diff --git a/flang/lib/Semantics/check-omp-structure.h b/flang/lib/Semantics/check-omp-structure.h
--- a/flang/lib/Semantics/check-omp-structure.h
+++ b/flang/lib/Semantics/check-omp-structure.h
@@ -25,6 +25,9 @@
 using OmpClauseSet =
     Fortran::common::EnumSet<llvm::omp::Clause, llvm::omp::Clause_enumSize>;
 
+#define GEN_FLANG_DIRECTIVE_CLAUSE_SETS
+#include "llvm/Frontend/OpenMP/OMP.cpp.inc"
+
 namespace llvm {
 namespace omp {
 static OmpDirectiveSet parallelSet{Directive::OMPD_distribute_parallel_do,
@@ -151,6 +154,9 @@
   void Enter(const parser::OmpScheduleClause &);
 
 private:
+#define GEN_FLANG_DIRECTIVE_CLAUSE_MAP
+#include "llvm/Frontend/OpenMP/OMP.cpp.inc"
+
   struct OmpContext {
     OmpContext(parser::CharBlock source, llvm::omp::Directive d)
         : directiveSource{source}, directive{d} {}
@@ -216,7 +222,20 @@
   void PushContext(const parser::CharBlock &source, llvm::omp::Directive dir) {
     ompContext_.emplace_back(source, dir);
   }
-
+  void SetClauseSets(llvm::omp::Directive dir) {
+    ompContext_.back().allowedClauses = directiveClausesTable[dir].allowed;
+    ompContext_.back().allowedOnceClauses =
+        directiveClausesTable[dir].allowedOnce;
+    ompContext_.back().allowedExclusiveClauses =
+        directiveClausesTable[dir].allowedExclusive;
+    ompContext_.back().requiredClauses =
+        directiveClausesTable[dir].requiredOneOf;
+  }
+  void PushContextAndClauseSets(
+      const parser::CharBlock &source, llvm::omp::Directive dir) {
+    PushContext(source, dir);
+    SetClauseSets(dir);
+  }
   void RequiresConstantPositiveParameter(
       const llvm::omp::Clause &clause, const parser::ScalarIntConstantExpr &i);
   void RequiresPositiveParameter(
diff --git a/flang/lib/Semantics/check-omp-structure.cpp b/flang/lib/Semantics/check-omp-structure.cpp
--- a/flang/lib/Semantics/check-omp-structure.cpp
+++ b/flang/lib/Semantics/check-omp-structure.cpp
@@ -13,58 +13,6 @@
 
 namespace Fortran::semantics {
 
-static OmpClauseSet doAllowedClauses{llvm::omp::Clause::OMPC_private,
-    llvm::omp::Clause::OMPC_firstprivate, llvm::omp::Clause::OMPC_lastprivate,
-    llvm::omp::Clause::OMPC_linear, llvm::omp::Clause::OMPC_reduction};
-static OmpClauseSet doAllowedOnceClauses{llvm::omp::Clause::OMPC_schedule,
-    llvm::omp::Clause::OMPC_collapse, llvm::omp::Clause::OMPC_ordered};
-
-static OmpClauseSet simdAllowedClauses{llvm::omp::Clause::OMPC_linear,
-    llvm::omp::Clause::OMPC_aligned, llvm::omp::Clause::OMPC_private,
-    llvm::omp::Clause::OMPC_lastprivate, llvm::omp::Clause::OMPC_reduction};
-static OmpClauseSet simdAllowedOnceClauses{llvm::omp::Clause::OMPC_collapse,
-    llvm::omp::Clause::OMPC_safelen, llvm::omp::Clause::OMPC_simdlen};
-
-static OmpClauseSet parallelAllowedClauses{llvm::omp::Clause::OMPC_default,
-    llvm::omp::Clause::OMPC_private, llvm::omp::Clause::OMPC_firstprivate,
-    llvm::omp::Clause::OMPC_shared, llvm::omp::Clause::OMPC_copyin,
-    llvm::omp::Clause::OMPC_reduction};
-static OmpClauseSet parallelAllowedOnceClauses{llvm::omp::Clause::OMPC_if,
-    llvm::omp::Clause::OMPC_num_threads, llvm::omp::Clause::OMPC_proc_bind};
-
-static OmpClauseSet taskloopAllowedClauses{llvm::omp::Clause::OMPC_shared,
-    llvm::omp::Clause::OMPC_private, llvm::omp::Clause::OMPC_firstprivate,
-    llvm::omp::Clause::OMPC_lastprivate, llvm::omp::Clause::OMPC_default,
-    llvm::omp::Clause::OMPC_untied, llvm::omp::Clause::OMPC_mergeable,
-    llvm::omp::Clause::OMPC_nogroup};
-static OmpClauseSet taskloopAllowedOnceClauses{llvm::omp::Clause::OMPC_collapse,
-    llvm::omp::Clause::OMPC_if, llvm::omp::Clause::OMPC_final,
-    llvm::omp::Clause::OMPC_priority};
-static OmpClauseSet taskloopAllowedExclusiveClauses{
-    llvm::omp::Clause::OMPC_grainsize, llvm::omp::Clause::OMPC_num_tasks};
-
-static OmpClauseSet distributeAllowedClauses{llvm::omp::Clause::OMPC_private,
-    llvm::omp::Clause::OMPC_firstprivate, llvm::omp::Clause::OMPC_lastprivate};
-static OmpClauseSet distributeAllowedOnceClauses{
-    llvm::omp::Clause::OMPC_collapse, llvm::omp::Clause::OMPC_dist_schedule};
-
-static OmpClauseSet targetAllowedClauses{llvm::omp::Clause::OMPC_if,
-    llvm::omp::Clause::OMPC_private, llvm::omp::Clause::OMPC_firstprivate,
-    llvm::omp::Clause::OMPC_map, llvm::omp::Clause::OMPC_is_device_ptr,
-    llvm::omp::Clause::OMPC_depend};
-static OmpClauseSet targetAllowedOnceClauses{llvm::omp::Clause::OMPC_device,
-    llvm::omp::Clause::OMPC_defaultmap, llvm::omp::Clause::OMPC_nowait};
-
-static OmpClauseSet teamsAllowedClauses{llvm::omp::Clause::OMPC_private,
-    llvm::omp::Clause::OMPC_firstprivate, llvm::omp::Clause::OMPC_shared,
-    llvm::omp::Clause::OMPC_reduction};
-static OmpClauseSet teamsAllowedOnceClauses{llvm::omp::Clause::OMPC_num_teams,
-    llvm::omp::Clause::OMPC_thread_limit, llvm::omp::Clause::OMPC_default};
-
-static OmpClauseSet sectionsAllowedClauses{llvm::omp::Clause::OMPC_private,
-    llvm::omp::Clause::OMPC_firstprivate, llvm::omp::Clause::OMPC_lastprivate,
-    llvm::omp::Clause::OMPC_reduction};
-
 std::string OmpStructureChecker::ContextDirectiveAsFortran() {
   auto dir = llvm::omp::getOpenMPDirectiveName(GetContext().directive).str();
   std::transform(dir.begin(), dir.end(), dir.begin(),
@@ -186,19 +134,18 @@
     CheckMatching<parser::OmpLoopDirective>(beginLoopDir, *endLoopDir);
   }
 
-  if (beginDir.v != llvm::omp::Directive::OMPD_do)
-    PushContext(beginDir.source, beginDir.v);
+  if (beginDir.v != llvm::omp::Directive::OMPD_do) {
+    PushContextAndClauseSets(beginDir.source, beginDir.v);
+  } else {
+    // 2.7.1 do-clause -> private-clause |
+    //                    firstprivate-clause |
+    //                    lastprivate-clause |
+    //                    linear-clause |
+    //                    reduction-clause |
+    //                    schedule-clause |
+    //                    collapse-clause |
+    //                    ordered-clause
 
-  switch (beginDir.v) {
-  // 2.7.1 do-clause -> private-clause |
-  //                    firstprivate-clause |
-  //                    lastprivate-clause |
-  //                    linear-clause |
-  //                    reduction-clause |
-  //                    schedule-clause |
-  //                    collapse-clause |
-  //                    ordered-clause
-  case llvm::omp::Directive::OMPD_do: {
     // nesting check
     HasInvalidWorksharingNesting(beginDir.source,
         {llvm::omp::Directive::OMPD_do, llvm::omp::Directive::OMPD_sections,
@@ -210,218 +157,7 @@
             llvm::omp::Directive::OMPD_ordered,
             llvm::omp::Directive::OMPD_atomic,
             llvm::omp::Directive::OMPD_master});
-    PushContext(beginDir.source, llvm::omp::Directive::OMPD_do);
-    SetContextAllowed(doAllowedClauses);
-    SetContextAllowedOnce(doAllowedOnceClauses);
-  } break;
-
-  // 2.11.1 parallel-do-clause -> parallel-clause |
-  //                              do-clause
-  case llvm::omp::Directive::OMPD_parallel_do: {
-    SetContextAllowed(parallelAllowedClauses | doAllowedClauses);
-    SetContextAllowedOnce(parallelAllowedOnceClauses | doAllowedOnceClauses);
-  } break;
-
-  // 2.8.1 simd-clause -> safelen-clause |
-  //                      simdlen-clause |
-  //                      linear-clause |
-  //                      aligned-clause |
-  //                      private-clause |
-  //                      lastprivate-clause |
-  //                      reduction-clause |
-  //                      collapse-clause
-  case llvm::omp::Directive::OMPD_simd: {
-    SetContextAllowed(simdAllowedClauses);
-    SetContextAllowedOnce(simdAllowedOnceClauses);
-  } break;
-
-  // 2.8.3 do-simd-clause -> do-clause |
-  //                         simd-clause
-  case llvm::omp::Directive::OMPD_do_simd: {
-    SetContextAllowed(doAllowedClauses | simdAllowedClauses);
-    SetContextAllowedOnce(doAllowedOnceClauses | simdAllowedOnceClauses);
-  } break;
-
-  // 2.11.4 parallel-do-simd-clause -> parallel-clause |
-  //                                   do-simd-clause
-  case llvm::omp::Directive::OMPD_parallel_do_simd: {
-    SetContextAllowed(
-        parallelAllowedClauses | doAllowedClauses | simdAllowedClauses);
-    SetContextAllowedOnce(parallelAllowedOnceClauses | doAllowedOnceClauses |
-        simdAllowedOnceClauses);
-  } break;
-
-  // 2.9.2 taskloop-clause -> if-clause |
-  //                          shared-clause |
-  //                          private-clause |
-  //                          firstprivate-clause |
-  //                          lastprivate-clause |
-  //                          default-clause |
-  //                          grainsize-clause |
-  //                          num-tasks-clause |
-  //                          collapse-clause |
-  //                          final-clause |
-  //                          priority-clause |
-  //                          untied-clause |
-  //                          mergeable-clause |
-  //                          nogroup-clause
-  case llvm::omp::Directive::OMPD_taskloop: {
-    SetContextAllowed(taskloopAllowedClauses);
-    SetContextAllowedOnce(taskloopAllowedOnceClauses);
-    SetContextAllowedExclusive(taskloopAllowedExclusiveClauses);
-  } break;
-
-  // 2.9.3 taskloop-simd-clause -> taskloop-clause |
-  //                               simd-clause
-  case llvm::omp::Directive::OMPD_taskloop_simd: {
-    SetContextAllowed((taskloopAllowedClauses | simdAllowedClauses) -
-        llvm::omp::Clause::OMPC_reduction);
-    SetContextAllowedOnce(taskloopAllowedOnceClauses | simdAllowedOnceClauses);
-    SetContextAllowedExclusive(taskloopAllowedExclusiveClauses);
-  } break;
-
-  // 2.10.8 distribute-clause -> private-clause |
-  //                             firstprivate-clause |
-  //                             lastprivate-clause |
-  //                             collapse-clause |
-  //                             dist-schedule-clause
-  case llvm::omp::Directive::OMPD_distribute: {
-    SetContextAllowed(distributeAllowedClauses);
-    SetContextAllowedOnce(distributeAllowedOnceClauses);
-  } break;
-
-  // 2.10.9 distribute-simd-clause -> distribute-clause |
-  //                                  simd-clause
-  case llvm::omp::Directive::OMPD_distribute_simd: {
-    SetContextAllowed(distributeAllowedClauses | simdAllowedClauses);
-    SetContextAllowedOnce(
-        distributeAllowedOnceClauses | simdAllowedOnceClauses);
-  } break;
-
-  // 2.10.10 distribute-parallel-do-clause -> distribute-clause |
-  //                                          parallel-do-clause
-  case llvm::omp::Directive::OMPD_distribute_parallel_do: {
-    SetContextAllowed(
-        distributeAllowedClauses | parallelAllowedClauses | doAllowedClauses);
-    SetContextAllowedOnce(distributeAllowedOnceClauses |
-        parallelAllowedOnceClauses | doAllowedOnceClauses);
-  } break;
-
-  // 2.10.11 distribute-parallel-do-simd-clause -> distribute-clause |
-  //                                               parallel-do-simd-clause
-  case llvm::omp::Directive::OMPD_distribute_parallel_do_simd: {
-    SetContextAllowed(distributeAllowedClauses | parallelAllowedClauses |
-        doAllowedClauses | simdAllowedClauses);
-    SetContextAllowedOnce(distributeAllowedOnceClauses |
-        parallelAllowedOnceClauses | doAllowedOnceClauses | simdAllowedClauses);
-  } break;
-
-  // 2.11.6 target-parallel-do-clause -> target-clause |
-  //                                     parallel-do-clause
-  case llvm::omp::Directive::OMPD_target_parallel_do: {
-    SetContextAllowed(
-        targetAllowedClauses | parallelAllowedClauses | doAllowedClauses);
-    SetContextAllowedOnce(
-        (targetAllowedOnceClauses | parallelAllowedOnceClauses |
-            doAllowedOnceClauses) -
-        llvm::omp::Clause::OMPC_nowait);
-  } break;
-
-  // 2.11.7 target-parallel-do-simd-clause -> target-clause |
-  //                                          parallel-do-simd-clause
-  case llvm::omp::Directive::OMPD_target_parallel_do_simd: {
-    SetContextAllowed(targetAllowedClauses | parallelAllowedClauses |
-        doAllowedClauses | simdAllowedClauses);
-    SetContextAllowedOnce(
-        (targetAllowedOnceClauses | parallelAllowedOnceClauses |
-            doAllowedOnceClauses | simdAllowedOnceClauses) -
-        llvm::omp::Clause::OMPC_nowait);
-  } break;
-
-  // 2.11.8 target-simd-clause -> target-clause |
-  //                              simd-clause
-  case llvm::omp::Directive::OMPD_target_simd: {
-    SetContextAllowed(targetAllowedClauses | simdAllowedClauses);
-    SetContextAllowedOnce(targetAllowedOnceClauses | simdAllowedOnceClauses);
-  } break;
-
-  // 2.11.10 teams-distribute-clause -> teams-clause |
-  //                                    distribute-clause
-  case llvm::omp::Directive::OMPD_teams_distribute: {
-    SetContextAllowed(teamsAllowedClauses | distributeAllowedClauses);
-    SetContextAllowedOnce(
-        teamsAllowedOnceClauses | distributeAllowedOnceClauses);
-  } break;
-
-  // 2.11.11 teams-distribute-simd-clause -> teams-clause |
-  //                                         distribute-simd-clause
-  case llvm::omp::Directive::OMPD_teams_distribute_simd: {
-    SetContextAllowed(
-        teamsAllowedClauses | distributeAllowedClauses | simdAllowedClauses);
-    SetContextAllowedOnce(teamsAllowedOnceClauses |
-        distributeAllowedOnceClauses | simdAllowedOnceClauses);
-  } break;
-
-  // 2.11.12 target-teams-distribute-clause -> target-clause |
-  //                                           teams-distribute-clause
-  case llvm::omp::Directive::OMPD_target_teams_distribute: {
-    SetContextAllowed(
-        targetAllowedClauses | teamsAllowedClauses | distributeAllowedClauses);
-    SetContextAllowedOnce(targetAllowedOnceClauses | teamsAllowedOnceClauses |
-        distributeAllowedOnceClauses);
-  } break;
-
-  // 2.11.13 target-teams-distribute-simd-clause -> target-clause |
-  //                                                teams-distribute-simd-clause
-  case llvm::omp::Directive::OMPD_target_teams_distribute_simd: {
-    SetContextAllowed(targetAllowedClauses | teamsAllowedClauses |
-        distributeAllowedClauses | simdAllowedClauses);
-    SetContextAllowed(targetAllowedOnceClauses | teamsAllowedOnceClauses |
-        distributeAllowedOnceClauses | simdAllowedOnceClauses);
-  } break;
-
-  // 2.11.14 teams-distribute-parallel-do-clause -> teams-clause |
-  //                                                distribute-parallel-do-clause
-  case llvm::omp::Directive::OMPD_teams_distribute_parallel_do: {
-    SetContextAllowed(teamsAllowedClauses | distributeAllowedClauses |
-        parallelAllowedClauses | doAllowedClauses);
-    SetContextAllowedOnce(teamsAllowedOnceClauses |
-        distributeAllowedOnceClauses | parallelAllowedOnceClauses |
-        doAllowedOnceClauses);
-  } break;
-
-  // 2.11.15 target-teams-distribute-parallel-do-clause -> target-clause |
-  //                                                       teams-distribute-parallel-do-clause
-  case llvm::omp::Directive::OMPD_target_teams_distribute_parallel_do: {
-    SetContextAllowed(targetAllowedClauses | teamsAllowedClauses |
-        distributeAllowedClauses | parallelAllowedClauses | doAllowedClauses);
-    SetContextAllowedOnce(targetAllowedOnceClauses | teamsAllowedOnceClauses |
-        distributeAllowedOnceClauses | parallelAllowedOnceClauses |
-        doAllowedOnceClauses);
-  } break;
-
-  // 2.11.16 teams-distribute-parallel-do-clause -> teams-clause |
-  //                                                distribute-parallel-do-simd-clause
-  case llvm::omp::Directive::OMPD_teams_distribute_parallel_do_simd: {
-    SetContextAllowed(teamsAllowedClauses | distributeAllowedClauses |
-        parallelAllowedClauses | doAllowedClauses | simdAllowedClauses);
-    SetContextAllowedOnce(teamsAllowedOnceClauses |
-        distributeAllowedOnceClauses | parallelAllowedOnceClauses |
-        doAllowedOnceClauses | simdAllowedOnceClauses);
-  } break;
-
-  case llvm::omp::Directive::OMPD_target_teams_distribute_parallel_do_simd: {
-    SetContextAllowed(targetAllowedClauses | teamsAllowedClauses |
-        distributeAllowedClauses | parallelAllowedClauses | doAllowedClauses |
-        simdAllowedClauses);
-    SetContextAllowedOnce(targetAllowedOnceClauses | teamsAllowedOnceClauses |
-        distributeAllowedOnceClauses | parallelAllowedOnceClauses |
-        doAllowedOnceClauses | simdAllowedOnceClauses);
-  } break;
-
-  default:
-    // TODO others
-    break;
+    PushContextAndClauseSets(beginDir.source, llvm::omp::Directive::OMPD_do);
   }
 }
 
@@ -436,12 +172,8 @@
   // 2.7.1 end-do -> END DO [nowait-clause]
   // 2.8.3 end-do-simd -> END DO SIMD [nowait-clause]
   case llvm::omp::Directive::OMPD_do:
-    SetContextDirectiveEnum(llvm::omp::Directive::OMPD_end_do);
-    SetContextAllowed(OmpClauseSet{llvm::omp::Clause::OMPC_nowait});
-    break;
   case llvm::omp::Directive::OMPD_do_simd:
-    SetContextDirectiveEnum(llvm::omp::Directive::OMPD_end_do_simd);
-    SetContextAllowed(OmpClauseSet{llvm::omp::Clause::OMPC_nowait});
+    SetClauseSets(dir.v);
     break;
   default:
     // no clauses are allowed
@@ -455,112 +187,7 @@
   const auto &beginDir{
       CheckMatching<parser::OmpBlockDirective>(beginBlockDir, endBlockDir)};
 
-  PushContext(beginDir.source, beginDir.v);
-  switch (beginDir.v) {
-  // 2.5 parallel-clause -> if-clause |
-  //                        num-threads-clause |
-  //                        default-clause |
-  //                        private-clause |
-  //                        firstprivate-clause |
-  //                        shared-clause |
-  //                        copyin-clause |
-  //                        reduction-clause |
-  //                        proc-bind-clause
-  case llvm::omp::Directive::OMPD_parallel: {
-    // reserve for nesting check
-    SetContextAllowed(parallelAllowedClauses);
-    SetContextAllowedOnce(parallelAllowedOnceClauses);
-  } break;
-  // 2.7.3 single-clause -> private-clause |
-  //                        firstprivate-clause
-  case llvm::omp::Directive::OMPD_single:
-    SetContextAllowed({llvm::omp::Clause::OMPC_private,
-        llvm::omp::Clause::OMPC_firstprivate});
-    break;
-  // 2.7.4 workshare (no clauses are allowed)
-  case llvm::omp::Directive::OMPD_workshare:
-    break;
-  // 2.11.3 parallel-workshare-clause -> parallel-clause
-  case llvm::omp::Directive::OMPD_parallel_workshare: {
-    SetContextAllowed(parallelAllowedClauses);
-    SetContextAllowedOnce(parallelAllowedOnceClauses);
-  } break;
-    // 2.9.1 task-clause -> if-clause |
-    //                      final-clause |
-    //                      untied-clause |
-    //                      default-clause |
-    //                      mergeable-clause |
-    //                      private-clause |
-    //                      firstprivate-clause |
-    //                      shared-clause |
-    //                      depend-clause |
-    //                      priority-clause
-  case llvm::omp::Directive::OMPD_task: {
-    OmpClauseSet allowed{llvm::omp::Clause::OMPC_untied,
-        llvm::omp::Clause::OMPC_default, llvm::omp::Clause::OMPC_mergeable,
-        llvm::omp::Clause::OMPC_private, llvm::omp::Clause::OMPC_firstprivate,
-        llvm::omp::Clause::OMPC_shared, llvm::omp::Clause::OMPC_depend};
-    SetContextAllowed(allowed);
-    OmpClauseSet allowedOnce{llvm::omp::Clause::OMPC_if,
-        llvm::omp::Clause::OMPC_final, llvm::omp::Clause::OMPC_priority};
-    SetContextAllowedOnce(allowedOnce);
-  } break;
-  // 2.10.4 target-clause -> if-clause |
-  //                         device-clause |
-  //                         private-clause |
-  //                         firstprivate-clause |
-  //                         map-clause |
-  //                         is-device-ptr-clause |
-  //                         defaultmap-clause |
-  //                         nowait-clause |
-  //                         depend-clause
-  case llvm::omp::Directive::OMPD_target: {
-    SetContextAllowed(targetAllowedClauses);
-    SetContextAllowedOnce(targetAllowedOnceClauses);
-  } break;
-  // 2.10.7 teams-clause -> num-teams-clause |
-  //                        thread-limit-clause |
-  //                        default-clause |
-  //                        private-clause |
-  //                        firstprivate-clause |
-  //                        shared-clause |
-  //                        reduction-clause
-  case llvm::omp::Directive::OMPD_teams: {
-    SetContextAllowed(teamsAllowedClauses);
-    SetContextAllowedOnce(teamsAllowedOnceClauses);
-  } break;
-  // 2.11.9 target-teams -> target-clause |
-  //                        teams-clause
-  case llvm::omp::Directive::OMPD_target_teams: {
-    SetContextAllowed(targetAllowedClauses | teamsAllowedClauses);
-    SetContextAllowedOnce(targetAllowedOnceClauses | teamsAllowedOnceClauses);
-  } break;
-  // 2.10.1 target-data-clause -> if-clause |
-  //                              device-clause |
-  //                              map-clause |
-  //                              use-device-ptr-clause
-  case llvm::omp::Directive::OMPD_target_data: {
-    OmpClauseSet allowed{llvm::omp::Clause::OMPC_if,
-        llvm::omp::Clause::OMPC_map, llvm::omp::Clause::OMPC_use_device_ptr};
-    SetContextAllowed(allowed);
-    SetContextAllowedOnce({llvm::omp::Clause::OMPC_device});
-    SetContextRequired({llvm::omp::Clause::OMPC_map});
-  } break;
-  // 2.13.1 master (no clauses are allowed)
-  case llvm::omp::Directive::OMPD_master:
-    break;
-  // 2.11.5 target-parallel-clause -> target-clause |
-  //                                  parallel-clause
-  case llvm::omp::Directive::OMPD_target_parallel: {
-    SetContextAllowed((targetAllowedClauses | parallelAllowedClauses) -
-        llvm::omp::Clause::OMPC_copyin);
-    SetContextAllowedOnce(
-        targetAllowedOnceClauses | parallelAllowedOnceClauses);
-  } break;
-  default:
-    // TODO others
-    break;
-  }
+  PushContextAndClauseSets(beginDir.source, beginDir.v);
 }
 
 void OmpStructureChecker::Leave(const parser::OpenMPBlockConstruct &) {
@@ -574,25 +201,7 @@
   const auto &beginDir{CheckMatching<parser::OmpSectionsDirective>(
       beginSectionsDir, endSectionsDir)};
 
