BranchPredictor.py revision 13454
19480Snilay@cs.wisc.edu# Copyright (c) 2012 Mark D. Hill and David A. Wood 210785Sgope@wisc.edu# Copyright (c) 2015 The University of Wisconsin 39480Snilay@cs.wisc.edu# All rights reserved. 49480Snilay@cs.wisc.edu# 59480Snilay@cs.wisc.edu# Redistribution and use in source and binary forms, with or without 69480Snilay@cs.wisc.edu# modification, are permitted provided that the following conditions are 79480Snilay@cs.wisc.edu# met: redistributions of source code must retain the above copyright 89480Snilay@cs.wisc.edu# notice, this list of conditions and the following disclaimer; 99480Snilay@cs.wisc.edu# redistributions in binary form must reproduce the above copyright 109480Snilay@cs.wisc.edu# notice, this list of conditions and the following disclaimer in the 119480Snilay@cs.wisc.edu# documentation and/or other materials provided with the distribution; 129480Snilay@cs.wisc.edu# neither the name of the copyright holders nor the names of its 139480Snilay@cs.wisc.edu# contributors may be used to endorse or promote products derived from 149480Snilay@cs.wisc.edu# this software without specific prior written permission. 159480Snilay@cs.wisc.edu# 169480Snilay@cs.wisc.edu# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 179480Snilay@cs.wisc.edu# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 189480Snilay@cs.wisc.edu# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 199480Snilay@cs.wisc.edu# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 209480Snilay@cs.wisc.edu# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 219480Snilay@cs.wisc.edu# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 229480Snilay@cs.wisc.edu# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 239480Snilay@cs.wisc.edu# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 249480Snilay@cs.wisc.edu# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 259480Snilay@cs.wisc.edu# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 269480Snilay@cs.wisc.edu# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 279480Snilay@cs.wisc.edu# 2810785Sgope@wisc.edu# Authors: Nilay Vaish and Dibakar Gope 299480Snilay@cs.wisc.edu 309480Snilay@cs.wisc.edufrom m5.SimObject import SimObject 319480Snilay@cs.wisc.edufrom m5.params import * 3213432Spau.cabre@metempsy.comfrom m5.proxy import * 339480Snilay@cs.wisc.edu 349480Snilay@cs.wisc.educlass BranchPredictor(SimObject): 359480Snilay@cs.wisc.edu type = 'BranchPredictor' 369480Snilay@cs.wisc.edu cxx_class = 'BPredUnit' 379480Snilay@cs.wisc.edu cxx_header = "cpu/pred/bpred_unit.hh" 3810785Sgope@wisc.edu abstract = True 399480Snilay@cs.wisc.edu 4013432Spau.cabre@metempsy.com numThreads = Param.Unsigned(Parent.numThreads, "Number of threads") 4110785Sgope@wisc.edu BTBEntries = Param.Unsigned(4096, "Number of BTB entries") 4210785Sgope@wisc.edu BTBTagSize = Param.Unsigned(16, "Size of the BTB tags, in bits") 4310785Sgope@wisc.edu RASSize = Param.Unsigned(16, "RAS size") 4410785Sgope@wisc.edu instShiftAmt = Param.Unsigned(2, "Number of bits to shift instructions by") 4510785Sgope@wisc.edu 4611433Smitch.hayenga@arm.com useIndirect = Param.Bool(True, "Use indirect branch predictor") 4711433Smitch.hayenga@arm.com indirectHashGHR = Param.Bool(True, "Hash branch predictor GHR") 4811433Smitch.hayenga@arm.com