RFR: 8354242: VectorAPI: combine vector not operation with compare [v6]

[erifan]

On Thu, 29 May 2025 01:44:49 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

>> test/micro/org/openjdk/bench/jdk/incubator/vector/MaskCompareNotBenchmark.java line 49:
>> 
>>> 47:     private static final VectorSpecies<Long> L_SPECIES = LongVector.SPECIES_MAX;
>>> 48:     private static final VectorSpecies<Float> F_SPECIES = FloatVector.SPECIES_MAX;
>>> 49:     private static final VectorSpecies<Double> D_SPECIES = DoubleVector.SPECIES_MAX;
>> 
>> Are you taking `SPECIES_MAX` on purpose here, or could we take `SPECIES_PREFERRED` instead?
>> @jatin-bhateja What is the best to do in these tests? I suppose best would be to test with all vector lengths...
>
> Thanks for pointing out this @eme64 ! Per my understanding, `SPECIES_MAX` is almost the same with `SPECIES_PREFERRED` in this case which are all specified to the max vector size of a hardware. Since the max vector size is different on different architectures, not all vector lengths are supported to be intrinsified on a specified architecture like AArch64, especially the SVE arch with different vector register size. Hence, just testing the max species makes sense to me as this is a mid-end common transformation.

Changed to use `ofLargestShape()` because on x64 the max vector length is related to data types.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/24674#discussion_r2128383805