lildmh marked an inline comment as done.
lildmh added inline comments.
================
Comment at: lib/AST/DeclOpenMP.cpp:164
+ if (NumClauses) {
+ Clauses = (OMPClause **)C.Allocate(sizeof(OMPClause *) * NumClauses);
+ setClauses(CL);
----------------
ABataev wrote:
> lildmh wrote:
> > ABataev wrote:
> > > lildmh wrote:
> > > > ABataev wrote:
> > > > > No, bad idea. Use tail allocation for the clauses. Check the
> > > > > implementation of `OMPRequiresDecl`
> > > > I think it is possible to use TrailingObjects for clause storage when
> > > > the number of clauses are known before creating the directive (e.g.,
> > > > for OMPRequiresDecl and OMPExecutableDirective).
> > > >
> > > > The reason that I had to create OMPDeclareMapperDecl before parsing map
> > > > clauses, is the mapper variable (AA in the example below) needs to be
> > > > declared within OMPDeclareMapperDecl, because the following map clauses
> > > > will use it.
> > > >
> > > > ```
> > > > #pragma omp declare mapper(struct S AA) map(AA.field1)
> > > > ```
> > > >
> > > > A possible way to get around this is to count the number of map clauses
> > > > before hand. But this solution is not trivial since the normal method
> > > > for parsing map clauses cannot be used (e.g., it does not know AA when
> > > > parsing map(AA.field1)). A customized and complex (because it needs to
> > > > handle all possible situations) parsing method needs to be created,
> > > > just for counting clause number. I think it's not worthy to do this
> > > > compared with allocating map clause space later.
> > > >
> > > > I checked the code for OMPDeclareReductionDecl that you wrote. It also
> > > > has to be created before parsing the combiner and initializer. It does
> > > > not have a variable number of clauses though.
> > > >
> > > > Any suggestions?
> > > Instead, you can introduce special DeclContext-based declaration and keep
> > > the reference to this declaration inside of the `OMPDeclareMapperDecl`.
> > Hi Alexey,
> >
> > Thanks a lot for your quick response! I don't think I understand your idea.
> > Can you establish more on that?
> >
> > In my current implementation, OMPDeclareMapperDecl is used as the
> > DeclConext of the variable AA in the above example, and it already includes
> > the reference to AA's declaration.
> >
> > My problem is, I need to create OMPDeclareMapperDecl before parsing map
> > clauses. But before parsing map clauses, I don't know the number of
> > clauses. Using TrailingObject requires to know how many clauses there are
> > when creating OMPDeclareMapperDecl. So I couldn't use TrailingObject.
> >
> > My current solution is to create OMPDeclareMapperDecl before parsing map
> > clauses, and to create the clause storage after parsing finishes.
> What I meant, that you don't need to use `OMPDeclareMapperDecl` for this,
> instead you can add another (very simple) special declaration based on
> `DeclContext` to use it as the parent declaration for the variable. In the
> `OMPDeclareMapperDecl` you can keep the reference to this special declaration.
Thanks for your response! Please let me know if my understanding below is
correct:
`OMPDeclareMapperDecl` no longer inherits from `DeclContext`. Instead, we
create something like `OMPDeclareMapperDeclContext` which inherits from
`DeclContext`, and `OMPDeclareMapperDecl` keeps a pointer that points to this
`OMPDeclareMapperDeclContext`. AA and map clauses are parsed within
`OMPDeclareMapperDeclContext`.
This sounds a bit more complex, but if you believe it's better, I can change
the code. Please share your thoughts.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D56326/new/
https://reviews.llvm.org/D56326
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