RFR: 8315884: New Object to ObjectMonitor mapping [v15]

[Axel Boldt-Christmas]

On Wed, 14 Aug 2024 20:58:24 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

>> src/hotspot/share/runtime/lightweightSynchronizer.cpp line 341:
>> 
>>> 339: 
>>> 340: ObjectMonitor* LightweightSynchronizer::get_or_insert_monitor_from_table(oop object, JavaThread* current, bool* inserted) {
>>> 341:   assert(LockingMode == LM_LIGHTWEIGHT, "must be");
>> 
>> Do you want to assert: `inserted != nullptr`?
>
> What was the resolution? I don't see a reply or a change here.

_Must have missed pressing Comment_

The assert does not seem necessary, this member function is local to LightweightSynchronizer (private) and it will crash hard if it is called with a bad pointer for the out parameter.

It could have been a reference type here instead. I am not sure what is the best when it comes to out parameters, all styles have pros and cons. We seem to use all different combinations throughout hotspot.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20067#discussion_r1717996898