From: Andrew Haley <aph@redhat.com>
To: gcc-help@gcc.gnu.org
Subject: Re: how to make gcc warn about arithmetic signed overflow
Date: Thu, 26 Sep 2013 18:19:00 -0000 [thread overview]
Message-ID: <52446F22.3040205@redhat.com> (raw)
In-Reply-To: <20130926170232.GA8435@xvii.vinc17.org>
On 09/26/2013 06:02 PM, Vincent Lefevre wrote:
> On 2013-09-26 15:49:05 +0100, Andrew Haley wrote:
>> On 09/26/2013 09:29 AM, Vincent Lefevre wrote:
>>> On 2013-09-25 22:29:58 -0400, James K. Lowden wrote:
>>>> You mean that a naïve rendering of the source code implies an overflow
>>>> where none might exist in the actual emitted object code. And,
>>>> presumably, the converse: that even if the source is written such that
>>>> there logically can't be an overflow, the compiler might render object
>>>> code that does.
>>>
>>> The converse is forbidden.
>>
>> You'll find it hard to justify that by any language in the standard.
>
> What do you mean?
There is no reason why a compiler should not generate an overflow
where none is written in the program, as long as it doesn't generate
a different result.
Andrew.
next prev parent reply other threads:[~2013-09-26 18:19 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-21 16:45 wempwer
2013-09-21 17:24 ` Jonathan Wakely
2013-09-21 17:41 ` wempwer
2013-09-21 18:30 ` Jonathan Wakely
2013-09-21 18:50 ` wempwer
2013-09-21 19:55 ` Jędrzej Dudkiewicz
2013-09-21 20:16 ` wempwer
2013-09-21 20:52 ` Jędrzej Dudkiewicz
2013-09-21 21:07 ` wempwer
2013-09-23 4:04 ` James K. Lowden
2013-09-23 7:55 ` Jonathan Wakely
2013-09-23 15:47 ` James K. Lowden
2013-09-23 21:50 ` Jonathan Wakely
2013-09-23 22:44 ` James K. Lowden
2013-09-23 23:20 ` Jonathan Wakely
2013-09-23 19:38 ` Dave Allured - NOAA Affiliate
2013-09-23 19:43 ` Oleg Endo
2013-09-23 20:37 ` Dave Allured - NOAA Affiliate
2013-09-23 19:48 ` Andrew Haley
2013-09-23 22:00 ` James K. Lowden
2013-09-24 17:48 ` Andrew Haley
2013-09-26 2:30 ` James K. Lowden
2013-09-26 8:29 ` Vincent Lefevre
2013-09-26 14:49 ` Andrew Haley
2013-09-26 17:03 ` Vincent Lefevre
2013-09-26 18:19 ` Andrew Haley [this message]
2013-09-27 7:58 ` Vincent Lefevre
2013-09-27 8:23 ` Andrew Haley
2013-09-27 9:28 ` Vincent Lefevre
2013-09-27 9:43 ` Andrew Haley
2013-09-26 17:41 ` Andrew Haley
2013-09-24 7:42 ` Brian Drummond
2013-09-21 17:53 ` Marc Glisse
2013-09-21 18:09 ` wempwer
2013-09-21 18:27 ` Jonathan Wakely
2013-09-21 19:32 ` wempwer
2013-09-22 15:52 ` Jonathan Wakely
2013-09-23 13:04 ` David Brown
2013-09-21 17:36 ` Brian Drummond
2013-09-21 17:45 ` wempwer
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