[llvm] [DAG] Add generic i8 CTPOP lowering using i32 MUL (PR #79989)
Nikita Popov via llvm-commits
llvm-commits at lists.llvm.org
Thu Feb 1 07:20:38 PST 2024
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@@ -8639,6 +8639,24 @@ SDValue TargetLowering::expandCTPOP(SDNode *Node, SelectionDAG &DAG) const {
if (VT.isVector() && !canExpandVectorCTPOP(*this, VT))
return SDValue();
+ // i8 CTPOP - with efficient i32 MUL, then attempt multiply-mask-multiply.
+ if (VT == MVT::i8 && shouldAllowMultiplyInBitCounts(MVT::i8, MVT::i32) &&
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nikic wrote:
Would checking the immediate cost be able to distinguish targets where this is profitable?
https://github.com/llvm/llvm-project/pull/79989
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