From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 123337 invoked by alias); 27 Feb 2018 14:21:44 -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 122990 invoked by uid 89); 27 Feb 2018 14:21:42 -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,RCVD_IN_DNSWL_NONE,SPF_HELO_PASS,SPF_PASS autolearn=ham version=3.3.2 spammy= X-Spam-User: qpsmtpd, 2 recipients X-HELO: EUR01-VE1-obe.outbound.protection.outlook.com Received: from mail-ve1eur01on0085.outbound.protection.outlook.com (HELO EUR01-VE1-obe.outbound.protection.outlook.com) (104.47.1.85) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Tue, 27 Feb 2018 14:21:40 +0000 Received: from DB6PR0801MB2053.eurprd08.prod.outlook.com (10.168.86.22) by DB6PR0801MB1910.eurprd08.prod.outlook.com (10.168.85.20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P256) id 15.20.527.15; Tue, 27 Feb 2018 14:21:37 +0000 Received: from DB6PR0801MB2053.eurprd08.prod.outlook.com ([fe80::ac2f:91c:c9da:ec56]) by DB6PR0801MB2053.eurprd08.prod.outlook.com ([fe80::ac2f:91c:c9da:ec56%17]) with mapi id 15.20.0506.028; Tue, 27 Feb 2018 14:21:37 +0000 From: Wilco Dijkstra To: Richard Biener , James Greenhalgh CC: GCC Patches , nd , "sje@gcc.gnu.org" Subject: Re: [PATCH][AArch64] PR84114: Avoid reassociating FMA Date: Tue, 27 Feb 2018 14:21:00 -0000 Message-ID: References: <20180226222545.GA3086@arm.com>, In-Reply-To: authentication-results: spf=none (sender IP is ) smtp.mailfrom=Wilco.Dijkstra@arm.com; x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;DB6PR0801MB1910;7:Q9GRpqZ4HpK+IGQNQAXCJFSSGvhuTTjjt9TYdAOi1/mPjAOgejAPs4WX+v8p1ZQr9YktPAfYCVnHtJzqqCyKr3fz/AluRSupkkpVrynsTO8PO5+M0safEd7l2M8u/qsBuShLyPHmXcZHecmKVjyyghSlmPhlM/ry3yYSXq3BfZbFVL40bu01JXBN7sD7i06YKScMZAQfOUNKanAaLQLX/hPPg2T8kVkJFZEe0RQf+mREoDlTnHINE3cjfXxuspsC x-ms-exchange-antispam-srfa-diagnostics: SSOS;SSOR; x-ms-office365-filtering-ht: Tenant x-ms-office365-filtering-correlation-id: 8784df59-32ac-439a-f178-08d57ded697d x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095)(4652020)(4534165)(4627221)(201703031133081)(201702281549075)(48565401081)(5600026)(4604075)(3008032)(2017052603307)(7153060)(7193020);SRVR:DB6PR0801MB1910; x-ms-traffictypediagnostic: DB6PR0801MB1910: nodisclaimer: True x-microsoft-antispam-prvs: x-exchange-antispam-report-test: UriScan:(85827821059158); x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(8211001083)(6040501)(2401047)(5005006)(8121501046)(3231220)(944501198)(52105095)(10201501046)(3002001)(93006095)(93001095)(6055026)(6041288)(20161123564045)(201703131423095)(201702281528075)(20161123555045)(201703061421075)(201703061406153)(20161123562045)(20161123558120)(20161123560045)(6072148)(201708071742011);SRVR:DB6PR0801MB1910;BCL:0;PCL:0;RULEID:;SRVR:DB6PR0801MB1910; x-forefront-prvs: 05961EBAFC x-forefront-antispam-report: SFV:NSPM;SFS:(10009020)(346002)(39380400002)(39860400002)(396003)(376002)(366004)(189003)(199004)(39060400002)(68736007)(53936002)(2906002)(14454004)(478600001)(97736004)(72206003)(9686003)(6246003)(3280700002)(54906003)(6116002)(2900100001)(3846002)(305945005)(110136005)(33656002)(81156014)(316002)(81166006)(8936002)(5660300001)(8676002)(7736002)(74316002)(2950100002)(76176011)(3660700001)(186003)(6636002)(105586002)(102836004)(7696005)(66066001)(25786009)(106356001)(4326008)(6506007)(86362001)(55016002)(26005)(99286004)(6436002)(229853002)(5250100002);DIR:OUT;SFP:1101;SCL:1;SRVR:DB6PR0801MB1910;H:DB6PR0801MB2053.eurprd08.prod.outlook.com;FPR:;SPF:None;PTR:InfoNoRecords;MX:1;A:1;LANG:en; received-spf: None (protection.outlook.com: arm.com does not designate permitted sender hosts) x-microsoft-antispam-message-info: IEkxR+v7ZWpH7tF9jqcrFgE5yFYs3WwzWkwCDuY3x1zRFa9FKN4WwE0Ma45N1AvOnwhoxxCss09hzLj3MBeCSYRwHq/OjsQnnNJPD7PsP3B+yrC1lnfJkaLTxaqbOhjCNPKTmrHV5YE54nUPxh8EW7LaXFQq7Xk88lWJwRUcKBQ= spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-Network-Message-Id: 8784df59-32ac-439a-f178-08d57ded697d X-MS-Exchange-CrossTenant-originalarrivaltime: 27 Feb 2018 14:21:37.2594 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: f34e5979-57d9-4aaa-ad4d-b122a662184d X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB6PR0801MB1910 X-SW-Source: 2018-02/txt/msg01501.txt.bz2 Richard Biener > It happens that on some targets doing two FMAs in parallel and one > non-FMA operation merging them is faster than chaining three FMAs... Like I mentioned in the PR, long chains should be broken, but for that we n= eed a new parameter to state how long a chain may be before it is split. Th= e issue today is that it splits even very short chains, removing beneficial= FMAs. > But yes, somewhere I suggested that FMA detection should/could be > integrated with reassociation. Absolutely. Wilco