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

[Jatin Bhateja]

On Mon, 16 Oct 2023 01:07:55 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

>> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Review comments resolutions.
>
> src/hotspot/share/oops/inlineKlass.cpp line 158:
> 
>> 156:   if (VectorSupport::is_vector_payload_mf(this) || VectorSupport::is_vector(this)) {
>> 157:     return false;
>> 158:   }
> 
> Why do you close the array flatten for vectors?

Array of vector may be heterogeneous in nature where each element points to a vector of different shape, thus array flatten do not make much sense to vectors. In additional during type resolution flat_array flag is set for imbalanced Phi (having different type of inputs e.g. VectorPayload64 and VectorPayload128) even though Phi's type is lower common ancestor type of participating inputs i.e., VectorPayload which itself is not an inlinetype, this leads to assertion failures in downstream flow.

https://github.com/openjdk/valhalla/blob/lworld/src/hotspot/share/opto/type.cpp#L4636

Instead of making a wider change in type resolution, where we flat_array setting also take into account exact type of PhiNode, I prefer to restrict array flatten for vectors.

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PR Review Comment: https://git.openjdk.org/valhalla/pull/931#discussion_r1360164551