RFR: 8304743: Compile_lock and SystemDictionary updates [v2]

[Coleen Phillimore]

On Fri, 31 Mar 2023 21:25:17 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

>> Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Add a utility function for SystemDictionary find.
>
> Looks good. Thanks for taking care of it, Coleen.
> 
> FTR there are other redundant usages of `Compile_lock` in CI code.

There isn't a guarantee that the klasses the compiler finds in the hierarchy are also in the dictionary.  Changing scope of the Compile_lock breaks this guarantee.  In discussions, @iwanowww thinks this race is benign as the klass returned by dependencies might not be in the dictionary (if hidden class for example). Creating an instance requires that the class be in the dictionary so we think Class.forName(this.getClass().getName()) would not be affected since "this" is an instance.

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PR Comment: https://git.openjdk.org/jdk/pull/13270#issuecomment-1492751187