[Mesa-dev] [PATCH 06/16] nir: improve convert_yuv_to_rgb when fuse_ffma=true

[Jonathan marek]

On 12/20/2018 01:28 AM, Nils Wallménius wrote:
> Den ons 19 dec. 2018 17:44 skrev Jonathan Marek <jonathan at marek.ca>:
> 
>> When ffma is available, we can use a different arrangement of constants to
>> get a better result. On freedreno/ir3, this reduces the YUV->RGB to 7
>> scalar ffma. On freedreno/a2xx, it will allow YUV->RGB to be 3 vec4 ffma.
>>
>> Signed-off-by: Jonathan Marek <jonathan at marek.ca>
>> ---
>>   src/compiler/nir/nir_lower_tex.c | 62 ++++++++++++++++++++++----------
>>   1 file changed, 43 insertions(+), 19 deletions(-)
>>
>> diff --git a/src/compiler/nir/nir_lower_tex.c
>> b/src/compiler/nir/nir_lower_tex.c
>> index 6a6b6c41a7..f7c821bb34 100644
>> --- a/src/compiler/nir/nir_lower_tex.c
>> +++ b/src/compiler/nir/nir_lower_tex.c
>> @@ -342,25 +342,49 @@ 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 *a)
>>   {
>> -   nir_const_value m[3] = {
>> -      { .f32 = { 1.0f,  0.0f,         1.59602678f, 0.0f } },
>> -      { .f32 = { 1.0f, -0.39176229f, -0.81296764f, 0.0f } },
>> -      { .f32 = { 1.0f,  2.01723214f,  0.0f,        0.0f } }
>> -   };
>> -
>> -   nir_ssa_def *yuv =
>> -      nir_vec4(b,
>> -               nir_fmul(b, nir_imm_float(b, 1.16438356f),
>> -                        nir_fadd(b, y, nir_imm_float(b, -16.0f /
>> 255.0f))),
>> -               nir_channel(b, nir_fadd(b, u, nir_imm_float(b, -128.0f /
>> 255.0f)), 0),
>> -               nir_channel(b, nir_fadd(b, v, nir_imm_float(b, -128.0f /
>> 255.0f)), 0),
>> -               nir_imm_float(b, 0.0));
>> -
>> -   nir_ssa_def *red = nir_fdot4(b, yuv, nir_build_imm(b, 4, 32, m[0]));
>> -   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, a);
>> +   nir_ssa_def *result;
>> +
>> +
>> +   if (b->shader->options->fuse_ffma) {
>> +      nir_const_value m[4] = {
>>
> 
> Drive-by comment, but shouldn't this^ be m[3]?
> 
> Regards
> Nils
> 

Yes, it should be m[3]. It was originally 4 before alpha was added.

>> +         { .f32 = { 1.16438356f, 1.16438356f, 1.16438356f, 0.0f } },
>> +         { .f32 = { 0.0f,       -0.39176229f, 2.01723214f, 0.0f } },
>> +         { .f32 = { 1.59602678f,-0.81296764f, 0.0f,        0.0f } },
>> +      };
>> +      static const float y_off = -16.0f * 1.16438356f / 255.0f;
>> +      static const float sc = 128.0f / 255.0f;
>> +
>> +      nir_ssa_def *offset =
>> +         nir_vec4(b,
>> +                  nir_imm_float(b, y_off - sc * 1.59602678f),
>> +                  nir_imm_float(b, y_off + sc * (0.81296764f +
>> 0.39176229f)),
>> +                  nir_imm_float(b, y_off - sc * 2.01723214f),
>> +                  a);
>> +
>> +      result = nir_ffma(b, y, nir_build_imm(b, 4, 32, m[0]),
>> +                       nir_ffma(b, u, nir_build_imm(b, 4, 32, m[1]),
>> +                                nir_ffma(b, v, nir_build_imm(b, 4, 32,
>> m[2]), offset)));
>> +   } else {
>> +      nir_const_value m[3] = {
>> +         { .f32 = { 1.0f,  0.0f,         1.59602678f, 0.0f } },
>> +         { .f32 = { 1.0f, -0.39176229f, -0.81296764f, 0.0f } },
>> +         { .f32 = { 1.0f,  2.01723214f,  0.0f,        0.0f } }
>> +      };
>> +
>> +      nir_ssa_def *yuv =
>> +         nir_vec4(b,
>> +                  nir_fmul(b, nir_imm_float(b, 1.16438356f),
>> +                           nir_fadd(b, y, nir_imm_float(b, -16.0f /
>> 255.0f))),
>> +                  nir_channel(b, nir_fadd(b, u, nir_imm_float(b, -128.0f
>> / 255.0f)), 0),
>> +                  nir_channel(b, nir_fadd(b, v, nir_imm_float(b, -128.0f
>> / 255.0f)), 0),
>> +                  nir_imm_float(b, 0.0));
>> +
>> +      nir_ssa_def *red = nir_fdot4(b, yuv, nir_build_imm(b, 4, 32, m[0]));
>> +      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]));
>> +
>> +      result = nir_vec4(b, red, green, blue, a);
>> +   }
>>
>>      nir_ssa_def_rewrite_uses(&tex->dest.ssa, nir_src_for_ssa(result));
>>   }
>> --
>> 2.17.1
>>
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>