#include "llvm/Transforms/Utils/Local.h"
using namespace llvm;
+#define DEBUG_TYPE "instcombine"
+
STATISTIC(NumDeadStore, "Number of dead stores eliminated");
STATISTIC(NumGlobalCopies, "Number of allocas copied from constant global");
static bool pointsToConstantGlobal(Value *V) {
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
return GV->isConstant();
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
+
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
if (CE->getOpcode() == Instruction::BitCast ||
+ CE->getOpcode() == Instruction::AddrSpaceCast ||
CE->getOpcode() == Instruction::GetElementPtr)
return pointsToConstantGlobal(CE->getOperand(0));
+ }
return false;
}
/// can optimize this.
static bool
isOnlyCopiedFromConstantGlobal(Value *V, MemTransferInst *&TheCopy,
- SmallVectorImpl<Instruction *> &ToDelete,
- bool IsOffset = false) {
+ SmallVectorImpl<Instruction *> &ToDelete) {
// We track lifetime intrinsics as we encounter them. If we decide to go
// ahead and replace the value with the global, this lets the caller quickly
// eliminate the markers.
- for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI!=E; ++UI) {
- User *U = cast<Instruction>(*UI);
-
- if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
- // Ignore non-volatile loads, they are always ok.
- if (!LI->isSimple()) return false;
- continue;
- }
-
- if (BitCastInst *BCI = dyn_cast<BitCastInst>(U)) {
- // If uses of the bitcast are ok, we are ok.
- if (!isOnlyCopiedFromConstantGlobal(BCI, TheCopy, ToDelete, IsOffset))
- return false;
- continue;
- }
- if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(U)) {
- // If the GEP has all zero indices, it doesn't offset the pointer. If it
- // doesn't, it does.
- if (!isOnlyCopiedFromConstantGlobal(
- GEP, TheCopy, ToDelete, IsOffset || !GEP->hasAllZeroIndices()))
- return false;
- continue;
- }
+ SmallVector<std::pair<Value *, bool>, 35> ValuesToInspect;
+ ValuesToInspect.push_back(std::make_pair(V, false));
+ while (!ValuesToInspect.empty()) {
+ auto ValuePair = ValuesToInspect.pop_back_val();
+ const bool IsOffset = ValuePair.second;
+ for (auto &U : ValuePair.first->uses()) {
+ Instruction *I = cast<Instruction>(U.getUser());
+
+ if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
+ // Ignore non-volatile loads, they are always ok.
+ if (!LI->isSimple()) return false;
+ continue;
+ }
- if (CallSite CS = U) {
- // If this is the function being called then we treat it like a load and
- // ignore it.
- if (CS.isCallee(UI))
+ if (isa<BitCastInst>(I) || isa<AddrSpaceCastInst>(I)) {
+ // If uses of the bitcast are ok, we are ok.
+ ValuesToInspect.push_back(std::make_pair(I, IsOffset));
+ continue;
+ }
+ if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(I)) {
+ // If the GEP has all zero indices, it doesn't offset the pointer. If it
+ // doesn't, it does.
+ ValuesToInspect.push_back(
+ std::make_pair(I, IsOffset || !GEP->hasAllZeroIndices()));
continue;
+ }
- // Inalloca arguments are clobbered by the call.
- unsigned ArgNo = CS.getArgumentNo(UI);
- if (CS.isInAllocaArgument(ArgNo))
- return false;
+ if (CallSite CS = I) {
+ // If this is the function being called then we treat it like a load and
+ // ignore it.
+ if (CS.isCallee(&U))
+ continue;
- // If this is a readonly/readnone call site, then we know it is just a
- // load (but one that potentially returns the value itself), so we can
- // ignore it if we know that the value isn't captured.
- if (CS.onlyReadsMemory() &&
- (CS.getInstruction()->use_empty() || CS.doesNotCapture(ArgNo)))
- continue;
+ // Inalloca arguments are clobbered by the call.
+ unsigned ArgNo = CS.getArgumentNo(&U);
+ if (CS.isInAllocaArgument(ArgNo))
+ return false;
- // If this is being passed as a byval argument, the caller is making a
- // copy, so it is only a read of the alloca.
