From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Lisp_Marker size on 32bit systems Date: Thu, 06 Sep 2018 08:17:40 -0400 Message-ID: References: <5a2c709e-aa49-b5b6-3fbe-fb8bd33acb23@cs.ucla.edu> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: blaine.gmane.org 1536236333 7326 195.159.176.226 (6 Sep 2018 12:18:53 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Thu, 6 Sep 2018 12:18:53 +0000 (UTC) User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) Cc: emacs-devel@gnu.org To: Paul Eggert Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Thu Sep 06 14:18:49 2018 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fxtFE-0001gY-FQ for ged-emacs-devel@m.gmane.org; Thu, 06 Sep 2018 14:18:44 +0200 Original-Received: from localhost ([::1]:33001 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fxtHK-000332-NB for ged-emacs-devel@m.gmane.org; Thu, 06 Sep 2018 08:20:54 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:41297) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fxtES-0001UR-34 for emacs-devel@gnu.org; Thu, 06 Sep 2018 08:17:58 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fxtEO-0000ev-CF for emacs-devel@gnu.org; Thu, 06 Sep 2018 08:17:56 -0400 Original-Received: from pruche.dit.umontreal.ca ([132.204.246.22]:46939) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fxtEO-0000e8-7w for emacs-devel@gnu.org; Thu, 06 Sep 2018 08:17:52 -0400 Original-Received: from pastel.home (lechon.iro.umontreal.ca [132.204.27.242]) by pruche.dit.umontreal.ca (8.14.7/8.14.1) with ESMTP id w86CHfvE011511; Thu, 6 Sep 2018 08:17:41 -0400 Original-Received: by pastel.home (Postfix, from userid 20848) id A5BCF6A61F; Thu, 6 Sep 2018 08:17:40 -0400 (EDT) In-Reply-To: <5a2c709e-aa49-b5b6-3fbe-fb8bd33acb23@cs.ucla.edu> (Paul Eggert's message of "Wed, 5 Sep 2018 23:51:30 -0700") X-NAI-Spam-Flag: NO X-NAI-Spam-Threshold: 5 X-NAI-Spam-Score: 0 X-NAI-Spam-Rules: 2 Rules triggered EDT_SA_DN_PASS=0, RV6368=0 X-NAI-Spam-Version: 2.3.0.9418 : core <6368> : inlines <6860> : streams <1797660> : uri <2704253> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 132.204.246.22 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 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.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:229338 Archived-At: >> used to be 24 (bytes) when we used Lisp_Misc, but it is now 32 >> (bytes) instead! > I'll take a look at it. Thanks. AFAICT the only solution is to use the GCALIGNED_UNION trick in each and every "real Lisp_Object struct" rather than once and forall in vectorlike_header. Maybe we should use a LISP_STRUCT macro like #define LISP_STRUCT(name, fields) \ struct name { union { struct { fields } s; GCALIGNED_UNION; } u; } > I was hoping those 8 bytes wouldn't make enough > difference to worry about, but evidently not.... It's really the 4 extra padding bytes incurred by all vectorlikes that annoy me. The resulting extra 8 bytes in markers is just a symptom ;-) Stefan