RFR: 8352003: Support --add-opens with -XX:+AOTClassLinking [v3]

[Calvin Cheung]

On Mon, 21 Apr 2025 18:39:39 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> Calvin Cheung has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   @iklam comment
>
> src/java.base/share/classes/jdk/internal/module/ModuleBootstrap.java line 165:
> 
>> 163:             BootLoader.getUnnamedModule(); // trigger <clinit> of BootLoader.
>> 164:             CDS.defineArchivedModules(ClassLoaders.platformClassLoader(), ClassLoaders.appClassLoader());
>> 165:             boolean extraExportsOrOpens = addExtraExportsAndOpens(bootLayer);
> 
> (1) The returned value of `addExtraExportsAndOpens()` is not used. So I think this function can be changed to `void`, and all occurrences of the local variable `extraExportsOrOpens` can be removed.
> 
> (2) I traced the code paths that depend on the effects of `--add-opens` and `--add-exports`. It Looks like some of the effects are recorded in the `java.lang.Module$ReflectionData::export` table:
> 
> https://github.com/openjdk/jdk/blob/684d3b336e9cb31707d35e75f9b785e04e1fdbee/src/java.base/share/classes/java/lang/Module.java#L398C2-L412
> 
> 
>         /**
>          * A module (1st key) exports or opens a package to another module
>          * (2nd key). The map value is a map of package name to a boolean
>          * that indicates if the package is opened.
>          */
>         static final WeakPairMap<Module, Module, Map<String, Boolean>> exports =
>             new WeakPairMap<>();
> 
> 
> This table is *not* stored as part of the `ArchivedBootLayer`, so we must re-initialize this table in the production run. @AlanBateman could you confirm that this is correct.
> 
> Eventually, we should enhance the `ArchivedBootLayer` to also include the tables in `Module$ReflectionData`. That will obviate the call to `addExtraExportsAndOpens()` and save a few bytecodes during start-up (but the overall impact would be small, so it's not critical in the current PR). Because these tables use WeakReference, we need to wait for [JDK-8354897](https://bugs.openjdk.org/browse/JDK-8354897).

Fixed (1) above.

> test/hotspot/jtreg/runtime/cds/appcds/jigsaw/modulepath/AddOpens.java line 109:
> 
>> 107:                             "--add-opens", addOpensArg,
>> 108:                             "--module-path", moduleDir.toString(),
>> 109:                             "-m", TEST_MODULE1, "with_add_opens")
> 
> Could you add a test case for `=ALL-UNNAMED` as well? That is frequently used by applications, and it takes a different code path inside the implementation.
> 
> I think this can be done by running `com.simple.Main` in the classpath rather than module path.

Added the test case.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24695#discussion_r2053082635
PR Review Comment: https://git.openjdk.org/jdk/pull/24695#discussion_r2053082907