Parse/Sema support for reduction over private variable with reduction clause

Author: Chandra Ghale

clang/include/clang/AST/OpenMPClause.h

@@ -3678,6 +3678,9 @@ class OMPReductionClause final
   /// Name of custom operator.
   DeclarationNameInfo NameInfo;
 
+  /// Private variable reduction flag
+  llvm::SmallVector<bool, 8> IsPrivateVarReductionFlags;
+
   /// Build clause with number of variables \a N.
   ///
   /// \param StartLoc Starting location of the clause.
@@ -3854,6 +3857,7 @@ class OMPReductionClause final
   /// region with this clause.
   /// \param PostUpdate Expression that must be executed after exit from the
   /// OpenMP region with this clause.
+  /// \pram IsPrivateVarReduction array for private variable reduction flags
   static OMPReductionClause *
   Create(const ASTContext &C, SourceLocation StartLoc, SourceLocation LParenLoc,
          SourceLocation ModifierLoc, SourceLocation ColonLoc,
@@ -3863,7 +3867,7 @@ class OMPReductionClause final
          ArrayRef<Expr *> LHSExprs, ArrayRef<Expr *> RHSExprs,
          ArrayRef<Expr *> ReductionOps, ArrayRef<Expr *> CopyOps,
          ArrayRef<Expr *> CopyArrayTemps, ArrayRef<Expr *> CopyArrayElems,
-         Stmt *PreInit, Expr *PostUpdate);
+         Stmt *PreInit, Expr *PostUpdate, ArrayRef<bool> IsPrivateVarReduction);
 
   /// Creates an empty clause with the place for \a N variables.
   ///
@@ -3889,6 +3893,16 @@ class OMPReductionClause final
   /// Gets the nested name specifier.
   NestedNameSpecifierLoc getQualifierLoc() const { return QualifierLoc; }
 
+  /// Get all private variable reduction flags
+  ArrayRef<bool> getPrivateVariableReductionFlags() const {
+    return IsPrivateVarReductionFlags;
+  }
+
+  //// Set private variable reduction flags
+  void setPrivateVariableReductionFlags(ArrayRef<bool> Flags) {
+    std::copy(Flags.begin(), Flags.end(), IsPrivateVarReductionFlags.begin());
+  }
+
   using helper_expr_iterator = MutableArrayRef<Expr *>::iterator;
   using helper_expr_const_iterator = ArrayRef<const Expr *>::iterator;
   using helper_expr_range = llvm::iterator_range<helper_expr_iterator>;

clang/include/clang/Basic/OpenMPKinds.def

@@ -71,6 +71,9 @@
 #ifndef OPENMP_REDUCTION_MODIFIER
 #define OPENMP_REDUCTION_MODIFIER(Name)
 #endif
+#ifndef OPENMP_ORIGINAL_SHARING_MODIFIER
+#define OPENMP_ORIGINAL_SHARING_MODIFIER(Name)
+#endif
 #ifndef OPENMP_ADJUST_ARGS_KIND
 #define OPENMP_ADJUST_ARGS_KIND(Name)
 #endif
@@ -202,6 +205,11 @@ OPENMP_REDUCTION_MODIFIER(default)
 OPENMP_REDUCTION_MODIFIER(inscan)
 OPENMP_REDUCTION_MODIFIER(task)
 
+// OpenMP 6.0 modifiers for 'reduction' clause.
+OPENMP_ORIGINAL_SHARING_MODIFIER(shared)
+OPENMP_ORIGINAL_SHARING_MODIFIER(private)
+OPENMP_ORIGINAL_SHARING_MODIFIER(default)
+
 // Adjust-op kinds for the 'adjust_args' clause.
 OPENMP_ADJUST_ARGS_KIND(nothing)
 OPENMP_ADJUST_ARGS_KIND(need_device_ptr)
@@ -233,6 +241,7 @@ OPENMP_DOACROSS_MODIFIER(source_omp_cur_iteration)
 #undef OPENMP_ADJUST_ARGS_KIND
 #undef OPENMP_REDUCTION_MODIFIER
 #undef OPENMP_DEVICE_MODIFIER
+#undef OPENMP_ORIGINAL_SHARING_MODIFIER
 #undef OPENMP_ORDER_KIND
 #undef OPENMP_ORDER_MODIFIER
 #undef OPENMP_LASTPRIVATE_KIND

