[Clang][Sema][OpenMP] Allow thread_limit to accept multiple express…

…ions (#102715)

clang/docs/OpenMPSupport.rst

@@ -363,7 +363,8 @@ considered for standardization. Please post on the
 | device extension             | `'ompx_bare' clause on 'target teams' construct                                   | :good:`prototyped`       | #66844, #70612                                         |
 |                              | <https://www.osti.gov/servlets/purl/2205717>`_                                    |                          |                                                        |
 +------------------------------+-----------------------------------------------------------------------------------+--------------------------+--------------------------------------------------------+
-| device extension             | Multi-dim 'num_teams' clause on 'target teams ompx_bare' construct                | :good:`partial`          | #99732, #101407                                        |
+| device extension             | Multi-dim 'num_teams' and 'thread_limit' clause on 'target teams ompx_bare'       | :good:`partial`          | #99732, #101407, #102715                               |
+|                              | construct                                                                         |                          |                                                        |
 +------------------------------+-----------------------------------------------------------------------------------+--------------------------+--------------------------------------------------------+
 
 .. _Discourse forums (Runtimes - OpenMP category): https://discourse.llvm.org/c/runtimes/openmp/35

clang/docs/ReleaseNotes.rst

@@ -360,8 +360,9 @@ Improvements
 ^^^^^^^^^^^^
 - Improve the handling of mapping array-section for struct containing nested structs with user defined mappers
 
-- `num_teams` now accepts multiple expressions when it is used along in ``target teams ompx_bare`` construct.
-  This allows the target region to be launched with multi-dim grid on GPUs.
+- `num_teams` and `thead_limit` now accept multiple expressions when it is used
+  along in ``target teams ompx_bare`` construct. This allows the target region
+  to be launched with multi-dim grid on GPUs.
 
 Additional Information
 ======================

clang/include/clang/AST/OpenMPClause.h

@@ -6462,61 +6462,78 @@ class OMPNumTeamsClause final
 /// \endcode
 /// In this example directive '#pragma omp teams' has clause 'thread_limit'
 /// with single expression 'n'.
-class OMPThreadLimitClause : public OMPClause, public OMPClauseWithPreInit {
-  friend class OMPClauseReader;
+///
+/// When 'ompx_bare' clause exists on a 'target' directive, 'thread_limit'
+/// clause can accept up to three expressions.
+///
+/// \code
+/// #pragma omp target teams ompx_bare thread_limit(x, y, z)
+/// \endcode
+class OMPThreadLimitClause final
+    : public OMPVarListClause<OMPThreadLimitClause>,
+      public OMPClauseWithPreInit,
+      private llvm::TrailingObjects<OMPThreadLimitClause, Expr *> {
+  friend OMPVarListClause;
+  friend TrailingObjects;
 
   /// Location of '('.
   SourceLocation LParenLoc;
 
-  /// ThreadLimit number.
-  Stmt *ThreadLimit = nullptr;
+  OMPThreadLimitClause(const ASTContext &C, SourceLocation StartLoc,
+                       SourceLocation LParenLoc, SourceLocation EndLoc,
+                       unsigned N)
+      : OMPVarListClause(llvm::omp::OMPC_thread_limit, StartLoc, LParenLoc,
+                         EndLoc, N),
+        OMPClauseWithPreInit(this) {}
 
-  /// Set the ThreadLimit number.
-  ///
-  /// \param E ThreadLimit number.
-  void setThreadLimit(Expr *E) { ThreadLimit = E; }
+  /// Build an empty clause.
+  OMPThreadLimitClause(unsigned N)
+      : OMPVarListClause(llvm::omp::OMPC_thread_limit, SourceLocation(),
+                         SourceLocation(), SourceLocation(), N),
+        OMPClauseWithPreInit(this) {}
 
