[all-commits] [llvm/llvm-project] 714417: [SelectionDAG] Add OPC_MoveSibling (#73643)

[Wang Pengcheng via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 714417455da34855290c3b575b8daabb78340e45
      https://github.com/llvm/llvm-project/commit/714417455da34855290c3b575b8daabb78340e45
  Author: Wang Pengcheng <wangpengcheng.pp at bytedance.com>
  Date:   2023-12-12 (Tue, 12 Dec 2023)

  Changed paths:
    M llvm/include/llvm/CodeGen/SelectionDAGISel.h
    M llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
    M llvm/utils/TableGen/DAGISelMatcher.cpp
    M llvm/utils/TableGen/DAGISelMatcher.h
    M llvm/utils/TableGen/DAGISelMatcherEmitter.cpp
    M llvm/utils/TableGen/DAGISelMatcherOpt.cpp

  Log Message:
  -----------
  [SelectionDAG] Add OPC_MoveSibling (#73643)

There are a lot of operations to move current node to parent and
then move to another child.

So `OPC_MoveSibling` and its space-optimized forms are added to do
this "move to sibling" operations.

These new operations will be generated when optimizing matcher in
`ContractNodes`. Currently `MoveParent+MoveChild` will be optimized
to `MoveSibling` and sequences `MoveParent+RecordChild+MoveChild`
will be transformed into `MoveSibling+RecordNode`.

Overall this reduces the llc binary size with all in-tree targets by
about 30K.