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[flang][OpenMP] Privatize vars referenced in statement functions #103390

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Aug 26, 2024
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[flang][OpenMP] Privatize vars referenced in statement functions #103390

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962b226
[flang][OpenMP] Privatize vars referenced in statement functions
luporl Jul 23, 2024
5d453c6
Refactoring: simplify the handling of statement function symbols
luporl Aug 20, 2024
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2 changes: 1 addition & 1 deletion flang/include/flang/Semantics/symbol.h
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Original file line number Diff line number Diff line change
Expand Up @@ -755,7 +755,7 @@ class Symbol {
OmpDeclarativeAllocateDirective, OmpExecutableAllocateDirective,
OmpDeclareSimd, OmpDeclareTarget, OmpThreadprivate, OmpDeclareReduction,
OmpFlushed, OmpCriticalLock, OmpIfSpecified, OmpNone, OmpPreDetermined,
OmpImplicit);
OmpImplicit, OmpFromStmtFunction);
using Flags = common::EnumSet<Flag, Flag_enumSize>;

const Scope &owner() const { return *owner_; }
Expand Down
9 changes: 9 additions & 0 deletions flang/lib/Lower/OpenMP/DataSharingProcessor.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -402,6 +402,15 @@ void DataSharingProcessor::collectSymbols(
/*collectSymbols=*/true,
/*collectHostAssociatedSymbols=*/true);

// Add implicitly referenced symbols from statement functions.
if (curScope) {
for (const auto &sym : curScope->GetSymbols()) {
if (sym->test(semantics::Symbol::Flag::OmpFromStmtFunction) &&
sym->test(flag))
allSymbols.insert(&*sym);
}
}

llvm::SetVector<const semantics::Symbol *> symbolsInNestedRegions;
collectSymbolsInNestedRegions(eval, flag, symbolsInNestedRegions);

Expand Down
313 changes: 174 additions & 139 deletions flang/lib/Semantics/resolve-directives.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -91,11 +91,12 @@ template <typename T> class DirectiveAttributeVisitor {
void SetContextAssociatedLoopLevel(std::int64_t level) {
GetContext().associatedLoopLevel = level;
}
Symbol &MakeAssocSymbol(const SourceName &name, Symbol &prev, Scope &scope) {
Symbol &MakeAssocSymbol(
const SourceName &name, const Symbol &prev, Scope &scope) {
const auto pair{scope.try_emplace(name, Attrs{}, HostAssocDetails{prev})};
return *pair.first->second;
}
Symbol &MakeAssocSymbol(const SourceName &name, Symbol &prev) {
Symbol &MakeAssocSymbol(const SourceName &name, const Symbol &prev) {
return MakeAssocSymbol(name, prev, currScope());
}
void AddDataSharingAttributeObject(SymbolRef object) {
Expand All @@ -108,6 +109,7 @@ template <typename T> class DirectiveAttributeVisitor {
const parser::Name *GetLoopIndex(const parser::DoConstruct &);
const parser::DoConstruct *GetDoConstructIf(
const parser::ExecutionPartConstruct &);
Symbol *DeclareNewPrivateAccessEntity(const Symbol &, Symbol::Flag, Scope &);
Symbol *DeclarePrivateAccessEntity(
const parser::Name &, Symbol::Flag, Scope &);
Symbol *DeclarePrivateAccessEntity(Symbol &, Symbol::Flag, Scope &);
Expand Down Expand Up @@ -736,6 +738,9 @@ class OmpAttributeVisitor : DirectiveAttributeVisitor<llvm::omp::Directive> {
std::optional<common::OmpAtomicDefaultMemOrderType>);
void IssueNonConformanceWarning(
llvm::omp::Directive D, parser::CharBlock source);

void CreateImplicitSymbols(
const Symbol *symbol, std::optional<Symbol::Flag> setFlag = std::nullopt);
};

template <typename T>
Expand Down Expand Up @@ -771,6 +776,19 @@ const parser::DoConstruct *DirectiveAttributeVisitor<T>::GetDoConstructIf(
return parser::Unwrap<parser::DoConstruct>(x);
}

template <typename T>
Symbol *DirectiveAttributeVisitor<T>::DeclareNewPrivateAccessEntity(
const Symbol &object, Symbol::Flag flag, Scope &scope) {
assert(object.owner() != currScope());
auto &symbol{MakeAssocSymbol(object.name(), object, scope)};
symbol.set(flag);
if (flag == Symbol::Flag::OmpCopyIn) {
// The symbol in copyin clause must be threadprivate entity.
symbol.set(Symbol::Flag::OmpThreadprivate);
}
return &symbol;
}

