RFR: 8300926: Several startup regressions ~6-70% in 21-b6 all platforms [v6]

[Daniel D. Daugherty]

On Mon, 27 Feb 2023 00:29:26 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Robbin Ehn has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - Comment fixes
>>  - Include/fwd fixes
>
> In `ciEnv::register_method` we take the `Compile_lock` to ensure `add_to_hierarchy` can't run:
> 
>     // Prevent SystemDictionary::add_to_hierarchy from running
>     // and invalidating our dependencies until we install this method.
>     // No safepoints are allowed. Otherwise, class redefinition can occur in between.
>     MutexLocker ml(Compile_lock);
>     NoSafepointVerifier nsv;
> 
> does moving the deopt outside of the `Compile_lock` affect that?

I've just tried to figure out whether @dholmes-ora's concerns have
been addressed. The last mesgs that I see from David are from
2023.02.26 so about 2 weeks ago, but I can't tell for sure whether
@robehn has addressed those remaining comments or not.

Sorry, but the GitHub UI is really messing me up here.

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PR: https://git.openjdk.org/jdk/pull/12585