| //===- InstructionCombining.cpp - Combine multiple instructions -----------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file was developed by the LLVM research group and 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 int %X, 1 |
| // %Z = add int %Y, 1 |
| // into: |
| // %Z = add int %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. SetCC instructions are converted from <,>,<=,>= to ==,!= if possible |
| // 4. All SetCC 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/Target/TargetData.h" |
| #include "llvm/Transforms/Utils/BasicBlockUtils.h" |
| #include "llvm/Transforms/Utils/Local.h" |
| #include "llvm/Support/CallSite.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/Statistic.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include <algorithm> |
| using namespace llvm; |
| using namespace llvm::PatternMatch; |
| |
| namespace { |
| Statistic<> NumCombined ("instcombine", "Number of insts combined"); |
| Statistic<> NumConstProp("instcombine", "Number of constant folds"); |
| Statistic<> NumDeadInst ("instcombine", "Number of dead inst eliminated"); |
| Statistic<> NumDeadStore("instcombine", "Number of dead stores eliminated"); |
| Statistic<> NumSunkInst ("instcombine", "Number of instructions sunk"); |
| |
| class VISIBILITY_HIDDEN InstCombiner |
| : public FunctionPass, |
| public InstVisitor<InstCombiner, Instruction*> { |
| // Worklist of all of the instructions that need to be simplified. |
| std::vector<Instruction*> WorkList; |
| TargetData *TD; |
| |
| /// 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) |
| WorkList.push_back(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 (unsigned i = 0, e = I.getNumOperands(); i != e; ++i) |
| if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i))) |
| WorkList.push_back(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 (unsigned i = 0, e = I.getNumOperands(); i != e; ++i) |
| if (Instruction *Op = dyn_cast<Instruction>(I.getOperand(i))) { |
| WorkList.push_back(Op); |
| // Set the operand to undef to drop the use. |
| I.setOperand(i, UndefValue::get(Op->getType())); |
| } |
| |
| return R; |
| } |
| |
| // removeFromWorkList - remove all instances of I from the worklist. |
| void removeFromWorkList(Instruction *I); |
| public: |
| virtual bool runOnFunction(Function &F); |
| |
| 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); |
| 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 *visitAnd(BinaryOperator &I); |
| Instruction *visitOr (BinaryOperator &I); |
| Instruction *visitXor(BinaryOperator &I); |
| Instruction *visitSetCondInst(SetCondInst &I); |
| Instruction *visitSetCondInstWithCastAndCast(SetCondInst &SCI); |
| |
| Instruction *FoldGEPSetCC(User *GEPLHS, Value *RHS, |
| Instruction::BinaryOps Cond, Instruction &I); |
| Instruction *visitShiftInst(ShiftInst &I); |
| Instruction *FoldShiftByConstant(Value *Op0, ConstantInt *Op1, |
| ShiftInst &I); |
| Instruction *commonCastTransforms(CastInst &CI); |
| Instruction *commonIntCastTransforms(CastInst &CI); |
| Instruction *visitTrunc(CastInst &CI); |
| Instruction *visitZExt(CastInst &CI); |
| Instruction *visitSExt(CastInst &CI); |
| Instruction *visitFPTrunc(CastInst &CI); |
| Instruction *visitFPExt(CastInst &CI); |
| Instruction *visitFPToUI(CastInst &CI); |
| Instruction *visitFPToSI(CastInst &CI); |
| Instruction *visitUIToFP(CastInst &CI); |
| Instruction *visitSIToFP(CastInst &CI); |
| Instruction *visitPtrToInt(CastInst &CI); |
| Instruction *visitIntToPtr(CastInst &CI); |
| Instruction *visitBitCast(CastInst &CI); |
| Instruction *FoldSelectOpOp(SelectInst &SI, Instruction *TI, |
| Instruction *FI); |
| Instruction *visitSelectInst(SelectInst &CI); |
| 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); |
| |
| // visitInstruction - Specify what to return for unhandled instructions... |
| Instruction *visitInstruction(Instruction &I) { return 0; } |
| |
| private: |
| Instruction *visitCallSite(CallSite CS); |
| bool transformConstExprCastCall(CallSite CS); |
| |
| 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 |
| WorkList.push_back(New); // Add to worklist |
| 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(Value *V, const Type *Ty, Instruction &Pos) { |
| if (V->getType() == Ty) return V; |
| |
| if (Constant *CV = dyn_cast<Constant>(V)) |
| return ConstantExpr::getCast(CV, Ty); |
| |
| Instruction *C = CastInst::createInferredCast(V, Ty, V->getName(), &Pos); |
| WorkList.push_back(C); |
| return C; |
| } |
| |
| // 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)) |
| WorkList.push_back(I); |
| if (Instruction *I = dyn_cast<Instruction>(New)) |
| WorkList.push_back(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 |
| } |
| |
| private: |
| /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the |
| /// InsertBefore instruction. This is specialized a bit to avoid inserting |
| /// casts that are known to not do anything... |
| /// |
| Value *InsertOperandCastBefore(Value *V, const Type *DestTy, |
| Instruction *InsertBefore); |
| |
| // SimplifyCommutative - This performs a few simplifications for commutative |
| // operators. |
| bool SimplifyCommutative(BinaryOperator &I); |
| |
| bool SimplifyDemandedBits(Value *V, uint64_t Mask, |
| uint64_t &KnownZero, uint64_t &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 *OptAndOp(Instruction *Op, ConstantIntegral *OpRHS, |
| ConstantIntegral *AndRHS, BinaryOperator &TheAnd); |
| |
| Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantIntegral *Mask, |
| bool isSub, Instruction &I); |
| Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi, |
| bool Inside, Instruction &IB); |
| Instruction *PromoteCastOfAllocation(CastInst &CI, AllocationInst &AI); |
| Instruction *MatchBSwap(BinaryOperator &I); |
| |
| Value *EvaluateInDifferentType(Value *V, const Type *Ty); |
| }; |
| |
| 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) { |
| switch (Ty->getTypeID()) { |
| case Type::SByteTyID: |
| case Type::ShortTyID: return Type::IntTy; |
| case Type::UByteTyID: |
| case Type::UShortTyID: return Type::UIntTy; |
| case Type::FloatTyID: return Type::DoubleTy; |
| default: return Ty; |
| } |
| } |
| |
| /// getBitCastOperand - If the specified operand is a CastInst or a constant |
| /// expression bitcast, return the operand value, otherwise return null. |
| static Value *getBitCastOperand(Value *V) { |
| if (BitCastInst *I = dyn_cast<BitCastInst>(V)) |
| return I->getOperand(0); |
| else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) |
| if (CE->getOpcode() == Instruction::BitCast) |
| return CE->getOperand(0); |
| return 0; |
| } |
| |
| /// This function is a wrapper around CastInst::isEliminableCastPair. It |
| /// simply extracts arguments and returns what that function returns. |
| /// @Determine if it is valid to eliminate a Convert pair |
| 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(const Value *V, const Type *Ty, TargetData *TD) { |
| if (V->getType() == Ty || isa<Constant>(V)) return false; |
| |
| // If this is a noop cast, it isn't real codegen. |
| if (V->getType()->canLosslesslyBitCastTo(Ty)) |
| 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, CastInst::getCastOpcode(V, Ty), Ty, TD)) |
| return false; |
| return true; |
| } |
| |
| /// InsertOperandCastBefore - This inserts a cast of V to DestTy before the |
| /// InsertBefore instruction. This is specialized a bit to avoid inserting |
| /// casts that are known to not do anything... |
| /// |
| Value *InstCombiner::InsertOperandCastBefore(Value *V, const Type *DestTy, |
| Instruction *InsertBefore) { |
| if (V->getType() == DestTy) return V; |
| if (Constant *C = dyn_cast<Constant>(V)) |
| return ConstantExpr::getCast(C, DestTy); |
| |
| return InsertCastBefore(V, DestTy, *InsertBefore); |
| } |
| |
| // 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); |
| WorkList.push_back(New); |
| I.setOperand(0, New); |
| I.setOperand(1, Folded); |
| return true; |
| } |
| } |
| return Changed; |
| } |
| |
| // 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); |
| 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 (ConstantIntegral *C = dyn_cast<ConstantIntegral>(V)) |
| return ConstantExpr::getNot(C); |
| 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. |
| Constant *One = ConstantInt::get(V->getType(), 1); |
| CST = cast<ConstantInt>(ConstantExpr::getShl(One, CST)); |
| 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; |
| } |
| |
| // AddOne, SubOne - Add or subtract a constant one from an integer constant... |
| static ConstantInt *AddOne(ConstantInt *C) { |
| return cast<ConstantInt>(ConstantExpr::getAdd(C, |
| ConstantInt::get(C->getType(), 1))); |
| } |
| static ConstantInt *SubOne(ConstantInt *C) { |
| return cast<ConstantInt>(ConstantExpr::getSub(C, |
| ConstantInt::get(C->getType(), 1))); |
| } |
| |
| /// GetConstantInType - Return a ConstantInt with the specified type and value. |
| /// |
| static ConstantIntegral *GetConstantInType(const Type *Ty, uint64_t Val) { |
| if (Ty->isUnsigned()) |
| return ConstantInt::get(Ty, Val); |
| else if (Ty->getTypeID() == Type::BoolTyID) |
| return ConstantBool::get(Val); |
| int64_t SVal = Val; |
| SVal <<= 64-Ty->getPrimitiveSizeInBits(); |
| SVal >>= 64-Ty->getPrimitiveSizeInBits(); |
| return ConstantInt::get(Ty, SVal); |
| } |
| |
| |
| /// ComputeMaskedBits - Determine which of the bits specified in Mask are |
| /// known to be either zero or one and return them in the KnownZero/KnownOne |
| /// bitsets. This code only analyzes bits in Mask, in order to short-circuit |
| /// processing. |
| static void ComputeMaskedBits(Value *V, uint64_t Mask, uint64_t &KnownZero, |
| uint64_t &KnownOne, unsigned Depth = 0) { |
| // Note, we cannot consider 'undef' to be "IsZero" here. The problem is that |
| // we cannot optimize based on the assumption that it is zero without changing |
| // it to be an explicit zero. If we don't change it to zero, other code could |
| // optimized based on the contradictory assumption that it is non-zero. |
| // Because instcombine aggressively folds operations with undef args anyway, |
| // this won't lose us code quality. |
| if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V)) { |
| // We know all of the bits for a constant! |
| KnownOne = CI->getZExtValue() & Mask; |
| KnownZero = ~KnownOne & Mask; |
| return; |
| } |
| |
| KnownZero = KnownOne = 0; // Don't know anything. |
| if (Depth == 6 || Mask == 0) |
| return; // Limit search depth. |
| |
| uint64_t KnownZero2, KnownOne2; |
| Instruction *I = dyn_cast<Instruction>(V); |
| if (!I) return; |
| |
| Mask &= V->getType()->getIntegralTypeMask(); |
| |
| switch (I->getOpcode()) { |
| case Instruction::And: |
| // If either the LHS or the RHS are Zero, the result is zero. |
| ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1); |
| Mask &= ~KnownZero; |
| ComputeMaskedBits(I->getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1); |
| assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); |
| assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); |
| |
| // Output known-1 bits are only known if set in both the LHS & RHS. |
| KnownOne &= KnownOne2; |
| // Output known-0 are known to be clear if zero in either the LHS | RHS. |
| KnownZero |= KnownZero2; |
| return; |
| case Instruction::Or: |
| ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1); |
| Mask &= ~KnownOne; |
| ComputeMaskedBits(I->getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1); |
| assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); |
| assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); |
| |
| // Output known-0 bits are only known if clear in both the LHS & RHS. |
| KnownZero &= KnownZero2; |
| // Output known-1 are known to be set if set in either the LHS | RHS. |
| KnownOne |= KnownOne2; |
| return; |
| case Instruction::Xor: { |
| ComputeMaskedBits(I->getOperand(1), Mask, KnownZero, KnownOne, Depth+1); |
| ComputeMaskedBits(I->getOperand(0), Mask, KnownZero2, KnownOne2, Depth+1); |
| assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); |
| assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); |
| |
| // Output known-0 bits are known if clear or set in both the LHS & RHS. |
| uint64_t KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2); |
| // Output known-1 are known to be set if set in only one of the LHS, RHS. |
| KnownOne = (KnownZero & KnownOne2) | (KnownOne & KnownZero2); |
| KnownZero = KnownZeroOut; |
| return; |
| } |
| case Instruction::Select: |
| ComputeMaskedBits(I->getOperand(2), Mask, KnownZero, KnownOne, Depth+1); |
| ComputeMaskedBits(I->getOperand(1), Mask, KnownZero2, KnownOne2, Depth+1); |
| assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); |
| assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?"); |
| |
| // Only known if known in both the LHS and RHS. |
| KnownOne &= KnownOne2; |
| KnownZero &= KnownZero2; |
| return; |
| case Instruction::FPTrunc: |
| case Instruction::FPExt: |
| case Instruction::FPToUI: |
| case Instruction::FPToSI: |
| case Instruction::SIToFP: |
| case Instruction::PtrToInt: |
| case Instruction::UIToFP: |
| case Instruction::IntToPtr: |
| return; // Can't work with floating point or pointers |
| case Instruction::Trunc: |
| // All these have integer operands |
| ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1); |
| return; |
| case Instruction::BitCast: { |
| const Type *SrcTy = I->getOperand(0)->getType(); |
| if (SrcTy->isIntegral()) { |
| ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1); |
| return; |
| } |
| break; |
| } |
| case Instruction::ZExt: { |
| // Compute the bits in the result that are not present in the input. |
| const Type *SrcTy = I->getOperand(0)->getType(); |
| uint64_t NotIn = ~SrcTy->getIntegralTypeMask(); |
| uint64_t NewBits = I->getType()->getIntegralTypeMask() & NotIn; |
| |
| Mask &= SrcTy->getIntegralTypeMask(); |
| ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1); |
| assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); |
| // The top bits are known to be zero. |
| KnownZero |= NewBits; |
| return; |
| } |
| case Instruction::SExt: { |
| // Compute the bits in the result that are not present in the input. |
| const Type *SrcTy = I->getOperand(0)->getType(); |
| uint64_t NotIn = ~SrcTy->getIntegralTypeMask(); |
| uint64_t NewBits = I->getType()->getIntegralTypeMask() & NotIn; |
| |
| Mask &= SrcTy->getIntegralTypeMask(); |
| ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1); |
| assert((KnownZero & KnownOne) == 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. |
| uint64_t InSignBit = 1ULL << (SrcTy->getPrimitiveSizeInBits()-1); |
| if (KnownZero & InSignBit) { // Input sign bit known zero |
| KnownZero |= NewBits; |
| KnownOne &= ~NewBits; |
| } else if (KnownOne & InSignBit) { // Input sign bit known set |
| KnownOne |= NewBits; |
| KnownZero &= ~NewBits; |
| } else { // Input sign bit unknown |
| KnownZero &= ~NewBits; |
| KnownOne &= ~NewBits; |
| } |
| return; |
| } |
| case Instruction::Shl: |
| // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0 |
| if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| uint64_t ShiftAmt = SA->getZExtValue(); |
| Mask >>= ShiftAmt; |
| ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1); |
| assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); |
| KnownZero <<= ShiftAmt; |
| KnownOne <<= ShiftAmt; |
| KnownZero |= (1ULL << ShiftAmt)-1; // low bits known zero. |
| return; |
| } |
| break; |
| case Instruction::LShr: |
| // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0 |
| if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| // Compute the new bits that are at the top now. |
| uint64_t ShiftAmt = SA->getZExtValue(); |
| uint64_t HighBits = (1ULL << ShiftAmt)-1; |
| HighBits <<= I->getType()->getPrimitiveSizeInBits()-ShiftAmt; |
| |
| // Unsigned shift right. |
| Mask <<= ShiftAmt; |
| ComputeMaskedBits(I->getOperand(0), Mask, KnownZero,KnownOne,Depth+1); |
| assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?"); |
| KnownZero >>= ShiftAmt; |
| KnownOne >>= ShiftAmt; |
| KnownZero |= HighBits; // high bits known zero. |
| return; |
| } |
| break; |
| case Instruction::AShr: |
| // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0 |
| if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| // Compute the new bits that are at the top now. |
| uint64_t ShiftAmt = SA->getZExtValue(); |
| uint64_t HighBits = (1ULL << ShiftAmt)-1; |
| HighBits <<= I->getType()->getPrimitiveSizeInBits()-ShiftAmt; |
| |
| // Signed shift right. |
| Mask <<= ShiftAmt; |
| ComputeMaskedBits(I->getOperand(0), Mask, KnownZero,KnownOne,Depth+1); |
| assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?"); |
| KnownZero >>= ShiftAmt; |
| KnownOne >>= ShiftAmt; |
| |
| // Handle the sign bits. |
| uint64_t SignBit = 1ULL << (I->getType()->getPrimitiveSizeInBits()-1); |
| SignBit >>= ShiftAmt; // Adjust to where it is now in the mask. |
| |
| if (KnownZero & SignBit) { // New bits are known zero. |
| KnownZero |= HighBits; |
| } else if (KnownOne & SignBit) { // New bits are known one. |
| KnownOne |= HighBits; |
| } |
| return; |
| } |
| break; |
| } |
| } |
| |
| /// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use |
| /// this predicate to simplify operations downstream. Mask is known to be zero |
| /// for bits that V cannot have. |
| static bool MaskedValueIsZero(Value *V, uint64_t Mask, unsigned Depth = 0) { |
| uint64_t KnownZero, KnownOne; |
| ComputeMaskedBits(V, Mask, KnownZero, KnownOne, Depth); |
| assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); |
| return (KnownZero & Mask) == Mask; |
| } |
| |
| /// 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, |
| uint64_t Demanded) { |
| 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. |
| if ((~Demanded & OpC->getZExtValue()) == 0) |
| return false; |
| |
| // This is producing any bits that are not needed, shrink the RHS. |
| uint64_t Val = Demanded & OpC->getZExtValue(); |
| I->setOperand(OpNo, GetConstantInType(OpC->getType(), Val)); |
| 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, |
| uint64_t KnownZero, |
| uint64_t KnownOne, |
| int64_t &Min, int64_t &Max) { |
| uint64_t TypeBits = Ty->getIntegralTypeMask(); |
| uint64_t UnknownBits = ~(KnownZero|KnownOne) & TypeBits; |
| |
| uint64_t SignBit = 1ULL << (Ty->getPrimitiveSizeInBits()-1); |
| |
| // 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 (SignBit & UnknownBits) { // Sign bit is unknown |
| Min |= SignBit; |
| Max &= ~SignBit; |
| } |
| |
| // Sign extend the min/max values. |
| int ShAmt = 64-Ty->getPrimitiveSizeInBits(); |
| Min = (Min << ShAmt) >> ShAmt; |
| Max = (Max << ShAmt) >> ShAmt; |
| } |
| |
| // 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, |
| uint64_t KnownZero, |
| uint64_t KnownOne, |
| uint64_t &Min, |
| uint64_t &Max) { |
| uint64_t TypeBits = Ty->getIntegralTypeMask(); |
| uint64_t UnknownBits = ~(KnownZero|KnownOne) & TypeBits; |
| |
| // 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 - Look at V. At this point, we know that only the |
| /// DemandedMask bits of the result of V are ever used downstream. If we can |
| /// use this information to simplify V, do so and return true. Otherwise, |
| /// analyze the expression and return a mask of KnownOne and KnownZero bits for |
| /// the expression (used to simplify the caller). The KnownZero/One bits may |
| /// only be accurate for those bits in the DemandedMask. |
| bool InstCombiner::SimplifyDemandedBits(Value *V, uint64_t DemandedMask, |
| uint64_t &KnownZero, uint64_t &KnownOne, |
| unsigned Depth) { |
| if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V)) { |
| // We know all of the bits for a constant! |
| KnownOne = CI->getZExtValue() & DemandedMask; |
| KnownZero = ~KnownOne & DemandedMask; |
| return false; |
| } |
| |
| KnownZero = KnownOne = 0; |
| 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 = V->getType()->getIntegralTypeMask(); |
| } else if (DemandedMask == 0) { // Not demanding any bits from V. |
| if (V != UndefValue::get(V->getType())) |
| return UpdateValueUsesWith(V, UndefValue::get(V->getType())); |
| return false; |
| } else if (Depth == 6) { // Limit search depth. |
| return false; |
| } |
| |
| Instruction *I = dyn_cast<Instruction>(V); |
| if (!I) return false; // Only analyze instructions. |
| |
| DemandedMask &= V->getType()->getIntegralTypeMask(); |
| |
| uint64_t KnownZero2 = 0, KnownOne2 = 0; |
| switch (I->getOpcode()) { |
| default: break; |
| case Instruction::And: |
| // If either the LHS or the RHS are Zero, the result is zero. |
| if (SimplifyDemandedBits(I->getOperand(1), DemandedMask, |
| KnownZero, KnownOne, Depth+1)) |
| return true; |
| assert((KnownZero & KnownOne) == 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 & ~KnownZero, |
| KnownZero2, KnownOne2, Depth+1)) |
| return true; |
| assert((KnownZero2 & KnownOne2) == 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 & ~KnownZero2 & KnownOne) == (DemandedMask & ~KnownZero2)) |
| return UpdateValueUsesWith(I, I->getOperand(0)); |
| if ((DemandedMask & ~KnownZero & KnownOne2) == (DemandedMask & ~KnownZero)) |
| return UpdateValueUsesWith(I, I->getOperand(1)); |
| |
| // If all of the demanded bits in the inputs are known zeros, return zero. |
| if ((DemandedMask & (KnownZero|KnownZero2)) == DemandedMask) |
| return UpdateValueUsesWith(I, Constant::getNullValue(I->getType())); |
| |
| // If the RHS is a constant, see if we can simplify it. |
| if (ShrinkDemandedConstant(I, 1, DemandedMask & ~KnownZero2)) |
| return UpdateValueUsesWith(I, I); |
| |
| // Output known-1 bits are only known if set in both the LHS & RHS. |
| KnownOne &= KnownOne2; |
| // Output known-0 are known to be clear if zero in either the LHS | RHS. |
| KnownZero |= KnownZero2; |
| break; |
| case Instruction::Or: |
| if (SimplifyDemandedBits(I->getOperand(1), DemandedMask, |
| KnownZero, KnownOne, Depth+1)) |
| return true; |
| assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); |
| if (SimplifyDemandedBits(I->getOperand(0), DemandedMask & ~KnownOne, |
| KnownZero2, KnownOne2, Depth+1)) |
| return true; |
| assert((KnownZero2 & KnownOne2) == 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 & ~KnownOne2 & KnownZero) == (DemandedMask & ~KnownOne2)) |
| return UpdateValueUsesWith(I, I->getOperand(0)); |
| if ((DemandedMask & ~KnownOne & KnownZero2) == (DemandedMask & ~KnownOne)) |
| 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 & (~KnownZero) & KnownOne2) == |
| (DemandedMask & (~KnownZero))) |
| return UpdateValueUsesWith(I, I->getOperand(0)); |
| if ((DemandedMask & (~KnownZero2) & KnownOne) == |
| (DemandedMask & (~KnownZero2))) |
| 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. |
| KnownZero &= KnownZero2; |
| // Output known-1 are known to be set if set in either the LHS | RHS. |
| KnownOne |= KnownOne2; |
| break; |
| case Instruction::Xor: { |
| if (SimplifyDemandedBits(I->getOperand(1), DemandedMask, |
| KnownZero, KnownOne, Depth+1)) |
| return true; |
| assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); |
| if (SimplifyDemandedBits(I->getOperand(0), DemandedMask, |
| KnownZero2, KnownOne2, Depth+1)) |
| return true; |
| assert((KnownZero2 & KnownOne2) == 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 & KnownZero) == DemandedMask) |
| return UpdateValueUsesWith(I, I->getOperand(0)); |
| if ((DemandedMask & KnownZero2) == DemandedMask) |
| return UpdateValueUsesWith(I, I->getOperand(1)); |
| |
| // Output known-0 bits are known if clear or set in both the LHS & RHS. |
| uint64_t KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2); |
| // Output known-1 are known to be set if set in only one of the LHS, RHS. |
| uint64_t KnownOneOut = (KnownZero & KnownOne2) | (KnownOne & KnownZero2); |
| |
| // If all of the unknown bits are known to be zero on one side or the other |
| // (but not both) turn this into an *inclusive* or. |
| // e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0 |
| if (uint64_t UnknownBits = DemandedMask & ~(KnownZeroOut|KnownOneOut)) { |
| if ((UnknownBits & (KnownZero|KnownZero2)) == UnknownBits) { |
| 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 & (KnownZero|KnownOne)) == DemandedMask) { // all known |
| if ((KnownOne & KnownOne2) == KnownOne) { |
| Constant *AndC = GetConstantInType(I->getType(), |
| ~KnownOne & 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); |
| |
| KnownZero = KnownZeroOut; |
| KnownOne = KnownOneOut; |
| break; |
| } |
| case Instruction::Select: |
| if (SimplifyDemandedBits(I->getOperand(2), DemandedMask, |
| KnownZero, KnownOne, Depth+1)) |
| return true; |
| if (SimplifyDemandedBits(I->getOperand(1), DemandedMask, |
| KnownZero2, KnownOne2, Depth+1)) |
| return true; |
| assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); |
| assert((KnownZero2 & KnownOne2) == 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. |
| KnownOne &= KnownOne2; |
| KnownZero &= KnownZero2; |
| break; |
| case Instruction::Trunc: |
| if (SimplifyDemandedBits(I->getOperand(0), DemandedMask, |
| KnownZero, KnownOne, Depth+1)) |
| return true; |
| assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); |
| break; |
| case Instruction::BitCast: |
| if (!I->getOperand(0)->getType()->isIntegral()) |
| return false; |
| |
| if (SimplifyDemandedBits(I->getOperand(0), DemandedMask, |
| KnownZero, KnownOne, Depth+1)) |
| return true; |
| assert((KnownZero & KnownOne) == 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 Type *SrcTy = I->getOperand(0)->getType(); |
| uint64_t NotIn = ~SrcTy->getIntegralTypeMask(); |
| uint64_t NewBits = I->getType()->getIntegralTypeMask() & NotIn; |
| |
| DemandedMask &= SrcTy->getIntegralTypeMask(); |
| if (SimplifyDemandedBits(I->getOperand(0), DemandedMask, |
| KnownZero, KnownOne, Depth+1)) |
| return true; |
| assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); |
| // The top bits are known to be zero. |
| KnownZero |= NewBits; |
| break; |
| } |
| case Instruction::SExt: { |
| // Compute the bits in the result that are not present in the input. |
| const Type *SrcTy = I->getOperand(0)->getType(); |
| uint64_t NotIn = ~SrcTy->getIntegralTypeMask(); |
| uint64_t NewBits = I->getType()->getIntegralTypeMask() & NotIn; |
| |
| // Get the sign bit for the source type |
| uint64_t InSignBit = 1ULL << (SrcTy->getPrimitiveSizeInBits()-1); |
| int64_t InputDemandedBits = DemandedMask & SrcTy->getIntegralTypeMask(); |
| |
| // If any of the sign extended bits are demanded, we know that the sign |
| // bit is demanded. |
| if (NewBits & DemandedMask) |
| InputDemandedBits |= InSignBit; |
| |
| if (SimplifyDemandedBits(I->getOperand(0), InputDemandedBits, |
| KnownZero, KnownOne, Depth+1)) |
| return true; |
| assert((KnownZero & KnownOne) == 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 ((KnownZero & InSignBit) || (NewBits & ~DemandedMask) == NewBits) { |
| // Convert to ZExt cast |
| CastInst *NewCast = CastInst::create( |
| Instruction::ZExt, I->getOperand(0), I->getType(), I->getName(), I); |
| return UpdateValueUsesWith(I, NewCast); |
| } else if (KnownOne & InSignBit) { // Input sign bit known set |
| KnownOne |= NewBits; |
| KnownZero &= ~NewBits; |
| } else { // Input sign bit unknown |
| KnownZero &= ~NewBits; |
| KnownOne &= ~NewBits; |
| } |
| break; |
| } |
| case Instruction::Add: |
| // 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->isNullValue()) |
| break; |
| |
| // 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. |
| |
| // Shift the demanded mask up so that it's at the top of the uint64_t. |
| unsigned BitWidth = I->getType()->getPrimitiveSizeInBits(); |
| unsigned NLZ = CountLeadingZeros_64(DemandedMask << (64-BitWidth)); |
| |
| // 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. |
| uint64_t InDemandedBits = ~0ULL >> 64-BitWidth+NLZ; |
| |
| // Find information about known zero/one bits in the input. |
| if (SimplifyDemandedBits(I->getOperand(0), InDemandedBits, |
| KnownZero2, KnownOne2, 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 (KnownZero2 == 0 && KnownOne2 == 0) |
| break; |
| |
| // Turn it into OR if input bits are zero. |
| if ((KnownZero2 & RHS->getZExtValue()) == RHS->getZExtValue()) { |
| 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. |
| uint64_t RHSVal = RHS->getZExtValue(); |
| |
| bool CarryIn = false; |
| uint64_t CarryBits = 0; |
| uint64_t CurBit = 1; |
| for (unsigned i = 0; i != BitWidth; ++i, CurBit <<= 1) { |
| // Record the current carry in. |
| if (CarryIn) CarryBits |= CurBit; |
| |
| bool CarryOut; |
| |
| // This bit has a carry out unless it is "zero + zero" or |
| // "zero + anything" with no carry in. |
| if ((KnownZero2 & CurBit) && ((RHSVal & CurBit) == 0)) { |
| CarryOut = false; // 0 + 0 has no carry out, even with carry in. |
| } else if (!CarryIn && |
| ((KnownZero2 & CurBit) || ((RHSVal & CurBit) == 0))) { |
| CarryOut = false; // 0 + anything has no carry out if no carry in. |
| } else { |
| // Otherwise, we have to assume we have a carry out. |
| CarryOut = true; |
| } |
| |
| // This stage's carry out becomes the next stage's carry-in. |
| CarryIn = CarryOut; |
| } |
| |
| // 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. |
| KnownOne = ((KnownZero2 & RHSVal) | (KnownOne2 & ~RHSVal)) & ~CarryBits; |
| |
| // Bits are known zero if they are known zero in both operands and there |
| // is no input carry. |
| KnownZero = KnownZero2 & ~RHSVal & ~CarryBits; |
| } |
| break; |
| case Instruction::Shl: |
| if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| uint64_t ShiftAmt = SA->getZExtValue(); |
| if (SimplifyDemandedBits(I->getOperand(0), DemandedMask >> ShiftAmt, |
| KnownZero, KnownOne, Depth+1)) |
| return true; |
| assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); |
| KnownZero <<= ShiftAmt; |
| KnownOne <<= ShiftAmt; |
| KnownZero |= (1ULL << ShiftAmt) - 1; // low bits known zero. |
| } |
| break; |
| case Instruction::LShr: |
| // For a logical shift right |
| if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| unsigned ShiftAmt = SA->getZExtValue(); |
| |
| // Compute the new bits that are at the top now. |
| uint64_t HighBits = (1ULL << ShiftAmt)-1; |
| HighBits <<= I->getType()->getPrimitiveSizeInBits() - ShiftAmt; |
| uint64_t TypeMask = I->getType()->getIntegralTypeMask(); |
| // Unsigned shift right. |
| if (SimplifyDemandedBits(I->getOperand(0), |
| (DemandedMask << ShiftAmt) & TypeMask, |
| KnownZero, KnownOne, Depth+1)) |
| return true; |
| assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); |
| KnownZero &= TypeMask; |
| KnownOne &= TypeMask; |
| KnownZero >>= ShiftAmt; |
| KnownOne >>= ShiftAmt; |
| KnownZero |= 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 = new ShiftInst(Instruction::LShr, I->getOperand(0), |
| I->getOperand(1), I->getName()); |
| InsertNewInstBefore(cast<Instruction>(NewVal), *I); |
| return UpdateValueUsesWith(I, NewVal); |
| } |
| |
| if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| unsigned ShiftAmt = SA->getZExtValue(); |
| |
| // Compute the new bits that are at the top now. |
| uint64_t HighBits = (1ULL << ShiftAmt)-1; |
| HighBits <<= I->getType()->getPrimitiveSizeInBits() - ShiftAmt; |
| uint64_t TypeMask = I->getType()->getIntegralTypeMask(); |