- if (CS.isByValArgument(ArgNo))
- continue;
- }
+ // If this is a readonly/readnone call site, then we know it is just a
+ // load (but one that potentially returns the value itself), so we can
+ // ignore it if we know that the value isn't captured.
+ if (CS.onlyReadsMemory() &&
+ (CS.getInstruction()->use_empty() || CS.doesNotCapture(ArgNo)))
+ continue;
+
+ // If this is being passed as a byval argument, the caller is making a
+ // copy, so it is only a read of the alloca.
+ if (CS.isByValArgument(ArgNo))
+ continue;
+ }
- // Lifetime intrinsics can be handled by the caller.
- if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(U)) {
- if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
- II->getIntrinsicID() == Intrinsic::lifetime_end) {
- assert(II->use_empty() && "Lifetime markers have no result to use!");
- ToDelete.push_back(II);
- continue;
+ // Lifetime intrinsics can be handled by the caller.
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
+ if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
+ II->getIntrinsicID() == Intrinsic::lifetime_end) {
+ assert(II->use_empty() && "Lifetime markers have no result to use!");
+ ToDelete.push_back(II);
+ continue;
+ }
}
- }
- // If this is isn't our memcpy/memmove, reject it as something we can't
- // handle.
- MemTransferInst *MI = dyn_cast<MemTransferInst>(U);
- if (MI == 0)
- return false;
+ // If this is isn't our memcpy/memmove, reject it as something we can't
+ // handle.
+ MemTransferInst *MI = dyn_cast<MemTransferInst>(I);
+ if (!MI)
+ return false;
- // If the transfer is using the alloca as a source of the transfer, then
- // ignore it since it is a load (unless the transfer is volatile).
- if (UI.getOperandNo() == 1) {
- if (MI->isVolatile()) return false;
- continue;
- }
+ // If the transfer is using the alloca as a source of the transfer, then
+ // ignore it since it is a load (unless the transfer is volatile).
+ if (U.getOperandNo() == 1) {
+ if (MI->isVolatile()) return false;
+ continue;
+ }
- // If we already have seen a copy, reject the second one.
- if (TheCopy) return false;
+ // If we already have seen a copy, reject the second one.
+ if (TheCopy) return false;
- // If the pointer has been offset from the start of the alloca, we can't
- // safely handle this.
- if (IsOffset) return false;
+ // If the pointer has been offset from the start of the alloca, we can't
+ // safely handle this.
+ if (IsOffset) return false;
- // If the memintrinsic isn't using the alloca as the dest, reject it.
- if (UI.getOperandNo() != 0) return false;
+ // If the memintrinsic isn't using the alloca as the dest, reject it.
+ if (U.getOperandNo() != 0) return false;
- // If the source of the memcpy/move is not a constant global, reject it.
- if (!pointsToConstantGlobal(MI->getSource()))
- return false;
+ // If the source of the memcpy/move is not a constant global, reject it.
+ if (!pointsToConstantGlobal(MI->getSource()))
+ return false;
- // Otherwise, the transform is safe. Remember the copy instruction.
- TheCopy = MI;
+ // Otherwise, the transform is safe. Remember the copy instruction.
+ TheCopy = MI;
+ }
}
return true;
}
static MemTransferInst *
isOnlyCopiedFromConstantGlobal(AllocaInst *AI,
SmallVectorImpl<Instruction *> &ToDelete) {
- MemTransferInst *TheCopy = 0;
+ MemTransferInst *TheCopy = nullptr;
if (isOnlyCopiedFromConstantGlobal(AI, TheCopy, ToDelete))
return TheCopy;
- return 0;
+ 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 (TD) {
- Type *IntPtrTy = TD->getIntPtrType(AI.getType());
+ if (DL) {
+ Type *IntPtrTy = DL->getIntPtrType(AI.getType());
if (AI.getArraySize()->getType() != IntPtrTy) {
Value *V = Builder->CreateIntCast(AI.getArraySize(),
IntPtrTy, false);
if (const ConstantInt *C = dyn_cast<ConstantInt>(AI.getArraySize())) {
Type *NewTy =
ArrayType::get(AI.getAllocatedType(), C->getZExtValue());
- AllocaInst *New = Builder->CreateAlloca(NewTy, 0, AI.getName());
+ 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
// Now that I is pointing to the first non-allocation-inst in the block,
// insert our getelementptr instruction...
