[lworld+vector] RFR: 8311675: [lworld+vector] Max Species support. [v3]

[Xiaohong Gong]

On Mon, 16 Oct 2023 08:11:10 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> Thanks for the explanation! Seems it also causes the jvm crash in `VectorXXXConversionTests`, but I didn't figure out the root cause yet.  Is it possible supporting the flat array for vector objects with some fixes in future? We may lose the performance with this change, right?
>
> Since we never expose concrete vector types to users hence its only possible to create an array of abstract vector references which can be heterogeneous. This is different from an array of value types which are implicitly final classes and may be flattened into a compact layout since such an array will be homogeneous in nature.

Yeah, I understand. Maybe we could find other more general ways to forbit such kind of array flatten like vector objects, instead of hard coding the `vector/vector_payload` classes. We can revisit this in future. WDYT?

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PR Review Comment: https://git.openjdk.org/valhalla/pull/931#discussion_r1361408537