[OpenMP][clang] 6.0: parsing/sema for num_threads 'strict' modifier (#145490)

Implement parsing and semantic analysis support for the optional
'strict' modifier of the num_threads clause. This modifier has been
introduced in OpenMP 6.0, section 12.1.2.

Note: this is basically 1:1 https://reviews.llvm.org/D138328.

Author: ro-i

clang/include/clang/AST/OpenMPClause.h

@@ -824,31 +824,52 @@ class OMPNumThreadsClause final
       public OMPClauseWithPreInit {
   friend class OMPClauseReader;
 
+  /// Modifiers for 'num_threads' clause.
+  OpenMPNumThreadsClauseModifier Modifier = OMPC_NUMTHREADS_unknown;
+
+  /// Location of the modifier.
+  SourceLocation ModifierLoc;
+
+  /// Sets modifier.
+  void setModifier(OpenMPNumThreadsClauseModifier M) { Modifier = M; }
+
+  /// Sets modifier location.
+  void setModifierLoc(SourceLocation Loc) { ModifierLoc = Loc; }
+
   /// Set condition.
   void setNumThreads(Expr *NThreads) { setStmt(NThreads); }
 
 public:
   /// Build 'num_threads' clause with condition \a NumThreads.
   ///
+  /// \param Modifier Clause modifier.
   /// \param NumThreads Number of threads for the construct.
   /// \param HelperNumThreads Helper Number of threads for the construct.
   /// \param CaptureRegion Innermost OpenMP region where expressions in this
   /// clause must be captured.
   /// \param StartLoc Starting location of the clause.
   /// \param LParenLoc Location of '('.
+  /// \param ModifierLoc Modifier location.
   /// \param EndLoc Ending location of the clause.
-  OMPNumThreadsClause(Expr *NumThreads, Stmt *HelperNumThreads,
-                      OpenMPDirectiveKind CaptureRegion,
+  OMPNumThreadsClause(OpenMPNumThreadsClauseModifier Modifier, Expr *NumThreads,
+                      Stmt *HelperNumThreads, OpenMPDirectiveKind CaptureRegion,
                       SourceLocation StartLoc, SourceLocation LParenLoc,
-                      SourceLocation EndLoc)
+                      SourceLocation ModifierLoc, SourceLocation EndLoc)
       : OMPOneStmtClause(NumThreads, StartLoc, LParenLoc, EndLoc),
-        OMPClauseWithPreInit(this) {
+        OMPClauseWithPreInit(this), Modifier(Modifier),
+        ModifierLoc(ModifierLoc) {
     setPreInitStmt(HelperNumThreads, CaptureRegion);
   }
 
   /// Build an empty clause.
   OMPNumThreadsClause() : OMPOneStmtClause(), OMPClauseWithPreInit(this) {}
 
+  /// Gets modifier.
+  OpenMPNumThreadsClauseModifier getModifier() const { return Modifier; }
+
+  /// Gets modifier location.
+  SourceLocation getModifierLoc() const { return ModifierLoc; }
+
   /// Returns number of threads.
   Expr *getNumThreads() const { return getStmtAs<Expr>(); }
 };

clang/include/clang/Basic/OpenMPKinds.def

@@ -86,6 +86,9 @@
 #ifndef OPENMP_NUMTASKS_MODIFIER
 #define OPENMP_NUMTASKS_MODIFIER(Name)
 #endif
+#ifndef OPENMP_NUMTHREADS_MODIFIER
+#define OPENMP_NUMTHREADS_MODIFIER(Name)
+#endif
 #ifndef OPENMP_DOACROSS_MODIFIER
 #define OPENMP_DOACROSS_MODIFIER(Name)
 #endif
@@ -227,6 +230,9 @@ OPENMP_GRAINSIZE_MODIFIER(strict)
 // Modifiers for the 'num_tasks' clause.
 OPENMP_NUMTASKS_MODIFIER(strict)
 
+// Modifiers for the 'num_tasks' clause.
+OPENMP_NUMTHREADS_MODIFIER(strict)
+
 // Modifiers for 'allocate' clause.
 OPENMP_ALLOCATE_MODIFIER(allocator)
 OPENMP_ALLOCATE_MODIFIER(align)
@@ -238,6 +244,7 @@ OPENMP_DOACROSS_MODIFIER(sink_omp_cur_iteration)
 OPENMP_DOACROSS_MODIFIER(source_omp_cur_iteration)
 
