[Bug tree-optimization/126503] Wrong code with signed bitint

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126503

--- Comment #1 from ktkachov at gcc dot gnu.org ---
Another testcase that goes wrong (I'm not sure if it's a dup)
typedef _BitInt(129) T;
__attribute__((noipa)) T f (T x) { return x - 24; }
__attribute__((noipa)) int eq (T a, T b) { return a == b; }
int main (void)
{
  if (!eq (f (100), 76))
    __builtin_abort ();
  return 0;
}