[Mesa-dev] [PATCH 2/2] st/glsl_to_nir: delay adding built-in uniforms to Parameters list

[Nicolai Hähnle]

On 01.11.2017 06:20, Timothy Arceri wrote:
> Delaying adding built-in uniforms until after we convert to NIR
> gives us a better chance to optimise them away. Also NIR allows
> us to iterate over the uniforms directly so should be faster.
> ---
>   src/mesa/state_tracker/st_glsl_to_nir.cpp  | 68 +++++++++++++++---------------
>   src/mesa/state_tracker/st_glsl_to_tgsi.cpp |  2 +-
>   2 files changed, 34 insertions(+), 36 deletions(-)
> 
> diff --git a/src/mesa/state_tracker/st_glsl_to_nir.cpp b/src/mesa/state_tracker/st_glsl_to_nir.cpp
> index 5b37d2cd63..bbef830a2e 100644
> --- a/src/mesa/state_tracker/st_glsl_to_nir.cpp
> +++ b/src/mesa/state_tracker/st_glsl_to_nir.cpp
> @@ -235,20 +235,53 @@ st_glsl_to_nir(struct st_context *st, struct gl_program *prog,
>   
>      options = (const nir_shader_compiler_options *)
>         pscreen->get_compiler_options(pscreen, PIPE_SHADER_IR_NIR, ptarget);
>      assert(options);
>   
>      if (prog->nir)
>         return prog->nir;
>   
>      nir = glsl_to_nir(shader_program, stage, options);
>   
> +   /* Make a pass over the IR to add state references for any built-in
> +    * uniforms that are used.  This has to be done now (during linking).
> +    * Code generation doesn't happen until the first time this shader is
> +    * used for rendering.  Waiting until then to generate the parameters is
> +    * too late.  At that point, the values for the built-in uniforms won't
> +    * get sent to the shader.
> +    */
> +   nir_foreach_variable(var, &nir->uniforms) {
> +      if (strncmp(var->name, "gl_", 3) == 0) {
> +         const nir_state_slot *const slots = var->state_slots;
> +         assert(var->state_slots != NULL);
> +
> +         for (unsigned int i = 0; i < var->num_state_slots; i++) {
> +            _mesa_add_state_reference(prog->Parameters,
> +                                      (gl_state_index *)slots[i].tokens);
> +         }
> +      }
> +   }
> +
> +   /* Avoid reallocation of the program parameter list, because the uniform
> +    * storage is only associated with the original parameter list.
> +    * This should be enough for Bitmap and DrawPixels constants.
> +    */
> +   _mesa_reserve_parameter_storage(prog->Parameters, 8);
> +
> +   /* This has to be done last.  Any operation the can cause
> +    * prog->ParameterValues to get reallocated (e.g., anything that adds a
> +    * program constant) has to happen before creating this linkage.
> +    */
> +   _mesa_associate_uniform_storage(st->ctx, shader_program, prog, true);
> +
> +   st_set_prog_affected_state_flags(prog);
> +
>      NIR_PASS_V(nir, nir_lower_io_to_temporaries,
>            nir_shader_get_entrypoint(nir),
>            true, true);
>      NIR_PASS_V(nir, nir_lower_global_vars_to_local);
>      NIR_PASS_V(nir, nir_split_var_copies);
>      NIR_PASS_V(nir, nir_lower_var_copies);
>      NIR_PASS_V(nir, st_nir_lower_builtin);
>      NIR_PASS_V(nir, nir_lower_atomics, shader_program);
>   
>      /* fragment shaders may need : */
> @@ -381,67 +414,32 @@ st_nir_get_mesa_program(struct gl_context *ctx,
>      prog = shader->Program;
>   
>      prog->Parameters = _mesa_new_parameter_list();
>   
>      do_set_program_inouts(shader->ir, prog, shader->Stage);
>   
>      _mesa_copy_linked_program_data(shader_program, shader);
>      _mesa_generate_parameters_list_for_uniforms(ctx, shader_program, shader,
>                                                  prog->Parameters);
>   
> -   /* Make a pass over the IR to add state references for any built-in
> -    * uniforms that are used.  This has to be done now (during linking).
