[OpenMP 6.0] Parse/Sema support for reduction over private variable with reduction clause. (llvm#129938)

Initial Parse/Sema support for reduction over private variable with
reduction clause.
Section 7.6.10 in  in OpenMP 6.0 spec. 
- list item in a reduction clause can now be private in the enclosing
context.
-  Added support for _original-sharing-modifier_  with reduction clause.

---------

Co-authored-by: Chandra Ghale <[email protected]>

Author: chandraghale

clang/docs/OpenMPSupport.rst

@@ -405,8 +405,8 @@ implementation.
 | Extensions to depobj construct                              | :none:`unclaimed`         | :none:`unclaimed`         |                                                                          |
 +-------------------------------------------------------------+---------------------------+---------------------------+--------------------------------------------------------------------------+
 | Extensions to atomic construct                              | :none:`unclaimed`         | :none:`unclaimed`         |                                                                          |
-+-------------------------------------------------------------+---------------------------+---------------------------+--------------------------------------------------------------------------+
-| Private reductions                                          | :none:`unclaimed`         | :none:`unclaimed`         |                                                                          |
++-------------------------------------------------------------+---------------------------+---------------------------+--------------------------------------------------------------------------+ 
+| Private reductions                                          | :part:`partial`           | :none:`unclaimed`         | Parse/Sema:https://github.com/llvm/llvm-project/pull/129938              |
 +-------------------------------------------------------------+---------------------------+---------------------------+--------------------------------------------------------------------------+
 | Self maps                                                   | :part:`partial`           | :none:`unclaimed`         | parsing/sema done: https://github.com/llvm/llvm-project/pull/129888      |
 +-------------------------------------------------------------+---------------------------+---------------------------+--------------------------------------------------------------------------+

clang/include/clang/AST/OpenMPClause.h

@@ -3701,14 +3701,18 @@ class OMPSharedClause final
 class OMPReductionClause final
     : public OMPVarListClause<OMPReductionClause>,
       public OMPClauseWithPostUpdate,
-      private llvm::TrailingObjects<OMPReductionClause, Expr *> {
+      private llvm::TrailingObjects<OMPReductionClause, Expr *, bool> {
   friend class OMPClauseReader;
   friend OMPVarListClause;
   friend TrailingObjects;
 
   /// Reduction modifier.
   OpenMPReductionClauseModifier Modifier = OMPC_REDUCTION_unknown;
 
+  /// Original Sharing  modifier.
+  OpenMPOriginalSharingModifier OriginalSharingModifier =
+      OMPC_ORIGINAL_SHARING_default;
+
   /// Reduction modifier location.
   SourceLocation ModifierLoc;
 
@@ -3734,12 +3738,14 @@ class OMPReductionClause final
   OMPReductionClause(SourceLocation StartLoc, SourceLocation LParenLoc,
                      SourceLocation ModifierLoc, SourceLocation ColonLoc,
                      SourceLocation EndLoc,
-                     OpenMPReductionClauseModifier Modifier, unsigned N,
-                     NestedNameSpecifierLoc QualifierLoc,
+                     OpenMPReductionClauseModifier Modifier,
+                     OpenMPOriginalSharingModifier OriginalSharingModifier,
+                     unsigned N, NestedNameSpecifierLoc QualifierLoc,
                      const DeclarationNameInfo &NameInfo)
       : OMPVarListClause<OMPReductionClause>(llvm::omp::OMPC_reduction,
                                              StartLoc, LParenLoc, EndLoc, N),
         OMPClauseWithPostUpdate(this), Modifier(Modifier),
+        OriginalSharingModifier(OriginalSharingModifier),
         ModifierLoc(ModifierLoc), ColonLoc(ColonLoc),
         QualifierLoc(QualifierLoc), NameInfo(NameInfo) {}
 
@@ -3755,6 +3761,11 @@ class OMPReductionClause final
   /// Sets reduction modifier.
   void setModifier(OpenMPReductionClauseModifier M) { Modifier = M; }
 
+  /// Sets Original Sharing  modifier.
+  void setOriginalSharingModifier(OpenMPOriginalSharingModifier M) {
+    OriginalSharingModifier = M;
+  }
+
   /// Sets location of the modifier.
   void setModifierLoc(SourceLocation Loc) { ModifierLoc = Loc; }
 
