RFR: 8274299: Make Method/Constructor/Field accessors @Stable

[Peter Levart]

On Mon, 27 Sep 2021 17:31:50 GMT, Mandy Chung <mchung at openjdk.org> wrote:

> Looks good to me. Very nice performance improvement.
> 
> One minor comment: I think the change in `UnsafeFieldAccessorImpl.java` and `UnsafeStaticFieldAccessorImpl.java` isn't necessary since they're final fields. It can be reverted.

There are two changes in `UnsafeFieldAccessorImpl.java` and `UnsafeStaticFieldAccessorImpl.java`. One is making `fieldOffset` and `base` (for static fields) @Stable and the other is moving `field` one level up to `FieldAccessorImpl` and making it @Stable. This later change is not necessary for this patch, but I noticed that you did that in JEP 416 so that `field` is common to all subclasses of `FieldAccessorImpl` including those that you are adding in JEP 416. I can undo this later change. But making fields @Stable does improve performance since `jdk.internal.reflect` and `java.lang.reflect` are not final-field-trusted packages as you noted above. If JEP 416 makes them trusted, it can also remove the @Stable annotations. But for backporting, they better stay there. WDYT?

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PR: https://git.openjdk.java.net/jdk/pull/5694