Re: GCC optimizes integer overflow: bug or feature?

[Florian Weimer]

* Paolo Bonzini:

> Interesting read.  I agree with the proposed fix; however, note that
> GCC does not make the result of overflowing signed left-shifts
> undefined, exactly because in this case the overflow is relied upon by
> too many existing programs

Is this documented somewhere?  Without documentation, it could also be
an oversight (lack of optimization) from a programmer perspective.