
Also reapply "[llvm] Teach whole program devirtualization about relative vtables" This reverts commit 1c604a9780fcfe92a99d539913553f0835b81de3 and 474f5efebed24547e76d022f0c5ffcc9db97ce6f.
Also reapply "[llvm] Teach whole program devirtualization about relative vtables" This reverts commit 1c604a9780fcfe92a99d539913553f0835b81de3 and 474f5efebed24547e76d022f0c5ffcc9db97ce6f.