RFR: 8291555: Implement alternative fast-locking scheme [v29]

[Roman Kennke]

On Fri, 24 Mar 2023 06:39:18 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Roman Kennke has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - Merge remote-tracking branch 'origin/JDK-8291555-v2' into JDK-8291555-v2
>>  - Set condition flags correctly after fast-lock call on aarch64
>
> src/hotspot/share/runtime/synchronizer.cpp line 516:
> 
>> 514:       // No room on the lock_stack so fall-through to inflate-enter.
>> 515:     } else {
>> 516:       markWord mark = obj->mark();
> 
> why is it `mark` here but `header` above?

Oh I don't know. We are very inconsistent in our nomenclature here and use mark in some places and header in some others (e.g. OM::set_header() or the displaced_header() methods). The name mark is not really fitting and only still exists for historical reasons I believe (when one of the primary functions of the object header is to indicate GC marking?) However, the central data type is still called markWord so I changed my new code paths to use *mark as well. This probably warrants a round of codebase cleanup and consolidation later.

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PR Review Comment: https://git.openjdk.org/jdk/pull/10907#discussion_r1149630607