Force compiler to not optimize side-effect-less statements

Question

I was reading some old game programming books and as some of you might know, back in that day it was usually faster to do bit hacks than do things the standard way. (Convert

Answer 1

You just need to skip to the part where you learn something and read the published Intel CPU optimisation manual.

These quite clearly state that casting between float and int is a really bad idea because it requires a store from the int register to memory followed by a load into a float register. These operations cause a bubble in the pipeline and waste many precious cycles.