indirectHashTargets = Param.Bool(True, "Hash path history targets") 4911433Smitch.hayenga@arm.com indirectSets = Param.Unsigned(256, "Cache sets for indirect predictor") 5011433Smitch.hayenga@arm.com indirectWays = Param.Unsigned(2, "Ways for indirect predictor") 5111433Smitch.hayenga@arm.com indirectTagSize = Param.Unsigned(16, "Indirect target cache tag bits") 5211433Smitch.hayenga@arm.com indirectPathLength = Param.Unsigned(3, 5311433Smitch.hayenga@arm.com "Previous indirect targets to use for path history") 5411433Smitch.hayenga@arm.com 5511433Smitch.hayenga@arm.com 5610785Sgope@wisc.edu 5710785Sgope@wisc.educlass LocalBP(BranchPredictor): 5810785Sgope@wisc.edu type = 'LocalBP' 5910785Sgope@wisc.edu cxx_class = 'LocalBP' 6010785Sgope@wisc.edu cxx_header = "cpu/pred/2bit_local.hh" 6110785Sgope@wisc.edu 629480Snilay@cs.wisc.edu localPredictorSize = Param.Unsigned(2048, "Size of local predictor") 639480Snilay@cs.wisc.edu localCtrBits = Param.Unsigned(2, "Bits per counter") 6410785Sgope@wisc.edu 6510785Sgope@wisc.edu 6610785Sgope@wisc.educlass TournamentBP(BranchPredictor): 6710785Sgope@wisc.edu type = 'TournamentBP' 6810785Sgope@wisc.edu cxx_class = 'TournamentBP' 6910785Sgope@wisc.edu cxx_header = "cpu/pred/tournament.hh" 7010785Sgope@wisc.edu 7110785Sgope@wisc.edu localPredictorSize = Param.Unsigned(2048, "Size of local predictor") 7210785Sgope@wisc.edu localCtrBits = Param.Unsigned(2, "Bits per counter") 7310785Sgope@wisc.edu localHistoryTableSize = Param.Unsigned(2048, "size of local history table") 749480Snilay@cs.wisc.edu globalPredictorSize = Param.Unsigned(8192, "Size of global predictor") 759480Snilay@cs.wisc.edu globalCtrBits = Param.Unsigned(2, "Bits per counter") 769480Snilay@cs.wisc.edu choicePredictorSize = Param.Unsigned(8192, "Size of choice predictor") 779480Snilay@cs.wisc.edu choiceCtrBits = Param.Unsigned(2, "Bits of choice counters") 789480Snilay@cs.wisc.edu 799480Snilay@cs.wisc.edu 8010785Sgope@wisc.educlass BiModeBP(BranchPredictor): 8110785Sgope@wisc.edu type = 'BiModeBP' 8210785Sgope@wisc.edu cxx_class = 'BiModeBP' 8310785Sgope@wisc.edu cxx_header = "cpu/pred/bi_mode.hh" 8410785Sgope@wisc.edu 8510785Sgope@wisc.edu globalPredictorSize = Param.Unsigned(8192, "Size of global predictor") 8610785Sgope@wisc.edu globalCtrBits = Param.Unsigned(2, "Bits per counter") 8710785Sgope@wisc.edu choicePredictorSize = Param.Unsigned(8192, "Size of choice predictor") 8810785Sgope@wisc.edu choiceCtrBits = Param.Unsigned(2, "Bits of choice counters") 8910785Sgope@wisc.edu 9013454Spau.cabre@metempsy.com# TAGE branch predictor as described in https://www.jilp.org/vol8/v8paper1.pdf 9113454Spau.cabre@metempsy.com# The default sizes below are for the 8C-TAGE configuration (63.5 Kbits) 9213454Spau.cabre@metempsy.comclass TAGE(BranchPredictor): 9313454Spau.cabre@metempsy.com type = 'TAGE' 9413454Spau.cabre@metempsy.com cxx_class = 'TAGE' 9513454Spau.cabre@metempsy.com cxx_header = "cpu/pred/tage.hh" 9613454Spau.cabre@metempsy.com 9713454Spau.cabre@metempsy.com nHistoryTables = Param.Unsigned(7, "Number of history tables") 9813454Spau.cabre@metempsy.com minHist = Param.Unsigned(5, "Minimum history size of LTAGE") 9913454Spau.cabre@metempsy.com maxHist = Param.Unsigned(130, "Maximum history size of LTAGE") 10013454Spau.cabre@metempsy.com 