https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68823
--- Comment #11 from Sebastian Pop <spop at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #10)
> But then with different number of subscripts (and also likely different
> DR_BASE_OBJECT) you can't do anything with them and have to assume
> dependence. See initialize_data_dependence_relation:
>
> /* If the references do not access the same object, we do not know
> whether they alias or not. We do not care about TBAA or alignment
> info so we can use OEP_ADDRESS_OF to avoid false negatives.
> But the accesses have to use compatible types as otherwise the
> built indices would not match. */
> if (!operand_equal_p (DR_BASE_OBJECT (a), DR_BASE_OBJECT (b),
> OEP_ADDRESS_OF)
> || !types_compatible_p (TREE_TYPE (DR_BASE_OBJECT (a)),
> TREE_TYPE (DR_BASE_OBJECT (b))))
> {
> DDR_ARE_DEPENDENT (res) = chrec_dont_know;
> return res;
>
> not sure how you communicate that to ISL of course... is it what you
> use "alias-sets" for? To create extra dependence egdes?
alias-sets differ for two arrays with bases that have been proven to be
different.
If they may point to the same thing, they will have the same number.
