anchor.diff:                (t ;; Flatten the body as much as possible.
                  (setf (cdr tail) (flatten x)
                        tail (last tail))))))
  -    ;; Kill code after GO statements and try to eliminate no-op GOs.
  +    ;; Kill code after GO/RETURN-FROM statements and try to eliminate no-op GOs.
  +    ;; Remove forms with no effect as well.
       (do* ((i (statements form) (cdr i))
             (prev nil)
             (last-was-go nil))
  
positive.code:                (if prev
                     (setf (cdr prev) (cdr i))
                     (setf (statements form) (cdr i))))
                ((typep stmt 'ast-go)
                 (cond ((eql (cadr i) (target stmt))
                        ;; This GO can be eliminated.
                        (change-made)
  
negative.code:     ;; Reduce tagbodys with no tags to progn.
      (cond ((tagbody-information-go-tags (info form))
             ;; Has go tags.
             form)
            ((endp (statements form))
             ;; Empty tagbody.
             (change-made)
             (ast `(quote nil)))
            (t
             ;; Non-empty tagbody with no go tags.
  