[flang][openacc] OpenACC 3.0 parser

[clementval]

Summary

This patch introduce the parser for OpenACC 3.0 in Flang. It uses the same TableGen mechanism
than OpenMP.

[tskeith]

When I try to build this (on macos) I get a missing include for unordered_map:

In file included from ../../flang/lib/Semantics/check-omp-structure.h:159:
include/llvm/Frontend/OpenMP/OMP.cpp.inc:2123:6: error: no template named 'unordered_map' in namespace 'std'
std::unordered_map<llvm::omp::Directive, OpenMPDirectiveClauses>
~~~~~^

Adding the include to check-omp-structure.h fixes the build problem.

[clementval]

In D83649#2147348, @tskeith wrote:

When I try to build this (on macos) I get a missing include for unordered_map:

In file included from ../../flang/lib/Semantics/check-omp-structure.h:159:
include/llvm/Frontend/OpenMP/OMP.cpp.inc:2123:6: error: no template named 'unordered_map' in namespace 'std'
std::unordered_map<llvm::omp::Directive, OpenMPDirectiveClauses>
~~~~~^

Adding the include to check-omp-structure.h fixes the build problem.

@DavidTruby has seen similar problem here https://reviews.llvm.org/rG6e42a417bacbfd5a1f58b0ccb7c9b34ff9e54523. I'll send a patch today to switch to DenseMap so this should go away with it.

[DavidTruby]

I've already committed a quick fix just moving the header, so builds should work again now.

[klausler]

This looks spectacular to me (at least the f18 parts that I reviewed). Thank you so much for taking on this task and contributing so much value to the project.

flang/include/flang/Parser/parse-tree.h

3853

Minor: eqv and neqv are missing their second periods.

flang/lib/Parser/openacc-parsers.cpp

26

Doesn't OpenMP use something similar? Put it into token-parsers.h and share it, if so.

36

Extra space at end of line, and not in alphabetic order.

88

Where synonyms like this appear, it would probably be more clear to use something like ("DEVICE_TYPE"_tok || "DTYPE"_tok) >> ...) to combine the recognition of the synonymous keywords and have just the one following parser.

155

We use C++-style comments with //, please.

[clementval]

Address review comment

[clementval]

In D83649#2147634, @klausler wrote:

This looks spectacular to me (at least the f18 parts that I reviewed). Thank you so much for taking on this task and contributing so much value to the project.

Thanks for the review. I just updated the patch with fixes to your comments.

[MaskRay]

Hi, your git commit contains extra Phabricator tags. You can drop Reviewers: Subscribers: Tags: and the text Summary: from the git commit with the following script:

arcfilter () {
        arc amend
        git log -1 --pretty=%B | awk '/Reviewers:|Subscribers:/{p=1} /Reviewed By:|Differential Revision:/{p=0} !p && !/^Summary:$/ {sub(/^Summary: /,"");print}' | git commit --amend --date=now -F -
}

Reviewed By: is considered important by some people. Please keep the tag. (--date=now is my personal preference (author dates are usually not useful. Using committer dates can make log almost monotonic in time))

llvm/utils/git/pre-push.py can validate the message does not include unneeded tags.

[clementval]

@klausler I had to temporarly revert this patch since it fails for one buildbot. http://lab.llvm.org:8011/builders/clang-ppc64le-rhel/builds/5677

Even after adding Support as a link dependency it still fails. Will investigate tomorrow.

FAILED: lib/libLLVMFrontendOpenACC.so.11git
: && /home/buildbots/clang.10.0.0/bin/clang++ --gcc-toolchain=/opt/rh/devtoolset-7/root/usr -fPIC -fPIC -fvisibility-inlines-hidden -Werror -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wstring-conversion -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -Wl,-z,defs -Wl,-z,nodelete -Wl,-rpath-link,/home/buildbots/docker-RHEL-buildbot/SetupBot/worker_env/ppc64le-clang-rhel-test/clang-ppc64le-rhel/stage1/./lib -Wl,-O3 -Wl,--gc-sections -shared -Wl,-soname,libLLVMFrontendOpenACC.so.11git -o lib/libLLVMFrontendOpenACC.so.11git lib/Frontend/OpenACC/CMakeFiles/LLVMFrontendOpenACC.dir/ACC.cpp.o -Wl,-rpath,"\$ORIGIN/../lib" && :
lib/Frontend/OpenACC/CMakeFiles/LLVMFrontendOpenACC.dir/ACC.cpp.o: In function `llvm::acc::getOpenACCDirectiveName(llvm::acc::Directive)':
ACC.cpp:(.text._ZN4llvm3acc23getOpenACCDirectiveNameENS0_9DirectiveE+0x280): undefined reference to `llvm::llvm_unreachable_internal(char const*, char const*, unsigned int)'
lib/Frontend/OpenACC/CMakeFiles/LLVMFrontendOpenACC.dir/ACC.cpp.o: In function `llvm::acc::getOpenACCClauseName(llvm::acc::Clause)':
ACC.cpp:(.text._ZN4llvm3acc20getOpenACCClauseNameENS0_6ClauseE+0x4a4): undefined reference to `llvm::llvm_unreachable_internal(char const*, char const*, unsigned int)'
lib/Frontend/OpenACC/CMakeFiles/LLVMFrontendOpenACC.dir/ACC.cpp.o: In function `llvm::acc::isAllowedClauseForDirective(llvm::acc::Directive, llvm::acc::Clause, unsigned int)':
ACC.cpp:(.text._ZN4llvm3acc27isAllowedClauseForDirectiveENS0_9DirectiveENS0_6ClauseEj+0x344): undefined reference to `llvm::llvm_unreachable_internal(char const*, char const*, unsigned int)'

[clementval]

Had to revert because of a failed buildbot. http://lab.llvm.org:8011/builders/clang-ppc64le-rhel/builds/5673

FAILED: lib/libLLVMFrontendOpenACC.so.11git 
: && /home/buildbots/clang.10.0.0/bin/clang++ --gcc-toolchain=/opt/rh/devtoolset-7/root/usr -fPIC -fPIC -fvisibility-inlines-hidden -Werror -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wstring-conversion -fdiagnostics-color -ffunction-sections -fdata-sections -O3  -Wl,-z,defs -Wl,-z,nodelete   -Wl,-rpath-link,/home/buildbots/docker-RHEL-buildbot/SetupBot/worker_env/ppc64le-clang-rhel-test/clang-ppc64le-rhel/stage1/./lib  -Wl,-O3 -Wl,--gc-sections -shared -Wl,-soname,libLLVMFrontendOpenACC.so.11git -o lib/libLLVMFrontendOpenACC.so.11git lib/Frontend/OpenACC/CMakeFiles/LLVMFrontendOpenACC.dir/ACC.cpp.o  -Wl,-rpath,"\$ORIGIN/../lib" && :
lib/Frontend/OpenACC/CMakeFiles/LLVMFrontendOpenACC.dir/ACC.cpp.o: In function `llvm::acc::getOpenACCDirectiveName(llvm::acc::Directive)':
ACC.cpp:(.text._ZN4llvm3acc23getOpenACCDirectiveNameENS0_9DirectiveE+0x280): undefined reference to `llvm::llvm_unreachable_internal(char const*, char const*, unsigned int)'
lib/Frontend/OpenACC/CMakeFiles/LLVMFrontendOpenACC.dir/ACC.cpp.o: In function `llvm::acc::getOpenACCClauseName(llvm::acc::Clause)':
ACC.cpp:(.text._ZN4llvm3acc20getOpenACCClauseNameENS0_6ClauseE+0x4a4): undefined reference to `llvm::llvm_unreachable_internal(char const*, char const*, unsigned int)'
lib/Frontend/OpenACC/CMakeFiles/LLVMFrontendOpenACC.dir/ACC.cpp.o: In function `llvm::acc::isAllowedClauseForDirective(llvm::acc::Directive, llvm::acc::Clause, unsigned int)':
ACC.cpp:(.text._ZN4llvm3acc27isAllowedClauseForDirectiveENS0_9DirectiveENS0_6ClauseEj+0x344): undefined reference to `llvm::llvm_unreachable_internal(char const*, char const*, unsigned int)'
clang-10: error: linker command failed with exit code 1 (use -v to see invocation)

[clementval]

Fix after build failure on clang-ppc64le-rhel

flang/include/flang/Common/Fortran-features.h

ENUM_CLASS(LanguageFeature, BackslashEscapes, OldDebugLines,
     FixedFormContinuationWithColumn1Ampersand, LogicalAbbreviations,
     XOROperator, PunctuationInNames, OptionalFreeFormSpace, BOZExtensions,
     EmptyStatement, AlternativeNE, ExecutionPartNamelist, DECStructures,
     DoubleComplex, Byte, StarKind, QuadPrecision, SlashInitialization,
     TripletInArrayConstructor, MissingColons, SignedComplexLiteral,
     OldStyleParameter, ComplexConstructor, PercentLOC, SignedPrimary, FileName,
     Convert, Dispose, IOListLeadingComma, AbbreviatedEditDescriptor,
     ProgramParentheses, PercentRefAndVal, OmitFunctionDummies, CrayPointer,
-    Hollerith, ArithmeticIF, Assign, AssignedGOTO, Pause, OpenMP,
+    Hollerith, ArithmeticIF, Assign, AssignedGOTO, Pause, OpenACC, OpenMP,
     CruftAfterAmpersand, ClassicCComments, AdditionalFormats, BigIntLiterals,
     RealDoControls, EquivalenceNumericWithCharacter, AdditionalIntrinsics,
     AnonymousParents, OldLabelDoEndStatements, LogicalIntegerAssignment,
     EmptySourceFile, ProgramReturn)
 
 using LanguageFeatures = EnumSet<LanguageFeature, LanguageFeature_enumSize>;
 
 class LanguageFeatureControl {
 public:
   LanguageFeatureControl() {
     // These features must be explicitly enabled by command line options.
     disable_.set(LanguageFeature::OldDebugLines);
+    disable_.set(LanguageFeature::OpenACC);
     disable_.set(LanguageFeature::OpenMP);
     // These features, if enabled, conflict with valid standard usage,
     // so there are disabled here by default.
     disable_.set(LanguageFeature::BackslashEscapes);
     disable_.set(LanguageFeature::LogicalAbbreviations);
     disable_.set(LanguageFeature::XOROperator);
   }
   LanguageFeatureControl(const LanguageFeatureControl &) = default;
   void Enable(LanguageFeature f, bool yes = true) { disable_.set(f, !yes); }
   void EnableWarning(LanguageFeature f, bool yes = true) { warn_.set(f, yes); }
   void WarnOnAllNonstandard(bool yes = true) { warnAll_ = yes; }
   bool IsEnabled(LanguageFeature f) const { return !disable_.test(f); }
   bool ShouldWarn(LanguageFeature f) const {
-    return (warnAll_ && f != LanguageFeature::OpenMP) || warn_.test(f);
+    return (warnAll_ && f != LanguageFeature::OpenMP &&
+               f != LanguageFeature::OpenACC) ||
+        warn_.test(f);
   }
   // Return all spellings of operators names, depending on features enabled
   std::vector<const char *> GetNames(LogicalOperator) const;
   std::vector<const char *> GetNames(RelationalOperator) const;
 
 private:
   LanguageFeatures disable_;
   LanguageFeatures warn_;
   bool warnAll_{false};
 };
 } // namespace Fortran::common
 #endif // FORTRAN_COMMON_FORTRAN_FEATURES_H_

