Optimizing compilers are tricky this way, if you want to do it with optimzations turned on, you usually have to make the work "real" in some sense. Sometimes m

Optimizing compilers are tricky this way, if you want to do it with optimzations turned on, you usually have to make the work "real" in some sense. Sometimes making enough nesting depth that the compiler can't fully reason it out works, but usually it's easier to modify some memory it can't be sure isn't touched otherwise (and hence elide or register allocate it or whatever).