1 //===-- lib/Semantics/check-omp-structure.cpp -----------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "check-omp-structure.h"
10 #include "flang/Parser/parse-tree.h"
11 #include "flang/Semantics/tools.h"
12 
13 namespace Fortran::semantics {
14 
15 // Use when clause falls under 'struct OmpClause' in 'parse-tree.h'.
16 #define CHECK_SIMPLE_CLAUSE(X, Y) \
17   void OmpStructureChecker::Enter(const parser::OmpClause::X &) { \
18     CheckAllowed(llvm::omp::Clause::Y); \
19   }
20 
21 #define CHECK_REQ_CONSTANT_SCALAR_INT_CLAUSE(X, Y) \
22   void OmpStructureChecker::Enter(const parser::OmpClause::X &c) { \
23     CheckAllowed(llvm::omp::Clause::Y); \
24     RequiresConstantPositiveParameter(llvm::omp::Clause::Y, c.v); \
25   }
26 
27 #define CHECK_REQ_SCALAR_INT_CLAUSE(X, Y) \
28   void OmpStructureChecker::Enter(const parser::OmpClause::X &c) { \
29     CheckAllowed(llvm::omp::Clause::Y); \
30     RequiresPositiveParameter(llvm::omp::Clause::Y, c.v); \
31   }
32 
33 // Use when clause don't falls under 'struct OmpClause' in 'parse-tree.h'.
34 #define CHECK_SIMPLE_PARSER_CLAUSE(X, Y) \
35   void OmpStructureChecker::Enter(const parser::X &) { \
36     CheckAllowed(llvm::omp::Y); \
37   }
38 
39 bool OmpStructureChecker::HasInvalidWorksharingNesting(
40     const parser::CharBlock &source, const OmpDirectiveSet &set) {
41   // set contains all the invalid closely nested directives
42   // for the given directive (`source` here)
43   if (CurrentDirectiveIsNested() && set.test(GetContext().directive)) {
44     context_.Say(source,
45         "A worksharing region may not be closely nested inside a "
46         "worksharing, explicit task, taskloop, critical, ordered, atomic, or "
47         "master region"_err_en_US);
48     return true;
49   }
50   return false;
51 }
52 
53 void OmpStructureChecker::Enter(const parser::OpenMPConstruct &) {
54   // 2.8.1 TODO: Simd Construct with Ordered Construct Nesting check
55 }
56 
57 void OmpStructureChecker::Enter(const parser::OpenMPLoopConstruct &x) {
58   const auto &beginLoopDir{std::get<parser::OmpBeginLoopDirective>(x.t)};
59   const auto &beginDir{std::get<parser::OmpLoopDirective>(beginLoopDir.t)};
60 
61   // check matching, End directive is optional
62   if (const auto &endLoopDir{
63           std::get<std::optional<parser::OmpEndLoopDirective>>(x.t)}) {
64     const auto &endDir{
65         std::get<parser::OmpLoopDirective>(endLoopDir.value().t)};
66 
67     CheckMatching<parser::OmpLoopDirective>(beginDir, endDir);
68   }
69 
70   if (beginDir.v != llvm::omp::Directive::OMPD_do) {
71     PushContextAndClauseSets(beginDir.source, beginDir.v);
72   } else {
73     // 2.7.1 do-clause -> private-clause |
74     //                    firstprivate-clause |
75     //                    lastprivate-clause |
76     //                    linear-clause |
77     //                    reduction-clause |
78     //                    schedule-clause |
79     //                    collapse-clause |
80     //                    ordered-clause
81 
82     // nesting check
83     HasInvalidWorksharingNesting(beginDir.source,
84         {llvm::omp::Directive::OMPD_do, llvm::omp::Directive::OMPD_sections,
85             llvm::omp::Directive::OMPD_single,
86             llvm::omp::Directive::OMPD_workshare,
87             llvm::omp::Directive::OMPD_task,
88             llvm::omp::Directive::OMPD_taskloop,
89             llvm::omp::Directive::OMPD_critical,
90             llvm::omp::Directive::OMPD_ordered,
91             llvm::omp::Directive::OMPD_atomic,
