[OpenMP] atomic compare fail : Parser & AST support

[koops]

Summary

This is a support for " #pragma omp atomic compare fail ". It has Parser & AST support for now.

[koops]

Fixing a minor error : clang formatting of variable names to avoid build errors.

[koops]

Clang formatting for variables in ParseOpenMP.cpp

[tianshilei1992]

LGTM

clang/lib/Parse/ParseOpenMP.cpp

3692–3694

[kda]

This has broken sanitizer buildbot:
https://lab.llvm.org/buildbot/#/builders/5/builds/24074

Relevant log snippet:

FAIL: Clang :: OpenMP/atomic_messages.cpp (9696 of 66080)
******************** TEST 'Clang :: OpenMP/atomic_messages.cpp' FAILED ********************
Script:
--
: 'RUN: at line 1';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_msan/bin/clang -cc1 -internal-isystem /b/sanitizer-x86_64-linux-fast/build/llvm_build_msan/lib/clang/15.0.0/include -nostdsysteminc -verify=expected,omp45 -fopenmp -fopenmp-version=45 -ferror-limit 150 /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/test/OpenMP/atomic_messages.cpp -Wuninitialized
: 'RUN: at line 2';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_msan/bin/clang -cc1 -internal-isystem /b/sanitizer-x86_64-linux-fast/build/llvm_build_msan/lib/clang/15.0.0/include -nostdsysteminc -verify=expected,omp50 -fopenmp -ferror-limit 150 /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/test/OpenMP/atomic_messages.cpp -Wuninitialized
: 'RUN: at line 3';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_msan/bin/clang -cc1 -internal-isystem /b/sanitizer-x86_64-linux-fast/build/llvm_build_msan/lib/clang/15.0.0/include -nostdsysteminc -DOMP51 -verify=expected,omp50,omp51 -fopenmp -fopenmp-version=51 -ferror-limit 150 /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/test/OpenMP/atomic_messages.cpp -Wuninitialized
: 'RUN: at line 5';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_msan/bin/clang -cc1 -internal-isystem /b/sanitizer-x86_64-linux-fast/build/llvm_build_msan/lib/clang/15.0.0/include -nostdsysteminc -verify=expected,omp45 -fopenmp-simd -fopenmp-version=45 -ferror-limit 150 /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/test/OpenMP/atomic_messages.cpp -Wuninitialized
: 'RUN: at line 6';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_msan/bin/clang -cc1 -internal-isystem /b/sanitizer-x86_64-linux-fast/build/llvm_build_msan/lib/clang/15.0.0/include -nostdsysteminc -verify=expected,omp50 -fopenmp-simd -ferror-limit 150 /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/test/OpenMP/atomic_messages.cpp -Wuninitialized
: 'RUN: at line 7';   /b/sanitizer-x86_64-linux-fast/build/llvm_build_msan/bin/clang -cc1 -internal-isystem /b/sanitizer-x86_64-linux-fast/build/llvm_build_msan/lib/clang/15.0.0/include -nostdsysteminc -DOMP51 -verify=expected,omp50,omp51 -fopenmp-simd -fopenmp-version=51 -ferror-limit 150 /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/test/OpenMP/atomic_messages.cpp -Wuninitialized
--
Exit Code: 1
Command Output (stderr):
--
==75693==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x561f8672eb0e in (anonymous namespace)::OpenMPAtomicFailChecker::checkSubClause(llvm::ArrayRef<clang::OMPClause*>, clang::SourceLocation*) /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/lib/Sema/SemaOpenMP.cpp:12060:11
    #1 0x561f866ef4bc in clang::Sema::ActOnOpenMPAtomicDirective(llvm::ArrayRef<clang::OMPClause*>, clang::Stmt*, clang::SourceLocation, clang::SourceLocation) /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/lib/Sema/SemaOpenMP.cpp:12634:22
    #2 0x561f866c0775 in clang::Sema::ActOnOpenMPExecutableDirective(llvm::omp::Directive, clang::DeclarationNameInfo const&, llvm::omp::Directive, llvm::ArrayRef<clang::OMPClause*>, clang::Stmt*, clang::SourceLocation, clang::SourceLocation) /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/lib/Sema/SemaOpenMP.cpp:6168:11
    #3 0x561f856da291 in clang::Parser::ParseOpenMPDeclarativeOrExecutableDirective(clang::Parser::ParsedStmtContext, bool) /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/lib/Parse/ParseOpenMP.cpp:2922:25
    #4 0x561f8553b46f in clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::ParsedAttributes&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/lib/Parse/ParseStmt.cpp:413:12
    #5 0x561f85537f27 in clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*) /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/lib/Parse/ParseStmt.cpp:113:20
    #6 0x561f85551be1 in clang::Parser::ParseCompoundStatementBody(bool) /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/lib/Parse/ParseStmt.cpp:1111:11
    #7 0x561f85554cfd in clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/lib/Parse/ParseStmt.cpp:2379:21
    #8 0x561f854cfa8e in clang::Parser::ParseFunctionDefinition(clang::ParsingDeclarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::LateParsedAttrList*) /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/lib/Parse/Parser.cpp:1407:10
    #9 0x561f855bbc3e in clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::SourceLocation*, clang::Parser::ForRangeInit*) /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/lib/Parse/ParseDecl.cpp:2097:27
    #10 0x561f854cb272 in clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/lib/Parse/Parser.cpp:1158:10
    #11 0x561f854ca0b6 in clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/lib/Parse/Parser.cpp:1172:12
    #12 0x561f854c754a in clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsingDeclSpec*) /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/lib/Parse/Parser.cpp:998:12
    #13 0x561f854c0c9a in clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/lib/Parse/Parser.cpp:727:12
    #14 0x561f854ae252 in clang::ParseAST(clang::Sema&, bool, bool) /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/lib/Parse/ParseAST.cpp:162:20
    #15 0x561f8203140d in clang::FrontendAction::Execute() /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/lib/Frontend/FrontendAction.cpp:1032:8
    #16 0x561f81e8da47 in clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/lib/Frontend/CompilerInstance.cpp:1036:33
    #17 0x561f82278528 in clang::ExecuteCompilerInvocation(clang::CompilerInstance*) /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp:266:25
    #18 0x561f79792507 in cc1_main(llvm::ArrayRef<char const*>, char const*, void*) /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/tools/driver/cc1_main.cpp:248:15
    #19 0x561f7978b484 in ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&) /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/tools/driver/driver.cpp:317:12
    #20 0x561f7978a434 in main /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/tools/driver/driver.cpp:388:12
    #21 0x7fada460f09a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2409a) (BuildId: eb6a5dd378d22b1e695984462a799cd4c81cdc22)
    #22 0x561f796fa6d9 in _start (/b/sanitizer-x86_64-linux-fast/build/llvm_build_msan/bin/clang-15+0x480d6d9)
SUMMARY: MemorySanitizer: use-of-uninitialized-value /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang/lib/Sema/SemaOpenMP.cpp:12060:11 in (anonymous namespace)::OpenMPAtomicFailChecker::checkSubClause(llvm::ArrayRef<clang::OMPClause*>, clang::SourceLocation*)
Exiting
--
********************
Testing:  0.. 10.. 20.. 30.. 40.. 50.. 60.. 70.. 80.. 90..
********************
Failed Tests (1):
  Clang :: OpenMP/atomic_messages.cpp

[koops]

Hello Kevin,

I am not sure why it is indicating an uninitialized variable at that point. The code at " llvm-project/clang/lib/Sema/SemaOpenMP.cpp:12060 " is as below:

for (const OMPClause *C : Clauses) {
  if (C->getClauseKind() == OMPC_fail) {
    NoOfFails++;
    const OMPFailClause *FC = static_cast<const OMPFailClause *>(C);
    const OMPClause *MemOrderC = FC->const_getMemoryOrderClause();
    /* Clauses contains OMPC_fail and the subclause */
    if (MemOrderC) {

Here " if (MemOrderC) { " is the 12060 line.

Regards,
--Sunil

[aaron.ballman]

In D123235#3537580, @koops wrote:

I am not sure why it is indicating an uninitialized variable at that point. The code at " llvm-project/clang/lib/Sema/SemaOpenMP.cpp:12060 " is as below:

FWIW, it's outright crashing for me on Windows.

FAIL: Clang :: OpenMP/atomic_messages.cpp (255 of 15035)
******************** TEST 'Clang :: OpenMP/atomic_messages.cpp' FAILED ********************
Script:
--
: 'RUN: at line 1';   f:\source\llvm-project\llvm\out\build\x64-debug\bin\clang.exe -cc1 -internal-isystem f:\source\llvm-project\llvm\out\build\x64-debug\lib\clang\15.0.0\include -nostdsysteminc -verify=expected,omp45 -fopenmp -fopenmp-version=45 -ferror-limit 150 F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp -Wuninitialized
: 'RUN: at line 2';   f:\source\llvm-project\llvm\out\build\x64-debug\bin\clang.exe -cc1 -internal-isystem f:\source\llvm-project\llvm\out\build\x64-debug\lib\clang\15.0.0\include -nostdsysteminc -verify=expected,omp50 -fopenmp -ferror-limit 150 F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp -Wuninitialized
: 'RUN: at line 3';   f:\source\llvm-project\llvm\out\build\x64-debug\bin\clang.exe -cc1 -internal-isystem f:\source\llvm-project\llvm\out\build\x64-debug\lib\clang\15.0.0\include -nostdsysteminc -DOMP51 -verify=expected,omp50,omp51 -fopenmp -fopenmp-version=51 -ferror-limit 150 F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp -Wuninitialized
: 'RUN: at line 5';   f:\source\llvm-project\llvm\out\build\x64-debug\bin\clang.exe -cc1 -internal-isystem f:\source\llvm-project\llvm\out\build\x64-debug\lib\clang\15.0.0\include -nostdsysteminc -verify=expected,omp45 -fopenmp-simd -fopenmp-version=45 -ferror-limit 150 F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp -Wuninitialized
: 'RUN: at line 6';   f:\source\llvm-project\llvm\out\build\x64-debug\bin\clang.exe -cc1 -internal-isystem f:\source\llvm-project\llvm\out\build\x64-debug\lib\clang\15.0.0\include -nostdsysteminc -verify=expected,omp50 -fopenmp-simd -ferror-limit 150 F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp -Wuninitialized
: 'RUN: at line 7';   f:\source\llvm-project\llvm\out\build\x64-debug\bin\clang.exe -cc1 -internal-isystem f:\source\llvm-project\llvm\out\build\x64-debug\lib\clang\15.0.0\include -nostdsysteminc -DOMP51 -verify=expected,omp50,omp51 -fopenmp-simd -fopenmp-version=51 -ferror-limit 150 F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp -Wuninitialized
--
Exit Code: 3221225477

