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-rw-r--r--src/cpu/o3/tournament_pred.cc297
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diff --git a/src/cpu/o3/tournament_pred.cc b/src/cpu/o3/tournament_pred.cc
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index ffb941c77..000000000
--- a/src/cpu/o3/tournament_pred.cc
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-/*
- * Copyright (c) 2004-2006 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
- */
-
-#include "base/intmath.hh"
-#include "cpu/o3/tournament_pred.hh"
-
-TournamentBP::TournamentBP(unsigned _localPredictorSize,
- unsigned _localCtrBits,
- unsigned _localHistoryTableSize,
- unsigned _localHistoryBits,
- unsigned _globalPredictorSize,
- unsigned _globalCtrBits,
- unsigned _globalHistoryBits,
- unsigned _choicePredictorSize,
- unsigned _choiceCtrBits,
- unsigned _instShiftAmt)
- : localPredictorSize(_localPredictorSize),
- localCtrBits(_localCtrBits),
- localHistoryTableSize(_localHistoryTableSize),
- localHistoryBits(_localHistoryBits),
- globalPredictorSize(_globalPredictorSize),
- globalCtrBits(_globalCtrBits),
- globalHistoryBits(_globalHistoryBits),
- choicePredictorSize(_globalPredictorSize),
- choiceCtrBits(_choiceCtrBits),
- instShiftAmt(_instShiftAmt)
-{
- if (!isPowerOf2(localPredictorSize)) {
- fatal("Invalid local predictor size!\n");
- }
-
- //Setup the array of counters for the local predictor
- localCtrs.resize(localPredictorSize);
-
- for (int i = 0; i < localPredictorSize; ++i)
- localCtrs[i].setBits(localCtrBits);
-
- localPredictorMask = floorPow2(localPredictorSize) - 1;
-
- if (!isPowerOf2(localHistoryTableSize)) {
- fatal("Invalid local history table size!\n");
- }
-
- //Setup the history table for the local table
- localHistoryTable.resize(localHistoryTableSize);
-
- for (int i = 0; i < localHistoryTableSize; ++i)
- localHistoryTable[i] = 0;
-
- // Setup the local history mask
- localHistoryMask = (1 << localHistoryBits) - 1;
-
- if (!isPowerOf2(globalPredictorSize)) {
- fatal("Invalid global predictor size!\n");
- }
-
- //Setup the array of counters for the global predictor
- globalCtrs.resize(globalPredictorSize);
-
- for (int i = 0; i < globalPredictorSize; ++i)
- globalCtrs[i].setBits(globalCtrBits);
-
- //Clear the global history
- globalHistory = 0;
- // Setup the global history mask
- globalHistoryMask = (1 << globalHistoryBits) - 1;
-
- if (!isPowerOf2(choicePredictorSize)) {
- fatal("Invalid choice predictor size!\n");
- }
-
- //Setup the array of counters for the choice predictor
- choiceCtrs.resize(choicePredictorSize);
-
- for (int i = 0; i < choicePredictorSize; ++i)
- choiceCtrs[i].setBits(choiceCtrBits);
-
- // @todo: Allow for different thresholds between the predictors.
- threshold = (1 << (localCtrBits - 1)) - 1;
- threshold = threshold / 2;
-}
-
-inline
-unsigned
-TournamentBP::calcLocHistIdx(Addr &branch_addr)
-{
- // Get low order bits after removing instruction offset.
- return (branch_addr >> instShiftAmt) & (localHistoryTableSize - 1);
-}
-
-inline
-void
-TournamentBP::updateGlobalHistTaken()
-{
- globalHistory = (globalHistory << 1) | 1;
- globalHistory = globalHistory & globalHistoryMask;
-}
-
-inline
-void
-TournamentBP::updateGlobalHistNotTaken()
-{
- globalHistory = (globalHistory << 1);
- globalHistory = globalHistory & globalHistoryMask;
-}
-
-inline
-void
-TournamentBP::updateLocalHistTaken(unsigned local_history_idx)
-{
- localHistoryTable[local_history_idx] =
- (localHistoryTable[local_history_idx] << 1) | 1;
-}
-
-inline
-void
-TournamentBP::updateLocalHistNotTaken(unsigned local_history_idx)
-{
- localHistoryTable[local_history_idx] =
- (localHistoryTable[local_history_idx] << 1);
-}
-
-bool
-TournamentBP::lookup(Addr &branch_addr, void * &bp_history)
-{
- bool local_prediction;
- unsigned local_history_idx;
- unsigned local_predictor_idx;
-
- bool global_prediction;
- bool choice_prediction;
-
- //Lookup in the local predictor to get its branch prediction
- local_history_idx = calcLocHistIdx(branch_addr);
- local_predictor_idx = localHistoryTable[local_history_idx]
- & localPredictorMask;
- local_prediction = localCtrs[local_predictor_idx].read() > threshold;
-
- //Lookup in the global predictor to get its branch prediction
- global_prediction = globalCtrs[globalHistory].read() > threshold;
-
- //Lookup in the choice predictor to see which one to use
- choice_prediction = choiceCtrs[globalHistory].read() > threshold;
-
- // Create BPHistory and pass it back to be recorded.