92             llvm::omp::Directive::OMPD_master});
93     PushContextAndClauseSets(beginDir.source, llvm::omp::Directive::OMPD_do);
94   }
95 }
96 
97 void OmpStructureChecker::Leave(const parser::OpenMPLoopConstruct &) {
98   dirContext_.pop_back();
99 }
100 
101 void OmpStructureChecker::Enter(const parser::OmpEndLoopDirective &x) {
102   const auto &dir{std::get<parser::OmpLoopDirective>(x.t)};
103   ResetPartialContext(dir.source);
104   switch (dir.v) {
105   // 2.7.1 end-do -> END DO [nowait-clause]
106   // 2.8.3 end-do-simd -> END DO SIMD [nowait-clause]
107   case llvm::omp::Directive::OMPD_do:
108   case llvm::omp::Directive::OMPD_do_simd:
109     SetClauseSets(dir.v);
110     break;
111   default:
112     // no clauses are allowed
113     break;
114   }
115 }
116 
117 void OmpStructureChecker::Enter(const parser::OpenMPBlockConstruct &x) {
118   const auto &beginBlockDir{std::get<parser::OmpBeginBlockDirective>(x.t)};
119   const auto &endBlockDir{std::get<parser::OmpEndBlockDirective>(x.t)};
120   const auto &beginDir{std::get<parser::OmpBlockDirective>(beginBlockDir.t)};
121   const auto &endDir{std::get<parser::OmpBlockDirective>(endBlockDir.t)};
122   const parser::Block &block{std::get<parser::Block>(x.t)};
123 
124   CheckMatching<parser::OmpBlockDirective>(beginDir, endDir);
125 
126   PushContextAndClauseSets(beginDir.source, beginDir.v);
127 
128   switch (beginDir.v) {
129   case llvm::omp::OMPD_parallel:
130     CheckNoBranching(block, llvm::omp::OMPD_parallel, beginDir.source);
131     break;
132   default:
133     break;
134   }
135 }
136 
137 void OmpStructureChecker::Leave(const parser::OpenMPBlockConstruct &) {
138   dirContext_.pop_back();
139 }
140 
141 void OmpStructureChecker::Enter(const parser::OpenMPSectionsConstruct &x) {
142   const auto &beginSectionsDir{
143       std::get<parser::OmpBeginSectionsDirective>(x.t)};
144   const auto &endSectionsDir{std::get<parser::OmpEndSectionsDirective>(x.t)};
145   const auto &beginDir{
146       std::get<parser::OmpSectionsDirective>(beginSectionsDir.t)};
147   const auto &endDir{std::get<parser::OmpSectionsDirective>(endSectionsDir.t)};
148   CheckMatching<parser::OmpSectionsDirective>(beginDir, endDir);
149 
150   PushContextAndClauseSets(beginDir.source, beginDir.v);
151 }
152 
153 void OmpStructureChecker::Leave(const parser::OpenMPSectionsConstruct &) {
154   dirContext_.pop_back();
155 }
156 
157 void OmpStructureChecker::Enter(const parser::OmpEndSectionsDirective &x) {
158   const auto &dir{std::get<parser::OmpSectionsDirective>(x.t)};
159   ResetPartialContext(dir.source);
160   switch (dir.v) {
161     // 2.7.2 end-sections -> END SECTIONS [nowait-clause]
162   case llvm::omp::Directive::OMPD_sections:
163     SetContextDirectiveEnum(llvm::omp::Directive::OMPD_end_sections);
164     SetContextAllowedOnce(OmpClauseSet{llvm::omp::Clause::OMPC_nowait});
165     break;
166   default:
167     // no clauses are allowed
168     break;
169   }
170 }
171 
172 void OmpStructureChecker::Enter(const parser::OpenMPDeclareSimdConstruct &x) {
173   const auto &dir{std::get<parser::Verbatim>(x.t)};
174   PushContextAndClauseSets(dir.source, llvm::omp::Directive::OMPD_declare_simd);
175 }
176 
177 void OmpStructureChecker::Leave(const parser::OpenMPDeclareSimdConstruct &) {
178   dirContext_.pop_back();
179 }
180 
181 void OmpStructureChecker::Enter(const parser::OpenMPDeclareTargetConstruct &x) {
182   const auto &dir{std::get<parser::Verbatim>(x.t)};
183   PushContext(dir.source, llvm::omp::Directive::OMPD_declare_target);
