From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.devel Subject: Re: Removing some workarounds for big integers Date: Tue, 4 Aug 2020 23:11:31 -0700 Organization: UCLA Computer Science Department Message-ID: <2cad6bf3-e0ef-eada-41d8-00d13ea814e4@cs.ucla.edu> References: <86d0uck5o0.fsf@gmail.com> <15786884-92c4-efb0-58d3-a6ec6726a0fe@cs.ucla.edu> <86lg02our6.fsf@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="36327"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 Cc: Andy Moreton , Emacs developers To: Philipp Stephani Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Wed Aug 05 08:12:11 2020 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 1k3Cep-0009LL-D8 for ged-emacs-devel@m.gmane-mx.org; Wed, 05 Aug 2020 08:12:11 +0200 Original-Received: from localhost ([::1]:32912 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1k3Ceo-0006mE-E6 for ged-emacs-devel@m.gmane-mx.org; Wed, 05 Aug 2020 02:12:10 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:49614) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1k3CeJ-0006MM-70 for emacs-devel@gnu.org; Wed, 05 Aug 2020 02:11:39 -0400 Original-Received: from zimbra.cs.ucla.edu ([131.179.128.68]:52246) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1k3CeH-00070M-4O for emacs-devel@gnu.org; Wed, 05 Aug 2020 02:11:38 -0400 Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id D6F7D1600C4; Tue, 4 Aug 2020 23:11:32 -0700 (PDT) Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id aPR3G6y-ldv4; Tue, 4 Aug 2020 23:11:32 -0700 (PDT) Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 14F041600D1; Tue, 4 Aug 2020 23:11:32 -0700 (PDT) X-Virus-Scanned: amavisd-new at zimbra.cs.ucla.edu Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id 5NQekKHR0VRK; Tue, 4 Aug 2020 23:11:31 -0700 (PDT) Original-Received: from [192.168.1.9] (cpe-75-82-69-226.socal.res.rr.com [75.82.69.226]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id B506F1600C4; Tue, 4 Aug 2020 23:11:31 -0700 (PDT) Autocrypt: addr=eggert@cs.ucla.edu; prefer-encrypt=mutual; keydata= LS0tLS1CRUdJTiBQR1AgUFVCTElDIEtFWSBCTE9DSy0tLS0tCgptUUlOQkV5QWNtUUJFQURB QXlIMnhvVHU3cHBHNUQzYThGTVpFb243NGRDdmM0K3ExWEEySjJ0QnkycHdhVHFmCmhweHhk R0E5Smo1MFVKM1BENGJTVUVnTjh0TFowc2FuNDdsNVhUQUZMaTI0NTZjaVNsNW04c0thSGxH ZHQ5WG0KQUF0bVhxZVpWSVlYL1VGUzk2ZkR6ZjR4aEVtbS95N0xiWUVQUWRVZHh1NDd4QTVL aFRZcDVibHRGM1dZRHoxWQpnZDdneDA3QXV3cDdpdzdlTnZub0RUQWxLQWw4S1lEWnpiRE5D UUdFYnBZM2VmWkl2UGRlSStGV1FONFcra2doCnkrUDZhdTZQcklJaFlyYWV1YTdYRGRiMkxT MWVuM1NzbUUzUWpxZlJxSS9BMnVlOEpNd3N2WGUvV0szOEV6czYKeDc0aVRhcUkzQUZINmls QWhEcXBNbmQvbXNTRVNORnQ3NkRpTzFaS1FNcjlhbVZQa25qZlBtSklTcWRoZ0IxRApsRWR3 MzRzUk9mNlY4bVp3MHhmcVQ2UEtFNDZMY0ZlZnpzMGtiZzRHT1JmOHZqRzJTZjF0azVlVThN Qml5Ti9iClowM2JLTmpOWU1wT0REUVF3dVA4NGtZTGtYMndCeHhNQWhCeHdiRFZadWR6eERa SjFDMlZYdWpDT0pWeHEya2wKakJNOUVUWXVVR3FkNzVBVzJMWHJMdzYrTXVJc0hGQVlBZ1Jy NytLY3dEZ0JBZndoU In-Reply-To: Content-Language: en-US Received-SPF: pass client-ip=131.179.128.68; envelope-from=eggert@cs.ucla.edu; helo=zimbra.cs.ucla.edu X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/05 02:11:33 X-ACL-Warn: Detected OS = Linux 3.1-3.10 X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.23 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" Xref: news.gmane.io gmane.emacs.devel:253457 Archived-At: On 8/1/20 1:09 PM, Philipp Stephani wrote: > Am Mo., 22. Apr. 2019 um 20:45 Uhr schrieb Paul Eggert : >> >> On 4/22/19 9:59 AM, Philipp Stephani wrote: >>> >>>> +#define INTEGER_TO_INT(num, type) \ >>>> + (TYPE_SIGNED (type) \ >>>> + ? ranged_integer_to_int ((num), TYPE_MINIMUM (type), TYPE_MAXIMUM (type)) \ >>>> + : ranged_integer_to_uint ((num), TYPE_MINIMUM (type))) >>>> ^^^^^^^^^^^^ >>>> This should be TYPE_MAXIMUM. >>> >>> Thanks, fixed >>> >> More important, INTEGER_TO_INT's type conversion messes up and can cause >> a signal on picky platforms. > > How so? The type conversion is messed up because on conventional platforms INTEGER_TO_INT returns a value of uintmax_t, which means that an expression like 'INTEGER_TO_INT (n, t) < 0' will always be false, even if N is negative and T is a signed type. The "picky platform" is one where conversion from unsigned to signed signals when the value is out of range for the signed type; this behavior is allowed by POSIX and the C standard and I imagine some debugging implementations might check for it. On these implementations, To work around this problem, the macro could have another argument, being the lvalue destination; that would avoid these problems. However, it'd be more awkward to use. At some point it's easier to avoid the macro and use the underlying functions.