InstCombine: (sub (or A B) (xor A B)) --> (and A B)
The following implements the transformation:
(sub (or A B) (xor A B)) --> (and A B).
Patch by Ankur Garg!
Differential Revision: http://reviews.llvm.org/D5719
llvm-svn: 220163
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
index ace7597..ef68752 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -1621,6 +1621,15 @@
return BinaryOperator::CreateNeg(Y);
}
+ // (sub (or A, B) (xor A, B)) --> (and A, B)
+ {
+ Value *A = nullptr, *B = nullptr;
+ if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
+ (match(Op0, m_Or(m_Specific(A), m_Specific(B))) ||
+ match(Op0, m_Or(m_Specific(B), m_Specific(A)))))
+ return BinaryOperator::CreateAnd(A, B);
+ }
+
if (Op1->hasOneUse()) {
Value *X = nullptr, *Y = nullptr, *Z = nullptr;
Constant *C = nullptr;