glsl: Add glsl LowerCsDerivedVariables option

v2:
 * Move lower flag to context constants. (Ken)

Cc: "12.0" <mesa-stable@lists.freedesktop.org>
Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org> (v1)
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

src/compiler/glsl/builtin_variables.cpp

@@ -1201,8 +1201,15 @@ builtin_variable_generator::generate_cs_special_vars()
                     "gl_LocalInvocationID");
    add_system_value(SYSTEM_VALUE_WORK_GROUP_ID, uvec3_t, "gl_WorkGroupID");
    add_system_value(SYSTEM_VALUE_NUM_WORK_GROUPS, uvec3_t, "gl_NumWorkGroups");
+   if (state->ctx->Const.LowerCsDerivedVariables) {
       add_variable("gl_GlobalInvocationID", uvec3_t, ir_var_auto, 0);
       add_variable("gl_LocalInvocationIndex", uint_t, ir_var_auto, 0);
+   } else {
+      add_system_value(SYSTEM_VALUE_GLOBAL_INVOCATION_ID,
+                       uvec3_t, "gl_GlobalInvocationID");
+      add_system_value(SYSTEM_VALUE_LOCAL_INVOCATION_INDEX,
+                       uint_t, "gl_LocalInvocationIndex");
+   }
 }
 
 
@@ -1431,16 +1438,16 @@ initialize_cs_derived_variables(gl_shader *shader,
  * These are initialized in the main function.
  */
 void
-_mesa_glsl_initialize_derived_variables(gl_shader *shader)
+_mesa_glsl_initialize_derived_variables(struct gl_context *ctx,
+                                        gl_shader *shader)
 {
    /* We only need to set CS variables currently. */
-   if (shader->Stage != MESA_SHADER_COMPUTE)
-      return;
-
+   if (shader->Stage == MESA_SHADER_COMPUTE &&
+       ctx->Const.LowerCsDerivedVariables) {
       ir_function_signature *const main_sig =
          _mesa_get_main_function_signature(shader);
-   if (main_sig == NULL)
-      return;
 
+      if (main_sig != NULL)
          initialize_cs_derived_variables(shader, main_sig);
    }
+}

src/compiler/glsl/glsl_parser_extras.cpp

@@ -1907,7 +1907,7 @@ _mesa_glsl_compile_shader(struct gl_context *ctx, struct gl_shader *shader,
       }
    }
 
-   _mesa_glsl_initialize_derived_variables(shader);
+   _mesa_glsl_initialize_derived_variables(ctx, shader);
 
    delete state->symbols;
    ralloc_free(state);

src/compiler/glsl/ir.h

@@ -2562,7 +2562,8 @@ _mesa_glsl_initialize_variables(exec_list *instructions,
 				struct _mesa_glsl_parse_state *state);
 
 extern void
-_mesa_glsl_initialize_derived_variables(gl_shader *shader);
+_mesa_glsl_initialize_derived_variables(struct gl_context *ctx,
+                                        gl_shader *shader);
 
 extern void
 _mesa_glsl_initialize_functions(_mesa_glsl_parse_state *state);

src/mesa/drivers/dri/i965/brw_context.c

@@ -599,6 +599,7 @@ brw_initialize_context_constants(struct brw_context *brw)
       ctx->Const.MaxClipPlanes = 8;
 
    ctx->Const.LowerTessLevel = true;
+   ctx->Const.LowerCsDerivedVariables = true;
    ctx->Const.PrimitiveRestartForPatches = true;
 
    ctx->Const.Program[MESA_SHADER_VERTEX].MaxNativeInstructions = 16 * 1024;

src/mesa/main/mtypes.h

@@ -3763,6 +3763,9 @@ struct gl_constants
    GLuint MaxTessControlTotalOutputComponents;
    bool LowerTessLevel; /**< Lower gl_TessLevel* from float[n] to vecn? */
    bool PrimitiveRestartForPatches;
+   bool LowerCsDerivedVariables;    /**< Lower gl_GlobalInvocationID and
+                                     *   gl_LocalInvocationIndex based on
+                                     *   other builtin variables. */
 };
 
 

src/mesa/state_tracker/st_extensions.c

@@ -314,6 +314,7 @@ void st_init_limits(struct pipe_screen *screen,
    }
 
    c->LowerTessLevel = true;
+   c->LowerCsDerivedVariables = true;
    c->PrimitiveRestartForPatches =
       screen->get_param(screen, PIPE_CAP_PRIMITIVE_RESTART_FOR_PATCHES);