I don't really agree with that. floating point operations are just inexact, regardless of optimizations. That's how they work, period.
It is true that they are inexact, but inexact and non-deterministic are not the same thing. Floating point operations are deterministic. Doing the same operation twice on the same machine with the same rounding mode and parameters will give you the same result. This should also be true when you do those operations using D, and using == on the two results should return true.