Command Output (stdout):
--
$ ":" "RUN: at line 1"
$ "f:\source\llvm-project\llvm\out\build\x64-debug\bin\clang.exe" "-cc1" "-internal-isystem" "f:\source\llvm-project\llvm\out\build\x64-debug\lib\clang\15.0.0\include" "-nostdsysteminc" "-verify=expected,omp45" "-fopenmp" "-fopenmp-version=45" "-ferror-limit" "150" "F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp" "-Wuninitialized"
$ ":" "RUN: at line 2"
$ "f:\source\llvm-project\llvm\out\build\x64-debug\bin\clang.exe" "-cc1" "-internal-isystem" "f:\source\llvm-project\llvm\out\build\x64-debug\lib\clang\15.0.0\include" "-nostdsysteminc" "-verify=expected,omp50" "-fopenmp" "-ferror-limit" "150" "F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp" "-Wuninitialized"
$ ":" "RUN: at line 3"
$ "f:\source\llvm-project\llvm\out\build\x64-debug\bin\clang.exe" "-cc1" "-internal-isystem" "f:\source\llvm-project\llvm\out\build\x64-debug\lib\clang\15.0.0\include" "-nostdsysteminc" "-DOMP51" "-verify=expected,omp50,omp51" "-fopenmp" "-fopenmp-version=51" "-ferror-limit" "150" "F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp" "-Wuninitialized"
# command stderr:
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: f:\\source\\llvm-project\\llvm\\out\\build\\x64-debug\\bin\\clang.exe -cc1 -internal-isystem f:\\source\\llvm-project\\llvm\\out\\build\\x64-debug\\lib\\clang\\15.0.0\\include -nostdsysteminc -DOMP51 -verify=expected,omp50,omp51 -fopenmp -fopenmp-version=51 -ferror-limit 150 F:\\source\\llvm-project\\clang\\test\\OpenMP\\atomic_messages.cpp -Wuninitialized
1.      F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp:968:1: at annotation token
2.      F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp:930:13: parsing function body 'mixed'
3.      F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp:930:13: in compound statement ('{}')
 #0 0x00007ff61281a32b clang::OMPClause::getClauseKind(void) const F:\source\llvm-project\clang\include\clang\AST\OpenMPClause.h:83:0
 #1 0x00007ff617bcf805 `anonymous namespace'::OpenMPAtomicFailChecker::checkSubClause F:\source\llvm-project\clang\lib\Sema\SemaOpenMP.cpp:12061:0
 #2 0x00007ff617b5d38d clang::Sema::ActOnOpenMPAtomicDirective(class llvm::ArrayRef<class clang::OMPClause *>, class clang::Stmt *, class clang::SourceLocation, class clang::SourceLocation) F:\source\llvm-project\clang\lib\Sema\SemaOpenMP.cpp:12634:0
 #3 0x00007ff617b50901 clang::Sema::ActOnOpenMPExecutableDirective(enum llvm::omp::Directive, struct clang::DeclarationNameInfo const &, enum llvm::omp::Directive, class llvm::ArrayRef<class clang::OMPClause *>, class clang::Stmt *, class clang::SourceLocation, class clang::SourceLocation) F:\source\llvm-project\clang\lib\Sema\SemaOpenMP.cpp:6168:0
 #4 0x00007ff616c2fba8 clang::Parser::ParseOpenMPDeclarativeOrExecutableDirective(enum clang::Parser::ParsedStmtContext, bool) F:\source\llvm-project\clang\lib\Parse\ParseOpenMP.cpp:2932:0
 #5 0x00007ff616be46b2 clang::Parser::ParseStatementOrDeclarationAfterAttributes(class llvm::SmallVector<class clang::Stmt *, 32> &, enum clang::Parser::ParsedStmtContext, class clang::SourceLocation *, class clang::ParsedAttributes &) F:\source\llvm-project\clang\lib\Parse\ParseStmt.cpp:413:0
 #6 0x00007ff616be3342 clang::Parser::ParseStatementOrDeclaration(class llvm::SmallVector<class clang::Stmt *, 32> &, enum clang::Parser::ParsedStmtContext, class clang::SourceLocation *) F:\source\llvm-project\clang\lib\Parse\ParseStmt.cpp:115:0
 #7 0x00007ff616be6cc9 clang::Parser::ParseCompoundStatementBody(bool) F:\source\llvm-project\clang\lib\Parse\ParseStmt.cpp:1111:0
 #8 0x00007ff616bedb92 clang::Parser::ParseFunctionStatementBody(class clang::Decl *, class clang::Parser::ParseScope &) F:\source\llvm-project\clang\lib\Parse\ParseStmt.cpp:2382:0
 #9 0x00007ff616aef1ec clang::Parser::ParseFunctionDefinition(class clang::ParsingDeclarator &, struct clang::Parser::ParsedTemplateInfo const &, class clang::Parser::LateParsedAttrList *) F:\source\llvm-project\clang\lib\Parse\Parser.cpp:1407:0
#10 0x00007ff616b3778c clang::Parser::ParseDeclGroup(class clang::ParsingDeclSpec &, enum clang::DeclaratorContext, class clang::SourceLocation *, struct clang::Parser::ForRangeInit *) F:\source\llvm-project\clang\lib\Parse\ParseDecl.cpp:2097:0
#11 0x00007ff616aede14 clang::Parser::ParseDeclOrFunctionDefInternal(class clang::ParsedAttributes &, class clang::ParsingDeclSpec &, enum clang::AccessSpecifier) F:\source\llvm-project\clang\lib\Parse\Parser.cpp:1158:0
#12 0x00007ff616aed6c2 clang::Parser::ParseDeclarationOrFunctionDefinition(class clang::ParsedAttributes &, class clang::ParsingDeclSpec *, enum clang::AccessSpecifier) F:\source\llvm-project\clang\lib\Parse\Parser.cpp:1172:0
#13 0x00007ff616aed0c8 clang::Parser::ParseExternalDeclaration(class clang::ParsedAttributes &, class clang::ParsingDeclSpec *) F:\source\llvm-project\clang\lib\Parse\Parser.cpp:998:0
#14 0x00007ff616ae7799 clang::Parser::ParseTopLevelDecl(class clang::OpaquePtr<class clang::DeclGroupRef> &, enum clang::Sema::ModuleImportState &) F:\source\llvm-project\clang\lib\Parse\Parser.cpp:727:0
#15 0x00007ff616ae3900 clang::ParseAST(class clang::Sema &, bool, bool) F:\source\llvm-project\clang\lib\Parse\ParseAST.cpp:162:0
#16 0x00007ff613805dd7 clang::ASTFrontendAction::ExecuteAction(void) F:\source\llvm-project\clang\lib\Frontend\FrontendAction.cpp:1141:0
#17 0x00007ff61380578e clang::FrontendAction::Execute(void) F:\source\llvm-project\clang\lib\Frontend\FrontendAction.cpp:1036:0
#18 0x00007ff61378a66a clang::CompilerInstance::ExecuteAction(class clang::FrontendAction &) F:\source\llvm-project\clang\lib\Frontend\CompilerInstance.cpp:1036:0
#19 0x00007ff613a002b8 clang::ExecuteCompilerInvocation(class clang::CompilerInstance *) F:\source\llvm-project\clang\lib\FrontendTool\ExecuteCompilerInvocation.cpp:266:0
#20 0x00007ff60f72e4c8 cc1_main(class llvm::ArrayRef<char const *>, char const *, void *) F:\source\llvm-project\clang\tools\driver\cc1_main.cpp:248:0
#21 0x00007ff60f719135 ExecuteCC1Tool F:\source\llvm-project\clang\tools\driver\driver.cpp:317:0
#22 0x00007ff60f7199ca main F:\source\llvm-project\clang\tools\driver\driver.cpp:388:0
#23 0x00007ff61997b2b9 invoke_main D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:79:0
#24 0x00007ff61997b15e __scrt_common_main_seh D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288:0
#25 0x00007ff61997b01e __scrt_common_main D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:331:0
#26 0x00007ff61997b34e mainCRTStartup D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_main.cpp:17:0
#27 0x00007ffec5937034 (C:\WINDOWS\System32\KERNEL32.DLL+0x17034)
#28 0x00007ffec6502651 (C:\WINDOWS\SYSTEM32\ntdll.dll+0x52651)

error: command failed with exit status: 3221225477

--

I made some comments on things I saw when looking through the review but didn't spot a smoking gun. I think the issue is possibly the fact that this patch uses static_cast instead of the usual casting infrastructure, but I'm not positive.

Please revert the changes while investigating how to resolve the crashes though.

clang/include/clang/AST/ASTNodeTraverser.h

217–218

This is an anti-pattern, it should be:

if (const auto *OMPC = dyn_cast<OMPFailClause>(C))
  Visit(OMPC);

clang/lib/Parse/ParseOpenMP.cpp

3637

3643–3645

The coding style has us dropping braces here.

3648

Formatting (the whole patch should be run through clang-format: https://clang.llvm.org/docs/ClangFormat.html#script-for-patch-reformatting)

clang/lib/Sema/SemaOpenMP.cpp

12003–12005

This looks like another anti-pattern; why is this not:

if (const auto *FC = dyn_cast<OMPFailClause>(C)) {
  ...

12580–12581

Why are you assigning to ErrorLoc and then immediately overwriting it?

12582

Formatting is off here.

[aaron.ballman]

In D123235#3537636, @aaron.ballman wrote:

Please revert the changes while investigating how to resolve the crashes though.

I just noticed that you needed someone to commit on your behalf for this, so I went ahead and did the revert myself in 69da3b6aead2e7a18a2578aad661d6d36b8d30cf.

[aaron.ballman]

In D123235#3537820, @aaron.ballman wrote:

In D123235#3537636, @aaron.ballman wrote:

Please revert the changes while investigating how to resolve the crashes though.

I just noticed that you needed someone to commit on your behalf for this, so I went ahead and did the revert myself in 69da3b6aead2e7a18a2578aad661d6d36b8d30cf.

There was a follow-up I also needed to revert in 9368bf9023eee0dc6fcfa007e157fe30e1540fcc.

[koops]

This comment was removed by koops.

[koops]

Changes suggested by aaron.ballman to avoid failures on windows.

[aaron.ballman]

Precommit CI on Linux seems to be failing, but I can't quite tell whether the failures are related or not. I suspect they're unrelated, but they're with libomp and other OpenMP tests so it's not fully clear. Can you investigate those?

I tried your patch locally on Windows and it seems to still crash:

FAIL: Clang :: OpenMP/atomic_messages.cpp (1412 of 15074)
******************** TEST 'Clang :: OpenMP/atomic_messages.cpp' FAILED ********************
Script:
--
: 'RUN: at line 1';   f:\source\llvm-project\llvm\out\build\x64-debug\bin\clang.exe -cc1 -internal-isystem f:\source\llvm-project\llvm\out\build\x64-debug\lib\clang\15.0.0\include -nostdsysteminc -verify=expected,omp45 -fopenmp -fopenmp-version=45 -ferror-limit 150 F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp -Wuninitialized
: 'RUN: at line 2';   f:\source\llvm-project\llvm\out\build\x64-debug\bin\clang.exe -cc1 -internal-isystem f:\source\llvm-project\llvm\out\build\x64-debug\lib\clang\15.0.0\include -nostdsysteminc -verify=expected,omp50 -fopenmp -ferror-limit 150 F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp -Wuninitialized
: 'RUN: at line 3';   f:\source\llvm-project\llvm\out\build\x64-debug\bin\clang.exe -cc1 -internal-isystem f:\source\llvm-project\llvm\out\build\x64-debug\lib\clang\15.0.0\include -nostdsysteminc -DOMP51 -verify=expected,omp50,omp51 -fopenmp -fopenmp-version=51 -ferror-limit 150 F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp -Wuninitialized
: 'RUN: at line 5';   f:\source\llvm-project\llvm\out\build\x64-debug\bin\clang.exe -cc1 -internal-isystem f:\source\llvm-project\llvm\out\build\x64-debug\lib\clang\15.0.0\include -nostdsysteminc -verify=expected,omp45 -fopenmp-simd -fopenmp-version=45 -ferror-limit 150 F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp -Wuninitialized
: 'RUN: at line 6';   f:\source\llvm-project\llvm\out\build\x64-debug\bin\clang.exe -cc1 -internal-isystem f:\source\llvm-project\llvm\out\build\x64-debug\lib\clang\15.0.0\include -nostdsysteminc -verify=expected,omp50 -fopenmp-simd -ferror-limit 150 F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp -Wuninitialized
: 'RUN: at line 7';   f:\source\llvm-project\llvm\out\build\x64-debug\bin\clang.exe -cc1 -internal-isystem f:\source\llvm-project\llvm\out\build\x64-debug\lib\clang\15.0.0\include -nostdsysteminc -DOMP51 -verify=expected,omp50,omp51 -fopenmp-simd -fopenmp-version=51 -ferror-limit 150 F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp -Wuninitialized
--
Exit Code: 3221225477

