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[GlobalISel](NFC) Refactor construction of LLTs in LegalizerHelper #170664

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Merged
cofibrant merged 1 commit into from
Dec 15, 2025
+37 −28
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[GlobalISel](NFC) Refactor construction of LLTs in LegalizerHelper #170664

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16 changes: 15 additions & 1 deletion llvm/include/llvm/CodeGenTypes/LowLevelType.h
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Original file line number Diff line number Diff line change
Expand Up @@ -207,10 +207,16 @@ class LLT {
return isVector() ? getElementType() : *this;
}

/// Returns a vector with the same number of elements but the new element
/// type. Must only be called on vector types.
constexpr LLT changeVectorElementType(LLT NewEltTy) const {
return LLT::vector(getElementCount(), NewEltTy);
}

/// If this type is a vector, return a vector with the same number of elements
/// but the new element type. Otherwise, return the new element type.
constexpr LLT changeElementType(LLT NewEltTy) const {
return isVector() ? LLT::vector(getElementCount(), NewEltTy) : NewEltTy;
return isVector() ? changeVectorElementType(NewEltTy) : NewEltTy;
}

/// If this type is a vector, return a vector with the same number of elements
Expand All @@ -223,6 +229,14 @@ class LLT {
: LLT::scalar(NewEltSize);
}

/// Return a vector with the same element type and the new element count. Must
/// be called on vector types.
constexpr LLT changeVectorElementCount(ElementCount EC) const {
assert(isVector() &&
"cannot change vector element count of non-vector type");
return LLT::vector(EC, getElementType());
}

/// Return a vector or scalar with the same element type and the new element
/// count.
constexpr LLT changeElementCount(ElementCount EC) const {
Expand Down
49 changes: 22 additions & 27 deletions llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -70,9 +70,8 @@ getNarrowTypeBreakDown(LLT OrigTy, LLT NarrowTy, LLT &LeftoverTy) {
unsigned EltSize = OrigTy.getScalarSizeInBits();
if (LeftoverSize % EltSize != 0)
return {-1, -1};
LeftoverTy =
LLT::scalarOrVector(ElementCount::getFixed(LeftoverSize / EltSize),
OrigTy.getElementType());
LeftoverTy = OrigTy.changeElementCount(
ElementCount::getFixed(LeftoverSize / EltSize));
} else {
LeftoverTy = LLT::scalar(LeftoverSize);
}
Expand Down Expand Up @@ -1558,10 +1557,7 @@ LegalizerHelper::LegalizeResult LegalizerHelper::narrowScalar(MachineInstr &MI,
// combines not being hit). This seems to be a problem related to the
// artifact combiner.
if (SizeOp0 % NarrowSize != 0) {
LLT ImplicitTy = NarrowTy;
if (DstTy.isVector())
ImplicitTy = LLT::vector(DstTy.getElementCount(), ImplicitTy);

LLT ImplicitTy = DstTy.changeElementType(NarrowTy);
Register ImplicitReg = MIRBuilder.buildUndef(ImplicitTy).getReg(0);
MIRBuilder.buildAnyExt(DstReg, ImplicitReg);

Expand Down Expand Up @@ -3289,7 +3285,8 @@ LegalizerHelper::widenScalar(MachineInstr &MI, unsigned TypeIdx, LLT WideTy) {
Observer.changingInstr(MI);

widenScalarSrc(
MI, LLT::vector(VecTy.getElementCount(), WideTy.getSizeInBits()), 1,
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@arsenm arsenm Dec 4, 2025

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The cases directly using LLT::vector/fixed_vector are slightly different, since this doesn't handle scalar inputs which are presumed impossible. This is a direct replacement for the scalarOrVector cases

MI,
VecTy.changeVectorElementType(LLT::scalar(WideTy.getSizeInBits())), 1,
TargetOpcode::G_ANYEXT);

widenScalarDst(MI, WideTy, 0);
Expand Down Expand Up @@ -3321,7 +3318,7 @@ LegalizerHelper::widenScalar(MachineInstr &MI, unsigned TypeIdx, LLT WideTy) {

