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diff --git a/include/llvm/CodeGen/CalcSpillWeights.h b/include/llvm/CodeGen/CalcSpillWeights.h
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+//===---------------- lib/CodeGen/CalcSpillWeights.h ------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+
+#ifndef LLVM_CODEGEN_CALCSPILLWEIGHTS_H
+#define LLVM_CODEGEN_CALCSPILLWEIGHTS_H
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/CodeGen/SlotIndexes.h"
+
+namespace llvm {
+
+  class LiveInterval;
+  class LiveIntervals;
+  class MachineBlockFrequencyInfo;
+  class MachineLoopInfo;
+
+  /// \brief Normalize the spill weight of a live interval
+  ///
+  /// The spill weight of a live interval is computed as:
+  ///
+  ///   (sum(use freq) + sum(def freq)) / (K + size)
+  ///
+  /// @param UseDefFreq Expected number of executed use and def instructions
+  ///                   per function call. Derived from block frequencies.
+  /// @param Size       Size of live interval as returnexd by getSize()
+  ///
+  static inline float normalizeSpillWeight(float UseDefFreq, unsigned Size) {
+    // The constant 25 instructions is added to avoid depending too much on
+    // accidental SlotIndex gaps for small intervals. The effect is that small
+    // intervals have a spill weight that is mostly proportional to the number
+    // of uses, while large intervals get a spill weight that is closer to a use
+    // density.
+    return UseDefFreq / (Size + 25*SlotIndex::InstrDist);
+  }
+
+  /// \brief Calculate auxiliary information for a virtual register such as its
+  /// spill weight and allocation hint.
+  class VirtRegAuxInfo {
+  public:
+    typedef float (*NormalizingFn)(float, unsigned);
+
+  private:
+    MachineFunction &MF;
+    LiveIntervals &LIS;
+    const MachineLoopInfo &Loops;
+    const MachineBlockFrequencyInfo &MBFI;
+    DenseMap<unsigned, float> Hint;
+    NormalizingFn normalize;
+
+  public:
+    VirtRegAuxInfo(MachineFunction &mf, LiveIntervals &lis,
+                   const MachineLoopInfo &loops,
+                   const MachineBlockFrequencyInfo &mbfi,
+                   NormalizingFn norm = normalizeSpillWeight)
+        : MF(mf), LIS(lis), Loops(loops), MBFI(mbfi), normalize(norm) {}
+
+    /// \brief (re)compute li's spill weight and allocation hint.
+    void calculateSpillWeightAndHint(LiveInterval &li);
+  };
+
+  /// \brief Compute spill weights and allocation hints for all virtual register
+  /// live intervals.
+  void calculateSpillWeightsAndHints(LiveIntervals &LIS, MachineFunction &MF,
+                                     const MachineLoopInfo &MLI,
+                                     const MachineBlockFrequencyInfo &MBFI,
+                                     VirtRegAuxInfo::NormalizingFn norm =
+                                         normalizeSpillWeight);
+}
+
+#endif // LLVM_CODEGEN_CALCSPILLWEIGHTS_H