Command Output (stdout):
--
$ ":" "RUN: at line 1"
$ "f:\source\llvm-project\llvm\out\build\x64-debug\bin\clang.exe" "-cc1" "-internal-isystem" "f:\source\llvm-project\llvm\out\build\x64-debug\lib\clang\15.0.0\include" "-nostdsysteminc" "-verify=expected,omp45" "-fopenmp" "-fopenmp-version=45" "-ferror-limit" "150" "F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp" "-Wuninitialized"
$ ":" "RUN: at line 2"
$ "f:\source\llvm-project\llvm\out\build\x64-debug\bin\clang.exe" "-cc1" "-internal-isystem" "f:\source\llvm-project\llvm\out\build\x64-debug\lib\clang\15.0.0\include" "-nostdsysteminc" "-verify=expected,omp50" "-fopenmp" "-ferror-limit" "150" "F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp" "-Wuninitialized"
$ ":" "RUN: at line 3"
$ "f:\source\llvm-project\llvm\out\build\x64-debug\bin\clang.exe" "-cc1" "-internal-isystem" "f:\source\llvm-project\llvm\out\build\x64-debug\lib\clang\15.0.0\include" "-nostdsysteminc" "-DOMP51" "-verify=expected,omp50,omp51" "-fopenmp" "-fopenmp-version=51" "-ferror-limit" "150" "F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp" "-Wuninitialized"
# command stderr:
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: f:\\source\\llvm-project\\llvm\\out\\build\\x64-debug\\bin\\clang.exe -cc1 -internal-isystem f:\\source\\llvm-project\\llvm\\out\\build\\x64-debug\\lib\\clang\\15.0.0\\include -nostdsysteminc -DOMP51 -verify=expected,omp50,omp51 -fopenmp -fopenmp-version=51 -ferror-limit 150 F:\\source\\llvm-project\\clang\\test\\OpenMP\\atomic_messages.cpp -Wuninitialized
1.      F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp:968:1: at annotation token
2.      F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp:930:13: parsing function body 'mixed'
3.      F:\source\llvm-project\clang\test\OpenMP\atomic_messages.cpp:930:13: in compound statement ('{}')
 #0 0x00007ff6c208caab clang::OMPClause::getClauseKind(void) const F:\source\llvm-project\clang\include\clang\AST\OpenMPClause.h:83:0
 #1 0x00007ff6c7492153 `anonymous namespace'::OpenMPAtomicFailChecker::checkSubClause F:\source\llvm-project\clang\lib\Sema\SemaOpenMP.cpp:12069:0
 #2 0x00007ff6c741fc3d clang::Sema::ActOnOpenMPAtomicDirective(class llvm::ArrayRef<class clang::OMPClause *>, class clang::Stmt *, class clang::SourceLocation, class clang::SourceLocation) F:\source\llvm-project\clang\lib\Sema\SemaOpenMP.cpp:12652:0
 #3 0x00007ff6c74130f1 clang::Sema::ActOnOpenMPExecutableDirective(enum llvm::omp::Directive, struct clang::DeclarationNameInfo const &, enum llvm::omp::Directive, class llvm::ArrayRef<class clang::OMPClause *>, class clang::Stmt *, class clang::SourceLocation, class clang::SourceLocation) F:\source\llvm-project\clang\lib\Sema\SemaOpenMP.cpp:6172:0
 #4 0x00007ff6c64e6d78 clang::Parser::ParseOpenMPDeclarativeOrExecutableDirective(enum clang::Parser::ParsedStmtContext, bool) F:\source\llvm-project\clang\lib\Parse\ParseOpenMP.cpp:2932:0
 #5 0x00007ff6c649b8e2 clang::Parser::ParseStatementOrDeclarationAfterAttributes(class llvm::SmallVector<class clang::Stmt *, 32> &, enum clang::Parser::ParsedStmtContext, class clang::SourceLocation *, class clang::ParsedAttributes &) F:\source\llvm-project\clang\lib\Parse\ParseStmt.cpp:413:0
 #6 0x00007ff6c649a572 clang::Parser::ParseStatementOrDeclaration(class llvm::SmallVector<class clang::Stmt *, 32> &, enum clang::Parser::ParsedStmtContext, class clang::SourceLocation *) F:\source\llvm-project\clang\lib\Parse\ParseStmt.cpp:115:0
 #7 0x00007ff6c649def9 clang::Parser::ParseCompoundStatementBody(bool) F:\source\llvm-project\clang\lib\Parse\ParseStmt.cpp:1111:0
 #8 0x00007ff6c64a4dc2 clang::Parser::ParseFunctionStatementBody(class clang::Decl *, class clang::Parser::ParseScope &) F:\source\llvm-project\clang\lib\Parse\ParseStmt.cpp:2382:0
 #9 0x00007ff6c63a642c clang::Parser::ParseFunctionDefinition(class clang::ParsingDeclarator &, struct clang::Parser::ParsedTemplateInfo const &, class clang::Parser::LateParsedAttrList *) F:\source\llvm-project\clang\lib\Parse\Parser.cpp:1407:0
#10 0x00007ff6c63ee9ac clang::Parser::ParseDeclGroup(class clang::ParsingDeclSpec &, enum clang::DeclaratorContext, class clang::SourceLocation *, struct clang::Parser::ForRangeInit *) F:\source\llvm-project\clang\lib\Parse\ParseDecl.cpp:2098:0
#11 0x00007ff6c63a5054 clang::Parser::ParseDeclOrFunctionDefInternal(class clang::ParsedAttributes &, class clang::ParsingDeclSpec &, enum clang::AccessSpecifier) F:\source\llvm-project\clang\lib\Parse\Parser.cpp:1158:0
#12 0x00007ff6c63a4902 clang::Parser::ParseDeclarationOrFunctionDefinition(class clang::ParsedAttributes &, class clang::ParsingDeclSpec *, enum clang::AccessSpecifier) F:\source\llvm-project\clang\lib\Parse\Parser.cpp:1172:0
#13 0x00007ff6c63a4308 clang::Parser::ParseExternalDeclaration(class clang::ParsedAttributes &, class clang::ParsingDeclSpec *) F:\source\llvm-project\clang\lib\Parse\Parser.cpp:998:0
#14 0x00007ff6c639e9d9 clang::Parser::ParseTopLevelDecl(class clang::OpaquePtr<class clang::DeclGroupRef> &, enum clang::Sema::ModuleImportState &) F:\source\llvm-project\clang\lib\Parse\Parser.cpp:727:0
#15 0x00007ff6c639ab40 clang::ParseAST(class clang::Sema &, bool, bool) F:\source\llvm-project\clang\lib\Parse\ParseAST.cpp:162:0
#16 0x00007ff6c308ae97 clang::ASTFrontendAction::ExecuteAction(void) F:\source\llvm-project\clang\lib\Frontend\FrontendAction.cpp:1137:0
#17 0x00007ff6c308a84e clang::FrontendAction::Execute(void) F:\source\llvm-project\clang\lib\Frontend\FrontendAction.cpp:1032:0
#18 0x00007ff6c300f59a clang::CompilerInstance::ExecuteAction(class clang::FrontendAction &) F:\source\llvm-project\clang\lib\Frontend\CompilerInstance.cpp:1033:0
#19 0x00007ff6c32856d8 clang::ExecuteCompilerInvocation(class clang::CompilerInstance *) F:\source\llvm-project\clang\lib\FrontendTool\ExecuteCompilerInvocation.cpp:266:0
#20 0x00007ff6bef3da48 cc1_main(class llvm::ArrayRef<char const *>, char const *, void *) F:\source\llvm-project\clang\tools\driver\cc1_main.cpp:248:0
#21 0x00007ff6bef26e65 ExecuteCC1Tool F:\source\llvm-project\clang\tools\driver\driver.cpp:317:0
#22 0x00007ff6bef276fa clang_main(int, char **) F:\source\llvm-project\clang\tools\driver\driver.cpp:388:0
#23 0x00007ff6bef6859c main F:\source\llvm-project\llvm\out\build\x64-Debug\tools\clang\tools\driver\clang-driver.cpp:11:0
#24 0x00007ff6c92600b9 invoke_main D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:79:0
#25 0x00007ff6c925ff5e __scrt_common_main_seh D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288:0
#26 0x00007ff6c925fe1e __scrt_common_main D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:331:0
#27 0x00007ff6c926014e mainCRTStartup D:\a\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_main.cpp:17:0
#28 0x00007ff826487034 (C:\WINDOWS\System32\KERNEL32.DLL+0x17034)
#29 0x00007ff828362651 (C:\WINDOWS\SYSTEM32\ntdll.dll+0x52651)

error: command failed with exit status: 3221225477

--

********************

[koops]

This comment was removed by koops.

[koops]

Pulling in latest changes.
The patch uploaded 2 hours back was a wrong one (meant for another feature) and has been unrolled back with this patch.

[koops]

This comment was removed by koops.

[ABataev]

clang/include/clang/AST/OpenMPClause.h

2278–2279

Why need tail-allocation here for constant number of attributes? They can be represented simply as data members

2280

OMPClause *MemoryOrderClause = nullptr;

2319

Remove this

2325

Remove this

clang/lib/Basic/OpenMPKinds.cpp

378

Not recommended to use defaul switch, use all enums explicitly

clang/lib/Parse/ParseOpenMP.cpp

3237

Looks like this is the wrong place for this clause, better to parse like OMPC_default clause

3622

auto *FailClause = cast<OMPFailClause>(Clause)

clang/lib/Sema/SemaOpenMP.cpp

11978

Needs class description

11979–11980

Why protected?

11985–11986

Should be private member with the default initializer

12005

const auto *FC = dyn_cast<OMPFailClause>(C)
if (!FC)
  continue;

to reduce structural complexity

12021

1. default: cases are not repcommended
2. formatting

clang/lib/Serialization/ASTReader.cpp

12128–12136

This is strange you need this

12137–12138

do not use default:

clang/lib/Serialization/ASTWriter.cpp

6319–6320

Remove this

[koops]

Removed the tail-allocation.
Other changes suggested in the previous review.

[ABataev]

clang/include/clang/AST/ASTNodeTraverser.h

217–220

Why do you need special logic here?

clang/include/clang/AST/OpenMPClause.h

2278

That's not the best decision, better to make this kind of clause a base class for these new class.

2331

Formatting

2387

No need for const_ prefix in the name

[koops]

1. In class OMPFailClause, the was a duplication in the storage of parameter to the fail clause because the parameter was stored as FailParameterKind and MemoryOrderClause (FailMemoryOrderClause). There was a possibility of these two being out of sync along with confusion to the reader of the code. Hence storing FailMemoryOrderClause only. The FailParameterKind (of type ClauseKind) is now obtained from the FailMemoryOrderClause when needed.
2. In Visit(const OMPClause *C) there is a check for if (const auto *OMPC = dyn_cast<OMPFailClause>(C)). This is mainly done to visit the parameter of the FailClause which is a memory Order Clause.

[koops]

Correcting a git-clang-format error.

[koops]

Removing the printing of parameter of FailClause. This needed a special if statement in Visit(const OMPClause *C) , which is a generalized Visit for Clauses.

[ABataev]

clang/include/clang/AST/OpenMPClause.h

2610

I don't like the idea of a reference to another clause here, it may lead to many issues with serialization/deserialization, use-after-free etc. Better to keep a flag (kind of memory order clause?) that there is associated clause here and then just find it in the list of clauses, where required.

[koops]

Replacing the storing of "OMPClause *FailMemoryOrderClause" with "OpenMPClauseKind FailParameter" in class OMPFailClause.

[ABataev]

clang/include/clang/AST/OpenMPClause.h

2628

Remove this empty line

2696–2702

make this function private

clang/include/clang/Basic/DiagnosticSemaKinds.td

10633

Unused error message?

10634

I thin k this must be handled by parse..clause function already

[koops]

clang/include/clang/AST/OpenMPClause.h

2696–2702

OMPFailClause::initFailClause() is called from ParseOpenMPFailClause().

clang/include/clang/Basic/DiagnosticSemaKinds.td

10634

This is not being handled by the ParseOpenMPFailClause() or any other Parse function. It is done only in the SemaOpenMP.cpp.

[ABataev]

clang/lib/Parse/ParseOpenMP.cpp

3257–3261

If there is a second instance of this clause, it should be reported here

3645

That's a bad place, it should be done in Sema.

