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Date:      Wed, 17 Jul 2024 16:47:01 -0400
From:      enh <enh@google.com>
To:        sgk@troutmask.apl.washington.edu
Cc:        enh via freebsd-numerics <freebsd-numerics@freebsd.org>
Subject:   Re: #pragma STDC FENV_ACCESS ON
Message-ID:  <CAJgzZooM%2B7ECj2fu0CbE-Lm3HF3NPXzEE1zsFGicRGwitVYnYg@mail.gmail.com>
In-Reply-To: <ZpgpEc5zKPeEThzK@troutmask.apl.washington.edu>
References:  <CAJgzZoopJT3AJM8cbWzPjheKkcO9bAXXjVauw5g08bb=hgWeHQ@mail.gmail.com> <ZpgjDUvZc90-QfWW@troutmask.apl.washington.edu> <CAJgzZorpyKCE8RPiaDYED33dfck=%2BLVqcoDO8oWbUQRpfRe4mw@mail.gmail.com> <ZpgpEc5zKPeEThzK@troutmask.apl.washington.edu>

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On Wed, Jul 17, 2024 at 4:27=E2=80=AFPM Steve Kargl
<sgk@troutmask.apl.washington.edu> wrote:
>
> On Wed, Jul 17, 2024 at 04:16:33PM -0400, enh wrote:
> > On Wed, Jul 17, 2024 at 4:01=E2=80=AFPM Steve Kargl
> > <sgk@troutmask.apl.washington.edu> wrote:
> > >
> > > On Wed, Jul 17, 2024 at 01:30:39PM -0400, enh wrote:
> > > > i see lib/msun/src/e_sqrtl.c has `#pragma STDC FENV_ACCESS ON`, but
> > > > s_fma.c, s_fmaf.c, s_fmal.c, and s_nearbyint.c all use fesetround()=
 or
> > > > fesetenv() too --- shouldn't they also have the pragma?
> > > >
> > > > (Android currently builds all of libm with that pragma, but (a) tha=
t
> > > > seems like a big hammer and (b) afaict upstream [you] don't, so thi=
s
> > > > is potentially causing problems^W^Wallowing the compiler to cause
> > > > problems for you?)
> > >
> > > Some of the compilers, which that are used to compile FreeBSD,
> > > do not support "#pragma STDC FENV_ACCESS ON".
> >
> > that's why you have a line in the Makefile to quiet the warning :-)
> >
> > (remember you _do_ have this #pragma in e_sqrtl.c already.)
> >
>
> Then your original post is simply a rhetorical question?

no. i said:

1. e_sqrtl.c has `#pragma STDC FENV_ACCESS ON`

2. s_fma.c, s_fmaf.c, s_fmal.c, and s_nearbyint.c all use fesetround()
or fesetenv() but _don't_ have the pragma

that is: #1 implies you think this is needed, but #2 shows that it's
inconsistently applied in places where it's needed.

> Consider it future-proofing for when all compilers supprt
> the pragma.

"future proofing" is exactly why i'm suggesting you should probably
have the pragma in the other files that use the relevant functions :-)

> --
> Steve
>



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