[flang][openmp] Required clauses are allowed

[clementval]

Summary

This patch fix a problem where clause needed to be in the allowed set even
they were in the required set. A required clause is allowed obvisouly. This allow
to remove the duplicate in OMP.td

[kiranchandramohan]

llvm/include/llvm/Frontend/OpenMP/OMP.td

424–427

Is requiredClause missing here?

[clementval]

llvm/include/llvm/Frontend/OpenMP/OMP.td

424–427

Well it is not mandatory but looks like that map is required for target enter data so it should be moved from allowedClauses to requiredClauses. I will update the patch to include this change as well.

[clementval]

Update clauses for target enter data as per review comment

[kiranchandramohan]

LGTM.

flang/lib/Semantics/check-omp-structure.cpp

if (CurrentDirectiveIsNested() && set.test(GetContext().directive)) {
     return true;
   }
   return false;
 }
 
 void OmpStructureChecker::CheckAllowed(llvm::omp::Clause type) {
   if (!GetContext().allowedClauses.test(type) &&
       !GetContext().allowedOnceClauses.test(type) &&
-      !GetContext().allowedExclusiveClauses.test(type)) {
+      !GetContext().allowedExclusiveClauses.test(type) &&
+      !GetContext().requiredClauses.test(type)) {
     context_.Say(GetContext().clauseSource,
         "%s clause is not allowed on the %s directive"_err_en_US,
         parser::ToUpperCaseLetters(llvm::omp::getOpenMPClauseName(type).str()),
         parser::ToUpperCaseLetters(GetContext().directiveSource.ToString()));
     return;
   }
   if ((GetContext().allowedOnceClauses.test(type) ||
           GetContext().allowedExclusiveClauses.test(type)) &&

llvm/include/llvm/Frontend/OpenMP/OMP.td

let allowedClauses = [
     VersionedClause<OMPC_UnifiedSharedMemory>,
     VersionedClause<OMPC_ReverseOffload>,
     VersionedClause<OMPC_DynamicAllocators>,
     VersionedClause<OMPC_AtomicDefaultMemOrder>
   ];
 }
 def OMP_TargetData : Directive<"target data"> {
   let allowedClauses = [
-    VersionedClause<OMPC_Map>,
     VersionedClause<OMPC_UseDevicePtr>,
     VersionedClause<OMPC_UseDeviceAddr, 50>
   ];
   let allowedOnceClauses = [
     VersionedClause<OMPC_Device>,
     VersionedClause<OMPC_If>
   ];
   let requiredClauses = [
     VersionedClause<OMPC_Map>
   ];
 }
 def OMP_TargetEnterData : Directive<"target enter data"> {
   let allowedClauses = [
-    VersionedClause<OMPC_Depend>,
-    VersionedClause<OMPC_Map>
+    VersionedClause<OMPC_Depend>
   ];
   let allowedOnceClauses = [
     VersionedClause<OMPC_If>,
     VersionedClause<OMPC_Device>,
     VersionedClause<OMPC_NoWait>
   ];
+  let requiredClauses = [
+    VersionedClause<OMPC_Map>
+  ];
 }
 def OMP_TargetExitData : Directive<"target exit data"> {
   let allowedClauses = [
-    VersionedClause<OMPC_Depend>,
-    VersionedClause<OMPC_Map>
+    VersionedClause<OMPC_Depend>
   ];
   let allowedOnceClauses = [
     VersionedClause<OMPC_Device>,
     VersionedClause<OMPC_If>,
     VersionedClause<OMPC_NoWait>
   ];
   let requiredClauses = [
     VersionedClause<OMPC_Map>