[Bug c/103406] gcc -O0 behaves differently on "DBL_MAX related operations" than gcc -O1 and above

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103406

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Hmm, the trunk is constant folding (maybe wrong?).

We used to get for 11.1.0:
  _1 = 1.79769313486231570814527423731704356798070567525844996599e+308 *
2.0e+0;
  _2 = 1.79769313486231570814527423731704356798070567525844996599e+308 *
2.0e+0;
  _3 = _1 - _2;
  x_6 = -_3;

But now we get 0.0.