eliminating null pointer checks on mmu-less machines

Sat Sep 13 09:09:00 GMT 2003

Adam Megacz wrote:
>Hey, I was thinking about NullPointerException handling on machines
>with no MMU. There's not much that can be done for field accesses,
>but method invocations are much more common.
>>Is it feasible to place an object at address 0x0
>Short answer: No in 90% of the cases.
Processors often have special stuff at physical address 0, like internal
registers, trap vectors and such.
It could be possible to redefine NULL to be something different
from 0. I've no idea how expensive that would be, but I suspect
it is very expensive.
Cedric