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Diffstat (limited to 'cpu/o3/bpred_unit_impl.hh')
| -rw-r--r-- | cpu/o3/bpred_unit_impl.hh | 410 |
1 files changed, 0 insertions, 410 deletions
diff --git a/cpu/o3/bpred_unit_impl.hh b/cpu/o3/bpred_unit_impl.hh deleted file mode 100644 index 1844c155e..000000000 --- a/cpu/o3/bpred_unit_impl.hh +++ /dev/null @@ -1,410 +0,0 @@ -/* - * 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. - */ - -#include <list> -#include <vector> - -#include "base/trace.hh" -#include "base/traceflags.hh" -#include "cpu/o3/bpred_unit.hh" - -using namespace std; - -template<class Impl> -BPredUnit<Impl>::BPredUnit(Params *params) - : BTB(params->BTBEntries, - params->BTBTagSize, - params->instShiftAmt) -{ - // Setup the selected predictor. - if (params->predType == "local") { - localBP = new LocalBP(params->localPredictorSize, - params->localCtrBits, - params->instShiftAmt); - predictor = Local; - } else if (params->predType == "tournament") { - tournamentBP = new TournamentBP(params->localPredictorSize, - params->localCtrBits, - params->localHistoryTableSize, - params->localHistoryBits, - params->globalPredictorSize, - params->globalHistoryBits, - params->globalCtrBits, - params->choicePredictorSize, - params->choiceCtrBits, - params->instShiftAmt); - predictor = Tournament; - } else { - fatal("Invalid BP selected!"); - } - - for (int i=0; i < Impl::MaxThreads; i++) - RAS[i].init(params->RASSize); -} - -template <class Impl> -void -BPredUnit<Impl>::regStats() -{ - lookups - .name(name() + ".BPredUnit.lookups") - .desc("Number of BP lookups") - ; - - condPredicted - .name(name() + ".BPredUnit.condPredicted") - .desc("Number of conditional branches predicted") - ; - - condIncorrect - .name(name() + ".BPredUnit.condIncorrect") - .desc("Number of conditional branches incorrect") - ; - - BTBLookups - .name(name() + ".BPredUnit.BTBLookups") - .desc("Number of BTB lookups") - ; - - BTBHits - .name(name() + ".BPredUnit.BTBHits") - .desc("Number of BTB hits") - ; - - BTBCorrect - .name(name() + ".BPredUnit.BTBCorrect") - .desc("Number of correct BTB predictions (this stat may not " - "work properly.") - ; - - usedRAS - .name(name() + ".BPredUnit.usedRAS") - .desc("Number of times the RAS was used to get a target.") - ; - - RASIncorrect - .name(name() + ".BPredUnit.RASInCorrect") - .desc("Number of incorrect RAS predictions.") - ; -} - -template <class Impl> -void -BPredUnit<Impl>::switchOut() -{ - // Clear any state upon switch out. - for (int i = 0; i < Impl::MaxThreads; ++i) { - squash(0, i); - } -} - -template <class Impl> -void -BPredUnit<Impl>::takeOverFrom() -{ - // Can reset all predictor state, but it's not necessarily better - // than leaving it be. -/* - for (int i = 0; i < Impl::MaxThreads; ++i) - RAS[i].reset(); - - BP.reset(); - BTB.reset(); -*/ -} - -template <class Impl> -bool -BPredUnit<Impl>::predict(DynInstPtr &inst, Addr &PC, unsigned tid) -{ - // See if branch predictor predicts taken. - // If so, get its target addr either from the BTB or the RAS. - // Save off record of branch stuff so the RAS can be fixed - // up once it's done. - - using TheISA::MachInst; - - bool pred_taken = false; - Addr target; - - ++lookups; - - void *bp_history = NULL; - - if (inst->isUncondCtrl()) { - DPRINTF(Fetch, "BranchPred: [tid:%i] Unconditional control.\n", tid); - pred_taken = true; - // Tell the BP there was an unconditional branch. - BPUncond(bp_history); - } else { - ++condPredicted; - - pred_taken = BPLookup(PC, bp_history); - - DPRINTF(Fetch, "BranchPred: [tid:%i]: Branch predictor predicted %i " - "for PC %#x\n", - tid, pred_taken, inst->readPC()); - } - - PredictorHistory predict_record(inst->seqNum, PC, pred_taken, - bp_history, tid); - - // Now lookup in the BTB or RAS. - if (pred_taken) { - if (inst->isReturn()) { - ++usedRAS; - - // If it's a function return call, then look up the address - // in the RAS. - target = RAS[tid].top(); - - // Record the top entry of the RAS, and its index. - predict_record.usedRAS = true; - predict_record.RASIndex = RAS[tid].topIdx(); - predict_record.RASTarget = target; - - assert(predict_record.RASIndex < 16); - - RAS[tid].pop(); - - DPRINTF(Fetch, "BranchPred: [tid:%i]: Instruction %#x is a return, " - "RAS predicted target: %#x, RAS index: %i.\n", - tid, inst->readPC(), target, predict_record.RASIndex); - } else { - ++BTBLookups; - - if (inst->isCall()) { - RAS[tid].push(PC + sizeof(MachInst)); - - // Record that it was a call so that the top RAS entry can - // be popped off if the speculation is incorrect. - predict_record.wasCall = true; - - DPRINTF(Fetch, "BranchPred: [tid:%i] Instruction %#x was a call" - ", adding %#x to the RAS.