//
- Type *IdxTy = TD
- ? TD->getIntPtrType(AI.getType())
+ Type *IdxTy = DL
+ ? DL->getIntPtrType(AI.getType())
: Type::getInt64Ty(AI.getContext());
Value *NullIdx = Constant::getNullValue(IdxTy);
Value *Idx[2] = { NullIdx, NullIdx };
}
}
- if (TD && AI.getAllocatedType()->isSized()) {
+ if (DL && AI.getAllocatedType()->isSized()) {
// If the alignment is 0 (unspecified), assign it the preferred alignment.
if (AI.getAlignment() == 0)
- AI.setAlignment(TD->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 (TD->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.
// dominance as the array size was forced to a constant earlier already.
AllocaInst *EntryAI = dyn_cast<AllocaInst>(FirstInst);
if (!EntryAI || !EntryAI->getAllocatedType()->isSized() ||
- TD->getTypeAllocSize(EntryAI->getAllocatedType()) != 0) {
+ DL->getTypeAllocSize(EntryAI->getAllocatedType()) != 0) {
AI.moveBefore(FirstInst);
return &AI;
}
// assign it the preferred alignment.
if (EntryAI->getAlignment() == 0)
EntryAI->setAlignment(
- TD->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.
SmallVector<Instruction *, 4> ToDelete;
if (MemTransferInst *Copy = isOnlyCopiedFromConstantGlobal(&AI, ToDelete)) {
unsigned SourceAlign = getOrEnforceKnownAlignment(Copy->getSource(),
- AI.getAlignment(), TD);
+ AI.getAlignment(),
+ DL, AT, &AI, DT);
if (AI.getAlignment() <= SourceAlign) {
DEBUG(dbgs() << "Found alloca equal to global: " << AI << '\n');
DEBUG(dbgs() << " memcpy = " << *Copy << '\n');
/// InstCombineLoadCast - Fold 'load (cast P)' -> cast (load P)' when possible.
static Instruction *InstCombineLoadCast(InstCombiner &IC, LoadInst &LI,
- const DataLayout *TD) {
+ const DataLayout *DL) {
User *CI = cast<User>(LI.getOperand(0));
Value *CastOp = CI->getOperand(0);
// If the address spaces don't match, don't eliminate the cast.
if (DestTy->getAddressSpace() != SrcTy->getAddressSpace())
- return 0;
+ return nullptr;
Type *SrcPTy = SrcTy->getElementType();
if (ArrayType *ASrcTy = dyn_cast<ArrayType>(SrcPTy))
if (Constant *CSrc = dyn_cast<Constant>(CastOp))
if (ASrcTy->getNumElements() != 0) {
- Type *IdxTy = TD
- ? TD->getIntPtrType(SrcTy)
+ Type *IdxTy = DL
+ ? DL->getIntPtrType(SrcTy)
: Type::getInt64Ty(SrcTy->getContext());
Value *Idx = Constant::getNullValue(IdxTy);
Value *Idxs[2] = { Idx, Idx };
NewLoad->setAlignment(LI.getAlignment());
NewLoad->setAtomic(LI.getOrdering(), LI.getSynchScope());
// Now cast the result of the load.
+ PointerType *OldTy = dyn_cast<PointerType>(NewLoad->getType());
+ PointerType *NewTy = dyn_cast<PointerType>(LI.getType());
+ if (OldTy && NewTy &&
+ OldTy->getAddressSpace() != NewTy->getAddressSpace()) {
+ return new AddrSpaceCastInst(NewLoad, LI.getType());
+ }
+
return new BitCastInst(NewLoad, LI.getType());
}
}
}
- return 0;
+ return nullptr;
}
Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
Value *Op = LI.getOperand(0);
// Attempt to improve the alignment.
