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NNTP-Posting-Date: Thu, 07 Jul 2011 16:53:56 -0500
Date: Thu, 07 Jul 2011 14:53:50 -0700
From: Patricia Shanahan <pats@acm.org>
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Subject: Re: Arithmetic overflow checking
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On 7/7/2011 2:34 PM, Gene Wirchenko wrote:
> On Wed, 06 Jul 2011 22:41:54 -0700, Roedy Green
> <see_website@mindprod.com.invalid>  wrote:
>
>> On Wed, 6 Jul 2011 08:35:01 -0700 (PDT), rop rop<rop049@gmail.com>
>> wrote, quoted or indirectly quoted someone who said :
>>
>>> If I want to have arithmetic-overflow checking in all parts of an
>>> application,
>>> what is the most practical, simple, efficient way to achieve this?
>>> Id like to clutter the code as little a possible...
>>> Is there any way to instruct the JVM to include it?
>>
>> the JVM does not detect it because most hardware does not. You pretty
>> well have to use long instead of int and mask off and check overflow.
>
>       Which hardware does not have overflow detection?
>
>       x86 does have an overflow flag.

So far, every instruction set I have studied has included overflow
detection at the hardware level.

I think the problem is more a matter of software knowing when overflow
should and should not be treated as an error.

Patricia