RFR: 8293922: Extend barrier-less Java thread transitions to native transitions

[Robbin Ehn]

On Fri, 16 Sep 2022 10:01:18 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

> As suggested by @TheRealMDoerr, avoid the fence for native trans when UseSystemMemoryBarrier is enabled.
> 
> Locally I can see methods like Thread.holdsLock() getting a 4 ns speed boost, (~20% faster).
> 
> Running t1-5 with UseSystemMemoryBarrier on.

Thanks, great.

But since you bring it up. We should use correct accessors for _thread_state.
Fixed that, please have a second look @TheRealMDoerr.

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PR: https://git.openjdk.org/jdk/pull/10302