RFR: 8366671: Refactor Thread::SpinAcquire and Thread::SpinRelease [v12]

[David Holmes]

On Thu, 4 Dec 2025 12:33:02 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> src/hotspot/share/utilities/spinCriticalSection.hpp line 46:
>> 
>>> 44:   // compared to  smaller/larger types.
>>> 45:   volatile int* const _lock;
>>> 46:   DEBUG_ONLY(NoSafepointVerifier _nsv;)
>> 
>> I thought NSV had to be used as a StackObj ?? I don't understand why it is a field of SCS.
>
> It can be a field of a StackObj too.

Okay, yes I misunderstand the purpose here. We want the NSV covering the critical section, not just the code of the SCS.

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PR Review Comment: https://git.openjdk.org/jdk/pull/28264#discussion_r2590322392