From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 13375 invoked by alias); 1 Mar 2018 22:04:07 -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 13349 invoked by uid 89); 1 Mar 2018 22:04:07 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.6 required=5.0 tests=AWL,BAYES_00,FREEMAIL_FROM,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 spammy= X-Spam-User: qpsmtpd, 2 recipients X-HELO: mail-it0-f53.google.com Received: from mail-it0-f53.google.com (HELO mail-it0-f53.google.com) (209.85.214.53) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 01 Mar 2018 22:04:05 +0000 Received: by mail-it0-f53.google.com with SMTP id w63so9399280ita.3; Thu, 01 Mar 2018 14:04:05 -0800 (PST) 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=Tp6O6uKliLKvIJmsKKCF/lsDw5Qlsiqu6vgqBX3G1zA=; b=QyfaiwcK+ukEU3uGj3u4XtR/6kXDzS0hH7ezUN32f7hIyMv5YXhNWhdAzX7d7OVvzJ G8+mNWtJVrbaRfUq4Mx8kiRuRrXVFnoVBQ1nlimQEbm/gx3Kn0osHmKcIj/2+T1TQqy0 r/60cttW83zcsNlu+T7kGM1JZ/EFygCsmMcbCoO/hMZjBpw/wMUaquyzadJ/5RfXqXEh FdQSKeZq70Mh6ncZqbboHvH4TB1Jh6A2HqMujXBxdRsb+J+rF5FClknxPMWXhuoS91zm Csj7D1rLGVQpQkEobX3EHcyK8WnhOgI2WxzDVmhcs4fDGTkIoTOipkXmnagXucN88y67 c0pQ== X-Gm-Message-State: APf1xPBdg5oXGJOQQvpdp5Ls4Li8fkPgpBot27N2Aak+QBYl19I+aHef f6AJnT3pIt4EjaCENHgUnG58poH3x7ZmRRY8Pemzikl9 X-Google-Smtp-Source: AG47ELs/6xgE8fFOmRvyJplA4WMW1XEKhtejzMXThLAAFEtl8TFe2AHk14EVB34RBavR1n8mOLBDMmPyn5brHHgzRCI= X-Received: by 10.36.98.21 with SMTP id d21mr4726030itc.1.1519941843897; Thu, 01 Mar 2018 14:04:03 -0800 (PST) MIME-Version: 1.0 Received: by 10.107.50.83 with HTTP; Thu, 1 Mar 2018 14:04:03 -0800 (PST) In-Reply-To: References: <20180301184719.16691-1-tuliom@linux.vnet.ibm.com> From: Jonathan Wakely Date: Thu, 01 Mar 2018 22:04:00 -0000 Message-ID: Subject: Re: [PATCH] PR libstdc++/84654 Do not use __float128 if it is disabled by the compiler To: "libstdc++" Cc: Tulio Magno Quites Machado Filho , gcc-patches , wschmidt@linux.vnet.ibm.com, Segher Boessenkool Content-Type: text/plain; charset="UTF-8" X-SW-Source: 2018-03/txt/msg00067.txt.bz2 On 1 March 2018 at 18:54, Marc Glisse wrote: > On Thu, 1 Mar 2018, Tulio Magno Quites Machado Filho wrote: > >> In order to use the __float128 in C++ it's necessary to check if >> it is supported in libstdc++ (i.e. via _GLIBCXX_USE_FLOAT128) and if the >> compiler enabled its support too, e.g. -mfloat128 or -mno-float128. > > > Shouldn't we ensure that _GLIBCXX_USE_FLOAT128 is undefined instead? Yes, a better approach might be to add this to libstdc++-v3/include/bits/c++config.h: #define _GLIBCXX_USE_FLOAT128 #if !defined(__FLOAT128__) && !defined(__SIZEOF_FLOAT128__) #undef _GLIBCXX_USE_FLOAT128 #endif Then change libstdc++-v3/acinclude.m4 so that instead of defining _GLIBCXX_USE_FLOAT128 it does: GLIBCXX_CONDITIONAL(ENABLE_FLOAT128, ...) and then have libstdc++-v3/include/Makefile modify based on that, setting _GLIBCXX_USE_FLOAT128 to 0 or 1