@@ -3800,6 +3811,31 @@ class OMPReductionClause final
   /// reduction copies.
   void setRHSExprs(ArrayRef<Expr *> RHSExprs);
 
+  /// Set the list private reduction flags
+  void setPrivateVariableReductionFlags(ArrayRef<bool> Flags) {
+    assert(Flags.size() == varlist_size() &&
+           "Number of private flags does not match vars");
+    llvm::copy(Flags, getTrailingObjects<bool>());
+  }
+
+  /// Get the list of help private variable reduction flags
+  MutableArrayRef<bool> getPrivateVariableReductionFlags() {
+    return MutableArrayRef(getTrailingObjects<bool>(), varlist_size());
+  }
+  ArrayRef<bool> getPrivateVariableReductionFlags() const {
+    return ArrayRef(getTrailingObjects<bool>(), varlist_size());
+  }
+
+  /// Returns the number of Expr* objects in trailing storage
+  size_t numTrailingObjects(OverloadToken<Expr *>) const {
+    return varlist_size() * (Modifier == OMPC_REDUCTION_inscan ? 8 : 5);
+  }
+
+  /// Returns the number of bool flags in trailing storage
+  size_t numTrailingObjects(OverloadToken<bool>) const {
+    return varlist_size();
+  }
+
   /// Get the list of helper destination expressions.
   MutableArrayRef<Expr *> getRHSExprs() {
     return MutableArrayRef<Expr *>(getLHSExprs().end(), varlist_size());
@@ -3897,6 +3933,7 @@ class OMPReductionClause final
   /// region with this clause.
   /// \param PostUpdate Expression that must be executed after exit from the
   /// OpenMP region with this clause.
+  /// \param IsPrivateVarReduction array for private variable reduction flags
   static OMPReductionClause *
   Create(const ASTContext &C, SourceLocation StartLoc, SourceLocation LParenLoc,
          SourceLocation ModifierLoc, SourceLocation ColonLoc,
@@ -3906,7 +3943,8 @@ 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,
+         OpenMPOriginalSharingModifier OriginalSharingModifier);
 
   /// Creates an empty clause with the place for \a N variables.
   ///
@@ -3920,6 +3958,11 @@ class OMPReductionClause final
   /// Returns modifier.
   OpenMPReductionClauseModifier getModifier() const { return Modifier; }
 
+  /// Returns Original Sharing Modifier.
+  OpenMPOriginalSharingModifier getOriginalSharingModifier() const {
+    return OriginalSharingModifier;
+  }
+
   /// Returns modifier location.
   SourceLocation getModifierLoc() const { return ModifierLoc; }
 
@@ -3937,6 +3980,11 @@ class OMPReductionClause final
   using helper_expr_range = llvm::iterator_range<helper_expr_iterator>;
   using helper_expr_const_range =
       llvm::iterator_range<helper_expr_const_iterator>;
+  using helper_flag_iterator = MutableArrayRef<bool>::iterator;
+  using helper_flag_const_iterator = ArrayRef<bool>::iterator;
+  using helper_flag_range = llvm::iterator_range<helper_flag_iterator>;
+  using helper_flag_const_range =
+      llvm::iterator_range<helper_flag_const_iterator>;
 
   helper_expr_const_range privates() const {
     return helper_expr_const_range(getPrivates().begin(), getPrivates().end());
@@ -3962,6 +4010,16 @@ class OMPReductionClause final
     return helper_expr_range(getRHSExprs().begin(), getRHSExprs().end());
   }
 
+  helper_flag_const_range private_var_reduction_flags() const {
+    return helper_flag_const_range(getPrivateVariableReductionFlags().begin(),
+                                   getPrivateVariableReductionFlags().end());
+  }
+
+  helper_flag_range private_var_reduction_flags() {
+    return helper_flag_range(getPrivateVariableReductionFlags().begin(),
+                             getPrivateVariableReductionFlags().end());
+  }
+
   helper_expr_const_range reduction_ops() const {
     return helper_expr_const_range(getReductionOps().begin(),
                                    getReductionOps().end());

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
@@ -203,6 +206,11 @@ 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)
@@ -234,6 +242,7 @@ 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

