value range propagation for _bitwise_ OR

[bearophile]

Fawzi Mohamed:
> I guess that I am missing something obvious, so I don't see the reason  
> for range propagation, but maybe I am not the only one, so thanks for  
> an explanation...

Range propagation can improve the situation a little, so it's not bad. But it can't replace proper integral overflows. You need integral overflows at runtime.

Bye,
bearophile