RFR: 8351655: Optimize ObjectMonitor::unlink_after_acquire() [v2]

[Fredrik Bredberg]

On Thu, 20 Mar 2025 16:34:29 GMT, Patricio Chilano Mateo <pchilanomate at openjdk.org> wrote:

>> Fredrik Bredberg has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Update after review
>
> src/hotspot/share/runtime/objectMonitor.cpp line 1258:
> 
>> 1256: // entry_list can be in any of these forms:
>> 1257: //   1. Only singly linked.
>> 1258: //   2. Only doubly linked.
> 
> This case should also never happen. If the whole list is already fully doubly linked we would not call this.

Rewrote the comment.

> src/hotspot/share/runtime/objectMonitor.cpp line 1287:
> 
>> 1285:     // into a doubly linked list. Now we just need to set the tail
>> 1286:     // pointer.
>> 1287:     assert(prev == nullptr || prev->next() == nullptr, "invariant");
> 
> Since empty list is not possible instead of `prev == nullptr ||` this should be `prev != nullptr &&`.

Fixed

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

PR Review Comment: https://git.openjdk.org/jdk/pull/24078#discussion_r2007164136
PR Review Comment: https://git.openjdk.org/jdk/pull/24078#discussion_r2007163432