flang/include/flang/Parser/dump-parse-tree.h

#define NODE(T1, T2) NODE_NAME(T1::T2, #T2)
   NODE(format, ControlEditDesc)
   NODE(format::ControlEditDesc, Kind)
   NODE(format, DerivedTypeDataEditDesc)
   NODE(format, FormatItem)
   NODE(format, FormatSpecification)
   NODE(format, IntrinsicTypeDataEditDesc)
   NODE(format::IntrinsicTypeDataEditDesc, Kind)
   NODE(parser, Abstract)
+  NODE(parser, AccAtomicCapture)
+  NODE(AccAtomicCapture, Stmt1)
+  NODE(AccAtomicCapture, Stmt2)
+  NODE(parser, AccAtomicRead)
+  NODE(parser, AccAtomicUpdate)
+  NODE(parser, AccAtomicWrite)
+  NODE(parser, AccBeginBlockDirective)
+  NODE(parser, AccBeginCombinedDirective)
+  NODE(parser, AccBeginLoopDirective)
+  NODE(parser, AccBlockDirective)
+  NODE(parser, AccClause)
+  NODE(AccClause, Auto)
+  NODE(AccClause, Async)
+  NODE(AccClause, Attach)
+  NODE(AccClause, Bind)
+  NODE(AccClause, Capture)
+  NODE(AccClause, Collapse)
+  NODE(AccClause, Copy)
+  NODE(AccClause, Copyin)
+  NODE(AccClause, Copyout)
+  NODE(AccClause, Create)
+  NODE(AccClause, Default)
+  NODE(AccClause, DefaultAsync)
+  NODE(AccClause, Delete)
+  NODE(AccClause, Detach)
+  NODE(AccClause, Device)
+  NODE(AccClause, DeviceNum)
+  NODE(AccClause, DevicePtr)
+  NODE(AccClause, DeviceResident)
+  NODE(AccClause, DeviceType)
+  NODE(AccClause, Finalize)
+  NODE(AccClause, FirstPrivate)
+  NODE(AccClause, Gang)
+  NODE(AccClause, Host)
+  NODE(AccClause, If)
+  NODE(AccClause, IfPresent)
+  NODE(AccClause, Independent)
+  NODE(AccClause, Link)
+  NODE(AccClause, NoCreate)
+  NODE(AccClause, NoHost)
+  NODE(AccClause, NumGangs)
+  NODE(AccClause, NumWorkers)
+  NODE(AccClause, Present)
+  NODE(AccClause, Private)
+  NODE(AccClause, Tile)
+  NODE(AccClause, UseDevice)
+  NODE(AccClause, Read)
+  NODE(AccClause, Reduction)
+  NODE(AccClause, Self)
+  NODE(AccClause, Seq)
+  NODE(AccClause, Vector)
+  NODE(AccClause, VectorLength)
+  NODE(AccClause, Wait)
+  NODE(AccClause, Worker)
+  NODE(AccClause, Write)
+  NODE(AccClause, Unknown)
+  NODE(parser, AccDefaultClause)
+  NODE_ENUM(parser::AccDefaultClause, Arg)
+  NODE(parser, AccClauseList)
+  NODE(parser, AccCombinedDirective)
+  NODE(parser, AccDataModifier)
+  NODE_ENUM(parser::AccDataModifier, Modifier)
+  NODE(parser, AccDeclarativeDirective)
+  NODE(parser, AccEndAtomic)
+  NODE(parser, AccEndBlockDirective)
+  NODE(parser, AccEndCombinedDirective)
+  NODE(parser, AccGangArgument)
+  NODE(parser, AccObject)
+  NODE(parser, AccObjectList)
+  NODE(parser, AccObjectListWithModifier)
+  NODE(parser, AccObjectListWithReduction)
+  NODE(parser, AccReductionOperator)
+  NODE(parser, AccSizeExpr)
+  NODE(parser, AccSizeExprList)
+  NODE(parser, AccStandaloneDirective)
+  NODE(parser, AccLoopDirective)
+  NODE(parser, AccWaitArgument)
+  static std::string GetNodeName(const llvm::acc::Directive &x) {
+    return llvm::Twine(
+        "llvm::acc::Directive = ", llvm::acc::getOpenACCDirectiveName(x))
+        .str();
+  }
   NODE(parser, AcImpliedDo)
   NODE(parser, AcImpliedDoControl)
   NODE(parser, AcValue)
   NODE(parser, AccessStmt)
   NODE(parser, AccessId)
   NODE(parser, AccessSpec)
   NODE_ENUM(AccessSpec, Kind)
   NODE(parser, AcSpec)
#define NODE(T1, T2) NODE_NAME(T1::T2, #T2)
   NODE(OmpScheduleModifier, Modifier1)
   NODE(OmpScheduleModifier, Modifier2)
   NODE(parser, OmpScheduleModifierType)
   NODE_ENUM(OmpScheduleModifierType, ModType)
   NODE(parser, OmpSectionBlocks)
   NODE(parser, OmpSectionsDirective)
   NODE(parser, OmpSimpleStandaloneDirective)
   NODE(parser, Only)
+  NODE(parser, OpenACCAtomicConstruct)
+  NODE(parser, OpenACCBlockConstruct)
+  NODE(parser, OpenACCCacheConstruct)
+  NODE(parser, OpenACCCombinedConstruct)
+  NODE(parser, OpenACCConstruct)
+  NODE(parser, OpenACCDeclarativeConstruct)
+  NODE(parser, OpenACCLoopConstruct)
+  NODE(parser, OpenACCRoutineConstruct)
+  NODE(parser, OpenACCStandaloneDeclarativeConstruct)
+  NODE(parser, OpenACCStandaloneConstruct)
+  NODE(parser, OpenACCWaitConstruct)
   NODE(parser, OpenMPAtomicConstruct)
   NODE(parser, OpenMPBlockConstruct)
   NODE(parser, OpenMPCancelConstruct)
   NODE(OpenMPCancelConstruct, If)
   NODE(parser, OpenMPCancellationPointConstruct)
   NODE(parser, OpenMPConstruct)
   NODE(parser, OpenMPCriticalConstruct)
   NODE(parser, OpenMPDeclarativeConstruct)

flang/include/flang/Parser/parse-tree.h

 #include "char-block.h"
 #include "characters.h"
 #include "format-specification.h"
 #include "message.h"
 #include "provenance.h"
 #include "flang/Common/Fortran.h"
 #include "flang/Common/idioms.h"
 #include "flang/Common/indirection.h"
+#include "llvm/Frontend/OpenACC/ACC.h.inc"
 #include "llvm/Frontend/OpenMP/OMPConstants.h"
 #include <cinttypes>
 #include <list>
 #include <memory>
 #include <optional>
 #include <string>
 #include <tuple>
 #include <type_traits>

 // Directives, extensions, and deprecated statements
 struct CompilerDirective;
 struct BasedPointerStmt;
 struct StructureDef;
 struct ArithmeticIfStmt;
 struct AssignStmt;
 struct AssignedGotoStmt;
 struct PauseStmt;
+struct OpenACCConstruct;
+struct OpenACCDeclarativeConstruct;
 struct OpenMPConstruct;
 struct OpenMPDeclarativeConstruct;
 struct OmpEndLoopDirective;
 
 // Cooked character stream locations
 using Location = const char *;
 
 // A parse tree node with provenance only
std::variant<common::Indirection<DerivedTypeDef>,
       common::Indirection<EnumDef>, Statement<common::Indirection<GenericStmt>>,
       common::Indirection<InterfaceBlock>,
       Statement<common::Indirection<ParameterStmt>>,
       Statement<common::Indirection<OldParameterStmt>>,
       Statement<common::Indirection<ProcedureDeclarationStmt>>,
       Statement<OtherSpecificationStmt>,
       Statement<common::Indirection<TypeDeclarationStmt>>,
       common::Indirection<StructureDef>,
+      common::Indirection<OpenACCDeclarativeConstruct>,
       common::Indirection<OpenMPDeclarativeConstruct>,
       common::Indirection<CompilerDirective>>
       u;
 };
 
 // R506 implicit-part-stmt ->
 //         implicit-stmt | parameter-stmt | format-stmt | entry-stmt
 struct ImplicitPartStmt {

 };
 
 // R504 specification-part -> [use-stmt]... [import-stmt]... [implicit-part]
 //                            [declaration-construct]...
 // TODO: transfer any statements after the last IMPLICIT (if any)
 // from the implicit part to the declaration constructs
 struct SpecificationPart {
   TUPLE_CLASS_BOILERPLATE(SpecificationPart);
-  std::tuple<std::list<OpenMPDeclarativeConstruct>,
+  std::tuple<std::list<OpenACCDeclarativeConstruct>,
+      std::list<OpenMPDeclarativeConstruct>,
       std::list<Statement<common::Indirection<UseStmt>>>,
       std::list<Statement<common::Indirection<ImportStmt>>>, ImplicitPart,
       std::list<DeclarationConstruct>>
       t;
 };
 
 // R512 internal-subprogram -> function-subprogram | subroutine-subprogram
 struct InternalSubprogram {
std::variant<Statement<ActionStmt>, common::Indirection<AssociateConstruct>,
       common::Indirection<CriticalConstruct>,
       Statement<common::Indirection<LabelDoStmt>>,
       Statement<common::Indirection<EndDoStmt>>,
       common::Indirection<DoConstruct>, common::Indirection<IfConstruct>,
       common::Indirection<SelectRankConstruct>,
       common::Indirection<SelectTypeConstruct>,
       common::Indirection<WhereConstruct>, common::Indirection<ForallConstruct>,
       common::Indirection<CompilerDirective>,
+      common::Indirection<OpenACCConstruct>,
       common::Indirection<OpenMPConstruct>,
       common::Indirection<OmpEndLoopDirective>>
       u;
 };
 
 // R510 execution-part-construct ->
 //        executable-construct | format-stmt | entry-stmt | data-stmt
 // Extension (PGI/Intel): also accept NAMELIST in execution part

