diff options
Diffstat (limited to 'contrib/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp')
| -rw-r--r-- | contrib/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp | 630 |
1 files changed, 520 insertions, 110 deletions
diff --git a/contrib/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/contrib/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp index ab98ef9fccf8..92874b95234d 100644 --- a/contrib/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp +++ b/contrib/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp @@ -46,8 +46,10 @@ #include "llvm/Support/Debug.h" #include "llvm/Support/GetElementPtrTypeIterator.h" #include "llvm/Support/PatternMatch.h" +#include "llvm/Support/ValueHandle.h" #include "llvm/ADT/SmallPtrSet.h" #include "llvm/ADT/Statistic.h" +#include "llvm/ADT/StringSwitch.h" #include "llvm-c/Initialization.h" #include <algorithm> #include <climits> @@ -83,7 +85,7 @@ void InstCombiner::getAnalysisUsage(AnalysisUsage &AU) const { /// ShouldChangeType - Return true if it is desirable to convert a computation /// from 'From' to 'To'. We don't want to convert from a legal to an illegal /// type for example, or from a smaller to a larger illegal type. -bool InstCombiner::ShouldChangeType(const Type *From, const Type *To) const { +bool InstCombiner::ShouldChangeType(Type *From, Type *To) const { assert(From->isIntegerTy() && To->isIntegerTy()); // If we don't have TD, we don't know if the source/dest are legal. @@ -107,6 +109,43 @@ bool InstCombiner::ShouldChangeType(const Type *From, const Type *To) const { return true; } +// Return true, if No Signed Wrap should be maintained for I. +// The No Signed Wrap flag can be kept if the operation "B (I.getOpcode) C", +// where both B and C should be ConstantInts, results in a constant that does +// not overflow. This function only handles the Add and Sub opcodes. For +// all other opcodes, the function conservatively returns false. +static bool MaintainNoSignedWrap(BinaryOperator &I, Value *B, Value *C) { + OverflowingBinaryOperator *OBO = dyn_cast<OverflowingBinaryOperator>(&I); + if (!OBO || !OBO->hasNoSignedWrap()) { + return false; + } + + // We reason about Add and Sub Only. + Instruction::BinaryOps Opcode = I.getOpcode(); + if (Opcode != Instruction::Add && + Opcode != Instruction::Sub) { + return false; + } + + ConstantInt *CB = dyn_cast<ConstantInt>(B); + ConstantInt *CC = dyn_cast<ConstantInt>(C); + + if (!CB || !CC) { + return false; + } + + const APInt &BVal = CB->getValue(); + const APInt &CVal = CC->getValue(); + bool Overflow = false; + + if (Opcode == Instruction::Add) { + BVal.sadd_ov(CVal, Overflow); + } else { + BVal.ssub_ov(CVal, Overflow); + } + + return !Overflow; +} /// SimplifyAssociativeOrCommutative - This performs a few simplifications for /// operators which are associative or commutative: @@ -158,7 +197,16 @@ bool InstCombiner::SimplifyAssociativeOrCommutative(BinaryOperator &I) { I.setOperand(1, V); // Conservatively clear the optional flags, since they may not be // preserved by the reassociation. - I.clearSubclassOptionalData(); + if (MaintainNoSignedWrap(I, B, C) && + (!Op0 || (isa<BinaryOperator>(Op0) && Op0->hasNoSignedWrap()))) { + // Note: this is only valid because SimplifyBinOp doesn't look at + // the operands to Op0. + I.clearSubclassOptionalData(); + I.setHasNoSignedWrap(true); + } else { + I.clearSubclassOptionalData(); + } + Changed = true; ++NumReassoc; continue; @@ -240,7 +288,7 @@ bool InstCombiner::SimplifyAssociativeOrCommutative(BinaryOperator &I) { Constant *C2 = cast<Constant>(Op1->getOperand(1)); Constant *Folded = ConstantExpr::get(Opcode, C1, C2); - Instruction *New = BinaryOperator::Create(Opcode, A, B); + BinaryOperator *New = BinaryOperator::Create(Opcode, A, B); InsertNewInstWith(New, I); New->takeName(Op1); I.setOperand(0, New); @@ -248,6 +296,7 @@ bool InstCombiner::SimplifyAssociativeOrCommutative(BinaryOperator &I) { // Conservatively clear the optional flags, since they may not be // preserved by the reassociation. I.clearSubclassOptionalData(); + Changed = true; continue; } @@ -516,8 +565,8 @@ Instruction *InstCombiner::FoldOpIntoSelect(Instruction &Op, SelectInst *SI) { // If it's a bitcast involving vectors, make sure it has the same number of // elements on both sides. if (BitCastInst *BC = dyn_cast<BitCastInst>(&Op)) { - const VectorType *DestTy = dyn_cast<VectorType>(BC->getDestTy()); - const VectorType *SrcTy = dyn_cast<VectorType>(BC->getSrcTy()); + VectorType *DestTy = dyn_cast<VectorType>(BC->getDestTy()); + VectorType *SrcTy = dyn_cast<VectorType>(BC->getSrcTy()); // Verify that either both or neither are vectors. if ((SrcTy == NULL) != (DestTy == NULL)) return 0; @@ -654,7 +703,7 @@ Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) { } } else { CastInst *CI = cast<CastInst>(&I); - const Type *RetTy = CI->getType(); + Type *RetTy = CI->getType(); for (unsigned i = 0; i != NumPHIValues; ++i) { Value *InV; if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) @@ -680,7 +729,7 @@ Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) { /// or not there is a sequence of GEP indices into the type that will land us at /// the specified offset. If so, fill them into NewIndices and return the /// resultant element type, otherwise return null. -const Type *InstCombiner::FindElementAtOffset(const Type *Ty, int64_t Offset, +Type *InstCombiner::FindElementAtOffset(Type *Ty, int64_t Offset, SmallVectorImpl<Value*> &NewIndices) { if (!TD) return 0; if (!Ty->isSized()) return 0; @@ -688,7 +737,7 @@ const Type *InstCombiner::FindElementAtOffset(const Type *Ty, int64_t Offset, // Start with the index over the outer type. Note that the type size // might be zero (even if the offset isn't zero) if the indexed type // is something like [0 x {int, int}] - const Type *IntPtrTy = TD->getIntPtrType(Ty->getContext()); + Type *IntPtrTy = TD->getIntPtrType(Ty->getContext()); int64_t FirstIdx = 0; if (int64_t TySize = TD->getTypeAllocSize(Ty)) { FirstIdx = Offset/TySize; @@ -711,7 +760,7 @@ const Type *InstCombiner::FindElementAtOffset(const Type *Ty, int64_t Offset, if (uint64_t(Offset*8) >= TD->getTypeSizeInBits(Ty)) return 0; - if (const StructType *STy = dyn_cast<StructType>(Ty)) { + if (StructType *STy = dyn_cast<StructType>(Ty)) { const StructLayout *SL = TD->getStructLayout(STy); assert(Offset < (int64_t)SL->getSizeInBytes() && "Offset must stay within the indexed type"); @@ -722,7 +771,7 @@ const Type *InstCombiner::FindElementAtOffset(const Type *Ty, int64_t Offset, Offset -= SL->getElementOffset(Elt); Ty = STy->getElementType(Elt); - } else if (const ArrayType *AT = dyn_cast<ArrayType>(Ty)) { + } else if (ArrayType *AT = dyn_cast<ArrayType>(Ty)) { uint64_t EltSize = TD->getTypeAllocSize(AT->getElementType()); assert(EltSize && "Cannot index into a zero-sized array"); NewIndices.push_back(ConstantInt::get(IntPtrTy,Offset/EltSize)); @@ -737,12 +786,20 @@ const Type *InstCombiner::FindElementAtOffset(const Type *Ty, int64_t Offset, return Ty; } - +static bool shouldMergeGEPs(GEPOperator &GEP, GEPOperator &Src) { + // If this GEP has only 0 indices, it is the same pointer as + // Src. If Src is not a trivial GEP too, don't combine + // the indices. + if (GEP.hasAllZeroIndices() && !Src.hasAllZeroIndices() && + !Src.hasOneUse()) + return false; + return true; +} Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) { SmallVector<Value*, 8> Ops(GEP.op_begin(), GEP.op_end()); - if (Value *V = SimplifyGEPInst(&Ops[0], Ops.size(), TD)) + if (Value *V = SimplifyGEPInst(Ops, TD)) return ReplaceInstUsesWith(GEP, V); Value *PtrOp = GEP.getOperand(0); @@ -751,13 +808,13 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) { // by multiples of a zero size type with zero. if (TD) { bool MadeChange = false; - const Type *IntPtrTy = TD->getIntPtrType(GEP.getContext()); + Type *IntPtrTy = TD->getIntPtrType(GEP.getContext()); gep_type_iterator GTI = gep_type_begin(GEP); for (User::op_iterator I = GEP.op_begin() + 1, E = GEP.op_end(); I != E; ++I, ++GTI) { // Skip indices into struct types. - const SequentialType *SeqTy = dyn_cast<SequentialType>(*GTI); + SequentialType *SeqTy = dyn_cast<SequentialType>(*GTI); if (!SeqTy) continue; // If the element type has zero size then any index over it is equivalent @@ -785,21 +842,15 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) { // getelementptr instructions into a single instruction. // if (GEPOperator *Src = dyn_cast<GEPOperator>(PtrOp)) { - - // If this GEP has only 0 indices, it is the same pointer as - // Src. If Src is not a trivial GEP too, don't combine - // the indices. - if (GEP.hasAllZeroIndices() && !Src->hasAllZeroIndices() && - !Src->hasOneUse()) + if (!shouldMergeGEPs(*cast<GEPOperator>(&GEP), *Src)) return 0; // 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 (GetElementPtrInst *SrcGEP = - dyn_cast<GetElementPtrInst>(Src->getOperand(0))) - if (SrcGEP->getNumOperands() == 2) + if (GEPOperator *SrcGEP = + dyn_cast<GEPOperator>(Src->getOperand(0))) + if (SrcGEP->getNumOperands() == 2 && shouldMergeGEPs(*Src, *SrcGEP)) return 0; // Wait until our source is folded to completion. SmallVector<Value*, 8> Indices; @@ -851,15 +902,14 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) { if (!Indices.empty()) return (GEP.isInBounds() && Src->isInBounds()) ? - GetElementPtrInst::CreateInBounds(Src->getOperand(0), Indices.begin(), - Indices.end(), GEP.getName()) : - GetElementPtrInst::Create(Src->getOperand(0), Indices.begin(), - Indices.end(), GEP.getName()); + GetElementPtrInst::CreateInBounds(Src->getOperand(0), Indices, + GEP.getName()) : + GetElementPtrInst::Create(Src->getOperand(0), Indices, GEP.getName()); } // Handle gep(bitcast x) and gep(gep x, 0, 0, 0). Value *StrippedPtr = PtrOp->stripPointerCasts(); - const PointerType *StrippedPtrTy =cast<PointerType>(StrippedPtr->getType()); + PointerType *StrippedPtrTy =cast<PointerType>(StrippedPtr->getType()); if (StrippedPtr != PtrOp && StrippedPtrTy->getAddressSpace() == GEP.getPointerAddressSpace()) { @@ -875,21 +925,20 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) { // // This occurs when the program declares an array extern like "int X[];" if (HasZeroPointerIndex) { - const PointerType *CPTy = cast<PointerType>(PtrOp->getType()); - if (const ArrayType *CATy = + PointerType *CPTy = cast<PointerType>(PtrOp->getType()); + if (ArrayType *CATy = dyn_cast<ArrayType>(CPTy->getElementType())) { // GEP (bitcast i8* X to [0 x i8]*), i32 0, ... ? if (CATy->getElementType() == StrippedPtrTy->getElementType()) { // -> GEP i8* X, ... SmallVector<Value*, 8> Idx(GEP.idx_begin()+1, GEP.idx_end()); GetElementPtrInst *Res = - GetElementPtrInst::Create(StrippedPtr, Idx.begin(), - Idx.end(), GEP.getName()); + GetElementPtrInst::Create(StrippedPtr, Idx, GEP.getName()); Res->setIsInBounds(GEP.isInBounds()); return Res; } - if (const ArrayType *XATy = + if (ArrayType *XATy = dyn_cast<ArrayType>(StrippedPtrTy->getElementType())){ // GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ... ? if (CATy->getElementType() == XATy->getElementType()) { @@ -907,8 +956,8 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) { // Transform things like: // %t = getelementptr i32* bitcast ([2 x i32]* %str to i32*), i32 %V // into: %t1 = getelementptr [2 x i32]* %str, i32 0, i32 %V; bitcast - const Type *SrcElTy = StrippedPtrTy->getElementType(); - const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType(); + Type *SrcElTy = StrippedPtrTy->getElementType(); + Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType(); if (TD && SrcElTy->isArrayTy() && TD->getTypeAllocSize(cast<ArrayType>(SrcElTy)->getElementType()) == TD->getTypeAllocSize(ResElTy)) { @@ -916,8 +965,8 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) { Idx[0] = Constant::getNullValue(Type::getInt32Ty(GEP.getContext())); Idx[1] = GEP.getOperand(1); Value *NewGEP = GEP.isInBounds() ? - Builder->CreateInBoundsGEP(StrippedPtr, Idx, Idx + 2, GEP.getName()) : - Builder->CreateGEP(StrippedPtr, Idx, Idx + 2, GEP.getName()); + Builder->CreateInBoundsGEP(StrippedPtr, Idx, GEP.getName()) : + Builder->CreateGEP(StrippedPtr, Idx, GEP.getName()); // V and GEP are both pointer types --> BitCast return new BitCastInst(NewGEP, GEP.getType()); } @@ -975,8 +1024,8 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) { Idx[0] = Constant::getNullValue(Type::getInt32Ty(GEP.getContext())); Idx[1] = NewIdx; Value *NewGEP = GEP.isInBounds() ? - Builder->CreateInBoundsGEP(StrippedPtr, Idx, Idx + 2,GEP.getName()): - Builder->CreateGEP(StrippedPtr, Idx, Idx + 2, GEP.getName()); + Builder->CreateInBoundsGEP(StrippedPtr, Idx, GEP.getName()): + Builder->CreateGEP(StrippedPtr, Idx, GEP.getName()); // The NewGEP must be pointer typed, so must the old one -> BitCast return new BitCastInst(NewGEP, GEP.getType()); } @@ -1023,14 +1072,12 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) { // field at Offset in 'A's type. If so, we can pull the cast through the // GEP. SmallVector<Value*, 8> NewIndices; - const Type *InTy = + Type *InTy = cast<PointerType>(BCI->getOperand(0)->getType())->getElementType(); if (FindElementAtOffset(InTy, Offset, NewIndices)) { Value *NGEP = GEP.isInBounds() ? - Builder->CreateInBoundsGEP(BCI->getOperand(0), NewIndices.begin(), - NewIndices.end()) : - Builder->CreateGEP(BCI->getOperand(0), NewIndices.begin(), - NewIndices.end()); + Builder->CreateInBoundsGEP(BCI->getOperand(0), NewIndices) : + Builder->CreateGEP(BCI->getOperand(0), NewIndices); if (NGEP->getType() == GEP.getType()) return ReplaceInstUsesWith(GEP, NGEP); @@ -1045,15 +1092,43 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) { -static bool IsOnlyNullComparedAndFreed(const Value &V) { - for (Value::const_use_iterator UI = V.use_begin(), UE = V.use_end(); +static bool IsOnlyNullComparedAndFreed(Value *V, SmallVectorImpl<WeakVH> &Users, + int Depth = 0) { + if (Depth == 8) + return false; + + for (Value::use_iterator UI = V->use_begin(), UE = V->use_end(); UI != UE; ++UI) { - const User *U = *UI; - if (isFreeCall(U)) + User *U = *UI; + if (isFreeCall(U)) { + Users.push_back(U); continue; - if (const ICmpInst *ICI = dyn_cast<ICmpInst>(U)) - if (ICI->isEquality() && isa<ConstantPointerNull>(ICI->getOperand(1))) + } + if (ICmpInst *ICI = dyn_cast<ICmpInst>(U)) { + if (ICI->isEquality() && isa<ConstantPointerNull>(ICI->getOperand(1))) { + Users.push_back(ICI); + continue; + } + } + if (BitCastInst *BCI = dyn_cast<BitCastInst>(U)) { + if (IsOnlyNullComparedAndFreed(BCI, Users, Depth+1)) { + Users.push_back(BCI); + continue; + } + } + if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(U)) { + if (IsOnlyNullComparedAndFreed(GEPI, Users, Depth+1)) { + Users.push_back(GEPI); + continue; + } + } + if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(U)) { + if (II->getIntrinsicID() == Intrinsic::lifetime_start || + II->getIntrinsicID() == Intrinsic::lifetime_end) { + Users.push_back(II); continue; + } + } return false; } return true; @@ -1063,25 +1138,20 @@ Instruction *InstCombiner::visitMalloc(Instruction &MI) { // If we have a malloc call which is only used in any amount of comparisons // to null and free calls, delete the calls and replace the comparisons with // true or false as appropriate. - if (IsOnlyNullComparedAndFreed(MI)) { - for (Value::use_iterator UI = MI.use_begin(), UE = MI.use_end(); - UI != UE;) { - // We can assume that every remaining use is a free call or an icmp eq/ne - // to null, so the cast is safe. - Instruction *I = cast<Instruction>(*UI); - - // Early increment here, as we're about to get rid of the user. - ++UI; - - if (isFreeCall(I)) { - EraseInstFromFunction(*cast<CallInst>(I)); - continue; + SmallVector<WeakVH, 64> Users; + if (IsOnlyNullComparedAndFreed(&MI, Users)) { + for (unsigned i = 0, e = Users.size(); i != e; ++i) { + Instruction *I = cast_or_null<Instruction>(&*Users[i]); + if (!I) continue; + + if (ICmpInst *C = dyn_cast<ICmpInst>(I)) { + ReplaceInstUsesWith(*C, + ConstantInt::get(Type::getInt1Ty(C->getContext()), + C->isFalseWhenEqual())); + } else if (isa<BitCastInst>(I) || isa<GetElementPtrInst>(I)) { + ReplaceInstUsesWith(*I, UndefValue::get(I->getType())); } - // Again, the cast is safe. - ICmpInst *C = cast<ICmpInst>(I); - ReplaceInstUsesWith(*C, ConstantInt::get(Type::getInt1Ty(C->getContext()), - C->isFalseWhenEqual())); - EraseInstFromFunction(*C); + EraseInstFromFunction(*I); } return EraseInstFromFunction(MI); } @@ -1120,8 +1190,7 @@ Instruction *InstCombiner::visitBranchInst(BranchInst &BI) { !isa<Constant>(X)) { // Swap Destinations and condition... BI.setCondition(X); - BI.setSuccessor(0, FalseDest); - BI.setSuccessor(1, TrueDest); + BI.swapSuccessors(); return &BI; } @@ -1136,8 +1205,7 @@ Instruction *InstCombiner::visitBranchInst(BranchInst &BI) { Cond->setPredicate(FCmpInst::getInversePredicate(FPred)); // Swap Destinations and condition. - BI.setSuccessor(0, FalseDest); - BI.setSuccessor(1, TrueDest); + BI.swapSuccessors(); Worklist.Add(Cond); return &BI; } @@ -1153,8 +1221,7 @@ Instruction *InstCombiner::visitBranchInst(BranchInst &BI) { ICmpInst *Cond = cast<ICmpInst>(BI.getCondition()); Cond->setPredicate(ICmpInst::getInversePredicate(IPred)); // Swap Destinations and condition. - BI.setSuccessor(0, FalseDest); - BI.setSuccessor(1, TrueDest); + BI.swapSuccessors(); Worklist.Add(Cond); return &BI; } @@ -1168,11 +1235,17 @@ Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) { 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)); + unsigned NumCases = SI.getNumCases(); + // Skip the first item since that's the default case. + for (unsigned i = 1; i < NumCases; ++i) { + ConstantInt* CaseVal = SI.getCaseValue(i); + Constant* NewCaseVal = ConstantExpr::getSub(cast<Constant>(CaseVal), + AddRHS); + assert(isa<ConstantInt>(NewCaseVal) && + "Result of expression should be constant"); + SI.setSuccessorValue(i, cast<ConstantInt>(NewCaseVal)); + } + SI.setCondition(I->getOperand(0)); Worklist.Add(I); return &SI; } @@ -1242,7 +1315,7 @@ Instruction *InstCombiner::visitExtractValueInst(ExtractValueInst &EV) { Value *NewEV = Builder->CreateExtractValue(IV->getAggregateOperand(), EV.getIndices()); return InsertValueInst::Create(NewEV, IV->getInsertedValueOperand(), - ArrayRef<unsigned>(insi, inse)); + makeArrayRef(insi, inse)); } if (insi == inse) // The insert list is a prefix of the extract list @@ -1254,7 +1327,7 @@ Instruction *InstCombiner::visitExtractValueInst(ExtractValueInst &EV) { // with // %E extractvalue { i32 } { i32 42 }, 0 return ExtractValueInst::Create(IV->getInsertedValueOperand(), - ArrayRef<unsigned>(exti, exte)); + makeArrayRef(exti, exte)); } if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Agg)) { // We're extracting from an intrinsic, see if we're the only user, which @@ -1310,7 +1383,7 @@ Instruction *InstCombiner::visitExtractValueInst(ExtractValueInst &EV) { // load from a GEP. This reduces the size of the load. // FIXME: If a load is used only by extractvalue instructions then this // could be done regardless of having multiple uses. - if (!L->isVolatile() && L->hasOneUse()) { + if (L->isSimple() && L->hasOneUse()) { // extractvalue has integer indices, getelementptr has Value*s. Convert. SmallVector<Value*, 4> Indices; // Prefix an i32 0 since we need the first element. @@ -1322,8 +1395,7 @@ Instruction *InstCombiner::visitExtractValueInst(ExtractValueInst &EV) { // We need to insert these at the location of the old load, not at that of // the extractvalue. Builder->SetInsertPoint(L->getParent(), L); - Value *GEP = Builder->CreateInBoundsGEP(L->getPointerOperand(), - Indices.begin(), Indices.end()); + Value *GEP = Builder->CreateInBoundsGEP(L->getPointerOperand(), Indices); // Returning the load directly will cause the main loop to insert it in // the wrong spot, so use ReplaceInstUsesWith(). return ReplaceInstUsesWith(EV, Builder->CreateLoad(GEP)); @@ -1339,6 +1411,342 @@ Instruction *InstCombiner::visitExtractValueInst(ExtractValueInst &EV) { return 0; } +enum Personality_Type { + Unknown_Personality, + GNU_Ada_Personality, + GNU_CXX_Personality +}; + +/// RecognizePersonality - See if the given exception handling personality +/// function is one that we understand. If so, return a description of it; +/// otherwise return Unknown_Personality. +static Personality_Type RecognizePersonality(Value *Pers) { + Function *F = dyn_cast<Function>(Pers->stripPointerCasts()); + if (!F) + return Unknown_Personality; + return StringSwitch<Personality_Type>(F->getName()) + .Case("__gnat_eh_personality", GNU_Ada_Personality) + .Case("__gxx_personality_v0", GNU_CXX_Personality) + .Default(Unknown_Personality); +} + +/// isCatchAll - Return 'true' if the given typeinfo will match anything. +static bool isCatchAll(Personality_Type Personality, Constant *TypeInfo) { + switch (Personality) { + case Unknown_Personality: + return false; + case GNU_Ada_Personality: + // While __gnat_all_others_value will match any Ada exception, it doesn't + // match foreign exceptions (or didn't, before gcc-4.7). + return false; + case GNU_CXX_Personality: + return TypeInfo->isNullValue(); + } + llvm_unreachable("Unknown personality!"); +} + +static bool shorter_filter(const Value *LHS, const Value *RHS) { + return + cast<ArrayType>(LHS->getType())->getNumElements() + < + cast<ArrayType>(RHS->getType())->getNumElements(); +} + +Instruction *InstCombiner::visitLandingPadInst(LandingPadInst &LI) { + // The logic here should be correct for any real-world personality function. + // However if that turns out not to be true, the offending logic can always + // be conditioned on the personality function, like the catch-all logic is. + Personality_Type Personality = RecognizePersonality(LI.getPersonalityFn()); + + // Simplify the list of clauses, eg by removing repeated catch clauses + // (these are often created by inlining). + bool MakeNewInstruction = false; // If true, recreate using the following: + SmallVector<Value *, 16> NewClauses; // - Clauses for the new instruction; + bool CleanupFlag = LI.isCleanup(); // - The new instruction is a cleanup. + + SmallPtrSet<Value *, 16> AlreadyCaught; // Typeinfos known caught already. + for (unsigned i = 0, e = LI.getNumClauses(); i != e; ++i) { + bool isLastClause = i + 1 == e; + if (LI.isCatch(i)) { + // A catch clause. + Value *CatchClause = LI.getClause(i); + Constant *TypeInfo = cast<Constant>(CatchClause->stripPointerCasts()); + + // If