[Mesa-dev] [PATCH 4/5] radv/gfx10: do not enable NGG if a pipeline uses XFB

[Samuel Pitoiset]

On 7/23/19 9:31 PM, Bas Nieuwenhuizen wrote:
> On Tue, Jul 23, 2019 at 3:21 PM Samuel Pitoiset
> <samuel.pitoiset at gmail.com> wrote:
>> NGG GS for streamout requires a bunch of work, so enable it with
>> the legacy path only for now.
>>
>> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
>> ---
>>   src/amd/vulkan/radv_pipeline.c | 28 ++++++++++++++++++++++++++++
>>   1 file changed, 28 insertions(+)
>>
>> diff --git a/src/amd/vulkan/radv_pipeline.c b/src/amd/vulkan/radv_pipeline.c
>> index a7ff0e2d139..0903e5abf37 100644
>> --- a/src/amd/vulkan/radv_pipeline.c
>> +++ b/src/amd/vulkan/radv_pipeline.c
>> @@ -33,6 +33,7 @@
>>   #include "radv_shader.h"
>>   #include "nir/nir.h"
>>   #include "nir/nir_builder.h"
>> +#include "nir/nir_xfb_info.h"
>>   #include "spirv/nir_spirv.h"
>>   #include "vk_util.h"
>>
>> @@ -2269,6 +2270,16 @@ radv_generate_graphics_pipeline_key(struct radv_pipeline *pipeline,
>>          return key;
>>   }
>>
>> +static bool
>> +radv_nir_stage_uses_xfb(const nir_shader *nir)
>> +{
>> +       nir_xfb_info *xfb = nir_gather_xfb_info(nir, NULL);
>> +       bool uses_xfb = !!xfb;
>> +
>> +       ralloc_free(xfb);
>> +       return uses_xfb;
>> +}
>> +
>>   static void
>>   radv_fill_shader_keys(struct radv_device *device,
>>                        struct radv_shader_variant_key *keys,
>> @@ -2321,6 +2332,23 @@ radv_fill_shader_keys(struct radv_device *device,
>>                           */
>>                          keys[MESA_SHADER_TESS_EVAL].vs_common_out.as_ngg = false;
>>                  }
>> +
>> +               /* TODO: Implement streamout support for NGG. */
>> +               bool uses_xfb = false;
>> +               if ((nir[MESA_SHADER_VERTEX] &&
>> +                    radv_nir_stage_uses_xfb(nir[MESA_SHADER_VERTEX])) ||
>> +                   (nir[MESA_SHADER_TESS_EVAL] &&
>> +                    radv_nir_stage_uses_xfb(nir[MESA_SHADER_TESS_EVAL])) ||
>> +                   (nir[MESA_SHADER_GEOMETRY] &&
>> +                    radv_nir_stage_uses_xfb(nir[MESA_SHADER_GEOMETRY])))
>> +                       uses_xfb = true;
> transform feedback can only happen on the last stage before PS right?
> Can we first determine what the last shader is and only then check for
> xfb? That way we don't have to scan 3 shaders.
Yes. Pushed with this slightly improved.
>> +
>> +               if (uses_xfb) {
>> +                       if (nir[MESA_SHADER_TESS_CTRL])
>> +                               keys[MESA_SHADER_TESS_EVAL].vs_common_out.as_ngg = false;
>> +                       else
>> +                               keys[MESA_SHADER_VERTEX].vs_common_out.as_ngg = false;
>> +               }
>>          }
>>
>>          for(int i = 0; i < MESA_SHADER_STAGES; ++i)
>> --
>> 2.22.0
>>
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