RFR: 8320318: ObjectMonitor Responsible thread

[Axel Boldt-Christmas]

On Wed, 11 Sep 2024 00:30:17 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> src/hotspot/cpu/x86/c2_MacroAssembler_x86.cpp line 482:
>> 
>>> 480:   // This is faster on Nehalem and AMD Shanghai/Barcelona.
>>> 481:   // See https://blogs.oracle.com/dave/entry/instruction_selection_for_volatile_fences
>>> 482:   lock(); addl(Address(rsp, 0), 0);
>> 
>> Since there's a membar above, do you need this lock/addl instructions?
>
> Just FTR this is a full fence on x86.

It is not needed. `membar(StoreLoad)` does exactly this.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19454#discussion_r1753184198