[Nouveau] NV50 compute support questions

[Hans de Goede]

Hi,

On 20-11-15 17:07, Samuel Pitoiset wrote:
>
>
> On 11/20/2015 11:36 AM, Hans de Goede wrote:
>> Hi Samual, et al,
>
> Hi Hans,
>
>>
>> In
>> http://cgit.freedesktop.org/mesa/mesa/commit/src/gallium/drivers/nouveau?id=ff72440b40211326eda118232fabd53965410afd
>>
>> you write: "This compute support has been tested by
>> Pierre Moreau and myself with some compute kernels."
>>
>> Can you provide testing instructions (and the
>> necessary files) so that I can try to reproduce
>> your tests ?
>>
>> And once I've reproduced your tests, the next
>> question is where / how did you get the compute
>> kernels for testing. I guess you manually wrote them ?
>
> Yeah, I wrote those compute kernels directly in assembly by hand.
>
> I already said few days ago, you have some examples in src/gallium/tests/trivial/compute.c which show how to use that compute support stuff with TGSI kernels and without clover.

Ah, right. Ok I'll take a look at those.

> Because clover is not currently able to do OpenCL -> TGSI using Clang/LLVM, you can't really use your backend directly.

I know I'm fine with manually copying TGSI output by llc for my first
tests. I've the feeling I need to understand how inputs to / outputs
from the TGSI code are handled better before I can do further work
on the llvm TGSI backend.

> An other way to achieve what you need is to copy/paste your TGSI kernel in src/gallium/tests/trivial/compute.c, set up the global buffers and other stuff (maybe samplers, textures and so on) yourself. This is a bit painful but should work as expected.
>
>>
>> As you know I'm working on a llvm tgsi backend,
>> it actually produces some output now, if you want
>> to take a peek it lives here:
>> http://cgit.freedesktop.org/~jwrdegoede/llvm
>
> I'm currently building your TGSI branch. :-)

Cool, note this is very very preliminary. This really
is just curro's work ported to the latest llvm trunk
without me having added anything (yet).

>> Before working further on this I want to take
>> a bottom up approach, so I want to first make
>> sure we've working TGSI -> compute-kernel and
>> compute-kernel -> hardware steps. So the next
>> question is, do you know if we can go from
>> (manually written) TGSI to a compute-kernel
>> using say nouveau-compiler ?
>
> Sure, you can use nouveau-compiler to convert TGSI to NV50 IR, but as I said, you can't directly execute your compute kernel without setting a ton of stuff before... That's a bunch of fun! :-)
>
> Btw, do you still need compute support on your GK208? or did you have an other card for testing ?

No I've a GT 610 / GF119 card now (still need to plug it in).

Regards,

Hans