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/ScheduleDAGSDNodes.h b/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.h
index 9c27b2e..17b4901 100644
--- a/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.h
+++ b/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.h
@@ -53,6 +53,7 @@
       if (isa<ConstantSDNode>(Node))       return true;
       if (isa<ConstantFPSDNode>(Node))     return true;
       if (isa<RegisterSDNode>(Node))       return true;
+      if (isa<RegisterMaskSDNode>(Node))   return true;
       if (isa<GlobalAddressSDNode>(Node))  return true;
       if (isa<BasicBlockSDNode>(Node))     return true;
       if (isa<FrameIndexSDNode>(Node))     return true;