 #undef OPENMP_NUMTASKS_MODIFIER
+#undef OPENMP_NUMTHREADS_MODIFIER
 #undef OPENMP_GRAINSIZE_MODIFIER
 #undef OPENMP_BIND_KIND
 #undef OPENMP_ADJUST_ARGS_KIND

clang/include/clang/Basic/OpenMPKinds.h

@@ -223,6 +223,12 @@ enum OpenMPNumTasksClauseModifier {
   OMPC_NUMTASKS_unknown
 };
 
+enum OpenMPNumThreadsClauseModifier {
+#define OPENMP_NUMTHREADS_MODIFIER(Name) OMPC_NUMTHREADS_##Name,
+#include "clang/Basic/OpenMPKinds.def"
+  OMPC_NUMTHREADS_unknown
+};
+
 /// OpenMP dependence types for 'doacross' clause.
 enum OpenMPDoacrossClauseModifier {
 #define OPENMP_DOACROSS_MODIFIER(Name) OMPC_DOACROSS_##Name,

clang/include/clang/Sema/SemaOpenMP.h

@@ -877,10 +877,10 @@ class SemaOpenMP : public SemaBase {
                                     SourceLocation LParenLoc,
                                     SourceLocation EndLoc);
   /// Called on well-formed 'num_threads' clause.
-  OMPClause *ActOnOpenMPNumThreadsClause(Expr *NumThreads,
-                                         SourceLocation StartLoc,
-                                         SourceLocation LParenLoc,
-                                         SourceLocation EndLoc);
+  OMPClause *ActOnOpenMPNumThreadsClause(
+      OpenMPNumThreadsClauseModifier Modifier, Expr *NumThreads,
+      SourceLocation StartLoc, SourceLocation LParenLoc,
+      SourceLocation ModifierLoc, SourceLocation EndLoc);
   /// Called on well-formed 'align' clause.
   OMPClause *ActOnOpenMPAlignClause(Expr *Alignment, SourceLocation StartLoc,
                                     SourceLocation LParenLoc,

clang/lib/AST/OpenMPClause.cpp

@@ -1830,6 +1830,11 @@ void OMPClausePrinter::VisitOMPFinalClause(OMPFinalClause *Node) {
 
 void OMPClausePrinter::VisitOMPNumThreadsClause(OMPNumThreadsClause *Node) {
   OS << "num_threads(";
+  OpenMPNumThreadsClauseModifier Modifier = Node->getModifier();
+  if (Modifier != OMPC_NUMTHREADS_unknown) {
+    OS << getOpenMPSimpleClauseTypeName(Node->getClauseKind(), Modifier)
+       << ": ";
+  }
   Node->getNumThreads()->printPretty(OS, nullptr, Policy, 0);
   OS << ")";
 }

clang/lib/Basic/OpenMPKinds.cpp

@@ -185,11 +185,19 @@ unsigned clang::getOpenMPSimpleClauseType(OpenMPClauseKind Kind, StringRef Str,
 #define OPENMP_ALLOCATE_MODIFIER(Name) .Case(#Name, OMPC_ALLOCATE_##Name)
 #include "clang/Basic/OpenMPKinds.def"
         .Default(OMPC_ALLOCATE_unknown);
+  case OMPC_num_threads: {
+    unsigned Type = llvm::StringSwitch<unsigned>(Str)
+#define OPENMP_NUMTHREADS_MODIFIER(Name) .Case(#Name, OMPC_NUMTHREADS_##Name)
+#include "clang/Basic/OpenMPKinds.def"
+                        .Default(OMPC_NUMTHREADS_unknown);
+    if (LangOpts.OpenMP < 60)
+      return OMPC_NUMTHREADS_unknown;
+    return Type;
+  }
   case OMPC_unknown:
   case OMPC_threadprivate:
   case OMPC_if:
   case OMPC_final:
-  case OMPC_num_threads:
   case OMPC_safelen:
   case OMPC_simdlen:
   case OMPC_sizes:
@@ -520,11 +528,20 @@ const char *clang::getOpenMPSimpleClauseTypeName(OpenMPClauseKind Kind,
 #include "clang/Basic/OpenMPKinds.def"
     }
     llvm_unreachable("Invalid OpenMP 'allocate' clause modifier");
+  case OMPC_num_threads:
+    switch (Type) {
+    case OMPC_NUMTHREADS_unknown:
+      return "unknown";
+#define OPENMP_NUMTHREADS_MODIFIER(Name)                                       \
+  case OMPC_NUMTHREADS_##Name:                                                 \
+    return #Name;
+#include "clang/Basic/OpenMPKinds.def"
+    }
+    llvm_unreachable("Invalid OpenMP 'num_threads' clause modifier");
   case OMPC_unknown:
   case OMPC_threadprivate:
   case OMPC_if:
   case OMPC_final:
-  case OMPC_num_threads:
   case OMPC_safelen:
   case OMPC_simdlen:
   case OMPC_sizes:

