From dd3cea898fe27110ffa948792854c47f9138b8f6 Mon Sep 17 00:00:00 2001 From: Chandler Carruth Date: Fri, 14 Sep 2012 10:30:40 +0000 Subject: [PATCH] Add some comments clarifying that the GEP analysis for vector GEPs is deeply suspicious and likely to go away eventually. Also fix a bogus comment about one of the checks in the vector GEP analysis. Based on review from Duncan. llvm-svn: 163894 --- llvm/lib/Transforms/Scalar/SROA.cpp | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/llvm/lib/Transforms/Scalar/SROA.cpp b/llvm/lib/Transforms/Scalar/SROA.cpp index acfa87a32ebf..97c28d442ad3 100644 --- a/llvm/lib/Transforms/Scalar/SROA.cpp +++ b/llvm/lib/Transforms/Scalar/SROA.cpp @@ -1300,10 +1300,13 @@ static Value *getNaturalGEPRecursively(IRBuilder<> &IRB, const TargetData &TD, if (Ty->isPointerTy()) return 0; + // We try to analyze GEPs over vectors here, but note that these GEPs are + // extremely poorly defined currently. The long-term goal is to remove GEPing + // over a vector from the IR completely. if (VectorType *VecTy = dyn_cast(Ty)) { unsigned ElementSizeInBits = VecTy->getScalarSizeInBits(); if (ElementSizeInBits % 8) - return 0; // GEPs over multiple of 8 size vector elements are invalid. + return 0; // GEPs over non-multiple of 8 size vector elements are invalid. APInt ElementSize(Offset.getBitWidth(), ElementSizeInBits / 8); APInt NumSkippedElements = Offset.udiv(ElementSize); if (NumSkippedElements.ugt(VecTy->getNumElements()))