RFR: Add flag to prevent multiple deopts on the same nmethod. [v3]

[Rickard Bäckman]

On Tue, 9 Nov 2021 20:22:37 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> I added a flag to prevent the same nmethod from being optimized multiple times.  It might be better to have a new MarkForDeoptimizationStatus enum but wasn't sure how that would interact with the deoptimize_update state.  Advice welcome.
>> I also don't know why the sweeper is so slow to get rid of these entries.
>> This makes ctw_2 test run in an hour on my machine, just like mainline jdk/jdk (machine is slow!) in fastdebug.
>
> Coleen Phillimore has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:
> 
>  - Merge branch 'fibers' into ctw
>  - This is better imo.
>  - Add flag to prevent multiple deopts on the same nmethod.

Looks good.

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Marked as reviewed by rbackman (Committer).

PR: https://git.openjdk.java.net/loom/pull/81