There are algorithms that use bits just like there are algorithms that use trees. You wouldn't expect your compiler to write your algorithms for you, would you.

There are algorithms that use bits just like there are algorithms that use trees. You wouldn't expect your compiler to write your algorithms for you, would you. Just recently, I've used the bitboards representation for cellular automata (which lets you compute 64 cells at the same time by doing about 100 non-branching integer instructions). I have difficulty seeing a compiler that can recognize that algorithmic optimization.