RE: GSoC Separate Host Process Offloading

["Prasad, Adi" <adi.prasad21@imperial.ac.uk>]

Hi Tobias and Thomas,
My apologies for the double email; I have an unrelated administrative ask. Would it be possible to provide any past successful GSoC proposals? I'm interested in any thnigs GCC specifically is looking for in proposals (I've seen quite a few generic guides on the web but none specific to GCC).

Thanks,
Adi

> -----Original Message-----
> From: Prasad, Adi
> Sent: Saturday, April 1, 2023 4:16 AM
> To: 'Tobias Burnus' <tobias@codesourcery.com>; Thomas Schwinge
> <thomas@codesourcery.com>
> Cc: gcc@gcc.gnu.org
> Subject: RE: GSoC Separate Host Process Offloading
> 
> Hi Tobias,
> Thanks for the reply!
> 
> >
> > Note that multiple offload targets are possible. For instance, on
> > Debian/Ubuntu, 'gcc -v' shows:
> > 'OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa' and lto-wrapper
> then
> > cycles through those, finding the offloading compiler in
> > $PATH/accel/<triple>/mkoffload
> >
> > Example: x86_64-none-linux-gnu/12.2.1/accel/amdgcn-amdhsa/mkoffload
> >
> > Thus, if you install it to 'x86_64-none-linux-gnu' and add it to
> > OFFLOAD_TARGET_NAMES,* it will work; albeit, we probably want to have
> > some special handling in gcc.cc to avoid host-process offloading by
> > default and permit something like -foffload=host instead of having to
> > specify -foffload=x86_64-none-linux-gnu
> >
> Understood. Forgive me if I'm misunderstanding this, but I wonder if it might be
> better to put the new mkoffload in an "accel/host" directory, and add "host" to
> OFFLOAD_TARGET_NAMES rather than have the specific host e.g. "x86_64-none-
> linux-gnu"? This would 1) enable the use of "-foffload=host" automatically and 2)
> distinguish between compiling for the same device on a separate process versus
> compiling to a separate device with the same architecture and kernel as the host.
> I can imagine this clash wouldn’t happen in practice, since compiling for a
> separate host process would target CPUs while compiling for a separate device
> would target GPUs, but it might be nicer to keep them conceptually separate all
> the same.
> 
> > I think it would be useful to start posting patches early – such that
> > they can be reviewed and discussed. Thus, this is not really the 4th
> > and 5th item.
> >
> I can post patches every week instead since my proposal will set a milestone
> target for each week.
> Additionally, what do you think about me doing some other small tasks besides
> the proposed scope? What I was thinking about specifically was that it might be
> helpful to get the offloading documentation page up to date and add info on
> OpenACC.
> 
> > No quick idea for work items – maybe I get one – or Thomas does :-)
> >
> > Tobias
> >
> Thank you so much for all the info, and do let me know if any small tasks come
> up!
> Adi