[Mesa-dev] Mesa (shader-work): glsl: introduce ir_binop_all_equal and ir_binop_any_equal, allow vector cmps

[Jakob Bornecrantz]

On Thu, Sep 9, 2010 at 2:35 AM, Eric Anholt <eric at anholt.net> wrote:
> On Wed, 8 Sep 2010 20:25:15 +0200, Luca Barbieri <luca at luca-barbieri.com> wrote:
>> > I keep hearing this, and a bunch of people have been trying to build the
>> > equivalent gallium hardware drivers to various core drivers for a long
>> > time.  So, can we get some details on a success story?  What driver is
>> > now more correct/faster than it was before?  By how much?  How much of
>> > that was hardware enabling you did on the gallium side only?
>>
>> I think Corbin Simpson and Marek Olsak could be the best people to
>> comment on this, since they mostly wrote the r300g driver, which seems
>> now to be the preferred driver, instead of the older r300 classic DRI
>> driver.
>>
>> Dave Airlie extensively contributed both to the r300 DRI driver and to
>> r600 Gallium drivers, and possibly others are in a similar position.
>>
>> Keith Whitwell wrote the current Gallium i965 driver, and as far as I
>> know stopped work on it due to other commitments.
>>
>> Personally I never worked on classic drivers, so I can't really give a
>> thorough comparison.
>>
>> The general advantages of Gallium are, as I see it, are:
>> - Ability to write the driver in a more maintainable "object-oriented"
>> fashion, where you just provide code to create hardware-specific
>> objects from general self-contained descriptions and then bind them to
>> the pipeline
>
> So you're taking the GL state from Mesa's structures, munging it into
> intermediate structures, then presenting me with intermediate objects?
> The biggest thing I've found for CPU-side performance on 965 was that
> you want to avoid some sort of intermediate state step for everything
> but shader compile.  I've seriously thought about going back to the
> 915-style immediate mode state updates for 965 -- anecdotal evidence
> From other groups says that this is *immense* win.