[koops]

Moving OMC_fail to use ParseOpenMPSimpleClause instead of ParseOpenMPClause.
Other changes suggested by previous review.

[ABataev]

clang/include/clang/AST/OpenMPClause.h

2646

Unused?

2675–2682

You don't need all these function, this clause is a simple one, it does not require special create function, just new (...) OMPFailClause works in all cases

clang/lib/Sema/SemaOpenMP.cpp

12041

You already has all the info for the fail clause, why do you need to scan through the list of all available clauses to find this fail clause?

12046

Use С++ style comments.

12097

You can perform all required checks for the fail clause here

16681

Just new (Context) OMPFailClause(StartLoc, EndLoc);

clang/lib/Serialization/ASTReader.cpp

11747

Just С = new (Context) OMPFailClause();

[koops]

1. Removing the Create methods from OMPFailClause class.
2. checkFailClauseParameters removed and the checking is now done in ActOnOpenMPAtomicDirective() itself.

[ABataev]

clang/lib/Parse/ParseOpenMP.cpp

3691–3696

clang/lib/Sema/SemaOpenMP.cpp

12095

12100–12104

12104–12106

No need for braces here

[ABataev]

clang/lib/Sema/SemaOpenMP.cpp

12098–12099

Remove extra parens

12100–12102

Remove extra parens, LLVM does not use this style

[koops]

Removing extra brackets.

[ABataev]

LG with a nit

clang/lib/Sema/SemaOpenMP.cpp

12097

Same, remove parens

[uabelho]

clang/lib/Basic/OpenMPKinds.cpp

371

Hi @koops ,
clang complains on this patch with

../../clang/lib/Basic/OpenMPKinds.cpp:444:13: error: 97 enumeration values not handled in switch: 'OMPC_adjust_args', 'OMPC_affinity', 'OMPC_align'... [-Werror,-Wswitch]
    switch (CK) {
            ^~
1 error generated.

[qiucf]

Hi, it seems rG086b65340cca2648a2a91a0a47d28c7d9bafd1e5 causes build failure:

llvm-project/clang/lib/Basic/OpenMPKinds.cpp:444:13: error: 97 enumeration values not handled in switch: 'OMPC_adjust_args', 'OMPC_affinity', 'OMPC_align'... [-Werror,-Wswitch]
    switch (CK) {
            ^~
1 error generated.

[koops]

Only on ppc64 this error is being seen because it is expecting a default in the switch statement:
OpenMPClauseKind CK = ...
switch(CK)

This is similar to what has been added in OMPClauseWithPreInit::get() {
switch(C->getClauseKind()) {
case ...
....
default:
}
I am about to make this change.

[koops]

To avoid build error in ppc64 adding a "default" to switch statement. This is similar to the way it is currently handled in

 OMPClauseWithPreInit::get() {
switch(C->getClauseKind()) {
case ...
....
default:
}

[uabelho]

In D123235#4656427, @koops wrote:

To avoid build error in ppc64 adding a "default" to switch statement.

I don't think it has anything particular to do with ppc64.

I see the warning/error when i compile with clang 15 on a RHEL7 machine.

If you compile without -Werror you just get a warning.

[uabelho]

Btw, a bit confusing (to me at least) to reopen this review since it's already landed.

clang/lib/Basic/OpenMPKinds.cpp

370

Adding "default:" here silences the warning.
But looks like @ABataev commented on something similar earlier and said that's not recommended?

[koops]

clang/lib/Basic/OpenMPKinds.cpp

370

I agree but, I am

370

Alexey was referring to

the -Wswitch warning won’t fire when new elements are added to that enumeration. To help avoid adding these kinds of defaults, Clang has the warning -Wcovered-switch-default which is off by default but turned on when building LLVM with a version of Clang that supports the warning

in the standards document. In this particular case this has been taken care of by using the macro

#define OPENMP_ATOMIC_FAIL_MODIFIER(Name)
case OMPC_##Name:

which covers all cases added to the enum.

[koops]

After the reverting of changes, putting the default in the switch case as discussed in the comments earlier.

[ABataev]

In D123235#4656459, @koops wrote:

After the reverting of changes, putting the default in the switch case as discussed in the comments earlier.

No, do not put the default: switch, instead you need explicitly list all other enumeric values, like

case 1:
case 2:
  break;

clang/include/clang/AST/OpenMPClause.h

2640

Same here, remove default: and explicitly list all possible values

[koops]

In clang/lib/AST/OpenMPClause.cpp,

OMPClauseWithPreInit::get(const OMPClause *C) {
switch(C->getClauseKind()) {
case OMPC_schedule:
....
default:
    break;
}

It is not possible to list down all possible `OpenMPClauseKind`` types in the switch. Hence they have used a default even in other methods. I am following the same logic.

[ABataev]

In D123235#4656464, @koops wrote:

In clang/lib/AST/OpenMPClause.cpp,

OMPClauseWithPreInit::get(const OMPClause *C) {
switch(C->getClauseKind()) {
case OMPC_schedule:
....
default:
    break;
}

It is not possible to list down all possible `OpenMPClauseKind`` types in the switch. Hence they have used a default even in other methods. I am following the same logic.

Why not possible?

[koops]

Removing default from switch statements.

[ABataev]

clang/include/clang/AST/OpenMPClause.h

2639

I think all these cases are unexpected and must be terminated with llvm_unreachable

[koops]

1. Added a check for the fail parameter before the instance of OMPFailClause is created in ActOnOpenMPFailClause. An error in fail parameter like #pragma omp atomic compare fail(capture) was creating a wrong instance of OMPFailClause with OMPC_unknown as parameter.
2. In g++ 12.3 and spec, fail(acq_rel) and fail(release) are not permitted. Removed them from being supported as parameters to the fail clause.
3. Checking the parameters to fail clause into a single routine clang::checkFailParameter.

[ABataev]

clang/include/clang/AST/OpenMPClause.h

2601

No way for extern functions. Declare in include/clang/Basic/OpenMPKinds.h

2629–2630

clang/lib/Sema/SemaOpenMP.cpp

16684–16691

Move it to lib/Basic/OpenMPKinds.cpp

16698

[koops]

Moving the declaration and definition of checkFailClauseParameter to include/clang/Basic/OpenMPKinds.h & lib/Basic/OpenMPKinds.cpp respectively.
2 other minor changes suggested by Alexey.

[ABataev]

LG

[aaron.ballman]

FWIW, this appears to have broken some build bots: https://lab.llvm.org/buildbot/#/builders/121/builds/36635 -- can you revert and investigate (or fix-forward quickly)?

[koops]

Adding libFrontendOpenMP.so as a dependent library when building libclangBasic.so. Shared libraries were not built and tested by default, hence build and failed when checking on ppc64le.

[ABataev]

clang/lib/Basic/CMakeLists.txt

4 ↗

(On Diff #558146)

What requires this new dependency?

[koops]

clang/lib/Basic/CMakeLists.txt

4 ↗

(On Diff #558146)

When cmake uses -DBUILD_SHARED_LIBS=1 shared libraries are built instead of archive libraries in lib/ directory.
Then, I was getting this error:
Error in linking libclangBasic.so.18git because getOpenMPClauseName() is not defined.

While linking the .o files to form libFrontendOpenMP.so, OMP.cpp.o is also included which has the function definition of getOpenMPClauseName(). Hence there was a need to have libFrontendOpenMP.so in the link line of libclangBasic.so.18git.

[koops]

clang/lib/Basic/CMakeLists.txt

4 ↗

(On Diff #558146)

The error Error in linking libclangBasic.so.18git because getOpenMPClauseName() is not defined. was seen on ppc64le and can be reproduced on other platforms using -DBUILD_SHARED_LIBS=1 in the cmake command line.

[ABataev]

LG

[koops]

No changes from my side. pre-commit builds failed while applying patch. Changes in flang/lib/Semantics/check-omp-structure.cpp in the master caused a conflict. This patch upload is to resolve the conflict.

[koops]

Can someone please commit this change to the master branch?

clang/include/clang/AST/ASTNodeTraverser.h

void Visit(const BlockDecl::Capture &C) {
     getNodeDelegate().AddChild([=] {
       getNodeDelegate().Visit(C);
       if (C.hasCopyExpr())
         Visit(C.getCopyExpr());
     });
   }
 
   void Visit(const OMPClause *C) {
+    if (OMPFailClause::classof(C)) {
+      Visit(static_cast<const OMPFailClause *>(C));
+      return;
+    }
     getNodeDelegate().AddChild([=] {
       getNodeDelegate().Visit(C);
       for (const auto *S : C->children())
         Visit(S);
     });
   }
 
+  void Visit(const OMPFailClause *C) {
+    getNodeDelegate().AddChild([=] {
+      getNodeDelegate().Visit(C);
+      const OMPClause *MOC = C->const_getMemoryOrderClause();
+      Visit(MOC);
+    });
+  }
   void Visit(const GenericSelectionExpr::ConstAssociation &A) {
     getNodeDelegate().AddChild([=] {
       getNodeDelegate().Visit(A);
       if (const TypeSourceInfo *TSI = A.getTypeSourceInfo())
         Visit(TSI->getType());
       Visit(A.getAssociationExpr());
     });
   }

clang/include/clang/AST/OpenMPClause.h

const_child_range used_children() const {
     return const_child_range(const_child_iterator(), const_child_iterator());
   }
 
   static bool classof(const OMPClause *T) {
     return T->getClauseKind() == llvm::omp::OMPC_compare;
   }
 };
 
