Re: Handling of large stack objects in GPU code generation -- maybe transform into heap allocation?

[Janne Blomqvist <blomqvist.janne@gmail.com>]

On Fri, Nov 11, 2022 at 4:13 PM Thomas Schwinge <thomas@codesourcery.com> wrote:
> For example, for Fortran code like:
>
>     write (*,*) "Hello world"
>
> ..., 'gfortran' creates:

> The issue: the stack object 'dt_parm.0' is a half-KiB in size (yes,
> really! -- there's a lot of state in Fortran I/O apparently).

> Any other clever ideas?

There's a lot of potential options to set during Fortran I/O, but in
the vast majority of cases only a few are used. So a better library
interface would be to transfer only those options that are used, and
then let the full set of options live in heap memory managed by
libgfortran. Say some kind of simple byte-code format, with an
'opcode' saying which option it is, followed by the value.

See also https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48419 for some
rough ideas in this direction, although I'm not personally working on
GFortran at this time so somebody else would have to pick it up.


-- 
Janne Blomqvist