diff options
Diffstat (limited to 'lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp')
| -rw-r--r-- | lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp | 561 |
1 files changed, 444 insertions, 117 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp index 6230c000cf57f..5aa59c69f39bb 100644 --- a/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp +++ b/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp @@ -11,12 +11,13 @@ // //===----------------------------------------------------------------------===// -#include "InstCombine.h" +#include "InstCombineInternal.h" #include "llvm/ADT/Statistic.h" #include "llvm/Analysis/Loads.h" #include "llvm/IR/DataLayout.h" #include "llvm/IR/LLVMContext.h" #include "llvm/IR/IntrinsicInst.h" +#include "llvm/IR/MDBuilder.h" #include "llvm/Transforms/Utils/BasicBlockUtils.h" #include "llvm/Transforms/Utils/Local.h" using namespace llvm; @@ -83,7 +84,7 @@ isOnlyCopiedFromConstantGlobal(Value *V, MemTransferInst *&TheCopy, continue; } - if (CallSite CS = I) { + if (auto CS = CallSite(I)) { // If this is the function being called then we treat it like a load and // ignore it. if (CS.isCallee(&U)) @@ -163,62 +164,75 @@ isOnlyCopiedFromConstantGlobal(AllocaInst *AI, return nullptr; } -Instruction *InstCombiner::visitAllocaInst(AllocaInst &AI) { - // Ensure that the alloca array size argument has type intptr_t, so that - // any casting is exposed early. - if (DL) { - Type *IntPtrTy = DL->getIntPtrType(AI.getType()); - if (AI.getArraySize()->getType() != IntPtrTy) { - Value *V = Builder->CreateIntCast(AI.getArraySize(), - IntPtrTy, false); - AI.setOperand(0, V); - return &AI; - } +static Instruction *simplifyAllocaArraySize(InstCombiner &IC, AllocaInst &AI) { + // Check for array size of 1 (scalar allocation). + if (!AI.isArrayAllocation()) { + // i32 1 is the canonical array size for scalar allocations. + if (AI.getArraySize()->getType()->isIntegerTy(32)) + return nullptr; + + // Canonicalize it. + Value *V = IC.Builder->getInt32(1); + AI.setOperand(0, V); + return &AI; } // Convert: alloca Ty, C - where C is a constant != 1 into: alloca [C x Ty], 1 - if (AI.isArrayAllocation()) { // Check C != 1 - if (const ConstantInt *C = dyn_cast<ConstantInt>(AI.getArraySize())) { - Type *NewTy = - ArrayType::get(AI.getAllocatedType(), C->getZExtValue()); - AllocaInst *New = Builder->CreateAlloca(NewTy, nullptr, AI.getName()); - New->setAlignment(AI.getAlignment()); - - // Scan to the end of the allocation instructions, to skip over a block of - // allocas if possible...also skip interleaved debug info - // - BasicBlock::iterator It = New; - while (isa<AllocaInst>(*It) || isa<DbgInfoIntrinsic>(*It)) ++It; - - // Now that I is pointing to the first non-allocation-inst in the block, - // insert our getelementptr instruction... - // - Type *IdxTy = DL - ? DL->getIntPtrType(AI.getType()) - : Type::getInt64Ty(AI.getContext()); - Value *NullIdx = Constant::getNullValue(IdxTy); - Value *Idx[2] = { NullIdx, NullIdx }; - Instruction *GEP = + if (const ConstantInt *C = dyn_cast<ConstantInt>(AI.getArraySize())) { + Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getZExtValue()); + AllocaInst *New = IC.Builder->CreateAlloca(NewTy, nullptr, AI.getName()); + New->setAlignment(AI.getAlignment()); + + // Scan to the end of the allocation instructions, to skip over a block of + // allocas if possible...also skip interleaved debug info + // + BasicBlock::iterator It = New; + while (isa<AllocaInst>(*It) || isa<DbgInfoIntrinsic>(*It)) + ++It; + + // Now that I is pointing to the first non-allocation-inst in the block, + // insert our getelementptr instruction... + // + Type *IdxTy = IC.getDataLayout().getIntPtrType(AI.getType()); + Value *NullIdx = Constant::getNullValue(IdxTy); + Value *Idx[2] = {NullIdx, NullIdx}; + Instruction *GEP = GetElementPtrInst::CreateInBounds(New, Idx, New->getName() + ".sub"); - InsertNewInstBefore(GEP, *It); + IC.InsertNewInstBefore(GEP, *It); - // Now make everything use the getelementptr instead of the original - // allocation. - return ReplaceInstUsesWith(AI, GEP); - } else if (isa<UndefValue>(AI.getArraySize())) { - return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType())); - } + // Now make everything use the getelementptr instead of the original + // allocation. + return IC.ReplaceInstUsesWith(AI, GEP); + } + + if (isa<UndefValue>(AI.getArraySize())) + return IC.ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType())); + + // Ensure that the alloca array size argument has type intptr_t, so that + // any casting is exposed early. + Type *IntPtrTy = IC.getDataLayout().getIntPtrType(AI.getType()); + if (AI.getArraySize()->getType() != IntPtrTy) { + Value *V = IC.Builder->CreateIntCast(AI.getArraySize(), IntPtrTy, false); + AI.setOperand(0, V); + return &AI; } - if (DL && AI.getAllocatedType()->isSized()) { + return nullptr; +} + +Instruction *InstCombiner::visitAllocaInst(AllocaInst &AI) { + if (auto *I = simplifyAllocaArraySize(*this, AI)) + return I; + + if (AI.getAllocatedType()->isSized()) { // If the alignment is 0 (unspecified), assign it the preferred alignment. if (AI.getAlignment() == 0) - AI.setAlignment(DL->getPrefTypeAlignment(AI.getAllocatedType())); + AI.setAlignment(DL.getPrefTypeAlignment(AI.getAllocatedType())); // Move all alloca's of zero byte objects to the entry block and merge them // together. 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 (DL->getTypeAllocSize(AI.getAllocatedType()) == 0) { + if (DL.getTypeAllocSize(AI.getAllocatedType()) == 0) { // For a zero sized alloca there is no point in doing an array allocation. // This is helpful if the array size is a complicated expression not used // elsewhere. @@ -236,7 +250,7 @@ Instruction *InstCombiner::visitAllocaInst(AllocaInst &AI) { // dominance as the array size was forced to a constant earlier already. AllocaInst *EntryAI = dyn_cast<AllocaInst>(FirstInst); if (!EntryAI || !EntryAI->getAllocatedType()->isSized() || - DL->getTypeAllocSize(EntryAI->getAllocatedType()) != 0) { + DL.getTypeAllocSize(EntryAI->getAllocatedType()) != 0) { AI.moveBefore(FirstInst); return &AI; } @@ -245,7 +259,7 @@ Instruction *InstCombiner::visitAllocaInst(AllocaInst &AI) { // assign it the preferred alignment. if (EntryAI->getAlignment() == 0) EntryAI->setAlignment( - DL->getPrefTypeAlignment(EntryAI->getAllocatedType())); + DL.getPrefTypeAlignment(EntryAI->getAllocatedType())); // Replace this zero-sized alloca with the one at the start of the entry // block after ensuring that the address will be aligned enough for both // types. @@ -269,7 +283,7 @@ Instruction *InstCombiner::visitAllocaInst(AllocaInst &AI) { SmallVector<Instruction *, 4> ToDelete; if (MemTransferInst *Copy = isOnlyCopiedFromConstantGlobal(&AI, ToDelete)) { unsigned SourceAlign = getOrEnforceKnownAlignment( - Copy->getSource(), AI.getAlignment(), DL, AC, &AI, DT); + Copy->getSource(), AI.getAlignment(), DL, &AI, AC, DT); if (AI.getAlignment() <= SourceAlign) { DEBUG(dbgs() << "Found alloca equal to global: " << AI << '\n'); DEBUG(dbgs() << " memcpy = " << *Copy << '\n'); @@ -300,7 +314,8 @@ Instruction *InstCombiner::visitAllocaInst(AllocaInst &AI) { /// /// Note that this will create all of the instructions with whatever insert /// point the \c InstCombiner currently is using. -static LoadInst *combineLoadToNewType(InstCombiner &IC, LoadInst &LI, Type *NewTy) { +static LoadInst *combineLoadToNewType(InstCombiner &IC, LoadInst &LI, Type *NewTy, + const Twine &Suffix = "") { Value *Ptr = LI.getPointerOperand(); unsigned AS = LI.getPointerAddressSpace(); SmallVector<std::pair<unsigned, MDNode *>, 8> MD; @@ -308,7 +323,8 @@ static LoadInst *combineLoadToNewType(InstCombiner &IC, LoadInst &LI, Type *NewT LoadInst *NewLoad = IC.Builder->CreateAlignedLoad( IC.Builder->CreateBitCast(Ptr, NewTy->getPointerTo(AS)), - LI.getAlignment(), LI.getName()); + LI.getAlignment(), LI.getName() + Suffix); + MDBuilder MDB(NewLoad->getContext()); for (const auto &MDPair : MD) { unsigned ID = MDPair.first; MDNode *N = MDPair.second; @@ -335,21 +351,81 @@ static LoadInst *combineLoadToNewType(InstCombiner &IC, LoadInst &LI, Type *NewT break; case LLVMContext::MD_nonnull: - // FIXME: We should translate this into range metadata for integer types - // and vice versa. - if (NewTy->isPointerTy()) + // This only directly applies if the new type is also a pointer. + if (NewTy->isPointerTy()) { NewLoad->setMetadata(ID, N); + break; + } + // If it's integral now, translate it to !range metadata. + if (NewTy->isIntegerTy()) { + auto *ITy = cast<IntegerType>(NewTy); + auto *NullInt = ConstantExpr::getPtrToInt( + ConstantPointerNull::get(cast<PointerType>(Ptr->getType())), ITy); + auto *NonNullInt = + ConstantExpr::getAdd(NullInt, ConstantInt::get(ITy, 1)); + NewLoad->setMetadata(LLVMContext::MD_range, + MDB.createRange(NonNullInt, NullInt)); + } break; case LLVMContext::MD_range: // FIXME: It would be nice to propagate this in some way, but the type - // conversions make it hard. + // conversions make it hard. If the new type is a pointer, we could + // translate it to !nonnull metadata. break; } } return NewLoad; } +/// \brief Combine a store to a new type. +/// +/// Returns the newly created store instruction. +static StoreInst *combineStoreToNewValue(InstCombiner &IC, StoreInst &SI, Value *V) { + Value *Ptr = SI.getPointerOperand(); + unsigned AS = SI.getPointerAddressSpace(); + SmallVector<std::pair<unsigned, MDNode *>, 8> MD; + SI.getAllMetadata(MD); + + StoreInst *NewStore = IC.Builder->CreateAlignedStore( + V, IC.Builder->CreateBitCast(Ptr, V->getType()->getPointerTo(AS)), + SI.getAlignment()); + for (const auto &MDPair : MD) { + unsigned ID = MDPair.first; + MDNode *N = MDPair.second; + // Note, essentially every kind of metadata should be preserved here! This + // routine is supposed to clone a store instruction changing *only its + // type*. The only metadata it makes sense to drop is metadata which is + // invalidated when the pointer type changes. This should essentially + // never be the case in LLVM, but we explicitly switch over only known + // metadata to be conservatively correct. If you are adding metadata to + // LLVM which pertains to stores, you almost certainly want to add it + // here. + switch (ID) { + case LLVMContext::MD_dbg: + case LLVMContext::MD_tbaa: + case LLVMContext::MD_prof: + case LLVMContext::MD_fpmath: + case LLVMContext::MD_tbaa_struct: + case LLVMContext::MD_alias_scope: + case LLVMContext::MD_noalias: + case LLVMContext::MD_nontemporal: + case LLVMContext::MD_mem_parallel_loop_access: + // All of these directly apply. + NewStore->setMetadata(ID, N); + break; + + case LLVMContext::MD_invariant_load: + case LLVMContext::MD_nonnull: + case LLVMContext::MD_range: + // These don't apply for stores. + break; + } + } + + return NewStore; +} + /// \brief Combine loads to match the type of value their uses after looking /// through intervening bitcasts. /// @@ -376,6 +452,35 @@ static Instruction *combineLoadToOperationType(InstCombiner &IC, LoadInst &LI) { if (LI.use_empty()) return nullptr; + Type *Ty = LI.getType(); + const DataLayout &DL = IC.getDataLayout(); + + // Try to canonicalize loads which