[PATCH] D76342: [OpenMP] Implement '#pragma omp tile'

[Michael Kruse via Phabricator via cfe-commits]

Meinersbur marked an inline comment as done.
Meinersbur added inline comments.


================
Comment at: clang/include/clang/AST/StmtOpenMP.h:4781-4784
+/// This represents the '#pragma omp tile' loop transformation directive.
+class OMPTileDirective final
+    : public OMPLoopDirective,
+      private llvm::TrailingObjects<OMPTileDirective, OMPClause *, Stmt *> {
----------------
ABataev wrote:
> Meinersbur wrote:
> > ABataev wrote:
> > > Not sure that this is a good idea to treat this directive as the executable directive. To me, it looks like kind of `AttributedStmt`. Maybe better to introduce some kind of a new base node for this and similar constructs, which does not own the loop but is its kind of attribute-like entity?
> > > Also, can we have something like:
> > > ```
> > > #pragma omp simd
> > > #pragma omp tile ...
> > > for(...) ;
> > > ```
> > > Thoughts?
> > While not executed at runtime, syntactically it is parsed like a executable (loop-associated) directive. IMHO it does 'own' the loop, but produces another one for to be owned(/associated) by a different directive, as in your tile/simd example, which should already work. Allowing this was the motivation to do the transformation on the AST-level for now.
> I'm not saying that we should separate parsing of this directive from others, it is just better to treat this directive as a little bit different node. Currently, it introduces too many changes in the base classes. Better to create a new base class, that does not relies on `CapturedStmt` as the base, and derive `OMPExecutableDirective` and this directive and other similar (+ maybe, `OMPSimdDirective`) from this new base class.
Unless you tell me otherwise, `OMPLoopDirective` represents a loop-associated directive. `#pragma omp tile` is a loop-associated directive. `OMPLoopDirective` contains all the functionality to parse associated loops, and unfortunately if derived from `OMPExecutableDirective`.

You seem to ask me to create a new class "OMPDirectiveAssociatedWithLoopButNotExecutable" that duplicates the parsing part of "OMPLoopDirective"? This will either be a lot of duplicated code or result in even more changes to the base classes due to the refactoring.

By the OpenMP specification, simd and tile are executable directives, so structurally I think the class hierarchy as-is makes sense. From the glossary of the upcoming OpenMP 5.1:
> An OpenMP directive that appears in an executable context and results in implementation code and/or prescribes the manner in which associated user code must execute.

Avoiding a CapturedStmt when not needed would a modification of `clang::getOpenMPCaptureRegions` which currently adds a capture of type `OMPD_unknown` for such directives. This is unrelated to loop-associated directives.



Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D76342/new/

https://reviews.llvm.org/D76342