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: Sat, 01 Apr 2023 17:17:07 +0800 Message-ID: <87wn2wrmgc.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> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="36665"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Cc: Mattias =?utf-8?Q?Engdeg=C3=A5rd?= , 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 Sat Apr 01 11:18:02 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 1piXN4-0009Jo-G5 for ged-emacs-devel@m.gmane-mx.org; Sat, 01 Apr 2023 11:18:02 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1piXMQ-0006Go-Ug; Sat, 01 Apr 2023 05:17:22 -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 1piXMO-0006GX-Tf for emacs-devel@gnu.org; Sat, 01 Apr 2023 05:17:21 -0400 Original-Received: from sonic311-23.consmr.mail.ne1.yahoo.com ([66.163.188.204]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1piXMM-0006Fl-VQ for emacs-devel@gnu.org; Sat, 01 Apr 2023 05:17:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1680340636; bh=k1oxvGYhSpCAC5IV0iLBeZgufAumTRPcQm+vCTqnRlk=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From:Subject:Reply-To; b=G9hWvj3Q6w5gD7AABMCgMc0IpdTPcIbj+6B9ZviHcW0E+skm/jbZTLJt7W1E+xuyXckOnIRQN7zws9rpRyZw3rH5FZI975F6AH/OkJNFM5u2gVnooyyxbnmqkyrcNx785vmYLXbFIXvRd9hOHBxFRbAB3otFkiQs0xYwv4DZbmLWqBjtAf9cUcc41w5lzILIbr4ecV9usNNINdKy9YNzkpl3oWjneOcIxdCM7StxYkcdg/awV2eUSb/3cW0Fm9V6lOAlWWMp6vvJIR3SmPKmKLqdZ3aYG6ZLEVg9syM/qwENyIuKlSVZRoAE0l8FaCNXUw5DdRzBsogCKJwfznpLHQ== X-SONIC-DKIM-SIGN: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s2048; t=1680340636; bh=H1A9NczA9fF3w00P7C4YRhCxchjcqmAG66VrzyuaZYK=; h=X-Sonic-MF:From:To:Subject:Date:From:Subject; b=sBhpiZB4alUBS3wvcz/FZSi6ovmNFPI/qHZkgfTXXULDcrnTgnwcxGvanofl7VlRDm5AjypnfjY+fOHr4b19rG/bBQWWnHb8dXL9IodWLX62vLds0XZpx9XldyaT5ec//M53uNO25URvqdhujY7legJ+Fz5S59S7XHnXWqBSaOvADSHZM01Odr4r1Y+oLQRAeZ2RBuXKD29syiLZAanxTkEg44HqL9wGzeHJwImgIYzzruy5VA20pZ0KNh7Dkb2bPjpv3j7scMCh3EOx9uzcGThEBwDze6Ww1fhEDDtr1L9SD4kVIBpyxBz6TiA5kKdv7kLlvzXt8o1tsissoBzQog== X-YMail-OSG: ZFP54EEVM1mpwMtlaHU0sOUnENDPrq3lGf7TI.mGwLI7FI22L194ZPZid_VZKIi T0jMom3bExFn7LArAnaxW0At6GHamqPMAqX0P202d5TjIVHORjk2AZhDmmbhWk1b_ORGI5iUF36o lbGY8iqeKSSbX_qMEBuTf44b7b6O4ffnVehDWEemBSMlD27flNSsFAabDxpvZY78HggdJfi86j65 8x8tSd_j9RKFvWZoFsvlKWAmKap7fwYnz_mm7Zp_sYeY9xUQi6Ab5PuCGLtc4WiukANeoWzRDMnO qZJGgmITdjzPnvys3wlul0IPqio4sSUm9O0flZ3qqW6YaTWX3LRT1uI4zp_GKu55d8VT1HVr0dof Dhx1OYTvF2IalDfP7DKJ7lGH1XbGIV.PJ5P6etHW8LPF7qB7BPrt1bUoWv5yGzNrCbOu0Sa7Z1I2 vl8Vr047zIEbF2J9yst8GQOwlitQGk9HfxdX3RqokxQq0vDYRaHPWRwMKwQQR8CgTdP4Yv7cRS_Z nRdVTyPYqtheLYL8.TnyI7JUNs3FwZRUWgeCzIWoD4pzxKGAlI5Jr7YjbVZrYAoBq3IZ.38p5cJp gGL5A_5NTJlV2eIqDsTu_Ub8Wp7A_tHzJG1FYmdUAawd3TPCWlnMzPT3zLw2ZyPH.JaQyP0waSMM xmQSHmR9yi9lI2RQ2MQ4zMIQihD9AF5oc5OfWiI38sdqScQUS5GEdTHa5C0c7yitzlqJ8n0fUMk5 erpSWDOmxIfN0kt9cSGqU6X2KTIlb1emmfZ5_DQsRHGpawGB2L735.e5IWAf7Le_9CMKNSGHSBQv 1nFSJJ2hXU5hdSSKoR1rvRkAo.wL_Ncl48SbTkREAk X-Sonic-MF: X-Sonic-ID: 9bff2f79-74d8-4537-9069-6b9c3ee71041 Original-Received: from sonic.gate.mail.ne1.yahoo.com by sonic311.consmr.mail.ne1.yahoo.com with HTTP; Sat, 1 Apr 2023 09:17:16 +0000 Original-Received: by hermes--production-sg3-6d6fb994f6-7thcs (Yahoo Inc. Hermes SMTP Server) with ESMTPA ID 22079eddcb79f07a280ea7418d5ed18b; Sat, 01 Apr 2023 09:17:13 +0000 (UTC) In-Reply-To: <83lejcypyw.fsf@gnu.org> (Eli Zaretskii's message of "Sat, 01 Apr 2023 11:19:19 +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=66.163.188.204; envelope-from=luangruo@yahoo.com; helo=sonic311-23.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, 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:304984 Archived-At: Eli Zaretskii writes: > IOW, "best engineering practices" are for master; on the release > branch, using existing code proven by time takes precedence, because > our ability to predict consequences is limited. This problem is not about engineering practices, but basic program correctness. Look at the GCC bug tracker: every release, a program that relies on this undefined behavior becomes subtly broken, a bug is filed against GCC, and is closed by the GCC developers, stating that this behavior is unsupported. Emacs 29 has been in development for less than three years... not nearly long enough to be sure no subtle miscompilations have taken (or will take) place. If that's ``proven by time'', then so is this: null_terminate (buffer, size) char *buffer; { buffer[size] = '\0'; } It might work for a few months, or a year, then suddenly break with a new compiler release, or perhaps a change to malloc, or something else.