From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by sourceware.org (Postfix) with ESMTPS id 2CCF83A6A03E for ; Fri, 6 Nov 2020 23:16:37 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 2CCF83A6A03E Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 0A6MXXej124999 for ; Fri, 6 Nov 2020 18:16:36 -0500 Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 34nd8muvyw-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 06 Nov 2020 18:16:36 -0500 Received: from m0098396.ppops.net (m0098396.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 0A6MXluT125871 for ; Fri, 6 Nov 2020 18:16:36 -0500 Received: from ppma02dal.us.ibm.com (a.bd.3ea9.ip4.static.sl-reverse.com [169.62.189.10]) by mx0a-001b2d01.pphosted.com with ESMTP id 34nd8muvyq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 06 Nov 2020 18:16:35 -0500 Received: from pps.filterd (ppma02dal.us.ibm.com [127.0.0.1]) by ppma02dal.us.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 0A6NBb05016786; Fri, 6 Nov 2020 23:16:35 GMT Received: from b01cxnp23032.gho.pok.ibm.com (b01cxnp23032.gho.pok.ibm.com [9.57.198.27]) by ppma02dal.us.ibm.com with ESMTP id 34h023aen8-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 06 Nov 2020 23:16:35 +0000 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp23032.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 0A6NGY7m6816342 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 6 Nov 2020 23:16:34 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6BBF3B205F; Fri, 6 Nov 2020 23:16:34 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C097DB2065; Fri, 6 Nov 2020 23:16:33 +0000 (GMT) Received: from [9.211.80.128] (unknown [9.211.80.128]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Fri, 6 Nov 2020 23:16:33 +0000 (GMT) Subject: Re: Question about alignment of struct _Unwind_Exception To: Florian Weimer Cc: Matheus Castanho , GNU C Library , Tulio Magno Quites Machado Filho References: <87tuu42a2v.fsf@oldenburg2.str.redhat.com> From: Peter Bergner Message-ID: <7fed9c8e-1682-2f7f-4c95-5140e5f60ebe@linux.ibm.com> Date: Fri, 6 Nov 2020 17:16:32 -0600 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 MIME-Version: 1.0 In-Reply-To: <87tuu42a2v.fsf@oldenburg2.str.redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.312, 18.0.737 definitions=2020-11-06_06:2020-11-05, 2020-11-06 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 phishscore=0 suspectscore=0 bulkscore=0 clxscore=1015 impostorscore=0 malwarescore=0 mlxlogscore=999 adultscore=0 spamscore=0 priorityscore=1501 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011060153 X-Spam-Status: No, score=-3.6 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_EF, NICE_REPLY_A, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 06 Nov 2020 23:16:38 -0000 On 11/4/20 1:31 PM, Florian Weimer wrote: >> If I can align the MMA types a different way, then the default >> alignment will go back to 128 bits, which should "fix" the issue >> you are seeing. > > x86-64 does this as well if 512-bit vector types exist. We need to fix > this in glibc. (Maybe things work out due to the struct pthread layout > on x86-64, but it's still a bug.) I agree GLIBC has a problem here. That said, GCC should not have changed the default alignment either. I just committed a fix to GCC trunk that reverts the change to BIGGEST_ALIGNMENT and fixes the alignment of the MMA types a different way. I will backport the fix to thje GCC 10 release branch after it's baked a couple of days on trunk. Peter