From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 109456 invoked by alias); 6 Jun 2018 16:22:52 -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 109447 invoked by uid 89); 6 Jun 2018 16:22:51 -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,HTML_MESSAGE,RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.2 spammy=gcc.gnu.org@molgen.mpg.de, gccgnuorgmolgenmpgde, surfaces, 10.1.1.679 X-HELO: mail-wm0-f46.google.com Received: from mail-wm0-f46.google.com (HELO mail-wm0-f46.google.com) (74.125.82.46) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 06 Jun 2018 16:22:49 +0000 Received: by mail-wm0-f46.google.com with SMTP id r15-v6so12614884wmc.1 for ; Wed, 06 Jun 2018 09:22:48 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=fVcTUaFevIk7KGQFkmAkz4LjpimkXP3eO1nM6Gg2ZLE=; b=dSf8Btayc7LO2GnIY84QM48HUH8XhtxpHZuPvkIN2ZecH3JkNdbzd1tImmXcr00nPD Jd/rzFdRFUU1ir8ml7LYPelChlxKfti1t4h1vW9mhxHT/aM5UisD2qexXSglDJnvwh53 kTuuEdc1VqCeu4V4ixpzp0M5DIGTjND8ACBKAf4r9+zFwmLXet4OLW7IYzdc87lseXNF Y6hp1j6gknwx4VLGmVJrPr4Th9cgpGl8YACN00mv/V3xM/DZD/a/AFvfGIJaE6RePgDi CqLG5aVJcVgk6bOozU5XX0z12HCyGS2Nt7IQHLcAx6/C2xz6+Sr6V7UIMlOcZVJgUK5g IIQQ== X-Gm-Message-State: APt69E3GRsAYhFmGIzRHQOaYCjHTC6KgJZPlqIaR5BcnVt16g4KA+60J 7y46UY77DW3Yd5SA7Cky1pGKCg9ZSPYGon1TLXmiqg== X-Google-Smtp-Source: ADUXVKIjixWyoj6cTgdbL3g91j6BqjKKhV2d0zYHXHsL1QTawbIIFmYseaqi1KjNCUorevmLR0YvM04z+96ULfmHQcM= X-Received: by 2002:a1c:355:: with SMTP id 82-v6mr2067116wmd.96.1528302167174; Wed, 06 Jun 2018 09:22:47 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:a1c:1453:0:0:0:0:0 with HTTP; Wed, 6 Jun 2018 09:22:46 -0700 (PDT) In-Reply-To: <01126195-f718-7dd0-063b-6997e5b82559@molgen.mpg.de> References: <01126195-f718-7dd0-063b-6997e5b82559@molgen.mpg.de> From: Dmitry Mikushin Date: Wed, 06 Jun 2018 18:31:00 -0000 Message-ID: Subject: Re: How to get GCC on par with ICC? To: Paul Menzel Cc: GCC Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-IsSubscribed: yes X-SW-Source: 2018-06/txt/msg00082.txt.bz2 Dear Paul, The opinion you've mentioned is common in scientific community. However, in more detail it often surfaces that the used set of GCC compiler options simply does not correspond to that "fast" version of Intel. For instance, when you do "-O3" for Intel it actually corresponds to (at least) "-O3 -ffast-math -march=3Dnative" of GCC. Omitting "-ffast-math" obviously introduces significant performance gap. Kind regards, - Dmitry Mikushin | Applied Parallel Computing LLC | https://parallel-computing.pro 2018-06-06 18:51 GMT+03:00 Paul Menzel : > Dear GCC folks, > > > Some scientists in our organization still want to use the Intel compiler, > as they say, it produces faster code, which is then executed on clusters. > Some resources on the Web [1][2] confirm this. (I am aware, that it=E2=80= =99s > heavily dependent on the actual program.) > > My question is, is it realistic, that GCC could catch up and that the > scientists will start to use it over Intel=E2=80=99s compiler? Or will In= tel > developers always have the lead, because they have secret documentation a= nd > direct contact with the processor designers? > > If it is realistic, how can we get there? Would first the program be > written, and then the compiler be optimized for that? Or are just more GCC > developers needed? > > > Kind regards, > > Paul > > > [1]: https://colfaxresearch.com/compiler-comparison/ > [2]: http://citeseerx.ist.psu.edu/viewdoc/download?doi=3D10.1.1.679 > .1280&rep=3Drep1&type=3Dpdf > >