From: Geoff Keating <geoffk@cygnus.com>
To: dewar@gnat.com
Cc: kenner@vlsi1.ultra.nyu.edu, gcc@gcc.gnu.org
Subject: Re: Pathalogical divides
Date: Sun, 24 Sep 2000 23:29:00 -0000 [thread overview]
Message-ID: <200009250627.XAA20873@geoffk.org> (raw)
In-Reply-To: <20000925060704.18ACD34DB0@nile.gnat.com>
> Cc: gcc@gcc.gnu.org
> Date: Mon, 25 Sep 2000 02:07:04 -0400 (EDT)
> From: dewar@gnat.com (Robert Dewar)
>
> <<Yes. C interpreters are permitted to do anything they like when
> signed integer arithmetic overflows, including producing a signal.
> >>
>
> Actually while I think that is a valid interpretation of K&R rules,
> it is VERY difficult to read the ANSI standard this way, check out
> the exact wording, which seems to imply that the result is implementation
> defined within certain limits, but I cannot read it to allow a signal.
???
It says, in s. 6.5 paragraph 5 of ISO/IEC 9899:1999:
If an _exceptional condition_ occurs during the evaluation of an
expression (that is, if the result is not mathematically defined or
not in the range of representable values for its type), the behaviour
is undefined.
'undefined behaviour' can always include a signal, or anything else
that a mad compiler designer could dream up.
--
- Geoffrey Keating <geoffk@cygnus.com>
next prev parent reply other threads:[~2000-09-24 23:29 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-09-25 2:35 Robert Dewar
2000-09-24 23:29 ` Geoff Keating [this message]
-- strict thread matches above, loose matches on Subject: below --
2000-09-25 6:57 Robert Dewar
2000-09-25 5:19 Robert Dewar
2000-09-25 2:43 Richard Kenner
2000-09-25 14:27 ` Geoff Keating
2000-09-26 4:37 ` Jamie Lokier
2000-09-21 12:12 Richard Kenner
2000-09-22 1:45 ` Andreas Schwab
2000-09-23 13:38 ` Jeffrey A Law
2000-09-25 6:53 ` Alexandre Oliva
2000-09-24 22:53 ` Geoff Keating
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