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

[Coleen Phillimore]

On Thu, 12 Sep 2024 16:04:45 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> src/hotspot/cpu/aarch64/compressedKlass_aarch64.cpp line 147:
>> 
>>> 145: #endif
>>> 146: 
>>> 147:   return true;
>> 
>> This should only be in the compressedKlass.cpp file.
>
> Okay. I will remove the whole `CompressedKlassPointers::pd_initialize` logic. We only need it for one architecture (aarch) and one case (+UseCCP -UseCOH), so maybe its not worth fanning out across all platforms, including Zero. Instead, I will add a short `ifdef` section to `CompressedKlassPointers::initialize`.

Yes, looking at this further, it does seem like a small amount of conditional compilation that sets all the same values that are set in the architecture independent version.  It seems best to move it there.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20677#discussion_r1757300544