RFR: 8305895: Implement JEP 450: Compact Object Headers (Experimental) [v30]

[Roman Kennke]

On Mon, 7 Oct 2024 08:25:55 GMT, Stefan Karlsson <stefank 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 76 commits:
>> 
>>  - Merge remote-tracking branch 'rkennke/JDK-8305895-v4' into JDK-8305895-v4
>>  - Revert "Disable TestSplitPacks::test4a, failing on aarch64"
>>    
>>    This reverts commit 059b1573db26d1d2902ca6dadc8413f445234c2a.
>>  - Simplify object init code in interpreter
>>  - Disable some vectorization tests that fail with +UCOH and UseSSE<=3
>>  - Fix for CDSPluginTest.java
>>  - Merge tag 'jdk-24+18' into JDK-8305895-v4
>>    
>>    Added tag jdk-24+18 for changeset 19642bd3
>>  - Disable TestSplitPacks::test4a, failing on aarch64
>>  - @robcasloz review comments
>>  - Improve CollectedHeap::is_oop()
>>  - Allow LM_MONITOR on 32-bit platforms
>>  - ... and 66 more: https://git.openjdk.org/jdk/compare/19642bd3...8742f3c1
>
> src/hotspot/share/oops/compressedKlass.cpp line 28:
> 
>> 26: #include "logging/log.hpp"
>> 27: #include "memory/metaspace.hpp"
>> 28: #include "oops/klass.hpp"
> 
> Is this include really needed or could this be reverted klass.hpp? If it is needed is should be moved to after compressedKlass.inline.hpp.

I don't think it's needed. I'll remove it.

> src/hotspot/share/oops/compressedKlass.cpp line 31:
> 
>> 29: #include "oops/compressedKlass.inline.hpp"
>> 30: #include "runtime/globals.hpp"
>> 31: #include "runtime/java.hpp"
> 
> Do you remember why this was added?

Looks like this is for vm_exit_during_initialization().

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PR Review Comment: https://git.openjdk.org/jdk/pull/20677#discussion_r1789996985
PR Review Comment: https://git.openjdk.org/jdk/pull/20677#discussion_r1789999402