rb_gc_register_address 1410 ext/curses/curses.c     rb_gc_register_address(&rb_stdscr);
rb_gc_register_address 1199 ext/iconv/iconv.c     rb_gc_register_address(&charset_map);
rb_gc_register_address  410 gc.c               rb_gc_register_address(var);
rb_gc_register_address  894 include/ruby/ruby.h void rb_gc_register_address(VALUE*);