glsl: A shader cannot redefine or overload built-in functions in GLSL ES 3.00

Create a new search function to look for matching built-in functions by name
and use it for built-in function redefinition or overload in GLSL ES 3.00.

GLSL ES 3.0 spec, chapter 6.1 "Function Definitions", page 71

  "A shader cannot redefine or overload built-in functions."

While in GLSL ES 1.0 specification, chapter 8 "Built-in Functions"

  "User code can overload the built-in functions but cannot redefine them."

So this check is specific to GLSL ES 3.00.

This patch fixes the following dEQP tests:

dEQP-GLES3.functional.shaders.functions.invalid.overload_builtin_function_vertex
dEQP-GLES3.functional.shaders.functions.invalid.overload_builtin_function_fragment
dEQP-GLES3.functional.shaders.functions.invalid.redefine_builtin_function_vertex
dEQP-GLES3.functional.shaders.functions.invalid.redefine_builtin_function_fragment

No piglit regressions.

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/glsl/ast_to_hir.cpp

@@ -4205,6 +4205,27 @@ ast_function::hir(exec_list *instructions,
       emit_function(state, f);
    }
 
+   /* From GLSL ES 3.0 spec, chapter 6.1 "Function Definitions", page 71:
+    *
+    * "A shader cannot redefine or overload built-in functions."
+    *
+    * While in GLSL ES 1.0 specification, chapter 8 "Built-in Functions":
+    *
+    * "User code can overload the built-in functions but cannot redefine
+    * them."
+    */
+   if (state->es_shader && state->language_version >= 300) {
+      /* Local shader has no exact candidates; check the built-ins. */
+      _mesa_glsl_initialize_builtin_functions();
+      if (_mesa_glsl_find_builtin_function_by_name(state, name)) {
+         YYLTYPE loc = this->get_location();
+         _mesa_glsl_error(& loc, state,
+                          "A shader cannot redefine or overload built-in "
+                          "function `%s' in GLSL ES 3.00", name);
+         return NULL;
+      }
+   }
+
    /* Verify that this function's signature either doesn't match a previously
     * seen signature for a function with the same name, or, if a match is found,
     * that the previously seen signature does not have an associated definition.

src/glsl/builtin_functions.cpp

@@ -4851,6 +4851,17 @@ _mesa_glsl_find_builtin_function(_mesa_glsl_parse_state *state,
    return s;
 }
 
+ir_function *
+_mesa_glsl_find_builtin_function_by_name(_mesa_glsl_parse_state *state,
+                                         const char *name)
+{
+   ir_function *f;
+   mtx_lock(&builtins_lock);
+   f = builtins.shader->symbols->get_function(name);
+   mtx_unlock(&builtins_lock);
+   return f;
+}
+
 gl_shader *
 _mesa_glsl_get_builtin_function_shader()
 {

src/glsl/ir.h

@@ -2439,6 +2439,10 @@ extern ir_function_signature *
 _mesa_glsl_find_builtin_function(_mesa_glsl_parse_state *state,
                                  const char *name, exec_list *actual_parameters);
 
+extern ir_function *
+_mesa_glsl_find_builtin_function_by_name(_mesa_glsl_parse_state *state,
+                                         const char *name);
+
 extern gl_shader *
 _mesa_glsl_get_builtin_function_shader(void);