2bit_local.hh revision 13626
110244Satgutier@umich.edu/* 210244Satgutier@umich.edu * Copyright (c) 2011, 2014 ARM Limited 310244Satgutier@umich.edu * All rights reserved 410244Satgutier@umich.edu * 510244Satgutier@umich.edu * The license below extends only to copyright in the software and shall 610244Satgutier@umich.edu * not be construed as granting a license to any other intellectual 710244Satgutier@umich.edu * property including but not limited to intellectual property relating 810244Satgutier@umich.edu * to a hardware implementation of the functionality of the software 910244Satgutier@umich.edu * licensed hereunder. You may use the software subject to the license 1010244Satgutier@umich.edu * terms below provided that you ensure that this notice is replicated 1110244Satgutier@umich.edu * unmodified and in its entirety in all distributions of the software, 1210244Satgutier@umich.edu * modified or unmodified, in source code or in binary form. 1310244Satgutier@umich.edu * 1410244Satgutier@umich.edu * Copyright (c) 2004-2006 The Regents of The University of Michigan 1510244Satgutier@umich.edu * All rights reserved. 1610244Satgutier@umich.edu * 1710244Satgutier@umich.edu * Redistribution and use in source and binary forms, with or without 1810244Satgutier@umich.edu * modification, are permitted provided that the following conditions are 1910244Satgutier@umich.edu * met: redistributions of source code must retain the above copyright 2010244Satgutier@umich.edu * notice, this list of conditions and the following disclaimer; 2110244Satgutier@umich.edu * redistributions in binary form must reproduce the above copyright 2210244Satgutier@umich.edu * notice, this list of conditions and the following disclaimer in the 2310244Satgutier@umich.edu * documentation and/or other materials provided with the distribution; 2410244Satgutier@umich.edu * neither the name of the copyright holders nor the names of its 2510244Satgutier@umich.edu * contributors may be used to endorse or promote products derived from 2610244Satgutier@umich.edu * this software without specific prior written permission. 2710244Satgutier@umich.edu * 2810244Satgutier@umich.edu * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 2910244Satgutier@umich.edu * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 3010244Satgutier@umich.edu * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 3110244Satgutier@umich.edu * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 3210244Satgutier@umich.edu * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 3310244Satgutier@umich.edu * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 3410244Satgutier@umich.edu * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 3510244Satgutier@umich.edu * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 3610244Satgutier@umich.edu * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 3710244Satgutier@umich.edu * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 3810244Satgutier@umich.edu * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 3910244Satgutier@umich.edu * 4010785Sgope@wisc.edu * Authors: Kevin Lim 4110244Satgutier@umich.edu * Timothy M. Jones 4210244Satgutier@umich.edu */ 4310244Satgutier@umich.edu 4410244Satgutier@umich.edu#ifndef __CPU_PRED_2BIT_LOCAL_PRED_HH__ 4510244Satgutier@umich.edu#define __CPU_PRED_2BIT_LOCAL_PRED_HH__ 4610244Satgutier@umich.edu 4710244Satgutier@umich.edu#include <vector> 4810244Satgutier@umich.edu 4910244Satgutier@umich.edu#include "base/types.hh" 5010244Satgutier@umich.edu#include "cpu/pred/bpred_unit.hh" 5110244Satgutier@umich.edu#include "cpu/pred/sat_counter.hh" 5210244Satgutier@umich.edu#include "params/LocalBP.hh" 5310244Satgutier@umich.edu 5410244Satgutier@umich.edu/** 5510244Satgutier@umich.edu * Implements a local predictor that uses the PC to index into a table of 5610244Satgutier@umich.edu * counters. Note that any time a pointer to the bp_history is given, it 5710244Satgutier@umich.edu * should be NULL using this predictor because it does not have any branch 5810244Satgutier@umich.edu * predictor state that needs to be recorded or updated; the update can be 5910785Sgope@wisc.edu * determined solely by the branch being taken or not taken. 