 
 struct OpenMPConstruct {
   UNION_CLASS_BOILERPLATE(OpenMPConstruct);
   std::variant<OpenMPStandaloneConstruct, OpenMPSectionsConstruct,
       OpenMPLoopConstruct, OpenMPBlockConstruct, OpenMPAtomicConstruct,
       OpenMPCriticalConstruct>
       u;
 };
+
+// Parse tree nodes for OpenACC 3.0 directives and clauses
+
+struct AccObject {
+  UNION_CLASS_BOILERPLATE(AccObject);
+  std::variant<Designator, /*common block*/ Name> u;
+};
+
+WRAPPER_CLASS(AccObjectList, std::list<AccObject>);
+
+// OpenACC directive beginning or ending a block
+struct AccBlockDirective {
+  WRAPPER_CLASS_BOILERPLATE(AccBlockDirective, llvm::acc::Directive);
+  CharBlock source;
+};
+
+struct AccLoopDirective {
+  WRAPPER_CLASS_BOILERPLATE(AccLoopDirective, llvm::acc::Directive);
+  CharBlock source;
+};
+
+struct AccStandaloneDirective {
+  WRAPPER_CLASS_BOILERPLATE(AccStandaloneDirective, llvm::acc::Directive);
+  CharBlock source;
+};
+
+// 2.11 Combined constructs
+struct AccCombinedDirective {
+  WRAPPER_CLASS_BOILERPLATE(AccCombinedDirective, llvm::acc::Directive);
+  CharBlock source;
+};
+
+struct AccDeclarativeDirective {
+  WRAPPER_CLASS_BOILERPLATE(AccDeclarativeDirective, llvm::acc::Directive);
+  CharBlock source;
+};
+
+// OpenACC Clauses
+struct AccDefaultClause {
+  ENUM_CLASS(Arg, None, Present)
+  WRAPPER_CLASS_BOILERPLATE(AccDefaultClause, Arg);
+  CharBlock source;
+};
+
+struct AccDataModifier {
+  ENUM_CLASS(Modifier, ReadOnly, Zero)
+  WRAPPER_CLASS_BOILERPLATE(AccDataModifier, Modifier);
+  CharBlock source;
+};
+
+struct AccObjectListWithModifier {
+  TUPLE_CLASS_BOILERPLATE(AccObjectListWithModifier);
+  std::tuple<std::optional<AccDataModifier>, AccObjectList> t;
+};
+
+// 2.5.13: + | * | max | min | iand | ior | ieor | .and. | .or. | .eqv. | .neqv.
+struct AccReductionOperator {
+  UNION_CLASS_BOILERPLATE(AccReductionOperator);
+  std::variant<DefinedOperator, ProcedureDesignator> u;
+};
+
+struct AccObjectListWithReduction {
+  TUPLE_CLASS_BOILERPLATE(AccObjectListWithReduction);
+  std::tuple<AccReductionOperator, AccObjectList> t;
+};
+
+struct AccWaitArgument {
+  TUPLE_CLASS_BOILERPLATE(AccWaitArgument);
+  std::tuple<std::optional<ScalarIntExpr>, std::list<ScalarIntExpr>> t;
+};
+
+struct AccSizeExpr {
+  TUPLE_CLASS_BOILERPLATE(AccSizeExpr);
+  CharBlock source;
+  std::tuple<std::optional<ScalarIntExpr>> t; // if null then *
+};
+
+struct AccSizeExprList {
+  WRAPPER_CLASS_BOILERPLATE(AccSizeExprList, std::list<AccSizeExpr>);
+};
+
+struct AccGangArgument {
+  TUPLE_CLASS_BOILERPLATE(AccGangArgument);
+  std::tuple<std::optional<ScalarIntExpr>, std::optional<AccSizeExpr>> t;
+};
+
+struct AccClause {
+  UNION_CLASS_BOILERPLATE(AccClause);
+
+  EMPTY_CLASS(Auto);
+  WRAPPER_CLASS(Async, std::optional<ScalarIntExpr>);
+  WRAPPER_CLASS(Attach, AccObjectList);
+  WRAPPER_CLASS(Bind, Name);
+  EMPTY_CLASS(Capture);
+  WRAPPER_CLASS(Collapse, ScalarIntConstantExpr);
+  WRAPPER_CLASS(Copy, AccObjectList);
+  WRAPPER_CLASS(Copyin, AccObjectListWithModifier);
+  WRAPPER_CLASS(Copyout, AccObjectListWithModifier);
+  WRAPPER_CLASS(Create, AccObjectListWithModifier);
+  WRAPPER_CLASS(Default, AccDefaultClause);
+  WRAPPER_CLASS(DefaultAsync, ScalarIntExpr);
+  WRAPPER_CLASS(Delete, AccObjectList);
+  WRAPPER_CLASS(Detach, AccObjectList);
+  WRAPPER_CLASS(Device, AccObjectList);
+  WRAPPER_CLASS(DeviceNum, ScalarIntConstantExpr);
+  WRAPPER_CLASS(DevicePtr, AccObjectList);
+  WRAPPER_CLASS(DeviceResident, AccObjectList);
+  WRAPPER_CLASS(DeviceType, std::optional<std::list<Name>>);
+  EMPTY_CLASS(Finalize);
+  WRAPPER_CLASS(FirstPrivate, AccObjectList);
+  WRAPPER_CLASS(Gang, std::optional<AccGangArgument>);
+  WRAPPER_CLASS(Host, AccObjectList);
+  WRAPPER_CLASS(If, ScalarLogicalExpr);
+  EMPTY_CLASS(IfPresent);
+  EMPTY_CLASS(Independent);
+  WRAPPER_CLASS(Link, AccObjectList);
+  WRAPPER_CLASS(NoCreate, AccObjectList);
+  EMPTY_CLASS(NoHost);
+  WRAPPER_CLASS(NumGangs, ScalarIntExpr);
+  WRAPPER_CLASS(NumWorkers, ScalarIntExpr);
+  WRAPPER_CLASS(Present, AccObjectList);
+  WRAPPER_CLASS(Private, AccObjectList);
+  WRAPPER_CLASS(Tile, AccSizeExprList);
+  WRAPPER_CLASS(UseDevice, AccObjectList);
+  EMPTY_CLASS(Read);
+  WRAPPER_CLASS(Reduction, AccObjectListWithReduction);
+  WRAPPER_CLASS(Self, std::optional<ScalarLogicalExpr>);
+  EMPTY_CLASS(Seq);
+  WRAPPER_CLASS(Vector, std::optional<ScalarIntExpr>);
+  WRAPPER_CLASS(VectorLength, ScalarIntExpr);
+  WRAPPER_CLASS(Wait, std::optional<AccWaitArgument>);
+  WRAPPER_CLASS(Worker, std::optional<ScalarIntExpr>);
+  EMPTY_CLASS(Write);
+  EMPTY_CLASS(Unknown);
+
+  CharBlock source;
+
+  std::variant<Auto, Async, Attach, Bind, Capture, Collapse, Copy, Copyin,
+      Copyout, Create, Default, DefaultAsync, Delete, Detach, Device, DeviceNum,
+      DevicePtr, DeviceResident, DeviceType, Finalize, FirstPrivate, Gang, Host,
+      If, IfPresent, Independent, Link, NoCreate, NoHost, NumGangs, NumWorkers,
+      Present, Private, Tile, UseDevice, Read, Reduction, Self, Seq, Vector,
+      VectorLength, Wait, Worker, Write, Unknown>
+      u;
+};
+
+struct AccClauseList {
+  WRAPPER_CLASS_BOILERPLATE(AccClauseList, std::list<AccClause>);
+  CharBlock source;
+};
+
+struct OpenACCRoutineConstruct {
+  TUPLE_CLASS_BOILERPLATE(OpenACCRoutineConstruct);
+  CharBlock source;
+  std::tuple<Verbatim, std::optional<Name>, AccClauseList> t;
+};
+
+struct OpenACCCacheConstruct {
+  TUPLE_CLASS_BOILERPLATE(OpenACCCacheConstruct);
+  CharBlock source;
+  std::tuple<Verbatim, AccObjectListWithModifier> t;
+};
+
+struct OpenACCWaitConstruct {
+  TUPLE_CLASS_BOILERPLATE(OpenACCWaitConstruct);
+  CharBlock source;
+  std::tuple<Verbatim, std::optional<AccWaitArgument>, AccClauseList> t;
+};
+
+struct AccBeginLoopDirective {
+  TUPLE_CLASS_BOILERPLATE(AccBeginLoopDirective);
+  std::tuple<AccLoopDirective, AccClauseList> t;
+  CharBlock source;
+};
+
+struct AccBeginBlockDirective {
+  TUPLE_CLASS_BOILERPLATE(AccBeginBlockDirective);
+  CharBlock source;
+  std::tuple<AccBlockDirective, AccClauseList> t;
+};
+
+struct AccEndBlockDirective {
+  CharBlock source;
+  WRAPPER_CLASS_BOILERPLATE(AccEndBlockDirective, AccBlockDirective);
+};
+
+// ACC END ATOMIC
+EMPTY_CLASS(AccEndAtomic);
+
+// ACC ATOMIC READ
+struct AccAtomicRead {
+  TUPLE_CLASS_BOILERPLATE(AccAtomicRead);
+  std::tuple<Verbatim, Statement<AssignmentStmt>, std::optional<AccEndAtomic>>
+      t;
+};
+
+// ACC ATOMIC WRITE
+struct AccAtomicWrite {
+  TUPLE_CLASS_BOILERPLATE(AccAtomicWrite);
+  std::tuple<Verbatim, Statement<AssignmentStmt>, std::optional<AccEndAtomic>>
+      t;
+};
+
+// ACC ATOMIC UPDATE
+struct AccAtomicUpdate {
+  TUPLE_CLASS_BOILERPLATE(AccAtomicUpdate);
+  std::tuple<std::optional<Verbatim>, Statement<AssignmentStmt>,
+      std::optional<AccEndAtomic>>
+      t;
+};
+
+// ACC ATOMIC CAPTURE
+struct AccAtomicCapture {
+  TUPLE_CLASS_BOILERPLATE(AccAtomicCapture);
+  WRAPPER_CLASS(Stmt1, Statement<AssignmentStmt>);
+  WRAPPER_CLASS(Stmt2, Statement<AssignmentStmt>);
+  std::tuple<Verbatim, Stmt1, Stmt2, AccEndAtomic> t;
+};
+
+struct OpenACCAtomicConstruct {
+  UNION_CLASS_BOILERPLATE(OpenACCAtomicConstruct);
+  std::variant<AccAtomicRead, AccAtomicWrite, AccAtomicCapture, AccAtomicUpdate>
+      u;
+};
+
+struct OpenACCBlockConstruct {
+  TUPLE_CLASS_BOILERPLATE(OpenACCBlockConstruct);
+  std::tuple<AccBeginBlockDirective, Block, AccEndBlockDirective> t;
+};
+
+struct OpenACCStandaloneDeclarativeConstruct {
+  TUPLE_CLASS_BOILERPLATE(OpenACCStandaloneDeclarativeConstruct);
+  CharBlock source;
+  std::tuple<AccDeclarativeDirective, AccClauseList> t;
+};
+
+struct AccBeginCombinedDirective {
+  TUPLE_CLASS_BOILERPLATE(AccBeginCombinedDirective);
+  std::tuple<AccCombinedDirective, AccClauseList> t;
+};
+
+struct AccEndCombinedDirective {
+  WRAPPER_CLASS_BOILERPLATE(AccEndCombinedDirective, AccCombinedDirective);
+  CharBlock source;
+};
+
+struct OpenACCCombinedConstruct {
+  TUPLE_CLASS_BOILERPLATE(OpenACCCombinedConstruct);
+  CharBlock source;
+  std::tuple<AccBeginCombinedDirective, Block,
+      std::optional<AccEndCombinedDirective>>
+      t;
+};
+
+struct OpenACCDeclarativeConstruct {
+  UNION_CLASS_BOILERPLATE(OpenACCDeclarativeConstruct);
+  CharBlock source;
+  std::variant<OpenACCStandaloneDeclarativeConstruct> u;
+};
+
+// OpenACC directives enclosing do loop
+struct OpenACCLoopConstruct {
+  TUPLE_CLASS_BOILERPLATE(OpenACCLoopConstruct);
+  OpenACCLoopConstruct(AccBeginLoopDirective &&a)
+      : t({std::move(a), std::nullopt}) {}
+  std::tuple<AccBeginLoopDirective, std::optional<DoConstruct>> t;
+};
+
+struct OpenACCStandaloneConstruct {
+  TUPLE_CLASS_BOILERPLATE(OpenACCStandaloneConstruct);
+  CharBlock source;
+  std::tuple<AccStandaloneDirective, AccClauseList> t;
+};
+
+struct OpenACCConstruct {
+  UNION_CLASS_BOILERPLATE(OpenACCConstruct);
+  std::variant<OpenACCBlockConstruct, OpenACCCombinedConstruct,
+      OpenACCLoopConstruct, OpenACCStandaloneConstruct, OpenACCRoutineConstruct,
+      OpenACCCacheConstruct, OpenACCWaitConstruct, OpenACCAtomicConstruct>
+      u;
+};
+
 } // namespace Fortran::parser
 #endif // FORTRAN_PARSER_PARSE_TREE_H_

flang/lib/Parser/CMakeLists.txt

 
 add_flang_library(FortranParser
   Fortran-parsers.cpp
   char-buffer.cpp
   char-block.cpp
   char-set.cpp
   characters.cpp
   debug-parser.cpp
   executable-parsers.cpp
   expr-parsers.cpp
   instrumented-parser.cpp
   io-parsers.cpp
   message.cpp
+  openacc-parsers.cpp
   openmp-parsers.cpp
   parse-tree.cpp
   parsing.cpp
   preprocessor.cpp
   prescan.cpp
   program-parsers.cpp
   provenance.cpp
   source.cpp
   token-sequence.cpp
   tools.cpp
   unparse.cpp
   user-state.cpp
 
   LINK_LIBS
   FortranCommon
 
   LINK_COMPONENTS
   Support
 
   DEPENDS
   omp_gen
+  acc_gen
 )

flang/lib/Parser/executable-parsers.cpp

first(construct<ExecutableConstruct>(CapturedLabelDoStmt{}),
         construct<ExecutableConstruct>(indirect(Parser<ChangeTeamConstruct>{})),
         construct<ExecutableConstruct>(indirect(Parser<CriticalConstruct>{})),
         construct<ExecutableConstruct>(indirect(Parser<IfConstruct>{})),
         construct<ExecutableConstruct>(indirect(Parser<SelectRankConstruct>{})),
         construct<ExecutableConstruct>(indirect(Parser<SelectTypeConstruct>{})),
         construct<ExecutableConstruct>(indirect(whereConstruct)),
         construct<ExecutableConstruct>(indirect(forallConstruct)),
         construct<ExecutableConstruct>(indirect(ompEndLoopDirective)),
+        construct<ExecutableConstruct>(indirect(openaccConstruct)),
         construct<ExecutableConstruct>(indirect(openmpConstruct)),
         construct<ExecutableConstruct>(indirect(compilerDirective)))};
 
 // R510 execution-part-construct ->
 //        executable-construct | format-stmt | entry-stmt | data-stmt
 // Extension (PGI/Intel): also accept NAMELIST in execution part
 constexpr auto obsoleteExecutionPartConstruct{recovery(ignoredStatementPrefix >>
         fail<ExecutionPartConstruct>(

