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.

llvm-svn: 137781

1 files changed, 5 insertions, 4 deletions

diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index cfff9c03c83..89e55a46516 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/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))))