[Bug tree-optimization/126458] New: Wrong code with bitint

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126458

            Bug ID: 126458
           Summary: Wrong code with bitint
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ktkachov at gcc dot gnu.org
                CC: jakub at gcc dot gnu.org
  Target Milestone: ---

Testcase:
typedef unsigned _BitInt(33) u33;

__attribute__((noipa)) int
neg (unsigned int a)
{
  return ((int) a) < 0;
}

__attribute__((noipa)) u33
fref (unsigned int a)
{
  return neg (a) ? (u33) a : (u33) 4294967295u;
}

__attribute__((noipa)) u33
f (unsigned int a)
{
  return ((int) a) < 0 ? (u33) a : (u33) 4294967295u;
}

int
main (void)
{
  static const unsigned int v[] = { 0x80000000u, 0xfffffffeu, 0x7fffffffu, 0u
};

  for (unsigned i = 0; i < sizeof v / sizeof v[0]; i++)
    if (f (v[i]) != fref (v[i]))
      __builtin_abort ();
  return 0;
}

This aborts with GCC on aarch64, but passes with Clang