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

[Vladimir Ivanov]

On Wed, 16 Apr 2025 02:11:09 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

>> Vladimir Ivanov 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 19 additional commits since the last revision:
>> 
>>  - Merge branch 'master' into vector.math.01.java
>>  - RVV and SVE adjustments
>>  - Merge branch 'master' into vector.math.01.java
>>  - Fix windows-aarch64 build failure
>>  - features_string -> cpu_info_string
>>  - Reviews and Float64Vector-related fix
>>  - Misc fixes and cleanups
>>  - CPU features support
>>  - Cleanup
>>  - TODO list
>>  - ... and 9 more: https://git.openjdk.org/jdk/compare/e269cc66...0ffed12f
>
> src/jdk.incubator.vector/share/classes/jdk/incubator/vector/VectorMathLibrary.java line 240:
> 
>> 238:                 if (isAARCH64() && vspecies.vectorBitSize() > 128) {
>> 239:                     return false; // FIXME: SVE support only for MAX shapes
>> 240:                 }
> 
> SVE also supports operations for partial vector size, which means the vector size is smaller than MAX size. For example, if the max vector size of a SVE architecture is 512-bit, the FP vector operations with `VectorShape.S_256_BIT` are also supported. They are implemented with the same scalable math functions in SLEEF.
> 
> Hence, I think this check and the assertion in line-198 can be removed. Thanks!

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.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24462#discussion_r2047489059