RFR: 8367387: Add @AOTInitialize annotation [v5]

[Chen Liang]

On Fri, 19 Sep 2025 02:10:15 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> This PR adds a new annotation, `@AOTInitialize` that forces a class to be (a) initialized in the AOT assembly phase, and (b) stored in the AOT cache in an already initialized state. This means that all the static fields in this class will be immediately available upon JVM bootstrap when the AOT cache is used in an application's production run.
>> 
>> This PR annotates a single class, `jdk.internal.math.MathUtils` (also the object hierarchy root class, `Object.class`, which has no associated AOT initialization but is required for completeness). More classes will be added in future PRs.
>> 
>> If a class `K` has the `@AOTInitialize` annotation, the same annotation must be also added to
>> - All of `K`'s super classes
>> - All of `K`'s super interfaces that require to be initialized when `K` is initialized (see JVMS 5.5. Initialization, step 7; also C++ function `InstanceKlass::interface_needs_clinit_execution_as_super()`
>> 
>> Note, the check of the above requirement has been moved to `AOTClassInitializer::check_aot_annotations()`. The previous check in `ClassFileParser` was not executed because the class is loaded in the AOT training run, where `CDSConfig::is_initing_classes_at_dump_time()` returns `false` (this function returns `true` only in the AOT assembly phase).
>> 
>> This annotation is awfully similar to `@AOTSafeClassInitializer`, and I am not sure if we need both. Please see the javadoc in `@AOTInitialize` to see the difference between the two annotations.
>
> Ioi Lam has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 23 commits:
> 
>  - Updated requirements for annotations on supertypes for AOTInitialize and AOTSafeClassInitializer
>  - Merge branch 'master' into aot-initialize-math-utils
>  - Added logging about @AOTSafeClassInitializer classes that have not been initialized
>  - Added comment about the order of FinalImageRecipes::apply_recipes() vs link_all_loaded_classes()
>  - Exclude more GC heap size tests as AOT cache size has increased for "make test JTREG=AOT_JDK=onestep ..."
>  - Added javadoc; added test case; code clean up
>  - Merge branch 'master' into aot-initialize-math-utils
>  - cleanup
>  - Merge branch 'master' into aot-initialize-math-utils
>  - Merge branch '8366477-refactor-aot-related-flag-bits-in-klass-hpp' into aot-initialize-math-utils
>  - ... and 13 more: https://git.openjdk.org/jdk/compare/7ec3fa5f...d21bfb12

src/hotspot/share/cds/aotMetaspace.cpp line 1266:

> 1264:     if (HAS_PENDING_EXCEPTION) {
> 1265:       ResourceMark rm;
> 1266:       log_error(aot, init)("class %s has @AOTForceInitialize but failed to initialize",

Suggestion:

      log_error(aot, init)("class %s has @AOTInitialize but failed to initialize",

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PR Review Comment: https://git.openjdk.org/jdk/pull/27024#discussion_r2363651802