RFR: 8338383: Implement JEP 491: Synchronize Virtual Threads without Pinning [v7]

[Patricio Chilano Mateo]

On Wed, 23 Oct 2024 00:19:23 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Patricio Chilano Mateo has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Minor fixes in inc/dec_held_monitor_count on aarch64 and riscv
>
> src/hotspot/cpu/aarch64/macroAssembler_aarch64.cpp line 5354:
> 
>> 5352:   str(rscratch2, dst);
>> 5353:   Label ok;
>> 5354:   tbz(rscratch2, 63, ok);
> 
> 63?  Does this really need to have underflow checking?  That would alleviate the register use concerns if it didn't.  And it's only for legacy locking which should be stable until it's removed.

I can remove the check. I don't think it hurts either though. Also we can actually just use rscratch1 in the ASSERT case.

> src/hotspot/cpu/riscv/macroAssembler_riscv.cpp line 231:
> 
>> 229: 
>> 230: void MacroAssembler::inc_held_monitor_count(Register tmp) {
>> 231:   Address dst = Address(xthread, JavaThread::held_monitor_count_offset());
> 
> Address dst(xthread, JavaThread::held_monitor_count_offset());

Done.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21565#discussion_r1813516395
PR Review Comment: https://git.openjdk.org/jdk/pull/21565#discussion_r1813519648