[MachineScheduler] Disable default copy ctor and copy assignment operator for SchedBoundary

[yubing]

Summary

class SchedBoundary manages resources such as dynamically allocated memory, it's generally a good practice to either implement a custom copy constructor or disable the default one.

[pengfei]

LGTM.

llvm/include/llvm/CodeGen/MachineScheduler.h

 
 public:
   /// Pending queues extend the ready queues with the same ID and the
   /// PendingFlag set.
   SchedBoundary(unsigned ID, const Twine &Name):
     Available(ID, Name+".A"), Pending(ID << LogMaxQID, Name+".P") {
     reset();
   }
-
+  SchedBoundary &operator=(const SchedBoundary &other) = delete;
+  SchedBoundary(const SchedBoundary &other) = delete;
   ~SchedBoundary();
 
   void reset();
 
   void init(ScheduleDAGMI *dag, const TargetSchedModel *smodel,
             SchedRemainder *rem);
 
   bool isTop() const {