RFR: 8199328: Fix unsafe field accesses in heap dumper

[Aleksey Shipilev]

On 03/08/2018 03:19 PM, Thomas Schatzl wrote:
> On Thu, 2018-03-08 at 15:01 +0100, Per Liden wrote:
>> The heap dumper, more specifically the
>> DumperSupport::dump_field_value() 
>> function, is doing unsafe raw loads of fields in heap objects. Those 
>> loads should go thru the access API.
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8199328
>> Webrev: http://cr.openjdk.java.net/~pliden/8199328/webrev.0/
>>
>> Testing: manual dumping using jcmd GC.heap_dump, awaiting hs-tier1-3
>> results
> 
>   I think this is good, but somebody else should also look into this as
> making sure that the right invariants hold for all collectors is
> tricky.

This looks fine to me, given my cursory understanding of Access API,
and following through where the new calls end up in Shenandoah barrier set. Our
gc/shenandoah/jvmti/TestHeapDump.java test that used to find troubles in this
code is also happy with this change applied.

Thanks,
-Aleksey