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

[Evgeny Astigeevich]

On Sat, 18 Sep 2021 09:36:25 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> src/hotspot/cpu/aarch64/aarch64.ad line 14368:
>> 
>>> 14366:         for (unsigned int i = 1; i < VM_Version::pause_impl_desc().inst_count(); ++i) {
>>> 14367:           $$emit$$"\tisb\n"
>>> 14368:         }
>> 
>> The code to generate n copies of a pause_impl instruction would be much happier in the MacroAssembler.
>
> So, lose all the code here in C2 and push it down into a single macro.

Done

-------------

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