From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 58925 invoked by alias); 2 Aug 2017 20:16:21 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 58911 invoked by uid 89); 2 Aug 2017 20:16:20 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD,SPF_PASS,UNPARSEABLE_RELAY autolearn=ham version=3.3.2 spammy= X-HELO: userp1040.oracle.com Received: from userp1040.oracle.com (HELO userp1040.oracle.com) (156.151.31.81) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 02 Aug 2017 20:16:20 +0000 Received: from aserv0021.oracle.com (aserv0021.oracle.com [141.146.126.233]) by userp1040.oracle.com (Sentrion-MTA-4.3.2/Sentrion-MTA-4.3.2) with ESMTP id v72KGH3e026941 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Wed, 2 Aug 2017 20:16:18 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserv0021.oracle.com (8.14.4/8.14.4) with ESMTP id v72KGHLi029474 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Wed, 2 Aug 2017 20:16:17 GMT Received: from abhmp0006.oracle.com (abhmp0006.oracle.com [141.146.116.12]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id v72KGH9q007902 for ; Wed, 2 Aug 2017 20:16:17 GMT Received: from dhcp-adc-twvpn-3-vpnpool-10-154-97-215.vpn.oracle.com (/10.154.97.215) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 02 Aug 2017 13:16:16 -0700 From: Qing Zhao Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\)) Subject: Re: [PATCH 1/1] sparc: support for -mmisalign in the SPARC M8 Date: Wed, 02 Aug 2017 20:16:00 -0000 References: <1501687671-143345-1-git-send-email-qing.zhao@oracle.com> <20170802.094255.903257310121261526.davem@davemloft.net> To: gcc-patches@gcc.gnu.org In-Reply-To: <20170802.094255.903257310121261526.davem@davemloft.net> Message-Id: X-IsSubscribed: yes X-SW-Source: 2017-08/txt/msg00237.txt.bz2 Hi, David, thanks a lot for your comment. see my reply below > STRICT_ALIGNMENT has a lot of implications. from the definition of STRICT_ALIGNMENT: /* Set this nonzero if move instructions will actually fail to work when given unaligned data. */ #define STRICT_ALIGNMENT 1 for MISALIGN_TARGET, it=E2=80=99s clear that move instructions will NOT fa= il to work when given unaligned data. so, it=E2=80=99s reasonable to set STRICT_ALIGNMENT to 0 for MISALIGN_TARGE= T. >=20 > I think just because we happen to have misaligned loads and stores > available doesn't mean we want all of the side effects associated > with STRICT_ALIGNMENT being true. so, could you please specify what kind of side effects will have when =3D set STRICT_ALIGNMENT to true on TARGET_MISALIGN?=3D20 thanks a lot. Qing