RFR: 8374145: Remove legacy locking remnants from markWord

[Stefan Karlsson]

On Fri, 19 Dec 2025 14:16:25 GMT, Stefan Karlsson <stefank at openjdk.org> wrote:

>> src/hotspot/share/gc/shenandoah/shenandoahHeap.inline.hpp line 349:
>> 
>>> 347:   } else if (w.is_being_inflated() || w.has_displaced_mark_helper()) {
>>> 348:     // Informs caller that we aren't able to determine the age
>>> 349:     return markWord::max_age + 1; // sentinel
>> 
>> Not sure if we want an `!w.has_displaced_mark_helper()` assert. Even if we already check  for (and handled) the exact conditions (in the current implementation) for `has_displaced_mark_helper()`.
>
> That would work for me. I'll wait for input from the Shenandoah devs.

In the interest to get this integrated I've created an Enh for this:
https://bugs.openjdk.org/browse/JDK-8374191

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PR Review Comment: https://git.openjdk.org/jdk/pull/28927#discussion_r2639248718