184   const auto &spec{std::get<parser::OmpDeclareTargetSpecifier>(x.t)};
185   if (std::holds_alternative<parser::OmpDeclareTargetWithClause>(spec.u)) {
186     SetContextAllowed(
187         OmpClauseSet{llvm::omp::Clause::OMPC_to, llvm::omp::Clause::OMPC_link});
188   }
189 }
190 
191 void OmpStructureChecker::Leave(const parser::OpenMPDeclareTargetConstruct &) {
192   dirContext_.pop_back();
193 }
194 
195 void OmpStructureChecker::Enter(
196     const parser::OpenMPSimpleStandaloneConstruct &x) {
197   const auto &dir{std::get<parser::OmpSimpleStandaloneDirective>(x.t)};
198   PushContextAndClauseSets(dir.source, dir.v);
199 }
200 
201 void OmpStructureChecker::Leave(
202     const parser::OpenMPSimpleStandaloneConstruct &) {
203   dirContext_.pop_back();
204 }
205 
206 void OmpStructureChecker::Enter(const parser::OpenMPFlushConstruct &x) {
207   const auto &dir{std::get<parser::Verbatim>(x.t)};
208   PushContextAndClauseSets(dir.source, llvm::omp::Directive::OMPD_flush);
209 }
210 
211 void OmpStructureChecker::Leave(const parser::OpenMPFlushConstruct &) {
212   dirContext_.pop_back();
213 }
214 
215 void OmpStructureChecker::Enter(const parser::OpenMPCancelConstruct &x) {
216   const auto &dir{std::get<parser::Verbatim>(x.t)};
217   PushContextAndClauseSets(dir.source, llvm::omp::Directive::OMPD_cancel);
218 }
219 
220 void OmpStructureChecker::Leave(const parser::OpenMPCancelConstruct &) {
221   dirContext_.pop_back();
222 }
223 
224 void OmpStructureChecker::Enter(const parser::OpenMPCriticalConstruct &x) {
225   const auto &dir{std::get<parser::OmpCriticalDirective>(x.t)};
226   PushContextAndClauseSets(dir.source, llvm::omp::Directive::OMPD_critical);
227 }
228 
229 void OmpStructureChecker::Leave(const parser::OpenMPCriticalConstruct &) {
230   dirContext_.pop_back();
231 }
232 
233 void OmpStructureChecker::Enter(
234     const parser::OpenMPCancellationPointConstruct &x) {
235   const auto &dir{std::get<parser::Verbatim>(x.t)};
236   PushContextAndClauseSets(
237       dir.source, llvm::omp::Directive::OMPD_cancellation_point);
238 }
239 
240 void OmpStructureChecker::Leave(
241     const parser::OpenMPCancellationPointConstruct &) {
242   dirContext_.pop_back();
243 }
244 
245 void OmpStructureChecker::Enter(const parser::OmpEndBlockDirective &x) {
246   const auto &dir{std::get<parser::OmpBlockDirective>(x.t)};
247   ResetPartialContext(dir.source);
248   switch (dir.v) {
249   // 2.7.3 end-single-clause -> copyprivate-clause |
250   //                            nowait-clause
251   case llvm::omp::Directive::OMPD_single: {
252     SetContextDirectiveEnum(llvm::omp::Directive::OMPD_end_single);
253     OmpClauseSet allowed{llvm::omp::Clause::OMPC_copyprivate};
254     SetContextAllowed(allowed);
255     OmpClauseSet allowedOnce{llvm::omp::Clause::OMPC_nowait};
256     SetContextAllowedOnce(allowedOnce);
257   } break;
258   // 2.7.4 end-workshare -> END WORKSHARE [nowait-clause]
259   case llvm::omp::Directive::OMPD_workshare:
260     SetContextDirectiveEnum(llvm::omp::Directive::OMPD_end_workshare);
261     SetContextAllowed(OmpClauseSet{llvm::omp::Clause::OMPC_nowait});
262     break;
263   default:
264     // no clauses are allowed
265     break;
266   }
267 }
268 
269 // Clauses
270 // Mainly categorized as
271 // 1. Checks on 'OmpClauseList' from 'parse-tree.h'.
272 // 2. Checks on clauses which fall under 'struct OmpClause' from parse-tree.h.
273 // 3. Checks on clauses which are not in 'struct OmpClause' from parse-tree.h.