template <typename T>
Symbol *DirectiveAttributeVisitor<T>::DeclarePrivateAccessEntity(
const parser::Name &name, Symbol::Flag flag, Scope &scope) {
Expand All @@ -785,13 +803,7 @@ template <typename T>
Symbol *DirectiveAttributeVisitor<T>::DeclarePrivateAccessEntity(
Symbol &object, Symbol::Flag flag, Scope &scope) {
if (object.owner() != currScope()) {
auto &symbol{MakeAssocSymbol(object.name(), object, scope)};
symbol.set(flag);
if (flag == Symbol::Flag::OmpCopyIn) {
// The symbol in copyin clause must be threadprivate entity.
symbol.set(Symbol::Flag::OmpThreadprivate);
}
return &symbol;
return DeclareNewPrivateAccessEntity(object, flag, scope);
} else {
object.set(flag);
return &object;
Expand Down Expand Up @@ -2031,24 +2043,152 @@ void OmpAttributeVisitor::Post(const parser::OpenMPAllocatorsConstruct &x) {
PopContext();
}

static bool IsPrivatizable(const Symbol *sym) {
auto *misc{sym->detailsIf<MiscDetails>()};
return !IsProcedure(*sym) && !IsNamedConstant(*sym) &&
!sym->owner().IsDerivedType() &&
sym->owner().kind() != Scope::Kind::ImpliedDos &&
!sym->detailsIf<semantics::AssocEntityDetails>() &&
!sym->detailsIf<semantics::NamelistDetails>() &&
(!misc ||
(misc->kind() != MiscDetails::Kind::ComplexPartRe &&
misc->kind() != MiscDetails::Kind::ComplexPartIm &&
misc->kind() != MiscDetails::Kind::KindParamInquiry &&
misc->kind() != MiscDetails::Kind::LenParamInquiry &&
misc->kind() != MiscDetails::Kind::ConstructName));
}

void OmpAttributeVisitor::CreateImplicitSymbols(
const Symbol *symbol, std::optional<Symbol::Flag> setFlag) {
if (!IsPrivatizable(symbol)) {
return;
}

// Implicitly determined DSAs
// OMP 5.2 5.1.1 - Variables Referenced in a Construct
Symbol *lastDeclSymbol = nullptr;
std::optional<Symbol::Flag> prevDSA;
for (int dirDepth{0}; dirDepth < (int)dirContext_.size(); ++dirDepth) {
DirContext &dirContext = dirContext_[dirDepth];
std::optional<Symbol::Flag> dsa;

for (auto symMap : dirContext.objectWithDSA) {
// if the `symbol` already has a data-sharing attribute
if (symMap.first->name() == symbol->name()) {
dsa = symMap.second;
break;
}
}

// When handling each implicit rule for a given symbol, one of the
// following 3 actions may be taken:
// 1. Declare a new private symbol.
// 2. Create a new association symbol with no flags, that will represent
// a shared symbol in the current scope. Note that symbols without
// any private flags are considered as shared.
// 3. Use the last declared private symbol, by inserting a new symbol
// in the scope being processed, associated with it.
// If no private symbol was declared previously, then no association
// is needed and the symbol from the enclosing scope will be
// inherited by the current one.
//
// Because of how symbols are collected in lowering, not inserting a new
// symbol in the last case could lead to the conclusion that a symbol
// from an enclosing construct was declared in the current construct,
// which would result in wrong privatization code being generated.
// Consider the following example:
//
// !$omp parallel default(private) ! p1
// !$omp parallel default(private) shared(x) ! p2
// x = 10
// !$omp end parallel
// !$omp end parallel
//
// If a new x symbol was not inserted in the inner parallel construct
// (p2), it would use the x symbol definition from the enclosing scope.
// Then, when p2's default symbols were collected in lowering, the x
// symbol from the outer parallel construct (p1) would be collected, as
// it would have the private flag set.
// This would make x appear to be defined in p2, causing it to be
// privatized in p2 and its privatization in p1 to be skipped.
auto makePrivateSymbol = [&](Symbol::Flag flag) {
const Symbol *hostSymbol =
lastDeclSymbol ? lastDeclSymbol : &symbol->GetUltimate();
lastDeclSymbol = DeclareNewPrivateAccessEntity(
*hostSymbol, flag, context_.FindScope(dirContext.directiveSource));
if (setFlag) {
lastDeclSymbol->set(*setFlag);
}
return lastDeclSymbol;
};
auto makeSharedSymbol = [&]() {
const Symbol *hostSymbol =
lastDeclSymbol ? lastDeclSymbol : &symbol->GetUltimate();
MakeAssocSymbol(symbol->name(), *hostSymbol,
context_.FindScope(dirContext.directiveSource));
};
auto useLastDeclSymbol = [&]() {
if (lastDeclSymbol) {
makeSharedSymbol();
}
};

