64 bit version?

[mok-kong shen]

I just read that D fits nicely to the 64-bit architecture. Is there currently
a D compiler that fully exploits the 64-bit hardware under Windows 7? I mean
e.g. one can have operations in D on unsigned long int of 64 bits size that
correspond directly to hardware operations so as to achieve high efficiency?
(Sorry for my ignorant's question, I don't know yet the language.) Thanks in
advance.

M. K. Shen