src/cpu/pred/ras.cc

/*
 * 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.
 */

#include "cpu/pred/ras.hh"

namespace gem5
{

namespace branch_prediction
{

void
ReturnAddrStack::init(unsigned _numEntries)
{
    numEntries = _numEntries;
    addrStack.resize(numEntries);
    reset();
}

void
ReturnAddrStack::reset()
{
    usedEntries = 0;
    tos = 0;
}

void
ReturnAddrStack::push(const PCStateBase &return_addr)
{
    incrTos();

    set(addrStack[tos], return_addr);

    if (usedEntries != numEntries) {
        ++usedEntries;
    }
}

void
ReturnAddrStack::pop()
{
    if (usedEntries > 0) {
        --usedEntries;
    }

    decrTos();
}

void
ReturnAddrStack::restore(unsigned top_entry_idx, const PCStateBase *restored)
{
    tos = top_entry_idx;

    set(addrStack[tos], restored);

    if (usedEntries != numEntries) {
        ++usedEntries;
    }
}

} // namespace branch_prediction
} // namespace gem5