[Mesa-dev] meta/blit: Write gl_FragDepth only when really needed

[Kenneth Graunke]

On Thursday, January 29, 2015 04:20:59 PM Topi Pohjolainen wrote:
> Currently meta blit programs unconditionally write both color and
> depth values. This series introduces two flavours - with and without
> gl_FragDepth - allowing simpler programs for color only blits. Ken
> had observed that i965 behaves badly emitting five unnecessary moves
> when the depth is included in the shader.
> While this didn't improve any performance benches I tried, it doesn't
> seem to introduce any regressions either in the benches or with
> piglit.
> 
> Topi Pohjolainen (5):
>   meta/blit: Add plumbing for shaders without depth
>   meta/blit: Write depth only when asked for
>   meta/blit: Compile programs with and without depth
>   meta: Don't write depth when generating miptrees
>   meta: Don't write depth when decompressing tex-images

Series is:
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

This should also help with future Cherryview optimizations.  Thanks!
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