RFR: 8365191: Cleanup after removing LockingMode related code

[Yudi Zheng]

On Tue, 23 Sep 2025 17:30:05 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> This is a general cleanup after removing `LockingMode` related code.
>> It's a sub-task of [JDK-8344261](https://bugs.openjdk.org/browse/JDK-8344261).
>> It includes:
>> - Removing asserts that are no longer necessary, since we removed legacy locking and monitor locking.
>> - Removing or rewriting comments, arguments or functions that are related to displaced headers.
>> - Remove "always true" parameter from `MonitorExitStub`.
>> - Re-type/name metadata in `BasicLock`.
>> 
>> Tier1-5 passes okay on supported platforms.
>> 
>> All other platforms (arm, ppc, riscv and s390) has been sanity checked using Qemu.
>
> src/hotspot/share/jvmci/vmStructs_jvmci.cpp line 171:
> 
>> 169:   nonstatic_field(Array<Klass*>,               _data[0],                               Klass*)                                       \
>> 170:                                                                                                                                      \
>> 171:   volatile_nonstatic_field(BasicLock,          _monitor,                               ObjectMonitor*)                               \
> 
> I don't see any references to this in the JVMCI code either.  I assume the compiler/jvmci tests all passed with this change without any change to jvmci code.  Maybe @mur47x111  can confirm.

Correct, I dont think JVMCI tests will be affected. We only use this field (offset) in the actual monitorenter implementation to write ObjectMonitor cache.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27448#discussion_r2375418781