[OpenMP 60] Update parsing and semantic support for `nowait` clause to accept optional argument (#159628)

This PR enhances the OpenMP `nowait` clause implementation by adding
support for optional argument in both parsing and semantic analysis
phases.

Reference:
1. OpenMP 6.0 Specification, page 481

7 files changed, 71 insertions, 11 deletions

diff --git a/clang/lib/AST/OpenMPClause.cpp b/clang/lib/AST/OpenMPClause.cpp
index 2ce4419..791df7e 100644
--- a/clang/lib/AST/OpenMPClause.cpp
+++ b/clang/lib/AST/OpenMPClause.cpp
@@ -309,6 +309,12 @@ OMPClause::child_range OMPIfClause::used_children() {
   return child_range(&Condition, &Condition + 1);
 }
 
+OMPClause::child_range OMPNowaitClause::used_children() {
+  if (Condition)
+    return child_range(&Condition, &Condition + 1);
+  return children();
+}
+
 OMPClause::child_range OMPGrainsizeClause::used_children() {
   if (Stmt **C = getAddrOfExprAsWritten(getPreInitStmt()))
     return child_range(C, C + 1);
@@ -2113,8 +2119,13 @@ void OMPClausePrinter::VisitOMPOrderedClause(OMPOrderedClause *Node) {
   }
 }
 
-void OMPClausePrinter::VisitOMPNowaitClause(OMPNowaitClause *) {
+void OMPClausePrinter::VisitOMPNowaitClause(OMPNowaitClause *Node) {
   OS << "nowait";
+  if (auto *Cond = Node->getCondition()) {
+    OS << "(";
+    Cond->printPretty(OS, nullptr, Policy, 0);
+    OS << ")";
+  }
 }
 
 void OMPClausePrinter::VisitOMPUntiedClause(OMPUntiedClause *) {
diff --git a/clang/lib/AST/StmtProfile.cpp b/clang/lib/AST/StmtProfile.cpp
index 3cd033e..05b64cc 100644
--- a/clang/lib/AST/StmtProfile.cpp
+++ b/clang/lib/AST/StmtProfile.cpp
@@ -585,7 +585,10 @@ void OMPClauseProfiler::VisitOMPOrderedClause(const OMPOrderedClause *C) {
     Profiler->VisitStmt(Num);
 }
 
-void OMPClauseProfiler::VisitOMPNowaitClause(const OMPNowaitClause *) {}
+void OMPClauseProfiler::VisitOMPNowaitClause(const OMPNowaitClause *C) {
+  if (C->getCondition())
+    Profiler->VisitStmt(C->getCondition());
+}
 
 void OMPClauseProfiler::VisitOMPUntiedClause(const OMPUntiedClause *) {}
 
diff --git a/clang/lib/Parse/ParseOpenMP.cpp b/clang/lib/Parse/ParseOpenMP.cpp
index 04f29c8..25199c7 100644
--- a/clang/lib/Parse/ParseOpenMP.cpp
+++ b/clang/lib/Parse/ParseOpenMP.cpp
@@ -3311,7 +3311,11 @@ OMPClause *Parser::ParseOpenMPClause(OpenMPDirectiveKind DKind,
       ErrorFound = true;
     }
 
-    Clause = ParseOpenMPClause(CKind, WrongDirective);
+    if (CKind == OMPC_nowait && PP.LookAhead(/*N=*/0).is(tok::l_paren) &&
+        getLangOpts().OpenMP >= 60)
+      Clause = ParseOpenMPSingleExprClause(CKind, WrongDirective);
+    else
+      Clause = ParseOpenMPClause(CKind, WrongDirective);
     break;
   case OMPC_self_maps:
     // OpenMP [6.0, self_maps clause]
diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index 0fa21e8..5b5b1b6 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -16491,6 +16491,9 @@ OMPClause *SemaOpenMP::ActOnOpenMPSingleExprClause(OpenMPClauseKind Kind,
   case OMPC_ordered:
     Res = ActOnOpenMPOrderedClause(StartLoc, EndLoc, LParenLoc, Expr);
     break;
+  case OMPC_nowait:
+    Res = ActOnOpenMPNowaitClause(StartLoc, EndLoc, LParenLoc, Expr);
+    break;
   case OMPC_priority:
     Res = ActOnOpenMPPriorityClause(Expr, StartLoc, LParenLoc, EndLoc);
     break;
@@ -16546,7 +16549,6 @@ OMPClause *SemaOpenMP::ActOnOpenMPSingleExprClause(OpenMPClauseKind Kind,
   case OMPC_aligned:
   case OMPC_copyin:
   case OMPC_copyprivate:
-  case OMPC_nowait:
   case OMPC_untied:
   case OMPC_mergeable:
   case OMPC_threadprivate:
@@ -17955,7 +17957,9 @@ OMPClause *SemaOpenMP::ActOnOpenMPClause(OpenMPClauseKind Kind,
     Res = ActOnOpenMPOrderedClause(StartLoc, EndLoc);
     break;
   case OMPC_nowait:
-    Res = ActOnOpenMPNowaitClause(StartLoc, EndLoc);
+    Res = ActOnOpenMPNowaitClause(StartLoc, EndLoc,
+                                  /*LParenLoc=*/SourceLocation(),
+                                  /*Condition=*/nullptr);
     break;
   case OMPC_untied:
     Res = ActOnOpenMPUntiedClause(StartLoc, EndLoc);
@@ -18107,9 +18111,24 @@ OMPClause *SemaOpenMP::ActOnOpenMPClause(OpenMPClauseKind Kind,
 }
 
