Do C++ signed types have modulo semantics?

[Robert Dewar]

Steven Bosscher wrote:
> On Wednesday 29 June 2005 20:01, Daniel Berlin wrote:
> 
>>So i would advise anyone arguing against turning on -fwrapv simply
>>because it doesn't seem to hurt us at O2.
> 
> 
> wtf, "doesn't seem to hurt us at -O2".  Look again at the 64 bits
> numbers!  Losing 5% on the fp benchmarks is a serious regression.
> Even without exercising the heavy-ammo loop optimizers, -fwrapv is
> a serious performance-hurter.

Still these figures are very interesting for Ada, where I am afraid
the kludge we do in the front end for required overflow checking is
much more expensive than these figures indicate. Of course this will
be *highly* target dependent.