[clang] [CIR][OpenMP] Enable lowering of the OpenMP dialect to LLVM IR (PR #178515)

[Jan Leyonberg via cfe-commits]

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@@ -149,9 +149,7 @@ void CIRGenerator::HandleTagDeclDefinition(TagDecl *d) {
   // inline initializers as definitions.
   if (astContext->getTargetInfo().getCXXABI().isMicrosoft())
     cgm->errorNYI(d->getSourceRange(), "HandleTagDeclDefinition: MSABI");
-  // For OpenMP emit declare reduction functions, if required.
-  if (astContext->getLangOpts().OpenMP)
-    cgm->errorNYI(d->getSourceRange(), "HandleTagDeclDefinition: OpenMP");
+  // TODO(OMP): For OpenMP emit declare reduction functions, if required.
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jsjodin wrote:

I took a look at this function in the old clang generation, which this is essentially a copy of. I took the specific cases for OpenMP from ModuleBuilder.cpp:HandleTagDeclDefinition() and added errorNYI calls for those here. 

I cannot write a test since using declare target gives this error first:
main.c:3:39: error: ClangIR code gen Not Yet Implemented: OpenMP
      OMPDeclareReduction
    3 | #pragma omp declare reduction (mysum: int : omp_out = omp_out + omp_in)
      |   
This should reflect what is not yet implemented correctly at least.

https://github.com/llvm/llvm-project/pull/178515