xref: /gem5/src/mem/cache/cache.hh

/*
 * Copyright (c) 2002-2005 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.
 *
 * Authors: Erik Hallnor
 *          Dave Greene
 *          Steve Reinhardt
 *          Ron Dreslinski
 */

/**
 * @file
 * Describes a cache based on template policies.
 */

#ifndef __CACHE_HH__
#define __CACHE_HH__

#include "base/compression/base.hh"
#include "base/misc.hh" // fatal, panic, and warn
#include "cpu/smt.hh" // SMT_MAX_THREADS

#include "mem/cache/base_cache.hh"
#include "mem/cache/cache_blk.hh"
#include "mem/cache/miss/mshr.hh"

#include "sim/eventq.hh"

//Forward decleration
class BasePrefetcher;

/**
 * A template-policy based cache. The behavior of the cache can be altered by
 * supplying different template policies. TagStore handles all tag and data
 * storage @sa TagStore. Buffering handles all misses and writes/writebacks
 * @sa MissQueue. Coherence handles all coherence policy details @sa
 * UniCoherence, SimpleMultiCoherence.
 */
template <class TagStore, class Coherence>
class Cache : public BaseCache
{
  public:
    /** Define the type of cache block to use. */
    typedef typename TagStore::BlkType BlkType;
    /** A typedef for a list of BlkType pointers. */
    typedef typename TagStore::BlkList BlkList;

    bool prefetchAccess;

  protected:

    class CpuSidePort : public CachePort
    {
      public:
        CpuSidePort(const std::string &_name,
                    Cache<TagStore,Coherence> *_cache);

        // BaseCache::CachePort just has a BaseCache *; this function
        // lets us get back the type info we lost when we stored the
        // cache pointer there.
        Cache<TagStore,Coherence> *myCache() {
            return static_cast<Cache<TagStore,Coherence> *>(cache);
        }

        virtual void getDeviceAddressRanges(AddrRangeList &resp,
                                            bool &snoop);

        virtual bool recvTiming(PacketPtr pkt);

        virtual Tick recvAtomic(PacketPtr pkt);

        virtual void recvFunctional(PacketPtr pkt);
    };

    class MemSidePort : public CachePort
    {
      public:
        MemSidePort(const std::string &_name,
                    Cache<TagStore,Coherence> *_cache);

        // BaseCache::CachePort just has a BaseCache *; this function
        // lets us get back the type info we lost when we stored the
        // cache pointer there.
        Cache<TagStore,Coherence> *myCache() {
            return static_cast<Cache<TagStore,Coherence> *>(cache);
        }

        void sendPacket();

        void processSendEvent();

        virtual void getDeviceAddressRanges(AddrRangeList &resp,
                                            bool &snoop);

        virtual bool recvTiming(PacketPtr pkt);

        virtual void recvRetry();

        virtual Tick recvAtomic(PacketPtr pkt);

        virtual void recvFunctional(PacketPtr pkt);

        typedef EventWrapper<MemSidePort, &MemSidePort::processSendEvent>
                SendEvent;
    };

    /** Tag and data Storage */
    TagStore *tags;

    /** Coherence protocol. */
    Coherence *coherence;

    /** Prefetcher */
    BasePrefetcher *prefetcher;

    /**
     * The clock ratio of the outgoing bus.
     * Used for calculating critical word first.
     */
    int busRatio;

     /**
      * The bus width in bytes of the outgoing bus.
      * Used for calculating critical word first.
      */
    int busWidth;

    /**
     * The latency of a hit in this device.
     */
    int hitLatency;

    /**
     * Can this cache should allocate a block on a line-sized write miss.
     */
    const bool doFastWrites;

    const bool prefetchMiss;

    /**
     * Handle a replacement for the given request.
     * @param blk A pointer to the block, usually NULL
     * @param pkt The memory request to satisfy.
     * @param new_state The new state of the block.
     * @param writebacks A list to store any generated writebacks.
     */
    BlkType* doReplacement(BlkType *blk, PacketPtr pkt,
                           CacheBlk::State new_state, PacketList &writebacks);

    /**
     * Does all the processing necessary to perform the provided request.
     * @param pkt The memory request to perform.
     * @param lat The latency of the access.
     * @param writebacks List for any writebacks that need to be performed.
     * @param update True if the replacement data should be updated.
     * @return Pointer to the cache block touched by the request. NULL if it
     * was a miss.
     */
    bool access(PacketPtr pkt, BlkType *blk, int & lat);

    /**
     *Handle doing the Compare and Swap function for SPARC.
     */
    void cmpAndSwap(BlkType *blk, PacketPtr pkt);

