rob_impl.hh

来自「M5,一个功能强大的多处理器系统模拟器.很多针对处理器架构,性能的研究都使用它作」· HH 代码 · 共 696 行 · 第 1/2 页

ROB<Impl>::doSquash(unsigned tid)
{
    DPRINTF(ROB, "[tid:%u]: Squashing instructions until [sn:%i].\n",
            tid, squashedSeqNum[tid]);

    assert(squashIt[tid] != instList[tid].end());

    if ((*squashIt[tid])->seqNum < squashedSeqNum[tid]) {
        DPRINTF(ROB, "[tid:%u]: Done squashing instructions.\n",
                tid);

        squashIt[tid] = instList[tid].end();

        doneSquashing[tid] = true;
        return;
    }

    bool robTailUpdate = false;

    for (int numSquashed = 0;
         numSquashed < squashWidth &&
         squashIt[tid] != instList[tid].end() &&
         (*squashIt[tid])->seqNum > squashedSeqNum[tid];
         ++numSquashed)
    {
        DPRINTF(ROB, "[tid:%u]: Squashing instruction PC %#x, seq num %i.\n",
                (*squashIt[tid])->threadNumber,
                (*squashIt[tid])->readPC(),
                (*squashIt[tid])->seqNum);

        // Mark the instruction as squashed, and ready to commit so that
        // it can drain out of the pipeline.
        (*squashIt[tid])->setSquashed();

        (*squashIt[tid])->setCanCommit();


        if (squashIt[tid] == instList[tid].begin()) {
            DPRINTF(ROB, "Reached head of instruction list while "
                    "squashing.\n");

            squashIt[tid] = instList[tid].end();

            doneSquashing[tid] = true;

            return;
        }

        InstIt tail_thread = instList[tid].end();
        tail_thread--;

        if ((*squashIt[tid]) == (*tail_thread))
            robTailUpdate = true;

        squashIt[tid]--;
    }


    // Check if ROB is done squashing.
    if ((*squashIt[tid])->seqNum <= squashedSeqNum[tid]) {
        DPRINTF(ROB, "[tid:%u]: Done squashing instructions.\n",
                tid);

        squashIt[tid] = instList[tid].end();

        doneSquashing[tid] = true;
    }

    if (robTailUpdate) {
        updateTail();
    }
}


template <class Impl>
void
ROB<Impl>::updateHead()
{
    DynInstPtr head_inst;
    InstSeqNum lowest_num = 0;
    bool first_valid = true;

    // @todo: set ActiveThreads through ROB or CPU
    std::list<unsigned>::iterator threads = activeThreads->begin();
    std::list<unsigned>::iterator end = activeThreads->end();

    while (threads != end) {
        unsigned tid = *threads++;

        if (instList[tid].empty())
            continue;

        if (first_valid) {
            head = instList[tid].begin();
            lowest_num = (*head)->seqNum;
            first_valid = false;
            continue;
        }

        InstIt head_thread = instList[tid].begin();

        DynInstPtr head_inst = (*head_thread);

        assert(head_inst != 0);

        if (head_inst->seqNum < lowest_num) {
            head = head_thread;
            lowest_num = head_inst->seqNum;
        }
    }

    if (first_valid) {
        head = instList[0].end();
    }

}

template <class Impl>
void
ROB<Impl>::updateTail()
{
    tail = instList[0].end();
    bool first_valid = true;

    std::list<unsigned>::iterator threads = activeThreads->begin();
    std::list<unsigned>::iterator end = activeThreads->end();

    while (threads != end) {
        unsigned tid = *threads++;

        if (instList[tid].empty()) {
            continue;
        }

        // If this is the first valid then assign w/out
        // comparison
        if (first_valid) {
            tail = instList[tid].end();
            tail--;
            first_valid = false;
            continue;
        }

