From: Florian Weimer <fweimer@redhat.com>
To: Paul Zimmermann <Paul.Zimmermann@inria.fr>
Cc: carlos@redhat.com, libc-alpha@sourceware.org
Subject: Re: Linux Plumbers Conference: GNU Tools Track: glibc BoF (notes)
Date: Thu, 23 Sep 2021 10:08:51 +0200 [thread overview]
Message-ID: <87zgs3soh8.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <mwpmszen4i.fsf@tomate.loria.fr> (Paul Zimmermann's message of "Thu, 23 Sep 2021 10:01:49 +0200")
* Paul Zimmermann:
>> > thank you for the report. Where can we get more information on the
>> > "ppc64le long double change"?
>> >
>> > Is that https://fedoraproject.org/wiki/Changes/PPC64LE_Float128_Transition?
>> > On that page, by "128-bit IEEE format" you mean a 128-bit encoding, but
>> > holding only 64 bits of significand (format called ldbl-96 in glibc)?
>>
>> Essentially it's about switching the distribution default from
>> sysdeps/ieee754/ldbl-128ibm to sysdeps/ieee754/ldbl-128.
>>
>> The former is a pair of doubles, using Dekker's method, and the latter
>> is the regular binary128 IEEE quad-precision format.
>
> thank you Florian for the clarification. Then "long double" in C will
> map to binary128, like _Float128?
Yes, but you can go back to double-double with a compiler flag if you
wish (-mabi=ibmlongdouble, I think).
Thanks,
Florian
next prev parent reply other threads:[~2021-09-23 8:09 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-22 17:59 Carlos O'Donell
2021-09-22 18:33 ` Siddhesh Poyarekar
2021-09-23 7:20 ` Paul Zimmermann
2021-09-23 7:54 ` Florian Weimer
2021-09-23 8:01 ` Paul Zimmermann
2021-09-23 8:08 ` Florian Weimer [this message]
2021-09-23 18:01 ` Tulio Magno Quites Machado Filho
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