6011434Smitch.hayenga@arm.com */ 6111434Smitch.hayenga@arm.comclass LocalBP : public BPredUnit 6211434Smitch.hayenga@arm.com{ 6311434Smitch.hayenga@arm.com public: 6411434Smitch.hayenga@arm.com /** 6513626Sjairo.balart@metempsy.com * Default branch predictor constructor. 6611434Smitch.hayenga@arm.com */ 6710244Satgutier@umich.edu LocalBP(const LocalBPParams *params); 6810244Satgutier@umich.edu 6911434Smitch.hayenga@arm.com virtual void uncondBranch(ThreadID tid, Addr pc, void * &bp_history); 7010244Satgutier@umich.edu 7110244Satgutier@umich.edu /** 7210244Satgutier@umich.edu * Looks up the given address in the branch predictor and returns 7310244Satgutier@umich.edu * a true/false value as to whether it is taken. 7410244Satgutier@umich.edu * @param branch_addr The address of the branch to look up. 7510244Satgutier@umich.edu * @param bp_history Pointer to any bp history state. 7610244Satgutier@umich.edu * @return Whether or not the branch is taken. 7710244Satgutier@umich.edu */ 7810244Satgutier@umich.edu bool lookup(ThreadID tid, Addr branch_addr, void * &bp_history); 7910244Satgutier@umich.edu 8010244Satgutier@umich.edu /** 8110244Satgutier@umich.edu * Updates the branch predictor to Not Taken if a BTB entry is 8210244Satgutier@umich.edu * invalid or not found. 8310244Satgutier@umich.edu * @param branch_addr The address of the branch to look up. 8410244Satgutier@umich.edu * @param bp_history Pointer to any bp history state. 8510244Satgutier@umich.edu * @return Whether or not the branch is taken. 8610244Satgutier@umich.edu */ 8710244Satgutier@umich.edu void btbUpdate(ThreadID tid, Addr branch_addr, void * &bp_history); 8810244Satgutier@umich.edu 8910244Satgutier@umich.edu /** 9010244Satgutier@umich.edu * Updates the branch predictor with the actual result of a branch. 9110244Satgutier@umich.edu * @param branch_addr The address of the branch to update. 9210244Satgutier@umich.edu * @param taken Whether or not the branch was taken. 9310244Satgutier@umich.edu */ 9410244Satgutier@umich.edu void update(ThreadID tid, Addr branch_addr, bool taken, void *bp_history, 9510244Satgutier@umich.edu bool squashed, const StaticInstPtr & inst, Addr corrTarget); 9610244Satgutier@umich.edu 9710244Satgutier@umich.edu void squash(ThreadID tid, void *bp_history) 9811434Smitch.hayenga@arm.com { assert(bp_history == NULL); } 9910244Satgutier@umich.edu 10010244Satgutier@umich.edu void reset(); 10110244Satgutier@umich.edu 10210244Satgutier@umich.edu private: 10310244Satgutier@umich.edu /** 10410244Satgutier@umich.edu * Returns the taken/not taken prediction given the value of the 10510244Satgutier@umich.edu * counter. 10610244Satgutier@umich.edu * @param count The value of the counter. 10710244Satgutier@umich.edu * @return The prediction based on the counter value. 10810244Satgutier@umich.edu */ 10910244Satgutier@umich.edu inline bool getPrediction(uint8_t &count); 11010244Satgutier@umich.edu 11110244Satgutier@umich.edu /** Calculates the local index based on the PC. */ 11210244Satgutier@umich.edu inline unsigned getLocalIndex(Addr &PC); 11310244Satgutier@umich.edu 11410244Satgutier@umich.edu /** Array of counters that make up the local predictor. */ 115 std::vector<SatCounter> localCtrs; 116 117 /** Size of the local predictor. */ 118 unsigned localPredictorSize; 119 120 /** Number of sets. */ 121 unsigned localPredictorSets; 122 123 /** Number of bits of the local predictor's counters. */ 124 unsigned localCtrBits; 125 126 /** Mask to get index bits. */ 127 unsigned indexMask; 128}; 129 130#endif // __CPU_PRED_2BIT_LOCAL_PRED_HH__ 131