C programming The "C is Efficient" Language Fallacy
The Objective-Caml bytecode interpreter was faster than the carefully hand-optimized C program! Why? Because the OCaml compiler could recognize that the arrays were completely independent — it didn't need to worry about one iteration of the loop stepping on the values used by another. The C compiler couldn't apply a lot of useful optimizations, because it couldn't be sure that they were valid.
а что разве в современных компиляторах нет никаких костылей, чтобы помогать компилятору понимать такие вещи?