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[InstCombine] Remove unnecessary MaybeAlign use (NFC) 

Alloca align is required now.
This commit is contained in:
Nikita Popov 2020-06-06 11:15:45 +02:00
parent 97a670958c
commit a4953db530
1 changed files with 32 additions and 34 deletions
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66
llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
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@ -365,42 +365,40 @@ Instruction *InstCombiner::visitAllocaInst(AllocaInst &AI) {
}
}
if (AI.getAlignment()) {
// Check to see if this allocation is only modified by a memcpy/memmove from
// a constant whose alignment is equal to or exceeds that of the allocation.
// If this is the case, we can change all users to use the constant global
// instead. This is commonly produced by the CFE by constructs like "void
// foo() { int A[] = {1,2,3,4,5,6,7,8,9...}; }" if 'A' is only subsequently
// read.
SmallVector<Instruction *, 4> ToDelete;
if (MemTransferInst *Copy = isOnlyCopiedFromConstantMemory(AA, &AI, ToDelete)) {
MaybeAlign AllocaAlign = AI.getAlign();
Align SourceAlign = getOrEnforceKnownAlignment(
Copy->getSource(), AllocaAlign, DL, &AI, &AC, &DT);
if ((!AllocaAlign || *AllocaAlign <= SourceAlign) &&
isDereferenceableForAllocaSize(Copy->getSource(), &AI, DL)) {
LLVM_DEBUG(dbgs() << "Found alloca equal to global: " << AI << '\n');
LLVM_DEBUG(dbgs() << " memcpy = " << *Copy << '\n');
for (unsigned i = 0, e = ToDelete.size(); i != e; ++i)
eraseInstFromFunction(*ToDelete[i]);
Value *TheSrc = Copy->getSource();
auto *SrcTy = TheSrc->getType();
auto *DestTy = PointerType::get(AI.getType()->getPointerElementType(),
SrcTy->getPointerAddressSpace());
Value *Cast =
Builder.CreatePointerBitCastOrAddrSpaceCast(TheSrc, DestTy);
if (AI.getType()->getPointerAddressSpace() ==
SrcTy->getPointerAddressSpace()) {
Instruction *NewI = replaceInstUsesWith(AI, Cast);
eraseInstFromFunction(*Copy);
++NumGlobalCopies;
return NewI;
}
PointerReplacer PtrReplacer(*this);
PtrReplacer.replacePointer(AI, Cast);
// Check to see if this allocation is only modified by a memcpy/memmove from
// a constant whose alignment is equal to or exceeds that of the allocation.
// If this is the case, we can change all users to use the constant global
// instead. This is commonly produced by the CFE by constructs like "void
// foo() { int A[] = {1,2,3,4,5,6,7,8,9...}; }" if 'A' is only subsequently
// read.
SmallVector<Instruction *, 4> ToDelete;
if (MemTransferInst *Copy = isOnlyCopiedFromConstantMemory(AA, &AI, ToDelete)) {
Align AllocaAlign = AI.getAlign();
Align SourceAlign = getOrEnforceKnownAlignment(
Copy->getSource(), AllocaAlign, DL, &AI, &AC, &DT);
if (AllocaAlign <= SourceAlign &&
isDereferenceableForAllocaSize(Copy->getSource(), &AI, DL)) {
LLVM_DEBUG(dbgs() << "Found alloca equal to global: " << AI << '\n');
LLVM_DEBUG(dbgs() << " memcpy = " << *Copy << '\n');
for (unsigned i = 0, e = ToDelete.size(); i != e; ++i)
eraseInstFromFunction(*ToDelete[i]);
Value *TheSrc = Copy->getSource();
auto *SrcTy = TheSrc->getType();
auto *DestTy = PointerType::get(AI.getType()->getPointerElementType(),
SrcTy->getPointerAddressSpace());
Value *Cast =
Builder.CreatePointerBitCastOrAddrSpaceCast(TheSrc, DestTy);
if (AI.getType()->getPointerAddressSpace() ==
SrcTy->getPointerAddressSpace()) {
Instruction *NewI = replaceInstUsesWith(AI, Cast);
eraseInstFromFunction(*Copy);
++NumGlobalCopies;
return NewI;
}
PointerReplacer PtrReplacer(*this);
PtrReplacer.replacePointer(AI, Cast);
++NumGlobalCopies;
}
}