From a8225083ba7b2368cec0ced232e43dc77d5f6f0a Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Mon, 26 Oct 2009 15:32:57 +0000 Subject: Make LSR's OptimizeShadowIV ignore induction variables with negative strides for now, because it doesn't handle them correctly. This fixes a miscompile of SingleSource/Benchmarks/Misc-C++/ray. This problem was usually hidden because indvars transforms such induction variables into negations of canonical induction variables. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85118 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/LoopStrengthReduce.cpp | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'lib/Transforms/Scalar/LoopStrengthReduce.cpp') diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp index 4c305aae83..e20fb16fb1 100644 --- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp +++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp @@ -2262,6 +2262,10 @@ void LoopStrengthReduce::OptimizeShadowIV(Loop *L) { if (!C) continue; + // Ignore negative constants, as the code below doesn't handle them + // correctly. TODO: Remove this restriction. + if (!C->getValue().isStrictlyPositive()) continue; + /* Add new PHINode. */ PHINode *NewPH = PHINode::Create(DestTy, "IV.S.", PH); -- cgit v1.2.3-70-g09d2