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diff --git a/lib/CodeGen/SelectionDAG/LatencyPriorityQueue.h b/lib/CodeGen/SelectionDAG/LatencyPriorityQueue.h
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+++ b/lib/CodeGen/SelectionDAG/LatencyPriorityQueue.h
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+//===---- LatencyPriorityQueue.h - A latency-oriented priority queue ------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the LatencyPriorityQueue class, which is a
+// SchedulingPriorityQueue that schedules using latency information to
+// reduce the length of the critical path through the basic block.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LATENCY_PRIORITY_QUEUE_H
+#define LATENCY_PRIORITY_QUEUE_H
+
+#include "llvm/CodeGen/ScheduleDAG.h"
+#include "llvm/ADT/PriorityQueue.h"
+
+namespace llvm {
+  class LatencyPriorityQueue;
+  
+  /// Sorting functions for the Available queue.
+  struct latency_sort : public std::binary_function<SUnit*, SUnit*, bool> {
+    LatencyPriorityQueue *PQ;
+    explicit latency_sort(LatencyPriorityQueue *pq) : PQ(pq) {}
+    
+    bool operator()(const SUnit* left, const SUnit* right) const;
+  };
+
+  class LatencyPriorityQueue : public SchedulingPriorityQueue {
+    // SUnits - The SUnits for the current graph.
+    std::vector<SUnit> *SUnits;
+    
+    // Latencies - The latency (max of latency from this node to the bb exit)
+    // for each node.
+    std::vector<int> Latencies;
+
+    /// NumNodesSolelyBlocking - This vector contains, for every node in the
+    /// Queue, the number of nodes that the node is the sole unscheduled
+    /// predecessor for.  This is used as a tie-breaker heuristic for better
+    /// mobility.
+    std::vector<unsigned> NumNodesSolelyBlocking;
+
+    PriorityQueue<SUnit*, std::vector<SUnit*>, latency_sort> Queue;
+public:
+    LatencyPriorityQueue() : Queue(latency_sort(this)) {
+    }
+    
+    void initNodes(std::vector<SUnit> &sunits) {
+      SUnits = &sunits;
+      // Calculate node priorities.
+      CalculatePriorities();
+    }
+
+    void addNode(const SUnit *SU) {
+      Latencies.resize(SUnits->size(), -1);
+      NumNodesSolelyBlocking.resize(SUnits->size(), 0);
+      CalcLatency(*SU);
+    }
+
+    void updateNode(const SUnit *SU) {
+      Latencies[SU->NodeNum] = -1;
+      CalcLatency(*SU);
+    }
+
+    void releaseState() {
+      SUnits = 0;
+      Latencies.clear();
+    }
+    
+    unsigned getLatency(unsigned NodeNum) const {
+      assert(NodeNum < Latencies.size());
+      return Latencies[NodeNum];
+    }
+    
+    unsigned getNumSolelyBlockNodes(unsigned NodeNum) const {
+      assert(NodeNum < NumNodesSolelyBlocking.size());
+      return NumNodesSolelyBlocking[NodeNum];
+    }
+    
+    unsigned size() const { return Queue.size(); }
+
+    bool empty() const { return Queue.empty(); }
+    
+    virtual void push(SUnit *U) {
+      push_impl(U);
+    }
+    void push_impl(SUnit *U);
+    
+    void push_all(const std::vector<SUnit *> &Nodes) {
+      for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
+        push_impl(Nodes[i]);
+    }
+    
+    SUnit *pop() {
+      if (empty()) return NULL;
+      SUnit *V = Queue.top();
+      Queue.pop();
+      return V;
+    }
+
+    void remove(SUnit *SU) {
+      assert(!Queue.empty() && "Not in queue!");
+      Queue.erase_one(SU);
+    }
+
+    // ScheduledNode - As nodes are scheduled, we look to see if there are any
+    // successor nodes that have a single unscheduled predecessor.  If so, that
+    // single predecessor has a higher priority, since scheduling it will make
+    // the node available.
+    void ScheduledNode(SUnit *Node);
+
+private:
+    void CalculatePriorities();
+    int CalcLatency(const SUnit &SU);
+    void AdjustPriorityOfUnscheduledPreds(SUnit *SU);
+    SUnit *getSingleUnscheduledPred(SUnit *SU);
+  };
+}
+
+#endif