Implementing a Chaitin Graph Coloring Register Allocator

[dibyendumajumdar]

Most implementations we can find are of more advanced versions rather than the original Chaitin Graph Coloring Allocator described in Register Allocation & Spilling via Graph Coloring.

Our allocator will work on the IR targeting a virtual machine rather than a real machine, so spilling is not strictly required. But it will be nice to have it anyway.