[PATCH] D20907: [IfConversion] Bugfix: don't add Undef flag on use if reg is live.

[Matthias Braun via llvm-commits]

MatzeB added a comment.

In https://reviews.llvm.org/D20907#504458, @jonpa wrote:

> Pushed again as r277571, since everyone agrees this is better to have in trunk.
>
> Do we need to do anything further with IfConversion liveness tracking at this point, or should it really work with correct live-in lists? (I am having a bit of second thoughts about this although we agreed before that this could be possible).


I don't know whether there is further work necessary at the moment. However I plan to revisit IfConversion soon anyway, because I am still in the process of making code depend less on kill flags (ideally to the point where we can completely remove them). That means I have to rework the liveness tracking logic in IfConversion anyway to walk backwards instead of forward.


https://reviews.llvm.org/D20907