RSSA

[Matthew Fluet]

(Oops - had this postponed all day.)

> > If you don't, then we need the live variables at an array allocation
> > to fill in the live variables that are live around the
> > initialization loop.
> 
> Arrays are always at the beginning of a basic block, so until it's
> there (add it if you want (or I will)), you can use the live of the
> block.

We can live without it for now; the live information taken from the
Machine IL is just used as hints, albeit very accurate hints, about the
live pseudo-regs and stack-slots at each block.  There is a pass that
checks and fills in any discrepencies; the last time I printed out
warnings when the Machine IL and computed