[PATCH] D84192: [OpenMP5.0] map item can be non-contiguous for target update

[Chi Chun Chen via Phabricator via cfe-commits]

cchen added a comment.

In D84192#2165438 <https://reviews.llvm.org/D84192#2165438>, @ABataev wrote:

> In D84192#2165396 <https://reviews.llvm.org/D84192#2165396>, @cchen wrote:
>
> > In D84192#2165249 <https://reviews.llvm.org/D84192#2165249>, @ABataev wrote:
> >
> > > In D84192#2165235 <https://reviews.llvm.org/D84192#2165235>, @cchen wrote:
> > >
> > > > In D84192#2164885 <https://reviews.llvm.org/D84192#2164885>, @ABataev wrote:
> > > >
> > > > > Also, what about compatibility with declare mapper? Can you add tests for it?
> > > >
> > > >
> > > > There's a restriction for map clause that non-contiguous is not allowed and I guess it also applies to declare mapper.
> > >
> > >
> > > I see that to/from clauses allow to use mappers too:
> > >
> > >   to([mapper(mapper-identifier):]locator-list) from([mapper(mapper-identifier):]locator-list
> > >   
> >
> >
> > I'm confused of how to use to([mapper(mapper-identifier):]locator-list) with array section.
> >  For this case:
> >
> >   class C {
> >   public:
> >     int a;
> >     double b[3][4][5];
> >   };
> >  
> >   #pragma omp declare mapper(id: C s) map(s.a, s.b[0:3][0:4][0:5])
> >  
> >   #pragma omp target update from(mapper(id): c)
> >
> >
> > Clang already has a semantic check in from clause when mapper is used: "mapper type must be of struct, union or class type".
> >  So the only item I can put in from clause in the above example is `c` and I cannot put c.b[0:2][1:2][0:2] or any even c.b[0:2].
>
>
> Does clang compile your example? If not, shall it be allowed for to/from clauses or not?


Clang can compile my example but the problem is that Clang do not accept something like `#pragma omp target update from(mapper(id): c.b[0:2][1:2][2:2])` (non-contiguous) or even `#pragma omp target update from(mapper(id): c.b[2][1][0:2])` (contiguous).
Actually, Clang now only accepts `c` as struct/union/class type in `from(mapper(id): c)`. And the reason for the restriction is from declare mapper directive - "The type must be of struct, union or class type in C and C++".


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