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From "Ivan Volosyuk" <ivan.volos...@gmail.com>
Subject Re: [drlvm/mmtk] jitrino.jet write barrier initial implementaion
Date Mon, 10 Jul 2006 15:17:19 GMT
On 7/10/06, Weldon Washburn <weldonwjw@gmail.com> wrote:
> On 7/10/06, Ivan Volosyuk <ivan.volosyuk@gmail.com> 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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