-  PushContext(beginDir.source, beginDir.v);
-  switch (beginDir.v) {
-  // 2.7.2 sections-clause -> private-clause |
-  //                          firstprivate-clause |
-  //                          lastprivate-clause |
-  //                          reduction-clause
-  case llvm::omp::Directive::OMPD_sections: {
-    SetContextAllowed(sectionsAllowedClauses);
-  } break;
-    // 2.11.2 -> parallel-sections-clause -> parallel-clause |
-    //                                       sections-clause
-  case llvm::omp::Directive::OMPD_parallel_sections: {
-    SetContextAllowed(parallelAllowedClauses | sectionsAllowedClauses);
-    SetContextAllowedOnce(parallelAllowedOnceClauses);
-  } break;
-  default:
-    // TODO others
-    break;
-  }
+  PushContextAndClauseSets(beginDir.source, beginDir.v);
 }
 
 void OmpStructureChecker::Leave(const parser::OpenMPSectionsConstruct &) {
@@ -616,19 +225,7 @@
 
 void OmpStructureChecker::Enter(const parser::OpenMPDeclareSimdConstruct &x) {
   const auto &dir{std::get<parser::Verbatim>(x.t)};
-  PushContext(dir.source, llvm::omp::Directive::OMPD_declare_simd);
-  // 2.8.2 declare-simd-clause -> simdlen-clause |
-  //                              linear-clause |
-  //                              aligned-clause |
-  //                              uniform-clause |
-  //                              inbranch-clause |
-  //                              notinbranch-clause
-  OmpClauseSet allowed{llvm::omp::Clause::OMPC_linear,
-      llvm::omp::Clause::OMPC_aligned, llvm::omp::Clause::OMPC_uniform};
-  SetContextAllowed(allowed);
-  SetContextAllowedOnce({llvm::omp::Clause::OMPC_simdlen});
-  SetContextAllowedExclusive(
-      {llvm::omp::Clause::OMPC_inbranch, llvm::omp::Clause::OMPC_notinbranch});
+  PushContextAndClauseSets(dir.source, llvm::omp::Directive::OMPD_declare_simd);
 }
 
 void OmpStructureChecker::Leave(const parser::OpenMPDeclareSimdConstruct &) {
@@ -652,57 +249,7 @@
 void OmpStructureChecker::Enter(
     const parser::OpenMPSimpleStandaloneConstruct &x) {
   const auto &dir{std::get<parser::OmpSimpleStandaloneDirective>(x.t)};
-  PushContext(dir.source, dir.v);
-  switch (dir.v) {
-  case llvm::omp::Directive::OMPD_barrier: {
-    // 2.13.3 barrier
-  } break;
-  case llvm::omp::Directive::OMPD_taskwait: {
-    // 2.13.4 taskwait
-  } break;
-  case llvm::omp::Directive::OMPD_taskyield: {
-    // 2.9.4 taskyield
-  } break;
-  case llvm::omp::Directive::OMPD_target_enter_data: {
-    // 2.10.2 target-enter-data-clause -> if-clause |
-    //                                    device-clause |
-    //                                    map-clause |
-    //                                    depend-clause |
-    //                                    nowait-clause
-    OmpClauseSet allowed{llvm::omp::Clause::OMPC_map,
-        llvm::omp::Clause::OMPC_depend, llvm::omp::Clause::OMPC_nowait};
-    SetContextAllowed(allowed);
-    OmpClauseSet allowedOnce{
-        llvm::omp::Clause::OMPC_device, llvm::omp::Clause::OMPC_if};
-    SetContextAllowedOnce(allowedOnce);
-    SetContextRequired({llvm::omp::Clause::OMPC_map});
-  } break;
-  case llvm::omp::Directive::OMPD_target_exit_data: {
-    // 2.10.3  target-enter-data-clause -> if-clause |
-    //                                     device-clause |
-    //                                     map-clause |
-    //                                     depend-clause |
-    //                                     nowait-clause
-    OmpClauseSet allowed{llvm::omp::Clause::OMPC_map,
-        llvm::omp::Clause::OMPC_depend, llvm::omp::Clause::OMPC_nowait};
-    SetContextAllowed(allowed);
-    OmpClauseSet allowedOnce{
-        llvm::omp::Clause::OMPC_device, llvm::omp::Clause::OMPC_if};
-    SetContextAllowedOnce(allowedOnce);
-    SetContextRequired({llvm::omp::Clause::OMPC_map});
-  } break;
-  case llvm::omp::Directive::OMPD_target_update: {
-    // 2.10.5 target-update
-  } break;
-  case llvm::omp::Directive::OMPD_ordered: {
-    // 2.13.8 ordered-construct-clause -> depend-clause
-    OmpClauseSet allowed{llvm::omp::Clause::OMPC_depend};
-    SetContextAllowed(allowed);
-  } break;
-  default:
-    // TODO others
-    break;
-  }
+  PushContextAndClauseSets(dir.source, dir.v);
 }
 
 void OmpStructureChecker::Leave(
@@ -712,7 +259,7 @@
 
 void OmpStructureChecker::Enter(const parser::OpenMPFlushConstruct &x) {
   const auto &dir{std::get<parser::Verbatim>(x.t)};
-  PushContext(dir.source, llvm::omp::Directive::OMPD_flush);
+  PushContextAndClauseSets(dir.source, llvm::omp::Directive::OMPD_flush);
 }
 
 void OmpStructureChecker::Leave(const parser::OpenMPFlushConstruct &) {
@@ -721,7 +268,7 @@
 
 void OmpStructureChecker::Enter(const parser::OpenMPCancelConstruct &x) {
   const auto &dir{std::get<parser::Verbatim>(x.t)};
-  PushContext(dir.source, llvm::omp::Directive::OMPD_cancel);
+  PushContextAndClauseSets(dir.source, llvm::omp::Directive::OMPD_cancel);
 }
 
 void OmpStructureChecker::Leave(const parser::OpenMPCancelConstruct &) {
@@ -731,7 +278,8 @@
 void OmpStructureChecker::Enter(
     const parser::OpenMPCancellationPointConstruct &x) {
   const auto &dir{std::get<parser::Verbatim>(x.t)};
-  PushContext(dir.source, llvm::omp::Directive::OMPD_cancellation_point);
+  PushContextAndClauseSets(
+      dir.source, llvm::omp::Directive::OMPD_cancellation_point);
 }
 
 void OmpStructureChecker::Leave(
diff --git a/flang/test/Semantics/omp-clause-validity01.f90 b/flang/test/Semantics/omp-clause-validity01.f90
--- a/flang/test/Semantics/omp-clause-validity01.f90
+++ b/flang/test/Semantics/omp-clause-validity01.f90
@@ -458,7 +458,6 @@
   enddo
   !$omp end taskloop simd
 
-  !ERROR: REDUCTION clause is not allowed on the TASKLOOP SIMD directive
   !$omp taskloop simd reduction(+:a)
   do i = 1, N
      a = a + 3.14
diff --git a/llvm/include/llvm/Frontend/Directive/DirectiveBase.td b/llvm/include/llvm/Frontend/Directive/DirectiveBase.td
--- a/llvm/include/llvm/Frontend/Directive/DirectiveBase.td
+++ b/llvm/include/llvm/Frontend/Directive/DirectiveBase.td
@@ -43,6 +43,9 @@
   // Header file included in the implementation code generated. Ususally the
   // output file of the declaration code generation. Can be left blank.
   string includeHeader = "";
+
+  // EnumSet class name used for clauses to generated the allowed clauses map.
+  string clauseEnumSetClass = "";
 }
 
 // Information about a specific clause.
@@ -92,6 +95,9 @@
   // List of clauses that are allowed to appear only once.
   list<VersionedClause> allowedOnceClauses = [];
 
+  // List of clauses that are allowed but mutually exclusive.
+  list<VersionedClause> allowedExclusiveClauses = [];
+
   // List of clauses that are required.
   list<VersionedClause> requiredClauses = [];
 
diff --git a/llvm/include/llvm/Frontend/OpenMP/CMakeLists.txt b/llvm/include/llvm/Frontend/OpenMP/CMakeLists.txt
--- a/llvm/include/llvm/Frontend/OpenMP/CMakeLists.txt
+++ b/llvm/include/llvm/Frontend/OpenMP/CMakeLists.txt
@@ -1,3 +1,4 @@
 set(LLVM_TARGET_DEFINITIONS OMP.td)
 tablegen(LLVM OMP.h.inc --gen-directive-decl)
+tablegen(LLVM OMP.cpp.inc --gen-directive-gen)
 add_public_tablegen_target(omp_gen)
diff --git a/llvm/include/llvm/Frontend/OpenMP/OMP.td b/llvm/include/llvm/Frontend/OpenMP/OMP.td
--- a/llvm/include/llvm/Frontend/OpenMP/OMP.td
+++ b/llvm/include/llvm/Frontend/OpenMP/OMP.td
@@ -24,6 +24,7 @@
   let makeEnumAvailableInNamespace = 1;
   let enableBitmaskEnumInNamespace = 1;
   let includeHeader = "llvm/Frontend/OpenMP/OMP.h.inc";
+  let clauseEnumSetClass = "OmpClauseSet";
 }
 
