https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117279
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
it's because p points to itself and thus p.ptr[index] "points to" p:
p.ptr = &p.local_buf;
..
_4 = p.ptr;
_5 = _4 + index_11(D);
_6 = *_5;
_7 = (int) _6;
__builtin_printf ("%c\n", _7);
points-to does not use range-info to see that _4 + index_11(D) doesn't
access p.ptr. In the end any non-constant pointer offsetting will cause
us to consider the whole object.
This could in theory be improved with (static) range-info.