clang/lib/Parse/ParseOpenMP.cpp

@@ -3196,7 +3196,8 @@ OMPClause *Parser::ParseOpenMPClause(OpenMPDirectiveKind DKind,
     if ((CKind == OMPC_ordered || CKind == OMPC_partial) &&
         PP.LookAhead(/*N=*/0).isNot(tok::l_paren))
       Clause = ParseOpenMPClause(CKind, WrongDirective);
-    else if (CKind == OMPC_grainsize || CKind == OMPC_num_tasks)
+    else if (CKind == OMPC_grainsize || CKind == OMPC_num_tasks ||
+             CKind == OMPC_num_threads)
       Clause = ParseOpenMPSingleExprWithArgClause(DKind, CKind, WrongDirective);
     else
       Clause = ParseOpenMPSingleExprClause(CKind, WrongDirective);
@@ -3981,6 +3982,33 @@ OMPClause *Parser::ParseOpenMPSingleExprWithArgClause(OpenMPDirectiveKind DKind,
       Arg.push_back(OMPC_NUMTASKS_unknown);
       KLoc.emplace_back();
     }
+  } else if (Kind == OMPC_num_threads) {
+    // Parse optional <num_threads modifier> ':'
+    OpenMPNumThreadsClauseModifier Modifier =
+        static_cast<OpenMPNumThreadsClauseModifier>(getOpenMPSimpleClauseType(
+            Kind, Tok.isAnnotation() ? "" : PP.getSpelling(Tok),
+            getLangOpts()));
+    if (getLangOpts().OpenMP >= 60) {
+      if (NextToken().is(tok::colon)) {
+        Arg.push_back(Modifier);
+        KLoc.push_back(Tok.getLocation());
+        // Parse modifier
+        ConsumeAnyToken();
+        // Parse ':'
+        ConsumeAnyToken();
+      } else {
+        if (Modifier == OMPC_NUMTHREADS_strict) {
+          Diag(Tok, diag::err_modifier_expected_colon) << "strict";
+          // Parse modifier
+          ConsumeAnyToken();
+        }
+        Arg.push_back(OMPC_NUMTHREADS_unknown);
+        KLoc.emplace_back();
+      }
+    } else {
+      Arg.push_back(OMPC_NUMTHREADS_unknown);
+      KLoc.emplace_back();
+    }
   } else {
     assert(Kind == OMPC_if);
     KLoc.push_back(Tok.getLocation());
@@ -4004,7 +4032,8 @@ OMPClause *Parser::ParseOpenMPSingleExprWithArgClause(OpenMPDirectiveKind DKind,
   bool NeedAnExpression = (Kind == OMPC_schedule && DelimLoc.isValid()) ||
                           (Kind == OMPC_dist_schedule && DelimLoc.isValid()) ||
                           Kind == OMPC_if || Kind == OMPC_device ||
-                          Kind == OMPC_grainsize || Kind == OMPC_num_tasks;
+                          Kind == OMPC_grainsize || Kind == OMPC_num_tasks ||
+                          Kind == OMPC_num_threads;
   if (NeedAnExpression) {
     SourceLocation ELoc = Tok.getLocation();
     ExprResult LHS(ParseCastExpression(CastParseKind::AnyCastExpr, false,

