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diff --git a/clang-r353983e/include/llvm/CodeGen/LatencyPriorityQueue.h b/clang-r353983e/include/llvm/CodeGen/LatencyPriorityQueue.h
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+//===---- LatencyPriorityQueue.h - A latency-oriented priority queue ------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// 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 LLVM_CODEGEN_LATENCYPRIORITYQUEUE_H
+#define LLVM_CODEGEN_LATENCYPRIORITYQUEUE_H
+
+#include "llvm/CodeGen/ScheduleDAG.h"
+#include "llvm/Config/llvm-config.h"
+
+namespace llvm {
+  class LatencyPriorityQueue;
+
+  /// Sorting functions for the Available queue.
+  struct latency_sort {
+    LatencyPriorityQueue *PQ;
+    explicit latency_sort(LatencyPriorityQueue *pq) : PQ(pq) {}
+
+    bool operator()(const SUnit* LHS, const SUnit* RHS) const;
+  };
+
+  class LatencyPriorityQueue : public SchedulingPriorityQueue {
+    // SUnits - The SUnits for the current graph.
+    std::vector<SUnit> *SUnits;
+
+    /// 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;
+
+    /// Queue - The queue.
+    std::vector<SUnit*> Queue;
+    latency_sort Picker;
+
+  public:
+    LatencyPriorityQueue() : Picker(this) {
+    }
+
+    bool isBottomUp() const override { return false; }
+
+    void initNodes(std::vector<SUnit> &sunits) override {
+      SUnits = &sunits;
+      NumNodesSolelyBlocking.resize(SUnits->size(), 0);
+    }
+
+    void addNode(const SUnit *SU) override {
+      NumNodesSolelyBlocking.resize(SUnits->size(), 0);
+    }
+
+    void updateNode(const SUnit *SU) override {
+    }
+
+    void releaseState() override {
+      SUnits = nullptr;
+    }
+
+    unsigned getLatency(unsigned NodeNum) const {
+      assert(NodeNum < (*SUnits).size());
+      return (*SUnits)[NodeNum].getHeight();
+    }
+
+    unsigned getNumSolelyBlockNodes(unsigned NodeNum) const {
+      assert(NodeNum < NumNodesSolelyBlocking.size());
+      return NumNodesSolelyBlocking[NodeNum];
+    }
+
+    bool empty() const override { return Queue.empty(); }
+
+    void push(SUnit *U) override;
+
+    SUnit *pop() override;
+
+    void remove(SUnit *SU) override;
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+    LLVM_DUMP_METHOD void dump(ScheduleDAG *DAG) const override;
+#endif
+
+    // 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 *SU) override;
+
+private:
+    void AdjustPriorityOfUnscheduledPreds(SUnit *SU);
+    SUnit *getSingleUnscheduledPred(SUnit *SU);
+  };
+}
+
+#endif