| // Signed shift right. |
| if (SimplifyDemandedBits(I->getOperand(0), |
| (DemandedMask << ShiftAmt) & TypeMask, |
| KnownZero, KnownOne, Depth+1)) |
| return true; |
| assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); |
| KnownZero &= TypeMask; |
| KnownOne &= TypeMask; |
| KnownZero >>= ShiftAmt; |
| KnownOne >>= ShiftAmt; |
| |
| // Handle the sign bits. |
| uint64_t SignBit = 1ULL << (I->getType()->getPrimitiveSizeInBits()-1); |
| SignBit >>= ShiftAmt; // Adjust to where it is now in the mask. |
| |
| // 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 ((KnownZero & SignBit) || (HighBits & ~DemandedMask) == HighBits) { |
| // Perform the logical shift right. |
| Value *NewVal = new ShiftInst(Instruction::LShr, I->getOperand(0), |
| SA, I->getName()); |
| InsertNewInstBefore(cast<Instruction>(NewVal), *I); |
| return UpdateValueUsesWith(I, NewVal); |
| } else if (KnownOne & SignBit) { // New bits are known one. |
| KnownOne |= HighBits; |
| } |
| } |
| break; |
| } |
| |
| // If the client is only demanding bits that we know, return the known |
| // constant. |
| if ((DemandedMask & (KnownZero|KnownOne)) == DemandedMask) |
| return UpdateValueUsesWith(I, GetConstantInType(I->getType(), KnownOne)); |
| return false; |
| } |
| |
| |
| /// SimplifyDemandedVectorElts - The specified value producecs 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<PackedType>(V->getType())->getNumElements(); |
| assert(VWidth <= 64 && "Vector too wide to analyze!"); |
| uint64_t EltMask = ~0ULL >> (64-VWidth); |
| assert(DemandedElts != EltMask && (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 (ConstantPacked *CP = dyn_cast<ConstantPacked>(V)) { |
| const Type *EltTy = cast<PackedType>(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 = ConstantPacked::get(Elts); |
| return NewCP != CP ? NewCP : 0; |
| } else if (isa<ConstantAggregateZero>(V)) { |
| // Simplify the CAZ to a ConstantPacked where the non-demanded elements are |
| // set to undef. |
| const Type *EltTy = cast<PackedType>(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 ConstantPacked::get(Elts); |
| } |
| |
| if (!V->hasOneUse()) { // Other users may use these bits. |
| if (Depth != 0) { // Not at the root. |
| // TODO: Just compute the UndefElts information recursively. |
| return false; |
| } |
| return false; |
| } else if (Depth == 10) { // Limit search depth. |
| return false; |
| } |
| |
| 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::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 = |
| new InsertElementInst(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; |
| } |
| |
| // isTrueWhenEqual - Return true if the specified setcondinst instruction is |
| // true when both operands are equal... |
| // |
| static bool isTrueWhenEqual(Instruction &I) { |
| return I.getOpcode() == Instruction::SetEQ || |
| I.getOpcode() == Instruction::SetGE || |
| I.getOpcode() == Instruction::SetLE; |
| } |
| |
| /// AssociativeOpt - Perform an optimization on an associative operator. This |
| /// function is designed to check a chain of associative operators for a |
| /// potential to apply a certain optimization. Since the optimization may be |
| /// applicable if the expression was reassociated, this checks the chain, then |
| /// reassociates the expression as necessary to expose the optimization |
| /// opportunity. This makes use of a special Functor, which must define |
| /// 'shouldApply' and 'apply' methods. |
| /// |
| template<typename Functor> |
| Instruction *AssociativeOpt(BinaryOperator &Root, const Functor &F) { |
| unsigned Opcode = Root.getOpcode(); |
| Value *LHS = Root.getOperand(0); |
| |
| // Quick check, see if the immediate LHS matches... |
| if (F.shouldApply(LHS)) |
| return F.apply(Root); |
| |
| // Otherwise, if the LHS is not of the same opcode as the root, return. |
| Instruction *LHSI = dyn_cast<Instruction>(LHS); |
| while (LHSI && LHSI->getOpcode() == Opcode && LHSI->hasOneUse()) { |
| // Should we apply this transform to the RHS? |
| bool ShouldApply = F.shouldApply(LHSI->getOperand(1)); |
| |
| // If not to the RHS, check to see if we should apply to the LHS... |
| if (!ShouldApply && F.shouldApply(LHSI->getOperand(0))) { |
| cast<BinaryOperator>(LHSI)->swapOperands(); // Make the LHS the RHS |
| ShouldApply = true; |
| } |
| |
| // If the functor wants to apply the optimization to the RHS of LHSI, |
| // reassociate the expression from ((? op A) op B) to (? op (A op B)) |
| if (ShouldApply) { |
| BasicBlock *BB = Root.getParent(); |
| |
| // Now all of the instructions are in the current basic block, go ahead |
| // and perform the reassociation. |
| Instruction *TmpLHSI = cast<Instruction>(Root.getOperand(0)); |
| |
| // First move the selected RHS to the LHS of the root... |
| Root.setOperand(0, LHSI->getOperand(1)); |
| |
| // Make what used to be the LHS of the root be the user of the root... |
| Value *ExtraOperand = TmpLHSI->getOperand(1); |
| if (&Root == TmpLHSI) { |
| Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType())); |
| return 0; |
| } |
| Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI |
| TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root |
| TmpLHSI->getParent()->getInstList().remove(TmpLHSI); |
| BasicBlock::iterator ARI = &Root; ++ARI; |
| BB->getInstList().insert(ARI, TmpLHSI); // Move TmpLHSI to after Root |
| ARI = Root; |
| |
| // Now propagate the ExtraOperand down the chain of instructions until we |
| // get to LHSI. |
| while (TmpLHSI != LHSI) { |
| Instruction *NextLHSI = cast<Instruction>(TmpLHSI->getOperand(0)); |
| // Move the instruction to immediately before the chain we are |
| // constructing to avoid breaking dominance properties. |
| NextLHSI->getParent()->getInstList().remove(NextLHSI); |
| BB->getInstList().insert(ARI, NextLHSI); |
| ARI = NextLHSI; |
| |
| Value *NextOp = NextLHSI->getOperand(1); |
| NextLHSI->setOperand(1, ExtraOperand); |
| TmpLHSI = NextLHSI; |
| ExtraOperand = NextOp; |
| } |
| |
| // Now that the instructions are reassociated, have the functor perform |
| // the transformation... |
| return F.apply(Root); |
| } |
| |
| LHSI = dyn_cast<Instruction>(LHSI->getOperand(0)); |
| } |
| return 0; |
| } |
| |
| |
| // AddRHS - Implements: X + X --> X << 1 |
| struct AddRHS { |
| Value *RHS; |
| AddRHS(Value *rhs) : RHS(rhs) {} |
| bool shouldApply(Value *LHS) const { return LHS == RHS; } |
| Instruction *apply(BinaryOperator &Add) const { |
| return new ShiftInst(Instruction::Shl, Add.getOperand(0), |
| ConstantInt::get(Type::UByteTy, 1)); |
| } |
| }; |
| |
| // AddMaskingAnd - Implements (A & C1)+(B & C2) --> (A & C1)|(B & C2) |
| // iff C1&C2 == 0 |
| struct AddMaskingAnd { |
| Constant *C2; |
| AddMaskingAnd(Constant *c) : C2(c) {} |
| bool shouldApply(Value *LHS) const { |
| ConstantInt *C1; |
| return match(LHS, m_And(m_Value(), m_ConstantInt(C1))) && |
| ConstantExpr::getAnd(C1, C2)->isNullValue(); |
| } |
| Instruction *apply(BinaryOperator &Add) const { |
| return BinaryOperator::createOr(Add.getOperand(0), Add.getOperand(1)); |
| } |
| }; |
| |
| static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO, |
| InstCombiner *IC) { |
| if (CastInst *CI = dyn_cast<CastInst>(&I)) { |
| if (Constant *SOC = dyn_cast<Constant>(SO)) |
| return ConstantExpr::getCast(CI->getOpcode(), SOC, I.getType()); |
| |
| return IC->InsertNewInstBefore(CastInst::create( |
| CI->getOpcode(), SO, I.getType(), SO->getName() + ".cast"), I); |
| } |
| |
| // Figure out if the constant is the left or the right argument. |
| bool ConstIsRHS = isa<Constant>(I.getOperand(1)); |
| Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS)); |
| |
| if (Constant *SOC = dyn_cast<Constant>(SO)) { |
| if (ConstIsRHS) |
| return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand); |
| return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC); |
| } |
| |
| Value *Op0 = SO, *Op1 = ConstOperand; |
| if (!ConstIsRHS) |
| std::swap(Op0, Op1); |
| Instruction *New; |
| if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I)) |
| New = BinaryOperator::create(BO->getOpcode(), Op0, Op1,SO->getName()+".op"); |
| else if (ShiftInst *SI = dyn_cast<ShiftInst>(&I)) |
| New = new ShiftInst(SI->getOpcode(), Op0, Op1, SO->getName()+".sh"); |
| else { |
| assert(0 && "Unknown binary instruction type!"); |
| abort(); |
| } |
| return IC->InsertNewInstBefore(New, I); |
| } |
| |
| // FoldOpIntoSelect - Given an instruction with a select as one operand and a |
| // constant as the other operand, try to fold the binary operator into the |
| // select arguments. This also works for Cast instructions, which obviously do |
| // not have a second operand. |
| static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI, |
| InstCombiner *IC) { |
| // Don't modify shared select instructions |
| if (!SI->hasOneUse()) return 0; |
| Value *TV = SI->getOperand(1); |
| Value *FV = SI->getOperand(2); |
| |
| if (isa<Constant>(TV) || isa<Constant>(FV)) { |
| // Bool selects with constant operands can be folded to logical ops. |
| if (SI->getType() == Type::BoolTy) return 0; |
| |
| Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC); |
| Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC); |
| |
| return new SelectInst(SI->getCondition(), SelectTrueVal, |
| SelectFalseVal); |
| } |
| return 0; |
| } |
| |
| |
| /// FoldOpIntoPhi - Given a binary operator or cast instruction which has a PHI |
| /// node as operand #0, see if we can fold the instruction into the PHI (which |
| /// is only possible if all operands to the PHI are constants). |
| Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) { |
| PHINode *PN = cast<PHINode>(I.getOperand(0)); |
| unsigned NumPHIValues = PN->getNumIncomingValues(); |
| if (!PN->hasOneUse() || NumPHIValues == 0) 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 |
| // 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. |
| 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 = new PHINode(I.getType(), I.getName()); |
| I.setName(""); |
| NewPN->reserveOperandSpace(PN->getNumOperands()/2); |
| InsertNewInstBefore(NewPN, *PN); |
| |
| // Next, add all of the operands to the PHI. |
| if (I.getNumOperands() == 2) { |
| Constant *C = cast<Constant>(I.getOperand(1)); |
| for (unsigned i = 0; i != NumPHIValues; ++i) { |
| Value *InV; |
| if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) { |
| 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 (ShiftInst *SI = dyn_cast<ShiftInst>(&I)) |
| InV = new ShiftInst(SI->getOpcode(), |
| PN->getIncomingValue(i), C, "phitmp", |
| NonConstBB->getTerminator()); |
| else |
| assert(0 && "Unknown binop!"); |
| |
| WorkList.push_back(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()); |
| WorkList.push_back(cast<Instruction>(InV)); |
| } |
| NewPN->addIncoming(InV, PN->getIncomingBlock(i)); |
| } |
| } |
| return ReplaceInstUsesWith(I, NewPN); |
| } |
| |
| Instruction *InstCombiner::visitAdd(BinaryOperator &I) { |
| bool Changed = SimplifyCommutative(I); |
| Value *LHS = I.getOperand(0), *RHS = I.getOperand(1); |
| |
| if (Constant *RHSC = dyn_cast<Constant>(RHS)) { |
| // X + undef -> undef |
| if (isa<UndefValue>(RHS)) |
| return ReplaceInstUsesWith(I, RHS); |
| |
| // X + 0 --> X |
| if (!I.getType()->isFloatingPoint()) { // NOTE: -0 + +0 = +0. |
| if (RHSC->isNullValue()) |
| return ReplaceInstUsesWith(I, LHS); |
| } else if (ConstantFP *CFP = dyn_cast<ConstantFP>(RHSC)) { |
| if (CFP->isExactlyValue(-0.0)) |
| return ReplaceInstUsesWith(I, LHS); |
| } |
| |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) { |
| // X + (signbit) --> X ^ signbit |
| uint64_t Val = CI->getZExtValue(); |
| if (Val == (1ULL << (CI->getType()->getPrimitiveSizeInBits()-1))) |
| return BinaryOperator::createXor(LHS, RHS); |
| |
| // See if SimplifyDemandedBits can simplify this. This handles stuff like |
| // (X & 254)+1 -> (X&254)|1 |
| uint64_t KnownZero, KnownOne; |
| if (!isa<PackedType>(I.getType()) && |
| SimplifyDemandedBits(&I, I.getType()->getIntegralTypeMask(), |
| KnownZero, KnownOne)) |
| return &I; |
| } |
| |
| if (isa<PHINode>(LHS)) |
| if (Instruction *NV = FoldOpIntoPhi(I)) |
| return NV; |
| |
| ConstantInt *XorRHS = 0; |
| Value *XorLHS = 0; |
| if (match(LHS, m_Xor(m_Value(XorLHS), m_ConstantInt(XorRHS)))) { |
| unsigned TySizeBits = I.getType()->getPrimitiveSizeInBits(); |
| int64_t RHSSExt = cast<ConstantInt>(RHSC)->getSExtValue(); |
| uint64_t RHSZExt = cast<ConstantInt>(RHSC)->getZExtValue(); |
| |
| uint64_t C0080Val = 1ULL << 31; |
| int64_t CFF80Val = -C0080Val; |
| unsigned Size = 32; |
| do { |
| if (TySizeBits > Size) { |
| bool Found = false; |
| // If we have ADD(XOR(AND(X, 0xFF), 0x80), 0xF..F80), it's a sext. |
| // If we have ADD(XOR(AND(X, 0xFF), 0xF..F80), 0x80), it's a sext. |
| if (RHSSExt == CFF80Val) { |
| if (XorRHS->getZExtValue() == C0080Val) |
| Found = true; |
| } else if (RHSZExt == C0080Val) { |
| if (XorRHS->getSExtValue() == CFF80Val) |
| Found = true; |
| } |
| if (Found) { |
| // This is a sign extend if the top bits are known zero. |
| uint64_t Mask = ~0ULL; |
| Mask <<= 64-(TySizeBits-Size); |
| Mask &= XorLHS->getType()->getIntegralTypeMask(); |
| if (!MaskedValueIsZero(XorLHS, Mask)) |
| Size = 0; // Not a sign ext, but can't be any others either. |
| goto FoundSExt; |
| } |
| } |
| Size >>= 1; |
| C0080Val >>= Size; |
| CFF80Val >>= Size; |
| } while (Size >= 8); |
| |
| FoundSExt: |
| const Type *MiddleType = 0; |
| switch (Size) { |
| default: break; |
| case 32: MiddleType = Type::IntTy; break; |
| case 16: MiddleType = Type::ShortTy; break; |
| case 8: MiddleType = Type::SByteTy; break; |
| } |
| if (MiddleType) { |
| Instruction *NewTrunc = |
| CastInst::createInferredCast(XorLHS, MiddleType, "sext"); |
| InsertNewInstBefore(NewTrunc, I); |
| return new SExtInst(NewTrunc, I.getType()); |
| } |
| } |
| } |
| |
| // X + X --> X << 1 |
| if (I.getType()->isInteger()) { |
| if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result; |
| |
| if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) { |
| if (RHSI->getOpcode() == Instruction::Sub) |
| if (LHS == RHSI->getOperand(1)) // A + (B - A) --> B |
| return ReplaceInstUsesWith(I, RHSI->getOperand(0)); |
| } |
| if (Instruction *LHSI = dyn_cast<Instruction>(LHS)) { |
| if (LHSI->getOpcode() == Instruction::Sub) |
| if (RHS == LHSI->getOperand(1)) // (B - A) + A --> B |
| return ReplaceInstUsesWith(I, LHSI->getOperand(0)); |
| } |
| } |
| |
| // -A + B --> B - A |
| if (Value *V = dyn_castNegVal(LHS)) |
| return BinaryOperator::createSub(RHS, V); |
| |
| // A + -B --> A - B |
| if (!isa<Constant>(RHS)) |
| if (Value *V = dyn_castNegVal(RHS)) |
| return BinaryOperator::createSub(LHS, V); |
| |
| |
| ConstantInt *C2; |
| if (Value *X = dyn_castFoldableMul(LHS, C2)) { |
| if (X == RHS) // X*C + X --> X * (C+1) |
| return BinaryOperator::createMul(RHS, AddOne(C2)); |
| |
| // X*C1 + X*C2 --> X * (C1+C2) |
| ConstantInt *C1; |
| if (X == dyn_castFoldableMul(RHS, C1)) |
| return BinaryOperator::createMul(X, ConstantExpr::getAdd(C1, C2)); |
| } |
| |
| // X + X*C --> X * (C+1) |
| if (dyn_castFoldableMul(RHS, C2) == LHS) |
| return BinaryOperator::createMul(LHS, AddOne(C2)); |
| |
| |
| // (A & C1)+(B & C2) --> (A & C1)|(B & C2) iff C1&C2 == 0 |
| if (match(RHS, m_And(m_Value(), m_ConstantInt(C2)))) |
| if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2))) return R; |
| |
| if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) { |
| Value *X = 0; |
| if (match(LHS, m_Not(m_Value(X)))) { // ~X + C --> (C-1) - X |
| Constant *C= ConstantExpr::getSub(CRHS, ConstantInt::get(I.getType(), 1)); |
| return BinaryOperator::createSub(C, X); |
| } |
| |
| // (X & FF00) + xx00 -> (X+xx00) & FF00 |
| if (LHS->hasOneUse() && match(LHS, m_And(m_Value(X), m_ConstantInt(C2)))) { |
| Constant *Anded = ConstantExpr::getAnd(CRHS, C2); |
| if (Anded == CRHS) { |
| // See if all bits from the first bit set in the Add RHS up are included |
| // in the mask. First, get the rightmost bit. |
| uint64_t AddRHSV = CRHS->getZExtValue(); |
| |
| // Form a mask of all bits from the lowest bit added through the top. |
| uint64_t AddRHSHighBits = ~((AddRHSV & -AddRHSV)-1); |
| AddRHSHighBits &= C2->getType()->getIntegralTypeMask(); |
| |
| // See if the and mask includes all of these bits. |
| uint64_t AddRHSHighBitsAnd = AddRHSHighBits & C2->getZExtValue(); |
| |
| 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()->getPrimitiveSize() == |
| TD->getIntPtrType()->getPrimitiveSize()) |
| && isa<PointerType>(CI->getOperand(0)->getType())) { |
| Value *I2 = InsertCastBefore(CI->getOperand(0), |
| PointerType::get(Type::SByteTy), I); |
| I2 = InsertNewInstBefore(new GetElementPtrInst(I2, Other, "ctg2"), I); |
| return new PtrToIntInst(I2, CI->getType()); |
| } |
| } |
| |
| return Changed ? &I : 0; |
| } |
| |
| // isSignBit - Return true if the value represented by the constant only has the |
| // highest order bit set. |
| static bool isSignBit(ConstantInt *CI) { |
| unsigned NumBits = CI->getType()->getPrimitiveSizeInBits(); |
| return (CI->getZExtValue() & (~0ULL >> (64-NumBits))) == (1ULL << (NumBits-1)); |
| } |
| |
| /// RemoveNoopCast - Strip off nonconverting casts from the value. |
| /// |
| static Value *RemoveNoopCast(Value *V) { |
| if (CastInst *CI = dyn_cast<CastInst>(V)) { |
| const Type *CTy = CI->getType(); |
| const Type *OpTy = CI->getOperand(0)->getType(); |
| if (CTy->isInteger() && OpTy->isInteger()) { |
| if (CTy->getPrimitiveSizeInBits() == OpTy->getPrimitiveSizeInBits()) |
| return RemoveNoopCast(CI->getOperand(0)); |
| } else if (isa<PointerType>(CTy) && isa<PointerType>(OpTy)) |
| return RemoveNoopCast(CI->getOperand(0)); |
| } |
| return V; |
| } |
| |
| Instruction *InstCombiner::visitSub(BinaryOperator &I) { |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| if (Op0 == Op1) // sub X, X -> 0 |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| |
| // If this is a 'B = x-(-A)', change to B = x+A... |
| if (Value *V = dyn_castNegVal(Op1)) |
| return BinaryOperator::createAdd(Op0, V); |
| |
| if (isa<UndefValue>(Op0)) |
| return ReplaceInstUsesWith(I, Op0); // undef - X -> undef |
| if (isa<UndefValue>(Op1)) |
| return ReplaceInstUsesWith(I, Op1); // X - undef -> undef |
| |
| if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) { |
| // Replace (-1 - A) with (~A)... |
| if (C->isAllOnesValue()) |
| return BinaryOperator::createNot(Op1); |
| |
| // C - ~X == X + (1+C) |
| Value *X = 0; |
| if (match(Op1, m_Not(m_Value(X)))) |
| return BinaryOperator::createAdd(X, |
| ConstantExpr::getAdd(C, ConstantInt::get(I.getType(), 1))); |
| // -((uint)X >> 31) -> ((int)X >> 31) |
| // -((int)X >> 31) -> ((uint)X >> 31) |
| if (C->isNullValue()) { |
| Value *NoopCastedRHS = RemoveNoopCast(Op1); |
| if (ShiftInst *SI = dyn_cast<ShiftInst>(NoopCastedRHS)) |
| if (SI->getOpcode() == Instruction::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->getZExtValue() == |
| SI->getType()->getPrimitiveSizeInBits()-1) { |
| // Ok, the transformation is safe. Insert AShr. |
| return new ShiftInst(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->getZExtValue() == |
| SI->getType()->getPrimitiveSizeInBits()-1) { |
| // Ok, the transformation is safe. Insert LShr. |
| return new ShiftInst(Instruction::LShr, 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 (isa<PHINode>(Op0)) |
| if (Instruction *NV = FoldOpIntoPhi(I)) |
| return NV; |
| } |
| |
| if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) { |
| if (Op1I->getOpcode() == Instruction::Add && |
| !Op0->getType()->isFloatingPoint()) { |
| if (Op1I->getOperand(0) == Op0) // X-(X+Y) == -Y |
| return BinaryOperator::createNeg(Op1I->getOperand(1), I.getName()); |
| else if (Op1I->getOperand(1) == Op0) // X-(Y+X) == -Y |
| return BinaryOperator::createNeg(Op1I->getOperand(0), I.getName()); |
| else if (ConstantInt *CI1 = dyn_cast<ConstantInt>(I.getOperand(0))) { |
| if (ConstantInt *CI2 = dyn_cast<ConstantInt>(Op1I->getOperand(1))) |
| // C1-(X+C2) --> (C1-C2)-X |
| return BinaryOperator::createSub(ConstantExpr::getSub(CI1, CI2), |
| Op1I->getOperand(0)); |
| } |
| } |
| |
| if (Op1I->hasOneUse()) { |
| // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression |
| // is not used by anyone else... |
| // |
| if (Op1I->getOpcode() == Instruction::Sub && |
| !Op1I->getType()->isFloatingPoint()) { |
| // Swap the two operands of the subexpr... |
| Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1); |
| Op1I->setOperand(0, IIOp1); |
| Op1I->setOperand(1, IIOp0); |
| |
| // Create the new top level add instruction... |
| return BinaryOperator::createAdd(Op0, Op1); |
| } |
| |
| // Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)... |
| // |
| if (Op1I->getOpcode() == Instruction::And && |
| (Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) { |
| Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0); |
| |
| Value *NewNot = |
| InsertNewInstBefore(BinaryOperator::createNot(OtherOp, "B.not"), I); |
| return BinaryOperator::createAnd(Op0, NewNot); |
| } |
| |
| // 0 - (X sdiv C) -> (X sdiv -C) |
| if (Op1I->getOpcode() == Instruction::SDiv) |
| if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0)) |
| if (CSI->isNullValue()) |
| 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 = |
| ConstantExpr::getSub(ConstantInt::get(I.getType(), 1), C2); |
| return BinaryOperator::createMul(Op0, CP1); |
| } |
| } |
| } |
| |
| if (!Op0->getType()->isFloatingPoint()) |
| if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) |
| if (Op0I->getOpcode() == Instruction::Add) { |
| if (Op0I->getOperand(0) == Op1) // (Y+X)-Y == X |
| return ReplaceInstUsesWith(I, Op0I->getOperand(1)); |
| else if (Op0I->getOperand(1) == Op1) // (X+Y)-Y == X |
| return ReplaceInstUsesWith(I, Op0I->getOperand(0)); |
| } else if (Op0I->getOpcode() == Instruction::Sub) { |
| if (Op0I->getOperand(0) == Op1) // (X-Y)-X == -Y |
| return BinaryOperator::createNeg(Op0I->getOperand(1), I.getName()); |
| } |
| |
| ConstantInt *C1; |
| if (Value *X = dyn_castFoldableMul(Op0, C1)) { |
| if (X == Op1) { // X*C - X --> X * (C-1) |
| Constant *CP1 = ConstantExpr::getSub(C1, ConstantInt::get(I.getType(),1)); |
| return BinaryOperator::createMul(Op1, CP1); |
| } |
| |
| ConstantInt *C2; // X*C1 - X*C2 -> X * (C1-C2) |
| if (X == dyn_castFoldableMul(Op1, C2)) |
| return BinaryOperator::createMul(Op1, ConstantExpr::getSub(C1, C2)); |
| } |
| return 0; |
| } |
| |
| /// isSignBitCheck - Given an exploded setcc instruction, return true if it is |
| /// really just returns true if the most significant (sign) bit is set. |
| static bool isSignBitCheck(unsigned Opcode, Value *LHS, ConstantInt *RHS) { |
| if (RHS->getType()->isSigned()) { |
| // True if source is LHS < 0 or LHS <= -1 |
| return Opcode == Instruction::SetLT && RHS->isNullValue() || |
| Opcode == Instruction::SetLE && RHS->isAllOnesValue(); |
| } else { |
| ConstantInt *RHSC = cast<ConstantInt>(RHS); |
| // True if source is LHS > 127 or LHS >= 128, where the constants depend on |
| // the size of the integer type. |
| if (Opcode == Instruction::SetGE) |
| return RHSC->getZExtValue() == |
| 1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1); |
| if (Opcode == Instruction::SetGT) |
| return RHSC->getZExtValue() == |
| (1ULL << (RHS->getType()->getPrimitiveSizeInBits()-1))-1; |
| } |
| return false; |
| } |
| |
| Instruction *InstCombiner::visitMul(BinaryOperator &I) { |
| bool Changed = SimplifyCommutative(I); |
| Value *Op0 = I.getOperand(0); |
| |
| if (isa<UndefValue>(I.getOperand(1))) // undef * X -> 0 |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| |
| // Simplify mul instructions with a constant RHS... |
| if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) { |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { |
| |
| // ((X << C1)*C2) == (X * (C2 << C1)) |
| if (ShiftInst *SI = dyn_cast<ShiftInst>(Op0)) |
| if (SI->getOpcode() == Instruction::Shl) |
| if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1))) |
| return BinaryOperator::createMul(SI->getOperand(0), |
| ConstantExpr::getShl(CI, ShOp)); |
| |
| if (CI->isNullValue()) |
| return ReplaceInstUsesWith(I, Op1); // X * 0 == 0 |
| if (CI->equalsInt(1)) // X * 1 == X |
| return ReplaceInstUsesWith(I, Op0); |
| if (CI->isAllOnesValue()) // X * -1 == 0 - X |
| return BinaryOperator::createNeg(Op0, I.getName()); |
| |
| int64_t Val = (int64_t)cast<ConstantInt>(CI)->getZExtValue(); |
| if (isPowerOf2_64(Val)) { // Replace X*(2^C) with X << C |
| uint64_t C = Log2_64(Val); |
| return new ShiftInst(Instruction::Shl, Op0, |
| ConstantInt::get(Type::UByteTy, C)); |
| } |
| } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) { |
| if (Op1F->isNullValue()) |
| return ReplaceInstUsesWith(I, Op1); |
| |
| // "In IEEE floating point, x*1 is not equivalent to x for nans. However, |
| // ANSI says we can drop signals, so we can do this anyway." (from GCC) |
| if (Op1F->getValue() == 1.0) |
| return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0' |
| } |
| |
| if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) |
| if (Op0I->getOpcode() == Instruction::Add && Op0I->hasOneUse() && |
| isa<ConstantInt>(Op0I->getOperand(1))) { |
| // 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); |
| |
| // If one of the operands of the multiply is a cast from a boolean value, then |
| // we know the bool is either zero or one, so this is a 'masking' multiply. |
| // See if we can simplify things based on how the boolean was originally |
| // formed. |
| CastInst *BoolCast = 0; |
| if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(0))) |
| if (CI->getOperand(0)->getType() == Type::BoolTy) |
| BoolCast = CI; |
| if (!BoolCast) |
| if (CastInst *CI = dyn_cast<CastInst>(I.getOperand(1))) |
| if (CI->getOperand(0)->getType() == Type::BoolTy) |
| BoolCast = CI; |
| if (BoolCast) { |
| if (SetCondInst *SCI = dyn_cast<SetCondInst>(BoolCast->getOperand(0))) { |
| Value *SCIOp0 = SCI->getOperand(0), *SCIOp1 = SCI->getOperand(1); |
| const Type *SCOpTy = SCIOp0->getType(); |
| |
| // If the setcc is true iff the sign bit of X is set, then convert this |
| // multiply into a shift/and combination. |
| if (isa<ConstantInt>(SCIOp1) && |
| isSignBitCheck(SCI->getOpcode(), SCIOp0, cast<ConstantInt>(SCIOp1))) { |
| // Shift the X value right to turn it into "all signbits". |
| Constant *Amt = ConstantInt::get(Type::UByteTy, |
| SCOpTy->getPrimitiveSizeInBits()-1); |
| if (SCIOp0->getType()->isUnsigned()) { |
| const Type *NewTy = SCIOp0->getType()->getSignedVersion(); |
| SCIOp0 = InsertCastBefore(SCIOp0, NewTy, I); |
| } |
| |
| Value *V = |
| InsertNewInstBefore(new ShiftInst(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()) |
| V = InsertCastBefore(V, I.getType(), I); |
| |
| Value *OtherOp = Op0 == BoolCast ? I.getOperand(1) : Op0; |
| return BinaryOperator::createAnd(V, OtherOp); |
| } |
| } |
| } |
| |
| return Changed ? &I : 0; |
| } |
| |
| /// 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 |
| if (isa<UndefValue>(Op0)) |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| |
| // X / undef -> undef |
| if (isa<UndefValue>(Op1)) |
| return ReplaceInstUsesWith(I, Op1); |
| |
| // Handle cases involving: div X, (select Cond, Y, Z) |
| if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) { |
| // div X, (Cond ? 0 : Y) -> div X, Y. If the div and the select are in the |
| // same basic block, then we replace the select with Y, and the condition |
| // of the select with false (if the cond value is in the same BB). If the |
| // select has uses other than the div, this allows them to be simplified |
| // also. Note that div X, Y is just as good as div X, 0 (undef) |
| if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1))) |
| if (ST->isNullValue()) { |
| Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0)); |
| if (CondI && CondI->getParent() == I.getParent()) |
| UpdateValueUsesWith(CondI, ConstantBool::getFalse()); |
| else if (I.getParent() != SI->getParent() || SI->hasOneUse()) |
| I.setOperand(1, SI->getOperand(2)); |
| else |
| UpdateValueUsesWith(SI, SI->getOperand(2)); |
| return &I; |
| } |
| |
| // Likewise for: div X, (Cond ? Y : 0) -> div X, Y |
| if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2))) |
| if (ST->isNullValue()) { |
| Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0)); |
| if (CondI && CondI->getParent() == I.getParent()) |
| UpdateValueUsesWith(CondI, ConstantBool::getTrue()); |
| else if (I.getParent() != SI->getParent() || SI->hasOneUse()) |
| I.setOperand(1, SI->getOperand(1)); |
| else |
| UpdateValueUsesWith(SI, SI->getOperand(1)); |
| return &I; |
| } |
| } |
| |
| 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); |
| |
| if (Instruction *Common = commonDivTransforms(I)) |
| return Common; |
| |
| 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))) { |
| return BinaryOperator::create(I.getOpcode(), LHS->getOperand(0), |
| ConstantExpr::getMul(RHS, LHSRHS)); |
| } |
| |
| if (!RHS->isNullValue()) { // 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())); |
| |
| 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; |
| |
| // 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 (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) { |
| if (uint64_t Val = C->getZExtValue()) // Don't break X / 0 |
| if (isPowerOf2_64(Val)) { |
| uint64_t ShiftAmt = Log2_64(Val); |
| return new ShiftInst(Instruction::LShr, Op0, |
| ConstantInt::get(Type::UByteTy, ShiftAmt)); |
| } |
| } |
| |
| // X udiv (C1 << N), where C1 is "1<<C2" --> X >> (N+C2) |
| if (ShiftInst *RHSI = dyn_cast<ShiftInst>(I.getOperand(1))) { |
| if (RHSI->getOpcode() == Instruction::Shl && |
| isa<ConstantInt>(RHSI->getOperand(0))) { |
| uint64_t C1 = cast<ConstantInt>(RHSI->getOperand(0))->getZExtValue(); |
| if (isPowerOf2_64(C1)) { |
| Value *N = RHSI->getOperand(1); |
| const Type *NTy = N->getType(); |
| if (uint64_t C2 = Log2_64(C1)) { |
| Constant *C2V = ConstantInt::get(NTy, C2); |
| N = InsertNewInstBefore(BinaryOperator::createAdd(N, C2V, "tmp"), I); |
| } |
| return new ShiftInst(Instruction::LShr, 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))) |
| if (!STO->isNullValue() && !STO->isNullValue()) { |
| uint64_t TVA = STO->getZExtValue(), FVA = SFO->getZExtValue(); |
| if (isPowerOf2_64(TVA) && isPowerOf2_64(FVA)) { |
| // Compute the shift amounts |
| unsigned TSA = Log2_64(TVA), FSA = Log2_64(FVA); |
| // Construct the "on true" case of the select |
| Constant *TC = ConstantInt::get(Type::UByteTy, TSA); |
| Instruction *TSI = |
| new ShiftInst(Instruction::LShr, Op0, TC, SI->getName()+".t"); |
| TSI = InsertNewInstBefore(TSI, I); |
| |
| // Construct the "on false" case of the select |
| Constant *FC = ConstantInt::get(Type::UByteTy, FSA); |
| Instruction *FSI = |
| new ShiftInst(Instruction::LShr, Op0, FC, SI->getName()+".f"); |
| FSI = InsertNewInstBefore(FSI, I); |
| |
| // construct the select instruction and return it. |
| return new SelectInst(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); |
| |
| // -X/C -> X/-C |
| if (Value *LHSNeg = dyn_castNegVal(Op0)) |
| return BinaryOperator::createSDiv(LHSNeg, ConstantExpr::getNeg(RHS)); |
| } |
| |
| // 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()) { |
| uint64_t Mask = 1ULL << (I.getType()->getPrimitiveSizeInBits()-1); |