+/// This represents 'fail' clause in the '#pragma omp atomic'
+/// directive.
+///
+/// \code
+/// #pragma omp atomic compare fail
+/// \endcode
+/// In this example directive '#pragma omp atomic compare' has 'fail' clause.
+class OMPFailClause final
+    : public OMPClause,
+      private llvm::TrailingObjects<OMPFailClause, SourceLocation,
+                                    OpenMPClauseKind> {
+  OMPClause *MemoryOrderClause;
+
+  friend class OMPClauseReader;
+  friend TrailingObjects;
+
+  /// Define the sizes of each trailing object array except the last one. This
+  /// is required for TrailingObjects to work properly.
+  size_t numTrailingObjects(OverloadToken<SourceLocation>) const {
+    // 2 locations: for '(' and argument location.
+    return 2;
+  }
+
+  /// Sets the location of '(' in fail clause.
+  void setLParenLoc(SourceLocation Loc) {
+    *getTrailingObjects<SourceLocation>() = Loc;
+  }
+
+  /// Sets the location of memoryOrder clause argument in fail clause.
+  void setArgumentLoc(SourceLocation Loc) {
+    *std::next(getTrailingObjects<SourceLocation>(), 1) = Loc;
+  }
+
+  /// Sets the mem_order clause for 'atomic compare fail' directive.
+  void setMemOrderClauseKind(OpenMPClauseKind MemOrder) {
+    OpenMPClauseKind *MOCK = getTrailingObjects<OpenMPClauseKind>();
+    *MOCK = MemOrder;
+  }
+
+  /// Sets the mem_order clause for 'atomic compare fail' directive.
+  void setMemOrderClause(OMPClause *MemoryOrderClauseParam) {
+    MemoryOrderClause = MemoryOrderClauseParam;
+  }
+public:
+  /// Build 'fail' clause.
+  ///
+  /// \param StartLoc Starting location of the clause.
+  /// \param EndLoc Ending location of the clause.
+  OMPFailClause(SourceLocation StartLoc, SourceLocation EndLoc)
+      : OMPClause(llvm::omp::OMPC_fail, StartLoc, EndLoc) {}
+
+  /// Build an empty clause.
+  OMPFailClause()
+      : OMPClause(llvm::omp::OMPC_fail, SourceLocation(), SourceLocation()) {}
+
+  static OMPFailClause *CreateEmpty(const ASTContext &C);
+  static OMPFailClause *Create(const ASTContext &C, SourceLocation StartLoc,
+                               SourceLocation EndLoc);
+
+  child_range children() {
+    return child_range(child_iterator(), child_iterator());
+  }
+
+
+  const_child_range children() const {
+    return const_child_range(const_child_iterator(), const_child_iterator());
+  }
+
+  child_range used_children() {
+    return child_range(child_iterator(), child_iterator());
+  }
+  const_child_range used_children() const {
+    return const_child_range(const_child_iterator(), const_child_iterator());
+  }
+
+  static bool classof(const OMPClause *T) {
+    return T->getClauseKind() == llvm::omp::OMPC_fail;
+  }
+
+  void initFailClause(SourceLocation LParenLoc, OMPClause *MemOClause,
+                      SourceLocation MemOrderLoc) {
+
+    setLParenLoc(LParenLoc);
+    MemoryOrderClause = MemOClause;
+    setArgumentLoc(MemOrderLoc);
+
+    OpenMPClauseKind ClauseKind = MemoryOrderClause->getClauseKind();
+    OpenMPClauseKind MemClauseKind = llvm::omp::OMPC_unknown;
+    switch(ClauseKind) {
+    case llvm::omp::OMPC_acq_rel:
+    case llvm::omp::OMPC_acquire:
+      MemClauseKind = llvm::omp::OMPC_acquire;
+      break;
+    case llvm::omp::OMPC_relaxed:
+    case llvm::omp::OMPC_release:
+      MemClauseKind = llvm::omp::OMPC_relaxed;
+      break;
+    case llvm::omp::OMPC_seq_cst:
+      MemClauseKind = llvm::omp::OMPC_seq_cst;
+      break;
+    default : break;
+    }
+    setMemOrderClauseKind(MemClauseKind);
+  }
+
+  /// Gets the location of '(' in fail clause.
+  SourceLocation getLParenLoc() const {
+    return *getTrailingObjects<SourceLocation>();
+  }
+
+  OMPClause *getMemoryOrderClause() { return MemoryOrderClause; }
+
+  const OMPClause *const_getMemoryOrderClause() const {
+    return static_cast<const OMPClause *>(MemoryOrderClause);
+  }
+
+  /// Gets the location of memoryOrder clause argument in fail clause.
+  SourceLocation getArgumentLoc() const {
+    return *std::next(getTrailingObjects<SourceLocation>(), 1);
+  }
+
+  /// Gets the dependence kind in clause for 'depobj' directive.
+  OpenMPClauseKind getMemOrderClauseKind() const {
+    return *getTrailingObjects<OpenMPClauseKind>();
+  }
+};
+
 /// This represents 'seq_cst' clause in the '#pragma omp atomic'
 /// directive.
 ///
 /// \code
 /// #pragma omp atomic seq_cst
 /// \endcode
 /// In this example directive '#pragma omp atomic' has 'seq_cst' clause.
 class OMPSeqCstClause : public OMPClause {
const_child_range used_children() const {
     return const_child_range(const_child_iterator(), const_child_iterator());
   }
 
   static bool classof(const OMPClause *T) {
     return T->getClauseKind() == llvm::omp::OMPC_relaxed;
   }
 };
 
 /// This represents clause 'private' in the '#pragma omp ...' directives.
 ///
 /// \code
 /// #pragma omp parallel private(a,b)
 /// \endcode
 /// In this example directive '#pragma omp parallel' has clause 'private'
 /// with the variables 'a' and 'b'.
 class OMPPrivateClause final
     : public OMPVarListClause<OMPPrivateClause>,
       private llvm::TrailingObjects<OMPPrivateClause, Expr *> {
   friend class OMPClauseReader;
   friend OMPVarListClause;
   friend TrailingObjects;
 
   /// Build clause with number of variables \a N.
   ///
   /// \param StartLoc Starting location of the clause.
   /// \param LParenLoc Location of '('.
   /// \param EndLoc Ending location of the clause.
   /// \param N Number of the variables in the clause.
   OMPPrivateClause(SourceLocation StartLoc, SourceLocation LParenLoc,
                    SourceLocation EndLoc, unsigned N)
       : OMPVarListClause<OMPPrivateClause>(llvm::omp::OMPC_private, StartLoc,
                                            LParenLoc, EndLoc, N) {}
 
   /// Build an empty clause.
   ///
   /// \param N Number of variables.
   explicit OMPPrivateClause(unsigned N)
       : OMPVarListClause<OMPPrivateClause>(llvm::omp::OMPC_private,
                                            SourceLocation(), SourceLocation(),
                                            SourceLocation(), N) {}
 
   /// Sets the list of references to private copies with initializers for
   /// new private variables.
   /// \param VL List of references.
   void setPrivateCopies(ArrayRef<Expr *> VL);
 
   /// Gets the list of references to private copies with initializers for
   /// new private variables.
   MutableArrayRef<Expr *> getPrivateCopies() {
     return MutableArrayRef<Expr *>(varlist_end(), varlist_size());
   }
   ArrayRef<const Expr *> getPrivateCopies() const {
     return llvm::makeArrayRef(varlist_end(), varlist_size());
   }
 
 public:
   /// Creates clause with a list of variables \a VL.
   ///
   /// \param C AST context.
   /// \param StartLoc Starting location of the clause.
   /// \param LParenLoc Location of '('.
   /// \param EndLoc Ending location of the clause.
public:
 
   using private_copies_iterator = MutableArrayRef<Expr *>::iterator;
   using private_copies_const_iterator = ArrayRef<const Expr *>::iterator;
   using private_copies_range = llvm::iterator_range<private_copies_iterator>;
   using private_copies_const_range =
       llvm::iterator_range<private_copies_const_iterator>;
 
   private_copies_range private_copies() {
     return private_copies_range(getPrivateCopies().begin(),
                                 getPrivateCopies().end());
   }
 
   private_copies_const_range private_copies() const {
     return private_copies_const_range(getPrivateCopies().begin(),
                                       getPrivateCopies().end());
   }
 
   child_range children() {
     return child_range(reinterpret_cast<Stmt **>(varlist_begin()),
                        reinterpret_cast<Stmt **>(varlist_end()));
   }
 
   const_child_range children() const {
     auto Children = const_cast<OMPPrivateClause *>(this)->children();
     return const_child_range(Children.begin(), Children.end());
   }
 
   child_range used_children() {
     return child_range(child_iterator(), child_iterator());
   }
   const_child_range used_children() const {
     return const_child_range(const_child_iterator(), const_child_iterator());
   }
 
   static bool classof(const OMPClause *T) {
     return T->getClauseKind() == llvm::omp::OMPC_private;
   }
 };
 
 /// This represents clause 'firstprivate' in the '#pragma omp ...'
 /// directives.
 ///
 /// \code
 /// #pragma omp parallel firstprivate(a,b)

clang/include/clang/AST/RecursiveASTVisitor.h

 }
 
 template <typename Derived>
 bool RecursiveASTVisitor<Derived>::VisitOMPCompareClause(OMPCompareClause *) {
   return true;
 }
 
 template <typename Derived>
+bool RecursiveASTVisitor<Derived>::VisitOMPFailClause(OMPFailClause *) {
+  return true;
+}
+
+template <typename Derived>
 bool RecursiveASTVisitor<Derived>::VisitOMPSeqCstClause(OMPSeqCstClause *) {
   return true;
 }
 
 template <typename Derived>
 bool RecursiveASTVisitor<Derived>::VisitOMPAcqRelClause(OMPAcqRelClause *) {
   return true;
 }

clang/include/clang/Basic/DiagnosticSemaKinds.td

def err_omp_atomic_compare_capture : Error<
   " '{r = x == e; if(r) {x = d;}}', or '{r = x == e; if(r) {x = d;} else {v = x;}}', where 'cond-update-stmt' can have one of the following forms: 'if(expr ordop x) {x = expr;}',"
   " 'if(x ordop expr) {x = expr;}', 'if(x == e) {x = d;}', or 'if(e == x) {x = d;}' where 'x', 'r', and 'v' are lvalue expressions with scalar type, 'expr', 'e', and 'd' are expressions with scalar type,"
   " and 'ordop' is one of '<' or '>'.">;
 def note_omp_atomic_compare: Note<
   "%select{expected compound statement|expected exactly one expression statement|expected assignment statement|expected conditional operator|expect result value to be at false expression|"
   "expect binary operator in conditional expression|expect '<', '>' or '==' as order operator|expect comparison in a form of 'x == e', 'e == x', 'x ordop expr', or 'expr ordop x'|"
   "expect lvalue for result value|expect scalar value|expect integer value|unexpected 'else' statement|expect '==' operator|expect an assignment statement 'v = x'|"
   "expect a 'if' statement|expect no more than two statements|expect a compound statement|expect 'else' statement|expect a form 'r = x == e; if (r) ...'}0">;
+def err_omp_atomic_fail_wrong_or_no_clauses : Error<"expected a memory order clause">;
+def err_omp_atomic_fail_extra_mem_order_clauses : Error<"directive '#pragma omp atomic compare fail' cannot contain more than one memory order clause">;
+def err_omp_atomic_fail_extra_clauses : Error<"directive '#pragma omp atomic compare' cannot contain more than one fail clause">;
+def err_omp_atomic_fail_no_compare : Error<"expected 'compare' clause with the 'fail' modifier">;
 def err_omp_atomic_several_clauses : Error<
   "directive '#pragma omp atomic' cannot contain more than one 'read', 'write', 'update', 'capture', or 'compare' clause">;
 def err_omp_several_mem_order_clauses : Error<
   "directive '#pragma omp %0' cannot contain more than one %select{'seq_cst', 'relaxed', |}1'acq_rel', 'acquire' or 'release' clause">;
 def err_omp_atomic_incompatible_mem_order_clause : Error<
   "directive '#pragma omp atomic%select{ %0|}1' cannot be used with '%2' clause">;
 def note_omp_previous_mem_order_clause : Note<
   "'%0' clause used here">;

clang/include/clang/Parse/Parser.h

enum class ParsedStmtContext {
     LLVM_MARK_AS_BITMASK_ENUM(InStmtExpr)
   };
 
   /// Act on an expression statement that might be the last statement in a
   /// GNU statement expression. Checks whether we are actually at the end of
   /// a statement expression and builds a suitable expression statement.
   StmtResult handleExprStmt(ExprResult E, ParsedStmtContext StmtCtx);
 
+  OMPClause *ParseOpenMPFailClause(OMPClause *Clause);
+
 public:
   Parser(Preprocessor &PP, Sema &Actions, bool SkipFunctionBodies);
   ~Parser() override;
 
   const LangOptions &getLangOpts() const { return PP.getLangOpts(); }
   const TargetInfo &getTargetInfo() const { return PP.getTargetInfo(); }
   Preprocessor &getPreprocessor() const { return PP; }
   Sema &getActions() const { return Actions; }

clang/include/clang/Sema/Sema.h

public:
   OMPClause *ActOnOpenMPUpdateClause(SourceLocation StartLoc,
                                      SourceLocation EndLoc);
   /// Called on well-formed 'capture' clause.
   OMPClause *ActOnOpenMPCaptureClause(SourceLocation StartLoc,
                                       SourceLocation EndLoc);
   /// Called on well-formed 'compare' clause.
   OMPClause *ActOnOpenMPCompareClause(SourceLocation StartLoc,
                                       SourceLocation EndLoc);
+  /// Called on well-formed 'fail' clause.
+  OMPClause *ActOnOpenMPFailClause(SourceLocation StartLoc,
+                                   SourceLocation EndLoc);
   /// Called on well-formed 'seq_cst' clause.
   OMPClause *ActOnOpenMPSeqCstClause(SourceLocation StartLoc,
                                      SourceLocation EndLoc);
   /// Called on well-formed 'acq_rel' clause.
   OMPClause *ActOnOpenMPAcqRelClause(SourceLocation StartLoc,
                                      SourceLocation EndLoc);
   /// Called on well-formed 'acquire' clause.
   OMPClause *ActOnOpenMPAcquireClause(SourceLocation StartLoc,

clang/lib/AST/OpenMPClause.cpp

const OMPClauseWithPreInit *OMPClauseWithPreInit::get(const OMPClause *C) {
   case OMPC_threadprivate:
   case OMPC_flush:
   case OMPC_depobj:
   case OMPC_read:
   case OMPC_write:
   case OMPC_update:
   case OMPC_capture:
   case OMPC_compare:
+  case OMPC_fail:
   case OMPC_seq_cst:
   case OMPC_acq_rel:
   case OMPC_acquire:
   case OMPC_release:
   case OMPC_relaxed:
   case OMPC_depend:
   case OMPC_threads:
   case OMPC_simd:
const OMPClauseWithPostUpdate *OMPClauseWithPostUpdate::get(const OMPClause *C) {
   case OMPC_threadprivate:
   case OMPC_flush:
   case OMPC_depobj:
   case OMPC_read:
   case OMPC_write:
   case OMPC_update:
   case OMPC_capture:
   case OMPC_compare:
+  case OMPC_fail:
   case OMPC_seq_cst:
   case OMPC_acq_rel:
   case OMPC_acquire:
   case OMPC_release:
   case OMPC_relaxed:
   case OMPC_depend:
   case OMPC_device:
   case OMPC_threads:
OMPUpdateClause *OMPUpdateClause::CreateEmpty(const ASTContext &C,
   void *Mem =
       C.Allocate(totalSizeToAlloc<SourceLocation, OpenMPDependClauseKind>(2, 1),
                  alignof(OMPUpdateClause));
   auto *Clause = new (Mem) OMPUpdateClause(/*IsExtended=*/true);
   Clause->IsExtended = true;
   return Clause;
 }
 
