[Mesa-dev] [PATCH] i965: Rework the unlit centroid workaround.

[Matt Turner]

On Mon, Aug 1, 2016 at 8:59 PM, Kenneth Graunke <kenneth at whitecape.org> wrote:
> Previously, for every input, we moved the dispatch mask to the flag
> register, then emitted two predicated PLN instructions, one with
> centroid barycentric coordinates (for normal pixels), and one with
> pixel barycentric coordinates (for unlit helper pixels).
>
> Instead, we can simply emit a set of predicated MOVs at the top of
> the program which copy the pixel barycentric coordinates over the
> centroid ones for unlit helper pixel channels.  Then, we can just
> use normal PLNs.
>
> On Sandybridge:
>
> total instructions in shared programs: 7538470 -> 7534500 (-0.05%)
> instructions in affected programs: 101268 -> 97298 (-3.92%)
> helped: 705
> HURT: 9 (all of which are SIMD16 programs)

Reviewed-by: Matt Turner <mattst88 at gmail.com>

Maybe wait a few days before pushing so we can confirm that my patch
indeed doesn't cause any regressions on Gen7.