clang/lib/Sema/SemaOpenMP.cpp

@@ -15509,9 +15509,6 @@ OMPClause *SemaOpenMP::ActOnOpenMPSingleExprClause(OpenMPClauseKind Kind,
   case OMPC_final:
     Res = ActOnOpenMPFinalClause(Expr, StartLoc, LParenLoc, EndLoc);
     break;
-  case OMPC_num_threads:
-    Res = ActOnOpenMPNumThreadsClause(Expr, StartLoc, LParenLoc, EndLoc);
-    break;
   case OMPC_safelen:
     Res = ActOnOpenMPSafelenClause(Expr, StartLoc, LParenLoc, EndLoc);
     break;
@@ -15565,6 +15562,7 @@ OMPClause *SemaOpenMP::ActOnOpenMPSingleExprClause(OpenMPClauseKind Kind,
     break;
   case OMPC_grainsize:
   case OMPC_num_tasks:
+  case OMPC_num_threads:
   case OMPC_device:
   case OMPC_if:
   case OMPC_default:
@@ -15911,10 +15909,41 @@ isNonNegativeIntegerValue(Expr *&ValExpr, Sema &SemaRef, OpenMPClauseKind CKind,
   return true;
 }
 
-OMPClause *SemaOpenMP::ActOnOpenMPNumThreadsClause(Expr *NumThreads,
-                                                   SourceLocation StartLoc,
-                                                   SourceLocation LParenLoc,
-                                                   SourceLocation EndLoc) {
+static std::string getListOfPossibleValues(OpenMPClauseKind K, unsigned First,
+                                           unsigned Last,
+                                           ArrayRef<unsigned> Exclude = {}) {
+  SmallString<256> Buffer;
+  llvm::raw_svector_ostream Out(Buffer);
+  unsigned Skipped = Exclude.size();
+  for (unsigned I = First; I < Last; ++I) {
+    if (llvm::is_contained(Exclude, I)) {
+      --Skipped;
+      continue;
+    }
+    Out << "'" << getOpenMPSimpleClauseTypeName(K, I) << "'";
+    if (I + Skipped + 2 == Last)
+      Out << " or ";
+    else if (I + Skipped + 1 != Last)
+      Out << ", ";
+  }
+  return std::string(Out.str());
+}
+
+OMPClause *SemaOpenMP::ActOnOpenMPNumThreadsClause(
+    OpenMPNumThreadsClauseModifier Modifier, Expr *NumThreads,
+    SourceLocation StartLoc, SourceLocation LParenLoc,
+    SourceLocation ModifierLoc, SourceLocation EndLoc) {
+  assert((ModifierLoc.isInvalid() || getLangOpts().OpenMP >= 60) &&
+         "Unexpected num_threads modifier in OpenMP < 60.");
+
+  if (ModifierLoc.isValid() && Modifier == OMPC_NUMTHREADS_unknown) {
+    std::string Values = getListOfPossibleValues(OMPC_num_threads, /*First=*/0,
+                                                 OMPC_NUMTHREADS_unknown);
+    Diag(ModifierLoc, diag::err_omp_unexpected_clause_value)
+        << Values << getOpenMPClauseNameForDiag(OMPC_num_threads);
+    return nullptr;
+  }
+
   Expr *ValExpr = NumThreads;
   Stmt *HelperValStmt = nullptr;
 
@@ -15935,8 +15964,9 @@ OMPClause *SemaOpenMP::ActOnOpenMPNumThreadsClause(Expr *NumThreads,
     HelperValStmt = buildPreInits(getASTContext(), Captures);
   }
 
-  return new (getASTContext()) OMPNumThreadsClause(
-      ValExpr, HelperValStmt, CaptureRegion, StartLoc, LParenLoc, EndLoc);
+  return new (getASTContext())
+      OMPNumThreadsClause(Modifier, ValExpr, HelperValStmt, CaptureRegion,
+                          StartLoc, LParenLoc, ModifierLoc, EndLoc);
 }
 
 ExprResult SemaOpenMP::VerifyPositiveIntegerConstantInClause(
@@ -16301,26 +16331,6 @@ OMPClause *SemaOpenMP::ActOnOpenMPSimpleClause(
   return Res;
 }
 
