[Bug tree-optimization/104334] [12 Regression] Ranger/dom miscompilation

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104334

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
So, in the debugger the difference is in the range_operator::wi_fold_in_parts
function (with:
enum class A { A0, A1, A2, A3 };
int x;

void baz ();

struct B {
  unsigned b : 2;

  A
  foo () const
  {
    return static_cast<A> (b);
  }

  void bar ();
};

void
B::bar ()
{
  if (foo () == A::A2 || foo () == A::A3)
    baz ();
}
the first one).
type is unsigned:2, lh_lb 0, lh_ub -1 (aka 3), rh_lb and rh_ub -2 (aka 2).
lh_range is -1 (aka 3), rh_range is 0, ov_{l,r}h is OVF_NONE.
In the non-LTO case, we do wi_fold on line 176
171       // Otherise check for 2, 3, or 4 values in the LH range and split
them up.
172       // The RH side has been checked, so no recursion needed.
173       else if (wi::gt_p (lh_range, 0, sign) && wi::lt_p (lh_range, 4, sign)
174                && ov_lh == wi::OVF_NONE)
175         {
176           wi_fold (r, type, lh_lb, lh_lb, rh_lb, rh_ub);
while in the LTO case on line 192.

The wi::lt_p (rh_range, 4, sign) and wi::lt_p (lh_range, 4, sign) calls
look highly suspicious, 4 is not representable in unsigned:2.