133 lines
4.1 KiB
C++
133 lines
4.1 KiB
C++
/*
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* Copyright (c) 2004-2005 The Regents of The University of Michigan
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef __BPRED_UNIT_HH__
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#define __BPRED_UNIT_HH__
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// For Addr type.
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#include "arch/alpha/isa_traits.hh"
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#include "base/statistics.hh"
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#include "cpu/inst_seq.hh"
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#include "cpu/beta_cpu/2bit_local_pred.hh"
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#include "cpu/beta_cpu/tournament_pred.hh"
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#include "cpu/beta_cpu/btb.hh"
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#include "cpu/beta_cpu/ras.hh"
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#include <list>
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/**
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* Basically a wrapper class to hold both the branch predictor
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* and the BTB. Right now I'm unsure of the implementation; it would
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* be nicer to have something closer to the CPUPolicy or the Impl where
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* this is just typedefs, but it forces the upper level stages to be
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* aware of the constructors of the BP and the BTB. The nicer thing
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* to do is have this templated on the Impl, accept the usual Params
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* object, and be able to call the constructors on the BP and BTB.
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*/
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template<class Impl>
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class TwobitBPredUnit
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{
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public:
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typedef typename Impl::Params Params;
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typedef typename Impl::DynInstPtr DynInstPtr;
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TwobitBPredUnit(Params ¶ms);
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void regStats();
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bool predict(DynInstPtr &inst, Addr &PC);
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void update(const InstSeqNum &done_sn);
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void squash(const InstSeqNum &squashed_sn);
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void squash(const InstSeqNum &squashed_sn, const Addr &corr_target,
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bool actually_taken);
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bool BPLookup(Addr &inst_PC)
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{ return BP.lookup(inst_PC); }
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bool BTBValid(Addr &inst_PC)
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{ return BTB.valid(inst_PC); }
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Addr BTBLookup(Addr &inst_PC)
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{ return BTB.lookup(inst_PC); }
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// Will want to include global history.
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void BPUpdate(Addr &inst_PC, bool taken)
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{ BP.update(inst_PC, taken); }
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void BTBUpdate(Addr &inst_PC, Addr &target_PC)
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{ BTB.update(inst_PC, target_PC); }
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private:
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struct PredictorHistory {
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PredictorHistory(const InstSeqNum &seq_num, const Addr &inst_PC,
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const bool pred_taken)
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: seqNum(seq_num), PC(inst_PC), predTaken(pred_taken),
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globalHistory(0), usedRAS(0), wasCall(0), RASIndex(0),
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RASTarget(0)
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{ }
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InstSeqNum seqNum;
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Addr PC;
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bool predTaken;
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unsigned globalHistory;
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bool usedRAS;
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bool wasCall;
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unsigned RASIndex;
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Addr RASTarget;
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};
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std::list<PredictorHistory> predHist;
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DefaultBP BP;
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DefaultBTB BTB;
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ReturnAddrStack RAS;
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Stats::Scalar<> lookups;
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Stats::Scalar<> condPredicted;
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Stats::Scalar<> condIncorrect;
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Stats::Scalar<> BTBLookups;
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Stats::Scalar<> BTBHits;
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Stats::Scalar<> BTBCorrect;
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Stats::Scalar<> usedRAS;
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Stats::Scalar<> RASIncorrect;
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};
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#endif // __BPRED_UNIT_HH__
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