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

Rifat,

The seg fault is thrown for poisoned implementation also. Not just for my
implementation. I hope you can let me know why  this is happening.  Thank
you.


On Tue, Jan 14, 2014 at 12:55 AM, Hari Krishnan <[email protected]>wrote:

> 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:
>>
>>> -----BEGIN PGP SIGNED MESSAGE-----
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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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