RFR: 8365190: Remove LockingMode related code from share

[David Holmes]

On Tue, 2 Sep 2025 20:15:51 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Since the integration of [JDK-8359437](https://bugs.openjdk.org/browse/JDK-8359437) the `LockingMode` flag can no longer be set by the user. After that, a number of PRs has been integrated which has removed all `LockingMode` related code from all platforms (except from zero, which is done in this PR).
>> 
>> This PR removes `LockingMode` related code from the shared (non-platform specific) files. It also removes the `LockingMode` variable itself.
>> 
>> Passes tier1-tier5 with no added problems.
>
> src/hotspot/share/runtime/basicLock.hpp line 51:
> 
>> 49:   void set_bad_metadata_deopt() { set_metadata(badDispHeaderDeopt); }
>> 50: 
>> 51:   static int displaced_header_offset_in_bytes() { return metadata_offset_in_bytes(); }
> 
> Also delete line 51 ?

Still appears used in LIRAssembler. But the assert in which it is used doesn't really make sense as it just checks the offset == 0.

> src/hotspot/share/runtime/lightweightSynchronizer.cpp line 769:
> 
>> 767: 
>> 768: // LightweightSynchronizer::inflate_locked_or_imse is used to to get an inflated
>> 769: // ObjectMonitor* when lightweight locking is used. It is used from contexts
> 
> I guess you don't need the phrase "when lightweight locking is used".

Even calling it "lightweight locking" is no longer needed.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27041#discussion_r2320640694
PR Review Comment: https://git.openjdk.org/jdk/pull/27041#discussion_r2320651595