RFR: 8338383: Implement JEP 491: Synchronize Virtual Threads without Pinning [v12]

[Dean Long]

On Mon, 28 Oct 2024 16:39:14 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> src/hotspot/cpu/aarch64/stackChunkFrameStream_aarch64.inline.hpp line 119:
>> 
>>> 117:   return  mask.num_oops()
>>> 118:         + 1 // for the mirror oop
>>> 119:         + (f.interpreter_frame_method()->is_native() ? 1 : 0) // temp oop slot
>> 
>> Where is this temp oop slot set and used?
>
> It's the offset of the mirror passed to static native calls.  It pre-existed saving the mirror in all frames to keep the Method alive, and is duplicated.  I think this could be cleaned up someday, which would remove this special case.

I tried to track down how interpreter_frame_num_oops() is used, and as far as I can tell, it is only used to compare against the bitmap in debug/verify code.  So if this slot was added here, shouldn't there be a corresponding change for the bitmap?

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PR Review Comment: https://git.openjdk.org/jdk/pull/21565#discussion_r1819687576