| if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) { |
| return BinaryOperator::createUDiv(Op0, Op1, I.getName()); |
| } |
| } |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitFDiv(BinaryOperator &I) { |
| return commonDivTransforms(I); |
| } |
| |
| /// GetFactor - If we can prove that the specified value is at least a multiple |
| /// of some factor, return that factor. |
| static Constant *GetFactor(Value *V) { |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) |
| return CI; |
| |
| // Unless we can be tricky, we know this is a multiple of 1. |
| Constant *Result = ConstantInt::get(V->getType(), 1); |
| |
| Instruction *I = dyn_cast<Instruction>(V); |
| if (!I) return Result; |
| |
| if (I->getOpcode() == Instruction::Mul) { |
| // Handle multiplies by a constant, etc. |
| return ConstantExpr::getMul(GetFactor(I->getOperand(0)), |
| GetFactor(I->getOperand(1))); |
| } else if (I->getOpcode() == Instruction::Shl) { |
| // (X<<C) -> X * (1 << C) |
| if (Constant *ShRHS = dyn_cast<Constant>(I->getOperand(1))) { |
| ShRHS = ConstantExpr::getShl(Result, ShRHS); |
| return ConstantExpr::getMul(GetFactor(I->getOperand(0)), ShRHS); |
| } |
| } else if (I->getOpcode() == Instruction::And) { |
| if (ConstantInt *RHS = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| // X & 0xFFF0 is known to be a multiple of 16. |
| unsigned Zeros = CountTrailingZeros_64(RHS->getZExtValue()); |
| if (Zeros != V->getType()->getPrimitiveSizeInBits()) |
| return ConstantExpr::getShl(Result, |
| ConstantInt::get(Type::UByteTy, Zeros)); |
| } |
| } else if (CastInst *CI = dyn_cast<CastInst>(I)) { |
| // Only handle int->int casts. |
| if (!CI->isIntegerCast()) |
| return Result; |
| Value *Op = CI->getOperand(0); |
| return ConstantExpr::getCast(CI->getOpcode(), GetFactor(Op), V->getType()); |
| } |
| return Result; |
| } |
| |
| /// 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, 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 |
| 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 (SelectInst *SI = dyn_cast<SelectInst>(Op1)) { |
| // rem X, (Cond ? 0 : Y) -> rem X, Y. If the rem and the select are in |
| // the same basic block, then we replace the select with Y, and the |
| // condition of the select with false (if the cond value is in the same |
| // BB). If the select has uses other than the div, this allows them to be |
| // simplified also. |
| if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1))) |
| if (ST->isNullValue()) { |
| Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0)); |
| if (CondI && CondI->getParent() == I.getParent()) |
| UpdateValueUsesWith(CondI, ConstantBool::getFalse()); |
| else if (I.getParent() != SI->getParent() || SI->hasOneUse()) |
| I.setOperand(1, SI->getOperand(2)); |
| else |
| UpdateValueUsesWith(SI, SI->getOperand(2)); |
| return &I; |
| } |
| // Likewise for: rem X, (Cond ? Y : 0) -> rem X, Y |
| if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2))) |
| if (ST->isNullValue()) { |
| Instruction *CondI = dyn_cast<Instruction>(SI->getOperand(0)); |
| if (CondI && CondI->getParent() == I.getParent()) |
| UpdateValueUsesWith(CondI, ConstantBool::getTrue()); |
| else if (I.getParent() != SI->getParent() || SI->hasOneUse()) |
| I.setOperand(1, SI->getOperand(1)); |
| else |
| UpdateValueUsesWith(SI, SI->getOperand(1)); |
| 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; |
| } |
| // (X * C1) % C2 --> 0 iff C1 % C2 == 0 |
| if (ConstantExpr::getSRem(GetFactor(Op0I), RHS)->isNullValue()) |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| } |
| } |
| |
| 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 (isPowerOf2_64(C->getZExtValue())) |
| 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))) { |
| unsigned C1 = cast<ConstantInt>(RHSI->getOperand(0))->getZExtValue(); |
| if (isPowerOf2_64(C1)) { |
| 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 (isPowerOf2_64(STO->getZExtValue()) && |
| isPowerOf2_64(SFO->getZExtValue())) { |
| Value *TrueAnd = InsertNewInstBefore( |
| BinaryOperator::createAnd(Op0, SubOne(STO), SI->getName()+".t"), I); |
| Value *FalseAnd = InsertNewInstBefore( |
| BinaryOperator::createAnd(Op0, SubOne(SFO), SI->getName()+".f"), I); |
| return new SelectInst(SI->getOperand(0), TrueAnd, FalseAnd); |
| } |
| } |
| } |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitSRem(BinaryOperator &I) { |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| if (Instruction *common = commonIRemTransforms(I)) |
| return common; |
| |
| if (Value *RHSNeg = dyn_castNegVal(Op1)) |
| if (!isa<ConstantInt>(RHSNeg) || |
| cast<ConstantInt>(RHSNeg)->getSExtValue() > 0) { |
| // X % -Y -> X % Y |
| AddUsesToWorkList(I); |
| I.setOperand(1, RHSNeg); |
| return &I; |
| } |
| |
| // If the top bits of both operands are zero (i.e. we can prove they are |
| // unsigned inputs), turn this into a urem. |
| uint64_t Mask = 1ULL << (I.getType()->getPrimitiveSizeInBits()-1); |
| 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()); |
| } |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitFRem(BinaryOperator &I) { |
| return commonRemTransforms(I); |
| } |
| |
| // isMaxValueMinusOne - return true if this is Max-1 |
| static bool isMaxValueMinusOne(const ConstantInt *C) { |
| if (C->getType()->isUnsigned()) |
| return C->getZExtValue() == C->getType()->getIntegralTypeMask()-1; |
| |
| // Calculate 0111111111..11111 |
| unsigned TypeBits = C->getType()->getPrimitiveSizeInBits(); |
| int64_t Val = INT64_MAX; // All ones |
| Val >>= 64-TypeBits; // Shift out unwanted 1 bits... |
| return C->getSExtValue() == Val-1; |
| } |
| |
| // isMinValuePlusOne - return true if this is Min+1 |
| static bool isMinValuePlusOne(const ConstantInt *C) { |
| if (C->getType()->isUnsigned()) |
| return C->getZExtValue() == 1; |
| |
| // Calculate 1111111111000000000000 |
| unsigned TypeBits = C->getType()->getPrimitiveSizeInBits(); |
| int64_t Val = -1; // All ones |
| Val <<= TypeBits-1; // Shift over to the right spot |
| return C->getSExtValue() == Val+1; |
| } |
| |
| // isOneBitSet - Return true if there is exactly one bit set in the specified |
| // constant. |
| static bool isOneBitSet(const ConstantInt *CI) { |
| uint64_t V = CI->getZExtValue(); |
| return V && (V & (V-1)) == 0; |
| } |
| |
| #if 0 // Currently unused |
| // isLowOnes - Return true if the constant is of the form 0+1+. |
| static bool isLowOnes(const ConstantInt *CI) { |
| uint64_t V = CI->getZExtValue(); |
| |
| // There won't be bits set in parts that the type doesn't contain. |
| V &= ConstantInt::getAllOnesValue(CI->getType())->getZExtValue(); |
| |
| uint64_t U = V+1; // If it is low ones, this should be a power of two. |
| return U && V && (U & V) == 0; |
| } |
| #endif |
| |
| // isHighOnes - Return true if the constant is of the form 1+0+. |
| // This is the same as lowones(~X). |
| static bool isHighOnes(const ConstantInt *CI) { |
| uint64_t V = ~CI->getZExtValue(); |
| if (~V == 0) return false; // 0's does not match "1+" |
| |
| // There won't be bits set in parts that the type doesn't contain. |
| V &= ConstantInt::getAllOnesValue(CI->getType())->getZExtValue(); |
| |
| uint64_t U = V+1; // If it is low ones, this should be a power of two. |
| return U && V && (U & V) == 0; |
| } |
| |
| |
| /// getSetCondCode - Encode a setcc opcode into a three bit mask. These bits |
| /// are carefully arranged to allow folding of expressions such as: |
| /// |
| /// (A < B) | (A > B) --> (A != B) |
| /// |
| /// Bit value '4' represents that the comparison is true if A > B, bit value '2' |
| /// represents that the comparison is true if A == B, and bit value '1' is true |
| /// if A < B. |
| /// |
| static unsigned getSetCondCode(const SetCondInst *SCI) { |
| switch (SCI->getOpcode()) { |
| // False -> 0 |
| case Instruction::SetGT: return 1; |
| case Instruction::SetEQ: return 2; |
| case Instruction::SetGE: return 3; |
| case Instruction::SetLT: return 4; |
| case Instruction::SetNE: return 5; |
| case Instruction::SetLE: return 6; |
| // True -> 7 |
| default: |
| assert(0 && "Invalid SetCC opcode!"); |
| return 0; |
| } |
| } |
| |
| /// getSetCCValue - This is the complement of getSetCondCode, which turns an |
| /// opcode and two operands into either a constant true or false, or a brand new |
| /// SetCC instruction. |
| static Value *getSetCCValue(unsigned Opcode, Value *LHS, Value *RHS) { |
| switch (Opcode) { |
| case 0: return ConstantBool::getFalse(); |
| case 1: return new SetCondInst(Instruction::SetGT, LHS, RHS); |
| case 2: return new SetCondInst(Instruction::SetEQ, LHS, RHS); |
| case 3: return new SetCondInst(Instruction::SetGE, LHS, RHS); |
| case 4: return new SetCondInst(Instruction::SetLT, LHS, RHS); |
| case 5: return new SetCondInst(Instruction::SetNE, LHS, RHS); |
| case 6: return new SetCondInst(Instruction::SetLE, LHS, RHS); |
| case 7: return ConstantBool::getTrue(); |
| default: assert(0 && "Illegal SetCCCode!"); return 0; |
| } |
| } |
| |
| // FoldSetCCLogical - Implements (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B) |
| namespace { |
| struct FoldSetCCLogical { |
| InstCombiner &IC; |
| Value *LHS, *RHS; |
| FoldSetCCLogical(InstCombiner &ic, SetCondInst *SCI) |
| : IC(ic), LHS(SCI->getOperand(0)), RHS(SCI->getOperand(1)) {} |
| bool shouldApply(Value *V) const { |
| if (SetCondInst *SCI = dyn_cast<SetCondInst>(V)) |
| return (SCI->getOperand(0) == LHS && SCI->getOperand(1) == RHS || |
| SCI->getOperand(0) == RHS && SCI->getOperand(1) == LHS); |
| return false; |
| } |
| Instruction *apply(BinaryOperator &Log) const { |
| SetCondInst *SCI = cast<SetCondInst>(Log.getOperand(0)); |
| if (SCI->getOperand(0) != LHS) { |
| assert(SCI->getOperand(1) == LHS); |
| SCI->swapOperands(); // Swap the LHS and RHS of the SetCC |
| } |
| |
| unsigned LHSCode = getSetCondCode(SCI); |
| unsigned RHSCode = getSetCondCode(cast<SetCondInst>(Log.getOperand(1))); |
| unsigned Code; |
| switch (Log.getOpcode()) { |
| case Instruction::And: Code = LHSCode & RHSCode; break; |
| case Instruction::Or: Code = LHSCode | RHSCode; break; |
| case Instruction::Xor: Code = LHSCode ^ RHSCode; break; |
| default: assert(0 && "Illegal logical opcode!"); return 0; |
| } |
| |
| Value *RV = getSetCCValue(Code, LHS, RHS); |
| if (Instruction *I = dyn_cast<Instruction>(RV)) |
| return I; |
| // Otherwise, it's a constant boolean value... |
| return IC.ReplaceInstUsesWith(Log, RV); |
| } |
| }; |
| } // 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 either a shift instruction or a binary operator. |
| Instruction *InstCombiner::OptAndOp(Instruction *Op, |
| ConstantIntegral *OpRHS, |
| ConstantIntegral *AndRHS, |
| BinaryOperator &TheAnd) { |
| Value *X = Op->getOperand(0); |
| Constant *Together = 0; |
| if (!isa<ShiftInst>(Op)) |
| Together = ConstantExpr::getAnd(AndRHS, OpRHS); |
| |
| switch (Op->getOpcode()) { |
| case Instruction::Xor: |
| if (Op->hasOneUse()) { |
| // (X ^ C1) & C2 --> (X & C2) ^ (C1&C2) |
| std::string OpName = Op->getName(); Op->setName(""); |
| Instruction *And = BinaryOperator::createAnd(X, AndRHS, OpName); |
| InsertNewInstBefore(And, TheAnd); |
| return BinaryOperator::createXor(And, Together); |
| } |
| break; |
| case Instruction::Or: |
| if (Together == AndRHS) // (X | C) & C --> C |
| return ReplaceInstUsesWith(TheAnd, AndRHS); |
| |
| if (Op->hasOneUse() && Together != OpRHS) { |
| // (X | C1) & C2 --> (X | (C1&C2)) & C2 |
| std::string Op0Name = Op->getName(); Op->setName(""); |
| Instruction *Or = BinaryOperator::createOr(X, Together, Op0Name); |
| InsertNewInstBefore(Or, TheAnd); |
| return BinaryOperator::createAnd(Or, AndRHS); |
| } |
| break; |
| case Instruction::Add: |
| if (Op->hasOneUse()) { |
| // Adding a one to a single bit bit-field should be turned into an XOR |
| // of the bit. First thing to check is to see if this AND is with a |
| // single bit constant. |
| uint64_t AndRHSV = cast<ConstantInt>(AndRHS)->getZExtValue(); |
| |
| // Clear bits that are not part of the constant. |
| AndRHSV &= AndRHS->getType()->getIntegralTypeMask(); |
| |
| // If there is only one bit set... |
| if (isOneBitSet(cast<ConstantInt>(AndRHS))) { |
| // Ok, at this point, we know that we are masking the result of the |
| // ADD down to exactly one bit. If the constant we are adding has |
| // no bits set below this bit, then we can eliminate the ADD. |
| uint64_t AddRHS = cast<ConstantInt>(OpRHS)->getZExtValue(); |
| |
| // Check to see if any bits below the one bit set in AndRHSV are set. |
| if ((AddRHS & (AndRHSV-1)) == 0) { |
| // If not, the only thing that can effect the output of the AND is |
| // the bit specified by AndRHSV. If that bit is set, the effect of |
| // the XOR is to toggle the bit. If it is clear, then the ADD has |
| // no effect. |
| if ((AddRHS & AndRHSV) == 0) { // Bit is not set, noop |
| TheAnd.setOperand(0, X); |
| return &TheAnd; |
| } else { |
| std::string Name = Op->getName(); Op->setName(""); |
| // Pull the XOR out of the AND. |
| Instruction *NewAnd = BinaryOperator::createAnd(X, AndRHS, Name); |
| InsertNewInstBefore(NewAnd, TheAnd); |
| return BinaryOperator::createXor(NewAnd, AndRHS); |
| } |
| } |
| } |
| } |
| break; |
| |
| case Instruction::Shl: { |
| // We know that the AND will not produce any of the bits shifted in, so if |
| // the anded constant includes them, clear them now! |
| // |
| Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType()); |
| Constant *ShlMask = ConstantExpr::getShl(AllOne, OpRHS); |
| Constant *CI = ConstantExpr::getAnd(AndRHS, ShlMask); |
| |
| if (CI == ShlMask) { // Masking out bits that the shift already masks |
| return ReplaceInstUsesWith(TheAnd, Op); // No need for the and. |
| } else if (CI != AndRHS) { // Reducing bits set in and. |
| TheAnd.setOperand(1, CI); |
| return &TheAnd; |
| } |
| break; |
| } |
| case Instruction::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! |
| // |
| Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType()); |
| Constant *ShrMask = ConstantExpr::getLShr(AllOne, OpRHS); |
| Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask); |
| |
| if (CI == ShrMask) { // Masking out bits that the shift already masks. |
| return ReplaceInstUsesWith(TheAnd, Op); |
| } else if (CI != AndRHS) { |
| TheAnd.setOperand(1, CI); // Reduce bits set in and cst. |
| return &TheAnd; |
| } |
| 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()) { |
| Constant *AllOne = ConstantIntegral::getAllOnesValue(AndRHS->getType()); |
| Constant *ShrMask = ConstantExpr::getLShr(AllOne, OpRHS); |
| Constant *CI = ConstantExpr::getAnd(AndRHS, ShrMask); |
| if (CI == AndRHS) { // Masking out bits shifted in. |
| // Make the argument unsigned. |
| Value *ShVal = Op->getOperand(0); |
| ShVal = InsertNewInstBefore(new ShiftInst(Instruction::LShr, ShVal, |
| OpRHS, Op->getName()), |
| TheAnd); |
| Value *AndRHS2 = ConstantExpr::getCast(AndRHS, ShVal->getType()); |
| return BinaryOperator::createAnd(ShVal, AndRHS2, 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. IB is the location to |
| /// insert new instructions. |
| Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi, |
| bool Inside, Instruction &IB) { |
| assert(cast<ConstantBool>(ConstantExpr::getSetLE(Lo, Hi))->getValue() && |
| "Lo is not <= Hi in range emission code!"); |
| if (Inside) { |
| if (Lo == Hi) // Trivially false. |
| return new SetCondInst(Instruction::SetNE, V, V); |
| if (cast<ConstantIntegral>(Lo)->isMinValue()) |
| return new SetCondInst(Instruction::SetLT, V, Hi); |
| |
| Constant *AddCST = ConstantExpr::getNeg(Lo); |
| Instruction *Add = BinaryOperator::createAdd(V, AddCST,V->getName()+".off"); |
| InsertNewInstBefore(Add, IB); |
| // Convert to unsigned for the comparison. |
| const Type *UnsType = Add->getType()->getUnsignedVersion(); |
| Value *OffsetVal = InsertCastBefore(Add, UnsType, IB); |
| AddCST = ConstantExpr::getAdd(AddCST, Hi); |
| AddCST = ConstantExpr::getCast(AddCST, UnsType); |
| return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST); |
| } |
| |
| if (Lo == Hi) // Trivially true. |
| return new SetCondInst(Instruction::SetEQ, V, V); |
| |
| Hi = SubOne(cast<ConstantInt>(Hi)); |
| |
| // V < 0 || V >= Hi ->'V > Hi-1' |
| if (cast<ConstantIntegral>(Lo)->isMinValue()) |
| return new SetCondInst(Instruction::SetGT, V, Hi); |
| |
| // Emit X-Lo > Hi-Lo-1 |
| Constant *AddCST = ConstantExpr::getNeg(Lo); |
| Instruction *Add = BinaryOperator::createAdd(V, AddCST, V->getName()+".off"); |
| InsertNewInstBefore(Add, IB); |
| // Convert to unsigned for the comparison. |
| const Type *UnsType = Add->getType()->getUnsignedVersion(); |
| Value *OffsetVal = InsertCastBefore(Add, UnsType, IB); |
| AddCST = ConstantExpr::getAdd(AddCST, Hi); |
| AddCST = ConstantExpr::getCast(AddCST, UnsType); |
| return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST); |
| } |
| |
| // isRunOfOnes - Returns true iff Val consists of one contiguous run of 1s with |
| // any number of 0s on either side. The 1s are allowed to wrap from LSB to |
| // MSB, so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is |
| // not, since all 1s are not contiguous. |
| static bool isRunOfOnes(ConstantIntegral *Val, unsigned &MB, unsigned &ME) { |
| uint64_t V = Val->getZExtValue(); |
| if (!isShiftedMask_64(V)) return false; |
| |
| // look for the first zero bit after the run of ones |
| MB = 64-CountLeadingZeros_64((V - 1) ^ V); |
| // look for the first non-zero bit |
| ME = 64-CountLeadingZeros_64(V); |
| return true; |
| } |
| |
| |
| |
| /// FoldLogicalPlusAnd - This is part of an expression (LHS +/- RHS) & Mask, |
| /// where isSub determines whether the operator is a sub. If we can fold one of |
| /// the following xforms: |
| /// |
| /// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask |
| /// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0 |
| /// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0 |
| /// |
| /// return (A +/- B). |
| /// |
| Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS, |
| ConstantIntegral *Mask, bool isSub, |
| Instruction &I) { |
| Instruction *LHSI = dyn_cast<Instruction>(LHS); |
| if (!LHSI || LHSI->getNumOperands() != 2 || |
| !isa<ConstantInt>(LHSI->getOperand(1))) return 0; |
| |
| ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1)); |
| |
| switch (LHSI->getOpcode()) { |
| default: return 0; |
| case Instruction::And: |
| if (ConstantExpr::getAnd(N, Mask) == Mask) { |
| // If the AndRHS is a power of two minus one (0+1+), this is simple. |
| if ((Mask->getZExtValue() & Mask->getZExtValue()+1) == 0) |
| break; |
| |
| // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+ |
| // part, we don't need any explicit masks to take them out of A. If that |
| // is all N is, ignore it. |
| unsigned MB, ME; |
| if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive |
| uint64_t Mask = RHS->getType()->getIntegralTypeMask(); |
| Mask >>= 64-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->getZExtValue() & Mask->getZExtValue()+1) == 0 && |
| ConstantExpr::getAnd(N, Mask)->isNullValue()) |
| break; |
| return 0; |
| } |
| |
| Instruction *New; |
| if (isSub) |
| New = BinaryOperator::createSub(LHSI->getOperand(0), RHS, "fold"); |
| else |
| New = BinaryOperator::createAdd(LHSI->getOperand(0), RHS, "fold"); |
| return InsertNewInstBefore(New, I); |
| } |
| |
| Instruction *InstCombiner::visitAnd(BinaryOperator &I) { |
| bool Changed = SimplifyCommutative(I); |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| if (isa<UndefValue>(Op1)) // X & undef -> 0 |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| |
| // and X, X = X |
| if (Op0 == Op1) |
| return ReplaceInstUsesWith(I, Op1); |
| |
| // See if we can simplify any instructions used by the instruction whose sole |
| // purpose is to compute bits we don't care about. |
| uint64_t KnownZero, KnownOne; |
| if (!isa<PackedType>(I.getType()) && |
| SimplifyDemandedBits(&I, I.getType()->getIntegralTypeMask(), |
| KnownZero, KnownOne)) |
| return &I; |
| |
| if (ConstantIntegral *AndRHS = dyn_cast<ConstantIntegral>(Op1)) { |
| uint64_t AndRHSMask = AndRHS->getZExtValue(); |
| uint64_t TypeMask = Op0->getType()->getIntegralTypeMask(); |
| uint64_t NotAndRHS = AndRHSMask^TypeMask; |
| |
| // Optimize a variety of ((val OP C1) & C2) combinations... |
| if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(Op0)) { |
| Instruction *Op0I = cast<Instruction>(Op0); |
| Value *Op0LHS = Op0I->getOperand(0); |
| Value *Op0RHS = Op0I->getOperand(1); |
| switch (Op0I->getOpcode()) { |
| case Instruction::Xor: |
| case Instruction::Or: |
| // 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); |
| 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::createInferredCast(CastOp->getOperand(0), I.getType(), |
| CastOp->getName()+".shrunk"); |
| NewCast = InsertNewInstBefore(NewCast, I); |
| // trunc_or_bitcast(C1)&C2 |
| Instruction::CastOps opc = ( |
| AndCI->getType()->getPrimitiveSizeInBits() == |
| I.getType()->getPrimitiveSizeInBits() ? |
| Instruction::BitCast : Instruction::Trunc); |
| Constant *C3 = ConstantExpr::getCast(opc, 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::getCast(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; |
| if (match(Op0, m_Or(m_Value(A), m_Value(B)))) |
| if (A == Op1 || B == Op1) // (A | ?) & A --> A |
| return ReplaceInstUsesWith(I, Op1); |
| if (match(Op1, m_Or(m_Value(A), m_Value(B)))) |
| if (A == Op0 || B == Op0) // A & (A | ?) --> A |
| return ReplaceInstUsesWith(I, Op0); |
| |
| 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); |
| } |
| } |
| } |
| |
| |
| if (SetCondInst *RHS = dyn_cast<SetCondInst>(Op1)) { |
| // (setcc1 A, B) & (setcc2 A, B) --> (setcc3 A, B) |
| if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS))) |
| return R; |
| |
| Value *LHSVal, *RHSVal; |
| ConstantInt *LHSCst, *RHSCst; |
| Instruction::BinaryOps LHSCC, RHSCC; |
| if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst)))) |
| if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst)))) |
| if (LHSVal == RHSVal && // Found (X setcc C1) & (X setcc C2) |
| // Set[GL]E X, CST is folded to Set[GL]T elsewhere. |
| LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE && |
| RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) { |
| // Ensure that the larger constant is on the RHS. |
| Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst); |
| SetCondInst *LHS = cast<SetCondInst>(Op0); |
| if (cast<ConstantBool>(Cmp)->getValue()) { |
| std::swap(LHS, RHS); |
| std::swap(LHSCst, RHSCst); |
| std::swap(LHSCC, RHSCC); |
| } |
| |
| // At this point, we know we have have two setcc instructions |
| // comparing a value against two constants and and'ing the result |
| // together. Because of the above check, we know that we only have |
| // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the |
| // FoldSetCCLogical check above), that the two constants are not |
| // equal. |
| assert(LHSCst != RHSCst && "Compares not folded above?"); |
| |
| switch (LHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case Instruction::SetEQ: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case Instruction::SetEQ: // (X == 13 & X == 15) -> false |
| case Instruction::SetGT: // (X == 13 & X > 15) -> false |
| return ReplaceInstUsesWith(I, ConstantBool::getFalse()); |
| case Instruction::SetNE: // (X == 13 & X != 15) -> X == 13 |
| case Instruction::SetLT: // (X == 13 & X < 15) -> X == 13 |
| return ReplaceInstUsesWith(I, LHS); |
| } |
| case Instruction::SetNE: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case Instruction::SetLT: |
| if (LHSCst == SubOne(RHSCst)) // (X != 13 & X < 14) -> X < 13 |
| return new SetCondInst(Instruction::SetLT, LHSVal, LHSCst); |
| break; // (X != 13 & X < 15) -> no change |
| case Instruction::SetEQ: // (X != 13 & X == 15) -> X == 15 |
| case Instruction::SetGT: // (X != 13 & X > 15) -> X > 15 |
| return ReplaceInstUsesWith(I, RHS); |
| case Instruction::SetNE: |
| if (LHSCst == SubOne(RHSCst)) {// (X != 13 & X != 14) -> X-13 >u 1 |
| Constant *AddCST = ConstantExpr::getNeg(LHSCst); |
| Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST, |
| LHSVal->getName()+".off"); |
| InsertNewInstBefore(Add, I); |
| const Type *UnsType = Add->getType()->getUnsignedVersion(); |
| Value *OffsetVal = InsertCastBefore(Add, UnsType, I); |
| AddCST = ConstantExpr::getSub(RHSCst, LHSCst); |
| AddCST = ConstantExpr::getCast(AddCST, UnsType); |
| return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST); |
| } |
| break; // (X != 13 & X != 15) -> no change |
| } |
| break; |
| case Instruction::SetLT: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case Instruction::SetEQ: // (X < 13 & X == 15) -> false |
| case Instruction::SetGT: // (X < 13 & X > 15) -> false |
| return ReplaceInstUsesWith(I, ConstantBool::getFalse()); |
| case Instruction::SetNE: // (X < 13 & X != 15) -> X < 13 |
| case Instruction::SetLT: // (X < 13 & X < 15) -> X < 13 |
| return ReplaceInstUsesWith(I, LHS); |
| } |
| case Instruction::SetGT: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case Instruction::SetEQ: // (X > 13 & X == 15) -> X > 13 |
| return ReplaceInstUsesWith(I, LHS); |
| case Instruction::SetGT: // (X > 13 & X > 15) -> X > 15 |
| return ReplaceInstUsesWith(I, RHS); |
| case Instruction::SetNE: |
| if (RHSCst == AddOne(LHSCst)) // (X > 13 & X != 14) -> X > 14 |
| return new SetCondInst(Instruction::SetGT, LHSVal, RHSCst); |
| break; // (X > 13 & X != 15) -> no change |
| case Instruction::SetLT: // (X > 13 & X < 15) -> (X-14) <u 1 |
| return InsertRangeTest(LHSVal, AddOne(LHSCst), RHSCst, true, I); |
| } |
| } |
| } |
| } |
| |
| // fold (and (cast A), (cast B)) -> (cast (and A, B)) |
| if (CastInst *Op1C = dyn_cast<CastInst>(Op1)) { |
| if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) { |
| const Type *SrcTy = Op0C->getOperand(0)->getType(); |
| if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isIntegral() && |
| // Only do this if the casts both really cause code to be generated. |
| ValueRequiresCast(Op0C->getOperand(0), I.getType(), TD) && |
| ValueRequiresCast(Op1C->getOperand(0), I.getType(), TD)) { |
| Instruction *NewOp = BinaryOperator::createAnd(Op0C->getOperand(0), |
| Op1C->getOperand(0), |
| I.getName()); |
| InsertNewInstBefore(NewOp, I); |
| return CastInst::createInferredCast(NewOp, I.getType()); |
| } |
| } |
| } |
| |
| // (X >> Z) & (Y >> Z) -> (X&Y) >> Z for all shifts. |
| if (ShiftInst *SI1 = dyn_cast<ShiftInst>(Op1)) { |
| if (ShiftInst *SI0 = dyn_cast<ShiftInst>(Op0)) |
| if (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 new ShiftInst(SI1->getOpcode(), NewOp, SI1->getOperand(1)); |
| } |
| } |
| |
| return Changed ? &I : 0; |
| } |
| |
| /// CollectBSwapParts - Look to see if the specified value defines a single byte |
| /// in the result. If it does, and if the specified byte hasn't been filled in |
| /// yet, fill it in and return false. |
| static bool CollectBSwapParts(Value *V, std::vector<Value*> &ByteValues) { |
| Instruction *I = dyn_cast<Instruction>(V); |
| if (I == 0) return true; |
| |
| // If this is an or instruction, it is an inner node of the bswap. |
| if (I->getOpcode() == Instruction::Or) |
| return CollectBSwapParts(I->getOperand(0), ByteValues) || |
| CollectBSwapParts(I->getOperand(1), ByteValues); |
| |
| // If this is a shift by a constant int, and it is "24", then its operand |
| // defines a byte. We only handle unsigned types here. |
| if (isa<ShiftInst>(I) && isa<ConstantInt>(I->getOperand(1))) { |
| // Not shifting the entire input by N-1 bytes? |
| if (cast<ConstantInt>(I->getOperand(1))->getZExtValue() != |
| 8*(ByteValues.size()-1)) |
| return true; |
| |
| unsigned DestNo; |
| if (I->getOpcode() == Instruction::Shl) { |
| // X << 24 defines the top byte with the lowest of the input bytes. |
| DestNo = ByteValues.size()-1; |
| } else { |
| // X >>u 24 defines the low byte with the highest of the input bytes. |
| DestNo = 0; |
| } |
| |
| // 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[DestNo] && ByteValues[DestNo] != I->getOperand(0)) |
| return true; |
| ByteValues[DestNo] = I->getOperand(0); |
| return false; |
| } |
| |
| // Otherwise, we can only handle and(shift X, imm), imm). Bail out of if we |
| // don't have this. |
| Value *Shift = 0, *ShiftLHS = 0; |
| ConstantInt *AndAmt = 0, *ShiftAmt = 0; |
| if (!match(I, m_And(m_Value(Shift), m_ConstantInt(AndAmt))) || |
| !match(Shift, m_Shift(m_Value(ShiftLHS), m_ConstantInt(ShiftAmt)))) |
| return true; |
| Instruction *SI = cast<Instruction>(Shift); |
| |
| // Make sure that the shift amount is by a multiple of 8 and isn't too big. |
| if (ShiftAmt->getZExtValue() & 7 || |
| ShiftAmt->getZExtValue() > 8*ByteValues.size()) |
| return true; |
| |
| // Turn 0xFF -> 0, 0xFF00 -> 1, 0xFF0000 -> 2, etc. |
| unsigned DestByte; |
| for (DestByte = 0; DestByte != ByteValues.size(); ++DestByte) |
| if (AndAmt->getZExtValue() == uint64_t(0xFF) << 8*DestByte) |
| break; |
| // Unknown mask for bswap. |
| if (DestByte == ByteValues.size()) return true; |
| |
| unsigned ShiftBytes = ShiftAmt->getZExtValue()/8; |
| unsigned SrcByte; |
| if (SI->getOpcode() == Instruction::Shl) |
| SrcByte = DestByte - ShiftBytes; |
| else |
| SrcByte = DestByte + ShiftBytes; |
| |
| // If the SrcByte isn't a bswapped value from the DestByte, reject it. |
| if (SrcByte != ByteValues.size()-DestByte-1) |
| 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[DestByte] && ByteValues[DestByte] != SI->getOperand(0)) |
| return true; |
| ByteValues[DestByte] = SI->getOperand(0); |
| 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) { |
| // We can only handle bswap of unsigned integers, and cannot bswap one byte. |
| if (!I.getType()->isUnsigned() || I.getType() == Type::UByteTy) |
| return 0; |
| |
| /// ByteValues - For each byte of the result, we keep track of which value |
| /// defines each byte. |
| std::vector<Value*> ByteValues; |
| ByteValues.resize(I.getType()->getPrimitiveSize()); |
| |
| // Try to find all the pieces corresponding to the bswap. |
| if (CollectBSwapParts(I.getOperand(0), ByteValues) || |
| CollectBSwapParts(I.getOperand(1), 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; |
| |
| // If they do then *success* we can turn this into a bswap. Figure out what |
| // bswap to make it into. |
| Module *M = I.getParent()->getParent()->getParent(); |
| const char *FnName = 0; |
| if (I.getType() == Type::UShortTy) |
| FnName = "llvm.bswap.i16"; |
| else if (I.getType() == Type::UIntTy) |
| FnName = "llvm.bswap.i32"; |
| else if (I.getType() == Type::ULongTy) |
| FnName = "llvm.bswap.i64"; |
| else |
| assert(0 && "Unknown integer type!"); |
| Function *F = M->getOrInsertFunction(FnName, I.getType(), I.getType(), NULL); |
| |
| return new CallInst(F, V); |
| } |
| |
| |
| Instruction *InstCombiner::visitOr(BinaryOperator &I) { |
| bool Changed = SimplifyCommutative(I); |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| if (isa<UndefValue>(Op1)) |
| return ReplaceInstUsesWith(I, // X | undef -> -1 |
| ConstantIntegral::getAllOnesValue(I.getType())); |
| |
| // or X, X = X |
| 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. |
| uint64_t KnownZero, KnownOne; |
| if (!isa<PackedType>(I.getType()) && |
| SimplifyDemandedBits(&I, I.getType()->getIntegralTypeMask(), |
