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

Compilers are unfortunately allowed to optimise as much as they like, even without any explicit switches, if the code behaves as if no optimisation takes place. However, you can often trick them into not doing so if you indicate that value might be used later, so I would change your code to:

int float_to_int(float f)
{
    return static_cast(f); // has no side-effects
}

As others have suggested, you will need to examine the assemnler output to check that this approach actually works.