From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vs1-xe2e.google.com (mail-vs1-xe2e.google.com [IPv6:2607:f8b0:4864:20::e2e]) by sourceware.org (Postfix) with ESMTPS id 549363857C6A; Wed, 6 Oct 2021 15:42:59 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 549363857C6A Received: by mail-vs1-xe2e.google.com with SMTP id 188so3480950vsv.0; Wed, 06 Oct 2021 08:42:59 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=5s8cWT+X5+Tq776zpLG5TzhwXygsiKjZFxZYnq9TPT0=; b=SlFHS9EqbZFzywB5iz5otbb6h5dN379ivaKFaiw/EUMyYNjd9GEhvyt4/I9UTn4HEn CCoHU2LIGtM2nB3W3GB3PnghRStTL7GF+3uWAjB29viOAbC0V0mPdH/8wNv5wMs2i/a9 w3fMoW/1je3TmAGc34TgWRMm34JTNAxwP49Kqe1hjYiV89DJLDqnfRiaefs5j5orrz0Y /E/UT4j1Wif8770OnxHU9ipaX8dNdVcOF8XX0dP9lqglUvydHyoYLlvQhaHwPaqVyDD2 B5ldeY+iOMlE9p9Y5S7cX6b7ZgA0YQ7slULLmNF628KYMhy+qQ6eBmYhaAqGxoPLDQm9 9Y8A== X-Gm-Message-State: AOAM531Cv0vp4LJ0MoXl1j5RqAbFFlWLMX/B4g92laXqeTugWehxFT8M FqNgGlEUYSZaybDulSoK74OSQNjAVKwfeJekdsA= X-Google-Smtp-Source: ABdhPJwX3wZZG6rumLRss1Qc52/0Tyrm0ZKrf8TaX7uQHOhX9W7MKUeM+6HARQI2xXLipAynTmAxoVRfbSwJo/AP5YE= X-Received: by 2002:a05:6102:389:: with SMTP id m9mr23010863vsq.34.1633534978863; Wed, 06 Oct 2021 08:42:58 -0700 (PDT) MIME-Version: 1.0 References: <20211004100754.GL304296@tucnak> <20211004141410.GP304296@tucnak> <6d845542-536e-1a0f-70e9-d05eea98aae7@netcologne.de> <20211005215450.GC10333@gate.crashing.org> <90df1250-9b3f-4a55-bc67-e3e05e54f7ef@netcologne.de> <20211006151744.GE10333@gate.crashing.org> In-Reply-To: <20211006151744.GE10333@gate.crashing.org> From: David Edelsohn Date: Wed, 6 Oct 2021 11:42:17 -0400 Message-ID: Subject: Re: libgfortran.so SONAME and powerpc64le-linux ABI changes To: Segher Boessenkool Cc: Thomas Koenig , Jakub Jelinek , GCC Development , Michael Meissner , Fortran List , Tobias Burnus , Jonathan Wakely Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-1.5 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: gcc@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 06 Oct 2021 15:43:00 -0000 On Wed, Oct 6, 2021 at 11:19 AM Segher Boessenkool wrote: > > On Wed, Oct 06, 2021 at 08:59:53AM +0200, Thomas Koenig wrote: > > On 05.10.21 23:54, Segher Boessenkool wrote: > > >>There is also the issue of binary data. If some user has written > > >>out data in double double and wants to read it in as IEEE quad, > > >>the results are going to be garbage. Another option for CONVERT > > >>might be the solution to that, or, as you wrote, having a > > >>REAL(KIND=15). It should be inaccessible via SELECTED_REAL_KIND, > > >>though. > > > > > >That means flipping the default on all PowerPC to no longer be double- > > >double. This means that you should have IEEE QP work everywhere, or the > > >people who do need more than double precision will have no recourse. > > > > I think we can exclude big-endian POWER from this - they do not have > > IEEE QP support, correct? So, exclude that from the SONAME change. > > Not correct, no. IEEE QP works fine in either endianness. This needs to be described with more granularity. IEEE QP instructions work with either endianness. IEEE QP is enabled and supported for PPC64 LE Linux on Power. The transition is under discussion. PPC64 BE Linux on Power does not define IEEE QP. The ABI could be updated and IEEE QP could be enabled, but PPC64 BE is not planning future releases from Linux distros. IEEE QP for PPC64 FreeBSD on Power is an open question for the FreeBSD community. AIX on Power will continue to use double-double long double format. GCC, LLVM, IBM Open XL and IBM XL compilers will continue to implement and support the double-double format on AIX. Thanks, David P.S. This is my personal understanding and not an official statement of support or product guidance from IBM.