btb.hh

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/*
 * Copyright (c) 2004-2005 The Regents of The University of Michigan
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 */

#ifndef __CPU_PRED_BTB_HH__
#define __CPU_PRED_BTB_HH__

#include "arch/types.hh"
#include "base/logging.hh"
#include "base/types.hh"
#include "config/the_isa.hh"

class DefaultBTB
{
  private:
    struct BTBEntry
    {
        BTBEntry()
            : tag(0), target(0), valid(false)
        {}

        Addr tag;

        TheISA::PCState target;

        ThreadID tid;

        bool valid;
    };

  public:
    DefaultBTB(unsigned numEntries, unsigned tagBits,
               unsigned instShiftAmt, unsigned numThreads);

    void reset();

    TheISA::PCState lookup(Addr instPC, ThreadID tid);

    bool valid(Addr instPC, ThreadID tid);

    void update(Addr instPC, const TheISA::PCState &targetPC,
                ThreadID tid);

  private:
    inline unsigned getIndex(Addr instPC, ThreadID tid);

    inline Addr getTag(Addr instPC);

    std::vector<BTBEntry> btb;

    unsigned numEntries;

    unsigned idxMask;

    unsigned tagBits;

    unsigned tagMask;

    unsigned instShiftAmt;

    unsigned tagShiftAmt;

    unsigned log2NumThreads;
};

#endif // __CPU_PRED_BTB_HH__