RFR: 8331558: AArch64: optimize integer remainder [v8]

[Eric Liu]

On Thu, 9 May 2024 03:30:04 GMT, Jin Guojie <duke at openjdk.org> wrote:

>> 8331558: AArch64: optimize integer remainder
>>     On some Arm processors, a separate multiply/subtract is actually faster than the combined instruction.
>> 
>> 8331556: AArch64: CPU_Model support for Neoverse N1/N2/V1/V2
>>     Add full platform coverage for Neoverse variants in vm_version.?pp
>> 
>> The following test has passed, which shows definite performance improvement.
>> 
>> make test TEST="micro:java.lang.IntegerDivMod"
>> make test TEST="micro:java.lang.LongDivMod"
>> 
>> * IntegerDivMod.testDivideRemainderUnsigned
>> baseline(ns/ops)                2223
>> with this pacth(ns/ops)         1885    
>> improvement(%)                  17.93%
>> 
>> * IntegerDivMod.testRemainderUnsigned
>> baseline(ns/ops)                2225
>> with this pacth(ns/ops)         1885    
>> improvement(%)                  18.03%
>> 
>> * LongDivMod.testDivideRemainderUnsigned
>> baseline(ns/ops)                2231
>> with this pacth(ns/ops)         1894    
>> improvement(%)                  17.79%
>> 
>> * LongDivMod.testRemainderUnsigned
>> baseline(ns/ops)                2232
>> with this pacth(ns/ops)         1891
>> improvement(%)                  18.03%
>
> Jin Guojie has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Refine comments

Looks good to me.

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Marked as reviewed by eliu (Committer).

PR Review: https://git.openjdk.org/jdk/pull/19093#pullrequestreview-2047239434