From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 108743 invoked by alias); 21 Jun 2018 23:05:17 -0000 Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org Received: (qmail 108734 invoked by uid 89); 21 Jun 2018 23:05:16 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.7 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_NONE,SPF_HELO_PASS,SPF_PASS autolearn=ham version=3.3.2 spammy=ellcey, Ellcey, HContent-Transfer-Encoding:8bit X-HELO: NAM03-CO1-obe.outbound.protection.outlook.com Received: from mail-co1nam03on0058.outbound.protection.outlook.com (HELO NAM03-CO1-obe.outbound.protection.outlook.com) (104.47.40.58) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 21 Jun 2018 23:05:15 +0000 Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=Steve.Ellcey@cavium.com; Received: from sellcey-dt.caveonetworks.com (50.233.148.156) by DM6PR07MB5033.namprd07.prod.outlook.com (2603:10b6:5:25::30) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.884.20; Thu, 21 Jun 2018 23:05:12 +0000 Message-ID: <1529622309.19200.12.camel@cavium.com> Subject: Re: How to get GCC on par with ICC? From: Steve Ellcey Reply-To: sellcey@cavium.com To: NightStrike , joel@rtems.org Cc: Paul Menzel , "gcc@gcc.gnu.org" Date: Fri, 22 Jun 2018 00:48:00 -0000 In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 8bit X-ClientProxiedBy: CO2PR05CA0091.namprd05.prod.outlook.com (2603:10b6:104:1::17) To DM6PR07MB5033.namprd07.prod.outlook.com (2603:10b6:5:25::30) X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 56debbf2-e399-47d8-25f1-08d5d7cb71fc X-MS-TrafficTypeDiagnostic: DM6PR07MB5033: X-Exchange-Antispam-Report-Test: UriScan:(20558992708506); X-MS-Exchange-SenderADCheck: 1 X-Forefront-PRVS: 07106EF9B9 Received-SPF: None (protection.outlook.com: cavium.com does not designate permitted sender hosts) SpamDiagnosticOutput: 1:99 SpamDiagnosticMetadata: NSPM X-OriginatorOrg: cavium.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 21 Jun 2018 23:05:12.9257 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 56debbf2-e399-47d8-25f1-08d5d7cb71fc X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 711e4ccf-2e9b-4bcf-a551-4094005b6194 X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR07MB5033 X-SW-Source: 2018-06/txt/msg00239.txt.bz2 On Wed, 2018-06-20 at 17:11 -0400, NightStrike wrote: >  > If I could perhaps jump in here for a moment...  Just today I hit upon > a series of small (in lines of code) loops that gcc can't vectorize, > and intel vectorizes like a madman.  They all involve a lot of heavy > use of std::vector>.  Comparisons were with gcc > 8.1, intel 2018.u1, an AMD Opteron 6386 SE, with the program running > as sched_FIFO, mlockall, affinity set to its own core, and all > interrupts vectored off that core.  So, as close to not-noisy as > possible. There are a quite a number of bugzilla reports with examples where GCC does not vectorize a loop.  I wonder if this example is related to PR 61247. Steve Ellcey