    /**
     * Populates a cache block and handles all outstanding requests for the
     * satisfied fill request. This version takes two memory requests. One
     * contains the fill data, the other is an optional target to satisfy.
     * Used for Cache::probe.
     * @param pkt The memory request with the fill data.
     * @param blk The cache block if it already exists.
     * @param writebacks List for any writebacks that need to be performed.
     * @return Pointer to the new cache block.
     */
    BlkType *handleFill(PacketPtr pkt, BlkType *blk,
                        PacketList &writebacks);

    bool satisfyCpuSideRequest(PacketPtr pkt, BlkType *blk);
    bool satisfyTarget(MSHR::Target *target, BlkType *blk);
    void satisfyMSHR(MSHR *mshr, PacketPtr pkt, BlkType *blk);

    void doTimingSupplyResponse(PacketPtr req_pkt, uint8_t *blk_data);

    /**
     * Sets the blk to the new state.
     * @param blk The cache block being snooped.
     * @param new_state The new coherence state for the block.
     */
    void handleSnoop(PacketPtr ptk, BlkType *blk, bool is_timing);

    /**
     * Create a writeback request for the given block.
     * @param blk The block to writeback.
     * @return The writeback request for the block.
     */
    PacketPtr writebackBlk(BlkType *blk);

  public:

    class Params
    {
      public:
        TagStore *tags;
        Coherence *coherence;
        BaseCache::Params baseParams;
        BasePrefetcher*prefetcher;
        bool prefetchAccess;
        const bool doFastWrites;
        const bool prefetchMiss;

        Params(TagStore *_tags, Coherence *coh,
               BaseCache::Params params,
               BasePrefetcher *_prefetcher,
               bool prefetch_access, int hit_latency,
               bool do_fast_writes,
               bool prefetch_miss)
            : tags(_tags), coherence(coh),
              baseParams(params),
              prefetcher(_prefetcher), prefetchAccess(prefetch_access),
              doFastWrites(do_fast_writes),
              prefetchMiss(prefetch_miss)
        {
        }
    };

    /** Instantiates a basic cache object. */
    Cache(const std::string &_name, Params &params);

    virtual Port *getPort(const std::string &if_name, int idx = -1);
    virtual void deletePortRefs(Port *p);

    void regStats();

    /**
     * Performs the access specified by the request.
     * @param pkt The request to perform.
     * @return The result of the access.
     */
    bool timingAccess(PacketPtr pkt);

    /**
     * Performs the access specified by the request.
     * @param pkt The request to perform.
     * @return The result of the access.
     */
    Tick atomicAccess(PacketPtr pkt);

    /**
     * Performs the access specified by the request.
     * @param pkt The request to perform.
     * @return The result of the access.
     */
    void functionalAccess(PacketPtr pkt, CachePort *otherSidePort);

    /**
     * Handles a response (cache line fill/write ack) from the bus.
     * @param pkt The request being responded to.
     */
    void handleResponse(PacketPtr pkt);

    /**
     * Snoops bus transactions to maintain coherence.
     * @param pkt The current bus transaction.
     */
    void snoopTiming(PacketPtr pkt);

    /**
     * Snoop for the provided request in the cache and return the estimated
     * time of completion.
     * @param pkt The memory request to snoop
     * @return The estimated completion time.
     */
    Tick snoopAtomic(PacketPtr pkt);

    /**
     * Squash all requests associated with specified thread.
     * intended for use by I-cache.
     * @param threadNum The thread to squash.
     */
    void squash(int threadNum);

    /**
     * Allocate a new MSHR or write buffer to handle a miss.
     * @param pkt The access that missed.
     * @param time The time to continue processing the miss.
     * @param isFill Whether to fetch & allocate a block
     *               or just forward the request.
     */
    MSHR *allocateBuffer(PacketPtr pkt, Tick time, bool isFill,
                         bool requestBus);

    /**
     * Selects a outstanding request to service.
     * @return The request to service, NULL if none found.
     */
    MSHR *getNextMSHR();
    PacketPtr getPacket();

    /**
     * Marks a request as in service (sent on the bus). This can have side
     * effect since storage for no response commands is deallocated once they
     * are successfully sent.
     * @param pkt The request that was sent on the bus.
     */
    void markInService(MSHR *mshr);

    /**
     * Collect statistics and free resources of a satisfied request.
     * @param pkt The request that has been satisfied.
     * @param time The time when the request is satisfied.
     */
    void handleResponse(PacketPtr pkt, Tick time);

    /**
     * Perform the given writeback request.
     * @param pkt The writeback request.
     */
    void doWriteback(PacketPtr pkt);

    /**
     * Return whether there are any outstanding misses.
     */
    bool outstandingMisses() const
    {
        return mshrQueue.allocated != 0;
    }

    CacheBlk *findBlock(Addr addr) {
        return tags->findBlock(addr);
    }

    bool inCache(Addr addr) {
        return (tags->findBlock(addr) != 0);
    }

    bool inMissQueue(Addr addr) {
        return (mshrQueue.findMatch(addr) != 0);
    }
};

#endif // __CACHE_HH__