occasionally the first hop of a block would try to rearrange its registers (due
to evicted throughs), resulting in the phi moves copying values into the wrong
registers.
order. Since the dominance tree has changed when I fiddled with the graph, I
need to recompute it, so factor it out of the SSA pass. Code is uglier than I'd
like but at least the RET statement goes last in the generated code now.
inasmuch as it looks better before register allocation. Basic blocks now know
their own successors and predecessors (after a certain point in the IR
processing).
