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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,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef __CPU_O3_CPU_TOURNAMENT_PRED_HH__
#define __CPU_O3_CPU_TOURNAMENT_PRED_HH__
// For Addr type.
#include "arch/isa_traits.hh"
#include "cpu/o3/sat_counter.hh"
class TournamentBP
{
protected:
typedef TheISA::Addr Addr;
public:
/**
* Default branch predictor constructor.
*/
TournamentBP(unsigned local_predictor_size,
unsigned local_ctr_bits,
unsigned local_history_table_size,
unsigned local_history_bits,
unsigned global_predictor_size,
unsigned global_history_bits,
unsigned global_ctr_bits,
unsigned choice_predictor_size,
unsigned choice_ctr_bits,
unsigned instShiftAmt);
/**
* Looks up the given address in the branch predictor and returns
* a true/false value as to whether it is taken.
* @param branch_addr The address of the branch to look up.
* @return Whether or not the branch is taken.
*/
bool lookup(Addr &branch_addr);
/**
* Updates the branch predictor with the actual result of a branch.
* @param branch_addr The address of the branch to update.
* @param taken Whether or not the branch was taken.
*/
void update(Addr &branch_addr, unsigned global_history, bool taken);
inline unsigned readGlobalHist() { return globalHistory; }
private:
inline bool getPrediction(uint8_t &count);
inline unsigned calcLocHistIdx(Addr &branch_addr);
inline void updateHistoriesTaken(unsigned local_history_idx);
inline void updateHistoriesNotTaken(unsigned local_history_idx);
/** Local counters. */
SatCounter *localCtrs;
/** Size of the local predictor. */
unsigned localPredictorSize;
/** Number of bits of the local predictor's counters. */
unsigned localCtrBits;
/** Array of local history table entries. */
unsigned *localHistoryTable;
/** Size of the local history table. */
unsigned localHistoryTableSize;
/** Number of bits for each entry of the local history table.
* @todo Doesn't this come from the size of the local predictor?
*/
unsigned localHistoryBits;
/** Mask to get the proper local history. */
unsigned localHistoryMask;
/** Array of counters that make up the global predictor. */
SatCounter *globalCtrs;
/** Size of the global predictor. */
unsigned globalPredictorSize;
/** Number of bits of the global predictor's counters. */
unsigned globalCtrBits;
/** Global history register. */
unsigned globalHistory;
/** Number of bits for the global history. */
unsigned globalHistoryBits;
/** Mask to get the proper global history. */
unsigned globalHistoryMask;
/** Array of counters that make up the choice predictor. */
SatCounter *choiceCtrs;
/** Size of the choice predictor (identical to the global predictor). */
unsigned choicePredictorSize;
/** Number of bits of the choice predictor's counters. */
unsigned choiceCtrBits;
/** Number of bits to shift the instruction over to get rid of the word
* offset.
*/
unsigned instShiftAmt;
/** Threshold for the counter value; above the threshold is taken,
* equal to or below the threshold is not taken.
*/
unsigned threshold;
};
#endif // __CPU_O3_CPU_TOURNAMENT_PRED_HH__
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