-static std::string getListOfPossibleValues(OpenMPClauseKind K, unsigned First,
-                                           unsigned Last,
-                                           ArrayRef<unsigned> Exclude = {}) {
-  SmallString<256> Buffer;
-  llvm::raw_svector_ostream Out(Buffer);
-  unsigned Skipped = Exclude.size();
-  for (unsigned I = First; I < Last; ++I) {
-    if (llvm::is_contained(Exclude, I)) {
-      --Skipped;
-      continue;
-    }
-    Out << "'" << getOpenMPSimpleClauseTypeName(K, I) << "'";
-    if (I + Skipped + 2 == Last)
-      Out << " or ";
-    else if (I + Skipped + 1 != Last)
-      Out << ", ";
-  }
-  return std::string(Out.str());
-}
-
 OMPClause *SemaOpenMP::ActOnOpenMPDefaultClause(DefaultKind Kind,
                                                 SourceLocation KindKwLoc,
                                                 SourceLocation StartLoc,
@@ -16693,8 +16703,14 @@ OMPClause *SemaOpenMP::ActOnOpenMPSingleExprWithArgClause(
         static_cast<OpenMPNumTasksClauseModifier>(Argument.back()), Expr,
         StartLoc, LParenLoc, ArgumentLoc.back(), EndLoc);
     break;
-  case OMPC_final:
   case OMPC_num_threads:
+    assert(Argument.size() == 1 && ArgumentLoc.size() == 1 &&
+           "Modifier for num_threads clause and its location are expected.");
+    Res = ActOnOpenMPNumThreadsClause(
+        static_cast<OpenMPNumThreadsClauseModifier>(Argument.back()), Expr,
+        StartLoc, LParenLoc, ArgumentLoc.back(), EndLoc);
+    break;
+  case OMPC_final:
   case OMPC_safelen:
   case OMPC_simdlen:
   case OMPC_sizes:

clang/lib/Sema/TreeTransform.h

@@ -1714,12 +1714,14 @@ class TreeTransform {
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
   /// Subclasses may override this routine to provide different behavior.
-  OMPClause *RebuildOMPNumThreadsClause(Expr *NumThreads,
+  OMPClause *RebuildOMPNumThreadsClause(OpenMPNumThreadsClauseModifier Modifier,
+                                        Expr *NumThreads,
                                         SourceLocation StartLoc,
                                         SourceLocation LParenLoc,
+                                        SourceLocation ModifierLoc,
                                         SourceLocation EndLoc) {
-    return getSema().OpenMP().ActOnOpenMPNumThreadsClause(NumThreads, StartLoc,
-                                                          LParenLoc, EndLoc);
+    return getSema().OpenMP().ActOnOpenMPNumThreadsClause(
+        Modifier, NumThreads, StartLoc, LParenLoc, ModifierLoc, EndLoc);
   }
 
   /// Build a new OpenMP 'safelen' clause.
@@ -10461,7 +10463,8 @@ TreeTransform<Derived>::TransformOMPNumThreadsClause(OMPNumThreadsClause *C) {
   if (NumThreads.isInvalid())
     return nullptr;
   return getDerived().RebuildOMPNumThreadsClause(
-      NumThreads.get(), C->getBeginLoc(), C->getLParenLoc(), C->getEndLoc());
+      C->getModifier(), NumThreads.get(), C->getBeginLoc(), C->getLParenLoc(),
+      C->getModifierLoc(), C->getEndLoc());
 }
 
 template <typename Derived>

clang/lib/Serialization/ASTReader.cpp

@@ -11461,7 +11461,9 @@ void OMPClauseReader::VisitOMPFinalClause(OMPFinalClause *C) {
 
 void OMPClauseReader::VisitOMPNumThreadsClause(OMPNumThreadsClause *C) {
   VisitOMPClauseWithPreInit(C);
+  C->setModifier(Record.readEnum<OpenMPNumThreadsClauseModifier>());
   C->setNumThreads(Record.readSubExpr());
+  C->setModifierLoc(Record.readSourceLocation());
   C->setLParenLoc(Record.readSourceLocation());
 }