I'm writing a compiler, but if I want it to be on more than one platform, it seems I have to learn every assembly language for the different platforms. I've seen a number of languages which try to be 'portable assembly languages' such as Linolium and C--, but they all seem to be incomplete or abandoned.
Is there any such language which can be used as a compiler back-end language?
If this is a stupid question for any reason, please say so, as I am new to writing compilers/interpreters.
--PieSquared