[gclist] Compiler tables for accurate gc

[David Chase]

I said:
> Just curious, but what algorithm for "live" are you using?
> There's a very good one based on SSA that has the entertaining
> but unfortunate characteristic of deleting output-free
> infinite loops (unless it is tweaked).

But I have live-dead dyslexia.  It's SSA dead code elimination
that does this, which changes the question to:

  do you precede your live variable analysis with another
  optimizations, especially (but not limited to) a good
  dead code elimination?

David