[Mesa-dev] [PATCH v2] swr: move msaa resolve to generalized StoreTile

[Ilia Mirkin]

On Thu, Apr 27, 2017 at 8:45 PM, Cherniak, Bruce
<bruce.cherniak at intel.com> wrote:
>
>> On Apr 27, 2017, at 7:38 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>>
>> Erm, so ... what happens if I render to FB1, then render to FB2, then
>> render to FB1 again (and I have blending enabled)? Doesn't the resolve
>> lose the per-sample information? Or does the resolve merely precompute
>> the resolved version on the off chance that it's needed, without
>> losing the source data?
>
> The resolve occurs into a secondary, driver private, surface.  All per-sample
> information is maintained in the original surfaces.
>
> Yes, the resolve is currently done "on the off chance that it’s needed”.
> There is likely an optimization to be had there, but it should be functionally
> correct.

Got it. May I ask why this isn't done on-demand instead? Is it a pain
to plug into swr's execution engine? I'm just concerned that
StoreTile() may get called a lot, more than even there are draws, as
tiles are swapped in and out of "hotness", and I wouldn't be surprised
if resolves were needed only a fraction of the time.

Cheers,

  -ilia