[Mesa-dev] [PATCH] i965/skl: Don't try to apply the opt_sampler_eot extension for vs

[Kristian Høgsberg]

On Tue, Apr 28, 2015 at 02:27:17PM +0100, Neil Roberts wrote:
> The opt_sampler_eot optimisation of fs_visitor effectively assumes
> that it is running on a fragment shader because it casts the program
> key to a brw_wm_prog_key. However on Skylake fs_visitor can also be
> used for vertex shaders. It looks like this usually works anyway
> because the optimisation is skipped if key->nr_color_regions != 1.
> However for a vertex shader the key is actually a brw_vs_prog_key so
> the space for nr_color_regions is probably taken up by
> key->base.program_string_id. This can end up making nr_color_regions
> be 1 in which case the function will later assert when the last
> instruction is not FS_OPCODE_FB_WRITE. This was making the DEQP test
> suite assert. Presumably this only happens there because that compiles
> a lot of shaders so it would end up with a high value for
> program_string_id.

Right, good catch.

Reviewed-by: Kristian Høgsberg <krh at bitplanet.net>

> ---
>  src/mesa/drivers/dri/i965/brw_fs.cpp | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
> index 61ee056..255ddf4 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
> @@ -2548,6 +2548,9 @@ fs_visitor::opt_sampler_eot()
>  {
>     brw_wm_prog_key *key = (brw_wm_prog_key*) this->key;
>  
> +   if (stage != MESA_SHADER_FRAGMENT)
> +      return false;
> +
>     if (devinfo->gen < 9 && !devinfo->is_cherryview)
>        return false;
>  
> -- 
> 1.9.3
> 
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