86 lines
3.1 KiB
C++
86 lines
3.1 KiB
C++
/*
|
|
* Copyright (c) 2004-2005 The Regents of The University of Michigan
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions are
|
|
* met: redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer;
|
|
* redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution;
|
|
* neither the name of the copyright holders nor the names of its
|
|
* contributors may be used to endorse or promote products derived from
|
|
* this software without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
|
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
|
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
|
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
|
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
|
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
|
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
|
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
*/
|
|
|
|
#ifndef __CPU_BETA_CPU_2BIT_LOCAL_PRED_HH__
|
|
#define __CPU_BETA_CPU_2BIT_LOCAL_PRED_HH__
|
|
|
|
// For Addr type.
|
|
#include "arch/alpha/isa_traits.hh"
|
|
#include "cpu/beta_cpu/sat_counter.hh"
|
|
|
|
class DefaultBP
|
|
{
|
|
public:
|
|
/**
|
|
* Default branch predictor constructor.
|
|
*/
|
|
DefaultBP(unsigned localPredictorSize, unsigned localCtrBits,
|
|
unsigned instShiftAmt);
|
|
|
|
/**
|
|
* Looks up the given address in the branch predictor and returns
|
|
* a true/false value as to whether it is taken.
|
|
* @param branch_addr The address of the branch to look up.
|
|
* @return Whether or not the branch is taken.
|
|
*/
|
|
bool lookup(Addr &branch_addr);
|
|
|
|
/**
|
|
* Updates the branch predictor with the actual result of a branch.
|
|
* @param branch_addr The address of the branch to update.
|
|
* @param taken Whether or not the branch was taken.
|
|
*/
|
|
void update(Addr &branch_addr, bool taken);
|
|
|
|
private:
|
|
|
|
/** Returns the taken/not taken prediction given the value of the
|
|
* counter.
|
|
*/
|
|
inline bool getPrediction(uint8_t &count);
|
|
|
|
/** Calculates the local index based on the PC. */
|
|
inline unsigned getLocalIndex(Addr &PC);
|
|
|
|
/** Array of counters that make up the local predictor. */
|
|
SatCounter *localCtrs;
|
|
|
|
/** Size of the local predictor. */
|
|
unsigned localPredictorSize;
|
|
|
|
/** Number of bits of the local predictor's counters. */
|
|
unsigned localCtrBits;
|
|
|
|
/** Number of bits to shift the PC when calculating index. */
|
|
unsigned instShiftAmt;
|
|
|
|
/** Mask to get index bits. */
|
|
unsigned indexMask;
|
|
};
|
|
|
|
#endif // __CPU_BETA_CPU_2BIT_LOCAL_PRED_HH__
|