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[SLP][REVEC] Add getScalarizationOverhead helper function to reduce error when REVEC is enabled. #128530

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Merged
merged 5 commits into from
Feb 25, 2025
Merged

[SLP][REVEC] Add getScalarizationOverhead helper function to reduce error when REVEC is enabled. #128530

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9786add
[SLP][REVEC] Add getScalarizationOverhead helper function to reduce
HanKuanChen Feb 24, 2025
26fe00a
[SLP][REVEC] Use getScalarizationOverhead.
HanKuanChen Feb 24, 2025
cb8acd6
add assert to prevent incorrect usage
HanKuanChen Feb 24, 2025
91c156b
use VF to instead of VecTy->getNumElements()
HanKuanChen Feb 24, 2025
ba93ce0
use general getScalarizationOverhead
HanKuanChen Feb 25, 2025
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166 changes: 81 additions & 85 deletions llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5014,6 +5014,42 @@ getShuffleCost(const TargetTransformInfo &TTI, TTI::ShuffleKind Kind,
return TTI.getShuffleCost(Kind, Tp, Mask, CostKind, Index, SubTp, Args);
}

/// This is similar to TargetTransformInfo::getScalarizationOverhead, but if
/// ScalarTy is a FixedVectorType, a vector will be inserted or extracted
/// instead of a scalar.
static InstructionCost getScalarizationOverhead(const TargetTransformInfo &TTI,
Type *ScalarTy, VectorType *Ty,
const APInt &DemandedElts,
bool Insert, bool Extract,
TTI::TargetCostKind CostKind,
ArrayRef<Value *> VL = {}) {
assert(!isa<ScalableVectorType>(Ty) &&
"ScalableVectorType is not supported.");
assert(getNumElements(ScalarTy) * DemandedElts.getBitWidth() ==
getNumElements(Ty) &&
"Incorrect usage.");
if (auto *VecTy = dyn_cast<FixedVectorType>(ScalarTy)) {
assert(SLPReVec && "Only supported by REVEC.");
// If ScalarTy is FixedVectorType, we should use CreateInsertVector instead
// of CreateInsertElement.
unsigned ScalarTyNumElements = VecTy->getNumElements();
InstructionCost Cost = 0;
for (unsigned I : seq(DemandedElts.getBitWidth())) {
if (!DemandedElts[I])
continue;
if (Insert)
Cost += getShuffleCost(TTI, TTI::SK_InsertSubvector, Ty, {}, CostKind,
I * ScalarTyNumElements, VecTy);
if (Extract)
Cost += getShuffleCost(TTI, TTI::SK_ExtractSubvector, Ty, {}, CostKind,
I * ScalarTyNumElements, VecTy);
}
return Cost;
}
return TTI.getScalarizationOverhead(Ty, DemandedElts, Insert, Extract,
CostKind, VL);
}

