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Sat, 8 Jan 2022 19:37:17 +0000 (GMT) Date: Sat, 8 Jan 2022 14:37:16 -0500 From: Michael Meissner To: David Edelsohn Cc: Michael Meissner , Jakub Jelinek , Thomas Koenig , Segher Boessenkool , "fortran@gcc.gnu.org" , Peter Bergner , Bill Schmidt , GCC Patches Subject: Re: [power-ieee128] OPEN CONV Message-ID: Mail-Followup-To: Michael Meissner , David Edelsohn , Jakub Jelinek , Thomas Koenig , Segher Boessenkool , "fortran@gcc.gnu.org" , Peter Bergner , Bill Schmidt , GCC Patches References: <332da363-1c64-e1bf-a05a-d412c600f580@netcologne.de> <20220107214813.GR2646553@tucnak> <124cfb8a-e3d0-207c-8dcb-bdfab29372cb@netcologne.de> <20220108110038.GS2646553@tucnak> <20220108111056.GT2646553@tucnak> <20220108140258.GU2646553@tucnak> <8aff0c01-1715-aa06-5823-ed92567c1ea6@netcologne.de> <20220108141807.GV2646553@tucnak> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-TM-AS-GCONF: 00 X-Proofpoint-GUID: PfTNzY_hJG0GwbGqaJSE4f982opEnblu X-Proofpoint-ORIG-GUID: yZafw0YjScMkKVVxzW5zoOITRR1RZsy7 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2022-01-08_07,2022-01-07_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 mlxlogscore=960 clxscore=1015 impostorscore=0 mlxscore=0 phishscore=0 malwarescore=0 lowpriorityscore=0 suspectscore=0 spamscore=0 bulkscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2201080147 X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_EF, RCVD_IN_MSPIKE_H2, 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: fortran@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Fortran mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 08 Jan 2022 19:37:23 -0000 On Sat, Jan 08, 2022 at 02:15:14PM -0500, David Edelsohn wrote: > On Sat, Jan 8, 2022 at 1:59 PM Michael Meissner wrote: > > > > On Sat, Jan 08, 2022 at 03:18:07PM +0100, Jakub Jelinek wrote: > > > On Sat, Jan 08, 2022 at 03:13:10PM +0100, Thomas Koenig wrote: > > > > > > > > On 08.01.22 15:02, Jakub Jelinek via Fortran wrote: > > > > > Note, as for byteswapping, apparently it wasn't ever working right fox > > > > > the IBM extended real(kind=16) and complex(kind=16). > > > > > > > > The lack of bug reports since the conversion feature was introduced in > > > > 2006, more than 15 years ago, tells us something, I guess... > > > > > > powerpc64le was only introduced in GCC 4.8 in 2013, so slightly less > > > than that, but still. > > > Either nobody interchanges/shares fortran unformatted data between > > > powerpc big and little endian, or if they do, they don't use real(kind=16) > > > or complex(kind=16) in there... > > > > I still wish I had had the forethought when we were setting up the LE ABI to > > change the default 128-bit format to IEEE instead of IBM. But alas, I didn't. > > You would still need converters between the big endian IBM format and little > > endian IEEE format, but it would have avoided a lot of the problems where GCC > > assumes there is only one floating point format for each size. > > Mike, > > The LE ABI initial target was Power8 and IEEE128 hardware support was > added to Power9. The ABI was a conscious decision. IEEE 128 was not a > viable requirement for the LE ABI at the time of the transition. Yes I know, but my memory is we (the GCC group within IBM) at least knew that IEEE 128-bit was coming towards the end of the ABI definition period. But perhaps not. In any case, it doesn't much matter now, as it is all ancient history. -- Michael Meissner, IBM PO Box 98, Ayer, Massachusetts, USA, 01432 email: meissner@linux.ibm.com