From 07ff9b03f6bf750e491cdde73f943a65f58f0d80 Mon Sep 17 00:00:00 2001 From: "Duncan P. N. Exon Smith" Date: Fri, 13 Mar 2015 19:34:55 +0000 Subject: [PATCH] instcombine: alloca: Limit array size type promotion Move type promotion of the size of the array allocation to the end of `simplifyAllocaArraySize()`. This avoids promoting the type of the array size if it's a `ConstantInt`, since the next -instcombine iteration will drop it to a scalar allocation anyway. Similarly, this avoids promoting the type if it's an `UndefValue`, in which case the alloca gets RAUW'ed. This is NFC when considered over the lifetime of -instcombine, since it's just reducing the number of iterations needed to reach fixed point. llvm-svn: 232201 --- .../InstCombine/InstCombineLoadStoreAlloca.cpp | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp index a44a8de..deed58c 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp @@ -169,15 +169,6 @@ static Instruction *simplifyAllocaArraySize(InstCombiner &IC, AllocaInst &AI) { if (!AI.isArrayAllocation()) return nullptr; - // 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; - } - // Convert: alloca Ty, C - where C is a constant != 1 into: alloca [C x Ty], 1 if (const ConstantInt *C = dyn_cast(AI.getArraySize())) { Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getZExtValue()); @@ -209,6 +200,15 @@ static Instruction *simplifyAllocaArraySize(InstCombiner &IC, AllocaInst &AI) { if (isa(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; + } + return nullptr; } -- 2.7.4