- BPHistory *history = new BPHistory;
- history->globalHistory = globalHistory;
- history->localPredTaken = local_prediction;
- history->globalPredTaken = global_prediction;
- history->globalUsed = choice_prediction;
- bp_history = (void *)history;
-
- assert(globalHistory < globalPredictorSize &&
- local_history_idx < localHistoryTableSize &&
- local_predictor_idx < localPredictorSize);
-
- // Commented code is for doing speculative update of counters and
- // all histories.
- if (choice_prediction) {
- if (global_prediction) {
-// updateHistoriesTaken(local_history_idx);
-// globalCtrs[globalHistory].increment();
-// localCtrs[local_history_idx].increment();
- updateGlobalHistTaken();
- return true;
- } else {
-// updateHistoriesNotTaken(local_history_idx);
-// globalCtrs[globalHistory].decrement();
-// localCtrs[local_history_idx].decrement();
- updateGlobalHistNotTaken();
- return false;
- }
- } else {
- if (local_prediction) {
-// updateHistoriesTaken(local_history_idx);
-// globalCtrs[globalHistory].increment();
-// localCtrs[local_history_idx].increment();
- updateGlobalHistTaken();
- return true;
- } else {
-// updateHistoriesNotTaken(local_history_idx);
-// globalCtrs[globalHistory].decrement();
-// localCtrs[local_history_idx].decrement();
- updateGlobalHistNotTaken();
- return false;
- }
- }
-}
-
-void
-TournamentBP::uncondBr(void * &bp_history)
-{
- // Create BPHistory and pass it back to be recorded.
- BPHistory *history = new BPHistory;
- history->globalHistory = globalHistory;
- history->localPredTaken = true;
- history->globalPredTaken = true;
- bp_history = static_cast<void *>(history);
-
- updateGlobalHistTaken();
-}
-
-void
-TournamentBP::update(Addr &branch_addr, bool taken, void *bp_history)
-{
- unsigned local_history_idx;
- unsigned local_predictor_idx;
- unsigned local_predictor_hist;
-
- // Get the local predictor's current prediction
- local_history_idx = calcLocHistIdx(branch_addr);
- local_predictor_hist = localHistoryTable[local_history_idx];
- local_predictor_idx = local_predictor_hist & localPredictorMask;
-
- // Update the choice predictor to tell it which one was correct if
- // there was a prediction.
- if (bp_history) {
- BPHistory *history = static_cast<BPHistory *>(bp_history);
- if (history->localPredTaken != history->globalPredTaken) {
- // If the local prediction matches the actual outcome,
- // decerement the counter. Otherwise increment the
- // counter.
- if (history->localPredTaken == taken) {
- choiceCtrs[globalHistory].decrement();
- } else if (history->globalPredTaken == taken){
- choiceCtrs[globalHistory].increment();
- }
- }
-
- // We're done with this history, now delete it.
- delete history;
- }
-
- assert(globalHistory < globalPredictorSize &&
- local_history_idx < localHistoryTableSize &&
- local_predictor_idx < localPredictorSize);
-
- // Update the counters and local history with the proper
- // resolution of the branch. Global history is updated
- // speculatively and restored upon squash() calls, so it does not
- // need to be updated.
- if (taken) {
- localCtrs[local_predictor_idx].increment();
- globalCtrs[globalHistory].increment();
-
- updateLocalHistTaken(local_history_idx);
- } else {
- localCtrs[local_predictor_idx].decrement();
- globalCtrs[globalHistory].decrement();
-
- updateLocalHistNotTaken(local_history_idx);
- }
-}
-
-void
-TournamentBP::squash(void *bp_history)
-{
- BPHistory *history = static_cast<BPHistory *>(bp_history);
-
- // Restore global history to state prior to this branch.
- globalHistory = history->globalHistory;
-
- // Delete this BPHistory now that we're done with it.
- delete history;
-}
-
-#ifdef DEBUG
-int
-TournamentBP::BPHistory::newCount = 0;
-#endif
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