"For an optimizing programmer, SIMD instructions are a resource from which most benefit must be squeezed at any reasonable cost, including tweaking the behavior

"For an optimizing programmer, SIMD instructions are a resource from which most benefit must be squeezed at any reasonable cost, including tweaking the behavior of the program. For an optimizing compiler, SIMD instructions are something that can be used to implement a piece of source code, in fact the preferable way to implement it - as long as its semantics are preserved. This means that a compiler obeys rules a programmer doesn’t, making winning impossible."