Add a RegisterMaskSDNode class.

This SelectionDAG node will be attached to call nodes by LowerCall(),
and eventually becomes a MO_RegisterMask MachineOperand on the
MachineInstr representing the call instruction.

LowerCall() will attach a register mask that depends on the calling
convention.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148436 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 9f39699..8b1d9ee 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -2206,6 +2206,7 @@
   case ISD::EntryToken:       // These nodes remain the same.
   case ISD::BasicBlock:
   case ISD::Register:
+  case ISD::RegisterMask:
   //case ISD::VALUETYPE:
   //case ISD::CONDCODE:
   case ISD::HANDLENODE: