From: Paul Eggert <eggert@cs.ucla.edu>
To: Eli Zaretskii <eliz@gnu.org>, Richard Copley <rcopley@gmail.com>
Cc: angelo.g0@libero.it, emacs-devel@gnu.org
Subject: Re: Suspicious warning in W64 build
Date: Thu, 7 Sep 2017 12:26:06 -0700 [thread overview]
Message-ID: <102a4c21-c275-c73e-ec53-0d85975dc968@cs.ucla.edu> (raw)
In-Reply-To: <83mv66z66p.fsf@gnu.org>
Eli Zaretskii wrote:
>> 18446744065119617024 is 1<<64.
>> The other number is (1<<64) - (1<<33) - (1<<2).
> Yes, I know. I just don't understand why GCC things that
>
> nglyphs * sizeof (WORD) * 2
>
> can have a value in this range. The type of nglyphs is 'int', and
> sizeof(WORD) gives 2. So the range should be between 0 (or 4) and 4
> times INT_MAX, which is nowhere near the values GCC displays.
>
If nglyphs is negative the first multiplication is done using unsigned
arithmetic, which could result in huge results. Presumably GCC does not know
that nglyphs must be nonnegative. Try putting an 'eassume (0 <= nglyphs);'
before the line in question. That is, if you're sure that nglyphs is
nonnegative: if you're not, GCC has found a real bug here.
next prev parent reply other threads:[~2017-09-07 19:26 UTC|newest]
Thread overview: 123+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-05 13:38 Suspicious warning in W64 build Angelo Graziosi
2017-09-05 14:04 ` Richard Copley
2017-09-07 15:16 ` Eli Zaretskii
2017-09-07 15:42 ` Angelo Graziosi
2017-09-07 17:52 ` Richard Copley
2017-09-07 17:58 ` Richard Copley
2017-09-07 19:00 ` Angelo Graziosi
2017-09-07 19:21 ` Richard Copley
2017-09-09 4:58 ` Herring, Davis
2017-09-09 9:55 ` Richard Copley
2017-09-09 10:20 ` Eli Zaretskii
2017-09-09 11:24 ` Angelo Graziosi
2017-09-09 13:25 ` Eli Zaretskii
2017-09-09 11:16 ` Angelo Graziosi
2017-09-07 18:58 ` Eli Zaretskii
2017-09-07 19:26 ` Paul Eggert [this message]
2017-09-07 19:50 ` Richard Copley
2017-09-07 20:02 ` Richard Copley
2017-09-08 6:49 ` Eli Zaretskii
2017-09-08 8:02 ` Eli Zaretskii
2017-09-08 19:31 ` Richard Copley
2017-09-08 20:17 ` Eli Zaretskii
2017-09-08 21:08 ` Richard Copley
2017-09-08 21:37 ` Richard Copley
2017-09-09 7:37 ` Eli Zaretskii
2017-09-08 22:20 ` Richard Copley
2017-09-09 7:33 ` Eli Zaretskii
2017-09-09 9:36 ` Richard Copley
2017-09-09 10:42 ` Eli Zaretskii
2017-09-09 10:52 ` Eli Zaretskii
2017-09-09 11:17 ` Richard Copley
2017-09-09 16:07 ` Eli Zaretskii
2017-09-10 1:01 ` Richard Copley
2017-09-10 14:40 ` Eli Zaretskii
2017-09-10 19:14 ` Richard Copley
2017-09-10 19:38 ` Angelo Graziosi
2017-09-11 16:17 ` Eli Zaretskii
2017-09-11 22:21 ` Angelo Graziosi
2017-09-11 16:39 ` Óscar Fuentes
2017-09-11 17:20 ` Eli Zaretskii
2017-09-12 17:49 ` Eli Zaretskii
2017-09-12 18:01 ` Fabrice Popineau
2017-09-12 18:37 ` Richard Copley
