[PATCH] D99888: [flang][OpenMP] Add semantic checks for occurrence of nested Barrier regions

[Arnamoy B via Phabricator via llvm-commits]

arnamoy10 added inline comments.


================
Comment at: flang/lib/Semantics/check-omp-structure.cpp:462
+    if (CurrentDirectiveIsNested() &&
+        llvm::omp::nestedBarrierErrSet.test(GetContextParent().directive)) {
+      context_.Say(parser::FindSourceLocation(x),
----------------
kiranchandramohan wrote:
> arnamoy10 wrote:
> > kiranchandramohan wrote:
> > > arnamoy10 wrote:
> > > > kiranchandramohan wrote:
> > > > > Definition of closely nested region is 
> > > > > "A region nested inside another region with no parallel region nested between them."
> > > > > 
> > > > > Does this check capture this definition correctly?
> > > > Thanks for pointing in out.
> > > > 
> > > > 1.  Just double checking -- is //parallel region// a region enclosed by the `!$omp parallel` construct?
> > > > 2. IIUC, [[ https://github.com/llvm/llvm-project/blob/0116d04d04f20e9ae62ba847075840c3cb298080/flang/lib/Semantics/check-omp-structure.cpp#L130 | this ]] check (by which my code was inspired) also does not cover the definition of "close nesting"?  Please confirm.
> > > > 
> > > 1. Yes. But it is a dynamic concept, i.e it is the body of code executed during the execution.
> > > 2. Yes that code also does not cover the definition. Will appreciate a fix.
> > I need one more clarification before implementing the fix.
> > 
> > From the definition:
> > 
> > ```A region nested inside another region with no parallel region nested between them```
> > 
> > What does nesting "between" mean?  I can think of two cases.
> > 
> > Case 1:
> > 
> > ```
> > !$omp ordered
> >   !$omp parallel <-- Child of ordered
> >     !$omp barrier <-- Child of parallel, grandchild of ordered
> > ```
> > 
> > Case 2:
> > 
> > ```
> > !$omp ordered
> >   !$omp parallel <-- Child of ordered
> >   !$omp barrier <-- Child of ordered
> > ```
> > 
> > Can you comment on which one of the above two cases has a `barrier` closely nested inside the `ordered` construct?
> > 
> Case 2 has a barrier closely nested inside ordered. 
Thanks.

So IIUC, basically if your //immediate// parent (say region1) is **not** a `!$omp parallel`, then you are closely nested inside region1.

If that is the case, IMO we do not need a fix.  Because `GetContextParent()` gives us our immediate parent.


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  https://reviews.llvm.org/D99888/new/

https://reviews.llvm.org/D99888