From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: Crashes in "C-h h" Date: Sat, 06 Jul 2019 10:08:13 +0300 Message-ID: <837e8vabdu.fsf@gnu.org> References: <83y31hes6r.fsf@gnu.org> <83r279epwe.fsf@gnu.org> <09f72051-d740-9115-c6fd-c4344c749568@cs.ucla.edu> <83muhvd9nm.fsf@gnu.org> <9b78b85d-a3c8-761f-e500-d51d4a985fa8@cs.ucla.edu> <83k1cybk8c.fsf@gnu.org> <83ef36ar0p.fsf@gnu.org> <5e9b9214-4ccd-68a4-2016-7ac3ea8a06d9@cs.ucla.edu> <83wogwapf7.fsf@gnu.org> <83sgrkanbo.fsf@gnu.org> Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="90630"; mail-complaints-to="usenet@blaine.gmane.org" Cc: pipcet@gmail.com, emacs-devel@gnu.org To: Paul Eggert Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sat Jul 06 09:10:22 2019 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([209.51.188.17]) by blaine.gmane.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1hjepw-000NPJ-9v for ged-emacs-devel@m.gmane.org; Sat, 06 Jul 2019 09:10:20 +0200 Original-Received: from localhost ([::1]:58076 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hjepv-0001gb-9Y for ged-emacs-devel@m.gmane.org; Sat, 06 Jul 2019 03:10:19 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:52779) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hjeo0-0001gJ-TS for emacs-devel@gnu.org; Sat, 06 Jul 2019 03:08:21 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]:51182) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hjenz-0003IA-IJ; Sat, 06 Jul 2019 03:08:19 -0400 Original-Received: from [176.228.60.248] (port=1779 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from ) id 1hjeny-0000lo-NA; Sat, 06 Jul 2019 03:08:19 -0400 In-reply-to: (message from Paul Eggert on Fri, 5 Jul 2019 20:42:09 -0700) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] 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.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:238375 Archived-At: > Cc: emacs-devel@gnu.org > From: Paul Eggert > Date: Fri, 5 Jul 2019 20:42:09 -0700 > > > The comparison with > > > > if (FIXNUMP (x) && XFIXNUM (x) == n) > > > > is IMO not useful, because it should be clear up front that it will > > always lose due to the additional test. > > I suspect much of this thread is due to a misunderstanding then, as I > interpreted your earlier comment "It normally shouldn't matter either way" to > mean the opposite Sorry about that. I should have been clearer in my wording. The original code there was just if (XFIXNUM (x) == y) so that was my reference point for judging performance. > It is amusing that those benchmarks yield such wildly-different > results on different CPUs, though. That's a mystery in itself, yes. Whether we want to pursue it is another matter, as it seems to involve subtle aspects of code generation on modern CPUs, something we aren't the best specialists in.