RFR: 8322174: RISC-V: C2 VectorizedHashCode RVV Version [v9]

[Yuri Gaevsky]

On Tue, 15 Jul 2025 08:28:51 GMT, Yuri Gaevsky <duke at openjdk.org> wrote:

>> Yuri Gaevsky has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   simplified arrays_hashcode_v() to be closer to VLA and use less general-purpose registers; minor cosmetic changes
>
> bpif3-16g% ( for i in "-XX:DisableIntrinsic=_vectorizedHashCode" "-XX:-UseRVV" "-XX:+UseRVV" ; \
>     do ( echo "--- ${i} ---" && ${JAVA_HOME}/bin/java  -jar benchmarks.jar  \
> 	--jvmArgs="-XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions ${i}" \
> 	org.openjdk.bench.java.lang.ArraysHashCode.ints  \
> 	-p size=1,5,10,20,30,40,50,60,70,80,90,100,200,300 \
> 	-f 3 -r 1 -w 1 -wi 10 -i 10 2>&1 | tail -15 ) done )
> --- -XX:DisableIntrinsic=_vectorizedHashCode ---
> Benchmark            (size)  Mode  Cnt    Score   Error  Units
> ArraysHashCode.ints       1  avgt   30   11.273 ± 0.003  ns/op
> ArraysHashCode.ints       5  avgt   30   28.817 ± 0.013  ns/op
> ArraysHashCode.ints      10  avgt   30   41.330 ± 0.280  ns/op
> ArraysHashCode.ints      20  avgt   30   68.236 ± 0.057  ns/op
> ArraysHashCode.ints      30  avgt   30   88.455 ± 0.142  ns/op
> ArraysHashCode.ints      40  avgt   30  115.251 ± 0.350  ns/op
> ArraysHashCode.ints      50  avgt   30  135.525 ± 0.685  ns/op
> ArraysHashCode.ints      60  avgt   30  161.547 ± 0.165  ns/op
> ArraysHashCode.ints      70  avgt   30  171.417 ± 0.402  ns/op
> ArraysHashCode.ints      80  avgt   30  193.232 ± 0.241  ns/op
> ArraysHashCode.ints      90  avgt   30  207.720 ± 0.304  ns/op
> ArraysHashCode.ints     100  avgt   30  232.256 ± 0.792  ns/op
> ArraysHashCode.ints     200  avgt   30  447.408 ± 0.308  ns/op
> ArraysHashCode.ints     300  avgt   30  656.444 ± 1.332  ns/op
> --- -XX:-UseRVV ---
> Benchmark            (size)  Mode  Cnt    Score   Error  Units
> ArraysHashCode.ints       1  avgt   30   11.279 ± 0.013  ns/op
> ArraysHashCode.ints       5  avgt   30   24.427 ± 0.005  ns/op
> ArraysHashCode.ints      10  avgt   30   35.704 ± 0.011  ns/op
> ArraysHashCode.ints      20  avgt   30   58.894 ± 0.062  ns/op
> ArraysHashCode.ints      30  avgt   30   82.685 ± 0.015  ns/op
> ArraysHashCode.ints      40  avgt   30  105.861 ± 0.065  ns/op
> ArraysHashCode.ints      50  avgt   30  129.672 ± 0.038  ns/op
> ArraysHashCode.ints      60  avgt   30  152.865 ± 0.057  ns/op
> ArraysHashCode.ints      70  avgt   30  176.689 ± 0.063  ns/op
> ArraysHashCode.ints      80  avgt   30  199.823 ± 0.035  ns/op
> ArraysHashCode.ints      90  avgt   30  223.588 ± 0.046  ns/op
> ArraysHashCode.ints     100  avgt   30  247.405 ± 0.661  ns/op
> ArraysHashCode.ints     200  avgt   30  481.698 ± 0.123  ns/op
> ArraysHashCode.ints     300  avgt   30  716.488 ± 0.104  ns/op
> --- -XX:+UseRVV ---
> Benchmark            (size)  Mode  Cnt    Score   Error  Units
> ArraysHashCode.ints       1  avgt   30 ...

> > @ygaevsky @RealFYang how can we procced ?
> 
> My apologies, just busy at the moment with other things, going to update the patch soon.

Thinking more about suggestions to make the code VLA: I don't understand how to break the dependency on `result` calculation? It depends on previous `result`:
 ```
   result = 31^^M * result  + 31^^(M-1) * val[i+0] + 32^^0 * val[i+(M-1)];

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

PR Comment: https://git.openjdk.org/jdk/pull/17413#issuecomment-3072726308