From: Jakub Jelinek <jakub@redhat.com>
To: Thomas Koenig <tkoenig@netcologne.de>
Cc: Bill Schmidt <wschmidt@linux.ibm.com>,
fortran@gcc.gnu.org, gcc@gcc.gnu.org,
Tobias Burnus <tobias@codesourcery.com>,
Segher Boessenkool <segher@kernel.crashing.org>,
Michael Meissner <meissner@linux.ibm.com>
Subject: Re: libgfortran.so SONAME and powerpc64le-linux ABI changes
Date: Fri, 15 Oct 2021 20:11:38 +0200 [thread overview]
Message-ID: <20211015181138.GI304296@tucnak> (raw)
In-Reply-To: <4c0d1a0d-457f-68d7-94f3-420bc2c33c69@netcologne.de>
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?
Because precision (0.0_double_double_kind) < precision (0.0_ieee_quad_kind)
so the "smallest of the kind values" doesn't trigger.
Jakub
next prev parent reply other threads:[~2021-10-15 18:11 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-04 10:07 Jakub Jelinek
2021-10-04 11:24 ` Richard Biener
2021-10-04 11:36 ` Jakub Jelinek
2021-10-04 12:31 ` Jakub Jelinek
2021-10-04 14:14 ` Jakub Jelinek
2021-10-04 16:47 ` Joseph Myers
2021-10-04 18:33 ` Segher Boessenkool
2021-10-04 19:24 ` Joseph Myers
2021-10-05 17:43 ` Segher Boessenkool
2021-10-14 19:39 ` Bill Schmidt
2021-10-15 0:26 ` Segher Boessenkool
2021-10-05 20:16 ` Thomas Koenig
2021-10-05 21:54 ` Segher Boessenkool
2021-10-06 6:59 ` Thomas Koenig
2021-10-06 15:17 ` Segher Boessenkool
2021-10-06 15:41 ` Jakub Jelinek
2021-10-06 16:07 ` Segher Boessenkool
2021-10-06 16:34 ` Jakub Jelinek
2021-10-06 16:59 ` Segher Boessenkool
2021-10-06 17:07 ` Jakub Jelinek
2021-10-06 17:50 ` Segher Boessenkool
2021-10-06 19:30 ` Peter Bergner
2021-10-06 17:13 ` Joseph Myers
2021-10-06 18:39 ` Segher Boessenkool
2021-10-06 19:42 ` Joseph Myers
2021-10-06 20:57 ` Segher Boessenkool
2021-10-06 21:55 ` Joseph Myers
2021-10-06 22:03 ` Joseph Myers
2021-10-08 17:53 ` Segher Boessenkool
2021-10-11 20:11 ` Joseph Myers
2021-10-15 0:16 ` Segher Boessenkool
2021-10-06 15:42 ` David Edelsohn
2021-10-06 16:19 ` Segher Boessenkool
2021-10-06 17:38 ` David Edelsohn
2021-10-07 3:42 ` Michael Meissner
2021-10-08 21:10 ` Segher Boessenkool
2021-10-07 9:48 ` Alastair McKinstry
2021-10-07 9:56 ` Andreas Schwab
2021-10-07 10:01 ` Jakub Jelinek
2021-10-07 12:43 ` Alastair McKinstry
2021-10-05 21:53 ` Jonathan Wakely
2021-10-07 3:35 ` Michael Meissner
2021-10-07 6:08 ` Thomas Koenig
2021-10-07 9:40 ` Jakub Jelinek
2021-10-07 15:24 ` Michael Meissner
2021-10-07 15:33 ` Jakub Jelinek
2021-10-08 6:35 ` Thomas Koenig
2021-10-08 7:20 ` Iain Sandoe
2021-10-08 16:26 ` Thomas Koenig
2021-10-08 19:11 ` Iain Sandoe
2021-10-08 22:55 ` Thomas Koenig
2021-10-08 23:18 ` Iain Sandoe
2021-10-09 9:11 ` Thomas Koenig
2021-10-09 9:19 ` Iain Sandoe
2021-10-09 9:25 ` Jakub Jelinek
2021-10-09 7:44 ` Andreas Schwab
2021-10-10 16:14 ` Florian Weimer
2021-10-15 13:50 ` Bill Schmidt
2021-10-15 14:20 ` Jakub Jelinek
2021-10-15 18:05 ` Thomas Koenig
2021-10-15 18:11 ` Jakub Jelinek [this message]
2021-10-15 18:58 ` Thomas Koenig
2021-10-15 22:24 ` Segher Boessenkool
2021-10-15 22:36 ` Segher Boessenkool
2021-10-18 19:02 ` Joseph Myers
2021-10-28 3:10 ` Michael Meissner
2021-10-29 3:36 ` libgfortran.so SONAME and powerpc64le-linux ABI changes (work in progress patches) Michael Meissner
2021-10-29 19:07 ` Thomas Koenig
2021-10-29 21:06 ` Michael Meissner
2021-11-01 15:56 ` Bill Schmidt
2021-11-02 15:40 ` Michael Meissner
2021-10-30 0:16 ` libgfortran.so SONAME and powerpc64le-linux ABI changes (2nd patch) Michael Meissner
2021-10-30 9:30 ` Thomas Koenig
2021-10-30 10:03 ` Jakub Jelinek
2021-10-30 10:31 ` Thomas Koenig
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