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

[suyog]

Summary

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

[suyog]

Gentle Ping !!

Patch won't take much time to review :)

[majnemer]

LGTM with review comments addressed.

lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

2001 ↗

(On Diff #11835)

Please format this like so:

// (A & (~B)) | (A ^ B) -> (A ^ B)

[suyog]

Closed by commit rL214477 (authored by @suyog).

llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

if (match(Op0, m_And(m_Not(m_Value(A)), m_Value(B))) &&
       match(Op1, m_Specific(A)))
     return BinaryOperator::CreateOr(A, B);
 
   // ((A & B) | ~A) -> (~A | B)
   if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
       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))) &&
       match(Op1, m_And(m_Value(B), m_Value(D)))) {
     Value *V1 = nullptr, *V2 = nullptr;
     C1 = dyn_cast<ConstantInt>(C);
     C2 = dyn_cast<ConstantInt>(D);
     if (C1 && C2) {  // (A & C1)|(B & C2)

llvm/trunk/test/Transforms/InstCombine/or.ll

 ; CHECK-NEXT: %1 = xor i32 %a, -1
 ; CHECK-NEXT: %or = xor i32 %1, %b
  %nega = xor i32 %a, -1
  %xor = xor i32 %nega, %b
  %and = and i32 %a, %b
  %or = or i32 %xor, %and
  ret i32 %or
 }
+
+define i32 @test43(i32 %a, i32 %b) {
+; CHECK-LABEL: test43(
+; 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 @test44(i32 %a, i32 %b) {
+; CHECK-LABEL: test44(
+; 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
+}