pub fn interference_edges(spec: &RegSpec) -> Vec<(usize, usize)>Expand description
The interference graph’s edges: every pair of variables (i, j) (i < j) whose live ranges
overlap, so they cannot share a register. Register allocation is exactly colouring this graph; for
straight-line code it is an interval graph (perfect), so its chromatic number equals the largest
clique equals the register pressure.