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[flang][Lower][OpenMP] Don't read moldarg for static sized array #125901

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Merged
merged 2 commits into from
Feb 18, 2025
Merged

[flang][Lower][OpenMP] Don't read moldarg for static sized array #125901

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4b31b3f
[flang][Lower][OpenMP] Don't read moldarg for static sized array
tblah Feb 5, 2025
d444627
Fix spelling
tblah Feb 6, 2025
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5 changes: 3 additions & 2 deletions flang/lib/Lower/OpenMP/DataSharingProcessor.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -508,6 +508,8 @@ void DataSharingProcessor::doPrivatize(const semantics::Symbol *sym,

lower::SymbolBox hsb = converter.lookupOneLevelUpSymbol(*sym);
assert(hsb && "Host symbol box not found");
hlfir::Entity entity{hsb.getAddr()};
bool cannotHaveNonDefaultLowerBounds = !entity.mayHaveNonDefaultLowerBounds();

mlir::Location symLoc = hsb.getAddr().getLoc();
std::string privatizerName = sym->name().ToString() + ".privatizer";
Expand All @@ -528,7 +530,6 @@ void DataSharingProcessor::doPrivatize(const semantics::Symbol *sym,
// an alloca for a fir.array type there. Get around this by boxing all
// arrays.
if (mlir::isa<fir::SequenceType>(allocType)) {
hlfir::Entity entity{hsb.getAddr()};
entity = genVariableBox(symLoc, firOpBuilder, entity);
privVal = entity.getBase();
allocType = privVal.getType();
Expand Down Expand Up @@ -590,7 +591,7 @@ void DataSharingProcessor::doPrivatize(const semantics::Symbol *sym,
result.getDeallocRegion(),
isFirstPrivate ? DeclOperationKind::FirstPrivate
: DeclOperationKind::Private,
sym);
sym, cannotHaveNonDefaultLowerBounds);
// TODO: currently there are false positives from dead uses of the mold
// arg
if (!result.getInitMoldArg().getUses().empty())
Expand Down
61 changes: 41 additions & 20 deletions flang/lib/Lower/OpenMP/PrivateReductionUtils.cpp
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Expand Up @@ -122,25 +122,40 @@ static void createCleanupRegion(Fortran::lower::AbstractConverter &converter,
typeError();
}

fir::ShapeShiftOp Fortran::lower::omp::getShapeShift(fir::FirOpBuilder &builder,
mlir::Location loc,
mlir::Value box) {
fir::ShapeShiftOp
Fortran::lower::omp::getShapeShift(fir::FirOpBuilder &builder,
mlir::Location loc, mlir::Value box,
bool cannotHaveNonDefaultLowerBounds) {
fir::SequenceType sequenceType = mlir::cast<fir::SequenceType>(
hlfir::getFortranElementOrSequenceType(box.getType()));
const unsigned rank = sequenceType.getDimension();

llvm::SmallVector<mlir::Value> lbAndExtents;
lbAndExtents.reserve(rank * 2);

mlir::Type idxTy = builder.getIndexType();
for (unsigned i = 0; i < rank; ++i) {
// TODO: ideally we want to hoist box reads out of the critical section.
// We could do this by having box dimensions in block arguments like
// OpenACC does
mlir::Value dim = builder.createIntegerConstant(loc, idxTy, i);
auto dimInfo =
builder.create<fir::BoxDimsOp>(loc, idxTy, idxTy, idxTy, box, dim);
lbAndExtents.push_back(dimInfo.getLowerBound());
lbAndExtents.push_back(dimInfo.getExtent());

if (cannotHaveNonDefaultLowerBounds && !sequenceType.hasDynamicExtents()) {
// We don't need fir::BoxDimsOp if all of the extents are statically known
// and we can assume default lower bounds. This helps avoids reads from the
// mold arg.
mlir::Value one = builder.createIntegerConstant(loc, idxTy, 1);
for (int64_t extent : sequenceType.getShape()) {
assert(extent != sequenceType.getUnknownExtent());
mlir::Value extentVal = builder.createIntegerConstant(loc, idxTy, extent);
lbAndExtents.push_back(one);
lbAndExtents.push_back(extentVal);
}
} else {
for (unsigned i = 0; i < rank; ++i) {
// TODO: ideally we want to hoist box reads out of the critical section.
// We could do this by having box dimensions in block arguments like
// OpenACC does
mlir::Value dim = builder.createIntegerConstant(loc, idxTy, i);
auto dimInfo =
builder.create<fir::BoxDimsOp>(loc, idxTy, idxTy, idxTy, box, dim);
lbAndExtents.push_back(dimInfo.getLowerBound());
lbAndExtents.push_back(dimInfo.getExtent());
}
}

