From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.ciao.gmane.io!not-for-mail From: Andrea Corallo Newsgroups: gmane.emacs.bugs Subject: bug#41357: 28.0.50; GC may miss to mark calle safe register content Date: Sun, 17 May 2020 18:16:24 +0000 Message-ID: References: <83pnb2bmk2.fsf@gnu.org> <83eeribiim.fsf@gnu.org> <83a726bhn1.fsf@gnu.org> <835zcubg1j.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="ciao.gmane.io:159.69.161.202"; logging-data="126400"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) Cc: 41357@debbugs.gnu.org, eggert@cs.ucla.edu To: Eli Zaretskii Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Sun May 17 20:17:09 2020 Return-path: Envelope-to: geb-bug-gnu-emacs@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 1jaNqW-000Wkd-RA for geb-bug-gnu-emacs@m.gmane-mx.org; Sun, 17 May 2020 20:17:08 +0200 Original-Received: from localhost ([::1]:49302 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jaNqV-0007rI-M8 for geb-bug-gnu-emacs@m.gmane-mx.org; Sun, 17 May 2020 14:17:07 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:40394) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jaNqQ-0007rA-1c for bug-gnu-emacs@gnu.org; Sun, 17 May 2020 14:17:02 -0400 Original-Received: from debbugs.gnu.org ([209.51.188.43]:33152) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jaNqP-0002XO-OX for bug-gnu-emacs@gnu.org; Sun, 17 May 2020 14:17:01 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1jaNqP-00008w-JI for bug-gnu-emacs@gnu.org; Sun, 17 May 2020 14:17:01 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Andrea Corallo Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Sun, 17 May 2020 18:17:01 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 41357 X-GNU-PR-Package: emacs X-Debbugs-Original-Cc: bug-gnu-emacs@gnu.org, eggert@cs.ucla.edu Original-Received: via spool by submit@debbugs.gnu.org id=B.1589739391512 (code B ref -1); Sun, 17 May 2020 18:17:01 +0000 Original-Received: (at submit) by debbugs.gnu.org; 17 May 2020 18:16:31 +0000 Original-Received: from localhost ([127.0.0.1]:44698 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1jaNpv-00008B-F8 for submit@debbugs.gnu.org; Sun, 17 May 2020 14:16:31 -0400 Original-Received: from lists.gnu.org ([209.51.188.17]:48320) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1jaNpu-000084-0V for submit@debbugs.gnu.org; Sun, 17 May 2020 14:16:30 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:40374) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jaNpt-0007kn-RP for bug-gnu-emacs@gnu.org; Sun, 17 May 2020 14:16:29 -0400 Original-Received: from mx.sdf.org ([205.166.94.20]:64883) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jaNps-0002Od-Eu; Sun, 17 May 2020 14:16:29 -0400 Original-Received: from sdf.org (ma.sdf.org [205.166.94.33]) by mx.sdf.org (8.15.2/8.14.5) with ESMTPS id 04HIGOLP018945 (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256 bits) verified NO); Sun, 17 May 2020 18:16:24 GMT Original-Received: (from akrl@localhost) by sdf.org (8.15.2/8.12.8/Submit) id 04HIGOiI019015; Sun, 17 May 2020 18:16:24 GMT In-Reply-To: <835zcubg1j.fsf@gnu.org> (Eli Zaretskii's message of "Sun, 17 May 2020 20:57:28 +0300") Received-SPF: pass client-ip=205.166.94.20; envelope-from=akrl@sdf.org; helo=mx.sdf.org X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/17 12:40:18 X-ACL-Warn: Detected OS = ??? 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, RCVD_IN_DNSWL_NONE=-0.0001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.io gmane.emacs.bugs:180499 Archived-At: Eli Zaretskii writes: >> From: Andrea Corallo >> Cc: bug-gnu-emacs@gnu.org, eggert@cs.ucla.edu >> Date: Sun, 17 May 2020 17:45:28 +0000 >> >> Lisp_Object >> foo (void) >> { >> /* 'res' goes in a callee saved reg */ >> Lisp_Object res = build_string ("bar"); >> [...] >> /* LTO inline the following as "flush_stack_call_func (mark_threads_callback, NULL);" */ >> mark_threads (); >> [...] >> gc_sweep (); >> >> /* The string pointed by 'res' was garbage collected. */ >> return res; >> } > > But mark_threads etc. (GC in general) isn't called from functions like > your 'foo. It is more like this: > > Lisp_Object > foo (void) > { > /* 'res' goes in a callee saved reg */ > Lisp_Object res = build_string ("bar"); > [...] > call_something (); > [...] > > } > > call_something (void) > { > [...] > garbage_collect (); > [...] > } Yes, my example was minimal your is certanly more realistic. But also this can be critical. We have to hope that in 'call_something' or 'garbage_collect' there is sufficient register pressure to have the register that is holding 'res' to be pushed. Andrea -- akrl@sdf.org