Switch to MC for instruction printing.
This encompasses several changes which are all interconnected:
- Use the MC framework for printing almost all instructions.
- AsmStrings are now live.
- This introduces an indirection between LLVM vregs and WebAssembly registers,
and a new pass, WebAssemblyRegNumbering, for computing a basic the mapping.
This addresses some basic issues with argument registers and unused registers.
- The way ARGUMENT instructions are handled no longer generates redundant
get_local+set_local for every argument.
This also changes the assembly syntax somewhat; most notably, MC's printing
does not use sigils on label names, so those are no longer present, and
push/pop now have a sigil to keep them unambiguous.
The usage of set_local/get_local/$push/$pop will continue to evolve
significantly. This patch is just one step of a larger change.
llvm-svn: 252910