 public:
-  /// Build 'thread_limit' clause.
+  /// Creates clause with a list of variables \a VL.
   ///
-  /// \param E Expression associated with this clause.
-  /// \param HelperE Helper Expression associated with this clause.
-  /// \param CaptureRegion Innermost OpenMP region where expressions in this
-  /// clause must be captured.
+  /// \param C AST context.
   /// \param StartLoc Starting location of the clause.
   /// \param LParenLoc Location of '('.
   /// \param EndLoc Ending location of the clause.
-  OMPThreadLimitClause(Expr *E, Stmt *HelperE,
-                       OpenMPDirectiveKind CaptureRegion,
-                       SourceLocation StartLoc, SourceLocation LParenLoc,
-                       SourceLocation EndLoc)
-      : OMPClause(llvm::omp::OMPC_thread_limit, StartLoc, EndLoc),
-        OMPClauseWithPreInit(this), LParenLoc(LParenLoc), ThreadLimit(E) {
-    setPreInitStmt(HelperE, CaptureRegion);
-  }
+  /// \param VL List of references to the variables.
+  /// \param PreInit
+  static OMPThreadLimitClause *
+  Create(const ASTContext &C, OpenMPDirectiveKind CaptureRegion,
+         SourceLocation StartLoc, SourceLocation LParenLoc,
+         SourceLocation EndLoc, ArrayRef<Expr *> VL, Stmt *PreInit);
 
-  /// Build an empty clause.
-  OMPThreadLimitClause()
-      : OMPClause(llvm::omp::OMPC_thread_limit, SourceLocation(),
-                  SourceLocation()),
-        OMPClauseWithPreInit(this) {}
+  /// Creates an empty clause with \a N variables.
+  ///
+  /// \param C AST context.
+  /// \param N The number of variables.
+  static OMPThreadLimitClause *CreateEmpty(const ASTContext &C, unsigned N);
 
   /// Sets the location of '('.
   void setLParenLoc(SourceLocation Loc) { LParenLoc = Loc; }
 
   /// Returns the location of '('.
   SourceLocation getLParenLoc() const { return LParenLoc; }
 
-  /// Return ThreadLimit number.
-  Expr *getThreadLimit() { return cast<Expr>(ThreadLimit); }
+  /// Return ThreadLimit expressions.
+  ArrayRef<Expr *> getThreadLimit() { return getVarRefs(); }
 
-  /// Return ThreadLimit number.
-  Expr *getThreadLimit() const { return cast<Expr>(ThreadLimit); }
+  /// Return ThreadLimit expressions.
+  ArrayRef<Expr *> getThreadLimit() const {
+    return const_cast<OMPThreadLimitClause *>(this)->getThreadLimit();
+  }
 
-  child_range children() { return child_range(&ThreadLimit, &ThreadLimit + 1); }
+  child_range children() {
+    return child_range(reinterpret_cast<Stmt **>(varlist_begin()),
+                       reinterpret_cast<Stmt **>(varlist_end()));
+  }
 
   const_child_range children() const {
-    return const_child_range(&ThreadLimit, &ThreadLimit + 1);
+    auto Children = const_cast<OMPThreadLimitClause *>(this)->children();
+    return const_child_range(Children.begin(), Children.end());
   }
 
   child_range used_children() {

clang/include/clang/AST/RecursiveASTVisitor.h

@@ -3836,8 +3836,8 @@ bool RecursiveASTVisitor<Derived>::VisitOMPNumTeamsClause(
 template <typename Derived>
 bool RecursiveASTVisitor<Derived>::VisitOMPThreadLimitClause(
     OMPThreadLimitClause *C) {
+  TRY_TO(VisitOMPClauseList(C));
   TRY_TO(VisitOMPClauseWithPreInit(C));
-  TRY_TO(TraverseStmt(C->getThreadLimit()));
   return true;
 }
 

clang/include/clang/Sema/SemaOpenMP.h

@@ -1264,7 +1264,7 @@ class SemaOpenMP : public SemaBase {
                                        SourceLocation LParenLoc,
                                        SourceLocation EndLoc);
   /// Called on well-formed 'thread_limit' clause.
-  OMPClause *ActOnOpenMPThreadLimitClause(Expr *ThreadLimit,
+  OMPClause *ActOnOpenMPThreadLimitClause(ArrayRef<Expr *> VarList,
                                           SourceLocation StartLoc,
                                           SourceLocation LParenLoc,
                                           SourceLocation EndLoc);

clang/lib/AST/OpenMPClause.cpp

@@ -1773,6 +1773,24 @@ OMPNumTeamsClause *OMPNumTeamsClause::CreateEmpty(const ASTContext &C,
   return new (Mem) OMPNumTeamsClause(N);
 }
 
