From 04fcbf954fef6d9866b5120f406e7401dc9aa29f Mon Sep 17 00:00:00 2001 From: Eric Christopher Date: Fri, 1 Oct 2010 09:02:05 +0000 Subject: [PATCH] Fix the other half of the alignment changing issue by making sure that the memcpy alignment is the minimum of the incoming alignments. Fixes PR 8266. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115305 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/MemCpyOptimizer.cpp | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/lib/Transforms/Scalar/MemCpyOptimizer.cpp b/lib/Transforms/Scalar/MemCpyOptimizer.cpp index f94c9e22576..4172b345c61 100644 --- a/lib/Transforms/Scalar/MemCpyOptimizer.cpp +++ b/lib/Transforms/Scalar/MemCpyOptimizer.cpp @@ -697,13 +697,18 @@ bool MemCpyOpt::processMemCpy(MemCpyInst *M) { M->getParent()->getParent()->getParent(), M->getIntrinsicID(), ArgTys, 3); - // Make sure to use the alignment of the source since we're changing the - // location we're reading from. + // Make sure to use the lesser of the alignment of the source and the dest + // since we're changing where we're reading from, but don't want to increase + // the alignment past what can be read from or written to. // TODO: Is this worth it if we're creating a less aligned memcpy? For // example we could be moving from movaps -> movq on x86. + unsigned Align = std::min(MDep->getAlignmentCst()->getZExtValue(), + M->getAlignmentCst()->getZExtValue()); + LLVMContext &Context = M->getContext(); + ConstantInt *AlignCI = ConstantInt::get(Type::getInt32Ty(Context), Align); Value *Args[5] = { M->getRawDest(), MDep->getRawSource(), M->getLength(), - MDep->getAlignmentCst(), M->getVolatileCst() + AlignCI, M->getVolatileCst() }; CallInst *C = CallInst::Create(MemCpyFun, Args, Args+5, "", M); -- 2.34.1