how to test which register is being used?

[matthew green]

hi folks.



how can one determine which register is being used, rather than
the value of the register?  i need to determine (in several
instructions) whether r6 or r7 are being used, and if so, set
a status bit (one for r6, one for r7).  the only solution i can
think of (that bje also suggested) was to have something in the
getter/setter to allow this, but as not every time these registers
are used are the status bits set, so this would not be correct.


thanks,


.mrg.