simple_btb.hh

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#ifndef __CPU_PRED_SIMPLE_BTB_HH__
#define __CPU_PRED_SIMPLE_BTB_HH__
 
#include "base/logging.hh"
#include "base/types.hh"
#include "cpu/pred/btb.hh"
#include "params/SimpleBTB.hh"
 
namespace gem5
{
 
namespace branch_prediction
{
 
class SimpleBTB : public BranchTargetBuffer
{
  public:
    SimpleBTB(const SimpleBTBParams &params);
 
    void memInvalidate() override;
    bool valid(ThreadID tid, Addr instPC) override;
    const PCStateBase *lookup(ThreadID tid, Addr instPC,
                           BranchType type = BranchType::NoBranch) override;
    void update(ThreadID tid, Addr instPC, const PCStateBase &target_pc,
                           BranchType type = BranchType::NoBranch,
                           StaticInstPtr inst = nullptr) override;
    const StaticInstPtr getInst(ThreadID tid, Addr instPC) override;
 
 
  private:
    struct BTBEntry
    {
        Addr tag = 0;
 
        std::unique_ptr<PCStateBase> target;
 
        ThreadID tid;
 
        bool valid = false;
 
        StaticInstPtr inst = nullptr;
    };
 
 
    inline unsigned getIndex(Addr instPC, ThreadID tid);
 
    inline Addr getTag(Addr instPC);
 
    BTBEntry *findEntry(Addr instPC, ThreadID tid);
 
    std::vector<BTBEntry> btb;
 
    unsigned numEntries;
 
    unsigned idxMask;
 
    unsigned tagBits;
 
    unsigned tagMask;
 
    unsigned instShiftAmt;
 
    unsigned tagShiftAmt;
 
    unsigned log2NumThreads;
};
 
} // namespace branch_prediction
} // namespace gem5
 
#endif // __CPU_PRED_SIMPLE_BTB_HH__