are only ever stored to operate over + // integers instead of any other type. We only do this when the loaded type + // is sized and has a size exactly the same as its store size and the store + // size is a legal integer type. + if (!Ty->isIntegerTy() && Ty->isSized() && + DL.isLegalInteger(DL.getTypeStoreSizeInBits(Ty)) && + DL.getTypeStoreSizeInBits(Ty) == DL.getTypeSizeInBits(Ty)) { + if (std::all_of(LI.user_begin(), LI.user_end(), [&LI](User *U) { + auto *SI = dyn_cast<StoreInst>(U); + return SI && SI->getPointerOperand() != &LI; + })) { + LoadInst *NewLoad = combineLoadToNewType( + IC, LI, + Type::getIntNTy(LI.getContext(), DL.getTypeStoreSizeInBits(Ty))); + // Replace all the stores with stores of the newly loaded value. + for (auto UI = LI.user_begin(), UE = LI.user_end(); UI != UE;) { + auto *SI = cast<StoreInst>(*UI++); + IC.Builder->SetInsertPoint(SI); + combineStoreToNewValue(IC, *SI, NewLoad); + IC.EraseInstFromFunction(*SI); + } + assert(LI.use_empty() && "Failed to remove all users of the load!"); + // Return the old load so the combiner can delete it safely. + return &LI; + } + } // Fold away bit casts of the loaded value by loading the desired type. if (LI.hasOneUse()) @@ -391,6 +496,218 @@ static Instruction *combineLoadToOperationType(InstCombiner &IC, LoadInst &LI) { return nullptr; } +static Instruction *unpackLoadToAggregate(InstCombiner &IC, LoadInst &LI) { + // FIXME: We could probably with some care handle both volatile and atomic + // stores here but it isn't clear that this is important. + if (!LI.isSimple()) + return nullptr; + + Type *T = LI.getType(); + if (!T->isAggregateType()) + return nullptr; + + assert(LI.getAlignment() && "Alignement must be set at this point"); + + if (auto *ST = dyn_cast<StructType>(T)) { + // If the struct only have one element, we unpack. + if (ST->getNumElements() == 1) { + LoadInst *NewLoad = combineLoadToNewType(IC, LI, ST->getTypeAtIndex(0U), + ".unpack"); + return IC.ReplaceInstUsesWith(LI, IC.Builder->CreateInsertValue( + UndefValue::get(T), NewLoad, 0, LI.getName())); + } + } + + if (auto *AT = dyn_cast<ArrayType>(T)) { + // If the array only have one element, we unpack. + if (AT->getNumElements() == 1) { + LoadInst *NewLoad = combineLoadToNewType(IC, LI, AT->getElementType(), + ".unpack"); + return IC.ReplaceInstUsesWith(LI, IC.Builder->CreateInsertValue( + UndefValue::get(T), NewLoad, 0, LI.getName())); + } + } + + return nullptr; +} + +// If we can determine that all possible objects pointed to by the provided +// pointer value are, not only dereferenceable, but also definitively less than +// or equal to the provided maximum size, then return true. Otherwise, return +// false (constant global values and allocas fall into this category). +// +// FIXME: This should probably live in ValueTracking (or similar). +static bool isObjectSizeLessThanOrEq(Value *V, uint64_t MaxSize, + const DataLayout &DL) { + SmallPtrSet<Value *, 4> Visited; + SmallVector<Value *, 4> Worklist(1, V); + + do { + Value *P = Worklist.pop_back_val(); + P = P->stripPointerCasts(); + + if (!Visited.insert(P).second) + continue; + + if (SelectInst *SI = dyn_cast<SelectInst>(P)) { + Worklist.push_back(SI->getTrueValue()); + Worklist.push_back(SI->getFalseValue()); + continue; + } + + if (PHINode *PN = dyn_cast<PHINode>(P)) { + for (Value *IncValue : PN->incoming_values()) + Worklist.push_back(IncValue); + continue; + } + + if (GlobalAlias *GA = dyn_cast<GlobalAlias>(P)) { + if (GA->mayBeOverridden()) + return false; + Worklist.push_back(GA->getAliasee()); + continue; + } + + // If we know how big this object is, and it is less than MaxSize, continue + // searching. Otherwise, return false. + if (AllocaInst *AI = dyn_cast<AllocaInst>(P)) { + if (!AI->getAllocatedType()->isSized()) + return false; + + ConstantInt *CS = dyn_cast<ConstantInt>(AI->getArraySize()); + if (!CS) + return false; + + uint64_t TypeSize = DL.getTypeAllocSize(AI->getAllocatedType()); + // Make sure that, even if the multiplication below would wrap as an + // uint64_t, we still do the right thing. + if ((CS->getValue().zextOrSelf(128)*APInt(128, TypeSize)).ugt(MaxSize)) + return false; + continue; + } + + if (GlobalVariable *GV = dyn_cast<GlobalVariable>(P)) { + if (!GV->hasDefinitiveInitializer() || !GV->isConstant()) + return false; + + uint64_t InitSize = DL.getTypeAllocSize(GV->getType()->getElementType()); + if (InitSize > MaxSize) + return false; + continue; + } + + return false; + } while (!Worklist.empty()); + + return true; +} + +// If we're indexing into an object of a known size, and the outer index is +// not a constant, but having any value but zero would lead to undefined +// behavior, replace it with zero. +// +// For example, if we have: +// @f.a = private unnamed_addr constant [1 x i32] [i32 12], align 4 +// ... +// %arrayidx = getelementptr inbounds [1 x i32]* @f.a, i64 0, i64 %x +// ... = load i32* %arrayidx, align 4 +// Then we know that we can replace %x in the GEP with i64 0. +// +// FIXME: We could fold any GEP index to zero that would cause UB if it were +// not zero. Currently, we only handle the first such index. Also, we could +// also search through non-zero constant indices if we kept track of the +// offsets those indices implied. +static bool canReplaceGEPIdxWithZero(InstCombiner &IC, GetElementPtrInst *GEPI, + Instruction *MemI, unsigned &Idx) { + if (GEPI->getNumOperands() < 2) + return false; + + // Find the first non-zero index of a GEP. If all indices are zero, return + // one past the last index. + auto FirstNZIdx = [](const GetElementPtrInst *GEPI) { + unsigned I = 1; + for (unsigned IE = GEPI->getNumOperands(); I != IE; ++I) { + Value *V = GEPI->getOperand(I); + if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) + if (CI->isZero()) + continue; + + break; + } + + return I; + }; + + // Skip through initial 'zero' indices, and find the corresponding pointer + // type. See if the next index is not a constant. + Idx = FirstNZIdx(GEPI); + if (Idx == GEPI->getNumOperands()) + return false; + if (isa<Constant>(GEPI->getOperand(Idx))) + return false; + + SmallVector<Value *, 4> Ops(GEPI->idx_begin(), GEPI->idx_begin() + Idx); + Type *AllocTy = GetElementPtrInst::getIndexedType( + cast<PointerType>(GEPI->getOperand(0)->getType()->getScalarType()) + ->getElementType(), + Ops); + if (!AllocTy || !AllocTy->isSized()) + return false; + const DataLayout &DL = IC.getDataLayout(); + uint64_t TyAllocSize = DL.getTypeAllocSize(AllocTy); + + // If there are more indices after the one we might replace with a zero, make + // sure they're all non-negative. If any of them are negative, the overall + // address being computed might be before the base address determined by the + // first non-zero index. + auto IsAllNonNegative = [&]() { + for (unsigned i = Idx+1, e = GEPI->getNumOperands(); i != e; ++i) { + bool KnownNonNegative, KnownNegative; + IC.ComputeSignBit(GEPI->getOperand(i), KnownNonNegative, + KnownNegative, 0, MemI); + if (KnownNonNegative) + continue; + return false; + } + + return true; + }; + + // FIXME: If the GEP is not inbounds, and there are extra indices after the + // one we'll replace, those could cause the address computation to wrap + // (rendering the IsAllNonNegative() check below insufficient). We can do + // better, ignoring zero indicies (and other indicies we can prove small + // enough not to wrap). + if (Idx+1 != GEPI->getNumOperands() && !GEPI->isInBounds()) + return