 //===----------------------------------------------------------------------===//
@@ -201,10 +202,7 @@
 def OMP_ThreadPrivate : Directive<"threadprivate"> {}
 def OMP_Parallel : Directive<"parallel"> {
   let allowedClauses = [
-    VersionedClause<OMPC_If>,
-    VersionedClause<OMPC_NumThreads>,
     VersionedClause<OMPC_Default>,
-    VersionedClause<OMPC_ProcBind>,
     VersionedClause<OMPC_Private>,
     VersionedClause<OMPC_FirstPrivate>,
     VersionedClause<OMPC_Shared>,
@@ -212,11 +210,14 @@
     VersionedClause<OMPC_Copyin>,
     VersionedClause<OMPC_Allocate>
   ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_If>,
+    VersionedClause<OMPC_NumThreads>,
+    VersionedClause<OMPC_ProcBind>,
+  ];
 }
 def OMP_Task : Directive<"task"> {
   let allowedClauses = [
-    VersionedClause<OMPC_If>,
-    VersionedClause<OMPC_Final>,
     VersionedClause<OMPC_Default>,
     VersionedClause<OMPC_Private>,
     VersionedClause<OMPC_FirstPrivate>,
@@ -224,12 +225,16 @@
     VersionedClause<OMPC_Untied>,
     VersionedClause<OMPC_Mergeable>,
     VersionedClause<OMPC_Depend>,
-    VersionedClause<OMPC_Priority>,
     VersionedClause<OMPC_InReduction>,
     VersionedClause<OMPC_Allocate>,
     VersionedClause<OMPC_Detach, 50>,
     VersionedClause<OMPC_Affinity, 50>
   ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_If>,
+    VersionedClause<OMPC_Final>,
+    VersionedClause<OMPC_Priority>
+  ];
 }
 def OMP_Simd : Directive<"simd"> {
   let allowedClauses = [
@@ -237,15 +242,17 @@
     VersionedClause<OMPC_LastPrivate>,
     VersionedClause<OMPC_Linear>,
     VersionedClause<OMPC_Aligned>,
-    VersionedClause<OMPC_SafeLen>,
-    VersionedClause<OMPC_SimdLen>,
-    VersionedClause<OMPC_Collapse>,
     VersionedClause<OMPC_Reduction>,
     VersionedClause<OMPC_Allocate>,
-    VersionedClause<OMPC_If, 50>,
     VersionedClause<OMPC_NonTemporal, 50>,
     VersionedClause<OMPC_Order, 50>
   ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_Collapse>,
+    VersionedClause<OMPC_SafeLen>,
+    VersionedClause<OMPC_SimdLen>,
+    VersionedClause<OMPC_If, 50>,
+  ];
 }
 def OMP_For : Directive<"for"> {
   let allowedClauses = [
@@ -273,7 +280,8 @@
   let allowedOnceClauses = [
     VersionedClause<OMPC_Schedule>,
     VersionedClause<OMPC_Collapse>,
-    VersionedClause<OMPC_Ordered>
+    VersionedClause<OMPC_Ordered>,
+    VersionedClause<OMPC_NoWait>
   ];
 }
 def OMP_Sections : Directive<"sections"> {
@@ -345,30 +353,34 @@
 def OMP_Target : Directive<"target"> {
   let allowedClauses = [
     VersionedClause<OMPC_If>,
-    VersionedClause<OMPC_Device>,
     VersionedClause<OMPC_Map>,
     VersionedClause<OMPC_Private>,
-    VersionedClause<OMPC_NoWait>,
     VersionedClause<OMPC_Depend>,
-    VersionedClause<OMPC_DefaultMap>,
     VersionedClause<OMPC_FirstPrivate>,
     VersionedClause<OMPC_IsDevicePtr>,
     VersionedClause<OMPC_Reduction>,
     VersionedClause<OMPC_Allocate>,
     VersionedClause<OMPC_UsesAllocators, 50>
   ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_Device>,
+    VersionedClause<OMPC_DefaultMap>,
+    VersionedClause<OMPC_NoWait>
+  ];
 }
 def OMP_Teams : Directive<"teams"> {
   let allowedClauses = [
-    VersionedClause<OMPC_Default>,
     VersionedClause<OMPC_Private>,
     VersionedClause<OMPC_FirstPrivate>,
     VersionedClause<OMPC_Shared>,
     VersionedClause<OMPC_Reduction>,
-    VersionedClause<OMPC_NumTeams>,
-    VersionedClause<OMPC_ThreadLimit>,
     VersionedClause<OMPC_Allocate>
   ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_Default>,
+    VersionedClause<OMPC_NumTeams>,
+    VersionedClause<OMPC_ThreadLimit>
+  ];
 }
 def OMP_Cancel : Directive<"cancel"> {
   let allowedClauses = [
@@ -386,50 +398,64 @@
 }
 def OMP_TargetData : Directive<"target data"> {
   let allowedClauses = [
-    VersionedClause<OMPC_If>,
-    VersionedClause<OMPC_Device>,
     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>
+  ];
+  let allowedOnceClauses = [
     VersionedClause<OMPC_If>,
     VersionedClause<OMPC_Device>,
-    VersionedClause<OMPC_Map>,
-    VersionedClause<OMPC_NoWait>,
-    VersionedClause<OMPC_Depend>
+    VersionedClause<OMPC_NoWait>
   ];
 }
 def OMP_TargetExitData : Directive<"target exit data"> {
   let allowedClauses = [
-    VersionedClause<OMPC_If>,
+    VersionedClause<OMPC_Depend>,
+    VersionedClause<OMPC_Map>
+  ];
+  let allowedOnceClauses = [
     VersionedClause<OMPC_Device>,
-    VersionedClause<OMPC_Map>,
-    VersionedClause<OMPC_NoWait>,
-    VersionedClause<OMPC_Depend>
+    VersionedClause<OMPC_If>,
+    VersionedClause<OMPC_NoWait>
+  ];
+  let requiredClauses = [
+    VersionedClause<OMPC_Map>
   ];
 }
 def OMP_TargetParallel : Directive<"target parallel"> {
   let allowedClauses = [
-    VersionedClause<OMPC_If>,
-    VersionedClause<OMPC_Device>,
     VersionedClause<OMPC_Map>,
     VersionedClause<OMPC_NoWait>,
     VersionedClause<OMPC_Depend>,
     VersionedClause<OMPC_Private>,
     VersionedClause<OMPC_FirstPrivate>,
-    VersionedClause<OMPC_DefaultMap>,
-    VersionedClause<OMPC_NumThreads>,
     VersionedClause<OMPC_Default>,
-    VersionedClause<OMPC_ProcBind>,
     VersionedClause<OMPC_Shared>,
     VersionedClause<OMPC_Reduction>,
     VersionedClause<OMPC_IsDevicePtr>,
     VersionedClause<OMPC_Allocate>,
     VersionedClause<OMPC_UsesAllocators, 50>
   ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_DefaultMap>,
+    VersionedClause<OMPC_Device>,
+    VersionedClause<OMPC_If>,
+    VersionedClause<OMPC_NumThreads>,
+    VersionedClause<OMPC_ProcBind>
+  ];
 }
 def OMP_TargetParallelFor : Directive<"target parallel for"> {
   let allowedClauses = [
@@ -459,27 +485,31 @@
 }
 def OMP_TargetParallelDo : Directive<"target parallel do"> {
   let allowedClauses = [
-    VersionedClause<OMPC_If>,
-    VersionedClause<OMPC_Device>,
     VersionedClause<OMPC_Map>,
     VersionedClause<OMPC_Private>,
     VersionedClause<OMPC_FirstPrivate>,
     VersionedClause<OMPC_LastPrivate>,
-    VersionedClause<OMPC_NoWait>,
     VersionedClause<OMPC_Depend>,
-    VersionedClause<OMPC_DefaultMap>,
-    VersionedClause<OMPC_NumThreads>,
-    VersionedClause<OMPC_ProcBind>,
     VersionedClause<OMPC_Shared>,
     VersionedClause<OMPC_Reduction>,
-    VersionedClause<OMPC_Collapse>,
-    VersionedClause<OMPC_Schedule>,
-    VersionedClause<OMPC_Ordered>,
     VersionedClause<OMPC_Linear>,
     VersionedClause<OMPC_IsDevicePtr>,
     VersionedClause<OMPC_Allocator>,
     VersionedClause<OMPC_Order>,
-    VersionedClause<OMPC_UsesAllocators>
+    VersionedClause<OMPC_UsesAllocators>,
+    VersionedClause<OMPC_Default>,
+    VersionedClause<OMPC_Copyin>
+  ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_If>,
+    VersionedClause<OMPC_NumThreads>,
+    VersionedClause<OMPC_ProcBind>,
+    VersionedClause<OMPC_Device>,
+    VersionedClause<OMPC_DefaultMap>,
+    VersionedClause<OMPC_Schedule>,
+    VersionedClause<OMPC_Collapse>,
+    VersionedClause<OMPC_Ordered>,
+    VersionedClause<OMPC_NoWait>
   ];
 }
 def OMP_TargetUpdate : Directive<"target update"> {
@@ -558,27 +588,29 @@
 }
 def OMP_ParallelDoSimd : Directive<"parallel do simd"> {
   let allowedClauses = [
-    VersionedClause<OMPC_If>,
-    VersionedClause<OMPC_NumThreads>,
     VersionedClause<OMPC_Default>,
-    VersionedClause<OMPC_ProcBind>,
     VersionedClause<OMPC_Private>,
     VersionedClause<OMPC_FirstPrivate>,
     VersionedClause<OMPC_Shared>,
     VersionedClause<OMPC_Reduction>,
     VersionedClause<OMPC_Copyin>,
     VersionedClause<OMPC_LastPrivate>,
-    VersionedClause<OMPC_Collapse>,
-    VersionedClause<OMPC_Schedule>,
-    VersionedClause<OMPC_SafeLen>,
-    VersionedClause<OMPC_SimdLen>,
     VersionedClause<OMPC_Linear>,
     VersionedClause<OMPC_Aligned>,
-    VersionedClause<OMPC_Ordered>,
     VersionedClause<OMPC_Allocate>,
     VersionedClause<OMPC_NonTemporal>,
     VersionedClause<OMPC_Order>
   ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_If>,
+    VersionedClause<OMPC_NumThreads>,
+    VersionedClause<OMPC_ProcBind>,
+    VersionedClause<OMPC_Schedule>,
+    VersionedClause<OMPC_Ordered>,
+    VersionedClause<OMPC_Collapse>,
+    VersionedClause<OMPC_SafeLen>,
+    VersionedClause<OMPC_SimdLen>
+  ];
 }
 def OMP_ParallelMaster : Directive<"parallel master"> {
   let allowedClauses = [
@@ -597,7 +629,6 @@
 def OMP_ParallelSections : Directive<"parallel sections"> {
   let allowedClauses = [
     VersionedClause<OMPC_If>,
-    VersionedClause<OMPC_NumThreads>,
     VersionedClause<OMPC_Default>,
     VersionedClause<OMPC_ProcBind>,
     VersionedClause<OMPC_Private>,
@@ -608,6 +639,9 @@
     VersionedClause<OMPC_LastPrivate>,
     VersionedClause<OMPC_Allocate>
   ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_NumThreads>
+  ];
 }
 def OMP_ForSimd : Directive<"for simd"> {
   let allowedClauses = [
@@ -643,7 +677,8 @@
     VersionedClause<OMPC_Collapse>,
     VersionedClause<OMPC_Ordered>,
     VersionedClause<OMPC_SafeLen>,
-    VersionedClause<OMPC_SimdLen>
+    VersionedClause<OMPC_SimdLen>,
+    VersionedClause<OMPC_NoWait>
   ];
 }
 def OMP_CancellationPoint : Directive<"cancellation point"> {}
@@ -653,53 +688,74 @@
     VersionedClause<OMPC_Map>
   ];
 }
-def OMP_DeclareSimd : Directive<"declare simd"> {}
+def OMP_DeclareSimd : Directive<"declare simd"> {
+  let allowedClauses = [
+    VersionedClause<OMPC_Linear>,
+    VersionedClause<OMPC_Aligned>,
+    VersionedClause<OMPC_Uniform>
+  ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_SimdLen>
+  ];
+  let allowedExclusiveClauses = [
+    VersionedClause<OMPC_Inbranch>,
+    VersionedClause<OMPC_Notinbranch>
+  ];
+}
 def OMP_TaskLoop : Directive<"taskloop"> {
   let allowedClauses = [
-    VersionedClause<OMPC_If>,
     VersionedClause<OMPC_Shared>,
     VersionedClause<OMPC_Private>,
     VersionedClause<OMPC_FirstPrivate>,
     VersionedClause<OMPC_LastPrivate>,
     VersionedClause<OMPC_Default>,
-    VersionedClause<OMPC_Collapse>,
-    VersionedClause<OMPC_Final>,
     VersionedClause<OMPC_Untied>,
     VersionedClause<OMPC_Mergeable>,
-    VersionedClause<OMPC_Priority>,
-    VersionedClause<OMPC_GrainSize>,
     VersionedClause<OMPC_NoGroup>,
-    VersionedClause<OMPC_NumTasks>,
     VersionedClause<OMPC_Reduction>,
     VersionedClause<OMPC_InReduction>,
     VersionedClause<OMPC_Allocate>
   ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_If>,
+    VersionedClause<OMPC_Collapse>,
+    VersionedClause<OMPC_Final>,
+    VersionedClause<OMPC_Priority>,
+  ];
+  let allowedExclusiveClauses = [
+    VersionedClause<OMPC_GrainSize>,
+    VersionedClause<OMPC_NumTasks>
+  ];
 }
 def OMP_TaskLoopSimd : Directive<"taskloop simd"> {
   let allowedClauses = [
-    VersionedClause<OMPC_If>,
-    VersionedClause<OMPC_Shared>,
-    VersionedClause<OMPC_Private>,
+    VersionedClause<OMPC_Aligned>,
+    VersionedClause<OMPC_Allocate>,
+    VersionedClause<OMPC_Default>,
     VersionedClause<OMPC_FirstPrivate>,
+    VersionedClause<OMPC_InReduction>,
     VersionedClause<OMPC_LastPrivate>,
-    VersionedClause<OMPC_Default>,
-    VersionedClause<OMPC_Collapse>,
-    VersionedClause<OMPC_Final>,
-    VersionedClause<OMPC_Untied>,
-    VersionedClause<OMPC_Mergeable>,
-    VersionedClause<OMPC_Priority>,
     VersionedClause<OMPC_Linear>,
-    VersionedClause<OMPC_Aligned>,
-    VersionedClause<OMPC_SafeLen>,
-    VersionedClause<OMPC_SimdLen>,
-    VersionedClause<OMPC_GrainSize>,
+    VersionedClause<OMPC_Mergeable>,
     VersionedClause<OMPC_NoGroup>,
-    VersionedClause<OMPC_NumTasks>,
-    VersionedClause<OMPC_Reduction>,
-    VersionedClause<OMPC_InReduction>,
-    VersionedClause<OMPC_Allocate>,
     VersionedClause<OMPC_NonTemporal, 50>,
     VersionedClause<OMPC_Order, 50>,
+    VersionedClause<OMPC_Private>,
+    VersionedClause<OMPC_Reduction>,
+    VersionedClause<OMPC_Shared>,
+    VersionedClause<OMPC_Untied>
+  ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_If>,
+    VersionedClause<OMPC_Collapse>,
+    VersionedClause<OMPC_SafeLen>,
+    VersionedClause<OMPC_SimdLen>,
+    VersionedClause<OMPC_Final>,
+    VersionedClause<OMPC_Priority>
+  ];
+  let allowedExclusiveClauses = [
+    VersionedClause<OMPC_GrainSize>,
+    VersionedClause<OMPC_NumTasks>
   ];
 }
 def OMP_Distribute : Directive<"distribute"> {
@@ -707,10 +763,12 @@
     VersionedClause<OMPC_Private>,
     VersionedClause<OMPC_FirstPrivate>,
     VersionedClause<OMPC_LastPrivate>,
-    VersionedClause<OMPC_Collapse>,
-    VersionedClause<OMPC_DistSchedule>,
     VersionedClause<OMPC_Allocate>
   ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_Collapse>,
+    VersionedClause<OMPC_DistSchedule>
+  ];
 }
 def OMP_DeclareTarget : Directive<"declare target"> {}
 def OMP_EndDeclareTarget : Directive<"end declare target"> {}
@@ -735,21 +793,25 @@
 }
 def OMP_DistributeParallelDo : Directive<"distribute parallel do"> {
   let allowedClauses = [
+    VersionedClause<OMPC_Private>,
     VersionedClause<OMPC_FirstPrivate>,
     VersionedClause<OMPC_LastPrivate>,
+    VersionedClause<OMPC_Allocate>,
+    VersionedClause<OMPC_Order>,
+    VersionedClause<OMPC_Default>,
+    VersionedClause<OMPC_Shared>,
+    VersionedClause<OMPC_Reduction>,
+    VersionedClause<OMPC_Copyin>,
+    VersionedClause<OMPC_Linear>
+  ];
+  let allowedOnceClauses = [
     VersionedClause<OMPC_Collapse>,
     VersionedClause<OMPC_DistSchedule>,
     VersionedClause<OMPC_If>,
     VersionedClause<OMPC_NumThreads>,
-    VersionedClause<OMPC_Default>,
     VersionedClause<OMPC_ProcBind>,
-    VersionedClause<OMPC_Private>,
-    VersionedClause<OMPC_Shared>,
-    VersionedClause<OMPC_Reduction>,
-    VersionedClause<OMPC_Copyin>,
     VersionedClause<OMPC_Schedule>,
-    VersionedClause<OMPC_Allocate>,
-    VersionedClause<OMPC_Order>
+    VersionedClause<OMPC_Ordered>
   ];
 }
 def OMP_DistributeParallelForSimd : Directive<"distribute parallel for simd"> {
@@ -802,22 +864,31 @@
 }
 def OMP_DistributeSimd : Directive<"distribute simd"> {
   let allowedClauses = [
-    VersionedClause<OMPC_Private>,
+    VersionedClause<OMPC_Aligned>,
+    VersionedClause<OMPC_Allocate>,
+    VersionedClause<OMPC_Copyin>,
+    VersionedClause<OMPC_Default>,
+    VersionedClause<OMPC_Linear>,
     VersionedClause<OMPC_FirstPrivate>,
     VersionedClause<OMPC_LastPrivate>,
+    VersionedClause<OMPC_NonTemporal, 50>,
+    VersionedClause<OMPC_Order, 50>,
+    VersionedClause<OMPC_Private>,
+    VersionedClause<OMPC_Reduction>
+  ];
+  let allowedOnceClauses = [
     VersionedClause<OMPC_Collapse>,
     VersionedClause<OMPC_DistSchedule>,
-    VersionedClause<OMPC_Linear>,
-    VersionedClause<OMPC_Aligned>,
-    VersionedClause<OMPC_SafeLen>,
-    VersionedClause<OMPC_SimdLen>,
-    VersionedClause<OMPC_Reduction>,
