[clang] [OpenMP][CodeGen] Improved codegen for combined loop directives (PR #72417)

[via cfe-commits]

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@@ -7485,6 +7485,99 @@ void CodeGenModule::printPostfixForExternalizedDecl(llvm::raw_ostream &OS,
   }
 }
 
+namespace {
+/// A 'teams loop' with a nested 'loop bind(parallel)' or generic function
+/// call in the associated loop-nest cannot be a 'parllel for'.
+class TeamsLoopChecker final : public ConstStmtVisitor<TeamsLoopChecker> {
+public:
+  TeamsLoopChecker(CodeGenModule &CGM)
+      : CGM(CGM), TeamsLoopCanBeParallelFor{true} {}
+  bool teamsLoopCanBeParallelFor() const {
+    return TeamsLoopCanBeParallelFor;
+  }
+  // Is there a nested OpenMP loop bind(parallel)
+  void VisitOMPExecutableDirective(const OMPExecutableDirective *D) {
+    if (D->getDirectiveKind() == llvm::omp::Directive::OMPD_loop) {
+      if (const auto *C = D->getSingleClause<OMPBindClause>())
+        if (C->getBindKind() == OMPC_BIND_parallel) {
+          TeamsLoopCanBeParallelFor = false;
+          // No need to continue visiting any more
+          return;
+        }
+    }
+    for (const Stmt *Child : D->children())
+      if (Child)
+        Visit(Child);
+  }
+
+  void VisitCallExpr(const CallExpr *C) {
+    // Function calls inhibit parallel loop translation of 'target teams loop'
+    // unless the assume-no-nested-parallelism flag has been specified.
+    // OpenMP API runtime library calls do not inhibit parallel loop
+    // translation, regardless of the assume-no-nested-parallelism.
+    if (C) {
+      bool IsOpenMPAPI = false;
+      auto *FD = dyn_cast_or_null<FunctionDecl>(C->getCalleeDecl());
+      if (FD) {
+        std::string Name = FD->getNameInfo().getAsString();
+        IsOpenMPAPI = Name.find("omp_") == 0;
----------------
dhruvachak wrote:

> No, it is not.

I see the following in the spec:
```
 Programs must not declare names that begin with the omp_ or ompx_ prefix, as these are reserved for the OpenMP implementation.
```

https://github.com/llvm/llvm-project/pull/72417