[lworld] RFR: object methods in VM for lworld value type (locked mark word edition)

John Rose john.r.rose at oracle.com
Mon May 21 22:31:09 UTC 2018


Good deal. We might use this in the future to build in other mode bits for other states, such as frozen, confined, and larval. All of those are disjoint from states where an object monitor is lockable.

Is the Class.isVT test still cheap?

> On May 21, 2018, at 5:02 AM, David Simms <david.simms at oracle.com> wrote:
> 
> 
> So take 2, now with "markOopDesc::is_always_locked()".
> 
> http://cr.openjdk.java.net/~dsimms/valhalla/object_methods/webrev2/
> 
> 
> Functionality is the same as previous patches, with John's comments applied (default VM hash is klass mirror hash code, not zero). I went to the trouble of encoding mark word as always locked. I realized it was not completely trivial, and requires some explanation as to why I went with the pattern I did...
> 



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