flang/lib/Parser/openacc-parsers.cpp

+//===-- lib/Parser/openacc-parsers.cpp ------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// Top-level grammar specification for OpenACC 3.0.
+
+#include "basic-parsers.h"
+#include "expr-parsers.h"
+#include "misc-parsers.h"
+#include "stmt-parser.h"
+#include "token-parsers.h"
+#include "type-parser-implementation.h"
+#include "flang/Parser/parse-tree.h"
+
+// OpenACC Directives and Clauses
+namespace Fortran::parser {
+
+constexpr auto startAccLine = skipStuffBeforeStatement >> "!$ACC "_sptok;
+constexpr auto endAccLine = space >> endOfLine;
+
+// Basic clauses
+TYPE_PARSER("AUTO" >> construct<AccClause>(construct<AccClause::Auto>()) ||
+    "ASYNC" >> construct<AccClause>(construct<AccClause::Async>(
+                   maybe(parenthesized(scalarIntExpr)))) ||
+    "ATTACH" >> construct<AccClause>(construct<AccClause::Attach>(
+                    parenthesized(Parser<AccObjectList>{}))) ||
+    "BIND" >>
+        construct<AccClause>(construct<AccClause::Bind>(parenthesized(name))) ||
+    "CAPTURE" >> construct<AccClause>(construct<AccClause::Capture>()) ||
+    "COLLAPSE" >> construct<AccClause>(construct<AccClause::Collapse>(
+                      parenthesized(scalarIntConstantExpr))) ||
+    ("COPY"_tok || "PRESENT_OR_COPY"_tok || "PCOPY"_tok) >>
+        construct<AccClause>(construct<AccClause::Copy>(
+            parenthesized(Parser<AccObjectList>{}))) ||
+    ("COPYIN"_tok || "PRESENT_OR_COPYIN"_tok || "PCOPYIN"_tok) >>
+        construct<AccClause>(construct<AccClause::Copyin>(
+            parenthesized(Parser<AccObjectListWithModifier>{}))) ||
+    ("COPYOUT"_tok || "PRESENT_OR_COPYOUT"_tok || "PCOPYOUT"_tok) >>
+        construct<AccClause>(construct<AccClause::Copyout>(
+            parenthesized(Parser<AccObjectListWithModifier>{}))) ||
+    ("CREATE"_tok || "PRESENT_OR_CREATE"_tok || "PCREATE"_tok) >>
+        construct<AccClause>(construct<AccClause::Create>(
+            parenthesized(Parser<AccObjectListWithModifier>{}))) ||
+    "DEFAULT" >> construct<AccClause>(construct<AccClause::Default>(
+                     Parser<AccDefaultClause>{})) ||
+    "DEFAULT_ASYNC" >> construct<AccClause>(construct<AccClause::DefaultAsync>(
+                           parenthesized(scalarIntExpr))) ||
+    "DELETE" >> construct<AccClause>(construct<AccClause::Delete>(
+                    parenthesized(Parser<AccObjectList>{}))) ||
+    "DETACH" >> construct<AccClause>(construct<AccClause::Detach>(
+                    parenthesized(Parser<AccObjectList>{}))) ||
+    "DEVICE" >> construct<AccClause>(construct<AccClause::Device>(
+                    parenthesized(Parser<AccObjectList>{}))) ||
+    "DEVICEPTR" >> construct<AccClause>(construct<AccClause::DevicePtr>(
+                       parenthesized(Parser<AccObjectList>{}))) ||
+    "DEVICENUM" >> construct<AccClause>(construct<AccClause::DeviceNum>(
+                       parenthesized(scalarIntConstantExpr))) ||
+    "DEVICE_RESIDENT" >>
+        construct<AccClause>(construct<AccClause::DeviceResident>(
+            parenthesized(Parser<AccObjectList>{}))) ||
+    ("DEVICE_TYPE"_tok || "DTYPE"_tok) >>
+        construct<AccClause>(construct<AccClause::DeviceType>(parenthesized(
+            "*" >> construct<std::optional<std::list<Name>>>()))) ||
+    ("DEVICE_TYPE"_tok || "DTYPE"_tok) >>
+        construct<AccClause>(construct<AccClause::DeviceType>(
+            parenthesized(maybe(nonemptyList(name))))) ||
+    "FINALIZE" >> construct<AccClause>(construct<AccClause::Finalize>()) ||
+    "FIRSTPRIVATE" >> construct<AccClause>(construct<AccClause::FirstPrivate>(
+                          parenthesized(Parser<AccObjectList>{}))) ||
+    "GANG" >> construct<AccClause>(construct<AccClause::Gang>(
+                  maybe(parenthesized(Parser<AccGangArgument>{})))) ||
+    "HOST" >> construct<AccClause>(construct<AccClause::Host>(
+                  parenthesized(Parser<AccObjectList>{}))) ||
+    "IF" >> construct<AccClause>(
+                construct<AccClause::If>(parenthesized(scalarLogicalExpr))) ||
+    "IF_PRESENT" >> construct<AccClause>(construct<AccClause::IfPresent>()) ||
+    "INDEPENDENT" >>
+        construct<AccClause>(construct<AccClause::Independent>()) ||
+    "LINK" >> construct<AccClause>(construct<AccClause::Link>(
+                  parenthesized(Parser<AccObjectList>{}))) ||
+    "NO_CREATE" >> construct<AccClause>(construct<AccClause::NoCreate>(
+                       parenthesized(Parser<AccObjectList>{}))) ||
+    "NOHOST" >> construct<AccClause>(construct<AccClause::NoHost>()) ||
+    "NUM_GANGS" >> construct<AccClause>(construct<AccClause::NumGangs>(
+                       parenthesized(scalarIntExpr))) ||
+    "NUM_WORKERS" >> construct<AccClause>(construct<AccClause::NumWorkers>(
+                         parenthesized(scalarIntExpr))) ||
+    "PRESENT" >> construct<AccClause>(construct<AccClause::Present>(
+                     parenthesized(Parser<AccObjectList>{}))) ||
+    "PRIVATE" >> construct<AccClause>(construct<AccClause::Private>(
+                     parenthesized(Parser<AccObjectList>{}))) ||
+    "READ" >> construct<AccClause>(construct<AccClause::Read>()) ||
+    "REDUCTION" >> construct<AccClause>(construct<AccClause::Reduction>(
+                       parenthesized(construct<AccObjectListWithReduction>(
+                           Parser<AccReductionOperator>{} / ":",
+                           Parser<AccObjectList>{})))) ||
+    "SELF" >> construct<AccClause>(construct<AccClause::Self>(
+                  maybe(parenthesized(scalarLogicalExpr)))) ||
+    "SEQ" >> construct<AccClause>(construct<AccClause::Seq>()) ||
+    "TILE" >> construct<AccClause>(construct<AccClause::Tile>(
+                  parenthesized(Parser<AccSizeExprList>{}))) ||
+    "USE_DEVICE" >> construct<AccClause>(construct<AccClause::UseDevice>(
+                        parenthesized(Parser<AccObjectList>{}))) ||
+    "VECTOR_LENGTH" >> construct<AccClause>(construct<AccClause::VectorLength>(
+                           parenthesized(scalarIntExpr))) ||
+    "VECTOR" >>
+        construct<AccClause>(construct<AccClause::Vector>(maybe(
+            parenthesized(("LENGTH:" >> scalarIntExpr || scalarIntExpr))))) ||
+    "WAIT" >> construct<AccClause>(construct<AccClause::Wait>(
+                  maybe(Parser<AccWaitArgument>{}))) ||
+    "WORKER" >>
+        construct<AccClause>(construct<AccClause::Worker>(maybe(
+            parenthesized(("NUM:" >> scalarIntExpr || scalarIntExpr))))) ||
+    "WRITE" >> construct<AccClause>(construct<AccClause::Auto>()))
+
+TYPE_PARSER(
+    construct<AccObject>(designator) || construct<AccObject>("/" >> name / "/"))
+
+TYPE_PARSER(construct<AccObjectList>(nonemptyList(Parser<AccObject>{})))
+
+TYPE_PARSER(construct<AccObjectListWithModifier>(
+    maybe(Parser<AccDataModifier>{}), Parser<AccObjectList>{}))
+
+TYPE_PARSER(construct<AccWaitArgument>(
+    maybe("DEVNUM:" >> scalarIntExpr / ":"), nonemptyList(scalarIntExpr)))
+
+// 2.9 (1609) size-expr is one of:
+//   int-expr
+TYPE_PARSER(construct<AccSizeExpr>(scalarIntExpr) ||
+    construct<AccSizeExpr>("*" >> maybe(scalarIntExpr)))
+TYPE_PARSER(construct<AccSizeExprList>(nonemptyList(Parser<AccSizeExpr>{})))
+
+// 2.9 (1607) gang-arg is one of:
+//   [num:]int-expr
+//   static:size-expr
+TYPE_PARSER(construct<AccGangArgument>(maybe(scalarIntExpr),
+                maybe(","_tok / "STATIC:" >> Parser<AccSizeExpr>{})) ||
+    construct<AccGangArgument>(maybe("NUM:" >> scalarIntExpr),
+        maybe(","_tok / "STATIC:" >> Parser<AccSizeExpr>{})))
+
+// 2.5.13 Reduction
+TYPE_PARSER(construct<AccReductionOperator>(Parser<DefinedOperator>{}) ||
+    construct<AccReductionOperator>(Parser<ProcedureDesignator>{}))
+
+// 2.5.14 Default clause
+TYPE_PARSER(construct<AccDefaultClause>(
+    parenthesized(first("NONE" >> pure(AccDefaultClause::Arg::None),
+        "PRESENT" >> pure(AccDefaultClause::Arg::Present)))))
+
+// Modifier for copyin, copyout, cache and create
+TYPE_PARSER(construct<AccDataModifier>(
+    first("ZERO:" >> pure(AccDataModifier::Modifier::Zero),
+        "READONLY:" >> pure(AccDataModifier::Modifier::ReadOnly))))
+
+// Combined directives
+TYPE_PARSER(sourced(construct<AccCombinedDirective>(
+    first("KERNELS LOOP" >> pure(llvm::acc::Directive::ACCD_kernels_loop),
+        "PARALLEL LOOP" >> pure(llvm::acc::Directive::ACCD_parallel_loop),
+        "SERIAL LOOP" >> pure(llvm::acc::Directive::ACCD_serial_loop)))))
+
+// Block directives
+TYPE_PARSER(sourced(construct<AccBlockDirective>(
+    first("DATA" >> pure(llvm::acc::Directive::ACCD_data),
+        "HOST_DATA" >> pure(llvm::acc::Directive::ACCD_host_data),
+        "KERNELS" >> pure(llvm::acc::Directive::ACCD_kernels),
+        "PARALLEL" >> pure(llvm::acc::Directive::ACCD_parallel),
+        "SERIAL" >> pure(llvm::acc::Directive::ACCD_serial)))))
+
+// Standalone directives
+TYPE_PARSER(sourced(construct<AccStandaloneDirective>(
+    first("ENTER DATA" >> pure(llvm::acc::Directive::ACCD_enter_data),
+        "EXIT DATA" >> pure(llvm::acc::Directive::ACCD_exit_data),
+        "INIT" >> pure(llvm::acc::Directive::ACCD_init),
+        "SHUTDOWN" >> pure(llvm::acc::Directive::ACCD_shutdown),
+        "SET" >> pure(llvm::acc::Directive::ACCD_set),
+        "UPDATE" >> pure(llvm::acc::Directive::ACCD_update)))))
+
+// Loop directives
+TYPE_PARSER(sourced(construct<AccLoopDirective>(
+    first("LOOP" >> pure(llvm::acc::Directive::ACCD_loop)))))
+
+TYPE_PARSER(construct<AccBeginLoopDirective>(
+    sourced(Parser<AccLoopDirective>{}), Parser<AccClauseList>{}))
+
+TYPE_PARSER(
+    construct<OpenACCLoopConstruct>(sourced(Parser<AccBeginLoopDirective>{})))
+
+// 2.15.1 Routine directive
+TYPE_PARSER(sourced(construct<OpenACCRoutineConstruct>(verbatim("ROUTINE"_tok),
+    maybe(parenthesized(name)), Parser<AccClauseList>{})))
+
+// 2.10 Cache directive
+TYPE_PARSER(sourced(
+    construct<OpenACCCacheConstruct>(sourced(construct<Verbatim>("CACHE"_tok)),
+        parenthesized(Parser<AccObjectListWithModifier>{}))))
+
+// 2.11 Combined constructs
+TYPE_PARSER(startAccLine >> construct<AccEndCombinedDirective>(sourced(
+                                "END"_tok >> Parser<AccCombinedDirective>{})))
+
+TYPE_PARSER(construct<AccBeginCombinedDirective>(
+    sourced(Parser<AccCombinedDirective>{}), Parser<AccClauseList>{}))
+
+TYPE_PARSER(construct<OpenACCCombinedConstruct>(
+    Parser<AccBeginCombinedDirective>{} / endAccLine, block,
+    maybe(Parser<AccEndCombinedDirective>{} / endAccLine)))
+
+// 2.12 Atomic constructs
+TYPE_PARSER(construct<AccEndAtomic>(startAccLine >> "END ATOMIC"_tok))
+
+TYPE_PARSER("ATOMIC" >>
+    construct<AccAtomicRead>(verbatim("READ"_tok) / endAccLine,
+        statement(assignmentStmt), maybe(Parser<AccEndAtomic>{} / endAccLine)))
+
+TYPE_PARSER("ATOMIC" >>
+    construct<AccAtomicWrite>(verbatim("WRITE"_tok) / endAccLine,
+        statement(assignmentStmt), maybe(Parser<AccEndAtomic>{} / endAccLine)))
+
+TYPE_PARSER("ATOMIC" >>
+    construct<AccAtomicUpdate>(maybe(verbatim("UPDATE"_tok)) / endAccLine,
+        statement(assignmentStmt), maybe(Parser<AccEndAtomic>{} / endAccLine)))
+
+TYPE_PARSER("ATOMIC" >>
+    construct<AccAtomicCapture>(verbatim("CAPTURE"_tok) / endAccLine,
+        statement(assignmentStmt), statement(assignmentStmt),
+        Parser<AccEndAtomic>{} / endAccLine))
+
+TYPE_PARSER(construct<OpenACCAtomicConstruct>(Parser<AccAtomicRead>{}) ||
+    construct<OpenACCAtomicConstruct>(Parser<AccAtomicCapture>{}) ||
+    construct<OpenACCAtomicConstruct>(Parser<AccAtomicWrite>{}) ||
+    construct<OpenACCAtomicConstruct>(Parser<AccAtomicUpdate>{}))
+
+// 2.13 Declare constructs
+TYPE_PARSER(sourced(construct<AccDeclarativeDirective>(
+    first("DECLARE" >> pure(llvm::acc::Directive::ACCD_declare)))))
+
+// [Clause, [Clause], ...]
+TYPE_PARSER(sourced(construct<AccClauseList>(
+    many(maybe(","_tok) >> sourced(Parser<AccClause>{})))))
+
+// 2.16.3 Wait directive
+TYPE_PARSER(sourced(construct<OpenACCWaitConstruct>(
+    sourced(construct<Verbatim>("WAIT"_tok)),
+    maybe(parenthesized(Parser<AccWaitArgument>{})), Parser<AccClauseList>{})))
+
+// Block Constructs
+TYPE_PARSER(sourced(construct<AccBeginBlockDirective>(
+    sourced(Parser<AccBlockDirective>{}), Parser<AccClauseList>{})))
+
+TYPE_PARSER(startAccLine >> sourced(construct<AccEndBlockDirective>("END"_tok >>
+                                sourced(Parser<AccBlockDirective>{}))))
+
+TYPE_PARSER(construct<OpenACCBlockConstruct>(
+    Parser<AccBeginBlockDirective>{} / endAccLine, block,
+    Parser<AccEndBlockDirective>{} / endAccLine))
+
+// Standalone constructs
+TYPE_PARSER(construct<OpenACCStandaloneConstruct>(
+    sourced(Parser<AccStandaloneDirective>{}), Parser<AccClauseList>{}))
+
+// Standalone declarative constructs
+TYPE_PARSER(construct<OpenACCStandaloneDeclarativeConstruct>(
+    sourced(Parser<AccDeclarativeDirective>{}), Parser<AccClauseList>{}))
+
+TYPE_PARSER(
+    startAccLine >> sourced(construct<OpenACCDeclarativeConstruct>(
+                        Parser<OpenACCStandaloneDeclarativeConstruct>{})))
+
+// OpenACC constructs
+TYPE_CONTEXT_PARSER("OpenACC construct"_en_US,
+    startAccLine >>
+        first(construct<OpenACCConstruct>(Parser<OpenACCBlockConstruct>{}),
+            construct<OpenACCConstruct>(Parser<OpenACCCombinedConstruct>{}),
+            construct<OpenACCConstruct>(Parser<OpenACCLoopConstruct>{}),
+            construct<OpenACCConstruct>(Parser<OpenACCStandaloneConstruct>{}),
+            construct<OpenACCConstruct>(Parser<OpenACCRoutineConstruct>{}),
+            construct<OpenACCConstruct>(Parser<OpenACCCacheConstruct>{}),
+            construct<OpenACCConstruct>(Parser<OpenACCWaitConstruct>{}),
+            construct<OpenACCConstruct>(Parser<OpenACCAtomicConstruct>{})))
+} // namespace Fortran::parser

flang/lib/Parser/openmp-parsers.cpp

 #include "flang/Parser/parse-tree.h"
 
 // OpenMP Directives and Clauses
 namespace Fortran::parser {
 
 constexpr auto startOmpLine = skipStuffBeforeStatement >> "!$OMP "_sptok;
 constexpr auto endOmpLine = space >> endOfLine;
 
