[Mesa-dev] [PATCH 1/2] intel/blorp: Swizzle clear colors on the CPU

[Juan A. Suarez Romero]

Reviewed-by: Juan A. Suarez Romero <jasuarez at igalia.com>


On Thu, 2017-02-09 at 14:37 -0800, Jason Ekstrand wrote:
> It's trivial to swizzle clear colors on the CPU, easily deals with the
> hardware restrictions for render target swizzles, and makes swizzled
> clears work on all hardware as opposed to just HSW+.
> ---
>  src/intel/blorp/blorp_clear.c | 48 +++++++++++++++++++++++++++----------------
>  1 file changed, 30 insertions(+), 18 deletions(-)
> 
> diff --git a/src/intel/blorp/blorp_clear.c b/src/intel/blorp/blorp_clear.c
> index 8ea22ac..4d63bbe 100644
> --- a/src/intel/blorp/blorp_clear.c
> +++ b/src/intel/blorp/blorp_clear.c
> @@ -328,6 +328,26 @@ blorp_fast_clear(struct blorp_batch *batch,
>     batch->blorp->exec(batch, &params);
>  }
>  
> +static union isl_color_value
> +swizzle_color_value(union isl_color_value src, struct isl_swizzle swizzle)
> +{
> +   union isl_color_value dst = { .u32 = { 0, } };
> +
> +   /* We assign colors in ABGR order so that the first one will be taken in
> +    * RGBA precedence order.  According to the PRM docs for shader channel
> +    * select, this matches Haswell hardware behavior.
> +    */
> +   if ((unsigned)(swizzle.a - ISL_CHANNEL_SELECT_RED) < 4)
> +      dst.u32[swizzle.a - ISL_CHANNEL_SELECT_RED] = src.u32[3];
> +   if ((unsigned)(swizzle.b - ISL_CHANNEL_SELECT_RED) < 4)
> +      dst.u32[swizzle.b - ISL_CHANNEL_SELECT_RED] = src.u32[2];
> +   if ((unsigned)(swizzle.g - ISL_CHANNEL_SELECT_RED) < 4)
> +      dst.u32[swizzle.g - ISL_CHANNEL_SELECT_RED] = src.u32[1];
> +   if ((unsigned)(swizzle.r - ISL_CHANNEL_SELECT_RED) < 4)
> +      dst.u32[swizzle.r - ISL_CHANNEL_SELECT_RED] = src.u32[0];
> +
> +   return dst;
> +}
>  
>  void
>  blorp_clear(struct blorp_batch *batch,
> @@ -346,6 +366,14 @@ blorp_clear(struct blorp_batch *batch,
>     params.x1 = x1;
>     params.y1 = y1;
>  
> +   /* Manually apply the clear destination swizzle.  This way swizzled clears
> +    * will work for swizzles which we can't normally use for rendering and it
> +    * also ensures that they work on pre-Haswell hardware which can't swizlle
> +    * at all.
> +    */
> +   clear_color = swizzle_color_value(clear_color, swizzle);
> +   swizzle = ISL_SWIZZLE_IDENTITY;
> +
>     if (format == ISL_FORMAT_R9G9B9E5_SHAREDEXP) {
>        clear_color.u32[0] = float3_to_rgb9e5(clear_color.f32);
>        format = ISL_FORMAT_R32_UINT;
> @@ -353,24 +381,8 @@ blorp_clear(struct blorp_batch *batch,
>        /* Broadwell and earlier cannot render to this format so we need to work
>         * around it by swapping the colors around and using B4G4R4A4 instead.
>         */
> -
> -      /* First, we apply the swizzle. */
> -      union isl_color_value old;
> -      assert((unsigned)(swizzle.r - ISL_CHANNEL_SELECT_RED) < 4);
> -      assert((unsigned)(swizzle.g - ISL_CHANNEL_SELECT_RED) < 4);
> -      assert((unsigned)(swizzle.b - ISL_CHANNEL_SELECT_RED) < 4);
> -      assert((unsigned)(swizzle.a - ISL_CHANNEL_SELECT_RED) < 4);
> -      old.u32[swizzle.r - ISL_CHANNEL_SELECT_RED] = clear_color.u32[0];
> -      old.u32[swizzle.g - ISL_CHANNEL_SELECT_RED] = clear_color.u32[1];
> -      old.u32[swizzle.b - ISL_CHANNEL_SELECT_RED] = clear_color.u32[2];
> -      old.u32[swizzle.a - ISL_CHANNEL_SELECT_RED] = clear_color.u32[3];
> -      swizzle = ISL_SWIZZLE_IDENTITY;
> -
> -      /* Now we re-order for the new format */
> -      clear_color.u32[0] = old.u32[1];
> -      clear_color.u32[1] = old.u32[2];
> -      clear_color.u32[2] = old.u32[3];
> -      clear_color.u32[3] = old.u32[0];
> +      const struct isl_swizzle ARGB = ISL_SWIZZLE(ALPHA, RED, GREEN, BLUE);
> +      clear_color = swizzle_color_value(clear_color, ARGB);
>        format = ISL_FORMAT_B4G4R4A4_UNORM;
>     }
>