248bd2bb62
cpu/o3/2bit_local_pred.cc:
Branch predictor cleanup/fixup. Rename this to LocalBP.
cpu/o3/2bit_local_pred.hh:
Rename to LocalBP, update to support changes to BPredUnit, include comments.
cpu/o3/alpha_cpu_builder.cc:
Support extra parameters to the branch predictor. Now it takes in a parameter to tell it which branch predictor it is using, the local or the tournament predictor.
cpu/o3/alpha_params.hh:
Add in extra parameter for the branch predictor type.
cpu/o3/bpred_unit.cc:
Branch predictor fixup/cleanup. Rename it to BPredUnit.
cpu/o3/bpred_unit.hh:
Branch predictor fixup/cleanup. Now supports both the local and tournament predictors, and stores the branch predictor update state.
cpu/o3/bpred_unit_impl.hh:
Branch predictor overhaul. Now supports both the local and tournament predictors.
cpu/o3/cpu_policy.hh:
cpu/ozone/ozone_impl.hh:
cpu/ozone/simple_impl.hh:
Reflect the class name change.
cpu/o3/decode_impl.hh:
Be sure to set the predicted target as well so we don't squash twice.
cpu/o3/tournament_pred.cc:
cpu/o3/tournament_pred.hh:
Fixes to the tournament predictor.
cpu/ozone/simple_params.hh:
Include parameter for the branch predictor type.
python/m5/objects/AlphaFullCPU.py:
python/m5/objects/OzoneCPU.py:
Include the parameter for the branch predictor type.
--HG--
extra : convert_revision : 34afebb3b40b47accb12558e439ee4cb03df5e64
109 lines
4 KiB
C++
109 lines
4 KiB
C++
/*
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* Copyright (c) 2004-2006 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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#ifndef __CPU_O3_2BIT_LOCAL_PRED_HH__
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#define __CPU_O3_2BIT_LOCAL_PRED_HH__
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// For Addr type.
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#include "arch/isa_traits.hh"
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#include "cpu/o3/sat_counter.hh"
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#include <vector>
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/**
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* Implements a local predictor that uses the PC to index into a table of
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* counters. Note that any time a pointer to the bp_history is given, it
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* should be NULL using this predictor because it does not have any branch
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* predictor state that needs to be recorded or updated; the update can be
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* determined solely by the branch being taken or not taken.
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*/
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class LocalBP
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{
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public:
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/**
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* Default branch predictor constructor.
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* @param localPredictorSize Size of the local predictor.
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* @param localCtrBits Number of bits per counter.
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* @param instShiftAmt Offset amount for instructions to ignore alignment.
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*/
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LocalBP(unsigned localPredictorSize, unsigned localCtrBits,
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unsigned instShiftAmt);
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/**
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* Looks up the given address in the branch predictor and returns
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* a true/false value as to whether it is taken.
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* @param branch_addr The address of the branch to look up.
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* @param bp_history Pointer to any bp history state.
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* @return Whether or not the branch is taken.
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*/
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bool lookup(Addr &branch_addr, void * &bp_history);
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/**
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* Updates the branch predictor with the actual result of a branch.
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* @param branch_addr The address of the branch to update.
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* @param taken Whether or not the branch was taken.
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*/
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void update(Addr &branch_addr, bool taken, void *bp_history);
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void squash(void *bp_history)
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{ assert(bp_history == NULL); }
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void reset();
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private:
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/**
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* Returns the taken/not taken prediction given the value of the
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* counter.
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* @param count The value of the counter.
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* @return The prediction based on the counter value.
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*/
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inline bool getPrediction(uint8_t &count);
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/** Calculates the local index based on the PC. */
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inline unsigned getLocalIndex(Addr &PC);
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/** Array of counters that make up the local predictor. */
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std::vector<SatCounter> localCtrs;
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/** Size of the local predictor. */
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unsigned localPredictorSize;
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/** Number of sets. */
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unsigned localPredictorSets;
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/** Number of bits of the local predictor's counters. */
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unsigned localCtrBits;
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/** Number of bits to shift the PC when calculating index. */
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unsigned instShiftAmt;
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/** Mask to get index bits. */
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unsigned indexMask;
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};
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#endif // __CPU_O3_2BIT_LOCAL_PRED_HH__
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