RFR: 8312425: [vectorapi] AArch64: Optimize vector math operations with SLEEF [v2]

[Hamlin Li]

On Thu, 14 Mar 2024 15:29:51 GMT, Andrew Haley <aph at openjdk.org> wrote:

> Hi, thanks for continuing with this.

Thanks for the comments

> As this is similar to SVML, comments applies to x86 also:
> 
> * There is no way to stop the VM from trying to load vmath ?

No official way, but deleting libvmath.so will have a same effect. 
I'm not sure if avoiding loading vmath is necessary for typical users, if it turns out to be true, we can add it later.

>   There is both a UseNeon and a UseSVE, if I set both to false I would expect no vector and no vmath.
>   The issue with UseNeon not really guarding neon code, but just crc, seems like a pre-existing bug.
>   A flag like 'UseNeon' should turn it on/off :)

I think Andrew asked this question, I agree it's better to remove the flag usage in crc32 on aarch64, better to be done in a separate [pr](https://bugs.openjdk.org/browse/JDK-8328265).

> * Doing open dll form stubrountines seems wrong.

I agree, logically it brings more clear code structure. But as this will be common change (e.g. on both x86 and aarch64) in the stub initialization steps, , and I think we'd better do it in a seprate [pr](https://bugs.openjdk.org/browse/JDK-8328266).

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PR Comment: https://git.openjdk.org/jdk/pull/18294#issuecomment-1999457249