RFR: 8360555: Archive all unnamed modules in CDS full module graph

[Coleen Phillimore]

On Wed, 2 Jul 2025 00:18:28 GMT, Ioi Lam <iklam at openjdk.org> wrote:

> The CDS full module graph is supposed to contain a snapshot of the boot layer, which has 3 unnamed modules for the boot, platform and system class loaders. Each unnamed module is represented by a `java.lang.Module` Java object and a `ModuleEntry` C++ object.
> 
> Currently, we archive only the `java.lang.Module` for the platform and system loaders. The other 4 objects are dynamically created in the production run while executing Java bytecodes during VM bootstrap.
> 
> With this PR, we archive all of the above 6 objects when `CDSConfig::is_dumping_full_module_graph()` is true.
> 
> This is required for [JDK-8350550](https://bugs.openjdk.org/browse/JDK-8350550), as we need the `java.lang.Module` object for archived classes in the unnamed module of the boot loader prior to executing any Java code.
> 
> We also archive the `ModuleEntry` objects for the 3 unnamed modules for uniformity, as these objects are already archived for named modules.

The code looks good.

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Marked as reviewed by coleenp (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/26082#pullrequestreview-3039130102