RFR: 8283726: x86_64 intrinsics for compareUnsigned method in Integer and Long

[Quan Anh Mai]

On Fri, 10 Jun 2022 00:05:53 GMT, Sandhya Viswanathan <sviswanathan at openjdk.org> wrote:

>> I have added a benchmark for the intrinsic. The result is as follows, thanks a lot:
>> 
>>                                                     Before          After
>>     Benchmark                 (size)  Mode  Cnt  Score   Error  Score   Error  Units
>>     Integers.compareUnsigned     500  avgt   15  0.527 ± 0.002  0.498 ± 0.011  us/op
>>     Longs.compareUnsigned        500  avgt   15  0.677 ± 0.014  0.561 ± 0.006  us/op
>
> @merykitty Could you please also add the micro benchmark where compareUnsigned result is stored directly in an integer and show the performance of that?

Thanks @sviswa7 for the suggestion, the results of getting the value of `compareUnsigned` directly is as follow:

                                                           Before          After
    Benchmark                       (size)  Mode  Cnt   Score   Error  Score   Error  Units
    Integers.compareUnsignedDirect     500  avgt   15   0.639 ± 0.022  0.626 ± 0.002  us/op
    Longs.compareUnsignedDirect        500  avgt   15   0.672 ± 0.011  0.609 ± 0.004  us/op

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PR: https://git.openjdk.org/jdk/pull/9068