS))) && |
| match(Op1, m_FCmp(Op1CC, m_Value(Op1LHS), m_Value(Op1RHS)))) { |
| if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) { |
| // Swap RHS operands to match LHS. |
| Op1CC = FCmpInst::getSwappedPredicate(Op1CC); |
| std::swap(Op1LHS, Op1RHS); |
| } |
| if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) { |
| // Simplify (fcmp cc0 x, y) & (fcmp cc1 x, y). |
| if (Op0CC == Op1CC) |
| return new FCmpInst((FCmpInst::Predicate)Op0CC, Op0LHS, Op0RHS); |
| else if (Op0CC == FCmpInst::FCMP_FALSE || |
| Op1CC == FCmpInst::FCMP_FALSE) |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| else if (Op0CC == FCmpInst::FCMP_TRUE) |
| return ReplaceInstUsesWith(I, Op1); |
| else if (Op1CC == FCmpInst::FCMP_TRUE) |
| return ReplaceInstUsesWith(I, Op0); |
| bool Op0Ordered; |
| bool Op1Ordered; |
| unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered); |
| unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered); |
| if (Op1Pred == 0) { |
| std::swap(Op0, Op1); |
| std::swap(Op0Pred, Op1Pred); |
| std::swap(Op0Ordered, Op1Ordered); |
| } |
| if (Op0Pred == 0) { |
| // uno && ueq -> uno && (uno || eq) -> ueq |
| // ord && olt -> ord && (ord && lt) -> olt |
| if (Op0Ordered == Op1Ordered) |
| return ReplaceInstUsesWith(I, Op1); |
| // uno && oeq -> uno && (ord && eq) -> false |
| // uno && ord -> false |
| if (!Op0Ordered) |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| // ord && ueq -> ord && (uno || eq) -> oeq |
| return cast<Instruction>(getFCmpValue(true, Op1Pred, |
| Op0LHS, Op0RHS)); |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| return Changed ? &I : 0; |
| } |
| |
| /// CollectBSwapParts - Analyze the specified subexpression and see if it is |
| /// capable of providing pieces of a bswap. The subexpression provides pieces |
| /// of a bswap if it is proven that each of the non-zero bytes in the output of |
| /// the expression came from the corresponding "byte swapped" byte in some other |
| /// value. For example, if the current subexpression is "(shl i32 %X, 24)" then |
| /// we know that the expression deposits the low byte of %X into the high byte |
| /// of the bswap result and that all other bytes are zero. This expression is |
| /// accepted, the high byte of ByteValues is set to X to indicate a correct |
| /// match. |
| /// |
| /// This function returns true if the match was unsuccessful and false if so. |
| /// On entry to the function the "OverallLeftShift" is a signed integer value |
| /// indicating the number of bytes that the subexpression is later shifted. For |
| /// example, if the expression is later right shifted by 16 bits, the |
| /// OverallLeftShift value would be -2 on entry. This is used to specify which |
| /// byte of ByteValues is actually being set. |
| /// |
| /// Similarly, ByteMask is a bitmask where a bit is clear if its corresponding |
| /// byte is masked to zero by a user. For example, in (X & 255), X will be |
| /// processed with a bytemask of 1. Because bytemask is 32-bits, this limits |
| /// this function to working on up to 32-byte (256 bit) values. ByteMask is |
| /// always in the local (OverallLeftShift) coordinate space. |
| /// |
| static bool CollectBSwapParts(Value *V, int OverallLeftShift, uint32_t ByteMask, |
| SmallVector<Value*, 8> &ByteValues) { |
| if (Instruction *I = dyn_cast<Instruction>(V)) { |
| // If this is an or instruction, it may be an inner node of the bswap. |
| if (I->getOpcode() == Instruction::Or) { |
| return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask, |
| ByteValues) || |
| CollectBSwapParts(I->getOperand(1), OverallLeftShift, ByteMask, |
| ByteValues); |
| } |
| |
| // If this is a logical shift by a constant multiple of 8, recurse with |
| // OverallLeftShift and ByteMask adjusted. |
| if (I->isLogicalShift() && isa<ConstantInt>(I->getOperand(1))) { |
| unsigned ShAmt = |
| cast<ConstantInt>(I->getOperand(1))->getLimitedValue(~0U); |
| // Ensure the shift amount is defined and of a byte value. |
| if ((ShAmt & 7) || (ShAmt > 8*ByteValues.size())) |
| return true; |
| |
| unsigned ByteShift = ShAmt >> 3; |
| if (I->getOpcode() == Instruction::Shl) { |
| // X << 2 -> collect(X, +2) |
| OverallLeftShift += ByteShift; |
| ByteMask >>= ByteShift; |
| } else { |
| // X >>u 2 -> collect(X, -2) |
| OverallLeftShift -= ByteShift; |
| ByteMask <<= ByteShift; |
| ByteMask &= (~0U >> (32-ByteValues.size())); |
| } |
| |
| if (OverallLeftShift >= (int)ByteValues.size()) return true; |
| if (OverallLeftShift <= -(int)ByteValues.size()) return true; |
| |
| return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask, |
| ByteValues); |
| } |
| |
| // If this is a logical 'and' with a mask that clears bytes, clear the |
| // corresponding bytes in ByteMask. |
| if (I->getOpcode() == Instruction::And && |
| isa<ConstantInt>(I->getOperand(1))) { |
| // Scan every byte of the and mask, seeing if the byte is either 0 or 255. |
| unsigned NumBytes = ByteValues.size(); |
| APInt Byte(I->getType()->getPrimitiveSizeInBits(), 255); |
| const APInt &AndMask = cast<ConstantInt>(I->getOperand(1))->getValue(); |
| |
| for (unsigned i = 0; i != NumBytes; ++i, Byte <<= 8) { |
| // If this byte is masked out by a later operation, we don't care what |
| // the and mask is. |
| if ((ByteMask & (1 << i)) == 0) |
| continue; |
| |
| // If the AndMask is all zeros for this byte, clear the bit. |
| APInt MaskB = AndMask & Byte; |
| if (MaskB == 0) { |
| ByteMask &= ~(1U << i); |
| continue; |
| } |
| |
| // If the AndMask is not all ones for this byte, it's not a bytezap. |
| if (MaskB != Byte) |
| return true; |
| |
| // Otherwise, this byte is kept. |
| } |
| |
| return CollectBSwapParts(I->getOperand(0), OverallLeftShift, ByteMask, |
| ByteValues); |
| } |
| } |
| |
| // Okay, we got to something that isn't a shift, 'or' or 'and'. This must be |
| // the input value to the bswap. Some observations: 1) if more than one byte |
| // is demanded from this input, then it could not be successfully assembled |
| // into a byteswap. At least one of the two bytes would not be aligned with |
| // their ultimate destination. |
| if (!isPowerOf2_32(ByteMask)) return true; |
| unsigned InputByteNo = CountTrailingZeros_32(ByteMask); |
| |
| // 2) The input and ultimate destinations must line up: if byte 3 of an i32 |
| // is demanded, it needs to go into byte 0 of the result. This means that the |
| // byte needs to be shifted until it lands in the right byte bucket. The |
| // shift amount depends on the position: if the byte is coming from the high |
| // part of the value (e.g. byte 3) then it must be shifted right. If from the |
| // low part, it must be shifted left. |
| unsigned DestByteNo = InputByteNo + OverallLeftShift; |
| if (InputByteNo < ByteValues.size()/2) { |
| if (ByteValues.size()-1-DestByteNo != InputByteNo) |
| return true; |
| } else { |
| if (ByteValues.size()-1-DestByteNo != InputByteNo) |
| return true; |
| } |
| |
| // If the destination byte value is already defined, the values are or'd |
| // together, which isn't a bswap (unless it's an or of the same bits). |
| if (ByteValues[DestByteNo] && ByteValues[DestByteNo] != V) |
| return true; |
| ByteValues[DestByteNo] = V; |
| return false; |
| } |
| |
| /// MatchBSwap - Given an OR instruction, check to see if this is a bswap idiom. |
| /// If so, insert the new bswap intrinsic and return it. |
| Instruction *InstCombiner::MatchBSwap(BinaryOperator &I) { |
| const IntegerType *ITy = dyn_cast<IntegerType>(I.getType()); |
| if (!ITy || ITy->getBitWidth() % 16 || |
| // ByteMask only allows up to 32-byte values. |
| ITy->getBitWidth() > 32*8) |
| return 0; // Can only bswap pairs of bytes. Can't do vectors. |
| |
| /// ByteValues - For each byte of the result, we keep track of which value |
| /// defines each byte. |
| SmallVector<Value*, 8> ByteValues; |
| ByteValues.resize(ITy->getBitWidth()/8); |
| |
| // Try to find all the pieces corresponding to the bswap. |
| uint32_t ByteMask = ~0U >> (32-ByteValues.size()); |
| if (CollectBSwapParts(&I, 0, ByteMask, ByteValues)) |
| return 0; |
| |
| // Check to see if all of the bytes come from the same value. |
| Value *V = ByteValues[0]; |
| if (V == 0) return 0; // Didn't find a byte? Must be zero. |
| |
| // Check to make sure that all of the bytes come from the same value. |
| for (unsigned i = 1, e = ByteValues.size(); i != e; ++i) |
| if (ByteValues[i] != V) |
| return 0; |
| const Type *Tys[] = { ITy }; |
| Module *M = I.getParent()->getParent()->getParent(); |
| Function *F = Intrinsic::getDeclaration(M, Intrinsic::bswap, Tys, 1); |
| return CallInst::Create(F, V); |
| } |
| |
| /// MatchSelectFromAndOr - We have an expression of the form (A&C)|(B&D). Check |
| /// If A is (cond?-1:0) and either B or D is ~(cond?-1,0) or (cond?0,-1), then |
| /// we can simplify this expression to "cond ? C : D or B". |
| static Instruction *MatchSelectFromAndOr(Value *A, Value *B, |
| Value *C, Value *D) { |
| // If A is not a select of -1/0, this cannot match. |
| Value *Cond = 0; |
| if (!match(A, m_SelectCst<-1, 0>(m_Value(Cond)))) |
| return 0; |
| |
| // ((cond?-1:0)&C) | (B&(cond?0:-1)) -> cond ? C : B. |
| if (match(D, m_SelectCst<0, -1>(m_Specific(Cond)))) |
| return SelectInst::Create(Cond, C, B); |
| if (match(D, m_Not(m_SelectCst<-1, 0>(m_Specific(Cond))))) |
| return SelectInst::Create(Cond, C, B); |
| // ((cond?-1:0)&C) | ((cond?0:-1)&D) -> cond ? C : D. |
| if (match(B, m_SelectCst<0, -1>(m_Specific(Cond)))) |
| return SelectInst::Create(Cond, C, D); |
| if (match(B, m_Not(m_SelectCst<-1, 0>(m_Specific(Cond))))) |
| return SelectInst::Create(Cond, C, D); |
| return 0; |
| } |
| |
| /// FoldOrOfICmps - Fold (icmp)|(icmp) if possible. |
| Instruction *InstCombiner::FoldOrOfICmps(Instruction &I, |
| ICmpInst *LHS, ICmpInst *RHS) { |
| Value *Val, *Val2; |
| ConstantInt *LHSCst, *RHSCst; |
| ICmpInst::Predicate LHSCC, RHSCC; |
| |
| // This only handles icmp of constants: (icmp1 A, C1) | (icmp2 B, C2). |
| if (!match(LHS, m_ICmp(LHSCC, m_Value(Val), m_ConstantInt(LHSCst))) || |
| !match(RHS, m_ICmp(RHSCC, m_Value(Val2), m_ConstantInt(RHSCst)))) |
| return 0; |
| |
| // From here on, we only handle: |
| // (icmp1 A, C1) | (icmp2 A, C2) --> something simpler. |
| if (Val != Val2) return 0; |
| |
| // ICMP_[US][GL]E X, CST is folded to ICMP_[US][GL]T elsewhere. |
| if (LHSCC == ICmpInst::ICMP_UGE || LHSCC == ICmpInst::ICMP_ULE || |
| RHSCC == ICmpInst::ICMP_UGE || RHSCC == ICmpInst::ICMP_ULE || |
| LHSCC == ICmpInst::ICMP_SGE || LHSCC == ICmpInst::ICMP_SLE || |
| RHSCC == ICmpInst::ICMP_SGE || RHSCC == ICmpInst::ICMP_SLE) |
| return 0; |
| |
| // We can't fold (ugt x, C) | (sgt x, C2). |
| if (!PredicatesFoldable(LHSCC, RHSCC)) |
| return 0; |
| |
| // Ensure that the larger constant is on the RHS. |
| bool ShouldSwap; |
| if (ICmpInst::isSignedPredicate(LHSCC) || |
| (ICmpInst::isEquality(LHSCC) && |
| ICmpInst::isSignedPredicate(RHSCC))) |
| ShouldSwap = LHSCst->getValue().sgt(RHSCst->getValue()); |
| else |
| ShouldSwap = LHSCst->getValue().ugt(RHSCst->getValue()); |
| |
| if (ShouldSwap) { |
| std::swap(LHS, RHS); |
| std::swap(LHSCst, RHSCst); |
| std::swap(LHSCC, RHSCC); |
| } |
| |
| // At this point, we know we have have two icmp instructions |
| // comparing a value against two constants and or'ing the result |
| // together. Because of the above check, we know that we only have |
| // ICMP_EQ, ICMP_NE, ICMP_LT, and ICMP_GT here. We also know (from the |
| // FoldICmpLogical check above), that the two constants are not |
| // equal. |
| assert(LHSCst != RHSCst && "Compares not folded above?"); |
| |
| switch (LHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case ICmpInst::ICMP_EQ: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case ICmpInst::ICMP_EQ: |
| if (LHSCst == SubOne(RHSCst)) { // (X == 13 | X == 14) -> X-13 <u 2 |
| Constant *AddCST = ConstantExpr::getNeg(LHSCst); |
| Instruction *Add = BinaryOperator::CreateAdd(Val, AddCST, |
| Val->getName()+".off"); |
| InsertNewInstBefore(Add, I); |
| AddCST = Subtract(AddOne(RHSCst), LHSCst); |
| return new ICmpInst(ICmpInst::ICMP_ULT, Add, AddCST); |
| } |
| break; // (X == 13 | X == 15) -> no change |
| case ICmpInst::ICMP_UGT: // (X == 13 | X u> 14) -> no change |
| case ICmpInst::ICMP_SGT: // (X == 13 | X s> 14) -> no change |
| break; |
| case ICmpInst::ICMP_NE: // (X == 13 | X != 15) -> X != 15 |
| case ICmpInst::ICMP_ULT: // (X == 13 | X u< 15) -> X u< 15 |
| case ICmpInst::ICMP_SLT: // (X == 13 | X s< 15) -> X s< 15 |
| return ReplaceInstUsesWith(I, RHS); |
| } |
| break; |
| case ICmpInst::ICMP_NE: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case ICmpInst::ICMP_EQ: // (X != 13 | X == 15) -> X != 13 |
| case ICmpInst::ICMP_UGT: // (X != 13 | X u> 15) -> X != 13 |
| case ICmpInst::ICMP_SGT: // (X != 13 | X s> 15) -> X != 13 |
| return ReplaceInstUsesWith(I, LHS); |
| case ICmpInst::ICMP_NE: // (X != 13 | X != 15) -> true |
| case ICmpInst::ICMP_ULT: // (X != 13 | X u< 15) -> true |
| case ICmpInst::ICMP_SLT: // (X != 13 | X s< 15) -> true |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| } |
| break; |
| case ICmpInst::ICMP_ULT: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case ICmpInst::ICMP_EQ: // (X u< 13 | X == 14) -> no change |
| break; |
| case ICmpInst::ICMP_UGT: // (X u< 13 | X u> 15) -> (X-13) u> 2 |
| // If RHSCst is [us]MAXINT, it is always false. Not handling |
| // this can cause overflow. |
| if (RHSCst->isMaxValue(false)) |
| return ReplaceInstUsesWith(I, LHS); |
| return InsertRangeTest(Val, LHSCst, AddOne(RHSCst), false, false, I); |
| case ICmpInst::ICMP_SGT: // (X u< 13 | X s> 15) -> no change |
| break; |
| case ICmpInst::ICMP_NE: // (X u< 13 | X != 15) -> X != 15 |
| case ICmpInst::ICMP_ULT: // (X u< 13 | X u< 15) -> X u< 15 |
| return ReplaceInstUsesWith(I, RHS); |
| case ICmpInst::ICMP_SLT: // (X u< 13 | X s< 15) -> no change |
| break; |
| } |
| break; |
| case ICmpInst::ICMP_SLT: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case ICmpInst::ICMP_EQ: // (X s< 13 | X == 14) -> no change |
| break; |
| case ICmpInst::ICMP_SGT: // (X s< 13 | X s> 15) -> (X-13) s> 2 |
| // If RHSCst is [us]MAXINT, it is always false. Not handling |
| // this can cause overflow. |
| if (RHSCst->isMaxValue(true)) |
| return ReplaceInstUsesWith(I, LHS); |
| return InsertRangeTest(Val, LHSCst, AddOne(RHSCst), true, false, I); |
| case ICmpInst::ICMP_UGT: // (X s< 13 | X u> 15) -> no change |
| break; |
| case ICmpInst::ICMP_NE: // (X s< 13 | X != 15) -> X != 15 |
| case ICmpInst::ICMP_SLT: // (X s< 13 | X s< 15) -> X s< 15 |
| return ReplaceInstUsesWith(I, RHS); |
| case ICmpInst::ICMP_ULT: // (X s< 13 | X u< 15) -> no change |
| break; |
| } |
| break; |
| case ICmpInst::ICMP_UGT: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case ICmpInst::ICMP_EQ: // (X u> 13 | X == 15) -> X u> 13 |
| case ICmpInst::ICMP_UGT: // (X u> 13 | X u> 15) -> X u> 13 |
| return ReplaceInstUsesWith(I, LHS); |
| case ICmpInst::ICMP_SGT: // (X u> 13 | X s> 15) -> no change |
| break; |
| case ICmpInst::ICMP_NE: // (X u> 13 | X != 15) -> true |
| case ICmpInst::ICMP_ULT: // (X u> 13 | X u< 15) -> true |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| case ICmpInst::ICMP_SLT: // (X u> 13 | X s< 15) -> no change |
| break; |
| } |
| break; |
| case ICmpInst::ICMP_SGT: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case ICmpInst::ICMP_EQ: // (X s> 13 | X == 15) -> X > 13 |
| case ICmpInst::ICMP_SGT: // (X s> 13 | X s> 15) -> X > 13 |
| return ReplaceInstUsesWith(I, LHS); |
| case ICmpInst::ICMP_UGT: // (X s> 13 | X u> 15) -> no change |
| break; |
| case ICmpInst::ICMP_NE: // (X s> 13 | X != 15) -> true |
| case ICmpInst::ICMP_SLT: // (X s> 13 | X s< 15) -> true |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| case ICmpInst::ICMP_ULT: // (X s> 13 | X u< 15) -> no change |
| break; |
| } |
| break; |
| } |
| return 0; |
| } |
| |
| /// FoldOrWithConstants - This helper function folds: |
| /// |
| /// ((A | B) & C1) | (B & C2) |
| /// |
| /// into: |
| /// |
| /// (A & C1) | B |
| /// |
| /// when the XOR of the two constants is "all ones" (-1). |
| Instruction *InstCombiner::FoldOrWithConstants(BinaryOperator &I, Value *Op, |
| Value *A, Value *B, Value *C) { |
| ConstantInt *CI1 = dyn_cast<ConstantInt>(C); |
| if (!CI1) return 0; |
| |
| Value *V1 = 0; |
| ConstantInt *CI2 = 0; |
| if (!match(Op, m_And(m_Value(V1), m_ConstantInt(CI2)))) return 0; |
| |
| APInt Xor = CI1->getValue() ^ CI2->getValue(); |
| if (!Xor.isAllOnesValue()) return 0; |
| |
| if (V1 == A || V1 == B) { |
| Instruction *NewOp = |
| InsertNewInstBefore(BinaryOperator::CreateAnd((V1 == A) ? B : A, CI1), I); |
| return BinaryOperator::CreateOr(NewOp, V1); |
| } |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitOr(BinaryOperator &I) { |
| bool Changed = SimplifyCommutative(I); |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| if (isa<UndefValue>(Op1)) // X | undef -> -1 |
| return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType())); |
| |
| // or X, X = X |
| if (Op0 == Op1) |
| return ReplaceInstUsesWith(I, Op0); |
| |
| // See if we can simplify any instructions used by the instruction whose sole |
| // purpose is to compute bits we don't care about. |
| if (!isa<VectorType>(I.getType())) { |
| uint32_t BitWidth = cast<IntegerType>(I.getType())->getBitWidth(); |
| APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0); |
| if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(BitWidth), |
| KnownZero, KnownOne)) |
| return &I; |
| } else if (isa<ConstantAggregateZero>(Op1)) { |
| return ReplaceInstUsesWith(I, Op0); // X | <0,0> -> X |
| } else if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1)) { |
| if (CP->isAllOnesValue()) // X | <-1,-1> -> <-1,-1> |
| return ReplaceInstUsesWith(I, I.getOperand(1)); |
| } |
| |
| |
| |
| // or X, -1 == -1 |
| if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) { |
| ConstantInt *C1 = 0; Value *X = 0; |
| // (X & C1) | C2 --> (X | C2) & (C1|C2) |
| if (match(Op0, m_And(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) { |
| Instruction *Or = BinaryOperator::CreateOr(X, RHS); |
| InsertNewInstBefore(Or, I); |
| Or->takeName(Op0); |
| return BinaryOperator::CreateAnd(Or, |
| ConstantInt::get(RHS->getValue() | C1->getValue())); |
| } |
| |
| // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2) |
| if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) { |
| Instruction *Or = BinaryOperator::CreateOr(X, RHS); |
| InsertNewInstBefore(Or, I); |
| Or->takeName(Op0); |
| return BinaryOperator::CreateXor(Or, |
| ConstantInt::get(C1->getValue() & ~RHS->getValue())); |
| } |
| |
| // Try to fold constant and into select arguments. |
| if (SelectInst *SI = dyn_cast<SelectInst>(Op0)) |
| if (Instruction *R = FoldOpIntoSelect(I, SI, this)) |
| return R; |
| if (isa<PHINode>(Op0)) |
| if (Instruction *NV = FoldOpIntoPhi(I)) |
| return NV; |
| } |
| |
| Value *A = 0, *B = 0; |
| ConstantInt *C1 = 0, *C2 = 0; |
| |
| if (match(Op0, m_And(m_Value(A), m_Value(B)))) |
| if (A == Op1 || B == Op1) // (A & ?) | A --> A |
| return ReplaceInstUsesWith(I, Op1); |
| if (match(Op1, m_And(m_Value(A), m_Value(B)))) |
| if (A == Op0 || B == Op0) // A | (A & ?) --> A |
| return ReplaceInstUsesWith(I, Op0); |
| |
| // (A | B) | C and A | (B | C) -> bswap if possible. |
| // (A >> B) | (C << D) and (A << B) | (B >> C) -> bswap if possible. |
| if (match(Op0, m_Or(m_Value(), m_Value())) || |
| match(Op1, m_Or(m_Value(), m_Value())) || |
| (match(Op0, m_Shift(m_Value(), m_Value())) && |
| match(Op1, m_Shift(m_Value(), m_Value())))) { |
| if (Instruction *BSwap = MatchBSwap(I)) |
| return BSwap; |
| } |
| |
| // (X^C)|Y -> (X|Y)^C iff Y&C == 0 |
| if (Op0->hasOneUse() && match(Op0, m_Xor(m_Value(A), m_ConstantInt(C1))) && |
| MaskedValueIsZero(Op1, C1->getValue())) { |
| Instruction *NOr = BinaryOperator::CreateOr(A, Op1); |
| InsertNewInstBefore(NOr, I); |
| NOr->takeName(Op0); |
| return BinaryOperator::CreateXor(NOr, C1); |
| } |
| |
| // Y|(X^C) -> (X|Y)^C iff Y&C == 0 |
| if (Op1->hasOneUse() && match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) && |
| MaskedValueIsZero(Op0, C1->getValue())) { |
| Instruction *NOr = BinaryOperator::CreateOr(A, Op0); |
| InsertNewInstBefore(NOr, I); |
| NOr->takeName(Op0); |
| return BinaryOperator::CreateXor(NOr, C1); |
| } |
| |
| // (A & C)|(B & D) |
| Value *C = 0, *D = 0; |
| if (match(Op0, m_And(m_Value(A), m_Value(C))) && |
| match(Op1, m_And(m_Value(B), m_Value(D)))) { |
| Value *V1 = 0, *V2 = 0, *V3 = 0; |
| C1 = dyn_cast<ConstantInt>(C); |
| C2 = dyn_cast<ConstantInt>(D); |
| if (C1 && C2) { // (A & C1)|(B & C2) |
| // If we have: ((V + N) & C1) | (V & C2) |
| // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0 |
| // replace with V+N. |
| if (C1->getValue() == ~C2->getValue()) { |
| if ((C2->getValue() & (C2->getValue()+1)) == 0 && // C2 == 0+1+ |
| match(A, m_Add(m_Value(V1), m_Value(V2)))) { |
| // Add commutes, try both ways. |
| if (V1 == B && MaskedValueIsZero(V2, C2->getValue())) |
| return ReplaceInstUsesWith(I, A); |
| if (V2 == B && MaskedValueIsZero(V1, C2->getValue())) |
| return ReplaceInstUsesWith(I, A); |
| } |
| // Or commutes, try both ways. |
| if ((C1->getValue() & (C1->getValue()+1)) == 0 && |
| match(B, m_Add(m_Value(V1), m_Value(V2)))) { |
| // Add commutes, try both ways. |
| if (V1 == A && MaskedValueIsZero(V2, C1->getValue())) |
| return ReplaceInstUsesWith(I, B); |
| if (V2 == A && MaskedValueIsZero(V1, C1->getValue())) |
| return ReplaceInstUsesWith(I, B); |
| } |
| } |
| V1 = 0; V2 = 0; V3 = 0; |
| } |
| |
| // Check to see if we have any common things being and'ed. If so, find the |
| // terms for V1 & (V2|V3). |
| if (isOnlyUse(Op0) || isOnlyUse(Op1)) { |
| if (A == B) // (A & C)|(A & D) == A & (C|D) |
| V1 = A, V2 = C, V3 = D; |
| else if (A == D) // (A & C)|(B & A) == A & (B|C) |
| V1 = A, V2 = B, V3 = C; |
| else if (C == B) // (A & C)|(C & D) == C & (A|D) |
| V1 = C, V2 = A, V3 = D; |
| else if (C == D) // (A & C)|(B & C) == C & (A|B) |
| V1 = C, V2 = A, V3 = B; |
| |
| if (V1) { |
| Value *Or = |
| InsertNewInstBefore(BinaryOperator::CreateOr(V2, V3, "tmp"), I); |
| return BinaryOperator::CreateAnd(V1, Or); |
| } |
| } |
| |
| // (A & (C0?-1:0)) | (B & ~(C0?-1:0)) -> C0 ? A : B, and commuted variants |
| if (Instruction *Match = MatchSelectFromAndOr(A, B, C, D)) |
| return Match; |
| if (Instruction *Match = MatchSelectFromAndOr(B, A, D, C)) |
| return Match; |
| if (Instruction *Match = MatchSelectFromAndOr(C, B, A, D)) |
| return Match; |
| if (Instruction *Match = MatchSelectFromAndOr(D, A, B, C)) |
| return Match; |
| |
| // ((A&~B)|(~A&B)) -> A^B |
| if ((match(C, m_Not(m_Specific(D))) && |
| match(B, m_Not(m_Specific(A))))) |
| return BinaryOperator::CreateXor(A, D); |
| // ((~B&A)|(~A&B)) -> A^B |
| if ((match(A, m_Not(m_Specific(D))) && |
| match(B, m_Not(m_Specific(C))))) |
| return BinaryOperator::CreateXor(C, D); |
| // ((A&~B)|(B&~A)) -> A^B |
| if ((match(C, m_Not(m_Specific(B))) && |
| match(D, m_Not(m_Specific(A))))) |
| return BinaryOperator::CreateXor(A, B); |
| // ((~B&A)|(B&~A)) -> A^B |
| if ((match(A, m_Not(m_Specific(B))) && |
| match(D, m_Not(m_Specific(C))))) |
| return BinaryOperator::CreateXor(C, B); |
| } |
| |
| // (X >> Z) | (Y >> Z) -> (X|Y) >> Z for all shifts. |
| if (BinaryOperator *SI1 = dyn_cast<BinaryOperator>(Op1)) { |
| if (BinaryOperator *SI0 = dyn_cast<BinaryOperator>(Op0)) |
| if (SI0->isShift() && SI0->getOpcode() == SI1->getOpcode() && |
| SI0->getOperand(1) == SI1->getOperand(1) && |
| (SI0->hasOneUse() || SI1->hasOneUse())) { |
| Instruction *NewOp = |
| InsertNewInstBefore(BinaryOperator::CreateOr(SI0->getOperand(0), |
| SI1->getOperand(0), |
| SI0->getName()), I); |
| return BinaryOperator::Create(SI1->getOpcode(), NewOp, |
| SI1->getOperand(1)); |
| } |
| } |
| |
| // ((A|B)&1)|(B&-2) -> (A&1) | B |
| if (match(Op0, m_And(m_Or(m_Value(A), m_Value(B)), m_Value(C))) || |
| match(Op0, m_And(m_Value(C), m_Or(m_Value(A), m_Value(B))))) { |
| Instruction *Ret = FoldOrWithConstants(I, Op1, A, B, C); |
| if (Ret) return Ret; |
| } |
| // (B&-2)|((A|B)&1) -> (A&1) | B |
| if (match(Op1, m_And(m_Or(m_Value(A), m_Value(B)), m_Value(C))) || |
| match(Op1, m_And(m_Value(C), m_Or(m_Value(A), m_Value(B))))) { |
| Instruction *Ret = FoldOrWithConstants(I, Op0, A, B, C); |
| if (Ret) return Ret; |
| } |
| |
| if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1 |
| if (A == Op1) // ~A | A == -1 |
| return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType())); |
| } else { |
| A = 0; |
| } |
| // Note, A is still live here! |
| if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B |
| if (Op0 == B) |
| return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType())); |
| |
| // (~A | ~B) == (~(A & B)) - De Morgan's Law |
| if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) { |
| Value *And = InsertNewInstBefore(BinaryOperator::CreateAnd(A, B, |
| I.getName()+".demorgan"), I); |
| return BinaryOperator::CreateNot(And); |
| } |
| } |
| |
| // (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B) |
| if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1))) { |
| if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS))) |
| return R; |
| |
| if (ICmpInst *LHS = dyn_cast<ICmpInst>(I.getOperand(0))) |
| if (Instruction *Res = FoldOrOfICmps(I, LHS, RHS)) |
| return Res; |
| } |
| |
| // fold (or (cast A), (cast B)) -> (cast (or A, B)) |
| if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) { |
| if (CastInst *Op1C = dyn_cast<CastInst>(Op1)) |
| if (Op0C->getOpcode() == Op1C->getOpcode()) {// same cast kind ? |
| if (!isa<ICmpInst>(Op0C->getOperand(0)) || |
| !isa<ICmpInst>(Op1C->getOperand(0))) { |
| const Type *SrcTy = Op0C->getOperand(0)->getType(); |
| if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() && |
| // Only do this if the casts both really cause code to be |
| // generated. |
| ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0), |
| I.getType(), TD) && |
| ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0), |
| I.getType(), TD)) { |
| Instruction *NewOp = BinaryOperator::CreateOr(Op0C->getOperand(0), |
| Op1C->getOperand(0), |
| I.getName()); |
| InsertNewInstBefore(NewOp, I); |
| return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType()); |
| } |
| } |
| } |
| } |
| |
| |
| // (fcmp uno x, c) | (fcmp uno y, c) -> (fcmp uno x, y) |
| if (FCmpInst *LHS = dyn_cast<FCmpInst>(I.getOperand(0))) { |
| if (FCmpInst *RHS = dyn_cast<FCmpInst>(I.getOperand(1))) { |
| if (LHS->getPredicate() == FCmpInst::FCMP_UNO && |
| RHS->getPredicate() == FCmpInst::FCMP_UNO && |
| LHS->getOperand(0)->getType() == RHS->getOperand(0)->getType()) { |
| if (ConstantFP *LHSC = dyn_cast<ConstantFP>(LHS->getOperand(1))) |
| if (ConstantFP *RHSC = dyn_cast<ConstantFP>(RHS->getOperand(1))) { |
| // If either of the constants are nans, then the whole thing returns |
| // true. |
| if (LHSC->getValueAPF().isNaN() || RHSC->getValueAPF().isNaN()) |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| |
| // Otherwise, no need to compare the two constants, compare the |
| // rest. |
| return new FCmpInst(FCmpInst::FCMP_UNO, LHS->getOperand(0), |
| RHS->getOperand(0)); |
| } |
| } else { |
| Value *Op0LHS, *Op0RHS, *Op1LHS, *Op1RHS; |
| FCmpInst::Predicate Op0CC, Op1CC; |
| if (match(Op0, m_FCmp(Op0CC, m_Value(Op0LHS), m_Value(Op0RHS))) && |
| match(Op1, m_FCmp(Op1CC, m_Value(Op1LHS), m_Value(Op1RHS)))) { |
| if (Op0LHS == Op1RHS && Op0RHS == Op1LHS) { |
| // Swap RHS operands to match LHS. |
| Op1CC = FCmpInst::getSwappedPredicate(Op1CC); |
| std::swap(Op1LHS, Op1RHS); |
| } |
| if (Op0LHS == Op1LHS && Op0RHS == Op1RHS) { |
| // Simplify (fcmp cc0 x, y) | (fcmp cc1 x, y). |
| if (Op0CC == Op1CC) |
| return new FCmpInst((FCmpInst::Predicate)Op0CC, Op0LHS, Op0RHS); |
| else if (Op0CC == FCmpInst::FCMP_TRUE || |
| Op1CC == FCmpInst::FCMP_TRUE) |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| else if (Op0CC == FCmpInst::FCMP_FALSE) |
| return ReplaceInstUsesWith(I, Op1); |
| else if (Op1CC == FCmpInst::FCMP_FALSE) |
| return ReplaceInstUsesWith(I, Op0); |
| bool Op0Ordered; |
| bool Op1Ordered; |
| unsigned Op0Pred = getFCmpCode(Op0CC, Op0Ordered); |
| unsigned Op1Pred = getFCmpCode(Op1CC, Op1Ordered); |
| if (Op0Ordered == Op1Ordered) { |
| // If both are ordered or unordered, return a new fcmp with |
| // or'ed predicates. |
| Value *RV = getFCmpValue(Op0Ordered, Op0Pred|Op1Pred, |
| Op0LHS, Op0RHS); |
| if (Instruction *I = dyn_cast<Instruction>(RV)) |
| return I; |
| // Otherwise, it's a constant boolean value... |
| return ReplaceInstUsesWith(I, RV); |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| return Changed ? &I : 0; |
| } |
| |
| namespace { |
| |
| // XorSelf - Implements: X ^ X --> 0 |
| struct XorSelf { |
| Value *RHS; |
| XorSelf(Value *rhs) : RHS(rhs) {} |
| bool shouldApply(Value *LHS) const { return LHS == RHS; } |
| Instruction *apply(BinaryOperator &Xor) const { |
| return &Xor; |
| } |
| }; |
| |
| } |
| |
| Instruction *InstCombiner::visitXor(BinaryOperator &I) { |
| bool Changed = SimplifyCommutative(I); |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| if (isa<UndefValue>(Op1)) { |
| if (isa<UndefValue>(Op0)) |
| // Handle undef ^ undef -> 0 special case. This is a common |
| // idiom (misuse). |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef |
| } |
| |
| // xor X, X = 0, even if X is nested in a sequence of Xor's. |
| if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) { |
| assert(Result == &I && "AssociativeOpt didn't work?"); Result=Result; |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| } |
| |
| // See if we can simplify any instructions used by the instruction whose sole |
| // purpose is to compute bits we don't care about. |
| if (!isa<VectorType>(I.getType())) { |
| uint32_t BitWidth = cast<IntegerType>(I.getType())->getBitWidth(); |
| APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0); |
| if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(BitWidth), |
| KnownZero, KnownOne)) |
| return &I; |
| } else if (isa<ConstantAggregateZero>(Op1)) { |
| return ReplaceInstUsesWith(I, Op0); // X ^ <0,0> -> X |
| } |
| |
| // Is this a ~ operation? |
| if (Value *NotOp = dyn_castNotVal(&I)) { |
| // ~(~X & Y) --> (X | ~Y) - De Morgan's Law |
| // ~(~X | Y) === (X & ~Y) - De Morgan's Law |
| if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(NotOp)) { |
| if (Op0I->getOpcode() == Instruction::And || |
| Op0I->getOpcode() == Instruction::Or) { |
| if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands(); |
| if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) { |
| Instruction *NotY = |
| BinaryOperator::CreateNot(Op0I->getOperand(1), |
| Op0I->getOperand(1)->getName()+".not"); |
| InsertNewInstBefore(NotY, I); |
| if (Op0I->getOpcode() == Instruction::And) |
| return BinaryOperator::CreateOr(Op0NotVal, NotY); |
| else |
| return BinaryOperator::CreateAnd(Op0NotVal, NotY); |
| } |
| } |
| } |
| } |
| |
| |
| if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) { |
| if (RHS == ConstantInt::getTrue() && Op0->hasOneUse()) { |
| // xor (cmp A, B), true = not (cmp A, B) = !cmp A, B |
| if (ICmpInst *ICI = dyn_cast<ICmpInst>(Op0)) |
| return new ICmpInst(ICI->getInversePredicate(), |
| ICI->getOperand(0), ICI->getOperand(1)); |
| |
| if (FCmpInst *FCI = dyn_cast<FCmpInst>(Op0)) |
| return new FCmpInst(FCI->getInversePredicate(), |
| FCI->getOperand(0), FCI->getOperand(1)); |
| } |
| |
| // fold (xor(zext(cmp)), 1) and (xor(sext(cmp)), -1) to ext(!cmp). |
| if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) { |
| if (CmpInst *CI = dyn_cast<CmpInst>(Op0C->getOperand(0))) { |
| if (CI->hasOneUse() && Op0C->hasOneUse()) { |
| Instruction::CastOps Opcode = Op0C->getOpcode(); |
| if (Opcode == Instruction::ZExt || Opcode == Instruction::SExt) { |
| if (RHS == ConstantExpr::getCast(Opcode, ConstantInt::getTrue(), |
| Op0C->getDestTy())) { |
| Instruction *NewCI = InsertNewInstBefore(CmpInst::Create( |
| CI->getOpcode(), CI->getInversePredicate(), |
| CI->getOperand(0), CI->getOperand(1)), I); |
| NewCI->takeName(CI); |
| return CastInst::Create(Opcode, NewCI, Op0C->getType()); |
| } |
| } |
| } |
| } |
| } |
| |
| if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) { |
| // ~(c-X) == X-c-1 == X+(-c-1) |
| if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue()) |
| if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) { |
| Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C); |
| Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C, |
| ConstantInt::get(I.getType(), 1)); |
| return BinaryOperator::CreateAdd(Op0I->getOperand(1), ConstantRHS); |
| } |
| |
| if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) { |
| if (Op0I->getOpcode() == Instruction::Add) { |
| // ~(X-c) --> (-c-1)-X |
| if (RHS->isAllOnesValue()) { |
| Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI); |
| return BinaryOperator::CreateSub( |
| ConstantExpr::getSub(NegOp0CI, |
| ConstantInt::get(I.getType(), 1)), |
| Op0I->getOperand(0)); |
| } else if (RHS->getValue().isSignBit()) { |
| // (X + C) ^ signbit -> (X + C + signbit) |
| Constant *C = ConstantInt::get(RHS->getValue() + Op0CI->getValue()); |
| return BinaryOperator::CreateAdd(Op0I->getOperand(0), C); |
| |
| } |
| } else if (Op0I->getOpcode() == Instruction::Or) { |
| // (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0 |
| if (MaskedValueIsZero(Op0I->getOperand(0), Op0CI->getValue())) { |
| Constant *NewRHS = ConstantExpr::getOr(Op0CI, RHS); |
| // Anything in both C1 and C2 is known to be zero, remove it from |
| // NewRHS. |
| Constant *CommonBits = And(Op0CI, RHS); |
| NewRHS = ConstantExpr::getAnd(NewRHS, |
| ConstantExpr::getNot(CommonBits)); |
| AddToWorkList(Op0I); |
| I.setOperand(0, Op0I->getOperand(0)); |
| I.setOperand(1, NewRHS); |
| return &I; |
| } |
| } |
| } |
| } |
| |
| // Try to fold constant and into select arguments. |
| if (SelectInst *SI = dyn_cast<SelectInst>(Op0)) |
| if (Instruction *R = FoldOpIntoSelect(I, SI, this)) |
| return R; |
| if (isa<PHINode>(Op0)) |
| if (Instruction *NV = FoldOpIntoPhi(I)) |
| return NV; |
| } |
| |
| if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1 |
| if (X == Op1) |
| return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType())); |
| |
| if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1 |
| if (X == Op0) |
| return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType())); |
| |
| |
| BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1); |
| if (Op1I) { |
| Value *A, *B; |
| if (match(Op1I, m_Or(m_Value(A), m_Value(B)))) { |
| if (A == Op0) { // B^(B|A) == (A|B)^B |
| Op1I->swapOperands(); |
| I.swapOperands(); |
| std::swap(Op0, Op1); |
| } else if (B == Op0) { // B^(A|B) == (A|B)^B |
| I.swapOperands(); // Simplified below. |
| std::swap(Op0, Op1); |
| } |
| } else if (match(Op1I, m_Xor(m_Specific(Op0), m_Value(B)))) { |
| return ReplaceInstUsesWith(I, B); // A^(A^B) == B |
| } else if (match(Op1I, m_Xor(m_Value(A), m_Specific(Op0)))) { |
| return ReplaceInstUsesWith(I, A); // A^(B^A) == B |
| } else if (match(Op1I, m_And(m_Value(A), m_Value(B))) && Op1I->hasOneUse()){ |
| if (A == Op0) { // A^(A&B) -> A^(B&A) |
| Op1I->swapOperands(); |
| std::swap(A, B); |
| } |
| if (B == Op0) { // A^(B&A) -> (B&A)^A |
| I.swapOperands(); // Simplified below. |
| std::swap(Op0, Op1); |
| } |
| } |
| } |
| |
| BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0); |
| if (Op0I) { |
| Value *A, *B; |
| if (match(Op0I, m_Or(m_Value(A), m_Value(B))) && Op0I->hasOneUse()) { |
| if (A == Op1) // (B|A)^B == (A|B)^B |
| std::swap(A, B); |
| if (B == Op1) { // (A|B)^B == A & ~B |
| Instruction *NotB = |
| InsertNewInstBefore(BinaryOperator::CreateNot(Op1, "tmp"), I); |
| return BinaryOperator::CreateAnd(A, NotB); |
| } |
| } else if (match(Op0I, m_Xor(m_Specific(Op1), m_Value(B)))) { |
| return ReplaceInstUsesWith(I, B); // (A^B)^A == B |
| } else if (match(Op0I, m_Xor(m_Value(A), m_Specific(Op1)))) { |
| return ReplaceInstUsesWith(I, A); // (B^A)^A == B |
| } else if (match(Op0I, m_And(m_Value(A), m_Value(B))) && Op0I->hasOneUse()){ |
| if (A == Op1) // (A&B)^A -> (B&A)^A |
| std::swap(A, B); |
| if (B == Op1 && // (B&A)^A == ~B & A |
| !isa<ConstantInt>(Op1)) { // Canonical form is (B&C)^C |
| Instruction *N = |
| InsertNewInstBefore(BinaryOperator::CreateNot(A, "tmp"), I); |
| return BinaryOperator::CreateAnd(N, Op1); |
| } |
| } |
| } |
| |
| // (X >> Z) ^ (Y >> Z) -> (X^Y) >> Z for all shifts. |
| if (Op0I && Op1I && Op0I->isShift() && |
| Op0I->getOpcode() == Op1I->getOpcode() && |
| Op0I->getOperand(1) == Op1I->getOperand(1) && |
| (Op1I->hasOneUse() || Op1I->hasOneUse())) { |
| Instruction *NewOp = |
| InsertNewInstBefore(BinaryOperator::CreateXor(Op0I->getOperand(0), |
| Op1I->getOperand(0), |
| Op0I->getName()), I); |
| return BinaryOperator::Create(Op1I->getOpcode(), NewOp, |
| Op1I->getOperand(1)); |
| } |
| |
| if (Op0I && Op1I) { |
| Value *A, *B, *C, *D; |
| // (A & B)^(A | B) -> A ^ B |
| if (match(Op0I, m_And(m_Value(A), m_Value(B))) && |
| match(Op1I, m_Or(m_Value(C), m_Value(D)))) { |
| if ((A == C && B == D) || (A == D && B == C)) |
| return BinaryOperator::CreateXor(A, B); |
| } |
| // (A | B)^(A & B) -> A ^ B |
| if (match(Op0I, m_Or(m_Value(A), m_Value(B))) && |
| match(Op1I, m_And(m_Value(C), m_Value(D)))) { |
| if ((A == C && B == D) || (A == D && B == C)) |
| return BinaryOperator::CreateXor(A, B); |
| } |
| |
| // (A & B)^(C & D) |
| if ((Op0I->hasOneUse() || Op1I->hasOneUse()) && |
| match(Op0I, m_And(m_Value(A), m_Value(B))) && |
| match(Op1I, m_And(m_Value(C), m_Value(D)))) { |
| // (X & Y)^(X & Y) -> (Y^Z) & X |
| Value *X = 0, *Y = 0, *Z = 0; |
| if (A == C) |
| X = A, Y = B, Z = D; |
| else if (A == D) |
| X = A, Y = B, Z = C; |
| else if (B == C) |
| X = B, Y = A, Z = D; |
| else if (B == D) |
| X = B, Y = A, Z = C; |
| |
| if (X) { |
| Instruction *NewOp = |
| InsertNewInstBefore(BinaryOperator::CreateXor(Y, Z, Op0->getName()), I); |
| return BinaryOperator::CreateAnd(NewOp, X); |
| } |
| } |
| } |
| |
| // (icmp1 A, B) ^ (icmp2 A, B) --> (icmp3 A, B) |
| if (ICmpInst *RHS = dyn_cast<ICmpInst>(I.getOperand(1))) |
| if (Instruction *R = AssociativeOpt(I, FoldICmpLogical(*this, RHS))) |
| return R; |
| |
| // fold (xor (cast A), (cast B)) -> (cast (xor A, B)) |
| if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) { |
| if (CastInst *Op1C = dyn_cast<CastInst>(Op1)) |
| if (Op0C->getOpcode() == Op1C->getOpcode()) { // same cast kind? |
| const Type *SrcTy = Op0C->getOperand(0)->getType(); |
| if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isInteger() && |
| // Only do this if the casts both really cause code to be generated. |
| ValueRequiresCast(Op0C->getOpcode(), Op0C->getOperand(0), |
| I.getType(), TD) && |
| ValueRequiresCast(Op1C->getOpcode(), Op1C->getOperand(0), |
| I.getType(), TD)) { |
| Instruction *NewOp = BinaryOperator::CreateXor(Op0C->getOperand(0), |
| Op1C->getOperand(0), |
| I.getName()); |
| InsertNewInstBefore(NewOp, I); |
| return CastInst::Create(Op0C->getOpcode(), NewOp, I.getType()); |
| } |
| } |
| } |
| |
| return Changed ? &I : 0; |
| } |
| |
| /// AddWithOverflow - Compute Result = In1+In2, returning true if the result |
| /// overflowed for this type. |
| static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1, |
| ConstantInt *In2, bool IsSigned = false) { |
| Result = cast<ConstantInt>(Add(In1, In2)); |
| |
| if (IsSigned) |
| if (In2->getValue().isNegative()) |
| return Result->getValue().sgt(In1->getValue()); |
| else |
| return Result->getValue().slt(In1->getValue()); |
| else |
| return Result->getValue().ult(In1->getValue()); |
| } |
| |
| /// SubWithOverflow - Compute Result = In1-In2, returning true if the result |
| /// overflowed for this type. |
| static bool SubWithOverflow(ConstantInt *&Result, ConstantInt *In1, |
| ConstantInt *In2, bool IsSigned = false) { |