| KnownZero, KnownOne)) |
| return &I; |
| |
| // or X, -1 == -1 |
| if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(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, Op0->getName()); |
| Op0->setName(""); |
| InsertNewInstBefore(Or, I); |
| return BinaryOperator::createAnd(Or, ConstantExpr::getOr(RHS, C1)); |
| } |
| |
| // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2) |
| if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) && isOnlyUse(Op0)) { |
| std::string Op0Name = Op0->getName(); Op0->setName(""); |
| Instruction *Or = BinaryOperator::createOr(X, RHS, Op0Name); |
| InsertNewInstBefore(Or, I); |
| return BinaryOperator::createXor(Or, |
| ConstantExpr::getAnd(C1, ConstantExpr::getNot(RHS))); |
| } |
| |
| // Try to fold constant and into select arguments. |
| if (SelectInst *SI = dyn_cast<SelectInst>(Op0)) |
| if (Instruction *R = FoldOpIntoSelect(I, SI, this)) |
| return R; |
| if (isa<PHINode>(Op0)) |
| if (Instruction *NV = FoldOpIntoPhi(I)) |
| return NV; |
| } |
| |
| Value *A = 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->getZExtValue())) { |
| Instruction *NOr = BinaryOperator::createOr(A, Op1, Op0->getName()); |
| Op0->setName(""); |
| return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1); |
| } |
| |
| // Y|(X^C) -> (X|Y)^C iff Y&C == 0 |
| if (Op1->hasOneUse() && match(Op1, m_Xor(m_Value(A), m_ConstantInt(C1))) && |
| MaskedValueIsZero(Op0, C1->getZExtValue())) { |
| Instruction *NOr = BinaryOperator::createOr(A, Op0, Op1->getName()); |
| Op0->setName(""); |
| return BinaryOperator::createXor(InsertNewInstBefore(NOr, I), C1); |
| } |
| |
| // (A & C1)|(B & C2) |
| if (match(Op0, m_And(m_Value(A), m_ConstantInt(C1))) && |
| match(Op1, m_And(m_Value(B), m_ConstantInt(C2)))) { |
| |
| if (A == B) // (A & C1)|(A & C2) == A & (C1|C2) |
| return BinaryOperator::createAnd(A, ConstantExpr::getOr(C1, C2)); |
| |
| |
| // If we have: ((V + N) & C1) | (V & C2) |
| // .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0 |
| // replace with V+N. |
| if (C1 == ConstantExpr::getNot(C2)) { |
| Value *V1 = 0, *V2 = 0; |
| if ((C2->getZExtValue() & (C2->getZExtValue()+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->getZExtValue())) |
| return ReplaceInstUsesWith(I, A); |
| if (V2 == B && MaskedValueIsZero(V1, C2->getZExtValue())) |
| return ReplaceInstUsesWith(I, A); |
| } |
| // Or commutes, try both ways. |
| if ((C1->getZExtValue() & (C1->getZExtValue()+1)) == 0 && |
| match(B, m_Add(m_Value(V1), m_Value(V2)))) { |
| // Add commutes, try both ways. |
| if (V1 == A && MaskedValueIsZero(V2, C1->getZExtValue())) |
| return ReplaceInstUsesWith(I, B); |
| if (V2 == A && MaskedValueIsZero(V1, C1->getZExtValue())) |
| return ReplaceInstUsesWith(I, B); |
| } |
| } |
| } |
| |
| // (X >> Z) | (Y >> Z) -> (X|Y) >> Z for all shifts. |
| if (ShiftInst *SI1 = dyn_cast<ShiftInst>(Op1)) { |
| if (ShiftInst *SI0 = dyn_cast<ShiftInst>(Op0)) |
| if (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 new ShiftInst(SI1->getOpcode(), NewOp, SI1->getOperand(1)); |
| } |
| } |
| |
| if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1 |
| if (A == Op1) // ~A | A == -1 |
| return ReplaceInstUsesWith(I, |
| ConstantIntegral::getAllOnesValue(I.getType())); |
| } else { |
| A = 0; |
| } |
| // Note, A is still live here! |
| if (match(Op1, m_Not(m_Value(B)))) { // Op0 | ~B |
| if (Op0 == B) |
| return ReplaceInstUsesWith(I, |
| ConstantIntegral::getAllOnesValue(I.getType())); |
| |
| // (~A | ~B) == (~(A & B)) - De Morgan's Law |
| if (A && isOnlyUse(Op0) && isOnlyUse(Op1)) { |
| Value *And = InsertNewInstBefore(BinaryOperator::createAnd(A, B, |
| I.getName()+".demorgan"), I); |
| return BinaryOperator::createNot(And); |
| } |
| } |
| |
| // (setcc1 A, B) | (setcc2 A, B) --> (setcc3 A, B) |
| if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1))) { |
| if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS))) |
| return R; |
| |
| Value *LHSVal, *RHSVal; |
| ConstantInt *LHSCst, *RHSCst; |
| Instruction::BinaryOps LHSCC, RHSCC; |
| if (match(Op0, m_SetCond(LHSCC, m_Value(LHSVal), m_ConstantInt(LHSCst)))) |
| if (match(RHS, m_SetCond(RHSCC, m_Value(RHSVal), m_ConstantInt(RHSCst)))) |
| if (LHSVal == RHSVal && // Found (X setcc C1) | (X setcc C2) |
| // Set[GL]E X, CST is folded to Set[GL]T elsewhere. |
| LHSCC != Instruction::SetGE && LHSCC != Instruction::SetLE && |
| RHSCC != Instruction::SetGE && RHSCC != Instruction::SetLE) { |
| // Ensure that the larger constant is on the RHS. |
| Constant *Cmp = ConstantExpr::getSetGT(LHSCst, RHSCst); |
| SetCondInst *LHS = cast<SetCondInst>(Op0); |
| if (cast<ConstantBool>(Cmp)->getValue()) { |
| std::swap(LHS, RHS); |
| std::swap(LHSCst, RHSCst); |
| std::swap(LHSCC, RHSCC); |
| } |
| |
| // At this point, we know we have have two setcc instructions |
| // comparing a value against two constants and or'ing the result |
| // together. Because of the above check, we know that we only have |
| // SetEQ, SetNE, SetLT, and SetGT here. We also know (from the |
| // FoldSetCCLogical check above), that the two constants are not |
| // equal. |
| assert(LHSCst != RHSCst && "Compares not folded above?"); |
| |
| switch (LHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case Instruction::SetEQ: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case Instruction::SetEQ: |
| if (LHSCst == SubOne(RHSCst)) {// (X == 13 | X == 14) -> X-13 <u 2 |
| Constant *AddCST = ConstantExpr::getNeg(LHSCst); |
| Instruction *Add = BinaryOperator::createAdd(LHSVal, AddCST, |
| LHSVal->getName()+".off"); |
| InsertNewInstBefore(Add, I); |
| const Type *UnsType = Add->getType()->getUnsignedVersion(); |
| Value *OffsetVal = InsertCastBefore(Add, UnsType, I); |
| AddCST = ConstantExpr::getSub(AddOne(RHSCst), LHSCst); |
| AddCST = ConstantExpr::getCast(AddCST, UnsType); |
| return new SetCondInst(Instruction::SetLT, OffsetVal, AddCST); |
| } |
| break; // (X == 13 | X == 15) -> no change |
| |
| case Instruction::SetGT: // (X == 13 | X > 14) -> no change |
| break; |
| case Instruction::SetNE: // (X == 13 | X != 15) -> X != 15 |
| case Instruction::SetLT: // (X == 13 | X < 15) -> X < 15 |
| return ReplaceInstUsesWith(I, RHS); |
| } |
| break; |
| case Instruction::SetNE: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case Instruction::SetEQ: // (X != 13 | X == 15) -> X != 13 |
| case Instruction::SetGT: // (X != 13 | X > 15) -> X != 13 |
| return ReplaceInstUsesWith(I, LHS); |
| case Instruction::SetNE: // (X != 13 | X != 15) -> true |
| case Instruction::SetLT: // (X != 13 | X < 15) -> true |
| return ReplaceInstUsesWith(I, ConstantBool::getTrue()); |
| } |
| break; |
| case Instruction::SetLT: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case Instruction::SetEQ: // (X < 13 | X == 14) -> no change |
| break; |
| case Instruction::SetGT: // (X < 13 | X > 15) -> (X-13) > 2 |
| return InsertRangeTest(LHSVal, LHSCst, AddOne(RHSCst), false, I); |
| case Instruction::SetNE: // (X < 13 | X != 15) -> X != 15 |
| case Instruction::SetLT: // (X < 13 | X < 15) -> X < 15 |
| return ReplaceInstUsesWith(I, RHS); |
| } |
| break; |
| case Instruction::SetGT: |
| switch (RHSCC) { |
| default: assert(0 && "Unknown integer condition code!"); |
| case Instruction::SetEQ: // (X > 13 | X == 15) -> X > 13 |
| case Instruction::SetGT: // (X > 13 | X > 15) -> X > 13 |
| return ReplaceInstUsesWith(I, LHS); |
| case Instruction::SetNE: // (X > 13 | X != 15) -> true |
| case Instruction::SetLT: // (X > 13 | X < 15) -> true |
| return ReplaceInstUsesWith(I, ConstantBool::getTrue()); |
| } |
| } |
| } |
| } |
| |
| // fold (or (cast A), (cast B)) -> (cast (or A, B)) |
| if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) { |
| const Type *SrcTy = Op0C->getOperand(0)->getType(); |
| if (CastInst *Op1C = dyn_cast<CastInst>(Op1)) |
| if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isIntegral() && |
| // Only do this if the casts both really cause code to be generated. |
| ValueRequiresCast(Op0C->getOperand(0), I.getType(), TD) && |
| ValueRequiresCast(Op1C->getOperand(0), I.getType(), TD)) { |
| Instruction *NewOp = BinaryOperator::createOr(Op0C->getOperand(0), |
| Op1C->getOperand(0), |
| I.getName()); |
| InsertNewInstBefore(NewOp, I); |
| return CastInst::createInferredCast(NewOp, I.getType()); |
| } |
| } |
| |
| |
| return Changed ? &I : 0; |
| } |
| |
| // XorSelf - Implements: X ^ X --> 0 |
| struct XorSelf { |
| Value *RHS; |
| XorSelf(Value *rhs) : RHS(rhs) {} |
| bool shouldApply(Value *LHS) const { return LHS == RHS; } |
| Instruction *apply(BinaryOperator &Xor) const { |
| return &Xor; |
| } |
| }; |
| |
| |
| Instruction *InstCombiner::visitXor(BinaryOperator &I) { |
| bool Changed = SimplifyCommutative(I); |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| |
| if (isa<UndefValue>(Op1)) |
| return ReplaceInstUsesWith(I, Op1); // X ^ undef -> undef |
| |
| // xor X, X = 0, even if X is nested in a sequence of Xor's. |
| if (Instruction *Result = AssociativeOpt(I, XorSelf(Op1))) { |
| assert(Result == &I && "AssociativeOpt didn't work?"); |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| } |
| |
| // See if we can simplify any instructions used by the instruction whose sole |
| // purpose is to compute bits we don't care about. |
| uint64_t KnownZero, KnownOne; |
| if (!isa<PackedType>(I.getType()) && |
| SimplifyDemandedBits(&I, I.getType()->getIntegralTypeMask(), |
| KnownZero, KnownOne)) |
| return &I; |
| |
| if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) { |
| if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) { |
| // xor (setcc A, B), true = not (setcc A, B) = setncc A, B |
| if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0I)) |
| if (RHS == ConstantBool::getTrue() && SCI->hasOneUse()) |
| return new SetCondInst(SCI->getInverseCondition(), |
| SCI->getOperand(0), SCI->getOperand(1)); |
| |
| // ~(c-X) == X-c-1 == X+(-c-1) |
| if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue()) |
| if (Constant *Op0I0C = dyn_cast<Constant>(Op0I->getOperand(0))) { |
| Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C); |
| Constant *ConstantRHS = ConstantExpr::getSub(NegOp0I0C, |
| ConstantInt::get(I.getType(), 1)); |
| return BinaryOperator::createAdd(Op0I->getOperand(1), ConstantRHS); |
| } |
| |
| // ~(~X & Y) --> (X | ~Y) |
| if (Op0I->getOpcode() == Instruction::And && RHS->isAllOnesValue()) { |
| if (dyn_castNotVal(Op0I->getOperand(1))) Op0I->swapOperands(); |
| if (Value *Op0NotVal = dyn_castNotVal(Op0I->getOperand(0))) { |
| Instruction *NotY = |
| BinaryOperator::createNot(Op0I->getOperand(1), |
| Op0I->getOperand(1)->getName()+".not"); |
| InsertNewInstBefore(NotY, I); |
| return BinaryOperator::createOr(Op0NotVal, NotY); |
| } |
| } |
| |
| if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) |
| 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 (Op0I->getOpcode() == Instruction::Or) { |
| // (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0 |
| if (MaskedValueIsZero(Op0I->getOperand(0), Op0CI->getZExtValue())) { |
| Constant *NewRHS = ConstantExpr::getOr(Op0CI, RHS); |
| // Anything in both C1 and C2 is known to be zero, remove it from |
| // NewRHS. |
| Constant *CommonBits = ConstantExpr::getAnd(Op0CI, RHS); |
| NewRHS = ConstantExpr::getAnd(NewRHS, |
| ConstantExpr::getNot(CommonBits)); |
| WorkList.push_back(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, |
| ConstantIntegral::getAllOnesValue(I.getType())); |
| |
| if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1 |
| if (X == Op0) |
| return ReplaceInstUsesWith(I, |
| ConstantIntegral::getAllOnesValue(I.getType())); |
| |
| if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) |
| if (Op1I->getOpcode() == Instruction::Or) { |
| if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B |
| Op1I->swapOperands(); |
| I.swapOperands(); |
| std::swap(Op0, Op1); |
| } else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B |
| I.swapOperands(); // Simplified below. |
| std::swap(Op0, Op1); |
| } |
| } else if (Op1I->getOpcode() == Instruction::Xor) { |
| if (Op0 == Op1I->getOperand(0)) // A^(A^B) == B |
| return ReplaceInstUsesWith(I, Op1I->getOperand(1)); |
| else if (Op0 == Op1I->getOperand(1)) // A^(B^A) == B |
| return ReplaceInstUsesWith(I, Op1I->getOperand(0)); |
| } else if (Op1I->getOpcode() == Instruction::And && Op1I->hasOneUse()) { |
| if (Op1I->getOperand(0) == Op0) // A^(A&B) -> A^(B&A) |
| Op1I->swapOperands(); |
| if (Op0 == Op1I->getOperand(1)) { // A^(B&A) -> (B&A)^A |
| I.swapOperands(); // Simplified below. |
| std::swap(Op0, Op1); |
| } |
| } |
| |
| if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) |
| if (Op0I->getOpcode() == Instruction::Or && Op0I->hasOneUse()) { |
| if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B |
| Op0I->swapOperands(); |
| if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B |
| Instruction *NotB = BinaryOperator::createNot(Op1, "tmp"); |
| InsertNewInstBefore(NotB, I); |
| return BinaryOperator::createAnd(Op0I->getOperand(0), NotB); |
| } |
| } else if (Op0I->getOpcode() == Instruction::Xor) { |
| if (Op1 == Op0I->getOperand(0)) // (A^B)^A == B |
| return ReplaceInstUsesWith(I, Op0I->getOperand(1)); |
| else if (Op1 == Op0I->getOperand(1)) // (B^A)^A == B |
| return ReplaceInstUsesWith(I, Op0I->getOperand(0)); |
| } else if (Op0I->getOpcode() == Instruction::And && Op0I->hasOneUse()) { |
| if (Op0I->getOperand(0) == Op1) // (A&B)^A -> (B&A)^A |
| Op0I->swapOperands(); |
| if (Op0I->getOperand(1) == Op1 && // (B&A)^A == ~B & A |
| !isa<ConstantInt>(Op1)) { // Canonical form is (B&C)^C |
| Instruction *N = BinaryOperator::createNot(Op0I->getOperand(0), "tmp"); |
| InsertNewInstBefore(N, I); |
| return BinaryOperator::createAnd(N, Op1); |
| } |
| } |
| |
| // (setcc1 A, B) ^ (setcc2 A, B) --> (setcc3 A, B) |
| if (SetCondInst *RHS = dyn_cast<SetCondInst>(I.getOperand(1))) |
| if (Instruction *R = AssociativeOpt(I, FoldSetCCLogical(*this, RHS))) |
| return R; |
| |
| // fold (xor (cast A), (cast B)) -> (cast (xor A, B)) |
| if (CastInst *Op0C = dyn_cast<CastInst>(Op0)) { |
| const Type *SrcTy = Op0C->getOperand(0)->getType(); |
| if (CastInst *Op1C = dyn_cast<CastInst>(Op1)) |
| if (SrcTy == Op1C->getOperand(0)->getType() && SrcTy->isIntegral() && |
| // Only do this if the casts both really cause code to be generated. |
| ValueRequiresCast(Op0C->getOperand(0), I.getType(), TD) && |
| ValueRequiresCast(Op1C->getOperand(0), I.getType(), TD)) { |
| Instruction *NewOp = BinaryOperator::createXor(Op0C->getOperand(0), |
| Op1C->getOperand(0), |
| I.getName()); |
| InsertNewInstBefore(NewOp, I); |
| return CastInst::createInferredCast(NewOp, I.getType()); |
| } |
| } |
| |
| // (X >> Z) ^ (Y >> Z) -> (X^Y) >> Z for all shifts. |
| if (ShiftInst *SI1 = dyn_cast<ShiftInst>(Op1)) { |
| if (ShiftInst *SI0 = dyn_cast<ShiftInst>(Op0)) |
| if (SI0->getOpcode() == SI1->getOpcode() && |
| SI0->getOperand(1) == SI1->getOperand(1) && |
| (SI0->hasOneUse() || SI1->hasOneUse())) { |
| Instruction *NewOp = |
| InsertNewInstBefore(BinaryOperator::createXor(SI0->getOperand(0), |
| SI1->getOperand(0), |
| SI0->getName()), I); |
| return new ShiftInst(SI1->getOpcode(), NewOp, SI1->getOperand(1)); |
| } |
| } |
| |
| return Changed ? &I : 0; |
| } |
| |
| static bool isPositive(ConstantInt *C) { |
| return C->getSExtValue() >= 0; |
| } |
| |
| /// AddWithOverflow - Compute Result = In1+In2, returning true if the result |
| /// overflowed for this type. |
| static bool AddWithOverflow(ConstantInt *&Result, ConstantInt *In1, |
| ConstantInt *In2) { |
| Result = cast<ConstantInt>(ConstantExpr::getAdd(In1, In2)); |
| |
| if (In1->getType()->isUnsigned()) |
| return cast<ConstantInt>(Result)->getZExtValue() < |
| cast<ConstantInt>(In1)->getZExtValue(); |
| if (isPositive(In1) != isPositive(In2)) |
| return false; |
| if (isPositive(In1)) |
| return cast<ConstantInt>(Result)->getSExtValue() < |
| cast<ConstantInt>(In1)->getSExtValue(); |
| return cast<ConstantInt>(Result)->getSExtValue() > |
| cast<ConstantInt>(In1)->getSExtValue(); |
| } |
| |
| /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the |
| /// code necessary to compute the offset from the base pointer (without adding |
| /// in the base pointer). Return the result as a signed integer of intptr size. |
| static Value *EmitGEPOffset(User *GEP, Instruction &I, InstCombiner &IC) { |
| TargetData &TD = IC.getTargetData(); |
| gep_type_iterator GTI = gep_type_begin(GEP); |
| const Type *UIntPtrTy = TD.getIntPtrType(); |
| const Type *SIntPtrTy = UIntPtrTy->getSignedVersion(); |
| Value *Result = Constant::getNullValue(SIntPtrTy); |
| |
| // Build a mask for high order bits. |
| uint64_t PtrSizeMask = ~0ULL >> (64-TD.getPointerSize()*8); |
| |
| for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i, ++GTI) { |
| Value *Op = GEP->getOperand(i); |
| uint64_t Size = TD.getTypeSize(GTI.getIndexedType()) & PtrSizeMask; |
| Constant *Scale = ConstantExpr::getCast(ConstantInt::get(UIntPtrTy, Size), |
| SIntPtrTy); |
| if (Constant *OpC = dyn_cast<Constant>(Op)) { |
| if (!OpC->isNullValue()) { |
| OpC = ConstantExpr::getCast(OpC, SIntPtrTy); |
| Scale = ConstantExpr::getMul(OpC, Scale); |
| if (Constant *RC = dyn_cast<Constant>(Result)) |
| Result = ConstantExpr::getAdd(RC, Scale); |
| else { |
| // Emit an add instruction. |
| Result = IC.InsertNewInstBefore( |
| BinaryOperator::createAdd(Result, Scale, |
| GEP->getName()+".offs"), I); |
| } |
| } |
| } else { |
| // Convert to correct type. |
| Op = IC.InsertNewInstBefore(CastInst::createInferredCast(Op, SIntPtrTy, |
| Op->getName()+".c"), I); |
| if (Size != 1) |
| // We'll let instcombine(mul) convert this to a shl if possible. |
| Op = IC.InsertNewInstBefore(BinaryOperator::createMul(Op, Scale, |
| GEP->getName()+".idx"), I); |
| |
| // Emit an add instruction. |
| Result = IC.InsertNewInstBefore(BinaryOperator::createAdd(Op, Result, |
| GEP->getName()+".offs"), I); |
| } |
| } |
| return Result; |
| } |
| |
| /// FoldGEPSetCC - Fold comparisons between a GEP instruction and something |
| /// else. At this point we know that the GEP is on the LHS of the comparison. |
| Instruction *InstCombiner::FoldGEPSetCC(User *GEPLHS, Value *RHS, |
| Instruction::BinaryOps Cond, |
| Instruction &I) { |
| assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!"); |
| |
| if (CastInst *CI = dyn_cast<CastInst>(RHS)) |
| if (isa<PointerType>(CI->getOperand(0)->getType())) |
| RHS = CI->getOperand(0); |
| |
| Value *PtrBase = GEPLHS->getOperand(0); |
| if (PtrBase == RHS) { |
| // As an optimization, we don't actually have to compute the actual value of |
| // OFFSET if this is a seteq or setne comparison, just return whether each |
| // index is zero or not. |
| if (Cond == Instruction::SetEQ || Cond == Instruction::SetNE) { |
| Instruction *InVal = 0; |
| gep_type_iterator GTI = gep_type_begin(GEPLHS); |
| for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i, ++GTI) { |
| bool EmitIt = true; |
| if (Constant *C = dyn_cast<Constant>(GEPLHS->getOperand(i))) { |
| if (isa<UndefValue>(C)) // undef index -> undef. |
| return ReplaceInstUsesWith(I, UndefValue::get(I.getType())); |
| if (C->isNullValue()) |
| EmitIt = false; |
| else if (TD->getTypeSize(GTI.getIndexedType()) == 0) { |
| EmitIt = false; // This is indexing into a zero sized array? |
| } else if (isa<ConstantInt>(C)) |
| return ReplaceInstUsesWith(I, // No comparison is needed here. |
| ConstantBool::get(Cond == Instruction::SetNE)); |
| } |
| |
| if (EmitIt) { |
| Instruction *Comp = |
| new SetCondInst(Cond, GEPLHS->getOperand(i), |
| Constant::getNullValue(GEPLHS->getOperand(i)->getType())); |
| if (InVal == 0) |
| InVal = Comp; |
| else { |
| InVal = InsertNewInstBefore(InVal, I); |
| InsertNewInstBefore(Comp, I); |
| if (Cond == Instruction::SetNE) // True if any are unequal |
| InVal = BinaryOperator::createOr(InVal, Comp); |
| else // True if all are equal |
| InVal = BinaryOperator::createAnd(InVal, Comp); |
| } |
| } |
| } |
| |
| if (InVal) |
| return InVal; |
| else |
| ReplaceInstUsesWith(I, // No comparison is needed here, all indexes = 0 |
| ConstantBool::get(Cond == Instruction::SetEQ)); |
| } |
| |
| // Only lower this if the setcc is the only user of the GEP or if we expect |
| // the result to fold to a constant! |
| if (isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) { |
| // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0). |
| Value *Offset = EmitGEPOffset(GEPLHS, I, *this); |
| return new SetCondInst(Cond, Offset, |
| Constant::getNullValue(Offset->getType())); |
| } |
| } else if (User *GEPRHS = dyn_castGetElementPtr(RHS)) { |
| // If the base pointers are different, but the indices are the same, just |
| // compare the base pointer. |
| if (PtrBase != GEPRHS->getOperand(0)) { |
| bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands(); |
| IndicesTheSame &= GEPLHS->getOperand(0)->getType() == |
| GEPRHS->getOperand(0)->getType(); |
| if (IndicesTheSame) |
| for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i) |
| if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) { |
| IndicesTheSame = false; |
| break; |
| } |
| |
| // If all indices are the same, just compare the base pointers. |
| if (IndicesTheSame) |
| return new SetCondInst(Cond, GEPLHS->getOperand(0), |
| GEPRHS->getOperand(0)); |
| |
| // Otherwise, the base pointers are different and the indices are |
| // different, bail out. |
| return 0; |
| } |
| |
| // If one of the GEPs has all zero indices, recurse. |
| bool AllZeros = true; |
| for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i) |
| if (!isa<Constant>(GEPLHS->getOperand(i)) || |
| !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) { |
| AllZeros = false; |
| break; |
| } |
| if (AllZeros) |
| return FoldGEPSetCC(GEPRHS, GEPLHS->getOperand(0), |
| SetCondInst::getSwappedCondition(Cond), I); |
| |
| // If the other GEP has all zero indices, recurse. |
| AllZeros = true; |
| for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i) |
| if (!isa<Constant>(GEPRHS->getOperand(i)) || |
| !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) { |
| AllZeros = false; |
| break; |
| } |
| if (AllZeros) |
| return FoldGEPSetCC(GEPLHS, GEPRHS->getOperand(0), Cond, I); |
| |
| if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) { |
| // If the GEPs only differ by one index, compare it. |
| unsigned NumDifferences = 0; // Keep track of # differences. |
| unsigned DiffOperand = 0; // The operand that differs. |
| for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i) |
| if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) { |
| if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() != |
| GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) { |
| // Irreconcilable differences. |
| NumDifferences = 2; |
| break; |
| } else { |
| if (NumDifferences++) break; |
| DiffOperand = i; |
| } |
| } |
| |
| if (NumDifferences == 0) // SAME GEP? |
| return ReplaceInstUsesWith(I, // No comparison is needed here. |
| ConstantBool::get(Cond == Instruction::SetEQ)); |
| else if (NumDifferences == 1) { |
| Value *LHSV = GEPLHS->getOperand(DiffOperand); |
| Value *RHSV = GEPRHS->getOperand(DiffOperand); |
| |
| // Convert the operands to signed values to make sure to perform a |
| // signed comparison. |
| const Type *NewTy = LHSV->getType()->getSignedVersion(); |
| if (LHSV->getType() != NewTy) |
| LHSV = InsertCastBefore(LHSV, NewTy, I); |
| if (RHSV->getType() != NewTy) |
| RHSV = InsertCastBefore(RHSV, NewTy, I); |
| return new SetCondInst(Cond, LHSV, RHSV); |
| } |
| } |
| |
| // Only lower this if the setcc is the only user of the GEP or if we expect |
| // the result to fold to a constant! |
| if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) && |
| (isa<ConstantExpr>(GEPRHS) || GEPRHS->hasOneUse())) { |
| // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2) |
| Value *L = EmitGEPOffset(GEPLHS, I, *this); |
| Value *R = EmitGEPOffset(GEPRHS, I, *this); |
| return new SetCondInst(Cond, L, R); |
| } |
| } |
| return 0; |
| } |
| |
| |
| Instruction *InstCombiner::visitSetCondInst(SetCondInst &I) { |
| bool Changed = SimplifyCommutative(I); |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| const Type *Ty = Op0->getType(); |
| |
| // setcc X, X |
| if (Op0 == Op1) |
| return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I))); |
| |
| if (isa<UndefValue>(Op1)) // X setcc undef -> undef |
| return ReplaceInstUsesWith(I, UndefValue::get(Type::BoolTy)); |
| |
| // setcc <global/alloca*/null>, <global/alloca*/null> - Global/Stack value |
| // addresses never equal each other! We already know that Op0 != Op1. |
| if ((isa<GlobalValue>(Op0) || isa<AllocaInst>(Op0) || |
| isa<ConstantPointerNull>(Op0)) && |
| (isa<GlobalValue>(Op1) || isa<AllocaInst>(Op1) || |
| isa<ConstantPointerNull>(Op1))) |
| return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I))); |
| |
| // setcc's with boolean values can always be turned into bitwise operations |
| if (Ty == Type::BoolTy) { |
| switch (I.getOpcode()) { |
| default: assert(0 && "Invalid setcc instruction!"); |
| case Instruction::SetEQ: { // seteq bool %A, %B -> ~(A^B) |
| Instruction *Xor = BinaryOperator::createXor(Op0, Op1, I.getName()+"tmp"); |
| InsertNewInstBefore(Xor, I); |
| return BinaryOperator::createNot(Xor); |
| } |
| case Instruction::SetNE: |
| return BinaryOperator::createXor(Op0, Op1); |
| |
| case Instruction::SetGT: |
| std::swap(Op0, Op1); // Change setgt -> setlt |
| // FALL THROUGH |
| case Instruction::SetLT: { // setlt bool A, B -> ~X & Y |
| Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp"); |
| InsertNewInstBefore(Not, I); |
| return BinaryOperator::createAnd(Not, Op1); |
| } |
| case Instruction::SetGE: |
| std::swap(Op0, Op1); // Change setge -> setle |
| // FALL THROUGH |
| case Instruction::SetLE: { // setle bool %A, %B -> ~A | B |
| Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp"); |
| InsertNewInstBefore(Not, I); |
| return BinaryOperator::createOr(Not, Op1); |
| } |
| } |
| } |
| |
| // See if we are doing a comparison between a constant and an instruction that |
| // can be folded into the comparison. |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) { |
| // Check to see if we are comparing against the minimum or maximum value... |
| if (CI->isMinValue()) { |
| if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE |
| return ReplaceInstUsesWith(I, ConstantBool::getFalse()); |
| if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE |
| return ReplaceInstUsesWith(I, ConstantBool::getTrue()); |
| if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN |
| return BinaryOperator::createSetEQ(Op0, Op1); |
| if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN |
| return BinaryOperator::createSetNE(Op0, Op1); |
| |
| } else if (CI->isMaxValue()) { |
| if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE |
| return ReplaceInstUsesWith(I, ConstantBool::getFalse()); |
| if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE |
| return ReplaceInstUsesWith(I, ConstantBool::getTrue()); |
| if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX |
| return BinaryOperator::createSetEQ(Op0, Op1); |
| if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX |
| return BinaryOperator::createSetNE(Op0, Op1); |
| |
| // Comparing against a value really close to min or max? |
| } else if (isMinValuePlusOne(CI)) { |
| if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN |
| return BinaryOperator::createSetEQ(Op0, SubOne(CI)); |
| if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN |
| return BinaryOperator::createSetNE(Op0, SubOne(CI)); |
| |
| } else if (isMaxValueMinusOne(CI)) { |
| if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX |
| return BinaryOperator::createSetEQ(Op0, AddOne(CI)); |
| if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX |
| return BinaryOperator::createSetNE(Op0, AddOne(CI)); |
| } |
| |
| // If we still have a setle or setge instruction, turn it into the |
| // appropriate setlt or setgt instruction. Since the border cases have |
| // already been handled above, this requires little checking. |
| // |
| if (I.getOpcode() == Instruction::SetLE) |
| return BinaryOperator::createSetLT(Op0, AddOne(CI)); |
| if (I.getOpcode() == Instruction::SetGE) |
| return BinaryOperator::createSetGT(Op0, SubOne(CI)); |
| |
| |
| // See if we can fold the comparison based on bits known to be zero or one |
| // in the input. |
| uint64_t KnownZero, KnownOne; |
| if (SimplifyDemandedBits(Op0, Ty->getIntegralTypeMask(), |
| KnownZero, KnownOne, 0)) |
| return &I; |
| |
| // Given the known and unknown bits, compute a range that the LHS could be |
| // in. |
| if (KnownOne | KnownZero) { |
| if (Ty->isUnsigned()) { // Unsigned comparison. |
| uint64_t Min, Max; |
| uint64_t RHSVal = CI->getZExtValue(); |
| ComputeUnsignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne, |
| Min, Max); |
| switch (I.getOpcode()) { // LE/GE have been folded already. |
| default: assert(0 && "Unknown setcc opcode!"); |
| case Instruction::SetEQ: |
| if (Max < RHSVal || Min > RHSVal) |
| return ReplaceInstUsesWith(I, ConstantBool::getFalse()); |
| break; |
| case Instruction::SetNE: |
| if (Max < RHSVal || Min > RHSVal) |
| return ReplaceInstUsesWith(I, ConstantBool::getTrue()); |
| break; |
| case Instruction::SetLT: |
| if (Max < RHSVal) |
| return ReplaceInstUsesWith(I, ConstantBool::getTrue()); |
| if (Min > RHSVal) |
| return ReplaceInstUsesWith(I, ConstantBool::getFalse()); |
| break; |
| case Instruction::SetGT: |
| if (Min > RHSVal) |
| return ReplaceInstUsesWith(I, ConstantBool::getTrue()); |
| if (Max < RHSVal) |
| return ReplaceInstUsesWith(I, ConstantBool::getFalse()); |
| break; |
| } |
| } else { // Signed comparison. |
| int64_t Min, Max; |
| int64_t RHSVal = CI->getSExtValue(); |
| ComputeSignedMinMaxValuesFromKnownBits(Ty, KnownZero, KnownOne, |
| Min, Max); |
| switch (I.getOpcode()) { // LE/GE have been folded already. |
| default: assert(0 && "Unknown setcc opcode!"); |
| case Instruction::SetEQ: |
| if (Max < RHSVal || Min > RHSVal) |
| return ReplaceInstUsesWith(I, ConstantBool::getFalse()); |
| break; |
| case Instruction::SetNE: |
| if (Max < RHSVal || Min > RHSVal) |
| return ReplaceInstUsesWith(I, ConstantBool::getTrue()); |
| break; |
| case Instruction::SetLT: |
| if (Max < RHSVal) |
| return ReplaceInstUsesWith(I, ConstantBool::getTrue()); |
| if (Min > RHSVal) |
| return ReplaceInstUsesWith(I, ConstantBool::getFalse()); |
| break; |
| case Instruction::SetGT: |
| if (Min > RHSVal) |
| return ReplaceInstUsesWith(I, ConstantBool::getTrue()); |
| if (Max < RHSVal) |
| return ReplaceInstUsesWith(I, ConstantBool::getFalse()); |
| break; |
| } |
| } |
| } |
| |
| // 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 setcc |
| if (Instruction *LHSI = dyn_cast<Instruction>(Op0)) |
| switch (LHSI->getOpcode()) { |
| case Instruction::And: |
| if (LHSI->hasOneUse() && isa<ConstantInt>(LHSI->getOperand(1)) && |
| LHSI->getOperand(0)->hasOneUse()) { |
| ConstantInt *AndCST = cast<ConstantInt>(LHSI->getOperand(1)); |
| |
| // If an operand 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 (CastInst *Cast = dyn_cast<CastInst>(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() && isa<TruncInst>(Cast) && |
