RFR: 8302354: InstanceKlass init state/thread should be atomic

[David Holmes]

On Mon, 13 Feb 2023 18:56:19 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

> Hi, please consider.
> 
> These states are read 'lock-less' should thus be atomic.
> Also the assert setting init thread state can be stricter.
> 
> Passes t1-4

Scratch previous review comments. Use of Atomic::load/store guards against theoretical possibility of non-atomic ptr read/writes. I was confusing with visibility issues. Sorry for the noise.

-------------

Marked as reviewed by dholmes (Reviewer).

PR: https://git.openjdk.org/jdk/pull/12542