| Result = cast<ConstantInt>(Subtract(In1, In2)); |
| |
| if (IsSigned) |
| if (In2->getValue().isNegative()) |
| return Result->getValue().slt(In1->getValue()); |
| else |
| return Result->getValue().sgt(In1->getValue()); |
| else |
| return Result->getValue().ugt(In1->getValue()); |
| } |
| |
| /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the |
| /// code necessary to compute the offset from the base pointer (without adding |
| /// in the base pointer). Return the result as a signed integer of intptr size. |
| static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) { |
| TargetData &TD = IC.getTargetData(); |
| gep_type_iterator GTI = gep_type_begin(GEP); |
| const Type *IntPtrTy = TD.getIntPtrType(); |
| Value *Result = Constant::getNullValue(IntPtrTy); |
| |
| // Build a mask for high order bits. |
| unsigned IntPtrWidth = TD.getPointerSizeInBits(); |
| uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth); |
| |
| for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end(); i != e; |
| ++i, ++GTI) { |
| Value *Op = *i; |
| uint64_t Size = TD.getTypePaddedSize(GTI.getIndexedType()) & PtrSizeMask; |
| if (ConstantInt *OpC = dyn_cast<ConstantInt>(Op)) { |
| if (OpC->isZero()) continue; |
| |
| // Handle a struct index, which adds its field offset to the pointer. |
| if (const StructType *STy = dyn_cast<StructType>(*GTI)) { |
| Size = TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue()); |
| |
| if (ConstantInt *RC = dyn_cast<ConstantInt>(Result)) |
| Result = ConstantInt::get(RC->getValue() + APInt(IntPtrWidth, Size)); |
| else |
| Result = IC.InsertNewInstBefore( |
| BinaryOperator::CreateAdd(Result, |
| ConstantInt::get(IntPtrTy, Size), |
| GEP->getName()+".offs"), I); |
| continue; |
| } |
| |
| Constant *Scale = ConstantInt::get(IntPtrTy, Size); |
| Constant *OC = ConstantExpr::getIntegerCast(OpC, IntPtrTy, true /*SExt*/); |
| Scale = ConstantExpr::getMul(OC, Scale); |
| if (Constant *RC = dyn_cast<Constant>(Result)) |
| Result = ConstantExpr::getAdd(RC, Scale); |
| else { |
| // Emit an add instruction. |
| Result = IC.InsertNewInstBefore( |
| BinaryOperator::CreateAdd(Result, Scale, |
| GEP->getName()+".offs"), I); |
| } |
| continue; |
| } |
| // Convert to correct type. |
| if (Op->getType() != IntPtrTy) { |
| if (Constant *OpC = dyn_cast<Constant>(Op)) |
| Op = ConstantExpr::getSExt(OpC, IntPtrTy); |
| else |
| Op = IC.InsertNewInstBefore(new SExtInst(Op, IntPtrTy, |
| Op->getName()+".c"), I); |
| } |
| if (Size != 1) { |
| Constant *Scale = ConstantInt::get(IntPtrTy, Size); |
| if (Constant *OpC = dyn_cast<Constant>(Op)) |
| Op = ConstantExpr::getMul(OpC, Scale); |
| else // We'll let instcombine(mul) convert this to a shl if possible. |
| Op = IC.InsertNewInstBefore(BinaryOperator::CreateMul(Op, Scale, |
| GEP->getName()+".idx"), I); |
| } |
| |
| // Emit an add instruction. |
| if (isa<Constant>(Op) && isa<Constant>(Result)) |
| Result = ConstantExpr::getAdd(cast<Constant>(Op), |
| cast<Constant>(Result)); |
| else |
| Result = IC.InsertNewInstBefore(BinaryOperator::CreateAdd(Op, Result, |
| GEP->getName()+".offs"), I); |
| } |
| return Result; |
| } |
| |
| |
| /// EvaluateGEPOffsetExpression - Return an value that can be used to compare of |
| /// the *offset* implied by GEP to zero. For example, if we have &A[i], we want |
| /// to return 'i' for "icmp ne i, 0". Note that, in general, indices can be |
| /// complex, and scales are involved. The above expression would also be legal |
| /// to codegen as "icmp ne (i*4), 0" (assuming A is a pointer to i32). This |
| /// later form is less amenable to optimization though, and we are allowed to |
| /// generate the first by knowing that pointer arithmetic doesn't overflow. |
| /// |
| /// If we can't emit an optimized form for this expression, this returns null. |
| /// |
| static Value *EvaluateGEPOffsetExpression(User *GEP, Instruction &I, |
| InstCombiner &IC) { |
| TargetData &TD = IC.getTargetData(); |
| gep_type_iterator GTI = gep_type_begin(GEP); |
| |
| // Check to see if this gep only has a single variable index. If so, and if |
| // any constant indices are a multiple of its scale, then we can compute this |
| // in terms of the scale of the variable index. For example, if the GEP |
| // implies an offset of "12 + i*4", then we can codegen this as "3 + i", |
| // because the expression will cross zero at the same point. |
| unsigned i, e = GEP->getNumOperands(); |
| int64_t Offset = 0; |
| for (i = 1; i != e; ++i, ++GTI) { |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) { |
| // Compute the aggregate offset of constant indices. |
| if (CI->isZero()) continue; |
| |
| // Handle a struct index, which adds its field offset to the pointer. |
| if (const StructType *STy = dyn_cast<StructType>(*GTI)) { |
| Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue()); |
| } else { |
| uint64_t Size = TD.getTypePaddedSize(GTI.getIndexedType()); |
| Offset += Size*CI->getSExtValue(); |
| } |
| } else { |
| // Found our variable index. |
| break; |
| } |
| } |
| |
| // If there are no variable indices, we must have a constant offset, just |
| // evaluate it the general way. |
| if (i == e) return 0; |
| |
| Value *VariableIdx = GEP->getOperand(i); |
| // Determine the scale factor of the variable element. For example, this is |
| // 4 if the variable index is into an array of i32. |
| uint64_t VariableScale = TD.getTypePaddedSize(GTI.getIndexedType()); |
| |
| // Verify that there are no other variable indices. If so, emit the hard way. |
| for (++i, ++GTI; i != e; ++i, ++GTI) { |
| ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i)); |
| if (!CI) return 0; |
| |
| // Compute the aggregate offset of constant indices. |
| if (CI->isZero()) continue; |
| |
| // Handle a struct index, which adds its field offset to the pointer. |
| if (const StructType *STy = dyn_cast<StructType>(*GTI)) { |
| Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue()); |
| } else { |
| uint64_t Size = TD.getTypePaddedSize(GTI.getIndexedType()); |
| Offset += Size*CI->getSExtValue(); |
| } |
| } |
| |
| // Okay, we know we have a single variable index, which must be a |
| // pointer/array/vector index. If there is no offset, life is simple, return |
| // the index. |
| unsigned IntPtrWidth = TD.getPointerSizeInBits(); |
| if (Offset == 0) { |
| // Cast to intptrty in case a truncation occurs. If an extension is needed, |
| // we don't need to bother extending: the extension won't affect where the |
| // computation crosses zero. |
| if (VariableIdx->getType()->getPrimitiveSizeInBits() > IntPtrWidth) |
| VariableIdx = new TruncInst(VariableIdx, TD.getIntPtrType(), |
| VariableIdx->getNameStart(), &I); |
| return VariableIdx; |
| } |
| |
| // Otherwise, there is an index. The computation we will do will be modulo |
| // the pointer size, so get it. |
| uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth); |
| |
| Offset &= PtrSizeMask; |
| VariableScale &= PtrSizeMask; |
| |
| // To do this transformation, any constant index must be a multiple of the |
| // variable scale factor. For example, we can evaluate "12 + 4*i" as "3 + i", |
| // but we can't evaluate "10 + 3*i" in terms of i. Check that the offset is a |
| // multiple of the variable scale. |
| int64_t NewOffs = Offset / (int64_t)VariableScale; |
| if (Offset != NewOffs*(int64_t)VariableScale) |
| return 0; |
| |
| // Okay, we can do this evaluation. Start by converting the index to intptr. |
| const Type *IntPtrTy = TD.getIntPtrType(); |
| if (VariableIdx->getType() != IntPtrTy) |
| VariableIdx = CastInst::CreateIntegerCast(VariableIdx, IntPtrTy, |
| true /*SExt*/, |
| VariableIdx->getNameStart(), &I); |
| Constant *OffsetVal = ConstantInt::get(IntPtrTy, NewOffs); |
| return BinaryOperator::CreateAdd(VariableIdx, OffsetVal, "offset", &I); |
| } |
| |
| |
| /// FoldGEPICmp - Fold comparisons between a GEP instruction and something |
| /// else. At this point we know that the GEP is on the LHS of the comparison. |
| Instruction *InstCombiner::FoldGEPICmp(User *GEPLHS, Value *RHS, |
| ICmpInst::Predicate Cond, |
| Instruction &I) { |
| assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!"); |
| |
| // Look through bitcasts. |
| if (BitCastInst *BCI = dyn_cast<BitCastInst>(RHS)) |
| RHS = BCI->getOperand(0); |
| |
| Value *PtrBase = GEPLHS->getOperand(0); |
| if (PtrBase == RHS) { |
| // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0). |
| // This transformation (ignoring the base and scales) is valid because we |
| // know pointers can't overflow. See if we can output an optimized form. |
| Value *Offset = EvaluateGEPOffsetExpression(GEPLHS, I, *this); |
| |
| // If not, synthesize the offset the hard way. |
| if (Offset == 0) |
| Offset = EmitGEPOffset(GEPLHS, I, *this); |
| return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset, |
| Constant::getNullValue(Offset->getType())); |
| } else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) { |
| // If the base pointers are different, but the indices are the same, just |
| // compare the base pointer. |
| if (PtrBase != GEPRHS->getOperand(0)) { |
| bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands(); |
| IndicesTheSame &= GEPLHS->getOperand(0)->getType() == |
| GEPRHS->getOperand(0)->getType(); |
| if (IndicesTheSame) |
| for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i) |
| if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) { |
| IndicesTheSame = false; |
| break; |
| } |
| |
| // If all indices are the same, just compare the base pointers. |
| if (IndicesTheSame) |
| return new ICmpInst(ICmpInst::getSignedPredicate(Cond), |
| GEPLHS->getOperand(0), GEPRHS->getOperand(0)); |
| |
| // Otherwise, the base pointers are different and the indices are |
| // different, bail out. |
| return 0; |
| } |
| |
| // If one of the GEPs has all zero indices, recurse. |
| bool AllZeros = true; |
| for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i) |
| if (!isa<Constant>(GEPLHS->getOperand(i)) || |
| !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) { |
| AllZeros = false; |
| break; |
| } |
| if (AllZeros) |
| return FoldGEPICmp(GEPRHS, GEPLHS->getOperand(0), |
| ICmpInst::getSwappedPredicate(Cond), I); |
| |
| // If the other GEP has all zero indices, recurse. |
| AllZeros = true; |
| for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i) |
| if (!isa<Constant>(GEPRHS->getOperand(i)) || |
| !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) { |
| AllZeros = false; |
| break; |
| } |
| if (AllZeros) |
| return FoldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I); |
| |
| if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) { |
| // If the GEPs only differ by one index, compare it. |
| unsigned NumDifferences = 0; // Keep track of # differences. |
| unsigned DiffOperand = 0; // The operand that differs. |
| for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i) |
| if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) { |
| if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() != |
| GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) { |
| // Irreconcilable differences. |
| NumDifferences = 2; |
| break; |
| } else { |
| if (NumDifferences++) break; |
| DiffOperand = i; |
| } |
| } |
| |
| if (NumDifferences == 0) // SAME GEP? |
| return ReplaceInstUsesWith(I, // No comparison is needed here. |
| ConstantInt::get(Type::Int1Ty, |
| ICmpInst::isTrueWhenEqual(Cond))); |
| |
| else if (NumDifferences == 1) { |
| Value *LHSV = GEPLHS->getOperand(DiffOperand); |
| Value *RHSV = GEPRHS->getOperand(DiffOperand); |
| // Make sure we do a signed comparison here. |
| return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV); |
| } |
| } |
| |
| // Only lower this if the icmp is the only user of the GEP or if we expect |
| // the result to fold to a constant! |
| if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) && |
| (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) { |
| // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2) |
| Value *L = EmitGEPOffset(GEPLHS, I, *this); |
| Value *R = EmitGEPOffset(GEPRHS, I, *this); |
| return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R); |
| } |
| } |
| return 0; |
| } |
| |
| /// FoldFCmp_IntToFP_Cst - Fold fcmp ([us]itofp x, cst) if possible. |
| /// |
| Instruction *InstCombiner::FoldFCmp_IntToFP_Cst(FCmpInst &I, |
| Instruction *LHSI, |
| Constant *RHSC) { |
| if (!isa<ConstantFP>(RHSC)) return 0; |
| const APFloat &RHS = cast<ConstantFP>(RHSC)->getValueAPF(); |
| |
| // Get the width of the mantissa. We don't want to hack on conversions that |
| // might lose information from the integer, e.g. "i64 -> float" |
| int MantissaWidth = LHSI->getType()->getFPMantissaWidth(); |
| if (MantissaWidth == -1) return 0; // Unknown. |
| |
| // Check to see that the input is converted from an integer type that is small |
| // enough that preserves all bits. TODO: check here for "known" sign bits. |
| // This would allow us to handle (fptosi (x >>s 62) to float) if x is i64 f.e. |
| unsigned InputSize = LHSI->getOperand(0)->getType()->getPrimitiveSizeInBits(); |
| |
| // If this is a uitofp instruction, we need an extra bit to hold the sign. |
| bool LHSUnsigned = isa<UIToFPInst>(LHSI); |
| if (LHSUnsigned) |
| ++InputSize; |
| |
| // If the conversion would lose info, don't hack on this. |
| if ((int)InputSize > MantissaWidth) |
| return 0; |
| |
| // Otherwise, we can potentially simplify the comparison. We know that it |
| // will always come through as an integer value and we know the constant is |
| // not a NAN (it would have been previously simplified). |
| assert(!RHS.isNaN() && "NaN comparison not already folded!"); |
| |
| ICmpInst::Predicate Pred; |
| switch (I.getPredicate()) { |
| default: assert(0 && "Unexpected predicate!"); |
| case FCmpInst::FCMP_UEQ: |
| case FCmpInst::FCMP_OEQ: |
| Pred = ICmpInst::ICMP_EQ; |
| break; |
| case FCmpInst::FCMP_UGT: |
| case FCmpInst::FCMP_OGT: |
| Pred = LHSUnsigned ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_SGT; |
| break; |
| case FCmpInst::FCMP_UGE: |
| case FCmpInst::FCMP_OGE: |
| Pred = LHSUnsigned ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_SGE; |
| break; |
| case FCmpInst::FCMP_ULT: |
| case FCmpInst::FCMP_OLT: |
| Pred = LHSUnsigned ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_SLT; |
| break; |
| case FCmpInst::FCMP_ULE: |
| case FCmpInst::FCMP_OLE: |
| Pred = LHSUnsigned ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_SLE; |
| break; |
| case FCmpInst::FCMP_UNE: |
| case FCmpInst::FCMP_ONE: |
| Pred = ICmpInst::ICMP_NE; |
| break; |
| case FCmpInst::FCMP_ORD: |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| case FCmpInst::FCMP_UNO: |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| } |
| |
| const IntegerType *IntTy = cast<IntegerType>(LHSI->getOperand(0)->getType()); |
| |
| // Now we know that the APFloat is a normal number, zero or inf. |
| |
| // See if the FP constant is too large for the integer. For example, |
| // comparing an i8 to 300.0. |
| unsigned IntWidth = IntTy->getPrimitiveSizeInBits(); |
| |
| if (!LHSUnsigned) { |
| // If the RHS value is > SignedMax, fold the comparison. This handles +INF |
| // and large values. |
| APFloat SMax(RHS.getSemantics(), APFloat::fcZero, false); |
| SMax.convertFromAPInt(APInt::getSignedMaxValue(IntWidth), true, |
| APFloat::rmNearestTiesToEven); |
| if (SMax.compare(RHS) == APFloat::cmpLessThan) { // smax < 13123.0 |
| if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SLT || |
| Pred == ICmpInst::ICMP_SLE) |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| } |
| } else { |
| // If the RHS value is > UnsignedMax, fold the comparison. This handles |
| // +INF and large values. |
| APFloat UMax(RHS.getSemantics(), APFloat::fcZero, false); |
| UMax.convertFromAPInt(APInt::getMaxValue(IntWidth), false, |
| APFloat::rmNearestTiesToEven); |
| if (UMax.compare(RHS) == APFloat::cmpLessThan) { // umax < 13123.0 |
| if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_ULT || |
| Pred == ICmpInst::ICMP_ULE) |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| } |
| } |
| |
| if (!LHSUnsigned) { |
| // See if the RHS value is < SignedMin. |
| APFloat SMin(RHS.getSemantics(), APFloat::fcZero, false); |
| SMin.convertFromAPInt(APInt::getSignedMinValue(IntWidth), true, |
| APFloat::rmNearestTiesToEven); |
| if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // smin > 12312.0 |
| if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT || |
| Pred == ICmpInst::ICMP_SGE) |
| return ReplaceInstUsesWith(I,ConstantInt::getTrue()); |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| } |
| } |
| |
| // Okay, now we know that the FP constant fits in the range [SMIN, SMAX] or |
| // [0, UMAX], but it may still be fractional. See if it is fractional by |
| // casting the FP value to the integer value and back, checking for equality. |
| // Don't do this for zero, because -0.0 is not fractional. |
| Constant *RHSInt = ConstantExpr::getFPToSI(RHSC, IntTy); |
| if (!RHS.isZero() && |
| ConstantExpr::getSIToFP(RHSInt, RHSC->getType()) != RHSC) { |
| // If we had a comparison against a fractional value, we have to adjust the |
| // compare predicate and sometimes the value. RHSC is rounded towards zero |
| // at this point. |
| switch (Pred) { |
| default: assert(0 && "Unexpected integer comparison!"); |
| case ICmpInst::ICMP_NE: // (float)int != 4.4 --> true |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| case ICmpInst::ICMP_EQ: // (float)int == 4.4 --> false |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| case ICmpInst::ICMP_ULE: |
| // (float)int <= 4.4 --> int <= 4 |
| // (float)int <= -4.4 --> false |
| if (RHS.isNegative()) |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| break; |
| case ICmpInst::ICMP_SLE: |
| // (float)int <= 4.4 --> int <= 4 |
| // (float)int <= -4.4 --> int < -4 |
| if (RHS.isNegative()) |
| Pred = ICmpInst::ICMP_SLT; |
| break; |
| case ICmpInst::ICMP_ULT: |
| // (float)int < -4.4 --> false |
| // (float)int < 4.4 --> int <= 4 |
| if (RHS.isNegative()) |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| Pred = ICmpInst::ICMP_ULE; |
| break; |
| case ICmpInst::ICMP_SLT: |
| // (float)int < -4.4 --> int < -4 |
| // (float)int < 4.4 --> int <= 4 |
| if (!RHS.isNegative()) |
| Pred = ICmpInst::ICMP_SLE; |
| break; |
| case ICmpInst::ICMP_UGT: |
| // (float)int > 4.4 --> int > 4 |
| // (float)int > -4.4 --> true |
| if (RHS.isNegative()) |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| break; |
| case ICmpInst::ICMP_SGT: |
| // (float)int > 4.4 --> int > 4 |
| // (float)int > -4.4 --> int >= -4 |
| if (RHS.isNegative()) |
| Pred = ICmpInst::ICMP_SGE; |
| break; |
| case ICmpInst::ICMP_UGE: |
| // (float)int >= -4.4 --> true |
| // (float)int >= 4.4 --> int > 4 |
| if (!RHS.isNegative()) |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| Pred = ICmpInst::ICMP_UGT; |
| break; |
| case ICmpInst::ICMP_SGE: |
| // (float)int >= -4.4 --> int >= -4 |
| // (float)int >= 4.4 --> int > 4 |
| if (!RHS.isNegative()) |
| Pred = ICmpInst::ICMP_SGT; |
| break; |
| } |
| } |
| |
| // Lower this FP comparison into an appropriate integer version of the |
| // comparison. |
| return new ICmpInst(Pred, LHSI->getOperand(0), RHSInt); |
| } |
| |
| Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) { |
| bool Changed = SimplifyCompare(I); |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| // Fold trivial predicates. |
| if (I.getPredicate() == FCmpInst::FCMP_FALSE) |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| if (I.getPredicate() == FCmpInst::FCMP_TRUE) |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| |
| // Simplify 'fcmp pred X, X' |
| if (Op0 == Op1) { |
| switch (I.getPredicate()) { |
| default: assert(0 && "Unknown predicate!"); |
| case FCmpInst::FCMP_UEQ: // True if unordered or equal |
| case FCmpInst::FCMP_UGE: // True if unordered, greater than, or equal |
| case FCmpInst::FCMP_ULE: // True if unordered, less than, or equal |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| case FCmpInst::FCMP_OGT: // True if ordered and greater than |
| case FCmpInst::FCMP_OLT: // True if ordered and less than |
| case FCmpInst::FCMP_ONE: // True if ordered and operands are unequal |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| |
| case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y) |
| case FCmpInst::FCMP_ULT: // True if unordered or less than |
| case FCmpInst::FCMP_UGT: // True if unordered or greater than |
| case FCmpInst::FCMP_UNE: // True if unordered or not equal |
| // Canonicalize these to be 'fcmp uno %X, 0.0'. |
| I.setPredicate(FCmpInst::FCMP_UNO); |
| I.setOperand(1, Constant::getNullValue(Op0->getType())); |
| return &I; |
| |
| case FCmpInst::FCMP_ORD: // True if ordered (no nans) |
| case FCmpInst::FCMP_OEQ: // True if ordered and equal |
| case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal |
| case FCmpInst::FCMP_OLE: // True if ordered and less than or equal |
| // Canonicalize these to be 'fcmp ord %X, 0.0'. |
| I.setPredicate(FCmpInst::FCMP_ORD); |
| I.setOperand(1, Constant::getNullValue(Op0->getType())); |
| return &I; |
| } |
| } |
| |
| if (isa<UndefValue>(Op1)) // fcmp pred X, undef -> undef |
| return ReplaceInstUsesWith(I, UndefValue::get(Type::Int1Ty)); |
| |
| // Handle fcmp with constant RHS |
| if (Constant *RHSC = dyn_cast<Constant>(Op1)) { |
| // If the constant is a nan, see if we can fold the comparison based on it. |
| if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) { |
| if (CFP->getValueAPF().isNaN()) { |
| if (FCmpInst::isOrdered(I.getPredicate())) // True if ordered and... |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| assert(FCmpInst::isUnordered(I.getPredicate()) && |
| "Comparison must be either ordered or unordered!"); |
| // True if unordered. |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| } |
| } |
| |
| if (Instruction *LHSI = dyn_cast<Instruction>(Op0)) |
| switch (LHSI->getOpcode()) { |
| case Instruction::PHI: |
| // Only fold fcmp into the PHI if the phi and fcmp are in the same |
| // block. If in the same block, we're encouraging jump threading. If |
| // not, we are just pessimizing the code by making an i1 phi. |
| if (LHSI->getParent() == I.getParent()) |
| if (Instruction *NV = FoldOpIntoPhi(I)) |
| return NV; |
| break; |
| case Instruction::SIToFP: |
| case Instruction::UIToFP: |
| if (Instruction *NV = FoldFCmp_IntToFP_Cst(I, LHSI, RHSC)) |
| return NV; |
| break; |
| case Instruction::Select: |
| // If either operand of the select is a constant, we can fold the |
| // comparison into the select arms, which will cause one to be |
| // constant folded and the select turned into a bitwise or. |
| Value *Op1 = 0, *Op2 = 0; |
| if (LHSI->hasOneUse()) { |
| if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) { |
| // Fold the known value into the constant operand. |
| Op1 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC); |
| // Insert a new FCmp of the other select operand. |
| Op2 = InsertNewInstBefore(new FCmpInst(I.getPredicate(), |
| LHSI->getOperand(2), RHSC, |
| I.getName()), I); |
| } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) { |
| // Fold the known value into the constant operand. |
| Op2 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC); |
| // Insert a new FCmp of the other select operand. |
| Op1 = InsertNewInstBefore(new FCmpInst(I.getPredicate(), |
| LHSI->getOperand(1), RHSC, |
| I.getName()), I); |
| } |
| } |
| |
| if (Op1) |
| return SelectInst::Create(LHSI->getOperand(0), Op1, Op2); |
| break; |
| } |
| } |
| |
| return Changed ? &I : 0; |
| } |
| |
| Instruction *InstCombiner::visitICmpInst(ICmpInst &I) { |
| bool Changed = SimplifyCompare(I); |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| const Type *Ty = Op0->getType(); |
| |
| // icmp X, X |
| if (Op0 == Op1) |
| return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, |
| I.isTrueWhenEqual())); |
| |
| if (isa<UndefValue>(Op1)) // X icmp undef -> undef |
| return ReplaceInstUsesWith(I, UndefValue::get(Type::Int1Ty)); |
| |
| // icmp <global/alloca*/null>, <global/alloca*/null> - Global/Stack value |
| // addresses never equal each other! We already know that Op0 != Op1. |
| if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) || |
| isa<ConstantPointerNull>(Op0)) && |
| (isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) || |
| isa<ConstantPointerNull>(Op1))) |
| return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, |
| !I.isTrueWhenEqual())); |
| |
| // icmp's with boolean values can always be turned into bitwise operations |
| if (Ty == Type::Int1Ty) { |
| switch (I.getPredicate()) { |
| default: assert(0 && "Invalid icmp instruction!"); |
| case ICmpInst::ICMP_EQ: { // icmp eq i1 A, B -> ~(A^B) |
| Instruction *Xor = BinaryOperator::CreateXor(Op0, Op1, I.getName()+"tmp"); |
| InsertNewInstBefore(Xor, I); |
| return BinaryOperator::CreateNot(Xor); |
| } |
| case ICmpInst::ICMP_NE: // icmp eq i1 A, B -> A^B |
| return BinaryOperator::CreateXor(Op0, Op1); |
| |
| case ICmpInst::ICMP_UGT: |
| std::swap(Op0, Op1); // Change icmp ugt -> icmp ult |
| // FALL THROUGH |
| case ICmpInst::ICMP_ULT:{ // icmp ult i1 A, B -> ~A & B |
| Instruction *Not = BinaryOperator::CreateNot(Op0, I.getName()+"tmp"); |
| InsertNewInstBefore(Not, I); |
| return BinaryOperator::CreateAnd(Not, Op1); |
| } |
| case ICmpInst::ICMP_SGT: |
| std::swap(Op0, Op1); // Change icmp sgt -> icmp slt |
| // FALL THROUGH |
| case ICmpInst::ICMP_SLT: { // icmp slt i1 A, B -> A & ~B |
| Instruction *Not = BinaryOperator::CreateNot(Op1, I.getName()+"tmp"); |
| InsertNewInstBefore(Not, I); |
| return BinaryOperator::CreateAnd(Not, Op0); |
| } |
| case ICmpInst::ICMP_UGE: |
| std::swap(Op0, Op1); // Change icmp uge -> icmp ule |
| // FALL THROUGH |
| case ICmpInst::ICMP_ULE: { // icmp ule i1 A, B -> ~A | B |
| Instruction *Not = BinaryOperator::CreateNot(Op0, I.getName()+"tmp"); |
| InsertNewInstBefore(Not, I); |
| return BinaryOperator::CreateOr(Not, Op1); |
| } |
| case ICmpInst::ICMP_SGE: |
| std::swap(Op0, Op1); // Change icmp sge -> icmp sle |
| // FALL THROUGH |
| case ICmpInst::ICMP_SLE: { // icmp sle i1 A, B -> A | ~B |
| Instruction *Not = BinaryOperator::CreateNot(Op1, I.getName()+"tmp"); |
| InsertNewInstBefore(Not, I); |
| return BinaryOperator::CreateOr(Not, Op0); |
| } |
| } |
| } |
| |
| // See if we are doing a comparison with a constant. |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { |
| Value *A, *B; |
| |
| // (icmp ne/eq (sub A B) 0) -> (icmp ne/eq A, B) |
| if (I.isEquality() && CI->isNullValue() && |
| match(Op0, m_Sub(m_Value(A), m_Value(B)))) { |
| // (icmp cond A B) if cond is equality |
| return new ICmpInst(I.getPredicate(), A, B); |
| } |
| |
| // If we have an icmp le or icmp ge instruction, turn it into the |
| // appropriate icmp lt or icmp gt instruction. This allows us to rely on |
| // them being folded in the code below. |
| switch (I.getPredicate()) { |
| default: break; |
| case ICmpInst::ICMP_ULE: |
| if (CI->isMaxValue(false)) // A <=u MAX -> TRUE |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| return new ICmpInst(ICmpInst::ICMP_ULT, Op0, AddOne(CI)); |
| case ICmpInst::ICMP_SLE: |
| if (CI->isMaxValue(true)) // A <=s MAX -> TRUE |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| return new ICmpInst(ICmpInst::ICMP_SLT, Op0, AddOne(CI)); |
| case ICmpInst::ICMP_UGE: |
| if (CI->isMinValue(false)) // A >=u MIN -> TRUE |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| return new ICmpInst( ICmpInst::ICMP_UGT, Op0, SubOne(CI)); |
| case ICmpInst::ICMP_SGE: |
| if (CI->isMinValue(true)) // A >=s MIN -> TRUE |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| return new ICmpInst(ICmpInst::ICMP_SGT, Op0, SubOne(CI)); |
| } |
| |
| // See if we can fold the comparison based on range information we can get |
| // by checking whether bits are known to be zero or one in the input. |
| uint32_t BitWidth = cast<IntegerType>(Ty)->getBitWidth(); |
| APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0); |
| |
| // If this comparison is a normal comparison, it demands all |
| // bits, if it is a sign bit comparison, it only demands the sign bit. |
| bool UnusedBit; |
| bool isSignBit = isSignBitCheck(I.getPredicate(), CI, UnusedBit); |
| |
| if (SimplifyDemandedBits(Op0, |
| isSignBit ? APInt::getSignBit(BitWidth) |
| : APInt::getAllOnesValue(BitWidth), |
| KnownZero, KnownOne, 0)) |
| return &I; |
| |
| // Given the known and unknown bits, compute a range that the LHS could be |
| // in. Compute the Min, Max and RHS values based on the known bits. For the |
| // EQ and NE we use unsigned values. |
| APInt Min(BitWidth, 0), Max(BitWidth, 0); |
| if (ICmpInst::isSignedPredicate(I.getPredicate())) |
| ComputeSignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne, Min, Max); |
| else |
| ComputeUnsignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne,Min,Max); |
| |
| // If Min and Max are known to be the same, then SimplifyDemandedBits |
| // figured out that the LHS is a constant. Just constant fold this now so |
| // that code below can assume that Min != Max. |
| if (Min == Max) |
| return ReplaceInstUsesWith(I, ConstantExpr::getICmp(I.getPredicate(), |
| ConstantInt::get(Min), |
| CI)); |
| |
| // Based on the range information we know about the LHS, see if we can |
| // simplify this comparison. For example, (x&4) < 8 is always true. |
| const APInt &RHSVal = CI->getValue(); |
| switch (I.getPredicate()) { // LE/GE have been folded already. |
| default: assert(0 && "Unknown icmp opcode!"); |
| case ICmpInst::ICMP_EQ: |
| if (Max.ult(RHSVal) || Min.ugt(RHSVal)) |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| break; |
| case ICmpInst::ICMP_NE: |
| if (Max.ult(RHSVal) || Min.ugt(RHSVal)) |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| break; |
| case ICmpInst::ICMP_ULT: |
| if (Max.ult(RHSVal)) // A <u C -> true iff max(A) < C |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| if (Min.uge(RHSVal)) // A <u C -> false iff min(A) >= C |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| if (RHSVal == Max) // A <u MAX -> A != MAX |
| return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); |
| if (RHSVal == Min+1) // A <u MIN+1 -> A == MIN |
| return new ICmpInst(ICmpInst::ICMP_EQ, Op0, SubOne(CI)); |
| |
| // (x <u 2147483648) -> (x >s -1) -> true if sign bit clear |
| if (CI->isMinValue(true)) |
| return new ICmpInst(ICmpInst::ICMP_SGT, Op0, |
| ConstantInt::getAllOnesValue(Op0->getType())); |
| break; |
| case ICmpInst::ICMP_UGT: |
| if (Min.ugt(RHSVal)) // A >u C -> true iff min(A) > C |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| if (Max.ule(RHSVal)) // A >u C -> false iff max(A) <= C |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| |
| if (RHSVal == Min) // A >u MIN -> A != MIN |
| return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); |
| if (RHSVal == Max-1) // A >u MAX-1 -> A == MAX |
| return new ICmpInst(ICmpInst::ICMP_EQ, Op0, AddOne(CI)); |
| |
| // (x >u 2147483647) -> (x <s 0) -> true if sign bit set |
| if (CI->isMaxValue(true)) |
| return new ICmpInst(ICmpInst::ICMP_SLT, Op0, |
| ConstantInt::getNullValue(Op0->getType())); |
| break; |
| case ICmpInst::ICMP_SLT: |
| if (Max.slt(RHSVal)) // A <s C -> true iff max(A) < C |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| if (Min.sge(RHSVal)) // A <s C -> false iff min(A) >= C |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| if (RHSVal == Max) // A <s MAX -> A != MAX |
| return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); |
| if (RHSVal == Min+1) // A <s MIN+1 -> A == MIN |
| return new ICmpInst(ICmpInst::ICMP_EQ, Op0, SubOne(CI)); |
| break; |
| case ICmpInst::ICMP_SGT: |
| if (Min.sgt(RHSVal)) // A >s C -> true iff min(A) > C |
| return ReplaceInstUsesWith(I, ConstantInt::getTrue()); |
| if (Max.sle(RHSVal)) // A >s C -> false iff max(A) <= C |
| return ReplaceInstUsesWith(I, ConstantInt::getFalse()); |
| |
| if (RHSVal == Min) // A >s MIN -> A != MIN |
| return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); |
| if (RHSVal == Max-1) // A >s MAX-1 -> A == MAX |
| return new ICmpInst(ICmpInst::ICMP_EQ, Op0, AddOne(CI)); |
| break; |
| } |
| } |
| |
| // Test if the ICmpInst instruction is used exclusively by a select as |
| // part of a minimum or maximum operation. If so, refrain from doing |
| // any other folding. This helps out other analyses which understand |
| // non-obfuscated minimum and maximum idioms, such as ScalarEvolution |
| // and CodeGen. And in this case, at least one of the comparison |
| // operands has at least one user besides the compare (the select), |
| // which would often largely negate the benefit of folding anyway. |
| if (I.hasOneUse()) |
| if (SelectInst *SI = dyn_cast<SelectInst>(*I.use_begin())) |
| if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) || |
| (SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1)) |
| return 0; |
| |
| // See if we are doing a comparison between a constant and an instruction that |
| // can be folded into the comparison. |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { |
| // Since the RHS is a ConstantInt (CI), if the left hand side is an |
| // instruction, see if that instruction also has constants so that the |
| // instruction can be folded into the icmp |
| if (Instruction *LHSI = dyn_cast<Instruction>(Op0)) |
| if (Instruction *Res = visitICmpInstWithInstAndIntCst(I, LHSI, CI)) |
| return Res; |
| } |
| |
| // Handle icmp with constant (but not simple integer constant) RHS |
| if (Constant *RHSC = dyn_cast<Constant>(Op1)) { |
| if (Instruction *LHSI = dyn_cast<Instruction>(Op0)) |
| switch (LHSI->getOpcode()) { |
| case Instruction::GetElementPtr: |
| if (RHSC->isNullValue()) { |
| // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null |
| bool isAllZeros = true; |
| for (unsigned i = 1, e = LHSI->getNumOperands(); i != e; ++i) |
| if (!isa<Constant>(LHSI->getOperand(i)) || |
| !cast<Constant>(LHSI->getOperand(i))->isNullValue()) { |
| isAllZeros = false; |
| break; |
| } |
| if (isAllZeros) |
| return new ICmpInst(I.getPredicate(), LHSI->getOperand(0), |
| Constant::getNullValue(LHSI->getOperand(0)->getType())); |
| } |
| break; |
| |
| case Instruction::PHI: |
| // Only fold icmp into the PHI if the phi and fcmp are in the same |
| // block. If in the same block, we're encouraging jump threading. If |
| // not, we are just pessimizing the code by making an i1 phi. |
| if (LHSI->getParent() == I.getParent()) |
| if (Instruction *NV = FoldOpIntoPhi(I)) |
| return NV; |
| break; |
| case Instruction::Select: { |
| // If either operand of the select is a constant, we can fold the |
| // comparison into the select arms, which will cause one to be |
| // constant folded and the select turned into a bitwise or. |
| Value *Op1 = 0, *Op2 = 0; |
| if (LHSI->hasOneUse()) { |
| if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) { |
| // Fold the known value into the constant operand. |
| Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC); |
| // Insert a new ICmp of the other select operand. |
| Op2 = InsertNewInstBefore(new ICmpInst(I.getPredicate(), |
| LHSI->getOperand(2), RHSC, |
| I.getName()), I); |
| } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) { |
| // Fold the known value into the constant operand. |
| Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC); |
| // Insert a new ICmp of the other select operand. |
| Op1 = InsertNewInstBefore(new ICmpInst(I.getPredicate(), |
| LHSI->getOperand(1), RHSC, |
| I.getName()), I); |
| } |
| } |
| |
| if (Op1) |
| return SelectInst::Create(LHSI->getOperand(0), Op1, Op2); |
| break; |
| } |
| case Instruction::Malloc: |
| // If we have (malloc != null), and if the malloc has a single use, we |
| // can assume it is successful and remove the malloc. |
| if (LHSI->hasOneUse() && isa<ConstantPointerNull>(RHSC)) { |
| AddToWorkList(LHSI); |
| return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, |
| !I.isTrueWhenEqual())); |
| } |
| break; |
| } |
| } |
| |
| // If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now. |
| if (User *GEP = dyn_castGetElementPtr(Op0)) |
| if (Instruction *NI = FoldGEPICmp(GEP, Op1, I.getPredicate(), I)) |
| return NI; |
| if (User *GEP = dyn_castGetElementPtr(Op1)) |
| if (Instruction *NI = FoldGEPICmp(GEP, Op0, |
| ICmpInst::getSwappedPredicate(I.getPredicate()), I)) |
| return NI; |
| |
| // Test to see if the operands of the icmp are casted versions of other |
| // values. If the ptr->ptr cast can be stripped off both arguments, we do so |
| // now. |
| if (BitCastInst *CI = dyn_cast<BitCastInst>(Op0)) { |
| if (isa<PointerType>(Op0->getType()) && |
| (isa<Constant>(Op1) || isa<BitCastInst>(Op1))) { |
| // We keep moving the cast from the left operand over to the right |
| // operand, where it can often be eliminated completely. |
| Op0 = CI->getOperand(0); |
| |
| // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast |
| // so eliminate it as well. |
| if (BitCastInst *CI2 = dyn_cast<BitCastInst>(Op1)) |
| Op1 = CI2->getOperand(0); |
| |
| // If Op1 is a constant, we can fold the cast into the constant. |
| if (Op0->getType() != Op1->getType()) { |
| if (Constant *Op1C = dyn_cast<Constant>(Op1)) { |
| Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType()); |
| } else { |
| // Otherwise, cast the RHS right before the icmp |
| Op1 = InsertBitCastBefore(Op1, Op0->getType(), I); |
| } |
| } |
| return new ICmpInst(I.getPredicate(), Op0, Op1); |
| } |
| } |
| |
| if (isa<CastInst>(Op0)) { |
| // Handle the special case of: icmp (cast bool to X), <cst> |
| // This comes up when you have code like |
| // int X = A < B; |
| // if (X) ... |
| // For generality, we handle any zero-extension of any operand comparison |
| // with a constant or another cast from the same type. |
| if (isa<ConstantInt>(Op1) || isa<CastInst>(Op1)) |
| if (Instruction *R = visitICmpInstWithCastAndCast(I)) |
| return R; |
| } |
| |
| // See if it's the same type of instruction on the left and right. |
| if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) { |
| if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) { |
| if (Op0I->getOpcode() == Op1I->getOpcode() && Op0I->hasOneUse() && |
| Op1I->hasOneUse() && Op0I->getOperand(1) == Op1I->getOperand(1) && |
| I.isEquality()) { |
| switch (Op0I->getOpcode()) { |
| default: break; |
| case Instruction::Add: |
| case Instruction::Sub: |
| case Instruction::Xor: |
| // a+x icmp eq/ne b+x --> a icmp b |
| return new ICmpInst(I.getPredicate(), Op0I->getOperand(0), |
| Op1I->getOperand(0)); |
| break; |
| case Instruction::Mul: |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) { |
| // a * Cst icmp eq/ne b * Cst --> a & Mask icmp b & Mask |
| // Mask = -1 >> count-trailing-zeros(Cst). |
| if (!CI->isZero() && !CI->isOne()) { |
| const APInt &AP = CI->getValue(); |
| ConstantInt *Mask = ConstantInt::get( |
| APInt::getLowBitsSet(AP.getBitWidth(), |
| AP.getBitWidth() - |
| AP.countTrailingZeros())); |
| Instruction *And1 = BinaryOperator::CreateAnd(Op0I->getOperand(0), |
| Mask); |
| Instruction *And2 = BinaryOperator::CreateAnd(Op1I->getOperand(0), |
| Mask); |
| InsertNewInstBefore(And1, I); |
| InsertNewInstBefore(And2, I); |
| return new ICmpInst(I.getPredicate(), And1, And2); |
| } |
| } |
| break; |
| } |
| } |
| } |
| } |
| |
| // ~x < ~y --> y < x |
| { Value *A, *B; |
| if (match(Op0, m_Not(m_Value(A))) && |
| match(Op1, m_Not(m_Value(B)))) |
| return new ICmpInst(I.getPredicate(), B, A); |
| } |
| |
| if (I.isEquality()) { |
| Value *A, *B, *C, *D; |
| |
| // -x == -y --> x == y |
| if (match(Op0, m_Neg(m_Value(A))) && |
| match(Op1, m_Neg(m_Value(B)))) |
| return new ICmpInst(I.getPredicate(), A, B); |
| |
| if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) { |
| if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0 |