| (I.isEquality() || |
| (AndCST->getZExtValue() == (uint64_t)AndCST->getSExtValue()) && |
| (CI->getZExtValue() == (uint64_t)CI->getSExtValue()))) { |
| ConstantInt *NewCST; |
| ConstantInt *NewCI; |
| if (Cast->getOperand(0)->getType()->isSigned()) { |
| NewCST = ConstantInt::get(Cast->getOperand(0)->getType(), |
| AndCST->getZExtValue()); |
| NewCI = ConstantInt::get(Cast->getOperand(0)->getType(), |
| CI->getZExtValue()); |
| } else { |
| NewCST = ConstantInt::get(Cast->getOperand(0)->getType(), |
| AndCST->getZExtValue()); |
| NewCI = ConstantInt::get(Cast->getOperand(0)->getType(), |
| CI->getZExtValue()); |
| } |
| Instruction *NewAnd = |
| BinaryOperator::createAnd(Cast->getOperand(0), NewCST, |
| LHSI->getName()); |
| InsertNewInstBefore(NewAnd, I); |
| return new SetCondInst(I.getOpcode(), NewAnd, 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. |
| ShiftInst *Shift = dyn_cast<ShiftInst>(LHSI->getOperand(0)); |
| |
| // Check to see if there is a noop-cast between the shift and the and. |
| if (!Shift) { |
| if (CastInst *CI = dyn_cast<CastInst>(LHSI->getOperand(0))) |
| if (CI->getOperand(0)->getType()->isIntegral() && |
| CI->getOperand(0)->getType()->getPrimitiveSizeInBits() == |
| CI->getType()->getPrimitiveSizeInBits()) |
| Shift = dyn_cast<ShiftInst>(CI->getOperand(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. |
| int ShAmtVal = Ty->getPrimitiveSizeInBits()-ShAmt->getZExtValue(); |
| if (ShAmtVal < 0) ShAmtVal = 0; // Out of range shift. |
| |
| Constant *OShAmt = ConstantInt::get(Type::UByteTy, ShAmtVal); |
| Constant *ShVal = |
| ConstantExpr::getShl(ConstantInt::getAllOnesValue(AndTy), |
| OShAmt); |
| if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue()) |
| CanFold = true; |
| } |
| |
| if (CanFold) { |
| Constant *NewCst; |
| if (Shift->getOpcode() == Instruction::Shl) |
| NewCst = ConstantExpr::getLShr(CI, ShAmt); |
| else |
| NewCst = ConstantExpr::getShl(CI, ShAmt); |
| |
| // Check to see if we are shifting out any of the bits being |
| // compared. |
| if (ConstantExpr::get(Shift->getOpcode(), NewCst, ShAmt) != CI){ |
| // If we shifted bits out, the fold is not going to work out. |
| // As a special case, check to see if this means that the |
| // result is always true or false now. |
| if (I.getOpcode() == Instruction::SetEQ) |
| return ReplaceInstUsesWith(I, ConstantBool::getFalse()); |
| if (I.getOpcode() == Instruction::SetNE) |
| return ReplaceInstUsesWith(I, ConstantBool::getTrue()); |
| } else { |
| I.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); |
| if (AndTy == Ty) |
| LHSI->setOperand(0, Shift->getOperand(0)); |
| else { |
| Value *NewCast = InsertCastBefore(Shift->getOperand(0), AndTy, |
| *Shift); |
| LHSI->setOperand(0, NewCast); |
| } |
| WorkList.push_back(Shift); // Shift is dead. |
| AddUsesToWorkList(I); |
| return &I; |
| } |
| } |
| } |
| |
| // 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() && CI->isNullValue() && |
| I.isEquality() && !Shift->isArithmeticShift() && |
| isa<Instruction>(Shift->getOperand(0))) { |
| // Compute C << Y. |
| Value *NS; |
| if (Shift->getOpcode() == Instruction::LShr) { |
| NS = new ShiftInst(Instruction::Shl, AndCST, Shift->getOperand(1), |
| "tmp"); |
| } else { |
| // Make sure we insert a logical shift. |
| Constant *NewAndCST = AndCST; |
| if (AndCST->getType()->isSigned()) |
| NewAndCST = ConstantExpr::getCast(AndCST, |
| AndCST->getType()->getUnsignedVersion()); |
| NS = new ShiftInst(Instruction::LShr, NewAndCST, |
| Shift->getOperand(1), "tmp"); |
| } |
| InsertNewInstBefore(cast<Instruction>(NS), I); |
| |
| // If C's sign doesn't agree with the and, insert a cast now. |
| if (NS->getType() != LHSI->getType()) |
| NS = InsertCastBefore(NS, LHSI->getType(), I); |
| |
| Value *ShiftOp = Shift->getOperand(0); |
| if (ShiftOp->getType() != LHSI->getType()) |
| ShiftOp = InsertCastBefore(ShiftOp, LHSI->getType(), I); |
| |
| // Compute X & (C << Y). |
| Instruction *NewAnd = |
| BinaryOperator::createAnd(ShiftOp, NS, LHSI->getName()); |
| InsertNewInstBefore(NewAnd, I); |
| |
| I.setOperand(0, NewAnd); |
| return &I; |
| } |
| } |
| break; |
| |
| case Instruction::Shl: // (setcc (shl X, ShAmt), CI) |
| if (ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1))) { |
| if (I.isEquality()) { |
| unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits(); |
| |
| // Check that the shift amount is in range. If not, don't perform |
| // undefined shifts. When the shift is visited it will be |
| // simplified. |
| if (ShAmt->getZExtValue() >= TypeBits) |
| break; |
| |
| // If we are comparing against bits always shifted out, the |
| // comparison cannot succeed. |
| Constant *Comp = |
| ConstantExpr::getShl(ConstantExpr::getLShr(CI, ShAmt), ShAmt); |
| if (Comp != CI) {// Comparing against a bit that we know is zero. |
| bool IsSetNE = I.getOpcode() == Instruction::SetNE; |
| Constant *Cst = ConstantBool::get(IsSetNE); |
| return ReplaceInstUsesWith(I, Cst); |
| } |
| |
| if (LHSI->hasOneUse()) { |
| // Otherwise strength reduce the shift into an and. |
| unsigned ShAmtVal = (unsigned)ShAmt->getZExtValue(); |
| uint64_t Val = (1ULL << (TypeBits-ShAmtVal))-1; |
| |
| Constant *Mask; |
| if (CI->getType()->isUnsigned()) { |
| Mask = ConstantInt::get(CI->getType(), Val); |
| } else if (ShAmtVal != 0) { |
| Mask = ConstantInt::get(CI->getType(), Val); |
| } else { |
| Mask = ConstantInt::getAllOnesValue(CI->getType()); |
| } |
| |
| Instruction *AndI = |
| BinaryOperator::createAnd(LHSI->getOperand(0), |
| Mask, LHSI->getName()+".mask"); |
| Value *And = InsertNewInstBefore(AndI, I); |
| return new SetCondInst(I.getOpcode(), And, |
| ConstantExpr::getLShr(CI, ShAmt)); |
| } |
| } |
| } |
| break; |
| |
| case Instruction::LShr: // (setcc (shr X, ShAmt), CI) |
| case Instruction::AShr: |
| if (ConstantInt *ShAmt = dyn_cast<ConstantInt>(LHSI->getOperand(1))) { |
| if (I.isEquality()) { |
| // Check that the shift amount is in range. If not, don't perform |
| // undefined shifts. When the shift is visited it will be |
| // simplified. |
| unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits(); |
| if (ShAmt->getZExtValue() >= TypeBits) |
| break; |
| |
| // If we are comparing against bits always shifted out, the |
| // comparison cannot succeed. |
| Constant *Comp; |
| if (CI->getType()->isUnsigned()) |
| Comp = ConstantExpr::getLShr(ConstantExpr::getShl(CI, ShAmt), |
| ShAmt); |
| else |
| Comp = ConstantExpr::getAShr(ConstantExpr::getShl(CI, ShAmt), |
| ShAmt); |
| |
| if (Comp != CI) {// Comparing against a bit that we know is zero. |
| bool IsSetNE = I.getOpcode() == Instruction::SetNE; |
| Constant *Cst = ConstantBool::get(IsSetNE); |
| return ReplaceInstUsesWith(I, Cst); |
| } |
| |
| if (LHSI->hasOneUse() || CI->isNullValue()) { |
| unsigned ShAmtVal = (unsigned)ShAmt->getZExtValue(); |
| |
| // Otherwise strength reduce the shift into an and. |
| uint64_t Val = ~0ULL; // All ones. |
| Val <<= ShAmtVal; // Shift over to the right spot. |
| |
| Constant *Mask; |
| if (CI->getType()->isUnsigned()) { |
| Val &= ~0ULL >> (64-TypeBits); |
| Mask = ConstantInt::get(CI->getType(), Val); |
| } else { |
| Mask = ConstantInt::get(CI->getType(), Val); |
| } |
| |
| Instruction *AndI = |
| BinaryOperator::createAnd(LHSI->getOperand(0), |
| Mask, LHSI->getName()+".mask"); |
| Value *And = InsertNewInstBefore(AndI, I); |
| return new SetCondInst(I.getOpcode(), And, |
| ConstantExpr::getShl(CI, ShAmt)); |
| } |
| } |
| } |
| break; |
| |
| case Instruction::SDiv: |
| case Instruction::UDiv: |
| // Fold: setcc ([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))) { |
| // 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. |
| const Type *DivRHSTy = DivRHS->getType(); |
| unsigned DivOpCode = LHSI->getOpcode(); |
| if (I.isEquality() && |
| ((DivOpCode == Instruction::SDiv && DivRHSTy->isUnsigned()) || |
| (DivOpCode == Instruction::UDiv && DivRHSTy->isSigned()))) |
| break; |
| |
| // Initialize the variables that will indicate the nature of the |
| // range check. |
| bool LoOverflow = false, HiOverflow = false; |
| ConstantInt *LoBound = 0, *HiBound = 0; |
| |
| // 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 = |
| cast<ConstantInt>(ConstantExpr::getMul(CI, 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 = !DivRHS->isNullValue() && |
| (DivOpCode == Instruction::SDiv ? |
| ConstantExpr::getSDiv(Prod, DivRHS) : |
| ConstantExpr::getUDiv(Prod, DivRHS)) != CI; |
| |
| // Get the SetCC opcode |
| Instruction::BinaryOps Opcode = I.getOpcode(); |
| |
| if (DivRHS->isNullValue()) { |
| // Don't hack on divide by zeros! |
| } else if (DivOpCode == Instruction::UDiv) { // udiv |
| LoBound = Prod; |
| LoOverflow = ProdOV; |
| HiOverflow = ProdOV || AddWithOverflow(HiBound, LoBound, DivRHS); |
| } else if (isPositive(DivRHS)) { // Divisor is > 0. |
| if (CI->isNullValue()) { // (X / pos) op 0 |
| // Can't overflow. |
| LoBound = cast<ConstantInt>(ConstantExpr::getNeg(SubOne(DivRHS))); |
| HiBound = DivRHS; |
| } else if (isPositive(CI)) { // (X / pos) op pos |
| LoBound = Prod; |
| LoOverflow = ProdOV; |
| HiOverflow = ProdOV || AddWithOverflow(HiBound, Prod, DivRHS); |
| } else { // (X / pos) op neg |
| Constant *DivRHSH = ConstantExpr::getNeg(SubOne(DivRHS)); |
| LoOverflow = AddWithOverflow(LoBound, Prod, |
| cast<ConstantInt>(DivRHSH)); |
| HiBound = Prod; |
| HiOverflow = ProdOV; |
| } |
| } else { // Divisor is < 0. |
| if (CI->isNullValue()) { // (X / neg) op 0 |
| LoBound = AddOne(DivRHS); |
| HiBound = cast<ConstantInt>(ConstantExpr::getNeg(DivRHS)); |
| if (HiBound == DivRHS) |
| LoBound = 0; // - INTMIN = INTMIN |
| } else if (isPositive(CI)) { // (X / neg) op pos |
| HiOverflow = LoOverflow = ProdOV; |
| if (!LoOverflow) |
| LoOverflow = AddWithOverflow(LoBound, Prod, AddOne(DivRHS)); |
| HiBound = AddOne(Prod); |
| } else { // (X / neg) op neg |
| LoBound = Prod; |
| LoOverflow = HiOverflow = ProdOV; |
| HiBound = cast<ConstantInt>(ConstantExpr::getSub(Prod, DivRHS)); |
| } |
| |
| // Dividing by a negate swaps the condition. |
| Opcode = SetCondInst::getSwappedCondition(Opcode); |
| } |
| |
| if (LoBound) { |
| Value *X = LHSI->getOperand(0); |
| switch (Opcode) { |
| default: assert(0 && "Unhandled setcc opcode!"); |
| case Instruction::SetEQ: |
| if (LoOverflow && HiOverflow) |
| return ReplaceInstUsesWith(I, ConstantBool::getFalse()); |
| else if (HiOverflow) |
| return new SetCondInst(Instruction::SetGE, X, LoBound); |
| else if (LoOverflow) |
| return new SetCondInst(Instruction::SetLT, X, HiBound); |
| else |
| return InsertRangeTest(X, LoBound, HiBound, true, I); |
| case Instruction::SetNE: |
| if (LoOverflow && HiOverflow) |
| return ReplaceInstUsesWith(I, ConstantBool::getTrue()); |
| else if (HiOverflow) |
| return new SetCondInst(Instruction::SetLT, X, LoBound); |
| else if (LoOverflow) |
| return new SetCondInst(Instruction::SetGE, X, HiBound); |
| else |
| return InsertRangeTest(X, LoBound, HiBound, false, I); |
| case Instruction::SetLT: |
| if (LoOverflow) |
| return ReplaceInstUsesWith(I, ConstantBool::getFalse()); |
| return new SetCondInst(Instruction::SetLT, X, LoBound); |
| case Instruction::SetGT: |
| if (HiOverflow) |
| return ReplaceInstUsesWith(I, ConstantBool::getFalse()); |
| return new SetCondInst(Instruction::SetGE, X, HiBound); |
| } |
| } |
| } |
| break; |
| } |
| |
| // Simplify seteq and setne instructions... |
| if (I.isEquality()) { |
| bool isSetNE = I.getOpcode() == Instruction::SetNE; |
| |
| // 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>(Op0)) { |
| switch (BO->getOpcode()) { |
| case Instruction::SRem: |
| // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one. |
| if (CI->isNullValue() && isa<ConstantInt>(BO->getOperand(1)) && |
| BO->hasOneUse()) { |
| int64_t V = cast<ConstantInt>(BO->getOperand(1))->getSExtValue(); |
| if (V > 1 && isPowerOf2_64(V)) { |
| Value *NewRem = InsertNewInstBefore(BinaryOperator::createURem( |
| BO->getOperand(0), BO->getOperand(1), BO->getName()), I); |
| return BinaryOperator::create(I.getOpcode(), 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 SetCondInst(I.getOpcode(), BO->getOperand(0), |
| ConstantExpr::getSub(CI, BOp1C)); |
| } else if (CI->isNullValue()) { |
| // Replace ((add A, B) != 0) with (A != -B) if A or B is |
| // efficiently invertible, or if the add has just this one use. |
| Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1); |
| |
| if (Value *NegVal = dyn_castNegVal(BOp1)) |
| return new SetCondInst(I.getOpcode(), BOp0, NegVal); |
| else if (Value *NegVal = dyn_castNegVal(BOp0)) |
| return new SetCondInst(I.getOpcode(), NegVal, BOp1); |
| else if (BO->hasOneUse()) { |
| Instruction *Neg = BinaryOperator::createNeg(BOp1, BO->getName()); |
| BO->setName(""); |
| InsertNewInstBefore(Neg, I); |
| return new SetCondInst(I.getOpcode(), BOp0, Neg); |
| } |
| } |
| break; |
| case Instruction::Xor: |
| // For the xor case, we can xor two constants together, eliminating |
| // the explicit xor. |
| if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) |
| return BinaryOperator::create(I.getOpcode(), BO->getOperand(0), |
| ConstantExpr::getXor(CI, BOC)); |
| |
| // FALLTHROUGH |
| case Instruction::Sub: |
| // Replace (([sub|xor] A, B) != 0) with (A != B) |
| if (CI->isNullValue()) |
| return new SetCondInst(I.getOpcode(), BO->getOperand(0), |
| BO->getOperand(1)); |
| break; |
| |
| case Instruction::Or: |
| // If bits are being or'd in that are not present in the constant we |
| // are comparing against, then the comparison could never succeed! |
| if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) { |
| Constant *NotCI = ConstantExpr::getNot(CI); |
| if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue()) |
| return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE)); |
| } |
| break; |
| |
| case Instruction::And: |
| if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) { |
| // If bits are being compared against that are and'd out, then the |
| // comparison can never succeed! |
| if (!ConstantExpr::getAnd(CI, |
| ConstantExpr::getNot(BOC))->isNullValue()) |
| return ReplaceInstUsesWith(I, ConstantBool::get(isSetNE)); |
| |
| // If we have ((X & C) == C), turn it into ((X & C) != 0). |
| if (CI == BOC && isOneBitSet(CI)) |
| return new SetCondInst(isSetNE ? Instruction::SetEQ : |
| Instruction::SetNE, Op0, |
| Constant::getNullValue(CI->getType())); |
| |
| // Replace (and X, (1 << size(X)-1) != 0) with x < 0, converting X |
| // to be a signed value as appropriate. |
| if (isSignBit(BOC)) { |
| Value *X = BO->getOperand(0); |
| // If 'X' is not signed, insert a cast now... |
| if (!BOC->getType()->isSigned()) { |
| const Type *DestTy = BOC->getType()->getSignedVersion(); |
| X = InsertCastBefore(X, DestTy, I); |
| } |
| return new SetCondInst(isSetNE ? Instruction::SetLT : |
| Instruction::SetGE, X, |
| Constant::getNullValue(X->getType())); |
| } |
| |
| // ((X & ~7) == 0) --> X < 8 |
| if (CI->isNullValue() && isHighOnes(BOC)) { |
| Value *X = BO->getOperand(0); |
| Constant *NegX = ConstantExpr::getNeg(BOC); |
| |
| // If 'X' is signed, insert a cast now. |
| if (NegX->getType()->isSigned()) { |
| const Type *DestTy = NegX->getType()->getUnsignedVersion(); |
| X = InsertCastBefore(X, DestTy, I); |
| NegX = ConstantExpr::getCast(NegX, DestTy); |
| } |
| |
| return new SetCondInst(isSetNE ? Instruction::SetGE : |
| Instruction::SetLT, X, NegX); |
| } |
| |
| } |
| default: break; |
| } |
| } |
| } else { // Not a SetEQ/SetNE |
| // If the LHS is a cast from an integral value of the same size, |
| if (CastInst *Cast = dyn_cast<CastInst>(Op0)) { |
| Value *CastOp = Cast->getOperand(0); |
| const Type *SrcTy = CastOp->getType(); |
| unsigned SrcTySize = SrcTy->getPrimitiveSizeInBits(); |
| if (SrcTy != Cast->getType() && SrcTy->isInteger() && |
| SrcTySize == Cast->getType()->getPrimitiveSizeInBits()) { |
| assert((SrcTy->isSigned() ^ Cast->getType()->isSigned()) && |
| "Source and destination signednesses should differ!"); |
| if (Cast->getType()->isSigned()) { |
| // If this is a signed comparison, check for comparisons in the |
| // vicinity of zero. |
| if (I.getOpcode() == Instruction::SetLT && CI->isNullValue()) |
| // X < 0 => x > 127 |
| return BinaryOperator::createSetGT(CastOp, |
| ConstantInt::get(SrcTy, (1ULL << (SrcTySize-1))-1)); |
| else if (I.getOpcode() == Instruction::SetGT && |
| cast<ConstantInt>(CI)->getSExtValue() == -1) |
| // X > -1 => x < 128 |
| return BinaryOperator::createSetLT(CastOp, |
| ConstantInt::get(SrcTy, 1ULL << (SrcTySize-1))); |
| } else { |
| ConstantInt *CUI = cast<ConstantInt>(CI); |
| if (I.getOpcode() == Instruction::SetLT && |
| CUI->getZExtValue() == 1ULL << (SrcTySize-1)) |
| // X < 128 => X > -1 |
| return BinaryOperator::createSetGT(CastOp, |
| ConstantInt::get(SrcTy, -1)); |
| else if (I.getOpcode() == Instruction::SetGT && |
| CUI->getZExtValue() == (1ULL << (SrcTySize-1))-1) |
| // X > 127 => X < 0 |
| return BinaryOperator::createSetLT(CastOp, |
| Constant::getNullValue(SrcTy)); |
| } |
| } |
| } |
| } |
| } |
| |
| // Handle setcc with constant RHS's that can be integer, FP or pointer. |
| if (Constant *RHSC = dyn_cast<Constant>(Op1)) { |
| if (Instruction *LHSI = dyn_cast<Instruction>(Op0)) |
| switch (LHSI->getOpcode()) { |
| case Instruction::GetElementPtr: |
| if (RHSC->isNullValue()) { |
| // Transform setcc GEP P, int 0, int 0, int 0, null -> setcc P, null |
| bool isAllZeros = true; |
| for (unsigned i = 1, e = LHSI->getNumOperands(); i != e; ++i) |
| if (!isa<Constant>(LHSI->getOperand(i)) || |
| !cast<Constant>(LHSI->getOperand(i))->isNullValue()) { |
| isAllZeros = false; |
| break; |
| } |
| if (isAllZeros) |
| return new SetCondInst(I.getOpcode(), LHSI->getOperand(0), |
| Constant::getNullValue(LHSI->getOperand(0)->getType())); |
| } |
| break; |
| |
| case Instruction::PHI: |
| if (Instruction *NV = FoldOpIntoPhi(I)) |
| return NV; |
| break; |
| case Instruction::Select: |
| // If either operand of the select is a constant, we can fold the |
| // comparison into the select arms, which will cause one to be |
| // constant folded and the select turned into a bitwise or. |
| Value *Op1 = 0, *Op2 = 0; |
| if (LHSI->hasOneUse()) { |
| if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(1))) { |
| // Fold the known value into the constant operand. |
| Op1 = ConstantExpr::get(I.getOpcode(), C, RHSC); |
| // Insert a new SetCC of the other select operand. |
| Op2 = InsertNewInstBefore(new SetCondInst(I.getOpcode(), |
| LHSI->getOperand(2), RHSC, |
| I.getName()), I); |
| } else if (Constant *C = dyn_cast<Constant>(LHSI->getOperand(2))) { |
| // Fold the known value into the constant operand. |
| Op2 = ConstantExpr::get(I.getOpcode(), C, RHSC); |
| // Insert a new SetCC of the other select operand. |
| Op1 = InsertNewInstBefore(new SetCondInst(I.getOpcode(), |
| LHSI->getOperand(1), RHSC, |
| I.getName()), I); |
| } |
| } |
| |
| if (Op1) |
| return new SelectInst(LHSI->getOperand(0), Op1, Op2); |
| break; |
| } |
| } |
| |
| // If we can optimize a 'setcc GEP, P' or 'setcc P, GEP', do so now. |
| if (User *GEP = dyn_castGetElementPtr(Op0)) |
| if (Instruction *NI = FoldGEPSetCC(GEP, Op1, I.getOpcode(), I)) |
| return NI; |
| if (User *GEP = dyn_castGetElementPtr(Op1)) |
| if (Instruction *NI = FoldGEPSetCC(GEP, Op0, |
| SetCondInst::getSwappedCondition(I.getOpcode()), I)) |
| return NI; |
| |
| // Test to see if the operands of the setcc are casted versions of other |
| // values. If the cast can be stripped off both arguments, we do so now. |
| if (CastInst *CI = dyn_cast<CastInst>(Op0)) { |
| Value *CastOp0 = CI->getOperand(0); |
| if (CI->isLosslessCast() && I.isEquality() && |
| (isa<Constant>(Op1) || isa<CastInst>(Op1))) { |
| // We keep moving the cast from the left operand over to the right |
| // operand, where it can often be eliminated completely. |
| Op0 = CastOp0; |
| |
| // If operand #1 is a cast instruction, see if we can eliminate it as |
| // well. |
| if (CastInst *CI2 = dyn_cast<CastInst>(Op1)) { |
| Value *CI2Op0 = CI2->getOperand(0); |
| if (CI2Op0->getType()->canLosslesslyBitCastTo(Op0->getType())) |
| Op1 = CI2Op0; |
| } |
| |
| // If Op1 is a constant, we can fold the cast into the constant. |
| if (Op1->getType() != Op0->getType()) |
| if (Constant *Op1C = dyn_cast<Constant>(Op1)) { |
| Op1 = ConstantExpr::getCast(Op1C, Op0->getType()); |
| } else { |
| // Otherwise, cast the RHS right before the setcc |
| Op1 = InsertCastBefore(Op1, Op0->getType(), I); |
| } |
| return BinaryOperator::create(I.getOpcode(), Op0, Op1); |
| } |
| |
| // Handle the special case of: setcc (cast bool to X), <cst> |
| // This comes up when you have code like |
| // int X = A < B; |
| // if (X) ... |
| // For generality, we handle any zero-extension of any operand comparison |
| // with a constant or another cast from the same type. |
| if (isa<ConstantInt>(Op1) || isa<CastInst>(Op1)) |
| if (Instruction *R = visitSetCondInstWithCastAndCast(I)) |
| return R; |
| } |
| |
| if (I.isEquality()) { |
| Value *A, *B; |
| if (match(Op0, m_Xor(m_Value(A), m_Value(B))) && |
| (A == Op1 || B == Op1)) { |
| // (A^B) == A -> B == 0 |
| Value *OtherVal = A == Op1 ? B : A; |
| return BinaryOperator::create(I.getOpcode(), OtherVal, |
| Constant::getNullValue(A->getType())); |
| } else 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 BinaryOperator::create(I.getOpcode(), OtherVal, |
| Constant::getNullValue(A->getType())); |
| } else if (match(Op0, m_Sub(m_Value(A), m_Value(B))) && A == Op1) { |
| // (A-B) == A -> B == 0 |
| return BinaryOperator::create(I.getOpcode(), B, |
| Constant::getNullValue(B->getType())); |
| } else if (match(Op1, m_Sub(m_Value(A), m_Value(B))) && A == Op0) { |
| // A == (A-B) -> B == 0 |
| return BinaryOperator::create(I.getOpcode(), B, |
| Constant::getNullValue(B->getType())); |
| } |
| |
| Value *C, *D; |
| // (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; |
| } |
| |
| // visitSetCondInstWithCastAndCast - Handle setcond (cast x to y), (cast/cst). |
| // We only handle extending casts so far. |
| // |
| Instruction *InstCombiner::visitSetCondInstWithCastAndCast(SetCondInst &SCI) { |
| const CastInst *LHSCI = cast<CastInst>(SCI.getOperand(0)); |
| Value *LHSCIOp = LHSCI->getOperand(0); |
| const Type *SrcTy = LHSCIOp->getType(); |
| const Type *DestTy = SCI.getOperand(0)->getType(); |
| Value *RHSCIOp; |
| |
| if (!DestTy->isIntegral() || !SrcTy->isIntegral()) |
| return 0; |
| |
| unsigned SrcBits = SrcTy->getPrimitiveSizeInBits(); |
| unsigned DestBits = DestTy->getPrimitiveSizeInBits(); |
| if (SrcBits >= DestBits) return 0; // Only handle extending cast. |
| |
| // Is this a sign or zero extension? |
| bool isSignSrc = SrcTy->isSigned(); |
| bool isSignDest = DestTy->isSigned(); |
| |
| if (CastInst *CI = dyn_cast<CastInst>(SCI.getOperand(1))) { |
| // Not an extension from the same type? |
| RHSCIOp = CI->getOperand(0); |
| if (RHSCIOp->getType() != LHSCIOp->getType()) return 0; |
| } else if (ConstantInt *CI = dyn_cast<ConstantInt>(SCI.getOperand(1))) { |
| // Compute the constant that would happen if we truncated to SrcTy then |
| // reextended to DestTy. |
| Constant *Res1 = ConstantExpr::getTrunc(CI, SrcTy); |
| Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(), Res1, DestTy); |
| |
| if (Res2 == CI) { |
| // Make sure that src sign and dest sign match. For example, |
| // |
| // %A = cast short %X to uint |
| // %B = setgt uint %A, 1330 |
| // |
| // It is incorrect to transform this into |
| // |
| // %B = setgt short %X, 1330 |
| // |
| // because %A may have negative value. |
| // However, it is OK if SrcTy is bool (See cast-set.ll testcase) |
| // OR operation is EQ/NE. |
| if (isSignSrc == isSignDest || SrcTy == Type::BoolTy || SCI.isEquality()) |
| RHSCIOp = Res1; |
| else |
| return 0; |
| } else { |
| // If the value cannot be represented in the shorter type, we cannot emit |
| // a simple comparison. |
| if (SCI.getOpcode() == Instruction::SetEQ) |
| return ReplaceInstUsesWith(SCI, ConstantBool::getFalse()); |
| if (SCI.getOpcode() == Instruction::SetNE) |
| return ReplaceInstUsesWith(SCI, ConstantBool::getTrue()); |
| |
| // Evaluate the comparison for LT. |
| Value *Result; |
| if (DestTy->isSigned()) { |
| // We're performing a signed comparison. |
| if (isSignSrc) { |
| // Signed extend and signed comparison. |
| if (cast<ConstantInt>(CI)->getSExtValue() < 0)// X < (small) --> false |
| Result = ConstantBool::getFalse(); |
| else |
| Result = ConstantBool::getTrue(); // X < (large) --> true |
| } else { |
| // Unsigned extend and signed comparison. |
| if (cast<ConstantInt>(CI)->getSExtValue() < 0) |
| Result = ConstantBool::getFalse(); |
| else |
| Result = ConstantBool::getTrue(); |
| } |
| } else { |
| // We're performing an unsigned comparison. |
| if (!isSignSrc) { |
| // Unsigned extend & compare -> always true. |
| Result = ConstantBool::getTrue(); |
| } else { |
| // We're performing an unsigned comp with a sign extended value. |
| // This is true if the input is >= 0. [aka >s -1] |
| Constant *NegOne = ConstantIntegral::getAllOnesValue(SrcTy); |
| Result = InsertNewInstBefore(BinaryOperator::createSetGT(LHSCIOp, |
| NegOne, SCI.getName()), SCI); |
| } |
| } |
| |
| // Finally, return the value computed. |
| if (SCI.getOpcode() == Instruction::SetLT) { |
| return ReplaceInstUsesWith(SCI, Result); |
| } else { |
| assert(SCI.getOpcode()==Instruction::SetGT &&"SetCC should be folded!"); |
| if (Constant *CI = dyn_cast<Constant>(Result)) |
| return ReplaceInstUsesWith(SCI, ConstantExpr::getNot(CI)); |
| else |
| return BinaryOperator::createNot(Result); |
| } |
| } |
| } else { |
| return 0; |
| } |
| |
| // Okay, just insert a compare of the reduced operands now! |
| return BinaryOperator::create(SCI.getOpcode(), LHSCIOp, RHSCIOp); |
| } |
| |
| Instruction *InstCombiner::visitShiftInst(ShiftInst &I) { |
| assert(I.getOperand(1)->getType() == Type::UByteTy); |
| Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); |
| bool isLeftShift = I.getOpcode() == Instruction::Shl; |
| |
| // shl X, 0 == X and shr X, 0 == X |
| // shl 0, X == 0 and shr 0, X == 0 |
| if (Op1 == Constant::getNullValue(Type::UByteTy) || |
| Op0 == Constant::getNullValue(Op0->getType())) |
| return ReplaceInstUsesWith(I, Op0); |
| |
| if (isa<UndefValue>(Op0)) { // undef >>s X -> undef |
| if (!isLeftShift && I.getType()->isSigned()) |
| return ReplaceInstUsesWith(I, Op0); |
| else // undef << X -> 0 AND undef >>u X -> 0 |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| } |
| if (isa<UndefValue>(Op1)) { |
| if (isLeftShift || I.getType()->isUnsigned())// X << undef, X >>u undef -> 0 |
| return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); |
| else |
| return ReplaceInstUsesWith(I, Op0); // X >>s undef -> X |
| } |
| |
| // ashr int -1, X = -1 (for any arithmetic shift rights of ~0) |
| if (I.getOpcode() == Instruction::AShr) |
| if (ConstantInt *CSI = dyn_cast<ConstantInt>(Op0)) |
| if (CSI->isAllOnesValue()) |
| return ReplaceInstUsesWith(I, CSI); |
| |
| // Try to fold constant and into select arguments. |
| if (isa<Constant>(Op0)) |
| if (SelectInst *SI = dyn_cast<SelectInst>(Op1)) |
| if (Instruction *R = FoldOpIntoSelect(I, SI, this)) |
| return R; |
| |
| // See if we can turn a signed shr into an unsigned shr. |
| if (I.isArithmeticShift()) { |
| if (MaskedValueIsZero(Op0, |
| 1ULL << (I.getType()->getPrimitiveSizeInBits()-1))) { |
| return new ShiftInst(Instruction::LShr, Op0, Op1, I.getName()); |
| } |
| } |
| |
| if (ConstantInt *CUI = dyn_cast<ConstantInt>(Op1)) |
| if (CUI->getType()->isUnsigned()) |
| if (Instruction *Res = FoldShiftByConstant(Op0, CUI, I)) |
| return Res; |
| return 0; |
| } |
| |
| Instruction *InstCombiner::FoldShiftByConstant(Value *Op0, ConstantInt *Op1, |
| ShiftInst &I) { |
| bool isLeftShift = I.getOpcode() == Instruction::Shl; |
| bool isSignedShift = isLeftShift ? Op0->getType()->isSigned() : |
| I.getOpcode() == Instruction::AShr; |
| bool isUnsignedShift = !isSignedShift; |
| |
| // See if we can simplify any instructions used by the instruction whose sole |
| // purpose is to compute bits we don't care about. |
| uint64_t KnownZero, KnownOne; |
| if (SimplifyDemandedBits(&I, I.getType()->getIntegralTypeMask(), |
| KnownZero, KnownOne)) |
| return &I; |
| |
| // shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr |
| // of a signed value. |
| // |
| unsigned TypeBits = Op0->getType()->getPrimitiveSizeInBits(); |
| if (Op1->getZExtValue() >= TypeBits) { |
| if (isUnsignedShift || isLeftShift) |
| return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType())); |
| else { |
| I.setOperand(1, ConstantInt::get(Type::UByteTy, TypeBits-1)); |
| return &I; |
| } |
| } |
| |
| // ((X*C1) << C2) == (X * (C1 << C2)) |
| if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0)) |
| if (BO->getOpcode() == Instruction::Mul && isLeftShift) |
| if (Constant *BOOp = dyn_cast<Constant>(BO->getOperand(1))) |
| return BinaryOperator::createMul(BO->getOperand(0), |
| ConstantExpr::getShl(BOOp, 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; |
| |
| 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_ConstantInt(CC))) && CC == Op1) { |
| Instruction *YS = new ShiftInst(Instruction::Shl, |
| 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)) |
| Constant *C2 = ConstantInt::getAllOnesValue(X->getType()); |
| C2 = ConstantExpr::getShl(C2, Op1); |
| return BinaryOperator::createAnd(X, C2); |
| } |
| |
| // Turn (Y + ((X >> C) & CC)) << C -> ((X & (CC << C)) + (Y << C)) |
| if (isLeftShift && Op0BO->getOperand(1)->hasOneUse() && |
| match(Op0BO->getOperand(1), |
| m_And(m_Shr(m_Value(V1), m_Value(V2)), |
| m_ConstantInt(CC))) && V2 == Op1 && |
| cast<BinaryOperator>(Op0BO->getOperand(1))->getOperand(0)->hasOneUse()) { |
| Instruction *YS = new ShiftInst(Instruction::Shl, |
| 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_ConstantInt(CC))) && CC == Op1) { |
| Instruction *YS = new ShiftInst(Instruction::Shl, |
| 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)) |
| Constant *C2 = ConstantInt::getAllOnesValue(X->getType()); |
| C2 = ConstantExpr::getShl(C2, Op1); |
| return BinaryOperator::createAnd(X, C2); |
| } |
| |
| // 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 = new ShiftInst(Instruction::Shl, |
| 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 && !isLeftShift && isSignedShift) { |
| uint64_t Val = Op0C->getZExtValue(); |
| isValid = ((Val & (1 << (TypeBits-1))) != 0) == highBitSet; |
| } |
| |
| if (isValid) { |
| Constant *NewRHS = ConstantExpr::get(I.getOpcode(), Op0C, Op1); |
| |
| Instruction *NewShift = |
| new ShiftInst(I.getOpcode(), Op0BO->getOperand(0), Op1, |
| Op0BO->getName()); |
| Op0BO->setName(""); |
| InsertNewInstBefore(NewShift, I); |
| |
| return BinaryOperator::create(Op0BO->getOpcode(), NewShift, |
| NewRHS); |
| } |
| } |
| } |
| } |
| |
| // Find out if this is a shift of a shift by a constant. |
| ShiftInst *ShiftOp = 0; |
| if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0)) |
| ShiftOp = Op0SI; |
| else if (BitCastInst *CI = dyn_cast<BitCastInst>(Op0)) { |
| // If this is a noop-integer cast of a shift instruction, use the shift. |
| if (isa<ShiftInst>(CI->getOperand(0))) { |
| ShiftOp = cast<ShiftInst>(CI->getOperand(0)); |
