GSoC Separate Host Process Offloading

[Prasad, Adi]

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