-template <typename A> constexpr decltype(auto) verbatim(A x) {
-  return sourced(construct<Verbatim>(x));
-}
-
 // OpenMP Clauses
 // 2.15.3.1 DEFAULT (PRIVATE | FIRSTPRIVATE | SHARED | NONE)
 TYPE_PARSER(construct<OmpDefaultClause>(
     "PRIVATE" >> pure(OmpDefaultClause::Type::Private) ||
     "FIRSTPRIVATE" >> pure(OmpDefaultClause::Type::Firstprivate) ||
     "SHARED" >> pure(OmpDefaultClause::Type::Shared) ||
     "NONE" >> pure(OmpDefaultClause::Type::None)))
 

flang/lib/Parser/parsing.cpp

for (const auto &predef : options.predefinitions) {
     } else {
       preprocessor.Undefine(predef.first);
     }
   }
   Prescanner prescanner{messages_, cooked_, preprocessor, options.features};
   prescanner.set_fixedForm(options.isFixedForm)
       .set_fixedFormColumnLimit(options.fixedFormColumns)
       .AddCompilerDirectiveSentinel("dir$");
+  if (options.features.IsEnabled(LanguageFeature::OpenACC)) {
+    prescanner.AddCompilerDirectiveSentinel("$acc");
+  }
   if (options.features.IsEnabled(LanguageFeature::OpenMP)) {
     prescanner.AddCompilerDirectiveSentinel("$omp");
     prescanner.AddCompilerDirectiveSentinel("$"); // OMP conditional line
   }
   ProvenanceRange range{allSources.AddIncludedFile(
       *sourceFile, ProvenanceRange{}, options.isModuleFile)};
   prescanner.Prescan(range);
   if (cooked_.BufferedBytes() == 0 && !options.isModuleFile) {

flang/lib/Parser/program-parsers.cpp

TYPE_PARSER(construct<ProgramUnit>(indirect(Parser<Module>{})) ||
     construct<ProgramUnit>(indirect(Parser<Submodule>{})) ||
     construct<ProgramUnit>(indirect(Parser<BlockData>{})) ||
     construct<ProgramUnit>(indirect(Parser<MainProgram>{})))
 
 // R504 specification-part ->
 //         [use-stmt]... [import-stmt]... [implicit-part]
 //         [declaration-construct]...
 TYPE_CONTEXT_PARSER("specification part"_en_US,
-    construct<SpecificationPart>(many(openmpDeclarativeConstruct),
+    construct<SpecificationPart>(many(openaccDeclarativeConstruct),
+        many(openmpDeclarativeConstruct),
         many(statement(indirect(Parser<UseStmt>{}))),
         many(unambiguousStatement(indirect(Parser<ImportStmt>{}))),
         implicitPart, many(declarationConstruct)))
 
 // R507 declaration-construct ->
 //        specification-construct | data-stmt | format-stmt |
 //        entry-stmt | stmt-function-stmt
 // N.B. These parsers incorporate recognition of some other statements that
 // may have been misplaced in the sequence of statements that are acceptable
 // as a specification part in order to improve error recovery.
 // Also note that many instances of specification-part in the standard grammar
 // are in contexts that impose constraints on the kinds of statements that
 // are allowed, and so we have a variant production for declaration-construct
 // that implements those constraints.
-constexpr auto execPartLookAhead{
-    first(actionStmt >> ok, ompEndLoopDirective >> ok, openmpConstruct >> ok,
-        "ASSOCIATE ("_tok, "BLOCK"_tok, "SELECT"_tok, "CHANGE TEAM"_sptok,
-        "CRITICAL"_tok, "DO"_tok, "IF ("_tok, "WHERE ("_tok, "FORALL ("_tok)};
+constexpr auto execPartLookAhead{first(actionStmt >> ok,
+    ompEndLoopDirective >> ok, openaccConstruct >> ok, openmpConstruct >> ok,
 constexpr auto declErrorRecovery{
     stmtErrorRecoveryStart >> !execPartLookAhead >> skipStmtErrorRecovery};
 constexpr auto misplacedSpecificationStmt{Parser<UseStmt>{} >>
         fail<DeclarationConstruct>("misplaced USE statement"_err_en_US) ||
     Parser<ImportStmt>{} >>
         fail<DeclarationConstruct>(
             "IMPORT statements must follow any USE statements and precede all other declarations"_err_en_US) ||
     Parser<ImplicitStmt>{} >>
construct<DeclarationConstruct>(
         stmtErrorRecoveryStart >> skipStmtErrorRecovery))};
 
 // R504 variant for many contexts (modules, submodules, BLOCK DATA subprograms,
 // and interfaces) which have constraints on their specification parts that
 // preclude FORMAT, ENTRY, and statement functions, and benefit from
 // specialized error recovery in the event of a spurious executable
 // statement.
 constexpr auto limitedSpecificationPart{inContext("specification part"_en_US,
-    construct<SpecificationPart>(many(openmpDeclarativeConstruct),
+    construct<SpecificationPart>(many(openaccDeclarativeConstruct),
+        many(openmpDeclarativeConstruct),
         many(statement(indirect(Parser<UseStmt>{}))),
         many(unambiguousStatement(indirect(Parser<ImportStmt>{}))),
         implicitPart, many(limitedDeclarationConstruct)))};
 
 // R508 specification-construct ->
 //        derived-type-def | enum-def | generic-stmt | interface-block |
 //        parameter-stmt | procedure-declaration-stmt |
 //        other-specification-stmt | type-declaration-stmt
 TYPE_CONTEXT_PARSER("specification construct"_en_US,
     first(construct<SpecificationConstruct>(indirect(Parser<DerivedTypeDef>{})),
         construct<SpecificationConstruct>(indirect(Parser<EnumDef>{})),
         construct<SpecificationConstruct>(
             statement(indirect(Parser<GenericStmt>{}))),
         construct<SpecificationConstruct>(indirect(interfaceBlock)),
         construct<SpecificationConstruct>(statement(indirect(parameterStmt))),
         construct<SpecificationConstruct>(
             statement(indirect(oldParameterStmt))),
         construct<SpecificationConstruct>(
             statement(indirect(Parser<ProcedureDeclarationStmt>{}))),
         construct<SpecificationConstruct>(
             statement(Parser<OtherSpecificationStmt>{})),
         construct<SpecificationConstruct>(
             statement(indirect(typeDeclarationStmt))),
         construct<SpecificationConstruct>(indirect(Parser<StructureDef>{})),
+        construct<SpecificationConstruct>(
+            indirect(openaccDeclarativeConstruct)),
         construct<SpecificationConstruct>(indirect(openmpDeclarativeConstruct)),
         construct<SpecificationConstruct>(indirect(compilerDirective))))
 
 // R513 other-specification-stmt ->
 //        access-stmt | allocatable-stmt | asynchronous-stmt | bind-stmt |
 //        codimension-stmt | contiguous-stmt | dimension-stmt | external-stmt |
 //        intent-stmt | intrinsic-stmt | namelist-stmt | optional-stmt |
 //        pointer-stmt | protected-stmt | save-stmt | target-stmt |

flang/lib/Parser/stmt-parser.h

 
 // Error recovery across statements: skip the line, unless it looks
 // like it might end the containing construct.
 constexpr auto stmtErrorRecoveryStart{ignoredStatementPrefix};
 constexpr auto skipBadLine{SkipPast<'\n'>{} >> construct<ErrorRecovery>()};
 constexpr auto executionPartErrorRecovery{stmtErrorRecoveryStart >>
     !"END"_tok >> !"CONTAINS"_tok >> !"ELSE"_tok >> !"CASE"_tok >>
     !"TYPE IS"_tok >> !"CLASS"_tok >> !"RANK"_tok >>
+    !("!$ACC "_sptok >> "END"_tok) >>
     !("!$OMP "_sptok >> ("END"_tok || "SECTION"_id)) >> skipBadLine};
 
 // END statement error recovery
 constexpr auto missingOptionalName{pure<std::optional<Name>>()};
 constexpr auto noNameEnd{"END" >> missingOptionalName};
 constexpr auto atEndOfStmt{space >>
     withMessage("expected end of statement"_err_en_US, lookAhead(";\n"_ch))};
 constexpr auto bareEnd{noNameEnd / recovery(atEndOfStmt, SkipTo<'\n'>{})};

flang/lib/Parser/token-parsers.h

constexpr auto logicalFALSE{
     (".FALSE."_tok ||
         extension<LanguageFeature::LogicalAbbreviations>(".F."_tok)) >>
     pure(false)};
 
 // deprecated: Hollerith literals
 constexpr auto rawHollerithLiteral{
     deprecated<LanguageFeature::Hollerith>(HollerithLiteral{})};
 
+template <typename A> constexpr decltype(auto) verbatim(A x) {
+  return sourced(construct<Verbatim>(x));
+}
+
 } // namespace Fortran::parser
 #endif // FORTRAN_PARSER_TOKEN_PARSERS_H_

flang/lib/Parser/type-parsers.h

 constexpr Parser<EndFunctionStmt> endFunctionStmt; // R1533
 constexpr Parser<SubroutineSubprogram> subroutineSubprogram; // R1534
 constexpr Parser<SubroutineStmt> subroutineStmt; // R1535
 constexpr Parser<DummyArg> dummyArg; // R1536
 constexpr Parser<EndSubroutineStmt> endSubroutineStmt; // R1537
 constexpr Parser<EntryStmt> entryStmt; // R1541
 constexpr Parser<ContainsStmt> containsStmt; // R1543
 constexpr Parser<CompilerDirective> compilerDirective;
+constexpr Parser<OpenACCConstruct> openaccConstruct;
+constexpr Parser<OpenACCDeclarativeConstruct> openaccDeclarativeConstruct;
 constexpr Parser<OpenMPConstruct> openmpConstruct;
 constexpr Parser<OpenMPDeclarativeConstruct> openmpDeclarativeConstruct;
 constexpr Parser<OmpEndLoopDirective> ompEndLoopDirective;
 } // namespace Fortran::parser
 #endif // FORTRAN_PARSER_TYPE_PARSERS_H_

