Re: [PATCH] add support for placing variables in shared memory

[Alexander Monakov <amonakov@ispras.ru>]

On Thu, 21 Apr 2016, Nathan Sidwell wrote:
> On 04/20/16 12:58, Alexander Monakov wrote:
> > Allow using __attribute__((shared)) to place static variables in '.shared'
> > memory space.
> 
> What is the rationale for a new attribute, rather than leveraging the existing
> section(".shared") machinery?

Section switching does not work at all on NVPTX in GCC at present.  PTX
assembly has no notion of different data sections, so the backend does not
advertise section switching capability to the middle end.

CUDA C does it via attributes too, and there's no point in diverging
gratuitously I think.

> > +  else if (current_function_decl && !TREE_STATIC (decl))
> > +    {
> > +      error ("%qE attribute only applies to non-stack variables", name);
> 
> 'non-stack'?  don't you mean 'static' or 'static storage'?

I avoided using 'static' because it applies to external declarations as well.
Other backends use "%qE attribute not allowed with auto storage class"; I'll
be happy to switch to that for consistency.

> Needs a test case.

OK, will follow up with a testcase.

Thanks.
Alexander