[LLVMdev] tbaa

[Daniel Berlin]

On Mon, Dec 5, 2011 at 11:01 PM, Dan Gohman <gohman at apple.com> wrote:
> On Dec 5, 2011, at 6:04 PM, Daniel Berlin wrote:
>>
>> Yet, aa-eval still says otherwise.
>
> The problem is with aa-eval. It collects all the pointer values in a
> function, and then just makes a bunch of raw pointer queries, rather than
> considering dereferences. TBAA tags are only attached to dereferences.
> So TBAA always has to say MayAlias for every aa-eval query.

Makes sense.  In that case, it would give the expected answers if
clang was enhanced to properly deal with similar/dissimilar pointer
types, instead of giving all pointer types the "everything" tag :)

This requires implementing the "pointer to first member is allowed as
pointer to struct"/etc rules, however.