#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;
- /// CalculateSpillWeights - Compute spill weights for all virtual register
- /// live intervals.
- class CalculateSpillWeights : public MachineFunctionPass {
- public:
- static char ID;
+ /// \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);
+ }
- CalculateSpillWeights() : MachineFunctionPass(&ID) {}
+ /// \brief Calculate auxiliary information for a virtual register such as its
+ /// spill weight and allocation hint.
+ class VirtRegAuxInfo {
+ public:
+ typedef float (*NormalizingFn)(float, unsigned, unsigned);
- virtual void getAnalysisUsage(AnalysisUsage &au) const;
+ private:
+ MachineFunction &MF;
+ LiveIntervals &LIS;
+ const MachineLoopInfo &Loops;
+ const MachineBlockFrequencyInfo &MBFI;
+ DenseMap<unsigned, float> Hint;
+ NormalizingFn normalize;
- virtual bool runOnMachineFunction(MachineFunction &fn);
+ 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) {}
- 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);
}
#endif // LLVM_CODEGEN_CALCSPILLWEIGHTS_H