[PATCH] Instcombine ((A & ~B) ^ (~A & B)) to A ^ B

[Mayur Pandey]

Hi majnemer,

Hi David,
Another small patch implementing ((A & ~B) ^ (~A & B))  -> A ^ B , similar to previous one, but with And condition.
Please review the patch.

Proof:
$ cat t.cvc 
A, B : BITVECTOR(32);
QUERY BVXOR((A & ~B),(~A & B)) = BVXOR(A,B);
$ cvc3 t.cvc 
Valid.

Thanks,
Mayur

http://reviews.llvm.org/D4898

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

Index: test/Transforms/InstCombine/or-xor.ll
===================================================================
--- test/Transforms/InstCombine/or-xor.ll
+++ test/Transforms/InstCombine/or-xor.ll
@@ -147,3 +147,16 @@
 ; CHECK-NEXT: %1 = and i32 %y, %x
 ; CHECK-NEXT: ret i32 %1
 }
+
+; ((x & ~y) ^ (~x & y)) -> x ^ y
+define i32 @test17(i32 %x, i32 %y) {
+  %noty = xor i32 %y, -1
+  %notx = xor i32 %x, -1
+  %and1 = and i32 %x, %noty
+  %and2 = and i32 %notx, %y
+  %xor = xor i32 %and1, %and2
+  ret i32 %xor
+; CHECK-LABEL: @test17(
+; CHECK-NEXT: %xor = xor i32 %x, %y
+; CHECK-NEXT: ret i32 %xor
+}
Index: lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -2508,6 +2508,16 @@
       if ((A == C && B == D) || (A == D && B == C))
         return BinaryOperator::CreateXor(A, B);
     }
+    // (A & ~B) ^ (~A & B) -> A ^ B
+    if (match(Op0I, m_And(m_Value(A), m_Not(m_Value(B)))) &&
+        match(Op1I, m_And(m_Not(m_Specific(A)), m_Specific(B)))) {
+      return BinaryOperator::CreateXor(A, B);
+    }
+    // (~A & B) ^ (A & ~B) -> A ^ B
+    if (match(Op0I, m_And(m_Not(m_Value(A)), m_Value(B))) &&
+        match(Op1I, m_And(m_Specific(A), m_Not(m_Specific(B))))) {
+      return BinaryOperator::CreateXor(A, B);
+    }
     // (A ^ B)^(A | B) -> A & B
     if (match(Op0I, m_Xor(m_Value(A), m_Value(B))) &&
         match(Op1I, m_Or(m_Value(C), m_Value(D)))) {
-------------- next part --------------
A non-text attachment was scrubbed...
Name: D4898.12485.patch
Type: text/x-patch
Size: 1558 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20140814/4c2bac30/attachment.bin>