274 
275 void OmpStructureChecker::Leave(const parser::OmpClauseList &) {
276   // 2.7 Loop Construct Restriction
277   if (llvm::omp::doSet.test(GetContext().directive)) {
278     if (auto *clause{FindClause(llvm::omp::Clause::OMPC_schedule)}) {
279       // only one schedule clause is allowed
280       const auto &schedClause{std::get<parser::OmpScheduleClause>(clause->u)};
281       if (ScheduleModifierHasType(schedClause,
282               parser::OmpScheduleModifierType::ModType::Nonmonotonic)) {
283         if (FindClause(llvm::omp::Clause::OMPC_ordered)) {
284           context_.Say(clause->source,
285               "The NONMONOTONIC modifier cannot be specified "
286               "if an ORDERED clause is specified"_err_en_US);
287         }
288         if (ScheduleModifierHasType(schedClause,
289                 parser::OmpScheduleModifierType::ModType::Monotonic)) {
290           context_.Say(clause->source,
291               "The MONOTONIC and NONMONOTONIC modifiers "
292               "cannot be both specified"_err_en_US);
293         }
294       }
295     }
296 
297     if (auto *clause{FindClause(llvm::omp::Clause::OMPC_ordered)}) {
298       // only one ordered clause is allowed
299       const auto &orderedClause{
300           std::get<parser::OmpClause::Ordered>(clause->u)};
301 
302       if (orderedClause.v) {
303         if (FindClause(llvm::omp::Clause::OMPC_linear)) {
304           context_.Say(clause->source,
305               "A loop directive may not have both a LINEAR clause and "
306               "an ORDERED clause with a parameter"_err_en_US);
307         }
308 
309         if (auto *clause2{FindClause(llvm::omp::Clause::OMPC_collapse)}) {
310           const auto &collapseClause{
311               std::get<parser::OmpClause::Collapse>(clause2->u)};
312           // ordered and collapse both have parameters
313           if (const auto orderedValue{GetIntValue(orderedClause.v)}) {
314             if (const auto collapseValue{GetIntValue(collapseClause.v)}) {
315               if (*orderedValue > 0 && *orderedValue < *collapseValue) {
316                 context_.Say(clause->source,
317                     "The parameter of the ORDERED clause must be "
318                     "greater than or equal to "
319                     "the parameter of the COLLAPSE clause"_err_en_US);
320               }
321             }
322           }
323         }
324       }
325 
326       // TODO: ordered region binding check (requires nesting implementation)
327     }
328   } // doSet
329 
330   // 2.8.1 Simd Construct Restriction
331   if (llvm::omp::simdSet.test(GetContext().directive)) {
332     if (auto *clause{FindClause(llvm::omp::Clause::OMPC_simdlen)}) {
333       if (auto *clause2{FindClause(llvm::omp::Clause::OMPC_safelen)}) {
334         const auto &simdlenClause{
335             std::get<parser::OmpClause::Simdlen>(clause->u)};
336         const auto &safelenClause{
337             std::get<parser::OmpClause::Safelen>(clause2->u)};
338         // simdlen and safelen both have parameters
339         if (const auto simdlenValue{GetIntValue(simdlenClause.v)}) {
340           if (const auto safelenValue{GetIntValue(safelenClause.v)}) {
341             if (*safelenValue > 0 && *simdlenValue > *safelenValue) {
342               context_.Say(clause->source,
343                   "The parameter of the SIMDLEN clause must be less than or "
344                   "equal to the parameter of the SAFELEN clause"_err_en_US);
345             }
346           }
347         }
348       }
349     }
350 
351     // TODO: A list-item cannot appear in more than one aligned clause
352   } // SIMD
353 
354   // 2.7.3 Single Construct Restriction
355   if (GetContext().directive == llvm::omp::Directive::OMPD_end_single) {
356     if (auto *clause{FindClause(llvm::omp::Clause::OMPC_copyprivate)}) {
357       if (FindClause(llvm::omp::Clause::OMPC_nowait)) {
358         context_.Say(clause->source,
359             "The COPYPRIVATE clause must not be used with "
360             "the NOWAIT clause"_err_en_US);
361       }
362     }
363   }
364 
365   GetContext().requiredClauses.IterateOverMembers(
366       [this](llvm::omp::Clause c) { CheckRequired(c); });
367 }
368 
369 void OmpStructureChecker::Enter(const parser::OmpClause &x) {
370   SetContextClause(x);
371 }
372 
373 // Following clauses do not have a seperate node in parse-tree.h.
