[Bug tree-optimization/83544] Missed optimization opportunity for constant folding

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83544

--- Comment #1 from Marc Glisse <glisse at gcc dot gnu.org> ---
In one case we optimize super early to
  int t = 1 / (int) x <= 0 ? 1 / 0 : 1;
which prevents the VRP optimization from the other case. We almost recover in
isolate-paths, except that Jeff insisted on using __builtin_trap() instead of
__builtin_unreachable(), so we don't. We could still simplify
  _2 = 1 / x.1_1;
  if (_2 != 1)
a bit to avoid actually performing the division, I think that's already tracked
in one of your earlier PRs.