[LLVMdev] tbaa

Dan Gohman gohman at apple.com
Tue Dec 6 09:25:36 PST 2011

On Dec 5, 2011, at 8:08 PM, liyi at cs.toronto.edu 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.
>> Dan
> Hi Dan,
> So do you know how to get the correct results from tbaa? It seems
> "print-alias-sets" also has all the pointers in one set.

-print-alias-sets is going to be pretty useless, because any time there's
even a single "omnipotent char" anywhere, it'll MayAlias everything,
so everything will be transitively MayAliased to everything else, and
you'll end up with one big set.

I don't think there are any other tools that do anything similar in LLVM.


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