+/// GetCostForDef - Looks up the register class and cost for a given definition.
+/// Typically this just means looking up the representative register class,
+/// but for untyped values (MVT::untyped) it means inspecting the node's
+/// opcode to determine what register class is being generated.
+static void GetCostForDef(const ScheduleDAGSDNodes::RegDefIter &RegDefPos,
+ const TargetLowering *TLI,
+ const TargetInstrInfo *TII,
+ const TargetRegisterInfo *TRI,
+ unsigned &RegClass, unsigned &Cost) {
+ EVT VT = RegDefPos.GetValue();
+
+ // Special handling for untyped values. These values can only come from
+ // the expansion of custom DAG-to-DAG patterns.
+ if (VT == MVT::untyped) {
+ const SDNode *Node = RegDefPos.GetNode();
+ unsigned Opcode = Node->getMachineOpcode();
+
+ if (Opcode == TargetOpcode::REG_SEQUENCE) {
+ unsigned DstRCIdx = cast<ConstantSDNode>(Node->getOperand(0))->getZExtValue();
+ const TargetRegisterClass *RC = TRI->getRegClass(DstRCIdx);
+ RegClass = RC->getID();
+ Cost = 1;
+ return;
+ }
+
+ unsigned Idx = RegDefPos.GetIdx();
+ const TargetInstrDesc Desc = TII->get(Opcode);
+ const TargetRegisterClass *RC = Desc.getRegClass(Idx, TRI);
+ RegClass = RC->getID();
+ // FIXME: Cost arbitrarily set to 1 because there doesn't seem to be a
+ // better way to determine it.
+ Cost = 1;
+ } else {
+ RegClass = TLI->getRepRegClassFor(VT)->getID();
+ Cost = TLI->getRepRegClassCostFor(VT);
+ }
+}