...I think a compromise would be to do define a interpreter global PMCNull and point (or init) all Px registers to it.
The downside is fast initialization of register blocks. memsetting with NULL (0)
will not be possible, but I'd have to actually go check and see if that
is really all that common.
If we determine that it makes a difference, we can store away a register block filled with our PMCNull, and memcpy (or memmove) from that to initialize a block. Should be nearly as fast.
JEff
