RFR: 8353786: Migrate Vector API math library support to FFM API [v5]

[Vladimir Ivanov]

On Thu, 17 Apr 2025 01:36:39 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

>> How does it work now? The code in `generate_vector_math_stubs()` in `stubGenerator_aarch64.cpp` only populates `VEC_SIZE_SCALABLE` shapes with SVE versions.
>
> Please see the `addr` definition code in https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/vectorIntrinsics.cpp#L1877 . If queried `addr` returns `nullptr` for 256-bit vectors, and the arch supports scalable vector, then the `addr` will be assigned to the scalable ones.

Ah, ok. Thanks for the pointer. I aligned lookup logic with existing behavior. 

I'd like to double-check one things: is it fine to use scalable vector variants for fixed-sized vector shapes of smaller size without any explicit masking/stripping of upper vector part?

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PR Review Comment: https://git.openjdk.org/jdk/pull/24462#discussion_r2049436133