my GSoC proposal for implementation of the RFC: Devirtualization v2 has been accepted and I already started coding a month ago. Some patches are already in clang and llvm. Right now I am finishing implementing strip.invariant.group intrinsic, but mostly I spend time debugging some segfaults that happen with -fstrict-vtable-pointers.
If you are interested in the topic and would like to help with reviewing patches, please let me know. I am making improvements in multiple components in clang and LLVM (DSA, MSSA, Capture Tracking, intrinsics, InstCombine, Alias Analysis, GVN, LICM), so I will certainly need help from people who are familiar with these.