How to deal with inline asm functions in Phobos/druntime?

[Johan Engelen via digitalmars-d-ldc]

Hi Kai,
   OK!
I'd very much appreciate an example of how to add the code above 
to ilogb in std.math. The "version(...)" stuff quickly becomes a 
mess.
Could you take the code above and show me how you would put this 
into std.math?
I'm sorry if this is too much hand-holding, it is really very 
much appreciated.

-Johan