From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Po Lu Newsgroups: gmane.emacs.devel Subject: Re: HAVE_FAST_UNALIGNED_ACCESS Date: Sun, 02 Apr 2023 08:48:02 +0800 Message-ID: <87ilefrtx9.fsf@yahoo.com> References: <87sfdmlgzx.fsf@gmail.com> <94d3de92c50a96d9172f88462bf3bc9c2792600c.camel@gmail.com> <83mt3s244o.fsf@gnu.org> <875yagtopn.fsf@yahoo.com> <838rfc17ja.fsf@gnu.org> <871ql4t8ph.fsf@yahoo.com> <83wn2wyuli.fsf@gnu.org> <63A29442-4C0C-4C3C-B40E-4A3DB91E3009@gmail.com> <83lejcypyw.fsf@gnu.org> <87wn2wrmgc.fsf@yahoo.com> <83bkk7zvxl.fsf@gnu.org> <87lejbpxkm.fsf@aarsen.me> <83zg7rybfo.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="10456"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Cc: Arsen =?utf-8?Q?Arsenovi=C4=87?= , mattias.engdegard@gmail.com, vibhavp@gmail.com, rpluim@gmail.com, emacs-devel@gnu.org To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Sun Apr 02 02:49:06 2023 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 1pilu5-0002Yb-1o for ged-emacs-devel@m.gmane-mx.org; Sun, 02 Apr 2023 02:49:05 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1piltM-0007FC-Ud; Sat, 01 Apr 2023 20:48:21 -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 1piltK-0007Eo-8l for emacs-devel@gnu.org; Sat, 01 Apr 2023 20:48:18 -0400 Original-Received: from sonic310-25.consmr.mail.ne1.yahoo.com ([66.163.186.206]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1piltI-0000Rg-NC for emacs-devel@gnu.org; Sat, 01 Apr 2023 20:48:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1680396493; bh=4ER7BXTyUHE7tK/j7/hrh/D8TMkjMtTDv0roo8A9Gl4=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From:Subject:Reply-To; b=G6f+o9qP8tj8ItudEGjAad2ulG+2hPeW9Pc5FC1pCXTjPPt5Ua3WqP+AeBJd9EJ8khBk4oDVROrRkU0rQpIjX8n+Qwzp/xWUGnfkiC2F9EIj3Mz8McBWZt9Vzfy6gI0dFDiev0KObB9B+oEKmdhhHAVa9yTIeGC957Ni8UO1/NKHhAlIW7sTGpIXeoCdj2gnuGzYo/lHGqfHJnRjklMaNUk+f0rSZVKSD+3qspyuME1kBrmnMBDc4LGDA5mM1CdZdkfrR6mn9fonfYvjEkZUkAe3eAs4+3HdbtaJluGRpcGHFRAuSmpHwHXRhMnd9dHHrTm4iZAI0YQ4fZWKB5gvIA== X-SONIC-DKIM-SIGN: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1680396493; bh=zzf+0V8eF0lfsqf7kMX9Vb4b2K+mqXz552Um5P7F1/K=; h=X-Sonic-MF:From:To:Subject:Date:From:Subject; b=MMca1IGxElH58tCynzAAFw6+JN47S/A5XvJd1JYr3NvNpsxMcxglHr1fjA9sX8stvEE/TX9YoPVZaaporC52ZRLl5GRoJr5tqed2OtHcU2csavDyOs9VuOX4kXe3tQxXYPP6NUfXgHrRBJow1BqjP5ang3vRnyKqN/Pfm4jZAB7os/g0gioSg1EzqJx5bqiXVJcEF5ZyNk3xQLlhqzQv3ppbHcVJWykUyVNxZjUNQuMLV2yD55ZHiZdkoLBSQBNQ0PMfZyn1smoVKCJfMqDbWMdbfQG3UjNrgxa3sevDaSuBDW/JGzL4BvvhENSNncoM+6TPiPsxXwwd6zgCKUViCA== X-YMail-OSG: bD3fVmcVM1nyORGUryjjJOxVEM.aBJoPfafK0JysL0oyk366cV8IOCwVMlgsWx. sugFoaiUaoIFbdhAkFxRW9WoBtyuV8AE2.xJ35VXt7V81a3nRdO8k0Z6KmDtP5QiozPNn1NjDHR0 PjJzWiwDlVH8S7QfGjktbI4FQuFp2vqDl5109udXe1JW8CBDoyKNK2kMgNNSBZM96wIHYtz15ZcY 2p3VNGPFFIWH1QkQRfqsLUfGaujfzek5tw4TrStGMY8UmepAexrqrQlBpo8Vxr2qA8.s15oR9QRh RA_zVwFjV_NKs4vIrm47AHhNpj6T8flGhzMm4bnGYaA6BcrpV1FnbVNBt62G3QyLgzCP.opare8f 86QJnWULRY2Fxirnmnp5x.lOtmizDWikrkmhVx5B3wjce7MmkzhuH3QYLa9QV8di_ES2bVch0hhH PpWrUymM1yPhuMdJ65Nvg4I9oZUZNMu2ldoq7Z2Gg_wHfxTL7g8IxcaXEISD8Piym2Wml1vzot14 qlCwc5MheIrZ5Qjx1sMqxqoZf4bsvYeB0b4f1C19t3UlIj8_6GDsop2zduIVheVzAZxpCMI897tb