From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Alan Mackenzie Newsgroups: gmane.emacs.devel Subject: Re: Correct byte compiler error/warning positions. The solution! Date: Sat, 27 Nov 2021 10:33:07 +0000 Message-ID: References: <83pmqm16vz.fsf@gnu.org> <8335nh29pt.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="27268"; mail-complaints-to="usenet@ciao.gmane.io" Cc: emacs-devel@gnu.org To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Sat Nov 27 11:33:48 2021 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 1mqv1g-0006vu-CQ for ged-emacs-devel@m.gmane-mx.org; Sat, 27 Nov 2021 11:33:48 +0100 Original-Received: from localhost ([::1]:55804 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mqv1e-0003nC-To for ged-emacs-devel@m.gmane-mx.org; Sat, 27 Nov 2021 05:33:46 -0500 Original-Received: from eggs.gnu.org ([209.51.188.92]:49802) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mqv16-000354-MG for emacs-devel@gnu.org; Sat, 27 Nov 2021 05:33:12 -0500 Original-Received: from colin.muc.de ([193.149.48.1]:45854 helo=mail.muc.de) by eggs.gnu.org with smtp (Exim 4.90_1) (envelope-from ) id 1mqv14-0007SD-HR for emacs-devel@gnu.org; Sat, 27 Nov 2021 05:33:12 -0500 Original-Received: (qmail 11564 invoked by uid 3782); 27 Nov 2021 10:33:08 -0000 Original-Received: from acm.muc.de (p2e5d5030.dip0.t-ipconnect.de [46.93.80.48]) (using STARTTLS) by colin.muc.de (tmda-ofmipd) with ESMTP; Sat, 27 Nov 2021 11:33:07 +0100 Original-Received: (qmail 5059 invoked by uid 1000); 27 Nov 2021 10:33:07 -0000 Content-Disposition: inline In-Reply-To: <8335nh29pt.fsf@gnu.org> X-Submission-Agent: TMDA/1.3.x (Ph3nix) X-Primary-Address: acm@muc.de Received-SPF: pass client-ip=193.149.48.1; envelope-from=acm@muc.de; helo=mail.muc.de X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 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:280318 Archived-At: Hello, Eli. On Sat, Nov 27, 2021 at 12:07:10 +0200, Eli Zaretskii wrote: > > Date: Sat, 27 Nov 2021 09:31:05 +0000 > > Cc: emacs-devel@gnu.org > > From: Alan Mackenzie > > Hello, Eli. > > On Sat, Nov 27, 2021 at 07:53:36 +0200, Eli Zaretskii wrote: > > > > Date: Fri, 26 Nov 2021 19:56:21 +0000 > > > > From: Alan Mackenzie > > > > A _LOT_ of these comparisons were for NILP, which is just #defined as EQ > > > > (arg, Qnil). However if NILP were to be defined directly as arg == > > > > Qnil, it would bypass the overhead in EQ. > > > How can you use == when the operands could be structures? > > I meant that NILP will be implemented as a binary comparison against > > zero, omitting the awkward test for symbols_with_position_enabled. > Please don't write code that assumes Qnil is zero. (Or maybe I still > misunderstand what exactly you mean by the above.) Don't worry! The new code merely assumes Qnil is a symbol, and leaves it to the compiler to optimise for Qnil being binary zero. -- Alan Mackenzie (Nuremberg, Germany).