From: Craig Topper <craig.topper@gmail.com>
Date: Mon, 10 Apr 2017 06:53:21 +0000 (+0000)
Subject: [InstCombine] Make the (A|B)^B -> A & ~B transform code consistent with the very... 
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=1a4cc6a638b20aeecf51cbed5bad0d278f5bd51c;p=llvm

[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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@299834 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 5b2dbd9d1f3..091c80daef6 100644
--- a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -2504,12 +2504,12 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) {
   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);
       }