we already saw this clause, there is no point in having a second + // copy of it. + if (AlreadyCaught.insert(TypeInfo)) { + // This catch clause was not already seen. + NewClauses.push_back(CatchClause); + } else { + // Repeated catch clause - drop the redundant copy. + MakeNewInstruction = true; + } + + // If this is a catch-all then there is no point in keeping any following + // clauses or marking the landingpad as having a cleanup. + if (isCatchAll(Personality, TypeInfo)) { + if (!isLastClause) + MakeNewInstruction = true; + CleanupFlag = false; + break; + } + } else { + // A filter clause. If any of the filter elements were already caught + // then they can be dropped from the filter. It is tempting to try to + // exploit the filter further by saying that any typeinfo that does not + // occur in the filter can't be caught later (and thus can be dropped). + // However this would be wrong, since typeinfos can match without being + // equal (for example if one represents a C++ class, and the other some + // class derived from it). + assert(LI.isFilter(i) && "Unsupported landingpad clause!"); + Value *FilterClause = LI.getClause(i); + ArrayType *FilterType = cast<ArrayType>(FilterClause->getType()); + unsigned NumTypeInfos = FilterType->getNumElements(); + + // An empty filter catches everything, so there is no point in keeping any + // following clauses or marking the landingpad as having a cleanup. By + // dealing with this case here the following code is made a bit simpler. + if (!NumTypeInfos) { + NewClauses.push_back(FilterClause); + if (!isLastClause) + MakeNewInstruction = true; + CleanupFlag = false; + break; + } + + bool MakeNewFilter = false; // If true, make a new filter. + SmallVector<Constant *, 16> NewFilterElts; // New elements. + if (isa<ConstantAggregateZero>(FilterClause)) { + // Not an empty filter - it contains at least one null typeinfo. + assert(NumTypeInfos > 0 && "Should have handled empty filter already!"); + Constant *TypeInfo = + Constant::getNullValue(FilterType->getElementType()); + // If this typeinfo is a catch-all then the filter can never match. + if (isCatchAll(Personality, TypeInfo)) { + // Throw the filter away. + MakeNewInstruction = true; + continue; + } + + // There is no point in having multiple copies of this typeinfo, so + // discard all but the first copy if there is more than one. + NewFilterElts.push_back(TypeInfo); + if (NumTypeInfos > 1) + MakeNewFilter = true; + } else { + ConstantArray *Filter = cast<ConstantArray>(FilterClause); + SmallPtrSet<Value *, 16> SeenInFilter; // For uniquing the elements. + NewFilterElts.reserve(NumTypeInfos); + + // Remove any filter elements that were already caught or that already + // occurred in the filter. While there, see if any of the elements are + // catch-alls. If so, the filter can be discarded. + bool SawCatchAll = false; + for (unsigned j = 0; j != NumTypeInfos; ++j) { + Value *Elt = Filter->getOperand(j); + Constant *TypeInfo = cast<Constant>(Elt->stripPointerCasts()); + if (isCatchAll(Personality, TypeInfo)) { + // This element is a catch-all. Bail out, noting this fact. + SawCatchAll = true; + break; + } + if (AlreadyCaught.count(TypeInfo)) + // Already caught by an earlier clause, so having it in the filter + // is pointless. + continue; + // There is no point in having multiple copies of the same typeinfo in + // a filter, so only add it if we didn't already. + if (SeenInFilter.insert(TypeInfo)) + NewFilterElts.push_back(cast<Constant>(Elt)); + } + // A filter containing a catch-all cannot match anything by definition. + if (SawCatchAll) { + // Throw the filter away. + MakeNewInstruction = true; + continue; + } + + // If we dropped something from the filter, make a new one. + if (NewFilterElts.size() < NumTypeInfos) + MakeNewFilter = true; + } + if (MakeNewFilter) { + FilterType = ArrayType::get(FilterType->getElementType(), + NewFilterElts.size()); + FilterClause = ConstantArray::get(FilterType, NewFilterElts); + MakeNewInstruction = true; + } + + NewClauses.push_back(FilterClause); + + // If the new filter is empty then it will catch everything so there is + // no point in keeping any following clauses or marking the landingpad + // as having a cleanup. The case of the original filter being empty was + // already handled above. + if (MakeNewFilter && !NewFilterElts.size()) { + assert(MakeNewInstruction && "New filter but not a new instruction!"); + CleanupFlag = false; + break; + } + } + } + + // If