 OMPClause *SemaOpenMP::ActOnOpenMPNowaitClause(SourceLocation StartLoc,
-                                               SourceLocation EndLoc) {
+                                               SourceLocation EndLoc,
+                                               SourceLocation LParenLoc,
+                                               Expr *Condition) {
+  Expr *ValExpr = Condition;
+  if (Condition && LParenLoc.isValid()) {
+    if (!Condition->isValueDependent() && !Condition->isTypeDependent() &&
+        !Condition->isInstantiationDependent() &&
+        !Condition->containsUnexpandedParameterPack()) {
+      ExprResult Val = SemaRef.CheckBooleanCondition(StartLoc, Condition);
+      if (Val.isInvalid())
+        return nullptr;
+
+      ValExpr = Val.get();
+    }
+  }
   DSAStack->setNowaitRegion();
-  return new (getASTContext()) OMPNowaitClause(StartLoc, EndLoc);
+  return new (getASTContext())
+      OMPNowaitClause(ValExpr, StartLoc, LParenLoc, EndLoc);
 }
 
 OMPClause *SemaOpenMP::ActOnOpenMPUntiedClause(SourceLocation StartLoc,
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index 0dcfe0e..04a5e4b 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -1865,6 +1865,17 @@ public:
                                                        LParenLoc, Num);
   }
 
+  /// Build a new OpenMP 'nowait' clause.
+  ///
+  /// By default, performs semantic analysis to build the new OpenMP clause.
+  /// Subclasses may override this routine to provide different behavior.
+  OMPClause *RebuildOMPNowaitClause(Expr *Condition, SourceLocation StartLoc,
+                                    SourceLocation LParenLoc,
+                                    SourceLocation EndLoc) {
+    return getSema().OpenMP().ActOnOpenMPNowaitClause(StartLoc, EndLoc,
+                                                      LParenLoc, Condition);
+  }
+
   /// Build a new OpenMP 'private' clause.
   ///
   /// By default, performs semantic analysis to build the new OpenMP clause.
@@ -10612,8 +10623,14 @@ TreeTransform<Derived>::TransformOMPDetachClause(OMPDetachClause *C) {
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPNowaitClause(OMPNowaitClause *C) {
-  // No need to rebuild this clause, no template-dependent parameters.
-  return C;
+  ExprResult Cond;
+  if (auto *Condition = C->getCondition()) {
+    Cond = getDerived().TransformExpr(Condition);
+    if (Cond.isInvalid())
+      return nullptr;
+  }
+  return getDerived().RebuildOMPNowaitClause(Cond.get(), C->getBeginLoc(),
+                                             C->getLParenLoc(), C->getEndLoc());
 }
 
 template <typename Derived>
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index ff6bbf9..32f7a0e 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -11688,7 +11688,10 @@ void OMPClauseReader::VisitOMPDetachClause(OMPDetachClause *C) {
   C->setLParenLoc(Record.readSourceLocation());
 }
 
-void OMPClauseReader::VisitOMPNowaitClause(OMPNowaitClause *) {}
+void OMPClauseReader::VisitOMPNowaitClause(OMPNowaitClause *C) {
+  C->setCondition(Record.readSubExpr());
+  C->setLParenLoc(Record.readSourceLocation());
+}
 
 void OMPClauseReader::VisitOMPUntiedClause(OMPUntiedClause *) {}
 
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 82ccde8..377e396 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -7942,7 +7942,10 @@ void OMPClauseWriter::VisitOMPOrderedClause(OMPOrderedClause *C) {
   Record.AddSourceLocation(C->getLParenLoc());
 }
 
-void OMPClauseWriter::VisitOMPNowaitClause(OMPNowaitClause *) {}
+void OMPClauseWriter::VisitOMPNowaitClause(OMPNowaitClause *C) {
+  Record.AddStmt(C->getCondition());
+  Record.AddSourceLocation(C->getLParenLoc());
+}
 
 void OMPClauseWriter::VisitOMPUntiedClause(OMPUntiedClause *) {}