How about a 100% CTFE?

[Trass3r]

>>> version(ARM)
>>> {
>>> immutable X = armSpecificCode(); // you want to run this on an X86???
>>> }
>>>
>> I've always thought that it would be worthwhile to experiment with
>> LLVM's JIT engine here.
>> But as has been said quite some care will be necessary for cross
>> compilation.
>> Allowing arbitrary non-pure functions would cause lots troubles.
>
> Yeah, I think JIT for CTFE would be *very* interesting. But mainly for  
> reasons of speed rather than functionality.

How would JIT work in the above case?