mCSEh9u8x6q5hqdshUQdPIwBpWJTxt4H5P.15wrCqGP61NfCkHTSwNipayKba4N0FqsJtOt6ilMf 0KeM43LFn_uOKFXP9AN8_zVA_68V6CuSondNHjqY6ZyNdV6tVwMubAklVb1LqNAQ6BRfc5vHMycT J5aaDsk1CzxtBOjZhrP_Y_YrqjALjIeQUVe_K6DzgFZzlMfbgxQXKzGpoxM14QDSVxMql7LYDzQJ Nn78CyUcG3kum4SAIcZmpKSsW0.40Qy9Dh9Cz8rIjr X-Sonic-MF: X-Sonic-ID: bb252f49-6863-4846-8ccc-ff5face976a6 Original-Received: from sonic.gate.mail.ne1.yahoo.com by sonic310.consmr.mail.ne1.yahoo.com with HTTP; Sun, 2 Apr 2023 00:48:13 +0000 Original-Received: by hermes--production-sg3-6d6fb994f6-5v57h (Yahoo Inc. Hermes SMTP Server) with ESMTPA ID 52dd86707396ddf6c22c8f4b23bf1ad9; Sun, 02 Apr 2023 00:48:07 +0000 (UTC) In-Reply-To: <83zg7rybfo.fsf@gnu.org> (Eli Zaretskii's message of "Sat, 01 Apr 2023 16:33:15 +0300") X-Mailer: WebService/1.1.21284 mail.backend.jedi.jws.acl:role.jedi.acl.token.atz.jws.hermes.yahoo Received-SPF: pass client-ip=66.163.186.206; envelope-from=luangruo@yahoo.com; helo=sonic310-25.consmr.mail.ne1.yahoo.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action 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:305023 Archived-At: Eli Zaretskii writes: >> From: Arsen Arsenovi=C4=87 >> Cc: Po Lu , mattias.engdegard@gmail.com, >> vibhavp@gmail.com, rpluim@gmail.com, emacs-devel@gnu.org >> Date: Sat, 01 Apr 2023 14:59:53 +0200 >>=20 >> Eli Zaretskii writes: >>=20 >> > I'm still unconvinced, and I said already what will have a chance of >> > convincing me: a specific report about a problem this particular code >> > causes on a specific existing platform we support in Emacs 29 and with >> > a specific compiler. >>=20 >> Similar (but not exactly the same) loops as this one have been shown to >> generate incorrect code in this thread. It's not a large leap for it to >> happen to this one, introducing subtle errors for a bit of code that is >> completely unnecessary (as demonstrated by it being optional), >> especially at higher optimization levels, where the compiler could >> easily produce better code than the assumption of a 'mov' would. >>=20 >> Is the following trivial enough for 29? > > You are again trying to push for a change without showing any actual > bug with the existing code. Please humor me, and please show me an > actual bug due to the existing code before suggesting a solution. See > above for the description of the details I'd like to know about such > actual bug. > Sorry, I don't want to risk any errors, and I would like to avoid any > experiments with the release branch. Which is why I'm asking for hard > evidence. It isn't that I don't understand what you and others are > saying, or don't believe you. It's just that we need to see the > problems before we can judge the solutions that must be safe on this > branch. The nature of this bug is that there is no ``hard evidence'' of its presence, until it strikes. Just like writing outside malloc'ed memory, or freeing a pointer twice, or signed integer overflow (which falls apart entirely on the R4000.) This code has a very high risk for errors. Removing it entirely will reduce the risk, since it was only installed late in Emacs 29's development.