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

[sonam kumari]

Hi nicholas, rafael, silvas, dexonsmith,

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

Please help in reviewing the same.

Thanks,
Sonam.

http://reviews.llvm.org/D4691

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
@@ -1279,7 +1279,8 @@
       return BinaryOperator::CreateAnd(A, Op1);
     if (match(Op1, m_Or(m_Not(m_Specific(Op0)), m_Value(A))) ||
         match(Op1, m_Or(m_Value(A), m_Not(m_Specific(Op0)))))
-      return BinaryOperator::CreateAnd(A, Op0);
+        return BinaryOperator::CreateAnd(A, Op0);
+
   }
 
   if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1))
@@ -1982,6 +1983,11 @@
     return BinaryOperator::CreateXor(NOr, C1);
   }
 
+  // (A^B) | (~(A)^B) -> 1
+    if(match(Op0,m_Xor(m_Value(A),m_Value(B)))
+            && match(Op1,m_Xor(m_Not(m_Specific(A)),m_Specific(B))))
+        return BinaryOperator::CreateOr(A, Builder->CreateNot(A));
+
   // (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
@@ -408,3 +408,13 @@
   %or = or i32 %x, %sext
   ret i32 %or
 }
+
+define i32 @test39(i32%x,i32%y){
+; CHECK-LABEL: @test39(
+; CHECK-NEXT: ret i32 -1
+%xor = xor i32%x,%y
+%nega = xor i32%x,-1
+%xor1 = xor i32%nega,%y
+%or = or i32%xor,%xor1
+ret i32 %or
+}
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