In JDK-8347273, we added IGVN Ideal and Identity verification. But we had to exclude a lot of nodes from verification. We should investigate and possibly fix them one-by-one, and file subtasks here.

In many cases, the issue is just a missing notification when inputs of inputs are changed. These would be good starter tasks. But there are probably also more complicated cases. And there are surely cases where verification will be impossible, because it is possible that the Idea / Identity optimizations traverse longer paths, and we cannot expect that notification makes it down that path. For those cases, we will have to leave the exception and document it well.