Jim,

In C++ optimisers are not generally seen as some sort of magic bullet, typically I always compile my code *without* optimisations and then when I know everythings as it should be I turn on specific optimisations telling the optimiser to optimise for size, speed or a combination of both.

Now optimisers can do strange things to code, so you are right they can have completely the opposite effect by introducing bugs! I have to say though that typically object code generated from well written C++ will be optimal.

Regards
Neil