From 207634263c6a5271d6a10f802c4970ffcd34d271 Mon Sep 17 00:00:00 2001 From: Eli Friedman Date: Tue, 16 Aug 2011 22:38:34 +0000 Subject: [PATCH] Extend the undef ^ undef idiom once more. No testcase: I can't figure out how to actually trigger the codepath in question at the moment, but it might get exposed in the future. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@137781 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Analysis/InstructionSimplify.cpp | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp index cfff9c03c83..89e55a46516 100644 --- a/lib/Analysis/InstructionSimplify.cpp +++ b/lib/Analysis/InstructionSimplify.cpp @@ -1348,6 +1348,11 @@ static Value *SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD, std::swap(Op0, Op1); } + // A ^ A = 0 + // Do this first so that we catch the undef ^ undef "idiom". + if (Op0 == Op1) + return Constant::getNullValue(Op0->getType()); + // A ^ undef -> undef if (match(Op1, m_Undef())) return Op1; @@ -1356,10 +1361,6 @@ static Value *SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD, if (match(Op1, m_Zero())) return Op0; - // A ^ A = 0 - if (Op0 == Op1) - return Constant::getNullValue(Op0->getType()); - // A ^ ~A = ~A ^ A = -1 if (match(Op0, m_Not(m_Specific(Op1))) || match(Op1, m_Not(m_Specific(Op0))))