AM30/AM33 SP handling

[Jeffrey A Law]

  In message < orpurj9run.fsf@zecarneiro.lsd.ic.unicamp.br >you write:
  > 	* config/mn10300/mn10300.h (REG_CLASS_FROM_LETTER): Return
  > 	EXTENDED_REGS only if TARGET_AM33.
  >
  > 	* config/mn10300/mn10300.md (movsi): Move SP handling to
  > 	separate patterns.
I fail to see the benefit of the movsi change.  It may also be dangerous --
at one time the movXX patterns were special in that they needed to support
all the possible movXX alternatives in a single pattern.  I do not know if
the movXX patterns are still special in that respect.

If the REG_CLASS_FROM_LETTER change is OK if it does not depend on the
movsi change.  

I'd prefer to leave movsi alone unless there is significant benefit in 
changing it -- measurable improvement across any of the 3 optimization
axis (compile time speed, generated code size, generated code speed) or
for maintenance purposes.

jeff