RFR: JDK-8307810: Consistently use LockingMode instead of UseHeavyMonitors

[Thomas Stuefe]

On Wed, 10 May 2023 11:20:16 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> [JDK-8291555](https://bugs.openjdk.org/browse/JDK-8291555) phased out UseHeavyMonitors in favor of LockingMode=0. We forgot to apply these changes to PPC and S390. 
> 
> Since UseHeavyMonitors implies LockingMode, but not vice versa, we now have a mismatch if JVM is started with LockingMode=0 but without UseHeavyMonitors. That leads to crashes.
> 
> The patch fixes that, and in addition makes sure that if LockingMode=0 is set, we are setting UseHeavyMonitors too.

Okay, I removed the setting-of-UseHeavyMonitors. We deprecated it in favour of LockingMode=0, and it is a develop flag now. I originally wanted to synchronize UseHeavyMonitors with LockingMode, but doing this only for debug makes no sense, and in release builds UseHeavyMonitors is const false.

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PR Comment: https://git.openjdk.org/jdk/pull/13900#issuecomment-1542154037