From 2ad8cf5555b7d53cc11f34d6fac019c4028aea25 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Sun, 11 Oct 2009 23:02:46 +0000 Subject: [PATCH] remove some harmful code that would turn an insertelement on an undef into a shuffle even if it was used by another insertelement. If the visitation order of instcombine was wrong, this would turn a chain of insertelements into a chain of shufflevectors, which was quite painful. Since CollectShuffleElements handles these cases, the code can just be nuked. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83810 91177308-0d34-0410-b5e6-96231b3b80d8 --- .../Scalar/InstructionCombining.cpp | 22 ------------------- 1 file changed, 22 deletions(-) diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index dcb65a8ed91..0c790f63150 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -12472,28 +12472,6 @@ Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) { if (EI->getOperand(0) == VecOp && ExtractedIdx == InsertedIdx) return ReplaceInstUsesWith(IE, VecOp); - // We could theoretically do this for ANY input. However, doing so could - // turn chains of insertelement instructions into a chain of shufflevector - // instructions, and right now we do not merge shufflevectors. As such, - // only do this in a situation where it is clear that there is benefit. - if (isa(VecOp) || isa(VecOp)) { - // Turn this into shuffle(EIOp0, VecOp, Mask). The result has all of - // the values of VecOp, except then one read from EIOp0. - // Build a new shuffle mask. - std::vector Mask; - if (isa(VecOp)) - Mask.assign(NumVectorElts, UndefValue::get(Type::getInt32Ty(*Context))); - else { - assert(isa(VecOp) && "Unknown thing"); - Mask.assign(NumVectorElts, ConstantInt::get(Type::getInt32Ty(*Context), - NumVectorElts)); - } - Mask[InsertedIdx] = - ConstantInt::get(Type::getInt32Ty(*Context), ExtractedIdx); - return new ShuffleVectorInst(EI->getOperand(0), VecOp, - ConstantVector::get(Mask)); - } - // If this insertelement isn't used by some other insertelement, turn it // (and any insertelements it points to), into one big shuffle. if (!IE.hasOneUse() || !isa(IE.use_back())) {