[Mesa-dev] i965 SamplerUnits rework

[Eric Anholt]

Kenneth Graunke <kenneth at whitecape.org> writes:

> On 08/24/2012 10:07 AM, Eric Anholt wrote:
>> Kenneth Graunke <kenneth at whitecape.org> writes:
>> 
>>> Greetings!
>>>
>>> This series reworks how i965 deals with sampler indirections, changing it
>>> to use linker-assigned sampler variable IDs in SEND instructions rather 
>>> than baking in the ID of the texture unit they happen to be bound to.
>>>
>>> Instead, it now encodes that mapping in the binding, sampler state,
>>> and sampler default color tables, which are updated and re-emitted at least
>>> once per batch anyway.
>> 
>> Nice work!  I think there's a cleanup available by making the texture
>> state part of the program key sampler-indexed as well, but that's
>> something that can be done later.  The texunit name change in the early
>> patches definitely helped make for easy reviewing.
>> 
>> Long term, we'll have to split our sampler/texture state tables for
>> ARB_sso, but I'm OK with this series because nobody uses EXT_sso and it
>> fixes a massive performance bug.
>
> Yeah, I neglected to mention...I'm not sure how best to do this in the
> presence of separate shader objects.  To clarify, though, you're saying
> that we have a pre-existing bug in our EXT_sso support, right?  Not that
> my series breaks it.

I think it does newly break it -- if under EXT_sso both vs and fs do
texturing, using different texunits from the same sampler index would
result in the wrong texture being chosen for one of them.

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