misched: rename ScheduleDAGILP to ScheduleDFS to prepare for other heuristics.

[oota-llvm.git] / include / llvm / CodeGen / CalcSpillWeights.h

diff --git a/include/llvm/CodeGen/CalcSpillWeights.h b/include/llvm/CodeGen/CalcSpillWeights.h
index e5273c549778811a73d1a713e981a39c30903676..2f76a6cc5583d86713188b447525f8f4dab3f680 100644 (file)
--- a/include/llvm/CodeGen/CalcSpillWeights.h
+++ b/include/llvm/CodeGen/CalcSpillWeights.h
@@ -11,11 +11,48 @@
 #ifndef LLVM_CODEGEN_CALCSPILLWEIGHTS_H
 #define LLVM_CODEGEN_CALCSPILLWEIGHTS_H
 
-#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/SlotIndexes.h"
+#include "llvm/ADT/DenseMap.h"
 
 namespace llvm {
 
   class LiveInterval;
+  class LiveIntervals;
+  class MachineLoopInfo;
+
+  /// normalizeSpillWeight - 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);
+  }
+
+  /// VirtRegAuxInfo - 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) {}
+
+    /// CalculateWeightAndHint - (re)compute li's spill weight and allocation
+    /// hint.
+    void CalculateWeightAndHint(LiveInterval &li);
+  };
 
   /// CalculateSpillWeights - Compute spill weights for all virtual register
   /// live intervals.
@@ -23,11 +60,13 @@ namespace llvm {
   public:
     static char ID;
 
-    CalculateSpillWeights() : MachineFunctionPass(ID) {}
+    CalculateSpillWeights() : MachineFunctionPass(ID) {
+      initializeCalculateSpillWeightsPass(*PassRegistry::getPassRegistry());
+    }
 
     virtual void getAnalysisUsage(AnalysisUsage &au) const;
 
-    virtual bool runOnMachineFunction(MachineFunction &fn);    
+    virtual bool runOnMachineFunction(MachineFunction &fn);
 
   private:
     /// Returns true if the given live interval is zero length.