mshr.hh

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/*
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 * 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
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 * Copyright (c) 2002-2005 The Regents of The University of Michigan
 * All rights reserved.
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 * met: redistributions of source code must retain the above copyright
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 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 *
 * Authors: Erik Hallnor
 *          Nikos Nikoleris
 */

#ifndef __MEM_CACHE_MSHR_HH__
#define __MEM_CACHE_MSHR_HH__

#include <cassert>
#include <iosfwd>
#include <list>
#include <string>
#include <vector>

#include "base/printable.hh"
#include "base/types.hh"
#include "mem/cache/queue_entry.hh"
#include "mem/packet.hh"
#include "mem/request.hh"
#include "sim/core.hh"

class BaseCache;

class MSHR : public QueueEntry, public Printable
{

    template<typename Entry>
    friend class Queue;
    friend class MSHRQueue;

  private:

    bool downstreamPending;

    bool pendingModified;

    bool postInvalidate;

    bool postDowngrade;

  public:

    bool wasWholeLineWrite;

    bool isForward;

    class Target : public QueueEntry::Target {
      public:

        enum Source {
            FromCPU,
            FromSnoop,
            FromPrefetcher
        };

        const Source source;  

        bool markedPending;

        const bool allocOnFill;   

        Target(PacketPtr _pkt, Tick _readyTime, Counter _order,
               Source _source, bool _markedPending, bool alloc_on_fill)
            : QueueEntry::Target(_pkt, _readyTime, _order), source(_source),
              markedPending(_markedPending), allocOnFill(alloc_on_fill)
        {}
    };

    class TargetList : public std::list<Target> {

      public:
        bool needsWritable;
        bool hasUpgrade;
        bool allocOnFill;
        bool hasFromCache;

        TargetList();

        void updateFlags(PacketPtr pkt, Target::Source source,
                         bool alloc_on_fill);

        void init(Addr blk_addr, Addr blk_size) {
            blkAddr = blk_addr;
            blkSize = blk_size;
            writesBitmap.resize(blk_size);

            resetFlags();
        }

        void resetFlags() {
            canMergeWrites = true;
            std::fill(writesBitmap.begin(), writesBitmap.end(), false);

            needsWritable = false;
            hasUpgrade = false;
            allocOnFill = false;
            hasFromCache = false;
        }

        void populateFlags();

        void updateWriteFlags(PacketPtr pkt);

        bool isReset() const {
            return !needsWritable && !hasUpgrade && !allocOnFill &&
                !hasFromCache && canMergeWrites;
        }

        void add(PacketPtr pkt, Tick readyTime, Counter order,
                 Target::Source source, bool markPending, bool alloc_on_fill);

        void replaceUpgrades();

        void clearDownstreamPending();
        void clearDownstreamPending(iterator begin, iterator end);
        bool trySatisfyFunctional(PacketPtr pkt);
        void print(std::ostream &os, int verbosity,
                   const std::string &prefix) const;

        bool isWholeLineWrite() const
        {
            return std::all_of(writesBitmap.begin(), writesBitmap.end(),
                               [](bool i) { return i; });
        }

      private:
        Addr blkAddr;

        Addr blkSize;

        bool canMergeWrites;

        // NOTE: std::vector<bool> might not meet satisfy the
        // ForwardIterator requirement and therefore cannot be used
        // for writesBitmap.
        std::vector<char> writesBitmap;
    };

    typedef std::list<MSHR *> List;
    typedef List::iterator Iterator;

    bool needsWritable() const { return targets.needsWritable; }

    bool isCleaning() const {
        PacketPtr pkt = targets.front().pkt;
        return pkt->isClean();
    }

    bool isPendingModified() const {
        assert(inService); return pendingModified;
    }

    bool hasPostInvalidate() const {
        assert(inService); return postInvalidate;
    }

    bool hasPostDowngrade() const {
        assert(inService); return postDowngrade;
    }

    bool sendPacket(BaseCache &cache) override;

    bool allocOnFill() const {
        return targets.allocOnFill;
    }

    bool hasFromCache() const {
        return targets.hasFromCache;
    }

  private:
    void promoteIf(const std::function<bool (Target &)>& pred);

    Iterator readyIter;

    Iterator allocIter;

    TargetList targets;

    TargetList deferredTargets;

  public:
    bool isWholeLineWrite() const {
        return targets.isWholeLineWrite();
    }

    void allocate(Addr blk_addr, unsigned blk_size, PacketPtr pkt,
                  Tick when_ready, Counter _order, bool alloc_on_fill);

    void markInService(bool pending_modified_resp);

    void clearDownstreamPending();

    void deallocate();

    void allocateTarget(PacketPtr target, Tick when, Counter order,
                        bool alloc_on_fill);
    bool handleSnoop(PacketPtr target, Counter order);

    MSHR();

    int getNumTargets() const
    { return targets.size() + deferredTargets.size(); }

    TargetList extractServiceableTargets(PacketPtr pkt);

    bool hasTargets() const { return !targets.empty(); }

    QueueEntry::Target *getTarget() override
    {
        assert(hasTargets());
        return &targets.front();
    }

    void popTarget()
    {
        targets.pop_front();
    }

    bool promoteDeferredTargets();

    void promoteReadable();

    void promoteWritable();

    bool trySatisfyFunctional(PacketPtr pkt);

    void delay(Tick delay_ticks)
    {
        assert(readyTime <= curTick());
        readyTime = curTick() + delay_ticks;
    }

    void print(std::ostream &os,
               int verbosity = 0,
               const std::string &prefix = "") const override;
    std::string print() const;

    bool matchBlockAddr(const Addr addr, const bool is_secure) const override;
    bool matchBlockAddr(const PacketPtr pkt) const override;
    bool conflictAddr(const QueueEntry* entry) const override;
};

#endif // __MEM_CACHE_MSHR_HH__