This is a quick-and-dirty straw man implementation of reference-types
support for the WebAssembly backend. anyref value types are represented
as non-integral pointers in addrspace(1) and tables are represented as
external global in addrspace(1) pointing to pointers also in addrspace(1).
The bulk of the work here is just adding all the boiler plate for multiple tables
and the new instruction encodings. The ISel part of this is very primitive
and just the quickest thing I could possibly do to play with this. In its current
state, I've gotten it to emit .o files that I think are correctly formed,
but I haven't been able to test them properly (I think at least some of the
problem is browser bugs I'm looking into).
This isn't ready for review or anything, but I figured
a) This might save somebody else some time in implementing the boiler plate
b) It could serve as a starting point to discuss how to represent this in IR