src/cpu/ozone/front_end.hh

/*
 * Copyright (c) 2006 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.
 *
 * Authors: Kevin Lim
 */

#ifndef __CPU_OZONE_FRONT_END_HH__
#define __CPU_OZONE_FRONT_END_HH__

#include <deque>

#include "arch/utility.hh"
#include "config/the_isa.hh"
#include "cpu/o3/bpred_unit.hh"
#include "cpu/ozone/rename_table.hh"
#include "cpu/inst_seq.hh"
#include "cpu/timebuf.hh"
#include "mem/port.hh"
#include "mem/request.hh"
#include "sim/eventq.hh"
#include "sim/stats.hh"

class ThreadContext;
class MemObject;
template <class>
class OzoneThreadState;
class PageTable;
template <class>
class TimeBuffer;

template <class Impl>
class FrontEnd
{
  public:
    typedef typename Impl::Params Params;
    typedef typename Impl::DynInst DynInst;
    typedef typename Impl::DynInstPtr DynInstPtr;
    typedef typename Impl::CPUType CPUType;
    typedef typename Impl::BackEnd BackEnd;

    typedef typename Impl::CPUType::OzoneTC OzoneTC;
    typedef typename Impl::CPUType::CommStruct CommStruct;

    /** IcachePort class.  Handles doing the communication with the
     * cache/memory.
     */
    class IcachePort : public MasterPort
    {
      protected:
        /** Pointer to FE. */
        FrontEnd<Impl> *fe;

      public:
        /** Default constructor. */
        IcachePort(FrontEnd<Impl> *_fe)
            : fe(_fe)
        { }

      protected:
        /** Atomic version of receive.  Panics. */
        virtual Tick recvAtomic(PacketPtr pkt);

        /** Functional version of receive.  Panics. */
        virtual void recvFunctional(PacketPtr pkt);

        /** Timing version of receive.  Handles setting fetch to the
         * proper status to start fetching. */
        virtual bool recvTiming(PacketPtr pkt);

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

    FrontEnd(Params *params);

    std::string name() const;

    void setCPU(CPUType *cpu_ptr);

    void setBackEnd(BackEnd *back_end_ptr)
    { backEnd = back_end_ptr; }

    void setCommBuffer(TimeBuffer<CommStruct> *_comm);

    void setTC(ThreadContext *tc_ptr);

    void setThreadState(OzoneThreadState<Impl> *thread_ptr)
    { thread = thread_ptr; }

    void regStats();

    Port *getIcachePort() { return &icachePort; }

    void tick();
    Fault fetchCacheLine();
    void processInst(DynInstPtr &inst);
    void squash(const InstSeqNum &squash_num, const Addr &next_PC,
                const bool is_branch = false, const bool branch_taken = false);
    DynInstPtr getInst();

    void processCacheCompletion(PacketPtr pkt);

    void addFreeRegs(int num_freed);

    bool isEmpty() { return instBuffer.empty(); }

    void switchOut();

    void doSwitchOut();

    void takeOverFrom(ThreadContext *old_tc = NULL);

    bool isSwitchedOut() { return switchedOut; }

    bool switchedOut;

  private:
    void recvRetry();

    bool updateStatus();

    void checkBE();
    DynInstPtr getInstFromCacheline();
    void renameInst(DynInstPtr &inst);
    // Returns true if we need to stop the front end this cycle
    bool processBarriers(DynInstPtr &inst);

    void handleFault(Fault &fault);
  public:
    Fault getFault() { return fetchFault; }
  private:
    Fault fetchFault;

    // Align an address (typically a PC) to the start of an I-cache block.
    // We fold in the PISA 64- to 32-bit conversion here as well.
    Addr icacheBlockAlignPC(Addr addr)
    {
        return (addr & ~(cacheBlkMask));
    }

    InstSeqNum getAndIncrementInstSeq()
    { return cpu->globalSeqNum++; }

  public:
    CPUType *cpu;

    BackEnd *backEnd;

