RFR: 8290234: [JVMCI] use JVMCIKlassHandle to protect raw Klass* values from concurrent G1 scanning

Wed Jul 13 17:34:05 UTC 2022

On Wed, 13 Jul 2022 12:24:50 GMT, Doug Simon <dnsimon at openjdk.org> wrote:

> JVMCI Java code must never read a raw `Klass*` value from memory (using `Unsafe`) that is not already known to be wrapped in a `HotSpotResolvedObjectTypeImpl` without going through a VM call. The VM call is necessary so that the `Klass*` is handlized in a `JVMCIKlassHandle` to protect it from the concurrent scanning done by G1. This PR re-introduces the VM calls that were mistakenly optimized away in [JDK-8289094](https://bugs.openjdk.org/browse/JDK-8289094).

Marked as reviewed by never (Reviewer).

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PR: https://git.openjdk.org/jdk/pull/9480