[PATCH] D36107: [PostDom] document the current handling of infinite loops and unreachables

[Jakub Kuderski via Phabricator via llvm-commits]

kuhar added a comment.

In https://reviews.llvm.org/D36107#826573, @grosser wrote:

> we have little tests that verify the update behavior of PDT after changes that introduce/remove virtual nodes. This is shown by the fact, that the first test case (construction of unreachables) illustrates a bug where we forget to add a new virtual exit node.
>
> I would like to commit this change, to have some more test coverage for https://reviews.llvm.org/D36107 and especially to make the impact of https://reviews.llvm.org/D36017 more clear.


Just to clarify a bit: the current behavior posdominator updates is just broken when it comes to root handling -- it just happens that the verifier is broken in an analogous way and blindly trusts the set of roots inside a dominator tree. If for some reason we wanted keep not including infinite loops in postdominators, then it would be still possible to fix the root-finding behavior on updates. I mean, this issue is a bit orthogonal to what https://reviews.llvm.org/D36017 tries to do.


https://reviews.llvm.org/D36107