From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Alan Mackenzie Newsgroups: gmane.emacs.devel Subject: Re: Making 'eq' == 'eql' in bignum branch Date: Sun, 26 Aug 2018 20:19:47 +0000 Message-ID: <20180826201947.GC1867@ACM> References: <09153aed-361d-4f82-d9ac-b502314769ae@cs.ucla.edu> <83lg91dqd4.fsf@gnu.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: blaine.gmane.org 1535315197 28035 195.159.176.226 (26 Aug 2018 20:26:37 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 26 Aug 2018 20:26:37 +0000 (UTC) User-Agent: Mutt/1.10.1 (2018-07-13) Cc: rms@gnu.org, emacs-devel@gnu.org, monnier@iro.umontreal.ca, pipcet@gmail.com, Lars Ingebrigtsen , eliz@gnu.org To: Paul Eggert Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sun Aug 26 22:26:32 2018 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fu1cG-0007Dc-Ef for ged-emacs-devel@m.gmane.org; Sun, 26 Aug 2018 22:26:32 +0200 Original-Received: from localhost ([::1]:50276 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fu1eM-0005tl-Pu for ged-emacs-devel@m.gmane.org; Sun, 26 Aug 2018 16:28:42 -0400 Original-Received: from eggs.gnu.org ([208.118.235.92]:41218) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fu1bW-0004dZ-Mb for emacs-devel@gnu.org; Sun, 26 Aug 2018 16:25:49 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fu1V8-0003fP-8m for emacs-devel@gnu.org; Sun, 26 Aug 2018 16:19:12 -0400 Original-Received: from colin.muc.de ([193.149.48.1]:28608 helo=mail.muc.de) by eggs.gnu.org with smtp (Exim 4.71) (envelope-from ) id 1fu1V8-0003f6-11 for emacs-devel@gnu.org; Sun, 26 Aug 2018 16:19:10 -0400 Original-Received: (qmail 9483 invoked by uid 3782); 26 Aug 2018 20:19:09 -0000 Original-Received: from acm.muc.de (p5B146EC2.dip0.t-ipconnect.de [91.20.110.194]) by colin.muc.de (tmda-ofmipd) with ESMTP; Sun, 26 Aug 2018 22:19:06 +0200 Original-Received: (qmail 4049 invoked by uid 1000); 26 Aug 2018 20:19:47 -0000 Content-Disposition: inline In-Reply-To: X-Delivery-Agent: TMDA/1.1.12 (Macallan) X-Primary-Address: acm@muc.de X-detected-operating-system: by eggs.gnu.org: FreeBSD 9.x [fuzzy] X-Received-From: 193.149.48.1 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:228948 Archived-At: Hello, Paul. On Sat, Aug 25, 2018 at 16:27:20 -0700, Paul Eggert wrote: [ .... ] > * Several modules assumes that buffer sizes fits into fixnums. This > assumption is correct for Emacs master, though it will become dubious > if we change Emacs to support buffer sizes greater than > most-positive-fixnum. The affected modules are emacs-lisp/syntax.el, > org/org-list.el, progmodes/cc-engine.el, progmodes/js.el, and > simple.el. I'm trying to imagine a buffer whose size won't fit into a fixnum, on a 64-bit machine. most-positive-fixnum is close to 2^61. Imagine scrolling through a 2^61 byte buffer. Let's imagine it has an average line length of 64 bytes, in a window 64 lines deep, and auto-repeat is at 16 screens per second. That's 2^(6+6+4) characters per second scroll rate, i.e. 2^16. So the number of seconds it would take would be 2^(61 - 16) = 2^45. 2^45 seconds = 2^45 / 86400 / 365.25 years, this being a little over 1.1 million years. Holding the PageDown key down for this length of time would get a little tedious. Surely, at least for 64-bit systems, expecting buffer sizes ever to exceed fixnums, is somewhat unrealistic. Is anybody seriously going to be editing a 540 Mbyte buffer on a 32-bit system nowadays? Surely the assumption of buffer sizes being fixnums is realistic and harmless. -- Alan Mackenzie (Nuremberg, Germany).