src/cpu/pred/multiperspective_perceptron_tage.hh

   1 /*
   2  * Copyright 2019 Texas A&M University
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions are met:
   6  *
   7  * 1. Redistributions of source code must retain the above copyright notice,
   8  *    this list of conditions and the following disclaimer.
   9  *
  10  * 2. Redistributions in binary form must reproduce the above copyright notice,
  11  *    this list of conditions and the following disclaimer in the documentation
  12  *    and/or other materials provided with the distribution.
  13  *
  14  * 3. Neither the name of the copyright holder nor the names of its
  15  *    contributors may be used to endorse or promote products derived from this
  16  *    software without specific prior written permission.
  17  *
  18  *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19  *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20  *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  21  *  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  22  *  HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  23  *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  24  *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25  *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26  *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27  *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  28  *  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  *
  30  *  Author: Daniel A. Jiménez
  31  *  Adapted to gem5 by: Javier Bueno Hedo
  32  *
  33  */
  34
  35 /*
  36  * Multiperspective Perceptron Predictor with TAGE (by Daniel A. Jiménez)
  37  */
  38
  39 #ifndef __CPU_PRED_MULTIPERSPECTIVE_PERCEPTRON_TAGE_HH__
  40 #define __CPU_PRED_MULTIPERSPECTIVE_PERCEPTRON_TAGE_HH__
  41
  42 #include "cpu/pred/loop_predictor.hh"
  43 #include "cpu/pred/multiperspective_perceptron.hh"
  44 #include "cpu/pred/statistical_corrector.hh"
  45 #include "cpu/pred/tage_base.hh"
  46 #include "params/MPP_LoopPredictor.hh"
  47 #include "params/MPP_StatisticalCorrector.hh"
  48 #include "params/MPP_TAGE.hh"
  49 #include "params/MultiperspectivePerceptronTAGE.hh"
  50
  51 class MPP_TAGE : public TAGEBase {
  52     std::vector<unsigned int> tunedHistoryLengths;
  53   public:
  54     struct BranchInfo : public TAGEBase::BranchInfo {
  55         BranchInfo(TAGEBase &tage) : TAGEBase::BranchInfo(tage)
  56         {}
  57         virtual ~BranchInfo()
  58         {}
  59     };
  60
  61     MPP_TAGE(const MPP_TAGEParams *p) : TAGEBase(p),
  62         tunedHistoryLengths(p->tunedHistoryLengths)
  63     {}
  64
  65     void calculateParameters() override;
  66     void handleTAGEUpdate(Addr branch_pc, bool taken, TAGEBase::BranchInfo* bi)
  67         override;
  68     void handleAllocAndUReset(bool alloc, bool taken, TAGEBase::BranchInfo* bi,
  69                               int nrand) override;
  70     void handleUReset() override;
  71     void resetUctr(uint8_t &u) override;
  72     int bindex(Addr pc_in) const override;
  73     bool isHighConfidence(TAGEBase::BranchInfo *bi) const override;
  74
  75     unsigned getUseAltIdx(TAGEBase::BranchInfo* bi, Addr branch_pc) override;
  76     void adjustAlloc(bool & alloc, bool taken, bool pred_taken) override;
  77     void updateHistories(ThreadID tid, Addr branch_pc, bool taken,
  78                          TAGEBase::BranchInfo* b, bool speculative,
  79                          const StaticInstPtr &inst, Addr target) override;
  80
  81     void updatePathAndGlobalHistory(ThreadHistory& tHist, int brtype,
  82                                     bool taken, Addr branch_pc, Addr target);
  83 };
  84
  85 class MPP_LoopPredictor : public LoopPredictor {
  86   public:
  87     MPP_LoopPredictor(MPP_LoopPredictorParams *p) : LoopPredictor(p)
  88     {}
  89
  90     bool calcConf(int index) const override;
  91     bool optionalAgeInc() const override;
  92 };
  93
  94 class MPP_StatisticalCorrector : public StatisticalCorrector {
  95   protected:
  96     int8_t thirdH;
  97     // global branch history variation GEHL
  98     const unsigned pnb;
  99     const unsigned logPnb;
 100     std::vector<int> pm;
 101     std::vector<int8_t> * pgehl;
 102     std::vector<int8_t> wp;
 103
 104     // global branch history GEHL
 105     const unsigned gnb;
 106     const unsigned logGnb;
 107     std::vector<int> gm;
 108     std::vector<int8_t> * ggehl;
 109     std::vector<int8_t> wg;
 110
 111     struct MPP_SCThreadHistory : public StatisticalCorrector::SCThreadHistory
 112     {
 113         MPP_SCThreadHistory() : globalHist(0), historyStack(16, 0),
 114             historyStackPointer(0) {}
 115         int64_t globalHist; // global history
 116         std::vector<int64_t> historyStack;
 117         unsigned int historyStackPointer;
 118
 119         int64_t getHistoryStackEntry() const
 120         {
 121             return historyStack[historyStackPointer];
 122         }
 123
 124         void updateHistoryStack(Addr target, bool taken, bool is_call,