        // Assign new tail if this thread's tail is younger
        // than our current "tail high"
        InstIt tail_thread = instList[tid].end();
        tail_thread--;

        if ((*tail_thread)->seqNum > (*tail)->seqNum) {
            tail = tail_thread;
        }
    }
}


template <class Impl>
void
ROB<Impl>::squash(InstSeqNum squash_num,unsigned tid)
{
    if (isEmpty()) {
        DPRINTF(ROB, "Does not need to squash due to being empty "
                "[sn:%i]\n",
                squash_num);

        return;
    }

    DPRINTF(ROB, "Starting to squash within the ROB.\n");

    robStatus[tid] = ROBSquashing;

    doneSquashing[tid] = false;

    squashedSeqNum[tid] = squash_num;

    if (!instList[tid].empty()) {
        InstIt tail_thread = instList[tid].end();
        tail_thread--;

        squashIt[tid] = tail_thread;

        doSquash(tid);
    }
}
/*
template <class Impl>
typename Impl::DynInstPtr
ROB<Impl>::readHeadInst()
{
    if (numInstsInROB != 0) {
        assert((*head)->isInROB()==true);
        return *head;
    } else {
        return dummyInst;
    }
}
*/

template <class Impl>
typename Impl::DynInstPtr
ROB<Impl>::readHeadInst(unsigned tid)
{
    if (threadEntries[tid] != 0) {
        InstIt head_thread = instList[tid].begin();

        assert((*head_thread)->isInROB()==true);

        return *head_thread;
    } else {
        return dummyInst;
    }
}

/*
template <class Impl>
uint64_t
ROB<Impl>::readHeadPC()
{
    //assert(numInstsInROB == countInsts());

    DynInstPtr head_inst = *head;

    return head_inst->readPC();
}

template <class Impl>
uint64_t
ROB<Impl>::readHeadPC(unsigned tid)
{
    //assert(numInstsInROB == countInsts());
    InstIt head_thread = instList[tid].begin();

    return (*head_thread)->readPC();
}


template <class Impl>
uint64_t
ROB<Impl>::readHeadNextPC()
{
    //assert(numInstsInROB == countInsts());

    DynInstPtr head_inst = *head;

    return head_inst->readNextPC();
}

template <class Impl>
uint64_t
ROB<Impl>::readHeadNextPC(unsigned tid)
{
    //assert(numInstsInROB == countInsts());
    InstIt head_thread = instList[tid].begin();

    return (*head_thread)->readNextPC();
}

template <class Impl>
InstSeqNum
ROB<Impl>::readHeadSeqNum()
{
    //assert(numInstsInROB == countInsts());
    DynInstPtr head_inst = *head;

    return head_inst->seqNum;
}

template <class Impl>
InstSeqNum
ROB<Impl>::readHeadSeqNum(unsigned tid)
{
    InstIt head_thread = instList[tid].begin();

    return ((*head_thread)->seqNum);
}

template <class Impl>
typename Impl::DynInstPtr
ROB<Impl>::readTailInst()
{
    //assert(numInstsInROB == countInsts());
    //assert(tail != instList[0].end());

    return (*tail);
}
*/
template <class Impl>
typename Impl::DynInstPtr
ROB<Impl>::readTailInst(unsigned tid)
{
    //assert(tail_thread[tid] != instList[tid].end());

    InstIt tail_thread = instList[tid].end();
    tail_thread--;

    return *tail_thread;
}

/*
template <class Impl>
uint64_t
ROB<Impl>::readTailPC()
{
    //assert(numInstsInROB == countInsts());

    //assert(tail != instList[0].end());

    return (*tail)->readPC();
}

template <class Impl>
uint64_t
ROB<Impl>::readTailPC(unsigned tid)
{
    //assert(tail_thread[tid] != instList[tid].end());

    InstIt tail_thread = instList[tid].end();
    tail_thread--;

    return (*tail_thread)->readPC();
}

template <class Impl>
InstSeqNum
ROB<Impl>::readTailSeqNum()
{
    // Return the last sequence number that has not been squashed.  Other
    // stages can use it to squash any instructions younger than the current
    // tail.
    return (*tail)->seqNum;
}

template <class Impl>
InstSeqNum
ROB<Impl>::readTailSeqNum(unsigned tid)
{
    // Return the last sequence number that has not been squashed.  Other
    // stages can use it to squash any instructions younger than the current
    // tail.
    //    assert(tail_thread[tid] != instList[tid].end());

    InstIt tail_thread = instList[tid].end();
    tail_thread--;

    return (*tail_thread)->seqNum;
}
*/