[CodeGen] Add OPC_MoveChild0-OPC_MoveChild7 opcodes to isel matching tables to optimize table size. Shaves about 12K off the X86 matcher table.

llvm-svn: 268209
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 3996645..016dd28 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -2971,6 +2971,18 @@
       continue;
     }
 
+    case OPC_MoveChild0: case OPC_MoveChild1:
+    case OPC_MoveChild2: case OPC_MoveChild3:
+    case OPC_MoveChild4: case OPC_MoveChild5:
+    case OPC_MoveChild6: case OPC_MoveChild7: {
+      unsigned ChildNo = Opcode-OPC_MoveChild0;
+      if (ChildNo >= N.getNumOperands())
+        break;  // Match fails if out of range child #.
+      N = N.getOperand(ChildNo);
+      NodeStack.push_back(N);
+      continue;
+    }
+
     case OPC_MoveParent:
       // Pop the current node off the NodeStack.
       NodeStack.pop_back();