The function oopDesc::mark_addr() returns a pointer to the mark word, with the volatile qualifer for the mark word stripped off. That's pretty questionable for what is supposed to be an atomic value that may have concurrent reads and writes. Fortunately, there is no code that examines the contents of that pointer. In fact, there are only 3 uses of this function, all as the base argument for a prefetch operation (and all in gc code). There are other ways to compute that same address. We can use those instead, and remove the questionable mark_addr().