xref: /gem5/src/cpu/o3/cpu.hh

/*
 * Copyright (c) 2011-2012 ARM Limited
 * All rights reserved
 *
 * The license below extends only to copyright in the software and shall
 * not be construed as granting a license to any other intellectual
 * property including but not limited to intellectual property relating
 * to a hardware implementation of the functionality of the software
 * licensed hereunder.  You may use the software subject to the license
 * terms below provided that you ensure that this notice is replicated
 * unmodified and in its entirety in all distributions of the software,
 * modified or unmodified, in source code or in binary form.
 *
 * Copyright (c) 2004-2005 The Regents of The University of Michigan
 * Copyright (c) 2011 Regents of the University of California
 * 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.
 *
 * Authors: Kevin Lim
 *          Korey Sewell
 *          Rick Strong
 */

#ifndef __CPU_O3_CPU_HH__
#define __CPU_O3_CPU_HH__

#include <iostream>
#include <list>
#include <queue>
#include <set>
#include <vector>

#include "arch/types.hh"
#include "base/statistics.hh"
#include "config/the_isa.hh"
#include "cpu/o3/comm.hh"
#include "cpu/o3/cpu_policy.hh"
#include "cpu/o3/scoreboard.hh"
#include "cpu/o3/thread_state.hh"
#include "cpu/activity.hh"
#include "cpu/base.hh"
#include "cpu/simple_thread.hh"
#include "cpu/timebuf.hh"
//#include "cpu/o3/thread_context.hh"
#include "params/DerivO3CPU.hh"
#include "sim/process.hh"

template <class>
class Checker;
class ThreadContext;
template <class>
class O3ThreadContext;

class Checkpoint;
class MemObject;
class Process;

struct BaseCPUParams;

class BaseO3CPU : public BaseCPU
{
    //Stuff that's pretty ISA independent will go here.
  public:
    BaseO3CPU(BaseCPUParams *params);

    void regStats();
};

/**
 * FullO3CPU class, has each of the stages (fetch through commit)
 * within it, as well as all of the time buffers between stages.  The
 * tick() function for the CPU is defined here.
 */
template <class Impl>
class FullO3CPU : public BaseO3CPU
{
  public:
    // Typedefs from the Impl here.
    typedef typename Impl::CPUPol CPUPolicy;
    typedef typename Impl::DynInstPtr DynInstPtr;
    typedef typename Impl::O3CPU O3CPU;

    typedef O3ThreadState<Impl> ImplState;
    typedef O3ThreadState<Impl> Thread;

    typedef typename std::list<DynInstPtr>::iterator ListIt;

    friend class O3ThreadContext<Impl>;

  public:
    enum Status {
        Running,
        Idle,
        Halted,
        Blocked,
        SwitchedOut
    };

    TheISA::TLB * itb;
    TheISA::TLB * dtb;

    /** Overall CPU status. */
    Status _status;

  private:

    /**
     * IcachePort class for instruction fetch.
     */
    class IcachePort : public CpuPort
    {
      protected:
        /** Pointer to fetch. */
        DefaultFetch<Impl> *fetch;

      public:
        /** Default constructor. */
        IcachePort(DefaultFetch<Impl> *_fetch, FullO3CPU<Impl>* _cpu)
            : CpuPort(_cpu->name() + ".icache_port", _cpu), fetch(_fetch)
        { }

      protected:

        /** Timing version of receive.  Handles setting fetch to the
         * proper status to start fetching. */
        virtual bool recvTimingResp(PacketPtr pkt);
        virtual void recvTimingSnoopReq(PacketPtr pkt) { }

        /** Handles doing a retry of a failed fetch. */
        virtual void recvRetry();
    };

    /**
     * DcachePort class for the load/store queue.
     */
    class DcachePort : public CpuPort
    {
      protected:

        /** Pointer to LSQ. */
        LSQ<Impl> *lsq;

      public:
        /** Default constructor. */
        DcachePort(LSQ<Impl> *_lsq, FullO3CPU<Impl>* _cpu)
            : CpuPort(_cpu->name() + ".dcache_port", _cpu), lsq(_lsq)
        { }

      protected:

