a8b03e4d01
arch/alpha/isa/decoder.isa:
Make IPR accessing instructions serializing so they are not issued incorrectly in the O3 model.
arch/alpha/isa/pal.isa:
Allow IPR instructions to have flags.
base/traceflags.py:
Include new trace flags from the two new CPU models.
cpu/SConscript:
Create the templates for the split mem accessor methods. Also include the new files from the new models (the Ozone model will be checked in next).
cpu/base_dyn_inst.cc:
cpu/base_dyn_inst.hh:
Update to the BaseDynInst for the new models.
--HG--
extra : convert_revision : cc82db9c72ec3e29cea4c3fdff74a3843e287a35
255 lines
8.9 KiB
C++
255 lines
8.9 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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#include "cpu/o3/tournament_pred.hh"
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TournamentBP::TournamentBP(unsigned _localPredictorSize,
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unsigned _localCtrBits,
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unsigned _localHistoryTableSize,
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unsigned _localHistoryBits,
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unsigned _globalPredictorSize,
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unsigned _globalCtrBits,
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unsigned _globalHistoryBits,
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unsigned _choicePredictorSize,
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unsigned _choiceCtrBits,
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unsigned _instShiftAmt)
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: localPredictorSize(_localPredictorSize),
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localCtrBits(_localCtrBits),
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localHistoryTableSize(_localHistoryTableSize),
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localHistoryBits(_localHistoryBits),
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globalPredictorSize(_globalPredictorSize),
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globalCtrBits(_globalCtrBits),
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globalHistoryBits(_globalHistoryBits),
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choicePredictorSize(_globalPredictorSize),
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choiceCtrBits(_choiceCtrBits),
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instShiftAmt(_instShiftAmt)
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{
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//Should do checks here to make sure sizes are correct (powers of 2)
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//Setup the array of counters for the local predictor
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localCtrs.resize(localPredictorSize);
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for (int i = 0; i < localPredictorSize; ++i)
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localCtrs[i].setBits(localCtrBits);
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//Setup the history table for the local table
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localHistoryTable.resize(localHistoryTableSize);
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for (int i = 0; i < localHistoryTableSize; ++i)
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localHistoryTable[i] = 0;
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// Setup the local history mask
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localHistoryMask = (1 << localHistoryBits) - 1;
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//Setup the array of counters for the global predictor
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globalCtrs.resize(globalPredictorSize);
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for (int i = 0; i < globalPredictorSize; ++i)
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globalCtrs[i].setBits(globalCtrBits);
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//Clear the global history
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globalHistory = 0;
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// Setup the global history mask
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globalHistoryMask = (1 << globalHistoryBits) - 1;
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//Setup the array of counters for the choice predictor
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choiceCtrs.resize(choicePredictorSize);
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for (int i = 0; i < choicePredictorSize; ++i)
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choiceCtrs[i].setBits(choiceCtrBits);
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threshold = (1 << (localCtrBits - 1)) - 1;
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threshold = threshold / 2;
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}
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inline
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unsigned
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TournamentBP::calcLocHistIdx(Addr &branch_addr)
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{
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return (branch_addr >> instShiftAmt) & (localHistoryTableSize - 1);
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}
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inline
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void
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TournamentBP::updateHistoriesTaken(unsigned local_history_idx)
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{
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globalHistory = (globalHistory << 1) | 1;
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globalHistory = globalHistory & globalHistoryMask;
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localHistoryTable[local_history_idx] =
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(localHistoryTable[local_history_idx] << 1) | 1;
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}
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inline
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void
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TournamentBP::updateHistoriesNotTaken(unsigned local_history_idx)
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{
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globalHistory = (globalHistory << 1);
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globalHistory = globalHistory & globalHistoryMask;
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localHistoryTable[local_history_idx] =
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(localHistoryTable[local_history_idx] << 1);
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}
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bool
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TournamentBP::lookup(Addr &branch_addr)
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{
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uint8_t local_prediction;
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unsigned local_history_idx;
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unsigned local_predictor_idx;
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uint8_t global_prediction;
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uint8_t choice_prediction;
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//Lookup in the local predictor to get its branch prediction
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local_history_idx = calcLocHistIdx(branch_addr);
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local_predictor_idx = localHistoryTable[local_history_idx]
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& localHistoryMask;
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local_prediction = localCtrs[local_predictor_idx].read();
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//Lookup in the global predictor to get its branch prediction
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global_prediction = globalCtrs[globalHistory].read();
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//Lookup in the choice predictor to see which one to use
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choice_prediction = choiceCtrs[globalHistory].read();
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//@todo Put a threshold value in for the three predictors that can
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// be set through the constructor (so this isn't hard coded).
