Are we better served by fast and correct code, or faster and wrong?
The gain from application of an optimization needs to be compared with the time and cost of bugs introduced by the same optimization. And dead code elimination isn't necessarily a huge win - if you're fairly sure code is dead, you can make it cheap at the cost of being more expensive should it actually be alive (see my other comment).
The gain from application of an optimization needs to be compared with the time and cost of bugs introduced by the same optimization. And dead code elimination isn't necessarily a huge win - if you're fairly sure code is dead, you can make it cheap at the cost of being more expensive should it actually be alive (see my other comment).