-    VersionedClause<OMPC_Allocate>,
     VersionedClause<OMPC_If, 50>,
-    VersionedClause<OMPC_NonTemporal, 50>,
-    VersionedClause<OMPC_Order, 50>
+    VersionedClause<OMPC_NumThreads>,
+    VersionedClause<OMPC_Ordered>,
+    VersionedClause<OMPC_ProcBind>,
+    VersionedClause<OMPC_Schedule>,
+    VersionedClause<OMPC_SafeLen>,
+    VersionedClause<OMPC_SimdLen>
   ];
 }
+
 def OMP_TargetParallelForSimd : Directive<"target parallel for simd"> {
   let allowedClauses = [
     VersionedClause<OMPC_If>,
@@ -880,27 +951,33 @@
 }
 def OMP_TargetSimd : Directive<"target simd"> {
   let allowedClauses = [
-    VersionedClause<OMPC_If>,
-    VersionedClause<OMPC_Device>,
-    VersionedClause<OMPC_Map>,
-    VersionedClause<OMPC_Private>,
-    VersionedClause<OMPC_NoWait>,
+    VersionedClause<OMPC_Aligned>,
+    VersionedClause<OMPC_Allocate>,
     VersionedClause<OMPC_Depend>,
-    VersionedClause<OMPC_DefaultMap>,
     VersionedClause<OMPC_FirstPrivate>,
     VersionedClause<OMPC_IsDevicePtr>,
     VersionedClause<OMPC_LastPrivate>,
     VersionedClause<OMPC_Linear>,
-    VersionedClause<OMPC_Aligned>,
-    VersionedClause<OMPC_SafeLen>,
-    VersionedClause<OMPC_SimdLen>,
-    VersionedClause<OMPC_Collapse>,
-    VersionedClause<OMPC_Reduction>,
-    VersionedClause<OMPC_Allocate>,
+    VersionedClause<OMPC_Map>,
     VersionedClause<OMPC_NonTemporal, 50>,
+    VersionedClause<OMPC_NoWait>,
     VersionedClause<OMPC_Order, 50>,
+    VersionedClause<OMPC_Private>,
+    VersionedClause<OMPC_Reduction>,
+    VersionedClause<OMPC_Shared>,
     VersionedClause<OMPC_UsesAllocators, 50>
   ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_Collapse>,
+    VersionedClause<OMPC_SafeLen>,
+    VersionedClause<OMPC_SimdLen>,
+    VersionedClause<OMPC_If>,
+    VersionedClause<OMPC_NumThreads>,
+    VersionedClause<OMPC_ProcBind>,
+    VersionedClause<OMPC_Device>,
+    VersionedClause<OMPC_DefaultMap>,
+    VersionedClause<OMPC_Schedule>
+  ];
 }
 def OMP_TeamsDistribute : Directive<"teams distribute"> {
   let allowedClauses = [
@@ -919,26 +996,29 @@
 }
 def OMP_TeamsDistributeSimd : Directive<"teams distribute simd"> {
   let allowedClauses = [
-    VersionedClause<OMPC_Default>,
-    VersionedClause<OMPC_Private>,
+    VersionedClause<OMPC_Aligned>,
+    VersionedClause<OMPC_Allocate>,
     VersionedClause<OMPC_FirstPrivate>,
-    VersionedClause<OMPC_Shared>,
-    VersionedClause<OMPC_Reduction>,
-    VersionedClause<OMPC_NumTeams>,
-    VersionedClause<OMPC_ThreadLimit>,
     VersionedClause<OMPC_LastPrivate>,
+    VersionedClause<OMPC_Linear>,
+    VersionedClause<OMPC_NonTemporal, 50>,
+    VersionedClause<OMPC_Order, 50>,
+    VersionedClause<OMPC_Private>,
+    VersionedClause<OMPC_Reduction>,
+    VersionedClause<OMPC_Shared>
+  ];
+  let allowedOnceClauses = [
     VersionedClause<OMPC_Collapse>,
+    VersionedClause<OMPC_Default>,
     VersionedClause<OMPC_DistSchedule>,
-    VersionedClause<OMPC_Linear>,
-    VersionedClause<OMPC_Aligned>,
+    VersionedClause<OMPC_If, 50>,
+    VersionedClause<OMPC_NumTeams>,
     VersionedClause<OMPC_SafeLen>,
     VersionedClause<OMPC_SimdLen>,
-    VersionedClause<OMPC_Allocate>,
-    VersionedClause<OMPC_If, 50>,
-    VersionedClause<OMPC_NonTemporal, 50>,
-    VersionedClause<OMPC_Order, 50>
+    VersionedClause<OMPC_ThreadLimit>
   ];
 }
+
 def OMP_TeamsDistributeParallelForSimd :
     Directive<"teams distribute parallel for simd"> {
   let allowedClauses = [
@@ -968,27 +1048,29 @@
 def OMP_TeamsDistributeParallelDoSimd :
     Directive<"teams distribute parallel do simd"> {
   let allowedClauses = [
+    VersionedClause<OMPC_Private>,
     VersionedClause<OMPC_FirstPrivate>,
     VersionedClause<OMPC_LastPrivate>,
+    VersionedClause<OMPC_Allocate>,
+    VersionedClause<OMPC_Shared>,
+    VersionedClause<OMPC_Reduction>,
+    VersionedClause<OMPC_Linear>,
+    VersionedClause<OMPC_Order>,
+    VersionedClause<OMPC_Aligned>,
+    VersionedClause<OMPC_NonTemporal>
+  ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_Default>,
+    VersionedClause<OMPC_NumTeams>,
+    VersionedClause<OMPC_ThreadLimit>,
     VersionedClause<OMPC_Collapse>,
     VersionedClause<OMPC_DistSchedule>,
-    VersionedClause<OMPC_If>,
     VersionedClause<OMPC_NumThreads>,
-    VersionedClause<OMPC_Default>,
     VersionedClause<OMPC_ProcBind>,
-    VersionedClause<OMPC_Private>,
-    VersionedClause<OMPC_Shared>,
-    VersionedClause<OMPC_Reduction>,
     VersionedClause<OMPC_Schedule>,
-    VersionedClause<OMPC_Linear>,
-    VersionedClause<OMPC_Aligned>,
     VersionedClause<OMPC_SafeLen>,
     VersionedClause<OMPC_SimdLen>,
-    VersionedClause<OMPC_NumTeams>,
-    VersionedClause<OMPC_ThreadLimit>,
-    VersionedClause<OMPC_Allocate>,
-    VersionedClause<OMPC_NonTemporal>,
-    VersionedClause<OMPC_Order>
+    VersionedClause<OMPC_If>,
   ];
 }
 def OMP_TeamsDistributeParallelFor :
@@ -1016,68 +1098,78 @@
 def OMP_TeamsDistributeParallelDo :
     Directive<"teams distribute parallel do"> {
   let allowedClauses = [
+    VersionedClause<OMPC_Private>,
     VersionedClause<OMPC_FirstPrivate>,
     VersionedClause<OMPC_LastPrivate>,
+    VersionedClause<OMPC_Shared>,
+    VersionedClause<OMPC_Reduction>,
+    VersionedClause<OMPC_Allocate>,
+    VersionedClause<OMPC_Copyin>,
+    VersionedClause<OMPC_Linear>
+  ];
+let allowedOnceClauses = [
+    VersionedClause<OMPC_NumTeams>,
+    VersionedClause<OMPC_ThreadLimit>,
+    VersionedClause<OMPC_Default>,
     VersionedClause<OMPC_Collapse>,
     VersionedClause<OMPC_DistSchedule>,
+    VersionedClause<OMPC_Ordered>,
+    VersionedClause<OMPC_Order>,
     VersionedClause<OMPC_If>,
     VersionedClause<OMPC_NumThreads>,
-    VersionedClause<OMPC_Default>,
     VersionedClause<OMPC_ProcBind>,
-    VersionedClause<OMPC_Private>,
-    VersionedClause<OMPC_Shared>,
-    VersionedClause<OMPC_Reduction>,
-    VersionedClause<OMPC_Schedule>,
-    VersionedClause<OMPC_NumTeams>,
-    VersionedClause<OMPC_ThreadLimit>,
-    VersionedClause<OMPC_Copyin>,
-    VersionedClause<OMPC_Allocate>,
-    VersionedClause<OMPC_Order>
+    VersionedClause<OMPC_Schedule>
   ];
 }
 def OMP_TargetTeams : Directive<"target teams"> {
   let allowedClauses = [
     VersionedClause<OMPC_If>,
-    VersionedClause<OMPC_Device>,
     VersionedClause<OMPC_Map>,
     VersionedClause<OMPC_Private>,
-    VersionedClause<OMPC_NoWait>,
     VersionedClause<OMPC_Depend>,
-    VersionedClause<OMPC_DefaultMap>,
     VersionedClause<OMPC_FirstPrivate>,
     VersionedClause<OMPC_IsDevicePtr>,
-    VersionedClause<OMPC_Default>,
-    VersionedClause<OMPC_Shared>,
     VersionedClause<OMPC_Reduction>,
-    VersionedClause<OMPC_NumTeams>,
-    VersionedClause<OMPC_ThreadLimit>,
     VersionedClause<OMPC_Allocate>,
-    VersionedClause<OMPC_UsesAllocators, 50>
+    VersionedClause<OMPC_UsesAllocators, 50>,
+    VersionedClause<OMPC_Shared>
+  ];
+
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_Device>,
+    VersionedClause<OMPC_NoWait>,
+    VersionedClause<OMPC_DefaultMap>,
+    VersionedClause<OMPC_Default>,
+    VersionedClause<OMPC_NumTeams>,
+    VersionedClause<OMPC_ThreadLimit>
   ];
 }
 def OMP_TargetTeamsDistribute : Directive<"target teams distribute"> {
   let allowedClauses = [
     VersionedClause<OMPC_If>,
-    VersionedClause<OMPC_Device>,
     VersionedClause<OMPC_Map>,
     VersionedClause<OMPC_Private>,
-    VersionedClause<OMPC_NoWait>,
     VersionedClause<OMPC_Depend>,
-    VersionedClause<OMPC_DefaultMap>,
     VersionedClause<OMPC_FirstPrivate>,
     VersionedClause<OMPC_IsDevicePtr>,
-    VersionedClause<OMPC_Default>,
-    VersionedClause<OMPC_Shared>,
     VersionedClause<OMPC_Reduction>,
+    VersionedClause<OMPC_Allocate>,
+    VersionedClause<OMPC_UsesAllocators, 50>,
+    VersionedClause<OMPC_Shared>,
+    VersionedClause<OMPC_LastPrivate>
+  ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_Device>,
+    VersionedClause<OMPC_NoWait>,
+    VersionedClause<OMPC_DefaultMap>,
+    VersionedClause<OMPC_Default>,
     VersionedClause<OMPC_NumTeams>,
     VersionedClause<OMPC_ThreadLimit>,
-    VersionedClause<OMPC_LastPrivate>,
     VersionedClause<OMPC_Collapse>,
-    VersionedClause<OMPC_DistSchedule>,
-    VersionedClause<OMPC_Allocate>,
-    VersionedClause<OMPC_UsesAllocators, 50>
+    VersionedClause<OMPC_DistSchedule>
   ];
 }
+
 def OMP_TargetTeamsDistributeParallelFor :
     Directive<"target teams distribute parallel for"> {
   let allowedClauses = [
@@ -1110,28 +1202,33 @@
     Directive<"target teams distribute parallel do"> {
   let allowedClauses = [
     VersionedClause<OMPC_If>,
-    VersionedClause<OMPC_Device>,
     VersionedClause<OMPC_Map>,
     VersionedClause<OMPC_Private>,
-    VersionedClause<OMPC_NoWait>,
     VersionedClause<OMPC_Depend>,
-    VersionedClause<OMPC_DefaultMap>,
     VersionedClause<OMPC_FirstPrivate>,
     VersionedClause<OMPC_IsDevicePtr>,
-    VersionedClause<OMPC_Default>,
-    VersionedClause<OMPC_Shared>,
     VersionedClause<OMPC_Reduction>,
+    VersionedClause<OMPC_Allocate>,
+    VersionedClause<OMPC_UsesAllocators>,
+    VersionedClause<OMPC_Shared>,
+    VersionedClause<OMPC_LastPrivate>,
+    VersionedClause<OMPC_Copyin>,
+    VersionedClause<OMPC_Linear>,
+    VersionedClause<OMPC_Ordered>,
+    VersionedClause<OMPC_Order>
+  ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_Device>,
+    VersionedClause<OMPC_DefaultMap>,
+    VersionedClause<OMPC_NoWait>,
+    VersionedClause<OMPC_Default>,
     VersionedClause<OMPC_NumTeams>,
     VersionedClause<OMPC_ThreadLimit>,
-    VersionedClause<OMPC_LastPrivate>,
     VersionedClause<OMPC_Collapse>,
     VersionedClause<OMPC_DistSchedule>,
     VersionedClause<OMPC_NumThreads>,
     VersionedClause<OMPC_ProcBind>,
     VersionedClause<OMPC_Schedule>,
-    VersionedClause<OMPC_Allocate>,
-    VersionedClause<OMPC_Order>,
-    VersionedClause<OMPC_UsesAllocators>
   ];
 }
 def OMP_TargetTeamsDistributeParallelForSimd :
@@ -1170,63 +1267,69 @@
 def OMP_TargetTeamsDistributeParallelDoSimd :
     Directive<"target teams distribute parallel do simd"> {
   let allowedClauses = [
-    VersionedClause<OMPC_If>,
-    VersionedClause<OMPC_Device>,
     VersionedClause<OMPC_Map>,
     VersionedClause<OMPC_Private>,
-    VersionedClause<OMPC_NoWait>,
     VersionedClause<OMPC_Depend>,
-    VersionedClause<OMPC_DefaultMap>,
     VersionedClause<OMPC_FirstPrivate>,
     VersionedClause<OMPC_IsDevicePtr>,
-    VersionedClause<OMPC_Default>,
-    VersionedClause<OMPC_Shared>,
     VersionedClause<OMPC_Reduction>,
+    VersionedClause<OMPC_Allocate>,
+    VersionedClause<OMPC_UsesAllocators>,
+    VersionedClause<OMPC_Shared>,
+    VersionedClause<OMPC_LastPrivate>,
+    VersionedClause<OMPC_Copyin>,
+    VersionedClause<OMPC_Linear>,
+    VersionedClause<OMPC_Ordered>,
+    VersionedClause<OMPC_Order>,
+    VersionedClause<OMPC_Aligned>,
+    VersionedClause<OMPC_NonTemporal>
+  ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_If>,
+    VersionedClause<OMPC_Device>,
+    VersionedClause<OMPC_NoWait>,
+    VersionedClause<OMPC_DefaultMap>,
+    VersionedClause<OMPC_Default>,
     VersionedClause<OMPC_NumTeams>,
     VersionedClause<OMPC_ThreadLimit>,
-    VersionedClause<OMPC_LastPrivate>,
     VersionedClause<OMPC_Collapse>,
     VersionedClause<OMPC_DistSchedule>,
     VersionedClause<OMPC_NumThreads>,
     VersionedClause<OMPC_ProcBind>,
     VersionedClause<OMPC_Schedule>,
-    VersionedClause<OMPC_Linear>,
-    VersionedClause<OMPC_Aligned>,
     VersionedClause<OMPC_SafeLen>,
-    VersionedClause<OMPC_SimdLen>,
-    VersionedClause<OMPC_Allocate>,
-    VersionedClause<OMPC_NonTemporal>,
-    VersionedClause<OMPC_Order>,
-    VersionedClause<OMPC_UsesAllocators>
+    VersionedClause<OMPC_SimdLen>
   ];
 }
 def OMP_TargetTeamsDistributeSimd :
     Directive<"target teams distribute simd"> {
   let allowedClauses = [
-    VersionedClause<OMPC_If>,
-    VersionedClause<OMPC_Device>,
-    VersionedClause<OMPC_Map>,
-    VersionedClause<OMPC_Private>,
-    VersionedClause<OMPC_NoWait>,
+    VersionedClause<OMPC_Aligned>,
+    VersionedClause<OMPC_Allocate>,
     VersionedClause<OMPC_Depend>,
-    VersionedClause<OMPC_DefaultMap>,
     VersionedClause<OMPC_FirstPrivate>,
-    VersionedClause<OMPC_LastPrivate>,
+    VersionedClause<OMPC_If>,
     VersionedClause<OMPC_IsDevicePtr>,
-    VersionedClause<OMPC_Shared>,
+    VersionedClause<OMPC_LastPrivate>,
+    VersionedClause<OMPC_Linear>,
+    VersionedClause<OMPC_Map>,
+    VersionedClause<OMPC_NonTemporal, 50>,
+    VersionedClause<OMPC_Order, 50>,
+    VersionedClause<OMPC_Private>,
     VersionedClause<OMPC_Reduction>,
+    VersionedClause<OMPC_Shared>,
+    VersionedClause<OMPC_UsesAllocators, 50>
+  ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_Device>,
+    VersionedClause<OMPC_DefaultMap>,
+    VersionedClause<OMPC_NoWait>,
     VersionedClause<OMPC_NumTeams>,
     VersionedClause<OMPC_ThreadLimit>,
     VersionedClause<OMPC_Collapse>,
     VersionedClause<OMPC_DistSchedule>,
-    VersionedClause<OMPC_Linear>,
-    VersionedClause<OMPC_Aligned>,
     VersionedClause<OMPC_SafeLen>,
     VersionedClause<OMPC_SimdLen>,
-    VersionedClause<OMPC_Allocate>,
-    VersionedClause<OMPC_NonTemporal, 50>,
-    VersionedClause<OMPC_Order, 50>,
-    VersionedClause<OMPC_UsesAllocators, 50>
   ];
 }
 def OMP_Allocate : Directive<"allocate"> {
@@ -1359,7 +1462,22 @@
 }
 def OMP_BeginDeclareVariant : Directive<"begin declare variant"> {}
 def OMP_EndDeclareVariant : Directive<"end declare variant"> {}
-def OMP_ParallelWorkshare : Directive<"parallel workshare"> {}
+def OMP_ParallelWorkshare : Directive<"parallel workshare"> {
+  let allowedClauses = [
+    VersionedClause<OMPC_Allocate>,
+    VersionedClause<OMPC_Copyin>,
+    VersionedClause<OMPC_Default>,
+    VersionedClause<OMPC_FirstPrivate>,
+    VersionedClause<OMPC_Private>,
+    VersionedClause<OMPC_Reduction>,
+    VersionedClause<OMPC_Shared>
+  ];
+  let allowedOnceClauses = [
+    VersionedClause<OMPC_If>,
+    VersionedClause<OMPC_NumThreads>,
+    VersionedClause<OMPC_ProcBind>
+  ];
+}
 def OMP_Workshare : Directive<"workshare"> {}
 def OMP_EndDo : Directive<"end do"> {}
 def OMP_EndDoSimd : Directive<"end do simd"> {}
diff --git a/llvm/test/TableGen/directive1.td b/llvm/test/TableGen/directive1.td
--- a/llvm/test/TableGen/directive1.td
+++ b/llvm/test/TableGen/directive1.td
@@ -1,5 +1,6 @@
 // RUN: llvm-tblgen -gen-directive-decl -I %p/../../include %s | FileCheck -match-full-lines %s
 // RUN: llvm-tblgen -gen-directive-impl -I %p/../../include %s | FileCheck -match-full-lines %s -check-prefix=IMPL
+// RUN: llvm-tblgen -gen-directive-gen -I %p/../../include %s | FileCheck -match-full-lines %s -check-prefix=GEN
 