/// Correctly creates insert_subvector, checking that the index is multiple of
/// the subvectors length. Otherwise, generates shuffle using \p Generator or
/// using default shuffle.
Expand Down Expand Up @@ -5207,22 +5243,22 @@ BoUpSLP::canVectorizeLoads(ArrayRef<Value *> VL, const Value *VL0,
Instruction::GetElementPtr, CostKind, ScalarTy, VecTy);
// Estimate the cost of masked gather GEP. If not a splat, roughly
// estimate as a buildvector, otherwise estimate as splat.
APInt DemandedElts = APInt::getAllOnes(VecTy->getNumElements());
VectorType *PtrVecTy =
getWidenedType(PointerOps.front()->getType()->getScalarType(),
VecTy->getNumElements());
APInt DemandedElts = APInt::getAllOnes(Sz);
Type *PtrScalarTy = PointerOps.front()->getType()->getScalarType();
VectorType *PtrVecTy = getWidenedType(PtrScalarTy, Sz);
if (static_cast<unsigned>(count_if(
PointerOps, IsaPred<GetElementPtrInst>)) < PointerOps.size() - 1 ||
any_of(PointerOps, [&](Value *V) {
return getUnderlyingObject(V) !=
getUnderlyingObject(PointerOps.front());
}))
VectorGEPCost += TTI.getScalarizationOverhead(
PtrVecTy, DemandedElts, /*Insert=*/true, /*Extract=*/false, CostKind);
VectorGEPCost += getScalarizationOverhead(TTI, PtrScalarTy, PtrVecTy,
DemandedElts, /*Insert=*/true,
/*Extract=*/false, CostKind);
else
VectorGEPCost +=
TTI.getScalarizationOverhead(
PtrVecTy, APInt::getOneBitSet(VecTy->getNumElements(), 0),
getScalarizationOverhead(
TTI, PtrScalarTy, PtrVecTy, APInt::getOneBitSet(Sz, 0),
/*Insert=*/true, /*Extract=*/false, CostKind) +
::getShuffleCost(TTI, TTI::SK_Broadcast, PtrVecTy, {}, CostKind);
// The cost of scalar loads.
Expand All @@ -5240,8 +5276,9 @@ BoUpSLP::canVectorizeLoads(ArrayRef<Value *> VL, const Value *VL0,
/*VariableMask=*/false, CommonAlignment, CostKind) +
(ProfitableGatherPointers ? 0 : VectorGEPCost);
InstructionCost GatherCost =
TTI.getScalarizationOverhead(VecTy, DemandedElts, /*Insert=*/true,
/*Extract=*/false, CostKind) +
getScalarizationOverhead(TTI, ScalarTy, VecTy, DemandedElts,
/*Insert=*/true,
/*Extract=*/false, CostKind) +
ScalarLoadsCost;
// The list of loads is small or perform partial check already - directly
// compare masked gather cost and gather cost.
Expand Down Expand Up @@ -5294,16 +5331,15 @@ BoUpSLP::canVectorizeLoads(ArrayRef<Value *> VL, const Value *VL0,
// Can be vectorized later as a serie of loads/insertelements.
InstructionCost VecLdCost = 0;
if (!DemandedElts.isZero()) {
VecLdCost =
TTI.getScalarizationOverhead(VecTy, DemandedElts, /*Insert=*/true,
/*Extract=*/false, CostKind) +
ScalarGEPCost;
VecLdCost = getScalarizationOverhead(TTI, ScalarTy, VecTy, DemandedElts,
/*Insert=*/true,
/*Extract=*/false, CostKind) +
ScalarGEPCost;
for (unsigned Idx : seq<unsigned>(VL.size()))
if (DemandedElts[Idx])
VecLdCost +=
TTI.getInstructionCost(cast<Instruction>(VL[Idx]), CostKind);
}
unsigned ScalarTyNumElements = getNumElements(ScalarTy);