+OMPThreadLimitClause *OMPThreadLimitClause::Create(
+    const ASTContext &C, OpenMPDirectiveKind CaptureRegion,
+    SourceLocation StartLoc, SourceLocation LParenLoc, SourceLocation EndLoc,
+    ArrayRef<Expr *> VL, Stmt *PreInit) {
+  void *Mem = C.Allocate(totalSizeToAlloc<Expr *>(VL.size()));
+  OMPThreadLimitClause *Clause =
+      new (Mem) OMPThreadLimitClause(C, StartLoc, LParenLoc, EndLoc, VL.size());
+  Clause->setVarRefs(VL);
+  Clause->setPreInitStmt(PreInit, CaptureRegion);
+  return Clause;
+}
+
+OMPThreadLimitClause *OMPThreadLimitClause::CreateEmpty(const ASTContext &C,
+                                                        unsigned N) {
+  void *Mem = C.Allocate(totalSizeToAlloc<Expr *>(N));
+  return new (Mem) OMPThreadLimitClause(N);
+}
+
 //===----------------------------------------------------------------------===//
 //  OpenMP clauses printing methods
 //===----------------------------------------------------------------------===//
@@ -2081,9 +2099,11 @@ void OMPClausePrinter::VisitOMPNumTeamsClause(OMPNumTeamsClause *Node) {
 }
 
 void OMPClausePrinter::VisitOMPThreadLimitClause(OMPThreadLimitClause *Node) {
-  OS << "thread_limit(";
-  Node->getThreadLimit()->printPretty(OS, nullptr, Policy, 0);
-  OS << ")";
+  if (!Node->varlist_empty()) {
+    OS << "thread_limit";
+    VisitOMPClauseList(Node, '(');
+    OS << ")";
+  }
 }
 
 void OMPClausePrinter::VisitOMPPriorityClause(OMPPriorityClause *Node) {

clang/lib/AST/StmtProfile.cpp

@@ -862,9 +862,8 @@ void OMPClauseProfiler::VisitOMPNumTeamsClause(const OMPNumTeamsClause *C) {
 }
 void OMPClauseProfiler::VisitOMPThreadLimitClause(
     const OMPThreadLimitClause *C) {
+  VisitOMPClauseList(C);
   VistOMPClauseWithPreInit(C);
-  if (C->getThreadLimit())
-    Profiler->VisitStmt(C->getThreadLimit());
 }
 void OMPClauseProfiler::VisitOMPPriorityClause(const OMPPriorityClause *C) {
   VistOMPClauseWithPreInit(C);

