[Mesa-dev] [PATCH 1/5] i965/gen9: Don't disallow fast clear for MSRT formats matching render

[Neil Roberts]

Ben Widawsky <ben at bwidawsk.net> writes:

>> +      if (brw->gen >= 9 &&
>> +          brw_format_for_mesa_format(irb->mt->format) !=
>> +          brw->render_target_format[irb->mt->format])
>
> Could you just do
> !brw->format_supported_as_render_target[irb->mt->format]?

Hrm, yes, you're right, that would be much neater.

> I forget, did you find failures for this in the non-MSRT case? If not,
> maybe we could skip this patch and just take the rest of the series?
> That way we can avoid the "perf regression" of RGBX clears which we do
> hit on certain workloads.

I couldn't find any regressions for the non-MSRT case. However, it looks
like the RGBX formats don't use fast clears on non-MSRT anyway because
none of them are marked as having lossless compression support. In fact,
if we land the whole series then it should be a performance
*improvement* on non-MSRT because the RGBX clears become RGBA clears
internally and those do support fast clears.

Regards,
- Neil