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[CodeGen] Remove NoSignedZerosFPMath uses #156147

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[CodeGen] Remove NoSignedZerosFPMath uses #156147

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34 changes: 13 additions & 21 deletions llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -11744,7 +11744,7 @@ static bool isLegalToCombineMinNumMaxNum(SelectionDAG &DAG, SDValue LHS,

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

return (Flags.hasNoSignedZeros() || Options.NoSignedZerosFPMath) &&
return Flags.hasNoSignedZeros() &&
TLI.isProfitableToCombineMinNumMaxNum(VT) &&
(Flags.hasNoNaNs() ||
(DAG.isKnownNeverNaN(RHS) && DAG.isKnownNeverNaN(LHS)));
Expand Down Expand Up @@ -17235,7 +17235,7 @@ SDValue DAGCombiner::visitFSUBForFMACombine(SDNode *N) {
// Always prefer FMAD to FMA for precision.
unsigned PreferredFusedOpcode = HasFMAD ? ISD::FMAD : ISD::FMA;
bool Aggressive = TLI.enableAggressiveFMAFusion(VT);
bool NoSignedZero = Options.NoSignedZerosFPMath || Flags.hasNoSignedZeros();
bool NoSignedZero = Flags.hasNoSignedZeros();

// Is the node an FMUL and contractable either due to global flags or
// SDNodeFlags.
Expand Down Expand Up @@ -17654,7 +17654,7 @@ SDValue DAGCombiner::visitFADD(SDNode *N) {
// N0 + -0.0 --> N0 (also allowed with +0.0 and fast-math)
ConstantFPSDNode *N1C = isConstOrConstSplatFP(N1, true);
if (N1C && N1C->isZero())
if (N1C->isNegative() || Options.NoSignedZerosFPMath || Flags.hasNoSignedZeros())
if (N1C->isNegative() || Flags.hasNoSignedZeros())
return N0;

if (SDValue NewSel = foldBinOpIntoSelect(N))
Expand Down Expand Up @@ -17710,8 +17710,7 @@ SDValue DAGCombiner::visitFADD(SDNode *N) {
// If 'unsafe math' or reassoc and nsz, fold lots of things.
// TODO: break out portions of the transformations below for which Unsafe is
// considered and which do not require both nsz and reassoc
if ((Options.NoSignedZerosFPMath ||
(Flags.hasAllowReassociation() && Flags.hasNoSignedZeros())) &&
if (Flags.hasAllowReassociation() && Flags.hasNoSignedZeros() &&
AllowNewConst) {
// fadd (fadd x, c1), c2 -> fadd x, c1 + c2
if (N1CFP && N0.getOpcode() == ISD::FADD &&
Expand Down Expand Up @@ -17797,8 +17796,7 @@ SDValue DAGCombiner::visitFADD(SDNode *N) {
}
} // enable-unsafe-fp-math && AllowNewConst

if ((Options.NoSignedZerosFPMath ||
(Flags.hasAllowReassociation() && Flags.hasNoSignedZeros()))) {
if (Flags.hasAllowReassociation() && Flags.hasNoSignedZeros()) {
// Fold fadd(vecreduce(x), vecreduce(y)) -> vecreduce(fadd(x, y))
if (SDValue SD = reassociateReduction(ISD::VECREDUCE_FADD, ISD::FADD, DL,
VT, N0, N1, Flags))
Expand Down Expand Up @@ -17869,8 +17867,7 @@ SDValue DAGCombiner::visitFSUB(SDNode *N) {

// (fsub A, 0) -> A
if (N1CFP && N1CFP->isZero()) {
if (!N1CFP->isNegative() || Options.NoSignedZerosFPMath ||
Flags.hasNoSignedZeros()) {
if (!N1CFP->isNegative() || Flags.hasNoSignedZeros()) {
return N0;
}
}
Expand All @@ -17883,8 +17880,7 @@ SDValue DAGCombiner::visitFSUB(SDNode *N) {

// (fsub -0.0, N1) -> -N1
if (N0CFP && N0CFP->isZero()) {
if (N0CFP->isNegative() ||
(Options.NoSignedZerosFPMath || Flags.hasNoSignedZeros())) {
if (N0CFP->isNegative() || Flags.hasNoSignedZeros()) {
// We cannot replace an FSUB(+-0.0,X) with FNEG(X) when denormals are
// flushed to zero, unless all users treat denorms as zero (DAZ).
// FIXME: This transform will change the sign of a NaN and the behavior
Expand All @@ -17900,8 +17896,7 @@ SDValue DAGCombiner::visitFSUB(SDNode *N) {
}
}

if ((Options.NoSignedZerosFPMath ||
(Flags.hasAllowReassociation() && Flags.hasNoSignedZeros())) &&
if (Flags.hasAllowReassociation() && Flags.hasNoSignedZeros() &&
N1.getOpcode() == ISD::FADD) {
// X - (X + Y) -> -Y
if (N0 == N1->getOperand(0))
Expand Down Expand Up @@ -18220,7 +18215,7 @@ template <class MatchContextClass> SDValue DAGCombiner::visitFMA(SDNode *N) {
// TODO: Finally migrate away from global TargetOptions.
if ((Options.NoNaNsFPMath && Options.NoInfsFPMath) ||
(N->getFlags().hasNoNaNs() && N->getFlags().hasNoInfs())) {
if (Options.NoSignedZerosFPMath || N->getFlags().hasNoSignedZeros() ||
if (N->getFlags().hasNoSignedZeros() ||
(N2CFP && !N2CFP->isExactlyValue(-0.0))) {
if (N0CFP && N0CFP->isZero())
return N2;
Expand Down Expand Up @@ -18525,8 +18520,7 @@ SDValue DAGCombiner::visitFDIV(SDNode *N) {
}

