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Re: svn_repos_trace_node_locations()

From: Florian Weimer <fw_at_deneb.enyo.de>
Date: 2004-06-19 13:40:39 CEST

* Greg Hudson:

> On Sun, 2004-06-13 at 04:52, Florian Weimer wrote:
>> * Greg Hudson:
>>
>> > I think we're already fairly sunk on platforms where signed overflow is
>> > signalled, so we're not worried about that.
>>
>> Uh-oh, you know that signed integer overflow is undefined in GCC land?
>> 8->
>
> Specifics?

It is undefined. Some optimizations do not check for possible
overflow conditions; anything can happen in such cases.

> But it's acceptable to behave as if some other value was
> specified in the input; or, in one case, we can detect the signed
> overflow after the fact by checking if newval / 10 == oldval.

In the future, when GCC has range propagation optimizations, such
checks will be optimized away. If you use signed integer arithmetic,
you have to check beforhand to ensure that no overflow occurs.

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Received on Sat Jun 19 13:47:59 2004

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