Register VecReg = MI.getOperand(1).getReg();
LLT VecTy = MRI.getType(VecReg);
LLT WideVecTy = LLT::vector(VecTy.getElementCount(), WideTy);
LLT WideVecTy = VecTy.changeVectorElementType(WideTy);

widenScalarSrc(MI, WideVecTy, 1, TargetOpcode::G_ANYEXT);
widenScalarSrc(MI, WideTy, 2, TargetOpcode::G_ANYEXT);
Expand Down Expand Up @@ -3522,9 +3519,7 @@ LegalizerHelper::widenScalar(MachineInstr &MI, unsigned TypeIdx, LLT WideTy) {
Observer.changingInstr(MI);
Register VecReg = MI.getOperand(1).getReg();
LLT VecTy = MRI.getType(VecReg);
LLT WideVecTy = VecTy.isVector()
? LLT::vector(VecTy.getElementCount(), WideTy)
: WideTy;
LLT WideVecTy = VecTy.changeElementType(WideTy);
widenScalarSrc(MI, WideVecTy, 1, TargetOpcode::G_FPEXT);
widenScalarDst(MI, WideTy, 0, TargetOpcode::G_FPTRUNC);
Observer.changedInstr(MI);
Expand Down Expand Up @@ -3658,7 +3653,8 @@ LegalizerHelper::lowerBitcast(MachineInstr &MI) {
// %3:_(<2 x s8>) = G_BITCAST %2
// %4:_(<2 x s8>) = G_BITCAST %3
// %1:_(<4 x s16>) = G_CONCAT_VECTORS %3, %4
DstCastTy = LLT::fixed_vector(NumDstElt / NumSrcElt, DstEltTy);
DstCastTy = DstTy.changeVectorElementCount(
ElementCount::getFixed(NumDstElt / NumSrcElt));
SrcPartTy = SrcEltTy;
} else if (NumSrcElt > NumDstElt) { // Source element type is smaller.
//
Expand All @@ -3670,7 +3666,8 @@ LegalizerHelper::lowerBitcast(MachineInstr &MI) {
// %3:_(s16) = G_BITCAST %2
// %4:_(s16) = G_BITCAST %3
// %1:_(<2 x s16>) = G_BUILD_VECTOR %3, %4
SrcPartTy = LLT::fixed_vector(NumSrcElt / NumDstElt, SrcEltTy);
SrcPartTy = SrcTy.changeVectorElementCount(
ElementCount::getFixed(NumSrcElt / NumDstElt));
DstCastTy = DstEltTy;
}

Expand Down Expand Up @@ -3736,7 +3733,7 @@ LegalizerHelper::bitcastExtractVectorElt(MachineInstr &MI, unsigned TypeIdx,
unsigned NewNumElts = CastTy.isVector() ? CastTy.getNumElements() : 1;
unsigned OldNumElts = SrcVecTy.getNumElements();

LLT NewEltTy = CastTy.isVector() ? CastTy.getElementType() : CastTy;
LLT NewEltTy = CastTy.getScalarType();
Register CastVec = MIRBuilder.buildBitcast(CastTy, SrcVec).getReg(0);

const unsigned NewEltSize = NewEltTy.getSizeInBits();
Expand All @@ -3758,7 +3755,7 @@ LegalizerHelper::bitcastExtractVectorElt(MachineInstr &MI, unsigned TypeIdx,
// Type of the intermediate result vector.
const unsigned NewEltsPerOldElt = NewNumElts / OldNumElts;
LLT MidTy =
LLT::scalarOrVector(ElementCount::getFixed(NewEltsPerOldElt), NewEltTy);
CastTy.changeElementCount(ElementCount::getFixed(NewEltsPerOldElt));

auto NewEltsPerOldEltK = MIRBuilder.buildConstant(IdxTy, NewEltsPerOldElt);

