Integrated: 8297914: Remove java_lang_Class::process_archived_mirror()

[Ioi Lam]

On Wed, 4 Jan 2023 21:01:28 GMT, Ioi Lam <iklam at openjdk.org> wrote:

> This is another prerequisite for [JDK-8296344](https://bugs.openjdk.org/browse/JDK-8296344).
> 
> Before this PR, when archiving mirror objects (i.e., instances of `java.lang.Class`):
> - We first allocate a copy of the mirror inside a safepoint. 
> - We then reinitialize the contents of the copy to the desired state (so that it can be used by `Klass::restore_unshareable_info()`
> 
> This copy-and-modify operation inside the safepoint makes it difficult to implement [JDK-8296344](https://bugs.openjdk.org/browse/JDK-8296344). It violates the requirements [1] and [2] as stated in [JDK-8298600](https://bugs.openjdk.org/browse/JDK-8298600). Also, the reinitialization code is complicated.
> 
> After this PR:
> - During the creation of each regular mirror object, we allocate a "scratch mirror" object, which has the states as expected by `Klass::restore_unshareable_info()`. See `java_lang_Class::create_scratch_mirror()`.
> - When the archive heap is dumped inside a safepoint, we use the scratch mirror, so we can avoid the copy-and-modify operation. See `HeapShared::archive_java_mirrors()`.
> 
> Testing: tiers 1-4

This pull request has now been integrated.

Changeset: 7bcd5f41
Author:    Ioi Lam <iklam at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/7bcd5f418c399678e9459dc376c3ef061493b33f
Stats:     495 lines in 10 files changed: 214 ins; 226 del; 55 mod

8297914: Remove java_lang_Class::process_archived_mirror()

Reviewed-by: ccheung

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PR: https://git.openjdk.org/jdk/pull/11853