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instcombine: alloca: Remove nesting in simplifyAllocaArraySize(), NFC

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232199 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan P. N. Exon Smith 2015-03-13 19:26:33 +00:00
parent cd67bbf07f
commit 7c93bfa994
1 changed files with 28 additions and 25 deletions
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53
lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
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@ -174,38 +174,41 @@ static Instruction *simplifyAllocaArraySize(InstCombiner &IC, AllocaInst &AI) {
return &AI; return &AI;
} }
// Check C != 1
if (!AI.isArrayAllocation())
return nullptr;
// Convert: alloca Ty, C - where C is a constant != 1 into: alloca [C x Ty], 1 // 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())) {
if (const ConstantInt *C = dyn_cast<ConstantInt>(AI.getArraySize())) { Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getZExtValue());
Type *NewTy = AllocaInst *New = IC.Builder->CreateAlloca(NewTy, nullptr, AI.getName());
ArrayType::get(AI.getAllocatedType(), C->getZExtValue()); New->setAlignment(AI.getAlignment());
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 // Scan to the end of the allocation instructions, to skip over a block of
// allocas if possible...also skip interleaved debug info // allocas if possible...also skip interleaved debug info
// //
BasicBlock::iterator It = New; BasicBlock::iterator It = New;
while (isa<AllocaInst>(*It) || isa<DbgInfoIntrinsic>(*It)) ++It; while (isa<AllocaInst>(*It) || isa<DbgInfoIntrinsic>(*It))
++It;
// Now that I is pointing to the first non-allocation-inst in the block, // Now that I is pointing to the first non-allocation-inst in the block,
// insert our getelementptr instruction... // insert our getelementptr instruction...
// //
Type *IdxTy = IC.getDataLayout().getIntPtrType(AI.getType()); Type *IdxTy = IC.getDataLayout().getIntPtrType(AI.getType());
Value *NullIdx = Constant::getNullValue(IdxTy); Value *NullIdx = Constant::getNullValue(IdxTy);
Value *Idx[2] = { NullIdx, NullIdx }; Value *Idx[2] = {NullIdx, NullIdx};
Instruction *GEP = Instruction *GEP =
GetElementPtrInst::CreateInBounds(New, Idx, New->getName() + ".sub"); GetElementPtrInst::CreateInBounds(New, Idx, New->getName() + ".sub");
IC.InsertNewInstBefore(GEP, *It); IC.InsertNewInstBefore(GEP, *It);
// Now make everything use the getelementptr instead of the original // Now make everything use the getelementptr instead of the original
// allocation. // allocation.
return IC.ReplaceInstUsesWith(AI, GEP); return IC.ReplaceInstUsesWith(AI, GEP);
} else if (isa<UndefValue>(AI.getArraySize())) {
return IC.ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
}
} }
if (isa<UndefValue>(AI.getArraySize()))
return IC.ReplaceInstUsesWith(AI, Constant::getNullValue(AI.getType()));
return nullptr; return nullptr;
} }