Some functions may have negative complexity and I’m worried for my crypto

Is this just a very smart optimizer that can reduce

  tot=x+x+x+x+x+x+x+x+x+x+x+x+x+x+x

to

  x2=x+x
  x4=x2+x2
  x8=x4+x4
  tot=x+x2+x4+x8

or I am missing something?

Note that the first code is O(N=15) and the second one is O(log(N)=4).