[lworld+vector] RFR: 8307715: Integrate VectorMask/Shuffle with value/primitive classes [v5]

[Jatin Bhateja]

On Fri, 19 May 2023 10:46:27 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

>> This patch changes the Vector API java side and hotspot compiler code to make the `VectorMask` and `VectorShuffle` operations work well after integrating with valhalla value/primitive classes.
>> 
>> Java side changes include:
>>  - Define the concrete `VectorMask/VectorShuffle `classes as value class.
>>  - Define the payload field type as primitive classes, which defines `MultiField` annotated field to save the element values.
>>  - Change all the relative API implementations, which use Unsafe APIs to access the new payload.
>>  - Move several VectorMask default operations to the abstract super class.
>>  - Minor code cleanup.
>> 
>> Compiler changes include:
>>  - Enable intrinsification for `VectorMask/VectorShuffle` related operations.
>>    Mask input/output of `VectorBox/VectorUnbox` is changed to the boolean vector format, to adapt C2's `InlineTypeNode`
>>    and new `VectorBox` features. Note that the mask input/output is a normal vector or predicate before.
>>  - Refine `VectorBox` expanding logic to make it right when the primitive payload instance is not flattened.
>>  - Minor code cleanup.
>> 
>> Basic VectorMask/VectorShuffle jtreg tests pass with"`-XX:+UnlockExperimentalVMOptions -XX:-EnableVectorSupport`",
>> and the basic unit tests work well after enabling vector support.
>
> Xiaohong Gong has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix jtreg failures

src/hotspot/share/opto/vector.cpp line 308:

> 306:   Node* klass_node = kit.makecon(TypeKlassPtr::make(vk));
> 307:   Node* alloc_oop  = kit.new_instance(klass_node, NULL, NULL, /* deoptimize_on_exception */ true, vector);
> 308:   vector->store(&kit, alloc_oop, alloc_oop, vk);

Do you think we should allocate explicit payload for non-flattened case before calling InlineTypeNode::store.
As per following 
https://github.com/openjdk/valhalla/blob/lworld%2Bvector/src/hotspot/share/classfile/fieldLayoutBuilder.cpp#L768
Flattening depends on InlineFieldMaxFlatSize (default 128 bytes so fine for current vectors) but its configurable and value can be reduced.

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PR Review Comment: https://git.openjdk.org/valhalla/pull/845#discussion_r1203470184