[PATCH] D28114: [StructurizeCfg] Update dominator info.

[Daniel Berlin via Phabricator via llvm-commits]

dberlin added a comment.

In https://reviews.llvm.org/D28114#639445, @dberlin wrote:

> I'm fairly confused.
>  Forward dominators should  not have multiple roots at once without multiple actual entry blocks (which i didn't think we supported).
>  Yet you seem to be creating such a thing.
>  That seems ... wrong.
>  What am i missing?
>
> Post-dom can have multiple roots due to multiple exit blocks, but honestly, we kind of mess this up, and would likely be much better off having a single virtual root, and removing the support for multiple real roots
>  (which is what everyone else does)


Oh, forget it, i see that you are swapping the root node.

This still won't work well with post-dom unless we move to a virtual root.
(and then you'd never have to swap the root node in either case)


https://reviews.llvm.org/D28114