RFR: 8322770: Implement C2 VectorizedHashCode on AArch64

[Mikhail Ablakatov]

On Thu, 16 May 2024 12:40:30 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> Hi,
>> 
>>>  I can update the patch with current results on Monday and we could decide how to proceed with this PR after that. Sounds good?
>> 
>> Yes, that's right.
>
>> Hi @theRealAph ! You may find the latest version here: [mikabl-arm at b3db421](https://github.com/mikabl-arm/jdk/commit/b3db421c795f683db1a001853990026bafc2ed4b) . I gave a short explanation in the commit message, feel free to ask for more details if required.
>> 
>> Unfortunately, it still contains critical bugs and I won't be able to take a look into the issue before the next week at best. Until it's fixed, it's not possible to run the benchmarks. Although I expect it to improve performance on longer integer arrays based on a benchmark I've written in C++ and Assembly. The results aren't comparable to the jmh results, so I won't post them here.
> 
> OK. One small thing, I think it's possible to rearrange things a bit to use `mlav`, which may help performance. No need for that until the code is correct, though.

@theRealAph , I've updated https://github.com/mikabl-arm/jdk/tree/285826-vmul to implement the Neon part of the intrinsic as a separate stub method. This solves the second issue mentioned in the comment above.

Could you check the code in https://github.com/mikabl-arm/jdk/tree/285826-vmul  ? if you're happy with the direction it's taking, I'll merge the changes to this PR's branch (https://github.com/mikabl-arm/jdk/tree/8322770) to make things a bit easier to keep track of.

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PR Comment: https://git.openjdk.org/jdk/pull/18487#issuecomment-2263484488