I don't know how much this actually affects your argument, since you seem to be making a more general statement, but for the record: it's extraordinarily rare f

I don't know how much this actually affects your argument, since you seem to be making a more general statement, but for the record: it's extraordinarily rare for vulnerabilities to be caused by compiler optimizations specifically. I've heard of a few instances (BIND denial of service; Linux TUN bug becoming exploitable instead of a denial of service; IIRC something with Native Client), but they're interesting precisely because they're rare. So I'd say that one shouldn't oppose compiler optimizations directly because of the risk of security vulnerabilities, although of course the prevalence of vulnerabilities can still be evidence that C programmers are prone to mistakes in general.