SafepointIRVerifier is made unreachable block tolerant

SafepointIRVerifier crashed while traversing blocks without a DomTreeNode.
This could happen with a custom pipeline or when some optional passes were skipped by OptBisect.

SafepointIRVerifier is fixed to traverse basic blocks that are reachable from entry. Test are added.

Patch Author: Yevgeny Rouban!
Reviewers: anna, reames, dneilson, DaniilSuchkov, skatkov
Reviewed By: reames
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D47011


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@333063 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed