<i18n dev> Integrated: 8373392: Replace CDS object subgraphs with @AOTSafeClassInitializer

[Ioi Lam]

On Wed, 10 Dec 2025 09:31:37 GMT, Ioi Lam <iklam at openjdk.org> wrote:

> In legacy CDS, Java objects used by certain classes are computed ahead of time using "object subgraphs"
> 
> https://github.com/openjdk/jdk/blob/1bbbce75c5e68429c2a32519eb3c36d964dcdf57/src/hotspot/share/cds/heapShared.cpp#L168-L171
> 
> Examples of subgraphs:
> 
> - `java.lang.Integer$IntegerCache::cache`
> - `jdk.internal.module.ArchivedBootLayer::bootLayer`
> 
> The implementation requires special code (in both Java and C++) to be executed when a CDS archive is created or loaded. As a result, we have an execution model that's difficult to implement/extend and the behavior is hard to understand.
> 
> To move towards the AOT Cache Snapshot Model ([JDK-8365645](https://bugs.openjdk.org/browse/JDK-8365645)) we should replace the subgraphs with the use of `@AOTSafeClassInitializer`, and if necessary, `@AOTRuntimeSetup`. This will simplify the current implementation, and make it possible to extend AOT-initializations to more core classes.
> 
> Note, the use of `@AOTSafeClassInitializer` requires `-XX:+AOTClassLinking`. For the time being, we retain the old CDS object subgraph code to cover the `-XX:-AOTClassLinking` cases. Such code will be marked with comments like `/* Legacy CDS archive support (to be deprecated) */`. All future AOT creation of Java objects will be done with  `@AOTSafeClassInitializer`.

This pull request has now been integrated.

Changeset: 232b41b2
Author:    Ioi Lam <iklam at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/232b41b2227bc9d03d88d316aa28d0cbe87086f7
Stats:     642 lines in 30 files changed: 406 ins; 186 del; 50 mod

8373392: Replace CDS object subgraphs with @AOTSafeClassInitializer

Reviewed-by: liach, heidinga

-------------

PR: https://git.openjdk.org/jdk/pull/28736