\n", - tid, inst->readPC(), PC + sizeof(MachInst)); - } - - if (BTB.valid(PC, tid)) { - ++BTBHits; - - // If it's not a return, use the BTB to get the target addr. - target = BTB.lookup(PC, tid); - - DPRINTF(Fetch, "BranchPred: [tid:%i]: Instruction %#x predicted" - " target is %#x.\n", - tid, inst->readPC(), target); - - } else { - DPRINTF(Fetch, "BranchPred: [tid:%i]: BTB doesn't have a " - "valid entry.\n",tid); - pred_taken = false; - } - - } - } - - if (pred_taken) { - // Set the PC and the instruction's predicted target. - PC = target; - inst->setPredTarg(target); - } else { - PC = PC + sizeof(MachInst); - inst->setPredTarg(PC); - } - - predHist[tid].push_front(predict_record); - - DPRINTF(Fetch, "[tid:%i] predHist.size(): %i\n", tid, predHist[tid].size()); - - return pred_taken; -} - -template <class Impl> -void -BPredUnit<Impl>::update(const InstSeqNum &done_sn, unsigned tid) -{ - DPRINTF(Fetch, "BranchPred: [tid:%i]: Commiting branches until sequence" - "number %lli.\n", tid, done_sn); - - while (!predHist[tid].empty() && - predHist[tid].back().seqNum <= done_sn) { - // Update the branch predictor with the correct results. - BPUpdate(predHist[tid].back().PC, - predHist[tid].back().predTaken, - predHist[tid].back().bpHistory); - - predHist[tid].pop_back(); - } -} - -template <class Impl> -void -BPredUnit<Impl>::squash(const InstSeqNum &squashed_sn, unsigned tid) -{ - History &pred_hist = predHist[tid]; - - while (!pred_hist.empty() && - pred_hist.front().seqNum > squashed_sn) { - if (pred_hist.front().usedRAS) { - DPRINTF(Fetch, "BranchPred: [tid:%i]: Restoring top of RAS to: %i," - " target: %#x.\n", - tid, - pred_hist.front().RASIndex, - pred_hist.front().RASTarget); - - RAS[tid].restore(pred_hist.front().RASIndex, - pred_hist.front().RASTarget); - - } else if (pred_hist.front().wasCall) { - DPRINTF(Fetch, "BranchPred: [tid:%i]: Removing speculative entry " - "added to the RAS.\n",tid); - - RAS[tid].pop(); - } - - // This call should delete the bpHistory. - BPSquash(pred_hist.front().bpHistory); - - pred_hist.pop_front(); - } - -} - -template <class Impl> -void -BPredUnit<Impl>::squash(const InstSeqNum &squashed_sn, - const Addr &corr_target, - const bool actually_taken, - unsigned tid) -{ - // Now that we know that a branch was mispredicted, we need to undo - // all the branches that have been seen up until this branch and - // fix up everything. - - History &pred_hist = predHist[tid]; - - ++condIncorrect; - - DPRINTF(Fetch, "BranchPred: [tid:%i]: Squashing from sequence number %i, " - "setting target to %#x.\n", - tid, squashed_sn, corr_target); - - squash(squashed_sn, tid); - - // If there's a squash due to a syscall, there may not be an entry - // corresponding to the squash. In that case, don't bother trying to - // fix up the entry. - if (!pred_hist.empty()) { - assert(pred_hist.front().seqNum == squashed_sn); - if (pred_hist.front().usedRAS) { - ++RASIncorrect; - } - - BPUpdate(pred_hist.front().PC, actually_taken, - pred_hist.front().bpHistory); - - BTB.update(pred_hist.front().PC, corr_target, tid); - pred_hist.pop_front(); - } -} - -template <class Impl> -void -BPredUnit<Impl>::BPUncond(void * &bp_history) -{ - // Only the tournament predictor cares about unconditional branches. - if (predictor == Tournament) { - tournamentBP->uncondBr(bp_history); - } -} - -template <class Impl> -void -BPredUnit<Impl>::BPSquash(void *bp_history) -{ - if (predictor == Local) { - localBP->squash(bp_history); - } else if (predictor == Tournament) { - tournamentBP->squash(bp_history); - } else { - panic("Predictor type is unexpected value!"); - } -} - -template <class Impl> -bool -BPredUnit<Impl>::BPLookup(Addr &inst_PC, void * &bp_history) -{ - if (predictor == Local) { - return localBP->lookup(inst_PC, bp_history); - } else if (predictor == Tournament) { - return tournamentBP->lookup(inst_PC, bp_history); - } else { - panic("Predictor type is unexpected value!"); - } -} - -template <class Impl> -void -BPredUnit<Impl>::BPUpdate(Addr &inst_PC, bool taken, void *bp_history) -{ - if (predictor == Local) { - localBP->update(inst_PC, taken, bp_history); - } else if (predictor == Tournament) { - tournamentBP->update(inst_PC, taken, bp_history); - } else { - panic("Predictor type is unexpected value!"); - } -} - -template <class Impl> -void -BPredUnit<Impl>::dump() -{ - typename History::iterator pred_hist_it; - - for (int i = 0; i < Impl::MaxThreads; ++i) { - if (!predHist[i].empty()) { - pred_hist_it = predHist[i].begin(); - - cprintf("predHist[%i].size(): %i\n", i, predHist[i].size()); - - while (pred_hist_it != predHist[i].end()) { - cprintf("[sn:%lli], PC:%#x, tid:%i, predTaken:%i, " - "bpHistory:%#x\n", - (*pred_hist_it).seqNum, (*pred_hist_it).PC, - (*pred_hist_it).tid, (*pred_hist_it).predTaken, - (*pred_hist_it).bpHistory); - pred_hist_it++; - } - - cprintf("\n"); - } - } -} |