bool taskGenDir = llvm::omp::taskGeneratingSet.test(dirContext.directive);
bool targetDir = llvm::omp::allTargetSet.test(dirContext.directive);
bool parallelDir = llvm::omp::allParallelSet.test(dirContext.directive);
bool teamsDir = llvm::omp::allTeamsSet.test(dirContext.directive);

if (dsa.has_value()) {
if (dsa.value() == Symbol::Flag::OmpShared &&
(parallelDir || taskGenDir || teamsDir))
makeSharedSymbol();
// Private symbols will have been declared already.
prevDSA = dsa;
continue;
}

if (dirContext.defaultDSA == Symbol::Flag::OmpPrivate ||
dirContext.defaultDSA == Symbol::Flag::OmpFirstPrivate ||
dirContext.defaultDSA == Symbol::Flag::OmpShared) {
// 1) default
// Allowed only with parallel, teams and task generating constructs.
assert(parallelDir || taskGenDir || teamsDir);
if (dirContext.defaultDSA != Symbol::Flag::OmpShared)
makePrivateSymbol(dirContext.defaultDSA);
else
makeSharedSymbol();
dsa = dirContext.defaultDSA;
} else if (parallelDir) {
// 2) parallel -> shared
makeSharedSymbol();
dsa = Symbol::Flag::OmpShared;
} else if (!taskGenDir && !targetDir) {
// 3) enclosing context
useLastDeclSymbol();
dsa = prevDSA;
} else if (targetDir) {
// TODO 4) not mapped target variable -> firstprivate
dsa = prevDSA;
} else if (taskGenDir) {
// TODO 5) dummy arg in orphaned taskgen construct -> firstprivate
if (prevDSA == Symbol::Flag::OmpShared) {
// 6) shared in enclosing context -> shared
makeSharedSymbol();
dsa = Symbol::Flag::OmpShared;
} else {
// 7) firstprivate
dsa = Symbol::Flag::OmpFirstPrivate;
makePrivateSymbol(*dsa)->set(Symbol::Flag::OmpImplicit);
}
}
prevDSA = dsa;
}
}

// For OpenMP constructs, check all the data-refs within the constructs
// and adjust the symbol for each Name if necessary
void OmpAttributeVisitor::Post(const parser::Name &name) {
auto *symbol{name.symbol};
auto IsPrivatizable = [](const Symbol *sym) {
auto *misc{sym->detailsIf<MiscDetails>()};
return !IsProcedure(*sym) && !IsNamedConstant(*sym) &&
!sym->owner().IsDerivedType() &&
sym->owner().kind() != Scope::Kind::ImpliedDos &&
!sym->detailsIf<semantics::AssocEntityDetails>() &&
!sym->detailsIf<semantics::NamelistDetails>() &&
(!misc ||
(misc->kind() != MiscDetails::Kind::ComplexPartRe &&
misc->kind() != MiscDetails::Kind::ComplexPartIm &&
misc->kind() != MiscDetails::Kind::KindParamInquiry &&
misc->kind() != MiscDetails::Kind::LenParamInquiry &&
misc->kind() != MiscDetails::Kind::ConstructName));
};

if (symbol && !dirContext_.empty() && GetContext().withinConstruct) {
if (IsPrivatizable(symbol) && !IsObjectWithDSA(*symbol)) {
Expand Down Expand Up @@ -2076,125 +2216,20 @@ void OmpAttributeVisitor::Post(const parser::Name &name) {
if (found->test(semantics::Symbol::Flag::OmpThreadprivate))
return;
}
if (!IsPrivatizable(symbol)) {
return;
}

// Implicitly determined DSAs
// OMP 5.2 5.1.1 - Variables Referenced in a Construct
Symbol *lastDeclSymbol = nullptr;
std::optional<Symbol::Flag> prevDSA;
for (int dirDepth{0}; dirDepth < (int)dirContext_.size(); ++dirDepth) {
DirContext &dirContext = dirContext_[dirDepth];
std::optional<Symbol::Flag> dsa;

for (auto symMap : dirContext.objectWithDSA) {
// if the `symbol` already has a data-sharing attribute
if (symMap.first->name() == name.symbol->name()) {
dsa = symMap.second;
break;
}
}

