From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: MPS prstack Date: Mon, 27 May 2024 16:12:51 +0300 Message-ID: <86ed9nv1nw.fsf@gnu.org> References: <87o790qsgm.fsf@gmail.com> <874jap95hi.fsf@gmail.com> <874janpa4m.fsf@gmail.com> <87le3vogt8.fsf@gmail.com> <87a5kbobt4.fsf@gmail.com> <86sey3v5p8.fsf@gnu.org> <87ed9nmnsm.fsf@gmail.com> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="1162"; mail-complaints-to="usenet@ciao.gmane.io" Cc: gerd.moellmann@gmail.com, emacs-devel@gnu.org To: Helmut Eller Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Mon May 27 15:13:46 2024 Return-path: Envelope-to: ged-emacs-devel@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 1sBaAb-000AeD-Sz for ged-emacs-devel@m.gmane-mx.org; Mon, 27 May 2024 15:13:46 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sBa9o-0006hg-8f; Mon, 27 May 2024 09:12:56 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sBa9n-0006hU-7P for emacs-devel@gnu.org; Mon, 27 May 2024 09:12:55 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sBa9m-0003kF-R6; Mon, 27 May 2024 09:12:54 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=gnu.org; s=fencepost-gnu-org; h=References:Subject:In-Reply-To:To:From:Date: mime-version; bh=SU9AbSEGgp44oKwwGUcEWRRdLN6fnnpJ1pq4honh56s=; b=jNi1H0UDbTmI yFA0QxZy1aXNL5oXhD6fVuct97uB/i+w9WDcJZClqcScdUJiFF6O689d1TvIt/zxcdRHqAkxkToBw sEaG3Mwf+fB6t23PCb2BoDXfj4CBtTUX95G8+QjPICXgs4mp/KmO0WqCPZBlnK212day6CyV6ozeD rxpKjWggsMtRdIyifAxuXBX798ODRFFjwZ1+TWPB7m1Qzy2c01CMzWsSgEi55yLGjZouZiiRIqqQ2 7qn+hMQvYBEWy90Nl1hMMVYYRw4cWMB3HFFNnDqFqHbVoS5k74b4ZLXdkq8kwvvbtTjmcc0JUJEUU XFdVHJXwif9Mus6rKr2PkA==; In-Reply-To: <87ed9nmnsm.fsf@gmail.com> (message from Helmut Eller on Mon, 27 May 2024 14:39:37 +0200) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 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-mx.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:319608 Archived-At: > From: Helmut Eller > Cc: gerd.moellmann@gmail.com, emacs-devel@gnu.org > Date: Mon, 27 May 2024 14:39:37 +0200 > > On Mon, May 27 2024, Eli Zaretskii wrote: > > >> But my question was more whether MPS actually does call scan_prstack at > >> "any moment" or if this is just a theoretical possibility for some > >> possible future version of MPS. > > > > Why is all this order important, can you elaborate? Neither MPS nor > > we can rely on the order in which the generated code does this stuff, > > AFAIU. > > It is important because scan_prstack only scans the region > prstack.stack[0..prstack.sp] and because scan_prstack runs (potentially) > concurrent to print_stack_push. > > If print_stack_push increments prstack.sp before initializing > prstack.stack[prstack.sp], then scan_prstack may read the old value out > of that slot. If we need to make sure that "prstack.stack[prstack.sp++] = e;" is done atomically, maybe we can use the __atomic builtins (see the node "__atomic Builtins" in the GCC manual).