[OpenACC] Handle sema for gang, worker, vector, seq clauses on routine

These 4 clauses are mutually exclusive, AND require at least one of
them. Additionally, gang has some additional restrictions in that only
the 'dim' specifier is permitted. This patch implements all of this, and
ends up refactoring the handling of each of these clauses for
readabililty.

Author: erichkeane

clang/include/clang/Sema/SemaOpenACC.h

@@ -698,7 +698,8 @@ class SemaOpenACC : public SemaBase {
   /// parsing has consumed the 'annot_pragma_openacc_end' token. This DOES
   /// happen before any associated declarations or statements have been parsed.
   /// This function is only called when we are parsing a 'Decl' context.
-  bool ActOnStartDeclDirective(OpenACCDirectiveKind K, SourceLocation StartLoc);
+  bool ActOnStartDeclDirective(OpenACCDirectiveKind K, SourceLocation StartLoc,
+                               ArrayRef<const OpenACCClause *> Clauses);
   /// Called when we encounter an associated statement for our construct, this
   /// should check legality of the statement as it appertains to this Construct.
   StmtResult ActOnAssociatedStmt(SourceLocation DirectiveLoc,

clang/lib/AST/DeclPrinter.cpp

@@ -1918,9 +1918,12 @@ void DeclPrinter::VisitNonTypeTemplateParmDecl(
 
 void DeclPrinter::VisitOpenACCDeclareDecl(OpenACCDeclareDecl *D) {
   if (!D->isInvalidDecl()) {
-    Out << "#pragma acc declare ";
-    OpenACCClausePrinter Printer(Out, Policy);
-    Printer.VisitClauseList(D->clauses());
+    Out << "#pragma acc declare";
+    if (!D->clauses().empty()) {
+      Out << ' ';
+      OpenACCClausePrinter Printer(Out, Policy);
+      Printer.VisitClauseList(D->clauses());
+    }
   }
 }
 void DeclPrinter::VisitOpenACCRoutineDecl(OpenACCRoutineDecl *D) {
@@ -1941,7 +1944,10 @@ void DeclPrinter::VisitOpenACCRoutineDecl(OpenACCRoutineDecl *D) {
       Out << ")";
     }
 
-    OpenACCClausePrinter Printer(Out, Policy);
-    Printer.VisitClauseList(D->clauses());
+    if (!D->clauses().empty()) {
+      Out << ' ';
+      OpenACCClausePrinter Printer(Out, Policy);
+      Printer.VisitClauseList(D->clauses());
+    }
   }
 }

clang/lib/Parse/ParseOpenACC.cpp

@@ -1539,8 +1539,8 @@ Parser::DeclGroupPtrTy Parser::ParseOpenACCDirectiveDecl() {
 
   OpenACCDirectiveParseInfo DirInfo = ParseOpenACCDirective();
 
-  if (getActions().OpenACC().ActOnStartDeclDirective(DirInfo.DirKind,
-                                                     DirInfo.StartLoc))
+  if (getActions().OpenACC().ActOnStartDeclDirective(
+          DirInfo.DirKind, DirInfo.StartLoc, DirInfo.Clauses))
     return nullptr;
 
   return DeclGroupPtrTy::make(getActions().OpenACC().ActOnEndDeclDirective(

clang/lib/Sema/SemaOpenACC.cpp

@@ -1555,7 +1555,7 @@ bool SemaOpenACC::ActOnStartStmtDirective(
   // Declaration directives an appear in a statement location, so call into that
   // function here.
   if (K == OpenACCDirectiveKind::Declare || K == OpenACCDirectiveKind::Routine)
-    return ActOnStartDeclDirective(K, StartLoc);
+    return ActOnStartDeclDirective(K, StartLoc, Clauses);
 
   SemaRef.DiscardCleanupsInEvaluationContext();
   SemaRef.PopExpressionEvaluationContext();
@@ -1832,14 +1832,29 @@ StmtResult SemaOpenACC::ActOnAssociatedStmt(
   llvm_unreachable("Invalid associated statement application");
 }
 
-bool SemaOpenACC::ActOnStartDeclDirective(OpenACCDirectiveKind K,
-                                          SourceLocation StartLoc) {
+bool SemaOpenACC::ActOnStartDeclDirective(
+    OpenACCDirectiveKind K, SourceLocation StartLoc,
+    ArrayRef<const OpenACCClause *> Clauses) {
   // OpenCC3.3 2.1 (line 889)
   // A program must not depend on the order of evaluation of expressions in
   // clause arguments or on any side effects of the evaluations.
   SemaRef.DiscardCleanupsInEvaluationContext();
   SemaRef.PopExpressionEvaluationContext();
 
+  if (K == OpenACCDirectiveKind::Routine &&
+      llvm::find_if(Clauses,
+                    llvm::IsaPred<OpenACCGangClause, OpenACCWorkerClause,
+                                  OpenACCVectorClause, OpenACCSeqClause>) ==
+          Clauses.end())
+    return Diag(StartLoc, diag::err_acc_construct_one_clause_of)
+           << K
+           << GetListOfClauses({
+                  OpenACCClauseKind::Gang,
+                  OpenACCClauseKind::Worker,
+                  OpenACCClauseKind::Vector,
+                  OpenACCClauseKind::Seq,
+              });
+
   return diagnoseConstructAppertainment(*this, K, StartLoc, /*IsStmt=*/false);
 }