From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.devel Subject: Re: [Emacs-diffs] trunk r117941: Default to stack objects on non-GNU/Linux, non-DOS_NT platforms. Date: Thu, 25 Sep 2014 12:08:05 -0700 Organization: UCLA Computer Science Department Message-ID: <54246815.7030301@cs.ucla.edu> References: <837g0sw1yx.fsf@gnu.org> <5423E5B0.4070002@yandex.ru> <54243ED1.4060708@yandex.ru> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Trace: ger.gmane.org 1411672166 26845 80.91.229.3 (25 Sep 2014 19:09:26 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 25 Sep 2014 19:09:26 +0000 (UTC) Cc: Eli Zaretskii , Emacs development discussions To: Stefan Monnier , Dmitry Antipov Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Thu Sep 25 21:09:19 2014 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 1XXEPm-0001ei-Ho for ged-emacs-devel@m.gmane.org; Thu, 25 Sep 2014 21:09:18 +0200 Original-Received: from localhost ([::1]:41948 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XXEPm-0005ZE-3i for ged-emacs-devel@m.gmane.org; Thu, 25 Sep 2014 15:09:18 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:43858) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XXEP7-0004pU-9f for emacs-devel@gnu.org; Thu, 25 Sep 2014 15:08:44 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XXEOz-0000nf-LR for emacs-devel@gnu.org; Thu, 25 Sep 2014 15:08:37 -0400 Original-Received: from smtp.cs.ucla.edu ([131.179.128.62]:42395) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XXEOr-0000jy-KX; Thu, 25 Sep 2014 15:08:21 -0400 Original-Received: from localhost (localhost.localdomain [127.0.0.1]) by smtp.cs.ucla.edu (Postfix) with ESMTP id E511DA60038; Thu, 25 Sep 2014 12:08:14 -0700 (PDT) X-Virus-Scanned: amavisd-new at smtp.cs.ucla.edu Original-Received: from smtp.cs.ucla.edu ([127.0.0.1]) by localhost (smtp.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id HtzyI5W6u+QB; Thu, 25 Sep 2014 12:08:06 -0700 (PDT) Original-Received: from penguin.cs.ucla.edu (Penguin.CS.UCLA.EDU [131.179.64.200]) by smtp.cs.ucla.edu (Postfix) with ESMTPSA id 3DFB2A60036; Thu, 25 Sep 2014 12:08:06 -0700 (PDT) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.1.0 In-Reply-To: X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6.x X-Received-From: 131.179.128.62 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:174713 Archived-At: On 09/25/2014 11:12 AM, Stefan Monnier wrote: > I saw this extra checking in > local_cons, I figured this is going to kill too much of the > performance gain. I agree that the performance gains are iffy, and would like to see some measurements here. If it's any consolation, in some cases the new MAX_ALLOCA checking is optimized away. For example, other_buffer_safely calls build_local_string twice, both with constant literals, and in both cases my compiler (GCC 4.9.1 x86-64) deduces that there's no need to check for MAX_ALLOCA, and generates code that creates the Lisp string on the stack unconditionally.