flang/lib/Parser/unparse.cpp

if (!list.empty()) {
       Put("(");
       for (const char *tkr : list) {
         Put(*tkr);
       }
       Put(") ");
     }
     Walk(std::get<Name>(x.t));
   }
+
+  // OpenACC Directives & Clauses
+  void Unparse(const AccAtomicCapture &x) {
+    BeginOpenACC();
+    Word("!$ACC CAPTURE");
+    Put("\n");
+    EndOpenACC();
+    Walk(std::get<AccAtomicCapture::Stmt1>(x.t));
+    Put("\n");
+    Walk(std::get<AccAtomicCapture::Stmt2>(x.t));
+    BeginOpenACC();
+    Word("!$ACC END ATOMIC\n");
+    EndOpenACC();
+  }
+  void Unparse(const AccAtomicRead &x) {
+    BeginOpenACC();
+    Word("!$ACC ATOMIC READ");
+    Put("\n");
+    EndOpenACC();
+    Walk(std::get<Statement<AssignmentStmt>>(x.t));
+    BeginOpenACC();
+    Walk(std::get<std::optional<AccEndAtomic>>(x.t), "!$ACC END ATOMIC\n");
+    EndOpenACC();
+  }
+  void Unparse(const AccAtomicWrite &x) {
+    BeginOpenACC();
+    Word("!$ACC ATOMIC WRITE");
+    Put("\n");
+    EndOpenACC();
+    Walk(std::get<Statement<AssignmentStmt>>(x.t));
+    BeginOpenACC();
+    Walk(std::get<std::optional<AccEndAtomic>>(x.t), "!$ACC END ATOMIC\n");
+    EndOpenACC();
+  }
+  void Unparse(const AccAtomicUpdate &x) {
+    BeginOpenACC();
+    Word("!$ACC ATOMIC UPDATE");
+    Put("\n");
+    EndOpenACC();
+    Walk(std::get<Statement<AssignmentStmt>>(x.t));
+    BeginOpenACC();
+    Walk(std::get<std::optional<AccEndAtomic>>(x.t), "!$ACC END ATOMIC\n");
+    EndOpenACC();
+  }
+  void Unparse(const llvm::acc::Directive &x) {
+    Word(llvm::acc::getOpenACCDirectiveName(x).str());
+  }
+  void Before(const AccClause::Auto &) { Word("AUTO"); }
+  void Before(const AccClause::Capture &) { Word("CAPTURE"); }
+  void Before(const AccClause::Finalize &) { Word("FINALIZE"); }
+  void Before(const AccClause::IfPresent &) { Word("IF_PRESENT"); }
+  void Before(const AccClause::Independent &) { Word("INDEPENDENT"); }
+  void Before(const AccClause::NoHost &) { Word("NOHOST"); }
+  void Before(const AccClause::Read &) { Word("READ"); }
+  void Before(const AccClause::Seq &) { Word("SEQ"); }
+  void Before(const AccClause::Write &) { Word("WRITE"); }
+  void Before(const AccClause::Unknown &) { Word("UNKNOWN"); }
+  void Unparse(const AccClause::Attach &x) {
+    Word("ATTACH");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::Bind &x) {
+    Word("BIND");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::Collapse &x) {
+    Word("COLLAPSE");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::Copy &x) {
+    Word("COPY");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::Copyin &x) {
+    Word("COPYIN");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::Copyout &x) {
+    Word("COPYOUT");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::Create &x) {
+    Word("CREATE");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::Default &x) {
+    Word("DEFAULT");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::Delete &x) {
+    Word("DELETE");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::Detach &x) {
+    Word("DETACH");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::Device &x) {
+    Word("DEVICE");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::DevicePtr &x) {
+    Word("DEVICEPTR");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::DeviceResident &x) {
+    Word("DEVICE_RESIDENT");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::FirstPrivate &x) {
+    Word("FIRSTPRIVATE");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::Host &x) {
+    Word("HOST");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::If &x) {
+    Word("IF");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::Link &x) {
+    Word("LINK");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::NumGangs &x) {
+    Word("NUM_GANGS");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::NumWorkers &x) {
+    Word("NUM_WORKERS");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::Present &x) {
+    Word("PRESENT");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::Private &x) {
+    Word("PRIVATE");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::Reduction &x) {
+    Word("REDUCTION");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::VectorLength &x) {
+    Word("VECTOR_LENGTH");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::Async &x) {
+    Word("ASYNC");
+    Walk("(", x.v, ")");
+  }
+  void Unparse(const AccClause::DefaultAsync &x) {
+    Word("DEFAULT_ASYNC");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::DeviceNum &x) {
+    Word("DEVICE_NUM");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::Gang &x) {
+    Word("GANG");
+    Walk("(", x.v, ")");
+  }
+  void Unparse(const AccClause::NoCreate &x) {
+    Word("NO_CREATE");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::UseDevice &x) {
+    Word("USE_DEVICE");
+    Put("(");
+    Walk(x.v);
+    Put(")");
+  }
+  void Unparse(const AccClause::Self &x) {
+    Word("SELF");
+    Walk("(", x.v, ")");
+  }
+  void Unparse(const AccClause::Vector &x) {
+    Word("VECTOR");
+    Walk("(", x.v, ")");
+  }
+  void Unparse(const AccClause::Wait &x) {
+    Word("WAIT");
+    Walk("(", x.v, ")");
+  }
+  void Unparse(const AccClause::Worker &x) {
+    Word("WORKER");
+    Walk("(", x.v, ")");
+  }
+  void Unparse(const AccClause::DeviceType &x) {
+    Word("DEVICE_TYPE");
+    Put("(");
+    if (x.v.has_value())
+      Walk(x.v);
+    else
+      Put("*");
+    Put(")");
+  }
+  void Unparse(const AccObjectListWithModifier &x) {
+    Walk(std::get<std::optional<AccDataModifier>>(x.t), ":");
+    Walk(std::get<AccObjectList>(x.t));
+  }
+  void Unparse(const AccDataModifier::Modifier &x) {
+    Word(AccDataModifier::EnumToString(x));
+  }
+  void Unparse(const AccDefaultClause &x) {
+    switch (x.v) {
+    case AccDefaultClause::Arg::None:
+      Put("NONE");
+      break;
+    case AccDefaultClause::Arg::Present:
+      Put("PRESENT");
+      break;
+    }
+  }
+  void Unparse(const AccClauseList &x) { Walk(" ", x.v, " "); }
+  void Unparse(const AccGangArgument &x) {
+    Walk("NUM:", std::get<std::optional<ScalarIntExpr>>(x.t));
+    Walk(", STATIC:", std::get<std::optional<AccSizeExpr>>(x.t));
+  }
+  void Unparse(const OpenACCBlockConstruct &x) {
+    BeginOpenACC();
+    Word("!$ACC ");
+    Walk(std::get<AccBeginBlockDirective>(x.t));
+    Put("\n");
+    EndOpenACC();
+    Walk(std::get<Block>(x.t), "");
+    BeginOpenACC();
+    Word("!$ACC END ");
+    Walk(std::get<AccEndBlockDirective>(x.t));
+    Put("\n");
+    EndOpenACC();
+  }
+  void Unparse(const OpenACCLoopConstruct &x) {
+    BeginOpenACC();
+    Word("!$ACC ");
+    Walk(std::get<AccBeginLoopDirective>(x.t));
+    Put("\n");
+    EndOpenACC();
+    Walk(std::get<std::optional<DoConstruct>>(x.t));
+  }
+  void Unparse(const AccBeginLoopDirective &x) {
+    Walk(std::get<AccLoopDirective>(x.t));
+    Walk(std::get<AccClauseList>(x.t));
+  }
+  void Unparse(const OpenACCStandaloneConstruct &x) {
+    BeginOpenACC();
+    Word("!$ACC ");
+    Walk(std::get<AccStandaloneDirective>(x.t));
+    Walk(std::get<AccClauseList>(x.t));
+    Put("\n");
+    EndOpenACC();
+  }
+  void Unparse(const OpenACCStandaloneDeclarativeConstruct &x) {
+    BeginOpenACC();
+    Word("!$ACC ");
+    Walk(std::get<AccDeclarativeDirective>(x.t));
+    Walk(std::get<AccClauseList>(x.t));
+    Put("\n");
+    EndOpenACC();
+  }
+  void Unparse(const OpenACCCombinedConstruct &x) {
+    BeginOpenACC();
+    Word("!$ACC ");
+    Walk(std::get<AccBeginCombinedDirective>(x.t));
+    Put("\n");
+    EndOpenACC();
+    Walk(std::get<Block>(x.t), "");
+    BeginOpenACC();
+    Word("!$ACC END ");
+    Walk(std::get<std::optional<AccEndCombinedDirective>>(x.t));
+    Put("\n");
+    EndOpenACC();
+  }
+  void Unparse(const OpenACCRoutineConstruct &x) {
+    BeginOpenACC();
+    Word("!$ACC ROUTINE");
+    Walk("(", std::get<std::optional<Name>>(x.t), ")");
+    Walk(std::get<AccClauseList>(x.t));
+    Put("\n");
+    EndOpenACC();
+  }
+  void Unparse(const AccObject &x) {
+    std::visit(common::visitors{
+                   [&](const Designator &y) { Walk(y); },
+                   [&](const Name &y) { Put("/"), Walk(y), Put("/"); },
+               },
+        x.u);
+  }
+  void Unparse(const AccObjectList &x) { Walk(x.v, ","); }
+  void Unparse(const AccObjectListWithReduction &x) {
+    Walk(std::get<AccReductionOperator>(x.t));
+    Put(":");
+    Walk(std::get<AccObjectList>(x.t));
+  }
+  void Unparse(const OpenACCCacheConstruct &x) {
+    BeginOpenACC();
+    Word("!$ACC ");
+    Word("CACHE(");
+    Walk(std::get<AccObjectListWithModifier>(x.t));
+    Put(")");
+    Put("\n");
+    EndOpenACC();
+  }
+  void Unparse(const OpenACCWaitConstruct &x) {
+    BeginOpenACC();
+    Word("!$ACC ");
+    Word("WAIT(");
+    Walk(std::get<std::optional<AccWaitArgument>>(x.t));
+    Walk(std::get<AccClauseList>(x.t));
+    Put(")");
+    Put("\n");
+    EndOpenACC();
+  }
+
   // OpenMP Clauses & Directives
   void Unparse(const OmpObject &x) {
     std::visit(common::visitors{
                    [&](const Designator &y) { Walk(y); },
                    [&](const Name &y) { Put("/"), Walk(y), Put("/"); },
                },
         x.u);
   }
private:
   void Word(const std::string &);
   void Indent() { indent_ += indentationAmount_; }
   void Outdent() {
     CHECK(indent_ >= indentationAmount_);
     indent_ -= indentationAmount_;
   }
   void BeginOpenMP() { openmpDirective_ = true; }
   void EndOpenMP() { openmpDirective_ = false; }
+  void BeginOpenACC() { openaccDirective_ = true; }
+  void EndOpenACC() { openaccDirective_ = false; }
 
   // Call back to the traversal framework.
   template <typename T> void Walk(const T &x) {
     Fortran::parser::Walk(x, *this);
   }
 
   // Traverse a std::optional<> value.  Emit a prefix and/or a suffix string
   // only when it contains a value.
private:
   llvm::raw_ostream &out_;
   int indent_{0};
   const int indentationAmount_{1};
   int column_{1};
   const int maxColumns_{80};
   std::set<CharBlock> structureComponents_;
   Encoding encoding_{Encoding::UTF_8};
   bool capitalizeKeywords_{true};
+  bool openaccDirective_{false};
   bool openmpDirective_{false};
   bool backslashEscapes_{false};
   preStatementType *preStatement_{nullptr};
   AnalyzedObjectsAsFortran *asFortran_{nullptr};
 };
 
 void UnparseVisitor::Put(char ch) {
   int sav = indent_;
-  if (openmpDirective_) {
+  if (openmpDirective_ || openaccDirective_) {
     indent_ = 0;
   }
   if (column_ <= 1) {
     if (ch == '\n') {
       return;
     }
     for (int j{0}; j < indent_; ++j) {
       out_ << ' ';
     }
     column_ = indent_ + 2;
   } else if (ch == '\n') {
     column_ = 1;
   } else if (++column_ >= maxColumns_) {
     out_ << "&\n";
     for (int j{0}; j < indent_; ++j) {
       out_ << ' ';
     }
     if (openmpDirective_) {
       out_ << "!$OMP&";
       column_ = 8;
+    } else if (openaccDirective_) {
+      out_ << "!$ACC&";
+      column_ = 8;
     } else {
       out_ << '&';
       column_ = indent_ + 3;
     }
   }
   out_ << ch;
-  if (openmpDirective_) {
+  if (openmpDirective_ || openaccDirective_) {
     indent_ = sav;
   }
 }
 
 void UnparseVisitor::Put(const char *str) {
   for (; *str != '\0'; ++str) {
     Put(*str);
   }

flang/lib/Semantics/resolve-names.cpp

static bool NeedsExplicitType(const Symbol &symbol) {
   }
 }
 
 bool ResolveNamesVisitor::Pre(const parser::SpecificationPart &x) {
   Walk(std::get<0>(x.t));
   Walk(std::get<1>(x.t));
   Walk(std::get<2>(x.t));
   Walk(std::get<3>(x.t));
-  const std::list<parser::DeclarationConstruct> &decls{std::get<4>(x.t)};
+  Walk(std::get<4>(x.t));
+  const std::list<parser::DeclarationConstruct> &decls{std::get<5>(x.t)};
   for (const auto &decl : decls) {
     if (const auto *spec{
             std::get_if<parser::SpecificationConstruct>(&decl.u)}) {
       PreSpecificationConstruct(*spec);
     }
   }
   Walk(decls);
   FinishSpecificationPart(decls);

flang/test/Semantics/acc-validity.f90

+! RUN: %S/test_errors.sh %s %t %f18 -fopenacc
+
+! Check OpenACC clause validity for the following construct and directive:
+!   2.6.5 Data
+!   2.5.1 Parallel
+!   2.5.2 Kernels
+!   2.5.3 Serial
+!   2.15.1 Routine
+!   2.11 Parallel Loop
+!   2.11 Kernels Loop
+!   2.11 Serial Loop
+
+program openacc_clause_validity
+
+  implicit none
+
+  integer :: i, j
+  integer :: N = 256
+
+  !$acc declare
+  real(8) :: a(256)
+
+  !$acc enter data
+
+  !$acc enter data copyin(zero: i)
+
+  !$acc enter data create(readonly: i)
+
+  !$acc data copyout(readonly: i)
+  !$acc end data
+
+  !$acc enter data copyin(i) copyout(i)
+
+  !$acc data copy(i) if(.true.) if(.true.)
+  !$acc end data
+
+  !$acc exit data
+
+  !$acc host_data
+  !$acc end host_data
+
+  !$acc set
+
+  !$acc data
+  !$acc end data
+
+  !$acc data copyin(i)
+  !$acc end data
+
+  !$acc data copyin(i)
+
+  !$acc end parallel
+
+  !$acc update device(i) device_type(*) async
+
+
+  !$acc update device(i) device_type(*) if(.TRUE.)
+
+  !$acc parallel
+
+  !$acc loop seq independent
+  do i = 1, N
+    a(i) = 3.14
+  end do
+  !$acc end parallel
+
+  !$acc parallel device_type(*) num_gangs(2)
+  !$acc loop
+  do i = 1, N
+    a(i) = 3.14
+  end do
+  !$acc end parallel
+
+  !$acc parallel
+
+  !$acc loop collapse(-1)
+  do i = 1, N
+    do j = 1, N
+      a(i) = 3.14 + j
+    end do
+  end do
+  !$acc end parallel
+
+  !$acc parallel
+
+  !$acc loop device_type(*) private(i)
+  do i = 1, N
+    a(i) = 3.14
+  end do
+  !$acc end parallel
+
+  !$acc parallel
+
+  !$acc loop gang seq
+  do i = 1, N
+    a(i) = 3.14
+  end do
+  !$acc end parallel
+
+
+  !$acc parallel device_type(*) if(.TRUE.)
+  !$acc loop
+  do i = 1, N
+    a(i) = 3.14
+  end do
+  !$acc end parallel
+
+
+  !$acc parallel loop device_type(*) if(.TRUE.)
+  do i = 1, N
+    a(i) = 3.14
+  end do
+  !$acc end parallel loop
+
+  !$acc kernels device_type(*) async
+  do i = 1, N
+    a(i) = 3.14
+  end do
+  !$acc end kernels
+
+
+  !$acc kernels device_type(*) if(.TRUE.)
+  do i = 1, N
+    a(i) = 3.14
+  end do
+  !$acc end kernels
+
+
+  !$acc kernels loop device_type(*) if(.TRUE.)
+  do i = 1, N
+    a(i) = 3.14
+  end do
+  !$acc end kernels loop
+
+  !$acc serial device_type(*) async
+  do i = 1, N
+    a(i) = 3.14
+  end do
+  !$acc end serial
+
+
+  !$acc serial device_type(*) if(.TRUE.)
+  do i = 1, N
+    a(i) = 3.14
+  end do
+  !$acc end serial
+
+
+  !$acc serial loop device_type(*) if(.TRUE.)
+  do i = 1, N
+    a(i) = 3.14
+  end do
+  !$acc end serial loop
+
+ contains
+
+   subroutine sub1(a)
+     real :: a(:)
+
+     !$acc routine
+   end subroutine sub1
+
+   subroutine sub2(a)
+     real :: a(:)
+
+     !$acc routine seq device_type(*) nohost
+   end subroutine sub2
+
+end program openacc_clause_validity
 No newline at end of file

flang/tools/f18-parse-demo/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
+  FrontendOpenACC
   FrontendOpenMP
   )
 
 add_flang_tool(f18-parse-demo
   f18-parse-demo.cpp
   stub-evaluate.cpp
 )
 
 target_link_libraries(f18-parse-demo
   PRIVATE
   FortranCommon
   FortranParser
   )

flang/tools/f18/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
+  FrontendOpenACC
   FrontendOpenMP
   Support
   )
 add_flang_tool(f18
   dump.cpp
   f18.cpp
   )
 

 endforeach()
 
 add_custom_target(module_files ALL DEPENDS ${MODULE_FILES})
 
 install(TARGETS f18 DESTINATION bin)
 
