[Mesa-dev] [PATCH 1/3] nir/lower_tex: Add AYUV lowering support

[Tapani Pälli]

I haven't reviewed any NIR yet, so here's my 1st take and a bit explanation.

Alpha channel is introduced to the conversion, in case of other formats 
we give constant 1.0 (as there's no support for alpha) while for AYUV we 
support alpha and give the real channel value. Components go like 'VUYA' 
so 2103 is correct.

Reviewed-by: Tapani Pälli <tapani.palli at intel.com>

On 11/8/18 8:23 PM, Lionel Landwerlin wrote:
> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
> ---
>   src/compiler/nir/nir.h           |  1 +
>   src/compiler/nir/nir_lower_tex.c | 36 ++++++++++++++++++++++++++------
>   2 files changed, 31 insertions(+), 6 deletions(-)
> 
> diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
> index f4f6b106505..2a843de8ae1 100644
> --- a/src/compiler/nir/nir.h
> +++ b/src/compiler/nir/nir.h
> @@ -2904,6 +2904,7 @@ typedef struct nir_lower_tex_options {
>      unsigned lower_y_u_v_external;
>      unsigned lower_yx_xuxv_external;
>      unsigned lower_xy_uxvx_external;
> +   unsigned lower_ayuv_external;
>   
>      /**
>       * To emulate certain texture wrap modes, this can be used
> diff --git a/src/compiler/nir/nir_lower_tex.c b/src/compiler/nir/nir_lower_tex.c
> index dc40d82b27f..e10d4ea62f6 100644
> --- a/src/compiler/nir/nir_lower_tex.c
> +++ b/src/compiler/nir/nir_lower_tex.c
> @@ -261,7 +261,8 @@ sample_plane(nir_builder *b, nir_tex_instr *tex, int plane)
>   
>   static void
>   convert_yuv_to_rgb(nir_builder *b, nir_tex_instr *tex,
> -                   nir_ssa_def *y, nir_ssa_def *u, nir_ssa_def *v)
> +                   nir_ssa_def *y, nir_ssa_def *u, nir_ssa_def *v,
> +                   nir_ssa_def *a)
>   {
>      nir_const_value m[3] = {
>         { .f32 = { 1.0f,  0.0f,         1.59602678f, 0.0f } },
> @@ -281,7 +282,7 @@ convert_yuv_to_rgb(nir_builder *b, nir_tex_instr *tex,
>      nir_ssa_def *green = nir_fdot4(b, yuv, nir_build_imm(b, 4, 32, m[1]));
>      nir_ssa_def *blue = nir_fdot4(b, yuv, nir_build_imm(b, 4, 32, m[2]));
>   
> -   nir_ssa_def *result = nir_vec4(b, red, green, blue, nir_imm_float(b, 1.0f));
> +   nir_ssa_def *result = nir_vec4(b, red, green, blue, a);
>   
>      nir_ssa_def_rewrite_uses(&tex->dest.ssa, nir_src_for_ssa(result));
>   }
> @@ -297,7 +298,8 @@ lower_y_uv_external(nir_builder *b, nir_tex_instr *tex)
>      convert_yuv_to_rgb(b, tex,
>                         nir_channel(b, y, 0),
>                         nir_channel(b, uv, 0),
> -                      nir_channel(b, uv, 1));
> +                      nir_channel(b, uv, 1),
> +                      nir_imm_float(b, 1.0f));
>   }
>   
>   static void
> @@ -312,7 +314,8 @@ lower_y_u_v_external(nir_builder *b, nir_tex_instr *tex)
>      convert_yuv_to_rgb(b, tex,
>                         nir_channel(b, y, 0),
>                         nir_channel(b, u, 0),
> -                      nir_channel(b, v, 0));
> +                      nir_channel(b, v, 0),
> +                      nir_imm_float(b, 1.0f));
>   }
>   
>   static void
> @@ -326,7 +329,8 @@ lower_yx_xuxv_external(nir_builder *b, nir_tex_instr *tex)
>      convert_yuv_to_rgb(b, tex,
>                         nir_channel(b, y, 0),
>                         nir_channel(b, xuxv, 1),
> -                      nir_channel(b, xuxv, 3));
> +                      nir_channel(b, xuxv, 3),
> +                      nir_imm_float(b, 1.0f));
>   }
>   
>   static void
> @@ -340,7 +344,22 @@ lower_xy_uxvx_external(nir_builder *b, nir_tex_instr *tex)
>     convert_yuv_to_rgb(b, tex,
>                        nir_channel(b, y, 1),
>                        nir_channel(b, uxvx, 0),
> -                     nir_channel(b, uxvx, 2));
> +                     nir_channel(b, uxvx, 2),
> +                     nir_imm_float(b, 1.0f));
> +}
> +
> +static void
> +lower_ayuv_external(nir_builder *b, nir_tex_instr *tex)
> +{
> +  b->cursor = nir_after_instr(&tex->instr);
> +
> +  nir_ssa_def *ayuv = sample_plane(b, tex, 0);
> +
> +  convert_yuv_to_rgb(b, tex,
> +                     nir_channel(b, ayuv, 2),
> +                     nir_channel(b, ayuv, 1),
> +                     nir_channel(b, ayuv, 0),
> +                     nir_channel(b, ayuv, 3));
>   }
>   
>   /*
> @@ -788,6 +807,11 @@ nir_lower_tex_block(nir_block *block, nir_builder *b,
>            progress = true;
>         }
>   
> +      if ((1 << tex->texture_index) & options->lower_ayuv_external) {
> +         lower_ayuv_external(b, tex);
> +         progress = true;
> +      }
> +
>         if (sat_mask) {
>            saturate_src(b, tex, sat_mask);
>            progress = true;
>