From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from hamza.pair.com (hamza.pair.com [209.68.5.143]) by sourceware.org (Postfix) with ESMTPS id E93DF385841A for ; Fri, 10 Feb 2023 09:06:09 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org E93DF385841A Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=pfeifer.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=pfeifer.com Received: from hamza.pair.com (localhost [127.0.0.1]) by hamza.pair.com (Postfix) with ESMTP id 9D23E33EA1; Fri, 10 Feb 2023 04:06:07 -0500 (EST) Received: from [192.168.22.150] (212095005041.public.telering.at [212.95.5.41]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by hamza.pair.com (Postfix) with ESMTPSA id 5CA5833EAC; Fri, 10 Feb 2023 04:06:06 -0500 (EST) Date: Fri, 10 Feb 2023 10:06:03 +0100 (CET) From: Gerald Pfeifer To: Jakub Jelinek cc: gcc-patches@gcc.gnu.org Subject: Re: [wwwdocs] gcc-13/changes.html: Document C++ -fexcess-precision=standard In-Reply-To: Message-ID: <541d2859-4029-3a21-e57e-10a401c5d226@pfeifer.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Scanned-By: mailmunge 3.10 on 209.68.5.143 X-Spam-Status: No, score=-1.7 required=5.0 tests=BAYES_00,KAM_DMARC_STATUS,RCVD_IN_BARRACUDACENTRAL,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Thu, 9 Feb 2023, Jakub Jelinek wrote: > Martin Liska mentioned that porting_to.html doesn't mention > the C++ excess precision changes. Not really sure if porting_to > should document those, but I think changes.html certainly should. Do you think this is a widely spread issue for existing software? Did it materialize a couple of times building/testing Fedora with GCC 13 snapshots (assuming you have done so as in the past)? > Ok for wwwdocs? Yes, thank you! Two minor suggestions/questions below: > --- a/htdocs/gcc-13/changes.html > +++ b/htdocs/gcc-13/changes.html > + -fexcess-precision=fast. The option affects mainly Here I'd say "mainly affects". > + IA-32/x86-64 where when defaulting to x87 math and in some cases on > + Motorola 68000 float and double expressions > + are evaluated in long double precision and S/390, System z, > + IBM z Systems where float expressions are evaluated in > + double precision. The "where when" part proved a bit tricky for my brain. :-) I think it is precise, but am wondering whether ...IA-32/x64 using x87 math and in some cases on Motorola 68000, where float and double expressions are evaluated... might work? What do you think? Gerald