[llvm] r314435 - [JumpThreading] Preserve DT and LVI across the pass

[Philip Reames via llvm-commits]

To be clear, you're saying that there was a bug, we worked around it by 
making jump-threading not preserve LVI/DT, fixed the bug, then 
re-enabled the preservation?  If so, that's fine.  It would have been 
very helpful if the submit comment mentioned that history.


On 09/29/2017 08:49 AM, Sebastian Pop wrote:
> On Fri, Sep 29, 2017 at 10:29 AM, Philip Reames via llvm-commits
> <llvm-commits at lists.llvm.org> wrote:
>> Er, have you checked the history here?  I thought this preservation was
>> removed relatively recently to avoid a correctness bug.
> I think the bug you mention was related to jump-threading not preserving LVI,
> and this is because LVI was computed by jump-threading
> and LVI relies on correct dominators.
> I believe that with the committed patch we addressed all the problems
> to preserve both dominators and LVI across jump-threading.
> Please let us know if you see other problems.
>
> Thanks,
> Sebastian