[acqq]

> That suggests your C compiler isn't doing jump threading

And even if he has such a compiler (which is doubtful) he doesn't have to put the "break" in the switch! He can write continues, e.g. this:

        switch ( i ) {
        case 3:
            i = 7; continue;
        default:
            continue;
        }

is valid C, and specifies explicitly that the next loop pass is expected.