tournament.hh

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/*
 * Copyright (c) 2011, 2014 ARM Limited
 * Copyright (c) 2022-2023 The University of Edinburgh
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 *
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 * property including but not limited to intellectual property relating
 * to a hardware implementation of the functionality of the software
 * licensed hereunder.  You may use the software subject to the license
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 * modified or unmodified, in source code or in binary form.
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#ifndef __CPU_PRED_TOURNAMENT_PRED_HH__
#define __CPU_PRED_TOURNAMENT_PRED_HH__
 
#include <vector>
 
#include "base/sat_counter.hh"
#include "base/types.hh"
#include "cpu/pred/bpred_unit.hh"
#include "params/TournamentBP.hh"
 
namespace gem5
{
 
namespace branch_prediction
{

class TournamentBP : public BPredUnit
{
  public:
    TournamentBP(const TournamentBPParams &params);
 
    // Base class methods.
    bool lookup(ThreadID tid, Addr pc, void* &bp_history) override;
    void updateHistories(ThreadID tid, Addr pc, bool uncond, bool taken,
                         Addr target, const StaticInstPtr &inst,
                         void * &bp_history) override;
    void update(ThreadID tid, Addr pc, bool taken, void * &bp_history,
                bool squashed, const StaticInstPtr & inst,
                Addr target) override;
    void squash(ThreadID tid, void * &bp_history) override;
 
  private:
    inline bool getPrediction(uint8_t &count);

    inline unsigned calcLocHistIdx(Addr &branch_addr);

    inline void updateGlobalHist(ThreadID tid, bool taken);

    inline void updateLocalHist(unsigned local_history_idx, bool taken);

    struct BPHistory
    {
#ifdef GEM5_DEBUG
        BPHistory()
        { newCount++; }
        ~BPHistory()
        { newCount--; }
 
        static int newCount;
#endif
        unsigned globalHistory;
        unsigned localHistoryIdx;
        unsigned localHistory;
        bool localPredTaken;
        bool globalPredTaken;
        bool globalUsed;
    };

    static const int invalidPredictorIndex = -1;
    unsigned localPredictorSize;

    unsigned localPredictorMask;

    unsigned localCtrBits;

    std::vector<SatCounter8> localCtrs;

    std::vector<unsigned> localHistoryTable;

    unsigned localHistoryTableSize;

    unsigned localHistoryBits;

    unsigned globalPredictorSize;

    unsigned globalCtrBits;

    std::vector<SatCounter8> globalCtrs;

    std::vector<unsigned> globalHistory;

    unsigned globalHistoryBits;

    unsigned globalHistoryMask;

    unsigned choiceHistoryMask;

    unsigned historyRegisterMask;

    unsigned choicePredictorSize;

    unsigned choiceCtrBits;

    std::vector<SatCounter8> choiceCtrs;

    unsigned localThreshold;
    unsigned globalThreshold;
    unsigned choiceThreshold;
};
 
} // namespace branch_prediction
} // namespace gem5
 
#endif // __CPU_PRED_TOURNAMENT_PRED_HH__