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

[Christian Hagedorn]

On Fri, 3 Jan 2025 15:44:02 GMT, Emanuel Peter <epeter 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.

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Marked as reviewed by chagedorn (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/22917#pullrequestreview-2531569151