| Value *OtherVal = A == Op1 ? B : A; |
| return new ICmpInst(I.getPredicate(), OtherVal, |
| Constant::getNullValue(A->getType())); |
| } |
| |
| if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) { |
| // A^c1 == C^c2 --> A == C^(c1^c2) |
| ConstantInt *C1, *C2; |
| if (match(B, m_ConstantInt(C1)) && |
| match(D, m_ConstantInt(C2)) && Op1->hasOneUse()) { |
| Constant *NC = ConstantInt::get(C1->getValue() ^ C2->getValue()); |
| Instruction *Xor = BinaryOperator::CreateXor(C, NC, "tmp"); |
| return new ICmpInst(I.getPredicate(), A, |
| InsertNewInstBefore(Xor, I)); |
| } |
| |
| // A^B == A^D -> B == D |
| if (A == C) return new ICmpInst(I.getPredicate(), B, D); |
| if (A == D) return new ICmpInst(I.getPredicate(), B, C); |
| if (B == C) return new ICmpInst(I.getPredicate(), A, D); |
| if (B == D) return new ICmpInst(I.getPredicate(), A, C); |
| } |
| } |
| |
| if (match(Op1, m_Xor(m_Value(A), m_Value(B))) && |
| (A == Op0 || B == Op0)) { |
| // A == (A^B) -> B == 0 |
| Value *OtherVal = A == Op0 ? B : A; |
| return new ICmpInst(I.getPredicate(), OtherVal, |
| Constant::getNullValue(A->getType())); |
| } |
| |
| // (A-B) == A -> B == 0 |
| if (match(Op0, m_Sub(m_Specific(Op1), m_Value(B)))) |
| return new ICmpInst(I.getPredicate(), B, |
| Constant::getNullValue(B->getType())); |
| |
| // A == (A-B) -> B == 0 |
| if (match(Op1, m_Sub(m_Specific(Op0), m_Value(B)))) |
| return new ICmpInst(I.getPredicate(), B, |
| Constant::getNullValue(B->getType())); |
| |
| // (X&Z) == (Y&Z) -> (X^Y) & Z == 0 |
| if (Op0->hasOneUse() && Op1->hasOneUse() && |
| match(Op0, m_And(m_Value(A), m_Value(B))) && |
| match(Op1, m_And(m_Value(C), m_Value(D)))) { |
| Value *X = 0, *Y = 0, *Z = 0; |
| |
| if (A == C) { |
| X = B; Y = D; Z = A; |
| } else if (A == D) { |
| X = B; Y = C; Z = A; |
| } else if (B == C) { |
| X = A; Y = D; Z = B; |
| } else if (B == D) { |
| X = A; Y = C; Z = B; |
| } |
| |
| if (X) { // Build (X^Y) & Z |
| Op1 = InsertNewInstBefore(BinaryOperator::CreateXor(X, Y, "tmp"), I); |
| Op1 = InsertNewInstBefore(BinaryOperator::CreateAnd(Op1, Z, "tmp"), I); |
| I.setOperand(0, Op1); |
| I.setOperand(1, Constant::getNullValue(Op1->getType())); |
| return &I; |
| } |
| } |
| } |
| return Changed ? &I : 0; |
| } |
| |
| |
| /// FoldICmpDivCst - Fold "icmp pred, ([su]div X, DivRHS), CmpRHS" where DivRHS |
| /// and CmpRHS are both known to be integer constants. |
| Instruction *InstCombiner::FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI, |
| ConstantInt *DivRHS) { |
| ConstantInt *CmpRHS = cast<ConstantInt>(ICI.getOperand(1)); |
| const APInt &CmpRHSV = CmpRHS->getValue(); |
| |
| // FIXME: If the operand types don't match the type of the divide |
| // then don't attempt this transform. The code below doesn't have the |
| // logic to deal with a signed divide and an unsigned compare (and |
| // vice versa). This is because (x /s C1) <s C2 produces different |
| // results than (x /s C1) <u C2 or (x /u C1) <s C2 or even |
| // (x /u C1) <u C2. Simply casting the operands and result won't |
| // work. :( The if statement below tests that condition and bails |
| // if it finds it. |
| bool DivIsSigned = DivI->getOpcode() == Instruction::SDiv; |
| if (!ICI.isEquality() && DivIsSigned != ICI.isSignedPredicate()) |
| return 0; |
| if (DivRHS->isZero()) |
| return 0; // The ProdOV computation fails on divide by zero. |
| if (DivIsSigned && DivRHS->isAllOnesValue()) |
| return 0; // The overflow computation also screws up here |
| if (DivRHS->isOne()) |
| return 0; // Not worth bothering, and eliminates some funny cases |
| // with INT_MIN. |
| |
| // Compute Prod = CI * DivRHS. We are essentially solving an equation |
| // of form X/C1=C2. We solve for X by multiplying C1 (DivRHS) and |
| // C2 (CI). By solving for X we can turn this into a range check |
| // instead of computing a divide. |
| ConstantInt *Prod = Multiply(CmpRHS, DivRHS); |
| |
| // Determine if the product overflows by seeing if the product is |
| // not equal to the divide. Make sure we do the same kind of divide |
| // as in the LHS instruction that we're folding. |
| bool ProdOV = (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS) : |
| ConstantExpr::getUDiv(Prod, DivRHS)) != CmpRHS; |
| |
| // Get the ICmp opcode |
| ICmpInst::Predicate Pred = ICI.getPredicate(); |
| |
| // Figure out the interval that is being checked. For example, a comparison |
| // like "X /u 5 == 0" is really checking that X is in the interval [0, 5). |
| // Compute this interval based on the constants involved and the signedness of |
| // the compare/divide. This computes a half-open interval, keeping track of |
| // whether either value in the interval overflows. After analysis each |
| // overflow variable is set to 0 if it's corresponding bound variable is valid |
| // -1 if overflowed off the bottom end, or +1 if overflowed off the top end. |
| int LoOverflow = 0, HiOverflow = 0; |
| ConstantInt *LoBound = 0, *HiBound = 0; |
| |
| if (!DivIsSigned) { // udiv |
| // e.g. X/5 op 3 --> [15, 20) |
| LoBound = Prod; |
| HiOverflow = LoOverflow = ProdOV; |
| if (!HiOverflow) |
| HiOverflow = AddWithOverflow(HiBound, LoBound, DivRHS, false); |
| } else if (DivRHS->getValue().isStrictlyPositive()) { // Divisor is > 0. |
| if (CmpRHSV == 0) { // (X / pos) op 0 |
| // Can't overflow. e.g. X/2 op 0 --> [-1, 2) |
| LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS))); |
| HiBound = DivRHS; |
| } else if (CmpRHSV.isStrictlyPositive()) { // (X / pos) op pos |
| LoBound = Prod; // e.g. X/5 op 3 --> [15, 20) |
| HiOverflow = LoOverflow = ProdOV; |
| if (!HiOverflow) |
| HiOverflow = AddWithOverflow(HiBound, Prod, DivRHS, true); |
| } else { // (X / pos) op neg |
| // e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14) |
| HiBound = AddOne(Prod); |
| LoOverflow = HiOverflow = ProdOV ? -1 : 0; |
| if (!LoOverflow) { |
| ConstantInt* DivNeg = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS)); |
| LoOverflow = AddWithOverflow(LoBound, HiBound, DivNeg, |
| true) ? -1 : 0; |
| } |
| } |
| } else if (DivRHS->getValue().isNegative()) { // Divisor is < 0. |
| if (CmpRHSV == 0) { // (X / neg) op 0 |
| // e.g. X/-5 op 0 --> [-4, 5) |
| LoBound = AddOne(DivRHS); |
| HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS)); |
| if (HiBound == DivRHS) { // -INTMIN = INTMIN |
| HiOverflow = 1; // [INTMIN+1, overflow) |
| HiBound = 0; // e.g. X/INTMIN = 0 --> X > INTMIN |
| } |
| } else if (CmpRHSV.isStrictlyPositive()) { // (X / neg) op pos |
| // e.g. X/-5 op 3 --> [-19, -14) |
| HiBound = AddOne(Prod); |
| HiOverflow = LoOverflow = ProdOV ? -1 : 0; |
| if (!LoOverflow) |
| LoOverflow = AddWithOverflow(LoBound, HiBound, DivRHS, true) ? -1 : 0; |
| } else { // (X / neg) op neg |
| LoBound = Prod; // e.g. X/-5 op -3 --> [15, 20) |
| LoOverflow = HiOverflow = ProdOV; |
| if (!HiOverflow) |
| HiOverflow = SubWithOverflow(HiBound, Prod, DivRHS, true); |
| } |
| |
| // Dividing by a negative swaps the condition. LT <-> GT |
| Pred = ICmpInst::getSwappedPredicate(Pred); |
| } |
| |
| Value *X = DivI->getOperand(0); |
| switch (Pred) { |
| default: assert(0 && "Unhandled icmp opcode!"); |
| case ICmpInst::ICMP_EQ: |
| if (LoOverflow && HiOverflow) |
| return ReplaceInstUsesWith(ICI, ConstantInt::getFalse()); |
| else if (HiOverflow) |
| return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE : |
| ICmpInst::ICMP_UGE, X, LoBound); |
| else if (LoOverflow) |
| return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT : |
| ICmpInst::ICMP_ULT, X, HiBound); |
| else |
| return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, true, ICI); |
| case ICmpInst::ICMP_NE: |
| if (LoOverflow && HiOverflow) |
| return ReplaceInstUsesWith(ICI, ConstantInt::getTrue()); |
| else if (HiOverflow) |
| return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT : |
| ICmpInst::ICMP_ULT, X, LoBound); |
| else if (LoOverflow) |
| return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE : |
| ICmpInst::ICMP_UGE, X, HiBound); |
| else |
| return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, false, ICI); |
| case ICmpInst::ICMP_ULT: |
| case ICmpInst::ICMP_SLT: |
| if (LoOverflow == +1) // Low bound is greater than input range. |
| return ReplaceInstUsesWith(ICI, ConstantInt::getTrue()); |
| if (LoOverflow == -1) // Low bound is less than input range. |
| return ReplaceInstUsesWith(ICI, ConstantInt::getFalse()); |
| return new ICmpInst(Pred, X, LoBound); |
| case ICmpInst::ICMP_UGT: |
| case ICmpInst::ICMP_SGT: |
| if (HiOverflow == +1) // High bound greater than input range. |
| return ReplaceInstUsesWith(ICI, ConstantInt::getFalse()); |
| else if (HiOverflow == -1) // High bound less than input range. |
| return ReplaceInstUsesWith(ICI, ConstantInt::getTrue()); |
| if (Pred == ICmpInst::ICMP_UGT) |
| return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound); |
| else |
| return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound); |
| } |
| } |
| |
| |
| /// visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)". |
| /// |
| Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI, |
| Instruction *LHSI, |
| ConstantInt *RHS) { |
| const APInt &RHSV = RHS->getValue(); |
| |
| switch (LHSI->getOpcode()) { |
| case Instruction::Trunc: |
| if (ICI.isEquality() && LHSI->hasOneUse()) { |
| // Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all |
| // of the high bits truncated out of x are known. |
| unsigned DstBits = LHSI->getType()->getPrimitiveSizeInBits(), |
| SrcBits = LHSI->getOperand(0)->getType()->getPrimitiveSizeInBits(); |
| APInt Mask(APInt::getHighBitsSet(SrcBits, SrcBits-DstBits)); |
| APInt KnownZero(SrcBits, 0), KnownOne(SrcBits, 0); |
| ComputeMaskedBits(LHSI->getOperand(0), Mask, KnownZero, KnownOne); |
| |
| // If all the high bits are known, we can do this xform. |
| if ((KnownZero|KnownOne).countLeadingOnes() >= SrcBits-DstBits) { |
| // Pull in the high bits from known-ones set. |
| APInt NewRHS(RHS->getValue()); |
| NewRHS.zext(SrcBits); |
| NewRHS |= KnownOne; |
| return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0), |
| ConstantInt::get(NewRHS)); |
| } |
| } |
| break; |
| |
| case Instruction::Xor: // (icmp pred (xor X, XorCST), CI) |
| if (ConstantInt *XorCST = dyn_cast<ConstantInt>(LHSI->getOperand(1))) { |
| // If this is a comparison that tests the signbit (X < 0) or (x > -1), |
| // fold the xor. |
| if ((ICI.getPredicate() == ICmpInst::ICMP_SLT && RHSV == 0) || |
| (ICI.getPredicate() == ICmpInst::ICMP_SGT && RHSV.isAllOnesValue())) { |
| Value *CompareVal = LHSI->getOperand(0); |
| |
| // If the sign bit of the XorCST is not set, there is no change to |
| // the operation, just stop using the Xor. |
| if (!XorCST->getValue().isNegative()) { |
| ICI.setOperand(0, CompareVal); |
| AddToWorkList(LHSI); |
| return &ICI; |
| } |
| |
| // Was the old condition true if the operand is positive? |
| bool isTrueIfPositive = ICI.getPredicate() == ICmpInst::ICMP_SGT; |
| |
| // If so, the new one isn't. |
| isTrueIfPositive ^= true; |
| |
| if (isTrueIfPositive) |
| return new ICmpInst(ICmpInst::ICMP_SGT, CompareVal, SubOne(RHS)); |
| else |
| return new ICmpInst(ICmpInst::ICMP_SLT, CompareVal, AddOne(RHS)); |
| } |
| } |
| break; |
| case Instruction::And: // (icmp pred (and X, AndCST), RHS) |
| if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) && |
| LHSI->getOperand(0)->hasOneUse()) { |
| ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1)); |
| |
| // If the LHS is an AND of a truncating cast, we can widen the |
| // and/compare to be the input width without changing the value |
| // produced, eliminating a cast. |
| if (TruncInst *Cast = dyn_cast<TruncInst>(LHSI->getOperand(0))) { |
| // We can do this transformation if either the AND constant does not |
| // have its sign bit set or if it is an equality comparison. |
| // Extending a relational comparison when we're checking the sign |
| // bit would not work. |
| if (Cast->hasOneUse() && |
| (ICI.isEquality() || |
| (AndCST->getValue().isNonNegative() && RHSV.isNonNegative()))) { |
| uint32_t BitWidth = |
| cast<IntegerType>(Cast->getOperand(0)->getType())->getBitWidth(); |
| APInt NewCST = AndCST->getValue(); |
| NewCST.zext(BitWidth); |
| APInt NewCI = RHSV; |
| NewCI.zext(BitWidth); |
| Instruction *NewAnd = |
| BinaryOperator::CreateAnd(Cast->getOperand(0), |
| ConstantInt::get(NewCST),LHSI->getName()); |
| InsertNewInstBefore(NewAnd, ICI); |
| return new ICmpInst(ICI.getPredicate(), NewAnd, |
| ConstantInt::get(NewCI)); |
| } |
| } |
| |
| // If this is: (X >> C1) & C2 != C3 (where any shift and any compare |
| // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This |
| // happens a LOT in code produced by the C front-end, for bitfield |
| // access. |
| BinaryOperator *Shift = dyn_cast<BinaryOperator>(LHSI->getOperand(0)); |
| if (Shift && !Shift->isShift()) |
| Shift = 0; |
| |
| ConstantInt *ShAmt; |
| ShAmt = Shift ? dyn_cast<ConstantInt>(Shift->getOperand(1)) : 0; |
| const Type *Ty = Shift ? Shift->getType() : 0; // Type of the shift. |
| const Type *AndTy = AndCST->getType(); // Type of the and. |
| |
| // We can fold this as long as we can't shift unknown bits |
| // into the mask. This can only happen with signed shift |
| // rights, as they sign-extend. |
| if (ShAmt) { |
| bool CanFold = Shift->isLogicalShift(); |
| if (!CanFold) { |
| // To test for the bad case of the signed shr, see if any |
| // of the bits shifted in could be tested after the mask. |
| uint32_t TyBits = Ty->getPrimitiveSizeInBits(); |
| int ShAmtVal = TyBits - ShAmt->getLimitedValue(TyBits); |
| |
| uint32_t BitWidth = AndTy->getPrimitiveSizeInBits(); |
| if ((APInt::getHighBitsSet(BitWidth, BitWidth-ShAmtVal) & |
| AndCST->getValue()) == 0) |
| CanFold = true; |
| } |
| |
| if (CanFold) { |
| Constant *NewCst; |
| if (Shift->getOpcode() == Instruction::Shl) |
| NewCst = ConstantExpr::getLShr(RHS, ShAmt); |
| else |
| NewCst = ConstantExpr::getShl(RHS, ShAmt); |
| |
| // Check to see if we are shifting out any of the bits being |
| // compared. |
| if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != RHS) { |
| // If we shifted bits out, the fold is not going to work out. |
| // As a special case, check to see if this means that the |
| // result is always true or false now. |
| if (ICI.getPredicate() == ICmpInst::ICMP_EQ) |
| return ReplaceInstUsesWith(ICI, ConstantInt::getFalse()); |
| if (ICI.getPredicate() == ICmpInst::ICMP_NE) |
| return ReplaceInstUsesWith(ICI, ConstantInt::getTrue()); |
| } else { |
| ICI.setOperand(1, NewCst); |
| Constant *NewAndCST; |
| if (Shift->getOpcode() == Instruction::Shl) |
| NewAndCST = ConstantExpr::getLShr(AndCST, ShAmt); |
| else |
| NewAndCST = ConstantExpr::getShl(AndCST, ShAmt); |
| LHSI->setOperand(1, NewAndCST); |
| LHSI->setOperand(0, Shift->getOperand(0)); |
| AddToWorkList(Shift); // Shift is dead. |
| AddUsesToWorkList(ICI); |
| return &ICI; |
| } |
| } |
| } |
| |
| // Turn ((X >> Y) & C) == 0 into (X & (C << Y)) == 0. The later is |
| // preferable because it allows the C<<Y expression to be hoisted out |
| // of a loop if Y is invariant and X is not. |
| if (Shift && Shift->hasOneUse() && RHSV == 0 && |
| ICI.isEquality() && !Shift->isArithmeticShift() && |
| isa<Instruction>(Shift->getOperand(0))) { |
| // Compute C << Y. |
| Value *NS; |
| if (Shift->getOpcode() == Instruction::LShr) { |
| NS = BinaryOperator::CreateShl(AndCST, |
| Shift->getOperand(1), "tmp"); |
| } else { |
| // Insert a logical shift. |
| NS = BinaryOperator::CreateLShr(AndCST, |
| Shift->getOperand(1), "tmp"); |
| } |
| InsertNewInstBefore(cast<Instruction>(NS), ICI); |
| |
| // Compute X & (C << Y). |
| Instruction *NewAnd = |
| BinaryOperator::CreateAnd(Shift->getOperand(0), NS, LHSI->getName()); |
| InsertNewInstBefore(NewAnd, ICI); |
| |
| ICI.setOperand(0, NewAnd); |
| return &ICI; |
| } |
| } |
| break; |
| |
| case Instruction::Shl: { // (icmp pred (shl X, ShAmt), CI) |
| ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1)); |
| if (!ShAmt) break; |
| |
| uint32_t TypeBits = RHSV.getBitWidth(); |
| |
| // Check that the shift amount is in range. If not, don't perform |
| // undefined shifts. When the shift is visited it will be |
| // simplified. |
| if (ShAmt->uge(TypeBits)) |
| break; |
| |
| if (ICI.isEquality()) { |
| // If we are comparing against bits always shifted out, the |
| // comparison cannot succeed. |
| Constant *Comp = |
| ConstantExpr::getShl(ConstantExpr::getLShr(RHS, ShAmt), ShAmt); |
| if (Comp != RHS) {// Comparing against a bit that we know is zero. |
| bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE; |
| Constant *Cst = ConstantInt::get(Type::Int1Ty, IsICMP_NE); |
| return ReplaceInstUsesWith(ICI, Cst); |
| } |
| |
| if (LHSI->hasOneUse()) { |
| // Otherwise strength reduce the shift into an and. |
| uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits); |
| Constant *Mask = |
| ConstantInt::get(APInt::getLowBitsSet(TypeBits, TypeBits-ShAmtVal)); |
| |
| Instruction *AndI = |
| BinaryOperator::CreateAnd(LHSI->getOperand(0), |
| Mask, LHSI->getName()+".mask"); |
| Value *And = InsertNewInstBefore(AndI, ICI); |
| return new ICmpInst(ICI.getPredicate(), And, |
| ConstantInt::get(RHSV.lshr(ShAmtVal))); |
| } |
| } |
| |
| // Otherwise, if this is a comparison of the sign bit, simplify to and/test. |
| bool TrueIfSigned = false; |
| if (LHSI->hasOneUse() && |
| isSignBitCheck(ICI.getPredicate(), RHS, TrueIfSigned)) { |
| // (X << 31) <s 0 --> (X&1) != 0 |
| Constant *Mask = ConstantInt::get(APInt(TypeBits, 1) << |
| (TypeBits-ShAmt->getZExtValue()-1)); |
| Instruction *AndI = |
| BinaryOperator::CreateAnd(LHSI->getOperand(0), |
| Mask, LHSI->getName()+".mask"); |
| Value *And = InsertNewInstBefore(AndI, ICI); |
| |
| return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ, |
| And, Constant::getNullValue(And->getType())); |
| } |
| break; |
| } |
| |
| case Instruction::LShr: // (icmp pred (shr X, ShAmt), CI) |
| case Instruction::AShr: { |
| // Only handle equality comparisons of shift-by-constant. |
| ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1)); |
| if (!ShAmt || !ICI.isEquality()) break; |
| |
| // Check that the shift amount is in range. If not, don't perform |
| // undefined shifts. When the shift is visited it will be |
| // simplified. |
| uint32_t TypeBits = RHSV.getBitWidth(); |
| if (ShAmt->uge(TypeBits)) |
| break; |
| |
| uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits); |
| |
| // If we are comparing against bits always shifted out, the |
| // comparison cannot succeed. |
| APInt Comp = RHSV << ShAmtVal; |
| if (LHSI->getOpcode() == Instruction::LShr) |
| Comp = Comp.lshr(ShAmtVal); |
| else |
| Comp = Comp.ashr(ShAmtVal); |
| |
| if (Comp != RHSV) { // Comparing against a bit that we know is zero. |
| bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE; |
| Constant *Cst = ConstantInt::get(Type::Int1Ty, IsICMP_NE); |
| return ReplaceInstUsesWith(ICI, Cst); |
| } |
| |
| // Otherwise, check to see if the bits shifted out are known to be zero. |
| // If so, we can compare against the unshifted value: |
| // (X & 4) >> 1 == 2 --> (X & 4) == 4. |
| if (LHSI->hasOneUse() && |
| MaskedValueIsZero(LHSI->getOperand(0), |
| APInt::getLowBitsSet(Comp.getBitWidth(), ShAmtVal))) { |
| return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0), |
| ConstantExpr::getShl(RHS, ShAmt)); |
| } |
| |
| if (LHSI->hasOneUse()) { |
| // Otherwise strength reduce the shift into an and. |
| APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal)); |
| Constant *Mask = ConstantInt::get(Val); |
| |
| Instruction *AndI = |
| BinaryOperator::CreateAnd(LHSI->getOperand(0), |
| Mask, LHSI->getName()+".mask"); |
| Value *And = InsertNewInstBefore(AndI, ICI); |
| return new ICmpInst(ICI.getPredicate(), And, |
| ConstantExpr::getShl(RHS, ShAmt)); |
| } |
| break; |
| } |
| |
| case Instruction::SDiv: |
| case Instruction::UDiv: |
| // Fold: icmp pred ([us]div X, C1), C2 -> range test |
| // Fold this div into the comparison, producing a range check. |
| // Determine, based on the divide type, what the range is being |
| // checked. If there is an overflow on the low or high side, remember |
| // it, otherwise compute the range [low, hi) bounding the new value. |
| // See: InsertRangeTest above for the kinds of replacements possible. |
| if (ConstantInt *DivRHS = dyn_cast<ConstantInt>(LHSI->getOperand(1))) |
| if (Instruction *R = FoldICmpDivCst(ICI, cast<BinaryOperator>(LHSI), |
| DivRHS)) |
| return R; |
| break; |
| |
| case Instruction::Add: |
| // Fold: icmp pred (add, X, C1), C2 |
| |
| if (!ICI.isEquality()) { |
| ConstantInt *LHSC = dyn_cast<ConstantInt>(LHSI->getOperand(1)); |
| if (!LHSC) break; |
| const APInt &LHSV = LHSC->getValue(); |
| |
| ConstantRange CR = ICI.makeConstantRange(ICI.getPredicate(), RHSV) |
| .subtract(LHSV); |
| |
| if (ICI.isSignedPredicate()) { |
| if (CR.getLower().isSignBit()) { |
| return new ICmpInst(ICmpInst::ICMP_SLT, LHSI->getOperand(0), |
| ConstantInt::get(CR.getUpper())); |
| } else if (CR.getUpper().isSignBit()) { |
| return new ICmpInst(ICmpInst::ICMP_SGE, LHSI->getOperand(0), |
| ConstantInt::get(CR.getLower())); |
| } |
| } else { |
| if (CR.getLower().isMinValue()) { |
| return new ICmpInst(ICmpInst::ICMP_ULT, LHSI->getOperand(0), |
| ConstantInt::get(CR.getUpper())); |
| } else if (CR.getUpper().isMinValue()) { |
| return new ICmpInst(ICmpInst::ICMP_UGE, LHSI->getOperand(0), |
| ConstantInt::get(CR.getLower())); |
| } |
| } |
| } |
| break; |
| } |
| |
| // Simplify icmp_eq and icmp_ne instructions with integer constant RHS. |
| if (ICI.isEquality()) { |
| bool isICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE; |
| |
| // If the first operand is (add|sub|and|or|xor|rem) with a constant, and |
| // the second operand is a constant, simplify a bit. |
| if (BinaryOperator *BO = dyn_cast<BinaryOperator>(LHSI)) { |
| switch (BO->getOpcode()) { |
| case Instruction::SRem: |
| // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one. |
| if (RHSV == 0 && isa<ConstantInt>(BO->getOperand(1)) &&BO->hasOneUse()){ |
| const APInt &V = cast<ConstantInt>(BO->getOperand(1))->getValue(); |
| if (V.sgt(APInt(V.getBitWidth(), 1)) && V.isPowerOf2()) { |
| Instruction *NewRem = |
| BinaryOperator::CreateURem(BO->getOperand(0), BO->getOperand(1), |
| BO->getName()); |
| InsertNewInstBefore(NewRem, ICI); |
| return new ICmpInst(ICI.getPredicate(), NewRem, |
| Constant::getNullValue(BO->getType())); |
| } |
| } |
| break; |
| case Instruction::Add: |
| // Replace ((add A, B) != C) with (A != C-B) if B & C are constants. |
| if (ConstantInt *BOp1C = dyn_cast<ConstantInt>(BO->getOperand(1))) { |
| if (BO->hasOneUse()) |
| return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), |
| Subtract(RHS, BOp1C)); |
| } else if (RHSV == 0) { |
| // Replace ((add A, B) != 0) with (A != -B) if A or B is |
| // efficiently invertible, or if the add has just this one use. |
| Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1); |
| |
| if (Value *NegVal = dyn_castNegVal(BOp1)) |
| return new ICmpInst(ICI.getPredicate(), BOp0, NegVal); |
| else if (Value *NegVal = dyn_castNegVal(BOp0)) |
| return new ICmpInst(ICI.getPredicate(), NegVal, BOp1); |
| else if (BO->hasOneUse()) { |
| Instruction *Neg = BinaryOperator::CreateNeg(BOp1); |
| InsertNewInstBefore(Neg, ICI); |
| Neg->takeName(BO); |
| return new ICmpInst(ICI.getPredicate(), BOp0, Neg); |
| } |
| } |
| break; |
| case Instruction::Xor: |
| // For the xor case, we can xor two constants together, eliminating |
| // the explicit xor. |
| if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) |
| return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), |
| ConstantExpr::getXor(RHS, BOC)); |
| |
| // FALLTHROUGH |
| case Instruction::Sub: |
| // Replace (([sub|xor] A, B) != 0) with (A != B) |
| if (RHSV == 0) |
| return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), |
| BO->getOperand(1)); |
| break; |
| |
| case Instruction::Or: |
| // If bits are being or'd in that are not present in the constant we |
| // are comparing against, then the comparison could never succeed! |
| if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) { |
| Constant *NotCI = ConstantExpr::getNot(RHS); |
| if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue()) |
| return ReplaceInstUsesWith(ICI, ConstantInt::get(Type::Int1Ty, |
| isICMP_NE)); |
| } |
| break; |
| |
| case Instruction::And: |
| if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) { |
| // If bits are being compared against that are and'd out, then the |
| // comparison can never succeed! |
| if ((RHSV & ~BOC->getValue()) != 0) |
| return ReplaceInstUsesWith(ICI, ConstantInt::get(Type::Int1Ty, |
| isICMP_NE)); |
| |
| // If we have ((X & C) == C), turn it into ((X & C) != 0). |
| if (RHS == BOC && RHSV.isPowerOf2()) |
| return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ : |
| ICmpInst::ICMP_NE, LHSI, |
| Constant::getNullValue(RHS->getType())); |
| |
| // Replace (and X, (1 << size(X)-1) != 0) with x s< 0 |
| if (BOC->getValue().isSignBit()) { |
| Value *X = BO->getOperand(0); |
| Constant *Zero = Constant::getNullValue(X->getType()); |
| ICmpInst::Predicate pred = isICMP_NE ? |
| ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE; |
| return new ICmpInst(pred, X, Zero); |
| } |
| |
| // ((X & ~7) == 0) --> X < 8 |
| if (RHSV == 0 && isHighOnes(BOC)) { |
| Value *X = BO->getOperand(0); |
| Constant *NegX = ConstantExpr::getNeg(BOC); |
| ICmpInst::Predicate pred = isICMP_NE ? |
| ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT; |
| return new ICmpInst(pred, X, NegX); |
| } |
| } |
| default: break; |
| } |
| } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(LHSI)) { |
| // Handle icmp {eq|ne} <intrinsic>, intcst. |
| if (II->getIntrinsicID() == Intrinsic::bswap) { |
| AddToWorkList(II); |
| ICI.setOperand(0, II->getOperand(1)); |
| ICI.setOperand(1, ConstantInt::get(RHSV.byteSwap())); |
| return &ICI; |
| } |
| } |
| } |
| return 0; |
| } |
| |
| /// visitICmpInstWithCastAndCast - Handle icmp (cast x to y), (cast/cst). |
| /// We only handle extending casts so far. |
| /// |
| Instruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) { |
| const CastInst *LHSCI = cast<CastInst>(ICI.getOperand(0)); |
| Value *LHSCIOp = LHSCI->getOperand(0); |
| const Type *SrcTy = LHSCIOp->getType(); |
| const Type *DestTy = LHSCI->getType(); |
| Value *RHSCIOp; |
| |
| // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the |
| // integer type is the same size as the pointer type. |
| if (LHSCI->getOpcode() == Instruction::PtrToInt && |
| getTargetData().getPointerSizeInBits() == |
| cast<IntegerType>(DestTy)->getBitWidth()) { |
| Value *RHSOp = 0; |
| if (Constant *RHSC = dyn_cast<Constant>(ICI.getOperand(1))) { |
| RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy); |
| } else if (PtrToIntInst *RHSC = dyn_cast<PtrToIntInst>(ICI.getOperand(1))) { |
| RHSOp = RHSC->getOperand(0); |
| // If the pointer types don't match, insert a bitcast. |
| if (LHSCIOp->getType() != RHSOp->getType()) |
| RHSOp = InsertBitCastBefore(RHSOp, LHSCIOp->getType(), ICI); |
| } |
| |
| if (RHSOp) |
| return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSOp); |
| } |
| |
| // The code below only handles extension cast instructions, so far. |
| // Enforce this. |
| if (LHSCI->getOpcode() != Instruction::ZExt && |
| LHSCI->getOpcode() != Instruction::SExt) |
| return 0; |
| |
| bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt; |
| bool isSignedCmp = ICI.isSignedPredicate(); |
| |
| if (CastInst *CI = dyn_cast<CastInst>(ICI.getOperand(1))) { |
| // Not an extension from the same type? |
| RHSCIOp = CI->getOperand(0); |
| if (RHSCIOp->getType() != LHSCIOp->getType()) |
| return 0; |
| |
| // If the signedness of the two casts doesn't agree (i.e. one is a sext |
| // and the other is a zext), then we can't handle this. |
| if (CI->getOpcode() != LHSCI->getOpcode()) |
| return 0; |
| |
| // Deal with equality cases early. |
| if (ICI.isEquality()) |
| return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp); |
| |
| // A signed comparison of sign extended values simplifies into a |
| // signed comparison. |
| if (isSignedCmp && isSignedExt) |
| return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp); |
| |
| // The other three cases all fold into an unsigned comparison. |
| return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, RHSCIOp); |
| } |
| |
| // If we aren't dealing with a constant on the RHS, exit early |
| ConstantInt *CI = dyn_cast<ConstantInt>(ICI.getOperand(1)); |
| if (!CI) |
| return 0; |
| |
| // Compute the constant that would happen if we truncated to SrcTy then |
| // reextended to DestTy. |
| Constant *Res1 = ConstantExpr::getTrunc(CI, SrcTy); |
| Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(), Res1, DestTy); |
| |
| // If the re-extended constant didn't change... |
| if (Res2 == CI) { |
| // Make sure that sign of the Cmp and the sign of the Cast are the same. |
| // For example, we might have: |
| // %A = sext short %X to uint |
| // %B = icmp ugt uint %A, 1330 |
| // It is incorrect to transform this into |
| // %B = icmp ugt short %X, 1330 |
| // because %A may have negative value. |
| // |
| // However, we allow this when the compare is EQ/NE, because they are |
| // signless. |
| if (isSignedExt == isSignedCmp || ICI.isEquality()) |
| return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1); |
| return 0; |
| } |
| |
| // The re-extended constant changed so the constant cannot be represented |
| // in the shorter type. Consequently, we cannot emit a simple comparison. |
| |
| // First, handle some easy cases. We know the result cannot be equal at this |
| // point so handle the ICI.isEquality() cases |
| if (ICI.getPredicate() == ICmpInst::ICMP_EQ) |
| return ReplaceInstUsesWith(ICI, ConstantInt::getFalse()); |
| if (ICI.getPredicate() == ICmpInst::ICMP_NE) |
| return ReplaceInstUsesWith(ICI, ConstantInt::getTrue()); |
| |
| // Evaluate the comparison for LT (we invert for GT below). LE and GE cases |
| // should have been folded away previously and not enter in here. |
| Value *Result; |
| if (isSignedCmp) { |
| // We're performing a signed comparison. |
| if (cast<ConstantInt>(CI)->getValue().isNegative()) |
| Result = ConstantInt::getFalse(); // X < (small) --> false |
| else |
| Result = ConstantInt::getTrue(); // X < (large) --> true |
| } else { |
| // We're performing an unsigned comparison. |
| if (isSignedExt) { |
| // We're performing an unsigned comp with a sign extended value. |
| // This is true if the input is >= 0. [aka >s -1] |
| Constant *NegOne = ConstantInt::getAllOnesValue(SrcTy); |
| Result = InsertNewInstBefore(new ICmpInst(ICmpInst::ICMP_SGT, LHSCIOp, |
| NegOne, ICI.getName()), ICI); |
| } else { |
| // Unsigned extend & unsigned compare -> always true. |
| Result = ConstantInt::getTrue(); |
| } |
| } |
| |
| // Finally, return the value computed. |
| if (ICI.getPredicate() == ICmpInst::ICMP_ULT || |
| ICI.getPredicate() == ICmpInst::ICMP_SLT) |
| return ReplaceInstUsesWith(ICI, Result); |
| |
| assert((ICI.getPredicate()==ICmpInst::ICMP_UGT || |
| ICI.getPredicate()==ICmpInst::ICMP_SGT) && |
| "ICmp should be folded!"); |
| if (Constant *CI = dyn_cast<Constant>(Result)) |
| return ReplaceInstUsesWith(ICI, ConstantExpr::getNot(CI)); |
| return BinaryOperator::CreateNot(Result); |
| } |
| |
| Instruction *InstCombiner::visitShl(BinaryOperator &I) { |
| return commonShiftTransforms(I); |
| } |
| |
| Instruction *InstCombiner::visitLShr(BinaryOperator &I) { |
| return commonShiftTransforms(I); |
| } |
| |
| Instruction *InstCombiner::visitAShr(BinaryOperator &I) { |
| if (Instruction *R = commonShiftTransforms(I)) |
| return R; |
| |
| Value *Op0 = I.getOperand(0); |
| |
| // ashr int -1, X = -1 (for any arithmetic shift rights of ~0) |
| if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0)) |
| if (CSI->isAllOnesValue()) |
| return ReplaceInstUsesWith(I, CSI); |
| |
| // See if we can turn a signed shr into an unsigned shr. |
| if (!isa<VectorType>(I.getType()) && |
| MaskedValueIsZero(Op0, |
| APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()))) |
| return BinaryOperator::CreateLShr(Op0, I.getOperand(1)); |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::commonShiftTransforms(BinaryOperator &I) { |
| assert(I.getOperand(1)->getType() == I.getOperand(0)->getType()); |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| // shl X, 0 == X and shr X, 0 == X |
| // shl 0, X == 0 and shr 0, X == 0 |
| if (Op1 == Constant::getNullValue(Op1->getType()) || |
| Op0 == Constant::getNullValue(Op0->getType())) |
| return ReplaceInstUsesWith(I, Op0); |
| |
| if (isa<UndefValue>(Op0)) { |
| if (I.getOpcode() == Instruction::AShr) // undef >>s X -> undef |
| return ReplaceInstUsesWith(I, Op0); |
| else // undef << X -> 0, undef >>u X -> 0 |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| } |
| if (isa<UndefValue>(Op1)) { |
| if (I.getOpcode() == Instruction::AShr) // X >>s undef -> X |
| return ReplaceInstUsesWith(I, Op0); |
| else // X << undef, X >>u undef -> 0 |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| } |
| |
| // Try to fold constant and into select arguments. |
| if (isa<Constant>(Op0)) |
| if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) |
| if (Instruction *R = FoldOpIntoSelect(I, SI, this)) |
| return R; |
| |
| if (ConstantInt *CUI = dyn_cast<ConstantInt>(Op1)) |
| if (Instruction *Res = FoldShiftByConstant(Op0, CUI, I)) |
| return Res; |
| return 0; |
| } |
| |
| Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1, |
| BinaryOperator &I) { |
| bool isLeftShift = I.getOpcode() == Instruction::Shl; |
| |
| // See if we can simplify any instructions used by the instruction whose sole |
| // purpose is to compute bits we don't care about. |
| uint32_t TypeBits = Op0->getType()->getPrimitiveSizeInBits(); |
| APInt KnownZero(TypeBits, 0), KnownOne(TypeBits, 0); |
| if (SimplifyDemandedBits(&I, APInt::getAllOnesValue(TypeBits), |
| KnownZero, KnownOne)) |
| return &I; |
| |
| // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr |
| // of a signed value. |
| // |
| if (Op1->uge(TypeBits)) { |
| if (I.getOpcode() != Instruction::AShr) |
| return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType())); |
| else { |
| I.setOperand(1, ConstantInt::get(I.getType(), TypeBits-1)); |
| return &I; |
| } |
| } |
| |
| // ((X*C1) << C2) == (X * (C1 << C2)) |
| if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) |
| if (BO->getOpcode() == Instruction::Mul && isLeftShift) |
| if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1))) |
| return BinaryOperator::CreateMul(BO->getOperand(0), |
| ConstantExpr::getShl(BOOp, Op1)); |
| |
| // Try to fold constant and into select arguments. |
| if (SelectInst *SI = dyn_cast<SelectInst>(Op0)) |
| if (Instruction *R = FoldOpIntoSelect(I, SI, this)) |
| return R; |
| if (isa<PHINode>(Op0)) |
| if (Instruction *NV = FoldOpIntoPhi(I)) |
| return NV; |
| |
| // Fold shift2(trunc(shift1(x,c1)), c2) -> trunc(shift2(shift1(x,c1),c2)) |
| if (TruncInst *TI = dyn_cast<TruncInst>(Op0)) { |
| Instruction *TrOp = dyn_cast<Instruction>(TI->getOperand(0)); |
| // If 'shift2' is an ashr, we would have to get the sign bit into a funny |
| // place. Don't try to do this transformation in this case. Also, we |
| // require that the input operand is a shift-by-constant so that we have |
| // confidence that the shifts will get folded together. We could do this |
| // xform in more cases, but it is unlikely to be profitable. |
| if (TrOp && I.isLogicalShift() && TrOp->isShift() && |
| isa<ConstantInt>(TrOp->getOperand(1))) { |
| // Okay, we'll do this xform. Make the shift of shift. |
| Constant *ShAmt = ConstantExpr::getZExt(Op1, TrOp->getType()); |
| Instruction *NSh = BinaryOperator::Create(I.getOpcode(), TrOp, ShAmt, |
| I.getName()); |
| InsertNewInstBefore(NSh, I); // (shift2 (shift1 & 0x00FF), c2) |
| |
| // For logical shifts, the truncation has the effect of making the high |
| // part of the register be zeros. Emulate this by inserting an AND to |
| // clear the top bits as needed. This 'and' will usually be zapped by |
| // other xforms later if dead. |
| unsigned SrcSize = TrOp->getType()->getPrimitiveSizeInBits(); |
| unsigned DstSize = TI->getType()->getPrimitiveSizeInBits(); |
| APInt MaskV(APInt::getLowBitsSet(SrcSize, DstSize)); |
| |
| // The mask we constructed says what the trunc would do if occurring |
| // between the shifts. We want to know the effect *after* the second |
| // shift. We know that it is a logical shift by a constant, so adjust the |
| // mask as appropriate. |
| if (I.getOpcode() == Instruction::Shl) |
| MaskV <<= Op1->getZExtValue(); |
| else { |
| assert(I.getOpcode() == Instruction::LShr && "Unknown logical shift"); |
| MaskV = MaskV.lshr(Op1->getZExtValue()); |
| } |
| |
| Instruction *And = BinaryOperator::CreateAnd(NSh, ConstantInt::get(MaskV), |
| TI->getName()); |
| InsertNewInstBefore(And, I); // shift1 & 0x00FF |
| |
| // Return the value truncated to the interesting size. |
| return new TruncInst(And, I.getType()); |
| } |
| } |
| |
| if (Op0->hasOneUse()) { |
| if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0)) { |
| // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C) |
| Value *V1, *V2; |
| ConstantInt *CC; |
| switch (Op0BO->getOpcode()) { |
| default: break; |
| case Instruction::Add: |
| case Instruction::And: |
| case Instruction::Or: |
| case Instruction::Xor: { |
| // These operators commute. |
| // Turn (Y + (X >> C)) << C -> (X + (Y << C)) & (~0 << C) |
| if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() && |
| match(Op0BO->getOperand(1), m_Shr(m_Value(V1), m_Specific(Op1)))){ |
| Instruction *YS = BinaryOperator::CreateShl( |
| Op0BO->getOperand(0), Op1, |
| Op0BO->getName()); |
| InsertNewInstBefore(YS, I); // (Y << C) |
| Instruction *X = |
| BinaryOperator::Create(Op0BO->getOpcode(), YS, V1, |
| Op0BO->getOperand(1)->getName()); |
| InsertNewInstBefore(X, I); // (X + (Y << C)) |
| uint32_t Op1Val = Op1->getLimitedValue(TypeBits); |
| return BinaryOperator::CreateAnd(X, ConstantInt::get( |
| APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val))); |
| } |
| |
| // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C)) |
| Value *Op0BOOp1 = Op0BO->getOperand(1); |
| if (isLeftShift && Op0BOOp1->hasOneUse() && |
| match(Op0BOOp1, |
| m_And(m_Shr(m_Value(V1), m_Specific(Op1)), |
| m_ConstantInt(CC))) && |
| cast<BinaryOperator>(Op0BOOp1)->getOperand(0)->hasOneUse()) { |
| Instruction *YS = BinaryOperator::CreateShl( |
| Op0BO->getOperand(0), Op1, |
| Op0BO->getName()); |
| InsertNewInstBefore(YS, I); // (Y << C) |
| Instruction *XM = |
| BinaryOperator::CreateAnd(V1, ConstantExpr::getShl(CC, Op1), |
| V1->getName()+".mask"); |
| InsertNewInstBefore(XM, I); // X & (CC << C) |
| |
| return BinaryOperator::Create(Op0BO->getOpcode(), YS, XM); |
| } |
| } |
| |
| // FALL THROUGH. |
| case Instruction::Sub: { |
| // Turn ((X >> C) + Y) << C -> (X + (Y << C)) & (~0 << C) |
| if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() && |
| match(Op0BO->getOperand(0), m_Shr(m_Value(V1), m_Specific(Op1)))){ |
| Instruction *YS = BinaryOperator::CreateShl( |
| Op0BO->getOperand(1), Op1, |
| Op0BO->getName()); |
| InsertNewInstBefore(YS, I); // (Y << C) |
| Instruction *X = |
| BinaryOperator::Create(Op0BO->getOpcode(), V1, YS, |
| Op0BO->getOperand(0)->getName()); |
| InsertNewInstBefore(X, I); // (X + (Y << C)) |
| uint32_t Op1Val = Op1->getLimitedValue(TypeBits); |
| return BinaryOperator::CreateAnd(X, ConstantInt::get( |
| APInt::getHighBitsSet(TypeBits, TypeBits-Op1Val))); |
| } |
| |
| // Turn (((X >> C)&CC) + Y) << C -> (X + (Y << C)) & (CC << C) |
| if (isLeftShift && Op0BO->getOperand(0)->hasOneUse() && |
| match(Op0BO->getOperand(0), |
| m_And(m_Shr(m_Value(V1), m_Value(V2)), |
| m_ConstantInt(CC))) && V2 == Op1 && |