clang/include/clang/Basic/OpenMPKinds.h

@@ -190,6 +190,13 @@ enum OpenMPReductionClauseModifier {
   OMPC_REDUCTION_unknown,
 };
 
+/// OpenMP 6.0 original sharing modifiers
+enum OpenMPOriginalSharingModifier {
+#define OPENMP_ORIGINAL_SHARING_MODIFIER(Name) OMPC_ORIGINAL_SHARING_##Name,
+#include "clang/Basic/OpenMPKinds.def"
+  OMPC_ORIGINAL_SHARING_unknown,
+};
+
 /// OpenMP adjust-op kinds for 'adjust_args' clause.
 enum OpenMPAdjustArgsOpKind {
 #define OPENMP_ADJUST_ARGS_KIND(Name) OMPC_ADJUST_ARGS_##Name,

clang/include/clang/Sema/SemaOpenMP.h

@@ -1142,6 +1142,7 @@ class SemaOpenMP : public SemaBase {
     DeclarationNameInfo ReductionOrMapperId;
     int ExtraModifier = -1; ///< Additional modifier for linear, map, depend or
                             ///< lastprivate clause.
+    int OriginalSharingModifier = 0; // Default is shared
     SmallVector<OpenMPMapModifierKind, NumberOfOMPMapClauseModifiers>
         MapTypeModifiers;
     SmallVector<SourceLocation, NumberOfOMPMapClauseModifiers>
@@ -1151,6 +1152,7 @@ class SemaOpenMP : public SemaBase {
     SmallVector<SourceLocation, NumberOfOMPMotionModifiers> MotionModifiersLoc;
     bool IsMapTypeImplicit = false;
     SourceLocation ExtraModifierLoc;
+    SourceLocation OriginalSharingModifierLoc;
     SourceLocation OmpAllMemoryLoc;
     SourceLocation
         StepModifierLoc; /// 'step' modifier location for linear clause
@@ -1213,7 +1215,9 @@ class SemaOpenMP : public SemaBase {
       SourceLocation ModifierLoc, SourceLocation ColonLoc,
       SourceLocation EndLoc, CXXScopeSpec &ReductionIdScopeSpec,
       const DeclarationNameInfo &ReductionId,
-      ArrayRef<Expr *> UnresolvedReductions = {});
+      ArrayRef<Expr *> UnresolvedReductions = {},
+      OpenMPOriginalSharingModifier OriginalShareModifier =
+          OMPC_ORIGINAL_SHARING_default);
   /// Called on well-formed 'task_reduction' clause.
   OMPClause *ActOnOpenMPTaskReductionClause(
       ArrayRef<Expr *> VarList, SourceLocation StartLoc,