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//Also should put some of this code into functions.
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if (choice_prediction > threshold) {
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if (global_prediction > threshold) {
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updateHistoriesTaken(local_history_idx);
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assert(globalHistory < globalPredictorSize &&
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local_history_idx < localPredictorSize);
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globalCtrs[globalHistory].increment();
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localCtrs[local_history_idx].increment();
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return true;
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} else {
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updateHistoriesNotTaken(local_history_idx);
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assert(globalHistory < globalPredictorSize &&
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local_history_idx < localPredictorSize);
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globalCtrs[globalHistory].decrement();
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localCtrs[local_history_idx].decrement();
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return false;
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}
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} else {
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if (local_prediction > threshold) {
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updateHistoriesTaken(local_history_idx);
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assert(globalHistory < globalPredictorSize &&
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local_history_idx < localPredictorSize);
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globalCtrs[globalHistory].increment();
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localCtrs[local_history_idx].increment();
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return true;
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} else {
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updateHistoriesNotTaken(local_history_idx);
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assert(globalHistory < globalPredictorSize &&
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local_history_idx < localPredictorSize);
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globalCtrs[globalHistory].decrement();
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localCtrs[local_history_idx].decrement();
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return false;
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}
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}
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}
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// Update the branch predictor if it predicted a branch wrong.
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void
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TournamentBP::update(Addr &branch_addr, unsigned correct_gh, bool taken)
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{
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uint8_t local_prediction;
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unsigned local_history_idx;
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unsigned local_predictor_idx;
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bool local_pred_taken;
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uint8_t global_prediction;
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bool global_pred_taken;
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// Load the correct global history into the register.
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globalHistory = correct_gh;
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// Get the local predictor's current prediction, remove the incorrect
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// update, and update the local predictor
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local_history_idx = calcLocHistIdx(branch_addr);
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local_predictor_idx = localHistoryTable[local_history_idx];
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local_predictor_idx = (local_predictor_idx >> 1) & localHistoryMask;
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local_prediction = localCtrs[local_predictor_idx].read();
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local_pred_taken = local_prediction > threshold;
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//Get the global predictor's current prediction, and update the
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//global predictor
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global_prediction = globalCtrs[globalHistory].read();
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global_pred_taken = global_prediction > threshold;
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//Update the choice predictor to tell it which one was correct
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if (local_pred_taken != global_pred_taken) {
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//If the local prediction matches the actual outcome, decerement
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//the counter. Otherwise increment the counter.
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if (local_pred_taken == taken) {
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choiceCtrs[globalHistory].decrement();
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} else {
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choiceCtrs[globalHistory].increment();
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}
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}
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if (taken) {
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assert(globalHistory < globalPredictorSize &&
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local_predictor_idx < localPredictorSize);
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localCtrs[local_predictor_idx].increment();
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globalCtrs[globalHistory].increment();
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globalHistory = (globalHistory << 1) | 1;
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globalHistory = globalHistory & globalHistoryMask;
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localHistoryTable[local_history_idx] |= 1;
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} else {
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assert(globalHistory < globalPredictorSize &&
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local_predictor_idx < localPredictorSize);
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localCtrs[local_predictor_idx].decrement();
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globalCtrs[globalHistory].decrement();
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globalHistory = (globalHistory << 1);
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globalHistory = globalHistory & globalHistoryMask;
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localHistoryTable[local_history_idx] &= ~1;
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}
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}
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