[Mesa-dev] [PATCH] radv: try to select better export formats for chips without Rb+

[Samuel Pitoiset]

On 1/22/19 10:50 PM, Bas Nieuwenhuizen wrote:
> On Tue, Jan 22, 2019 at 4:32 PM Samuel Pitoiset
> <samuel.pitoiset at gmail.com> wrote:
>> For some R8 formats, it's useless to export two channels
>> when no alpha blending is used. I assume the CB should
>> automatically clamps its inputs.
>>
>> 29077 shaders in 15096 tests
>> Totals:
>> SGPRS: 1321106 -> 1320970 (-0.01 %)
>> VGPRS: 935936 -> 935948 (0.00 %)
>> Spilled SGPRs: 25186 -> 25204 (0.07 %)
>> Code Size: 49813556 -> 49796944 (-0.03 %) bytes
>> Max Waves: 242091 -> 242088 (-0.00 %)
>>
>> Totals from affected shaders:
>> SGPRS: 170608 -> 170472 (-0.08 %)
>> VGPRS: 99752 -> 99764 (0.01 %)
>> Spilled SGPRs: 10377 -> 10395 (0.17 %)
>> Code Size: 6332492 -> 6315880 (-0.26 %) bytes
>> Max Waves: 12317 -> 12314 (-0.02 %)
>>
>> This helps some Rise Of Tomb Raider shaders, especially
>> when an expcnt instruction is added between two MRT exports.
>>
>> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
>> ---
>>   src/amd/vulkan/radv_pipeline.c | 27 ++++++++++++++++++++++-----
>>   1 file changed, 22 insertions(+), 5 deletions(-)
>>
>> diff --git a/src/amd/vulkan/radv_pipeline.c b/src/amd/vulkan/radv_pipeline.c
>> index 138e153f9a4..25281c3c6da 100644
>> --- a/src/amd/vulkan/radv_pipeline.c
>> +++ b/src/amd/vulkan/radv_pipeline.c
>> @@ -372,9 +372,10 @@ static bool is_dual_src(VkBlendFactor factor)
>>          }
>>   }
>>
>> -static unsigned si_choose_spi_color_format(VkFormat vk_format,
>> -                                           bool blend_enable,
>> -                                           bool blend_need_alpha)
>> +static unsigned si_choose_spi_color_format(struct radv_device *device,
>> +                                          VkFormat vk_format,
>> +                                          bool blend_enable,
>> +                                          bool blend_need_alpha)
>>   {
>>          const struct vk_format_description *desc = vk_format_description(vk_format);
>>          unsigned format, ntype, swap;
>> @@ -486,6 +487,20 @@ static unsigned si_choose_spi_color_format(VkFormat vk_format,
>>                  unreachable("unhandled blend format");
>>          }
>>
>> +       if (device && /* NULL for internal meta formats */
>> +           !device->physical_device->rbplus_allowed) {
>> +               /* Try to select better export formats for chips without Rb+. */
>> +               if (desc->nr_channels == 1 &&
>> +                   desc->channel[0].size == 8 &&
> Why do we only allow this for 8 bit components? Why not also for
> 16/32-bit components?

For 32-bit, that should be already handled in the switch above. For 
16-bit, that should work but this hits a crash in LLVM.

I should probably add a TODO.

>
>> +                   swap == V_028C70_SWAP_STD && /* R */
>> +                   !vk_format_is_srgb(vk_format)) {
>> +                       /* Do not need to export two channels for some R8
>> +                        * formats when alpha blending isn't used.
>> +                        */
>> +                       blend = normal = V_028714_SPI_SHADER_32_R;
>> +               }
>> +       }
>> +
>>          if (blend_enable && blend_need_alpha)
>>                  return blend_alpha;
>>          else if(blend_need_alpha)
>> @@ -516,7 +531,8 @@ radv_pipeline_compute_spi_color_formats(struct radv_pipeline *pipeline,
>>                          bool blend_enable =
>>                                  blend->blend_enable_4bit & (0xfu << (i * 4));
>>
>> -                       cf = si_choose_spi_color_format(attachment->format,
>> +                       cf = si_choose_spi_color_format(pipeline->device,
>> +                                                       attachment->format,
>>                                                          blend_enable,
>>                                                          blend->need_src_alpha & (1 << i));
>>                  }
>> @@ -586,7 +602,8 @@ const VkFormat radv_fs_key_format_exemplars[NUM_META_FS_KEYS] = {
>>
>>   unsigned radv_format_meta_fs_key(VkFormat format)
>>   {
>> -       unsigned col_format = si_choose_spi_color_format(format, false, false);
>> +       unsigned col_format =
>> +               si_choose_spi_color_format(NULL, format, false, false);
> I think we properly need to plumb through the device here?

Yeah, but that breaks a bunch of tests. This function looks a bit hacky 
to me.

Requires investigations.

>>          assert(col_format != V_028714_SPI_SHADER_32_AR);
>>          if (col_format >= V_028714_SPI_SHADER_32_AR)
>> --
>> 2.20.1
>>
>> _______________________________________________
>> mesa-dev mailing list
>> mesa-dev at lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/mesa-dev