RFR: 8186670: Implement _onSpinWait() intrinsic for AArch64 [v4]

[Andrew Haley]

On Thu, 23 Sep 2021 08:38:05 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> Evgeny Astigeevich has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Move spin_wait in cpp file with removal of loop macro
>>   
>>   In addition, comments are added to a checking method of a test.
>
> src/hotspot/cpu/aarch64/vm_version_aarch64.cpp line 60:
> 
>> 58:     }
>> 59:     s += 1;
>> 60:   }
> 
> Suggestion:
> 
>   while (isdigit(*s++));
>   count = atoi(OnSpinWaitImpl);

As far as I know, this combination of digits and named option is unusual in HotSpot; it may be unique. For the sake of not doing something so unfamiliar to our users, it may be worth separating the count and the option string.

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