Skip to content

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

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 5 commits into from
Feb 25, 2025
Merged

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

Changes from 4 commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
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
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
161 changes: 78 additions & 83 deletions llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
View file
Open in desktop
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 @@ -5207,10 +5243,9 @@ 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());
APInt DemandedElts = APInt::getAllOnes(Sz);
VectorType *PtrVecTy =
getWidenedType(PointerOps.front()->getType()->getScalarType(),
VecTy->getNumElements());
getWidenedType(PointerOps.front()->getType()->getScalarType(), Sz);
if (static_cast<unsigned>(count_if(
PointerOps, IsaPred<GetElementPtrInst>)) < PointerOps.size() - 1 ||
any_of(PointerOps, [&](Value *V) {
Expand All @@ -5221,9 +5256,9 @@ BoUpSLP::canVectorizeLoads(ArrayRef<Value *> VL, const Value *VL0,
PtrVecTy, DemandedElts, /*Insert=*/true, /*Extract=*/false, CostKind);
else
VectorGEPCost +=
TTI.getScalarizationOverhead(
PtrVecTy, APInt::getOneBitSet(VecTy->getNumElements(), 0),
/*Insert=*/true, /*Extract=*/false, CostKind) +
TTI.getScalarizationOverhead(PtrVecTy, APInt::getOneBitSet(Sz, 0),
Copy link
Member

@alexey-bataev alexey-bataev Feb 24, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This is not a part of this change, the common function is not used

Copy link
Contributor Author

@HanKuanChen HanKuanChen Feb 25, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

They share DemandedElts in Line 5278.

    InstructionCost GatherCost =
        getScalarizationOverhead(TTI, ScalarTy, VecTy, DemandedElts,
                                 /*Insert=*/true,
                                 /*Extract=*/false, CostKind) +
        ScalarLoadsCost;

/*Insert=*/true, /*Extract=*/false,
CostKind) +
::getShuffleCost(TTI, TTI::SK_Broadcast, PtrVecTy, {}, CostKind);
// The cost of scalar loads.
InstructionCost ScalarLoadsCost =
Expand All @@ -5240,8 +5275,9 @@ 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 +5330,15 @@ 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 +5358,13 @@ 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 +9947,9 @@ 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 +9966,7 @@ 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 +9978,9 @@ 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 +11628,9 @@ 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 +13805,8 @@ 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 +13830,17 @@ 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 +13993,15 @@ 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
Loading