[Mesa-dev] [PATCH 2/2] radv/gfx10: correctly determine the number of vertices per primitive

[Ilia Mirkin]

On Mon, Jul 22, 2019 at 11:49 AM Samuel Pitoiset
<samuel.pitoiset at gmail.com> wrote:
>
> For TES as NGG.
>
> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
> ---
>  src/amd/vulkan/radv_nir_to_llvm.c | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/src/amd/vulkan/radv_nir_to_llvm.c b/src/amd/vulkan/radv_nir_to_llvm.c
> index 336bae28614..6e5a283f923 100644
> --- a/src/amd/vulkan/radv_nir_to_llvm.c
> +++ b/src/amd/vulkan/radv_nir_to_llvm.c
> @@ -112,6 +112,7 @@ struct radv_shader_context {
>         unsigned gs_max_out_vertices;
>         unsigned gs_output_prim;
>
> +       unsigned tes_point_mode;
>         unsigned tes_primitive_mode;
>
>         uint32_t tcs_patch_outputs_read;
> @@ -3304,7 +3305,6 @@ handle_ngg_outputs_post(struct radv_shader_context *ctx)
>  {
>         LLVMBuilderRef builder = ctx->ac.builder;
>         struct ac_build_if_state if_state;
> -       unsigned num_vertices = 3;
>         LLVMValueRef tmp;
>
>         assert((ctx->stage == MESA_SHADER_VERTEX ||
> @@ -3322,6 +3322,20 @@ handle_ngg_outputs_post(struct radv_shader_context *ctx)
>                 ac_unpack_param(&ctx->ac, ctx->gs_vtx_offset[2], 0, 16),
>         };
>
> +       /* Determine the number of vertices per primitive. */
> +       unsigned num_vertices;
> +
> +       if (ctx->stage == MESA_SHADER_VERTEX) {
> +               num_vertices = 3; /* TODO: optimize for points & lines */
> +       } else {
> +               if (ctx->tes_point_mode)
> +                       num_vertices = 1;
> +               else if (ctx->tes_primitive_mode == GL_LINES)
> +                       num_vertices = 2;
> +               else
> +                       num_vertices = 3;
> +       }
> +
>         /* TODO: streamout */
>
>         /* Copy Primitive IDs from GS threads to the LDS address corresponding
> @@ -4435,6 +4449,7 @@ LLVMModuleRef ac_translate_nir_to_llvm(struct ac_llvm_compiler *ac_llvm,
>                                 ctx.tcs_num_inputs = util_last_bit64(shader_info->info.vs.ls_outputs_written);
>                         ctx.tcs_num_patches = get_tcs_num_patches(&ctx);
>                 } else if (shaders[i]->info.stage == MESA_SHADER_TESS_EVAL) {
> +                       ctx.tes_point_mode = shaders[i]->info.tess.point_mode;

Drive-by-comment without reading the full context...

What if there's e.g. a GS which produces not-points? This bool will be
set, and the logic above will say num_vertices = 1, which presumably
is bad.

  -ilia

>                         ctx.tes_primitive_mode = shaders[i]->info.tess.primitive_mode;
>                         ctx.abi.load_tess_varyings = load_tes_input;
>                         ctx.abi.load_tess_coord = load_tess_coord;
> --
> 2.22.0
>
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