glsl: parser changes for GL_ARB_explicit_uniform_location

Patch adds a preprocessor define for the extension and stores explicit
location data for uniforms during AST->HIR conversion. It also sets
layout token to be available when having the extension in place.

v2: change parser check to require GLSL 330 or enabling
    GL_ARB_explicit_attrib_location (Ian)
v3: fix the check and comment in AST->HIR (Petri)

Signed-off-by: Tapani Pälli <tapani.palli@intel.com>

src/glsl/ast_to_hir.cpp

@@ -2181,6 +2181,41 @@ validate_explicit_location(const struct ast_type_qualifier *qual,
 {
    bool fail = false;
 
+   /* Checks for GL_ARB_explicit_uniform_location. */
+   if (qual->flags.q.uniform) {
+      if (!state->check_explicit_uniform_location_allowed(loc, var))
+         return;
+
+      const struct gl_context *const ctx = state->ctx;
+      unsigned max_loc = qual->location + var->type->uniform_locations() - 1;
+
+      /* ARB_explicit_uniform_location specification states:
+       *
+       *     "The explicitly defined locations and the generated locations
+       *     must be in the range of 0 to MAX_UNIFORM_LOCATIONS minus one."
+       *
+       *     "Valid locations for default-block uniform variable locations
+       *     are in the range of 0 to the implementation-defined maximum
+       *     number of uniform locations."
+       */
+      if (qual->location < 0) {
+         _mesa_glsl_error(loc, state,
+                          "explicit location < 0 for uniform %s", var->name);
+         return;
+      }
+
+      if (max_loc >= ctx->Const.MaxUserAssignableUniformLocations) {
+         _mesa_glsl_error(loc, state, "location(s) consumed by uniform %s "
+                          ">= MAX_UNIFORM_LOCATIONS (%u)", var->name,
+                          ctx->Const.MaxUserAssignableUniformLocations);
+         return;
+      }
+
+      var->data.explicit_location = true;
+      var->data.location = qual->location;
+      return;
+   }
+
    /* Between GL_ARB_explicit_attrib_location an
     * GL_ARB_separate_shader_objects, the inputs and outputs of any shader
     * stage can be assigned explicit locations.  The checking here associates

src/glsl/glcpp/glcpp-parse.y

@@ -2089,6 +2089,9 @@ _glcpp_parser_handle_version_declaration(glcpp_parser_t *parser, intmax_t versio
 	      if (extensions->ARB_explicit_attrib_location)
 	         add_builtin_define(parser, "GL_ARB_explicit_attrib_location", 1);
 
+	      if (extensions->ARB_explicit_uniform_location)
+	         add_builtin_define(parser, "GL_ARB_explicit_uniform_location", 1);
+
 	      if (extensions->ARB_shader_texture_lod)
 	         add_builtin_define(parser, "GL_ARB_shader_texture_lod", 1);
 

src/glsl/glsl_lexer.ll

@@ -396,6 +396,7 @@ layout		{
 		      || yyextra->AMD_conservative_depth_enable
 		      || yyextra->ARB_conservative_depth_enable
 		      || yyextra->ARB_explicit_attrib_location_enable
+		      || yyextra->ARB_explicit_uniform_location_enable
                       || yyextra->has_separate_shader_objects()
 		      || yyextra->ARB_uniform_buffer_object_enable
 		      || yyextra->ARB_fragment_coord_conventions_enable

src/glsl/glsl_parser_extras.h

@@ -151,6 +151,21 @@ struct _mesa_glsl_parse_state {
       return true;
    }
 
+   bool check_explicit_uniform_location_allowed(YYLTYPE *locp,
+                                                const ir_variable *var)
+   {
+      if (!this->has_explicit_attrib_location() ||
+          !this->ARB_explicit_uniform_location_enable) {
+         _mesa_glsl_error(locp, this,
+                          "uniform explicit location requires "
+                          "GL_ARB_explicit_uniform_location and either "
+                          "GL_ARB_explicit_attrib_location or GLSL 330.");
+         return false;
+      }
+
+      return true;
+   }
+
    bool has_explicit_attrib_location() const
    {
       return ARB_explicit_attrib_location_enable || is_version(330, 300);