| cast<BinaryOperator>(Op0BO->getOperand(0)) |
| ->getOperand(0)->hasOneUse()) { |
| Instruction *YS = BinaryOperator::CreateShl( |
| Op0BO->getOperand(1), Op1, |
| Op0BO->getName()); |
| InsertNewInstBefore(YS, I); // (Y << C) |
| Instruction *XM = |
| BinaryOperator::CreateAnd(V1, ConstantExpr::getShl(CC, Op1), |
| V1->getName()+".mask"); |
| InsertNewInstBefore(XM, I); // X & (CC << C) |
| |
| return BinaryOperator::Create(Op0BO->getOpcode(), XM, YS); |
| } |
| |
| break; |
| } |
| } |
| |
| |
| // If the operand is an bitwise operator with a constant RHS, and the |
| // shift is the only use, we can pull it out of the shift. |
| if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) { |
| bool isValid = true; // Valid only for And, Or, Xor |
| bool highBitSet = false; // Transform if high bit of constant set? |
| |
| switch (Op0BO->getOpcode()) { |
| default: isValid = false; break; // Do not perform transform! |
| case Instruction::Add: |
| isValid = isLeftShift; |
| break; |
| case Instruction::Or: |
| case Instruction::Xor: |
| highBitSet = false; |
| break; |
| case Instruction::And: |
| highBitSet = true; |
| break; |
| } |
| |
| // If this is a signed shift right, and the high bit is modified |
| // by the logical operation, do not perform the transformation. |
| // The highBitSet boolean indicates the value of the high bit of |
| // the constant which would cause it to be modified for this |
| // operation. |
| // |
| if (isValid && I.getOpcode() == Instruction::AShr) |
| isValid = Op0C->getValue()[TypeBits-1] == highBitSet; |
| |
| if (isValid) { |
| Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, Op1); |
| |
| Instruction *NewShift = |
| BinaryOperator::Create(I.getOpcode(), Op0BO->getOperand(0), Op1); |
| InsertNewInstBefore(NewShift, I); |
| NewShift->takeName(Op0BO); |
| |
| return BinaryOperator::Create(Op0BO->getOpcode(), NewShift, |
| NewRHS); |
| } |
| } |
| } |
| } |
| |
| // Find out if this is a shift of a shift by a constant. |
| BinaryOperator *ShiftOp = dyn_cast<BinaryOperator>(Op0); |
| if (ShiftOp && !ShiftOp->isShift()) |
| ShiftOp = 0; |
| |
| if (ShiftOp && isa<ConstantInt>(ShiftOp->getOperand(1))) { |
| ConstantInt *ShiftAmt1C = cast<ConstantInt>(ShiftOp->getOperand(1)); |
| uint32_t ShiftAmt1 = ShiftAmt1C->getLimitedValue(TypeBits); |
| uint32_t ShiftAmt2 = Op1->getLimitedValue(TypeBits); |
| assert(ShiftAmt2 != 0 && "Should have been simplified earlier"); |
| if (ShiftAmt1 == 0) return 0; // Will be simplified in the future. |
| Value *X = ShiftOp->getOperand(0); |
| |
| uint32_t AmtSum = ShiftAmt1+ShiftAmt2; // Fold into one big shift. |
| if (AmtSum > TypeBits) |
| AmtSum = TypeBits; |
| |
| const IntegerType *Ty = cast<IntegerType>(I.getType()); |
| |
| // Check for (X << c1) << c2 and (X >> c1) >> c2 |
| if (I.getOpcode() == ShiftOp->getOpcode()) { |
| return BinaryOperator::Create(I.getOpcode(), X, |
| ConstantInt::get(Ty, AmtSum)); |
| } else if (ShiftOp->getOpcode() == Instruction::LShr && |
| I.getOpcode() == Instruction::AShr) { |
| // ((X >>u C1) >>s C2) -> (X >>u (C1+C2)) since C1 != 0. |
| return BinaryOperator::CreateLShr(X, ConstantInt::get(Ty, AmtSum)); |
| } else if (ShiftOp->getOpcode() == Instruction::AShr && |
| I.getOpcode() == Instruction::LShr) { |
| // ((X >>s C1) >>u C2) -> ((X >>s (C1+C2)) & mask) since C1 != 0. |
| Instruction *Shift = |
| BinaryOperator::CreateAShr(X, ConstantInt::get(Ty, AmtSum)); |
| InsertNewInstBefore(Shift, I); |
| |
| APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2)); |
| return BinaryOperator::CreateAnd(Shift, ConstantInt::get(Mask)); |
| } |
| |
| // Okay, if we get here, one shift must be left, and the other shift must be |
| // right. See if the amounts are equal. |
| if (ShiftAmt1 == ShiftAmt2) { |
| // If we have ((X >>? C) << C), turn this into X & (-1 << C). |
| if (I.getOpcode() == Instruction::Shl) { |
| APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt1)); |
| return BinaryOperator::CreateAnd(X, ConstantInt::get(Mask)); |
| } |
| // If we have ((X << C) >>u C), turn this into X & (-1 >>u C). |
| if (I.getOpcode() == Instruction::LShr) { |
| APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt1)); |
| return BinaryOperator::CreateAnd(X, ConstantInt::get(Mask)); |
| } |
| // We can simplify ((X << C) >>s C) into a trunc + sext. |
| // NOTE: we could do this for any C, but that would make 'unusual' integer |
| // types. For now, just stick to ones well-supported by the code |
| // generators. |
| const Type *SExtType = 0; |
| switch (Ty->getBitWidth() - ShiftAmt1) { |
| case 1 : |
| case 8 : |
| case 16 : |
| case 32 : |
| case 64 : |
| case 128: |
| SExtType = IntegerType::get(Ty->getBitWidth() - ShiftAmt1); |
| break; |
| default: break; |
| } |
| if (SExtType) { |
| Instruction *NewTrunc = new TruncInst(X, SExtType, "sext"); |
| InsertNewInstBefore(NewTrunc, I); |
| return new SExtInst(NewTrunc, Ty); |
| } |
| // Otherwise, we can't handle it yet. |
| } else if (ShiftAmt1 < ShiftAmt2) { |
| uint32_t ShiftDiff = ShiftAmt2-ShiftAmt1; |
| |
| // (X >>? C1) << C2 --> X << (C2-C1) & (-1 << C2) |
| if (I.getOpcode() == Instruction::Shl) { |
| assert(ShiftOp->getOpcode() == Instruction::LShr || |
| ShiftOp->getOpcode() == Instruction::AShr); |
| Instruction *Shift = |
| BinaryOperator::CreateShl(X, ConstantInt::get(Ty, ShiftDiff)); |
| InsertNewInstBefore(Shift, I); |
| |
| APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt2)); |
| return BinaryOperator::CreateAnd(Shift, ConstantInt::get(Mask)); |
| } |
| |
| // (X << C1) >>u C2 --> X >>u (C2-C1) & (-1 >> C2) |
| if (I.getOpcode() == Instruction::LShr) { |
| assert(ShiftOp->getOpcode() == Instruction::Shl); |
| Instruction *Shift = |
| BinaryOperator::CreateLShr(X, ConstantInt::get(Ty, ShiftDiff)); |
| InsertNewInstBefore(Shift, I); |
| |
| APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2)); |
| return BinaryOperator::CreateAnd(Shift, ConstantInt::get(Mask)); |
| } |
| |
| // We can't handle (X << C1) >>s C2, it shifts arbitrary bits in. |
| } else { |
| assert(ShiftAmt2 < ShiftAmt1); |
| uint32_t ShiftDiff = ShiftAmt1-ShiftAmt2; |
| |
| // (X >>? C1) << C2 --> X >>? (C1-C2) & (-1 << C2) |
| if (I.getOpcode() == Instruction::Shl) { |
| assert(ShiftOp->getOpcode() == Instruction::LShr || |
| ShiftOp->getOpcode() == Instruction::AShr); |
| Instruction *Shift = |
| BinaryOperator::Create(ShiftOp->getOpcode(), X, |
| ConstantInt::get(Ty, ShiftDiff)); |
| InsertNewInstBefore(Shift, I); |
| |
| APInt Mask(APInt::getHighBitsSet(TypeBits, TypeBits - ShiftAmt2)); |
| return BinaryOperator::CreateAnd(Shift, ConstantInt::get(Mask)); |
| } |
| |
| // (X << C1) >>u C2 --> X << (C1-C2) & (-1 >> C2) |
| if (I.getOpcode() == Instruction::LShr) { |
| assert(ShiftOp->getOpcode() == Instruction::Shl); |
| Instruction *Shift = |
| BinaryOperator::CreateShl(X, ConstantInt::get(Ty, ShiftDiff)); |
| InsertNewInstBefore(Shift, I); |
| |
| APInt Mask(APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt2)); |
| return BinaryOperator::CreateAnd(Shift, ConstantInt::get(Mask)); |
| } |
| |
| // We can't handle (X << C1) >>a C2, it shifts arbitrary bits in. |
| } |
| } |
| return 0; |
| } |
| |
| |
| /// DecomposeSimpleLinearExpr - Analyze 'Val', seeing if it is a simple linear |
| /// expression. If so, decompose it, returning some value X, such that Val is |
| /// X*Scale+Offset. |
| /// |
| static Value *DecomposeSimpleLinearExpr(Value *Val, unsigned &Scale, |
| int &Offset) { |
| assert(Val->getType() == Type::Int32Ty && "Unexpected allocation size type!"); |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) { |
| Offset = CI->getZExtValue(); |
| Scale = 0; |
| return ConstantInt::get(Type::Int32Ty, 0); |
| } else if (BinaryOperator *I = dyn_cast<BinaryOperator>(Val)) { |
| if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| if (I->getOpcode() == Instruction::Shl) { |
| // This is a value scaled by '1 << the shift amt'. |
| Scale = 1U << RHS->getZExtValue(); |
| Offset = 0; |
| return I->getOperand(0); |
| } else if (I->getOpcode() == Instruction::Mul) { |
| // This value is scaled by 'RHS'. |
| Scale = RHS->getZExtValue(); |
| Offset = 0; |
| return I->getOperand(0); |
| } else if (I->getOpcode() == Instruction::Add) { |
| // We have X+C. Check to see if we really have (X*C2)+C1, |
| // where C1 is divisible by C2. |
| unsigned SubScale; |
| Value *SubVal = |
| DecomposeSimpleLinearExpr(I->getOperand(0), SubScale, Offset); |
| Offset += RHS->getZExtValue(); |
| Scale = SubScale; |
| return SubVal; |
| } |
| } |
| } |
| |
| // Otherwise, we can't look past this. |
| Scale = 1; |
| Offset = 0; |
| return Val; |
| } |
| |
| |
| /// PromoteCastOfAllocation - If we find a cast of an allocation instruction, |
| /// try to eliminate the cast by moving the type information into the alloc. |
| Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI, |
| AllocationInst &AI) { |
| const PointerType *PTy = cast<PointerType>(CI.getType()); |
| |
| // Remove any uses of AI that are dead. |
| assert(!CI.use_empty() && "Dead instructions should be removed earlier!"); |
| |
| for (Value::use_iterator UI = AI.use_begin(), E = AI.use_end(); UI != E; ) { |
| Instruction *User = cast<Instruction>(*UI++); |
| if (isInstructionTriviallyDead(User)) { |
| while (UI != E && *UI == User) |
| ++UI; // If this instruction uses AI more than once, don't break UI. |
| |
| ++NumDeadInst; |
| DOUT << "IC: DCE: " << *User; |
| EraseInstFromFunction(*User); |
| } |
| } |
| |
| // Get the type really allocated and the type casted to. |
| const Type *AllocElTy = AI.getAllocatedType(); |
| const Type *CastElTy = PTy->getElementType(); |
| if (!AllocElTy->isSized() || !CastElTy->isSized()) return 0; |
| |
| unsigned AllocElTyAlign = TD->getABITypeAlignment(AllocElTy); |
| unsigned CastElTyAlign = TD->getABITypeAlignment(CastElTy); |
| if (CastElTyAlign < AllocElTyAlign) return 0; |
| |
| // If the allocation has multiple uses, only promote it if we are strictly |
| // increasing the alignment of the resultant allocation. If we keep it the |
| // same, we open the door to infinite loops of various kinds. |
| if (!AI.hasOneUse() && CastElTyAlign == AllocElTyAlign) return 0; |
| |
| uint64_t AllocElTySize = TD->getTypePaddedSize(AllocElTy); |
| uint64_t CastElTySize = TD->getTypePaddedSize(CastElTy); |
| if (CastElTySize == 0 || AllocElTySize == 0) return 0; |
| |
| // See if we can satisfy the modulus by pulling a scale out of the array |
| // size argument. |
| unsigned ArraySizeScale; |
| int ArrayOffset; |
| Value *NumElements = // See if the array size is a decomposable linear expr. |
| DecomposeSimpleLinearExpr(AI.getOperand(0), ArraySizeScale, ArrayOffset); |
| |
| // If we can now satisfy the modulus, by using a non-1 scale, we really can |
| // do the xform. |
| if ((AllocElTySize*ArraySizeScale) % CastElTySize != 0 || |
| (AllocElTySize*ArrayOffset ) % CastElTySize != 0) return 0; |
| |
| unsigned Scale = (AllocElTySize*ArraySizeScale)/CastElTySize; |
| Value *Amt = 0; |
| if (Scale == 1) { |
| Amt = NumElements; |
| } else { |
| // If the allocation size is constant, form a constant mul expression |
| Amt = ConstantInt::get(Type::Int32Ty, Scale); |
| if (isa<ConstantInt>(NumElements)) |
| Amt = Multiply(cast<ConstantInt>(NumElements), cast<ConstantInt>(Amt)); |
| // otherwise multiply the amount and the number of elements |
| else if (Scale != 1) { |
| Instruction *Tmp = BinaryOperator::CreateMul(Amt, NumElements, "tmp"); |
| Amt = InsertNewInstBefore(Tmp, AI); |
| } |
| } |
| |
| if (int Offset = (AllocElTySize*ArrayOffset)/CastElTySize) { |
| Value *Off = ConstantInt::get(Type::Int32Ty, Offset, true); |
| Instruction *Tmp = BinaryOperator::CreateAdd(Amt, Off, "tmp"); |
| Amt = InsertNewInstBefore(Tmp, AI); |
| } |
| |
| AllocationInst *New; |
| if (isa<MallocInst>(AI)) |
| New = new MallocInst(CastElTy, Amt, AI.getAlignment()); |
| else |
| New = new AllocaInst(CastElTy, Amt, AI.getAlignment()); |
| InsertNewInstBefore(New, AI); |
| New->takeName(&AI); |
| |
| // If the allocation has multiple uses, insert a cast and change all things |
| // that used it to use the new cast. This will also hack on CI, but it will |
| // die soon. |
| if (!AI.hasOneUse()) { |
| AddUsesToWorkList(AI); |
| // New is the allocation instruction, pointer typed. AI is the original |
| // allocation instruction, also pointer typed. Thus, cast to use is BitCast. |
| CastInst *NewCast = new BitCastInst(New, AI.getType(), "tmpcast"); |
| InsertNewInstBefore(NewCast, AI); |
| AI.replaceAllUsesWith(NewCast); |
| } |
| return ReplaceInstUsesWith(CI, New); |
| } |
| |
| /// CanEvaluateInDifferentType - Return true if we can take the specified value |
| /// and return it as type Ty without inserting any new casts and without |
| /// changing the computed value. This is used by code that tries to decide |
| /// whether promoting or shrinking integer operations to wider or smaller types |
| /// will allow us to eliminate a truncate or extend. |
| /// |
| /// This is a truncation operation if Ty is smaller than V->getType(), or an |
| /// extension operation if Ty is larger. |
| /// |
| /// If CastOpc is a truncation, then Ty will be a type smaller than V. We |
| /// should return true if trunc(V) can be computed by computing V in the smaller |
| /// type. If V is an instruction, then trunc(inst(x,y)) can be computed as |
| /// inst(trunc(x),trunc(y)), which only makes sense if x and y can be |
| /// efficiently truncated. |
| /// |
| /// If CastOpc is a sext or zext, we are asking if the low bits of the value can |
| /// bit computed in a larger type, which is then and'd or sext_in_reg'd to get |
| /// the final result. |
| bool InstCombiner::CanEvaluateInDifferentType(Value *V, const IntegerType *Ty, |
| unsigned CastOpc, |
| int &NumCastsRemoved) { |
| // We can always evaluate constants in another type. |
| if (isa<ConstantInt>(V)) |
| return true; |
| |
| Instruction *I = dyn_cast<Instruction>(V); |
| if (!I) return false; |
| |
| const IntegerType *OrigTy = cast<IntegerType>(V->getType()); |
| |
| // If this is an extension or truncate, we can often eliminate it. |
| if (isa<TruncInst>(I) || isa<ZExtInst>(I) || isa<SExtInst>(I)) { |
| // If this is a cast from the destination type, we can trivially eliminate |
| // it, and this will remove a cast overall. |
| if (I->getOperand(0)->getType() == Ty) { |
| // If the first operand is itself a cast, and is eliminable, do not count |
| // this as an eliminable cast. We would prefer to eliminate those two |
| // casts first. |
| if (!isa<CastInst>(I->getOperand(0)) && I->hasOneUse()) |
| ++NumCastsRemoved; |
| return true; |
| } |
| } |
| |
| // We can't extend or shrink something that has multiple uses: doing so would |
| // require duplicating the instruction in general, which isn't profitable. |
| if (!I->hasOneUse()) return false; |
| |
| switch (I->getOpcode()) { |
| case Instruction::Add: |
| case Instruction::Sub: |
| case Instruction::Mul: |
| case Instruction::And: |
| case Instruction::Or: |
| case Instruction::Xor: |
| // These operators can all arbitrarily be extended or truncated. |
| return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc, |
| NumCastsRemoved) && |
| CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc, |
| NumCastsRemoved); |
| |
| case Instruction::Shl: |
| // If we are truncating the result of this SHL, and if it's a shift of a |
| // constant amount, we can always perform a SHL in a smaller type. |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| uint32_t BitWidth = Ty->getBitWidth(); |
| if (BitWidth < OrigTy->getBitWidth() && |
| CI->getLimitedValue(BitWidth) < BitWidth) |
| return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc, |
| NumCastsRemoved); |
| } |
| break; |
| case Instruction::LShr: |
| // If this is a truncate of a logical shr, we can truncate it to a smaller |
| // lshr iff we know that the bits we would otherwise be shifting in are |
| // already zeros. |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| uint32_t OrigBitWidth = OrigTy->getBitWidth(); |
| uint32_t BitWidth = Ty->getBitWidth(); |
| if (BitWidth < OrigBitWidth && |
| MaskedValueIsZero(I->getOperand(0), |
| APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) && |
| CI->getLimitedValue(BitWidth) < BitWidth) { |
| return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc, |
| NumCastsRemoved); |
| } |
| } |
| break; |
| case Instruction::ZExt: |
| case Instruction::SExt: |
| case Instruction::Trunc: |
| // If this is the same kind of case as our original (e.g. zext+zext), we |
| // can safely replace it. Note that replacing it does not reduce the number |
| // of casts in the input. |
| if (I->getOpcode() == CastOpc) |
| return true; |
| break; |
| case Instruction::Select: { |
| SelectInst *SI = cast<SelectInst>(I); |
| return CanEvaluateInDifferentType(SI->getTrueValue(), Ty, CastOpc, |
| NumCastsRemoved) && |
| CanEvaluateInDifferentType(SI->getFalseValue(), Ty, CastOpc, |
| NumCastsRemoved); |
| } |
| case Instruction::PHI: { |
| // We can change a phi if we can change all operands. |
| PHINode *PN = cast<PHINode>(I); |
| for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) |
| if (!CanEvaluateInDifferentType(PN->getIncomingValue(i), Ty, CastOpc, |
| NumCastsRemoved)) |
| return false; |
| return true; |
| } |
| default: |
| // TODO: Can handle more cases here. |
| break; |
| } |
| |
| return false; |
| } |
| |
| /// EvaluateInDifferentType - Given an expression that |
| /// CanEvaluateInDifferentType returns true for, actually insert the code to |
| /// evaluate the expression. |
| Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty, |
| bool isSigned) { |
| if (Constant *C = dyn_cast<Constant>(V)) |
| return ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/); |
| |
| // Otherwise, it must be an instruction. |
| Instruction *I = cast<Instruction>(V); |
| Instruction *Res = 0; |
| switch (I->getOpcode()) { |
| case Instruction::Add: |
| case Instruction::Sub: |
| case Instruction::Mul: |
| case Instruction::And: |
| case Instruction::Or: |
| case Instruction::Xor: |
| case Instruction::AShr: |
| case Instruction::LShr: |
| case Instruction::Shl: { |
| Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty, isSigned); |
| Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned); |
| Res = BinaryOperator::Create((Instruction::BinaryOps)I->getOpcode(), |
| LHS, RHS); |
| break; |
| } |
| case Instruction::Trunc: |
| case Instruction::ZExt: |
| case Instruction::SExt: |
| // If the source type of the cast is the type we're trying for then we can |
| // just return the source. There's no need to insert it because it is not |
| // new. |
| if (I->getOperand(0)->getType() == Ty) |
| return I->getOperand(0); |
| |
| // Otherwise, must be the same type of cast, so just reinsert a new one. |
| Res = CastInst::Create(cast<CastInst>(I)->getOpcode(), I->getOperand(0), |
| Ty); |
| break; |
| case Instruction::Select: { |
| Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned); |
| Value *False = EvaluateInDifferentType(I->getOperand(2), Ty, isSigned); |
| Res = SelectInst::Create(I->getOperand(0), True, False); |
| break; |
| } |
| case Instruction::PHI: { |
| PHINode *OPN = cast<PHINode>(I); |
| PHINode *NPN = PHINode::Create(Ty); |
| for (unsigned i = 0, e = OPN->getNumIncomingValues(); i != e; ++i) { |
| Value *V =EvaluateInDifferentType(OPN->getIncomingValue(i), Ty, isSigned); |
| NPN->addIncoming(V, OPN->getIncomingBlock(i)); |
| } |
| Res = NPN; |
| break; |
| } |
| default: |
| // TODO: Can handle more cases here. |
| assert(0 && "Unreachable!"); |
| break; |
| } |
| |
| Res->takeName(I); |
| return InsertNewInstBefore(Res, *I); |
| } |
| |
| /// @brief Implement the transforms common to all CastInst visitors. |
| Instruction *InstCombiner::commonCastTransforms(CastInst &CI) { |
| Value *Src = CI.getOperand(0); |
| |
| // Many cases of "cast of a cast" are eliminable. If it's eliminable we just |
| // eliminate it now. |
| if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast |
| if (Instruction::CastOps opc = |
| isEliminableCastPair(CSrc, CI.getOpcode(), CI.getType(), TD)) { |
| // The first cast (CSrc) is eliminable so we need to fix up or replace |
| // the second cast (CI). CSrc will then have a good chance of being dead. |
| return CastInst::Create(opc, CSrc->getOperand(0), CI.getType()); |
| } |
| } |
| |
| // If we are casting a select then fold the cast into the select |
| if (SelectInst *SI = dyn_cast<SelectInst>(Src)) |
| if (Instruction *NV = FoldOpIntoSelect(CI, SI, this)) |
| return NV; |
| |
| // If we are casting a PHI then fold the cast into the PHI |
| if (isa<PHINode>(Src)) |
| if (Instruction *NV = FoldOpIntoPhi(CI)) |
| return NV; |
| |
| return 0; |
| } |
| |
| /// FindElementAtOffset - Given a type and a constant offset, determine whether |
| /// or not there is a sequence of GEP indices into the type that will land us at |
| /// the specified offset. If so, fill them into NewIndices and return true, |
| /// otherwise return false. |
| static bool FindElementAtOffset(const Type *Ty, int64_t Offset, |
| SmallVectorImpl<Value*> &NewIndices, |
| const TargetData *TD) { |
| if (!Ty->isSized()) return false; |
| |
| // Start with the index over the outer type. Note that the type size |
| // might be zero (even if the offset isn't zero) if the indexed type |
| // is something like [0 x {int, int}] |
| const Type *IntPtrTy = TD->getIntPtrType(); |
| int64_t FirstIdx = 0; |
| if (int64_t TySize = TD->getTypePaddedSize(Ty)) { |
| FirstIdx = Offset/TySize; |
| Offset -= FirstIdx*TySize; |
| |
| // Handle hosts where % returns negative instead of values [0..TySize). |
| if (Offset < 0) { |
| --FirstIdx; |
| Offset += TySize; |
| assert(Offset >= 0); |
| } |
| assert((uint64_t)Offset < (uint64_t)TySize && "Out of range offset"); |
| } |
| |
| NewIndices.push_back(ConstantInt::get(IntPtrTy, FirstIdx)); |
| |
| // Index into the types. If we fail, set OrigBase to null. |
| while (Offset) { |
| // Indexing into tail padding between struct/array elements. |
| if (uint64_t(Offset*8) >= TD->getTypeSizeInBits(Ty)) |
| return false; |
| |
| if (const StructType *STy = dyn_cast<StructType>(Ty)) { |
| const StructLayout *SL = TD->getStructLayout(STy); |
| assert(Offset < (int64_t)SL->getSizeInBytes() && |
| "Offset must stay within the indexed type"); |
| |
| unsigned Elt = SL->getElementContainingOffset(Offset); |
| NewIndices.push_back(ConstantInt::get(Type::Int32Ty, Elt)); |
| |
| Offset -= SL->getElementOffset(Elt); |
| Ty = STy->getElementType(Elt); |
| } else if (const ArrayType *AT = dyn_cast<ArrayType>(Ty)) { |
| uint64_t EltSize = TD->getTypePaddedSize(AT->getElementType()); |
| assert(EltSize && "Cannot index into a zero-sized array"); |
| NewIndices.push_back(ConstantInt::get(IntPtrTy,Offset/EltSize)); |
| Offset %= EltSize; |
| Ty = AT->getElementType(); |
| } else { |
| // Otherwise, we can't index into the middle of this atomic type, bail. |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| |
| /// @brief Implement the transforms for cast of pointer (bitcast/ptrtoint) |
| Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) { |
| Value *Src = CI.getOperand(0); |
| |
| if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) { |
| // If casting the result of a getelementptr instruction with no offset, turn |
| // this into a cast of the original pointer! |
| if (GEP->hasAllZeroIndices()) { |
| // Changing the cast operand is usually not a good idea but it is safe |
| // here because the pointer operand is being replaced with another |
| // pointer operand so the opcode doesn't need to change. |
| AddToWorkList(GEP); |
| CI.setOperand(0, GEP->getOperand(0)); |
| return &CI; |
| } |
| |
| // If the GEP has a single use, and the base pointer is a bitcast, and the |
| // GEP computes a constant offset, see if we can convert these three |
| // instructions into fewer. This typically happens with unions and other |
| // non-type-safe code. |
| if (GEP->hasOneUse() && isa<BitCastInst>(GEP->getOperand(0))) { |
| if (GEP->hasAllConstantIndices()) { |
| // We are guaranteed to get a constant from EmitGEPOffset. |
| ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(GEP, CI, *this)); |
| int64_t Offset = OffsetV->getSExtValue(); |
| |
| // Get the base pointer input of the bitcast, and the type it points to. |
| Value *OrigBase = cast<BitCastInst>(GEP->getOperand(0))->getOperand(0); |
| const Type *GEPIdxTy = |
| cast<PointerType>(OrigBase->getType())->getElementType(); |
| SmallVector<Value*, 8> NewIndices; |
| if (FindElementAtOffset(GEPIdxTy, Offset, NewIndices, TD)) { |
| // If we were able to index down into an element, create the GEP |
| // and bitcast the result. This eliminates one bitcast, potentially |
| // two. |
| Instruction *NGEP = GetElementPtrInst::Create(OrigBase, |
| NewIndices.begin(), |
| NewIndices.end(), ""); |
| InsertNewInstBefore(NGEP, CI); |
| NGEP->takeName(GEP); |
| |
| if (isa<BitCastInst>(CI)) |
| return new BitCastInst(NGEP, CI.getType()); |
| assert(isa<PtrToIntInst>(CI)); |
| return new PtrToIntInst(NGEP, CI.getType()); |
| } |
| } |
| } |
| } |
| |
| return commonCastTransforms(CI); |
| } |
| |
| |
| |
| /// Only the TRUNC, ZEXT, SEXT, and BITCAST can both operand and result as |
| /// integer types. This function implements the common transforms for all those |
| /// cases. |
| /// @brief Implement the transforms common to CastInst with integer operands |
| Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) { |
| if (Instruction *Result = commonCastTransforms(CI)) |
| return Result; |
| |
| Value *Src = CI.getOperand(0); |
| const Type *SrcTy = Src->getType(); |
| const Type *DestTy = CI.getType(); |
| uint32_t SrcBitSize = SrcTy->getPrimitiveSizeInBits(); |
| uint32_t DestBitSize = DestTy->getPrimitiveSizeInBits(); |
| |
| // See if we can simplify any instructions used by the LHS whose sole |
| // purpose is to compute bits we don't care about. |
| APInt KnownZero(DestBitSize, 0), KnownOne(DestBitSize, 0); |
| if (SimplifyDemandedBits(&CI, APInt::getAllOnesValue(DestBitSize), |
| KnownZero, KnownOne)) |
| return &CI; |
| |
| // If the source isn't an instruction or has more than one use then we |
| // can't do anything more. |
| Instruction *SrcI = dyn_cast<Instruction>(Src); |
| if (!SrcI || !Src->hasOneUse()) |
| return 0; |
| |
| // Attempt to propagate the cast into the instruction for int->int casts. |
| int NumCastsRemoved = 0; |
| if (!isa<BitCastInst>(CI) && |
| CanEvaluateInDifferentType(SrcI, cast<IntegerType>(DestTy), |
| CI.getOpcode(), NumCastsRemoved)) { |
| // If this cast is a truncate, evaluting in a different type always |
| // eliminates the cast, so it is always a win. If this is a zero-extension, |
| // we need to do an AND to maintain the clear top-part of the computation, |
| // so we require that the input have eliminated at least one cast. If this |
| // is a sign extension, we insert two new casts (to do the extension) so we |
| // require that two casts have been eliminated. |
| bool DoXForm; |
| switch (CI.getOpcode()) { |
| default: |
| // All the others use floating point so we shouldn't actually |
| // get here because of the check above. |
| assert(0 && "Unknown cast type"); |
| case Instruction::Trunc: |
| DoXForm = true; |
| break; |
| case Instruction::ZExt: |
| DoXForm = NumCastsRemoved >= 1; |
| break; |
| case Instruction::SExt: |
| DoXForm = NumCastsRemoved >= 2; |
| break; |
| } |
| |
| if (DoXForm) { |
| Value *Res = EvaluateInDifferentType(SrcI, DestTy, |
| CI.getOpcode() == Instruction::SExt); |
| assert(Res->getType() == DestTy); |
| switch (CI.getOpcode()) { |
| default: assert(0 && "Unknown cast type!"); |
| case Instruction::Trunc: |
| case Instruction::BitCast: |
| // Just replace this cast with the result. |
| return ReplaceInstUsesWith(CI, Res); |
| case Instruction::ZExt: { |
| // We need to emit an AND to clear the high bits. |
| assert(SrcBitSize < DestBitSize && "Not a zext?"); |
| Constant *C = ConstantInt::get(APInt::getLowBitsSet(DestBitSize, |
| SrcBitSize)); |
| return BinaryOperator::CreateAnd(Res, C); |
| } |
| case Instruction::SExt: |
| // We need to emit a cast to truncate, then a cast to sext. |
| return CastInst::Create(Instruction::SExt, |
| InsertCastBefore(Instruction::Trunc, Res, Src->getType(), |
| CI), DestTy); |
| } |
| } |
| } |
| |
| Value *Op0 = SrcI->getNumOperands() > 0 ? SrcI->getOperand(0) : 0; |
| Value *Op1 = SrcI->getNumOperands() > 1 ? SrcI->getOperand(1) : 0; |
| |
| switch (SrcI->getOpcode()) { |
| case Instruction::Add: |
| case Instruction::Mul: |
| case Instruction::And: |
| case Instruction::Or: |
| case Instruction::Xor: |
| // If we are discarding information, rewrite. |
| if (DestBitSize <= SrcBitSize && DestBitSize != 1) { |
| // Don't insert two casts if they cannot be eliminated. We allow |
| // two casts to be inserted if the sizes are the same. This could |
| // only be converting signedness, which is a noop. |
| if (DestBitSize == SrcBitSize || |
| !ValueRequiresCast(CI.getOpcode(), Op1, DestTy,TD) || |
| !ValueRequiresCast(CI.getOpcode(), Op0, DestTy, TD)) { |
| Instruction::CastOps opcode = CI.getOpcode(); |
| Value *Op0c = InsertCastBefore(opcode, Op0, DestTy, *SrcI); |
| Value *Op1c = InsertCastBefore(opcode, Op1, DestTy, *SrcI); |
| return BinaryOperator::Create( |
| cast<BinaryOperator>(SrcI)->getOpcode(), Op0c, Op1c); |
| } |
| } |
| |
| // cast (xor bool X, true) to int --> xor (cast bool X to int), 1 |
| if (isa<ZExtInst>(CI) && SrcBitSize == 1 && |
| SrcI->getOpcode() == Instruction::Xor && |
| Op1 == ConstantInt::getTrue() && |
| (!Op0->hasOneUse() || !isa<CmpInst>(Op0))) { |
| Value *New = InsertCastBefore(Instruction::ZExt, Op0, DestTy, CI); |
| return BinaryOperator::CreateXor(New, ConstantInt::get(CI.getType(), 1)); |
| } |
| break; |
| case Instruction::SDiv: |
| case Instruction::UDiv: |
| case Instruction::SRem: |
| case Instruction::URem: |
| // If we are just changing the sign, rewrite. |
| if (DestBitSize == SrcBitSize) { |
| // Don't insert two casts if they cannot be eliminated. We allow |
| // two casts to be inserted if the sizes are the same. This could |
| // only be converting signedness, which is a noop. |
| if (!ValueRequiresCast(CI.getOpcode(), Op1, DestTy, TD) || |
| !ValueRequiresCast(CI.getOpcode(), Op0, DestTy, TD)) { |
| Value *Op0c = InsertCastBefore(Instruction::BitCast, |
| Op0, DestTy, *SrcI); |
| Value *Op1c = InsertCastBefore(Instruction::BitCast, |
| Op1, DestTy, *SrcI); |
| return BinaryOperator::Create( |
| cast<BinaryOperator>(SrcI)->getOpcode(), Op0c, Op1c); |
| } |
| } |
| break; |
| |
| case Instruction::Shl: |
| // Allow changing the sign of the source operand. Do not allow |
| // changing the size of the shift, UNLESS the shift amount is a |
| // constant. We must not change variable sized shifts to a smaller |
| // size, because it is undefined to shift more bits out than exist |
| // in the value. |
| if (DestBitSize == SrcBitSize || |
| (DestBitSize < SrcBitSize && isa<Constant>(Op1))) { |
| Instruction::CastOps opcode = (DestBitSize == SrcBitSize ? |
| Instruction::BitCast : Instruction::Trunc); |
| Value *Op0c = InsertCastBefore(opcode, Op0, DestTy, *SrcI); |
| Value *Op1c = InsertCastBefore(opcode, Op1, DestTy, *SrcI); |
| return BinaryOperator::CreateShl(Op0c, Op1c); |
| } |
| break; |
| case Instruction::AShr: |
| // If this is a signed shr, and if all bits shifted in are about to be |
| // truncated off, turn it into an unsigned shr to allow greater |
| // simplifications. |
| if (DestBitSize < SrcBitSize && |
| isa<ConstantInt>(Op1)) { |
| uint32_t ShiftAmt = cast<ConstantInt>(Op1)->getLimitedValue(SrcBitSize); |
| if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) { |
| // Insert the new logical shift right. |
| return BinaryOperator::CreateLShr(Op0, Op1); |
| } |
| } |
| break; |
| } |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitTrunc(TruncInst &CI) { |
| if (Instruction *Result = commonIntCastTransforms(CI)) |
| return Result; |
| |
| Value *Src = CI.getOperand(0); |
| const Type *Ty = CI.getType(); |
| uint32_t DestBitWidth = Ty->getPrimitiveSizeInBits(); |
| uint32_t SrcBitWidth = cast<IntegerType>(Src->getType())->getBitWidth(); |
| |
| if (Instruction *SrcI = dyn_cast<Instruction>(Src)) { |
| switch (SrcI->getOpcode()) { |
| default: break; |
| case Instruction::LShr: |
| // We can shrink lshr to something smaller if we know the bits shifted in |
| // are already zeros. |
| if (ConstantInt *ShAmtV = dyn_cast<ConstantInt>(SrcI->getOperand(1))) { |
| uint32_t ShAmt = ShAmtV->getLimitedValue(SrcBitWidth); |
| |
| // Get a mask for the bits shifting in. |
| APInt Mask(APInt::getLowBitsSet(SrcBitWidth, ShAmt).shl(DestBitWidth)); |
| Value* SrcIOp0 = SrcI->getOperand(0); |
| if (SrcI->hasOneUse() && MaskedValueIsZero(SrcIOp0, Mask)) { |
| if (ShAmt >= DestBitWidth) // All zeros. |
| return ReplaceInstUsesWith(CI, Constant::getNullValue(Ty)); |
| |
| // Okay, we can shrink this. Truncate the input, then return a new |
| // shift. |
| Value *V1 = InsertCastBefore(Instruction::Trunc, SrcIOp0, Ty, CI); |
| Value *V2 = InsertCastBefore(Instruction::Trunc, SrcI->getOperand(1), |
| Ty, CI); |
| return BinaryOperator::CreateLShr(V1, V2); |
| } |
| } else { // This is a variable shr. |
| |
| // Turn 'trunc (lshr X, Y) to bool' into '(X & (1 << Y)) != 0'. This is |
| // more LLVM instructions, but allows '1 << Y' to be hoisted if |
| // loop-invariant and CSE'd. |
| if (CI.getType() == Type::Int1Ty && SrcI->hasOneUse()) { |
| Value *One = ConstantInt::get(SrcI->getType(), 1); |
| |
| Value *V = InsertNewInstBefore( |
| BinaryOperator::CreateShl(One, SrcI->getOperand(1), |
| "tmp"), CI); |
| V = InsertNewInstBefore(BinaryOperator::CreateAnd(V, |
| SrcI->getOperand(0), |
| "tmp"), CI); |
| Value *Zero = Constant::getNullValue(V->getType()); |
| return new ICmpInst(ICmpInst::ICMP_NE, V, Zero); |
| } |
| } |
| break; |
| } |
| } |
| |
| return 0; |
| } |
| |
| /// transformZExtICmp - Transform (zext icmp) to bitwise / integer operations |
| /// in order to eliminate the icmp. |
| Instruction *InstCombiner::transformZExtICmp(ICmpInst *ICI, Instruction &CI, |
| bool DoXform) { |
| // If we are just checking for a icmp eq of a single bit and zext'ing it |
| // to an integer, then shift the bit to the appropriate place and then |
| // cast to integer to avoid the comparison. |
| if (ConstantInt *Op1C = dyn_cast<ConstantInt>(ICI->getOperand(1))) { |
| const APInt &Op1CV = Op1C->getValue(); |
| |
| // zext (x <s 0) to i32 --> x>>u31 true if signbit set. |
| // zext (x >s -1) to i32 --> (x>>u31)^1 true if signbit clear. |
| if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV == 0) || |
| (ICI->getPredicate() == ICmpInst::ICMP_SGT &&Op1CV.isAllOnesValue())) { |
| if (!DoXform) return ICI; |
| |
| Value *In = ICI->getOperand(0); |
| Value *Sh = ConstantInt::get(In->getType(), |
| In->getType()->getPrimitiveSizeInBits()-1); |
| In = InsertNewInstBefore(BinaryOperator::CreateLShr(In, Sh, |
| In->getName()+".lobit"), |
| CI); |
| if (In->getType() != CI.getType()) |
| In = CastInst::CreateIntegerCast(In, CI.getType(), |
| false/*ZExt*/, "tmp", &CI); |
| |
| if (ICI->getPredicate() == ICmpInst::ICMP_SGT) { |
| Constant *One = ConstantInt::get(In->getType(), 1); |
| In = InsertNewInstBefore(BinaryOperator::CreateXor(In, One, |
| In->getName()+".not"), |
| CI); |
| } |
| |
| return ReplaceInstUsesWith(CI, In); |
| } |
| |
| |
| |
| // zext (X == 0) to i32 --> X^1 iff X has only the low bit set. |
| // zext (X == 0) to i32 --> (X>>1)^1 iff X has only the 2nd bit set. |
| // zext (X == 1) to i32 --> X iff X has only the low bit set. |
| // zext (X == 2) to i32 --> X>>1 iff X has only the 2nd bit set. |
| // zext (X != 0) to i32 --> X iff X has only the low bit set. |
| // zext (X != 0) to i32 --> X>>1 iff X has only the 2nd bit set. |
| // zext (X != 1) to i32 --> X^1 iff X has only the low bit set. |
| // zext (X != 2) to i32 --> (X>>1)^1 iff X has only the 2nd bit set. |
| if ((Op1CV == 0 || Op1CV.isPowerOf2()) && |
| // This only works for EQ and NE |
| ICI->isEquality()) { |
| // If Op1C some other power of two, convert: |
| uint32_t BitWidth = Op1C->getType()->getBitWidth(); |
| APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0); |
| APInt TypeMask(APInt::getAllOnesValue(BitWidth)); |
| ComputeMaskedBits(ICI->getOperand(0), TypeMask, KnownZero, KnownOne); |
| |
| APInt KnownZeroMask(~KnownZero); |
| if (KnownZeroMask.isPowerOf2()) { // Exactly 1 possible 1? |
| if (!DoXform) return ICI; |
| |
| bool isNE = ICI->getPredicate() == ICmpInst::ICMP_NE; |
| if (Op1CV != 0 && (Op1CV != KnownZeroMask)) { |
| // (X&4) == 2 --> false |
| // (X&4) != 2 --> true |
| Constant *Res = ConstantInt::get(Type::Int1Ty, isNE); |
| Res = ConstantExpr::getZExt(Res, CI.getType()); |
| return ReplaceInstUsesWith(CI, Res); |
| } |
| |
| uint32_t ShiftAmt = KnownZeroMask.logBase2(); |
| Value *In = ICI->getOperand(0); |
| if (ShiftAmt) { |
| // Perform a logical shr by shiftamt. |
| // Insert the shift to put the result in the low bit. |
| In = InsertNewInstBefore(BinaryOperator::CreateLShr(In, |
| ConstantInt::get(In->getType(), ShiftAmt), |
| In->getName()+".lobit"), CI); |
| } |
| |
| if ((Op1CV != 0) == isNE) { // Toggle the low bit. |
| Constant *One = ConstantInt::get(In->getType(), 1); |
| In = BinaryOperator::CreateXor(In, One, "tmp"); |
| InsertNewInstBefore(cast<Instruction>(In), CI); |
| } |
| |
| if (CI.getType() == In->getType()) |
| return ReplaceInstUsesWith(CI, In); |
| else |
| return CastInst::CreateIntegerCast(In, CI.getType(), false/*ZExt*/); |
| } |
| } |
| } |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitZExt(ZExtInst &CI) { |
| // If one of the common conversion will work .. |
| if (Instruction *Result = commonIntCastTransforms(CI)) |
| return Result; |
| |
| Value *Src = CI.getOperand(0); |
| |
| // If this is a cast of a cast |
| if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast |
| // If this is a TRUNC followed by a ZEXT then we are dealing with integral |
| // types and if the sizes are just right we can convert this into a logical |
| // 'and' which will be much cheaper than the pair of casts. |
| if (isa<TruncInst>(CSrc)) { |
| // Get the sizes of the types involved |
| Value *A = CSrc->getOperand(0); |
| uint32_t SrcSize = A->getType()->getPrimitiveSizeInBits(); |
| uint32_t MidSize = CSrc->getType()->getPrimitiveSizeInBits(); |
| uint32_t DstSize = CI.getType()->getPrimitiveSizeInBits(); |
| // If we're actually extending zero bits and the trunc is a no-op |
| if (MidSize < DstSize && SrcSize == DstSize) { |
| // Replace both of the casts with an And of the type mask. |
| APInt AndValue(APInt::getLowBitsSet(SrcSize, MidSize)); |
| Constant *AndConst = ConstantInt::get(AndValue); |
| Instruction *And = |
| BinaryOperator::CreateAnd(CSrc->getOperand(0), AndConst); |
| // Unfortunately, if the type changed, we need to cast it back. |
| if (And->getType() != CI.getType()) { |
| And->setName(CSrc->getName()+".mask"); |
| InsertNewInstBefore(And, CI); |
| And = CastInst::CreateIntegerCast(And, CI.getType(), false/*ZExt*/); |
| } |
| return And; |
| } |
| } |
| } |
| |
| if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src)) |
| return transformZExtICmp(ICI, CI); |
| |
| BinaryOperator *SrcI = dyn_cast<BinaryOperator>(Src); |
| if (SrcI && SrcI->getOpcode() == Instruction::Or) { |
| // zext (or icmp, icmp) --> or (zext icmp), (zext icmp) if at least one |
| // of the (zext icmp) will be transformed. |
| ICmpInst *LHS = dyn_cast<ICmpInst>(SrcI->getOperand(0)); |
| ICmpInst *RHS = dyn_cast<ICmpInst>(SrcI->getOperand(1)); |
| if (LHS && RHS && LHS->hasOneUse() && RHS->hasOneUse() && |
| (transformZExtICmp(LHS, CI, false) || |
| transformZExtICmp(RHS, CI, false))) { |
| Value *LCast = InsertCastBefore(Instruction::ZExt, LHS, CI.getType(), CI); |