// When handling each implicit rule for a given symbol, one of the
// following 3 actions may be taken:
// 1. Declare a new private symbol.
// 2. Create a new association symbol with no flags, that will represent
// a shared symbol in the current scope. Note that symbols without
// any private flags are considered as shared.
// 3. Use the last declared private symbol, by inserting a new symbol
// in the scope being processed, associated with it.
// If no private symbol was declared previously, then no association
// is needed and the symbol from the enclosing scope will be
// inherited by the current one.
//
// Because of how symbols are collected in lowering, not inserting a new
// symbol in the last case could lead to the conclusion that a symbol
// from an enclosing construct was declared in the current construct,
// which would result in wrong privatization code being generated.
// Consider the following example:
//
// !$omp parallel default(private) ! p1
// !$omp parallel default(private) shared(x) ! p2
// x = 10
// !$omp end parallel
// !$omp end parallel
//
// If a new x symbol was not inserted in the inner parallel construct
// (p2), it would use the x symbol definition from the enclosing scope.
// Then, when p2's default symbols were collected in lowering, the x
// symbol from the outer parallel construct (p1) would be collected, as
// it would have the private flag set.
// This would make x appear to be defined in p2, causing it to be
// privatized in p2 and its privatization in p1 to be skipped.
auto makePrivateSymbol = [&](Symbol::Flag flag) {
Symbol *hostSymbol =
lastDeclSymbol ? lastDeclSymbol : &symbol->GetUltimate();
lastDeclSymbol = DeclarePrivateAccessEntity(
*hostSymbol, flag, context_.FindScope(dirContext.directiveSource));
return lastDeclSymbol;
};
auto makeSharedSymbol = [&]() {
Symbol *hostSymbol =
lastDeclSymbol ? lastDeclSymbol : &symbol->GetUltimate();
MakeAssocSymbol(symbol->name(), *hostSymbol,
context_.FindScope(dirContext.directiveSource));
};
auto useLastDeclSymbol = [&]() {
if (lastDeclSymbol)
MakeAssocSymbol(symbol->name(), *lastDeclSymbol,
context_.FindScope(dirContext.directiveSource));
};

bool taskGenDir = llvm::omp::taskGeneratingSet.test(dirContext.directive);
bool targetDir = llvm::omp::allTargetSet.test(dirContext.directive);
bool parallelDir = llvm::omp::allParallelSet.test(dirContext.directive);
bool teamsDir = llvm::omp::allTeamsSet.test(dirContext.directive);

if (dsa.has_value()) {
if (dsa.value() == Symbol::Flag::OmpShared &&
(parallelDir || taskGenDir || teamsDir))
makeSharedSymbol();
// Private symbols will have been declared already.
prevDSA = dsa;
continue;
}

if (dirContext.defaultDSA == Symbol::Flag::OmpPrivate ||
dirContext.defaultDSA == Symbol::Flag::OmpFirstPrivate ||
dirContext.defaultDSA == Symbol::Flag::OmpShared) {
// 1) default
// Allowed only with parallel, teams and task generating constructs.
assert(parallelDir || taskGenDir || teamsDir);
if (dirContext.defaultDSA != Symbol::Flag::OmpShared)
makePrivateSymbol(dirContext.defaultDSA);
else
makeSharedSymbol();
dsa = dirContext.defaultDSA;
} else if (parallelDir) {
// 2) parallel -> shared
makeSharedSymbol();
dsa = Symbol::Flag::OmpShared;
} else if (!taskGenDir && !targetDir) {
// 3) enclosing context
useLastDeclSymbol();
dsa = prevDSA;
} else if (targetDir) {
// TODO 4) not mapped target variable -> firstprivate
dsa = prevDSA;
} else if (taskGenDir) {
// TODO 5) dummy arg in orphaned taskgen construct -> firstprivate
if (prevDSA == Symbol::Flag::OmpShared) {
// 6) shared in enclosing context -> shared
makeSharedSymbol();
dsa = Symbol::Flag::OmpShared;
} else {
// 7) firstprivate
dsa = Symbol::Flag::OmpFirstPrivate;
makePrivateSymbol(*dsa)->set(Symbol::Flag::OmpImplicit);
if (auto *stmtFunction{symbol->detailsIf<semantics::SubprogramDetails>()};
stmtFunction && stmtFunction->stmtFunction()) {
// Each non-dummy argument from a statement function must be handled too,
// as if it was explicitly referenced.
semantics::UnorderedSymbolSet symbols{
CollectSymbols(stmtFunction->stmtFunction().value())};
for (const auto &sym : symbols) {
if (!IsStmtFunctionDummy(sym) && !IsObjectWithDSA(*sym)) {
CreateImplicitSymbols(&*sym, Symbol::Flag::OmpFromStmtFunction);
}
}
prevDSA = dsa;
} else {
CreateImplicitSymbols(symbol);
}
} // within OpenMP construct
}
Expand Down
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