10113454Spau.cabre@metempsy.com tagTableTagWidths = VectorParam.Unsigned( 10213454Spau.cabre@metempsy.com [0, 9, 9, 10, 10, 11, 11, 12], "Tag size in TAGE tag tables") 10313454Spau.cabre@metempsy.com logTagTableSizes = VectorParam.Int( 10413454Spau.cabre@metempsy.com [13, 9, 9, 9, 9, 9, 9, 9], "Log2 of TAGE table sizes") 10513454Spau.cabre@metempsy.com logRatioBiModalHystEntries = Param.Unsigned(2, 10613454Spau.cabre@metempsy.com "Log num of prediction entries for a shared hysteresis bit " \ 10713454Spau.cabre@metempsy.com "for the Bimodal") 10813454Spau.cabre@metempsy.com 10913454Spau.cabre@metempsy.com tagTableCounterBits = Param.Unsigned(3, "Number of tag table counter bits") 11013454Spau.cabre@metempsy.com tagTableUBits = Param.Unsigned(2, "Number of tag table u bits") 11113454Spau.cabre@metempsy.com 11213454Spau.cabre@metempsy.com histBufferSize = Param.Unsigned(2097152, 11313454Spau.cabre@metempsy.com "A large number to track all branch histories(2MEntries default)") 11413454Spau.cabre@metempsy.com 11513454Spau.cabre@metempsy.com pathHistBits = Param.Unsigned(16, "Path history size") 11613454Spau.cabre@metempsy.com logUResetPeriod = Param.Unsigned(18, 11713454Spau.cabre@metempsy.com "Log period in number of branches to reset TAGE useful counters") 11813454Spau.cabre@metempsy.com useAltOnNaBits = Param.Unsigned(4, "Size of the USE_ALT_ON_NA counter") 11913454Spau.cabre@metempsy.com 12013454Spau.cabre@metempsy.com 12113454Spau.cabre@metempsy.com# LTAGE branch predictor as described in 12213454Spau.cabre@metempsy.com# https://www.irisa.fr/caps/people/seznec/L-TAGE.pdf 12313454Spau.cabre@metempsy.com# It is basically a TAGE predictor plus a loop predictor 12413454Spau.cabre@metempsy.com# The differnt TAGE sizes are updated according to the paper values (256 Kbits) 12513454Spau.cabre@metempsy.comclass LTAGE(TAGE): 12611784Sarthur.perais@inria.fr type = 'LTAGE' 12711784Sarthur.perais@inria.fr cxx_class = 'LTAGE' 12811784Sarthur.perais@inria.fr cxx_header = "cpu/pred/ltage.hh" 12911784Sarthur.perais@inria.fr 13013454Spau.cabre@metempsy.com nHistoryTables = 12 13113454Spau.cabre@metempsy.com minHist = 4 13213454Spau.cabre@metempsy.com maxHist = 640 13313454Spau.cabre@metempsy.com tagTableTagWidths = [0, 7, 7, 8, 8, 9, 10, 11, 12, 12, 13, 14, 15] 13413454Spau.cabre@metempsy.com logTagTableSizes = [14, 10, 10, 11, 11, 11, 11, 10, 10, 10, 10, 9, 9] 13513454Spau.cabre@metempsy.com logUResetPeriod = 19 13613454Spau.cabre@metempsy.com 13711784Sarthur.perais@inria.fr logSizeLoopPred = Param.Unsigned(8, "Log size of the loop predictor") 13813444Spau.cabre@metempsy.com withLoopBits = Param.Unsigned(7, "Size of the WITHLOOP counter") 13913442Spau.cabre@metempsy.com loopTableAgeBits = Param.Unsigned(8, "Number of age bits per loop entry") 14013442Spau.cabre@metempsy.com loopTableConfidenceBits = Param.Unsigned(2, 14113442Spau.cabre@metempsy.com "Number of confidence bits per loop entry") 14213442Spau.cabre@metempsy.com loopTableTagBits = Param.Unsigned(14, "Number of tag bits per loop entry") 14313442Spau.cabre@metempsy.com loopTableIterBits = Param.Unsigned(14, "Nuber of iteration bits per loop") 14413444Spau.cabre@metempsy.com logLoopTableAssoc = Param.Unsigned(2, "Log loop predictor associativity") 14513442Spau.cabre@metempsy.com 146