RFR: 8204474: Have instanceRefKlass use HeapAccess when loading the referent

[Per Liden]

Thanks!

/Per

On 06/07/2018 09:42 AM, Stefan Karlsson wrote:
> Looks good.
> 
> StefanK
> 
> On 2018-06-06 16:16, Per Liden wrote:
>> Hi,
>>
>> To support concurrent reference processing in ZGC, 
>> instanceRefKlass::try_discover() can no longer use RawAccess to load 
>> the referent field. Instead it should use
>>
>>    HeapAccess<ON_PHANTOM_OOP_REF | AS_NO_KEEPALIVE>
>>
>> or
>>
>>    HeapAccess<ON_WEAK_OOP_REF | AS_NO_KEEPALIVE>
>>
>> depending on the reference type. This patch also adjusts 
>> InstanceRefKlass::trace_reference_gc() for the same reason.
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8204474
>> Webrev: http://cr.openjdk.java.net/~pliden/8204474/webrev.0
>>
>> Testing: This patch has been part of the ZGC repository for quite some 
>> time and gone through various testing, including tier{1,2,3,4,5,6} in 
>> mach5.
>>
>> /Per