https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120837
--- Comment #13 from Jakub Jelinek <jakub at gcc dot gnu.org> --- And/or detect cases where doing this optimization is valid on pointers, say &arr[0] + (x + 4) where (&arr[0] + 4) + x is valid because the arr is array and has 4+ elements, or &arr[1] + (x - 1) where (&arr[1] - 1) + x is valid too. But when for ptr + (x + cst) or ptr + (x - cst) ptr + cst or ptr - cst aren't valid pointer arithmetics, we can only do non-pointer arithmetics or punt.
