From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Conservative GC isn't safe Date: Mon, 28 Nov 2016 11:15:28 -0500 Message-ID: References: <66485157-00cd-4704-a421-cbfe84299cae@cs.ucla.edu> <805F5A19-BFAF-4CA4-AAD6-497C6D554830@raeburn.org> <6e5c928f-8130-08a6-d72d-1b64cc022846@cs.ucla.edu> <1CB11DFF-E6C2-4A1B-BE7E-8877DC38DB0A@raeburn.org> <83inr7zjjf.fsf@gnu.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: blaine.gmane.org 1480353964 3664 195.159.176.226 (28 Nov 2016 17:26:04 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 28 Nov 2016 17:26:04 +0000 (UTC) User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1.50 (gnu/linux) Cc: Ken Raeburn , emacs-devel@gnu.org, eggert@cs.ucla.edu To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Mon Nov 28 18:26:00 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 1cBPgl-0000GB-Cn for ged-emacs-devel@m.gmane.org; Mon, 28 Nov 2016 18:25:59 +0100 Original-Received: from localhost ([::1]:60263 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cBPgp-0004vf-91 for ged-emacs-devel@m.gmane.org; Mon, 28 Nov 2016 12:26:03 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:44432) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cBPgi-0004vI-Ra for emacs-devel@gnu.org; Mon, 28 Nov 2016 12:25:57 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cBPgi-0007XG-56 for emacs-devel@gnu.org; Mon, 28 Nov 2016 12:25:56 -0500 Original-Received: from ironport2-out.teksavvy.com ([206.248.154.181]:17567) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cBPgc-0007Ut-EQ; Mon, 28 Nov 2016 12:25:50 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: A0CaBgALW9BX/9qixEVdHAEBBAEBgy0BAQEBAR6ETYVQsXmGFgQCAoFpPRABAgEBAQEBAQFeJ4RiAQEDAVYjEAs0EhQYDSSIVQi8VQEBAQcCJYp9ihwFjx2KPJEVAYd3hguPDYE+NR+Ebh6GCgEBAQ X-IPAS-Result: A0CaBgALW9BX/9qixEVdHAEBBAEBgy0BAQEBAR6ETYVQsXmGFgQCAoFpPRABAgEBAQEBAQFeJ4RiAQEDAVYjEAs0EhQYDSSIVQi8VQEBAQcCJYp9ihwFjx2KPJEVAYd3hguPDYE+NR+Ebh6GCgEBAQ X-IronPort-AV: E=Sophos;i="5.30,296,1470715200"; d="scan'208";a="280853972" Original-Received: from 69-196-162-218.dsl.teksavvy.com (HELO pastel.home) ([69.196.162.218]) by smtp.teksavvy.com with ESMTP; 28 Nov 2016 12:25:47 -0500 Original-Received: by pastel.home (Postfix, from userid 20848) id D8A5F654B1; Mon, 28 Nov 2016 11:15:28 -0500 (EST) In-Reply-To: <83inr7zjjf.fsf@gnu.org> (Eli Zaretskii's message of "Mon, 28 Nov 2016 17:55:00 +0200") X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 206.248.154.181 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:209655 Archived-At: >> res = Fvector (ito - ifrom, aref_addr (string, ifrom)); > But 'string' still references the contents array of the vector, so GC > will mark it when it comes to 'string'. But after computing "aref_addr (string, ifrom)", it may very well be that `string` is dead and the compiler may then decide not to write it into the stack. Stefan