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

Rifat,

When I add in the constraints class to return true for the specified
method, the rvm when executing is giving a seg fault.


Cheers
Hari


On Tue, Jan 14, 2014 at 12:16 AM, Rifat Shahriyar <
[email protected]> wrote:

>  You need to set the constraint needsObjectReferenceReadBarrier() to
> true. Look at PoisonedConstraints.
>
> Regards
> -
> Rifat
>
>
> On 14/01/2014 5:11 pm, Hari Krishnan wrote:
>
> Robin,
>
>  Thank you. I am looking at that code.  When I override
> objectReferenceRead it seems like it is never called. I am trying to
> understand how it works. Is there anything I have to do other than
> overriding that in my mutator class?
>
>  Cheers
> Hari Krishnan.
>
>
> On Mon, Jan 13, 2014 at 11:47 PM, Robin Garner <[email protected]>wrote:
>
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>>  The MMTk plan "poisoned" unconditionally sets and clears the low-order
>> bit of all object references - this is the regression test for object
>> read and write barriers.
>>
>> cheers
>>
>> On 14/01/14 15:53, Hari Krishnan wrote:
>> > 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] <mailto:[email protected]>> wrote:
>> >
>> > 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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