| } |
| } |
| |
| if (ShiftOp && isa<ConstantInt>(ShiftOp->getOperand(1))) { |
| // Find the operands and properties of the input shift. Note that the |
| // signedness of the input shift may differ from the current shift if there |
| // is a noop cast between the two. |
| bool isShiftOfLeftShift = ShiftOp->getOpcode() == Instruction::Shl; |
| bool isShiftOfSignedShift = isShiftOfLeftShift ? |
| ShiftOp->getType()->isSigned() : |
| ShiftOp->getOpcode() == Instruction::AShr; |
| bool isShiftOfUnsignedShift = !isShiftOfSignedShift; |
| |
| ConstantInt *ShiftAmt1C = cast<ConstantInt>(ShiftOp->getOperand(1)); |
| |
| unsigned ShiftAmt1 = (unsigned)ShiftAmt1C->getZExtValue(); |
| unsigned ShiftAmt2 = (unsigned)Op1->getZExtValue(); |
| |
| // Check for (A << c1) << c2 and (A >> c1) >> c2. |
| if (isLeftShift == isShiftOfLeftShift) { |
| // Do not fold these shifts if the first one is signed and the second one |
| // is unsigned and this is a right shift. Further, don't do any folding |
| // on them. |
| if (isShiftOfSignedShift && isUnsignedShift && !isLeftShift) |
| return 0; |
| |
| unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift. |
| if (Amt > Op0->getType()->getPrimitiveSizeInBits()) |
| Amt = Op0->getType()->getPrimitiveSizeInBits(); |
| |
| Value *Op = ShiftOp->getOperand(0); |
| if (isShiftOfSignedShift != isSignedShift) |
| Op = InsertNewInstBefore( |
| CastInst::createInferredCast(Op, I.getType(), "tmp"), I); |
| ShiftInst *ShiftResult = new ShiftInst(I.getOpcode(), Op, |
| ConstantInt::get(Type::UByteTy, Amt)); |
| if (I.getType() == ShiftResult->getType()) |
| return ShiftResult; |
| InsertNewInstBefore(ShiftResult, I); |
| return CastInst::create(Instruction::BitCast, ShiftResult, I.getType()); |
| } |
| |
| // Check for (A << c1) >> c2 or (A >> c1) << c2. If we are dealing with |
| // signed types, we can only support the (A >> c1) << c2 configuration, |
| // because it can not turn an arbitrary bit of A into a sign bit. |
| if (isUnsignedShift || isLeftShift) { |
| // Calculate bitmask for what gets shifted off the edge. |
| Constant *C = ConstantIntegral::getAllOnesValue(I.getType()); |
| if (isLeftShift) |
| C = ConstantExpr::getShl(C, ShiftAmt1C); |
| else |
| C = ConstantExpr::getLShr(C, ShiftAmt1C); |
| |
| Value *Op = ShiftOp->getOperand(0); |
| if (Op->getType() != C->getType()) |
| Op = InsertCastBefore(Op, I.getType(), I); |
| |
| Instruction *Mask = |
| BinaryOperator::createAnd(Op, C, Op->getName()+".mask"); |
| InsertNewInstBefore(Mask, I); |
| |
| // Figure out what flavor of shift we should use... |
| if (ShiftAmt1 == ShiftAmt2) { |
| return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2 |
| } else if (ShiftAmt1 < ShiftAmt2) { |
| return new ShiftInst(I.getOpcode(), Mask, |
| ConstantInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1)); |
| } else if (isShiftOfUnsignedShift || isShiftOfLeftShift) { |
| if (isShiftOfUnsignedShift && !isShiftOfLeftShift && isSignedShift) { |
| return new ShiftInst(Instruction::LShr, Mask, |
| ConstantInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2)); |
| } else { |
| return new ShiftInst(ShiftOp->getOpcode(), Mask, |
| ConstantInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2)); |
| } |
| } else { |
| // (X >>s C1) << C2 where C1 > C2 === (X >>s (C1-C2)) & mask |
| Op = InsertCastBefore(Mask, I.getType()->getSignedVersion(), I); |
| Instruction *Shift = |
| new ShiftInst(ShiftOp->getOpcode(), Op, |
| ConstantInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2)); |
| InsertNewInstBefore(Shift, I); |
| |
| C = ConstantIntegral::getAllOnesValue(Shift->getType()); |
| C = ConstantExpr::getShl(C, Op1); |
| Mask = BinaryOperator::createAnd(Shift, C, Op->getName()+".mask"); |
| InsertNewInstBefore(Mask, I); |
| return CastInst::create(Instruction::BitCast, Mask, I.getType()); |
| } |
| } else { |
| // We can handle signed (X << C1) >>s C2 if it's a sign extend. In |
| // this case, C1 == C2 and C1 is 8, 16, or 32. |
| if (ShiftAmt1 == ShiftAmt2) { |
| const Type *SExtType = 0; |
| switch (Op0->getType()->getPrimitiveSizeInBits() - ShiftAmt1) { |
| case 8 : SExtType = Type::SByteTy; break; |
| case 16: SExtType = Type::ShortTy; break; |
| case 32: SExtType = Type::IntTy; break; |
| } |
| |
| if (SExtType) { |
| Instruction *NewTrunc = |
| new TruncInst(ShiftOp->getOperand(0), SExtType, "sext"); |
| InsertNewInstBefore(NewTrunc, I); |
| return new SExtInst(NewTrunc, I.getType()); |
| } |
| } |
| } |
| } |
| 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, |
| unsigned &Offset) { |
| assert(Val->getType() == Type::UIntTy && "Unexpected allocation size type!"); |
| if (ConstantInt *CI = dyn_cast<ConstantInt>(Val)) { |
| if (CI->getType()->isUnsigned()) { |
| Offset = CI->getZExtValue(); |
| Scale = 1; |
| return ConstantInt::get(Type::UIntTy, 0); |
| } |
| } else if (Instruction *I = dyn_cast<Instruction>(Val)) { |
| if (I->getNumOperands() == 2) { |
| if (ConstantInt *CUI = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| if (CUI->getType()->isUnsigned()) { |
| if (I->getOpcode() == Instruction::Shl) { |
| // This is a value scaled by '1 << the shift amt'. |
| Scale = 1U << CUI->getZExtValue(); |
| Offset = 0; |
| return I->getOperand(0); |
| } else if (I->getOpcode() == Instruction::Mul) { |
| // This value is scaled by 'CUI'. |
| Scale = CUI->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 += CUI->getZExtValue(); |
| if (SubScale > 1 && (Offset % SubScale == 0)) { |
| 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(CastInst &CI, |
| AllocationInst &AI) { |
| const PointerType *PTy = dyn_cast<PointerType>(CI.getType()); |
| if (!PTy) return 0; // Not casting the allocation to a pointer type. |
| |
| // Remove any uses of AI that are dead. |
| assert(!CI.use_empty() && "Dead instructions should be removed earlier!"); |
| std::vector<Instruction*> DeadUsers; |
| 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. |
| |
| // Add operands to the worklist. |
| AddUsesToWorkList(*User); |
| ++NumDeadInst; |
| DOUT << "IC: DCE: " << *User; |
| |
| User->eraseFromParent(); |
| removeFromWorkList(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->getTypeAlignment(AllocElTy); |
| unsigned CastElTyAlign = TD->getTypeAlignment(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->getTypeSize(AllocElTy); |
| uint64_t CastElTySize = TD->getTypeSize(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, 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::UIntTy, Scale); |
| if (isa<ConstantInt>(NumElements) && NumElements->getType()->isUnsigned()) |
| Amt = ConstantExpr::getMul( |
| 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 (unsigned Offset = (AllocElTySize*ArrayOffset)/CastElTySize) { |
| Value *Off = ConstantInt::get(Type::UIntTy, Offset); |
| Instruction *Tmp = BinaryOperator::createAdd(Amt, Off, "tmp"); |
| Amt = InsertNewInstBefore(Tmp, AI); |
| } |
| |
| std::string Name = AI.getName(); AI.setName(""); |
| AllocationInst *New; |
| if (isa<MallocInst>(AI)) |
| New = new MallocInst(CastElTy, Amt, AI.getAlignment(), Name); |
| else |
| New = new AllocaInst(CastElTy, Amt, AI.getAlignment(), Name); |
| InsertNewInstBefore(New, 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 without inserting any new casts. 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. |
| static bool CanEvaluateInDifferentType(Value *V, const Type *Ty, |
| int &NumCastsRemoved) { |
| if (isa<Constant>(V)) return true; |
| |
| Instruction *I = dyn_cast<Instruction>(V); |
| if (!I || !I->hasOneUse()) return false; |
| |
| switch (I->getOpcode()) { |
| case Instruction::And: |
| case Instruction::Or: |
| case Instruction::Xor: |
| // These operators can all arbitrarily be extended or truncated. |
| return CanEvaluateInDifferentType(I->getOperand(0), Ty, NumCastsRemoved) && |
| CanEvaluateInDifferentType(I->getOperand(1), Ty, NumCastsRemoved); |
| case Instruction::Trunc: |
| case Instruction::ZExt: |
| case Instruction::SExt: |
| case Instruction::BitCast: |
| // 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))) |
| return true; |
| |
| ++NumCastsRemoved; |
| return true; |
| } |
| break; |
| 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) { |
| if (Constant *C = dyn_cast<Constant>(V)) |
| return ConstantExpr::getCast(C, Ty); |
| |
| // Otherwise, it must be an instruction. |
| Instruction *I = cast<Instruction>(V); |
| Instruction *Res = 0; |
| switch (I->getOpcode()) { |
| case Instruction::And: |
| case Instruction::Or: |
| case Instruction::Xor: { |
| Value *LHS = EvaluateInDifferentType(I->getOperand(0), Ty); |
| Value *RHS = EvaluateInDifferentType(I->getOperand(1), Ty); |
| Res = BinaryOperator::create((Instruction::BinaryOps)I->getOpcode(), |
| LHS, RHS, I->getName()); |
| break; |
| } |
| case Instruction::Trunc: |
| case Instruction::ZExt: |
| case Instruction::SExt: |
| case Instruction::BitCast: |
| // 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 its not new. |
| if (I->getOperand(0)->getType() == Ty) |
| return I->getOperand(0); |
| |
| // Some other kind of cast, which shouldn't happen, so just .. |
| // FALL THROUGH |
| default: |
| // TODO: Can handle more cases here. |
| assert(0 && "Unreachable!"); |
| break; |
| } |
| |
| return InsertNewInstBefore(Res, *I); |
| } |
| |
| /// @brief Implement the transforms common to all CastInst visitors. |
| Instruction *InstCombiner::commonCastTransforms(CastInst &CI) { |
| Value *Src = CI.getOperand(0); |
| |
| // Casting undef to anything results in undef so might as just replace it and |
| // get rid of the cast. |
| if (isa<UndefValue>(Src)) // cast undef -> undef |
| return ReplaceInstUsesWith(CI, UndefValue::get(CI.getType())); |
| |
| // Many cases of "cast of a cast" are eliminable. If its 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 casting the result of a getelementptr instruction with no offset, turn |
| // this into a cast of the original pointer! |
| // |
| if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) { |
| bool AllZeroOperands = true; |
| for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i) |
| if (!isa<Constant>(GEP->getOperand(i)) || |
| !cast<Constant>(GEP->getOperand(i))->isNullValue()) { |
| AllZeroOperands = false; |
| break; |
| } |
| if (AllZeroOperands) { |
| // 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. |
| CI.setOperand(0, GEP->getOperand(0)); |
| return &CI; |
| } |
| } |
| |
| // If we are casting a malloc or alloca to a pointer to a type of the same |
| // size, rewrite the allocation instruction to allocate the "right" type. |
| if (AllocationInst *AI = dyn_cast<AllocationInst>(Src)) |
| if (Instruction *V = PromoteCastOfAllocation(CI, *AI)) |
| return V; |
| |
| // 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; |
| } |
| |
| /// Only the TRUNC, ZEXT, SEXT, and BITCONVERT can have both operands as |
| /// integers. 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(); |
| unsigned SrcBitSize = SrcTy->getPrimitiveSizeInBits(); |
| unsigned DestBitSize = DestTy->getPrimitiveSizeInBits(); |
| |
| // FIXME. We currently implement cast-to-bool as a setne %X, 0. This is |
| // because codegen cannot accurately perform a truncate to bool operation. |
| // Something goes wrong in promotion to a larger type. When CodeGen can |
| // handle a proper truncation to bool, this should be removed. |
| if (DestTy == Type::BoolTy) |
| return BinaryOperator::createSetNE(Src, Constant::getNullValue(SrcTy)); |
| |
| // See if we can simplify any instructions used by the LHS whose sole |
| // purpose is to compute bits we don't care about. |
| uint64_t KnownZero = 0, KnownOne = 0; |
| if (SimplifyDemandedBits(&CI, DestTy->getIntegralTypeMask(), |
| KnownZero, KnownOne)) |
| return &CI; |
| |
| // If the source isn't an instruction or has more than one use then we |
| // can't do anything more. |
| if (!isa<Instruction>(Src) || !Src->hasOneUse()) |
| return 0; |
| |
| // Attempt to propagate the cast into the instruction. |
| Instruction *SrcI = cast<Instruction>(Src); |
| int NumCastsRemoved = 0; |
| if (CanEvaluateInDifferentType(SrcI, DestTy, 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 noop-cast |
| // this just removes a noop cast which isn't pointful, but simplifies |
| // the code. 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 = CI.isNoopCast(TD->getIntPtrType()); |
| if (!DoXForm) { |
| switch (CI.getOpcode()) { |
| case Instruction::Trunc: |
| DoXForm = true; |
| break; |
| case Instruction::ZExt: |
| DoXForm = NumCastsRemoved >= 1; |
| break; |
| case Instruction::SExt: |
| DoXForm = NumCastsRemoved >= 2; |
| break; |
| case Instruction::BitCast: |
| DoXForm = false; |
| break; |
| default: |
| // All the others use floating point so we shouldn't actually |
| // get here because of the check above. |
| assert(!"Unknown cast type .. unreachable"); |
| break; |
| } |
| } |
| |
| if (DoXForm) { |
| Value *Res = EvaluateInDifferentType(SrcI, DestTy); |
| 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(Type::ULongTy, (1ULL << SrcBitSize)-1); |
| if (DestBitSize < 64) |
| C = ConstantExpr::getTrunc(C, DestTy); |
| else { |
| assert(DestBitSize == 64); |
| C = ConstantExpr::getBitCast(C, DestTy); |
| } |
| 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(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, or just changing the sign, |
| // rewrite. |
| if (DestBitSize <= SrcBitSize && DestBitSize != 1) { |
| // Don't insert two casts if they cannot be eliminated. We allow |
| // two casts to be inserted if the sizes are the same. This could |
| // only be converting signedness, which is a noop. |
| if (DestBitSize == SrcBitSize || |
| !ValueRequiresCast(Op1, DestTy,TD) || |
| !ValueRequiresCast(Op0, DestTy, TD)) { |
| Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI); |
| Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI); |
| return BinaryOperator::create(cast<BinaryOperator>(SrcI) |
| ->getOpcode(), Op0c, Op1c); |
| } |
| } |
| |
| // cast (xor bool X, true) to int --> xor (cast bool X to int), 1 |
| if (isa<ZExtInst>(CI) && SrcBitSize == 1 && |
| SrcI->getOpcode() == Instruction::Xor && |
| Op1 == ConstantBool::getTrue() && |
| (!Op0->hasOneUse() || !isa<SetCondInst>(Op0))) { |
| Value *New = InsertOperandCastBefore(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(Op1, DestTy,TD) || |
| !ValueRequiresCast(Op0, DestTy, TD)) { |
| Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI); |
| Value *Op1c = InsertOperandCastBefore(Op1, DestTy, SrcI); |
| return BinaryOperator::create( |
| cast<BinaryOperator>(SrcI)->getOpcode(), Op0c, Op1c); |
| } |
| } |
| 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))) { |
| Value *Op0c = InsertOperandCastBefore(Op0, DestTy, SrcI); |
| return new ShiftInst(Instruction::Shl, Op0c, Op1); |
| } |
| 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)) { |
| unsigned ShiftAmt = cast<ConstantInt>(Op1)->getZExtValue(); |
| if (SrcBitSize > ShiftAmt && SrcBitSize-ShiftAmt >= DestBitSize) { |
| // Insert the new logical shift right. |
| return new ShiftInst(Instruction::LShr, Op0, Op1); |
| } |
| } |
| break; |
| |
| case Instruction::SetEQ: |
| case Instruction::SetNE: |
| // If we are just checking for a seteq of a single bit and casting it |
| // to an integer. If so, shift the bit to the appropriate place then |
| // cast to integer to avoid the comparison. |
| if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) { |
| uint64_t Op1CV = Op1C->getZExtValue(); |
| // cast (X == 0) to int --> X^1 iff X has only the low bit set. |
| // cast (X == 0) to int --> (X>>1)^1 iff X has only the 2nd bit set. |
| // cast (X == 1) to int --> X iff X has only the low bit set. |
| // cast (X == 2) to int --> X>>1 iff X has only the 2nd bit set. |
| // cast (X != 0) to int --> X iff X has only the low bit set. |
| // cast (X != 0) to int --> X>>1 iff X has only the 2nd bit set. |
| // cast (X != 1) to int --> X^1 iff X has only the low bit set. |
| // cast (X != 2) to int --> (X>>1)^1 iff X has only the 2nd bit set. |
| if (Op1CV == 0 || isPowerOf2_64(Op1CV)) { |
| // If Op1C some other power of two, convert: |
| uint64_t KnownZero, KnownOne; |
| uint64_t TypeMask = Op1->getType()->getIntegralTypeMask(); |
| ComputeMaskedBits(Op0, TypeMask, KnownZero, KnownOne); |
| |
| if (isPowerOf2_64(KnownZero^TypeMask)) { // Exactly 1 possible 1? |
| bool isSetNE = SrcI->getOpcode() == Instruction::SetNE; |
| if (Op1CV && (Op1CV != (KnownZero^TypeMask))) { |
| // (X&4) == 2 --> false |
| // (X&4) != 2 --> true |
| Constant *Res = ConstantBool::get(isSetNE); |
| Res = ConstantExpr::getZeroExtend(Res, CI.getType()); |
| return ReplaceInstUsesWith(CI, Res); |
| } |
| |
| unsigned ShiftAmt = Log2_64(KnownZero^TypeMask); |
| Value *In = Op0; |
| if (ShiftAmt) { |
| // Perform a logical shr by shiftamt. |
| // Insert the shift to put the result in the low bit. |
| In = InsertNewInstBefore( |
| new ShiftInst(Instruction::LShr, In, |
| ConstantInt::get(Type::UByteTy, ShiftAmt), |
| In->getName()+".lobit"), CI); |
| } |
| |
| if ((Op1CV != 0) == isSetNE) { // 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::createInferredCast(In, CI.getType()); |
| } |
| } |
| } |
| break; |
| } |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitTrunc(CastInst &CI) { |
| return commonIntCastTransforms(CI); |
| } |
| |
| Instruction *InstCombiner::visitZExt(CastInst &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 the operand of the ZEXT is a TRUNC then we are dealing with integral |
| // types and we can convert this to a logical AND if the sizes are just |
| // right. This will be much cheaper than the pair of casts. |
| // 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); |
| unsigned SrcSize = A->getType()->getPrimitiveSizeInBits(); |
| unsigned MidSize = CSrc->getType()->getPrimitiveSizeInBits(); |
| unsigned 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. |
| uint64_t AndValue = CSrc->getType()->getIntegralTypeMask(); |
| Constant *AndConst = ConstantInt::get(A->getType(), 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::createInferredCast(And, CI.getType()); |
| } |
| return And; |
| } |
| } |
| } |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitSExt(CastInst &CI) { |
| return commonIntCastTransforms(CI); |
| } |
| |
| Instruction *InstCombiner::visitFPTrunc(CastInst &CI) { |
| return commonCastTransforms(CI); |
| } |
| |
| Instruction *InstCombiner::visitFPExt(CastInst &CI) { |
| return commonCastTransforms(CI); |
| } |
| |
| Instruction *InstCombiner::visitFPToUI(CastInst &CI) { |
| if (Instruction *I = commonCastTransforms(CI)) |
| return I; |
| |
| // FIXME. We currently implement cast-to-bool as a setne %X, 0. This is |
| // because codegen cannot accurately perform a truncate to bool operation. |
| // Something goes wrong in promotion to a larger type. When CodeGen can |
| // handle a proper truncation to bool, this should be removed. |
| Value *Src = CI.getOperand(0); |
| const Type *SrcTy = Src->getType(); |
| const Type *DestTy = CI.getType(); |
| if (DestTy == Type::BoolTy) |
| return BinaryOperator::createSetNE(Src, Constant::getNullValue(SrcTy)); |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitFPToSI(CastInst &CI) { |
| if (Instruction *I = commonCastTransforms(CI)) |
| return I; |
| |
| // FIXME. We currently implement cast-to-bool as a setne %X, 0. This is |
| // because codegen cannot accurately perform a truncate to bool operation. |
| // Something goes wrong in promotion to a larger type. When CodeGen can |
| // handle a proper truncation to bool, this should be removed. |
| Value *Src = CI.getOperand(0); |
| const Type *SrcTy = Src->getType(); |
| const Type *DestTy = CI.getType(); |
| if (DestTy == Type::BoolTy) |
| return BinaryOperator::createSetNE(Src, Constant::getNullValue(SrcTy)); |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitUIToFP(CastInst &CI) { |
| return commonCastTransforms(CI); |
| } |
| |
| Instruction *InstCombiner::visitSIToFP(CastInst &CI) { |
| return commonCastTransforms(CI); |
| } |
| |
| Instruction *InstCombiner::visitPtrToInt(CastInst &CI) { |
| if (Instruction *I = commonCastTransforms(CI)) |
| return I; |
| |
| // FIXME. We currently implement cast-to-bool as a setne %X, 0. This is |
| // because codegen cannot accurately perform a truncate to bool operation. |
| // Something goes wrong in promotion to a larger type. When CodeGen can |
| // handle a proper truncation to bool, this should be removed. |
| Value *Src = CI.getOperand(0); |
| const Type *SrcTy = Src->getType(); |
| const Type *DestTy = CI.getType(); |
| if (DestTy == Type::BoolTy) |
| return BinaryOperator::createSetNE(Src, Constant::getNullValue(SrcTy)); |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitIntToPtr(CastInst &CI) { |
| return commonCastTransforms(CI); |
| } |
| |
| Instruction *InstCombiner::visitBitCast(CastInst &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 (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 the source and destination are pointers, and this cast is equivalent to |
| // a getelementptr X, 0, 0, 0... turn it into the appropriate getelementptr. |
| // This can enhance SROA and other transforms that want type-safe pointers. |
| if (const PointerType *DstPTy = dyn_cast<PointerType>(DestTy)) { |
| if (const PointerType *SrcPTy = dyn_cast<PointerType>(SrcTy)) { |
| const Type *DstElTy = DstPTy->getElementType(); |
| const Type *SrcElTy = SrcPTy->getElementType(); |
| |
| Constant *ZeroUInt = Constant::getNullValue(Type::UIntTy); |
| 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) { |
| std::vector<Value*> Idxs(NumZeros+1, ZeroUInt); |
| return new GetElementPtrInst(Src, Idxs); |
| } |
| } |
| } |
| |
| 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<PackedType>(DestTy) && |
| cast<PackedType>(DestTy)->getNumElements() == |
| SVI->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 = InsertOperandCastBefore(SVI->getOperand(0), DestTy, &CI); |
| Value *RHS = InsertOperandCastBefore(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: |
| return Constant::getNullValue(I->getType()); |
| case Instruction::Shl: |
| case Instruction::LShr: |
| case Instruction::AShr: |
| return Constant::getNullValue(Type::UByteTy); |
| case Instruction::And: |
| return ConstantInt::getAllOnesValue(I->getType()); |
| case Instruction::Mul: |
| return ConstantInt::get(I->getType(), 1); |
| } |
| } |
| |
| /// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI |
| /// have the same opcode and only one use each. Try to simplify this. |
| Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI, |
| Instruction *FI) { |
| if (TI->getNumOperands() == 1) { |
| // If this is a non-volatile load or a cast from the same type, |
| // merge. |
| if (TI->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 = new SelectInst(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<ShiftInst>(TI) && !isa<BinaryOperator>(TI)) |
| return 0; |
| |
| // Figure out if the operations have any operands in common. |
| Value *MatchOp, *OtherOpT, *OtherOpF; |
| bool MatchIsOpZero; |
| if (TI->getOperand(0) == FI->getOperand(0)) { |
| MatchOp = TI->getOperand(0); |
| OtherOpT = TI->getOperand(1); |
| OtherOpF = FI->getOperand(1); |
| MatchIsOpZero = true; |
| } else if (TI->getOperand(1) == FI->getOperand(1)) { |
| MatchOp = TI->getOperand(1); |
| OtherOpT = TI->getOperand(0); |
| OtherOpF = FI->getOperand(0); |
| MatchIsOpZero = false; |
| } else if (!TI->isCommutative()) { |
| return 0; |
| } else if (TI->getOperand(0) == FI->getOperand(1)) { |
| MatchOp = TI->getOperand(0); |
| OtherOpT = TI->getOperand(1); |
| OtherOpF = FI->getOperand(0); |
| MatchIsOpZero = true; |
| } else if (TI->getOperand(1) == FI->getOperand(0)) { |
| MatchOp = TI->getOperand(1); |
| OtherOpT = TI->getOperand(0); |
| OtherOpF = FI->getOperand(1); |
| MatchIsOpZero = true; |
| } else { |
| return 0; |
| } |
| |
| // If we reach here, they do have operations in common. |
| SelectInst *NewSI = new SelectInst(SI.getCondition(), OtherOpT, |
| OtherOpF, SI.getName()+".v"); |
| InsertNewInstBefore(NewSI, SI); |
| |
| if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) { |
| if (MatchIsOpZero) |
| return BinaryOperator::create(BO->getOpcode(), MatchOp, NewSI); |
| else |
| return BinaryOperator::create(BO->getOpcode(), NewSI, MatchOp); |
| } else { |
| if (MatchIsOpZero) |
| return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), MatchOp, NewSI); |
| else |
| return new ShiftInst(cast<ShiftInst>(TI)->getOpcode(), NewSI, MatchOp); |
| } |
| } |
| |
| Instruction *InstCombiner::visitSelectInst(SelectInst &SI) { |
| Value *CondVal = SI.getCondition(); |
| Value *TrueVal = SI.getTrueValue(); |
| Value *FalseVal = SI.getFalseValue(); |
| |
| // select true, X, Y -> X |
| // select false, X, Y -> Y |
| if (ConstantBool *C = dyn_cast<ConstantBool>(CondVal)) |
| return ReplaceInstUsesWith(SI, C->getValue() ? 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::BoolTy) |
| if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) { |
| if (C->getValue()) { |
| // Change: A = select B, true, C --> A = or B, C |
| return BinaryOperator::createOr(CondVal, FalseVal); |
| } else { |
| // Change: A = select B, false, C --> A = and !B, C |
| Value *NotCond = |
| InsertNewInstBefore(BinaryOperator::createNot(CondVal, |
| "not."+CondVal->getName()), SI); |
| return BinaryOperator::createAnd(NotCond, FalseVal); |
| } |
| } else if (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) { |
| if (C->getValue() == false) { |
| // Change: A = select B, C, false --> A = and B, C |
| return BinaryOperator::createAnd(CondVal, TrueVal); |
| } else { |
| // Change: A = select B, C, true --> A = or !B, C |
| Value *NotCond = |
| InsertNewInstBefore(BinaryOperator::createNot(CondVal, |
| "not."+CondVal->getName()), SI); |
| return BinaryOperator::createOr(NotCond, TrueVal); |
| } |
| } |
| |
| // Selecting between two integer constants? |
| if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal)) |
| if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) { |
| // select C, 1, 0 -> cast C to int |
| if (FalseValC->isNullValue() && TrueValC->getZExtValue() == 1) { |
| return CastInst::create(Instruction::ZExt, CondVal, SI.getType()); |
| } else if (TrueValC->isNullValue() && FalseValC->getZExtValue() == 1) { |
| // select C, 0, 1 -> cast !C to int |
| Value *NotCond = |
| InsertNewInstBefore(BinaryOperator::createNot(CondVal, |
| "not."+CondVal->getName()), SI); |
| return CastInst::create(Instruction::ZExt, NotCond, SI.getType()); |
| } |
| |
| if (SetCondInst *IC = dyn_cast<SetCondInst>(SI.getCondition())) { |
| |
| // (x <s 0) ? -1 : 0 -> sra x, 31 |
| // (x >u 2147483647) ? -1 : 0 -> sra x, 31 |
| if (TrueValC->isAllOnesValue() && FalseValC->isNullValue()) |
| if (ConstantInt *CmpCst = dyn_cast<ConstantInt>(IC->getOperand(1))) { |
| bool CanXForm = false; |
| if (CmpCst->getType()->isSigned()) |
| CanXForm = CmpCst->isNullValue() && |
| IC->getOpcode() == Instruction::SetLT; |
| else { |
| unsigned Bits = CmpCst->getType()->getPrimitiveSizeInBits(); |
| CanXForm = (CmpCst->getZExtValue() == ~0ULL >> (64-Bits+1)) && |
| IC->getOpcode() == Instruction::SetGT; |
| } |
| |
| if (CanXForm) { |
| // 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); |
| unsigned Bits = X->getType()->getPrimitiveSizeInBits(); |
| Constant *ShAmt = ConstantInt::get(Type::UByteTy, Bits-1); |
| Instruction *SRA = new ShiftInst(Instruction::AShr, X, |
| ShAmt, "ones"); |
| InsertNewInstBefore(SRA, SI); |
| |
| // Finally, convert to the type of the select RHS. We figure out |
| // if this requires a SExt, Trunc or BitCast based on the sizes. |
| Instruction::CastOps opc = Instruction::BitCast; |
| unsigned SRASize = SRA->getType()->getPrimitiveSizeInBits(); |
| unsigned SISize = SI.getType()->getPrimitiveSizeInBits(); |
| if (SRASize < SISize) |
| opc = Instruction::SExt; |
| else if (SRASize > SISize) |
| opc = Instruction::Trunc; |
| return CastInst::create(opc, SRA, SI.getType()); |
| } |
| } |
| |
| |
| // If one of the constants is zero (we know they can't both be) and we |
| // have a setcc instruction with zero, and we have an 'and' with the |
| // non-constant value, eliminate this whole mess. This corresponds to |
| // cases like this: ((X & 27) ? 27 : 0) |
| if (TrueValC->isNullValue() || FalseValC->isNullValue()) |
| if (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 setne or seteq and whether the true or |
| // false val is the zero. |
| bool ShouldNotVal = !TrueValC->isNullValue(); |
| ShouldNotVal ^= IC->getOpcode() == Instruction::SetNE; |
| Value *V = ICA; |
| if (ShouldNotVal) |
| V = InsertNewInstBefore(BinaryOperator::create( |
| Instruction::Xor, V, ICA->getOperand(1)), SI); |
| return ReplaceInstUsesWith(SI, V); |
| } |
| } |
| } |
| |
| // See if we are selecting two values based on a comparison of the two values. |
| if (SetCondInst *SCI = dyn_cast<SetCondInst>(CondVal)) { |
| if (SCI->getOperand(0) == TrueVal && SCI->getOperand(1) == FalseVal) { |
| // Transform (X == Y) ? X : Y -> Y |
| if (SCI->getOpcode() == Instruction::SetEQ) |
| return ReplaceInstUsesWith(SI, FalseVal); |
| // Transform (X != Y) ? X : Y -> X |
| if (SCI->getOpcode() == Instruction::SetNE) |
| return ReplaceInstUsesWith(SI, TrueVal); |
| // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc. |
| |
| } else if (SCI->getOperand(0) == FalseVal && SCI->getOperand(1) == TrueVal){ |
| // Transform (X == Y) ? Y : X -> X |
| if (SCI->getOpcode() == Instruction::SetEQ) |
| return ReplaceInstUsesWith(SI, FalseVal); |
| // Transform (X != Y) ? Y : X -> Y |
| if (SCI->getOpcode() == Instruction::SetNE) |
| return ReplaceInstUsesWith(SI, TrueVal); |
| // NOTE: if we wanted to, this is where to detect MIN/MAX/ABS/etc. |
| } |
| } |
| |
| if (Instruction *TI = dyn_cast<Instruction>(TrueVal)) |
| if (Instruction *FI = dyn_cast<Instruction>(FalseVal)) |
| if (TI->hasOneUse() && FI->hasOneUse()) { |
| 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 = |
| new SelectInst(CondVal, NewTrueOp,NewFalseOp,SI.getName()+".p"); |
| |
| NewSel = InsertNewInstBefore(NewSel, SI); |
| return BinaryOperator::createAdd(SubOp->getOperand(0), NewSel); |
| } |
| } |
| } |
| |
| // See if we can fold the select into one of our operands. |
| if (SI.getType()->isInteger()) { |
| // See the comment above GetSelectFoldableOperands for a description of the |
| // transformation we are doing here. |
| if (Instruction *TVI = dyn_cast<Instruction>(TrueVal)) |
| if (TVI->hasOneUse() && TVI->getNumOperands() == 2 && |
| !isa<Constant>(FalseVal)) |
| if (unsigned SFO = GetSelectFoldableOperands(TVI)) { |
| unsigned OpToFold = 0; |
| if ((SFO & 1) && FalseVal == TVI->getOperand(0)) { |
| OpToFold = 1; |
| } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) { |
| OpToFold = 2; |
| } |
| |
| if (OpToFold) { |
| Constant *C = GetSelectFoldableConstant(TVI); |
| std::string Name = TVI->getName(); TVI->setName(""); |
| Instruction *NewSel = |
| new SelectInst(SI.getCondition(), TVI->getOperand(2-OpToFold), C, |
| Name); |
| InsertNewInstBefore(NewSel, SI); |
| if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI)) |
| return BinaryOperator::create(BO->getOpcode(), FalseVal, NewSel); |
| else if (ShiftInst *SI = dyn_cast<ShiftInst>(TVI)) |
