From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cc-smtpout1.netcologne.de (cc-smtpout1.netcologne.de [89.1.8.211]) by sourceware.org (Postfix) with ESMTPS id 80D5A3858C60; Fri, 15 Oct 2021 18:58:14 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 80D5A3858C60 Received: from cc-smtpin2.netcologne.de (cc-smtpin2.netcologne.de [89.1.8.202]) by cc-smtpout1.netcologne.de (Postfix) with ESMTP id E73981274B; Fri, 15 Oct 2021 20:58:12 +0200 (CEST) Received: from [IPv6:2001:4dd7:f01f:0:7285:c2ff:fe6c:992d] (2001-4dd7-f01f-0-7285-c2ff-fe6c-992d.ipv6dyn.netcologne.de [IPv6:2001:4dd7:f01f:0:7285:c2ff:fe6c:992d]) (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 cc-smtpin2.netcologne.de (Postfix) with ESMTPSA id 265F011DE7; Fri, 15 Oct 2021 20:58:05 +0200 (CEST) Subject: Re: libgfortran.so SONAME and powerpc64le-linux ABI changes To: Jakub Jelinek Cc: Bill Schmidt , fortran@gcc.gnu.org, gcc@gcc.gnu.org, Tobias Burnus , Segher Boessenkool , Michael Meissner References: <20211004100754.GL304296@tucnak> <20211015142049.GD304296@tucnak> <4c0d1a0d-457f-68d7-94f3-420bc2c33c69@netcologne.de> <20211015181138.GI304296@tucnak> From: Thomas Koenig Message-ID: <08e21868-014e-5d39-8390-df9b80a2e303@netcologne.de> Date: Fri, 15 Oct 2021 20:58:05 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20211015181138.GI304296@tucnak> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-NetCologne-Spam: L X-Rspamd-Queue-Id: 265F011DE7 X-Spam-Status: No, score=-3.6 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, NICE_REPLY_A, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, 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: Fri, 15 Oct 2021 18:58:15 -0000 On 15.10.21 20:11, Jakub Jelinek wrote: > On Fri, Oct 15, 2021 at 08:05:38PM +0200, Thomas Koenig wrote: >>> with -mabi=ibmlongdouble, I see 31 and 291, while with -mabi=ieeelongdouble >>> 33 and 4931. The 0.0_8 precision/range values are 15 and 307, so neither >>> precision of C long double if it is double-double nor range matches anything. >>> If we do implement double-double support, I think KIND=15 would be better >>> than KIND=17, it is true that double-double has for certain numbers much >>> higher precision than IEEE quad, but the precision depends on the numbers >>> and most of the time is smaller, the range is always smaller. And >>> the PRECISION/RANGE intrinsic numbers are also both smaller. >> >> There is one potential problem: selected_real_kind. >> >> The standard says about that... >> >> # If more than one kind type parameter value meets the criteria, the >> # value returned is the one with the smallest decimal precision, unless >> # there are several such values, in which case the smallest of these >> # kind values is returned >> >> So, selected_real_kind(25) would yield double double, and we would >> have to violate the standard there if we wanted people to have >> IEEE QP in that case. > > That would be true if some kind exist for double double, whether > it is kind == 15 or kind == 17, no? Correct. The authors probably did not think of this particular case when they wrote the standard. We can ask the J3 standards committee to change the wording. I think I will just do that, to see what they have to say. Best regards Thomas