clang/lib/CodeGen/CGOpenMPRuntime.cpp

@@ -6332,7 +6332,8 @@ const Expr *CGOpenMPRuntime::getNumThreadsExprForTargetDirective(
           CGOpenMPInnerExprInfo CGInfo(CGF, *CS);
           CodeGenFunction::CGCapturedStmtRAII CapInfoRAII(CGF, &CGInfo);
           CodeGenFunction::LexicalScope Scope(
-              CGF, ThreadLimitClause->getThreadLimit()->getSourceRange());
+              CGF,
+              ThreadLimitClause->getThreadLimit().front()->getSourceRange());
           if (const auto *PreInit =
                   cast_or_null<DeclStmt>(ThreadLimitClause->getPreInitStmt())) {
             for (const auto *I : PreInit->decls()) {
@@ -6349,7 +6350,8 @@ const Expr *CGOpenMPRuntime::getNumThreadsExprForTargetDirective(
       }
     }
     if (ThreadLimitClause)
-      CheckForConstExpr(ThreadLimitClause->getThreadLimit(), ThreadLimitExpr);
+      CheckForConstExpr(ThreadLimitClause->getThreadLimit().front(),
+                        ThreadLimitExpr);
     if (const auto *Dir = dyn_cast_or_null<OMPExecutableDirective>(Child)) {
       if (isOpenMPTeamsDirective(Dir->getDirectiveKind()) &&
           !isOpenMPDistributeDirective(Dir->getDirectiveKind())) {
@@ -6370,7 +6372,8 @@ const Expr *CGOpenMPRuntime::getNumThreadsExprForTargetDirective(
     if (D.hasClausesOfKind<OMPThreadLimitClause>()) {
       CodeGenFunction::RunCleanupsScope ThreadLimitScope(CGF);
       const auto *ThreadLimitClause = D.getSingleClause<OMPThreadLimitClause>();
-      CheckForConstExpr(ThreadLimitClause->getThreadLimit(), ThreadLimitExpr);
+      CheckForConstExpr(ThreadLimitClause->getThreadLimit().front(),
+                        ThreadLimitExpr);
     }
     const CapturedStmt *CS = D.getInnermostCapturedStmt();
     getNumThreads(CGF, CS, NTPtr, UpperBound, UpperBoundOnly, CondVal);
@@ -6388,7 +6391,8 @@ const Expr *CGOpenMPRuntime::getNumThreadsExprForTargetDirective(
     if (D.hasClausesOfKind<OMPThreadLimitClause>()) {
       CodeGenFunction::RunCleanupsScope ThreadLimitScope(CGF);
       const auto *ThreadLimitClause = D.getSingleClause<OMPThreadLimitClause>();
-      CheckForConstExpr(ThreadLimitClause->getThreadLimit(), ThreadLimitExpr);
+      CheckForConstExpr(ThreadLimitClause->getThreadLimit().front(),
+                        ThreadLimitExpr);
     }
     getNumThreads(CGF, D.getInnermostCapturedStmt(), NTPtr, UpperBound,
                   UpperBoundOnly, CondVal);
@@ -6424,7 +6428,8 @@ const Expr *CGOpenMPRuntime::getNumThreadsExprForTargetDirective(
     if (D.hasClausesOfKind<OMPThreadLimitClause>()) {
       CodeGenFunction::RunCleanupsScope ThreadLimitScope(CGF);
       const auto *ThreadLimitClause = D.getSingleClause<OMPThreadLimitClause>();
-      CheckForConstExpr(ThreadLimitClause->getThreadLimit(), ThreadLimitExpr);
+      CheckForConstExpr(ThreadLimitClause->getThreadLimit().front(),
+                        ThreadLimitExpr);
     }
     if (D.hasClausesOfKind<OMPNumThreadsClause>()) {
       CodeGenFunction::RunCleanupsScope NumThreadsScope(CGF);

clang/lib/CodeGen/CGStmtOpenMP.cpp

@@ -5259,7 +5259,7 @@ void CodeGenFunction::EmitOMPTargetTaskBasedDirective(
       // enclosing this target region. This will indirectly set the thread_limit
       // for every applicable construct within target region.
       CGF.CGM.getOpenMPRuntime().emitThreadLimitClause(
-          CGF, TL->getThreadLimit(), S.getBeginLoc());
+          CGF, TL->getThreadLimit().front(), S.getBeginLoc());
     }
     BodyGen(CGF);
   };
@@ -6860,7 +6860,7 @@ static void emitCommonOMPTeamsDirective(CodeGenFunction &CGF,
   const auto *TL = S.getSingleClause<OMPThreadLimitClause>();
   if (NT || TL) {
     const Expr *NumTeams = NT ? NT->getNumTeams().front() : nullptr;
-    const Expr *ThreadLimit = TL ? TL->getThreadLimit() : nullptr;
+    const Expr *ThreadLimit = TL ? TL->getThreadLimit().front() : nullptr;
 
     CGF.CGM.getOpenMPRuntime().emitNumTeamsClause(CGF, NumTeams, ThreadLimit,
                                                   S.getBeginLoc());

clang/lib/Parse/ParseOpenMP.cpp

@@ -3175,7 +3175,6 @@ OMPClause *Parser::ParseOpenMPClause(OpenMPDirectiveKind DKind,
   case OMPC_simdlen:
   case OMPC_collapse:
   case OMPC_ordered:
-  case OMPC_thread_limit:
   case OMPC_priority:
   case OMPC_grainsize:
   case OMPC_num_tasks:
@@ -3332,6 +3331,7 @@ OMPClause *Parser::ParseOpenMPClause(OpenMPDirectiveKind DKind,
                  : ParseOpenMPClause(CKind, WrongDirective);
     break;
   case OMPC_num_teams:
+  case OMPC_thread_limit:
     if (!FirstClause) {
       Diag(Tok, diag::err_omp_more_one_clause)
           << getOpenMPDirectiveName(DKind) << getOpenMPClauseName(CKind) << 0;