 include "llvm/Frontend/Directive/DirectiveBase.td"
 
@@ -126,3 +127,57 @@
 // IMPL-NEXT:    }
 // IMPL-NEXT:    llvm_unreachable("Invalid Tdl Directive kind");
 // IMPL-NEXT:  }
+// IMPL-EMPTY:
+
+
+
+// GEN:       #ifdef GEN_FLANG_DIRECTIVE_CLAUSE_SETS
+// GEN-NEXT:  #undef GEN_FLANG_DIRECTIVE_CLAUSE_SETS
+// GEN-EMPTY:
+// GEN-NEXT:  namespace llvm {
+// GEN-NEXT:  namespace tdl {
+// GEN-EMPTY:
+// GEN-NEXT:    // Sets for dira
+// GEN-EMPTY:
+// GEN-NEXT:    static  allowedClauses_TDLD_dira {
+// GEN-NEXT:      llvm::tdl::Clause::TDLC_clausea,
+// GEN-NEXT:      llvm::tdl::Clause::TDLC_clauseb,
+// GEN-NEXT:    };
+// GEN-EMPTY:
+// GEN-NEXT:    static  allowedOnceClauses_TDLD_dira {
+// GEN-NEXT:    };
+// GEN-EMPTY:
+// GEN-NEXT:    static  allowedExclusiveClauses_TDLD_dira {
+// GEN-NEXT:    };
+// GEN-EMPTY:
+// GEN-NEXT:    static  requiredClauses_TDLD_dira {
+// GEN-NEXT:    };
+// GEN-NEXT:  } // namespace tdl
+// GEN-NEXT:  } // namespace llvm
+// GEN-EMPTY:
+// GEN-NEXT:  #endif // GEN_FLANG_DIRECTIVE_CLAUSE_SETS
+// GEN-EMPTY:
+// GEN-NEXT:  #ifdef GEN_FLANG_DIRECTIVE_CLAUSE_MAP
+// GEN-NEXT:  #undef GEN_FLANG_DIRECTIVE_CLAUSE_MAP
+// GEN-EMPTY:
+// GEN-NEXT:  struct TdlDirectiveClauses {
+// GEN-NEXT:    const  allowed;
+// GEN-NEXT:    const  allowedOnce;
+// GEN-NEXT:    const  allowedExclusive;
+// GEN-NEXT:    const  requiredOneOf;
+// GEN-NEXT:  };
+// GEN-EMPTY:
+// GEN-NEXT:  std::unordered_map<llvm::tdl::Directive, TdlDirectiveClauses>
+// GEN-NEXT:      directiveClausesTable = {
+// GEN-NEXT:    {llvm::tdl::Directive::TDLD_dira,
+// GEN-NEXT:      {
+// GEN-NEXT:        llvm::tdl::allowedClauses_TDLD_dira,
+// GEN-NEXT:        llvm::tdl::allowedOnceClauses_TDLD_dira,
+// GEN-NEXT:        llvm::tdl::allowedExclusiveClauses_TDLD_dira,
+// GEN-NEXT:        llvm::tdl::requiredClauses_TDLD_dira,
+// GEN-NEXT:      }
+// GEN-NEXT:    },
+// GEN-NEXT:  };
+// GEN-EMPTY:
+// GEN-NEXT:  #endif // GEN_FLANG_DIRECTIVE_CLAUSE_MAP
+
diff --git a/llvm/test/TableGen/directive2.td b/llvm/test/TableGen/directive2.td
--- a/llvm/test/TableGen/directive2.td
+++ b/llvm/test/TableGen/directive2.td
@@ -1,5 +1,6 @@
 // RUN: llvm-tblgen -gen-directive-decl -I %p/../../include %s | FileCheck -match-full-lines %s
 // RUN: llvm-tblgen -gen-directive-impl -I %p/../../include %s | FileCheck -match-full-lines %s -check-prefix=IMPL
+// RUN: llvm-tblgen -gen-directive-gen -I %p/../../include %s | FileCheck -match-full-lines %s -check-prefix=GEN
 
