From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: "Stephen J. Turnbull" Newsgroups: gmane.emacs.devel Subject: Re: [RFC, PATCH] shrink struct vectorlike_header #2 Date: Thu, 08 Nov 2012 15:56:04 +0900 Message-ID: <874nl0vb0b.fsf@uwakimon.sk.tsukuba.ac.jp> References: <50766A2C.8070705@yandex.ru> <50994448.6020602@yandex.ru> <509A76F7.3050105@yandex.ru> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 X-Trace: ger.gmane.org 1352357780 25554 80.91.229.3 (8 Nov 2012 06:56:20 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 8 Nov 2012 06:56:20 +0000 (UTC) Cc: Dmitry Antipov , Emacs development discussions To: Stefan Monnier Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Thu Nov 08 07:56:26 2012 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1TWM2L-0004yz-2s for ged-emacs-devel@m.gmane.org; Thu, 08 Nov 2012 07:56:25 +0100 Original-Received: from localhost ([::1]:38154 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TWM2B-0004yI-Nl for ged-emacs-devel@m.gmane.org; Thu, 08 Nov 2012 01:56:15 -0500 Original-Received: from eggs.gnu.org ([208.118.235.92]:50073) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TWM29-0004y9-Sp for emacs-devel@gnu.org; Thu, 08 Nov 2012 01:56:14 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TWM28-0007SM-VC for emacs-devel@gnu.org; Thu, 08 Nov 2012 01:56:13 -0500 Original-Received: from mgmt2.sk.tsukuba.ac.jp ([130.158.97.224]:54177) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TWM28-0007R6-Ki for emacs-devel@gnu.org; Thu, 08 Nov 2012 01:56:12 -0500 Original-Received: from uwakimon.sk.tsukuba.ac.jp (uwakimon.sk.tsukuba.ac.jp [130.158.99.156]) by mgmt2.sk.tsukuba.ac.jp (Postfix) with ESMTP id 738229708DE; Thu, 8 Nov 2012 15:56:04 +0900 (JST) Original-Received: by uwakimon.sk.tsukuba.ac.jp (Postfix, from userid 1000) id 37F651A3271; Thu, 8 Nov 2012 15:56:04 +0900 (JST) In-Reply-To: X-Mailer: VM undefined under 21.5 (beta32) "habanero" b0d40183ac79 XEmacs Lucid (x86_64-unknown-linux) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6.x X-Received-From: 130.158.97.224 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 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-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:154726 Archived-At: Stefan Monnier writes: > I doubt (*(struct Lisp_Vector **)((char *) v + header_size)) > is any better. I guess it just defeats gcc's detection of the > problem. Not true, in general. Martin Buchholz (IIRC) reported that (at least for some constructs, for some versions of GCC, and specific optimization settings -- this was a few years ago) such gymnastics change the code generated (presumably from something incorrect to something correct).