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

[suyog]

Hi nicholas, rafael, dexonsmith,

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

Please help in reviewing this patch.

http://reviews.llvm.org/D4591

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

Index: test/Transforms/InstCombine/or.ll
===================================================================
--- test/Transforms/InstCombine/or.ll
+++ test/Transforms/InstCombine/or.ll
@@ -408,3 +408,12 @@
   %or = or i32 %x, %sext
   ret i32 %or
 }
+
+define i32 @test39(i32 %a, i32 %b) {
+; CHECK-LABEL: test39(
+; CHECK-NEXT: %or = or i32 %a, %b
+  %xor = xor i32 %a, -1
+  %and = and i32 %xor, %b
+  %or = or i32 %and, %a
+  ret i32 %or
+}
Index: lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -1988,6 +1988,11 @@
     return BinaryOperator::CreateXor(NOr, C1);
   }
 
+  // ((~A & B) | A) -> (A | B)
+  if (match(Op0, m_And(m_Not(m_Value(A)), m_Value(B))) &&
+      match(Op1, m_Specific(A)))
+    return BinaryOperator::CreateOr(A, B);
+
   // (A & C)|(B & D)
   Value *C = nullptr, *D = nullptr;
   if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
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