auto *SubVecTy = getWidenedType(ScalarTy, VF);
for (auto [I, LS] : enumerate(States)) {
auto *LI0 = cast<LoadInst>(VL[I * VF]);
Expand All @@ -5323,13 +5359,13 @@ BoUpSLP::canVectorizeLoads(ArrayRef<Value *> VL, const Value *VL0,
return getUnderlyingObject(V) !=
getUnderlyingObject(PointerOps.front());
}))
VectorGEPCost += TTI.getScalarizationOverhead(
SubVecTy, APInt::getAllOnes(VF),
VectorGEPCost += getScalarizationOverhead(
TTI, ScalarTy, SubVecTy, APInt::getAllOnes(VF),
/*Insert=*/true, /*Extract=*/false, CostKind);
else
VectorGEPCost +=
TTI.getScalarizationOverhead(
SubVecTy, APInt::getOneBitSet(ScalarTyNumElements * VF, 0),
getScalarizationOverhead(
TTI, ScalarTy, SubVecTy, APInt::getOneBitSet(VF, 0),
/*Insert=*/true, /*Extract=*/false, CostKind) +
::getShuffleCost(TTI, TTI::SK_Broadcast, SubVecTy, {},
CostKind);
Expand Down Expand Up @@ -9912,20 +9948,9 @@ void BoUpSLP::reorderGatherNode(TreeEntry &TE) {
Cost += ::getShuffleCost(*TTI, TTI::SK_InsertSubvector, VecTy, {}, CostKind,
Idx, getWidenedType(ScalarTy, Sz));
}
if (auto *FTy = dyn_cast<FixedVectorType>(ScalarTy)) {
assert(SLPReVec && "Only supported by REVEC.");
// If ScalarTy is FixedVectorType, we should use CreateInsertVector instead
// of CreateInsertElement.
unsigned ScalarTyNumElements = getNumElements(ScalarTy);
for (unsigned I : seq<unsigned>(TE.Scalars.size()))
if (DemandedElts[I])
Cost +=
TTI->getShuffleCost(TTI::SK_InsertSubvector, VecTy, std::nullopt,
CostKind, I * ScalarTyNumElements, FTy);
} else {
Cost += TTI->getScalarizationOverhead(VecTy, DemandedElts, /*Insert=*/true,
/*Extract=*/false, CostKind);
}
Cost += getScalarizationOverhead(*TTI, ScalarTy, VecTy, DemandedElts,
/*Insert=*/true,
/*Extract=*/false, CostKind);
int Sz = TE.Scalars.size();
SmallVector<int> ReorderMask(TE.ReorderIndices.begin(),
TE.ReorderIndices.end());
Expand All @@ -9942,7 +9967,7 @@ void BoUpSLP::reorderGatherNode(TreeEntry &TE) {
? TTI::SK_PermuteTwoSrc
: TTI::SK_PermuteSingleSrc,
VecTy, ReorderMask);
DemandedElts = APInt::getAllOnes(VecTy->getNumElements());
DemandedElts = APInt::getAllOnes(TE.Scalars.size());
ReorderMask.assign(Sz, PoisonMaskElem);
for (unsigned I : seq<unsigned>(Sz)) {
Value *V = TE.getOrdered(I);
Expand All @@ -9954,8 +9979,9 @@ void BoUpSLP::reorderGatherNode(TreeEntry &TE) {
ReorderMask[I] = I + Sz;
}
}
InstructionCost BVCost = TTI->getScalarizationOverhead(
VecTy, DemandedElts, /*Insert=*/true, /*Extract=*/false, CostKind);
InstructionCost BVCost =
getScalarizationOverhead(*TTI, ScalarTy, VecTy, DemandedElts,
/*Insert=*/true, /*Extract=*/false, CostKind);
if (!DemandedElts.isAllOnes())
BVCost += ::getShuffleCost(*TTI, TTI::SK_PermuteTwoSrc, VecTy, ReorderMask);
if (Cost >= BVCost) {
Expand Down Expand Up @@ -11603,9 +11629,9 @@ BoUpSLP::getEntryCost(const TreeEntry *E, ArrayRef<Value *> VectorizedVals,
assert(Offset < NumElts && "Failed to find vector index offset");