        /** Timing version of receive.  Handles writing back and
         * completing the load or store that has returned from
         * memory. */
        virtual bool recvTimingResp(PacketPtr pkt);
        virtual void recvTimingSnoopReq(PacketPtr pkt);

        /** Handles doing a retry of the previous send. */
        virtual void recvRetry();

        /**
         * As this CPU requires snooping to maintain the load store queue
         * change the behaviour from the base CPU port.
         *
         * @return true since we have to snoop
         */
        virtual bool isSnooping() const { return true; }
    };

    class TickEvent : public Event
    {
      private:
        /** Pointer to the CPU. */
        FullO3CPU<Impl> *cpu;

      public:
        /** Constructs a tick event. */
        TickEvent(FullO3CPU<Impl> *c);

        /** Processes a tick event, calling tick() on the CPU. */
        void process();
        /** Returns the description of the tick event. */
        const char *description() const;
    };

    /** The tick event used for scheduling CPU ticks. */
    TickEvent tickEvent;

    /** Schedule tick event, regardless of its current state. */
    void scheduleTickEvent(Cycles delay)
    {
        if (tickEvent.squashed())
            reschedule(tickEvent, clockEdge(delay));
        else if (!tickEvent.scheduled())
            schedule(tickEvent, clockEdge(delay));
    }

    /** Unschedule tick event, regardless of its current state. */
    void unscheduleTickEvent()
    {
        if (tickEvent.scheduled())
            tickEvent.squash();
    }

    class ActivateThreadEvent : public Event
    {
      private:
        /** Number of Thread to Activate */
        ThreadID tid;

        /** Pointer to the CPU. */
        FullO3CPU<Impl> *cpu;

      public:
        /** Constructs the event. */
        ActivateThreadEvent();

        /** Initialize Event */
        void init(int thread_num, FullO3CPU<Impl> *thread_cpu);

        /** Processes the event, calling activateThread() on the CPU. */
        void process();

        /** Returns the description of the event. */
        const char *description() const;
    };

    /** Schedule thread to activate , regardless of its current state. */
    void
    scheduleActivateThreadEvent(ThreadID tid, Cycles delay)
    {
        // Schedule thread to activate, regardless of its current state.
        if (activateThreadEvent[tid].squashed())
            reschedule(activateThreadEvent[tid],
                       clockEdge(delay));
        else if (!activateThreadEvent[tid].scheduled()) {
            Tick when = clockEdge(delay);

            // Check if the deallocateEvent is also scheduled, and make
            // sure they do not happen at same time causing a sleep that
            // is never woken from.
            if (deallocateContextEvent[tid].scheduled() &&
                deallocateContextEvent[tid].when() == when) {
                when++;
            }

            schedule(activateThreadEvent[tid], when);
        }
    }

    /** Unschedule actiavte thread event, regardless of its current state. */
    void
    unscheduleActivateThreadEvent(ThreadID tid)
    {
        if (activateThreadEvent[tid].scheduled())
            activateThreadEvent[tid].squash();
    }

    /** The tick event used for scheduling CPU ticks. */
    ActivateThreadEvent activateThreadEvent[Impl::MaxThreads];

    class DeallocateContextEvent : public Event
    {
      private:
        /** Number of Thread to deactivate */
        ThreadID tid;

        /** Should the thread be removed from the CPU? */
        bool remove;

        /** Pointer to the CPU. */
        FullO3CPU<Impl> *cpu;

      public:
        /** Constructs the event. */
        DeallocateContextEvent();

        /** Initialize Event */
        void init(int thread_num, FullO3CPU<Impl> *thread_cpu);

        /** Processes the event, calling activateThread() on the CPU. */
        void process();

        /** Sets whether the thread should also be removed from the CPU. */
        void setRemove(bool _remove) { remove = _remove; }

        /** Returns the description of the event. */
        const char *description() const;
    };

    /** Schedule cpu to deallocate thread context.*/
    void
    scheduleDeallocateContextEvent(ThreadID tid, bool remove, Cycles delay)
    {
        // Schedule thread to activate, regardless of its current state.
        if (deallocateContextEvent[tid].squashed())
            reschedule(deallocateContextEvent[tid],
                       clockEdge(delay));
        else if (!deallocateContextEvent[tid].scheduled())
            schedule(deallocateContextEvent[tid],
                     clockEdge(delay));
    }