@@ -1146,6 +1146,7 @@ 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>
@@ -1155,6 +1156,7 @@ 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
@@ -1164,6 +1166,12 @@ class SemaOpenMP : public SemaBase {
     SmallVector<SourceLocation, NumberOfOMPAllocateClauseModifiers>
         AllocClauseModifiersLoc;
     Expr *AllocateAlignment = nullptr;
+    struct OpenMPReductionClauseModifiers {
+      int ExtraModifier;
+      int OriginalSharingModifier;
+      OpenMPReductionClauseModifiers(int Extra, int Original)
+          : ExtraModifier(Extra), OriginalSharingModifier(Original) {}
+    };
   };
 
   OMPClause *ActOnOpenMPVarListClause(OpenMPClauseKind Kind,
@@ -1212,7 +1220,8 @@ class SemaOpenMP : public SemaBase {
                                      SourceLocation EndLoc);
   /// Called on well-formed 'reduction' clause.
   OMPClause *ActOnOpenMPReductionClause(
-      ArrayRef<Expr *> VarList, OpenMPReductionClauseModifier Modifier,
+      ArrayRef<Expr *> VarList,
+      OpenMPVarListDataTy::OpenMPReductionClauseModifiers Modifiers,
       SourceLocation StartLoc, SourceLocation LParenLoc,
       SourceLocation ModifierLoc, SourceLocation ColonLoc,
       SourceLocation EndLoc, CXXScopeSpec &ReductionIdScopeSpec,

clang/lib/AST/OpenMPClause.cpp

@@ -799,19 +799,22 @@ 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) {
-  void *Mem = C.Allocate(totalSizeToAlloc<Expr *>(
-      (Modifier == OMPC_REDUCTION_inscan ? 8 : 5) * VL.size()));
-  auto *Clause = new (Mem)
-      OMPReductionClause(StartLoc, LParenLoc, ModifierLoc, EndLoc, ColonLoc,
-                         Modifier, VL.size(), QualifierLoc, NameInfo);
+    ArrayRef<Expr *> CopyArrayElems, Stmt *PreInit, Expr *PostUpdate,
+    ArrayRef<bool> IsPrivateVarReduction,
+    OpenMPOriginalSharingModifier OrignalSharingModifier) {
+  void *Mem = C.Allocate(totalSizeToAlloc<Expr *, bool>(
+      (Modifier == OMPC_REDUCTION_inscan ? 8 : 5) * VL.size(), VL.size()));
+  auto *Clause = new (Mem) OMPReductionClause(
+      StartLoc, LParenLoc, ModifierLoc, EndLoc, ColonLoc, Modifier,
+      OrignalSharingModifier, VL.size(), QualifierLoc, NameInfo);
   Clause->setVarRefs(VL);
   Clause->setPrivates(Privates);
   Clause->setLHSExprs(LHSExprs);
   Clause->setRHSExprs(RHSExprs);
   Clause->setReductionOps(ReductionOps);
   Clause->setPreInitStmt(PreInit);
   Clause->setPostUpdateExpr(PostUpdate);
+  Clause->setPrivateVariableReductionFlags(IsPrivateVarReduction);
   if (Modifier == OMPC_REDUCTION_inscan) {
     Clause->setInscanCopyOps(CopyOps);
     Clause->setInscanCopyArrayTemps(CopyArrayTemps);
@@ -830,8 +833,8 @@ OMPReductionClause *OMPReductionClause::Create(
 OMPReductionClause *
 OMPReductionClause::CreateEmpty(const ASTContext &C, unsigned N,
                                 OpenMPReductionClauseModifier Modifier) {
-  void *Mem = C.Allocate(totalSizeToAlloc<Expr *>(
-      (Modifier == OMPC_REDUCTION_inscan ? 8 : 5) * N));
+  void *Mem = C.Allocate(totalSizeToAlloc<Expr *, bool>(
+      (Modifier == OMPC_REDUCTION_inscan ? 8 : 5) * N, N));
   auto *Clause = new (Mem) OMPReductionClause(N);
   Clause->setModifier(Modifier);
   return Clause;

clang/lib/Parse/ParseOpenMP.cpp

@@ -4706,6 +4706,37 @@ 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();
+      if (!Tok.is(tok::comma)) {
+        Diag(Tok.getLocation(), diag::err_expected) << "',' (comma)";
+        return false;
+      }
+      (void)ConsumeToken();
+    }
     ColonProtectionRAIIObject ColonRAII(*this);
     if (getLangOpts().CPlusPlus)
       ParseOptionalCXXScopeSpecifier(Data.ReductionOrMapperIdScopeSpec,