RFR (S): 8191888: Refactor ClassLoaderData::remove_handle to use the Access API

[Thomas Schatzl]

Hi,

On Mon, 2017-11-27 at 10:06 +0100, Erik Österlund wrote:
> Hi,
> 
> The ClassLoaderData::remove_handle() member function currently uses 
> explicit G1 SATB barriers to remove an oop from the root set, as
> these handles are not necessarily walked by the GC in a safepoint.
> Therefore G1 needs pre-write barriers.
> 
> This should now be modeled as a 
> RootAccess<IN_CONCURRENT_ROOT>::oop_store instead. This maps to 
> performing a pre-write SATB barrier with G1, but other GCs are free
> to do other things as necessary.
> 
> Webrev:
> http://cr.openjdk.java.net/~eosterlund/8191888/webrev.00/
> 
> Bug:
> https://bugs.openjdk.java.net/browse/JDK-8191888

  looks good.

Thomas