GCC主要数据结构之c_language_function

/* Global state pertinent to the current function.  Some C dialects
   extend this structure with additional fields.  */
struct GTY(()) c_language_function {
  /* While we are parsing the function, this contains information
     about the statement-tree that we are building.  */
  struct stmt_tree_s x_stmt_tree;
  /* Vector of locally defined typedefs, for
     -Wunused-local-typedefs.  */
  vec<tree, va_gc> *local_typedefs;
};