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diff --git a/include/llvm/CodeGen/ScoreboardHazardRecognizer.h b/include/llvm/CodeGen/ScoreboardHazardRecognizer.h
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+++ b/include/llvm/CodeGen/ScoreboardHazardRecognizer.h
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+//=- llvm/CodeGen/ScoreboardHazardRecognizer.h - Schedule Support -*- C++ -*-=//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the ScoreboardHazardRecognizer class, which
+// encapsulates hazard-avoidance heuristics for scheduling, based on the
+// scheduling itineraries specified for the target.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_SCOREBOARDHAZARDRECOGNIZER_H
+#define LLVM_CODEGEN_SCOREBOARDHAZARDRECOGNIZER_H
+
+#include "llvm/CodeGen/ScheduleHazardRecognizer.h"
+#include "llvm/Support/DataTypes.h"
+#include <cassert>
+#include <cstring>
+
+namespace llvm {
+
+class InstrItineraryData;
+class ScheduleDAG;
+class SUnit;
+
+class ScoreboardHazardRecognizer : public ScheduleHazardRecognizer {
+  // Scoreboard to track function unit usage. Scoreboard[0] is a
+  // mask of the FUs in use in the cycle currently being
+  // schedule. Scoreboard[1] is a mask for the next cycle. The
+  // Scoreboard is used as a circular buffer with the current cycle
+  // indicated by Head.
+  //
+  // Scoreboard always counts cycles in forward execution order. If used by a
+  // bottom-up scheduler, then the scoreboard cycles are the inverse of the
+  // scheduler's cycles.
+  class Scoreboard {
+    unsigned *Data;
+
+    // The maximum number of cycles monitored by the Scoreboard. This
+    // value is determined based on the target itineraries to ensure
+    // that all hazards can be tracked.
+    size_t Depth;
+    // Indices into the Scoreboard that represent the current cycle.
+    size_t Head;
+  public:
+    Scoreboard():Data(nullptr), Depth(0), Head(0) { }
+    ~Scoreboard() {
+      delete[] Data;
+    }
+
+    size_t getDepth() const { return Depth; }
+    unsigned& operator[](size_t idx) const {
+      // Depth is expected to be a power-of-2.
+      assert(Depth && !(Depth & (Depth - 1)) &&
+             "Scoreboard was not initialized properly!");
+
+      return Data[(Head + idx) & (Depth-1)];
+    }
+
+    void reset(size_t d = 1) {
+      if (!Data) {
+        Depth = d;
+        Data = new unsigned[Depth];
+      }
+
+      memset(Data, 0, Depth * sizeof(Data[0]));
+      Head = 0;
+    }
+
+    void advance() {
+      Head = (Head + 1) & (Depth-1);
+    }
+
+    void recede() {
+      Head = (Head - 1) & (Depth-1);
+    }
+
+    // Print the scoreboard.
+    void dump() const;
+  };
+
+#ifndef NDEBUG
+  // Support for tracing ScoreboardHazardRecognizer as a component within
+  // another module. Follows the current thread-unsafe model of tracing.
+  static const char *DebugType;
+#endif
+
+  // Itinerary data for the target.
+  const InstrItineraryData *ItinData;
+
+  const ScheduleDAG *DAG;
+
+  /// IssueWidth - Max issue per cycle. 0=Unknown.
+  unsigned IssueWidth;
+
+  /// IssueCount - Count instructions issued in this cycle.
+  unsigned IssueCount;
+
+  Scoreboard ReservedScoreboard;
+  Scoreboard RequiredScoreboard;
+
+public:
+  ScoreboardHazardRecognizer(const InstrItineraryData *ItinData,
+                             const ScheduleDAG *DAG,
+                             const char *ParentDebugType = "");
+
+  /// atIssueLimit - Return true if no more instructions may be issued in this
+  /// cycle.
+  bool atIssueLimit() const override;
+
+  // Stalls provides an cycle offset at which SU will be scheduled. It will be
+  // negative for bottom-up scheduling.
+  HazardType getHazardType(SUnit *SU, int Stalls) override;
+  void Reset() override;
+  void EmitInstruction(SUnit *SU) override;
+  void AdvanceCycle() override;
+  void RecedeCycle() override;
+};
+
+}
+
+#endif //!LLVM_CODEGEN_SCOREBOARDHAZARDRECOGNIZER_H