- if (TD) {
+ if (DL) {
unsigned KnownAlign =
- getOrEnforceKnownAlignment(Op, TD->getPrefTypeAlignment(LI.getType()),TD);
+ getOrEnforceKnownAlignment(Op, DL->getPrefTypeAlignment(LI.getType()),
+ DL, AT, &LI, DT);
unsigned LoadAlign = LI.getAlignment();
unsigned EffectiveLoadAlign = LoadAlign != 0 ? LoadAlign :
- TD->getABITypeAlignment(LI.getType());
+ DL->getABITypeAlignment(LI.getType());
if (KnownAlign > EffectiveLoadAlign)
LI.setAlignment(KnownAlign);
// load (cast X) --> cast (load X) iff safe.
if (isa<CastInst>(Op))
- if (Instruction *Res = InstCombineLoadCast(*this, LI, TD))
+ if (Instruction *Res = InstCombineLoadCast(*this, LI, DL))
return Res;
// 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 0;
+ if (!LI.isSimple()) return nullptr;
// Do really simple store-to-load forwarding and load CSE, to catch cases
// where there are several consecutive memory accesses to the same location,
// Instcombine load (constantexpr_cast global) -> cast (load global)
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op))
if (CE->isCast())
- if (Instruction *Res = InstCombineLoadCast(*this, LI, TD))
+ if (Instruction *Res = InstCombineLoadCast(*this, LI, DL))
return Res;
if (Op->hasOneUse()) {
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, TD) &&
- isSafeToLoadUnconditionally(SI->getOperand(2), SI, Align, TD)) {
+ if (isSafeToLoadUnconditionally(SI->getOperand(1), SI, Align, DL) &&
+ isSafeToLoadUnconditionally(SI->getOperand(2), SI, Align, DL)) {
LoadInst *V1 = Builder->CreateLoad(SI->getOperand(1),
SI->getOperand(1)->getName()+".val");
LoadInst *V2 = Builder->CreateLoad(SI->getOperand(2),
}
}
}
- return 0;
+ return nullptr;
}
/// InstCombineStoreToCast - Fold store V, (cast P) -> store (cast V), P
User *CI = cast<User>(SI.getOperand(1));
Value *CastOp = CI->getOperand(0);
- Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
+ Type *DestPTy = CI->getType()->getPointerElementType();
PointerType *SrcTy = dyn_cast<PointerType>(CastOp->getType());
- if (SrcTy == 0) return 0;
+ if (!SrcTy) return nullptr;
Type *SrcPTy = SrcTy->getElementType();
if (!DestPTy->isIntegerTy() && !DestPTy->isPointerTy())
- return 0;
+ return nullptr;
/// NewGEPIndices - If SrcPTy is an aggregate type, we can emit a "noop gep"
/// to its first element. This allows us to handle things like:
}
if (!SrcPTy->isIntegerTy() && !SrcPTy->isPointerTy())
- return 0;
+ return nullptr;
+
+ // If the pointers point into different address spaces don't do the
+ // transformation.
+ if (SrcTy->getAddressSpace() != CI->getType()->getPointerAddressSpace())
+ return nullptr;
- // If the pointers point into different address spaces or if they point to
- // values with different sizes, we can't do the transformation.
+ // If the pointers point to values of different sizes don't do the
+ // transformation.
if (!IC.getDataLayout() ||
- SrcTy->getAddressSpace() !=
- cast<PointerType>(CI->getType())->getAddressSpace() ||
IC.getDataLayout()->getTypeSizeInBits(SrcPTy) !=
IC.getDataLayout()->getTypeSizeInBits(DestPTy))
- return 0;
+ return nullptr;
+
+ // If the pointers point to pointers to different address spaces don't do the
+ // transformation. It is not safe to introduce an addrspacecast instruction in
+ // this case since, depending on the target, addrspacecast may not be a no-op
+ // cast.
+ if (SrcPTy->isPointerTy() && DestPTy->isPointerTy() &&
+ SrcPTy->getPointerAddressSpace() != DestPTy->getPointerAddressSpace())
+ return nullptr;
// Okay, we are casting from one integer or pointer type to another of
// the same size. Instead of casting the pointer before
// the store, cast the value to be stored.
