bpred_unit.hh revision 1689
1/* 2 * Copyright (c) 2004-2005 The Regents of The University of Michigan 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions are 7 * met: redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer; 9 * redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution; 12 * neither the name of the copyright holders nor the names of its 13 * contributors may be used to endorse or promote products derived from 14 * this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29#ifndef __BPRED_UNIT_HH__ 30#define __BPRED_UNIT_HH__ 31 32// For Addr type. 33#include "arch/alpha/isa_traits.hh" 34#include "base/statistics.hh" 35#include "cpu/inst_seq.hh" 36 37#include "cpu/beta_cpu/2bit_local_pred.hh" 38#include "cpu/beta_cpu/tournament_pred.hh" 39#include "cpu/beta_cpu/btb.hh" 40#include "cpu/beta_cpu/ras.hh" 41 42#include <list> 43 44/** 45 * Basically a wrapper class to hold both the branch predictor 46 * and the BTB. Right now I'm unsure of the implementation; it would 47 * be nicer to have something closer to the CPUPolicy or the Impl where 48 * this is just typedefs, but it forces the upper level stages to be 49 * aware of the constructors of the BP and the BTB. The nicer thing 50 * to do is have this templated on the Impl, accept the usual Params 51 * object, and be able to call the constructors on the BP and BTB. 52 */ 53template<class Impl> 54class TwobitBPredUnit 55{ 56 public: 57 typedef typename Impl::Params Params; 58 typedef typename Impl::DynInstPtr DynInstPtr; 59 60 TwobitBPredUnit(Params ¶ms); 61 62 void regStats(); 63 64 bool predict(DynInstPtr &inst, Addr &PC); 65 66 void update(const InstSeqNum &done_sn); 67 68 void squash(const InstSeqNum &squashed_sn); 69 70 void squash(const InstSeqNum &squashed_sn, const Addr &corr_target, 71 bool actually_taken); 72 73 bool BPLookup(Addr &inst_PC) 74 { return BP.lookup(inst_PC); } 75 76 bool BTBValid(Addr &inst_PC) 77 { return BTB.valid(inst_PC); } 78 79 Addr BTBLookup(Addr &inst_PC) 80 { return BTB.lookup(inst_PC); } 81 82 // Will want to include global history. 83 void BPUpdate(Addr &inst_PC, bool taken) 84 { BP.update(inst_PC, taken); } 85 86 void BTBUpdate(Addr &inst_PC, Addr &target_PC) 87 { BTB.update(inst_PC, target_PC); } 88 89 private: 90 struct PredictorHistory { 91 PredictorHistory(const InstSeqNum &seq_num, const Addr &inst_PC, 92 const bool pred_taken) 93 : seqNum(seq_num), PC(inst_PC), predTaken(pred_taken), 94 globalHistory(0), usedRAS(0), wasCall(0), RASIndex(0), 95 RASTarget(0) 96 { } 97 98 InstSeqNum seqNum; 99 100 Addr PC; 101 102 bool predTaken; 103 104 unsigned globalHistory; 105 106 bool usedRAS; 107 108 bool wasCall; 109 110 unsigned RASIndex; 111 112 Addr RASTarget; 113 }; 114 115 std::list<PredictorHistory> predHist; 116 117 DefaultBP BP; 118 119 DefaultBTB BTB; 120 121 ReturnAddrStack RAS; 122 123 Stats::Scalar<> lookups; 124 Stats::Scalar<> condPredicted; 125 Stats::Scalar<> condIncorrect; 126 Stats::Scalar<> BTBLookups; 127 Stats::Scalar<> BTBHits; 128 Stats::Scalar<> BTBCorrect; 129 Stats::Scalar<> usedRAS; 130 Stats::Scalar<> RASIncorrect; 131}; 132 133#endif // __BPRED_UNIT_HH__ 134