compressed oops and 64-bit header words

[Y Srinivas Ramakrishna]

Hi Coleen --

Regarding:-

> The mark word can also contain a forwarding pointer used during GC, so 
> 
> can't be 32 bits.

What about the lock record / stack pointer when the object is locked?
Would that also be a factor precluding compression to 32 bits even if GC were to 
compress and decompress forwarding pointers at some cost (in time
and representable heap size, because of the need for the forwarding bit
even in the compressed case).

-- ramki