From: "N.M. Maclaren" <nmm1@cam.ac.uk>
To: Paul Koning <paulkoning@comcast.net>
Cc: Janne Blomqvist <blomqvist.janne@gmail.com>,
Richard Guenther <richard.guenther@gmail.com>,
Fortran List <fortran@gcc.gnu.org>
Subject: Re: Target control of Fortran options
Date: Fri, 05 Oct 2018 08:44:00 -0000 [thread overview]
Message-ID: <Prayer.1.3.5.1810050944010.16700@hermes-2.csi.cam.ac.uk> (raw)
In-Reply-To: <FA0E0A34-DF2C-4A17-9472-EF374C20FC12@comcast.net>
On Oct 4 2018, Paul Koning wrote:
>> On Oct 4, 2018, at 10:31 AM, Janne Blomqvist
>>
>> So what this implies is that e.g. if you want the default kind REAL to
>> be 8 bytes, then the default kind INTEGER and LOGICAL must also be 8
>> bytes types, and further there must exist a 16 byte DOUBLE PRECISION
>> type.
>
> Thanks, that was very helpful. While pdp11 can do INTEGER*8, it can't do
> REAL*16. And I have no idea why the float == double thing was done
> originally in the first place. It goes all the way back to the original
> version of the file (from 1994).
The requirement is on storage size, not extra precision or range. As I
tried to say earlier, but may not have been clear, the usual solution to
that issue was to have DOUBLE PRECISION using an 8-byte real in a 16-byte
location - i.e. 8 bytes of data and 8 of padding, on some order.
It does seem a bit odd, though there are several plausible reasons.
Regards,
Nick Maclaren.
prev parent reply other threads:[~2018-10-05 8:44 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
[not found] ` <CAO9iq9F0oW35Ke3PjHM1hgZ_vjyq5H_gLYy=zLyUB5x1xBxrrg@mail.gmail.com>
2018-10-04 18:51 ` Paul Koning
2018-10-05 8:44 ` N.M. Maclaren [this message]
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