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

[Timothy Arceri]

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;
          }
       }
    }
 
    return GL_TRUE;
-- 
2.14.3