several filters occur in a row then reorder them so that the shortest + // filters come first (those with the smallest number of elements). This is + // advantageous because shorter filters are more likely to match, speeding up + // unwinding, but mostly because it increases the effectiveness of the other + // filter optimizations below. + for (unsigned i = 0, e = NewClauses.size(); i + 1 < e; ) { + unsigned j; + // Find the maximal 'j' s.t. the range [i, j) consists entirely of filters. + for (j = i; j != e; ++j) + if (!isa<ArrayType>(NewClauses[j]->getType())) + break; + + // Check whether the filters are already sorted by length. We need to know + // if sorting them is actually going to do anything so that we only make a + // new landingpad instruction if it does. + for (unsigned k = i; k + 1 < j; ++k) + if (shorter_filter(NewClauses[k+1], NewClauses[k])) { + // Not sorted, so sort the filters now. Doing an unstable sort would be + // correct too but reordering filters pointlessly might confuse users. + std::stable_sort(NewClauses.begin() + i, NewClauses.begin() + j, + shorter_filter); + MakeNewInstruction = true; + break; + } + + // Look for the next batch of filters. + i = j + 1; + } + + // If typeinfos matched if and only if equal, then the elements of a filter L + // that occurs later than a filter F could be replaced by the intersection of + // the elements of F and L. In reality two typeinfos can match without being + // equal (for example if one represents a C++ class, and the other some class + // derived from it) so it would be wrong to perform this transform in general. + // However the transform is correct and useful if F is a subset of L. In that + // case L can be replaced by F, and thus removed altogether since repeating a + // filter is pointless. So here we look at all pairs of filters F and L where + // L follows F in the list of clauses, and remove L if every element of F is + // an element of L. This can occur when inlining C++ functions with exception + // specifications. + for (unsigned i = 0; i + 1 < NewClauses.size(); ++i) { + // Examine each filter in turn. + Value *Filter = NewClauses[i]; + ArrayType *FTy = dyn_cast<ArrayType>(Filter->getType()); + if (!FTy) + // Not a filter - skip it. + continue; + unsigned FElts = FTy->getNumElements(); + // Examine each filter following this one. Doing this backwards means that + // we don't have to worry about filters disappearing under us when removed. + for (unsigned j = NewClauses.size() - 1; j != i; --j) { + Value *LFilter = NewClauses[j]; + ArrayType *LTy = dyn_cast<ArrayType>(LFilter->getType()); + if (!LTy) + // Not a filter - skip it. + continue; + // If Filter is a subset of LFilter, i.e. every element of Filter is also + // an element of LFilter, then discard LFilter. + SmallVector<Value *, 16>::iterator J = NewClauses.begin() + j; + // If Filter is empty then it is a subset of LFilter. + if (!FElts) { + // Discard LFilter. + NewClauses.erase(J); + MakeNewInstruction = true; + // Move on to the next filter. + continue; + } + unsigned LElts = LTy->getNumElements(); + // If Filter is longer than LFilter then it cannot be a subset of it. + if (FElts > LElts) + // Move on to the next filter. + continue; + // At this point we know that LFilter has at least one element. + if (isa<ConstantAggregateZero>(LFilter)) { // LFilter only contains zeros. + // Filter is a subset of LFilter iff Filter contains only zeros (as we + // already know that Filter is not longer than LFilter). + if (isa<ConstantAggregateZero>(Filter)) { + assert(FElts <= LElts && "Should have handled this case earlier!"); + // Discard LFilter. + NewClauses.erase(J); + MakeNewInstruction = true; + } + // Move on to the next filter. + continue; + } + ConstantArray *LArray = cast<ConstantArray>(LFilter); + if (isa<ConstantAggregateZero>(Filter)) { // Filter only contains zeros. + // Since Filter is non-empty and contains only zeros, it is a subset of + // LFilter iff LFilter contains a zero. + assert(FElts > 0 && "Should have eliminated the empty filter earlier!"); + for (unsigned l = 0; l != LElts; ++l) + if (LArray->getOperand(l)->isNullValue()) { + // LFilter contains a zero - discard it. + NewClauses.erase(J); + MakeNewInstruction = true; + break; + } + // Move on to the next filter. + continue; + } + // At this point we know that both filters are ConstantArrays. Loop over + // operands to see whether every element of Filter is also an element of + // LFilter. Since filters tend to be short this is probably faster than + // using a method that scales nicely. + ConstantArray *FArray = cast<ConstantArray>(Filter); + bool AllFound = true; + for (unsigned f = 0; f != FElts; ++f) { + Value *FTypeInfo = FArray->getOperand(f)->stripPointerCasts(); + AllFound = false; + for (unsigned l = 0; l != LElts; ++l) { + Value *LTypeInfo = LArray->getOperand(l)->stripPointerCasts(); + if (LTypeInfo == FTypeInfo) { + AllFound = true; + break; + } + } + if (!AllFound) + break; + } + if (AllFound) { + // Discard LFilter. + NewClauses.erase(J); + MakeNewInstruction = true; + } + // Move on to the next filter. + } + } + + // If we changed any of the clauses, replace the old landingpad instruction + // with a new one. + if (MakeNewInstruction) { + LandingPadInst *NLI = LandingPadInst::Create(LI.getType(), + LI.getPersonalityFn(), + NewClauses.size()); + for (unsigned i = 0, e = NewClauses.size(); i != e; ++i) + NLI->addClause(NewClauses[i]); + // A landing pad with no clauses must have the cleanup flag set. It is + // theoretically possible, though highly unlikely, that we eliminated all + // clauses. If so, force the cleanup flag to true. + if (NewClauses.empty()) + CleanupFlag = true; + NLI->setCleanup(CleanupFlag); + return NLI; + } + + // Even if none of the clauses changed, we may nonetheless have understood + // that the cleanup flag is pointless. Clear it if so. + if (LI.isCleanup() != CleanupFlag) { + assert(!CleanupFlag && "Adding a cleanup, not removing one?!"); + LI.setCleanup(CleanupFlag); + return &LI; + } + + return 0; +} + @@ -1350,7 +1758,8 @@ 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->mayHaveSideEffects() || isa<TerminatorInst>(I)) + if (isa<PHINode>(I) || isa<LandingPadInst>(I) || I->mayHaveSideEffects() || + isa<TerminatorInst>(I)) return false; // Do not sink alloca instructions out of the entry block. @@ -1367,8 +1776,7 @@ static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) { return false; } - BasicBlock::iterator InsertPos = DestBlock->getFirstNonPHI(); - + BasicBlock::iterator InsertPos = DestBlock->getFirstInsertionPt(); I->moveBefore(InsertPos); ++NumSunkInst; return true; @@ -1503,27 +1911,29 @@ bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) { // Do a quick scan over the function. If we find any blocks that are // unreachable, remove any instructions inside of them. This prevents // the instcombine code from having to deal with some bad special cases. - for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) - if (!Visited.count(BB)) { - Instruction *Term = BB->getTerminator(); - while (Term != BB->begin()) { // Remove instrs bottom-up - BasicBlock::iterator I = Term; --I; - - DEBUG(errs() << "IC: DCE: " << *I << '\n'); - // A debug intrinsic shouldn't force another iteration if we weren't - // going to do one without it. - if (!isa<DbgInfoIntrinsic>(I)) { - ++NumDeadInst; - MadeIRChange = true; - } - - // If I is not void type then replaceAllUsesWith undef. - // This allows ValueHandlers and custom metadata to adjust itself. - if (!I->getType()->isVoidTy()) - I->replaceAllUsesWith(UndefValue::get(I->getType())); - I->eraseFromParent(); + for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) { + if (Visited.count(BB)) continue; + + // Delete the instructions backwards, as it has a reduced likelihood of + // having to update as many def-use and use-def chains. + Instruction *EndInst = BB->getTerminator(); // Last not to be deleted. + while (EndInst != BB->begin()) { + // Delete the next to last instruction. + BasicBlock::iterator I = EndInst; + Instruction *Inst = --I; + if (!Inst->use_empty()) + Inst->replaceAllUsesWith(UndefValue::get(Inst->getType())); + if (isa<LandingPadInst>(Inst)) { + EndInst = Inst; + continue; } + if (!isa<DbgInfoIntrinsic>(Inst)) { + ++NumDeadInst; + MadeIRChange = true; + } + Inst->eraseFromParent(); } + } } while (!Worklist.isEmpty()) { @@ -1604,13 +2014,13 @@ bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) { // Everything uses the new instruction now. I->replaceAllUsesWith(Result); + // Move the name to the new instruction first. + Result->takeName(I); + // Push the new instruction and any users onto the worklist. Worklist.Add(Result); Worklist.AddUsersToWorkList(*Result); - // Move the name to the new instruction first. - Result->takeName(I); - // Insert the new instruction into the basic block... BasicBlock *InstParent = I->getParent(); BasicBlock::iterator InsertPos = I; |