[PATCH] D83762: [Attributor][WIP] allow multiple branches in followUsesInMBEC

Sun Jul 26 04:48:13 PDT 2020

okura added a comment.

In D83762#2173265 <https://reviews.llvm.org/D83762#2173265>, @jdoerfert wrote:

> In D83762#2169156 <https://reviews.llvm.org/D83762#2169156>, @okura wrote:
>
> > Sorry for the confusion. I'm thinking about AADereferenceable.
> >  The test above exist in dereferenceable-1.ll as @rec-branch-2.
> >  The method I used in this patch does not currently handle that case (i.e., cannot deduce dereferenceable(4) for argument %ptr). 
> >  I think you expect dereferenceable(4) to be propagated to Known state for argument %ptr at the time after initialize (and followUsesInMBEC) is called.
> >  I don't and want to know how to do (for this or follow up patch).
>
>
> It is not clear to me how that would look as we would basically need to do fixpoint iteration and not simply exploration of known facts. It would need to happen in the update, etc.

On second thoughts, I think we don't necessarily have to do fixpoint iteration for this task. So I changed the fixpoint iteration to path exploration.

> Are the attached test changes all that occur?

Yes. I will add some new tests to reinforce that the path exploration works fine.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D83762/new/

https://reviews.llvm.org/D83762