+OMPFailClause *OMPFailClause::Create(const ASTContext &C,
+                                     SourceLocation StartLoc,
+                                     SourceLocation EndLoc) {
+  void *Mem =
+      C.Allocate(totalSizeToAlloc<SourceLocation, OpenMPClauseKind>(2, 1),
+                 alignof(OMPFailClause));
+  auto *Clause =
+      new (Mem) OMPFailClause(StartLoc, EndLoc);
+  return Clause;
+}
+
+OMPFailClause *OMPFailClause::CreateEmpty(const ASTContext &C) {
+  void *Mem =
+      C.Allocate(totalSizeToAlloc<SourceLocation, OpenMPClauseKind>(2, 1),
+                 alignof(OMPFailClause));
+  auto *Clause = new (Mem) OMPFailClause();
+  return Clause;
+}
+
 void OMPPrivateClause::setPrivateCopies(ArrayRef<Expr *> VL) {
   assert(VL.size() == varlist_size() &&
          "Number of private copies is not the same as the preallocated buffer");
   std::copy(VL.begin(), VL.end(), varlist_end());
 }
 
 OMPPrivateClause *
 OMPPrivateClause::Create(const ASTContext &C, SourceLocation StartLoc,

 void OMPClausePrinter::VisitOMPCaptureClause(OMPCaptureClause *) {
   OS << "capture";
 }
 
 void OMPClausePrinter::VisitOMPCompareClause(OMPCompareClause *) {
   OS << "compare";
 }
 
+void OMPClausePrinter::VisitOMPFailClause(OMPFailClause *Node) {
+  OS << "fail";
+  if(Node) {
+    OS << "(";
+    OS << getOpenMPSimpleClauseTypeName(Node->getClauseKind(),
+                       static_cast<int>(Node->getMemOrderClauseKind()));
+    OS << ")";
+  }
+}
+
 void OMPClausePrinter::VisitOMPSeqCstClause(OMPSeqCstClause *) {
   OS << "seq_cst";
 }
 
 void OMPClausePrinter::VisitOMPAcqRelClause(OMPAcqRelClause *) {
   OS << "acq_rel";
 }
 

clang/lib/AST/StmtProfile.cpp

 void OMPClauseProfiler::VisitOMPWriteClause(const OMPWriteClause *) {}
 
 void OMPClauseProfiler::VisitOMPUpdateClause(const OMPUpdateClause *) {}
 
 void OMPClauseProfiler::VisitOMPCaptureClause(const OMPCaptureClause *) {}
 
 void OMPClauseProfiler::VisitOMPCompareClause(const OMPCompareClause *) {}
 
+void OMPClauseProfiler::VisitOMPFailClause(const OMPFailClause *) {}
+
 void OMPClauseProfiler::VisitOMPSeqCstClause(const OMPSeqCstClause *) {}
 
 void OMPClauseProfiler::VisitOMPAcqRelClause(const OMPAcqRelClause *) {}
 
 void OMPClauseProfiler::VisitOMPAcquireClause(const OMPAcquireClause *) {}
 
 void OMPClauseProfiler::VisitOMPReleaseClause(const OMPReleaseClause *) {}
 

clang/lib/Basic/OpenMPKinds.cpp

case OMPC_update:
     case OMPC_DEPEND_unknown:
       return "unknown";
 #define OPENMP_DEPEND_KIND(Name)                                               \
   case OMPC_DEPEND_##Name:                                                     \
     return #Name;
 #include "clang/Basic/OpenMPKinds.def"
     }
     llvm_unreachable("Invalid OpenMP 'depend' clause type");
+  case OMPC_fail: {
+    OpenMPClauseKind CK = static_cast<OpenMPClauseKind>(Type);
+    switch (CK) {
+    case OMPC_acquire:
+      return "acquire";
+    case OMPC_relaxed:
+      return "relaxed";
+    case OMPC_seq_cst:
+      return "seq_cst";
+    default:
+      return "unknown";
+    }
+    llvm_unreachable("Invalid OpenMP 'fail' clause modifier");
+  }
   case OMPC_device:
     switch (Type) {
     case OMPC_DEVICE_unknown:
       return "unknown";
 #define OPENMP_DEVICE_MODIFIER(Name)                                           \
   case OMPC_DEVICE_##Name:                                                     \
     return #Name;
 #include "clang/Basic/OpenMPKinds.def"

clang/lib/Parse/ParseOpenMP.cpp

case OMPC_if:
     break;
   case OMPC_nowait:
   case OMPC_untied:
   case OMPC_mergeable:
   case OMPC_read:
   case OMPC_write:
   case OMPC_capture:
   case OMPC_compare:
+  case OMPC_fail:
   case OMPC_seq_cst:
   case OMPC_acq_rel:
   case OMPC_acquire:
   case OMPC_release:
   case OMPC_relaxed:
   case OMPC_threads:
   case OMPC_simd:
   case OMPC_nogroup:
   case OMPC_unified_address:
   case OMPC_unified_shared_memory:
   case OMPC_reverse_offload:
   case OMPC_dynamic_allocators:
   case OMPC_full:
     // OpenMP [2.7.1, Restrictions, p. 9]
     //  Only one ordered clause can appear on a loop directive.
     // OpenMP [2.7.1, Restrictions, C/C++, p. 4]
     //  Only one nowait clause can appear on a for directive.
     // OpenMP [5.0, Requires directive, Restrictions]
     //   Each of the requires clauses can appear at most once on the directive.
     if (!FirstClause) {
       Diag(Tok, diag::err_omp_more_one_clause)
           << getOpenMPDirectiveName(DKind) << getOpenMPClauseName(CKind) << 0;
       ErrorFound = true;
     }
 
     Clause = ParseOpenMPClause(CKind, WrongDirective);
     break;
   case OMPC_update:
     if (!FirstClause) {
       Diag(Tok, diag::err_omp_more_one_clause)
           << getOpenMPDirectiveName(DKind) << getOpenMPClauseName(CKind) << 0;
       ErrorFound = true;
Diag(Val.getValue().LOpen, diag::err_omp_invalid_dsa)
         << getOpenMPClauseName(OMPC_default) << "5.1";
     return nullptr;
   }
   return Actions.ActOnOpenMPSimpleClause(
       Kind, Val.getValue().Type, Val.getValue().TypeLoc, Val.getValue().LOpen,
       Val.getValue().Loc, Val.getValue().RLoc);
 }
 
+OMPClause *Parser::ParseOpenMPFailClause(OMPClause *Clause) {
+
+  OMPFailClause *FailClause = static_cast<OMPFailClause *>(Clause);
+  SourceLocation LParenLoc;
+  if (Tok.is(tok::l_paren)) {
+    LParenLoc = Tok.getLocation();
+    ConsumeAnyToken();
+  } else {
+    Diag(diag::err_expected_lparen_after) << getOpenMPClauseName(OMPC_fail);
+    return Clause;
+  }
+
+
+  OpenMPClauseKind CKind = Tok.isAnnotation()
+         ? OMPC_unknown
+         : getOpenMPClauseKind(PP.getSpelling(Tok));
+  if (CKind == OMPC_unknown) {
+    Diag(diag::err_omp_expected_clause) << ("atomic compare fail");
+    return Clause;
+  }
+  OMPClause *MemoryOrderClause = ParseOpenMPClause(CKind, false);
+  SourceLocation MemOrderLoc;
+  // Store Memory Order SubClause for Sema.
+  if (MemoryOrderClause) {
+    MemOrderLoc = Tok.getLocation();
+  }
+
+  if (Tok.is(tok::r_paren)) {
+    FailClause->initFailClause(LParenLoc,MemoryOrderClause,MemOrderLoc);
+    ConsumeAnyToken();
+  } else {
+    const IdentifierInfo *Arg = Tok.getIdentifierInfo();
+    Diag(Tok, diag::err_expected_rparen_after)
+        << (Arg ? Arg->getName() : "atomic compare fail");
+  }
+
+  return Clause;
+}
+
 /// Parsing of OpenMP clauses like 'ordered'.
 ///
 ///    ordered-clause:
 ///         'ordered'
 ///
 ///    nowait-clause:
 ///         'nowait'
 ///

 ///         'nogroup'
 ///
 OMPClause *Parser::ParseOpenMPClause(OpenMPClauseKind Kind, bool ParseOnly) {
   SourceLocation Loc = Tok.getLocation();
   ConsumeAnyToken();
 
   if (ParseOnly)
     return nullptr;
-  return Actions.ActOnOpenMPClause(Kind, Loc, Tok.getLocation());
+  OMPClause *Clause = Actions.ActOnOpenMPClause(Kind, Loc, Tok.getLocation());
+  if (Kind == llvm::omp::Clause::OMPC_fail) {
+    Clause = ParseOpenMPFailClause(Clause);
+  }
+  return Clause;
 }
 
 /// Parsing of OpenMP clauses with single expressions and some additional
 /// argument like 'schedule' or 'dist_schedule'.
 ///
 ///    schedule-clause:
 ///      'schedule' '(' [ modifier [ ',' modifier ] ':' ] kind [',' expression ]
 ///      ')'
 ///
 ///    if-clause:
 ///      'if' '(' [ directive-name-modifier ':' ] expression ')'
 ///
 ///    defaultmap:
 ///      'defaultmap' '(' modifier [ ':' kind ] ')'
 ///
 ///    device-clause:
 ///      'device' '(' [ device-modifier ':' ] expression ')'
 ///
 OMPClause *Parser::ParseOpenMPSingleExprWithArgClause(OpenMPDirectiveKind DKind,
                                                       OpenMPClauseKind Kind,
                                                       bool ParseOnly) {
-  SourceLocation Loc = ConsumeToken();
+  SourceLoCation Loc = ConsumeToken();
   SourceLocation DelimLoc;
   // Parse '('.
   BalancedDelimiterTracker T(*this, tok::l_paren, tok::annot_pragma_openmp_end);
   if (T.expectAndConsume(diag::err_expected_lparen_after,
                          getOpenMPClauseName(Kind).data()))
     return nullptr;
 
