From: Mattias Engdegård <mattiase@acm.org>
Date: Thu, 26 Dec 2019 16:50:19 +0000 (+0100)
Subject: Optimise 'while' bodies for effect
X-Git-Tag: emacs-28.0.90~7934
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=1ba5b64dd1f0c0b22f3945ddc8b236fd565ebee8;p=emacs.git

Optimise 'while' bodies for effect

* lisp/emacs-lisp/byte-opt.el (byte-optimize-form-code-walker):
Treat all expressions in the body of 'while' as for-effect,
since their values are discarded.  This also finds some errors.
---

diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el
index 22fea1b8da9..07fd548dec2 100644
--- a/lisp/emacs-lisp/byte-opt.el
+++ b/lisp/emacs-lisp/byte-opt.el
@@ -480,6 +480,13 @@
                                                  backwards)))))
 	     (cons fn (mapcar 'byte-optimize-form (cdr form)))))
 
+	  ((eq fn 'while)
+           (unless (consp (cdr form))
+	     (byte-compile-warn "too few arguments for `while'"))
+           (cons fn
+                 (cons (byte-optimize-form (cadr form) nil)
+                       (byte-optimize-body (cddr form) t))))
+
 	  ((eq fn 'interactive)
 	   (byte-compile-warn "misplaced interactive spec: `%s'"
 			      (prin1-to-string form))