XEmacs 21.2.47 (Zephir).

[chise/xemacs-chise.git.1] / lisp / byte-optimize.el

diff --git a/lisp/byte-optimize.el b/lisp/byte-optimize.el
index ff6edde..dad9de8 100644 (file)
--- a/lisp/byte-optimize.el
+++ b/lisp/byte-optimize.el
@@ -473,12 +473,12 @@
                 (if (and (cdr form) (null backwards))
                     (byte-compile-log
                      "  all subforms of %s called for effect; deleted" form))
-                (and backwards
-                      ;; Now optimize the rest of the forms. We need the return
-                      ;; values. We already did the car.
-                      (setcdr backwards
-                              (mapcar 'byte-optimize-form (cdr backwards)))
-                     (cons fn (nreverse backwards))))
+                (when backwards
+                  ;; Now optimize the rest of the forms. We need the return
+                  ;; values. We already did the car.
+                  (setcdr backwards
+                          (mapcar 'byte-optimize-form (cdr backwards))))
+                (cons fn (nreverse backwards)))
             (cons fn (mapcar 'byte-optimize-form (cdr form)))))
 
          ((eq fn 'interactive)
@@ -729,9 +729,15 @@
       (decf (nth 1 form) last)
       (butlast form))
 
-     ;; (- 0 x ...)  -->  (- (- x) ...)
-     ((and (eq 0 (nth 1 form)) (>= (length form) 3))
-      `(- (- ,(nth 2 form)) ,@(nthcdr 3 form)))
+     ;; (- 0 ...) -->
+     ((eq 0 (nth 1 form))
+      (case (length form)
+       ;; (- 0) --> 0
+       (2 0)
+       ;; (- 0 x)  -->  (- x)
+       (3 `(- ,(nth 2 form)))
+       ;; (- 0 x y ...)  -->  (- (- x) y ...)
+       (t `(- (- ,(nth 2 form)) ,@(nthcdr 3 form)))))
 
      (t (byte-optimize-predicate form)))))