| Value *RCast = InsertCastBefore(Instruction::ZExt, RHS, CI.getType(), CI); |
| return BinaryOperator::Create(Instruction::Or, LCast, RCast); |
| } |
| } |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitSExt(SExtInst &CI) { |
| if (Instruction *I = commonIntCastTransforms(CI)) |
| return I; |
| |
| Value *Src = CI.getOperand(0); |
| |
| // Canonicalize sign-extend from i1 to a select. |
| if (Src->getType() == Type::Int1Ty) |
| return SelectInst::Create(Src, |
| ConstantInt::getAllOnesValue(CI.getType()), |
| Constant::getNullValue(CI.getType())); |
| |
| // See if the value being truncated is already sign extended. If so, just |
| // eliminate the trunc/sext pair. |
| if (getOpcode(Src) == Instruction::Trunc) { |
| Value *Op = cast<User>(Src)->getOperand(0); |
| unsigned OpBits = cast<IntegerType>(Op->getType())->getBitWidth(); |
| unsigned MidBits = cast<IntegerType>(Src->getType())->getBitWidth(); |
| unsigned DestBits = cast<IntegerType>(CI.getType())->getBitWidth(); |
| unsigned NumSignBits = ComputeNumSignBits(Op); |
| |
| if (OpBits == DestBits) { |
| // Op is i32, Mid is i8, and Dest is i32. If Op has more than 24 sign |
| // bits, it is already ready. |
| if (NumSignBits > DestBits-MidBits) |
| return ReplaceInstUsesWith(CI, Op); |
| } else if (OpBits < DestBits) { |
| // Op is i32, Mid is i8, and Dest is i64. If Op has more than 24 sign |
| // bits, just sext from i32. |
| if (NumSignBits > OpBits-MidBits) |
| return new SExtInst(Op, CI.getType(), "tmp"); |
| } else { |
| // Op is i64, Mid is i8, and Dest is i32. If Op has more than 56 sign |
| // bits, just truncate to i32. |
| if (NumSignBits > OpBits-MidBits) |
| return new TruncInst(Op, CI.getType(), "tmp"); |
| } |
| } |
| |
| // If the input is a shl/ashr pair of a same constant, then this is a sign |
| // extension from a smaller value. If we could trust arbitrary bitwidth |
| // integers, we could turn this into a truncate to the smaller bit and then |
| // use a sext for the whole extension. Since we don't, look deeper and check |
| // for a truncate. If the source and dest are the same type, eliminate the |
| // trunc and extend and just do shifts. For example, turn: |
| // %a = trunc i32 %i to i8 |
| // %b = shl i8 %a, 6 |
| // %c = ashr i8 %b, 6 |
| // %d = sext i8 %c to i32 |
| // into: |
| // %a = shl i32 %i, 30 |
| // %d = ashr i32 %a, 30 |
| Value *A = 0; |
| ConstantInt *BA = 0, *CA = 0; |
| if (match(Src, m_AShr(m_Shl(m_Value(A), m_ConstantInt(BA)), |
| m_ConstantInt(CA))) && |
| BA == CA && isa<TruncInst>(A)) { |
| Value *I = cast<TruncInst>(A)->getOperand(0); |
| if (I->getType() == CI.getType()) { |
| unsigned MidSize = Src->getType()->getPrimitiveSizeInBits(); |
| unsigned SrcDstSize = CI.getType()->getPrimitiveSizeInBits(); |
| unsigned ShAmt = CA->getZExtValue()+SrcDstSize-MidSize; |
| Constant *ShAmtV = ConstantInt::get(CI.getType(), ShAmt); |
| I = InsertNewInstBefore(BinaryOperator::CreateShl(I, ShAmtV, |
| CI.getName()), CI); |
| return BinaryOperator::CreateAShr(I, ShAmtV); |
| } |
| } |
| |
| return 0; |
| } |
| |
| /// FitsInFPType - Return a Constant* for the specified FP constant if it fits |
| /// in the specified FP type without changing its value. |
| static Constant *FitsInFPType(ConstantFP *CFP, const fltSemantics &Sem) { |
| bool losesInfo; |
| APFloat F = CFP->getValueAPF(); |
| (void)F.convert(Sem, APFloat::rmNearestTiesToEven, &losesInfo); |
| if (!losesInfo) |
| return ConstantFP::get(F); |
| return 0; |
| } |
| |
| /// LookThroughFPExtensions - If this is an fp extension instruction, look |
| /// through it until we get the source value. |
| static Value *LookThroughFPExtensions(Value *V) { |
| if (Instruction *I = dyn_cast<Instruction>(V)) |
| if (I->getOpcode() == Instruction::FPExt) |
| return LookThroughFPExtensions(I->getOperand(0)); |
| |
| // If this value is a constant, return the constant in the smallest FP type |
| // that can accurately represent it. This allows us to turn |
| // (float)((double)X+2.0) into x+2.0f. |
| if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) { |
| if (CFP->getType() == Type::PPC_FP128Ty) |
| return V; // No constant folding of this. |
| // See if the value can be truncated to float and then reextended. |
| if (Value *V = FitsInFPType(CFP, APFloat::IEEEsingle)) |
| return V; |
| if (CFP->getType() == Type::DoubleTy) |
| return V; // Won't shrink. |
| if (Value *V = FitsInFPType(CFP, APFloat::IEEEdouble)) |
| return V; |
| // Don't try to shrink to various long double types. |
| } |
| |
| return V; |
| } |
| |
| Instruction *InstCombiner::visitFPTrunc(FPTruncInst &CI) { |
| if (Instruction *I = commonCastTransforms(CI)) |
| return I; |
| |
| // If we have fptrunc(add (fpextend x), (fpextend y)), where x and y are |
| // smaller than the destination type, we can eliminate the truncate by doing |
| // the add as the smaller type. This applies to add/sub/mul/div as well as |
| // many builtins (sqrt, etc). |
| BinaryOperator *OpI = dyn_cast<BinaryOperator>(CI.getOperand(0)); |
| if (OpI && OpI->hasOneUse()) { |
| switch (OpI->getOpcode()) { |
| default: break; |
| case Instruction::Add: |
| case Instruction::Sub: |
| case Instruction::Mul: |
| case Instruction::FDiv: |
| case Instruction::FRem: |
| const Type *SrcTy = OpI->getType(); |
| Value *LHSTrunc = LookThroughFPExtensions(OpI->getOperand(0)); |
| Value *RHSTrunc = LookThroughFPExtensions(OpI->getOperand(1)); |
| if (LHSTrunc->getType() != SrcTy && |
| RHSTrunc->getType() != SrcTy) { |
| unsigned DstSize = CI.getType()->getPrimitiveSizeInBits(); |
| // If the source types were both smaller than the destination type of |
| // the cast, do this xform. |
| if (LHSTrunc->getType()->getPrimitiveSizeInBits() <= DstSize && |
| RHSTrunc->getType()->getPrimitiveSizeInBits() <= DstSize) { |
| LHSTrunc = InsertCastBefore(Instruction::FPExt, LHSTrunc, |
| CI.getType(), CI); |
| RHSTrunc = InsertCastBefore(Instruction::FPExt, RHSTrunc, |
| CI.getType(), CI); |
| return BinaryOperator::Create(OpI->getOpcode(), LHSTrunc, RHSTrunc); |
| } |
| } |
| break; |
| } |
| } |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitFPExt(CastInst &CI) { |
| return commonCastTransforms(CI); |
| } |
| |
| Instruction *InstCombiner::visitFPToUI(FPToUIInst &FI) { |
| Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0)); |
| if (OpI == 0) |
| return commonCastTransforms(FI); |
| |
| // fptoui(uitofp(X)) --> X |
| // fptoui(sitofp(X)) --> X |
| // This is safe if the intermediate type has enough bits in its mantissa to |
| // accurately represent all values of X. For example, do not do this with |
| // i64->float->i64. This is also safe for sitofp case, because any negative |
| // 'X' value would cause an undefined result for the fptoui. |
| if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) && |
| OpI->getOperand(0)->getType() == FI.getType() && |
| (int)FI.getType()->getPrimitiveSizeInBits() < /*extra bit for sign */ |
| OpI->getType()->getFPMantissaWidth()) |
| return ReplaceInstUsesWith(FI, OpI->getOperand(0)); |
| |
| return commonCastTransforms(FI); |
| } |
| |
| Instruction *InstCombiner::visitFPToSI(FPToSIInst &FI) { |
| Instruction *OpI = dyn_cast<Instruction>(FI.getOperand(0)); |
| if (OpI == 0) |
| return commonCastTransforms(FI); |
| |
| // fptosi(sitofp(X)) --> X |
| // fptosi(uitofp(X)) --> X |
| // This is safe if the intermediate type has enough bits in its mantissa to |
| // accurately represent all values of X. For example, do not do this with |
| // i64->float->i64. This is also safe for sitofp case, because any negative |
| // 'X' value would cause an undefined result for the fptoui. |
| if ((isa<UIToFPInst>(OpI) || isa<SIToFPInst>(OpI)) && |
| OpI->getOperand(0)->getType() == FI.getType() && |
| (int)FI.getType()->getPrimitiveSizeInBits() <= |
| OpI->getType()->getFPMantissaWidth()) |
| return ReplaceInstUsesWith(FI, OpI->getOperand(0)); |
| |
| return commonCastTransforms(FI); |
| } |
| |
| Instruction *InstCombiner::visitUIToFP(CastInst &CI) { |
| return commonCastTransforms(CI); |
| } |
| |
| Instruction *InstCombiner::visitSIToFP(CastInst &CI) { |
| return commonCastTransforms(CI); |
| } |
| |
| Instruction *InstCombiner::visitPtrToInt(CastInst &CI) { |
| return commonPointerCastTransforms(CI); |
| } |
| |
| Instruction *InstCombiner::visitIntToPtr(IntToPtrInst &CI) { |
| if (Instruction *I = commonCastTransforms(CI)) |
| return I; |
| |
| const Type *DestPointee = cast<PointerType>(CI.getType())->getElementType(); |
| if (!DestPointee->isSized()) return 0; |
| |
| // If this is inttoptr(add (ptrtoint x), cst), try to turn this into a GEP. |
| ConstantInt *Cst; |
| Value *X; |
| if (match(CI.getOperand(0), m_Add(m_Cast<PtrToIntInst>(m_Value(X)), |
| m_ConstantInt(Cst)))) { |
| // If the source and destination operands have the same type, see if this |
| // is a single-index GEP. |
| if (X->getType() == CI.getType()) { |
| // Get the size of the pointee type. |
| uint64_t Size = TD->getTypePaddedSize(DestPointee); |
| |
| // Convert the constant to intptr type. |
| APInt Offset = Cst->getValue(); |
| Offset.sextOrTrunc(TD->getPointerSizeInBits()); |
| |
| // If Offset is evenly divisible by Size, we can do this xform. |
| if (Size && !APIntOps::srem(Offset, APInt(Offset.getBitWidth(), Size))){ |
| Offset = APIntOps::sdiv(Offset, APInt(Offset.getBitWidth(), Size)); |
| return GetElementPtrInst::Create(X, ConstantInt::get(Offset)); |
| } |
| } |
| // TODO: Could handle other cases, e.g. where add is indexing into field of |
| // struct etc. |
| } else if (CI.getOperand(0)->hasOneUse() && |
| match(CI.getOperand(0), m_Add(m_Value(X), m_ConstantInt(Cst)))) { |
| // Otherwise, if this is inttoptr(add x, cst), try to turn this into an |
| // "inttoptr+GEP" instead of "add+intptr". |
| |
| // Get the size of the pointee type. |
| uint64_t Size = TD->getTypePaddedSize(DestPointee); |
| |
| // Convert the constant to intptr type. |
| APInt Offset = Cst->getValue(); |
| Offset.sextOrTrunc(TD->getPointerSizeInBits()); |
| |
| // If Offset is evenly divisible by Size, we can do this xform. |
| if (Size && !APIntOps::srem(Offset, APInt(Offset.getBitWidth(), Size))){ |
| Offset = APIntOps::sdiv(Offset, APInt(Offset.getBitWidth(), Size)); |
| |
| Instruction *P = InsertNewInstBefore(new IntToPtrInst(X, CI.getType(), |
| "tmp"), CI); |
| return GetElementPtrInst::Create(P, ConstantInt::get(Offset), "tmp"); |
| } |
| } |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitBitCast(BitCastInst &CI) { |
| // If the operands are integer typed then apply the integer transforms, |
| // otherwise just apply the common ones. |
| Value *Src = CI.getOperand(0); |
| const Type *SrcTy = Src->getType(); |
| const Type *DestTy = CI.getType(); |
| |
| if (SrcTy->isInteger() && DestTy->isInteger()) { |
| if (Instruction *Result = commonIntCastTransforms(CI)) |
| return Result; |
| } else if (isa<PointerType>(SrcTy)) { |
| if (Instruction *I = commonPointerCastTransforms(CI)) |
| return I; |
| } else { |
| if (Instruction *Result = commonCastTransforms(CI)) |
| return Result; |
| } |
| |
| |
| // Get rid of casts from one type to the same type. These are useless and can |
| // be replaced by the operand. |
| if (DestTy == Src->getType()) |
| return ReplaceInstUsesWith(CI, Src); |
| |
| if (const PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) { |
| const PointerType *SrcPTy = cast<PointerType>(SrcTy); |
| const Type *DstElTy = DstPTy->getElementType(); |
| const Type *SrcElTy = SrcPTy->getElementType(); |
| |
| // If the address spaces don't match, don't eliminate the bitcast, which is |
| // required for changing types. |
| if (SrcPTy->getAddressSpace() != DstPTy->getAddressSpace()) |
| return 0; |
| |
| // If we are casting a malloc or alloca to a pointer to a type of the same |
| // size, rewrite the allocation instruction to allocate the "right" type. |
| if (AllocationInst *AI = dyn_cast<AllocationInst>(Src)) |
| if (Instruction *V = PromoteCastOfAllocation(CI, *AI)) |
| return V; |
| |
| // If the source and destination are pointers, and this cast is equivalent |
| // to a getelementptr X, 0, 0, 0... turn it into the appropriate gep. |
| // This can enhance SROA and other transforms that want type-safe pointers. |
| Constant *ZeroUInt = Constant::getNullValue(Type::Int32Ty); |
| unsigned NumZeros = 0; |
| while (SrcElTy != DstElTy && |
| isa<CompositeType>(SrcElTy) && !isa<PointerType>(SrcElTy) && |
| SrcElTy->getNumContainedTypes() /* not "{}" */) { |
| SrcElTy = cast<CompositeType>(SrcElTy)->getTypeAtIndex(ZeroUInt); |
| ++NumZeros; |
| } |
| |
| // If we found a path from the src to dest, create the getelementptr now. |
| if (SrcElTy == DstElTy) { |
| SmallVector<Value*, 8> Idxs(NumZeros+1, ZeroUInt); |
| return GetElementPtrInst::Create(Src, Idxs.begin(), Idxs.end(), "", |
| ((Instruction*) NULL)); |
| } |
| } |
| |
| if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(Src)) { |
| if (SVI->hasOneUse()) { |
| // Okay, we have (bitconvert (shuffle ..)). Check to see if this is |
| // a bitconvert to a vector with the same # elts. |
| if (isa<VectorType>(DestTy) && |
| cast<VectorType>(DestTy)->getNumElements() == |
| SVI->getType()->getNumElements() && |
| SVI->getType()->getNumElements() == |
| cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements()) { |
| CastInst *Tmp; |
| // If either of the operands is a cast from CI.getType(), then |
| // evaluating the shuffle in the casted destination's type will allow |
| // us to eliminate at least one cast. |
| if (((Tmp = dyn_cast<CastInst>(SVI->getOperand(0))) && |
| Tmp->getOperand(0)->getType() == DestTy) || |
| ((Tmp = dyn_cast<CastInst>(SVI->getOperand(1))) && |
| Tmp->getOperand(0)->getType() == DestTy)) { |
| Value *LHS = InsertCastBefore(Instruction::BitCast, |
| SVI->getOperand(0), DestTy, CI); |
| Value *RHS = InsertCastBefore(Instruction::BitCast, |
| SVI->getOperand(1), DestTy, CI); |
| // Return a new shuffle vector. Use the same element ID's, as we |
| // know the vector types match #elts. |
| return new ShuffleVectorInst(LHS, RHS, SVI->getOperand(2)); |
| } |
| } |
| } |
| } |
| return 0; |
| } |
| |
| /// GetSelectFoldableOperands - We want to turn code that looks like this: |
| /// %C = or %A, %B |
| /// %D = select %cond, %C, %A |
| /// into: |
| /// %C = select %cond, %B, 0 |
| /// %D = or %A, %C |
| /// |
| /// Assuming that the specified instruction is an operand to the select, return |
| /// a bitmask indicating which operands of this instruction are foldable if they |
| /// equal the other incoming value of the select. |
| /// |
| static unsigned GetSelectFoldableOperands(Instruction *I) { |
| switch (I->getOpcode()) { |
| case Instruction::Add: |
| case Instruction::Mul: |
| case Instruction::And: |
| case Instruction::Or: |
| case Instruction::Xor: |
| return 3; // Can fold through either operand. |
| case Instruction::Sub: // Can only fold on the amount subtracted. |
| case Instruction::Shl: // Can only fold on the shift amount. |
| case Instruction::LShr: |
| case Instruction::AShr: |
| return 1; |
| default: |
| return 0; // Cannot fold |
| } |
| } |
| |
| /// GetSelectFoldableConstant - For the same transformation as the previous |
| /// function, return the identity constant that goes into the select. |
| static Constant *GetSelectFoldableConstant(Instruction *I) { |
| switch (I->getOpcode()) { |
| default: assert(0 && "This cannot happen!"); abort(); |
| case Instruction::Add: |
| case Instruction::Sub: |
| case Instruction::Or: |
| case Instruction::Xor: |
| case Instruction::Shl: |
| case Instruction::LShr: |
| case Instruction::AShr: |
| return Constant::getNullValue(I->getType()); |
| case Instruction::And: |
| return Constant::getAllOnesValue(I->getType()); |
| case Instruction::Mul: |
| return ConstantInt::get(I->getType(), 1); |
| } |
| } |
| |
| /// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI |
| /// have the same opcode and only one use each. Try to simplify this. |
| Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI, |
| Instruction *FI) { |
| if (TI->getNumOperands() == 1) { |
| // If this is a non-volatile load or a cast from the same type, |
| // merge. |
| if (TI->isCast()) { |
| if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType()) |
| return 0; |
| } else { |
| return 0; // unknown unary op. |
| } |
| |
| // Fold this by inserting a select from the input values. |
| SelectInst *NewSI = SelectInst::Create(SI.getCondition(), TI->getOperand(0), |
| FI->getOperand(0), SI.getName()+".v"); |
| InsertNewInstBefore(NewSI, SI); |
| return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI, |
| TI->getType()); |
| } |
| |
| // Only handle binary operators here. |
| if (!isa<BinaryOperator>(TI)) |
| return 0; |
| |
| // Figure out if the operations have any operands in common. |
| Value *MatchOp, *OtherOpT, *OtherOpF; |
| bool MatchIsOpZero; |
| if (TI->getOperand(0) == FI->getOperand(0)) { |
| MatchOp = TI->getOperand(0); |
| OtherOpT = TI->getOperand(1); |
| OtherOpF = FI->getOperand(1); |
| MatchIsOpZero = true; |
| } else if (TI->getOperand(1) == FI->getOperand(1)) { |
| MatchOp = TI->getOperand(1); |
| OtherOpT = TI->getOperand(0); |
| OtherOpF = FI->getOperand(0); |
| MatchIsOpZero = false; |
| } else if (!TI->isCommutative()) { |
| return 0; |
| } else if (TI->getOperand(0) == FI->getOperand(1)) { |
| MatchOp = TI->getOperand(0); |
| OtherOpT = TI->getOperand(1); |
| OtherOpF = FI->getOperand(0); |
| MatchIsOpZero = true; |
| } else if (TI->getOperand(1) == FI->getOperand(0)) { |
| MatchOp = TI->getOperand(1); |
| OtherOpT = TI->getOperand(0); |
| OtherOpF = FI->getOperand(1); |
| MatchIsOpZero = true; |
| } else { |
| return 0; |
| } |
| |
| // If we reach here, they do have operations in common. |
| SelectInst *NewSI = SelectInst::Create(SI.getCondition(), OtherOpT, |
| OtherOpF, SI.getName()+".v"); |
| InsertNewInstBefore(NewSI, SI); |
| |
| if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) { |
| if (MatchIsOpZero) |
| return BinaryOperator::Create(BO->getOpcode(), MatchOp, NewSI); |
| else |
| return BinaryOperator::Create(BO->getOpcode(), NewSI, MatchOp); |
| } |
| assert(0 && "Shouldn't get here"); |
| return 0; |
| } |
| |
| /// visitSelectInstWithICmp - Visit a SelectInst that has an |
| /// ICmpInst as its first operand. |
| /// |
| Instruction *InstCombiner::visitSelectInstWithICmp(SelectInst &SI, |
| ICmpInst *ICI) { |
| bool Changed = false; |
| ICmpInst::Predicate Pred = ICI->getPredicate(); |
| Value *CmpLHS = ICI->getOperand(0); |
| Value *CmpRHS = ICI->getOperand(1); |
| Value *TrueVal = SI.getTrueValue(); |
| Value *FalseVal = SI.getFalseValue(); |
| |
| // Check cases where the comparison is with a constant that |
| // can be adjusted to fit the min/max idiom. We may edit ICI in |
| // place here, so make sure the select is the only user. |
| if (ICI->hasOneUse()) |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(CmpRHS)) { |
| switch (Pred) { |
| default: break; |
| case ICmpInst::ICMP_ULT: |
| case ICmpInst::ICMP_SLT: { |
| // X < MIN ? T : F --> F |
| if (CI->isMinValue(Pred == ICmpInst::ICMP_SLT)) |
| return ReplaceInstUsesWith(SI, FalseVal); |
| // X < C ? X : C-1 --> X > C-1 ? C-1 : X |
| Constant *AdjustedRHS = SubOne(CI); |
| if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) || |
| (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) { |
| Pred = ICmpInst::getSwappedPredicate(Pred); |
| CmpRHS = AdjustedRHS; |
| std::swap(FalseVal, TrueVal); |
| ICI->setPredicate(Pred); |
| ICI->setOperand(1, CmpRHS); |
| SI.setOperand(1, TrueVal); |
| SI.setOperand(2, FalseVal); |
| Changed = true; |
| } |
| break; |
| } |
| case ICmpInst::ICMP_UGT: |
| case ICmpInst::ICMP_SGT: { |
| // X > MAX ? T : F --> F |
| if (CI->isMaxValue(Pred == ICmpInst::ICMP_SGT)) |
| return ReplaceInstUsesWith(SI, FalseVal); |
| // X > C ? X : C+1 --> X < C+1 ? C+1 : X |
| Constant *AdjustedRHS = AddOne(CI); |
| if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) || |
| (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) { |
| Pred = ICmpInst::getSwappedPredicate(Pred); |
| CmpRHS = AdjustedRHS; |
| std::swap(FalseVal, TrueVal); |
| ICI->setPredicate(Pred); |
| ICI->setOperand(1, CmpRHS); |
| SI.setOperand(1, TrueVal); |
| SI.setOperand(2, FalseVal); |
| Changed = true; |
| } |
| break; |
| } |
| } |
| |
| // (x <s 0) ? -1 : 0 -> ashr x, 31 -> all ones if signed |
| // (x >s -1) ? -1 : 0 -> ashr x, 31 -> all ones if not signed |
| CmpInst::Predicate Pred = CmpInst::BAD_ICMP_PREDICATE; |
| if (match(TrueVal, m_ConstantInt<-1>()) && |
| match(FalseVal, m_ConstantInt<0>())) |
| Pred = ICI->getPredicate(); |
| else if (match(TrueVal, m_ConstantInt<0>()) && |
| match(FalseVal, m_ConstantInt<-1>())) |
| Pred = CmpInst::getInversePredicate(ICI->getPredicate()); |
| |
| if (Pred != CmpInst::BAD_ICMP_PREDICATE) { |
| // If we are just checking for a icmp eq of a single bit and zext'ing it |
| // to an integer, then shift the bit to the appropriate place and then |
| // cast to integer to avoid the comparison. |
| const APInt &Op1CV = CI->getValue(); |
| |
| // sext (x <s 0) to i32 --> x>>s31 true if signbit set. |
| // sext (x >s -1) to i32 --> (x>>s31)^-1 true if signbit clear. |
| if ((Pred == ICmpInst::ICMP_SLT && Op1CV == 0) || |
| (Pred == ICmpInst::ICMP_SGT && Op1CV.isAllOnesValue())) { |
| Value *In = ICI->getOperand(0); |
| Value *Sh = ConstantInt::get(In->getType(), |
| In->getType()->getPrimitiveSizeInBits()-1); |
| In = InsertNewInstBefore(BinaryOperator::CreateAShr(In, Sh, |
| In->getName()+".lobit"), |
| *ICI); |
| if (In->getType() != SI.getType()) |
| In = CastInst::CreateIntegerCast(In, SI.getType(), |
| true/*SExt*/, "tmp", ICI); |
| |
| if (Pred == ICmpInst::ICMP_SGT) |
| In = InsertNewInstBefore(BinaryOperator::CreateNot(In, |
| In->getName()+".not"), *ICI); |
| |
| return ReplaceInstUsesWith(SI, In); |
| } |
| } |
| } |
| |
| if (CmpLHS == TrueVal && CmpRHS == FalseVal) { |
| // Transform (X == Y) ? X : Y -> Y |
| if (Pred == ICmpInst::ICMP_EQ) |
| return ReplaceInstUsesWith(SI, FalseVal); |
| // Transform (X != Y) ? X : Y -> X |
| if (Pred == ICmpInst::ICMP_NE) |
| return ReplaceInstUsesWith(SI, TrueVal); |
| /// NOTE: if we wanted to, this is where to detect integer MIN/MAX |
| |
| } else if (CmpLHS == FalseVal && CmpRHS == TrueVal) { |
| // Transform (X == Y) ? Y : X -> X |
| if (Pred == ICmpInst::ICMP_EQ) |
| return ReplaceInstUsesWith(SI, FalseVal); |
| // Transform (X != Y) ? Y : X -> Y |
| if (Pred == ICmpInst::ICMP_NE) |
| return ReplaceInstUsesWith(SI, TrueVal); |
| /// NOTE: if we wanted to, this is where to detect integer MIN/MAX |
| } |
| |
| /// NOTE: if we wanted to, this is where to detect integer ABS |
| |
| return Changed ? &SI : 0; |
| } |
| |
| Instruction *InstCombiner::visitSelectInst(SelectInst &SI) { |
| Value *CondVal = SI.getCondition(); |
| Value *TrueVal = SI.getTrueValue(); |
| Value *FalseVal = SI.getFalseValue(); |
| |
| // select true, X, Y -> X |
| // select false, X, Y -> Y |
| if (ConstantInt *C = dyn_cast<ConstantInt>(CondVal)) |
| return ReplaceInstUsesWith(SI, C->getZExtValue() ? TrueVal : FalseVal); |
| |
| // select C, X, X -> X |
| if (TrueVal == FalseVal) |
| return ReplaceInstUsesWith(SI, TrueVal); |
| |
| if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X |
| return ReplaceInstUsesWith(SI, FalseVal); |
| if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X |
| return ReplaceInstUsesWith(SI, TrueVal); |
| if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y |
| if (isa<Constant>(TrueVal)) |
| return ReplaceInstUsesWith(SI, TrueVal); |
| else |
| return ReplaceInstUsesWith(SI, FalseVal); |
| } |
| |
| if (SI.getType() == Type::Int1Ty) { |
| if (ConstantInt *C = dyn_cast<ConstantInt>(TrueVal)) { |
| if (C->getZExtValue()) { |
| // Change: A = select B, true, C --> A = or B, C |
| return BinaryOperator::CreateOr(CondVal, FalseVal); |
| } else { |
| // Change: A = select B, false, C --> A = and !B, C |
| Value *NotCond = |
| InsertNewInstBefore(BinaryOperator::CreateNot(CondVal, |
| "not."+CondVal->getName()), SI); |
| return BinaryOperator::CreateAnd(NotCond, FalseVal); |
| } |
| } else if (ConstantInt *C = dyn_cast<ConstantInt>(FalseVal)) { |
| if (C->getZExtValue() == false) { |
| // Change: A = select B, C, false --> A = and B, C |
| return BinaryOperator::CreateAnd(CondVal, TrueVal); |
| } else { |
| // Change: A = select B, C, true --> A = or !B, C |
| Value *NotCond = |
| InsertNewInstBefore(BinaryOperator::CreateNot(CondVal, |
| "not."+CondVal->getName()), SI); |
| return BinaryOperator::CreateOr(NotCond, TrueVal); |
| } |
| } |
| |
| // select a, b, a -> a&b |
| // select a, a, b -> a|b |
| if (CondVal == TrueVal) |
| return BinaryOperator::CreateOr(CondVal, FalseVal); |
| else if (CondVal == FalseVal) |
| return BinaryOperator::CreateAnd(CondVal, TrueVal); |
| } |
| |
| // Selecting between two integer constants? |
| if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal)) |
| if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) { |
| // select C, 1, 0 -> zext C to int |
| if (FalseValC->isZero() && TrueValC->getValue() == 1) { |
| return CastInst::Create(Instruction::ZExt, CondVal, SI.getType()); |
| } else if (TrueValC->isZero() && FalseValC->getValue() == 1) { |
| // select C, 0, 1 -> zext !C to int |
| Value *NotCond = |
| InsertNewInstBefore(BinaryOperator::CreateNot(CondVal, |
| "not."+CondVal->getName()), SI); |
| return CastInst::Create(Instruction::ZExt, NotCond, SI.getType()); |
| } |
| |
| if (ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition())) { |
| |
| // (x <s 0) ? -1 : 0 -> ashr x, 31 |
| if (TrueValC->isAllOnesValue() && FalseValC->isZero()) |
| if (ConstantInt *CmpCst = dyn_cast<ConstantInt>(IC->getOperand(1))) { |
| if (IC->getPredicate() == ICmpInst::ICMP_SLT && CmpCst->isZero()) { |
| // The comparison constant and the result are not neccessarily the |
| // same width. Make an all-ones value by inserting a AShr. |
| Value *X = IC->getOperand(0); |
| uint32_t Bits = X->getType()->getPrimitiveSizeInBits(); |
| Constant *ShAmt = ConstantInt::get(X->getType(), Bits-1); |
| Instruction *SRA = BinaryOperator::Create(Instruction::AShr, X, |
| ShAmt, "ones"); |
| InsertNewInstBefore(SRA, SI); |
| |
| // Then cast to the appropriate width. |
| return CastInst::CreateIntegerCast(SRA, SI.getType(), true); |
| } |
| } |
| |
| |
| // If one of the constants is zero (we know they can't both be) and we |
| // have an icmp instruction with zero, and we have an 'and' with the |
| // non-constant value, eliminate this whole mess. This corresponds to |
| // cases like this: ((X & 27) ? 27 : 0) |
| if (TrueValC->isZero() || FalseValC->isZero()) |
| if (IC->isEquality() && isa<ConstantInt>(IC->getOperand(1)) && |
| cast<Constant>(IC->getOperand(1))->isNullValue()) |
| if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0))) |
| if (ICA->getOpcode() == Instruction::And && |
| isa<ConstantInt>(ICA->getOperand(1)) && |
| (ICA->getOperand(1) == TrueValC || |
| ICA->getOperand(1) == FalseValC) && |
| isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) { |
| // Okay, now we know that everything is set up, we just don't |
| // know whether we have a icmp_ne or icmp_eq and whether the |
| // true or false val is the zero. |
| bool ShouldNotVal = !TrueValC->isZero(); |
| ShouldNotVal ^= IC->getPredicate() == ICmpInst::ICMP_NE; |
| Value *V = ICA; |
| if (ShouldNotVal) |
| V = InsertNewInstBefore(BinaryOperator::Create( |
| Instruction::Xor, V, ICA->getOperand(1)), SI); |
| return ReplaceInstUsesWith(SI, V); |
| } |
| } |
| } |
| |
| // See if we are selecting two values based on a comparison of the two values. |
| if (FCmpInst *FCI = dyn_cast<FCmpInst>(CondVal)) { |
| if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) { |
| // Transform (X == Y) ? X : Y -> Y |
| if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) { |
| // This is not safe in general for floating point: |
| // consider X== -0, Y== +0. |
| // It becomes safe if either operand is a nonzero constant. |
| ConstantFP *CFPt, *CFPf; |
| if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) && |
| !CFPt->getValueAPF().isZero()) || |
| ((CFPf = dyn_cast<ConstantFP>(FalseVal)) && |
| !CFPf->getValueAPF().isZero())) |
| return ReplaceInstUsesWith(SI, FalseVal); |
| } |
| // Transform (X != Y) ? X : Y -> X |
| if (FCI->getPredicate() == FCmpInst::FCMP_ONE) |
| return ReplaceInstUsesWith(SI, TrueVal); |
| // NOTE: if we wanted to, this is where to detect MIN/MAX |
| |
| } else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){ |
| // Transform (X == Y) ? Y : X -> X |
| if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) { |
| // This is not safe in general for floating point: |
| // consider X== -0, Y== +0. |
| // It becomes safe if either operand is a nonzero constant. |
| ConstantFP *CFPt, *CFPf; |
| if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) && |
| !CFPt->getValueAPF().isZero()) || |
| ((CFPf = dyn_cast<ConstantFP>(FalseVal)) && |
| !CFPf->getValueAPF().isZero())) |
| return ReplaceInstUsesWith(SI, FalseVal); |
| } |
| // Transform (X != Y) ? Y : X -> Y |
| if (FCI->getPredicate() == FCmpInst::FCMP_ONE) |
| return ReplaceInstUsesWith(SI, TrueVal); |
| // NOTE: if we wanted to, this is where to detect MIN/MAX |
| } |
| // NOTE: if we wanted to, this is where to detect ABS |
| } |
| |
| // See if we are selecting two values based on a comparison of the two values. |
| if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal)) |
| if (Instruction *Result = visitSelectInstWithICmp(SI, ICI)) |
| return Result; |
| |
| if (Instruction *TI = dyn_cast<Instruction>(TrueVal)) |
| if (Instruction *FI = dyn_cast<Instruction>(FalseVal)) |
| if (TI->hasOneUse() && FI->hasOneUse()) { |
| Instruction *AddOp = 0, *SubOp = 0; |
| |
| // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z)) |
| if (TI->getOpcode() == FI->getOpcode()) |
| if (Instruction *IV = FoldSelectOpOp(SI, TI, FI)) |
| return IV; |
| |
| // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is |
| // even legal for FP. |
| if (TI->getOpcode() == Instruction::Sub && |
| FI->getOpcode() == Instruction::Add) { |
| AddOp = FI; SubOp = TI; |
| } else if (FI->getOpcode() == Instruction::Sub && |
| TI->getOpcode() == Instruction::Add) { |
| AddOp = TI; SubOp = FI; |
| } |
| |
| if (AddOp) { |
| Value *OtherAddOp = 0; |
| if (SubOp->getOperand(0) == AddOp->getOperand(0)) { |
| OtherAddOp = AddOp->getOperand(1); |
| } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) { |
| OtherAddOp = AddOp->getOperand(0); |
| } |
| |
| if (OtherAddOp) { |
| // So at this point we know we have (Y -> OtherAddOp): |
| // select C, (add X, Y), (sub X, Z) |
| Value *NegVal; // Compute -Z |
| if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) { |
| NegVal = ConstantExpr::getNeg(C); |
| } else { |
| NegVal = InsertNewInstBefore( |
| BinaryOperator::CreateNeg(SubOp->getOperand(1), "tmp"), SI); |
| } |
| |
| Value *NewTrueOp = OtherAddOp; |
| Value *NewFalseOp = NegVal; |
| if (AddOp != TI) |
| std::swap(NewTrueOp, NewFalseOp); |
| Instruction *NewSel = |
| SelectInst::Create(CondVal, NewTrueOp, |
| NewFalseOp, SI.getName() + ".p"); |
| |
| NewSel = InsertNewInstBefore(NewSel, SI); |
| return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel); |
| } |
| } |
| } |
| |
| // See if we can fold the select into one of our operands. |
| if (SI.getType()->isInteger()) { |
| // See the comment above GetSelectFoldableOperands for a description of the |
| // transformation we are doing here. |
| if (Instruction *TVI = dyn_cast<Instruction>(TrueVal)) |
| if (TVI->hasOneUse() && TVI->getNumOperands() == 2 && |
| !isa<Constant>(FalseVal)) |
| if (unsigned SFO = GetSelectFoldableOperands(TVI)) { |
| unsigned OpToFold = 0; |
| if ((SFO & 1) && FalseVal == TVI->getOperand(0)) { |
| OpToFold = 1; |
| } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) { |
| OpToFold = 2; |
| } |
| |
| if (OpToFold) { |
| Constant *C = GetSelectFoldableConstant(TVI); |
| Instruction *NewSel = |
| SelectInst::Create(SI.getCondition(), |
| TVI->getOperand(2-OpToFold), C); |
| InsertNewInstBefore(NewSel, SI); |
| NewSel->takeName(TVI); |
| if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI)) |
| return BinaryOperator::Create(BO->getOpcode(), FalseVal, NewSel); |
| else { |
| assert(0 && "Unknown instruction!!"); |
| } |
| } |
| } |
| |
| if (Instruction *FVI = dyn_cast<Instruction>(FalseVal)) |
| if (FVI->hasOneUse() && FVI->getNumOperands() == 2 && |
| !isa<Constant>(TrueVal)) |
| if (unsigned SFO = GetSelectFoldableOperands(FVI)) { |
| unsigned OpToFold = 0; |
| if ((SFO & 1) && TrueVal == FVI->getOperand(0)) { |
| OpToFold = 1; |
| } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) { |
| OpToFold = 2; |
| } |
| |
| if (OpToFold) { |
| Constant *C = GetSelectFoldableConstant(FVI); |
| Instruction *NewSel = |
| SelectInst::Create(SI.getCondition(), C, |
| FVI->getOperand(2-OpToFold)); |
| InsertNewInstBefore(NewSel, SI); |
| NewSel->takeName(FVI); |
| if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI)) |
| return BinaryOperator::Create(BO->getOpcode(), TrueVal, NewSel); |
| else |
| assert(0 && "Unknown instruction!!"); |
| } |
| } |
| } |
| |
| if (BinaryOperator::isNot(CondVal)) { |
| SI.setOperand(0, BinaryOperator::getNotArgument(CondVal)); |
| SI.setOperand(1, FalseVal); |
| SI.setOperand(2, TrueVal); |
| return &SI; |
| } |
| |
| return 0; |
| } |
| |
| /// EnforceKnownAlignment - If the specified pointer points to an object that |
| /// we control, modify the object's alignment to PrefAlign. This isn't |
| /// often possible though. If alignment is important, a more reliable approach |
| /// is to simply align all global variables and allocation instructions to |
| /// their preferred alignment from the beginning. |
| /// |
| static unsigned EnforceKnownAlignment(Value *V, |
| unsigned Align, unsigned PrefAlign) { |
| |
| User *U = dyn_cast<User>(V); |
| if (!U) return Align; |
| |
| switch (getOpcode(U)) { |
| default: break; |
| case Instruction::BitCast: |
| return EnforceKnownAlignment(U->getOperand(0), Align, PrefAlign); |
| case Instruction::GetElementPtr: { |
| // If all indexes are zero, it is just the alignment of the base pointer. |
| bool AllZeroOperands = true; |
| for (User::op_iterator i = U->op_begin() + 1, e = U->op_end(); i != e; ++i) |
| if (!isa<Constant>(*i) || |
| !cast<Constant>(*i)->isNullValue()) { |
| AllZeroOperands = false; |
| break; |
| } |
| |
| if (AllZeroOperands) { |
| // Treat this like a bitcast. |
| return EnforceKnownAlignment(U->getOperand(0), Align, PrefAlign); |
| } |
| break; |
| } |
| } |
| |
| if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) { |
| // If there is a large requested alignment and we can, bump up the alignment |
| // of the global. |
| if (!GV->isDeclaration()) { |
| GV->setAlignment(PrefAlign); |
| Align = PrefAlign; |
| } |
| } else if (AllocationInst *AI = dyn_cast<AllocationInst>(V)) { |
| // If there is a requested alignment and if this is an alloca, round up. We |
| // don't do this for malloc, because some systems can't respect the request. |
| if (isa<AllocaInst>(AI)) { |
| AI->setAlignment(PrefAlign); |
| Align = PrefAlign; |
| } |
| } |
| |
| return Align; |
| } |
| |
| /// GetOrEnforceKnownAlignment - If the specified pointer has an alignment that |
| /// we can determine, return it, otherwise return 0. If PrefAlign is specified, |
| /// and it is more than the alignment of the ultimate object, see if we can |
| /// increase the alignment of the ultimate object, making this check succeed. |
| unsigned InstCombiner::GetOrEnforceKnownAlignment(Value *V, |
| unsigned PrefAlign) { |
| unsigned BitWidth = TD ? TD->getTypeSizeInBits(V->getType()) : |
| sizeof(PrefAlign) * CHAR_BIT; |
| APInt Mask = APInt::getAllOnesValue(BitWidth); |
| APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0); |
| ComputeMaskedBits(V, Mask, KnownZero, KnownOne); |
| unsigned TrailZ = KnownZero.countTrailingOnes(); |
| unsigned Align = 1u << std::min(BitWidth - 1, TrailZ); |
| |
| if (PrefAlign > Align) |
| Align = EnforceKnownAlignment(V, Align, PrefAlign); |
| |
| // We don't need to make any adjustment. |
| return Align; |
| } |
| |
| Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) { |
| unsigned DstAlign = GetOrEnforceKnownAlignment(MI->getOperand(1)); |
| unsigned SrcAlign = GetOrEnforceKnownAlignment(MI->getOperand(2)); |
| unsigned MinAlign = std::min(DstAlign, SrcAlign); |
| unsigned CopyAlign = MI->getAlignment()->getZExtValue(); |
| |
| if (CopyAlign < MinAlign) { |
| MI->setAlignment(ConstantInt::get(Type::Int32Ty, MinAlign)); |
| return MI; |
| } |
| |
| // If MemCpyInst length is 1/2/4/8 bytes then replace memcpy with |
| // load/store. |
| ConstantInt *MemOpLength = dyn_cast<ConstantInt>(MI->getOperand(3)); |
| if (MemOpLength == 0) return 0; |
| |
| // Source and destination pointer types are always "i8*" for intrinsic. See |
| // if the size is something we can handle with a single primitive load/store. |
| // A single load+store correctly handles overlapping memory in the memmove |
| // case. |
| unsigned Size = MemOpLength->getZExtValue(); |
| if (Size == 0) return MI; // Delete this mem transfer. |
| |
| if (Size > 8 || (Size&(Size-1))) |
| return 0; // If not 1/2/4/8 bytes, exit. |
| |
| // Use an integer load+store unless we can find something better. |
| Type *NewPtrTy = PointerType::getUnqual(IntegerType::get(Size<<3)); |
| |
| // Memcpy forces the use of i8* for the source and destination. That means |
| // that if you're using memcpy to move one double around, you'll get a cast |
| // from double* to i8*. We'd much rather use a double load+store rather than |
| // an i64 load+store, here because this improves the odds that the source or |
| // dest address will be promotable. See if we can find a better type than the |
| // integer datatype. |
| if (Value *Op = getBitCastOperand(MI->getOperand(1))) { |
| const Type *SrcETy = cast<PointerType>(Op->getType())->getElementType(); |
| if (SrcETy->isSized() && TD->getTypeStoreSize(SrcETy) == Size) { |
| // The SrcETy might be something like {{{double}}} or [1 x double]. Rip |
| // down through these levels if so. |
| while (!SrcETy->isSingleValueType()) { |
| if (const StructType *STy = dyn_cast<StructType>(SrcETy)) { |
| if (STy->getNumElements() == 1) |
| SrcETy = STy->getElementType(0); |
| else |
| break; |
| } else if (const ArrayType *ATy = dyn_cast<ArrayType>(SrcETy)) { |
| if (ATy->getNumElements() == 1) |
| SrcETy = ATy->getElementType(); |
| else |
| break; |
| } else |
| break; |
| } |
| |
| if (SrcETy->isSingleValueType()) |
| NewPtrTy = PointerType::getUnqual(SrcETy); |
| } |
| } |
| |
| |
| // If the memcpy/memmove provides better alignment info than we can |
| // infer, use it. |
| SrcAlign = std::max(SrcAlign, CopyAlign); |
| DstAlign = std::max(DstAlign, CopyAlign); |
| |
| Value *Src = InsertBitCastBefore(MI->getOperand(2), NewPtrTy, *MI); |
| Value *Dest = InsertBitCastBefore(MI->getOperand(1), NewPtrTy, *MI); |
| Instruction *L = new LoadInst(Src, "tmp", false, SrcAlign); |
| InsertNewInstBefore(L, *MI); |
| InsertNewInstBefore(new StoreInst(L, Dest, false, DstAlign), *MI); |
| |
| // Set the size of the copy to 0, it will be deleted on the next iteration. |
| MI->setOperand(3, Constant::getNullValue(MemOpLength->getType())); |
| return MI; |
| } |
| |
| Instruction *InstCombiner::SimplifyMemSet(MemSetInst *MI) { |
| unsigned Alignment = GetOrEnforceKnownAlignment(MI->getDest()); |
| if (MI->getAlignment()->getZExtValue() < Alignment) { |
| MI->setAlignment(ConstantInt::get(Type::Int32Ty, Alignment)); |
| return MI; |
| } |
| |
| // Extract the length and alignment and fill if they are constant. |
| ConstantInt *LenC = dyn_cast<ConstantInt>(MI->getLength()); |
| ConstantInt *FillC = dyn_cast<ConstantInt>(MI->getValue()); |
| if (!LenC || !FillC || FillC->getType() != Type::Int8Ty) |
| return 0; |
| uint64_t Len = LenC->getZExtValue(); |
