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

luporl · web-flow · commit 216ba6bc6c0d · 2024-08-26T08:39:32.000-03:00
Variables referenced in the body of statement functions need to be handled as if they are explicitly referenced. Otherwise, they are skipped during implicit privatization, because statement functions are represented as procedures in the parse tree. To avoid missing symbols referenced only in statement functions during implicit privatization, new symbols, associated with them, are created and inserted into the context of the directive that privatizes them. They are later collected and processed in lowering. To avoid confusing these new symbols with regular ones, they are tagged with the new OmpFromStmtFunction flag. Fixes #74273
diff --git a/flang/include/flang/Semantics/symbol.h b/flang/include/flang/Semantics/symbol.h
@@ -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_; }
diff --git a/flang/lib/Lower/OpenMP/DataSharingProcessor.cpp b/flang/lib/Lower/OpenMP/DataSharingProcessor.cpp
@@ -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);
 
diff --git a/flang/lib/Semantics/resolve-directives.cpp b/flang/lib/Semantics/resolve-directives.cpp
@@ -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) {
@@ -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 &);
@@ -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>
@@ -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) {
@@ -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;
@@ -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)) {
@@ -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
 }
diff --git a/flang/test/Lower/OpenMP/statement-function.f90 b/flang/test/Lower/OpenMP/statement-function.f90
