From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS22989 209.51.188.0/24 X-Spam-Status: No, score=-4.2 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, RCVD_IN_DNSWL_MED,RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id 03E101F8C6 for ; Mon, 30 Aug 2021 01:50:26 +0000 (UTC) Received: from localhost ([::1]:52502 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mKWRM-00040U-Pl for normalperson@yhbt.net; Sun, 29 Aug 2021 21:50:24 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:38766) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mKWR7-0003yW-1I for bug-gnulib@gnu.org; Sun, 29 Aug 2021 21:50:09 -0400 Received: from zimbra.cs.ucla.edu ([131.179.128.68]:40614) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mKWR4-00021j-TI for bug-gnulib@gnu.org; Sun, 29 Aug 2021 21:50:08 -0400 Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 627811600BB; Sun, 29 Aug 2021 18:50:04 -0700 (PDT) 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 nivapL0l6A6W; Sun, 29 Aug 2021 18:49:59 -0700 (PDT) Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id B45A71600FC; Sun, 29 Aug 2021 18:49:59 -0700 (PDT) X-Virus-Scanned: amavisd-new at zimbra.cs.ucla.edu 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 yO3uXuKkamZ5; Sun, 29 Aug 2021 18:49:59 -0700 (PDT) Received: from [192.168.1.9] (cpe-172-91-119-151.socal.res.rr.com [172.91.119.151]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id 919361600BB; Sun, 29 Aug 2021 18:49:59 -0700 (PDT) To: Bruno Haible References: <4660767.TKLx3GfHUD@omega> From: Paul Eggert Organization: UCLA Computer Science Department Subject: Re: timespec test failure on Linux/s390x Message-ID: <6f22234c-387b-faea-02dc-bee4a01a6528@cs.ucla.edu> Date: Sun, 29 Aug 2021 18:49:59 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <4660767.TKLx3GfHUD@omega> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=131.179.128.68; envelope-from=eggert@cs.ucla.edu; helo=zimbra.cs.ucla.edu X-Spam_score_int: -47 X-Spam_score: -4.8 X-Spam_bar: ---- X-Spam_report: (-4.8 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-0.58, 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: bug-gnulib@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Gnulib discussion list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: bug-gnulib@gnu.org Errors-To: bug-gnulib-bounces+normalperson=yhbt.net@gnu.org Sender: "bug-gnulib" On 8/29/21 6:15 PM, Bruno Haible wrote: > ../../gltests/test-timespec.c:152: assertion 'eq (timespec_add (a, sumb= c), timespec_add (sum, c))' failed > Aborted (core dumped) >=20 > In test-timespec.c:152 the local variables are: > ... > ntests =3D 26 > computed_hz =3D 1000000000 > i =3D 1 > a =3D {tv_sec =3D -9223372036854775808, tv_nsec =3D 0} > roundtrip =3D {tv_sec =3D -9223372036854775808, tv_nsec =3D 0} > prevroundtrip =3D {tv_sec =3D -9223372036854775808, tv_nsec =3D 0} > j =3D 1 > b =3D {tv_sec =3D -9223372036854775808, tv_nsec =3D 0} > sum =3D {tv_sec =3D 0, tv_nsec =3D 0} That value of 'sum' is wrong; it should be most-negative value {tv_sec =3D= =20 -9223372036854775808, tv_nsec =3D 0} because A and B are both that value,= =20 and 'sum =3D timespec_add (a, b)' is supposed to be saturated addition. My guess is that timespec-add.c's line 49 'INT_ADD_WRAPV (rs, bs, &rs)'=20 is not correctly returning true when RS and BS are both the=20 most-negative value. Since you're using GCC, line 49 should be=20 equivalent to '__builtin_add_overflow (rs, bs, &rs)' (though you should=20 check this), and that suggests a GCC bug. (Yes, I know, everybody at=20 first blames the compiler. :-) Which version of GCC are you using?=20 says that=20 __builtin_add_overflow does not work in GCC 6.5 on s390x, and that the=20 bug is fixed in GCC 7. Could this be the problem? > sumbc =3D {tv_sec =3D -9223372036854775807, tv_nsec =3D 0} > timespec_add (a, sumbc) =3D {tv_sec =3D -9223372036854775808, tv_nsec =3D= 0} ...> * Questions: > Is timespec_add (a, sumbc) wrong? No, it's right. > Or does this particular triple (a, b, c) need to be exluded from the te= sts? I suspect the bug is in the earlier call to timespec_add, as mentioned=20 above.