[InstCombine] Fold sub (or A, B) (and A, B) to (xor A, B)
Summary:
```
Name: sub or and to xor
%or = or i32 %y, %x
%and = and i32 %x, %y
%sub = sub i32 %or, %and
=>
%sub = xor i32 %x, %y
Optimization: sub or and to xor
Done: 1
Optimization is correct!
```
https://rise4fun.com/Alive/eJu
Reviewers: spatel, lebedev.ri
Reviewed By: lebedev.ri
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67153
llvm-svn: 370883
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
index 36a7766..776bef3 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -1717,6 +1717,14 @@
return BinaryOperator::CreateNeg(Y);
}
+ // (sub (or A, B) (and A, B)) --> (xor A, B)
+ {
+ Value *A, *B;
+ if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
+ match(Op0, m_c_Or(m_Specific(A), m_Specific(B))))
+ return BinaryOperator::CreateXor(A, B);
+ }
+
// (sub (or A, B), (xor A, B)) --> (and A, B)
{
Value *A, *B;