RFR 8038797: JVMTI FollowReferences does not report roots reachable from nmethods

[Coleen Phillimore]

On 8/11/16 2:32 PM, dean.long at oracle.com wrote:
> Can you make it work for any CompiledMethod and not just nmethods?

Dean, I tried to do this but CompiledMethod didn't have any oops_do 
function.
>
> I believe oops_do() also picks up klass_holder() oops that were added 
> to keep metadata references alive.

Yes, it does.

> So for those you will most likely get a ClassLoader and not the Class 
> object.  To get the Class object I think you would need to use 
> something like metadata_do(). Does FollowReferences care either way?

No, FollowReferences really wants the oops and you can use the oops to 
find out which Class objects (java.lang.Class) and ClassLoaders are 
alive.   FollowReferences doesn't follow any metadata for anything.

Coleen

>
> dl
>
> On 8/11/16 10:44 AM, Coleen Phillimore wrote:
>> Summary: Also follow nmethods found on the execution stack.
>>
>> I have this fix to follow nmethods found on the execution stack but 
>> not really a good way to test it.  There are two tests internally 
>> that exercise this code and with some printing, I verified that they 
>> do the right thing.   I am open to suggestions how to test this, it 
>> requires compiled methods on the stack with oops that are only 
>> referenced from said methods in the oop section (not in locals or on 
>> stack).
>>
>> Also ran the tonga colocated/non-colocated internal tests, 
>> jdk/test/com/sun/jdi.
>>
>> scp -r /home/cphillim/home/public_html/webrev/8038797.01 
>> coleenp at cr.openjdk.java.net:
>> open webrev at http://cr.openjdk.java.net/~coleenp/8038797.01/webrev
>>
>>
>> thanks,
>> Coleen
>