>
> But part of the expensiveness we want to avoid is this
> (repeated) walking of the ref tree...
I was considering to pass contains_union_p down from one of
earlier walks, but did not find suitable one for that...
>
> So...
>
> > + return !handled_component_p (ref2);
> > +}
> > +
> > /* Return true if an indirect reference based on *PTR1 constrained
> > to [OFFSET1, OFFSET1 + MAX_SIZE1) may alias a variable based on BASE2
> > constrained to [OFFSET2, OFFSET2 + MAX_SIZE2). *PTR1 and BASE2 have
> > @@ -1533,7 +1563,12 @@ indirect_ref_may_alias_decl_p (tree ref1
> > && (TREE_CODE (TREE_TYPE (base1)) != ARRAY_TYPE
> > || (TYPE_SIZE (TREE_TYPE (base1))
> > && TREE_CODE (TYPE_SIZE (TREE_TYPE (base1))) == INTEGER_CST)))
> > - return ranges_maybe_overlap_p (doffset1, max_size1, doffset2,
> > max_size2);
> > + {
> > + if (!ranges_maybe_overlap_p (doffset1, max_size1, doffset2,
> > max_size2))
> > + return false;
> > + if (same_access_paths_p (ref1, max_size1, ref2, max_size2))
> > + return true;
>
> how about a simpler test like
>
> if (known_size_p (max_size1) && known_size_p (max_size2))
> return true;
> /* If there's an unconstrained variable access in the ref fall
> through to access-path based disambiguation. */
If I have something like
struct a {int a[10];int b;}
and then
aptr->a[i]
in the access path, won't be max_size known (40) where type size is 4?
In this case I want to contiue to access path.
>
> ?
>
> I'd certainly like to see testcases btw...
There is a testcase for variable array access included in the patch,
would you like to have one with union in it?
>
> A more stricter test would be
>
> if (!maybe_eq (max_size1, size1) && !maybe_eq (max_size2, size2))
> return true;
> /* If there's a variable access in one of the refs fall through
> to access-path based disambiguation. */
>
> where you'd need to pass down ao_ref_size in addition to max_size as well.
Proably || here?
Honza
