[Mesa-dev] [PATCH 3/5] ffvertex: Don't try to read output registers in fog calculation

[Kenneth Graunke]

On Thursday, April 26, 2018 2:28:41 PM PDT Ian Romanick wrote:
> From: Ian Romanick <ian.d.romanick at intel.com>
> 
> This code was clearly never tested.  It's a good thing that no driver
> ever tried to enable this path.
> 
> Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
> ---
>  src/mesa/main/ffvertex_prog.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)

That's not quite accurate.  Gallium drivers advertise NV_fog_distance,
but st_program calls _mesa_remove_output_reads(), which presumably
lowers those away.  It looks like none of the classic drivers are
calling that, though, so they would be broken if they tried to enable
this.  Either your patch, or calling _mesa_remove_output_reads(),
would probably solve the issue.

At any rate, using a temporary seems reasonable.

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