From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.devel Subject: Re: Question regarding Lisp_Object representation of symbols Date: Wed, 6 Mar 2024 12:32:35 -0800 Organization: UCLA Computer Science Department Message-ID: References: <8634t3lfq7.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="28908"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Mozilla Thunderbird Cc: emacs-devel@gnu.org To: Eli Zaretskii , =?UTF-8?Q?Gerd_M=C3=B6llmann?= Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Wed Mar 06 21:33:39 2024 Return-path: Envelope-to: ged-emacs-devel@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1rhxxI-0007Dd-5e for ged-emacs-devel@m.gmane-mx.org; Wed, 06 Mar 2024 21:33:36 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rhxwX-0003h2-A2; Wed, 06 Mar 2024 15:32:51 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rhxwP-0003f5-QD for emacs-devel@gnu.org; Wed, 06 Mar 2024 15:32:43 -0500 Original-Received: from mail.cs.ucla.edu ([131.179.128.66]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rhxwO-0001Wd-3I; Wed, 06 Mar 2024 15:32:41 -0500 Original-Received: from localhost (localhost [127.0.0.1]) by mail.cs.ucla.edu (Postfix) with ESMTP id 7FD523C00E420; Wed, 6 Mar 2024 12:32:36 -0800 (PST) Original-Received: from mail.cs.ucla.edu ([127.0.0.1]) by localhost (mail.cs.ucla.edu [127.0.0.1]) (amavis, port 10032) with ESMTP id MsqKJ7Xgz-NE; Wed, 6 Mar 2024 12:32:36 -0800 (PST) Original-Received: from localhost (localhost [127.0.0.1]) by mail.cs.ucla.edu (Postfix) with ESMTP id 352E43C0140A4; Wed, 6 Mar 2024 12:32:36 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.10.3 mail.cs.ucla.edu 352E43C0140A4 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cs.ucla.edu; s=9D0B346E-2AEB-11ED-9476-E14B719DCE6C; t=1709757156; bh=0c9iK75OFAbkYIZzb4I+Tx89azT0Lor5rCU48s7qZkI=; h=Message-ID:Date:MIME-Version:To:From; b=Gs6pUaGNtIzT7XWCT62/libKwltfHn+XNCvJAkqdSYwIGTNoMKNzzgYtdshMar/Ff UotUwPi7YoACjPdrNVemaiCv8SHQa6Xc9bpXtb2eoGX51E0Twcfh3UU2DU7f4bZ74n jULgzHfCErOEp+elDeGCpNJ7xk7Yo9Uey+j2d2xoQW+LG0k4ya/gKcGYkX8JLPzot2 VkvrZlCepa0jMwwC7MOU+UQrqZCt7MsxheUrhzGkaALoqdftQhTUni45yEg9ouTMnq Icu0a8zXa2u6vwUxWuANudZIWWPLzQhyVnUFyDhLgAid/EaeGGYwSX0mpsBBtuZ4o5 R05k3J+mh1V1w== X-Virus-Scanned: amavis at mail.cs.ucla.edu Original-Received: from mail.cs.ucla.edu ([127.0.0.1]) by localhost (mail.cs.ucla.edu [127.0.0.1]) (amavis, port 10026) with ESMTP id jRdMjd_OiAul; Wed, 6 Mar 2024 12:32:36 -0800 (PST) Original-Received: from [192.168.254.12] (unknown [47.148.192.211]) by mail.cs.ucla.edu (Postfix) with ESMTPSA id 0F3B63C00E420; Wed, 6 Mar 2024 12:32:36 -0800 (PST) Content-Language: en-US In-Reply-To: <8634t3lfq7.fsf@gnu.org> Received-SPF: pass client-ip=131.179.128.66; envelope-from=eggert@cs.ucla.edu; helo=mail.cs.ucla.edu X-Spam_score_int: -19 X-Spam_score: -2.0 X-Spam_bar: -- X-Spam_report: (-2.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:316865 Archived-At: On 2024-03-06 04:14, Eli Zaretskii wrote: >> From: Gerd M=C3=B6llmann >> >> - Does someone remember the reasons why this has been done? Speed. It's significantly more efficient. >> - Is there something that relies on this? Maybe something that >> relies on 0x0 being a valid Lisp_Object? Yes, these assumptions are present in other places. I tried to mark all=20 these places with "verify (NIL_IS_ZERO)" a decade ago, though I wouldn't=20 be surprised if I missed one or two at the time, or if other=20 dependencies have crept in since then (notably in src/comp.c, which I=20 haven't audited for this).