From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: The Emacs master is much slower than the emacs-27 branch. Date: Sat, 05 Dec 2020 11:05:42 +0200 Message-ID: <83k0twd3mh.fsf@gnu.org> References: <877dpyzg9d.fsf@rub.de> <87czzpsyqn.fsf@gmx.net> <83o8j9eqwx.fsf@gnu.org> <874kl1spe9.fsf@gmx.net> <83blf9em55.fsf@gnu.org> <87zh2tr82r.fsf@gmx.net> <87v9dhr7i5.fsf@gmx.net> <838sadefiw.fsf@gnu.org> <83360le421.fsf@gnu.org> <83y2idcn8q.fsf@gnu.org> <83wnxxcmjr.fsf@gnu.org> <83tut0d7e9.fsf@gnu.org> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="11750"; mail-complaints-to="usenet@ciao.gmane.io" Cc: acm@muc.de, stephen.berman@gmx.net, emacs-devel@gnu.org To: Gregory Heytings Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Sat Dec 05 10:07:24 2020 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 1klTXI-0002ya-Am for ged-emacs-devel@m.gmane-mx.org; Sat, 05 Dec 2020 10:07:24 +0100 Original-Received: from localhost ([::1]:53244 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1klTXH-0005Hs-EA for ged-emacs-devel@m.gmane-mx.org; Sat, 05 Dec 2020 04:07:23 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:59360) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1klTW1-0004nS-H6 for emacs-devel@gnu.org; Sat, 05 Dec 2020 04:06:06 -0500 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]:43036) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1klTW0-0007EV-HY; Sat, 05 Dec 2020 04:06:04 -0500 Original-Received: from [176.228.60.248] (port=1045 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from ) id 1klTVu-0000Z2-UR; Sat, 05 Dec 2020 04:06:02 -0500 In-Reply-To: (message from Gregory Heytings on Sat, 05 Dec 2020 08:14:24 +0000) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.23 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" Xref: news.gmane.io gmane.emacs.devel:260343 Archived-At: > Date: Sat, 05 Dec 2020 08:14:24 +0000 > From: Gregory Heytings > cc: acm@muc.de, stephen.berman@gmx.net, emacs-devel@gnu.org > > >> Sorry, I meant: it only improves compilation with -Og _and -O0_. I > >> don't know if -O0 is important. > > > > Given my measurements (see upthread), the effect on -O0 build is > > negligible. And yes, -O0 _is_ important. > > > > I don't know what happens on your computer (what is your > platform/compiler?) but on mine (Debian GNU/Linux with the latest Linux > kernel and the latest GCC) the effect on -O0 is almost the same as on -Og > for this particular benchmark. I just tried again on the emacs-27 branch: > > -Og: ~67s > -O0: ~63s > -O1: ~26s > -O2: ~18s > -O3: ~17s Well, this could be due to the fact that my builds are with "--enable-checking=yes,glyphs" and --with-wide-int. I wouldn't expect any of these to have such a profound effect on the difference between the two branches, though. To answer your question: this is GCC 9.2.0 on MS-Windows. In any case, this is not a bug, and doesn't affect the production code, so making that change on emacs-27 is out of the question.