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

[Dean Long]

On Fri, 24 Mar 2023 06:15:31 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/oops/oop.cpp line 126:
> 
>> 124:   // Outside of a safepoint, the header could be changing (for example,
>> 125:   // another thread could be inflating a lock on this object).
>> 126:   if (ignore_mark_word || UseFastLocking) {
> 
> Not clear why UseFastLocking appears here instead of in the return expression - especially given the comment above.

I have the same question.  Based on the comment, I would expect
`return !SafepointSynchronize::is_at_safepoint() || UseFastLocking`;

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/10907#discussion_r1149966288