// Fold X/Sqrt(X) -> Sqrt(X)
if ((Options.NoSignedZerosFPMath || Flags.hasNoSignedZeros()) &&
Flags.hasAllowReassociation())
if (Flags.hasNoSignedZeros() && Flags.hasAllowReassociation())
if (N1.getOpcode() == ISD::FSQRT && N0 == N1.getOperand(0))
return N1;

Expand Down Expand Up @@ -18753,8 +18747,7 @@ static SDValue foldFPToIntToFP(SDNode *N, const SDLoc &DL, SelectionDAG &DAG,
// FIXME: We should be able to use node-level FMF here.
// TODO: If strict math, should we use FABS (+ range check for signed cast)?
EVT VT = N->getValueType(0);
if (!TLI.isOperationLegal(ISD::FTRUNC, VT) ||
!DAG.getTarget().Options.NoSignedZerosFPMath)
if (!TLI.isOperationLegal(ISD::FTRUNC, VT))
return SDValue();

// fptosi/fptoui round towards zero, so converting from FP to integer and
Expand Down Expand Up @@ -19195,9 +19188,8 @@ SDValue DAGCombiner::visitFNEG(SDNode *N) {
// FIXME: This is duplicated in getNegatibleCost, but getNegatibleCost doesn't
// know it was called from a context with a nsz flag if the input fsub does
// not.
if (N0.getOpcode() == ISD::FSUB &&
(DAG.getTarget().Options.NoSignedZerosFPMath ||
N->getFlags().hasNoSignedZeros()) && N0.hasOneUse()) {
if (N0.getOpcode() == ISD::FSUB && (N->getFlags().hasNoSignedZeros()) &&
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@s-barannikov s-barannikov Aug 30, 2025

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Suggested change
if (N0.getOpcode() == ISD::FSUB && (N->getFlags().hasNoSignedZeros()) &&
if (N0.getOpcode() == ISD::FSUB && N->getFlags().hasNoSignedZeros() &&

N0.hasOneUse()) {
return DAG.getNode(ISD::FSUB, SDLoc(N), VT, N0.getOperand(1),
N0.getOperand(0));
}
Expand Down
10 changes: 5 additions & 5 deletions llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -7581,7 +7581,7 @@ SDValue TargetLowering::getNegatedExpression(SDValue Op, SelectionDAG &DAG,
return DAG.getBuildVector(VT, DL, Ops);
}
case ISD::FADD: {
if (!Options.NoSignedZerosFPMath && !Flags.hasNoSignedZeros())
if (!Flags.hasNoSignedZeros())
break;

// After operation legalization, it might not be legal to create new FSUBs.
Expand Down Expand Up @@ -7626,7 +7626,7 @@ SDValue TargetLowering::getNegatedExpression(SDValue Op, SelectionDAG &DAG,
}
case ISD::FSUB: {
// We can't turn -(A-B) into B-A when we honor signed zeros.
if (!Options.NoSignedZerosFPMath && !Flags.hasNoSignedZeros())
if (!Flags.hasNoSignedZeros())
break;

SDValue X = Op.getOperand(0), Y = Op.getOperand(1);
Expand Down Expand Up @@ -7687,7 +7687,7 @@ SDValue TargetLowering::getNegatedExpression(SDValue Op, SelectionDAG &DAG,
}
case ISD::FMA:
case ISD::FMAD: {
if (!Options.NoSignedZerosFPMath && !Flags.hasNoSignedZeros())
if (!Flags.hasNoSignedZeros())
break;

SDValue X = Op.getOperand(0), Y = Op.getOperand(1), Z = Op.getOperand(2);
Expand Down Expand Up @@ -8865,8 +8865,8 @@ SDValue TargetLowering::expandFMINIMUMNUM_FMAXIMUMNUM(SDNode *Node,
// TODO: We need quiet sNaN if strictfp.

// Fixup signed zero behavior.
if (Options.NoSignedZerosFPMath || Flags.hasNoSignedZeros() ||
DAG.isKnownNeverZeroFloat(LHS) || DAG.isKnownNeverZeroFloat(RHS)) {
if (Flags.hasNoSignedZeros() || DAG.isKnownNeverZeroFloat(LHS) ||
DAG.isKnownNeverZeroFloat(RHS)) {
return MinMax;
}
SDValue TestZero =
Expand Down
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