<i18n dev> RFR: 8373392: Replace CDS object subgraphs with @AOTSafeClassInitializer [v3]

[Chen Liang]

On Wed, 17 Dec 2025 20:04:48 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`.
>
> Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fixed test case -- the regexp pattern could match the stats for the subgraphs table, which now has a single entry

The new tests look fine to me.

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Marked as reviewed by liach (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/28736#pullrequestreview-3589877162