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[DAG] Early exit for flags in canCreateUndefOrPoison [nfc] #89834

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Merged
merged 3 commits into from
Apr 25, 2024
Merged

[DAG] Early exit for flags in canCreateUndefOrPoison [nfc] #89834

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b500a48
[DAG] Early exit for flags in canCreateUndefOrPoison [nfc]
preames Apr 23, 2024
1ac2049
Only some fastmath flags imply poison
preames Apr 24, 2024
60bd0e1
Remove NoFPExcept and Unpredictable
preames Apr 24, 2024
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7 changes: 7 additions & 0 deletions llvm/include/llvm/CodeGen/SelectionDAGNodes.h
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Original file line number Diff line number Diff line change
Expand Up @@ -999,6 +999,13 @@ END_TWO_BYTE_PACK()
/// If Flags is not in a defined state then this has no effect.
void intersectFlagsWith(const SDNodeFlags Flags);

bool hasPoisonGeneratingFlags() const {
SDNodeFlags Flags = getFlags();
return Flags.hasNoUnsignedWrap() || Flags.hasNoSignedWrap() ||
Flags.hasExact() || Flags.hasDisjoint() || Flags.hasNonNeg() ||
Flags.hasNoNaNs() || Flags.hasNoInfs();
}

void setCFIType(uint32_t Type) { CFIType = Type; }
uint32_t getCFIType() const { return CFIType; }

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27 changes: 8 additions & 19 deletions llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5095,6 +5095,9 @@ bool SelectionDAG::canCreateUndefOrPoison(SDValue Op, const APInt &DemandedElts,
if (VT.isScalableVector())
return true;

if (ConsiderFlags && Op->hasPoisonGeneratingFlags())
return true;

unsigned Opcode = Op.getOpcode();
switch (Opcode) {
case ISD::FREEZE:
Expand Down Expand Up @@ -5134,34 +5137,20 @@ bool SelectionDAG::canCreateUndefOrPoison(SDValue Op, const APInt &DemandedElts,
return true;

const TargetOptions &Options = getTarget().Options;
return Options.NoNaNsFPMath || Options.NoInfsFPMath ||
(ConsiderFlags &&
(Op->getFlags().hasNoNaNs() || Op->getFlags().hasNoInfs()));
return Options.NoNaNsFPMath || Options.NoInfsFPMath;
}

// Matches hasPoisonGeneratingFlags().
case ISD::OR:
case ISD::ZERO_EXTEND:
return ConsiderFlags && Op->getFlags().hasNonNeg();

case ISD::ADD:
case ISD::SUB:
case ISD::MUL:
// Matches hasPoisonGeneratingFlags().
return ConsiderFlags && (Op->getFlags().hasNoSignedWrap() ||
Op->getFlags().hasNoUnsignedWrap());
// No poison except from flags (which is handled above)
return false;

case ISD::SHL:
// If the max shift amount isn't in range, then the shift can create poison.
if (!getValidMaximumShiftAmountConstant(Op, DemandedElts))
return true;

// Matches hasPoisonGeneratingFlags().
return ConsiderFlags && (Op->getFlags().hasNoSignedWrap() ||
Op->getFlags().hasNoUnsignedWrap());

// Matches hasPoisonGeneratingFlags().
case ISD::OR:
return ConsiderFlags && Op->getFlags().hasDisjoint();
return !getValidMaximumShiftAmountConstant(Op, DemandedElts);

case ISD::SCALAR_TO_VECTOR:
// Check if we demand any upper (undef) elements.
Expand Down