[llvm] r299834 - [InstCombine] Make the (A|B)^B -> A & ~B transform code consistent with the very similar (A&B)^B -> ~A & B code. This should be NFC except for the addition of hasOneUse check.

[Craig Topper via llvm-commits]

Author: ctopper
Date: Mon Apr 10 01:53:21 2017
New Revision: 299834

URL: http://llvm.org/viewvc/llvm-project?rev=299834&view=rev
Log:
[InstCombine] Make the (A|B)^B -> A & ~B transform code consistent with the very similar (A&B)^B -> ~A & B code. This should be NFC except for the addition of hasOneUse check.

I think this code is still overly complicated and should use matchers, but first I wanted to make it consistent.

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=299834&r1=299833&r2=299834&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Mon Apr 10 01:53:21 2017
@@ -2504,12 +2504,12 @@ Instruction *InstCombiner::visitXor(Bina
   BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1);
   if (Op1I) {
     Value *A, *B;
-    if (match(Op1I, m_Or(m_Value(A), m_Value(B)))) {
-      if (A == Op0) {              // B^(B|A) == (A|B)^B
+    if (match(Op1I, m_OneUse(m_Or(m_Value(A), m_Value(B))))) {
+      if (A == Op0) {                                      // A^(A|B) == A^(B|A)
         Op1I->swapOperands();
-        I.swapOperands();
-        std::swap(Op0, Op1);
-      } else if (B == Op0) {       // B^(A|B) == (A|B)^B
+        std::swap(A, B);
+      }
+      if (B == Op0) {                                      // A^(B|A) == (B|A)^A
         I.swapOperands();     // Simplified below.
         std::swap(Op0, Op1);
       }