From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.devel Subject: Re: Using __builtin_expect (likely/unlikely macros) Date: Sun, 14 Apr 2019 18:18:13 -0700 Organization: UCLA Computer Science Department Message-ID: References: <87a7gst973.fsf@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="267034"; mail-complaints-to="usenet@blaine.gmane.org" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 Cc: emacs-devel@gnu.org To: Alex Gramiak Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Mon Apr 15 03:19:02 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 (TLS1.0:RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1hFqH0-0017MW-Kd for ged-emacs-devel@m.gmane.org; Mon, 15 Apr 2019 03:19:02 +0200 Original-Received: from localhost ([127.0.0.1]:42933 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hFqGz-0007Gq-ME for ged-emacs-devel@m.gmane.org; Sun, 14 Apr 2019 21:19:01 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:58608) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hFqGI-0007Ga-BQ for emacs-devel@gnu.org; Sun, 14 Apr 2019 21:18:19 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hFqGH-0005BC-K5 for emacs-devel@gnu.org; Sun, 14 Apr 2019 21:18:18 -0400 Original-Received: from zimbra.cs.ucla.edu ([131.179.128.68]:51586) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hFqGH-0005Ah-AX for emacs-devel@gnu.org; Sun, 14 Apr 2019 21:18:17 -0400 Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 4459816171C; Sun, 14 Apr 2019 18:18:15 -0700 (PDT) Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id wHOzg3_eOg-o; Sun, 14 Apr 2019 18:18:14 -0700 (PDT) Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 8FBC4161727; Sun, 14 Apr 2019 18:18:14 -0700 (PDT) X-Virus-Scanned: amavisd-new at zimbra.cs.ucla.edu Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id jUdqMeVQCxNI; Sun, 14 Apr 2019 18:18:14 -0700 (PDT) Original-Received: from [192.168.1.9] (cpe-23-242-74-103.socal.res.rr.com [23.242.74.103]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id 6AD491616AA; Sun, 14 Apr 2019 18:18:14 -0700 (PDT) In-Reply-To: <87a7gst973.fsf@gmail.com> Content-Language: en-US X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 131.179.128.68 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 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:235468 Archived-At: Alex Gramiak wrote: > the likely/unlikely > macros are a nice way to indicate that a branch is exceedingly > rare/common. The cost (in making the C code harder to read, write and maintain) so often exceeds that benefit that I'd rather avoid these macros unless there's a good performance case for putting them in.