LoopVR::runOnFunction runs.
This should accomplish that, but it doesn't. I think that's a PassManager bug,
but without a consumer of LoopVR in the tree, I can't give steps to reproduce.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52886 91177308-0d34-0410-b5e6-96231b3b80d8