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DAG: Use flags in isLegalToCombineMinNumMaxNum #93555

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merged 2 commits into from
May 28, 2024
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DAG: Use flags in isLegalToCombineMinNumMaxNum #93555

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97073de
AMDGPU: Add baseline test for fcmp+select with flags to min/max
arsenm May 28, 2024
70dd1c3
DAG: Use flags in isLegalToCombineMinNumMaxNum
arsenm May 28, 2024
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19 changes: 11 additions & 8 deletions llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -11186,17 +11186,19 @@ SDValue DAGCombiner::visitCTPOP(SDNode *N) {
return SDValue();
}

// FIXME: This should be checking for no signed zeros on individual operands, as
// well as no nans.
static bool isLegalToCombineMinNumMaxNum(SelectionDAG &DAG, SDValue LHS,
SDValue RHS,
SDValue RHS, const SDNodeFlags Flags,
const TargetLowering &TLI) {
const TargetOptions &Options = DAG.getTarget().Options;
EVT VT = LHS.getValueType();
if (!VT.isFloatingPoint())
return false;

const TargetOptions &Options = DAG.getTarget().Options;

return Options.NoSignedZerosFPMath && VT.isFloatingPoint() &&
return (Flags.hasNoSignedZeros() || Options.NoSignedZerosFPMath) &&
TLI.isProfitableToCombineMinNumMaxNum(VT) &&
DAG.isKnownNeverNaN(LHS) && DAG.isKnownNeverNaN(RHS);
(Flags.hasNoNaNs() ||
(DAG.isKnownNeverNaN(RHS) && DAG.isKnownNeverNaN(LHS)));
}

static SDValue combineMinNumMaxNumImpl(const SDLoc &DL, EVT VT, SDValue LHS,
Expand Down Expand Up @@ -11674,7 +11676,7 @@ SDValue DAGCombiner::visitSELECT(SDNode *N) {
// select (fcmp gt x, y), x, y -> fmaxnum x, y
//
// This is OK if we don't care what happens if either operand is a NaN.
if (N0.hasOneUse() && isLegalToCombineMinNumMaxNum(DAG, N1, N2, TLI))
if (N0.hasOneUse() && isLegalToCombineMinNumMaxNum(DAG, N1, N2, Flags, TLI))
if (SDValue FMinMax =
combineMinNumMaxNum(DL, VT, Cond0, Cond1, N1, N2, CC))
return FMinMax;
Expand Down Expand Up @@ -12267,7 +12269,8 @@ SDValue DAGCombiner::visitVSELECT(SDNode *N) {
// This is OK if we don't care about what happens if either operand is a
// NaN.
//
if (N0.hasOneUse() && isLegalToCombineMinNumMaxNum(DAG, LHS, RHS, TLI)) {
if (N0.hasOneUse() &&
isLegalToCombineMinNumMaxNum(DAG, LHS, RHS, N->getFlags(), TLI)) {
if (SDValue FMinMax = combineMinNumMaxNum(DL, VT, LHS, RHS, N1, N2, CC))
return FMinMax;
}
Expand Down
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