[Mesa-dev] [PATCH] anv: Restrict the nuber of color regions to those actually written

[Caio Marcelo de Oliveira Filho]

On Wed, Jun 27, 2018 at 07:00:56PM -0700, Jason Ekstrand wrote:
> The back-end compiler emits the number of color writes specified by
> wm_prog_key::nr_color_regions regardless of what nir_store_outputs we
> have.  Once we've gone through and figured out which render targets
> actually exist and are written by the shader, we should restrict the key
> to avoid extra RT write messages.
> ---
>  src/intel/vulkan/anv_pipeline.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/src/intel/vulkan/anv_pipeline.c b/src/intel/vulkan/anv_pipeline.c
> index 523202cf3d9..6a27d305dbc 100644
> --- a/src/intel/vulkan/anv_pipeline.c
> +++ b/src/intel/vulkan/anv_pipeline.c
> @@ -965,6 +965,11 @@ anv_pipeline_compile_fs(struct anv_pipeline *pipeline,
>           var->data.location = rt_to_bindings[rt] + FRAG_RESULT_DATA0;
>        }
>  
> +      /* Now that we've determined the actual number of render targets, adjust
> +       * the key accordingly.
> +       */
> +      key.nr_color_regions = num_rts;
> +

Question: earlier in the code we call 

   populate_wm_prog_key(pipeline, info, &key);

which does

   key->nr_color_regions = pipeline->subpass->color_count;

   key->replicate_alpha = key->nr_color_regions > 1 &&
                          info->pMultisampleState &&
                          info->pMultisampleState->alphaToCoverageEnable;

so key->replicate_alpha is calculated based on the old value. Should
this be (re)calculated using the new value?


Thanks,
Caio