RFR: 8305895: Implement JEP 450: Compact Object Headers (Experimental) [v18]

[Thomas Stuefe]

On Tue, 17 Sep 2024 10:36:58 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

>> Roman Kennke has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 57 commits:
>> 
>>  - fix CompressedClassPointersEncodingScheme yet again for linux aarch64
>>  - Fixes post-8340184
>>  - Merge upstream up to and including 8340184
>>  - Merge remote-tracking branch 'origin/master' into JDK-8305895-v4
>>  - Fix  test/hotspot/jtreg/runtime/CompressedOops/CompressedClassPointersEncodingScheme.java
>>  - Fix loop on aarch64
>>  - clarify obscure assert in metasapce setup
>>  - Rework compressedklass encoding
>>  - remove stray debug output
>>  - Fixes post 8338526
>>  - ... and 47 more: https://git.openjdk.org/jdk/compare/7849f252...28a26aed
>
> test/hotspot/gtest/metaspace/test_clms.cpp line 193:
> 
>> 191: 
>> 192:       {
>> 193:         // Nonclass arena allocation.
> 
> The style in this source file isn't really up to scratch, especially *these* lines. Anyway, it's in the tests, so I'm OK with this being fixed in a follow up RFE.

Okay, will fix

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PR Review Comment: https://git.openjdk.org/jdk/pull/20677#discussion_r1766686807