+
+ /// ScheduleDAGTopologicalSort is a class that computes a topological
+ /// ordering for SUnits and provides methods for dynamically updating
+ /// the ordering as new edges are added.
+ ///
+ /// This allows a very fast implementation of IsReachable, for example.
+ ///
+ class ScheduleDAGTopologicalSort {
+ /// SUnits - A reference to the ScheduleDAG's SUnits.
+ std::vector<SUnit> &SUnits;
+
+ /// Index2Node - Maps topological index to the node number.
+ std::vector<int> Index2Node;
+ /// Node2Index - Maps the node number to its topological index.
+ std::vector<int> Node2Index;
+ /// Visited - a set of nodes visited during a DFS traversal.
+ BitVector Visited;
+
+ /// DFS - make a DFS traversal and mark all nodes affected by the
+ /// edge insertion. These nodes will later get new topological indexes
+ /// by means of the Shift method.
+ void DFS(const SUnit *SU, int UpperBound, bool& HasLoop);
+
+ /// Shift - reassign topological indexes for the nodes in the DAG
+ /// to preserve the topological ordering.
+ void Shift(BitVector& Visited, int LowerBound, int UpperBound);
+
+ /// Allocate - assign the topological index to the node n.
+ void Allocate(int n, int index);
+
+ public:
+ explicit ScheduleDAGTopologicalSort(std::vector<SUnit> &SUnits);
+
+ /// InitDAGTopologicalSorting - create the initial topological
+ /// ordering from the DAG to be scheduled.
+ void InitDAGTopologicalSorting();
+
+ /// IsReachable - Checks if SU is reachable from TargetSU.
+ bool IsReachable(const SUnit *SU, const SUnit *TargetSU);
+
+ /// WillCreateCycle - Returns true if adding an edge from SU to TargetSU
+ /// will create a cycle.
+ bool WillCreateCycle(SUnit *SU, SUnit *TargetSU);
+
+ /// AddPred - Updates the topological ordering to accomodate an edge
+ /// to be added from SUnit X to SUnit Y.
+ void AddPred(SUnit *Y, SUnit *X);
+
+ /// RemovePred - Updates the topological ordering to accomodate an
+ /// an edge to be removed from the specified node N from the predecessors
+ /// of the current node M.
+ void RemovePred(SUnit *M, SUnit *N);
+
+ typedef std::vector<int>::iterator iterator;
+ typedef std::vector<int>::const_iterator const_iterator;
+ iterator begin() { return Index2Node.begin(); }
+ const_iterator begin() const { return Index2Node.begin(); }
+ iterator end() { return Index2Node.end(); }
+ const_iterator end() const { return Index2Node.end(); }
+
+ typedef std::vector<int>::reverse_iterator reverse_iterator;
+ typedef std::vector<int>::const_reverse_iterator const_reverse_iterator;
+ reverse_iterator rbegin() { return Index2Node.rbegin(); }
+ const_reverse_iterator rbegin() const { return Index2Node.rbegin(); }
+ reverse_iterator rend() { return Index2Node.rend(); }
+ const_reverse_iterator rend() const { return Index2Node.rend(); }
+ };