D/Objective-C 64bit

[w0rp]

This is really awesome work. If you combined ARM support with 
Objective C support, it would mean you could write iOS programs 
in D without much frustration, and that would be a huge step 
forward. Objective C has a good runtime, but lacks templates and 
CTFE. Using CTFE for an iOS program could be very cool.

How do you plan to handle automatic reference counting? I imagine 
that's a hard part. When I was writing Objective C I remember 
having to write bridged casts so I could manually extend or limit 
object lifetime, but I never handled it from within a C library.