+ 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);
+ };