64-bit addresses have a number of subtle advantages, even if you aren't addressing more than 4GB of memory. One is address space layout randomization (ASLR), wh

64-bit addresses have a number of subtle advantages, even if you aren't addressing more than 4GB of memory. One is address space layout randomization (ASLR), which makes it harder for attackers to determine memory locations to use in exploits. ASLR works with 32-bit addresses, but it works far better with 64-bit addresses, where any given guess is overwhelmingly likely to point to absolutely nothing. This is pretty relevant to Apple, who are increasingly concerned about security on iOS.