[llvm-commits] [llvm] r137781 - /llvm/trunk/lib/Analysis/InstructionSimplify.cpp

[Eli Friedman]

Author: efriedma
Date: Tue Aug 16 17:38:34 2011
New Revision: 137781

URL: http://llvm.org/viewvc/llvm-project?rev=137781&view=rev
Log:
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.


Modified:
    llvm/trunk/lib/Analysis/InstructionSimplify.cpp

Modified: llvm/trunk/lib/Analysis/InstructionSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/InstructionSimplify.cpp?rev=137781&r1=137780&r2=137781&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/InstructionSimplify.cpp (original)
+++ llvm/trunk/lib/Analysis/InstructionSimplify.cpp Tue Aug 16 17:38:34 2011
@@ -1348,6 +1348,11 @@
     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 @@
   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))))