Re: [rvm-research] Regarding Address of Object Reference in Field section of Object

Robin,

The process is basically to mark the references as I trace the objects.
Since I want to mark the instance field references in each object, I want
to mutate a single bit indicating the reference is processed.  So yes to
question (you want to add a single bit of metadata to each object reference
?).Thank you for your help. I  want to try Read Barriers. I appreciate your
quick response. Is there any code that  already overrides read barrier?

Cheers
Hari Krishnan.


On Mon, Jan 13, 2014 at 10:45 PM, Robin Garner <[email protected]>wrote:

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> Hari,
>
> Just to clarify, you want to add a single bit of metadata to each
> object reference ?
>
> The "simplest"[1] solution is to use one of the two low-order bits of
> each object reference (objects are always (at least) 4-byte aligned).
>  In order to do this you'll need a read barrier that masks out this
> bit so that the mutator always sees aligned pointers, and a write
> barrier that reinstates the metadata.
>
> Alternatively, if this is too expensive, I'd suggest adding additional
> space to the object via the classloader - how easy this is depends on
> how you want to use the data, how much space you're prepared to use etc.
>
> cheers
>
> [1] Read barriers are never simple :-/
>
> On 14/01/14 12:01, Hari Krishnan wrote:
> > Hi ,
> >
> > I want to set a bit, toggle a bit and test a bit in the section
> > where each address of the instance field (object references) saved
> > in objects. Is there any bit that I can use in each object fields
> > for this purpose?
> >
> > Cheers Hari Krishnan
> >
> >
> >
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