[Mesa-dev] [PATCH 18/20] mesa: Rewrite the way uniforms are tracked and handled

[Eric Anholt]

On Wed, 04 Jan 2012 03:28:12 -0800, Kenneth Graunke <kenneth at whitecape.org> wrote:
> On 01/03/2012 09:43 PM, Marek Olšák wrote:
> > This ProgramStringNotify call causes excessive shader recompilations
> > in the game Cogs (from some Humble Bundle). Approximately 25% of
> > in-game CPU time is spent on translating shaders and register
> > allocation. If the shaders were larger, it would be much worse.
> > Moreover, I have realized calling ProgramStringNotify is not needed
> > for st/mesa in this case at all (I just comment it out if I want
> > higher frame rates), because it doesn't use the prog->SamplerUnits
> > array when translating shaders. The array is only used when we set
> > samplers, so setting _NEW_TEXTURE is sufficient. It seems that i965
> > could do the same thing. Another option would be to cache precompiled
> > shaders, but that seems more complicated than doing what st/mesa does.
> > 
> > Marek
> 
> Yeah, I noticed that a while back too, but we never arrived at a
> solution and it slipped off my radar.  I agree completely,
> ProgramStringNotify is completely overkill and bogus.
> 
> We actually already rely on _NEW_TEXTURE for all shader programs.  Since
> the uniform code already flags _NEW_TEXTURE, we should be able to just
> add the SamplerUnits array to the program key (specifically,
> brw_sampler_prog_key_data), and that should take care of any state
> dependent recompiles.  Then we wouldn't need ProgramStringNotify at all.
> 
> Right?

Well, since the data stored is part of the program, and when just
changing programs _NEW_TEXTURE wouldn't get set, I think _NEW_PROGRAM is
the flag you mean.  That would make a ton of sense to me -- if you
depend on SamplerUnits for your program handling, go look at it when
_NEW_PROGRAM is flagged.
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