RFR: 8346993: C2 SuperWord: refactor to make more vector nodes available in VectorNode::make

[Emanuel Peter]

On Mon, 6 Jan 2025 17:32:50 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> Extracted from cost-model code https://github.com/openjdk/jdk/pull/20964.
>> 
>> Currently, some nodes are only generated in their dedicated methods:
>> - VectorNode::shift_count
>>   - LShiftCntVNode
>>   - RShiftCntVNode
>> - VectorCastNode::make
>>   - Vector(U)Cast...
>> - VectorBlendNode has no corresponding "factory" method.
>> 
>> The goal is to have all available under VectorNode::make, so that they can be generated simply with the vector opcode. This is helpful for the plans with the cost-model, where the VTransform nodes will only carry the vector-opc, and I need to generate vectors for these vector-opc.
>
> Looks good to me too.

Thanks @vnkozlov @chhagedorn for the reviews!

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PR Comment: https://git.openjdk.org/jdk/pull/22917#issuecomment-2574469626