 include "llvm/Frontend/Directive/DirectiveBase.td"
 
@@ -71,7 +72,7 @@
 // IMPL-NEXT:  using namespace llvm;
 // IMPL-NEXT:  using namespace tdl;
 // IMPL-EMPTY:
-// IMPL:       Directive llvm::tdl::getTdlDirectiveKind(llvm::StringRef Str) {
+// IMPL-NEXT:  Directive llvm::tdl::getTdlDirectiveKind(llvm::StringRef Str) {
 // IMPL-NEXT:    return llvm::StringSwitch<Directive>(Str)
 // IMPL-NEXT:      .Case("dira",TDLD_dira)
 // IMPL-NEXT:      .Default(TDLD_dira);
@@ -119,3 +120,54 @@
 // IMPL-NEXT:    }
 // IMPL-NEXT:    llvm_unreachable("Invalid Tdl Directive kind");
 // IMPL-NEXT:  }
+
+
+// GEN:      #ifdef GEN_FLANG_DIRECTIVE_CLAUSE_SETS
+// GEN-NEXT: #undef GEN_FLANG_DIRECTIVE_CLAUSE_SETS
+// GEN-EMPTY:
+// GEN-NEXT: namespace llvm {
+// GEN-NEXT: namespace tdl {
+// GEN-EMPTY:
+// GEN-NEXT:   // Sets for dira
+// GEN-EMPTY:
+// GEN-NEXT:   static  allowedClauses_TDLD_dira {
+// GEN-NEXT:     llvm::tdl::Clause::TDLC_clausea,
+// GEN-NEXT:     llvm::tdl::Clause::TDLC_clauseb,
+// GEN-NEXT:   };
+// GEN-EMPTY:
+// GEN-NEXT:   static  allowedOnceClauses_TDLD_dira {
+// GEN-NEXT:   };
+// GEN-EMPTY:
+// GEN-NEXT:   static  allowedExclusiveClauses_TDLD_dira {
+// GEN-NEXT:   };
+// GEN-EMPTY:
+// GEN-NEXT:   static  requiredClauses_TDLD_dira {
+// GEN-NEXT:   };
+// GEN-NEXT: } // namespace tdl
+// GEN-NEXT: } // namespace llvm
+// GEN-EMPTY:
+// GEN-NEXT: #endif // GEN_FLANG_DIRECTIVE_CLAUSE_SETS
+// GEN-EMPTY:
+// GEN-NEXT: #ifdef GEN_FLANG_DIRECTIVE_CLAUSE_MAP
+// GEN-NEXT: #undef GEN_FLANG_DIRECTIVE_CLAUSE_MAP
+// GEN-EMPTY:
+// GEN-NEXT: struct TdlDirectiveClauses {
+// GEN-NEXT:   const  allowed;
+// GEN-NEXT:   const  allowedOnce;
+// GEN-NEXT:   const  allowedExclusive;
+// GEN-NEXT:   const  requiredOneOf;
+// GEN-NEXT: };
+// GEN-EMPTY:
+// GEN-NEXT: std::unordered_map<llvm::tdl::Directive, TdlDirectiveClauses>
+// GEN-NEXT:     directiveClausesTable = {
+// GEN-NEXT:   {llvm::tdl::Directive::TDLD_dira,
+// GEN-NEXT:     {
+// GEN-NEXT:       llvm::tdl::allowedClauses_TDLD_dira,
+// GEN-NEXT:       llvm::tdl::allowedOnceClauses_TDLD_dira,
+// GEN-NEXT:       llvm::tdl::allowedExclusiveClauses_TDLD_dira,
+// GEN-NEXT:       llvm::tdl::requiredClauses_TDLD_dira,
+// GEN-NEXT:     }
+// GEN-NEXT:   },
+// GEN-NEXT: };
+// GEN-EMPTY:
+// GEN-NEXT: #endif // GEN_FLANG_DIRECTIVE_CLAUSE_MAP
diff --git a/llvm/utils/TableGen/DirectiveEmitter.cpp b/llvm/utils/TableGen/DirectiveEmitter.cpp
--- a/llvm/utils/TableGen/DirectiveEmitter.cpp
+++ b/llvm/utils/TableGen/DirectiveEmitter.cpp
@@ -14,12 +14,30 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/StringSet.h"
 #include "llvm/TableGen/Error.h"
 #include "llvm/TableGen/Record.h"
 #include "llvm/TableGen/TableGenBackend.h"
 
 using namespace llvm;
 
+namespace {
+// Simple RAII helper for defining ifdef-undef-endif scopes.
+class IfDefScope {
+public:
+  IfDefScope(StringRef Name, raw_ostream &OS) : Name(Name), OS(OS) {
+    OS << "#ifdef " << Name << "\n"
+       << "#undef " << Name << "\n";
+  }
+
+  ~IfDefScope() { OS << "\n#endif // " << Name << "\n\n"; }
+
+private:
+  StringRef Name;
+  raw_ostream &OS;
+};
+} // end anonymous namespace
+
 namespace llvm {
 
 // Get Directive or Clause name formatted by replacing whitespaces with
@@ -205,16 +223,21 @@
 void GenerateCaseForVersionedClauses(const std::vector<Record *> &Clauses,
                                      raw_ostream &OS, StringRef DirectiveName,
                                      StringRef DirectivePrefix,
-                                     StringRef ClausePrefix) {
+                                     StringRef ClausePrefix,
+                                     llvm::StringSet<> &Cases) {
   for (const auto &C : Clauses) {
     const auto MinVersion = C->getValueAsInt("minVersion");
     const auto MaxVersion = C->getValueAsInt("maxVersion");
     const auto SpecificClause = C->getValueAsDef("clause");
-    const auto ClauseName = SpecificClause->getValueAsString("name");
-    OS << "        case " << ClausePrefix << getFormattedName(ClauseName)
-       << ":\n";
-    OS << "          return " << MinVersion << " <= Version && " << MaxVersion
-       << " >= Version;\n";
+    const auto ClauseName =
+        getFormattedName(SpecificClause->getValueAsString("name"));
+
+    if (Cases.find(ClauseName) == Cases.end()) {
+      Cases.insert(ClauseName);
+      OS << "        case " << ClausePrefix << ClauseName << ":\n";
+      OS << "          return " << MinVersion << " <= Version && " << MaxVersion
+         << " >= Version;\n";
+    }
   }
 }
 
@@ -239,24 +262,32 @@
     const auto &AllowedClauses = D->getValueAsListOfDefs("allowedClauses");
     const auto &AllowedOnceClauses =
         D->getValueAsListOfDefs("allowedOnceClauses");
+    const auto &AllowedExclusiveClauses =
+        D->getValueAsListOfDefs("allowedExclusiveClauses");
     const auto &RequiredClauses = D->getValueAsListOfDefs("requiredClauses");
 
     OS << "    case " << DirectivePrefix << getFormattedName(DirectiveName)
        << ":\n";
-    if (AllowedClauses.size() == 0 && AllowedOnceClauses.size() == 0 && 
-        AllowedOnceClauses.size() == 0) {
+    if (AllowedClauses.size() == 0 && AllowedOnceClauses.size() == 0 &&
+        AllowedExclusiveClauses.size() == 0 && RequiredClauses.size() == 0) {
       OS << "      return false;\n";
     } else {
       OS << "      switch (C) {\n";
 
+      llvm::StringSet<> Cases;
+
       GenerateCaseForVersionedClauses(AllowedClauses, OS, DirectiveName,
-                                      DirectivePrefix, ClausePrefix);
+                                      DirectivePrefix, ClausePrefix, Cases);
 
       GenerateCaseForVersionedClauses(AllowedOnceClauses, OS, DirectiveName,
-                                      DirectivePrefix, ClausePrefix);
+                                      DirectivePrefix, ClausePrefix, Cases);
+
+      GenerateCaseForVersionedClauses(AllowedExclusiveClauses, OS,
+                                      DirectiveName, DirectivePrefix,
+                                      ClausePrefix, Cases);
 
