zahiraam wrote:
> > @alexey-bataev - I understand the current implementation is fundamentally
> > broken. Before implementing a fix, I want to confirm the following correct
> > approach.
> > Parser:
> >
> > 1. Parse each variant directive completely including all clauses.
> > 2. Do not parse the associated statement (body).
> > 3. Return complete directive AST nodes with nullptr body.
> > 4. Parse the shared body once after all variants.
> > 5. Pass complete directive (nodes + shared body) to Sema.
> >
> > Sema:
> >
> > 1. Receive complete directive ASTs (with all clauses) and shared body.
> > 2. Set the shared body on each variant directive.
> > 3. Build IfStmt branching between complete directive nodes.
> > 4. Wrap in OMPMetaDirective.
> >
> > Example: #pragma omp metadirective when(user={condition(flag)}: parallel
> > num_threads(4)) otherwise(single nowait) { foo(); }
> > Parser produces:
> >
> > * OMPParallelDirective with num_threads(4) clause, body=nullptr
> > * OMPSingleDirective with nowait clause, body=nullptr
> > * Shared body: { foo(); }
> >
> > Sema produces: IfStmt(flag, then: OMPParallelDirective(num_threads(4)) {
> > foo(); }, else: OMPSingleDirective(nowait) { foo(); } )
> > Is this the correct approach? Thanks.
>
> Couple question:
>
> > 3. Return complete directive AST nodes with nullptr body.
>
> Why? We have to parse all directives completely, including all clauses, then
> parse the body and attach to the meta directive, which includes all other
> directives + clauses, like selectors.
>
> > 5. Pass complete directive (nodes + shared body) to Sema.
> > 6. Receive complete directive ASTs (with all clauses) and shared body.
>
> It should be done in Sema, Sema builds AST nodes, Parser just parses it,
> nothing else.
>
> > 2. Set the shared body on each variant directive.
>
> Hmm, why do wee need it? We need to build a metadirective, which will include
> all the stuff, and the single body should be attached to a metadirective.
> Upon lowering, metadirective codegen should correctly dispatch this body to
> the proper lowering function.
>
> > 3. Build IfStmt branching between complete directive nodes.
>
> You do not need it in AST, you can do it in codegen.
Thank you for the clarification. Let me confirm my understanding:
1. Parser: Parse all variant directives completely (including clauses) by
calling the normal directive parsing path. Parse the body once.
2. Sema: Build variant directive AST nodes (with clauses but no body). Build
metadirective containing the variant directives and attach the single body to
the metadirective itself.
3. AST Structure: Metadirective contains variant directives (templates with
clauses) + single body. NO IfStmt in AST.
4. Codegen: Generate if-else chain at codegen time, dispatching the
metadirective's body to the appropriate variant directive's lowering function
based on conditions.
https://github.com/llvm/llvm-project/pull/192455
_______________________________________________
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