clang/lib/AST/OpenMPClause.cpp

@@ -797,7 +797,7 @@ OMPReductionClause *OMPReductionClause::Create(
     ArrayRef<Expr *> Privates, ArrayRef<Expr *> LHSExprs,
     ArrayRef<Expr *> RHSExprs, ArrayRef<Expr *> ReductionOps,
     ArrayRef<Expr *> CopyOps, ArrayRef<Expr *> CopyArrayTemps,
-    ArrayRef<Expr *> CopyArrayElems, Stmt *PreInit, Expr *PostUpdate) {
+    ArrayRef<Expr *> CopyArrayElems, Stmt *PreInit, Expr *PostUpdate,ArrayRef<bool> IsPrivateVarReduction) {
   void *Mem = C.Allocate(totalSizeToAlloc<Expr *>(
       (Modifier == OMPC_REDUCTION_inscan ? 8 : 5) * VL.size()));
   auto *Clause = new (Mem)
@@ -810,6 +810,7 @@ OMPReductionClause *OMPReductionClause::Create(
   Clause->setReductionOps(ReductionOps);
   Clause->setPreInitStmt(PreInit);
   Clause->setPostUpdateExpr(PostUpdate);
+  Clause->setPrivateVariableReductionFlags(IsPrivateVarReduction);
   if (Modifier == OMPC_REDUCTION_inscan) {
     Clause->setInscanCopyOps(CopyOps);
     Clause->setInscanCopyArrayTemps(CopyArrayTemps);

clang/lib/Parse/ParseOpenMP.cpp

@@ -4668,6 +4668,33 @@ bool Parser::ParseOpenMPVarList(OpenMPDirectiveKind DKind,
       assert(Tok.is(tok::comma) && "Expected comma.");
       (void)ConsumeToken();
     }
+    // Handle original(private / shared) Modifier
+    if (Kind == OMPC_reduction && getLangOpts().OpenMP >= 60 &&
+        Tok.is(tok::identifier) && PP.getSpelling(Tok) == "original" &&
+        NextToken().is(tok::l_paren)) {
+      // Parse original(private) modifier.
+      ConsumeToken();
+      BalancedDelimiterTracker ParenT(*this, tok::l_paren, tok::r_paren);
+      ParenT.consumeOpen();
+      if (Tok.is(tok::kw_private)) {
+        Data.OriginalSharingModifier = OMPC_ORIGINAL_SHARING_private;
+        Data.OriginalSharingModifierLoc = Tok.getLocation();
+        ConsumeToken();
+      } else if (Tok.is(tok::identifier) && (PP.getSpelling(Tok) == "shared" 
+           || PP.getSpelling(Tok) == "default")) {
+        Data.OriginalSharingModifier = OMPC_ORIGINAL_SHARING_shared;
+        Data.OriginalSharingModifierLoc = Tok.getLocation();
+        ConsumeToken();
+      } else {
+        Diag(Tok.getLocation(), diag::err_expected)
+            << "'private or shared or default'";
+        SkipUntil(tok::r_paren);
+        return false;
+      }
+      ParenT.consumeClose();
+      assert(Tok.is(tok::comma) && "Expected comma.");
+      (void)ConsumeToken();
+    }
     ColonProtectionRAIIObject ColonRAII(*this);
     if (getLangOpts().CPlusPlus)
       ParseOptionalCXXScopeSpecifier(Data.ReductionOrMapperIdScopeSpec,

