From: "N.M. Maclaren" <nmm1@cam.ac.uk>
To: Paul Koning <paulkoning@comcast.net>
Cc: Richard Biener <richard.guenther@gmail.com>,
"fortran@gcc.gnu.org" <fortran@gcc.gnu.org>
Subject: Re: Target control of Fortran options
Date: Thu, 04 Oct 2018 16:20:00 -0000 [thread overview]
Message-ID: <Prayer.1.3.5.1810041720520.23555@hermes-2.csi.cam.ac.uk> (raw)
In-Reply-To: <9A8B6E3D-D56C-45D0-93AE-8ED9EB0ADE1A@comcast.net>
On Oct 4 2018, Paul Koning wrote:
>>
>> If you don't have a 4-byte REAL, why do you make default REAL 4 bytes?
>> Do you mean that the front-end code assumes that it is? In which case,
>> I would say that it's a clear design bug! If not, why not just set it to
>> your basic floating type?
>
> That's what I expected and apparently I'm not the only one. But the
> actual code says that the default REAL is the 4 byte one, and if the
> compiler doesn't supply a float type of that size, the compiler crashes
> at startup.
That's a design mistake, though I can see how it happened. You do mean
4 byte, and not just REAL*4, though? If the latter, you can just make
REAL*4 mean your default real and have done with it! As I said, that
number is not always the size in bytes :-)
> Janne raises an interesting point, about Fortran requirements of int and
> float and double sizes that I was not aware of. Given those, it seems
> that the correct answer is to do the more traditional thing where "float"
> (REAL) is SFmode, 4 bytes -- always. In other words, make -mfloat32 be
> the only operating mode and retire that switch.
Not necessarily. Another option is to simply pad default INTEGER and
DOUBLE PRECISION - that's a common solution, and fully conforming. But
I don't know how hard that would be to do.
It's not relevant to the PDP11, but a lot of people feel that the correct
defaults for the modern world are 8 byte default integer and real, and
16 byte double precision.
Regards,
Nick Maclaren.
next prev parent reply other threads:[~2018-10-04 16:20 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-03 21:04 Paul Koning
2018-10-04 8:06 ` Richard Biener
2018-10-04 14:04 ` Paul Koning
2018-10-04 15:41 ` N.M. Maclaren
2018-10-04 15:48 ` Paul Koning
2018-10-04 16:20 ` N.M. Maclaren [this message]
[not found] ` <CAO9iq9F0oW35Ke3PjHM1hgZ_vjyq5H_gLYy=zLyUB5x1xBxrrg@mail.gmail.com>
2018-10-04 18:51 ` Paul Koning
2018-10-05 8:44 ` N.M. Maclaren
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