   ExprResult Val;

clang/lib/Sema/SemaOpenMP.cpp

if (CS->size() == 1) {
     ErrorInfo.Error = ErrorTy::MoreThanTwoStmts;
     ErrorInfo.ErrorLoc = ErrorInfo.NoteLoc = CS->getBeginLoc();
     ErrorInfo.ErrorRange = ErrorInfo.NoteRange = CS->getSourceRange();
     return false;
   }
 
   return checkType(ErrorInfo);
 }
+
+class OpenMPAtomicFailChecker {
+
+protected:
+  Sema &SemaRef;
+  ASTContext &Context;
+
+public:
+  // Error descriptor type which will be returned to Sema
+  unsigned int ErrorNo;
+
+  OpenMPAtomicFailChecker(Sema &S) : SemaRef(S), Context(S.getASTContext()) {}
+
+  /// Check if all results conform with spec in terms of lvalue/rvalue
+  /// and scalar type.
+  bool checkSubClause(ArrayRef<OMPClause *> Clauses, SourceLocation *ErrorLoc);
+  /// Return the error descriptor that will guide the error message emission.
+  unsigned getErrorDesc() const { return ErrorNo; }
+};
+
+bool OpenMPAtomicFailChecker::checkSubClause(ArrayRef<OMPClause *> Clauses,
+                                             SourceLocation *ErrorLoc) {
+  int NoOfFails = 0;
+  ErrorNo = 0;
+  SourceLocation ClauseLoc;
+  for (const OMPClause *C : Clauses) {
+    if (C->getClauseKind() == OMPC_fail) {
+      NoOfFails++;
+      const OMPFailClause *FC = static_cast<const OMPFailClause *>(C);
+      const OMPClause *MemOrderC = FC->const_getMemoryOrderClause();
+      /* Clauses contains OMPC_fail and the subclause */
+      if (MemOrderC) {
+        OpenMPClauseKind ClauseKind = MemOrderC->getClauseKind();
+        if ((ClauseKind == OMPC_acq_rel) || (ClauseKind == OMPC_acquire) ||
+            (ClauseKind == OMPC_relaxed) || (ClauseKind == OMPC_release) ||
+            (ClauseKind == OMPC_seq_cst)) {
+          switch(ClauseKind) {
+          case OMPC_acq_rel :
+            ClauseKind = OMPC_acquire;
+            break;
+          case OMPC_release :
+            ClauseKind = OMPC_relaxed;
+            break;
+          default : break;
+          }
+          continue;
+        } else {
+          ErrorNo = diag::err_omp_atomic_fail_wrong_or_no_clauses;
+          *ErrorLoc = MemOrderC->getBeginLoc();
+          continue;
+        }
+      }
+    }
+  }
+  if (NoOfFails > 1) {
+    ErrorNo = diag::err_omp_atomic_fail_extra_clauses;
+    *ErrorLoc = ClauseLoc;
+  }
+
+  return !ErrorNo;
+}
+
 } // namespace
 
 StmtResult Sema::ActOnOpenMPAtomicDirective(ArrayRef<OMPClause *> Clauses,
                                             Stmt *AStmt,
                                             SourceLocation StartLoc,
                                             SourceLocation EndLoc) {
   // Register location of the first atomic directive.
   DSAStack->addAtomicDirectiveLoc(StartLoc);
   if (!AStmt)
     return StmtError();
 
   // 1.2.2 OpenMP Language Terminology
   // Structured block - An executable statement with a single entry at the
   // top and a single exit at the bottom.
   // The point of exit cannot be a branch out of the structured block.
   // longjmp() and throw() must not violate the entry/exit criteria.
   OpenMPClauseKind AtomicKind = OMPC_unknown;
   SourceLocation AtomicKindLoc;
   OpenMPClauseKind MemOrderKind = OMPC_unknown;
   SourceLocation MemOrderLoc;
+  llvm::omp::Clause SubClause = OMPC_unknown;
+  SourceLocation SubClauseLoc;
   bool MutexClauseEncountered = false;
   llvm::SmallSet<OpenMPClauseKind, 2> EncounteredAtomicKinds;
   for (const OMPClause *C : Clauses) {
     switch (C->getClauseKind()) {
     case OMPC_read:
     case OMPC_write:
     case OMPC_update:
       MutexClauseEncountered = true;
case OMPC_compare: {
           Diag(C->getBeginLoc(), diag::err_omp_atomic_several_clauses)
               << SourceRange(C->getBeginLoc(), C->getEndLoc());
           Diag(AtomicKindLoc, diag::note_omp_previous_mem_order_clause)
               << getOpenMPClauseName(AtomicKind);
         }
       }
       break;
     }
+    case OMPC_fail: {
+      if (AtomicKind != OMPC_compare) {
+        Diag(C->getBeginLoc(), diag::err_omp_atomic_fail_no_compare)
+            << SourceRange(C->getBeginLoc(), C->getEndLoc());
+        return StmtError();
+      }
+      SubClause = OMPC_fail;
+      SubClauseLoc = C->getBeginLoc();
+      break;
+    }
     case OMPC_seq_cst:
     case OMPC_acq_rel:
     case OMPC_acquire:
     case OMPC_release:
     case OMPC_relaxed: {
       if (MemOrderKind != OMPC_unknown) {
         Diag(C->getBeginLoc(), diag::err_omp_several_mem_order_clauses)
             << getOpenMPDirectiveName(OMPD_atomic) << 0
             << SourceRange(C->getBeginLoc(), C->getEndLoc());
         Diag(MemOrderLoc, diag::note_omp_previous_mem_order_clause)
             << getOpenMPClauseName(MemOrderKind);
       } else {
         MemOrderKind = C->getClauseKind();
         MemOrderLoc = C->getBeginLoc();
       }
       break;
if (IsCompareCapture) {
         return StmtError();
       }
       X = Checker.getX();
       E = Checker.getE();
       D = Checker.getD();
       CE = Checker.getCond();
       // We reuse IsXLHSInRHSPart to tell if it is in the form 'x ordop expr'.
       IsXLHSInRHSPart = Checker.isXBinopExpr();
+      if (SubClause == OMPC_fail) {
+        OpenMPAtomicFailChecker Checker(*this);
+        SourceLocation ErrorLoc, NoteLoc;
+        NoteLoc = ErrorLoc = Body->getBeginLoc();
+        ErrorLoc = SubClauseLoc;
+        if (!Checker.checkSubClause(Clauses,&ErrorLoc)) {
+          unsigned ErrorNo = Checker.getErrorDesc();
+          Diag(ErrorLoc, ErrorNo);
+          return StmtError();
+        }
+      }
     }
   }
 
   setFunctionHasBranchProtectedScope();
 
   return OMPAtomicDirective::Create(
       Context, StartLoc, EndLoc, Clauses, AStmt,
       {X, V, E, UE, D, CE, IsXLHSInRHSPart, IsPostfixUpdate});
case OMPC_update:
     Res = ActOnOpenMPUpdateClause(StartLoc, EndLoc);
     break;
   case OMPC_capture:
     Res = ActOnOpenMPCaptureClause(StartLoc, EndLoc);
     break;
   case OMPC_compare:
     Res = ActOnOpenMPCompareClause(StartLoc, EndLoc);
     break;
+  case OMPC_fail:
+    Res = ActOnOpenMPFailClause(StartLoc, EndLoc);
+    break;
   case OMPC_seq_cst:
     Res = ActOnOpenMPSeqCstClause(StartLoc, EndLoc);
     break;
   case OMPC_acq_rel:
     Res = ActOnOpenMPAcqRelClause(StartLoc, EndLoc);
     break;
   case OMPC_acquire:
     Res = ActOnOpenMPAcquireClause(StartLoc, EndLoc);
OMPClause *Sema::ActOnOpenMPCaptureClause(SourceLocation StartLoc,
   return new (Context) OMPCaptureClause(StartLoc, EndLoc);
 }
 
 OMPClause *Sema::ActOnOpenMPCompareClause(SourceLocation StartLoc,
                                           SourceLocation EndLoc) {
   return new (Context) OMPCompareClause(StartLoc, EndLoc);
 }
 
+OMPClause *Sema::ActOnOpenMPFailClause(SourceLocation StartLoc,
+                                       SourceLocation EndLoc) {
+  return OMPFailClause::Create(Context, StartLoc, EndLoc);
+}
+
 OMPClause *Sema::ActOnOpenMPSeqCstClause(SourceLocation StartLoc,
                                          SourceLocation EndLoc) {
   return new (Context) OMPSeqCstClause(StartLoc, EndLoc);
 }
 
 OMPClause *Sema::ActOnOpenMPAcqRelClause(SourceLocation StartLoc,
                                          SourceLocation EndLoc) {
   return new (Context) OMPAcqRelClause(StartLoc, EndLoc);
 }
 
 OMPClause *Sema::ActOnOpenMPAcquireClause(SourceLocation StartLoc,
                                           SourceLocation EndLoc) {
   return new (Context) OMPAcquireClause(StartLoc, EndLoc);
 }
 
 OMPClause *Sema::ActOnOpenMPReleaseClause(SourceLocation StartLoc,
                                           SourceLocation EndLoc) {
   return new (Context) OMPReleaseClause(StartLoc, EndLoc);
 }
 
 OMPClause *Sema::ActOnOpenMPRelaxedClause(SourceLocation StartLoc,
                                           SourceLocation EndLoc) {
   return new (Context) OMPRelaxedClause(StartLoc, EndLoc);

clang/lib/Sema/TreeTransform.h

 OMPClause *
 TreeTransform<Derived>::TransformOMPCompareClause(OMPCompareClause *C) {
   // No need to rebuild this clause, no template-dependent parameters.
   return C;
 }
 
 template <typename Derived>
 OMPClause *
+TreeTransform<Derived>::TransformOMPFailClause(OMPFailClause *C) {
+  // No need to rebuild this clause, no template-dependent parameters.
+  return C;
+}
+
+template <typename Derived>
+OMPClause *
 TreeTransform<Derived>::TransformOMPSeqCstClause(OMPSeqCstClause *C) {
   // No need to rebuild this clause, no template-dependent parameters.
   return C;
 }
 
 template <typename Derived>
 OMPClause *
 TreeTransform<Derived>::TransformOMPAcqRelClause(OMPAcqRelClause *C) {

clang/lib/Serialization/ASTReader.cpp

case llvm::omp::OMPC_update:
     C = OMPUpdateClause::CreateEmpty(Context, Record.readInt());
     break;
   case llvm::omp::OMPC_capture:
     C = new (Context) OMPCaptureClause();
     break;
   case llvm::omp::OMPC_compare:
     C = new (Context) OMPCompareClause();
     break;
+  case llvm::omp::OMPC_fail:
+    C = OMPFailClause::CreateEmpty(Context);
+    break;
   case llvm::omp::OMPC_seq_cst:
     C = new (Context) OMPSeqCstClause();
     break;
   case llvm::omp::OMPC_acq_rel:
     C = new (Context) OMPAcqRelClause();
     break;
   case llvm::omp::OMPC_acquire:
     C = new (Context) OMPAcquireClause();
if (C->isExtended()) {
     C->setDependencyKind(Record.readEnum<OpenMPDependClauseKind>());
   }
 }
 
 void OMPClauseReader::VisitOMPCaptureClause(OMPCaptureClause *) {}
 
 void OMPClauseReader::VisitOMPCompareClause(OMPCompareClause *) {}
 
+void OMPClauseReader::VisitOMPFailClause(OMPFailClause *C) {
+  C->setLParenLoc(Record.readSourceLocation());
+  SourceLocation SourceLoc = Record.readSourceLocation();
+  C->setArgumentLoc(SourceLoc);
+  OpenMPClauseKind CKind = Record.readEnum<OpenMPClauseKind>();
+  C->setMemOrderClauseKind(CKind);
+
+  SourceLocation EndLoc;
+  OMPClause *MemoryOrderClause = NULL;
+  switch(CKind) {
+  case llvm::omp::OMPC_acquire:
+    MemoryOrderClause = new (Context) OMPAcquireClause(SourceLoc, EndLoc);
+    break;
+  case llvm::omp::OMPC_relaxed:
+    MemoryOrderClause = new (Context) OMPRelaxedClause(SourceLoc, EndLoc);
+    break;
+  case llvm::omp::OMPC_seq_cst:
+    MemoryOrderClause = new (Context) OMPSeqCstClause(SourceLoc, EndLoc);
+    break;
+  default:
+    break;
+  }
+  C->setMemOrderClause(MemoryOrderClause);
+}
+
 void OMPClauseReader::VisitOMPSeqCstClause(OMPSeqCstClause *) {}
 