       GenerateCaseForVersionedClauses(RequiredClauses, OS, DirectiveName,
-                                      DirectivePrefix, ClausePrefix);
+                                      DirectivePrefix, ClausePrefix, Cases);
 
       OS << "        default:\n";
       OS << "          return false;\n";
@@ -271,9 +302,143 @@
   OS << "}\n"; // End of function isAllowedClauseForDirective
 }
 
+// Generate a simple enum set with the give clauses.
+void GenerateClauseSet(const std::vector<Record *> &Clauses, raw_ostream &OS,
+                       StringRef ClauseEnumSetClass, StringRef ClauseSetPrefix,
+                       StringRef DirectiveName, StringRef DirectivePrefix,
+                       StringRef ClausePrefix, StringRef CppNamespace) {
+
+  OS << "\n";
+  OS << "  static " << ClauseEnumSetClass << " " << ClauseSetPrefix
+     << DirectivePrefix << getFormattedName(DirectiveName) << " {\n";
+
+  for (const auto &C : Clauses) {
+    const auto SpecificClause = C->getValueAsDef("clause");
+    const auto ClauseName = SpecificClause->getValueAsString("name");
+    OS << "    llvm::" << CppNamespace << "::Clause::" << ClausePrefix
+       << getFormattedName(ClauseName) << ",\n";
+  }
+  OS << "  };\n";
+}
+
+// Generate an enum set for the 4 kinds of clauses linked to a directive.
+void GenerateDirectiveClauseSets(const std::vector<Record *> &Directives,
+                                 raw_ostream &OS, StringRef LanguageName,
+                                 StringRef ClauseEnumSetClass,
+                                 StringRef DirectivePrefix,
+                                 StringRef ClausePrefix,
+                                 StringRef CppNamespace) {
+
+  IfDefScope Scope("GEN_FLANG_DIRECTIVE_CLAUSE_SETS", OS);
+
+  OS << "\n";
+  OS << "namespace llvm {\n";
+
+  // Open namespaces defined in the directive language.
+  llvm::SmallVector<StringRef, 2> Namespaces;
+  llvm::SplitString(CppNamespace, Namespaces, "::");
+  for (auto Ns : Namespaces)
+    OS << "namespace " << Ns << " {\n";
+
+  for (const auto &D : Directives) {
+    const auto DirectiveName = D->getValueAsString("name");
+
+    const auto &AllowedClauses = D->getValueAsListOfDefs("allowedClauses");
+    const auto &AllowedOnceClauses =
+        D->getValueAsListOfDefs("allowedOnceClauses");
+    const auto &AllowedExclusiveClauses =
+        D->getValueAsListOfDefs("allowedExclusiveClauses");
+    const auto &RequiredClauses = D->getValueAsListOfDefs("requiredClauses");
+
+    OS << "\n";
+    OS << "  // Sets for " << DirectiveName << "\n";
+
+    GenerateClauseSet(AllowedClauses, OS, ClauseEnumSetClass, "allowedClauses_",
+                      DirectiveName, DirectivePrefix, ClausePrefix,
+                      CppNamespace);
+    GenerateClauseSet(AllowedOnceClauses, OS, ClauseEnumSetClass,
+                      "allowedOnceClauses_", DirectiveName, DirectivePrefix,
+                      ClausePrefix, CppNamespace);
+    GenerateClauseSet(AllowedExclusiveClauses, OS, ClauseEnumSetClass,
+                      "allowedExclusiveClauses_", DirectiveName,
+                      DirectivePrefix, ClausePrefix, CppNamespace);
+    GenerateClauseSet(RequiredClauses, OS, ClauseEnumSetClass,
+                      "requiredClauses_", DirectiveName, DirectivePrefix,
+                      ClausePrefix, CppNamespace);
+  }
+
+  // Closing namespaces
+  for (auto Ns : llvm::reverse(Namespaces))
+    OS << "} // namespace " << Ns << "\n";
+
+  OS << "} // namespace llvm\n";
+}
+
+// Generate a map of directive (key) with DirectiveClauses struct as values.
+// The struct holds the 4 sets of enumeration for the 4 kinds of clauses
+// allowances (allowed, allowed once, allowed exclusive and required).
+void GenerateDirectiveClauseMap(const std::vector<Record *> &Directives,
+                                raw_ostream &OS, StringRef LanguageName,
+                                StringRef ClauseEnumSetClass,
+                                StringRef DirectivePrefix,
+                                StringRef ClausePrefix,
+                                StringRef CppNamespace) {
+
+  IfDefScope Scope("GEN_FLANG_DIRECTIVE_CLAUSE_MAP", OS);
+
+  OS << "\n";
+  OS << "struct " << LanguageName << "DirectiveClauses {\n";
+  OS << "  const " << ClauseEnumSetClass << " allowed;\n";
+  OS << "  const " << ClauseEnumSetClass << " allowedOnce;\n";
+  OS << "  const " << ClauseEnumSetClass << " allowedExclusive;\n";
+  OS << "  const " << ClauseEnumSetClass << " requiredOneOf;\n";
+  OS << "};\n";
+
+  OS << "\n";
+
+  OS << "std::unordered_map<llvm::" << CppNamespace << "::Directive, "
+     << LanguageName << "DirectiveClauses>\n";
+  OS << "    directiveClausesTable = {\n";
+
+  for (const auto &D : Directives) {
+    const auto FormattedDirectiveName =
+        getFormattedName(D->getValueAsString("name"));
+    OS << "  {llvm::" << CppNamespace << "::Directive::" << DirectivePrefix
+       << FormattedDirectiveName << ",\n";
+    OS << "    {\n";
+    OS << "      llvm::" << CppNamespace << "::allowedClauses_"
+       << DirectivePrefix << FormattedDirectiveName << ",\n";
+    OS << "      llvm::" << CppNamespace << "::allowedOnceClauses_"
+       << DirectivePrefix << FormattedDirectiveName << ",\n";
+    OS << "      llvm::" << CppNamespace << "::allowedExclusiveClauses_"
+       << DirectivePrefix << FormattedDirectiveName << ",\n";
+    OS << "      llvm::" << CppNamespace << "::requiredClauses_"
+       << DirectivePrefix << FormattedDirectiveName << ",\n";
+    OS << "    }\n";
+    OS << "  },\n";
+  }
+
+  OS << "};\n";
+}
+
 // Generate the implemenation section for the enumeration in the directive
 // language
-void EmitDirectivesImpl(RecordKeeper &Records, raw_ostream &OS) {
+void EmitDirectivesFlangImpl(const std::vector<Record *> &Directives,
+                             raw_ostream &OS, StringRef LanguageName,
+                             StringRef ClauseEnumSetClass,
+                             StringRef DirectivePrefix, StringRef ClausePrefix,
+                             StringRef CppNamespace) {
+
+  GenerateDirectiveClauseSets(Directives, OS, LanguageName, ClauseEnumSetClass,
+                              DirectivePrefix, ClausePrefix, CppNamespace);
+
+  GenerateDirectiveClauseMap(Directives, OS, LanguageName, ClauseEnumSetClass,
+                             DirectivePrefix, ClausePrefix, CppNamespace);
+}
+
+// Generate the implemenation section for the enumeration in the directive
+// language.
+void EmitDirectivesGen(RecordKeeper &Records, raw_ostream &OS) {
 
   const auto &DirectiveLanguages =
       Records.getAllDerivedDefinitions("DirectiveLanguage");
@@ -289,12 +454,40 @@
   StringRef LanguageName = DirectiveLanguage->getValueAsString("name");
   StringRef ClausePrefix = DirectiveLanguage->getValueAsString("clausePrefix");
   StringRef CppNamespace = DirectiveLanguage->getValueAsString("cppNamespace");
-  StringRef IncludeHeader =
-      DirectiveLanguage->getValueAsString("includeHeader");
+  StringRef ClauseEnumSetClass =
+      DirectiveLanguage->getValueAsString("clauseEnumSetClass");
 
   const auto &Directives = Records.getAllDerivedDefinitions("Directive");
   const auto &Clauses = Records.getAllDerivedDefinitions("Clause");
 
+  EmitDirectivesFlangImpl(Directives, OS, LanguageName, ClauseEnumSetClass,
+                          DirectivePrefix, ClausePrefix, CppNamespace);
+}
+
+// Generate the implemenation for the enumeration in the directive
+// language. This code can be included in library.
+void EmitDirectivesImpl(RecordKeeper &Records, raw_ostream &OS) {
+
+  const auto &DirectiveLanguages =
+      Records.getAllDerivedDefinitions("DirectiveLanguage");
+
+  if (DirectiveLanguages.size() != 1) {
+    PrintError("A single definition of DirectiveLanguage is needed.");
+    return;
+  }
+
+  const auto &DirectiveLanguage = DirectiveLanguages[0];
+  StringRef DirectivePrefix =
+      DirectiveLanguage->getValueAsString("directivePrefix");
+  StringRef LanguageName = DirectiveLanguage->getValueAsString("name");
+  StringRef ClausePrefix = DirectiveLanguage->getValueAsString("clausePrefix");
+  StringRef CppNamespace = DirectiveLanguage->getValueAsString("cppNamespace");
+  const auto &Directives = Records.getAllDerivedDefinitions("Directive");
+  const auto &Clauses = Records.getAllDerivedDefinitions("Clause");
+
+  StringRef IncludeHeader =
+      DirectiveLanguage->getValueAsString("includeHeader");
+
   if (!IncludeHeader.empty())
     OS << "#include \"" << IncludeHeader << "\"\n\n";
 
@@ -323,6 +516,7 @@
   GenerateGetName(Clauses, OS, "Clause", ClausePrefix, LanguageName,
                   CppNamespace);
 
+  // isAllowedClauseForDirective(Directive D, Clause C, unsigned Version)
   GenerateIsAllowedClause(Directives, OS, LanguageName, DirectivePrefix,
                           ClausePrefix, CppNamespace);
 }
diff --git a/llvm/utils/TableGen/TableGen.cpp b/llvm/utils/TableGen/TableGen.cpp
--- a/llvm/utils/TableGen/TableGen.cpp
+++ b/llvm/utils/TableGen/TableGen.cpp
@@ -56,6 +56,7 @@
   GenAutomata,
   GenDirectivesEnumDecl,
   GenDirectivesEnumImpl,
+  GenDirectivesEnumGen,
 };
 
 namespace llvm {
@@ -132,9 +133,11 @@
                    "Generate llvm-exegesis tables"),
         clEnumValN(GenAutomata, "gen-automata", "Generate generic automata"),
         clEnumValN(GenDirectivesEnumDecl, "gen-directive-decl",
-                   "Generate directive related declaration code"),
+                   "Generate directive related declaration code (header file)"),
         clEnumValN(GenDirectivesEnumImpl, "gen-directive-impl",
-                   "Generate directive related implementation code")));
+                   "Generate directive related implementation code"),
+        clEnumValN(GenDirectivesEnumGen, "gen-directive-gen",
+                   "Generate directive related implementation code part")));
 
 cl::OptionCategory PrintEnumsCat("Options for -print-enums");
 cl::opt<std::string> Class("class", cl::desc("Print Enum list for this class"),
@@ -265,6 +268,9 @@
   case GenDirectivesEnumImpl:
     EmitDirectivesImpl(Records, OS);
     break;
+  case GenDirectivesEnumGen:
+    EmitDirectivesGen(Records, OS);
+    break;
   }
 
   return false;
diff --git a/llvm/utils/TableGen/TableGenBackends.h b/llvm/utils/TableGen/TableGenBackends.h
--- a/llvm/utils/TableGen/TableGenBackends.h
+++ b/llvm/utils/TableGen/TableGenBackends.h
@@ -92,6 +92,7 @@
 void EmitAutomata(RecordKeeper &RK, raw_ostream &OS);
 void EmitDirectivesDecl(RecordKeeper &RK, raw_ostream &OS);
 void EmitDirectivesImpl(RecordKeeper &RK, raw_ostream &OS);
+void EmitDirectivesGen(RecordKeeper &RK, raw_ostream &OS);
 
 } // End llvm namespace