 125                                 bool is_return)
 126         {
 127             unsigned int truncated_target = target;
 128             historyStack[historyStackPointer] =
 129                 (historyStack[historyStackPointer] << 1) ^ (truncated_target ^
 130                 (truncated_target >> 5) ^ taken);
 131             if (is_return) {
 132                 historyStackPointer = (historyStackPointer - 1) %
 133                     historyStack.size();
 134             }
 135             if (is_call) {
 136                 int index = (historyStackPointer + 1) % historyStack.size();
 137                 historyStack[index] = historyStack[historyStackPointer];
 138                 historyStackPointer = index;
 139             }
 140         }
 141         unsigned int getPointer() const { return historyStackPointer; }
 142     };
 143
 144   public:
 145     struct BranchInfo : public StatisticalCorrector::BranchInfo {
 146         virtual ~BranchInfo()
 147         {}
 148     };
 149     MPP_StatisticalCorrector(const MPP_StatisticalCorrectorParams *p);
 150
 151     void initBias() override;
 152     unsigned getIndBias(Addr branch_pc, StatisticalCorrector::BranchInfo* bi,
 153                         bool bias) const override;
 154     unsigned getIndBiasSK(Addr branch_pc, StatisticalCorrector::BranchInfo* bi)
 155             const override;
 156     unsigned getIndBiasBank(Addr branch_pc,
 157                             StatisticalCorrector::BranchInfo* bi, int hitBank,
 158                             int altBank) const override;
 159     unsigned getIndUpd(Addr branch_pc) const override;
 160     int gIndexLogsSubstr(int nbr, int i) override;
 161
 162     bool scPredict(ThreadID tid, Addr branch_pc, bool cond_branch,
 163                    StatisticalCorrector::BranchInfo* bi, bool prev_pred_taken,
 164                    bool bias_bit, bool use_conf_ctr, int8_t conf_ctr,
 165                    unsigned conf_bits, int hitBank, int altBank, int64_t phist,
 166                    int init_lsum) override;
 167
 168     void condBranchUpdate(ThreadID tid, Addr branch_pc, bool taken,
 169                           StatisticalCorrector::BranchInfo *bi,
 170                           Addr corrTarget, bool b, int hitBank, int altBank,
 171                           int64_t phist) override;
 172
 173     virtual void getBiasLSUM(Addr branch_pc,
 174             StatisticalCorrector::BranchInfo *bi, int &lsum) const = 0;
 175
 176     void gUpdate(
 177         Addr branch_pc, bool taken, int64_t hist, std::vector<int> & length,
 178         std::vector<int8_t> * tab, int nbr, int logs,
 179         std::vector<int8_t> &w, StatisticalCorrector::BranchInfo* bi) override;
 180 };
 181
 182 class MultiperspectivePerceptronTAGE : public MultiperspectivePerceptron
 183 {
 184     TAGEBase *tage;
 185     LoopPredictor *loopPredictor;
 186     StatisticalCorrector *statisticalCorrector;
 187
 188     /**
 189      * Branch information data type
 190      */
 191     struct MPPTAGEBranchInfo : public MPPBranchInfo
 192     {
 193         TAGEBase::BranchInfo *tageBranchInfo;
 194         LoopPredictor::BranchInfo *lpBranchInfo;
 195         StatisticalCorrector::BranchInfo *scBranchInfo;
 196         bool predictedTaken;
 197         MPPTAGEBranchInfo(Addr pc, int pcshift, bool cond, TAGEBase &tage,
 198                           LoopPredictor &loopPredictor,
 199                           StatisticalCorrector &statisticalCorrector)
 200           : MPPBranchInfo(pc, pcshift, cond),
 201             tageBranchInfo(tage.makeBranchInfo()),
 202             lpBranchInfo(loopPredictor.makeBranchInfo()),
 203             scBranchInfo(statisticalCorrector.makeBranchInfo()),
 204             predictedTaken(false)
 205         {}
 206         virtual ~MPPTAGEBranchInfo()
 207         {
 208             delete tageBranchInfo;
 209             delete lpBranchInfo;
 210             delete scBranchInfo;
 211         }
 212     };
 213
 214     unsigned int getIndex(ThreadID tid, MPPTAGEBranchInfo &bi,
 215                           const HistorySpec &spec, int index) const;
 216     int computePartialSum(ThreadID tid, MPPTAGEBranchInfo &bi) const;
 217     void updatePartial(ThreadID tid, MPPTAGEBranchInfo &bi, bool taken);
 218     void updateHistories(ThreadID tid, MPPTAGEBranchInfo &bi, bool taken);
 219
 220   public:
 221     MultiperspectivePerceptronTAGE(
 222         const MultiperspectivePerceptronTAGEParams *p);
 223
 224     void init() override;
 225
 226     bool lookup(ThreadID tid, Addr instPC, void * &bp_history) override;
 227
 228     void update(ThreadID tid, Addr instPC, bool taken,
 229             void *bp_history, bool squashed,
 230             const StaticInstPtr & inst,
 231             Addr corrTarget = MaxAddr) override;
 232     void uncondBranch(ThreadID tid, Addr pc, void * &bp_history) override;
 233     void squash(ThreadID tid, void *bp_history) override;
 234
 235 };
 236 #endif//__CPU_PRED_MULTIPERSPECTIVE_PERCEPTRON_TAGE_HH__