RFR: 8298733: Reconsider monitors_on_stack assert [v2]

[Coleen Phillimore]

On Wed, 16 Apr 2025 13:02:58 GMT, Fredrik Bredberg <fbredberg at openjdk.org> wrote:

>> This PR aims to revert this [8298371: monitors_on_stack extracts unprocessed oops](https://github.com/openjdk/jdk/pull/11582) fix at the same time as we retain the ability to assert that we don't have any monitors on the stack when legacy locking is used.
>> 
>> It does so by moving an assert that ensures that we don't have any monitors on the stack to a place where all stack frames should have been processed. I.e. it's safe to check the frame for any monitor.
>> 
>> A new function called assert_frames_in_continuation_are_safe() asserts that the frames has been processed (i.e. it  safe to revert the [8298371](https://github.com/openjdk/jdk/pull/11582) fix). By keeping that assertion functionality separate from monitors_on_stack() we will be able to keep that assertion after we have removed legacy locking.
>> 
>> In order to recreate the original [problem](https://github.com/openjdk/jdk/pull/11582) and verifying that this PR works used, I used:
>> `-XX:LockingMode=1 -XX:+UseZGC -XX:+ZVerifyOops -XX:ZCollectionIntervalMajor=0.001 Fuzz.java
>> `
>> 
>> Also passes tier1-7.
>
> Fredrik Bredberg has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Updated after Patricio's review

Looks good!

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Marked as reviewed by coleenp (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/24655#pullrequestreview-2773238108