[llvm] [InstCombine] Extend `(lshr/shl (shl/lshr -1, x), x)` -> `(lshr/shl -1, x)` for multi-use (PR #81576)
Nikita Popov via llvm-commits
llvm-commits at lists.llvm.org
Tue Feb 13 09:24:21 PST 2024
================
@@ -1206,6 +1206,12 @@ Instruction *InstCombinerImpl::visitShl(BinaryOperator &I) {
return BinaryOperator::CreateAnd(Mask, X);
}
+ // Transform (-1 >> y) << y to -1 << y
+ if (match(Op0, m_LShr(m_AllOnes(), m_Specific(Op1)))) {
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nikic wrote:
Oh duh, you're right.
https://github.com/llvm/llvm-project/pull/81576
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