RFR: 8252847: Optimize primitive arrayCopy stubs using AVX-512 masked instructions [v5]

[Nils Eliasson]

On Tue, 22 Sep 2020 15:55:11 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> Summary:
>> 
>> 1)  New AVX3 optimized stubs for both conjoint and disjoint arraycopy.
>> 2)  Special instruction sequence blocks for copy sizes b/w 32-192 bytes.
>> 3)  Block copy operation above 192 bytes is performed using destination address aligned PRE-MAIN-POST loop. Main loop
>> copies 192 byte in one iteration and tail part fall over special instruction sequence blocks. 4)  Both small copy block
>> and aligned loop use 32 byte vector register to prevent and frequency penalty for copy sizes less than AVX3Threshold.
>> 5)  For block size above AVX3Theshold both special blocks and loop operate using 64 byte register. 6)  In case user
>> sets the maximum vector size to 32 bytes, forward copy (disjoint) operations are done using efficient REP MOVS for copy
>> sizes above 4096 bytes.  JMH Results:
>>   System     :  CascadeLake Server, Intel(R) Xeon(R) Platinum 8280L CPU @ 2.70GHz
>>   Micros     :  test/micro/org/openjdk/bench/java/lang/ArrayCopy*.java
>>   Baseline   :  [http://cr.openjdk.java.net/~jbhateja/8252847/JMH_results/ArrayCopy_AVX3_Stubs_Baseline.txt]()
>>   WithOpt  :  [http://cr.openjdk.java.net/~jbhateja/8252847/JMH_results/ArrayCopy_AVX3_Stubs_WithOpts.txt]()
>
> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
> 
>   8252847 : Modifying file permission to resolve jcheck failure.

Looks good to me!

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Marked as reviewed by neliasso (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/61