c9d933efb0
This patch implements an L-TAGE predictor, based on André Seznec's code available from CBP-2 (http://hpca23.cse.tamu.edu/taco/camino/cbp2/cbp-src/realistic-seznec.h). Signed-off-by Jason Lowe-Power <jason@lowepower.com>
105 lines
4.7 KiB
Python
105 lines
4.7 KiB
Python
# Copyright (c) 2012 Mark D. Hill and David A. Wood
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# Copyright (c) 2015 The University of Wisconsin
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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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# Authors: Nilay Vaish and Dibakar Gope
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from m5.SimObject import SimObject
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from m5.params import *
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class BranchPredictor(SimObject):
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type = 'BranchPredictor'
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cxx_class = 'BPredUnit'
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cxx_header = "cpu/pred/bpred_unit.hh"
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abstract = True
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numThreads = Param.Unsigned(1, "Number of threads")
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BTBEntries = Param.Unsigned(4096, "Number of BTB entries")
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BTBTagSize = Param.Unsigned(16, "Size of the BTB tags, in bits")
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RASSize = Param.Unsigned(16, "RAS size")
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instShiftAmt = Param.Unsigned(2, "Number of bits to shift instructions by")
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useIndirect = Param.Bool(True, "Use indirect branch predictor")
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indirectHashGHR = Param.Bool(True, "Hash branch predictor GHR")
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indirectHashTargets = Param.Bool(True, "Hash path history targets")
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indirectSets = Param.Unsigned(256, "Cache sets for indirect predictor")
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indirectWays = Param.Unsigned(2, "Ways for indirect predictor")
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indirectTagSize = Param.Unsigned(16, "Indirect target cache tag bits")
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indirectPathLength = Param.Unsigned(3,
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"Previous indirect targets to use for path history")
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class LocalBP(BranchPredictor):
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type = 'LocalBP'
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cxx_class = 'LocalBP'
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cxx_header = "cpu/pred/2bit_local.hh"
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localPredictorSize = Param.Unsigned(2048, "Size of local predictor")
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localCtrBits = Param.Unsigned(2, "Bits per counter")
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class TournamentBP(BranchPredictor):
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type = 'TournamentBP'
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cxx_class = 'TournamentBP'
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cxx_header = "cpu/pred/tournament.hh"
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localPredictorSize = Param.Unsigned(2048, "Size of local predictor")
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localCtrBits = Param.Unsigned(2, "Bits per counter")
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localHistoryTableSize = Param.Unsigned(2048, "size of local history table")
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globalPredictorSize = Param.Unsigned(8192, "Size of global predictor")
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globalCtrBits = Param.Unsigned(2, "Bits per counter")
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choicePredictorSize = Param.Unsigned(8192, "Size of choice predictor")
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choiceCtrBits = Param.Unsigned(2, "Bits of choice counters")
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class BiModeBP(BranchPredictor):
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type = 'BiModeBP'
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cxx_class = 'BiModeBP'
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cxx_header = "cpu/pred/bi_mode.hh"
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globalPredictorSize = Param.Unsigned(8192, "Size of global predictor")
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globalCtrBits = Param.Unsigned(2, "Bits per counter")
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choicePredictorSize = Param.Unsigned(8192, "Size of choice predictor")
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choiceCtrBits = Param.Unsigned(2, "Bits of choice counters")
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class LTAGE(BranchPredictor):
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type = 'LTAGE'
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cxx_class = 'LTAGE'
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cxx_header = "cpu/pred/ltage.hh"
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logSizeBiMP = Param.Unsigned(14, "Log size of Bimodal predictor in bits")
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logSizeTagTables = Param.Unsigned(11, "Log size of tag table in LTAGE")
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logSizeLoopPred = Param.Unsigned(8, "Log size of the loop predictor")
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nHistoryTables = Param.Unsigned(12, "Number of history tables")
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tagTableCounterBits = Param.Unsigned(3, "Number of tag table counter bits")
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histBufferSize = Param.Unsigned(2097152,
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"A large number to track all branch histories(2MEntries default)")
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minHist = Param.Unsigned(4, "Minimum history size of LTAGE")
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maxHist = Param.Unsigned(640, "Maximum history size of LTAGE")
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minTagWidth = Param.Unsigned(7, "Minimum tag size in tag tables")
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