Expand Down Expand Up @@ -4231,8 +4228,8 @@ LegalizerHelper::LegalizeResult LegalizerHelper::lowerLoad(GAnyLoad &LoadMI) {
// the size of the load without needing to scalarize it.
if (Alignment.value() * 8 > MemSizeInBits &&
isPowerOf2_64(DstTy.getScalarSizeInBits())) {
LLT MoreTy = LLT::fixed_vector(NextPowerOf2(DstTy.getNumElements()),
DstTy.getElementType());
LLT MoreTy = DstTy.changeVectorElementCount(
ElementCount::getFixed(NextPowerOf2(DstTy.getNumElements())));
MachineMemOperand *NewMMO = MF.getMachineMemOperand(&MMO, 0, MoreTy);
auto NewLoad = MIRBuilder.buildLoad(MoreTy, PtrReg, *NewMMO);
MIRBuilder.buildDeleteTrailingVectorElements(LoadMI.getReg(0),
Expand Down Expand Up @@ -5023,8 +5020,7 @@ static void makeDstOps(SmallVectorImpl<DstOp> &DstOps, LLT Ty,
unsigned NumElts) {
LLT LeftoverTy;
assert(Ty.isVector() && "Expected vector type");
LLT EltTy = Ty.getElementType();
LLT NarrowTy = (NumElts == 1) ? EltTy : LLT::fixed_vector(NumElts, EltTy);
LLT NarrowTy = Ty.changeElementCount(ElementCount::getFixed(NumElts));
int NumParts, NumLeftover;
std::tie(NumParts, NumLeftover) =
getNarrowTypeBreakDown(Ty, NarrowTy, LeftoverTy);
Expand Down Expand Up @@ -5705,7 +5701,8 @@ LegalizerHelper::fewerElementsBitcast(MachineInstr &MI, unsigned int TypeIdx,
auto Unmerge = MIRBuilder.buildUnmerge(SrcNarrowTy, SrcReg);
getUnmergeResults(SrcVRegs, *Unmerge);
} else {
LLT SrcNarrowTy = LLT::fixed_vector(NewElemCount, SrcTy.getElementType());
LLT SrcNarrowTy =
SrcTy.changeVectorElementCount(ElementCount::getFixed(NewElemCount));

// Split the Src and Dst Reg into smaller registers
if (extractGCDType(SrcVRegs, DstTy, SrcNarrowTy, SrcReg) != SrcNarrowTy)
Expand Down Expand Up @@ -6837,8 +6834,7 @@ LegalizerHelper::moreElementsVector(MachineInstr &MI, unsigned TypeIdx,
Observer.changingInstr(MI);
moreElementsVectorSrc(MI, MoreTy, 2);
moreElementsVectorSrc(MI, MoreTy, 3);
LLT CondTy = LLT::fixed_vector(
MoreTy.getNumElements(),
LLT CondTy = MoreTy.changeVectorElementType(
MRI.getType(MI.getOperand(0).getReg()).getElementType());
moreElementsVectorDst(MI, CondTy, 0);
Observer.changedInstr(MI);
Expand Down Expand Up @@ -6930,7 +6926,8 @@ LegalizerHelper::equalizeVectorShuffleLengths(MachineInstr &MI) {

unsigned PaddedMaskNumElts = alignTo(MaskNumElts, SrcNumElts);
unsigned NumConcat = PaddedMaskNumElts / SrcNumElts;
LLT PaddedTy = LLT::fixed_vector(PaddedMaskNumElts, DestEltTy);
LLT PaddedTy =
DstTy.changeVectorElementCount(ElementCount::getFixed(PaddedMaskNumElts));

// Create new source vectors by concatenating the initial
// source vectors with undefined vectors of the same size.
Expand Down Expand Up @@ -9894,9 +9891,7 @@ LegalizerHelper::lowerISFPCLASS(MachineInstr &MI) {
unsigned BitSize = SrcTy.getScalarSizeInBits();
const fltSemantics &Semantics = getFltSemanticForLLT(SrcTy.getScalarType());

LLT IntTy = LLT::scalar(BitSize);
if (SrcTy.isVector())
IntTy = LLT::vector(SrcTy.getElementCount(), IntTy);
LLT IntTy = SrcTy.changeElementType(LLT::scalar(BitSize));
auto AsInt = MIRBuilder.buildCopy(IntTy, SrcReg);

// Various masks.
Expand Down