RFR: 8321371: SpinPause() not implemented for bsd_aarch64/macOS [v3]

[Aleksey Shipilev]

On Thu, 21 Dec 2023 17:52:01 GMT, Fredrik Bredberg <fbredberg at openjdk.org> wrote:

>> The SpinPause() function only returns 0 on bsd_aarch64 (i.e. macOS)
>> 
>> This PR implements SpinPause() for MacOS on AArch64 and makes it possible to choose between none, nop, isb and yield by using the OnSpinWaitInst option. The same functionality is found on AArch64 based Linux platforms.
>> 
>> Tested successfully on macosx-aarch64 tier1-tier5.
>
> Fredrik Bredberg has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Updated after review

All right, this one is pretty wild, but I somehow like it.

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Marked as reviewed by shade (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/16994#pullrequestreview-1809028712