| Alignment = MI->getAlignment()->getZExtValue(); |
| |
| // If the length is zero, this is a no-op |
| if (Len == 0) return MI; // memset(d,c,0,a) -> noop |
| |
| // memset(s,c,n) -> store s, c (for n=1,2,4,8) |
| if (Len <= 8 && isPowerOf2_32((uint32_t)Len)) { |
| const Type *ITy = IntegerType::get(Len*8); // n=1 -> i8. |
| |
| Value *Dest = MI->getDest(); |
| Dest = InsertBitCastBefore(Dest, PointerType::getUnqual(ITy), *MI); |
| |
| // Alignment 0 is identity for alignment 1 for memset, but not store. |
| if (Alignment == 0) Alignment = 1; |
| |
| // Extract the fill value and store. |
| uint64_t Fill = FillC->getZExtValue()*0x0101010101010101ULL; |
| InsertNewInstBefore(new StoreInst(ConstantInt::get(ITy, Fill), Dest, false, |
| Alignment), *MI); |
| |
| // Set the size of the copy to 0, it will be deleted on the next iteration. |
| MI->setLength(Constant::getNullValue(LenC->getType())); |
| return MI; |
| } |
| |
| return 0; |
| } |
| |
| |
| /// visitCallInst - CallInst simplification. This mostly only handles folding |
| /// of intrinsic instructions. For normal calls, it allows visitCallSite to do |
| /// the heavy lifting. |
| /// |
| Instruction *InstCombiner::visitCallInst(CallInst &CI) { |
| IntrinsicInst *II = dyn_cast<IntrinsicInst>(&CI); |
| if (!II) return visitCallSite(&CI); |
| |
| // Intrinsics cannot occur in an invoke, so handle them here instead of in |
| // visitCallSite. |
| if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(II)) { |
| bool Changed = false; |
| |
| // memmove/cpy/set of zero bytes is a noop. |
| if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) { |
| if (NumBytes->isNullValue()) return EraseInstFromFunction(CI); |
| |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes)) |
| if (CI->getZExtValue() == 1) { |
| // Replace the instruction with just byte operations. We would |
| // transform other cases to loads/stores, but we don't know if |
| // alignment is sufficient. |
| } |
| } |
| |
| // If we have a memmove and the source operation is a constant global, |
| // then the source and dest pointers can't alias, so we can change this |
| // into a call to memcpy. |
| if (MemMoveInst *MMI = dyn_cast<MemMoveInst>(MI)) { |
| if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource())) |
| if (GVSrc->isConstant()) { |
| Module *M = CI.getParent()->getParent()->getParent(); |
| Intrinsic::ID MemCpyID = Intrinsic::memcpy; |
| const Type *Tys[1]; |
| Tys[0] = CI.getOperand(3)->getType(); |
| CI.setOperand(0, |
| Intrinsic::getDeclaration(M, MemCpyID, Tys, 1)); |
| Changed = true; |
| } |
| |
| // memmove(x,x,size) -> noop. |
| if (MMI->getSource() == MMI->getDest()) |
| return EraseInstFromFunction(CI); |
| } |
| |
| // If we can determine a pointer alignment that is bigger than currently |
| // set, update the alignment. |
| if (isa<MemCpyInst>(MI) || isa<MemMoveInst>(MI)) { |
| if (Instruction *I = SimplifyMemTransfer(MI)) |
| return I; |
| } else if (MemSetInst *MSI = dyn_cast<MemSetInst>(MI)) { |
| if (Instruction *I = SimplifyMemSet(MSI)) |
| return I; |
| } |
| |
| if (Changed) return II; |
| } |
| |
| switch (II->getIntrinsicID()) { |
| default: break; |
| case Intrinsic::bswap: |
| // bswap(bswap(x)) -> x |
| if (IntrinsicInst *Operand = dyn_cast<IntrinsicInst>(II->getOperand(1))) |
| if (Operand->getIntrinsicID() == Intrinsic::bswap) |
| return ReplaceInstUsesWith(CI, Operand->getOperand(1)); |
| break; |
| case Intrinsic::ppc_altivec_lvx: |
| case Intrinsic::ppc_altivec_lvxl: |
| case Intrinsic::x86_sse_loadu_ps: |
| case Intrinsic::x86_sse2_loadu_pd: |
| case Intrinsic::x86_sse2_loadu_dq: |
| // Turn PPC lvx -> load if the pointer is known aligned. |
| // Turn X86 loadups -> load if the pointer is known aligned. |
| if (GetOrEnforceKnownAlignment(II->getOperand(1), 16) >= 16) { |
| Value *Ptr = InsertBitCastBefore(II->getOperand(1), |
| PointerType::getUnqual(II->getType()), |
| CI); |
| return new LoadInst(Ptr); |
| } |
| break; |
| case Intrinsic::ppc_altivec_stvx: |
| case Intrinsic::ppc_altivec_stvxl: |
| // Turn stvx -> store if the pointer is known aligned. |
| if (GetOrEnforceKnownAlignment(II->getOperand(2), 16) >= 16) { |
| const Type *OpPtrTy = |
| PointerType::getUnqual(II->getOperand(1)->getType()); |
| Value *Ptr = InsertBitCastBefore(II->getOperand(2), OpPtrTy, CI); |
| return new StoreInst(II->getOperand(1), Ptr); |
| } |
| break; |
| case Intrinsic::x86_sse_storeu_ps: |
| case Intrinsic::x86_sse2_storeu_pd: |
| case Intrinsic::x86_sse2_storeu_dq: |
| // Turn X86 storeu -> store if the pointer is known aligned. |
| if (GetOrEnforceKnownAlignment(II->getOperand(1), 16) >= 16) { |
| const Type *OpPtrTy = |
| PointerType::getUnqual(II->getOperand(2)->getType()); |
| Value *Ptr = InsertBitCastBefore(II->getOperand(1), OpPtrTy, CI); |
| return new StoreInst(II->getOperand(2), Ptr); |
| } |
| break; |
| |
| case Intrinsic::x86_sse_cvttss2si: { |
| // These intrinsics only demands the 0th element of its input vector. If |
| // we can simplify the input based on that, do so now. |
| uint64_t UndefElts; |
| if (Value *V = SimplifyDemandedVectorElts(II->getOperand(1), 1, |
| UndefElts)) { |
| II->setOperand(1, V); |
| return II; |
| } |
| break; |
| } |
| |
| case Intrinsic::ppc_altivec_vperm: |
| // Turn vperm(V1,V2,mask) -> shuffle(V1,V2,mask) if mask is a constant. |
| if (ConstantVector *Mask = dyn_cast<ConstantVector>(II->getOperand(3))) { |
| assert(Mask->getNumOperands() == 16 && "Bad type for intrinsic!"); |
| |
| // Check that all of the elements are integer constants or undefs. |
| bool AllEltsOk = true; |
| for (unsigned i = 0; i != 16; ++i) { |
| if (!isa<ConstantInt>(Mask->getOperand(i)) && |
| !isa<UndefValue>(Mask->getOperand(i))) { |
| AllEltsOk = false; |
| break; |
| } |
| } |
| |
| if (AllEltsOk) { |
| // Cast the input vectors to byte vectors. |
| Value *Op0 =InsertBitCastBefore(II->getOperand(1),Mask->getType(),CI); |
| Value *Op1 =InsertBitCastBefore(II->getOperand(2),Mask->getType(),CI); |
| Value *Result = UndefValue::get(Op0->getType()); |
| |
| // Only extract each element once. |
| Value *ExtractedElts[32]; |
| memset(ExtractedElts, 0, sizeof(ExtractedElts)); |
| |
| for (unsigned i = 0; i != 16; ++i) { |
| if (isa<UndefValue>(Mask->getOperand(i))) |
| continue; |
| unsigned Idx=cast<ConstantInt>(Mask->getOperand(i))->getZExtValue(); |
| Idx &= 31; // Match the hardware behavior. |
| |
| if (ExtractedElts[Idx] == 0) { |
| Instruction *Elt = |
| new ExtractElementInst(Idx < 16 ? Op0 : Op1, Idx&15, "tmp"); |
| InsertNewInstBefore(Elt, CI); |
| ExtractedElts[Idx] = Elt; |
| } |
| |
| // Insert this value into the result vector. |
| Result = InsertElementInst::Create(Result, ExtractedElts[Idx], |
| i, "tmp"); |
| InsertNewInstBefore(cast<Instruction>(Result), CI); |
| } |
| return CastInst::Create(Instruction::BitCast, Result, CI.getType()); |
| } |
| } |
| break; |
| |
| case Intrinsic::stackrestore: { |
| // If the save is right next to the restore, remove the restore. This can |
| // happen when variable allocas are DCE'd. |
| if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getOperand(1))) { |
| if (SS->getIntrinsicID() == Intrinsic::stacksave) { |
| BasicBlock::iterator BI = SS; |
| if (&*++BI == II) |
| return EraseInstFromFunction(CI); |
| } |
| } |
| |
| // Scan down this block to see if there is another stack restore in the |
| // same block without an intervening call/alloca. |
| BasicBlock::iterator BI = II; |
| TerminatorInst *TI = II->getParent()->getTerminator(); |
| bool CannotRemove = false; |
| for (++BI; &*BI != TI; ++BI) { |
| if (isa<AllocaInst>(BI)) { |
| CannotRemove = true; |
| break; |
| } |
| if (CallInst *BCI = dyn_cast<CallInst>(BI)) { |
| if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(BCI)) { |
| // If there is a stackrestore below this one, remove this one. |
| if (II->getIntrinsicID() == Intrinsic::stackrestore) |
| return EraseInstFromFunction(CI); |
| // Otherwise, ignore the intrinsic. |
| } else { |
| // If we found a non-intrinsic call, we can't remove the stack |
| // restore. |
| CannotRemove = true; |
| break; |
| } |
| } |
| } |
| |
| // If the stack restore is in a return/unwind block and if there are no |
| // allocas or calls between the restore and the return, nuke the restore. |
| if (!CannotRemove && (isa<ReturnInst>(TI) || isa<UnwindInst>(TI))) |
| return EraseInstFromFunction(CI); |
| break; |
| } |
| } |
| |
| return visitCallSite(II); |
| } |
| |
| // InvokeInst simplification |
| // |
| Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) { |
| return visitCallSite(&II); |
| } |
| |
| /// isSafeToEliminateVarargsCast - If this cast does not affect the value |
| /// passed through the varargs area, we can eliminate the use of the cast. |
| static bool isSafeToEliminateVarargsCast(const CallSite CS, |
| const CastInst * const CI, |
| const TargetData * const TD, |
| const int ix) { |
| if (!CI->isLosslessCast()) |
| return false; |
| |
| // The size of ByVal arguments is derived from the type, so we |
| // can't change to a type with a different size. If the size were |
| // passed explicitly we could avoid this check. |
| if (!CS.paramHasAttr(ix, Attribute::ByVal)) |
| return true; |
| |
| const Type* SrcTy = |
| cast<PointerType>(CI->getOperand(0)->getType())->getElementType(); |
| const Type* DstTy = cast<PointerType>(CI->getType())->getElementType(); |
| if (!SrcTy->isSized() || !DstTy->isSized()) |
| return false; |
| if (TD->getTypePaddedSize(SrcTy) != TD->getTypePaddedSize(DstTy)) |
| return false; |
| return true; |
| } |
| |
| // visitCallSite - Improvements for call and invoke instructions. |
| // |
| Instruction *InstCombiner::visitCallSite(CallSite CS) { |
| bool Changed = false; |
| |
| // If the callee is a constexpr cast of a function, attempt to move the cast |
| // to the arguments of the call/invoke. |
| if (transformConstExprCastCall(CS)) return 0; |
| |
| Value *Callee = CS.getCalledValue(); |
| |
| if (Function *CalleeF = dyn_cast<Function>(Callee)) |
| if (CalleeF->getCallingConv() != CS.getCallingConv()) { |
| Instruction *OldCall = CS.getInstruction(); |
| // If the call and callee calling conventions don't match, this call must |
| // be unreachable, as the call is undefined. |
| new StoreInst(ConstantInt::getTrue(), |
| UndefValue::get(PointerType::getUnqual(Type::Int1Ty)), |
| OldCall); |
| if (!OldCall->use_empty()) |
| OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType())); |
| if (isa<CallInst>(OldCall)) // Not worth removing an invoke here. |
| return EraseInstFromFunction(*OldCall); |
| return 0; |
| } |
| |
| if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) { |
| // This instruction is not reachable, just remove it. We insert a store to |
| // undef so that we know that this code is not reachable, despite the fact |
| // that we can't modify the CFG here. |
| new StoreInst(ConstantInt::getTrue(), |
| UndefValue::get(PointerType::getUnqual(Type::Int1Ty)), |
| CS.getInstruction()); |
| |
| if (!CS.getInstruction()->use_empty()) |
| CS.getInstruction()-> |
| replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType())); |
| |
| if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) { |
| // Don't break the CFG, insert a dummy cond branch. |
| BranchInst::Create(II->getNormalDest(), II->getUnwindDest(), |
| ConstantInt::getTrue(), II); |
| } |
| return EraseInstFromFunction(*CS.getInstruction()); |
| } |
| |
| if (BitCastInst *BC = dyn_cast<BitCastInst>(Callee)) |
| if (IntrinsicInst *In = dyn_cast<IntrinsicInst>(BC->getOperand(0))) |
| if (In->getIntrinsicID() == Intrinsic::init_trampoline) |
| return transformCallThroughTrampoline(CS); |
| |
| const PointerType *PTy = cast<PointerType>(Callee->getType()); |
| const FunctionType *FTy = cast<FunctionType>(PTy->getElementType()); |
| if (FTy->isVarArg()) { |
| int ix = FTy->getNumParams() + (isa<InvokeInst>(Callee) ? 3 : 1); |
| // See if we can optimize any arguments passed through the varargs area of |
| // the call. |
| for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(), |
| E = CS.arg_end(); I != E; ++I, ++ix) { |
| CastInst *CI = dyn_cast<CastInst>(*I); |
| if (CI && isSafeToEliminateVarargsCast(CS, CI, TD, ix)) { |
| *I = CI->getOperand(0); |
| Changed = true; |
| } |
| } |
| } |
| |
| if (isa<InlineAsm>(Callee) && !CS.doesNotThrow()) { |
| // Inline asm calls cannot throw - mark them 'nounwind'. |
| CS.setDoesNotThrow(); |
| Changed = true; |
| } |
| |
| return Changed ? CS.getInstruction() : 0; |
| } |
| |
| // transformConstExprCastCall - If the callee is a constexpr cast of a function, |
| // attempt to move the cast to the arguments of the call/invoke. |
| // |
| bool InstCombiner::transformConstExprCastCall(CallSite CS) { |
| if (!isa<ConstantExpr>(CS.getCalledValue())) return false; |
| ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue()); |
| if (CE->getOpcode() != Instruction::BitCast || |
| !isa<Function>(CE->getOperand(0))) |
| return false; |
| Function *Callee = cast<Function>(CE->getOperand(0)); |
| Instruction *Caller = CS.getInstruction(); |
| const AttrListPtr &CallerPAL = CS.getAttributes(); |
| |
| // Okay, this is a cast from a function to a different type. Unless doing so |
| // would cause a type conversion of one of our arguments, change this call to |
| // be a direct call with arguments casted to the appropriate types. |
| // |
| const FunctionType *FT = Callee->getFunctionType(); |
| const Type *OldRetTy = Caller->getType(); |
| const Type *NewRetTy = FT->getReturnType(); |
| |
| if (isa<StructType>(NewRetTy)) |
| return false; // TODO: Handle multiple return values. |
| |
| // Check to see if we are changing the return type... |
| if (OldRetTy != NewRetTy) { |
| if (Callee->isDeclaration() && |
| // Conversion is ok if changing from one pointer type to another or from |
| // a pointer to an integer of the same size. |
| !((isa<PointerType>(OldRetTy) || OldRetTy == TD->getIntPtrType()) && |
| (isa<PointerType>(NewRetTy) || NewRetTy == TD->getIntPtrType()))) |
| return false; // Cannot transform this return value. |
| |
| if (!Caller->use_empty() && |
| // void -> non-void is handled specially |
| NewRetTy != Type::VoidTy && !CastInst::isCastable(NewRetTy, OldRetTy)) |
| return false; // Cannot transform this return value. |
| |
| if (!CallerPAL.isEmpty() && !Caller->use_empty()) { |
| Attributes RAttrs = CallerPAL.getRetAttributes(); |
| if (RAttrs & Attribute::typeIncompatible(NewRetTy)) |
| return false; // Attribute not compatible with transformed value. |
| } |
| |
| // If the callsite is an invoke instruction, and the return value is used by |
| // a PHI node in a successor, we cannot change the return type of the call |
| // because there is no place to put the cast instruction (without breaking |
| // the critical edge). Bail out in this case. |
| if (!Caller->use_empty()) |
| if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) |
| for (Value::use_iterator UI = II->use_begin(), E = II->use_end(); |
| UI != E; ++UI) |
| if (PHINode *PN = dyn_cast<PHINode>(*UI)) |
| if (PN->getParent() == II->getNormalDest() || |
| PN->getParent() == II->getUnwindDest()) |
| return false; |
| } |
| |
| unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin()); |
| unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs); |
| |
| CallSite::arg_iterator AI = CS.arg_begin(); |
| for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) { |
| const Type *ParamTy = FT->getParamType(i); |
| const Type *ActTy = (*AI)->getType(); |
| |
| if (!CastInst::isCastable(ActTy, ParamTy)) |
| return false; // Cannot transform this parameter value. |
| |
| if (CallerPAL.getParamAttributes(i + 1) |
| & Attribute::typeIncompatible(ParamTy)) |
| return false; // Attribute not compatible with transformed value. |
| |
| // Converting from one pointer type to another or between a pointer and an |
| // integer of the same size is safe even if we do not have a body. |
| bool isConvertible = ActTy == ParamTy || |
| ((isa<PointerType>(ParamTy) || ParamTy == TD->getIntPtrType()) && |
| (isa<PointerType>(ActTy) || ActTy == TD->getIntPtrType())); |
| if (Callee->isDeclaration() && !isConvertible) return false; |
| } |
| |
| if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() && |
| Callee->isDeclaration()) |
| return false; // Do not delete arguments unless we have a function body. |
| |
| if (FT->getNumParams() < NumActualArgs && FT->isVarArg() && |
| !CallerPAL.isEmpty()) |
| // In this case we have more arguments than the new function type, but we |
| // won't be dropping them. Check that these extra arguments have attributes |
| // that are compatible with being a vararg call argument. |
| for (unsigned i = CallerPAL.getNumSlots(); i; --i) { |
| if (CallerPAL.getSlot(i - 1).Index <= FT->getNumParams()) |
| break; |
| Attributes PAttrs = CallerPAL.getSlot(i - 1).Attrs; |
| if (PAttrs & Attribute::VarArgsIncompatible) |
| return false; |
| } |
| |
| // Okay, we decided that this is a safe thing to do: go ahead and start |
| // inserting cast instructions as necessary... |
| std::vector<Value*> Args; |
| Args.reserve(NumActualArgs); |
| SmallVector<AttributeWithIndex, 8> attrVec; |
| attrVec.reserve(NumCommonArgs); |
| |
| // Get any return attributes. |
| Attributes RAttrs = CallerPAL.getRetAttributes(); |
| |
| // If the return value is not being used, the type may not be compatible |
| // with the existing attributes. Wipe out any problematic attributes. |
| RAttrs &= ~Attribute::typeIncompatible(NewRetTy); |
| |
| // Add the new return attributes. |
| if (RAttrs) |
| attrVec.push_back(AttributeWithIndex::get(0, RAttrs)); |
| |
| AI = CS.arg_begin(); |
| for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) { |
| const Type *ParamTy = FT->getParamType(i); |
| if ((*AI)->getType() == ParamTy) { |
| Args.push_back(*AI); |
| } else { |
| Instruction::CastOps opcode = CastInst::getCastOpcode(*AI, |
| false, ParamTy, false); |
| CastInst *NewCast = CastInst::Create(opcode, *AI, ParamTy, "tmp"); |
| Args.push_back(InsertNewInstBefore(NewCast, *Caller)); |
| } |
| |
| // Add any parameter attributes. |
| if (Attributes PAttrs = CallerPAL.getParamAttributes(i + 1)) |
| attrVec.push_back(AttributeWithIndex::get(i + 1, PAttrs)); |
| } |
| |
| // If the function takes more arguments than the call was taking, add them |
| // now... |
| for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i) |
| Args.push_back(Constant::getNullValue(FT->getParamType(i))); |
| |
| // If we are removing arguments to the function, emit an obnoxious warning... |
| if (FT->getNumParams() < NumActualArgs) { |
| if (!FT->isVarArg()) { |
| cerr << "WARNING: While resolving call to function '" |
| << Callee->getName() << "' arguments were dropped!\n"; |
| } else { |
| // Add all of the arguments in their promoted form to the arg list... |
| for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) { |
| const Type *PTy = getPromotedType((*AI)->getType()); |
| if (PTy != (*AI)->getType()) { |
| // Must promote to pass through va_arg area! |
| Instruction::CastOps opcode = CastInst::getCastOpcode(*AI, false, |
| PTy, false); |
| Instruction *Cast = CastInst::Create(opcode, *AI, PTy, "tmp"); |
| InsertNewInstBefore(Cast, *Caller); |
| Args.push_back(Cast); |
| } else { |
| Args.push_back(*AI); |
| } |
| |
| // Add any parameter attributes. |
| if (Attributes PAttrs = CallerPAL.getParamAttributes(i + 1)) |
| attrVec.push_back(AttributeWithIndex::get(i + 1, PAttrs)); |
| } |
| } |
| } |
| |
| if (Attributes FnAttrs = CallerPAL.getFnAttributes()) |
| attrVec.push_back(AttributeWithIndex::get(~0, FnAttrs)); |
| |
| if (NewRetTy == Type::VoidTy) |
| Caller->setName(""); // Void type should not have a name. |
| |
| const AttrListPtr &NewCallerPAL = AttrListPtr::get(attrVec.begin(),attrVec.end()); |
| |
| Instruction *NC; |
| if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) { |
| NC = InvokeInst::Create(Callee, II->getNormalDest(), II->getUnwindDest(), |
| Args.begin(), Args.end(), |
| Caller->getName(), Caller); |
| cast<InvokeInst>(NC)->setCallingConv(II->getCallingConv()); |
| cast<InvokeInst>(NC)->setAttributes(NewCallerPAL); |
| } else { |
| NC = CallInst::Create(Callee, Args.begin(), Args.end(), |
| Caller->getName(), Caller); |
| CallInst *CI = cast<CallInst>(Caller); |
| if (CI->isTailCall()) |
| cast<CallInst>(NC)->setTailCall(); |
| cast<CallInst>(NC)->setCallingConv(CI->getCallingConv()); |
| cast<CallInst>(NC)->setAttributes(NewCallerPAL); |
| } |
| |
| // Insert a cast of the return type as necessary. |
| Value *NV = NC; |
| if (OldRetTy != NV->getType() && !Caller->use_empty()) { |
| if (NV->getType() != Type::VoidTy) { |
| Instruction::CastOps opcode = CastInst::getCastOpcode(NC, false, |
| OldRetTy, false); |
| NV = NC = CastInst::Create(opcode, NC, OldRetTy, "tmp"); |
| |
| // If this is an invoke instruction, we should insert it after the first |
| // non-phi, instruction in the normal successor block. |
| if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) { |
| BasicBlock::iterator I = II->getNormalDest()->getFirstNonPHI(); |
| InsertNewInstBefore(NC, *I); |
| } else { |
| // Otherwise, it's a call, just insert cast right after the call instr |
| InsertNewInstBefore(NC, *Caller); |
| } |
| AddUsersToWorkList(*Caller); |
| } else { |
| NV = UndefValue::get(Caller->getType()); |
| } |
| } |
| |
| if (Caller->getType() != Type::VoidTy && !Caller->use_empty()) |
| Caller->replaceAllUsesWith(NV); |
| Caller->eraseFromParent(); |
| RemoveFromWorkList(Caller); |
| return true; |
| } |
| |
| // transformCallThroughTrampoline - Turn a call to a function created by the |
| // init_trampoline intrinsic into a direct call to the underlying function. |
| // |
| Instruction *InstCombiner::transformCallThroughTrampoline(CallSite CS) { |
| Value *Callee = CS.getCalledValue(); |
| const PointerType *PTy = cast<PointerType>(Callee->getType()); |
| const FunctionType *FTy = cast<FunctionType>(PTy->getElementType()); |
| const AttrListPtr &Attrs = CS.getAttributes(); |
| |
| // If the call already has the 'nest' attribute somewhere then give up - |
| // otherwise 'nest' would occur twice after splicing in the chain. |
| if (Attrs.hasAttrSomewhere(Attribute::Nest)) |
| return 0; |
| |
| IntrinsicInst *Tramp = |
| cast<IntrinsicInst>(cast<BitCastInst>(Callee)->getOperand(0)); |
| |
| Function *NestF = cast<Function>(Tramp->getOperand(2)->stripPointerCasts()); |
| const PointerType *NestFPTy = cast<PointerType>(NestF->getType()); |
| const FunctionType *NestFTy = cast<FunctionType>(NestFPTy->getElementType()); |
| |
| const AttrListPtr &NestAttrs = NestF->getAttributes(); |
| if (!NestAttrs.isEmpty()) { |
| unsigned NestIdx = 1; |
| const Type *NestTy = 0; |
| Attributes NestAttr = Attribute::None; |
| |
| // Look for a parameter marked with the 'nest' attribute. |
| for (FunctionType::param_iterator I = NestFTy->param_begin(), |
| E = NestFTy->param_end(); I != E; ++NestIdx, ++I) |
| if (NestAttrs.paramHasAttr(NestIdx, Attribute::Nest)) { |
| // Record the parameter type and any other attributes. |
| NestTy = *I; |
| NestAttr = NestAttrs.getParamAttributes(NestIdx); |
| break; |
| } |
| |
| if (NestTy) { |
| Instruction *Caller = CS.getInstruction(); |
| std::vector<Value*> NewArgs; |
| NewArgs.reserve(unsigned(CS.arg_end()-CS.arg_begin())+1); |
| |
| SmallVector<AttributeWithIndex, 8> NewAttrs; |
| NewAttrs.reserve(Attrs.getNumSlots() + 1); |
| |
| // Insert the nest argument into the call argument list, which may |
| // mean appending it. Likewise for attributes. |
| |
| // Add any result attributes. |
| if (Attributes Attr = Attrs.getRetAttributes()) |
| NewAttrs.push_back(AttributeWithIndex::get(0, Attr)); |
| |
| { |
| unsigned Idx = 1; |
| CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end(); |
| do { |
| if (Idx == NestIdx) { |
| // Add the chain argument and attributes. |
| Value *NestVal = Tramp->getOperand(3); |
| if (NestVal->getType() != NestTy) |
| NestVal = new BitCastInst(NestVal, NestTy, "nest", Caller); |
| NewArgs.push_back(NestVal); |
| NewAttrs.push_back(AttributeWithIndex::get(NestIdx, NestAttr)); |
| } |
| |
| if (I == E) |
| break; |
| |
| // Add the original argument and attributes. |
| NewArgs.push_back(*I); |
| if (Attributes Attr = Attrs.getParamAttributes(Idx)) |
| NewAttrs.push_back |
| (AttributeWithIndex::get(Idx + (Idx >= NestIdx), Attr)); |
| |
| ++Idx, ++I; |
| } while (1); |
| } |
| |
| // Add any function attributes. |
| if (Attributes Attr = Attrs.getFnAttributes()) |
| NewAttrs.push_back(AttributeWithIndex::get(~0, Attr)); |
| |
| // The trampoline may have been bitcast to a bogus type (FTy). |
| // Handle this by synthesizing a new function type, equal to FTy |
| // with the chain parameter inserted. |
| |
| std::vector<const Type*> NewTypes; |
| NewTypes.reserve(FTy->getNumParams()+1); |
| |
| // Insert the chain's type into the list of parameter types, which may |
| // mean appending it. |
| { |
| unsigned Idx = 1; |
| FunctionType::param_iterator I = FTy->param_begin(), |
| E = FTy->param_end(); |
| |
| do { |
| if (Idx == NestIdx) |
| // Add the chain's type. |
| NewTypes.push_back(NestTy); |
| |
| if (I == E) |
| break; |
| |
| // Add the original type. |
| NewTypes.push_back(*I); |
| |
| ++Idx, ++I; |
| } while (1); |
| } |
| |
| // Replace the trampoline call with a direct call. Let the generic |
| // code sort out any function type mismatches. |
| FunctionType *NewFTy = |
| FunctionType::get(FTy->getReturnType(), NewTypes, FTy->isVarArg()); |
| Constant *NewCallee = NestF->getType() == PointerType::getUnqual(NewFTy) ? |
| NestF : ConstantExpr::getBitCast(NestF, PointerType::getUnqual(NewFTy)); |
| const AttrListPtr &NewPAL = AttrListPtr::get(NewAttrs.begin(),NewAttrs.end()); |
| |
| Instruction *NewCaller; |
| if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) { |
| NewCaller = InvokeInst::Create(NewCallee, |
| II->getNormalDest(), II->getUnwindDest(), |
| NewArgs.begin(), NewArgs.end(), |
| Caller->getName(), Caller); |
| cast<InvokeInst>(NewCaller)->setCallingConv(II->getCallingConv()); |
| cast<InvokeInst>(NewCaller)->setAttributes(NewPAL); |
| } else { |
| NewCaller = CallInst::Create(NewCallee, NewArgs.begin(), NewArgs.end(), |
| Caller->getName(), Caller); |
| if (cast<CallInst>(Caller)->isTailCall()) |
| cast<CallInst>(NewCaller)->setTailCall(); |
| cast<CallInst>(NewCaller)-> |
| setCallingConv(cast<CallInst>(Caller)->getCallingConv()); |
| cast<CallInst>(NewCaller)->setAttributes(NewPAL); |
| } |
| if (Caller->getType() != Type::VoidTy && !Caller->use_empty()) |
| Caller->replaceAllUsesWith(NewCaller); |
| Caller->eraseFromParent(); |
| RemoveFromWorkList(Caller); |
| return 0; |
| } |
| } |
| |
| // Replace the trampoline call with a direct call. Since there is no 'nest' |
| // parameter, there is no need to adjust the argument list. Let the generic |
| // code sort out any function type mismatches. |
| Constant *NewCallee = |
| NestF->getType() == PTy ? NestF : ConstantExpr::getBitCast(NestF, PTy); |
| CS.setCalledFunction(NewCallee); |
| return CS.getInstruction(); |
| } |
| |
| /// FoldPHIArgBinOpIntoPHI - If we have something like phi [add (a,b), add(c,d)] |
| /// and if a/b/c/d and the add's all have a single use, turn this into two phi's |
| /// and a single binop. |
| Instruction *InstCombiner::FoldPHIArgBinOpIntoPHI(PHINode &PN) { |
| Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0)); |
| assert(isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst)); |
| unsigned Opc = FirstInst->getOpcode(); |
| Value *LHSVal = FirstInst->getOperand(0); |
| Value *RHSVal = FirstInst->getOperand(1); |
| |
| const Type *LHSType = LHSVal->getType(); |
| const Type *RHSType = RHSVal->getType(); |
| |
| // Scan to see if all operands are the same opcode, all have one use, and all |
| // kill their operands (i.e. the operands have one use). |
| for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) { |
| Instruction *I = dyn_cast<Instruction>(PN.getIncomingValue(i)); |
| if (!I || I->getOpcode() != Opc || !I->hasOneUse() || |
| // Verify type of the LHS matches so we don't fold cmp's of different |
| // types or GEP's with different index types. |
| I->getOperand(0)->getType() != LHSType || |
| I->getOperand(1)->getType() != RHSType) |
| return 0; |
| |
| // If they are CmpInst instructions, check their predicates |
| if (Opc == Instruction::ICmp || Opc == Instruction::FCmp) |
| if (cast<CmpInst>(I)->getPredicate() != |
| cast<CmpInst>(FirstInst)->getPredicate()) |
| return 0; |
| |
| // Keep track of which operand needs a phi node. |
| if (I->getOperand(0) != LHSVal) LHSVal = 0; |
| if (I->getOperand(1) != RHSVal) RHSVal = 0; |
| } |
| |
| // Otherwise, this is safe to transform! |
| |
| Value *InLHS = FirstInst->getOperand(0); |
| Value *InRHS = FirstInst->getOperand(1); |
| PHINode *NewLHS = 0, *NewRHS = 0; |
| if (LHSVal == 0) { |
| NewLHS = PHINode::Create(LHSType, |
| FirstInst->getOperand(0)->getName() + ".pn"); |
| NewLHS->reserveOperandSpace(PN.getNumOperands()/2); |
| NewLHS->addIncoming(InLHS, PN.getIncomingBlock(0)); |
| InsertNewInstBefore(NewLHS, PN); |
| LHSVal = NewLHS; |
| } |
| |
| if (RHSVal == 0) { |
| NewRHS = PHINode::Create(RHSType, |
| FirstInst->getOperand(1)->getName() + ".pn"); |
| NewRHS->reserveOperandSpace(PN.getNumOperands()/2); |
| NewRHS->addIncoming(InRHS, PN.getIncomingBlock(0)); |
| InsertNewInstBefore(NewRHS, PN); |
| RHSVal = NewRHS; |
| } |
| |
| // Add all operands to the new PHIs. |
| if (NewLHS || NewRHS) { |
| for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) { |
| Instruction *InInst = cast<Instruction>(PN.getIncomingValue(i)); |
| if (NewLHS) { |
| Value *NewInLHS = InInst->getOperand(0); |
| NewLHS->addIncoming(NewInLHS, PN.getIncomingBlock(i)); |
| } |
| if (NewRHS) { |
| Value *NewInRHS = InInst->getOperand(1); |
| NewRHS->addIncoming(NewInRHS, PN.getIncomingBlock(i)); |
| } |
| } |
| } |
| |
| if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst)) |
| return BinaryOperator::Create(BinOp->getOpcode(), LHSVal, RHSVal); |
| CmpInst *CIOp = cast<CmpInst>(FirstInst); |
| return CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(), LHSVal, |
| RHSVal); |
| } |
| |
| Instruction *InstCombiner::FoldPHIArgGEPIntoPHI(PHINode &PN) { |
| GetElementPtrInst *FirstInst =cast<GetElementPtrInst>(PN.getIncomingValue(0)); |
| |
| SmallVector<Value*, 16> FixedOperands(FirstInst->op_begin(), |
| FirstInst->op_end()); |
| |
| // Scan to see if all operands are the same opcode, all have one use, and all |
| // kill their operands (i.e. the operands have one use). |
| for (unsigned i = 1; i != PN.getNumIncomingValues(); ++i) { |
| GetElementPtrInst *GEP= dyn_cast<GetElementPtrInst>(PN.getIncomingValue(i)); |
| if (!GEP || !GEP->hasOneUse() || GEP->getType() != FirstInst->getType() || |
| GEP->getNumOperands() != FirstInst->getNumOperands()) |
| return 0; |
| |
| // Compare the operand lists. |
| for (unsigned op = 0, e = FirstInst->getNumOperands(); op != e; ++op) { |
| if (FirstInst->getOperand(op) == GEP->getOperand(op)) |
| continue; |
| |
| // Don't merge two GEPs when two operands differ (introducing phi nodes) |
| // if one of the PHIs has a constant for the index. The index may be |
| // substantially cheaper to compute for the constants, so making it a |
| // variable index could pessimize the path. This also handles the case |
| // for struct indices, which must always be constant. |
| if (isa<ConstantInt>(FirstInst->getOperand(op)) || |
| isa<ConstantInt>(GEP->getOperand(op))) |
| return 0; |
| |
| if (FirstInst->getOperand(op)->getType() !=GEP->getOperand(op)->getType()) |
| return 0; |
| FixedOperands[op] = 0; // Needs a PHI. |
| } |
| } |
| |
| // Otherwise, this is safe to transform. Insert PHI nodes for each operand |
| // that is variable. |
| SmallVector<PHINode*, 16> OperandPhis(FixedOperands.size()); |
| |
| bool HasAnyPHIs = false; |
| for (unsigned i = 0, e = FixedOperands.size(); i != e; ++i) { |
| if (FixedOperands[i]) continue; // operand doesn't need a phi. |
| Value *FirstOp = FirstInst->getOperand(i); |
| PHINode *NewPN = PHINode::Create(FirstOp->getType(), |
| FirstOp->getName()+".pn"); |
| InsertNewInstBefore(NewPN, PN); |
| |
| NewPN->reserveOperandSpace(e); |
| NewPN->addIncoming(FirstOp, PN.getIncomingBlock(0)); |
| OperandPhis[i] = NewPN; |
| FixedOperands[i] = NewPN; |
| HasAnyPHIs = true; |
| } |
| |
| |
| // Add all operands to the new PHIs. |
| if (HasAnyPHIs) { |
| for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) { |
| GetElementPtrInst *InGEP =cast<GetElementPtrInst>(PN.getIncomingValue(i)); |
| BasicBlock *InBB = PN.getIncomingBlock(i); |
| |
| for (unsigned op = 0, e = OperandPhis.size(); op != e; ++op) |
| if (PHINode *OpPhi = OperandPhis[op]) |
| OpPhi->addIncoming(InGEP->getOperand(op), InBB); |
| } |
| } |
| |
| Value *Base = FixedOperands[0]; |
| return GetElementPtrInst::Create(Base, FixedOperands.begin()+1, |
| FixedOperands.end()); |
| } |
| |
| |
| /// isSafeToSinkLoad - Return true if we know that it is safe sink the load out |
| /// of the block that defines it. This means that it must be obvious the value |
| /// of the load is not changed from the point of the load to the end of the |
| /// block it is in. |
| /// |
| /// Finally, it is safe, but not profitable, to sink a load targetting a |
| /// non-address-taken alloca. Doing so will cause us to not promote the alloca |
| /// to a register. |
| static bool isSafeToSinkLoad(LoadInst *L) { |
| BasicBlock::iterator BBI = L, E = L->getParent()->end(); |
| |
| for (++BBI; BBI != E; ++BBI) |
| if (BBI->mayWriteToMemory()) |
| return false; |
| |
| // Check for non-address taken alloca. If not address-taken already, it isn't |
| // profitable to do this xform. |
| if (AllocaInst *AI = dyn_cast<AllocaInst>(L->getOperand(0))) { |
| bool isAddressTaken = false; |
| for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end(); |
| UI != E; ++UI) { |
| if (isa<LoadInst>(UI)) continue; |
| if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) { |
| // If storing TO the alloca, then the address isn't taken. |
| if (SI->getOperand(1) == AI) continue; |
| } |
| isAddressTaken = true; |
| break; |
| } |
| |
| if (!isAddressTaken) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| |
| // FoldPHIArgOpIntoPHI - If all operands to a PHI node are the same "unary" |
| // operator and they all are only used by the PHI, PHI together their |
| // inputs, and do the operation once, to the result of the PHI. |
| Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) { |
| Instruction *FirstInst = cast<Instruction>(PN.getIncomingValue(0)); |
| |
| // Scan the instruction, looking for input operations that can be folded away. |
| // If all input operands to the phi are the same instruction (e.g. a cast from |
| // the same type or "+42") we can pull the operation through the PHI, reducing |
| // code size and simplifying code. |
| Constant *ConstantOp = 0; |
| const Type *CastSrcTy = 0; |
| bool isVolatile = false; |
| if (isa<CastInst>(FirstInst)) { |
| CastSrcTy = FirstInst->getOperand(0)->getType(); |
| } else if (isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst)) { |
| // Can fold binop, compare or shift here if the RHS is a constant, |
| // otherwise call FoldPHIArgBinOpIntoPHI. |
| ConstantOp = dyn_cast<Constant>(FirstInst->getOperand(1)); |
| if (ConstantOp == 0) |
| return FoldPHIArgBinOpIntoPHI(PN); |
| } else if (LoadInst *LI = dyn_cast<LoadInst>(FirstInst)) { |
| isVolatile = LI->isVolatile(); |
| // We can't sink the load if the loaded value could be modified between the |
| // load and the PHI. |
| if (LI->getParent() != PN.getIncomingBlock(0) || |
| !isSafeToSinkLoad(LI)) |
| return 0; |
| |
| // If the PHI is of volatile loads and the load block has multiple |
| // successors, sinking it would remove a load of the volatile value from |
| // the path through the other successor. |
| if (isVolatile && |
| LI->getParent()->getTerminator()->getNumSuccessors() != 1) |
| return 0; |
| |
| } else if (isa<GetElementPtrInst>(FirstInst)) { |
| return FoldPHIArgGEPIntoPHI(PN); |
| } else { |
| return 0; // Cannot fold this operation. |
| } |
| |
| // Check to see if all arguments are the same operation. |
| for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) { |
| if (!isa<Instruction>(PN.getIncomingValue(i))) return 0; |
| Instruction *I = cast<Instruction>(PN.getIncomingValue(i)); |
| if (!I->hasOneUse() || !I->isSameOperationAs(FirstInst)) |
| return 0; |
| if (CastSrcTy) { |
| if (I->getOperand(0)->getType() != CastSrcTy) |
| return 0; // Cast operation must match. |
| } else if (LoadInst *LI = dyn_cast<LoadInst>(I)) { |
| // We can't sink the load if the loaded value could be modified between |
| // the load and the PHI. |
| if (LI->isVolatile() != isVolatile || |
| LI->getParent() != PN.getIncomingBlock(i) || |
| !isSafeToSinkLoad(LI)) |
| return 0; |
| |
| // If the PHI is of volatile loads and the load block has multiple |
| // successors, sinking it would remove a load of the volatile value from |
| // the path through the other successor. |
| if (isVolatile && |
| LI->getParent()->getTerminator()->getNumSuccessors() != 1) |
| return 0; |
| |
| |
| } else if (I->getOperand(1) != ConstantOp) { |
| return 0; |
| } |
| } |
| |
| // Okay, they are all the same operation. Create a new PHI node of the |
| // correct type, and PHI together all of the LHS's of the instructions. |
| PHINode *NewPN = PHINode::Create(FirstInst->getOperand(0)->getType(), |
| PN.getName()+".in"); |
| NewPN->reserveOperandSpace(PN.getNumOperands()/2); |
| |
| Value *InVal = FirstInst->getOperand(0); |
| NewPN->addIncoming(InVal, PN.getIncomingBlock(0)); |
| |
| // Add all operands to the new PHI. |
| for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) { |
| Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0); |
| if (NewInVal != InVal) |
| InVal = 0; |
| NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i)); |
| } |
| |
| Value *PhiVal; |
| if (InVal) { |
| // The new PHI unions all of the same values together. This is really |
| // common, so we handle it intelligently here for compile-time speed. |
| PhiVal = InVal; |
| delete NewPN; |
| } else { |
| InsertNewInstBefore(NewPN, PN); |
| PhiVal = NewPN; |
| } |
| |
| // Insert and return the new operation. |
| if (CastInst* FirstCI = dyn_cast<CastInst>(FirstInst)) |
| return CastInst::Create(FirstCI->getOpcode(), PhiVal, PN.getType()); |
| if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst)) |
| return BinaryOperator::Create(BinOp->getOpcode(), PhiVal, ConstantOp); |
| if (CmpInst *CIOp = dyn_cast<CmpInst>(FirstInst)) |
| return CmpInst::Create(CIOp->getOpcode(), CIOp->getPredicate(), |
| PhiVal, ConstantOp); |
| assert(isa<LoadInst>(FirstInst) && "Unknown operation"); |
| |
| // If this was a volatile load that we are merging, make sure to loop through |
| // and mark all the input loads as non-volatile. If we don't do this, we will |
| // insert a new volatile load and the old ones will not be deletable. |
| if (isVolatile) |
| for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) |
| cast<LoadInst>(PN.getIncomingValue(i))->setVolatile(false); |
| |
| return new LoadInst(PhiVal, "", isVolatile); |
| } |
| |
| /// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle |
| /// that is dead. |
| static bool DeadPHICycle(PHINode *PN, |
| SmallPtrSet<PHINode*, 16> &PotentiallyDeadPHIs) { |
| if (PN->use_empty()) return true; |
| if (!PN->hasOneUse()) return false; |
| |
| // Remember this node, and if we find the cycle, return. |
| if (!PotentiallyDeadPHIs.insert(PN)) |
| return true; |
| |
| // Don't scan crazily complex things. |
| if (PotentiallyDeadPHIs.size() == 16) |
| return false; |
| |
| if (PHINode *PU = dyn_cast<PHINode>(PN->use_back())) |
| return DeadPHICycle(PU, PotentiallyDeadPHIs); |
| |
| return false; |
| } |
| |
| /// PHIsEqualValue - Return true if this phi node is always equal to |
