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[RISCV] Improve fixed vector handling in isCtpopFast. #158380

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Merged
merged 4 commits into from
Sep 16, 2025
Merged

[RISCV] Improve fixed vector handling in isCtpopFast. #158380

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f7f0da9
Pre-commit test
topperc Sep 12, 2025
96b3422
[RISCV] Improve fixed vector handling in isCtpopFast.
topperc Sep 12, 2025
31163fd
fixup! address review comments
topperc Sep 15, 2025
9b913d9
fixup! Address review comment
topperc Sep 16, 2025
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18 changes: 11 additions & 7 deletions llvm/lib/Target/RISCV/RISCVISelLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2752,7 +2752,7 @@ bool RISCVTargetLowering::isLegalElementTypeForRVV(EVT ScalarTy) const {
case MVT::i8:
case MVT::i16:
case MVT::i32:
return true;
return Subtarget.hasVInstructions();
case MVT::i64:
return Subtarget.hasVInstructionsI64();
case MVT::f16:
Expand Down Expand Up @@ -24840,12 +24840,16 @@ bool RISCVTargetLowering::areTwoSDNodeTargetMMOFlagsMergeable(
}

bool RISCVTargetLowering::isCtpopFast(EVT VT) const {
if (VT.isScalableVector())
return isTypeLegal(VT) && Subtarget.hasStdExtZvbb();
if (VT.isFixedLengthVector() && Subtarget.hasStdExtZvbb())
return true;
return Subtarget.hasCPOPLike() &&
(VT == MVT::i32 || VT == MVT::i64 || VT.isFixedLengthVector());
if (VT.isVector()) {
EVT SVT = VT.getVectorElementType();
// If the element type is legal we can use cpop.v if it is enabled.
if (isLegalElementTypeForRVV(SVT))
return Subtarget.hasStdExtZvbb();
// Don't consider it fast if the type needs to be legalized or scalarized.
return false;
}

return Subtarget.hasCPOPLike() && (VT == MVT::i32 || VT == MVT::i64);
}

unsigned RISCVTargetLowering::getCustomCtpopCost(EVT VT,
Expand Down
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