Identifying 32 vs 64 bit OS?

[via Digitalmars-d-learn]

On Monday, 11 August 2014 at 07:58:15 UTC, Freddy wrote:
> If you want to check if
> the target OS(not your code) is running 32 vs 64 bit you have 
> to do system call for your target OS.

Not the OS, but a special CPU instruction: isX86_64() in 
core.cpuid?