X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FCodeGen%2FCalcSpillWeights.h;h=7c901906308017a39f6e4755d7fc63cfebdefd87;hb=cf0db29df20d9c665da7e82bb261bdd7cf7f1b2b;hp=a47d8477393dede15641a41b1830b405f44fc3c1;hpb=08e93b14c37277ab40b835de340f89ba357d3332;p=oota-llvm.git

diff --git a/include/llvm/CodeGen/CalcSpillWeights.h b/include/llvm/CodeGen/CalcSpillWeights.h
index a47d8477393..7c901906308 100644
--- a/include/llvm/CodeGen/CalcSpillWeights.h
+++ b/include/llvm/CodeGen/CalcSpillWeights.h
@@ -11,54 +11,69 @@
 #ifndef LLVM_CODEGEN_CALCSPILLWEIGHTS_H
 #define LLVM_CODEGEN_CALCSPILLWEIGHTS_H
 
-#include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/ADT/DenseMap.h"
+#include "llvm/CodeGen/SlotIndexes.h"
 
 namespace llvm {
 
   class LiveInterval;
   class LiveIntervals;
+  class MachineBlockFrequencyInfo;
   class MachineLoopInfo;
 
-  /// VirtRegAuxInfo - Calculate auxiliary information for a virtual
-  /// register such as its spill weight and allocation hint.
+  /// \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()
+  /// @param NumInstr   Number of instructions using this live interval
+  ///
+  static inline float normalizeSpillWeight(float UseDefFreq, unsigned Size,
+                                           unsigned NumInstr) {
+    // 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 {
-    MachineFunction &mf_;
-    LiveIntervals &lis_;
-    const MachineLoopInfo &loops_;
-    DenseMap<unsigned, float> hint_;
   public:
-    VirtRegAuxInfo(MachineFunction &mf, LiveIntervals &lis,
-                   const MachineLoopInfo &loops) :
-      mf_(mf), lis_(lis), loops_(loops) {}
-
-    /// CalculateRegClass - recompute the register class for li from its uses.
-    /// Since the register class can affect the allocation hint, this function
-    /// should be called before CalculateWeightAndHint if both are called.
-    void CalculateRegClass(LiveInterval &li);
+    typedef float (*NormalizingFn)(float, unsigned, unsigned);
 
-    /// CalculateWeightAndHint - (re)compute li's spill weight and allocation
-    /// hint.
-    void CalculateWeightAndHint(LiveInterval &li);
-  };
+  private:
+    MachineFunction &MF;
+    LiveIntervals &LIS;
+    const MachineLoopInfo &Loops;
+    const MachineBlockFrequencyInfo &MBFI;
+    DenseMap<unsigned, float> Hint;
+    NormalizingFn normalize;
 
-  /// CalculateSpillWeights - Compute spill weights for all virtual register
-  /// live intervals.
-  class CalculateSpillWeights : public MachineFunctionPass {
   public:
-    static char ID;
-
-    CalculateSpillWeights() : MachineFunctionPass(ID) {}
-
-    virtual void getAnalysisUsage(AnalysisUsage &au) const;
-
-    virtual bool runOnMachineFunction(MachineFunction &fn);
+    VirtRegAuxInfo(MachineFunction &mf, LiveIntervals &lis,
+                   const MachineLoopInfo &loops,
+                   const MachineBlockFrequencyInfo &mbfi,
+                   NormalizingFn norm = normalizeSpillWeight)
+        : MF(mf), LIS(lis), Loops(loops), MBFI(mbfi), normalize(norm) {}
 
-  private:
-    /// Returns true if the given live interval is zero length.
-    bool isZeroLengthInterval(LiveInterval *li) const;
+    /// \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);
+} // namespace llvm
 
 #endif // LLVM_CODEGEN_CALCSPILLWEIGHTS_H