[Mesa-dev] [PATCH 23/23] i965: Skip uploading border color when unnecessary.

[Kenneth Graunke]

On Tuesday, July 29, 2014 04:29:28 PM Kenneth Graunke wrote:
> The border color is only needed when using the 
GL_CLAMP_TO_BORDER or
> (deprecated) GL_CLAMP wrap modes; all others ignore it, including 
the
> common GL_CLAMP_TO_EDGE and GL_REPEAT wrap modes.
> 
> In those cases, we can skip uploading it entirely, saving a bit of 
space
> in the batchbuffer.  Instead, we just point it at the start of the
> batch (offset 0); we have to program something, and that address is 
safe
> to read.
> 
> Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
> ---
>  src/mesa/drivers/dri/i965/brw_sampler_state.c | 22 
++++++++++++++++++++--
>  1 file changed, 20 insertions(+), 2 deletions(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_sampler_state.c
> b/src/mesa/drivers/dri/i965/brw_sampler_state.c index 
f48e3c9..ad9a527
> 100644
> --- a/src/mesa/drivers/dri/i965/brw_sampler_state.c
> +++ b/src/mesa/drivers/dri/i965/brw_sampler_state.c
> @@ -161,6 +161,16 @@ translate_wrap_mode(struct brw_context 
*brw, GLenum
> wrap, bool using_nearest) }
> 
>  /**
> + * Return true if the given wrap mode requires the border color to 
exist.
> + */
> +static bool
> +wrap_mode_needs_border_color(unsigned wrap_mode)
> +{
> +   return wrap_mode == BRW_TEXCOORDMODE_CLAMP_BORDER ||
> +          wrap_mode == GEN8_TEXCOORDMODE_HALF_BORDER;
> +}
> +
> +/**
>   * Upload SAMPLER_BORDER_COLOR_STATE.
>   */
>  static void
> @@ -410,8 +420,16 @@ brw_update_sampler_state(struct 
brw_context *brw,
>                        lod_bits);
>     base_level = U_FIXED(0, 1);
> 
> -   uint32_t border_color_offset;
> -   upload_default_color(brw, sampler, unit, &border_color_offset);
> +   /* Upload the border color if necessary.  If not, just point it at
> +    * offset 0 (the start of the batch) - the color should be ignored,
> +    * but that address won't fault in case something reads it anyway.
> +    */
> +   uint32_t border_color_offset = 0;
> +   if (wrap_mode_needs_border_color(wrap_s) ||
> +       wrap_mode_needs_border_color(wrap_t) ||
> +       wrap_mode_needs_border_color(wrap_r)) {
> +      upload_default_color(brw, sampler, unit, &border_color_offset);
> +   }
> 
>     brw_emit_sampler_state(brw,
>                            sampler_state,

I don't think I ever received any review on this patch (23/23).  The rest 
got pushed a long time ago.

Thoughts?
--Ken
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