auto shapeShiftTy = fir::ShapeShiftType::get(builder.getContext(), rank);
Expand Down Expand Up @@ -249,12 +264,13 @@ class PopulateInitAndCleanupRegionsHelper {
mlir::Type argType, mlir::Value scalarInitValue,
mlir::Value allocatedPrivVarArg, mlir::Value moldArg,
mlir::Block *initBlock, mlir::Region &cleanupRegion,
DeclOperationKind kind, const Fortran::semantics::Symbol *sym)
DeclOperationKind kind, const Fortran::semantics::Symbol *sym,
bool cannotHaveLowerBounds)
: converter{converter}, builder{converter.getFirOpBuilder()}, loc{loc},
argType{argType}, scalarInitValue{scalarInitValue},
allocatedPrivVarArg{allocatedPrivVarArg}, moldArg{moldArg},
initBlock{initBlock}, cleanupRegion{cleanupRegion}, kind{kind},
sym{sym} {
sym{sym}, cannotHaveNonDefaultLowerBounds{cannotHaveLowerBounds} {
valType = fir::unwrapRefType(argType);
}

Expand Down Expand Up @@ -296,6 +312,10 @@ class PopulateInitAndCleanupRegionsHelper {
/// Any length parameters which have been fetched for the type
mlir::SmallVector<mlir::Value> lenParams;

/// If the source variable being privatized definitely can't have non-default
/// lower bounds then we don't need to generate code to read them.
bool cannotHaveNonDefaultLowerBounds;

void createYield(mlir::Value ret) {
builder.create<mlir::omp::YieldOp>(loc, ret);
}
Expand Down Expand Up @@ -433,7 +453,8 @@ void PopulateInitAndCleanupRegionsHelper::initAndCleanupBoxedArray(
// Special case for (possibly allocatable) arrays of polymorphic types
// e.g. !fir.class<!fir.heap<!fir.array<?x!fir.type<>>>>
if (source.isPolymorphic()) {
fir::ShapeShiftOp shape = getShapeShift(builder, loc, source);
fir::ShapeShiftOp shape =
getShapeShift(builder, loc, source, cannotHaveNonDefaultLowerBounds);
mlir::Type arrayType = source.getElementOrSequenceType();
mlir::Value allocatedArray = builder.create<fir::AllocMemOp>(
loc, arrayType, /*typeparams=*/mlir::ValueRange{}, shape.getExtents());
Expand Down Expand Up @@ -472,8 +493,8 @@ void PopulateInitAndCleanupRegionsHelper::initAndCleanupBoxedArray(
// Put the temporary inside of a box:
// hlfir::genVariableBox doesn't handle non-default lower bounds
mlir::Value box;
fir::ShapeShiftOp shapeShift =
getShapeShift(builder, loc, getLoadedMoldArg());
fir::ShapeShiftOp shapeShift = getShapeShift(builder, loc, getLoadedMoldArg(),
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Does loading moldArg count as an use?
Or will we only insert a barrier if the loaded moldArg is referenced?

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Judging by the code in #125900, if there is only a load of moldArg it will be removed and no barrier will be inserted.

cannotHaveNonDefaultLowerBounds);
mlir::Type boxType = getLoadedMoldArg().getType();
if (mlir::isa<fir::BaseBoxType>(temp.getType()))
// the box created by the declare form createTempFromMold is missing
Expand Down Expand Up @@ -608,10 +629,10 @@ void Fortran::lower::omp::populateByRefInitAndCleanupRegions(
mlir::Type argType, mlir::Value scalarInitValue, mlir::Block *initBlock,
mlir::Value allocatedPrivVarArg, mlir::Value moldArg,
mlir::Region &cleanupRegion, DeclOperationKind kind,
const Fortran::semantics::Symbol *sym) {
const Fortran::semantics::Symbol *sym, bool cannotHaveLowerBounds) {
PopulateInitAndCleanupRegionsHelper helper(
converter, loc, argType, scalarInitValue, allocatedPrivVarArg, moldArg,
initBlock, cleanupRegion, kind, sym);
initBlock, cleanupRegion, kind, sym, cannotHaveLowerBounds);
helper.populateByRefInitAndCleanupRegions();

