RFR: 8322174: RISC-V: C2 VectorizedHashCode RVV Version [v22]

[Yuri Gaevsky]

On Wed, 6 Aug 2025 17:02:50 GMT, Yuri Gaevsky <duke at openjdk.org> wrote:

>> The patch adds possibility to use RVV instructions for faster vectorizedHashCode calculations on RVV v1.0.0 capable hardware.
>> 
>> Testing: hotspot/jtreg/compiler/ under QEMU-8.1 with RVV v1.0.0.
>
> Yuri Gaevsky has updated the pull request incrementally with one additional commit since the last revision:
> 
>   try m1 for grouping

`60b2d81`:

--- -XX:+UseRVV ---
Benchmark            (size)  Mode  Cnt     Score    Error  Units
ArraysHashCode.ints       1  avgt   30    11.298 ±  0.021  ns/op
ArraysHashCode.ints       5  avgt   30    21.475 ±  0.148  ns/op
ArraysHashCode.ints      10  avgt   30    37.011 ±  0.057  ns/op
ArraysHashCode.ints      20  avgt   30    47.146 ±  0.091  ns/op
ArraysHashCode.ints      30  avgt   30    56.377 ±  0.021  ns/op
ArraysHashCode.ints      40  avgt   30    55.116 ±  0.010  ns/op
ArraysHashCode.ints      50  avgt   30    66.537 ±  0.457  ns/op
ArraysHashCode.ints      60  avgt   30    72.110 ±  0.886  ns/op
ArraysHashCode.ints      70  avgt   30    88.029 ±  0.897  ns/op
ArraysHashCode.ints      80  avgt   30    77.739 ±  1.458  ns/op
ArraysHashCode.ints      90  avgt   30    92.164 ±  1.118  ns/op
ArraysHashCode.ints     100  avgt   30   104.852 ±  4.030  ns/op
ArraysHashCode.ints     200  avgt   30   180.402 ±  0.037  ns/op
ArraysHashCode.ints     300  avgt   30   234.598 ±  7.007  ns/op
ArraysHashCode.ints    1000  avgt   30   806.796 ±  0.126  ns/op
ArraysHashCode.ints   10000  avgt   30  8152.396 ± 79.158  ns/op

Based on above experiments it looks reasonable to use `m2` grouping.

-------------

PR Comment: https://git.openjdk.org/jdk/pull/17413#issuecomment-3160916148
PR Comment: https://git.openjdk.org/jdk/pull/17413#issuecomment-3160919289