On 7/10/06, Weldon Washburn <[EMAIL PROTECTED]> wrote:
On 7/10/06, Ivan Volosyuk <[EMAIL PROTECTED]> wrote:
> One question, why do we need write barriers for 'putstatic' bytecode?
> This fields appear in root set and does not represent heap to heap
> references. There is no need to add write barriers to this entities.

Good question.  The short answer is because MMTk makes zero
assumptions about the VM automatically enumerating all the static
locations holding ref ptrs.   DRLVM makes the assumption that statics
will be part of the root set.  We really don't have hard data at this
point to show us the best approach yet.   I vote for leaving it in for
now. This is really the kind of GC/VM integration issue I expect the
MMTk port force us to deal with.

I think nothing is done without the reason. Looks like the static
fields in Jikes live somewhere in java heap. The code will make sense
if DRLVM will do the same, otherwise the write barriers will possibly
confuse implementation of MMTk, as the changed values are reside
outside the heap.

Regards,
--
Ivan
Intel Middleware Products Division

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