From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.devel Subject: Re: Conservative GC isn't safe Date: Sat, 26 Nov 2016 16:24:34 -0800 Message-ID: <741b189f-2f2a-33b5-ba70-fa72499f27ef@cs.ucla.edu> References: NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Trace: blaine.gmane.org 1480206322 29048 195.159.176.226 (27 Nov 2016 00:25:22 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 27 Nov 2016 00:25:22 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 Cc: Emacs developers To: Pip Cet , Daniel Colascione Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sun Nov 27 01:25:14 2016 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 1cAnHO-0006aH-Cn for ged-emacs-devel@m.gmane.org; Sun, 27 Nov 2016 01:25:14 +0100 Original-Received: from localhost ([::1]:52183 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cAnHS-0002BG-43 for ged-emacs-devel@m.gmane.org; Sat, 26 Nov 2016 19:25:18 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:60627) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cAnGs-0002BB-G2 for emacs-devel@gnu.org; Sat, 26 Nov 2016 19:24:43 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cAnGn-0006ql-JP for emacs-devel@gnu.org; Sat, 26 Nov 2016 19:24:42 -0500 Original-Received: from zimbra.cs.ucla.edu ([131.179.128.68]:38092) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cAnGn-0006qX-Cz for emacs-devel@gnu.org; Sat, 26 Nov 2016 19:24:37 -0500 Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id ECCE6160069; Sat, 26 Nov 2016 16:24:35 -0800 (PST) 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 6IUnY6nTes8u; Sat, 26 Nov 2016 16:24:35 -0800 (PST) Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 46135160076; Sat, 26 Nov 2016 16:24:35 -0800 (PST) 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 SULVr2t5kQYO; Sat, 26 Nov 2016 16:24:35 -0800 (PST) Original-Received: from [192.168.0.104] (unknown [47.153.178.162]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id 1B2E3160069; Sat, 26 Nov 2016 16:24:35 -0800 (PST) In-Reply-To: X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] 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:209626 Archived-At: On 11/26/2016 11:08 AM, Pip Cet wrote: > There's a new, currently undocumented, GCC option called > -fkeep-gc-roots-live, which I think addresses this problem. Thanks, I hadn't heard about this option. Apparently it's designed for Go, whose garbage collector follows pointers to any part of the pointed-at object. Although this doesn't match Emacs's current GC, it should be an improvement. Perhaps someone could try using this option to build Emacs, to see whether it hurts performance or correctness.