[Bug tree-optimization/121952] [9 regression] produces incorrect code with optimisation on x86-64 Linux

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121952

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
bool0 - bool1 -> bool0 ^ bool1
bool0 + bool1 -> bool0 ^ bool1

Also:
  _7 = n_21 - _6;
  _8 = _7 + 1;
  _29 = _8 & 1;
  expected_24 = _29 == 0;

The +1 and == 0 cancel each other out.