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Re: Ada front-end depends on signed overflow
- From: Florian Weimer <fw at deneb dot enyo dot de>
- To: Paul Schlie <schlie at comcast dot net>
- Cc: Andrew Pinski <pinskia at physics dot uc dot edu>, GCC List <gcc at gcc dot gnu dot org>, <bosch at gnat dot com>
- Date: Fri, 03 Jun 2005 17:18:04 +0200
- Subject: Re: Ada front-end depends on signed overflow
- References: <BEC5DF94.A5CF%schlie@comcast.net>
* Paul Schlie:
>> (Without -fwrapv, integer overflow is undefined, and subsequent range
>> checks can be optimized away, so that it might cause erroneous
>> behavior.)
>
> - Since for all practical purposes most (if not all) target's use
> 2's complement integer representations which naturally "wrap", might
> it be simply best to presume that all do "wrap" by default, but allow
> -fnowrapv to disable it if ever required by the odd target/language?
Enabling -fwrapv disables quite a few optimizations on signed integer
types in C code. OTOH, you should compile most real-world C code with
-fwrapv anyway. See my security advisory on incorrect overflow
checking in C; this is a rather widespread issue, even in new code.