Backend port: Minimizing register usage in favor of memory accesses

[Richard Earnshaw]

> The goal of an optimizing compiler is to produce the fastest code for 
> the target.

Not necessarily.  The goal of an optimizing compiler is to minimize some 
cost metric.  Sometimes that cost metric is the same as 'target execution 
time' at other times it is something else, such as 'code size'.  Many of 
the specific optimizations performed will be same regardless of the 
overall cost metric being worked on; but not always.

R.