| /// NonPhiInVal. This happens with mutually cyclic phi nodes like: |
| /// z = some value; x = phi (y, z); y = phi (x, z) |
| static bool PHIsEqualValue(PHINode *PN, Value *NonPhiInVal, |
| SmallPtrSet<PHINode*, 16> &ValueEqualPHIs) { |
| // See if we already saw this PHI node. |
| if (!ValueEqualPHIs.insert(PN)) |
| return true; |
| |
| // Don't scan crazily complex things. |
| if (ValueEqualPHIs.size() == 16) |
| return false; |
| |
| // Scan the operands to see if they are either phi nodes or are equal to |
| // the value. |
| for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { |
| Value *Op = PN->getIncomingValue(i); |
| if (PHINode *OpPN = dyn_cast<PHINode>(Op)) { |
| if (!PHIsEqualValue(OpPN, NonPhiInVal, ValueEqualPHIs)) |
| return false; |
| } else if (Op != NonPhiInVal) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| |
| // PHINode simplification |
| // |
| Instruction *InstCombiner::visitPHINode(PHINode &PN) { |
| // If LCSSA is around, don't mess with Phi nodes |
| if (MustPreserveLCSSA) return 0; |
| |
| if (Value *V = PN.hasConstantValue()) |
| return ReplaceInstUsesWith(PN, V); |
| |
| // If all PHI operands are the same operation, pull them through the PHI, |
| // reducing code size. |
| if (isa<Instruction>(PN.getIncomingValue(0)) && |
| isa<Instruction>(PN.getIncomingValue(1)) && |
| cast<Instruction>(PN.getIncomingValue(0))->getOpcode() == |
| cast<Instruction>(PN.getIncomingValue(1))->getOpcode() && |
| // FIXME: The hasOneUse check will fail for PHIs that use the value more |
| // than themselves more than once. |
| PN.getIncomingValue(0)->hasOneUse()) |
| if (Instruction *Result = FoldPHIArgOpIntoPHI(PN)) |
| return Result; |
| |
| // If this is a trivial cycle in the PHI node graph, remove it. Basically, if |
| // this PHI only has a single use (a PHI), and if that PHI only has one use (a |
| // PHI)... break the cycle. |
| if (PN.hasOneUse()) { |
| Instruction *PHIUser = cast<Instruction>(PN.use_back()); |
| if (PHINode *PU = dyn_cast<PHINode>(PHIUser)) { |
| SmallPtrSet<PHINode*, 16> PotentiallyDeadPHIs; |
| PotentiallyDeadPHIs.insert(&PN); |
| if (DeadPHICycle(PU, PotentiallyDeadPHIs)) |
| return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType())); |
| } |
| |
| // If this phi has a single use, and if that use just computes a value for |
| // the next iteration of a loop, delete the phi. This occurs with unused |
| // induction variables, e.g. "for (int j = 0; ; ++j);". Detecting this |
| // common case here is good because the only other things that catch this |
| // are induction variable analysis (sometimes) and ADCE, which is only run |
| // late. |
| if (PHIUser->hasOneUse() && |
| (isa<BinaryOperator>(PHIUser) || isa<GetElementPtrInst>(PHIUser)) && |
| PHIUser->use_back() == &PN) { |
| return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType())); |
| } |
| } |
| |
| // We sometimes end up with phi cycles that non-obviously end up being the |
| // same value, for example: |
| // z = some value; x = phi (y, z); y = phi (x, z) |
| // where the phi nodes don't necessarily need to be in the same block. Do a |
| // quick check to see if the PHI node only contains a single non-phi value, if |
| // so, scan to see if the phi cycle is actually equal to that value. |
| { |
| unsigned InValNo = 0, NumOperandVals = PN.getNumIncomingValues(); |
| // Scan for the first non-phi operand. |
| while (InValNo != NumOperandVals && |
| isa<PHINode>(PN.getIncomingValue(InValNo))) |
| ++InValNo; |
| |
| if (InValNo != NumOperandVals) { |
| Value *NonPhiInVal = PN.getOperand(InValNo); |
| |
| // Scan the rest of the operands to see if there are any conflicts, if so |
| // there is no need to recursively scan other phis. |
| for (++InValNo; InValNo != NumOperandVals; ++InValNo) { |
| Value *OpVal = PN.getIncomingValue(InValNo); |
| if (OpVal != NonPhiInVal && !isa<PHINode>(OpVal)) |
| break; |
| } |
| |
| // If we scanned over all operands, then we have one unique value plus |
| // phi values. Scan PHI nodes to see if they all merge in each other or |
| // the value. |
| if (InValNo == NumOperandVals) { |
| SmallPtrSet<PHINode*, 16> ValueEqualPHIs; |
| if (PHIsEqualValue(&PN, NonPhiInVal, ValueEqualPHIs)) |
| return ReplaceInstUsesWith(PN, NonPhiInVal); |
| } |
| } |
| } |
| return 0; |
| } |
| |
| static Value *InsertCastToIntPtrTy(Value *V, const Type *DTy, |
| Instruction *InsertPoint, |
| InstCombiner *IC) { |
| unsigned PtrSize = DTy->getPrimitiveSizeInBits(); |
| unsigned VTySize = V->getType()->getPrimitiveSizeInBits(); |
| // We must cast correctly to the pointer type. Ensure that we |
| // sign extend the integer value if it is smaller as this is |
| // used for address computation. |
| Instruction::CastOps opcode = |
| (VTySize < PtrSize ? Instruction::SExt : |
| (VTySize == PtrSize ? Instruction::BitCast : Instruction::Trunc)); |
| return IC->InsertCastBefore(opcode, V, DTy, *InsertPoint); |
| } |
| |
| |
| Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) { |
| Value *PtrOp = GEP.getOperand(0); |
| // Is it 'getelementptr %P, i32 0' or 'getelementptr %P' |
| // If so, eliminate the noop. |
| if (GEP.getNumOperands() == 1) |
| return ReplaceInstUsesWith(GEP, PtrOp); |
| |
| if (isa<UndefValue>(GEP.getOperand(0))) |
| return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType())); |
| |
| bool HasZeroPointerIndex = false; |
| if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1))) |
| HasZeroPointerIndex = C->isNullValue(); |
| |
| if (GEP.getNumOperands() == 2 && HasZeroPointerIndex) |
| return ReplaceInstUsesWith(GEP, PtrOp); |
| |
| // Eliminate unneeded casts for indices. |
| bool MadeChange = false; |
| |
| gep_type_iterator GTI = gep_type_begin(GEP); |
| for (User::op_iterator i = GEP.op_begin() + 1, e = GEP.op_end(); |
| i != e; ++i, ++GTI) { |
| if (isa<SequentialType>(*GTI)) { |
| if (CastInst *CI = dyn_cast<CastInst>(*i)) { |
| if (CI->getOpcode() == Instruction::ZExt || |
| CI->getOpcode() == Instruction::SExt) { |
| const Type *SrcTy = CI->getOperand(0)->getType(); |
| // We can eliminate a cast from i32 to i64 iff the target |
| // is a 32-bit pointer target. |
| if (SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) { |
| MadeChange = true; |
| *i = CI->getOperand(0); |
| } |
| } |
| } |
| // If we are using a wider index than needed for this platform, shrink it |
| // to what we need. If narrower, sign-extend it to what we need. |
| // If the incoming value needs a cast instruction, |
| // insert it. This explicit cast can make subsequent optimizations more |
| // obvious. |
| Value *Op = *i; |
| if (TD->getTypeSizeInBits(Op->getType()) > TD->getPointerSizeInBits()) { |
| if (Constant *C = dyn_cast<Constant>(Op)) { |
| *i = ConstantExpr::getTrunc(C, TD->getIntPtrType()); |
| MadeChange = true; |
| } else { |
| Op = InsertCastBefore(Instruction::Trunc, Op, TD->getIntPtrType(), |
| GEP); |
| *i = Op; |
| MadeChange = true; |
| } |
| } else if (TD->getTypeSizeInBits(Op->getType()) < TD->getPointerSizeInBits()) { |
| if (Constant *C = dyn_cast<Constant>(Op)) { |
| *i = ConstantExpr::getSExt(C, TD->getIntPtrType()); |
| MadeChange = true; |
| } else { |
| Op = InsertCastBefore(Instruction::SExt, Op, TD->getIntPtrType(), |
| GEP); |
| *i = Op; |
| MadeChange = true; |
| } |
| } |
| } |
| } |
| if (MadeChange) return &GEP; |
| |
| // Combine Indices - If the source pointer to this getelementptr instruction |
| // is a getelementptr instruction, combine the indices of the two |
| // getelementptr instructions into a single instruction. |
| // |
| SmallVector<Value*, 8> SrcGEPOperands; |
| if (User *Src = dyn_castGetElementPtr(PtrOp)) |
| SrcGEPOperands.append(Src->op_begin(), Src->op_end()); |
| |
| if (!SrcGEPOperands.empty()) { |
| // Note that if our source is a gep chain itself that we wait for that |
| // chain to be resolved before we perform this transformation. This |
| // avoids us creating a TON of code in some cases. |
| // |
| if (isa<GetElementPtrInst>(SrcGEPOperands[0]) && |
| cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2) |
| return 0; // Wait until our source is folded to completion. |
| |
| SmallVector<Value*, 8> Indices; |
| |
| // Find out whether the last index in the source GEP is a sequential idx. |
| bool EndsWithSequential = false; |
| for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)), |
| E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I) |
| EndsWithSequential = !isa<StructType>(*I); |
| |
| // Can we combine the two pointer arithmetics offsets? |
| if (EndsWithSequential) { |
| // Replace: gep (gep %P, long B), long A, ... |
| // With: T = long A+B; gep %P, T, ... |
| // |
| Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1); |
| if (SO1 == Constant::getNullValue(SO1->getType())) { |
| Sum = GO1; |
| } else if (GO1 == Constant::getNullValue(GO1->getType())) { |
| Sum = SO1; |
| } else { |
| // If they aren't the same type, convert both to an integer of the |
| // target's pointer size. |
| if (SO1->getType() != GO1->getType()) { |
| if (Constant *SO1C = dyn_cast<Constant>(SO1)) { |
| SO1 = ConstantExpr::getIntegerCast(SO1C, GO1->getType(), true); |
| } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) { |
| GO1 = ConstantExpr::getIntegerCast(GO1C, SO1->getType(), true); |
| } else { |
| unsigned PS = TD->getPointerSizeInBits(); |
| if (TD->getTypeSizeInBits(SO1->getType()) == PS) { |
| // Convert GO1 to SO1's type. |
| GO1 = InsertCastToIntPtrTy(GO1, SO1->getType(), &GEP, this); |
| |
| } else if (TD->getTypeSizeInBits(GO1->getType()) == PS) { |
| // Convert SO1 to GO1's type. |
| SO1 = InsertCastToIntPtrTy(SO1, GO1->getType(), &GEP, this); |
| } else { |
| const Type *PT = TD->getIntPtrType(); |
| SO1 = InsertCastToIntPtrTy(SO1, PT, &GEP, this); |
| GO1 = InsertCastToIntPtrTy(GO1, PT, &GEP, this); |
| } |
| } |
| } |
| if (isa<Constant>(SO1) && isa<Constant>(GO1)) |
| Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1)); |
| else { |
| Sum = BinaryOperator::CreateAdd(SO1, GO1, PtrOp->getName()+".sum"); |
| InsertNewInstBefore(cast<Instruction>(Sum), GEP); |
| } |
| } |
| |
| // Recycle the GEP we already have if possible. |
| if (SrcGEPOperands.size() == 2) { |
| GEP.setOperand(0, SrcGEPOperands[0]); |
| GEP.setOperand(1, Sum); |
| return &GEP; |
| } else { |
| Indices.insert(Indices.end(), SrcGEPOperands.begin()+1, |
| SrcGEPOperands.end()-1); |
| Indices.push_back(Sum); |
| Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end()); |
| } |
| } else if (isa<Constant>(*GEP.idx_begin()) && |
| cast<Constant>(*GEP.idx_begin())->isNullValue() && |
| SrcGEPOperands.size() != 1) { |
| // Otherwise we can do the fold if the first index of the GEP is a zero |
| Indices.insert(Indices.end(), SrcGEPOperands.begin()+1, |
| SrcGEPOperands.end()); |
| Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end()); |
| } |
| |
| if (!Indices.empty()) |
| return GetElementPtrInst::Create(SrcGEPOperands[0], Indices.begin(), |
| Indices.end(), GEP.getName()); |
| |
| } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) { |
| // GEP of global variable. If all of the indices for this GEP are |
| // constants, we can promote this to a constexpr instead of an instruction. |
| |
| // Scan for nonconstants... |
| SmallVector<Constant*, 8> Indices; |
| User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end(); |
| for (; I != E && isa<Constant>(*I); ++I) |
| Indices.push_back(cast<Constant>(*I)); |
| |
| if (I == E) { // If they are all constants... |
| Constant *CE = ConstantExpr::getGetElementPtr(GV, |
| &Indices[0],Indices.size()); |
| |
| // Replace all uses of the GEP with the new constexpr... |
| return ReplaceInstUsesWith(GEP, CE); |
| } |
| } else if (Value *X = getBitCastOperand(PtrOp)) { // Is the operand a cast? |
| if (!isa<PointerType>(X->getType())) { |
| // Not interesting. Source pointer must be a cast from pointer. |
| } else if (HasZeroPointerIndex) { |
| // transform: GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ... |
| // into : GEP [10 x i8]* X, i32 0, ... |
| // |
| // This occurs when the program declares an array extern like "int X[];" |
| // |
| const PointerType *CPTy = cast<PointerType>(PtrOp->getType()); |
| const PointerType *XTy = cast<PointerType>(X->getType()); |
| if (const ArrayType *XATy = |
| dyn_cast<ArrayType>(XTy->getElementType())) |
| if (const ArrayType *CATy = |
| dyn_cast<ArrayType>(CPTy->getElementType())) |
| if (CATy->getElementType() == XATy->getElementType()) { |
| // At this point, we know that the cast source type is a pointer |
| // to an array of the same type as the destination pointer |
| // array. Because the array type is never stepped over (there |
| // is a leading zero) we can fold the cast into this GEP. |
| GEP.setOperand(0, X); |
| return &GEP; |
| } |
| } else if (GEP.getNumOperands() == 2) { |
| // Transform things like: |
| // %t = getelementptr i32* bitcast ([2 x i32]* %str to i32*), i32 %V |
| // into: %t1 = getelementptr [2 x i32]* %str, i32 0, i32 %V; bitcast |
| const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType(); |
| const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType(); |
| if (isa<ArrayType>(SrcElTy) && |
| TD->getTypePaddedSize(cast<ArrayType>(SrcElTy)->getElementType()) == |
| TD->getTypePaddedSize(ResElTy)) { |
| Value *Idx[2]; |
| Idx[0] = Constant::getNullValue(Type::Int32Ty); |
| Idx[1] = GEP.getOperand(1); |
| Value *V = InsertNewInstBefore( |
| GetElementPtrInst::Create(X, Idx, Idx + 2, GEP.getName()), GEP); |
| // V and GEP are both pointer types --> BitCast |
| return new BitCastInst(V, GEP.getType()); |
| } |
| |
| // Transform things like: |
| // getelementptr i8* bitcast ([100 x double]* X to i8*), i32 %tmp |
| // (where tmp = 8*tmp2) into: |
| // getelementptr [100 x double]* %arr, i32 0, i32 %tmp2; bitcast |
| |
| if (isa<ArrayType>(SrcElTy) && ResElTy == Type::Int8Ty) { |
| uint64_t ArrayEltSize = |
| TD->getTypePaddedSize(cast<ArrayType>(SrcElTy)->getElementType()); |
| |
| // Check to see if "tmp" is a scale by a multiple of ArrayEltSize. We |
| // allow either a mul, shift, or constant here. |
| Value *NewIdx = 0; |
| ConstantInt *Scale = 0; |
| if (ArrayEltSize == 1) { |
| NewIdx = GEP.getOperand(1); |
| Scale = ConstantInt::get(NewIdx->getType(), 1); |
| } else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) { |
| NewIdx = ConstantInt::get(CI->getType(), 1); |
| Scale = CI; |
| } else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){ |
| if (Inst->getOpcode() == Instruction::Shl && |
| isa<ConstantInt>(Inst->getOperand(1))) { |
| ConstantInt *ShAmt = cast<ConstantInt>(Inst->getOperand(1)); |
| uint32_t ShAmtVal = ShAmt->getLimitedValue(64); |
| Scale = ConstantInt::get(Inst->getType(), 1ULL << ShAmtVal); |
| NewIdx = Inst->getOperand(0); |
| } else if (Inst->getOpcode() == Instruction::Mul && |
| isa<ConstantInt>(Inst->getOperand(1))) { |
| Scale = cast<ConstantInt>(Inst->getOperand(1)); |
| NewIdx = Inst->getOperand(0); |
| } |
| } |
| |
| // If the index will be to exactly the right offset with the scale taken |
| // out, perform the transformation. Note, we don't know whether Scale is |
| // signed or not. We'll use unsigned version of division/modulo |
| // operation after making sure Scale doesn't have the sign bit set. |
| if (Scale && Scale->getSExtValue() >= 0LL && |
| Scale->getZExtValue() % ArrayEltSize == 0) { |
| Scale = ConstantInt::get(Scale->getType(), |
| Scale->getZExtValue() / ArrayEltSize); |
| if (Scale->getZExtValue() != 1) { |
| Constant *C = ConstantExpr::getIntegerCast(Scale, NewIdx->getType(), |
| false /*ZExt*/); |
| Instruction *Sc = BinaryOperator::CreateMul(NewIdx, C, "idxscale"); |
| NewIdx = InsertNewInstBefore(Sc, GEP); |
| } |
| |
| // Insert the new GEP instruction. |
| Value *Idx[2]; |
| Idx[0] = Constant::getNullValue(Type::Int32Ty); |
| Idx[1] = NewIdx; |
| Instruction *NewGEP = |
| GetElementPtrInst::Create(X, Idx, Idx + 2, GEP.getName()); |
| NewGEP = InsertNewInstBefore(NewGEP, GEP); |
| // The NewGEP must be pointer typed, so must the old one -> BitCast |
| return new BitCastInst(NewGEP, GEP.getType()); |
| } |
| } |
| } |
| } |
| |
| /// See if we can simplify: |
| /// X = bitcast A to B* |
| /// Y = gep X, <...constant indices...> |
| /// into a gep of the original struct. This is important for SROA and alias |
| /// analysis of unions. If "A" is also a bitcast, wait for A/X to be merged. |
| if (BitCastInst *BCI = dyn_cast<BitCastInst>(PtrOp)) { |
| if (!isa<BitCastInst>(BCI->getOperand(0)) && GEP.hasAllConstantIndices()) { |
| // Determine how much the GEP moves the pointer. We are guaranteed to get |
| // a constant back from EmitGEPOffset. |
| ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(&GEP, GEP, *this)); |
| int64_t Offset = OffsetV->getSExtValue(); |
| |
| // If this GEP instruction doesn't move the pointer, just replace the GEP |
| // with a bitcast of the real input to the dest type. |
| if (Offset == 0) { |
| // If the bitcast is of an allocation, and the allocation will be |
| // converted to match the type of the cast, don't touch this. |
| if (isa<AllocationInst>(BCI->getOperand(0))) { |
| // See if the bitcast simplifies, if so, don't nuke this GEP yet. |
| if (Instruction *I = visitBitCast(*BCI)) { |
| if (I != BCI) { |
| I->takeName(BCI); |
| BCI->getParent()->getInstList().insert(BCI, I); |
| ReplaceInstUsesWith(*BCI, I); |
| } |
| return &GEP; |
| } |
| } |
| return new BitCastInst(BCI->getOperand(0), GEP.getType()); |
| } |
| |
| // Otherwise, if the offset is non-zero, we need to find out if there is a |
| // field at Offset in 'A's type. If so, we can pull the cast through the |
| // GEP. |
| SmallVector<Value*, 8> NewIndices; |
| const Type *InTy = |
| cast<PointerType>(BCI->getOperand(0)->getType())->getElementType(); |
| if (FindElementAtOffset(InTy, Offset, NewIndices, TD)) { |
| Instruction *NGEP = |
| GetElementPtrInst::Create(BCI->getOperand(0), NewIndices.begin(), |
| NewIndices.end()); |
| if (NGEP->getType() == GEP.getType()) return NGEP; |
| InsertNewInstBefore(NGEP, GEP); |
| NGEP->takeName(&GEP); |
| return new BitCastInst(NGEP, GEP.getType()); |
| } |
| } |
| } |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) { |
| // Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1 |
| if (AI.isArrayAllocation()) { // Check C != 1 |
| if (const ConstantInt *C = dyn_cast<ConstantInt>(AI.getArraySize())) { |
| const Type *NewTy = |
| ArrayType::get(AI.getAllocatedType(), C->getZExtValue()); |
| AllocationInst *New = 0; |
| |
| // Create and insert the replacement instruction... |
| if (isa<MallocInst>(AI)) |
| New = new MallocInst(NewTy, 0, AI.getAlignment(), AI.getName()); |
| else { |
| assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!"); |
| New = new AllocaInst(NewTy, 0, AI.getAlignment(), AI.getName()); |
| } |
| |
| InsertNewInstBefore(New, AI); |
| |
| // Scan to the end of the allocation instructions, to skip over a block of |
| // allocas if possible... |
| // |
| BasicBlock::iterator It = New; |
| while (isa<AllocationInst>(*It)) ++It; |
| |
| // Now that I is pointing to the first non-allocation-inst in the block, |
| // insert our getelementptr instruction... |
| // |
| Value *NullIdx = Constant::getNullValue(Type::Int32Ty); |
| Value *Idx[2]; |
| Idx[0] = NullIdx; |
| Idx[1] = NullIdx; |
| Value *V = GetElementPtrInst::Create(New, Idx, Idx + 2, |
| New->getName()+".sub", It); |
| |
| // Now make everything use the getelementptr instead of the original |
| // allocation. |
| return ReplaceInstUsesWith(AI, V); |
| } else if (isa<UndefValue>(AI.getArraySize())) { |
| return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType())); |
| } |
| } |
| |
| // If 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->getTypePaddedSize(AI.getAllocatedType()) == 0) |
| return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType())); |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitFreeInst(FreeInst &FI) { |
| Value *Op = FI.getOperand(0); |
| |
| // free undef -> unreachable. |
| if (isa<UndefValue>(Op)) { |
| // Insert a new store to null because we cannot modify the CFG here. |
| new StoreInst(ConstantInt::getTrue(), |
| UndefValue::get(PointerType::getUnqual(Type::Int1Ty)), &FI); |
| return EraseInstFromFunction(FI); |
| } |
| |
| // If we have 'free null' delete the instruction. This can happen in stl code |
| // when lots of inlining happens. |
| if (isa<ConstantPointerNull>(Op)) |
| return EraseInstFromFunction(FI); |
| |
| // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X |
| if (BitCastInst *CI = dyn_cast<BitCastInst>(Op)) { |
| FI.setOperand(0, CI->getOperand(0)); |
| return &FI; |
| } |
| |
| // Change free (gep X, 0,0,0,0) into free(X) |
| if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) { |
| if (GEPI->hasAllZeroIndices()) { |
| AddToWorkList(GEPI); |
| FI.setOperand(0, GEPI->getOperand(0)); |
| return &FI; |
| } |
| } |
| |
| // Change free(malloc) into nothing, if the malloc has a single use. |
| if (MallocInst *MI = dyn_cast<MallocInst>(Op)) |
| if (MI->hasOneUse()) { |
| EraseInstFromFunction(FI); |
| return EraseInstFromFunction(*MI); |
| } |
| |
| return 0; |
| } |
| |
| |
| /// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible. |
| static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI, |
| const TargetData *TD) { |
| User *CI = cast<User>(LI.getOperand(0)); |
| Value *CastOp = CI->getOperand(0); |
| |
| if (ConstantExpr *CE = dyn_cast<ConstantExpr>(CI)) { |
| // Instead of loading constant c string, use corresponding integer value |
| // directly if string length is small enough. |
| std::string Str; |
| if (GetConstantStringInfo(CE->getOperand(0), Str) && !Str.empty()) { |
| unsigned len = Str.length(); |
| const Type *Ty = cast<PointerType>(CE->getType())->getElementType(); |
| unsigned numBits = Ty->getPrimitiveSizeInBits(); |
| // Replace LI with immediate integer store. |
| if ((numBits >> 3) == len + 1) { |
| APInt StrVal(numBits, 0); |
| APInt SingleChar(numBits, 0); |
| if (TD->isLittleEndian()) { |
| for (signed i = len-1; i >= 0; i--) { |
| SingleChar = (uint64_t) Str[i]; |
| StrVal = (StrVal << 8) | SingleChar; |
| } |
| } else { |
| for (unsigned i = 0; i < len; i++) { |
| SingleChar = (uint64_t) Str[i]; |
| StrVal = (StrVal << 8) | SingleChar; |
| } |
| // Append NULL at the end. |
| SingleChar = 0; |
| StrVal = (StrVal << 8) | SingleChar; |
| } |
| Value *NL = ConstantInt::get(StrVal); |
| return IC.ReplaceInstUsesWith(LI, NL); |
| } |
| } |
| } |
| |
| const 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) || |
| isa<VectorType>(DestPTy)) { |
| // If the source is an array, the code below will not succeed. Check to |
| // see if a trivial 'gep P, 0, 0' will help matters. Only do this for |
| // constants. |
| if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy)) |
| if (Constant *CSrc = dyn_cast<Constant>(CastOp)) |
| if (ASrcTy->getNumElements() != 0) { |
| Value *Idxs[2]; |
| Idxs[0] = Idxs[1] = Constant::getNullValue(Type::Int32Ty); |
| CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs, 2); |
| SrcTy = cast<PointerType>(CastOp->getType()); |
| SrcPTy = SrcTy->getElementType(); |
| } |
| |
| if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy) || |
| isa<VectorType>(SrcPTy)) && |
| // Do not allow turning this into a load of an integer, which is then |
| // casted to a pointer, this pessimizes pointer analysis a lot. |
| (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) && |
| IC.getTargetData().getTypeSizeInBits(SrcPTy) == |
| IC.getTargetData().getTypeSizeInBits(DestPTy)) { |
| |
| // Okay, we are casting from one integer or pointer type to another of |
| // the same size. Instead of casting the pointer before the load, cast |
| // the result of the loaded value. |
| Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CastOp, |
| CI->getName(), |
| LI.isVolatile()),LI); |
| // Now cast the result of the load. |
| return new BitCastInst(NewLoad, LI.getType()); |
| } |
| } |
| } |
| return 0; |
| } |
| |
| /// isSafeToLoadUnconditionally - Return true if we know that executing a load |
| /// from this value cannot trap. If it is not obviously safe to load from the |
| /// specified pointer, we do a quick local scan of the basic block containing |
| /// ScanFrom, to determine if the address is already accessed. |
| static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) { |
| // If it is an alloca it is always safe to load from. |
| if (isa<AllocaInst>(V)) return true; |
| |
| // If it is a global variable it is mostly safe to load from. |
| if (const GlobalValue *GV = dyn_cast<GlobalVariable>(V)) |
| // Don't try to evaluate aliases. External weak GV can be null. |
| return !isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage(); |
| |
| // Otherwise, be a little bit agressive by scanning the local block where we |
| // want to check to see if the pointer is already being loaded or stored |
| // from/to. If so, the previous load or store would have already trapped, |
| // so there is no harm doing an extra load (also, CSE will later eliminate |
| // the load entirely). |
| BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin(); |
| |
| while (BBI != E) { |
| --BBI; |
| |
| // If we see a free or a call (which might do a free) the pointer could be |
| // marked invalid. |
| if (isa<FreeInst>(BBI) || isa<CallInst>(BBI)) |
| return false; |
| |
| if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) { |
| if (LI->getOperand(0) == V) return true; |
| } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) { |
| if (SI->getOperand(1) == V) return true; |
| } |
| |
| } |
| return false; |
| } |
| |
| Instruction *InstCombiner::visitLoadInst(LoadInst &LI) { |
| Value *Op = LI.getOperand(0); |
| |
| // Attempt to improve the alignment. |
| unsigned KnownAlign = GetOrEnforceKnownAlignment(Op); |
| if (KnownAlign > |
| (LI.getAlignment() == 0 ? TD->getABITypeAlignment(LI.getType()) : |
| LI.getAlignment())) |
| LI.setAlignment(KnownAlign); |
| |
| // load (cast X) --> cast (load X) iff safe |
| if (isa<CastInst>(Op)) |
| if (Instruction *Res = InstCombineLoadCast(*this, LI, TD)) |
| return Res; |
| |
| // None of the following transforms are legal for volatile loads. |
| if (LI.isVolatile()) return 0; |
| |
| // Do really simple store-to-load forwarding and load CSE, to catch cases |
| // where there are several consequtive memory accesses to the same location, |
| // separated by a few arithmetic operations. |
| BasicBlock::iterator BBI = &LI; |
| if (Value *AvailableVal = FindAvailableLoadedValue(Op, LI.getParent(), BBI,6)) |
| return ReplaceInstUsesWith(LI, AvailableVal); |
| |
| if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) { |
| const Value *GEPI0 = GEPI->getOperand(0); |
| // TODO: Consider a target hook for valid address spaces for this xform. |
| if (isa<ConstantPointerNull>(GEPI0) && |
| cast<PointerType>(GEPI0->getType())->getAddressSpace() == 0) { |
| // Insert a new store to null instruction before the load to indicate |
| // that this code is not reachable. We do this instead of inserting |
| // an unreachable instruction directly because we cannot modify the |
| // CFG. |
| new StoreInst(UndefValue::get(LI.getType()), |
| Constant::getNullValue(Op->getType()), &LI); |
| return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType())); |
| } |
| } |
| |
| if (Constant *C = dyn_cast<Constant>(Op)) { |
| // load null/undef -> undef |
| // TODO: Consider a target hook for valid address spaces for this xform. |
| if (isa<UndefValue>(C) || (C->isNullValue() && |
| cast<PointerType>(Op->getType())->getAddressSpace() == 0)) { |
| // Insert a new store to null instruction before the load to indicate that |
| // this code is not reachable. We do this instead of inserting an |
| // unreachable instruction directly because we cannot modify the CFG. |
| new StoreInst(UndefValue::get(LI.getType()), |
| Constant::getNullValue(Op->getType()), &LI); |
| return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType())); |
| } |
| |
| // Instcombine load (constant global) into the value loaded. |
| if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op)) |
| if (GV->isConstant() && !GV->isDeclaration()) |
| return ReplaceInstUsesWith(LI, GV->getInitializer()); |
| |
| // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded. |
| if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op)) { |
| if (CE->getOpcode() == Instruction::GetElementPtr) { |
| if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0))) |
| if (GV->isConstant() && !GV->isDeclaration()) |
| if (Constant *V = |
| ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE)) |
| return ReplaceInstUsesWith(LI, V); |
| if (CE->getOperand(0)->isNullValue()) { |
| // Insert a new store to null instruction before the load to indicate |
| // that this code is not reachable. We do this instead of inserting |
| // an unreachable instruction directly because we cannot modify the |
| // CFG. |
| new StoreInst(UndefValue::get(LI.getType()), |
| Constant::getNullValue(Op->getType()), &LI); |
| return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType())); |
| } |
| |
| } else if (CE->isCast()) { |
| if (Instruction *Res = InstCombineLoadCast(*this, LI, TD)) |
| return Res; |
| } |
| } |
| } |
| |
| // If this load comes from anywhere in a constant global, and if the global |
| // is all undef or zero, we know what it loads. |
| if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op->getUnderlyingObject())){ |
| if (GV->isConstant() && GV->hasInitializer()) { |
| if (GV->getInitializer()->isNullValue()) |
| return ReplaceInstUsesWith(LI, Constant::getNullValue(LI.getType())); |
| else if (isa<UndefValue>(GV->getInitializer())) |
| return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType())); |
| } |
| } |
| |
| if (Op->hasOneUse()) { |
| // Change select and PHI nodes to select values instead of addresses: this |
| // helps alias analysis out a lot, allows many others simplifications, and |
| // exposes redundancy in the code. |
| // |
| // Note that we cannot do the transformation unless we know that the |
| // introduced loads cannot trap! Something like this is valid as long as |
| // the condition is always false: load (select bool %C, int* null, int* %G), |
| // but it would not be valid if we transformed it to load from null |
| // unconditionally. |
| // |
| if (SelectInst *SI = dyn_cast<SelectInst>(Op)) { |
| // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2). |
| if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) && |
| isSafeToLoadUnconditionally(SI->getOperand(2), SI)) { |
| Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1), |
| SI->getOperand(1)->getName()+".val"), LI); |
| Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2), |
| SI->getOperand(2)->getName()+".val"), LI); |
| return SelectInst::Create(SI->getCondition(), V1, V2); |
| } |
| |
| // load (select (cond, null, P)) -> load P |
| if (Constant *C = dyn_cast<Constant>(SI->getOperand(1))) |
| if (C->isNullValue()) { |
| LI.setOperand(0, SI->getOperand(2)); |
| return &LI; |
| } |
| |
| // load (select (cond, P, null)) -> load P |
| if (Constant *C = dyn_cast<Constant>(SI->getOperand(2))) |
| if (C->isNullValue()) { |
| LI.setOperand(0, SI->getOperand(1)); |
| return &LI; |
| } |
| } |
| } |
| return 0; |
| } |
| |
| /// InstCombineStoreToCast - Fold store V, (cast P) -> store (cast V), P |
| /// when possible. |
| 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) { |
| Value* Idxs[2]; |
| Idxs[0] = Idxs[1] = Constant::getNullValue(Type::Int32Ty); |
| CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs, 2); |
| SrcTy = cast<PointerType>(CastOp->getType()); |
| SrcPTy = SrcTy->getElementType(); |
| } |
| |
| if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) && |
| IC.getTargetData().getTypeSizeInBits(SrcPTy) == |
| IC.getTargetData().getTypeSizeInBits(DestPTy)) { |
| |
| // Okay, we are casting from one integer or pointer type to another of |
| // the same size. Instead of casting the pointer before |
| // the store, cast the value to be stored. |
| Value *NewCast; |
| Value *SIOp0 = SI.getOperand(0); |
| Instruction::CastOps opcode = Instruction::BitCast; |
| const Type* CastSrcTy = SIOp0->getType(); |
| const Type* CastDstTy = SrcPTy; |
| if (isa<PointerType>(CastDstTy)) { |
| if (CastSrcTy->isInteger()) |
| opcode = Instruction::IntToPtr; |
| } else if (isa<IntegerType>(CastDstTy)) { |
| if (isa<PointerType>(SIOp0->getType())) |
| opcode = Instruction::PtrToInt; |
| } |
| if (Constant *C = dyn_cast<Constant>(SIOp0)) |
| NewCast = ConstantExpr::getCast(opcode, C, CastDstTy); |
| else |
| NewCast = IC.InsertNewInstBefore( |
| CastInst::Create(opcode, SIOp0, CastDstTy, SIOp0->getName()+".c"), |
| SI); |
| return new StoreInst(NewCast, CastOp); |
| } |
| } |
| } |
| return 0; |
| } |
| |
| /// equivalentAddressValues - Test if A and B will obviously have the same |
| /// value. This includes recognizing that %t0 and %t1 will have the same |
| /// value in code like this: |
| /// %t0 = getelementptr @a, 0, 3 |
| /// store i32 0, i32* %t0 |
| /// %t1 = getelementptr @a, 0, 3 |
| /// %t2 = load i32* %t1 |
| /// |
| static bool equivalentAddressValues(Value *A, Value *B) { |
| // Test if the values are trivially equivalent. |
| if (A == B) return true; |
| |
| // Test if the values come form identical arithmetic instructions. |
| if (isa<BinaryOperator>(A) || |
| isa<CastInst>(A) || |
| isa<PHINode>(A) || |
| isa<GetElementPtrInst>(A)) |
| if (Instruction *BI = dyn_cast<Instruction>(B)) |
| if (cast<Instruction>(A)->isIdenticalTo(BI)) |
| return true; |
| |
| // Otherwise they may not be equivalent. |
| return false; |
| } |
| |
| Instruction *InstCombiner::visitStoreInst(StoreInst &SI) { |
| Value *Val = SI.getOperand(0); |
| Value *Ptr = SI.getOperand(1); |
| |
| if (isa<UndefValue>(Ptr)) { // store X, undef -> noop (even if volatile) |
| EraseInstFromFunction(SI); |
| ++NumCombined; |
| return 0; |
| } |
| |
| // If the RHS is an alloca with a single use, zapify the store, making the |
| // alloca dead. |
| if (Ptr->hasOneUse() && !SI.isVolatile()) { |
| if (isa<AllocaInst>(Ptr)) { |
| EraseInstFromFunction(SI); |
| ++NumCombined; |
| return 0; |
| } |
| |
| if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr)) |
| if (isa<AllocaInst>(GEP->getOperand(0)) && |
| GEP->getOperand(0)->hasOneUse()) { |
| EraseInstFromFunction(SI); |
| ++NumCombined; |
| return 0; |
| } |
| } |
| |
| // Attempt to improve the alignment. |
| unsigned KnownAlign = GetOrEnforceKnownAlignment(Ptr); |
| if (KnownAlign > |
| (SI.getAlignment() == 0 ? TD->getABITypeAlignment(Val->getType()) : |
| SI.getAlignment())) |
| SI.setAlignment(KnownAlign); |
| |
| // Do really simple DSE, to catch cases where there are several consequtive |
| // stores to the same location, separated by a few arithmetic operations. This |
| // situation often occurs with bitfield accesses. |
| BasicBlock::iterator BBI = &SI; |
| for (unsigned ScanInsts = 6; BBI != SI.getParent()->begin() && ScanInsts; |
| --ScanInsts) { |
| --BBI; |
| |
| if (StoreInst *PrevSI = dyn_cast<StoreInst>(BBI)) { |
| // Prev store isn't volatile, and stores to the same location? |
| if (!PrevSI->isVolatile() &&equivalentAddressValues(PrevSI->getOperand(1), |
| SI.getOperand(1))) { |
| ++NumDeadStore; |
| ++BBI; |
| EraseInstFromFunction(*PrevSI); |
| continue; |
| } |
| break; |
| } |
| |
| // If this is a load, we have to stop. However, if the loaded value is from |
| // the pointer we're loading and is producing the pointer we're storing, |
| // then *this* store is dead (X = load P; store X -> P). |
| if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) { |
| if (LI == Val && equivalentAddressValues(LI->getOperand(0), Ptr) && |
| !SI.isVolatile()) { |
| EraseInstFromFunction(SI); |
| ++NumCombined; |
| return 0; |
| } |
| // Otherwise, this is a load from some other location. Stores before it |
| // may not be dead. |
| break; |
| } |
| |
| // Don't skip over loads or things that can modify memory. |
| if (BBI->mayWriteToMemory() || BBI->mayReadFromMemory()) |
| break; |
| } |
| |
| |
| if (SI.isVolatile()) return 0; // Don't hack volatile stores. |
| |
| // store X, null -> turns into 'unreachable' in SimplifyCFG |
| if (isa<ConstantPointerNull>(Ptr)) { |
| if (!isa<UndefValue>(Val)) { |
| SI.setOperand(0, UndefValue::get(Val->getType())); |
| if (Instruction *U = dyn_cast<Instruction>(Val)) |
| AddToWorkList(U); // Dropped a use. |
| ++NumCombined; |
| } |
| return 0; // Do not modify these! |
| } |
| |
| // store undef, Ptr -> noop |
| if (isa<UndefValue>(Val)) { |
| EraseInstFromFunction(SI); |
| ++NumCombined; |
| return 0; |
| } |
| |
| // If the pointer destination is a cast, see if we can fold the cast into the |
| // source instead. |
| if (isa<CastInst>(Ptr)) |
| if (Instruction *Res = InstCombineStoreToCast(*this, SI)) |
| return Res; |
| if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr)) |
| if (CE->isCast()) |
| if (Instruction *Res = InstCombineStoreToCast(*this, SI)) |
| return Res; |
| |
| |
| // If this store is the last instruction in the basic block, and if the block |
| // ends with an unconditional branch, try to move it to the successor block. |
| BBI = &SI; ++BBI; |
| if (BranchInst *BI = dyn_cast<BranchInst>(BBI)) |
| if (BI->isUnconditional()) |
| if (SimplifyStoreAtEndOfBlock(SI)) |
| return 0; // xform done! |
| |
| return 0; |
| } |
| |
| /// SimplifyStoreAtEndOfBlock - Turn things like: |
| /// if () { *P = v1; } else { *P = v2 } |
| /// into a phi node with a store in the successor. |
| /// |
| /// Simplify things like: |
| /// *P = v1; if () { *P = v2; } |
| /// into a phi node with a store in the successor. |
| /// |
| bool InstCombiner::SimplifyStoreAtEndOfBlock(StoreInst &SI) { |
| BasicBlock *StoreBB = SI.getParent(); |
| |
| // Check to see if the successor block has exactly two incoming edges. If |
| // so, see if the other predecessor contains a store to the same location. |
| // if so, insert a PHI node (if needed) and move the stores down. |
| BasicBlock *DestBB = StoreBB->getTerminator()->getSuccessor(0); |
| |
| // Determine whether Dest has exactly two predecessors and, if so, compute |
| // the other predecessor. |
| pred_iterator PI = pred_begin(DestBB); |
| BasicBlock *OtherBB = 0; |
| if (*PI != StoreBB) |
| OtherBB = *PI; |
| ++PI; |
| if (PI == pred_end(DestBB)) |
| return false; |
| |
| if (*PI != StoreBB) { |
| if (OtherBB) |
| return false; |
| OtherBB = *PI; |
| } |
| if (++PI != pred_end(DestBB)) |
| return false; |
| |
| // Bail out if all the relevant blocks aren't distinct (this can happen, |
| // for example, if SI is in an infinite loop) |
| if (StoreBB == DestBB || OtherBB == DestBB) |
| return false; |
| |
| // Verify that the other block ends in a branch and is not otherwise empty. |
| BasicBlock::iterator BBI = OtherBB->getTerminator(); |
| BranchInst *OtherBr = dyn_cast<BranchInst>(BBI); |
| if (!OtherBr || BBI == OtherBB->begin()) |
| return false; |
| |
| // If the other block ends in an unconditional branch, check for the 'if then |
| // else' case. there is an instruction before the branch. |
| StoreInst *OtherStore = 0; |
| if (OtherBr->isUnconditional()) { |
| // If this isn't a store, or isn't a store to the same location, bail out. |
| --BBI; |
| OtherStore = dyn_cast<StoreInst>(BBI); |
| if (!OtherStore || OtherStore->getOperand(1) != SI.getOperand(1)) |
| return false; |
| } else { |
| // Otherwise, the other block ended with a conditional branch. If one of the |
| // destinations is StoreBB, then we have the if/then case. |
| if (OtherBr->getSuccessor(0) != StoreBB && |
| OtherBr->getSuccessor(1) != StoreBB) |
| return false; |
| |
| // Okay, we know that OtherBr now goes to Dest and StoreBB, so this is an |
| // if/then triangle. See if there is a store to the same ptr as SI that |
| // lives in OtherBB. |
| for (;; --BBI) { |