 void OMPClauseReader::VisitOMPAcqRelClause(OMPAcqRelClause *) {}
 
 void OMPClauseReader::VisitOMPAcquireClause(OMPAcquireClause *) {}
 
 void OMPClauseReader::VisitOMPReleaseClause(OMPReleaseClause *) {}
 

clang/lib/Serialization/ASTWriter.cpp

if (C->isExtended()) {
     Record.writeEnum(C->getDependencyKind());
   }
 }
 
 void OMPClauseWriter::VisitOMPCaptureClause(OMPCaptureClause *) {}
 
 void OMPClauseWriter::VisitOMPCompareClause(OMPCompareClause *) {}
 
+void OMPClauseWriter::VisitOMPFailClause(OMPFailClause *C) {
+  // Record.AddSourceLocation(C->getLParenLoc());
+  // Copied from VisitOMPUpdateClause
+  Record.AddSourceLocation(C->getLParenLoc());
+  Record.AddSourceLocation(C->getArgumentLoc());
+  Record.writeEnum(C->getMemOrderClauseKind());
+}
+
 void OMPClauseWriter::VisitOMPSeqCstClause(OMPSeqCstClause *) {}
 
 void OMPClauseWriter::VisitOMPAcqRelClause(OMPAcqRelClause *) {}
 
 void OMPClauseWriter::VisitOMPAcquireClause(OMPAcquireClause *) {}
 
 void OMPClauseWriter::VisitOMPReleaseClause(OMPReleaseClause *) {}
 

clang/test/OpenMP/atomic_ast_print.cpp

 #pragma omp atomic compare hint(6)
   { a = a == b ? c : a; }
 #pragma omp atomic compare capture hint(6)
   { v = a; if (a > b) { a = b; } }
 #pragma omp atomic compare hint(6) capture
   { v = a; if (a < b) { a = b; } }
 #pragma omp atomic compare capture hint(6)
   { v = a == b; if (v) a = c; }
+#pragma omp atomic compare fail(acq_rel)
+  { if (a < c) { a = c; } }
+#pragma omp atomic compare fail(acquire)
+  { if (a < c) { a = c; } }
+#pragma omp atomic compare fail(release)
+  { if (a < c) { a = c; } }
+#pragma omp atomic compare fail(relaxed)
+  { if (a < c) { a = c; } }
+#pragma omp atomic compare fail(seq_cst)
+  { if (a < c) { a = c; } }
 #endif
   return T();
 }
 
 // CHECK: T a = T();
 // CHECK-NEXT: #pragma omp atomic{{$}}
 // CHECK-NEXT: a++;
 // CHECK-NEXT: #pragma omp atomic read

 #pragma omp atomic compare hint(6)
   { a = a == b ? c : a; }
 #pragma omp atomic compare capture hint(6)
   { v = a; if (a > b) { a = b; } }
 #pragma omp atomic compare hint(6) capture
   { v = a; if (a < b) { a = b; } }
 #pragma omp atomic compare capture hint(6)
   { v = a == b; if (v) a = c; }
+#pragma omp atomic compare fail(acq_rel)
+  if(a < b) { a = b; }
+#pragma omp atomic compare fail(acquire)
+  if(a < b) { a = b; }
+#pragma omp atomic compare fail(release)
+  if(a < b) { a = b; }
+#pragma omp atomic compare fail(relaxed)
+  if(a < b) { a = b; }
+#pragma omp atomic compare fail(seq_cst)
+  if(a < b) { a = b; }
 #endif
   // CHECK-NEXT: #pragma omp atomic
   // CHECK-NEXT: a++;
   // CHECK-NEXT: #pragma omp atomic read
   // CHECK-NEXT: a = argc;
   // CHECK-NEXT: #pragma omp atomic write
   // CHECK-NEXT: a = argc + argc;
   // CHECK-NEXT: #pragma omp atomic update
#endif
   // CHECK-51-NEXT: }
   // CHECK-51-NEXT: }
   // CHECK-51-NEXT: #pragma omp atomic compare capture hint(6)
   // CHECK-51-NEXT: {
   // CHECK-51-NEXT: v = a == b;
   // CHECK-51-NEXT: if (v)
   // CHECK-51-NEXT: a = c;
   // CHECK-51-NEXT: }
+  // CHECK-51-NEXT: #pragma omp atomic compare fail(acquire)
+  // CHECK-51-NEXT: if (a < b) {
+  // CHECK-51-NEXT: a = b;
+  // CHECK-51-NEXT: }
+  // CHECK-51-NEXT: #pragma omp atomic compare fail(acquire)
+  // CHECK-51-NEXT: if (a < b) {
+  // CHECK-51-NEXT: a = b;
+  // CHECK-51-NEXT: }
+  // CHECK-51-NEXT: #pragma omp atomic compare fail(relaxed)
+  // CHECK-51-NEXT: if (a < b) {
+  // CHECK-51-NEXT: a = b;
+  // CHECK-51-NEXT: }
+  // CHECK-51-NEXT: #pragma omp atomic compare fail(relaxed)
+  // CHECK-51-NEXT: if (a < b) {
+  // CHECK-51-NEXT: a = b;
+  // CHECK-51-NEXT: }
+  // CHECK-51-NEXT: #pragma omp atomic compare fail(seq_cst)
+  // CHECK-51-NEXT: if (a < b) {
+  // CHECK-51-NEXT: a = b;
+  // CHECK-51-NEXT: }
   // expect-note@+1 {{in instantiation of function template specialization 'foo<int>' requested here}}
   return foo(a);
 }
 
 #endif

clang/test/OpenMP/atomic_messages.cpp

 // expected-error@+2 {{directive '#pragma omp atomic' cannot contain more than one 'read', 'write', 'update', 'capture', or 'compare' clause}}
 // expected-note@+1 {{'read' clause used here}}
 #pragma omp atomic read compare
   a = b;
 // expected-error@+2 {{directive '#pragma omp atomic' cannot contain more than one 'compare' clause}}
 // expected-error@+1 {{directive '#pragma omp atomic' cannot contain more than one 'capture' clause}}
 #pragma omp atomic compare compare capture capture
   { v = a; if (a > b) a = b; }
+// expected-error@+1 {{expected 'compare' clause with the 'fail' modifier}}
+#pragma omp atomic fail(seq_cst)
+  if(v == a) { v = a; }
+// expected-error@+1 {{expected '(' after 'fail'}}
+#pragma omp atomic compare fail
+  if(v < a) { v = a; }
+// expected-error@+1 {{expected a memory order clause}}
+#pragma omp atomic compare fail(capture)
+  if(v < a) { v = a; }
+ // expected-error@+2 {{expected ')' after 'atomic compare fail'}}
+ // expected-warning@+1 {{extra tokens at the end of '#pragma omp atomic' are ignored}}
+#pragma omp atomic compare fail(seq_cst | acquire)
+  if(v < a) { v = a; }
+// expected-error@+1 {{directive '#pragma omp atomic' cannot contain more than one 'fail' clause}}
+#pragma omp atomic compare fail(relaxed) fail(seq_cst)
+  if(v < a) { v = a; }
+
+
 #endif
   // expected-note@+1 {{in instantiation of function template specialization 'mixed<int>' requested here}}
   return mixed<int>();
 }

clang/tools/libclang/CIndex.cpp

 void OMPClauseEnqueue::VisitOMPWriteClause(const OMPWriteClause *) {}
 
 void OMPClauseEnqueue::VisitOMPUpdateClause(const OMPUpdateClause *) {}
 
 void OMPClauseEnqueue::VisitOMPCaptureClause(const OMPCaptureClause *) {}
 
 void OMPClauseEnqueue::VisitOMPCompareClause(const OMPCompareClause *) {}
 
+void OMPClauseEnqueue::VisitOMPFailClause(const OMPFailClause *) {}
+
 void OMPClauseEnqueue::VisitOMPSeqCstClause(const OMPSeqCstClause *) {}
 
 void OMPClauseEnqueue::VisitOMPAcqRelClause(const OMPAcqRelClause *) {}
 
 void OMPClauseEnqueue::VisitOMPAcquireClause(const OMPAcquireClause *) {}
 
 void OMPClauseEnqueue::VisitOMPReleaseClause(const OMPReleaseClause *) {}
 

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

 CHECK_SIMPLE_CLAUSE(When, OMPC_when)
 CHECK_SIMPLE_CLAUSE(AdjustArgs, OMPC_adjust_args)
 CHECK_SIMPLE_CLAUSE(AppendArgs, OMPC_append_args)
 CHECK_SIMPLE_CLAUSE(MemoryOrder, OMPC_memory_order)
 CHECK_SIMPLE_CLAUSE(Bind, OMPC_bind)
 CHECK_SIMPLE_CLAUSE(Align, OMPC_align)
 CHECK_SIMPLE_CLAUSE(Compare, OMPC_compare)
 CHECK_SIMPLE_CLAUSE(CancellationConstructType, OMPC_cancellation_construct_type)
+CHECK_SIMPLE_CLAUSE(Fail, OMPC_fail)
 
 CHECK_REQ_SCALAR_INT_CLAUSE(Grainsize, OMPC_grainsize)
 CHECK_REQ_SCALAR_INT_CLAUSE(NumTasks, OMPC_num_tasks)
 CHECK_REQ_SCALAR_INT_CLAUSE(NumTeams, OMPC_num_teams)
 CHECK_REQ_SCALAR_INT_CLAUSE(NumThreads, OMPC_num_threads)
 CHECK_REQ_SCALAR_INT_CLAUSE(Priority, OMPC_priority)
 CHECK_REQ_SCALAR_INT_CLAUSE(ThreadLimit, OMPC_thread_limit)
 CHECK_REQ_SCALAR_INT_CLAUSE(Device, OMPC_device)

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

 def OMPC_Mergeable : Clause<"mergeable"> {
   let clangClass = "OMPMergeableClause";
 }
 def OMPC_Read : Clause<"read"> { let clangClass = "OMPReadClause"; }
 def OMPC_Write : Clause<"write"> { let clangClass = "OMPWriteClause"; }
 def OMPC_Update : Clause<"update"> { let clangClass = "OMPUpdateClause"; }
 def OMPC_Capture : Clause<"capture"> { let clangClass = "OMPCaptureClause"; }
 def OMPC_Compare : Clause<"compare"> { let clangClass = "OMPCompareClause"; }
+def OMPC_Fail : Clause<"fail"> { let clangClass = "OMPFailClause"; }
 def OMPC_SeqCst : Clause<"seq_cst"> { let clangClass = "OMPSeqCstClause"; }
 def OMPC_AcqRel : Clause<"acq_rel"> { let clangClass = "OMPAcqRelClause"; }
 def OMPC_Acquire : Clause<"acquire"> { let clangClass = "OMPAcquireClause"; }
 def OMPC_Release : Clause<"release"> { let clangClass = "OMPReleaseClause"; }
 def OMPC_Relaxed : Clause<"relaxed"> { let clangClass = "OMPRelaxedClause"; }
 def OMPC_Depend : Clause<"depend"> {
   let clangClass = "OMPDependClause";
   let flangClass = "OmpDependClause";
let allowedClauses = [
     VersionedClause<OMPC_Compare, 51>
   ];
   let allowedOnceClauses = [
     VersionedClause<OMPC_SeqCst>,
     VersionedClause<OMPC_AcqRel, 50>,
     VersionedClause<OMPC_Acquire, 50>,
     VersionedClause<OMPC_Release, 50>,
     VersionedClause<OMPC_Relaxed, 50>,
-    VersionedClause<OMPC_Hint, 50>
+    VersionedClause<OMPC_Hint, 50>,
+    VersionedClause<OMPC_Fail, 51>
   ];
 }
 def OMP_Target : Directive<"target"> {
   let allowedClauses = [
     VersionedClause<OMPC_If>,
     VersionedClause<OMPC_Map>,
     VersionedClause<OMPC_Private>,
     VersionedClause<OMPC_Depend>,