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From: Joseph Myers <joseph@codesourcery.com>
To: Szabolcs Nagy <szabolcs.nagy@arm.com>
Cc: DJ Delorie <dj@redhat.com>, <libc-alpha@sourceware.org>, <nd@arm.com>
Subject: Re: riscv: fmax/fmin sNaN fix
Date: Tue, 20 Feb 2018 23:11:47 +0000	[thread overview]
Message-ID: <alpine.DEB.2.20.1802202302400.7674@digraph.polyomino.org.uk> (raw)
In-Reply-To: <b680364d-83ef-48ba-1885-71e50ccc4845@arm.com>

On Tue, 20 Feb 2018, Szabolcs Nagy wrote:

> On 20/02/18 02:57, DJ Delorie wrote:
> > 
> > RISC-V's FPU follows the IEEE spec, not the POSIX spec.  This patch
>                            ^^^^^^^^^
> which one?
> (the next ieee revision will have different min/max operations)

The point (as per 
<https://sourceware.org/ml/libc-alpha/2018-01/msg01084.html>) is that fmax 
and fmin in TS 18661-1 bind to maxNum and minNum.  Those operations are to 
be removed in IEEE 754-2018 so the C functions will have semantics that no 
longer have a corresponding IEEE operation (much like e.g. nextafter / 
nexttoward, which correspond to the Nextafter operation recommended in 
IEEE 754-1985 but removed in IEEE 754-2008).  Instead, the new minimum, 
minimumNumber, maximum and maximumNumber operations are proposed to have 
new functions fminimum, fminimum_num, fmaximum, fmaximum_num (and likewise 
*mag* functions) - but so far there is no public draft of those proposed 
TS changes (which might in any case more likely be dealt with in the C2x 
process rather than through a new revision of the TS being produced).

-- 
Joseph S. Myers
joseph@codesourcery.com


  parent reply	other threads:[~2018-02-20 23:09 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-20  2:57 riscv: fmax/fmin sNaN fix DJ Delorie
2018-02-20 10:26 ` Szabolcs Nagy
2018-02-20 17:12   ` DJ Delorie
2018-02-20 17:22   ` DJ Delorie
2018-02-21 10:44     ` Szabolcs Nagy
2018-02-21 17:25       ` DJ Delorie
2018-02-21 23:24         ` Carlos O'Donell
2018-02-22  0:24           ` DJ Delorie
2018-02-22 20:28             ` Carlos O'Donell
2018-02-22 20:34               ` DJ Delorie
2018-02-22 20:42                 ` Joseph Myers
2018-02-22 20:50                   ` Joseph Myers
2018-02-23  1:58                     ` DJ Delorie
2018-02-23  2:01                       ` Joseph Myers
2018-02-23  2:08                         ` DJ Delorie
2018-02-20 22:03   ` Richard Henderson
2018-02-20 23:11   ` Joseph Myers [this message]
2018-02-21 21:25 ` Palmer Dabbelt

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