RFR: 8261553: Efficient mask generation using BMI2 BZHI instruction [v2]

[Jatin Bhateja]

On Thu, 11 Feb 2021 10:28:05 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   8261553: Adding BMI2 missing check for partial in-lining.
>
> - Rather than removing the old code, I believe the code calling bzhiq needs to be in a branch checking `VM_Version::supports_bmi2`. Otherwise you'll hit asserts on older hardware without this extension
> - Some demonstration of the performance benefit would be nice - either a new microbenchmark or a statistically significant result running some existing ones, e.g. `make test TEST=micro:ArrayCopy`

Hi Claes,

Here is the JMH performance data over CLX for arraycopy benchmarks:
http://cr.openjdk.java.net/~jbhateja/8261553/JMH_PERF_CLX_BASELINE.txt
http://cr.openjdk.java.net/~jbhateja/8261553/JMH_PERF_CLX_WITH_OPTS.txt

Regards,
Jatin

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PR: https://git.openjdk.java.net/jdk/pull/2522