[patch] Fix behavior of TER on unrolled loops

[Daniel Berlin]

> > Google for optimal register allocation and you'll find a bunch of papers
> > that try to take *everything* into account.
> > You'll discover that except for coalescing, the "simple approaches"
> > actually aren't more than ~3% off completely optimal approaches that
> > take literally everything into account.
> 
> The only thing I ever said is that all of the "simple approaches" suffer
> from the local minimum type problems, and that their behavior is too
> unreliable and unpredictable to claim things like "this is only a
> workaround that we will be able to remove once we improve RA".

You missed my point.
Existing research on optimal register allocation argues very well that
it is *not* the case that simple approaches get stuck in local minima.
They are, in fact, in almost all cases, globally optimal, except for
coalescing strategy.