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

Tue Nov 9 15:47:53 UTC 2021

On Tue, 9 Nov 2021 13:25:50 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.

Seems fine to me, although I agree that adding another value to `MarkForDeoptimizationStatus` would look cleaner and make more sense if it were possible. I don't know the answer to that.

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Marked as reviewed by rpressler (Lead).

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