Another interesting take: Machine architectures expose an API, and it may become impossible for anyone but a chip manufacturer to distribute a compiler.
Machine architectures are very much copyrightable right? That's why Intel license x86 to AMD.
Thing is, for chip manufactures it makes no sense not to allow others to call this x86 API. Things could get dicier for other who try and virtualize a machine instruction set.
It might not matter to the law which side of an interface you're on, if your work is still clearly derivative (in the legal sense) of that interface design.
