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[GlobalIsel] [Utility] [NFC] Added isConstantOrConstantSplatVectorFP to handle float constants. #120935

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Merged
merged 3 commits into from
Dec 26, 2024
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[GlobalIsel] [Utility] [NFC] Added isConstantOrConstantSplatVectorFP to handle float constants. #120935

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a0dbbea
[GlobalIsel] [Utility] [NFC] Added isConstantOrConstantSplatVectorFP …
vg0204 Dec 23, 2024
e207b7a
Added unittest for isConstOrConstSplatVectorFP.
vg0204 Dec 23, 2024
3d5c026
Added g_implicit_def related unittests.
vg0204 Dec 26, 2024
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7 changes: 7 additions & 0 deletions llvm/include/llvm/CodeGen/GlobalISel/Utils.h
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Original file line number Diff line number Diff line change
Expand Up @@ -522,6 +522,13 @@ std::optional<APInt>
isConstantOrConstantSplatVector(MachineInstr &MI,
const MachineRegisterInfo &MRI);

/// Determines if \p MI defines a float constant integer or a splat vector of
/// float constant integers.
/// \returns the float constant or std::nullopt.
std::optional<APFloat>
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@arsenm arsenm Dec 23, 2024

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I thought we had switched the integer versions over to using ConstantInt* to avoid temporary copies of APInt, but I see the integer version above isn't doing that. We can change the pair as a set later

isConstantOrConstantSplatVectorFP(MachineInstr &MI,
const MachineRegisterInfo &MRI);

/// Attempt to match a unary predicate against a scalar/splat constant or every
/// element of a constant G_BUILD_VECTOR. If \p ConstVal is null, the source
/// value was undef.
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12 changes: 12 additions & 0 deletions llvm/lib/CodeGen/GlobalISel/Utils.cpp
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Expand Up @@ -1517,6 +1517,18 @@ llvm::isConstantOrConstantSplatVector(MachineInstr &MI,
return APInt(ScalarSize, *MaybeCst, true);
}

std::optional<APFloat>
llvm::isConstantOrConstantSplatVectorFP(MachineInstr &MI,
const MachineRegisterInfo &MRI) {
Register Def = MI.getOperand(0).getReg();
if (auto FpConst = getFConstantVRegValWithLookThrough(Def, MRI))
return FpConst->Value;
auto MaybeCstFP = getFConstantSplat(Def, MRI, /*allowUndef=*/false);
if (!MaybeCstFP)
return std::nullopt;
return MaybeCstFP->Value;
}

bool llvm::isNullOrNullSplat(const MachineInstr &MI,
const MachineRegisterInfo &MRI, bool AllowUndefs) {
switch (MI.getOpcode()) {
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