RFC: Unpredictable register set operations

[Doug Evans]

Daniel Jacobowitz writes:
 > So what happens if you "set $ps = 0"?  Well, the right thing happens, but
 > until the next time the target stops "print $ps" will print 0.  Which is not
 > actually the value of the $ps register.
 > 
 > Thoughts?  Is this a problem worth fixing?

Definately worth fixing.

In complex systems there may be various scripts that make use of
these register's values.
Having these scripts randomly break because gdb is lying to the script
about what the value of the register is is, well, not nice.