RFR: 8305895: Implement JEP 450: Compact Object Headers (Experimental) [v8]

[Stefan Karlsson]

On Mon, 9 Sep 2024 12:17:17 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

>> Roman Kennke has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - Try to avoid lea in loadNklass (aarch64)
>>  - Fix release build error
>
> src/hotspot/share/oops/oop.cpp line 230:
> 
>> 228:   // disjunct below to fail if the two comparands are computed across such
>> 229:   // a concurrent change.
>> 230:   return Universe::heap()->is_stw_gc_active() && klass->is_objArray_klass() && is_forwarded() && (UseParallelGC || UseG1GC);
> 
> Is this still true after the recent changes like JDK-8311163? It might be worth waiting for.

That bug doesn't fix all cases where the the length field is modified.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20677#discussion_r1758477168