RFR: 8312425: [vectorapi] AArch64: Optimize vector math operations with SLEEF [v3]

[Xiaohong Gong]

On Wed, 18 Oct 2023 09:45:01 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> Xiaohong Gong has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:
>> 
>>  - Add a bundled native lib in jdk as a bridge to libsleef
>>  - Merge 'jdk:master' into JDK-8312425
>>  - Disable sleef by default
>>  - Merge 'jdk:master' into JDK-8312425
>>  - 8312425: [vectorapi] AArch64: Optimize vector math operations with SLEEF
>
> This looks good. As far as I can tell the choice you've made of accuracy matches what we need to meet the spec.
> I'm very nervous about binding ourselves to a specific version of the SLEEF ABI, because Java releases are maintained for decades, and we don't want to be dependent on other projects.  
> 
> We'll have to make a plan for version evolution.

Hi @theRealAph , 

The latest commit created a native library as a bridge to the third-party sleef library. Could you please help check whether it's a better solution to fix the hard-coding sleef ABI version issue and the further evolution?

It re-defines all the vector math functions and implements them by calling the relative functions in libsleef. The library is bundled into the jdk image. With this way, we doesn't need to hard-code the libsleef ABI version into jdk. And the potential issue caused by the future ABI updating may be catched earlier. Meanwhile, the original added VM option (i.e. `-XX:UseSleefLib`) is not needed anymore. So we removed it then.

Thanks,
Xiaohong Gong

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PR Comment: https://git.openjdk.org/jdk/pull/16234#issuecomment-1811659809