RFR: 8316994: Avoid modifying ClassLoader and Module objects during -Xshare:dump

[Ioi Lam]

On Wed, 27 Sep 2023 21:16:19 GMT, Matias Saavedra Silva <matsaave at openjdk.org> wrote:

>> When dumping the module graph, we set some native pointers in `ClassLoader` and `Module` objects to null.
>> 
>> We used to modify the copies of these objects in the actual heap. This makes `InstanceKlass::class_loader_data()` return the wrong value inside `VM_PopulateDumpSharedSpace`.
>> 
>> Instead, this PR modifies the copies of the objects in the `ArchiveHeapWriter` buffer. This also means that the `HeapShared::restore_loader_data()` function is no longer needed.
>
> LGTM! Thanks for this improvement

Thanks @matias9927 and @calvinccheung for the review.
Passed tiers 1~4

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PR Comment: https://git.openjdk.org/jdk/pull/15937#issuecomment-1738324091