(byte-optimize-approx-equal): Use <=, not <.

(byte-optimize-minus, byte-optimize-plus): Optimize adding
or subtracting 1.

1 files changed, 19 insertions, 1 deletions

diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el
index 4b7b9f305e6..c75dbe4b696 100644
--- a/lisp/emacs-lisp/byte-opt.el
+++ b/lisp/emacs-lisp/byte-opt.el
@@ -643,7 +643,7 @@
 ;;      form))
 
 (defun byte-optimize-approx-equal (x y)
-  (< (* (abs (- x y)) 100) (abs (+ x y))))
+  (<= (* (abs (- x y)) 100) (abs (+ x y))))
 
 ;; Collect all the constants from FORM, after the STARTth arg,
 ;; and apply FUN to them to make one argument at the end.
@@ -694,6 +694,20 @@
 ;;; (actually, it would be safe if we know the sole arg
 ;;; is not a marker).
 ;;      ((null (cdr (cdr form))) (nth 1 form))
+        ((and (null (nthcdr 3 form))
+              (or (memq (nth 1 form) '(1 -1))
+                  (memq (nth 2 form) '(1 -1))))
+         ;; Optiize (+ x 1) into (1+ x) and (+ x -1) into (1- x).
+         (let ((integer
+                (if (memq (nth 1 form) '(1 -1))
+                    (nth 1 form)
+                  (nth 2 form)))
+               (other
+                (if (memq (nth 1 form) '(1 -1))
+                    (nth 2 form)
+                  (nth 1 form))))
+           (list (if (eq integer 1) '1+ '1-)
+                 other)))
         (t form)))
 
 (defun byte-optimize-minus (form)
@@ -705,6 +719,10 @@
            ;; (- x y ... 0)  --> (- x y ...)
            (setq form (copy-sequence form))
            (setcdr (cdr (cdr form)) (delq 0 (nthcdr 3 form))))
+          ((equal (nthcdr 2 form) '(1))
+           (setq form (list '1- (nth 1 form))))
+          ((equal (nthcdr 2 form) '(-1))
+           (setq form (list '1+ (nth 1 form))))
           ;; If form is (- CONST foo... CONST), merge first and last.
           ((and (numberp (nth 1 form))
                 (numberp last))