InstructionCost Cost = 0;
Cost -= TTI->getScalarizationOverhead(SrcVecTy, DemandedElts,
/*Insert*/ true, /*Extract*/ false,
CostKind);
Cost -=
getScalarizationOverhead(*TTI, ScalarTy, SrcVecTy, DemandedElts,
/*Insert*/ true, /*Extract*/ false, CostKind);

// First cost - resize to actual vector size if not identity shuffle or
// need to shift the vector.
Expand Down Expand Up @@ -13780,8 +13806,8 @@ BoUpSLP::isGatherShuffledSingleRegisterEntry(
}
if (!IsIdentity)
FirstShuffleCost = GetShuffleCost(FirstMask, Entries.front(), VecTy);
FirstShuffleCost += TTI->getScalarizationOverhead(
MaskVecTy, DemandedElts, /*Insert=*/true,
FirstShuffleCost += getScalarizationOverhead(
*TTI, VL.front()->getType(), MaskVecTy, DemandedElts, /*Insert=*/true,
/*Extract=*/false, CostKind);
}
InstructionCost SecondShuffleCost = 0;
Expand All @@ -13805,17 +13831,17 @@ BoUpSLP::isGatherShuffledSingleRegisterEntry(
}
if (!IsIdentity)
SecondShuffleCost = GetShuffleCost(SecondMask, Entries[1], VecTy);
SecondShuffleCost += TTI->getScalarizationOverhead(
MaskVecTy, DemandedElts, /*Insert=*/true,
SecondShuffleCost += getScalarizationOverhead(
*TTI, VL.front()->getType(), MaskVecTy, DemandedElts, /*Insert=*/true,
/*Extract=*/false, CostKind);
}
APInt DemandedElts = APInt::getAllOnes(SubMask.size());
for (auto [I, Idx] : enumerate(SubMask))
if (Idx == PoisonMaskElem)
DemandedElts.clearBit(I);
InstructionCost BuildVectorCost =
TTI->getScalarizationOverhead(MaskVecTy, DemandedElts, /*Insert=*/true,
/*Extract=*/false, CostKind);
InstructionCost BuildVectorCost = getScalarizationOverhead(
*TTI, VL.front()->getType(), MaskVecTy, DemandedElts, /*Insert=*/true,
/*Extract=*/false, CostKind);
const TreeEntry *BestEntry = nullptr;
if (FirstShuffleCost < ShuffleCost) {
std::for_each(std::next(Mask.begin(), Part * VL.size()),
Expand Down Expand Up @@ -13968,45 +13994,15 @@ InstructionCost BoUpSLP::getGatherCost(ArrayRef<Value *> VL, bool ForPoisonSrc,
ShuffledElements.setBit(I);
ShuffleMask[I] = Res.first->second;
}
if (!DemandedElements.isZero()) {
if (isa<FixedVectorType>(ScalarTy)) {
assert(SLPReVec && "Only supported by REVEC.");
// We don't need to insert elements one by one. Instead, we can insert the
// entire vector into the destination.
Cost = 0;
unsigned ScalarTyNumElements = getNumElements(ScalarTy);
for (unsigned I : seq<unsigned>(VL.size()))
if (DemandedElements[I])
Cost += ::getShuffleCost(*TTI, TTI::SK_InsertSubvector, VecTy, {},
CostKind, I * ScalarTyNumElements,
cast<FixedVectorType>(ScalarTy));
} else {
Cost += TTI->getScalarizationOverhead(VecTy, DemandedElements,
/*Insert=*/true,
/*Extract=*/false, CostKind, VL);
}
}
if (ForPoisonSrc) {
if (isa<FixedVectorType>(ScalarTy)) {
assert(SLPReVec && "Only supported by REVEC.");
// We don't need to insert elements one by one. Instead, we can insert the
// entire vector into the destination.
assert(DemandedElements.isZero() &&
"Need to consider the cost from DemandedElements.");
Cost = 0;
unsigned ScalarTyNumElements = getNumElements(ScalarTy);
for (unsigned I : seq<unsigned>(VL.size()))
if (!ShuffledElements[I])
Cost += TTI->getShuffleCost(
TTI::SK_InsertSubvector, VecTy, std::nullopt, CostKind,
I * ScalarTyNumElements, cast<FixedVectorType>(ScalarTy));
} else {
Cost = TTI->getScalarizationOverhead(VecTy,
/*DemandedElts*/ ~ShuffledElements,
/*Insert*/ true,
/*Extract*/ false, CostKind, VL);
}
}
if (!DemandedElements.isZero())
Cost += getScalarizationOverhead(*TTI, ScalarTy, VecTy, DemandedElements,
/*Insert=*/true,
/*Extract=*/false, CostKind, VL);
if (ForPoisonSrc)
Cost = getScalarizationOverhead(*TTI, ScalarTy, VecTy,
/*DemandedElts*/ ~ShuffledElements,
/*Insert*/ true,
/*Extract*/ false, CostKind, VL);
if (DuplicateNonConst)
Cost += ::getShuffleCost(*TTI, TargetTransformInfo::SK_PermuteSingleSrc,
VecTy, ShuffleMask);
Expand Down