[PATCH][no-undefined-overflow] Add basic C++ support

[Paolo Bonzini]

Joseph S. Myers wrote:
> On Fri, 6 Mar 2009, Paolo Bonzini wrote:
> 
>> Second, optimizations that require wrapping semantics are still disabled
>> with -fno-strict-overflow and require -fwrapv explicitly.  I don't know
> 
> These optimizations are of course a key advantage of having explicit tree 
> codes, since they can now transform an overflow-undefined operation to an 
> overflow-wraps one rather than being disabled altogether without -fwrapv.

Yes -- referring to the other thread, I only have doubts about the
trapping codes.  Everything else I can only applaud.

Paolo