RFR: 8210063: ZGC: Enable load barriers for IN_NATIVE runtime barriers

[Per Liden]

On 08/28/2018 01:03 PM, Erik Österlund wrote:
> Hi,
> 
> In an effort to scan more (strong) root sets concurrently, we need to 
> support IN_NATIVE oops not being fixed up in safepoints. Both the 
> ZBarrierSetAssembler, ZBarrierSetC1 and ZBarrierSetC2 already have 
> IN_NATIVE load barriers on for all strong oops. However, ZBarrierSet 
> does not yet enable it. I propose to enable it so we can scan more 
> things concurrently.
> 
> Webrev:
> http://cr.openjdk.java.net/~eosterlund/8210063/webrev.00/

Looks good. I think we should also add an 
verify_decorators_absent<ON_UNKNOWN_OOP_REF>(), like we do in "in_heap" 
version of oop_load. If nothing else, just to keep these in sync with 
each other.

/Per

> 
> Bug:
> https://bugs.openjdk.java.net/browse/JDK-8210063
> 
> Thanks,
> /Erik