clang/lib/Sema/SemaOpenMP.cpp

@@ -17366,6 +17366,7 @@ OMPClause *SemaOpenMP::ActOnOpenMPVarListClause(OpenMPClauseKind Kind,
   SourceLocation EndLoc = Locs.EndLoc;
   OMPClause *Res = nullptr;
   int ExtraModifier = Data.ExtraModifier;
+  int OriginalSharingModifier = Data.OriginalSharingModifier;
   SourceLocation ExtraModifierLoc = Data.ExtraModifierLoc;
   SourceLocation ColonLoc = Data.ColonLoc;
   switch (Kind) {
@@ -17391,7 +17392,8 @@ OMPClause *SemaOpenMP::ActOnOpenMPVarListClause(OpenMPClauseKind Kind,
     Res = ActOnOpenMPReductionClause(
         VarList, static_cast<OpenMPReductionClauseModifier>(ExtraModifier),
         StartLoc, LParenLoc, ExtraModifierLoc, ColonLoc, EndLoc,
-        Data.ReductionOrMapperIdScopeSpec, Data.ReductionOrMapperId);
+        Data.ReductionOrMapperIdScopeSpec, Data.ReductionOrMapperId, {},
+        static_cast<OpenMPOriginalSharingModifier>(OriginalSharingModifier));
     break;
   case OMPC_task_reduction:
     Res = ActOnOpenMPTaskReductionClause(
@@ -18570,14 +18572,20 @@ struct ReductionData {
   SmallVector<Expr *, 4> ExprPostUpdates;
   /// Reduction modifier.
   unsigned RedModifier = 0;
+  /// Original modifier.
+  unsigned OrigSharingModifier = 0;
+  /// Private Variable Reduction
+  SmallVector<bool, 8> IsPrivateVarReduction;
   ReductionData() = delete;
   /// Reserves required memory for the reduction data.
-  ReductionData(unsigned Size, unsigned Modifier = 0) : RedModifier(Modifier) {
+  ReductionData(unsigned Size, unsigned Modifier = 0, unsigned OrgModifier = 0)
+      : RedModifier(Modifier), OrigSharingModifier(OrgModifier) {
     Vars.reserve(Size);
     Privates.reserve(Size);
     LHSs.reserve(Size);
     RHSs.reserve(Size);
     ReductionOps.reserve(Size);
+    IsPrivateVarReduction.reserve(Size);
     if (RedModifier == OMPC_REDUCTION_inscan) {
       InscanCopyOps.reserve(Size);
       InscanCopyArrayTemps.reserve(Size);
@@ -18595,6 +18603,7 @@ struct ReductionData {
     LHSs.emplace_back(nullptr);
     RHSs.emplace_back(nullptr);
     ReductionOps.emplace_back(ReductionOp);
+    IsPrivateVarReduction.emplace_back(false);
     TaskgroupDescriptors.emplace_back(nullptr);
     if (RedModifier == OMPC_REDUCTION_inscan) {
       InscanCopyOps.push_back(nullptr);
@@ -18605,7 +18614,7 @@ struct ReductionData {
   /// Stores reduction data.
   void push(Expr *Item, Expr *Private, Expr *LHS, Expr *RHS, Expr *ReductionOp,
             Expr *TaskgroupDescriptor, Expr *CopyOp, Expr *CopyArrayTemp,
-            Expr *CopyArrayElem) {
+            Expr *CopyArrayElem, bool IsPrivate) {
     Vars.emplace_back(Item);
     Privates.emplace_back(Private);
     LHSs.emplace_back(LHS);
@@ -18621,6 +18630,7 @@ struct ReductionData {
              CopyArrayElem == nullptr &&
              "Copy operation must be used for inscan reductions only.");
     }
+    IsPrivateVarReduction.emplace_back(IsPrivate);
   }
 };
 } // namespace
@@ -18834,6 +18844,7 @@ static bool actOnOMPReductionKindClause(
     FirstIter = false;
     SourceLocation ELoc;
     SourceRange ERange;
+    bool IsPrivate = false;
     Expr *SimpleRefExpr = RefExpr;
     auto Res = getPrivateItem(S, SimpleRefExpr, ELoc, ERange,
                               /*AllowArraySection=*/true);
@@ -18933,12 +18944,35 @@ static bool actOnOMPReductionKindClause(
         reportOriginalDsa(S, Stack, D, DVar);
         continue;
       }
+      // OpenMP 6.0 [ 7.6.10 ]
+      // Support Reduction over private variables with reduction clause.
+      // A list item in a reduction clause can now be private in the enclosing
+      // context. For orphaned constructs it is assumed to be shared unless the
+      // original(private) modifier appears in the clause.
+      DVar = Stack->getImplicitDSA(D, true);
+      bool IsOrphaned = false;
+      OpenMPDirectiveKind CurrDir = Stack->getCurrentDirective();
+      OpenMPDirectiveKind ParentDir = Stack->getParentDirective();
+      // Check if the construct is orphaned (has no enclosing OpenMP context)
+      IsOrphaned = (ParentDir == OMPD_unknown);
+      IsPrivate =
+          ((isOpenMPPrivate(DVar.CKind) && DVar.CKind != OMPC_reduction &&
+            isOpenMPWorksharingDirective(CurrDir) &&
+            !isOpenMPParallelDirective(CurrDir) &&
+            !isOpenMPTeamsDirective(CurrDir) &&
+            !isOpenMPSimdDirective(ParentDir)) ||
+           (IsOrphaned && DVar.CKind == OMPC_unknown) ||
+           RD.OrigSharingModifier != OMPC_ORIGINAL_SHARING_shared);
+      // Disable private handling for OpenMP versions <= 5.2
+      if (S.getLangOpts().OpenMP <= 52)
+        IsPrivate = false;
 
