Doc for -fcall-used-REG and -fcall-saved-REG

[Jeffrey A Law]

  In message < m0zTED4-000s8JC@cetus.cygnus.com >you write:
  > My question is whether we need to keep the above comment for 
  > other fixed pervasive role registers (other than the sp and fp);
  > something like:
  > 
  >    Use of this flag for the stack pointer or the frame pointer is
  >    an error.  Use of this flag for a register that has a fixed 
  >    pervasive role in the machine's execution model, other than 
  >    the stack pointer and frame pointer, will produce disastrous
  >    results.
  > 
  > Or wether we know that there are no other such fixed registers,
  > and can drop that second sentance?  Does anyone know of other
  > fixed pervasive role (perhaps machine specific) registers  
  > exist?
argument & return value registers come to mind.  Registers which are in a class
by themselves (think HILO on mips, shift count registers and the like).  The
return pointer may be another worth worrying about.


jeff