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instcombine: alloca: Split out simplifyAllocaArraySize(), NFC

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Follow-up commits will change some of the logic here.  Splitting into a
separate function simplifies the logic by allowing early returns instead
of deeper nesting.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232197 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan P. N. Exon Smith 2015-03-13 19:22:03 +00:00
parent 52a1ca5306
commit 80cfeabd48
1 changed files with 15 additions and 8 deletions
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23
lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
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@ -164,12 +164,12 @@ isOnlyCopiedFromConstantGlobal(AllocaInst *AI,
return nullptr;
}
Instruction *InstCombiner::visitAllocaInst(AllocaInst &AI) {
static Instruction *simplifyAllocaArraySize(InstCombiner &IC, AllocaInst &AI) {
// Ensure that the alloca array size argument has type intptr_t, so that
// any casting is exposed early.
Type *IntPtrTy = DL.getIntPtrType(AI.getType());
Type *IntPtrTy = IC.getDataLayout().getIntPtrType(AI.getType());
if (AI.getArraySize()->getType() != IntPtrTy) {
Value *V = Builder->CreateIntCast(AI.getArraySize(), IntPtrTy, false);
Value *V = IC.Builder->CreateIntCast(AI.getArraySize(), IntPtrTy, false);
AI.setOperand(0, V);
return &AI;
}
@ -179,7 +179,7 @@ Instruction *InstCombiner::visitAllocaInst(AllocaInst &AI) {
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());
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
@ -191,21 +191,28 @@ Instruction *InstCombiner::visitAllocaInst(AllocaInst &AI) {
// Now that I is pointing to the first non-allocation-inst in the block,
// insert our getelementptr instruction...
//
Type *IdxTy = DL.getIntPtrType(AI.getType());
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);
return IC.ReplaceInstUsesWith(AI, GEP);
} else if (isa<UndefValue>(AI.getArraySize())) {
return ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
return IC.ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
}
}
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)