    /** Unschedule thread deallocation in CPU */
    void
    unscheduleDeallocateContextEvent(ThreadID tid)
    {
        if (deallocateContextEvent[tid].scheduled())
            deallocateContextEvent[tid].squash();
    }

    /** The tick event used for scheduling CPU ticks. */
    DeallocateContextEvent deallocateContextEvent[Impl::MaxThreads];

    /**
     * Check if the pipeline has drained and signal the DrainManager.
     *
     * This method checks if a drain has been requested and if the CPU
     * has drained successfully (i.e., there are no instructions in
     * the pipeline). If the CPU has drained, it deschedules the tick
     * event and signals the drain manager.
     *
     * @return False if a drain hasn't been requested or the CPU
     * hasn't drained, true otherwise.
     */
    bool tryDrain();

    /**
     * Perform sanity checks after a drain.
     *
     * This method is called from drain() when it has determined that
     * the CPU is fully drained when gem5 is compiled with the NDEBUG
     * macro undefined. The intention of this method is to do more
     * extensive tests than the isDrained() method to weed out any
     * draining bugs.
     */
    void drainSanityCheck() const;

    /** Check if a system is in a drained state. */
    bool isDrained() const;

  public:
    /** Constructs a CPU with the given parameters. */
    FullO3CPU(DerivO3CPUParams *params);
    /** Destructor. */
    ~FullO3CPU();

    /** Registers statistics. */
    void regStats();

    void demapPage(Addr vaddr, uint64_t asn)
    {
        this->itb->demapPage(vaddr, asn);
        this->dtb->demapPage(vaddr, asn);
    }

    void demapInstPage(Addr vaddr, uint64_t asn)
    {
        this->itb->demapPage(vaddr, asn);
    }

    void demapDataPage(Addr vaddr, uint64_t asn)
    {
        this->dtb->demapPage(vaddr, asn);
    }

    /** Ticks CPU, calling tick() on each stage, and checking the overall
     *  activity to see if the CPU should deschedule itself.
     */
    void tick();

    /** Initialize the CPU */
    void init();

    void startup();

    /** Returns the Number of Active Threads in the CPU */
    int numActiveThreads()
    { return activeThreads.size(); }

    /** Add Thread to Active Threads List */
    void activateThread(ThreadID tid);

    /** Remove Thread from Active Threads List */
    void deactivateThread(ThreadID tid);

    /** Setup CPU to insert a thread's context */
    void insertThread(ThreadID tid);

    /** Remove all of a thread's context from CPU */
    void removeThread(ThreadID tid);

    /** Count the Total Instructions Committed in the CPU. */
    virtual Counter totalInsts() const;

    /** Count the Total Ops (including micro ops) committed in the CPU. */
    virtual Counter totalOps() const;

    /** Add Thread to Active Threads List. */
    void activateContext(ThreadID tid, Cycles delay);

    /** Remove Thread from Active Threads List */
    void suspendContext(ThreadID tid);

    /** Remove Thread from Active Threads List &&
     *  Possibly Remove Thread Context from CPU.
     */
    bool scheduleDeallocateContext(ThreadID tid, bool remove,
                                   Cycles delay = Cycles(1));

    /** Remove Thread from Active Threads List &&
     *  Remove Thread Context from CPU.
     */
    void haltContext(ThreadID tid);

    /** Activate a Thread When CPU Resources are Available. */
    void activateWhenReady(ThreadID tid);

    /** Add or Remove a Thread Context in the CPU. */
    void doContextSwitch();

    /** Update The Order In Which We Process Threads. */
    void updateThreadPriority();

    /** Is the CPU draining? */
    bool isDraining() const { return getDrainState() == Drainable::Draining; }

    /** Serialize state. */
    virtual void serialize(std::ostream &os);

    /** Unserialize from a checkpoint. */
    virtual void unserialize(Checkpoint *cp, const std::string &section);

  public:
    /** Executes a syscall.
     * @todo: Determine if this needs to be virtual.
     */
    void syscall(int64_t callnum, ThreadID tid);

