gshare.hh

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/*
 * Copyright (c) 2024-2025 REDS-HEIG-VD and ESL-EPFL
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/* @file
 * Implementation of a gshare branch predictor
 */
 
#ifndef __CPU_PRED_GSHARE_PRED_HH__
#define __CPU_PRED_GSHARE_PRED_HH__
 
#include "base/sat_counter.hh"
#include "cpu/pred/bpred_unit.hh"
#include "params/GshareBP.hh"
 
namespace gem5
{
 
namespace branch_prediction
{

 
class GshareBP : public BPredUnit
{
  public:
    GshareBP(const GshareBPParams &params);
    bool lookup(ThreadID tid, Addr pc, void *&bp_history);
    void updateHistories(ThreadID tid, Addr pc, bool uncond, bool taken,
                         Addr target, const StaticInstPtr &inst,
                         void *&bp_history);
    void squash(ThreadID tid, void *&bp_history);
    void update(ThreadID tid, Addr pc, bool taken, void *&bp_history,
                bool squashed, const StaticInstPtr &inst, Addr target);
 
  private:
    void updateGlobalHistReg(ThreadID tid, bool taken);
    void uncondBranch(ThreadID tid, Addr pc, void *&bp_history);
 
    struct BPHistory
    {
        unsigned globalHistoryReg;
        bool finalPred;
    };
 
    std::vector<unsigned> globalHistoryReg;
    unsigned globalHistoryBits;
    unsigned historyRegisterMask;
 
    unsigned globalPredictorSize;
    unsigned globalCtrBits;
    unsigned globalHistoryMask;
 
    std::vector<SatCounter8> globalCtrs;
    unsigned takenThreshold;
};
 
} // namespace branch_prediction
} // namespace gem5
#endif // __CPU_PRED_GSHARE_PRED_HH__