Value *NewCast;
- Value *SIOp0 = SI.getOperand(0);
Instruction::CastOps opcode = Instruction::BitCast;
- Type* CastSrcTy = SIOp0->getType();
+ Type* CastSrcTy = DestPTy;
Type* CastDstTy = SrcPTy;
if (CastDstTy->isPointerTy()) {
if (CastSrcTy->isIntegerTy())
opcode = Instruction::IntToPtr;
} else if (CastDstTy->isIntegerTy()) {
- if (SIOp0->getType()->isPointerTy())
+ if (CastSrcTy->isPointerTy())
opcode = Instruction::PtrToInt;
}
if (!NewGEPIndices.empty())
CastOp = IC.Builder->CreateInBoundsGEP(CastOp, NewGEPIndices);
+ Value *SIOp0 = SI.getOperand(0);
NewCast = IC.Builder->CreateCast(opcode, SIOp0, CastDstTy,
SIOp0->getName()+".c");
SI.setOperand(0, NewCast);
Value *Ptr = SI.getOperand(1);
// Attempt to improve the alignment.
- if (TD) {
+ if (DL) {
unsigned KnownAlign =
- getOrEnforceKnownAlignment(Ptr, TD->getPrefTypeAlignment(Val->getType()),
- TD);
+ getOrEnforceKnownAlignment(Ptr, DL->getPrefTypeAlignment(Val->getType()),
+ DL, AT, &SI, DT);
unsigned StoreAlign = SI.getAlignment();
unsigned EffectiveStoreAlign = StoreAlign != 0 ? StoreAlign :
- TD->getABITypeAlignment(Val->getType());
+ DL->getABITypeAlignment(Val->getType());
if (KnownAlign > EffectiveStoreAlign)
SI.setAlignment(KnownAlign);
// Don't hack volatile/atomic stores.
// FIXME: Some bits are legal for atomic stores; needs refactoring.
- if (!SI.isSimple()) return 0;
+ if (!SI.isSimple()) return nullptr;
// If the RHS is an alloca with a single use, zapify the store, making the
// alloca dead.
if (Instruction *U = dyn_cast<Instruction>(Val))
Worklist.Add(U); // Dropped a use.
}
- return 0; // Do not modify these!
+ return nullptr; // Do not modify these!
}
// store undef, Ptr -> noop
if (BranchInst *BI = dyn_cast<BranchInst>(BBI))
if (BI->isUnconditional())
if (SimplifyStoreAtEndOfBlock(SI))
- return 0; // xform done!
+ return nullptr; // xform done!
- return 0;
+ return nullptr;
}
/// SimplifyStoreAtEndOfBlock - Turn things like:
// the other predecessor.
pred_iterator PI = pred_begin(DestBB);
BasicBlock *P = *PI;
- BasicBlock *OtherBB = 0;
+ BasicBlock *OtherBB = nullptr;
if (P != StoreBB)
OtherBB = P;
// If the other block ends in an unconditional branch, check for the 'if then
// else' case. there is an instruction before the branch.
- StoreInst *OtherStore = 0;
+ StoreInst *OtherStore = nullptr;
if (OtherBr->isUnconditional()) {
--BBI;
// Skip over debugging info.
InsertNewInstBefore(NewSI, *BBI);
NewSI->setDebugLoc(OtherStore->getDebugLoc());
- // If the two stores had the same TBAA tag, preserve it.
- if (MDNode *TBAATag = SI.getMetadata(LLVMContext::MD_tbaa))
- if ((TBAATag = MDNode::getMostGenericTBAA(TBAATag,
- OtherStore->getMetadata(LLVMContext::MD_tbaa))))
- NewSI->setMetadata(LLVMContext::MD_tbaa, TBAATag);
-
+ // If the two stores had AA tags, merge them.
+ AAMDNodes AATags;
+ SI.getAAMetadata(AATags);
+ if (AATags) {
+ OtherStore->getAAMetadata(AATags, /* Merge = */ true);
+ NewSI->setAAMetadata(AATags);
+ }
// Nuke the old stores.
EraseInstFromFunction(SI);
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