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

[Emanuel Peter]

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.

src/hotspot/share/opto/vectornode.cpp line 669:

> 667: }
> 668: 
> 669: // Make a vector node for unary or binary operation

Note: there were already unary cases, this just fixes the comment.

src/hotspot/share/opto/vectornode.cpp line 752:

> 750:   case Op_LShiftCntV: return new LShiftCntVNode(n1, vt);
> 751:   case Op_RShiftCntV: return new RShiftCntVNode(n1, vt);
> 752: 

Note: used to be in `VectorNode::shift_count`

src/hotspot/share/opto/vectornode.cpp line 783:

> 781:   case Op_VectorCastHF2F: return new VectorCastHF2FNode(n1, vt);
> 782:   case Op_VectorCastF2HF: return new VectorCastF2HFNode(n1, vt);
> 783: 

Note: used to be in `VectorCastNode::make`

src/hotspot/share/opto/vectornode.cpp line 856:

> 854:   default:
> 855:     fatal("Node class '%s' is not supported for shift count", NodeClassNames[opc]);
> 856:     return -1;

Note: splitting the old `VectorNode::shift_count` (scalar opc -> L/RShiftCntVNode).
- Created new `VectorNode::shift_count_opcode` (scalar opc -> vector shift cnt opc)
- Moved node creation to `VectorNode::make` (vector shift cnt opc -> L/RShiftCntVNode)

I need this for later VTransform changes, where I need to do the vector-opc determination in one stage (VTransform build), and then the vector-node creation in a later stage (VTransform apply).

src/hotspot/share/opto/vectornode.cpp line 1437:

> 1435: VectorNode* VectorCastNode::make(int vopc, Node* n1, BasicType bt, uint vlen) {
> 1436:   const TypeVect* vt = TypeVect::make(bt, vlen);
> 1437:   return VectorNode::make(vopc, n1, nullptr, vt);

Note: the code is moved to `VectorNode::make`

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PR Review Comment: https://git.openjdk.org/jdk/pull/22917#discussion_r1901918030
PR Review Comment: https://git.openjdk.org/jdk/pull/22917#discussion_r1901918317
PR Review Comment: https://git.openjdk.org/jdk/pull/22917#discussion_r1901918499
PR Review Comment: https://git.openjdk.org/jdk/pull/22917#discussion_r1901922127
PR Review Comment: https://git.openjdk.org/jdk/pull/22917#discussion_r1901922545