2017-09-12 18:59 ` Eli Zaretskii
2017-09-12 19:14 ` Richard Copley
2017-09-12 18:38 ` Eli Zaretskii
2017-09-14 17:47 ` Eli Zaretskii
2017-09-14 19:34 ` Richard Copley
2017-09-15 8:54 ` Eli Zaretskii
2017-09-15 23:05 ` Richard Copley
2017-09-16 6:40 ` Eli Zaretskii
2017-09-16 8:19 ` Richard Copley
2017-09-16 8:34 ` Richard Copley
2017-09-16 8:54 ` Eli Zaretskii
2017-09-16 9:07 ` Richard Copley
2017-09-16 11:54 ` Fabrice Popineau
2017-09-16 8:52 ` Eli Zaretskii
2017-09-15 8:59 ` Eli Zaretskii
2017-09-15 14:43 ` Eli Zaretskii
2017-09-17 6:42 ` Paul Eggert
2017-09-17 7:14 ` Richard Copley
2017-09-17 14:31 ` Eli Zaretskii
2017-09-17 6:40 ` Paul Eggert
2017-09-17 14:29 ` Eli Zaretskii
2017-09-17 16:39 ` Fabrice Popineau
2017-09-17 16:52 ` Eli Zaretskii
2017-09-18 0:26 ` Paul Eggert
2017-09-18 11:47 ` Fabrice Popineau
2017-09-18 14:46 ` Eli Zaretskii
2017-09-18 0:01 ` Richard Stallman
2017-09-14 19:36 ` Fabrice Popineau
2017-09-14 21:17 ` Andy Moreton
2017-09-15 6:55 ` Fabrice Popineau
2017-09-15 9:12 ` Eli Zaretskii
2017-09-15 15:33 ` Fabrice Popineau
2017-09-15 15:45 ` Eli Zaretskii
2017-09-15 18:15 ` Fabrice Popineau
2017-09-15 19:00 ` Eli Zaretskii
2017-09-15 21:02 ` Fabrice Popineau
2017-09-16 7:45 ` Eli Zaretskii
2017-09-17 7:01 ` Paul Eggert
2017-09-17 14:31 ` Eli Zaretskii
2017-09-17 14:52 ` Philipp Stephani
2017-09-17 22:34 ` Paul Eggert
2017-09-17 17:07 ` Paul Eggert
2017-09-17 17:14 ` Eli Zaretskii
2017-09-17 18:53 ` Paul Eggert
2017-09-17 19:30 ` Eli Zaretskii
2017-09-17 20:34 ` Paul Eggert
2017-09-18 2:30 ` Eli Zaretskii
2017-09-18 4:52 ` Paul Eggert
2017-09-18 14:41 ` Eli Zaretskii
2017-09-18 17:35 ` Paul Eggert
2017-09-18 17:58 ` Andy Moreton
2017-09-19 9:05 ` Paul Eggert
2017-09-18 18:01 ` Eli Zaretskii
2017-09-17 20:45 ` Paul Eggert
2017-09-16 13:17 ` Andy Moreton
2017-09-16 13:46 ` Eli Zaretskii
2017-09-16 18:57 ` Richard Copley
2017-09-16 19:21 ` Eli Zaretskii
2017-09-15 9:03 ` Eli Zaretskii
2017-09-09 8:49 ` Angelo Graziosi
2017-09-09 10:37 ` Eli Zaretskii
2017-09-09 11:32 ` Angelo Graziosi
2017-09-09 13:28 ` Eli Zaretskii
2017-09-09 13:33 ` Fabrice Popineau
2017-09-09 14:55 ` Angelo Graziosi
2017-09-09 16:37 ` Eli Zaretskii
2017-09-09 18:38 ` Angelo Graziosi
2017-09-09 18:59 ` Eli Zaretskii
2017-09-09 21:29 ` Angelo Graziosi
2017-09-10 14:56 ` Eli Zaretskii
2017-09-10 15:45 ` Angelo Graziosi
2017-09-10 16:02 ` Eli Zaretskii
2017-09-10 18:45 ` Angelo Graziosi
2017-09-10 19:43 ` Eli Zaretskii
2017-09-09 15:40 ` Angelo Graziosi
2017-09-09 16:40 ` Eli Zaretskii
2017-09-09 18:33 ` Fabrice Popineau
2017-09-07 20:20 ` Eli Zaretskii
2017-09-07 21:59 ` Angelo Graziosi
2017-09-08 8:01 ` Eli Zaretskii
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