the compiler is entitled and correct to optimize that out. the target language prohibits integer overflow, therefore the compiler may assume it doesn't happen, and given this assumption, the result of the compare is known.

what is funny to me is for people to think they're allowed to exceed the speed of light to test whether they're breaking some law of physics. you can't exceed the speed of light, and traffic guards who know their physics know they don't have to check, they can safely relax, as the actual laws of physics cannot be broken ;-)