       // OpenMP [2.14.3.6, Restrictions, p.1]
       //  A list item that appears in a reduction clause of a worksharing
       //  construct must be shared in the parallel regions to which any of the
       //  worksharing regions arising from the worksharing construct bind.
-      if (isOpenMPWorksharingDirective(CurrDir) &&
+
+      if (!IsPrivate && isOpenMPWorksharingDirective(CurrDir) &&
           !isOpenMPParallelDirective(CurrDir) &&
           !isOpenMPTeamsDirective(CurrDir)) {
         DVar = Stack->getImplicitDSA(D, true);
@@ -19434,7 +19468,7 @@ static bool actOnOMPReductionKindClause(
     }
     RD.push(VarsExpr, PrivateDRE, LHSDRE, RHSDRE, ReductionOp.get(),
             TaskgroupDescriptor, CopyOpRes.get(), TempArrayRes.get(),
-            TempArrayElem.get());
+            TempArrayElem.get(), IsPrivate);
   }
   return RD.Vars.empty();
 }
@@ -19444,7 +19478,8 @@ OMPClause *SemaOpenMP::ActOnOpenMPReductionClause(
     SourceLocation StartLoc, SourceLocation LParenLoc,
     SourceLocation ModifierLoc, SourceLocation ColonLoc, SourceLocation EndLoc,
     CXXScopeSpec &ReductionIdScopeSpec, const DeclarationNameInfo &ReductionId,
-    ArrayRef<Expr *> UnresolvedReductions) {
+    ArrayRef<Expr *> UnresolvedReductions,
+    OpenMPOriginalSharingModifier OriginalSharingMod) {
   if (ModifierLoc.isValid() && Modifier == OMPC_REDUCTION_unknown) {
     Diag(LParenLoc, diag::err_omp_unexpected_clause_value)
         << getListOfPossibleValues(OMPC_reduction, /*First=*/0,
@@ -19466,8 +19501,7 @@ OMPClause *SemaOpenMP::ActOnOpenMPReductionClause(
     Diag(ModifierLoc, diag::err_omp_wrong_inscan_reduction);
     return nullptr;
   }
-
-  ReductionData RD(VarList.size(), Modifier);
+  ReductionData RD(VarList.size(), Modifier, OriginalSharingMod);
   if (actOnOMPReductionKindClause(SemaRef, DSAStack, OMPC_reduction, VarList,
                                   StartLoc, LParenLoc, ColonLoc, EndLoc,
                                   ReductionIdScopeSpec, ReductionId,
@@ -19481,7 +19515,7 @@ OMPClause *SemaOpenMP::ActOnOpenMPReductionClause(
       RD.Privates, RD.LHSs, RD.RHSs, RD.ReductionOps, RD.InscanCopyOps,
       RD.InscanCopyArrayTemps, RD.InscanCopyArrayElems,
       buildPreInits(getASTContext(), RD.ExprCaptures),
-      buildPostUpdate(SemaRef, RD.ExprPostUpdates));
+      buildPostUpdate(SemaRef, RD.ExprPostUpdates), RD.IsPrivateVarReduction);
 }
 
 OMPClause *SemaOpenMP::ActOnOpenMPTaskReductionClause(