// Often we load moldArg to check something (e.g. length parameters, shape)
Expand Down
6 changes: 4 additions & 2 deletions flang/lib/Lower/OpenMP/PrivateReductionUtils.h
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Original file line number Diff line number Diff line change
Expand Up @@ -55,11 +55,13 @@ void populateByRefInitAndCleanupRegions(
mlir::Value scalarInitValue, mlir::Block *initBlock,
mlir::Value allocatedPrivVarArg, mlir::Value moldArg,
mlir::Region &cleanupRegion, DeclOperationKind kind,
const Fortran::semantics::Symbol *sym = nullptr);
const Fortran::semantics::Symbol *sym = nullptr,
bool cannotHaveNonDefaultLowerBounds = false);

/// Generate a fir::ShapeShift op describing the provided boxed array.
fir::ShapeShiftOp getShapeShift(fir::FirOpBuilder &builder, mlir::Location loc,
mlir::Value box);
mlir::Value box,
bool cannotHaveNonDefaultLowerBounds = false);

} // namespace omp
} // namespace lower
Expand Down
7 changes: 3 additions & 4 deletions flang/test/Lower/OpenMP/delayed-privatization-array.f90
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Expand Up @@ -108,15 +108,14 @@ program main
! ONE_DIM_DEFAULT_LB-SAME: @[[PRIVATIZER_SYM:.*]] : [[BOX_TYPE:!fir.box<!fir.array<10xi32>>]] init {

! ONE_DIM_DEFAULT_LB-NEXT: ^bb0(%[[PRIV_ARG:.*]]: [[TYPE:!fir.ref<!fir.box<!fir.array<10xi32>>>]], %[[PRIV_BOX_ALLOC:.*]]: [[TYPE]]):
! ONE_DIM_DEFAULT_LB-NEXT: %[[PRIV_ARG_VAL:.*]] = fir.load %[[PRIV_ARG]]
! ONE_DIM_DEFAULT_LB-NEXT: %[[C10:.*]] = arith.constant 10 : index
! ONE_DIM_DEFAULT_LB-NEXT: %[[SHAPE:.*]] = fir.shape %[[C10]]
! ONE_DIM_DEFAULT_LB-NEXT: %[[ARRAY_ALLOC:.*]] = fir.allocmem !fir.array<10xi32>
! ONE_DIM_DEFAULT_LB-NEXT: %[[TRUE:.*]] = arith.constant true
! ONE_DIM_DEFAULT_LB-NEXT: %[[DECL:.*]]:2 = hlfir.declare %[[ARRAY_ALLOC]](%[[SHAPE]])
! ONE_DIM_DEFAULT_LB-NEXT: %[[C0_0:.*]] = arith.constant 0
! ONE_DIM_DEFAULT_LB-NEXT: %[[DIMS2:.*]]:3 = fir.box_dims %[[PRIV_ARG_VAL]], %[[C0_0]]
! ONE_DIM_DEFAULT_LB-NEXT: %[[SHAPE_SHIFT:.*]] = fir.shape_shift %[[DIMS2]]#0, %[[DIMS2]]#1
! ONE_DIM_DEFAULT_LB-NEXT: %[[ONE:.*]] = arith.constant 1 : index
! ONE_DIM_DEFAULT_LB-NEXT: %[[TEN:.*]] = arith.constant 10 : index
! ONE_DIM_DEFAULT_LB-NEXT: %[[SHAPE_SHIFT:.*]] = fir.shape_shift %[[ONE]], %[[TEN]]
! ONE_DIM_DEFAULT_LB-NEXT: %[[EMBOX:.*]] = fir.embox %[[DECL]]#0(%[[SHAPE_SHIFT]])
! ONE_DIM_DEFAULT_LB-NEXT: fir.store %[[EMBOX]] to %[[PRIV_BOX_ALLOC]]
! ONE_DIM_DEFAULT_LB-NEXT: omp.yield(%[[PRIV_BOX_ALLOC]] : [[TYPE]])