From: Joel Sherrill <joel@rtems.org>
To: Stephanos Ioannidis <root@stephanos.io>
Cc: "Richard.Earnshaw@foss.arm.com" <Richard.Earnshaw@foss.arm.com>,
"newlib@sourceware.org" <newlib@sourceware.org>
Subject: Re: round() on arm vs aarch64
Date: Tue, 15 Nov 2022 12:17:00 -0600 [thread overview]
Message-ID: <CAF9ehCVNR8bP0TReoyLe4hBU7YCT1i-jm4-XQsRtmMYrBPCPvA@mail.gmail.com> (raw)
In-Reply-To: <c5223a720d7d447c1546c9cb9e8696350a6f817c.camel@stephanos.io>
[-- Attachment #1: Type: text/plain, Size: 1792 bytes --]
On Tue, Nov 15, 2022 at 9:58 AM Stephanos Ioannidis <root@stephanos.io>
wrote:
> On Tue, 2022-11-15 at 09:38 -0600, Joel Sherrill wrote:
> > Digging a bit, I noticed a huge block of <cmath> is ifdef'ed out for
> > aarch64.
> > I found the file c++config.h which is different between the two.
> >
> > Based on the diff of the arm and aarch64 versions, arm has
> > _GLIBCXX_USE_C99_MATH_TR1 defined but aarch64 does not.
> >
> > I have no idea where the settings in this file come from but this
> > appears to be the key difference.
> >
> > More insight appreciated.
>
> Funny how I came across a similar issue today. The following link might
> be of help in understanding what is going on:
>
>
> https://github.com/zephyrproject-rtos/sdk-ng/issues/566#issuecomment-1315165640
Thanks for the quick reply. It is a shame that the lack of long double
methods
prevents the entire TR1 from being there. Wouldn't it be ok to just have the
prototypes and let the user get a link error?
Anyway, I have been very very slowly picking at newlib long double support
but haven't gotten a complete patch set that is acceptable. See
https://sourceware.org/newlib/ for the discussion. I am happy to share
my work in process.
As I recall, one of the sticking points is that the FreeBSD code has
long double support for architectures which have true long double but
nothing as far as I can tell for architectures where double == long double.
I was proposing a configure time selection of the current code for when
long double == double and use the imported FreeBSD code when there
is true long double support.
Making libstdc++'s configure probe more forgiving would be a nice step
but long term having complete long double support would be better.
How to progress?
--joel
>
> Regards,
>
> Stephanos
>
prev parent reply other threads:[~2022-11-15 18:17 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-03 14:13 Joel Sherrill
2022-11-07 17:28 ` Richard Earnshaw
2022-11-15 15:38 ` Joel Sherrill
2022-11-15 15:58 ` Stephanos Ioannidis
2022-11-15 18:17 ` Joel Sherrill [this message]
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