[Bug c++/81410] O3 breaks code

[gcc at sjor dot sg]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81410

--- Comment #3 from Sjors Gielen <gcc at sjor dot sg> ---
A trivial workaround is put inside the first loop:

  std::cout << "";

I suppose this prevents loop optimization by introducing potential side
effects.