RFR: 8242440: use separate, destroyable JavaVM instances per libgraal compiler thread [v4]

[Doug Simon]

On Fri, 22 Apr 2022 11:30:15 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

>> Doug Simon has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   avoid resource allocation in JVMCIRuntime::release_and_clear_globals
>
> src/hotspot/share/jvmci/vmStructs_jvmci.cpp line 412:
> 
>> 410:   declare_constant(JVM_ACC_FIELD_STABLE)                                  \
>> 411:   declare_constant(JVM_ACC_FIELD_HAS_GENERIC_SIGNATURE)                   \
>> 412:   declare_constant(JVM_ACC_IS_VALUE_BASED_CLASS)                          \
> 
> This looks Valhalla specific, why is it added here?

This is needed to fix a Graal-specific regression on `DiagnoseSyncOnValueBasedClasses`.
It's a shame that there's no way to automatically iterate over all `JVM_ACC*` values in vmstructs.

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PR: https://git.openjdk.java.net/jdk/pull/8262