false; + + // Note that isObjectSizeLessThanOrEq will return true only if the pointer is + // also known to be dereferenceable. + return isObjectSizeLessThanOrEq(GEPI->getOperand(0), TyAllocSize, DL) && + IsAllNonNegative(); +} + +// If we're indexing into an object with a variable index for the memory +// access, but the object has only one element, we can assume that the index +// will always be zero. If we replace the GEP, return it. +template <typename T> +static Instruction *replaceGEPIdxWithZero(InstCombiner &IC, Value *Ptr, + T &MemI) { + if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Ptr)) { + unsigned Idx; + if (canReplaceGEPIdxWithZero(IC, GEPI, &MemI, Idx)) { + Instruction *NewGEPI = GEPI->clone(); + NewGEPI->setOperand(Idx, + ConstantInt::get(GEPI->getOperand(Idx)->getType(), 0)); + NewGEPI->insertBefore(GEPI); + MemI.setOperand(MemI.getPointerOperandIndex(), NewGEPI); + return NewGEPI; + } + } + + return nullptr; +} + Instruction *InstCombiner::visitLoadInst(LoadInst &LI) { Value *Op = LI.getOperand(0); @@ -399,23 +716,30 @@ Instruction *InstCombiner::visitLoadInst(LoadInst &LI) { return Res; // Attempt to improve the alignment. - if (DL) { - unsigned KnownAlign = getOrEnforceKnownAlignment( - Op, DL->getPrefTypeAlignment(LI.getType()), DL, AC, &LI, DT); - unsigned LoadAlign = LI.getAlignment(); - unsigned EffectiveLoadAlign = LoadAlign != 0 ? LoadAlign : - DL->getABITypeAlignment(LI.getType()); - - if (KnownAlign > EffectiveLoadAlign) - LI.setAlignment(KnownAlign); - else if (LoadAlign == 0) - LI.setAlignment(EffectiveLoadAlign); + unsigned KnownAlign = getOrEnforceKnownAlignment( + Op, DL.getPrefTypeAlignment(LI.getType()), DL, &LI, AC, DT); + unsigned LoadAlign = LI.getAlignment(); + unsigned EffectiveLoadAlign = + LoadAlign != 0 ? LoadAlign : DL.getABITypeAlignment(LI.getType()); + + if (KnownAlign > EffectiveLoadAlign) + LI.setAlignment(KnownAlign); + else if (LoadAlign == 0) + LI.setAlignment(EffectiveLoadAlign); + + // Replace GEP indices if possible. + if (Instruction *NewGEPI = replaceGEPIdxWithZero(*this, Op, LI)) { + Worklist.Add(NewGEPI); + return &LI; } // None of the following transforms are legal for volatile/atomic loads. // FIXME: Some of it is okay for atomic loads; needs refactoring. if (!LI.isSimple()) return nullptr; + if (Instruction *Res = unpackLoadToAggregate(*this, LI)) + return Res; + // Do really simple store-to-load forwarding and load CSE, to catch cases // where there are several consecutive memory accesses to the same location, // separated by a few arithmetic operations. @@ -466,8 +790,8 @@ Instruction *InstCombiner::visitLoadInst(LoadInst &LI) { if (SelectInst *SI = dyn_cast<SelectInst>(Op)) { // load (select (Cond, &V1, &V2)) --> select(Cond, load &V1, load &V2). unsigned Align = LI.getAlignment(); - if (isSafeToLoadUnconditionally(SI->getOperand(1), SI, Align, DL) && - isSafeToLoadUnconditionally(SI->getOperand(2), SI, Align, DL)) { + if (isSafeToLoadUnconditionally(SI->getOperand(1), SI, Align) && + isSafeToLoadUnconditionally(SI->getOperand(2), SI, Align)) { LoadInst *V1 = Builder->CreateLoad(SI->getOperand(1), SI->getOperand(1)->getName()+".val"); LoadInst *V2 = Builder->CreateLoad(SI->getOperand(2), @@ -521,50 +845,12 @@ static bool combineStoreToValueType(InstCombiner &IC, StoreInst &SI) { if (!SI.isSimple()) return false; - Value *Ptr = SI.getPointerOperand(); Value *V = SI.getValueOperand(); - unsigned AS = SI.getPointerAddressSpace(); - SmallVector<std::pair<unsigned, MDNode *>, 8> MD; - SI.getAllMetadata(MD); // Fold away bit casts of the stored value by storing the original type. if (auto *BC = dyn_cast<BitCastInst>(V)) { V = BC->getOperand(0); - StoreInst *NewStore = IC.Builder->CreateAlignedStore( - V, IC.Builder->CreateBitCast(Ptr, V->getType()->getPointerTo(AS)), - SI.getAlignment()); - for (const auto &MDPair : MD) { - unsigned ID = MDPair.first; - MDNode *N = MDPair.second; - // Note, essentially every kind of metadata should be preserved here! This - // routine is supposed to clone a store instruction changing *only its - // type*. The only metadata it makes sense to drop is metadata which is - // invalidated when the pointer type changes. This should essentially - // never be the case in LLVM, but we explicitly switch over only known - // metadata to be conservatively correct. If you are adding metadata to - // LLVM which pertains to stores, you almost certainly want to add it - // here. - switch (ID) { - case LLVMContext::MD_dbg: - case LLVMContext::MD_tbaa: - case LLVMContext::MD_prof: - case LLVMContext::MD_fpmath: - case LLVMContext::MD_tbaa_struct: - case LLVMContext::MD_alias_scope: - case LLVMContext::MD_noalias: - case LLVMContext::MD_nontemporal: - case LLVMContext::MD_mem_parallel_loop_access: - // All of these directly apply. - NewStore->setMetadata(ID, N); - break; - - case LLVMContext::MD_invariant_load: - case LLVMContext::MD_nonnull: - case LLVMContext::MD_range: - // These don't apply for stores. - break; - } - } + combineStoreToNewValue(IC, SI, V); return true; } @@ -573,6 +859,39 @@ static bool combineStoreToValueType(InstCombiner &IC, StoreInst &SI) { return false; } +static bool unpackStoreToAggregate(InstCombiner &IC, StoreInst &SI) { + // FIXME: We could probably with some care handle both volatile and atomic + // stores here but it isn't clear that this is important. + if (!SI.isSimple()) + return false; + + Value *V = SI.getValueOperand(); + Type *T = V->getType(); + + if (!T->isAggregateType()) + return false; + + if (auto *ST = dyn_cast<StructType>(T)) { + // If the struct only have one element, we unpack. + if (ST->getNumElements() == 1) { + V = IC.Builder->CreateExtractValue(V, 0); + combineStoreToNewValue(IC, SI, V); + return true; + } + } + + if (auto *AT = dyn_cast<ArrayType>(T)) { + // If the array only have one element, we unpack. + if (AT->getNumElements() == 1) { + V = IC.Builder->CreateExtractValue(V, 0); + combineStoreToNewValue(IC, SI, V); + return true; + } + } + + return false; +} + /// equivalentAddressValues - Test if A and B will obviously have the same /// value. This includes recognizing that %t0 and %t1 will have the same /// value in code like this: @@ -611,17 +930,25 @@ Instruction *InstCombiner::visitStoreInst(StoreInst &SI) { return EraseInstFromFunction(SI); // Attempt to improve the alignment. - if (DL) { - unsigned KnownAlign = getOrEnforceKnownAlignment( - Ptr, DL->getPrefTypeAlignment(Val->getType()), DL, AC, &SI, DT); - unsigned StoreAlign = SI.getAlignment(); - unsigned EffectiveStoreAlign = StoreAlign != 0 ? StoreAlign : - DL->getABITypeAlignment(Val->getType()); - - if (KnownAlign > EffectiveStoreAlign) - SI.setAlignment(KnownAlign); - else if (StoreAlign == 0) - SI.setAlignment(EffectiveStoreAlign); + unsigned KnownAlign = getOrEnforceKnownAlignment( + Ptr, DL.getPrefTypeAlignment(Val->getType()), DL, &SI, AC, DT); + unsigned StoreAlign = SI.getAlignment(); + unsigned EffectiveStoreAlign = + StoreAlign != 0 ? StoreAlign : DL.getABITypeAlignment(Val->getType()); + + if (KnownAlign > EffectiveStoreAlign) + SI.setAlignment(KnownAlign); + else if (StoreAlign == 0) + SI.setAlignment(EffectiveStoreAlign); + + // Try to canonicalize the stored type. + if (unpackStoreToAggregate(*this, SI)) + return EraseInstFromFunction(SI); + + // Replace GEP indices if possible. + if (Instruction *NewGEPI = replaceGEPIdxWithZero(*this, Ptr, SI)) { + Worklist.Add(NewGEPI); + return &SI; } // Don't hack volatile/atomic stores. |