 set(FLANG_INTRINSIC_MODULES_DIR ${FLANG_BINARY_DIR}/include/flang)
 configure_file(${CMAKE_CURRENT_SOURCE_DIR}/flang.sh.in ${CMAKE_BINARY_DIR}/tools/flang/bin/flang @ONLY)
-file(COPY ${CMAKE_BINARY_DIR}/tools/flang/bin/flang DESTINATION ${CMAKE_BINARY_DIR}/bin FILE_PERMISSIONS OWNER_EXECUTE OWNER_READ OWNER_WRITE) 
+file(COPY ${CMAKE_BINARY_DIR}/tools/flang/bin/flang DESTINATION ${CMAKE_BINARY_DIR}/bin FILE_PERMISSIONS OWNER_EXECUTE OWNER_READ OWNER_WRITE)
 # The flang script to be installed needs a different path to the headers.
 set(FLANG_INTRINSIC_MODULES_DIR ${CMAKE_INSTALL_PREFIX}/include/flang)
 configure_file(${CMAKE_CURRENT_SOURCE_DIR}/flang.sh.in ${FLANG_BINARY_DIR}/bin/flang-install.sh @ONLY)
 
 install(PROGRAMS ${FLANG_BINARY_DIR}/bin/flang-install.sh DESTINATION bin RENAME flang PERMISSIONS OWNER_EXECUTE OWNER_READ OWNER_WRITE)

flang/tools/f18/f18.cpp

if (arg.empty()) {
       options.features.Enable(
           Fortran::common::LanguageFeature::BackslashEscapes, false);
     } else if (arg == "-Mnobackslash") {
       options.features.Enable(
           Fortran::common::LanguageFeature::BackslashEscapes, true);
     } else if (arg == "-Mstandard" || arg == "-std=f95" ||
         arg == "-std=f2003" || arg == "-std=f2008" || arg == "-std=legacy") {
       driver.warnOnNonstandardUsage = true;
+    } else if (arg == "-fopenacc") {
+      options.features.Enable(Fortran::common::LanguageFeature::OpenACC);
+      options.predefinitions.emplace_back("_OPENACC", "201911");
     } else if (arg == "-fopenmp") {
       options.features.Enable(Fortran::common::LanguageFeature::OpenMP);
       options.predefinitions.emplace_back("_OPENMP", "201511");
     } else if (arg == "-Werror") {
       driver.warningsAreErrors = true;
     } else if (arg == "-ed") {
       options.features.Enable(Fortran::common::LanguageFeature::OldDebugLines);
     } else if (arg == "-E") {

llvm/include/llvm/CMakeLists.txt

 add_subdirectory(IR)
 add_subdirectory(Support)
-add_subdirectory(Frontend/OpenMP)
+add_subdirectory(Frontend)
 
 # If we're doing an out-of-tree build, copy a module map for generated
 # header files into the build area.
 if (NOT "${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_BINARY_DIR}")
   configure_file(module.modulemap.build module.modulemap COPYONLY)
 endif (NOT "${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_BINARY_DIR}")

llvm/include/llvm/Frontend/CMakeLists.txt

+add_subdirectory(OpenACC)
+add_subdirectory(OpenMP)

llvm/include/llvm/Frontend/Directive/DirectiveBase.td

class Clause<string c> {
   string name = c;
 
   // Define an alternative name return in get<LanguageName>ClauseName function.
   string alternativeName = "";
 
   // Optional class holding value of the clause in clang AST.
   string clangClass = ?;
 
+  // Optional class holding value of the clause in flang AST.
+  string flangClass = ?;
+
   // Is clause implicit? If clause is set as implicit, the default kind will
   // be return in get<LanguageName>ClauseKind instead of their own kind.
   bit isImplicit = 0;
 
   // Set directive used by default when unknown. Function returning the kind
   // of enumeration will use this clause as the default.
   bit isDefault = 0;
 }

llvm/include/llvm/Frontend/OpenACC/ACC.td

+//===-- ACC.td - OpenACC directive definition file ---------*- tablegen -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This is the definition file for OpenACC directives and clauses.
+//
+//===----------------------------------------------------------------------===//
+
+include "llvm/Frontend/Directive/DirectiveBase.td"
+
+//===----------------------------------------------------------------------===//
+// Definition of general OpenACC information
+//===----------------------------------------------------------------------===//
+
+def OpenACC : DirectiveLanguage {
+  let name = "OpenACC";
+  let cppNamespace = "acc"; // final namespace will be llvm::acc
+  let directivePrefix = "ACCD_";
+  let clausePrefix = "ACCC_";
+  let makeEnumAvailableInNamespace = 1;
+  let enableBitmaskEnumInNamespace = 1;
+  let includeHeader = "llvm/Frontend/OpenACC/ACC.h.inc";
+  let clauseEnumSetClass = "AccClauseSet";
+}
+
+//===----------------------------------------------------------------------===//
+// Definition of OpenACC clauses
+//===----------------------------------------------------------------------===//
+
+// 2.9.6
+def ACCC_Auto : Clause<"auto"> {}
+
+// 2.16.1
+def ACCC_Async : Clause<"async"> {
+  let flangClass = "std::optional<ScalarIntExpr>";
+}
+
+// 2.7.11
+def ACCC_Attach : Clause<"attach"> {
+  let flangClass = "AccObjectList";
+}
+
+// 2.15.1
+def ACCC_Bind : Clause<"bind"> {
+  let flangClass = "Name";
+}
+
+// 2.12
+def ACCC_Capture : Clause<"capture"> {
+}
+
+// 2.9.1
+def ACCC_Collapse : Clause<"collapse"> {
+  let flangClass = "ScalarIntConstantExpr";
+}
+
+// 2.7.5
+def ACCC_Copy : Clause<"copy"> {
+  let flangClass = "AccObjectList";
+}
+// 2.7.6
+def ACCC_Copyin : Clause<"copyin"> {
+  let flangClass = "AccObjectListWithModifier";
+}
+
+// 2.7.7
+def ACCC_Copyout : Clause<"copyout"> {
+  let flangClass = "AccObjectListWithModifier";
+}
+
+// 2.7.8
+def ACCC_Create : Clause<"create"> {
+  let flangClass = "AccObjectListWithModifier";
+}
+
+// 2.5.14
+def ACCC_Default : Clause<"default"> {
+  let flangClass = "AccDefaultClause";
+}
+
+// 2.4.12
+def ACCC_DefaultAsync : Clause<"default_async"> {
+  let flangClass = "ScalarIntExpr";
+}
+
+// 2.7.10
+def ACCC_Delete : Clause<"delete"> {
+  let flangClass = "AccObjectList";
+}
+
+// 2.7.12
+def ACCC_Detach : Clause<"detach"> {
+  let flangClass = "AccObjectList";
+}
+
+// 2.14.4
+def ACCC_Device : Clause<"device"> {
+  let flangClass = "AccObjectList";
+}
+
+// 2.14.1
+def ACCC_DeviceNum : Clause<"devicenum">  {
+  let flangClass = "ScalarIntConstantExpr";
+}
+
+// 2.7.3
+def ACCC_DevicePtr : Clause<"deviceptr"> {
+  let flangClass = "AccObjectList";
+}
+
+// 2.13
+def ACCC_DeviceResident : Clause<"device_resident"> {
+  let flangClass = "AccObjectList";
+}
+
+// 2.4
+def ACCC_DeviceType : Clause<"device_type"> {
+  // (DeviceType, "*"
+  let flangClass = "std::optional<std::list<Name>>";
+}
+
+// 2.6.6
+def ACCC_Finalize : Clause<"finalize"> {}
+
+// 2.5.12
+def ACCC_FirstPrivate : Clause<"firstprivate"> {
+  let flangClass = "AccObjectList";
+}
+
+// 2.9.2
+def ACCC_Gang : Clause<"gang"> {
+  let flangClass = "std::optional<AccGangArgument>";
+}
+
+// 2.14.4
+def ACCC_Host : Clause<"host"> {
+  let flangClass = "AccObjectList";
+}
+
+// 2.5.4
+def ACCC_If : Clause <"if"> {
+  let flangClass = "ScalarLogicalExpr";
+}
+
+// 2.14.4
+def ACCC_IfPresent : Clause<"if_present"> {}
+
+// 2.9.9
+def ACCC_Independent : Clause<"independent"> {}
+
+// 2.13
+def ACCC_Link : Clause<"link"> {
+  let flangClass = "AccObjectList";
+}
+
+// 2.7.9
+def ACCC_NoCreate : Clause<"no_create"> {
+  let flangClass = "AccObjectList";
+}
+
+// 2.15.1
+def ACCC_NoHost : Clause<"nohost"> {}
+
+// 2.5.8
+def ACCC_NumGangs : Clause<"num_gangs"> {
+  let flangClass = "ScalarIntExpr";
+}
+
+// 2.5.9
+def ACCC_NumWorkers : Clause<"num_workers"> {
+  let flangClass = "ScalarIntExpr";
+}
+
+// 2.7.4
+def ACCC_Present : Clause<"present"> {
+  let flangClass = "AccObjectList";
+}
+
+// 2.5.11
+def ACCC_Private : Clause<"private"> {
+  let flangClass = "AccObjectList";
+}
+
+// 2.9.7
+def ACCC_Tile : Clause <"tile"> {
+  let flangClass = "AccSizeExprList";
+}
+
+// 2.8.1
+def ACCC_UseDevice : Clause <"use_device"> {
+  let flangClass = "AccObjectList";
+}
+
+// 2.12
+def ACCC_Read : Clause<"read"> {}
+
+// 2.5.13
+def ACCC_Reduction : Clause<"reduction"> {
+  let flangClass = "AccObjectListWithReduction";
+}
+
+// 2.5.5
+def ACCC_Self : Clause<"self"> {
+  let flangClass = "std::optional<ScalarLogicalExpr>";
+}
+
+// 2.9.5
+def ACCC_Seq : Clause<"seq"> {}
+
+// 2.9.4
+def ACCC_Vector : Clause<"vector"> {
+  let flangClass = "std::optional<ScalarIntExpr>";
+}
+
+// 2.5.10
+def ACCC_VectorLength : Clause<"vector_length"> {
+  let flangClass = "ScalarIntExpr";
+}
+
+// 2.16.2
+def ACCC_Wait : Clause<"wait"> {
+  let flangClass = "std::optional<AccWaitArgument>";
+}
+
+// 2.9.3
+def ACCC_Worker: Clause<"worker"> {
+  let flangClass = "std::optional<ScalarIntExpr>";
+}
+
+// 2.12
+def ACCC_Write : Clause<"write"> {}
+
+def ACCC_Unknown : Clause<"unknown"> {
+  let isDefault = 1;
+}
+
+//===----------------------------------------------------------------------===//
+// Definition of OpenACC directives
+//===----------------------------------------------------------------------===//
+
+// 2.12
+def ACC_Atomic : Directive<"atomic"> {}
+
+// 2.6.5
+def ACC_Data : Directive<"data"> {
+  let allowedOnceClauses = [
+    VersionedClause<ACCC_If>
+  ];
+  let requiredClauses = [
+    VersionedClause<ACCC_Attach>,
+    VersionedClause<ACCC_Copy>,
+    VersionedClause<ACCC_Copyin>,
+    VersionedClause<ACCC_Copyout>,
+    VersionedClause<ACCC_Create>,
+    VersionedClause<ACCC_Default>,
+    VersionedClause<ACCC_DevicePtr>,
+    VersionedClause<ACCC_NoCreate>,
+    VersionedClause<ACCC_Present>
+  ];
+}
+
+// 2.13
+def ACC_Declare : Directive<"declare"> {
+  let allowedClauses = [
+    VersionedClause<ACCC_Copy>,
+    VersionedClause<ACCC_Copyin>,
+    VersionedClause<ACCC_Copyout>,
+    VersionedClause<ACCC_Create>,
+    VersionedClause<ACCC_Present>,
+    VersionedClause<ACCC_DevicePtr>,
+    VersionedClause<ACCC_DeviceResident>,
+    VersionedClause<ACCC_Link>
+  ];
+}
+
+// 2.5.2
+def ACC_Kernels : Directive<"kernels"> {
+  let allowedClauses = [
+    VersionedClause<ACCC_Attach>,
+    VersionedClause<ACCC_Copy>,
+    VersionedClause<ACCC_Copyin>,
+    VersionedClause<ACCC_Copyout>,
+    VersionedClause<ACCC_Create>,
+    VersionedClause<ACCC_DeviceType>,
+    VersionedClause<ACCC_NoCreate>,
+    VersionedClause<ACCC_Present>,
+    VersionedClause<ACCC_DevicePtr>
+  ];
+  let allowedOnceClauses = [
+    VersionedClause<ACCC_Async>,
+    VersionedClause<ACCC_Default>,
+    VersionedClause<ACCC_If>,
+    VersionedClause<ACCC_NumGangs>,
+    VersionedClause<ACCC_NumWorkers>,
+    VersionedClause<ACCC_Self>,
+    VersionedClause<ACCC_VectorLength>,
+    VersionedClause<ACCC_Wait>
+  ];
+}
+
+// 2.5.1
+def ACC_Parallel : Directive<"parallel"> {
+  let allowedClauses = [
+    VersionedClause<ACCC_Attach>,
+    VersionedClause<ACCC_Copy>,
+    VersionedClause<ACCC_Copyin>,
+    VersionedClause<ACCC_Copyout>,
+    VersionedClause<ACCC_Create>,
+    VersionedClause<ACCC_DevicePtr>,
+    VersionedClause<ACCC_DeviceType>,
+    VersionedClause<ACCC_NoCreate>,
+    VersionedClause<ACCC_Present>,
+    VersionedClause<ACCC_Private>,
+    VersionedClause<ACCC_FirstPrivate>,
+    VersionedClause<ACCC_Wait>
+  ];
+  let allowedOnceClauses = [
+    VersionedClause<ACCC_Async>,
+    VersionedClause<ACCC_Default>,
+    VersionedClause<ACCC_If>,
+    VersionedClause<ACCC_NumGangs>,
+    VersionedClause<ACCC_NumWorkers>,
+    VersionedClause<ACCC_Reduction>,
+    VersionedClause<ACCC_Self>,
+    VersionedClause<ACCC_VectorLength>
+  ];
+}
+
+// 2.5.3
+def ACC_Serial : Directive<"serial"> {
+  let allowedClauses = [
+    VersionedClause<ACCC_Attach>,
+    VersionedClause<ACCC_Copy>,
+    VersionedClause<ACCC_Copyin>,
+    VersionedClause<ACCC_Copyout>,
+    VersionedClause<ACCC_Create>,
+    VersionedClause<ACCC_DevicePtr>,
+    VersionedClause<ACCC_DeviceType>,
+    VersionedClause<ACCC_FirstPrivate>,
+    VersionedClause<ACCC_NoCreate>,
+    VersionedClause<ACCC_Present>,
+    VersionedClause<ACCC_Private>,
+    VersionedClause<ACCC_Wait>
+  ];
+  let allowedOnceClauses = [
+    VersionedClause<ACCC_Async>,
+    VersionedClause<ACCC_Default>,
+    VersionedClause<ACCC_If>,
+    VersionedClause<ACCC_Reduction>,
+    VersionedClause<ACCC_Self>
+  ];
+}
+
+// 2.9
+def ACC_Loop : Directive<"loop"> {
+  let allowedClauses = [
+    VersionedClause<ACCC_DeviceType>,
+    VersionedClause<ACCC_Private>
+  ];
+  let allowedOnceClauses = [
+    VersionedClause<ACCC_Collapse>,
+    VersionedClause<ACCC_Gang>,
+    VersionedClause<ACCC_Reduction>,
+    VersionedClause<ACCC_Tile>,
+    VersionedClause<ACCC_Vector>,
+    VersionedClause<ACCC_Worker>
+  ];
+  let allowedExclusiveClauses = [
+    VersionedClause<ACCC_Auto>,
+    VersionedClause<ACCC_Independent>,
+    VersionedClause<ACCC_Seq>
+  ];
+}
+
+// 2.10
+def ACC_Cache : Directive<"cache"> {}
+
+// 2.14.1
+def ACC_Init : Directive<"init"> {
+  let allowedOnceClauses = [
+    VersionedClause<ACCC_DeviceNum>,
+    VersionedClause<ACCC_DeviceType>,
+    VersionedClause<ACCC_If>
+  ];
+}
+
+// 2.15.1
+def ACC_Routine : Directive<"routine"> {
+  let allowedOnceClauses = [
+    VersionedClause<ACCC_Bind>,
+    VersionedClause<ACCC_DeviceType>,
+    VersionedClause<ACCC_NoHost>
+  ];
+  let requiredClauses = [
+    VersionedClause<ACCC_Gang>,
+    VersionedClause<ACCC_Seq>,
+    VersionedClause<ACCC_Vector>,
+    VersionedClause<ACCC_Worker>
+  ];
+}
+
+// 2.14.3
+def ACC_Set : Directive<"set"> {
+  let allowedOnceClauses = [
+    VersionedClause<ACCC_If>
+  ];
+  let requiredClauses = [
+    VersionedClause<ACCC_DefaultAsync>,
+    VersionedClause<ACCC_DeviceNum>,
+    VersionedClause<ACCC_DeviceType>
+  ];
+}
+
+// 2.14.2
+def ACC_Shutdown : Directive<"shutdown"> {
+  let allowedOnceClauses = [
+    VersionedClause<ACCC_DeviceNum>,
+    VersionedClause<ACCC_DeviceType>,
+    VersionedClause<ACCC_If>
+  ];
+}
+
+// 2.14.4
+def ACC_Update : Directive<"update"> {
+  let allowedClauses = [
+    VersionedClause<ACCC_DeviceType>,
+    VersionedClause<ACCC_Wait>
+  ];
+  let allowedOnceClauses = [
+    VersionedClause<ACCC_Async>,
+    VersionedClause<ACCC_If>,
+    VersionedClause<ACCC_IfPresent>
+  ];
+  let requiredClauses = [
+    VersionedClause<ACCC_Device>,
+    VersionedClause<ACCC_Host>,
+    VersionedClause<ACCC_Self>
+  ];
+}
+
+// 2.16.3
+def ACC_Wait : Directive<"wait"> {
+  let allowedOnceClauses = [
+    VersionedClause<ACCC_Async>,
+    VersionedClause<ACCC_If>
+  ];
+}
+
+// 2.14.6
+def ACC_EnterData : Directive<"enter data"> {
+  let allowedOnceClauses = [
+    VersionedClause<ACCC_Async>,
+    VersionedClause<ACCC_If>,
+    VersionedClause<ACCC_Wait>
+  ];
+  let requiredClauses = [
+    VersionedClause<ACCC_Attach>,
+    VersionedClause<ACCC_Create>,
+    VersionedClause<ACCC_Copyin>
+  ];
+}
+
+// 2.14.7
+def ACC_ExitData : Directive<"exit data"> {
+  let allowedClauses = [
+    VersionedClause<ACCC_Async>,
+    VersionedClause<ACCC_If>,
+    VersionedClause<ACCC_Wait>,
+    VersionedClause<ACCC_Finalize>
+  ];
+  let requiredClauses = [
+    VersionedClause<ACCC_Copyout>,
+    VersionedClause<ACCC_Delete>,
+    VersionedClause<ACCC_Detach>
+  ];
+}
+def ACC_HostData : Directive<"host_data"> {
+  let allowedClauses = [
+    VersionedClause<ACCC_If>,
+    VersionedClause<ACCC_IfPresent>
+  ];
+  let requiredClauses = [
+    VersionedClause<ACCC_UseDevice>
+  ];
+}
+
+// 2.11
+def ACC_KernelsLoop : Directive<"kernels loop"> {
+  let allowedClauses = [
+    VersionedClause<ACCC_Copy>,
+    VersionedClause<ACCC_Copyin>,
+    VersionedClause<ACCC_Copyout>,
+    VersionedClause<ACCC_Create>,
+    VersionedClause<ACCC_DeviceType>,
+    VersionedClause<ACCC_NoCreate>,
+    VersionedClause<ACCC_Present>,
+    VersionedClause<ACCC_Private>,
+    VersionedClause<ACCC_DevicePtr>,
+    VersionedClause<ACCC_Attach>
+  ];
+  let allowedOnceClauses = [
+    VersionedClause<ACCC_Async>,
+    VersionedClause<ACCC_Collapse>,
+    VersionedClause<ACCC_Default>,
+    VersionedClause<ACCC_Gang>,
+    VersionedClause<ACCC_If>,
+    VersionedClause<ACCC_Independent>,
+    VersionedClause<ACCC_NumGangs>,
+    VersionedClause<ACCC_NumWorkers>,
+    VersionedClause<ACCC_Reduction>,
+    VersionedClause<ACCC_Self>,
+    VersionedClause<ACCC_Tile>,
+    VersionedClause<ACCC_Vector>,
+    VersionedClause<ACCC_VectorLength>,
+    VersionedClause<ACCC_Wait>,
+    VersionedClause<ACCC_Worker>
+  ];
+  let allowedExclusiveClauses = [
+    VersionedClause<ACCC_Auto>,
+    VersionedClause<ACCC_Independent>,
+    VersionedClause<ACCC_Seq>
+  ];
+}
+
+// 2.11
+def ACC_ParallelLoop : Directive<"parallel loop"> {
+  let allowedClauses = [
+    VersionedClause<ACCC_Attach>,
+    VersionedClause<ACCC_Copy>,
+    VersionedClause<ACCC_Copyin>,
+    VersionedClause<ACCC_Copyout>,
+    VersionedClause<ACCC_Create>,
+    VersionedClause<ACCC_DevicePtr>,
+    VersionedClause<ACCC_DeviceType>,
+    VersionedClause<ACCC_FirstPrivate>,
+    VersionedClause<ACCC_NoCreate>,
+    VersionedClause<ACCC_Present>,
+    VersionedClause<ACCC_Private>,
+    VersionedClause<ACCC_Tile>,
+    VersionedClause<ACCC_Wait>
+  ];
+  let allowedOnceClauses = [
+    VersionedClause<ACCC_Async>,
+    VersionedClause<ACCC_Collapse>,
+    VersionedClause<ACCC_Default>,
+    VersionedClause<ACCC_Gang>,
+    VersionedClause<ACCC_If>,
+    VersionedClause<ACCC_NumGangs>,
+    VersionedClause<ACCC_NumWorkers>,
+    VersionedClause<ACCC_Reduction>,
+    VersionedClause<ACCC_Self>,
+    VersionedClause<ACCC_Vector>,
+    VersionedClause<ACCC_VectorLength>,
+    VersionedClause<ACCC_Worker>
+  ];
+  let allowedExclusiveClauses = [
+    VersionedClause<ACCC_Auto>,
+    VersionedClause<ACCC_Independent>,
+    VersionedClause<ACCC_Seq>
+  ];
+}
+
+// 2.11
+def ACC_SerialLoop : Directive<"serial loop"> {
+  let allowedClauses = [
+    VersionedClause<ACCC_Attach>,
+    VersionedClause<ACCC_Copy>,
+    VersionedClause<ACCC_Copyin>,
+    VersionedClause<ACCC_Copyout>,
+    VersionedClause<ACCC_Create>,
+    VersionedClause<ACCC_DevicePtr>,
+    VersionedClause<ACCC_DeviceType>,
+    VersionedClause<ACCC_FirstPrivate>,
+    VersionedClause<ACCC_NoCreate>,
+    VersionedClause<ACCC_Present>,
+    VersionedClause<ACCC_Private>,
+    VersionedClause<ACCC_Wait>
+  ];
+  let allowedOnceClauses = [
+    VersionedClause<ACCC_Async>,
+    VersionedClause<ACCC_Collapse>,
+    VersionedClause<ACCC_Default>,
+    VersionedClause<ACCC_Gang>,
+    VersionedClause<ACCC_If>,
+    VersionedClause<ACCC_Reduction>,
+    VersionedClause<ACCC_Self>,
+    VersionedClause<ACCC_Tile>,
+    VersionedClause<ACCC_Vector>,
+    VersionedClause<ACCC_Worker>
+  ];
+  let allowedExclusiveClauses = [
+    VersionedClause<ACCC_Auto>,
+    VersionedClause<ACCC_Independent>,
+    VersionedClause<ACCC_Seq>
+  ];
+}
+
+def ACC_Unknown : Directive<"unknown"> {
+  let isDefault = 1;
+}
 No newline at end of file

