compiler/glcpp: don't recalculate macro

The original code has a private helper called in one place doing a
lookup that it's parent has already done, which could be null, except
that the parent verified that it isn't. Instead, let's pass the pointer
from the parent and assert it's non-null in the child for good
measure/documentation.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/29666>

src/compiler/glsl/glcpp/glcpp-parse.y

@@ -1864,23 +1864,19 @@ _glcpp_parser_apply_pastes(glcpp_parser_t *parser, token_list_t *list)
  */
 static token_list_t *
 _glcpp_parser_expand_function(glcpp_parser_t *parser, token_node_t *node,
-                              token_node_t **last, expansion_mode_t mode)
+                              token_node_t **last, expansion_mode_t mode,
+                              macro_t *macro)
 {
-   struct hash_entry *entry;
-   macro_t *macro;
    const char *identifier;
    argument_list_t *arguments;
    function_status_t status;
    token_list_t *substituted;
    int parameter_index;
 
-   identifier = node->token->value.str;
-
-   entry = _mesa_hash_table_search(parser->defines, identifier);
-   macro = entry ? entry->data : NULL;
-
+   assert(macro);
    assert(macro->is_function);
 
+   identifier = node->token->value.str;
    arguments = _argument_list_create(parser);
    status = _arguments_parse(parser, arguments, node, last);
 
@@ -2053,7 +2049,7 @@ _glcpp_parser_expand_node(glcpp_parser_t *parser, token_node_t *node,
       return replacement;
    }
 
-   return _glcpp_parser_expand_function(parser, node, last, mode);
+   return _glcpp_parser_expand_function(parser, node, last, mode, macro);
 }
 
 /* Push a new identifier onto the parser's active list.