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

[sonam kumari]

Hi Majnemer,

Thanks for your valuable review comments.
I have made the changes as you mentioned.
Please help in reviewing the patch.

Thanks,
Sonam.

http://reviews.llvm.org/D4691

Files:
  lib/Analysis/InstructionSimplify.cpp
  test/Transforms/InstSimplify/AndOrXor.ll

Index: lib/Analysis/InstructionSimplify.cpp
===================================================================
--- lib/Analysis/InstructionSimplify.cpp
+++ lib/Analysis/InstructionSimplify.cpp
@@ -1603,6 +1603,11 @@
       (A == Op0 || B == Op0))
     return Constant::getAllOnesValue(Op0->getType());
 
+  // (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 Constant::getAllOnesValue(Op0->getType());
+
   // Try some generic simplifications for associative operations.
   if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q,
                                           MaxRecurse))
Index: test/Transforms/InstSimplify/AndOrXor.ll
===================================================================
--- test/Transforms/InstSimplify/AndOrXor.ll
+++ test/Transforms/InstSimplify/AndOrXor.ll
@@ -20,3 +20,13 @@
   ret i64 %e2
 ; CHECK: ret i64 %e
 }
+
+define i32 @test(i32 %x, i32 %y) {
+  ; CHECK-LABEL: @test39(
+  %xor = xor i32 %x, %y
+  %nega = xor i32 %x, -1
+  %xor1 = xor i32 %nega, %y
+  %or = or i32 %xor, %xor1
+  ret i32 %or
+; CHECK: ret i32 -1
+}
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