llvm/include/llvm/Frontend/OpenACC/CMakeLists.txt

+set(LLVM_TARGET_DEFINITIONS ACC.td)
+tablegen(LLVM ACC.h.inc --gen-directive-decl)
+tablegen(LLVM ACC.cpp.inc --gen-directive-impl)
+add_public_tablegen_target(acc_gen)

llvm/lib/Frontend/CMakeLists.txt

+add_subdirectory(OpenACC)
 add_subdirectory(OpenMP)

llvm/lib/Frontend/OpenACC/CMakeLists.txt

+set(LLVM_TARGET_DEFINITIONS ${LLVM_MAIN_INCLUDE_DIR}/llvm/Frontend/OpenACC/ACC.td)
+tablegen(LLVM ACC.cpp --gen-directive-impl)
+add_public_tablegen_target(acc_cpp)
+
+add_llvm_component_library(LLVMFrontendOpenACC
+  ACC.cpp # Generated by tablegen above
+
+  ADDITIONAL_HEADER_DIRS
+  ${LLVM_MAIN_INCLUDE_DIR}/llvm/Frontend
+  ${LLVM_MAIN_INCLUDE_DIR}/llvm/Frontend/OpenACC
+
+  DEPENDS
+  acc_gen
+  acc_cpp
+)
+
+target_link_libraries(LLVMFrontendOpenACC LLVMSupport)
+

llvm/test/TableGen/directive1.td

 // CHECK-EMPTY:
 // CHECK-NEXT:  } // namespace tdl
 // CHECK-NEXT:  } // namespace llvm
 // CHECK-NEXT:  #endif // LLVM_Tdl_INC
 
 
 // IMPL:       #include "llvm/ADT/StringRef.h"
 // IMPL-NEXT:  #include "llvm/ADT/StringSwitch.h"
+// IMPL-NEXT:  #include "llvm/Support/ErrorHandling.h"
 // IMPL-EMPTY:
 // IMPL-NEXT:  using namespace llvm;
 // IMPL-NEXT:  using namespace tdl;
 // IMPL-EMPTY:
 // 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);

llvm/test/TableGen/directive2.td

 // CHECK-NEXT:  } // namespace tdl
 // CHECK-NEXT:  } // namespace llvm
 // CHECK-NEXT:  #endif // LLVM_Tdl_INC
 
 // IMPL:       #include "tdl.h.inc"
 // IMPL-EMPTY:
 // IMPL-NEXT:  #include "llvm/ADT/StringRef.h"
 // IMPL-NEXT:  #include "llvm/ADT/StringSwitch.h"
+// IMPL-NEXT:  #include "llvm/Support/ErrorHandling.h"
 // IMPL-EMPTY:
 // IMPL-NEXT:  using namespace llvm;
 // IMPL-NEXT:  using namespace tdl;
 // IMPL-EMPTY:
 // 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);

llvm/utils/TableGen/DirectiveEmitter.cpp

void EmitDirectivesImpl(RecordKeeper &Records, raw_ostream &OS) {
   StringRef IncludeHeader =
       DirectiveLanguage->getValueAsString("includeHeader");
 
   if (!IncludeHeader.empty())
     OS << "#include \"" << IncludeHeader << "\"\n\n";
 
   OS << "#include \"llvm/ADT/StringRef.h\"\n";
   OS << "#include \"llvm/ADT/StringSwitch.h\"\n";
+  OS << "#include \"llvm/Support/ErrorHandling.h\"\n";
   OS << "\n";
   OS << "using namespace llvm;\n";
   llvm::SmallVector<StringRef, 2> Namespaces;
   llvm::SplitString(CppNamespace, Namespaces, "::");
   for (auto Ns : Namespaces)
     OS << "using namespace " << Ns << ";\n";
 
   // getDirectiveKind(StringRef Str)