| // Check to see if we find the matching store. |
| if ((OtherStore = dyn_cast<StoreInst>(BBI))) { |
| if (OtherStore->getOperand(1) != SI.getOperand(1)) |
| return false; |
| break; |
| } |
| // If we find something that may be using or overwriting the stored |
| // value, or if we run out of instructions, we can't do the xform. |
| if (BBI->mayReadFromMemory() || BBI->mayWriteToMemory() || |
| BBI == OtherBB->begin()) |
| return false; |
| } |
| |
| // In order to eliminate the store in OtherBr, we have to |
| // make sure nothing reads or overwrites the stored value in |
| // StoreBB. |
| for (BasicBlock::iterator I = StoreBB->begin(); &*I != &SI; ++I) { |
| // FIXME: This should really be AA driven. |
| if (I->mayReadFromMemory() || I->mayWriteToMemory()) |
| return false; |
| } |
| } |
| |
| // Insert a PHI node now if we need it. |
| Value *MergedVal = OtherStore->getOperand(0); |
| if (MergedVal != SI.getOperand(0)) { |
| PHINode *PN = PHINode::Create(MergedVal->getType(), "storemerge"); |
| PN->reserveOperandSpace(2); |
| PN->addIncoming(SI.getOperand(0), SI.getParent()); |
| PN->addIncoming(OtherStore->getOperand(0), OtherBB); |
| MergedVal = InsertNewInstBefore(PN, DestBB->front()); |
| } |
| |
| // Advance to a place where it is safe to insert the new store and |
| // insert it. |
| BBI = DestBB->getFirstNonPHI(); |
| InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1), |
| OtherStore->isVolatile()), *BBI); |
| |
| // Nuke the old stores. |
| EraseInstFromFunction(SI); |
| EraseInstFromFunction(*OtherStore); |
| ++NumCombined; |
| return true; |
| } |
| |
| |
| Instruction *InstCombiner::visitBranchInst(BranchInst &BI) { |
| // Change br (not X), label True, label False to: br X, label False, True |
| Value *X = 0; |
| BasicBlock *TrueDest; |
| BasicBlock *FalseDest; |
| if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) && |
| !isa<Constant>(X)) { |
| // Swap Destinations and condition... |
| BI.setCondition(X); |
| BI.setSuccessor(0, FalseDest); |
| BI.setSuccessor(1, TrueDest); |
| return &BI; |
| } |
| |
| // Cannonicalize fcmp_one -> fcmp_oeq |
| FCmpInst::Predicate FPred; Value *Y; |
| if (match(&BI, m_Br(m_FCmp(FPred, m_Value(X), m_Value(Y)), |
| TrueDest, FalseDest))) |
| if ((FPred == FCmpInst::FCMP_ONE || FPred == FCmpInst::FCMP_OLE || |
| FPred == FCmpInst::FCMP_OGE) && BI.getCondition()->hasOneUse()) { |
| FCmpInst *I = cast<FCmpInst>(BI.getCondition()); |
| FCmpInst::Predicate NewPred = FCmpInst::getInversePredicate(FPred); |
| Instruction *NewSCC = new FCmpInst(NewPred, X, Y, "", I); |
| NewSCC->takeName(I); |
| // Swap Destinations and condition... |
| BI.setCondition(NewSCC); |
| BI.setSuccessor(0, FalseDest); |
| BI.setSuccessor(1, TrueDest); |
| RemoveFromWorkList(I); |
| I->eraseFromParent(); |
| AddToWorkList(NewSCC); |
| return &BI; |
| } |
| |
| // Cannonicalize icmp_ne -> icmp_eq |
| ICmpInst::Predicate IPred; |
| if (match(&BI, m_Br(m_ICmp(IPred, m_Value(X), m_Value(Y)), |
| TrueDest, FalseDest))) |
| if ((IPred == ICmpInst::ICMP_NE || IPred == ICmpInst::ICMP_ULE || |
| IPred == ICmpInst::ICMP_SLE || IPred == ICmpInst::ICMP_UGE || |
| IPred == ICmpInst::ICMP_SGE) && BI.getCondition()->hasOneUse()) { |
| ICmpInst *I = cast<ICmpInst>(BI.getCondition()); |
| ICmpInst::Predicate NewPred = ICmpInst::getInversePredicate(IPred); |
| Instruction *NewSCC = new ICmpInst(NewPred, X, Y, "", I); |
| NewSCC->takeName(I); |
| // Swap Destinations and condition... |
| BI.setCondition(NewSCC); |
| BI.setSuccessor(0, FalseDest); |
| BI.setSuccessor(1, TrueDest); |
| RemoveFromWorkList(I); |
| I->eraseFromParent();; |
| AddToWorkList(NewSCC); |
| return &BI; |
| } |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) { |
| Value *Cond = SI.getCondition(); |
| if (Instruction *I = dyn_cast<Instruction>(Cond)) { |
| if (I->getOpcode() == Instruction::Add) |
| if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| // change 'switch (X+4) case 1:' into 'switch (X) case -3' |
| for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2) |
| SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)), |
| AddRHS)); |
| SI.setOperand(0, I->getOperand(0)); |
| AddToWorkList(I); |
| return &SI; |
| } |
| } |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitExtractValueInst(ExtractValueInst &EV) { |
| Value *Agg = EV.getAggregateOperand(); |
| |
| if (!EV.hasIndices()) |
| return ReplaceInstUsesWith(EV, Agg); |
| |
| if (Constant *C = dyn_cast<Constant>(Agg)) { |
| if (isa<UndefValue>(C)) |
| return ReplaceInstUsesWith(EV, UndefValue::get(EV.getType())); |
| |
| if (isa<ConstantAggregateZero>(C)) |
| return ReplaceInstUsesWith(EV, Constant::getNullValue(EV.getType())); |
| |
| if (isa<ConstantArray>(C) || isa<ConstantStruct>(C)) { |
| // Extract the element indexed by the first index out of the constant |
| Value *V = C->getOperand(*EV.idx_begin()); |
| if (EV.getNumIndices() > 1) |
| // Extract the remaining indices out of the constant indexed by the |
| // first index |
| return ExtractValueInst::Create(V, EV.idx_begin() + 1, EV.idx_end()); |
| else |
| return ReplaceInstUsesWith(EV, V); |
| } |
| return 0; // Can't handle other constants |
| } |
| if (InsertValueInst *IV = dyn_cast<InsertValueInst>(Agg)) { |
| // We're extracting from an insertvalue instruction, compare the indices |
| const unsigned *exti, *exte, *insi, *inse; |
| for (exti = EV.idx_begin(), insi = IV->idx_begin(), |
| exte = EV.idx_end(), inse = IV->idx_end(); |
| exti != exte && insi != inse; |
| ++exti, ++insi) { |
| if (*insi != *exti) |
| // The insert and extract both reference distinctly different elements. |
| // This means the extract is not influenced by the insert, and we can |
| // replace the aggregate operand of the extract with the aggregate |
| // operand of the insert. i.e., replace |
| // %I = insertvalue { i32, { i32 } } %A, { i32 } { i32 42 }, 1 |
| // %E = extractvalue { i32, { i32 } } %I, 0 |
| // with |
| // %E = extractvalue { i32, { i32 } } %A, 0 |
| return ExtractValueInst::Create(IV->getAggregateOperand(), |
| EV.idx_begin(), EV.idx_end()); |
| } |
| if (exti == exte && insi == inse) |
| // Both iterators are at the end: Index lists are identical. Replace |
| // %B = insertvalue { i32, { i32 } } %A, i32 42, 1, 0 |
| // %C = extractvalue { i32, { i32 } } %B, 1, 0 |
| // with "i32 42" |
| return ReplaceInstUsesWith(EV, IV->getInsertedValueOperand()); |
| if (exti == exte) { |
| // The extract list is a prefix of the insert list. i.e. replace |
| // %I = insertvalue { i32, { i32 } } %A, i32 42, 1, 0 |
| // %E = extractvalue { i32, { i32 } } %I, 1 |
| // with |
| // %X = extractvalue { i32, { i32 } } %A, 1 |
| // %E = insertvalue { i32 } %X, i32 42, 0 |
| // by switching the order of the insert and extract (though the |
| // insertvalue should be left in, since it may have other uses). |
| Value *NewEV = InsertNewInstBefore( |
| ExtractValueInst::Create(IV->getAggregateOperand(), |
| EV.idx_begin(), EV.idx_end()), |
| EV); |
| return InsertValueInst::Create(NewEV, IV->getInsertedValueOperand(), |
| insi, inse); |
| } |
| if (insi == inse) |
| // The insert list is a prefix of the extract list |
| // We can simply remove the common indices from the extract and make it |
| // operate on the inserted value instead of the insertvalue result. |
| // i.e., replace |
| // %I = insertvalue { i32, { i32 } } %A, { i32 } { i32 42 }, 1 |
| // %E = extractvalue { i32, { i32 } } %I, 1, 0 |
| // with |
| // %E extractvalue { i32 } { i32 42 }, 0 |
| return ExtractValueInst::Create(IV->getInsertedValueOperand(), |
| exti, exte); |
| } |
| // Can't simplify extracts from other values. Note that nested extracts are |
| // already simplified implicitely by the above (extract ( extract (insert) ) |
| // will be translated into extract ( insert ( extract ) ) first and then just |
| // the value inserted, if appropriate). |
| return 0; |
| } |
| |
| /// CheapToScalarize - Return true if the value is cheaper to scalarize than it |
| /// is to leave as a vector operation. |
| static bool CheapToScalarize(Value *V, bool isConstant) { |
| if (isa<ConstantAggregateZero>(V)) |
| return true; |
| if (ConstantVector *C = dyn_cast<ConstantVector>(V)) { |
| if (isConstant) return true; |
| // If all elts are the same, we can extract. |
| Constant *Op0 = C->getOperand(0); |
| for (unsigned i = 1; i < C->getNumOperands(); ++i) |
| if (C->getOperand(i) != Op0) |
| return false; |
| return true; |
| } |
| Instruction *I = dyn_cast<Instruction>(V); |
| if (!I) return false; |
| |
| // Insert element gets simplified to the inserted element or is deleted if |
| // this is constant idx extract element and its a constant idx insertelt. |
| if (I->getOpcode() == Instruction::InsertElement && isConstant && |
| isa<ConstantInt>(I->getOperand(2))) |
| return true; |
| if (I->getOpcode() == Instruction::Load && I->hasOneUse()) |
| return true; |
| if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) |
| if (BO->hasOneUse() && |
| (CheapToScalarize(BO->getOperand(0), isConstant) || |
| CheapToScalarize(BO->getOperand(1), isConstant))) |
| return true; |
| if (CmpInst *CI = dyn_cast<CmpInst>(I)) |
| if (CI->hasOneUse() && |
| (CheapToScalarize(CI->getOperand(0), isConstant) || |
| CheapToScalarize(CI->getOperand(1), isConstant))) |
| return true; |
| |
| return false; |
| } |
| |
| /// Read and decode a shufflevector mask. |
| /// |
| /// It turns undef elements into values that are larger than the number of |
| /// elements in the input. |
| static std::vector<unsigned> getShuffleMask(const ShuffleVectorInst *SVI) { |
| unsigned NElts = SVI->getType()->getNumElements(); |
| if (isa<ConstantAggregateZero>(SVI->getOperand(2))) |
| return std::vector<unsigned>(NElts, 0); |
| if (isa<UndefValue>(SVI->getOperand(2))) |
| return std::vector<unsigned>(NElts, 2*NElts); |
| |
| std::vector<unsigned> Result; |
| const ConstantVector *CP = cast<ConstantVector>(SVI->getOperand(2)); |
| for (User::const_op_iterator i = CP->op_begin(), e = CP->op_end(); i!=e; ++i) |
| if (isa<UndefValue>(*i)) |
| Result.push_back(NElts*2); // undef -> 8 |
| else |
| Result.push_back(cast<ConstantInt>(*i)->getZExtValue()); |
| return Result; |
| } |
| |
| /// FindScalarElement - Given a vector and an element number, see if the scalar |
| /// value is already around as a register, for example if it were inserted then |
| /// extracted from the vector. |
| static Value *FindScalarElement(Value *V, unsigned EltNo) { |
| assert(isa<VectorType>(V->getType()) && "Not looking at a vector?"); |
| const VectorType *PTy = cast<VectorType>(V->getType()); |
| unsigned Width = PTy->getNumElements(); |
| if (EltNo >= Width) // Out of range access. |
| return UndefValue::get(PTy->getElementType()); |
| |
| if (isa<UndefValue>(V)) |
| return UndefValue::get(PTy->getElementType()); |
| else if (isa<ConstantAggregateZero>(V)) |
| return Constant::getNullValue(PTy->getElementType()); |
| else if (ConstantVector *CP = dyn_cast<ConstantVector>(V)) |
| return CP->getOperand(EltNo); |
| else if (InsertElementInst *III = dyn_cast<InsertElementInst>(V)) { |
| // If this is an insert to a variable element, we don't know what it is. |
| if (!isa<ConstantInt>(III->getOperand(2))) |
| return 0; |
| unsigned IIElt = cast<ConstantInt>(III->getOperand(2))->getZExtValue(); |
| |
| // If this is an insert to the element we are looking for, return the |
| // inserted value. |
| if (EltNo == IIElt) |
| return III->getOperand(1); |
| |
| // Otherwise, the insertelement doesn't modify the value, recurse on its |
| // vector input. |
| return FindScalarElement(III->getOperand(0), EltNo); |
| } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(V)) { |
| unsigned LHSWidth = |
| cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements(); |
| unsigned InEl = getShuffleMask(SVI)[EltNo]; |
| if (InEl < LHSWidth) |
| return FindScalarElement(SVI->getOperand(0), InEl); |
| else if (InEl < LHSWidth*2) |
| return FindScalarElement(SVI->getOperand(1), InEl - LHSWidth); |
| else |
| return UndefValue::get(PTy->getElementType()); |
| } |
| |
| // Otherwise, we don't know. |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) { |
| // If vector val is undef, replace extract with scalar undef. |
| if (isa<UndefValue>(EI.getOperand(0))) |
| return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType())); |
| |
| // If vector val is constant 0, replace extract with scalar 0. |
| if (isa<ConstantAggregateZero>(EI.getOperand(0))) |
| return ReplaceInstUsesWith(EI, Constant::getNullValue(EI.getType())); |
| |
| if (ConstantVector *C = dyn_cast<ConstantVector>(EI.getOperand(0))) { |
| // If vector val is constant with all elements the same, replace EI with |
| // that element. When the elements are not identical, we cannot replace yet |
| // (we do that below, but only when the index is constant). |
| Constant *op0 = C->getOperand(0); |
| for (unsigned i = 1; i < C->getNumOperands(); ++i) |
| if (C->getOperand(i) != op0) { |
| op0 = 0; |
| break; |
| } |
| if (op0) |
| return ReplaceInstUsesWith(EI, op0); |
| } |
| |
| // If extracting a specified index from the vector, see if we can recursively |
| // find a previously computed scalar that was inserted into the vector. |
| if (ConstantInt *IdxC = dyn_cast<ConstantInt>(EI.getOperand(1))) { |
| unsigned IndexVal = IdxC->getZExtValue(); |
| unsigned VectorWidth = |
| cast<VectorType>(EI.getOperand(0)->getType())->getNumElements(); |
| |
| // If this is extracting an invalid index, turn this into undef, to avoid |
| // crashing the code below. |
| if (IndexVal >= VectorWidth) |
| return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType())); |
| |
| // This instruction only demands the single element from the input vector. |
| // If the input vector has a single use, simplify it based on this use |
| // property. |
| if (EI.getOperand(0)->hasOneUse() && VectorWidth != 1) { |
| uint64_t UndefElts; |
| if (Value *V = SimplifyDemandedVectorElts(EI.getOperand(0), |
| 1 << IndexVal, |
| UndefElts)) { |
| EI.setOperand(0, V); |
| return &EI; |
| } |
| } |
| |
| if (Value *Elt = FindScalarElement(EI.getOperand(0), IndexVal)) |
| return ReplaceInstUsesWith(EI, Elt); |
| |
| // If the this extractelement is directly using a bitcast from a vector of |
| // the same number of elements, see if we can find the source element from |
| // it. In this case, we will end up needing to bitcast the scalars. |
| if (BitCastInst *BCI = dyn_cast<BitCastInst>(EI.getOperand(0))) { |
| if (const VectorType *VT = |
| dyn_cast<VectorType>(BCI->getOperand(0)->getType())) |
| if (VT->getNumElements() == VectorWidth) |
| if (Value *Elt = FindScalarElement(BCI->getOperand(0), IndexVal)) |
| return new BitCastInst(Elt, EI.getType()); |
| } |
| } |
| |
| if (Instruction *I = dyn_cast<Instruction>(EI.getOperand(0))) { |
| if (I->hasOneUse()) { |
| // Push extractelement into predecessor operation if legal and |
| // profitable to do so |
| if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) { |
| bool isConstantElt = isa<ConstantInt>(EI.getOperand(1)); |
| if (CheapToScalarize(BO, isConstantElt)) { |
| ExtractElementInst *newEI0 = |
| new ExtractElementInst(BO->getOperand(0), EI.getOperand(1), |
| EI.getName()+".lhs"); |
| ExtractElementInst *newEI1 = |
| new ExtractElementInst(BO->getOperand(1), EI.getOperand(1), |
| EI.getName()+".rhs"); |
| InsertNewInstBefore(newEI0, EI); |
| InsertNewInstBefore(newEI1, EI); |
| return BinaryOperator::Create(BO->getOpcode(), newEI0, newEI1); |
| } |
| } else if (isa<LoadInst>(I)) { |
| unsigned AS = |
| cast<PointerType>(I->getOperand(0)->getType())->getAddressSpace(); |
| Value *Ptr = InsertBitCastBefore(I->getOperand(0), |
| PointerType::get(EI.getType(), AS),EI); |
| GetElementPtrInst *GEP = |
| GetElementPtrInst::Create(Ptr, EI.getOperand(1), I->getName()+".gep"); |
| InsertNewInstBefore(GEP, EI); |
| return new LoadInst(GEP); |
| } |
| } |
| if (InsertElementInst *IE = dyn_cast<InsertElementInst>(I)) { |
| // Extracting the inserted element? |
| if (IE->getOperand(2) == EI.getOperand(1)) |
| return ReplaceInstUsesWith(EI, IE->getOperand(1)); |
| // If the inserted and extracted elements are constants, they must not |
| // be the same value, extract from the pre-inserted value instead. |
| if (isa<Constant>(IE->getOperand(2)) && |
| isa<Constant>(EI.getOperand(1))) { |
| AddUsesToWorkList(EI); |
| EI.setOperand(0, IE->getOperand(0)); |
| return &EI; |
| } |
| } else if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I)) { |
| // If this is extracting an element from a shufflevector, figure out where |
| // it came from and extract from the appropriate input element instead. |
| if (ConstantInt *Elt = dyn_cast<ConstantInt>(EI.getOperand(1))) { |
| unsigned SrcIdx = getShuffleMask(SVI)[Elt->getZExtValue()]; |
| Value *Src; |
| unsigned LHSWidth = |
| cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements(); |
| |
| if (SrcIdx < LHSWidth) |
| Src = SVI->getOperand(0); |
| else if (SrcIdx < LHSWidth*2) { |
| SrcIdx -= LHSWidth; |
| Src = SVI->getOperand(1); |
| } else { |
| return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType())); |
| } |
| return new ExtractElementInst(Src, SrcIdx); |
| } |
| } |
| } |
| return 0; |
| } |
| |
| /// CollectSingleShuffleElements - If V is a shuffle of values that ONLY returns |
| /// elements from either LHS or RHS, return the shuffle mask and true. |
| /// Otherwise, return false. |
| static bool CollectSingleShuffleElements(Value *V, Value *LHS, Value *RHS, |
| std::vector<Constant*> &Mask) { |
| assert(V->getType() == LHS->getType() && V->getType() == RHS->getType() && |
| "Invalid CollectSingleShuffleElements"); |
| unsigned NumElts = cast<VectorType>(V->getType())->getNumElements(); |
| |
| if (isa<UndefValue>(V)) { |
| Mask.assign(NumElts, UndefValue::get(Type::Int32Ty)); |
| return true; |
| } else if (V == LHS) { |
| for (unsigned i = 0; i != NumElts; ++i) |
| Mask.push_back(ConstantInt::get(Type::Int32Ty, i)); |
| return true; |
| } else if (V == RHS) { |
| for (unsigned i = 0; i != NumElts; ++i) |
| Mask.push_back(ConstantInt::get(Type::Int32Ty, i+NumElts)); |
| return true; |
| } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) { |
| // If this is an insert of an extract from some other vector, include it. |
| Value *VecOp = IEI->getOperand(0); |
| Value *ScalarOp = IEI->getOperand(1); |
| Value *IdxOp = IEI->getOperand(2); |
| |
| if (!isa<ConstantInt>(IdxOp)) |
| return false; |
| unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue(); |
| |
| if (isa<UndefValue>(ScalarOp)) { // inserting undef into vector. |
| // Okay, we can handle this if the vector we are insertinting into is |
| // transitively ok. |
| if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) { |
| // If so, update the mask to reflect the inserted undef. |
| Mask[InsertedIdx] = UndefValue::get(Type::Int32Ty); |
| return true; |
| } |
| } else if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)){ |
| if (isa<ConstantInt>(EI->getOperand(1)) && |
| EI->getOperand(0)->getType() == V->getType()) { |
| unsigned ExtractedIdx = |
| cast<ConstantInt>(EI->getOperand(1))->getZExtValue(); |
| |
| // This must be extracting from either LHS or RHS. |
| if (EI->getOperand(0) == LHS || EI->getOperand(0) == RHS) { |
| // Okay, we can handle this if the vector we are insertinting into is |
| // transitively ok. |
| if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) { |
| // If so, update the mask to reflect the inserted value. |
| if (EI->getOperand(0) == LHS) { |
| Mask[InsertedIdx % NumElts] = |
| ConstantInt::get(Type::Int32Ty, ExtractedIdx); |
| } else { |
| assert(EI->getOperand(0) == RHS); |
| Mask[InsertedIdx % NumElts] = |
| ConstantInt::get(Type::Int32Ty, ExtractedIdx+NumElts); |
| |
| } |
| return true; |
| } |
| } |
| } |
| } |
| } |
| // TODO: Handle shufflevector here! |
| |
| return false; |
| } |
| |
| /// CollectShuffleElements - We are building a shuffle of V, using RHS as the |
| /// RHS of the shuffle instruction, if it is not null. Return a shuffle mask |
| /// that computes V and the LHS value of the shuffle. |
| static Value *CollectShuffleElements(Value *V, std::vector<Constant*> &Mask, |
| Value *&RHS) { |
| assert(isa<VectorType>(V->getType()) && |
| (RHS == 0 || V->getType() == RHS->getType()) && |
| "Invalid shuffle!"); |
| unsigned NumElts = cast<VectorType>(V->getType())->getNumElements(); |
| |
| if (isa<UndefValue>(V)) { |
| Mask.assign(NumElts, UndefValue::get(Type::Int32Ty)); |
| return V; |
| } else if (isa<ConstantAggregateZero>(V)) { |
| Mask.assign(NumElts, ConstantInt::get(Type::Int32Ty, 0)); |
| return V; |
| } else if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) { |
| // If this is an insert of an extract from some other vector, include it. |
| Value *VecOp = IEI->getOperand(0); |
| Value *ScalarOp = IEI->getOperand(1); |
| Value *IdxOp = IEI->getOperand(2); |
| |
| if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) { |
| if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) && |
| EI->getOperand(0)->getType() == V->getType()) { |
| unsigned ExtractedIdx = |
| cast<ConstantInt>(EI->getOperand(1))->getZExtValue(); |
| unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue(); |
| |
| // Either the extracted from or inserted into vector must be RHSVec, |
| // otherwise we'd end up with a shuffle of three inputs. |
| if (EI->getOperand(0) == RHS || RHS == 0) { |
| RHS = EI->getOperand(0); |
| Value *V = CollectShuffleElements(VecOp, Mask, RHS); |
| Mask[InsertedIdx % NumElts] = |
| ConstantInt::get(Type::Int32Ty, NumElts+ExtractedIdx); |
| return V; |
| } |
| |
| if (VecOp == RHS) { |
| Value *V = CollectShuffleElements(EI->getOperand(0), Mask, RHS); |
| // Everything but the extracted element is replaced with the RHS. |
| for (unsigned i = 0; i != NumElts; ++i) { |
| if (i != InsertedIdx) |
| Mask[i] = ConstantInt::get(Type::Int32Ty, NumElts+i); |
| } |
| return V; |
| } |
| |
| // If this insertelement is a chain that comes from exactly these two |
| // vectors, return the vector and the effective shuffle. |
| if (CollectSingleShuffleElements(IEI, EI->getOperand(0), RHS, Mask)) |
| return EI->getOperand(0); |
| |
| } |
| } |
| } |
| // TODO: Handle shufflevector here! |
| |
| // Otherwise, can't do anything fancy. Return an identity vector. |
| for (unsigned i = 0; i != NumElts; ++i) |
| Mask.push_back(ConstantInt::get(Type::Int32Ty, i)); |
| return V; |
| } |
| |
| Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) { |
| Value *VecOp = IE.getOperand(0); |
| Value *ScalarOp = IE.getOperand(1); |
| Value *IdxOp = IE.getOperand(2); |
| |
| // Inserting an undef or into an undefined place, remove this. |
| if (isa<UndefValue>(ScalarOp) || isa<UndefValue>(IdxOp)) |
| ReplaceInstUsesWith(IE, VecOp); |
| |
| // If the inserted element was extracted from some other vector, and if the |
| // indexes are constant, try to turn this into a shufflevector operation. |
| if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) { |
| if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) && |
| EI->getOperand(0)->getType() == IE.getType()) { |
| unsigned NumVectorElts = IE.getType()->getNumElements(); |
| unsigned ExtractedIdx = |
| cast<ConstantInt>(EI->getOperand(1))->getZExtValue(); |
| unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue(); |
| |
| if (ExtractedIdx >= NumVectorElts) // Out of range extract. |
| return ReplaceInstUsesWith(IE, VecOp); |
| |
| if (InsertedIdx >= NumVectorElts) // Out of range insert. |
| return ReplaceInstUsesWith(IE, UndefValue::get(IE.getType())); |
| |
| // If we are extracting a value from a vector, then inserting it right |
| // back into the same place, just use the input vector. |
| if (EI->getOperand(0) == VecOp && ExtractedIdx == InsertedIdx) |
| return ReplaceInstUsesWith(IE, VecOp); |
| |
| // We could theoretically do this for ANY input. However, doing so could |
| // turn chains of insertelement instructions into a chain of shufflevector |
| // instructions, and right now we do not merge shufflevectors. As such, |
| // only do this in a situation where it is clear that there is benefit. |
| if (isa<UndefValue>(VecOp) || isa<ConstantAggregateZero>(VecOp)) { |
| // Turn this into shuffle(EIOp0, VecOp, Mask). The result has all of |
| // the values of VecOp, except then one read from EIOp0. |
| // Build a new shuffle mask. |
| std::vector<Constant*> Mask; |
| if (isa<UndefValue>(VecOp)) |
| Mask.assign(NumVectorElts, UndefValue::get(Type::Int32Ty)); |
| else { |
| assert(isa<ConstantAggregateZero>(VecOp) && "Unknown thing"); |
| Mask.assign(NumVectorElts, ConstantInt::get(Type::Int32Ty, |
| NumVectorElts)); |
| } |
| Mask[InsertedIdx] = ConstantInt::get(Type::Int32Ty, ExtractedIdx); |
| return new ShuffleVectorInst(EI->getOperand(0), VecOp, |
| ConstantVector::get(Mask)); |
| } |
| |
| // If this insertelement isn't used by some other insertelement, turn it |
| // (and any insertelements it points to), into one big shuffle. |
| if (!IE.hasOneUse() || !isa<InsertElementInst>(IE.use_back())) { |
| std::vector<Constant*> Mask; |
| Value *RHS = 0; |
| Value *LHS = CollectShuffleElements(&IE, Mask, RHS); |
| if (RHS == 0) RHS = UndefValue::get(LHS->getType()); |
| // We now have a shuffle of LHS, RHS, Mask. |
| return new ShuffleVectorInst(LHS, RHS, ConstantVector::get(Mask)); |
| } |
| } |
| } |
| |
| return 0; |
| } |
| |
| |
| Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) { |
| Value *LHS = SVI.getOperand(0); |
| Value *RHS = SVI.getOperand(1); |
| std::vector<unsigned> Mask = getShuffleMask(&SVI); |
| |
| bool MadeChange = false; |
| |
| // Undefined shuffle mask -> undefined value. |
| if (isa<UndefValue>(SVI.getOperand(2))) |
| return ReplaceInstUsesWith(SVI, UndefValue::get(SVI.getType())); |
| |
| uint64_t UndefElts; |
| unsigned VWidth = cast<VectorType>(SVI.getType())->getNumElements(); |
| |
| if (VWidth != cast<VectorType>(LHS->getType())->getNumElements()) |
| return 0; |
| |
| uint64_t AllOnesEltMask = ~0ULL >> (64-VWidth); |
| if (VWidth <= 64 && |
| SimplifyDemandedVectorElts(&SVI, AllOnesEltMask, UndefElts)) { |
| LHS = SVI.getOperand(0); |
| RHS = SVI.getOperand(1); |
| MadeChange = true; |
| } |
| |
| // Canonicalize shuffle(x ,x,mask) -> shuffle(x, undef,mask') |
| // Canonicalize shuffle(undef,x,mask) -> shuffle(x, undef,mask'). |
| if (LHS == RHS || isa<UndefValue>(LHS)) { |
| if (isa<UndefValue>(LHS) && LHS == RHS) { |
| // shuffle(undef,undef,mask) -> undef. |
| return ReplaceInstUsesWith(SVI, LHS); |
| } |
| |
| // Remap any references to RHS to use LHS. |
| std::vector<Constant*> Elts; |
| for (unsigned i = 0, e = Mask.size(); i != e; ++i) { |
| if (Mask[i] >= 2*e) |
| Elts.push_back(UndefValue::get(Type::Int32Ty)); |
| else { |
| if ((Mask[i] >= e && isa<UndefValue>(RHS)) || |
| (Mask[i] < e && isa<UndefValue>(LHS))) { |
| Mask[i] = 2*e; // Turn into undef. |
| Elts.push_back(UndefValue::get(Type::Int32Ty)); |
| } else { |
| Mask[i] = Mask[i] % e; // Force to LHS. |
| Elts.push_back(ConstantInt::get(Type::Int32Ty, Mask[i])); |
| } |
| } |
| } |
| SVI.setOperand(0, SVI.getOperand(1)); |
| SVI.setOperand(1, UndefValue::get(RHS->getType())); |
| SVI.setOperand(2, ConstantVector::get(Elts)); |
| LHS = SVI.getOperand(0); |
| RHS = SVI.getOperand(1); |
| MadeChange = true; |
| } |
| |
| // Analyze the shuffle, are the LHS or RHS and identity shuffles? |
| bool isLHSID = true, isRHSID = true; |
| |
| for (unsigned i = 0, e = Mask.size(); i != e; ++i) { |
| if (Mask[i] >= e*2) continue; // Ignore undef values. |
| // Is this an identity shuffle of the LHS value? |
| isLHSID &= (Mask[i] == i); |
| |
| // Is this an identity shuffle of the RHS value? |
| isRHSID &= (Mask[i]-e == i); |
| } |
| |
| // Eliminate identity shuffles. |
| if (isLHSID) return ReplaceInstUsesWith(SVI, LHS); |
| if (isRHSID) return ReplaceInstUsesWith(SVI, RHS); |
| |
| // If the LHS is a shufflevector itself, see if we can combine it with this |
| // one without producing an unusual shuffle. Here we are really conservative: |
| // we are absolutely afraid of producing a shuffle mask not in the input |
| // program, because the code gen may not be smart enough to turn a merged |
| // shuffle into two specific shuffles: it may produce worse code. As such, |
| // we only merge two shuffles if the result is one of the two input shuffle |
| // masks. In this case, merging the shuffles just removes one instruction, |
| // which we know is safe. This is good for things like turning: |
| // (splat(splat)) -> splat. |
| if (ShuffleVectorInst *LHSSVI = dyn_cast<ShuffleVectorInst>(LHS)) { |
| if (isa<UndefValue>(RHS)) { |
| std::vector<unsigned> LHSMask = getShuffleMask(LHSSVI); |
| |
| std::vector<unsigned> NewMask; |
| for (unsigned i = 0, e = Mask.size(); i != e; ++i) |
| if (Mask[i] >= 2*e) |
| NewMask.push_back(2*e); |
| else |
| NewMask.push_back(LHSMask[Mask[i]]); |
| |
| // If the result mask is equal to the src shuffle or this shuffle mask, do |
| // the replacement. |
| if (NewMask == LHSMask || NewMask == Mask) { |
| std::vector<Constant*> Elts; |
| for (unsigned i = 0, e = NewMask.size(); i != e; ++i) { |
| if (NewMask[i] >= e*2) { |
| Elts.push_back(UndefValue::get(Type::Int32Ty)); |
| } else { |
| Elts.push_back(ConstantInt::get(Type::Int32Ty, NewMask[i])); |
| } |
| } |
| return new ShuffleVectorInst(LHSSVI->getOperand(0), |
| LHSSVI->getOperand(1), |
| ConstantVector::get(Elts)); |
| } |
| } |
| } |
| |
| return MadeChange ? &SVI : 0; |
| } |
| |
| |
| |
| |
| /// TryToSinkInstruction - Try to move the specified instruction from its |
| /// current block into the beginning of DestBlock, which can only happen if it's |
| /// safe to move the instruction past all of the instructions between it and the |
| /// end of its block. |
| static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) { |
| assert(I->hasOneUse() && "Invariants didn't hold!"); |
| |
| // Cannot move control-flow-involving, volatile loads, vaarg, etc. |
| if (isa<PHINode>(I) || I->mayWriteToMemory() || isa<TerminatorInst>(I)) |
| return false; |
| |
| // Do not sink alloca instructions out of the entry block. |
| if (isa<AllocaInst>(I) && I->getParent() == |
| &DestBlock->getParent()->getEntryBlock()) |
| return false; |
| |
| // We can only sink load instructions if there is nothing between the load and |
| // the end of block that could change the value. |
| if (I->mayReadFromMemory()) { |
| for (BasicBlock::iterator Scan = I, E = I->getParent()->end(); |
| Scan != E; ++Scan) |
| if (Scan->mayWriteToMemory()) |
| return false; |
| } |
| |
| BasicBlock::iterator InsertPos = DestBlock->getFirstNonPHI(); |
| |
| I->moveBefore(InsertPos); |
| ++NumSunkInst; |
| return true; |
| } |
| |
| |
| /// AddReachableCodeToWorklist - Walk the function in depth-first order, adding |
| /// all reachable code to the worklist. |
| /// |
| /// This has a couple of tricks to make the code faster and more powerful. In |
| /// particular, we constant fold and DCE instructions as we go, to avoid adding |
| /// them to the worklist (this significantly speeds up instcombine on code where |
| /// many instructions are dead or constant). Additionally, if we find a branch |
| /// whose condition is a known constant, we only visit the reachable successors. |
| /// |
| static void AddReachableCodeToWorklist(BasicBlock *BB, |
| SmallPtrSet<BasicBlock*, 64> &Visited, |
| InstCombiner &IC, |
| const TargetData *TD) { |
| SmallVector<BasicBlock*, 256> Worklist; |
| Worklist.push_back(BB); |
| |
| while (!Worklist.empty()) { |
| BB = Worklist.back(); |
| Worklist.pop_back(); |
| |
| // We have now visited this block! If we've already been here, ignore it. |
| if (!Visited.insert(BB)) continue; |
| |
| DbgInfoIntrinsic *DBI_Prev = NULL; |
| for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) { |
| Instruction *Inst = BBI++; |
| |
| // DCE instruction if trivially dead. |
| if (isInstructionTriviallyDead(Inst)) { |
| ++NumDeadInst; |
| DOUT << "IC: DCE: " << *Inst; |
| Inst->eraseFromParent(); |
| continue; |
| } |
| |
| // ConstantProp instruction if trivially constant. |
| if (Constant *C = ConstantFoldInstruction(Inst, TD)) { |
| DOUT << "IC: ConstFold to: " << *C << " from: " << *Inst; |
| Inst->replaceAllUsesWith(C); |
| ++NumConstProp; |
| Inst->eraseFromParent(); |
| continue; |
| } |
| |
| // If there are two consecutive llvm.dbg.stoppoint calls then |
| // it is likely that the optimizer deleted code in between these |
| // two intrinsics. |
| DbgInfoIntrinsic *DBI_Next = dyn_cast<DbgInfoIntrinsic>(Inst); |
| if (DBI_Next) { |
| if (DBI_Prev |
| && DBI_Prev->getIntrinsicID() == llvm::Intrinsic::dbg_stoppoint |
| && DBI_Next->getIntrinsicID() == llvm::Intrinsic::dbg_stoppoint) { |
| IC.RemoveFromWorkList(DBI_Prev); |
| DBI_Prev->eraseFromParent(); |
| } |
| DBI_Prev = DBI_Next; |
| } |
| |
| IC.AddToWorkList(Inst); |
| } |
| |
| // Recursively visit successors. If this is a branch or switch on a |
| // constant, only visit the reachable successor. |
| TerminatorInst *TI = BB->getTerminator(); |
| if (BranchInst *BI = dyn_cast<BranchInst>(TI)) { |
| if (BI->isConditional() && isa<ConstantInt>(BI->getCondition())) { |
| bool CondVal = cast<ConstantInt>(BI->getCondition())->getZExtValue(); |
| BasicBlock *ReachableBB = BI->getSuccessor(!CondVal); |
| Worklist.push_back(ReachableBB); |
| continue; |
| } |
| } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) { |
| if (ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition())) { |
| // See if this is an explicit destination. |
| for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i) |
| if (SI->getCaseValue(i) == Cond) { |
| BasicBlock *ReachableBB = SI->getSuccessor(i); |
| Worklist.push_back(ReachableBB); |
| continue; |
| } |
| |
| // Otherwise it is the default destination. |
| Worklist.push_back(SI->getSuccessor(0)); |
| continue; |
| } |
| } |
| |
| for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) |
| Worklist.push_back(TI->getSuccessor(i)); |
| } |
| } |
| |
| bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) { |
| bool Changed = false; |
| TD = &getAnalysis<TargetData>(); |
| |
| DEBUG(DOUT << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on " |
| << F.getNameStr() << "\n"); |
| |
| { |
| // Do a depth-first traversal of the function, populate the worklist with |
| // the reachable instructions. Ignore blocks that are not reachable. Keep |
| // track of which blocks we visit. |
| SmallPtrSet<BasicBlock*, 64> Visited; |
| AddReachableCodeToWorklist(F.begin(), Visited, *this, TD); |
| |
| // Do a quick scan over the function. If we find any blocks that are |
| // unreachable, remove any instructions inside of them. This prevents |
| // the instcombine code from having to deal with some bad special cases. |
| for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) |
| if (!Visited.count(BB)) { |
| Instruction *Term = BB->getTerminator(); |
| while (Term != BB->begin()) { // Remove instrs bottom-up |
| BasicBlock::iterator I = Term; --I; |
| |
| DOUT << "IC: DCE: " << *I; |
| ++NumDeadInst; |
| |
| if (!I->use_empty()) |
| I->replaceAllUsesWith(UndefValue::get(I->getType())); |
| I->eraseFromParent(); |
| } |
| } |
| } |
| |
| while (!Worklist.empty()) { |
| Instruction *I = RemoveOneFromWorkList(); |
| if (I == 0) continue; // skip null values. |
| |
| // Check to see if we can DCE the instruction. |
| if (isInstructionTriviallyDead(I)) { |
| // Add operands to the worklist. |
| if (I->getNumOperands() < 4) |
| AddUsesToWorkList(*I); |
| ++NumDeadInst; |
| |
| DOUT << "IC: DCE: " << *I; |
| |
| I->eraseFromParent(); |
| RemoveFromWorkList(I); |
| continue; |
| } |
| |
| // Instruction isn't dead, see if we can constant propagate it. |
| if (Constant *C = ConstantFoldInstruction(I, TD)) { |
| DOUT << "IC: ConstFold to: " << *C << " from: " << *I; |
| |
| // Add operands to the worklist. |
| AddUsesToWorkList(*I); |
| ReplaceInstUsesWith(*I, C); |
| |
| ++NumConstProp; |
| I->eraseFromParent(); |
| RemoveFromWorkList(I); |
| continue; |
| } |
| |
| if (TD && I->getType()->getTypeID() == Type::VoidTyID) { |
| // See if we can constant fold its operands. |
| for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i) { |
| if (ConstantExpr *CE = dyn_cast<ConstantExpr>(i)) { |
| if (Constant *NewC = ConstantFoldConstantExpression(CE, TD)) |
| i->set(NewC); |
| } |
| } |
| } |
| |
| // See if we can trivially sink this instruction to a successor basic block. |
| if (I->hasOneUse()) { |
| BasicBlock *BB = I->getParent(); |
| BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent(); |
| if (UserParent != BB) { |
| bool UserIsSuccessor = false; |
| // See if the user is one of our successors. |
| for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI) |
| if (*SI == UserParent) { |
| UserIsSuccessor = true; |
| break; |
| } |
| |
| // If the user is one of our immediate successors, and if that successor |
| // only has us as a predecessors (we'd have to split the critical edge |
| // otherwise), we can keep going. |
| if (UserIsSuccessor && !isa<PHINode>(I->use_back()) && |
| next(pred_begin(UserParent)) == pred_end(UserParent)) |
| // Okay, the CFG is simple enough, try to sink this instruction. |
| Changed |= TryToSinkInstruction(I, UserParent); |
| } |
| } |
| |
| // Now that we have an instruction, try combining it to simplify it... |
| #ifndef NDEBUG |
| std::string OrigI; |
| #endif |
| DEBUG(std::ostringstream SS; I->print(SS); OrigI = SS.str();); |
| if (Instruction *Result = visit(*I)) { |
| ++NumCombined; |
| // Should we replace the old instruction with a new one? |
| if (Result != I) { |
| DOUT << "IC: Old = " << *I |
| << " New = " << *Result; |
| |
| // Everything uses the new instruction now. |
| I->replaceAllUsesWith(Result); |
| |
| // Push the new instruction and any users onto the worklist. |
| AddToWorkList(Result); |
| AddUsersToWorkList(*Result); |
| |
| // Move the name to the new instruction first. |
| Result->takeName(I); |
| |
| // Insert the new instruction into the basic block... |
| BasicBlock *InstParent = I->getParent(); |
| BasicBlock::iterator InsertPos = I; |
| |
| if (!isa<PHINode>(Result)) // If combining a PHI, don't insert |
| while (isa<PHINode>(InsertPos)) // middle of a block of PHIs. |
| ++InsertPos; |
| |
| InstParent->getInstList().insert(InsertPos, Result); |
| |
| // Make sure that we reprocess all operands now that we reduced their |
| // use counts. |
| AddUsesToWorkList(*I); |
| |
| // Instructions can end up on the worklist more than once. Make sure |
| // we do not process an instruction that has been deleted. |
| RemoveFromWorkList(I); |
| |
| // Erase the old instruction. |
| InstParent->getInstList().erase(I); |
| } else { |
| #ifndef NDEBUG |
| DOUT << "IC: Mod = " << OrigI |
| << " New = " << *I; |
| #endif |
| |
| // If the instruction was modified, it's possible that it is now dead. |
| // if so, remove it. |
| if (isInstructionTriviallyDead(I)) { |
| // Make sure we process all operands now that we are reducing their |
| // use counts. |
| AddUsesToWorkList(*I); |
| |
| // Instructions may end up in the worklist more than once. Erase all |
| // occurrences of this instruction. |
| RemoveFromWorkList(I); |
| I->eraseFromParent(); |
| } else { |
| AddToWorkList(I); |
| AddUsersToWorkList(*I); |
| } |
| } |
| Changed = true; |
| } |
| } |
| |
| assert(WorklistMap.empty() && "Worklist empty, but map not?"); |
| |
| // Do an explicit clear, this shrinks the map if needed. |
| WorklistMap.clear(); |
| return Changed; |
| } |
| |
| |
| bool InstCombiner::runOnFunction(Function &F) { |
| MustPreserveLCSSA = mustPreserveAnalysisID(LCSSAID); |
| |
| bool EverMadeChange = false; |
| |
| // Iterate while there is work to do. |
| unsigned Iteration = 0; |
| while (DoOneIteration(F, Iteration++)) |
| EverMadeChange = true; |
| return EverMadeChange; |
| } |
| |
| FunctionPass *llvm::createInstructionCombiningPass() { |
| return new InstCombiner(); |
| } |
| |
| |