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

[Stefan Karlsson]

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