| return new ShiftInst(SI->getOpcode(), FalseVal, NewSel); |
| else { |
| assert(0 && "Unknown instruction!!"); |
| } |
| } |
| } |
| |
| if (Instruction *FVI = dyn_cast<Instruction>(FalseVal)) |
| if (FVI->hasOneUse() && FVI->getNumOperands() == 2 && |
| !isa<Constant>(TrueVal)) |
| if (unsigned SFO = GetSelectFoldableOperands(FVI)) { |
| unsigned OpToFold = 0; |
| if ((SFO & 1) && TrueVal == FVI->getOperand(0)) { |
| OpToFold = 1; |
| } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) { |
| OpToFold = 2; |
| } |
| |
| if (OpToFold) { |
| Constant *C = GetSelectFoldableConstant(FVI); |
| std::string Name = FVI->getName(); FVI->setName(""); |
| Instruction *NewSel = |
| new SelectInst(SI.getCondition(), C, FVI->getOperand(2-OpToFold), |
| Name); |
| InsertNewInstBefore(NewSel, SI); |
| if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI)) |
| return BinaryOperator::create(BO->getOpcode(), TrueVal, NewSel); |
| else if (ShiftInst *SI = dyn_cast<ShiftInst>(FVI)) |
| return new ShiftInst(SI->getOpcode(), TrueVal, NewSel); |
| else { |
| assert(0 && "Unknown instruction!!"); |
| } |
| } |
| } |
| } |
| |
| if (BinaryOperator::isNot(CondVal)) { |
| SI.setOperand(0, BinaryOperator::getNotArgument(CondVal)); |
| SI.setOperand(1, FalseVal); |
| SI.setOperand(2, TrueVal); |
| return &SI; |
| } |
| |
| return 0; |
| } |
| |
| /// GetKnownAlignment - If the specified pointer has an alignment that we can |
| /// determine, return it, otherwise return 0. |
| static unsigned GetKnownAlignment(Value *V, TargetData *TD) { |
| if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) { |
| unsigned Align = GV->getAlignment(); |
| if (Align == 0 && TD) |
| Align = TD->getTypeAlignment(GV->getType()->getElementType()); |
| return Align; |
| } else if (AllocationInst *AI = dyn_cast<AllocationInst>(V)) { |
| unsigned Align = AI->getAlignment(); |
| if (Align == 0 && TD) { |
| if (isa<AllocaInst>(AI)) |
| Align = TD->getTypeAlignment(AI->getType()->getElementType()); |
| else if (isa<MallocInst>(AI)) { |
| // Malloc returns maximally aligned memory. |
| Align = TD->getTypeAlignment(AI->getType()->getElementType()); |
| Align = std::max(Align, (unsigned)TD->getTypeAlignment(Type::DoubleTy)); |
| Align = std::max(Align, (unsigned)TD->getTypeAlignment(Type::LongTy)); |
| } |
| } |
| return Align; |
| } else if (isa<BitCastInst>(V) || |
| (isa<ConstantExpr>(V) && |
| cast<ConstantExpr>(V)->getOpcode() == Instruction::BitCast)) { |
| User *CI = cast<User>(V); |
| if (isa<PointerType>(CI->getOperand(0)->getType())) |
| return GetKnownAlignment(CI->getOperand(0), TD); |
| return 0; |
| } else if (isa<GetElementPtrInst>(V) || |
| (isa<ConstantExpr>(V) && |
| cast<ConstantExpr>(V)->getOpcode()==Instruction::GetElementPtr)) { |
| User *GEPI = cast<User>(V); |
| unsigned BaseAlignment = GetKnownAlignment(GEPI->getOperand(0), TD); |
| if (BaseAlignment == 0) return 0; |
| |
| // If all indexes are zero, it is just the alignment of the base pointer. |
| bool AllZeroOperands = true; |
| for (unsigned i = 1, e = GEPI->getNumOperands(); i != e; ++i) |
| if (!isa<Constant>(GEPI->getOperand(i)) || |
| !cast<Constant>(GEPI->getOperand(i))->isNullValue()) { |
| AllZeroOperands = false; |
| break; |
| } |
| if (AllZeroOperands) |
| return BaseAlignment; |
| |
| // Otherwise, if the base alignment is >= the alignment we expect for the |
| // base pointer type, then we know that the resultant pointer is aligned at |
| // least as much as its type requires. |
| if (!TD) return 0; |
| |
| const Type *BasePtrTy = GEPI->getOperand(0)->getType(); |
| if (TD->getTypeAlignment(cast<PointerType>(BasePtrTy)->getElementType()) |
| <= BaseAlignment) { |
| const Type *GEPTy = GEPI->getType(); |
| return TD->getTypeAlignment(cast<PointerType>(GEPTy)->getElementType()); |
| } |
| return 0; |
| } |
| 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>(II)) { |
| if (GlobalVariable *GVSrc = dyn_cast<GlobalVariable>(MMI->getSource())) |
| if (GVSrc->isConstant()) { |
| Module *M = CI.getParent()->getParent()->getParent(); |
| const char *Name; |
| if (CI.getCalledFunction()->getFunctionType()->getParamType(2) == |
| Type::UIntTy) |
| Name = "llvm.memcpy.i32"; |
| else |
| Name = "llvm.memcpy.i64"; |
| Function *MemCpy = M->getOrInsertFunction(Name, |
| CI.getCalledFunction()->getFunctionType()); |
| CI.setOperand(0, MemCpy); |
| Changed = true; |
| } |
| } |
| |
| // If we can determine a pointer alignment that is bigger than currently |
| // set, update the alignment. |
| if (isa<MemCpyInst>(MI) || isa<MemMoveInst>(MI)) { |
| unsigned Alignment1 = GetKnownAlignment(MI->getOperand(1), TD); |
| unsigned Alignment2 = GetKnownAlignment(MI->getOperand(2), TD); |
| unsigned Align = std::min(Alignment1, Alignment2); |
| if (MI->getAlignment()->getZExtValue() < Align) { |
| MI->setAlignment(ConstantInt::get(Type::UIntTy, Align)); |
| Changed = true; |
| } |
| } else if (isa<MemSetInst>(MI)) { |
| unsigned Alignment = GetKnownAlignment(MI->getDest(), TD); |
| if (MI->getAlignment()->getZExtValue() < Alignment) { |
| MI->setAlignment(ConstantInt::get(Type::UIntTy, Alignment)); |
| Changed = true; |
| } |
| } |
| |
| if (Changed) return II; |
| } else { |
| switch (II->getIntrinsicID()) { |
| default: 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 (GetKnownAlignment(II->getOperand(1), TD) >= 16) { |
| Value *Ptr = InsertCastBefore(II->getOperand(1), |
| PointerType::get(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 (GetKnownAlignment(II->getOperand(2), TD) >= 16) { |
| const Type *OpPtrTy = PointerType::get(II->getOperand(1)->getType()); |
| Value *Ptr = InsertCastBefore(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: |
| case Intrinsic::x86_sse2_storel_dq: |
| // Turn X86 storeu -> store if the pointer is known aligned. |
| if (GetKnownAlignment(II->getOperand(1), TD) >= 16) { |
| const Type *OpPtrTy = PointerType::get(II->getOperand(2)->getType()); |
| Value *Ptr = InsertCastBefore(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 (ConstantPacked *Mask = dyn_cast<ConstantPacked>(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 = InsertCastBefore(II->getOperand(1), Mask->getType(), CI); |
| Value *Op1 = InsertCastBefore(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 = new InsertElementInst(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); |
| } |
| } |
| |
| // 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. |
| TerminatorInst *TI = II->getParent()->getTerminator(); |
| if (isa<ReturnInst>(TI) || isa<UnwindInst>(TI)) { |
| BasicBlock::iterator BI = II; |
| bool CannotRemove = false; |
| for (++BI; &*BI != TI; ++BI) { |
| if (isa<AllocaInst>(BI) || |
| (isa<CallInst>(BI) && !isa<IntrinsicInst>(BI))) { |
| CannotRemove = true; |
| break; |
| } |
| } |
| if (!CannotRemove) |
| return EraseInstFromFunction(CI); |
| } |
| break; |
| } |
| } |
| } |
| |
| return visitCallSite(II); |
| } |
| |
| // InvokeInst simplification |
| // |
| Instruction *InstCombiner::visitInvokeInst(InvokeInst &II) { |
| return visitCallSite(&II); |
| } |
| |
| // visitCallSite - Improvements for call and invoke instructions. |
| // |
| Instruction *InstCombiner::visitCallSite(CallSite CS) { |
| bool Changed = false; |
| |
| // If the callee is a constexpr cast of a function, attempt to move the cast |
| // to the arguments of the call/invoke. |
| if (transformConstExprCastCall(CS)) return 0; |
| |
| Value *Callee = CS.getCalledValue(); |
| |
| if (Function *CalleeF = dyn_cast<Function>(Callee)) |
| if (CalleeF->getCallingConv() != CS.getCallingConv()) { |
| Instruction *OldCall = CS.getInstruction(); |
| // If the call and callee calling conventions don't match, this call must |
| // be unreachable, as the call is undefined. |
| new StoreInst(ConstantBool::getTrue(), |
| UndefValue::get(PointerType::get(Type::BoolTy)), OldCall); |
| if (!OldCall->use_empty()) |
| OldCall->replaceAllUsesWith(UndefValue::get(OldCall->getType())); |
| if (isa<CallInst>(OldCall)) // Not worth removing an invoke here. |
| return EraseInstFromFunction(*OldCall); |
| return 0; |
| } |
| |
| if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) { |
| // This instruction is not reachable, just remove it. We insert a store to |
| // undef so that we know that this code is not reachable, despite the fact |
| // that we can't modify the CFG here. |
| new StoreInst(ConstantBool::getTrue(), |
| UndefValue::get(PointerType::get(Type::BoolTy)), |
| CS.getInstruction()); |
| |
| if (!CS.getInstruction()->use_empty()) |
| CS.getInstruction()-> |
| replaceAllUsesWith(UndefValue::get(CS.getInstruction()->getType())); |
| |
| if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) { |
| // Don't break the CFG, insert a dummy cond branch. |
| new BranchInst(II->getNormalDest(), II->getUnwindDest(), |
| ConstantBool::getTrue(), II); |
| } |
| return EraseInstFromFunction(*CS.getInstruction()); |
| } |
| |
| const PointerType *PTy = cast<PointerType>(Callee->getType()); |
| const FunctionType *FTy = cast<FunctionType>(PTy->getElementType()); |
| if (FTy->isVarArg()) { |
| // See if we can optimize any arguments passed through the varargs area of |
| // the call. |
| for (CallSite::arg_iterator I = CS.arg_begin()+FTy->getNumParams(), |
| E = CS.arg_end(); I != E; ++I) |
| if (CastInst *CI = dyn_cast<CastInst>(*I)) { |
| // If this cast does not effect the value passed through the varargs |
| // area, we can eliminate the use of the cast. |
| Value *Op = CI->getOperand(0); |
| if (CI->isLosslessCast()) { |
| *I = Op; |
| Changed = true; |
| } |
| } |
| } |
| |
| return Changed ? CS.getInstruction() : 0; |
| } |
| |
| // transformConstExprCastCall - If the callee is a constexpr cast of a function, |
| // attempt to move the cast to the arguments of the call/invoke. |
| // |
| bool InstCombiner::transformConstExprCastCall(CallSite CS) { |
| if (!isa<ConstantExpr>(CS.getCalledValue())) return false; |
| ConstantExpr *CE = cast<ConstantExpr>(CS.getCalledValue()); |
| if (CE->getOpcode() != Instruction::BitCast || |
| !isa<Function>(CE->getOperand(0))) |
| return false; |
| Function *Callee = cast<Function>(CE->getOperand(0)); |
| Instruction *Caller = CS.getInstruction(); |
| |
| // Okay, this is a cast from a function to a different type. Unless doing so |
| // would cause a type conversion of one of our arguments, change this call to |
| // be a direct call with arguments casted to the appropriate types. |
| // |
| const FunctionType *FT = Callee->getFunctionType(); |
| const Type *OldRetTy = Caller->getType(); |
| |
| // Check to see if we are changing the return type... |
| if (OldRetTy != FT->getReturnType()) { |
| if (Callee->isExternal() && |
| !Caller->use_empty() && |
| !(OldRetTy->canLosslesslyBitCastTo(FT->getReturnType()) || |
| (isa<PointerType>(FT->getReturnType()) && |
| TD->getIntPtrType()->canLosslesslyBitCastTo(OldRetTy))) |
| ) |
| return false; // Cannot transform this return value... |
| |
| // If the callsite is an invoke instruction, and the return value is used by |
| // a PHI node in a successor, we cannot change the return type of the call |
| // because there is no place to put the cast instruction (without breaking |
| // the critical edge). Bail out in this case. |
| if (!Caller->use_empty()) |
| if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) |
| for (Value::use_iterator UI = II->use_begin(), E = II->use_end(); |
| UI != E; ++UI) |
| if (PHINode *PN = dyn_cast<PHINode>(*UI)) |
| if (PN->getParent() == II->getNormalDest() || |
| PN->getParent() == II->getUnwindDest()) |
| return false; |
| } |
| |
| unsigned NumActualArgs = unsigned(CS.arg_end()-CS.arg_begin()); |
| unsigned NumCommonArgs = std::min(FT->getNumParams(), NumActualArgs); |
| |
| CallSite::arg_iterator AI = CS.arg_begin(); |
| for (unsigned i = 0, e = NumCommonArgs; i != e; ++i, ++AI) { |
| const Type *ParamTy = FT->getParamType(i); |
| const Type *ActTy = (*AI)->getType(); |
| ConstantInt *c = dyn_cast<ConstantInt>(*AI); |
| //Either we can cast directly, or we can upconvert the argument |
| bool isConvertible = ActTy->canLosslesslyBitCastTo(ParamTy) || |
| (ParamTy->isIntegral() && ActTy->isIntegral() && |
| ParamTy->isSigned() == ActTy->isSigned() && |
| ParamTy->getPrimitiveSize() >= ActTy->getPrimitiveSize()) || |
| (c && ParamTy->getPrimitiveSize() >= ActTy->getPrimitiveSize() && |
| c->getSExtValue() > 0); |
| if (Callee->isExternal() && !isConvertible) return false; |
| } |
| |
| if (FT->getNumParams() < NumActualArgs && !FT->isVarArg() && |
| Callee->isExternal()) |
| return false; // Do not delete arguments unless we have a function body... |
| |
| // Okay, we decided that this is a safe thing to do: go ahead and start |
| // inserting cast instructions as necessary... |
| std::vector<Value*> Args; |
| Args.reserve(NumActualArgs); |
| |
| AI = CS.arg_begin(); |
| for (unsigned i = 0; i != NumCommonArgs; ++i, ++AI) { |
| const Type *ParamTy = FT->getParamType(i); |
| if ((*AI)->getType() == ParamTy) { |
| Args.push_back(*AI); |
| } else { |
| CastInst *NewCast = CastInst::createInferredCast(*AI, ParamTy, "tmp"); |
| Args.push_back(InsertNewInstBefore(NewCast, *Caller)); |
| } |
| } |
| |
| // If the function takes more arguments than the call was taking, add them |
| // now... |
| for (unsigned i = NumCommonArgs; i != FT->getNumParams(); ++i) |
| Args.push_back(Constant::getNullValue(FT->getParamType(i))); |
| |
| // If we are removing arguments to the function, emit an obnoxious warning... |
| if (FT->getNumParams() < NumActualArgs) |
| if (!FT->isVarArg()) { |
| llvm_cerr << "WARNING: While resolving call to function '" |
| << Callee->getName() << "' arguments were dropped!\n"; |
| } else { |
| // Add all of the arguments in their promoted form to the arg list... |
| for (unsigned i = FT->getNumParams(); i != NumActualArgs; ++i, ++AI) { |
| const Type *PTy = getPromotedType((*AI)->getType()); |
| if (PTy != (*AI)->getType()) { |
| // Must promote to pass through va_arg area! |
| Instruction *Cast = CastInst::createInferredCast(*AI, PTy, "tmp"); |
| InsertNewInstBefore(Cast, *Caller); |
| Args.push_back(Cast); |
| } else { |
| Args.push_back(*AI); |
| } |
| } |
| } |
| |
| if (FT->getReturnType() == Type::VoidTy) |
| Caller->setName(""); // Void type should not have a name... |
| |
| Instruction *NC; |
| if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) { |
| NC = new InvokeInst(Callee, II->getNormalDest(), II->getUnwindDest(), |
| Args, Caller->getName(), Caller); |
| cast<InvokeInst>(II)->setCallingConv(II->getCallingConv()); |
| } else { |
| NC = new CallInst(Callee, Args, Caller->getName(), Caller); |
| if (cast<CallInst>(Caller)->isTailCall()) |
| cast<CallInst>(NC)->setTailCall(); |
| cast<CallInst>(NC)->setCallingConv(cast<CallInst>(Caller)->getCallingConv()); |
| } |
| |
| // Insert a cast of the return type as necessary... |
| Value *NV = NC; |
| if (Caller->getType() != NV->getType() && !Caller->use_empty()) { |
| if (NV->getType() != Type::VoidTy) { |
| NV = NC = CastInst::createInferredCast(NC, Caller->getType(), "tmp"); |
| |
| // If this is an invoke instruction, we should insert it after the first |
| // non-phi, instruction in the normal successor block. |
| if (InvokeInst *II = dyn_cast<InvokeInst>(Caller)) { |
| BasicBlock::iterator I = II->getNormalDest()->begin(); |
| while (isa<PHINode>(I)) ++I; |
| InsertNewInstBefore(NC, *I); |
| } else { |
| // Otherwise, it's a call, just insert cast right after the call instr |
| InsertNewInstBefore(NC, *Caller); |
| } |
| AddUsersToWorkList(*Caller); |
| } else { |
| NV = UndefValue::get(Caller->getType()); |
| } |
| } |
| |
| if (Caller->getType() != Type::VoidTy && !Caller->use_empty()) |
| Caller->replaceAllUsesWith(NV); |
| Caller->getParent()->getInstList().erase(Caller); |
| removeFromWorkList(Caller); |
| return true; |
| } |
| |
| /// 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<ShiftInst>(FirstInst) || |
| isa<GetElementPtrInst>(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 = 0; 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 setcc's of different |
| // types or GEP's with different index types. |
| I->getOperand(0)->getType() != LHSType || |
| I->getOperand(1)->getType() != RHSType) |
| 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, determine if it is profitable. |
| |
| // If this is a GEP, and if the index (not the pointer) needs a PHI, bail out. |
| // Indexes are often folded into load/store instructions, so we don't want to |
| // hide them behind a phi. |
| if (isa<GetElementPtrInst>(FirstInst) && RHSVal == 0) |
| return 0; |
| |
| Value *InLHS = FirstInst->getOperand(0); |
| Value *InRHS = FirstInst->getOperand(1); |
| PHINode *NewLHS = 0, *NewRHS = 0; |
| if (LHSVal == 0) { |
| NewLHS = new PHINode(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 = new PHINode(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. |
| for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) { |
| if (NewLHS) { |
| Value *NewInLHS =cast<Instruction>(PN.getIncomingValue(i))->getOperand(0); |
| NewLHS->addIncoming(NewInLHS, PN.getIncomingBlock(i)); |
| } |
| if (NewRHS) { |
| Value *NewInRHS =cast<Instruction>(PN.getIncomingValue(i))->getOperand(1); |
| NewRHS->addIncoming(NewInRHS, PN.getIncomingBlock(i)); |
| } |
| } |
| |
| if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst)) |
| return BinaryOperator::create(BinOp->getOpcode(), LHSVal, RHSVal); |
| else if (ShiftInst *SI = dyn_cast<ShiftInst>(FirstInst)) |
| return new ShiftInst(SI->getOpcode(), LHSVal, RHSVal); |
| else { |
| assert(isa<GetElementPtrInst>(FirstInst)); |
| return new GetElementPtrInst(LHSVal, RHSVal); |
| } |
| } |
| |
| /// 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. |
| static bool isSafeToSinkLoad(LoadInst *L) { |
| BasicBlock::iterator BBI = L, E = L->getParent()->end(); |
| |
| for (++BBI; BBI != E; ++BBI) |
| if (BBI->mayWriteToMemory()) |
| 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<ShiftInst>(FirstInst)) { |
| // Can fold binop 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; |
| } else if (isa<GetElementPtrInst>(FirstInst)) { |
| if (FirstInst->getNumOperands() == 2) |
| return FoldPHIArgBinOpIntoPHI(PN); |
| // Can't handle general GEPs yet. |
| return 0; |
| } else { |
| return 0; // Cannot fold this operation. |
| } |
| |
| // Check to see if all arguments are the same operation. |
| for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) { |
| if (!isa<Instruction>(PN.getIncomingValue(i))) return 0; |
| Instruction *I = cast<Instruction>(PN.getIncomingValue(i)); |
| if (!I->hasOneUse() || I->getOpcode() != FirstInst->getOpcode()) |
| return 0; |
| if (CastSrcTy) { |
| if (I->getOperand(0)->getType() != CastSrcTy) |
| return 0; // Cast operation must match. |
| } else if (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; |
| } else if (I->getOperand(1) != ConstantOp) { |
| return 0; |
| } |
| } |
| |
| // Okay, they are all the same operation. Create a new PHI node of the |
| // correct type, and PHI together all of the LHS's of the instructions. |
| PHINode *NewPN = new PHINode(FirstInst->getOperand(0)->getType(), |
| PN.getName()+".in"); |
| NewPN->reserveOperandSpace(PN.getNumOperands()/2); |
| |
| Value *InVal = FirstInst->getOperand(0); |
| NewPN->addIncoming(InVal, PN.getIncomingBlock(0)); |
| |
| // Add all operands to the new PHI. |
| for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) { |
| Value *NewInVal = cast<Instruction>(PN.getIncomingValue(i))->getOperand(0); |
| if (NewInVal != InVal) |
| InVal = 0; |
| NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i)); |
| } |
| |
| Value *PhiVal; |
| if (InVal) { |
| // The new PHI unions all of the same values together. This is really |
| // common, so we handle it intelligently here for compile-time speed. |
| PhiVal = InVal; |
| delete NewPN; |
| } else { |
| InsertNewInstBefore(NewPN, PN); |
| PhiVal = NewPN; |
| } |
| |
| // Insert and return the new operation. |
| if (CastInst* FirstCI = dyn_cast<CastInst>(FirstInst)) |
| return CastInst::create(FirstCI->getOpcode(), PhiVal, PN.getType()); |
| else if (isa<LoadInst>(FirstInst)) |
| return new LoadInst(PhiVal, "", isVolatile); |
| else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(FirstInst)) |
| return BinaryOperator::create(BinOp->getOpcode(), PhiVal, ConstantOp); |
| else |
| return new ShiftInst(cast<ShiftInst>(FirstInst)->getOpcode(), |
| PhiVal, ConstantOp); |
| } |
| |
| /// DeadPHICycle - Return true if this PHI node is only used by a PHI node cycle |
| /// that is dead. |
| static bool DeadPHICycle(PHINode *PN, std::set<PHINode*> &PotentiallyDeadPHIs) { |
| if (PN->use_empty()) return true; |
| if (!PN->hasOneUse()) return false; |
| |
| // Remember this node, and if we find the cycle, return. |
| if (!PotentiallyDeadPHIs.insert(PN).second) |
| return true; |
| |
| if (PHINode *PU = dyn_cast<PHINode>(PN->use_back())) |
| return DeadPHICycle(PU, PotentiallyDeadPHIs); |
| |
| return false; |
| } |
| |
| // PHINode simplification |
| // |
| Instruction *InstCombiner::visitPHINode(PHINode &PN) { |
| // If LCSSA is around, don't mess with Phi nodes |
| if (mustPreserveAnalysisID(LCSSAID)) 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)) && |
| PN.getIncomingValue(0)->hasOneUse()) |
| if (Instruction *Result = FoldPHIArgOpIntoPHI(PN)) |
| return Result; |
| |
| // If this is a trivial cycle in the PHI node graph, remove it. Basically, if |
| // this PHI only has a single use (a PHI), and if that PHI only has one use (a |
| // PHI)... break the cycle. |
| if (PN.hasOneUse()) |
| if (PHINode *PU = dyn_cast<PHINode>(PN.use_back())) { |
| std::set<PHINode*> PotentiallyDeadPHIs; |
| PotentiallyDeadPHIs.insert(&PN); |
| if (DeadPHICycle(PU, PotentiallyDeadPHIs)) |
| return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType())); |
| } |
| |
| return 0; |
| } |
| |
| static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy, |
| Instruction *InsertPoint, |
| InstCombiner *IC) { |
| unsigned PS = IC->getTargetData().getPointerSize(); |
| const Type *VTy = V->getType(); |
| if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS) |
| // We must insert a cast to ensure we sign-extend. |
| V = IC->InsertCastBefore(V, VTy->getSignedVersion(), *InsertPoint); |
| return IC->InsertCastBefore(V, DTy, *InsertPoint); |
| } |
| |
| |
| Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) { |
| Value *PtrOp = GEP.getOperand(0); |
| // Is it 'getelementptr %P, long 0' or 'getelementptr %P' |
| // If so, eliminate the noop. |
| if (GEP.getNumOperands() == 1) |
| return ReplaceInstUsesWith(GEP, PtrOp); |
| |
| if (isa<UndefValue>(GEP.getOperand(0))) |
| return ReplaceInstUsesWith(GEP, UndefValue::get(GEP.getType())); |
| |
| bool HasZeroPointerIndex = false; |
| if (Constant *C = dyn_cast<Constant>(GEP.getOperand(1))) |
| HasZeroPointerIndex = C->isNullValue(); |
| |
| if (GEP.getNumOperands() == 2 && HasZeroPointerIndex) |
| return ReplaceInstUsesWith(GEP, PtrOp); |
| |
| // Eliminate unneeded casts for indices. |
| bool MadeChange = false; |
| gep_type_iterator GTI = gep_type_begin(GEP); |
| for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI) |
| if (isa<SequentialType>(*GTI)) { |
| if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) { |
| Value *Src = CI->getOperand(0); |
| const Type *SrcTy = Src->getType(); |
| const Type *DestTy = CI->getType(); |
| if (Src->getType()->isInteger()) { |
| if (SrcTy->getPrimitiveSizeInBits() == |
| DestTy->getPrimitiveSizeInBits()) { |
| // We can always eliminate a cast from ulong or long to the other. |
| // We can always eliminate a cast from uint to int or the other on |
| // 32-bit pointer platforms. |
| if (DestTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()){ |
| MadeChange = true; |
| GEP.setOperand(i, Src); |
| } |
| } else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() && |
| SrcTy->getPrimitiveSize() == 4) { |
| // We can always eliminate a cast from int to [u]long. We can |
| // eliminate a cast from uint to [u]long iff the target is a 32-bit |
| // pointer target. |
| if (SrcTy->isSigned() || |
| SrcTy->getPrimitiveSizeInBits() >= TD->getPointerSizeInBits()) { |
| MadeChange = true; |
| GEP.setOperand(i, Src); |
| } |
| } |
| } |
| } |
| // If we are using a wider index than needed for this platform, shrink it |
| // to what we need. If the incoming value needs a cast instruction, |
| // insert it. This explicit cast can make subsequent optimizations more |
| // obvious. |
| Value *Op = GEP.getOperand(i); |
| if (Op->getType()->getPrimitiveSize() > TD->getPointerSize()) |
| if (Constant *C = dyn_cast<Constant>(Op)) { |
| GEP.setOperand(i, ConstantExpr::getCast(C, |
| TD->getIntPtrType()->getSignedVersion())); |
| MadeChange = true; |
| } else { |
| Op = InsertCastBefore(Op, TD->getIntPtrType(), GEP); |
| GEP.setOperand(i, Op); |
| MadeChange = true; |
| } |
| |
| // If this is a constant idx, make sure to canonicalize it to be a signed |
| // operand, otherwise CSE and other optimizations are pessimized. |
| if (ConstantInt *CUI = dyn_cast<ConstantInt>(Op)) |
| if (CUI->getType()->isUnsigned()) { |
| GEP.setOperand(i, |
| ConstantExpr::getCast(CUI, CUI->getType()->getSignedVersion())); |
| MadeChange = true; |
| } |
| } |
| if (MadeChange) return &GEP; |
| |
| // Combine Indices - If the source pointer to this getelementptr instruction |
| // is a getelementptr instruction, combine the indices of the two |
| // getelementptr instructions into a single instruction. |
| // |
| std::vector<Value*> SrcGEPOperands; |
| if (User *Src = dyn_castGetElementPtr(PtrOp)) |
| SrcGEPOperands.assign(Src->op_begin(), Src->op_end()); |
| |
| if (!SrcGEPOperands.empty()) { |
| // Note that if our source is a gep chain itself that we wait for that |
| // chain to be resolved before we perform this transformation. This |
| // avoids us creating a TON of code in some cases. |
| // |
| if (isa<GetElementPtrInst>(SrcGEPOperands[0]) && |
| cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2) |
| return 0; // Wait until our source is folded to completion. |
| |
| std::vector<Value *> Indices; |
| |
| // Find out whether the last index in the source GEP is a sequential idx. |
| bool EndsWithSequential = false; |
| for (gep_type_iterator I = gep_type_begin(*cast<User>(PtrOp)), |
| E = gep_type_end(*cast<User>(PtrOp)); I != E; ++I) |
| EndsWithSequential = !isa<StructType>(*I); |
| |
| // Can we combine the two pointer arithmetics offsets? |
| if (EndsWithSequential) { |
| // Replace: gep (gep %P, long B), long A, ... |
| // With: T = long A+B; gep %P, T, ... |
| // |
| Value *Sum, *SO1 = SrcGEPOperands.back(), *GO1 = GEP.getOperand(1); |
| if (SO1 == Constant::getNullValue(SO1->getType())) { |
| Sum = GO1; |
| } else if (GO1 == Constant::getNullValue(GO1->getType())) { |
| Sum = SO1; |
| } else { |
| // If they aren't the same type, convert both to an integer of the |
| // target's pointer size. |
| if (SO1->getType() != GO1->getType()) { |
| if (Constant *SO1C = dyn_cast<Constant>(SO1)) { |
| SO1 = ConstantExpr::getCast(SO1C, GO1->getType()); |
| } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) { |
| GO1 = ConstantExpr::getCast(GO1C, SO1->getType()); |
| } else { |
| unsigned PS = TD->getPointerSize(); |
| if (SO1->getType()->getPrimitiveSize() == PS) { |
| // Convert GO1 to SO1's type. |
| GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this); |
| |
| } else if (GO1->getType()->getPrimitiveSize() == PS) { |
| // Convert SO1 to GO1's type. |
| SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this); |
| } else { |
| const Type *PT = TD->getIntPtrType(); |
| SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this); |
| GO1 = InsertSignExtendToPtrTy(GO1, PT, &GEP, this); |
| } |
| } |
| } |
| if (isa<Constant>(SO1) && isa<Constant>(GO1)) |
| Sum = ConstantExpr::getAdd(cast<Constant>(SO1), cast<Constant>(GO1)); |
| else { |
| Sum = BinaryOperator::createAdd(SO1, GO1, PtrOp->getName()+".sum"); |
| InsertNewInstBefore(cast<Instruction>(Sum), GEP); |
| } |
| } |
| |
| // Recycle the GEP we already have if possible. |
| if (SrcGEPOperands.size() == 2) { |
| GEP.setOperand(0, SrcGEPOperands[0]); |
| GEP.setOperand(1, Sum); |
| return &GEP; |
| } else { |
| Indices.insert(Indices.end(), SrcGEPOperands.begin()+1, |
| SrcGEPOperands.end()-1); |
| Indices.push_back(Sum); |
| Indices.insert(Indices.end(), GEP.op_begin()+2, GEP.op_end()); |
| } |
| } else if (isa<Constant>(*GEP.idx_begin()) && |
| cast<Constant>(*GEP.idx_begin())->isNullValue() && |
| SrcGEPOperands.size() != 1) { |
| // Otherwise we can do the fold if the first index of the GEP is a zero |
| Indices.insert(Indices.end(), SrcGEPOperands.begin()+1, |
| SrcGEPOperands.end()); |
| Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end()); |
| } |
| |
| if (!Indices.empty()) |
| return new GetElementPtrInst(SrcGEPOperands[0], Indices, GEP.getName()); |
| |
| } else if (GlobalValue *GV = dyn_cast<GlobalValue>(PtrOp)) { |
| // GEP of global variable. If all of the indices for this GEP are |
| // constants, we can promote this to a constexpr instead of an instruction. |
| |
| // Scan for nonconstants... |
| std::vector<Constant*> Indices; |
| User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end(); |
| for (; I != E && isa<Constant>(*I); ++I) |
| Indices.push_back(cast<Constant>(*I)); |
| |
| if (I == E) { // If they are all constants... |
| Constant *CE = ConstantExpr::getGetElementPtr(GV, Indices); |
| |
| // Replace all uses of the GEP with the new constexpr... |
| return ReplaceInstUsesWith(GEP, CE); |
| } |
| } else if (Value *X = 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 (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ... |
| // into : GEP [10 x ubyte]* X, long 0, ... |
| // |
| // This occurs when the program declares an array extern like "int X[];" |
| // |
| const PointerType *CPTy = cast<PointerType>(PtrOp->getType()); |
| const PointerType *XTy = cast<PointerType>(X->getType()); |
| if (const ArrayType *XATy = |
| dyn_cast<ArrayType>(XTy->getElementType())) |
| if (const ArrayType *CATy = |
| dyn_cast<ArrayType>(CPTy->getElementType())) |
| if (CATy->getElementType() == XATy->getElementType()) { |
| // At this point, we know that the cast source type is a pointer |
| // to an array of the same type as the destination pointer |
| // array. Because the array type is never stepped over (there |
| // is a leading zero) we can fold the cast into this GEP. |
| GEP.setOperand(0, X); |
| return &GEP; |
| } |
| } else if (GEP.getNumOperands() == 2) { |
| // Transform things like: |
| // %t = getelementptr ubyte* cast ([2 x int]* %str to uint*), uint %V |
| // into: %t1 = getelementptr [2 x int*]* %str, int 0, uint %V; cast |
| const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType(); |
| const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType(); |
| if (isa<ArrayType>(SrcElTy) && |
| TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()) == |
| TD->getTypeSize(ResElTy)) { |
| Value *V = InsertNewInstBefore( |
| new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy), |
| GEP.getOperand(1), GEP.getName()), GEP); |
| // V and GEP are both pointer types --> BitCast |
| return new BitCastInst(V, GEP.getType()); |
| } |
| |
| // Transform things like: |
