RFR: 8263058: Optimize vector shift with zero shift count [v2]

[Tobias Hartmann]

On Thu, 11 Mar 2021 10:37:49 GMT, Eric Liu <github.com+10482586+theRealELiu at openjdk.org> wrote:

>> src/hotspot/share/opto/vectornode.hpp line 524:
>> 
>>> 522:   ShiftVNode(Node* in1, Node* in2, const TypeVect* vt) : VectorNode(in1,in2,vt) {}
>>> 523:   virtual Node* Identity(PhaseGVN* phase);
>>> 524:   virtual int Opcode() const = 0;
>> 
>> I don't think the `Opcode` declaration is needed.
>
> I intended to mark this class as abstract, to prevent it from being instanced.

Right but that won't prevent instantiation and we don't do that for other nodes like `StrIntrinsicNode`. But I'm fine with leaving this in.

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PR: https://git.openjdk.java.net/jdk/pull/2911