374 // They fall under 'struct OmpClause' in parse-tree.h.
375 CHECK_SIMPLE_CLAUSE(Copyin, OMPC_copyin)
376 CHECK_SIMPLE_CLAUSE(Copyprivate, OMPC_copyprivate)
377 CHECK_SIMPLE_CLAUSE(Device, OMPC_device)
378 CHECK_SIMPLE_CLAUSE(Final, OMPC_final)
379 CHECK_SIMPLE_CLAUSE(Firstprivate, OMPC_firstprivate)
380 CHECK_SIMPLE_CLAUSE(From, OMPC_from)
381 CHECK_SIMPLE_CLAUSE(Inbranch, OMPC_inbranch)
382 CHECK_SIMPLE_CLAUSE(IsDevicePtr, OMPC_is_device_ptr)
383 CHECK_SIMPLE_CLAUSE(Lastprivate, OMPC_lastprivate)
384 CHECK_SIMPLE_CLAUSE(Link, OMPC_link)
385 CHECK_SIMPLE_CLAUSE(Mergeable, OMPC_mergeable)
386 CHECK_SIMPLE_CLAUSE(Nogroup, OMPC_nogroup)
387 CHECK_SIMPLE_CLAUSE(Notinbranch, OMPC_notinbranch)
388 CHECK_SIMPLE_CLAUSE(Private, OMPC_private)
389 CHECK_SIMPLE_CLAUSE(Shared, OMPC_shared)
390 CHECK_SIMPLE_CLAUSE(To, OMPC_to)
391 CHECK_SIMPLE_CLAUSE(Uniform, OMPC_uniform)
392 CHECK_SIMPLE_CLAUSE(Untied, OMPC_untied)
393 CHECK_SIMPLE_CLAUSE(UseDevicePtr, OMPC_use_device_ptr)
394 
395 CHECK_REQ_SCALAR_INT_CLAUSE(Grainsize, OMPC_grainsize)
396 CHECK_REQ_SCALAR_INT_CLAUSE(NumTasks, OMPC_num_tasks)
397 CHECK_REQ_SCALAR_INT_CLAUSE(NumTeams, OMPC_num_teams)
398 CHECK_REQ_SCALAR_INT_CLAUSE(NumThreads, OMPC_num_threads)
399 CHECK_REQ_SCALAR_INT_CLAUSE(Priority, OMPC_priority)
400 CHECK_REQ_SCALAR_INT_CLAUSE(ThreadLimit, OMPC_thread_limit)
401 
402 CHECK_REQ_CONSTANT_SCALAR_INT_CLAUSE(Collapse, OMPC_collapse)
403 CHECK_REQ_CONSTANT_SCALAR_INT_CLAUSE(Safelen, OMPC_safelen)
404 CHECK_REQ_CONSTANT_SCALAR_INT_CLAUSE(Simdlen, OMPC_simdlen)
405 
406 // Restrictions specific to each clause are implemented apart from the
407 // generalized restrictions.
408 void OmpStructureChecker::Enter(const parser::OmpClause::Ordered &x) {
409   CheckAllowed(llvm::omp::Clause::OMPC_ordered);
410   // the parameter of ordered clause is optional
411   if (const auto &expr{x.v}) {
412     RequiresConstantPositiveParameter(llvm::omp::Clause::OMPC_ordered, *expr);
413 
414     // 2.8.3 Loop SIMD Construct Restriction
415     if (llvm::omp::doSimdSet.test(GetContext().directive)) {
416       context_.Say(GetContext().clauseSource,
417           "No ORDERED clause with a parameter can be specified "
418           "on the %s directive"_err_en_US,
419           ContextDirectiveAsFortran());
420     }
421   }
422 }
423 
424 // Following clauses have a seperate node in parse-tree.h.
425 CHECK_SIMPLE_PARSER_CLAUSE(OmpAllocateClause, OMPC_allocate)
426 CHECK_SIMPLE_PARSER_CLAUSE(OmpDefaultClause, OMPC_default)
427 CHECK_SIMPLE_PARSER_CLAUSE(OmpDependClause, OMPC_depend)
428 CHECK_SIMPLE_PARSER_CLAUSE(OmpDistScheduleClause, OMPC_dist_schedule)
429 CHECK_SIMPLE_PARSER_CLAUSE(OmpNowait, OMPC_nowait)
430 CHECK_SIMPLE_PARSER_CLAUSE(OmpProcBindClause, OMPC_proc_bind)
431 CHECK_SIMPLE_PARSER_CLAUSE(OmpReductionClause, OMPC_reduction)
432 
433 // Restrictions specific to each clause are implemented apart from the
434 // generalized restrictions.