| // getelementptr sbyte* cast ([100 x double]* X to sbyte*), int %tmp |
| // (where tmp = 8*tmp2) into: |
| // getelementptr [100 x double]* %arr, int 0, int %tmp.2 |
| |
| if (isa<ArrayType>(SrcElTy) && |
| (ResElTy == Type::SByteTy || ResElTy == Type::UByteTy)) { |
| uint64_t ArrayEltSize = |
| TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()); |
| |
| // Check to see if "tmp" is a scale by a multiple of ArrayEltSize. We |
| // allow either a mul, shift, or constant here. |
| Value *NewIdx = 0; |
| ConstantInt *Scale = 0; |
| if (ArrayEltSize == 1) { |
| NewIdx = GEP.getOperand(1); |
| Scale = ConstantInt::get(NewIdx->getType(), 1); |
| } else if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP.getOperand(1))) { |
| NewIdx = ConstantInt::get(CI->getType(), 1); |
| Scale = CI; |
| } else if (Instruction *Inst =dyn_cast<Instruction>(GEP.getOperand(1))){ |
| if (Inst->getOpcode() == Instruction::Shl && |
| isa<ConstantInt>(Inst->getOperand(1))) { |
| unsigned ShAmt = |
| cast<ConstantInt>(Inst->getOperand(1))->getZExtValue(); |
| if (Inst->getType()->isSigned()) |
| Scale = ConstantInt::get(Inst->getType(), 1ULL << ShAmt); |
| else |
| Scale = ConstantInt::get(Inst->getType(), 1ULL << ShAmt); |
| NewIdx = Inst->getOperand(0); |
| } else if (Inst->getOpcode() == Instruction::Mul && |
| isa<ConstantInt>(Inst->getOperand(1))) { |
| Scale = cast<ConstantInt>(Inst->getOperand(1)); |
| NewIdx = Inst->getOperand(0); |
| } |
| } |
| |
| // If the index will be to exactly the right offset with the scale taken |
| // out, perform the transformation. |
| if (Scale && Scale->getZExtValue() % ArrayEltSize == 0) { |
| if (isa<ConstantInt>(Scale)) |
| Scale = ConstantInt::get(Scale->getType(), |
| Scale->getZExtValue() / ArrayEltSize); |
| if (Scale->getZExtValue() != 1) { |
| Constant *C = ConstantExpr::getCast(Scale, NewIdx->getType()); |
| Instruction *Sc = BinaryOperator::createMul(NewIdx, C, "idxscale"); |
| NewIdx = InsertNewInstBefore(Sc, GEP); |
| } |
| |
| // Insert the new GEP instruction. |
| Instruction *NewGEP = |
| new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy), |
| NewIdx, GEP.getName()); |
| NewGEP = InsertNewInstBefore(NewGEP, GEP); |
| // The NewGEP must be pointer typed, so must the old one -> BitCast |
| return new BitCastInst(NewGEP, 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::IntTy); |
| Value *V = new GetElementPtrInst(New, NullIdx, NullIdx, |
| New->getName()+".sub", It); |
| |
| // Now make everything use the getelementptr instead of the original |
| // allocation. |
| return ReplaceInstUsesWith(AI, V); |
| } else if (isa<UndefValue>(AI.getArraySize())) { |
| return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType())); |
| } |
| |
| // If alloca'ing a zero byte object, replace the alloca with a null pointer. |
| // Note that we only do this for alloca's, because malloc should allocate and |
| // return a unique pointer, even for a zero byte allocation. |
| if (isa<AllocaInst>(AI) && AI.getAllocatedType()->isSized() && |
| TD->getTypeSize(AI.getAllocatedType()) == 0) |
| return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType())); |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitFreeInst(FreeInst &FI) { |
| Value *Op = FI.getOperand(0); |
| |
| // Change free <ty>* (cast <ty2>* X to <ty>*) into free <ty2>* X |
| if (CastInst *CI = dyn_cast<CastInst>(Op)) |
| if (isa<PointerType>(CI->getOperand(0)->getType())) { |
| FI.setOperand(0, CI->getOperand(0)); |
| return &FI; |
| } |
| |
| // free undef -> unreachable. |
| if (isa<UndefValue>(Op)) { |
| // Insert a new store to null because we cannot modify the CFG here. |
| new StoreInst(ConstantBool::getTrue(), |
| UndefValue::get(PointerType::get(Type::BoolTy)), &FI); |
| return EraseInstFromFunction(FI); |
| } |
| |
| // If we have 'free null' delete the instruction. This can happen in stl code |
| // when lots of inlining happens. |
| if (isa<ConstantPointerNull>(Op)) |
| return EraseInstFromFunction(FI); |
| |
| return 0; |
| } |
| |
| |
| /// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible. |
| static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI) { |
| User *CI = cast<User>(LI.getOperand(0)); |
| Value *CastOp = CI->getOperand(0); |
| |
| const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType(); |
| if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) { |
| const Type *SrcPTy = SrcTy->getElementType(); |
| |
| if (DestPTy->isInteger() || isa<PointerType>(DestPTy) || |
| isa<PackedType>(DestPTy)) { |
| // If the source is an array, the code below will not succeed. Check to |
| // see if a trivial 'gep P, 0, 0' will help matters. Only do this for |
| // constants. |
| if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy)) |
| if (Constant *CSrc = dyn_cast<Constant>(CastOp)) |
| if (ASrcTy->getNumElements() != 0) { |
| std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy)); |
| CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs); |
| SrcTy = cast<PointerType>(CastOp->getType()); |
| SrcPTy = SrcTy->getElementType(); |
| } |
| |
| if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy) || |
| isa<PackedType>(SrcPTy)) && |
| // Do not allow turning this into a load of an integer, which is then |
| // casted to a pointer, this pessimizes pointer analysis a lot. |
| (isa<PointerType>(SrcPTy) == isa<PointerType>(LI.getType())) && |
| IC.getTargetData().getTypeSize(SrcPTy) == |
| IC.getTargetData().getTypeSize(DestPTy)) { |
| |
| // Okay, we are casting from one integer or pointer type to another of |
| // the same size. Instead of casting the pointer before the load, cast |
| // the result of the loaded value. |
| Value *NewLoad = IC.InsertNewInstBefore(new LoadInst(CastOp, |
| CI->getName(), |
| LI.isVolatile()),LI); |
| // Now cast the result of the load. |
| return CastInst::createInferredCast(NewLoad, LI.getType()); |
| } |
| } |
| } |
| return 0; |
| } |
| |
| /// isSafeToLoadUnconditionally - Return true if we know that executing a load |
| /// from this value cannot trap. If it is not obviously safe to load from the |
| /// specified pointer, we do a quick local scan of the basic block containing |
| /// ScanFrom, to determine if the address is already accessed. |
| static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) { |
| // If it is an alloca or global variable, it is always safe to load from. |
| if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true; |
| |
| // Otherwise, be a little bit agressive by scanning the local block where we |
| // want to check to see if the pointer is already being loaded or stored |
| // from/to. If so, the previous load or store would have already trapped, |
| // so there is no harm doing an extra load (also, CSE will later eliminate |
| // the load entirely). |
| BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin(); |
| |
| while (BBI != E) { |
| --BBI; |
| |
| if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) { |
| if (LI->getOperand(0) == V) return true; |
| } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) |
| if (SI->getOperand(1) == V) return true; |
| |
| } |
| return false; |
| } |
| |
| Instruction *InstCombiner::visitLoadInst(LoadInst &LI) { |
| Value *Op = LI.getOperand(0); |
| |
| // load (cast X) --> cast (load X) iff safe |
| if (isa<CastInst>(Op)) |
| if (Instruction *Res = InstCombineLoadCast(*this, LI)) |
| return Res; |
| |
| // None of the following transforms are legal for volatile loads. |
| if (LI.isVolatile()) return 0; |
| |
| if (&LI.getParent()->front() != &LI) { |
| BasicBlock::iterator BBI = &LI; --BBI; |
| // If the instruction immediately before this is a store to the same |
| // address, do a simple form of store->load forwarding. |
| if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) |
| if (SI->getOperand(1) == LI.getOperand(0)) |
| return ReplaceInstUsesWith(LI, SI->getOperand(0)); |
| if (LoadInst *LIB = dyn_cast<LoadInst>(BBI)) |
| if (LIB->getOperand(0) == LI.getOperand(0)) |
| return ReplaceInstUsesWith(LI, LIB); |
| } |
| |
| if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) |
| if (isa<ConstantPointerNull>(GEPI->getOperand(0)) || |
| isa<UndefValue>(GEPI->getOperand(0))) { |
| // Insert a new store to null instruction before the load to indicate |
| // that this code is not reachable. We do this instead of inserting |
| // an unreachable instruction directly because we cannot modify the |
| // CFG. |
| new StoreInst(UndefValue::get(LI.getType()), |
| Constant::getNullValue(Op->getType()), &LI); |
| return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType())); |
| } |
| |
| if (Constant *C = dyn_cast<Constant>(Op)) { |
| // load null/undef -> undef |
| if ((C->isNullValue() || isa<UndefValue>(C))) { |
| // Insert a new store to null instruction before the load to indicate that |
| // this code is not reachable. We do this instead of inserting an |
| // unreachable instruction directly because we cannot modify the CFG. |
| new StoreInst(UndefValue::get(LI.getType()), |
| Constant::getNullValue(Op->getType()), &LI); |
| return ReplaceInstUsesWith(LI, UndefValue::get(LI.getType())); |
| } |
| |
| // Instcombine load (constant global) into the value loaded. |
| if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op)) |
| if (GV->isConstant() && !GV->isExternal()) |
| return ReplaceInstUsesWith(LI, GV->getInitializer()); |
| |
| // Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded. |
| if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op)) |
| if (CE->getOpcode() == Instruction::GetElementPtr) { |
| if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0))) |
| if (GV->isConstant() && !GV->isExternal()) |
| if (Constant *V = |
| 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)) |
| return Res; |
| } |
| } |
| |
| if (Op->hasOneUse()) { |
| // Change select and PHI nodes to select values instead of addresses: this |
| // helps alias analysis out a lot, allows many others simplifications, and |
| // exposes redundancy in the code. |
| // |
| // Note that we cannot do the transformation unless we know that the |
| // introduced loads cannot trap! Something like this is valid as long as |
| // the condition is always false: load (select bool %C, int* null, int* %G), |
| // but it would not be valid if we transformed it to load from null |
| // unconditionally. |
| // |
| if (SelectInst *SI = dyn_cast<SelectInst>(Op)) { |
| // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2). |
| if (isSafeToLoadUnconditionally(SI->getOperand(1), SI) && |
| isSafeToLoadUnconditionally(SI->getOperand(2), SI)) { |
| Value *V1 = InsertNewInstBefore(new LoadInst(SI->getOperand(1), |
| SI->getOperand(1)->getName()+".val"), LI); |
| Value *V2 = InsertNewInstBefore(new LoadInst(SI->getOperand(2), |
| SI->getOperand(2)->getName()+".val"), LI); |
| return new SelectInst(SI->getCondition(), V1, V2); |
| } |
| |
| // load (select (cond, null, P)) -> load P |
| if (Constant *C = dyn_cast<Constant>(SI->getOperand(1))) |
| if (C->isNullValue()) { |
| LI.setOperand(0, SI->getOperand(2)); |
| return &LI; |
| } |
| |
| // load (select (cond, P, null)) -> load P |
| if (Constant *C = dyn_cast<Constant>(SI->getOperand(2))) |
| if (C->isNullValue()) { |
| LI.setOperand(0, SI->getOperand(1)); |
| return &LI; |
| } |
| } |
| } |
| return 0; |
| } |
| |
| /// InstCombineStoreToCast - Fold 'store V, (cast P)' -> store (cast V), P' |
| /// when possible. |
| static Instruction *InstCombineStoreToCast(InstCombiner &IC, StoreInst &SI) { |
| User *CI = cast<User>(SI.getOperand(1)); |
| Value *CastOp = CI->getOperand(0); |
| |
| const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType(); |
| if (const PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType())) { |
| const Type *SrcPTy = SrcTy->getElementType(); |
| |
| if (DestPTy->isInteger() || isa<PointerType>(DestPTy)) { |
| // If the source is an array, the code below will not succeed. Check to |
| // see if a trivial 'gep P, 0, 0' will help matters. Only do this for |
| // constants. |
| if (const ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy)) |
| if (Constant *CSrc = dyn_cast<Constant>(CastOp)) |
| if (ASrcTy->getNumElements() != 0) { |
| std::vector<Value*> Idxs(2, Constant::getNullValue(Type::IntTy)); |
| CastOp = ConstantExpr::getGetElementPtr(CSrc, Idxs); |
| SrcTy = cast<PointerType>(CastOp->getType()); |
| SrcPTy = SrcTy->getElementType(); |
| } |
| |
| if ((SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) && |
| IC.getTargetData().getTypeSize(SrcPTy) == |
| IC.getTargetData().getTypeSize(DestPTy)) { |
| |
| // Okay, we are casting from one integer or pointer type to another of |
| // the same size. Instead of casting the pointer before the store, cast |
| // the value to be stored. |
| Value *NewCast; |
| if (Constant *C = dyn_cast<Constant>(SI.getOperand(0))) |
| NewCast = ConstantExpr::getCast(C, SrcPTy); |
| else |
| NewCast = IC.InsertNewInstBefore( |
| CastInst::createInferredCast(SI.getOperand(0), SrcPTy, |
| SI.getOperand(0)->getName()+".c"), SI); |
| |
| return new StoreInst(NewCast, CastOp); |
| } |
| } |
| } |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitStoreInst(StoreInst &SI) { |
| Value *Val = SI.getOperand(0); |
| Value *Ptr = SI.getOperand(1); |
| |
| if (isa<UndefValue>(Ptr)) { // store X, undef -> noop (even if volatile) |
| EraseInstFromFunction(SI); |
| ++NumCombined; |
| return 0; |
| } |
| |
| // 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() && 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 && LI->getOperand(0) == Ptr) { |
| 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()) |
| 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)) |
| WorkList.push_back(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()) { |
| // Check to see if the successor block has exactly two incoming edges. If |
| // so, see if the other predecessor contains a store to the same location. |
| // if so, insert a PHI node (if needed) and move the stores down. |
| BasicBlock *Dest = BI->getSuccessor(0); |
| |
| pred_iterator PI = pred_begin(Dest); |
| BasicBlock *Other = 0; |
| if (*PI != BI->getParent()) |
| Other = *PI; |
| ++PI; |
| if (PI != pred_end(Dest)) { |
| if (*PI != BI->getParent()) |
| if (Other) |
| Other = 0; |
| else |
| Other = *PI; |
| if (++PI != pred_end(Dest)) |
| Other = 0; |
| } |
| if (Other) { // If only one other pred... |
| BBI = Other->getTerminator(); |
| // Make sure this other block ends in an unconditional branch and that |
| // there is an instruction before the branch. |
| if (isa<BranchInst>(BBI) && cast<BranchInst>(BBI)->isUnconditional() && |
| BBI != Other->begin()) { |
| --BBI; |
| StoreInst *OtherStore = dyn_cast<StoreInst>(BBI); |
| |
| // If this instruction is a store to the same location. |
| if (OtherStore && OtherStore->getOperand(1) == SI.getOperand(1)) { |
| // Okay, we know we can perform this transformation. Insert a PHI |
| // node now if we need it. |
| Value *MergedVal = OtherStore->getOperand(0); |
| if (MergedVal != SI.getOperand(0)) { |
| PHINode *PN = new PHINode(MergedVal->getType(), "storemerge"); |
| PN->reserveOperandSpace(2); |
| PN->addIncoming(SI.getOperand(0), SI.getParent()); |
| PN->addIncoming(OtherStore->getOperand(0), Other); |
| MergedVal = InsertNewInstBefore(PN, Dest->front()); |
| } |
| |
| // Advance to a place where it is safe to insert the new store and |
| // insert it. |
| BBI = Dest->begin(); |
| while (isa<PHINode>(BBI)) ++BBI; |
| InsertNewInstBefore(new StoreInst(MergedVal, SI.getOperand(1), |
| OtherStore->isVolatile()), *BBI); |
| |
| // Nuke the old stores. |
| EraseInstFromFunction(SI); |
| EraseInstFromFunction(*OtherStore); |
| ++NumCombined; |
| return 0; |
| } |
| } |
| } |
| } |
| |
| return 0; |
| } |
| |
| |
| Instruction *InstCombiner::visitBranchInst(BranchInst &BI) { |
| // Change br (not X), label True, label False to: br X, label False, True |
| Value *X = 0; |
| BasicBlock *TrueDest; |
| BasicBlock *FalseDest; |
| if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) && |
| !isa<Constant>(X)) { |
| // Swap Destinations and condition... |
| BI.setCondition(X); |
| BI.setSuccessor(0, FalseDest); |
| BI.setSuccessor(1, TrueDest); |
| return &BI; |
| } |
| |
| // Cannonicalize setne -> seteq |
| Instruction::BinaryOps Op; Value *Y; |
| if (match(&BI, m_Br(m_SetCond(Op, m_Value(X), m_Value(Y)), |
| TrueDest, FalseDest))) |
| if ((Op == Instruction::SetNE || Op == Instruction::SetLE || |
| Op == Instruction::SetGE) && BI.getCondition()->hasOneUse()) { |
| SetCondInst *I = cast<SetCondInst>(BI.getCondition()); |
| std::string Name = I->getName(); I->setName(""); |
| Instruction::BinaryOps NewOpcode = SetCondInst::getInverseCondition(Op); |
| Value *NewSCC = BinaryOperator::create(NewOpcode, X, Y, Name, I); |
| // Swap Destinations and condition... |
| BI.setCondition(NewSCC); |
| BI.setSuccessor(0, FalseDest); |
| BI.setSuccessor(1, TrueDest); |
| removeFromWorkList(I); |
| I->getParent()->getInstList().erase(I); |
| WorkList.push_back(cast<Instruction>(NewSCC)); |
| return &BI; |
| } |
| |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) { |
| Value *Cond = SI.getCondition(); |
| if (Instruction *I = dyn_cast<Instruction>(Cond)) { |
| if (I->getOpcode() == Instruction::Add) |
| if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) { |
| // change 'switch (X+4) case 1:' into 'switch (X) case -3' |
| for (unsigned i = 2, e = SI.getNumOperands(); i != e; i += 2) |
| SI.setOperand(i,ConstantExpr::getSub(cast<Constant>(SI.getOperand(i)), |
| AddRHS)); |
| SI.setOperand(0, I->getOperand(0)); |
| WorkList.push_back(I); |
| return &SI; |
| } |
| } |
| return 0; |
| } |
| |
| /// 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 (ConstantPacked *C = dyn_cast<ConstantPacked>(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; |
| |
| return false; |
| } |
| |
| /// getShuffleMask - Read and decode a shufflevector mask. It turns undef |
| /// elements into values that are larger than the #elts 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 ConstantPacked *CP = cast<ConstantPacked>(SVI->getOperand(2)); |
| for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i) |
| if (isa<UndefValue>(CP->getOperand(i))) |
| Result.push_back(NElts*2); // undef -> 8 |
| else |
| Result.push_back(cast<ConstantInt>(CP->getOperand(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<PackedType>(V->getType()) && "Not looking at a vector?"); |
| const PackedType *PTy = cast<PackedType>(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 (ConstantPacked *CP = dyn_cast<ConstantPacked>(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 InEl = getShuffleMask(SVI)[EltNo]; |
| if (InEl < Width) |
| return FindScalarElement(SVI->getOperand(0), InEl); |
| else if (InEl < Width*2) |
| return FindScalarElement(SVI->getOperand(1), InEl - Width); |
| else |
| return UndefValue::get(PTy->getElementType()); |
| } |
| |
| // Otherwise, we don't know. |
| return 0; |
| } |
| |
| Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) { |
| |
| // If packed val is undef, replace extract with scalar undef. |
| if (isa<UndefValue>(EI.getOperand(0))) |
| return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType())); |
| |
| // If packed val is constant 0, replace extract with scalar 0. |
| if (isa<ConstantAggregateZero>(EI.getOperand(0))) |
| return ReplaceInstUsesWith(EI, Constant::getNullValue(EI.getType())); |
| |
| if (ConstantPacked *C = dyn_cast<ConstantPacked>(EI.getOperand(0))) { |
| // If packed val is constant with uniform operands, replace EI |
| // with that operand |
| 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))) { |
| // 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. |
| uint64_t IndexVal = IdxC->getZExtValue(); |
| if (EI.getOperand(0)->hasOneUse()) { |
| 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 (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)) { |
| Value *Ptr = InsertCastBefore(I->getOperand(0), |
| PointerType::get(EI.getType()), EI); |
| GetElementPtrInst *GEP = |
| new GetElementPtrInst(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; |
| if (SrcIdx < SVI->getType()->getNumElements()) |
| Src = SVI->getOperand(0); |
| else if (SrcIdx < SVI->getType()->getNumElements()*2) { |
| SrcIdx -= SVI->getType()->getNumElements(); |
| 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<PackedType>(V->getType())->getNumElements(); |
| |
| if (isa<UndefValue>(V)) { |
| Mask.assign(NumElts, UndefValue::get(Type::UIntTy)); |
| return true; |
| } else if (V == LHS) { |
| for (unsigned i = 0; i != NumElts; ++i) |
| Mask.push_back(ConstantInt::get(Type::UIntTy, i)); |
| return true; |
| } else if (V == RHS) { |
| for (unsigned i = 0; i != NumElts; ++i) |
| Mask.push_back(ConstantInt::get(Type::UIntTy, 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::UIntTy); |
| 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-1)] = |
| ConstantInt::get(Type::UIntTy, ExtractedIdx); |
| } else { |
| assert(EI->getOperand(0) == RHS); |
| Mask[InsertedIdx & (NumElts-1)] = |
| ConstantInt::get(Type::UIntTy, 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<PackedType>(V->getType()) && |
| (RHS == 0 || V->getType() == RHS->getType()) && |
| "Invalid shuffle!"); |
| unsigned NumElts = cast<PackedType>(V->getType())->getNumElements(); |
| |
| if (isa<UndefValue>(V)) { |
| Mask.assign(NumElts, UndefValue::get(Type::UIntTy)); |
| return V; |
| } else if (isa<ConstantAggregateZero>(V)) { |
| Mask.assign(NumElts, ConstantInt::get(Type::UIntTy, 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-1)] = |
| ConstantInt::get(Type::UIntTy, 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::UIntTy, 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::UIntTy, i)); |
| return V; |
| } |
| |
| Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) { |
| Value *VecOp = IE.getOperand(0); |
| Value *ScalarOp = IE.getOperand(1); |
| Value *IdxOp = IE.getOperand(2); |
| |
| // 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::UIntTy)); |
| else { |
| assert(isa<ConstantAggregateZero>(VecOp) && "Unknown thing"); |
| Mask.assign(NumVectorElts, ConstantInt::get(Type::UIntTy, |
| NumVectorElts)); |
| } |
| Mask[InsertedIdx] = ConstantInt::get(Type::UIntTy, ExtractedIdx); |
| return new ShuffleVectorInst(EI->getOperand(0), VecOp, |
| ConstantPacked::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, ConstantPacked::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())); |
| |
| // TODO: If we have shuffle(x, undef, mask) and any elements of mask refer to |
| // the undef, change them to undefs. |
| |
| // 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::UIntTy)); |
| else { |
| if ((Mask[i] >= e && isa<UndefValue>(RHS)) || |
| (Mask[i] < e && isa<UndefValue>(LHS))) |
| Mask[i] = 2*e; // Turn into undef. |
| else |
| Mask[i] &= (e-1); // Force to LHS. |
| Elts.push_back(ConstantInt::get(Type::UIntTy, Mask[i])); |
| } |
| } |
| SVI.setOperand(0, SVI.getOperand(1)); |
| SVI.setOperand(1, UndefValue::get(RHS->getType())); |
| SVI.setOperand(2, ConstantPacked::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::UIntTy)); |
| } else { |
| Elts.push_back(ConstantInt::get(Type::UIntTy, NewMask[i])); |
| } |
| } |
| return new ShuffleVectorInst(LHSSVI->getOperand(0), |
| LHSSVI->getOperand(1), |
| ConstantPacked::get(Elts)); |
| } |
| } |
| } |
| |
| return MadeChange ? &SVI : 0; |
| } |
| |
| |
| |
| void InstCombiner::removeFromWorkList(Instruction *I) { |
| WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I), |
| WorkList.end()); |
| } |
| |
| |
| /// TryToSinkInstruction - Try to move the specified instruction from its |
| /// current block into the beginning of DestBlock, which can only happen if it's |
| /// safe to move the instruction past all of the instructions between it and the |
| /// end of its block. |
| static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) { |
| assert(I->hasOneUse() && "Invariants didn't hold!"); |
| |
| // Cannot move control-flow-involving, volatile loads, vaarg, etc. |
| if (isa<PHINode>(I) || I->mayWriteToMemory()) return false; |
| |
| // Do not sink alloca instructions out of the entry block. |
| if (isa<AllocaInst>(I) && I->getParent() == &DestBlock->getParent()->front()) |
| return false; |
| |
| // We can only sink load instructions if there is nothing between the load and |
| // the end of block that could change the value. |
| if (LoadInst *LI = dyn_cast<LoadInst>(I)) { |
| for (BasicBlock::iterator Scan = LI, E = LI->getParent()->end(); |
| Scan != E; ++Scan) |
| if (Scan->mayWriteToMemory()) |
| return false; |
| } |
| |
| BasicBlock::iterator InsertPos = DestBlock->begin(); |
| while (isa<PHINode>(InsertPos)) ++InsertPos; |
| |
| I->moveBefore(InsertPos); |
| ++NumSunkInst; |
| return true; |
| } |
| |
| /// OptimizeConstantExpr - Given a constant expression and target data layout |
| /// information, symbolically evaluation the constant expr to something simpler |
| /// if possible. |
| static Constant *OptimizeConstantExpr(ConstantExpr *CE, const TargetData *TD) { |
| if (!TD) return CE; |
| |
| Constant *Ptr = CE->getOperand(0); |
| if (CE->getOpcode() == Instruction::GetElementPtr && Ptr->isNullValue() && |
| cast<PointerType>(Ptr->getType())->getElementType()->isSized()) { |
| // If this is a constant expr gep that is effectively computing an |
| // "offsetof", fold it into 'cast int Size to T*' instead of 'gep 0, 0, 12' |
| bool isFoldableGEP = true; |
| for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i) |
| if (!isa<ConstantInt>(CE->getOperand(i))) |
| isFoldableGEP = false; |
| if (isFoldableGEP) { |
| std::vector<Value*> Ops(CE->op_begin()+1, CE->op_end()); |
| uint64_t Offset = TD->getIndexedOffset(Ptr->getType(), Ops); |
| Constant *C = ConstantInt::get(Type::ULongTy, Offset); |
| C = ConstantExpr::getCast(C, TD->getIntPtrType()); |
| return ConstantExpr::getCast(C, CE->getType()); |
| } |
| } |
| |
| return CE; |
| } |
| |
| |
| /// 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, |
| std::set<BasicBlock*> &Visited, |
| std::vector<Instruction*> &WorkList, |
| const TargetData *TD) { |
| // We have now visited this block! If we've already been here, bail out. |
| if (!Visited.insert(BB).second) return; |
| |
| 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)) { |
| if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) |
| C = OptimizeConstantExpr(CE, TD); |
| DOUT << "IC: ConstFold to: " << *C << " from: " << *Inst; |
| Inst->replaceAllUsesWith(C); |
| ++NumConstProp; |
| Inst->eraseFromParent(); |
| continue; |
| } |
| |
| WorkList.push_back(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<ConstantBool>(BI->getCondition())) { |
| bool CondVal = cast<ConstantBool>(BI->getCondition())->getValue(); |
| AddReachableCodeToWorklist(BI->getSuccessor(!CondVal), Visited, WorkList, |
| TD); |
| return; |
| } |
| } 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) { |
| AddReachableCodeToWorklist(SI->getSuccessor(i), Visited, WorkList,TD); |
| return; |
| } |
| |
| // Otherwise it is the default destination. |
| AddReachableCodeToWorklist(SI->getSuccessor(0), Visited, WorkList, TD); |
| return; |
| } |
| } |
| |
| for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) |
| AddReachableCodeToWorklist(TI->getSuccessor(i), Visited, WorkList, TD); |
| } |
| |
| bool InstCombiner::runOnFunction(Function &F) { |
| bool Changed = false; |
| TD = &getAnalysis<TargetData>(); |
| |
| { |
| // 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. |
| std::set<BasicBlock*> Visited; |
| AddReachableCodeToWorklist(F.begin(), Visited, WorkList, 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 = WorkList.back(); // Get an instruction from the worklist |
| WorkList.pop_back(); |
| |
| // 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)) { |
| if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) |
| C = OptimizeConstantExpr(CE, TD); |
| DOUT << "IC: ConstFold to: " << *C << " from: " << *I; |
| |
| // Add operands to the worklist. |
| AddUsesToWorkList(*I); |
| ReplaceInstUsesWith(*I, C); |
| |
| ++NumConstProp; |
| I->eraseFromParent(); |
| removeFromWorkList(I); |
| continue; |
| } |
| |
| // See if we can trivially sink this instruction to a successor basic block. |
| if (I->hasOneUse()) { |
| BasicBlock *BB = I->getParent(); |
| BasicBlock *UserParent = cast<Instruction>(I->use_back())->getParent(); |
| if (UserParent != BB) { |
| bool UserIsSuccessor = false; |
| // See if the user is one of our successors. |
| for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI) |
| if (*SI == UserParent) { |
| UserIsSuccessor = true; |
| break; |
| } |
| |
| // If the user is one of our immediate successors, and if that successor |
| // only has us as a predecessors (we'd have to split the critical edge |
| // otherwise), we can keep going. |
| if (UserIsSuccessor && !isa<PHINode>(I->use_back()) && |
| next(pred_begin(UserParent)) == pred_end(UserParent)) |
| // Okay, the CFG is simple enough, try to sink this instruction. |
| Changed |= TryToSinkInstruction(I, UserParent); |
| } |
| } |
| |
| // Now that we have an instruction, try combining it to simplify it... |
| if (Instruction *Result = visit(*I)) { |
| ++NumCombined; |
| // Should we replace the old instruction with a new one? |
| if (Result != I) { |
| 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. |
| WorkList.push_back(Result); |
| AddUsersToWorkList(*Result); |
| |
| // Move the name to the new instruction first... |
| std::string OldName = I->getName(); I->setName(""); |
| Result->setName(OldName); |
| |
| // Insert the new instruction into the basic block... |
| BasicBlock *InstParent = I->getParent(); |
| BasicBlock::iterator InsertPos = I; |
| |
| if (!isa<PHINode>(Result)) // If combining a PHI, don't insert |
| while (isa<PHINode>(InsertPos)) // middle of a block of PHIs. |
| ++InsertPos; |
| |
| InstParent->getInstList().insert(InsertPos, Result); |
| |
| // Make sure that we reprocess all operands now that we reduced their |
| // use counts. |
| for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) |
| if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i))) |
| WorkList.push_back(OpI); |
| |
| // Instructions can end up on the worklist more than once. Make sure |
| // we do not process an instruction that has been deleted. |
| removeFromWorkList(I); |
| |
| // Erase the old instruction. |
| InstParent->getInstList().erase(I); |
| } else { |
| DOUT << "IC: MOD = " << *I; |
| |
| // If the instruction was modified, it's possible that it is now dead. |
| // if so, remove it. |
| if (isInstructionTriviallyDead(I)) { |
| // Make sure we process all operands now that we are reducing their |
| // use counts. |
| for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) |
| if (Instruction *OpI = dyn_cast<Instruction>(I->getOperand(i))) |
| WorkList.push_back(OpI); |
| |
| // Instructions may end up in the worklist more than once. Erase all |
| // occurrences of this instruction. |
| removeFromWorkList(I); |
| I->eraseFromParent(); |
| } else { |
| WorkList.push_back(Result); |
| AddUsersToWorkList(*Result); |
| } |
| } |
| Changed = true; |
| } |
| } |
| |
| return Changed; |
| } |
| |
| FunctionPass *llvm::createInstructionCombiningPass() { |
| return new InstCombiner(); |
| } |
| |