RFR: 8312425: [vectorapi] AArch64: Optimize vector math operations with SLEEF [v4]

[Paul Sandoz]

On Fri, 15 Mar 2024 13:58:05 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> Hi,
>> Can you help to review this patch?
>> Thanks
>> 
>> This is a continuation of work based on [1] by @XiaohongGong, most work was done in that pr. In this new pr, just rebased the code in [1], then added some minor changes (renaming of calling method, add libsleef as extra lib in CI cross-build on aarch64 in github workflow); I aslo tested the combination of following scenarios:
>> * at build time
>>   * with/without sleef
>>   * with/without sve support 
>> * at runtime
>>   * with/without sleef
>>   * with/without sve support 
>> 
>> [1] https://github.com/openjdk/jdk/pull/16234
>> 
>> ## Regression Test
>> * test/jdk/jdk/incubator/vector/
>> * test/hotspot/jtreg/compiler/vectorapi/
>> 
>> ## Performance Test
>> Previously, @XiaohongGong has shared the data: https://github.com/openjdk/jdk/pull/16234#issuecomment-1767727028
>
> Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fix jni includes

Hamlin, thank you for working on this. I think integrating a sub-set of SLEEF is valuable (not all of it makes sense e.g., DFT part). My recommendation would be to focus on a PR that integrates the required source, rather taking steps towards that.

AFAICT from browsing prior comments "integrate the source" appears to be the generally preferred solution, but there is some understandable hesitancy about legal aspects. IIUC from what you say this is a technically feasible and maintainable solution. As said here:

> We (Oracle Java Platform Group) can handle the required "paperwork 
https://github.com/openjdk/jdk/pull/16234#issuecomment-1823335443

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PR Comment: https://git.openjdk.org/jdk/pull/18294#issuecomment-2025878452