From: Corinna Vinschen <vinschen@redhat.com>
To: newlib@sourceware.org
Subject: Re: generic fenv wrapup
Date: Tue, 13 Aug 2019 07:50:00 -0000 [thread overview]
Message-ID: <20190813075032.GR11632@calimero.vinschen.de> (raw)
In-Reply-To: <CAF9ehCV+J3u4WoaXH9hUXK2KXrXXq7DMD0aszv34Az=vgNLOhg@mail.gmail.com>
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On Aug 12 08:51, Joel Sherrill wrote:
> Hi
>
> We discussed a lot for this patch. I see FE_NOMASK_ENV isn't included.
> When looking at that, the comment in /usr/include/bits/fenv.h on CentOS 7
> has a subject verb agreement issue that leads me to question its intent.
> I would like someone to confirm that the glibc manual and this comment
> mean the same thing:
>
> ifd#f __USE_GNU
> /* Floating-point environment where none of the exception is masked. */
> # define FE_NOMASK_ENV ((const fenv_t *) -2)
> #endif
>
> And from the manual:
>
> If possible, the GNU C Library defines a macro FE_NOMASK_ENV which rep‐
> resents an environment where every exception raised causes a trap
> to
> occur. You can test for this macro using #ifdef. It is defined
> only
> if _GNU_SOURCE is defined.
>
> I think the manual version is clearer on intent.
>
> Also.. there are three other GNU specific methods:
>
> #define _GNU_SOURCE /* See feature_test_macros(7) */
> #include <fenv.h>
>
> int feenableexcept(int excepts);
> int fedisableexcept(int excepts);
> int fegetexcept(void);
>
> Should all those be added conditionally?
_GNU_SOURCE definitely. Conditionally on what else?
> What else did we think needed to be done with the fenv generic code before
> moving on to focusing on implementations?
Just have a look into Cygwin's fenv.h. There's also fegetprec/fesetprec
which have been defined with SunOS and made it into a standarization
proposal http://www.open-std.org/jtc1/sc22//WG14/www/docs/n752.htm They
have not been standarized, though, so this is kind of optional. They
should probably get defined for x86{_64} but not necessarily for any
other target.
Corinna
--
Corinna Vinschen
Cygwin Maintainer
Red Hat
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prev parent reply other threads:[~2019-08-13 7:50 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-12 13:51 Joel Sherrill
2019-08-13 7:50 ` Corinna Vinschen [this message]
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