Patch: Support IA-64 speculation [4/5]

[Andi Kleen]

Jan Hubicka <hubicka@ucw.cz> writes:
> 
> Adding backward pointers will increase their size by 30%, so perhaps
> some mark dead and collect later scheme would work here better?

Can't you use a xor list?  It works as long as you can keep 
enough context to know about the following (or previous) entry too.
However if it's garbage collected it might be difficult to teach the GC
about it because the pointers will be encoded. I guess it could 
be done however with some tricks.

-Andi