# -- next MAIN_LOOP jumps here unless there's a continue block too
MAIN_LOOP: while (<>) {
    # -- redo MAIN_LOOP or goto MAIN_LOOP jumps here
    ....
        a()
    ....
    }
sub a {
    ....
        myerror ();
    ....
    }
sub myerror {
    redo MAIN_LOOP;
    }