GNU bug report logs - #17475
24.3.91; bug of byte-optimize-zerop

Previous Next

To add a comment to this bug, you must first unarchive it, by sending
a message to control AT debbugs.gnu.org, with unarchive 17475 in the body.
You can then email your comments to 17475 AT debbugs.gnu.org in the normal way.

Toggle the display of automated, internal messages from the tracker.

Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Shigeru Fukaya <shigeru.fukaya <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 24.3.91; bug of byte-optimize-zerop
Date: Tue, 13 May 2014 00:11:11 +0900

`byte-optimize-zerop' is badly implemented.  Even when
`byte-compile-delete-errors' is non-nil, bute-compiled code may
signal an error.
(= FORM 0) and (zerop FORM) are functionally equal, besides, the
former is better when byte-compiled.

The following is the poor alternative.
I can't make a smart code without creating a new function.

(defun byte-optimize-zerop (form)
  (cond ((numberp (nth 1 form))
         (eval form))
        (byte-compile-delete-errors
         `(and (member ,(nth 1 form) (quote 0 0.0))) t)
        ((list '= (nth 1 form) 0))))

-- Shigeru

Message #8 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Shigeru Fukaya <shigeru.fukaya <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: Re: 24.3.91; bug of byte-optimize-zerop
Date: Sat, 17 May 2014 06:11:55 +0900

>`byte-optimize-zerop' is badly implemented.  Even when
>`byte-compile-delete-errors' is non-nil, bute-compiled code may
>signal an error.
>(= FORM 0) and (zerop FORM) are functionally equal, besides, the
>former is better when byte-compiled.
>
>The following is the poor alternative.
>I can't make a smart code without creating a new function.
>
>(defun byte-optimize-zerop (form)
>  (cond ((numberp (nth 1 form))
>         (eval form))
>        (byte-compile-delete-errors
>         `(and (member ,(nth 1 form) (quote 0 0.0))) t)
>        ((list '= (nth 1 form) 0))))
>
>-- Shigeru

zerop itself is not an error-free fuction.
I'll change my poroposal code.

(defun byte-optimize-zerop (form)
  (cond ((numberp (nth 1 form))
         (eval form))
	((list '= (nth 1 form) 0))))

-- Shigeru

Message #11 received at 17475 <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Shigeru Fukaya <shigeru.fukaya <at> gmail.com>
Cc: 17475 <at> debbugs.gnu.org
Subject: Re: bug#17475: 24.3.91; bug of byte-optimize-zerop
Date: Tue, 20 May 2014 14:32:49 -0400

> zerop itself is not an error-free fuction.
> I'll change my poroposal code.

> (defun byte-optimize-zerop (form)
>   (cond ((numberp (nth 1 form))
>          (eval form))
> 	((list '= (nth 1 form) 0))))

Actually, you can drop the first option since the optimizer rules for
`=' will take care of it for us.


        Stefan

Message #16 received at 17475-done <at> debbugs.gnu.org (full text, mbox):

From: Stefan Monnier <monnier <at> iro.umontreal.ca>
To: Shigeru Fukaya <shigeru.fukaya <at> gmail.com>
Cc: 17475-done <at> debbugs.gnu.org
Subject: Re: bug#17475: 24.3.91; bug of byte-optimize-zerop
Date: Tue, 27 May 2014 20:51:40 -0400

> (defun byte-optimize-zerop (form)
>   (cond ((numberp (nth 1 form))
>          (eval form))
> 	((list '= (nth 1 form) 0))))

I simplified as suggested and turned it into a compiler-macro.
Thank you for paying attention to details.


        Stefan

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.