[llvm] r214476 - This patch implements transform for pattern "(A & B) | ((~A) ^ B) -> (~A ^ B)".

[Suyog Sarda]

Author: suyog
Date: Thu Jul 31 23:41:43 2014
New Revision: 214476

URL: http://llvm.org/viewvc/llvm-project?rev=214476&view=rev
Log:
This patch implements transform for pattern "(A & B) | ((~A) ^ B) -> (~A ^ B)".
Patch Credit to Ankit Jain !

Differential Revision: http://reviews.llvm.org/D4655


Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
    llvm/trunk/test/Transforms/InstCombine/or.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=214476&r1=214475&r2=214476&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Thu Jul 31 23:41:43 2014
@@ -2167,6 +2167,16 @@ Instruction *InstCombiner::visitOr(Binar
         return BinaryOperator::CreateOr(Not, Op0);
       }
 
+  // (A & B) | ((~A) ^ B) -> (~A ^ B)
+  if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
+      match(Op1, m_Xor(m_Not(m_Specific(A)), m_Specific(B))))
+    return BinaryOperator::CreateXor(Builder->CreateNot(A), B);
+
+  // ((~A) ^ B) | (A & B) -> (~A ^ B)
+  if (match(Op0, m_Xor(m_Not(m_Value(A)), m_Value(B))) &&
+      match(Op1, m_And(m_Specific(A), m_Specific(B))))
+    return BinaryOperator::CreateXor(Builder->CreateNot(A), B);
+
   if (SwappedForXor)
     std::swap(Op0, Op1);
 

Modified: llvm/trunk/test/Transforms/InstCombine/or.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/or.ll?rev=214476&r1=214475&r2=214476&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/or.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/or.ll Thu Jul 31 23:41:43 2014
@@ -427,3 +427,25 @@ define i32 @test40(i32 %a, i32 %b) {
  %or = or i32 %and, %xor
  ret i32 %or
 }
+
+define i32 @test41(i32 %a, i32 %b) {
+; CHECK-LABEL: test41(
+; CHECK-NEXT: %1 = xor i32 %a, -1
+; CHECK-NEXT: %or = xor i32 %1, %b
+ %and = and i32 %a, %b
+ %nega = xor i32 %a, -1
+ %xor = xor i32 %nega, %b
+ %or = or i32 %and, %xor
+ ret i32 %or
+}
+
+define i32 @test42(i32 %a, i32 %b) {
+; CHECK-LABEL: test42(
+; CHECK-NEXT: %1 = xor i32 %a, -1
+; CHECK-NEXT: %or = xor i32 %1, %b
+ %nega = xor i32 %a, -1
+ %xor = xor i32 %nega, %b
+ %and = and i32 %a, %b
+ %or = or i32 %xor, %and
+ ret i32 %or
+}