[LLVMdev] tbaa

Daniel Berlin dberlin at dberlin.org
Tue Dec 6 17:36:18 PST 2011

On Tue, Dec 6, 2011 at 12:26 PM, Dan Gohman <gohman at apple.com> wrote:
> On Dec 5, 2011, at 9:32 PM, Daniel Berlin wrote:
>> 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 :)
> No, you've confused pointer types with pointee types.  That "any pointer"
> tag is for describing when the in-memory objects themselves have pointer
> types.

Right, and when i later debugged it, some of the queries were about
whether int** could alias a float *, which would properly be fixed ...

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