RFR: 8186670: Implement _onSpinWait() intrinsic for AArch64 [v2]

[Andrew Haley]

On Tue, 21 Sep 2021 12:38:50 GMT, Evgeny Astigeevich <github.com+42899633+eastig at openjdk.org> wrote:

>> `-XX:+PrintAssembly`
>
> To have assembly instructions in `-XX:+PrintAssembly` output `hsdis` needs to be provided:
> 
>   0x0000ffff61ba2b5c: ;   {metadata({method} {0x0000000800466ab8} 'isLatin1' '()Z' in 'java/lang/String')}
>   0x0000ffff61ba2b5c: 0857 8dd2 | c808 a0f2 | 0801 c0f2 | e807 00f9
>  ;; 0xFFFFFFFFFFFFFFFF
>   0x0000ffff61ba2b6c: 0800 8092 | e803 00f9
> 
>   0x0000ffff61ba2b74: ;   {runtime_call counter_overflow Runtime1 stub}
> 
> 
>  However it can help to skip to the place where instructions are expected and to check instructions' hex code.

True. There's no C1 equivalent.

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PR: https://git.openjdk.java.net/jdk/pull/5562