We used to represent these just as normal LLVM functions, e.x.:
declare objc_object* @objc_retain(objc_object*)
declare void @objc_release(objc_object*)
Recently, special objc intrinsics were added to LLVM. This pass updates these
small (old) passes to use the new intrinsics.
This turned out to not be too difficult since we never create these
instructions. We only analyze them, move them, and delete them.
rdar://47852297
These functions don't accept local variable heap memory, although the names make it sound like they work on anything. When you try, they mistakenly identify such things as ObjC objects, call through to the equivalent objc_* function, and crash confusingly. This adds Object to the name of each one to make it more clear what they accept.
rdar://problem/37285743
