>>>>> "Gabriel" == Gabriel Dos Reis <[EMAIL PROTECTED]> writes:
> Robert Dewar <[EMAIL PROTECTED]> writes: > > Gabriel Dos Reis wrote: >> Robert Dewar <[EMAIL PROTECTED]> writes: >> >"has the semantics that Gabriel Dos Reis wants" is not an evaluable >> >predicate! >> You completely missed the point, but I guess it is consistent with >> your denying that there is any connection between C or C++ and >> hardware. > > So, let's make this MUCH more specific. Gabriel, on the MIPS chip, > do you think there is something in the definition of C that leads > you to prefer wrap around semantics to trapping semantics? Gabriel> When it comes down for the compiler writer to chose Gabriel> something for undefined behaviour, it is hardly solely based Gabriel> on the C standard. In fact, the C standard is of much less Gabriel> help because it gaves up. That's my reaction as well. The standard says "do something". The compiler has to pick a "something". If the choice is between trapping and wrap for MIPS arithmetic, I'd choose wrap without a question. The reason: my expectation is that, in each place where the situation arises in the code created in our team, wrap is the better answer. Ideally the issue should not arise -- if it's expected in the code, unsigned variables should be used or the condition should be tested for explicitly. But if that's missed, I believe that wrapping will produce the "that's what I meant" outcome, while an overflow trap will cause the system to malfunction at the customer site. paul
