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[DAG] Cleanup MatchFunnelPosNeg by using SDPatternMatch matchers #129431

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[DAG] Cleanup MatchFunnelPosNeg by using SDPatternMatch matchers #129431

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7 changes: 7 additions & 0 deletions llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -8528,6 +8528,13 @@ SDValue DAGCombiner::MatchFunnelPosNeg(SDValue N0, SDValue N1, SDValue Pos,
return DAG.getNode(ISD::FSHL, DL, VT, N0, N1.getOperand(0), Pos);
}
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@RKSimon RKSimon Mar 2, 2025

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This should be removed entirely


SDValue X1, Y;
if (sd_match(N1, m_Srl(X1, m_SpecificInt(1))) &&
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@RKSimon RKSimon Mar 2, 2025

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X1 -> m_Value(X1)

sd_match(InnerNeg, m_Xor(Y, m_SpecificInt(EltBits - 1))) &&
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@RKSimon RKSimon Mar 2, 2025

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You can remove Y and use m_Specific(InnerPos)

Y == InnerPos && TLI.isOperationLegalOrCustom(ISD::FSHL, VT)) {
return DAG.getNode(ISD::FSHL, DL, VT, N0, N1.getOperand(0), Pos);
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@RKSimon RKSimon Mar 2, 2025

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N1.getOperand(0) -> X1

}

// fold (or (shl (shl x0, 1), (xor y, 31)), (srl x1, y))
// -> (fshr x0, x1, y)
if (IsBinOpImm(N0, ISD::SHL, 1) &&
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