They refer mostly to how globals and constants maintain use lists as linked lists, which is indeed a nightmare for synchronization. And yes, fixing that would r

They refer mostly to how globals and constants maintain use lists as linked lists, which is indeed a nightmare for synchronization. And yes, fixing that would require some difficult surgery. But let's be honest about what is more work: refactoring that, or rewriting all users of LLVM out there. My bet is on the first one being cheaper by at least three orders of magnitude.