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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.
*
* Authors: Kevin Lim
*/
#ifndef __BPRED_UNIT_HH__
#define __BPRED_UNIT_HH__
// For Addr type.
#include "arch/isa_traits.hh"
#include "base/statistics.hh"
#include "cpu/inst_seq.hh"
#include "cpu/o3/2bit_local_pred.hh"
#include "cpu/o3/tournament_pred.hh"
#include "cpu/o3/btb.hh"
#include "cpu/o3/ras.hh"
#include <list>
/**
* Basically a wrapper class to hold both the branch predictor
* and the BTB. Right now I'm unsure of the implementation; it would
* be nicer to have something closer to the CPUPolicy or the Impl where
* this is just typedefs, but it forces the upper level stages to be
* aware of the constructors of the BP and the BTB. The nicer thing
* to do is have this templated on the Impl, accept the usual Params
* object, and be able to call the constructors on the BP and BTB.
*/
template<class Impl>
class TwobitBPredUnit
{
public:
typedef typename Impl::Params Params;
typedef typename Impl::DynInstPtr DynInstPtr;
TwobitBPredUnit(Params ¶ms);
void regStats();
bool predict(DynInstPtr &inst, Addr &PC);
void update(const InstSeqNum &done_sn);
void squash(const InstSeqNum &squashed_sn);
void squash(const InstSeqNum &squashed_sn, const Addr &corr_target,
bool actually_taken);
bool BPLookup(Addr &inst_PC)
{ return BP.lookup(inst_PC); }
bool BTBValid(Addr &inst_PC)
{ return BTB.valid(inst_PC); }
Addr BTBLookup(Addr &inst_PC)
{ return BTB.lookup(inst_PC); }
// Will want to include global history.
void BPUpdate(Addr &inst_PC, bool taken)
{ BP.update(inst_PC, taken); }
void BTBUpdate(Addr &inst_PC, Addr &target_PC)
{ BTB.update(inst_PC, target_PC); }
private:
struct PredictorHistory {
PredictorHistory(const InstSeqNum &seq_num, const Addr &inst_PC,
const bool pred_taken)
: seqNum(seq_num), PC(inst_PC), predTaken(pred_taken),
globalHistory(0), usedRAS(0), wasCall(0), RASIndex(0),
RASTarget(0)
{ }
InstSeqNum seqNum;
Addr PC;
bool predTaken;
unsigned globalHistory;
bool usedRAS;
bool wasCall;
unsigned RASIndex;
Addr RASTarget;
};
std::list<PredictorHistory> predHist;
DefaultBP BP;
DefaultBTB BTB;
ReturnAddrStack RAS;
Stats::Scalar<> lookups;
Stats::Scalar<> condPredicted;
Stats::Scalar<> condIncorrect;
Stats::Scalar<> BTBLookups;
Stats::Scalar<> BTBHits;
Stats::Scalar<> BTBCorrect;
Stats::Scalar<> usedRAS;
Stats::Scalar<> RASIncorrect;
};
#endif // __BPRED_UNIT_HH__
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