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InstCombine: (sub (or A B) (xor A B)) --> (and A B)

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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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220163 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Majnemer
2014-10-19 08:32:32 +00:00
parent 242aeb9d84
commit 0fd4e2e5a1
2 changed files with 19 additions and 0 deletions
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lib/Transforms/InstCombine/InstCombineAddSub.cpp
+9
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@@ -1621,6 +1621,15 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
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;