    ThreadContext *tc;

    OzoneThreadState<Impl> *thread;

    enum Status {
        Running,
        Idle,
        IcacheWaitResponse,
        IcacheWaitRetry,
        IcacheAccessComplete,
        SerializeBlocked,
        SerializeComplete,
        RenameBlocked,
        QuiescePending,
        TrapPending,
        BEBlocked
    };

    Status status;

  private:
    TimeBuffer<CommStruct> *comm;
    typename TimeBuffer<CommStruct>::wire fromCommit;

    typedef typename Impl::BranchPred BranchPred;

    BranchPred branchPred;

    IcachePort icachePort;

    RequestPtr memReq;

    /** Mask to get a cache block's address. */
    Addr cacheBlkMask;

    unsigned cacheBlkSize;

    Addr cacheBlkPC;

    /** The cache line being fetched. */
    uint8_t *cacheData;

    bool fetchCacheLineNextCycle;

    bool cacheBlkValid;

    bool cacheBlocked;

    /** The packet that is waiting to be retried. */
    PacketPtr retryPkt;

  public:
    RenameTable<Impl> renameTable;

  private:
    Addr PC;
    Addr nextPC;

  public:
    void setPC(Addr val) { PC = val; }
    void setNextPC(Addr val) { nextPC = val; }

    void wakeFromQuiesce();

    void dumpInsts();

  private:
    TimeBuffer<int> numInstsReady;

    typedef typename std::deque<DynInstPtr> InstBuff;
    typedef typename InstBuff::iterator InstBuffIt;

    InstBuff feBuffer;

    InstBuff instBuffer;

    int instBufferSize;

    int maxInstBufferSize;

    int latency;

    int width;

    int freeRegs;

    int numPhysRegs;

    bool serializeNext;

    DynInstPtr barrierInst;

  public:
    bool interruptPending;
  private:
    // number of idle cycles
/*
    Stats::Average notIdleFraction;
    Stats::Formula idleFraction;
*/
    // @todo: Consider making these vectors and tracking on a per thread basis.
    /** Stat for total number of cycles stalled due to an icache miss. */
    Stats::Scalar icacheStallCycles;
    /** Stat for total number of fetched instructions. */
    Stats::Scalar fetchedInsts;
    Stats::Scalar fetchedBranches;
    /** Stat for total number of predicted branches. */
    Stats::Scalar predictedBranches;
    /** Stat for total number of cycles spent fetching. */
    Stats::Scalar fetchCycles;

    Stats::Scalar fetchIdleCycles;
    /** Stat for total number of cycles spent squashing. */
    Stats::Scalar fetchSquashCycles;
    /** Stat for total number of cycles spent blocked due to other stages in
     * the pipeline.
     */
    Stats::Scalar fetchBlockedCycles;
    /** Stat for total number of fetched cache lines. */
    Stats::Scalar fetchedCacheLines;

    Stats::Scalar fetchIcacheSquashes;
    /** Distribution of number of instructions fetched each cycle. */
    Stats::Distribution fetchNisnDist;
//    Stats::Vector qfull_iq_occupancy;
//    Stats::VectorDistribution qfull_iq_occ_dist_;
    Stats::Formula idleRate;
    Stats::Formula branchRate;
    Stats::Formula fetchRate;
    Stats::Scalar IFQCount;   // cumulative IFQ occupancy
    Stats::Formula IFQOccupancy;
    Stats::Formula IFQLatency;
    Stats::Scalar IFQFcount; // cumulative IFQ full count
    Stats::Formula IFQFullRate;

    Stats::Scalar dispatchCountStat;
    Stats::Scalar dispatchedSerializing;
    Stats::Scalar dispatchedTempSerializing;
    Stats::Scalar dispatchSerializeStallCycles;
    Stats::Formula dispatchRate;
    Stats::Formula regIntFull;
    Stats::Formula regFpFull;
};

#endif // __CPU_OZONE_FRONT_END_HH__