> -    * Code generation doesn't happen until the first time this shader is
> -    * used for rendering.  Waiting until then to generate the parameters is
> -    * too late.  At that point, the values for the built-in uniforms won't
> -    * get sent to the shader.
> -    */
> -   foreach_in_list(ir_instruction, node, shader->ir) {
> -      ir_variable *var = node->as_variable();
> -
> -      if ((var == NULL) || (var->data.mode != ir_var_uniform) ||
> -          (strncmp(var->name, "gl_", 3) != 0))
> -         continue;
> -
> -      const ir_state_slot *const slots = var->get_state_slots();
> -      assert(slots != NULL);
> -
> -      for (unsigned int i = 0; i < var->get_num_state_slots(); i++) {
> -         _mesa_add_state_reference(prog->Parameters,
> -                                   (gl_state_index *) slots[i].tokens);
> -      }
> -   }
> -
>      if (ctx->_Shader->Flags & GLSL_DUMP) {
>         _mesa_log("\n");
>         _mesa_log("GLSL IR for linked %s program %d:\n",
>                _mesa_shader_stage_to_string(shader->Stage),
>                shader_program->Name);
>         _mesa_print_ir(_mesa_get_log_file(), shader->ir, NULL);
>         _mesa_log("\n\n");
>      }
>   
>      prog->ExternalSamplersUsed = gl_external_samplers(prog);
>      _mesa_update_shader_textures_used(shader_program, prog);
>   
> -   /* Avoid reallocation of the program parameter list, because the uniform
> -    * storage is only associated with the original parameter list.
> -    * This should be enough for Bitmap and DrawPixels constants.
> -    */
> -   _mesa_reserve_parameter_storage(prog->Parameters, 8);
> -
> -   /* This has to be done last.  Any operation the can cause
> -    * prog->ParameterValues to get reallocated (e.g., anything that adds a
> -    * program constant) has to happen before creating this linkage.
> -    */
> -   _mesa_associate_uniform_storage(ctx, shader_program, prog, true);
> -
>      struct st_vertex_program *stvp;
>      struct st_common_program *stp;
>      struct st_fragment_program *stfp;
>      struct st_compute_program *stcp;
>   
>      switch (shader->Stage) {
>      case MESA_SHADER_VERTEX:
>         stvp = (struct st_vertex_program *)prog;
>         stvp->shader_program = shader_program;
>         break;
> diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> index eaed052a17..419183d5c9 100644
> --- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> +++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
> @@ -6969,24 +6969,24 @@ st_link_shader(struct gl_context *ctx, struct gl_shader_program *prog)
>            pipe_shader_type_from_mesa(shader->Stage);
>         enum pipe_shader_ir preferred_ir = (enum pipe_shader_ir)
>            pscreen->get_shader_param(pscreen, ptarget,
>                                      PIPE_SHADER_CAP_PREFERRED_IR);
>   
>         struct gl_program *linked_prog = NULL;
>         if (preferred_ir == PIPE_SHADER_IR_NIR) {
>            linked_prog = st_nir_get_mesa_program(ctx, prog, shader);
>         } else {
>            linked_prog = get_mesa_program_tgsi(ctx, prog, shader);
> +         st_set_prog_affected_state_flags(linked_prog);
>         }
>   
>         if (linked_prog) {
> -         st_set_prog_affected_state_flags(linked_prog);
>            if (!ctx->Driver.ProgramStringNotify(ctx,
>                                                 _mesa_shader_stage_to_program(i),
>                                                 linked_prog)) {
>               _mesa_reference_program(ctx, &shader->Program, NULL);
>               return GL_FALSE;
>            }
>         }

This hunk doesn't seem to fit with the rest of the patch.


>      }
>   
>      return GL_TRUE;
> 


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