    /** Starts draining the CPU's pipeline of all instructions in
     * order to stop all memory accesses. */
    unsigned int drain(DrainManager *drain_manager);

    /** Resumes execution after a drain. */
    void drainResume();

    /**
     * Commit has reached a safe point to drain a thread.
     *
     * Commit calls this method to inform the pipeline that it has
     * reached a point where it is not executed microcode and is about
     * to squash uncommitted instructions to fully drain the pipeline.
     */
    void commitDrained(ThreadID tid);

    /** Switches out this CPU. */
    virtual void switchOut();

    /** Takes over from another CPU. */
    virtual void takeOverFrom(BaseCPU *oldCPU);

    /** Get the current instruction sequence number, and increment it. */
    InstSeqNum getAndIncrementInstSeq()
    { return globalSeqNum++; }

    /** Traps to handle given fault. */
    void trap(Fault fault, ThreadID tid, StaticInstPtr inst);

    /** HW return from error interrupt. */
    Fault hwrei(ThreadID tid);

    bool simPalCheck(int palFunc, ThreadID tid);

    /** Returns the Fault for any valid interrupt. */
    Fault getInterrupts();

    /** Processes any an interrupt fault. */
    void processInterrupts(Fault interrupt);

    /** Halts the CPU. */
    void halt() { panic("Halt not implemented!\n"); }

    /** Check if this address is a valid instruction address. */
    bool validInstAddr(Addr addr) { return true; }

    /** Check if this address is a valid data address. */
    bool validDataAddr(Addr addr) { return true; }

    /** Register accessors.  Index refers to the physical register index. */

    /** Reads a miscellaneous register. */
    TheISA::MiscReg readMiscRegNoEffect(int misc_reg, ThreadID tid);

    /** Reads a misc. register, including any side effects the read
     * might have as defined by the architecture.
     */
    TheISA::MiscReg readMiscReg(int misc_reg, ThreadID tid);

    /** Sets a miscellaneous register. */
    void setMiscRegNoEffect(int misc_reg, const TheISA::MiscReg &val,
            ThreadID tid);

    /** Sets a misc. register, including any side effects the write
     * might have as defined by the architecture.
     */
    void setMiscReg(int misc_reg, const TheISA::MiscReg &val,
            ThreadID tid);

    uint64_t readIntReg(int reg_idx);

    TheISA::FloatReg readFloatReg(int reg_idx);

    TheISA::FloatRegBits readFloatRegBits(int reg_idx);

    void setIntReg(int reg_idx, uint64_t val);

    void setFloatReg(int reg_idx, TheISA::FloatReg val);

    void setFloatRegBits(int reg_idx, TheISA::FloatRegBits val);

    uint64_t readArchIntReg(int reg_idx, ThreadID tid);

    float readArchFloatReg(int reg_idx, ThreadID tid);

    uint64_t readArchFloatRegInt(int reg_idx, ThreadID tid);

    /** Architectural register accessors.  Looks up in the commit
     * rename table to obtain the true physical index of the
     * architected register first, then accesses that physical
     * register.
     */
    void setArchIntReg(int reg_idx, uint64_t val, ThreadID tid);

    void setArchFloatReg(int reg_idx, float val, ThreadID tid);

    void setArchFloatRegInt(int reg_idx, uint64_t val, ThreadID tid);

    /** Sets the commit PC state of a specific thread. */
    void pcState(const TheISA::PCState &newPCState, ThreadID tid);

    /** Reads the commit PC state of a specific thread. */
    TheISA::PCState pcState(ThreadID tid);

    /** Reads the commit PC of a specific thread. */
    Addr instAddr(ThreadID tid);

    /** Reads the commit micro PC of a specific thread. */
    MicroPC microPC(ThreadID tid);

    /** Reads the next PC of a specific thread. */
    Addr nextInstAddr(ThreadID tid);

    /** Initiates a squash of all in-flight instructions for a given
     * thread.  The source of the squash is an external update of
     * state through the TC.
     */
    void squashFromTC(ThreadID tid);

    /** Function to add instruction onto the head of the list of the
     *  instructions.  Used when new instructions are fetched.
     */
    ListIt addInst(DynInstPtr &inst);

