From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 116443 invoked by alias); 6 Sep 2016 21:53:35 -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 116433 invoked by uid 89); 6 Sep 2016 21:53:34 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_NONE,SPF_PASS,URIBL_RED autolearn=ham version=3.3.2 spammy=sk:cxx_fun, p0035, new-expression, wg21.link X-HELO: relay1.mentorg.com Received: from relay1.mentorg.com (HELO relay1.mentorg.com) (192.94.38.131) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Tue, 06 Sep 2016 21:53:24 +0000 Received: from nat-ies.mentorg.com ([192.94.31.2] helo=svr-ies-mbx-01.mgc.mentorg.com) by relay1.mentorg.com with esmtp id 1bhOIz-0001WD-2S from joseph_myers@mentor.com ; Tue, 06 Sep 2016 14:53:21 -0700 Received: from digraph.polyomino.org.uk (137.202.0.87) by svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) with Microsoft SMTP Server (TLS) id 15.0.1210.3; Tue, 6 Sep 2016 22:53:17 +0100 Received: from jsm28 (helo=localhost) by digraph.polyomino.org.uk with local-esmtp (Exim 4.86_2) (envelope-from ) id 1bhOIr-0004ze-B5; Tue, 06 Sep 2016 21:53:13 +0000 Date: Tue, 06 Sep 2016 21:56:00 -0000 From: Joseph Myers To: Jason Merrill CC: Florian Weimer , gcc-patches List , Subject: Re: Make max_align_t respect _Float128 [version 2] In-Reply-To: Message-ID: References: <3bb7530e-fff4-6030-a87e-1654d55d1e45@redhat.com> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-ClientProxiedBy: svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) To svr-ies-mbx-01.mgc.mentorg.com (139.181.222.1) X-SW-Source: 2016-09/txt/msg00349.txt.bz2 On Tue, 6 Sep 2016, Jason Merrill wrote: > The reason I care is that C++17 aligned new (wg21.link/p0035) > specifies that for types that require more alignment than the usual > operator new provides, the new-expression instead calls an operator > new with an explicit alignment parameter. MALLOC_ABI_ALIGNMENT > sounded like exactly what I was looking for, but then I noticed that > 'new long double' was going to the aligned new operator, which breaks > older code that replaces operator new (without, of course, replacing > the aligned variant). I'd say that cxx_fundamental_alignment_p is the right thing to use here, but maybe you want an option to override the alignment threshold for aligned new (in case someone interposes a malloc that uses lower alignment, but still wants to allocate some objects with higher alignment). -- Joseph S. Myers joseph@codesourcery.com