64-bit support

[Bill Baxter]

bearophile wrote:
> Bill Baxter:
>> eventually Walter himself may decide that switching to the 
>> LLVM back-end makes the most sense.
> 
> LLVM may allow D to do certain things that today are difficult, like run-time creation of routines (they can be created by macros too), and other dynamic things you can see in C#3.x, etc. With that you can create something that even CommonLisp programmers may find attractive ;-)

Not to mention that it should fix a raft of other long-standing bugs 
that have to do with OPTLINK.  I'm pretty convinced that LLVM is the way 
to go long term.  It would free Walter up from having to deal with back 
end issues, but still allow him to tinker with the back end or 
contribute patches to the LLVM team if he needs something to be fixed 
for D.  It would allow D to benefit from a world wide community working 
on porting to new back-end targets, and making improvements to the 
optimizer etc. Not to mention allowing D to piggyback on the corporate 
support from the likes of Apple that is going into LLVM right now.

I see basically no down sides to such a move, other than making the move 
would initially be a big time suck.  But I think the writing is on the 
wall that OPTLINK will have to be replaced eventually one way or 
another.  Going with LLVM looks to be the best way to do that in terms 
of cost/benefit ratios.

--bb