    /** Function to tell the CPU that an instruction has completed. */
    void instDone(ThreadID tid, DynInstPtr &inst);

    /** Remove an instruction from the front end of the list.  There's
     *  no restriction on location of the instruction.
     */
    void removeFrontInst(DynInstPtr &inst);

    /** Remove all instructions that are not currently in the ROB.
     *  There's also an option to not squash delay slot instructions.*/
    void removeInstsNotInROB(ThreadID tid);

    /** Remove all instructions younger than the given sequence number. */
    void removeInstsUntil(const InstSeqNum &seq_num, ThreadID tid);

    /** Removes the instruction pointed to by the iterator. */
    inline void squashInstIt(const ListIt &instIt, ThreadID tid);

    /** Cleans up all instructions on the remove list. */
    void cleanUpRemovedInsts();

    /** Debug function to print all instructions on the list. */
    void dumpInsts();

  public:
#ifndef NDEBUG
    /** Count of total number of dynamic instructions in flight. */
    int instcount;
#endif

    /** List of all the instructions in flight. */
    std::list<DynInstPtr> instList;

    /** List of all the instructions that will be removed at the end of this
     *  cycle.
     */
    std::queue<ListIt> removeList;

#ifdef DEBUG
    /** Debug structure to keep track of the sequence numbers still in
     * flight.
     */
    std::set<InstSeqNum> snList;
#endif

    /** Records if instructions need to be removed this cycle due to
     *  being retired or squashed.
     */
    bool removeInstsThisCycle;

  protected:
    /** The fetch stage. */
    typename CPUPolicy::Fetch fetch;

    /** The decode stage. */
    typename CPUPolicy::Decode decode;

    /** The dispatch stage. */
    typename CPUPolicy::Rename rename;

    /** The issue/execute/writeback stages. */
    typename CPUPolicy::IEW iew;

    /** The commit stage. */
    typename CPUPolicy::Commit commit;

    /** The register file. */
    typename CPUPolicy::RegFile regFile;

    /** The free list. */
    typename CPUPolicy::FreeList freeList;

    /** The rename map. */
    typename CPUPolicy::RenameMap renameMap[Impl::MaxThreads];

    /** The commit rename map. */
    typename CPUPolicy::RenameMap commitRenameMap[Impl::MaxThreads];

    /** The re-order buffer. */
    typename CPUPolicy::ROB rob;

    /** Active Threads List */
    std::list<ThreadID> activeThreads;

    /** Integer Register Scoreboard */
    Scoreboard scoreboard;

    std::vector<TheISA::ISA *> isa;

    /** Instruction port. Note that it has to appear after the fetch stage. */
    IcachePort icachePort;

    /** Data port. Note that it has to appear after the iew stages */
    DcachePort dcachePort;

  public:
    /** Enum to give each stage a specific index, so when calling
     *  activateStage() or deactivateStage(), they can specify which stage
     *  is being activated/deactivated.
     */
    enum StageIdx {
        FetchIdx,
        DecodeIdx,
        RenameIdx,
        IEWIdx,
        CommitIdx,
        NumStages };

    /** Typedefs from the Impl to get the structs that each of the
     *  time buffers should use.
     */
    typedef typename CPUPolicy::TimeStruct TimeStruct;

    typedef typename CPUPolicy::FetchStruct FetchStruct;

    typedef typename CPUPolicy::DecodeStruct DecodeStruct;

    typedef typename CPUPolicy::RenameStruct RenameStruct;

    typedef typename CPUPolicy::IEWStruct IEWStruct;

    /** The main time buffer to do backwards communication. */
    TimeBuffer<TimeStruct> timeBuffer;

    /** The fetch stage's instruction queue. */
    TimeBuffer<FetchStruct> fetchQueue;

    /** The decode stage's instruction queue. */
    TimeBuffer<DecodeStruct> decodeQueue;

    /** The rename stage's instruction queue. */
    TimeBuffer<RenameStruct> renameQueue;

    /** The IEW stage's instruction queue. */
    TimeBuffer<IEWStruct> iewQueue;

  private:
    /** The activity recorder; used to tell if the CPU has any
     * activity remaining or if it can go to idle and deschedule
     * itself.
     */
    ActivityRecorder activityRec;

  public:
    /** Records that there was time buffer activity this cycle. */
    void activityThisCycle() { activityRec.activity(); }

