[PATCH] Added InstCombine transform for pattern "(A & B) | ((~A) ^ B) -> (~A ^ B)"

[suyog]

Hi dexonsmith, nicholas, rafael, silvas,

This patch implements transform for pattern "(A & B) | ((~A) ^ B) -> (~A ^ B)"

Please help in reviewing the same.

Z3 link : http://www.rise4fun.com/Z3/FslAug

Thanks,
Suyog

http://reviews.llvm.org/D4655

Files:
  lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
  test/Transforms/InstCombine/or.ll

Index: lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -2143,6 +2143,16 @@
         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);
 
Index: test/Transforms/InstCombine/or.ll
===================================================================
--- test/Transforms/InstCombine/or.ll
+++ test/Transforms/InstCombine/or.ll
@@ -427,3 +427,25 @@
  %or = or i32 %and, %xor
  ret i32 %or
 }
+
+define i32 @test43(i32 %a, i32 %b) {
+; CHECK-LABEL: test43(
+; 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 @test44(i32 %a, i32 %b) {
+; CHECK-LABEL: test44(
+; 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
+}
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