RFR: 8365191: Cleanup after removing LockingMode related code

[Fredrik Bredberg]

On Tue, 23 Sep 2025 09:29:57 GMT, Fredrik Bredberg <fbredberg 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.

@bulasevich, @TheRealMDoerr, @RealFYang, @offamitkumar
I've run rudimentary tests using QEMU, but it would be nice if you guys (or any of your friends) could take it for a spin on real hardware. Thanks in advance.

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PR Comment: https://git.openjdk.org/jdk/pull/27448#issuecomment-3323970915