435 void OmpStructureChecker::Enter(const parser::OmpAlignedClause &x) {
436   CheckAllowed(llvm::omp::Clause::OMPC_aligned);
437 
438   if (const auto &expr{
439           std::get<std::optional<parser::ScalarIntConstantExpr>>(x.t)}) {
440     if (const auto v{GetIntValue(*expr)}) {
441       if (*v <= 0) {
442         context_.Say(GetContext().clauseSource,
443             "The ALIGNMENT parameter of the ALIGNED clause must be "
444             "a constant positive integer expression"_err_en_US);
445       }
446     }
447   }
448   // 2.8.1 TODO: list-item attribute check
449 }
450 void OmpStructureChecker::Enter(const parser::OmpDefaultmapClause &x) {
451   CheckAllowed(llvm::omp::Clause::OMPC_defaultmap);
452   using VariableCategory = parser::OmpDefaultmapClause::VariableCategory;
453   if (!std::get<std::optional<VariableCategory>>(x.t)) {
454     context_.Say(GetContext().clauseSource,
455         "The argument TOFROM:SCALAR must be specified on the DEFAULTMAP "
456         "clause"_err_en_US);
457   }
458 }
459 void OmpStructureChecker::Enter(const parser::OmpIfClause &x) {
460   CheckAllowed(llvm::omp::Clause::OMPC_if);
461 
462   using dirNameModifier = parser::OmpIfClause::DirectiveNameModifier;
463   static std::unordered_map<dirNameModifier, OmpDirectiveSet>
464       dirNameModifierMap{{dirNameModifier::Parallel, llvm::omp::parallelSet},
465           {dirNameModifier::Target, llvm::omp::targetSet},
466           {dirNameModifier::TargetEnterData,
467               {llvm::omp::Directive::OMPD_target_enter_data}},
468           {dirNameModifier::TargetExitData,
469               {llvm::omp::Directive::OMPD_target_exit_data}},
470           {dirNameModifier::TargetData,
471               {llvm::omp::Directive::OMPD_target_data}},
472           {dirNameModifier::TargetUpdate,
473               {llvm::omp::Directive::OMPD_target_update}},
474           {dirNameModifier::Task, {llvm::omp::Directive::OMPD_task}},
475           {dirNameModifier::Taskloop, llvm::omp::taskloopSet}};
476   if (const auto &directiveName{
477           std::get<std::optional<dirNameModifier>>(x.t)}) {
478     auto search{dirNameModifierMap.find(*directiveName)};
479     if (search == dirNameModifierMap.end() ||
480         !search->second.test(GetContext().directive)) {
481       context_
482           .Say(GetContext().clauseSource,
483               "Unmatched directive name modifier %s on the IF clause"_err_en_US,
484               parser::ToUpperCaseLetters(
485                   parser::OmpIfClause::EnumToString(*directiveName)))
486           .Attach(
487               GetContext().directiveSource, "Cannot apply to directive"_en_US);
488     }
489   }
490 }
491 
492 void OmpStructureChecker::Enter(const parser::OmpLinearClause &x) {
493   CheckAllowed(llvm::omp::Clause::OMPC_linear);
494 
495   // 2.7 Loop Construct Restriction
496   if ((llvm::omp::doSet | llvm::omp::simdSet).test(GetContext().directive)) {
497     if (std::holds_alternative<parser::OmpLinearClause::WithModifier>(x.u)) {
498       context_.Say(GetContext().clauseSource,
499           "A modifier may not be specified in a LINEAR clause "
500           "on the %s directive"_err_en_US,
501           ContextDirectiveAsFortran());
502     }
503   }
504 }
505 void OmpStructureChecker::Enter(const parser::OmpMapClause &x) {
506   CheckAllowed(llvm::omp::Clause::OMPC_map);
507   if (const auto &maptype{std::get<std::optional<parser::OmpMapType>>(x.t)}) {
508     using Type = parser::OmpMapType::Type;
509     const Type &type{std::get<Type>(maptype->t)};
510     switch (GetContext().directive) {
511     case llvm::omp::Directive::OMPD_target:
512     case llvm::omp::Directive::OMPD_target_teams:
513     case llvm::omp::Directive::OMPD_target_teams_distribute:
514     case llvm::omp::Directive::OMPD_target_teams_distribute_simd:
515     case llvm::omp::Directive::OMPD_target_teams_distribute_parallel_do:
516     case llvm::omp::Directive::OMPD_target_teams_distribute_parallel_do_simd:
517     case llvm::omp::Directive::OMPD_target_data: {
518       if (type != Type::To && type != Type::From && type != Type::Tofrom &&
519           type != Type::Alloc) {
520         context_.Say(GetContext().clauseSource,
521             "Only the TO, FROM, TOFROM, or ALLOC map types are permitted "
522             "for MAP clauses on the %s directive"_err_en_US,
523             ContextDirectiveAsFortran());
524       }
525     } break;
526     case llvm::omp::Directive::OMPD_target_enter_data: {
527       if (type != Type::To && type != Type::Alloc) {
528         context_.Say(GetContext().clauseSource,
529             "Only the TO or ALLOC map types are permitted "
530             "for MAP clauses on the %s directive"_err_en_US,
531             ContextDirectiveAsFortran());
532       }
533     } break;
534     case llvm::omp::Directive::OMPD_target_exit_data: {
535       if (type != Type::Delete && type != Type::Release && type != Type::From) {
536         context_.Say(GetContext().clauseSource,
537             "Only the FROM, RELEASE, or DELETE map types are permitted "
538             "for MAP clauses on the %s directive"_err_en_US,
539             ContextDirectiveAsFortran());
540       }
541     } break;
542     default:
543       break;
544     }
545   }
546 }
547 
548 bool OmpStructureChecker::ScheduleModifierHasType(
549     const parser::OmpScheduleClause &x,
550     const parser::OmpScheduleModifierType::ModType &type) {
551   const auto &modifier{
552       std::get<std::optional<parser::OmpScheduleModifier>>(x.t)};
553   if (modifier) {
554     const auto &modType1{
555         std::get<parser::OmpScheduleModifier::Modifier1>(modifier->t)};
556     const auto &modType2{
557         std::get<std::optional<parser::OmpScheduleModifier::Modifier2>>(
558             modifier->t)};
559     if (modType1.v.v == type || (modType2 && modType2->v.v == type)) {
560       return true;
561     }
562   }
563   return false;
564 }
565 void OmpStructureChecker::Enter(const parser::OmpScheduleClause &x) {
566   CheckAllowed(llvm::omp::Clause::OMPC_schedule);
567 
568   // 2.7 Loop Construct Restriction
569   if (llvm::omp::doSet.test(GetContext().directive)) {
570     const auto &kind{std::get<1>(x.t)};
571     const auto &chunk{std::get<2>(x.t)};
572     if (chunk) {
573       if (kind == parser::OmpScheduleClause::ScheduleType::Runtime ||
574           kind == parser::OmpScheduleClause::ScheduleType::Auto) {
575         context_.Say(GetContext().clauseSource,
576             "When SCHEDULE clause has %s specified, "
577             "it must not have chunk size specified"_err_en_US,
578             parser::ToUpperCaseLetters(
579                 parser::OmpScheduleClause::EnumToString(kind)));
580       }
581     }
582 
583     if (ScheduleModifierHasType(
584             x, parser::OmpScheduleModifierType::ModType::Nonmonotonic)) {
585       if (kind != parser::OmpScheduleClause::ScheduleType::Dynamic &&
586           kind != parser::OmpScheduleClause::ScheduleType::Guided) {
587         context_.Say(GetContext().clauseSource,
588             "The NONMONOTONIC modifier can only be specified with "
589             "SCHEDULE(DYNAMIC) or SCHEDULE(GUIDED)"_err_en_US);
590       }
591     }
592   }
593 }
594 
595 llvm::StringRef OmpStructureChecker::getClauseName(llvm::omp::Clause clause) {
596   return llvm::omp::getOpenMPClauseName(clause);
597 }
598 
599 llvm::StringRef OmpStructureChecker::getDirectiveName(
600     llvm::omp::Directive directive) {
601   return llvm::omp::getOpenMPDirectiveName(directive);
602 }
603 
604 } // namespace Fortran::semantics
605