ras.hh

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#ifndef __CPU_PRED_RAS_HH__
#define __CPU_PRED_RAS_HH__
 
#include <vector>
 
#include "arch/generic/pcstate.hh"
#include "base/statistics.hh"
#include "base/types.hh"
#include "cpu/pred/branch_type.hh"
#include "cpu/static_inst.hh"
#include "params/ReturnAddrStack.hh"
#include "sim/sim_object.hh"
 
namespace gem5
{
 
namespace branch_prediction
{
 
class ReturnAddrStack : public SimObject
{
  public:
 
    class AddrStack
    {
      public:
        AddrStack(ReturnAddrStack &_parent)
          : parent(_parent)
        {}
 
 
      void init(unsigned numEntries);
 
      void reset();
 
      const PCStateBase *top();
 
      unsigned topIdx() { return tos; }
 
      void push(const PCStateBase &return_addr);
 
      void pop();
 
      void restore(unsigned top_of_stack, const PCStateBase *restored);
 
      bool empty() { return usedEntries == 0; }
 
      bool full() { return usedEntries >= numEntries; }
 
      std::string toString(int n);
 
      inline void
      incrTos()
      {
          if (++tos == numEntries)
              tos = 0;
      }
 
      inline void
      decrTos()
      {
          tos = (tos == 0 ? numEntries - 1 : tos - 1);
      }
 
      std::vector<std::unique_ptr<PCStateBase>> addrStack;
 
      unsigned numEntries;
 
      unsigned usedEntries;
 
      unsigned tos;
 
      protected:
        ReturnAddrStack &parent;
    };
 
 
 
  public:
    // typedef RASParams Params;
    typedef ReturnAddrStackParams Params;
 
    // ReturnAddrStack(BPredUnit &_parent, const RASParams);
    ReturnAddrStack(const Params &p);
 
    void reset();
 
    void push(ThreadID tid, const PCStateBase &pc, void * &ras_history);
 
    const PCStateBase* pop(ThreadID tid, void * &ras_history);
 
    void squash(ThreadID tid, void * &ras_history);
 
    void commit(ThreadID tid, bool misp,
                const BranchType brType, void * &ras_history);
 
  private:
 
    class RASHistory
    {
      public:
        /* Was the RAS pushed or poped for this branch. */
        bool pushed = false;
        bool poped = false;
        /* Was it a call */
        bool wasReturn = false;
        bool wasCall = false;
        std::unique_ptr<PCStateBase> ras_entry;
        unsigned tos = 0;
    };
 
    void makeRASHistory(void* &ras_history);
 
    std::vector<AddrStack> addrStacks;
 
    unsigned numEntries;
    unsigned numThreads;
 
    struct ReturnAddrStackStats : public statistics::Group
    {
        ReturnAddrStackStats(statistics::Group *parent);
        statistics::Scalar pushes;
        statistics::Scalar pops;
        statistics::Scalar squashes;
        statistics::Scalar used;
        statistics::Scalar correct;
        statistics::Scalar incorrect;
    } stats;
};
 
} // namespace branch_prediction
} // namespace gem5
 
#endif // __CPU_PRED_RAS_HH__