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

[suyog]

Hi dexonsmith, nicholas, silvas, rafael,

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/hx7d

Thanks,
Suyog

http://reviews.llvm.org/D4652

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
@@ -1998,6 +1998,16 @@
       match(Op1, m_Not(m_Specific(A))))
     return BinaryOperator::CreateOr(Builder->CreateNot(A), B);
 
+  // ( A & (~B)) | (A ^ B) -> (A ^ B)
+  if (match(Op0, m_And(m_Value(A), m_Not(m_Value(B)))) &&
+      match(Op1, m_Xor(m_Specific(A), m_Specific(B))))
+    return BinaryOperator::CreateXor(A, B);
+
+  // (A ^ B) | ( A & (~B)) -> (A ^ B)
+  if (match(Op0, m_Xor(m_Value(A), m_Value(B))) &&
+      match(Op1, m_And(m_Specific(A), m_Not(m_Specific(B)))))
+    return BinaryOperator::CreateXor(A, B);
+
   // (A & C)|(B & D)
   Value *C = nullptr, *D = nullptr;
   if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
Index: test/Transforms/InstCombine/or.ll
===================================================================
--- test/Transforms/InstCombine/or.ll
+++ test/Transforms/InstCombine/or.ll
@@ -427,3 +427,23 @@
  %or = or i32 %and, %xor
  ret i32 %or
 }
+
+define i32 @test41(i32 %a, i32 %b) {
+; CHECK-LABEL: test41(
+; CHECK-NEXT: %or = xor i32 %a, %b
+  %neg = xor i32 %b, -1
+  %and = and i32 %a, %neg
+  %xor = xor i32 %a, %b
+  %or = or i32 %and, %xor
+  ret i32 %or
+}
+
+define i32 @test42(i32 %a, i32 %b) {
+; CHECK-LABEL: test42(
+; CHECK-NEXT: %or = xor i32 %a, %b  
+  %xor = xor i32 %a, %b
+  %neg = xor i32 %b, -1
+  %and = and i32 %a, %neg
+  %or = or i32 %xor, %and
+  ret i32 %or
+}
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