    /** Changes a stage's status to active within the activity recorder. */
    void activateStage(const StageIdx idx)
    { activityRec.activateStage(idx); }

    /** Changes a stage's status to inactive within the activity recorder. */
    void deactivateStage(const StageIdx idx)
    { activityRec.deactivateStage(idx); }

    /** Wakes the CPU, rescheduling the CPU if it's not already active. */
    void wakeCPU();

    virtual void wakeup();

    /** Gets a free thread id. Use if thread ids change across system. */
    ThreadID getFreeTid();

  public:
    /** Returns a pointer to a thread context. */
    ThreadContext *
    tcBase(ThreadID tid)
    {
        return thread[tid]->getTC();
    }

    /** The global sequence number counter. */
    InstSeqNum globalSeqNum;//[Impl::MaxThreads];

    /** Pointer to the checker, which can dynamically verify
     * instruction results at run time.  This can be set to NULL if it
     * is not being used.
     */
    Checker<Impl> *checker;

    /** Pointer to the system. */
    System *system;

    /** DrainManager to notify when draining has completed. */
    DrainManager *drainManager;

    /** Pointers to all of the threads in the CPU. */
    std::vector<Thread *> thread;

    /** Is there a context switch pending? */
    bool contextSwitch;

    /** Threads Scheduled to Enter CPU */
    std::list<int> cpuWaitList;

    /** The cycle that the CPU was last running, used for statistics. */
    Cycles lastRunningCycle;

    /** The cycle that the CPU was last activated by a new thread*/
    Tick lastActivatedCycle;

    /** Mapping for system thread id to cpu id */
    std::map<ThreadID, unsigned> threadMap;

    /** Available thread ids in the cpu*/
    std::vector<ThreadID> tids;

    /** CPU read function, forwards read to LSQ. */
    Fault read(RequestPtr &req, RequestPtr &sreqLow, RequestPtr &sreqHigh,
               uint8_t *data, int load_idx)
    {
        return this->iew.ldstQueue.read(req, sreqLow, sreqHigh,
                                        data, load_idx);
    }

    /** CPU write function, forwards write to LSQ. */
    Fault write(RequestPtr &req, RequestPtr &sreqLow, RequestPtr &sreqHigh,
                uint8_t *data, int store_idx)
    {
        return this->iew.ldstQueue.write(req, sreqLow, sreqHigh,
                                         data, store_idx);
    }

    /** Used by the fetch unit to get a hold of the instruction port. */
    virtual CpuPort &getInstPort() { return icachePort; }

    /** Get the dcache port (used to find block size for translations). */
    virtual CpuPort &getDataPort() { return dcachePort; }

    /** Stat for total number of times the CPU is descheduled. */
    Stats::Scalar timesIdled;
    /** Stat for total number of cycles the CPU spends descheduled. */
    Stats::Scalar idleCycles;
    /** Stat for total number of cycles the CPU spends descheduled due to a
     * quiesce operation or waiting for an interrupt. */
    Stats::Scalar quiesceCycles;
    /** Stat for the number of committed instructions per thread. */
    Stats::Vector committedInsts;
    /** Stat for the number of committed ops (including micro ops) per thread. */
    Stats::Vector committedOps;
    /** Stat for the total number of committed instructions. */
    Stats::Scalar totalCommittedInsts;
    /** Stat for the CPI per thread. */
    Stats::Formula cpi;
    /** Stat for the total CPI. */
    Stats::Formula totalCpi;
    /** Stat for the IPC per thread. */
    Stats::Formula ipc;
    /** Stat for the total IPC. */
    Stats::Formula totalIpc;

    //number of integer register file accesses
    Stats::Scalar intRegfileReads;
    Stats::Scalar intRegfileWrites;
    //number of float register file accesses
    Stats::Scalar fpRegfileReads;
    Stats::Scalar fpRegfileWrites;
    //number of misc
    Stats::Scalar miscRegfileReads;
    Stats::Scalar miscRegfileWrites;
};

#endif // __CPU_O3_CPU_HH__