[Mesa-dev] [PATCH 1/3] gallium: add PIPE_CAP_SHAREABLE_SHADERS

[Rob Clark]

On Mon, Oct 19, 2015 at 7:07 PM, Marek Olšák <maraeo at gmail.com> wrote:
> On Mon, Oct 19, 2015 at 11:52 PM, Rob Clark <robdclark at gmail.com> wrote:
>> On Sat, Oct 10, 2015 at 9:09 PM, Marek Olšák <maraeo at gmail.com> wrote:
>>> From: Marek Olšák <marek.olsak at amd.com>
>>>
>>> I'll let drivers figure out how to do it.
>>> ---
>>>  src/gallium/docs/source/screen.rst               | 2 ++
>>>  src/gallium/drivers/freedreno/freedreno_screen.c | 1 +
>>>  src/gallium/drivers/i915/i915_screen.c           | 1 +
>>>  src/gallium/drivers/ilo/ilo_screen.c             | 1 +
>>>  src/gallium/drivers/llvmpipe/lp_screen.c         | 1 +
>>>  src/gallium/drivers/nouveau/nv30/nv30_screen.c   | 1 +
>>>  src/gallium/drivers/nouveau/nv50/nv50_screen.c   | 1 +
>>>  src/gallium/drivers/nouveau/nvc0/nvc0_screen.c   | 1 +
>>>  src/gallium/drivers/r300/r300_screen.c           | 1 +
>>>  src/gallium/drivers/r600/r600_pipe.c             | 1 +
>>>  src/gallium/drivers/radeonsi/si_pipe.c           | 1 +
>>>  src/gallium/drivers/softpipe/sp_screen.c         | 1 +
>>>  src/gallium/drivers/svga/svga_screen.c           | 1 +
>>>  src/gallium/drivers/vc4/vc4_screen.c             | 1 +
>>>  src/gallium/include/pipe/p_defines.h             | 1 +
>>>  15 files changed, 16 insertions(+)
>>>
>>> diff --git a/src/gallium/docs/source/screen.rst b/src/gallium/docs/source/screen.rst
>>> index e08844b..72f7596 100644
>>> --- a/src/gallium/docs/source/screen.rst
>>> +++ b/src/gallium/docs/source/screen.rst
>>> @@ -276,6 +276,8 @@ The integer capabilities:
>>>    GL4 hardware will likely need to emulate it with a shader variant, or by
>>>    selecting the interpolation weights with a conditional assignment
>>>    in the shader.
>>> +* ``PIPE_CAP_SHAREABLE_SHADERS``: Whether shader CSOs can be used by any
>>> +  pipe_context.
>>
>> An extra sentence along the lines that drivers supporting this cap can
>> save pipe->screen ptr but not pipe ptr in the CSO might not hurt..
>>
>> other than that nitpick, lgtm..
>
> I don't understand why drivers would want to put either of them into
> the CSO. All calls manipulating the CSO take pipe_context, so you
> always have some pipe_context and pipe_screen if you need them. The
> correct answer - don't put any of them into the CSO - applied before
> and still applies.

My point was, pipe_screen never changes for the CSO but pipe_context
can..  I need the pipe_screen to stay the same for allocating memory
to hold the shader, figure out which gpu generation for some things
that differ between a3xx/a4xx in the backend, etc.

Sure technically you could pass the screen down the call stack instead
of storing it in CSO.. for me that would be a lot of adding extra fxn
param's in a bunch of places, so I won't bother (but I would replace
the current pipe_context ptr w/ pipe_screen, and update the emit code
to pass down the ctx)

BR,
-R

> Marek