fdp.hh

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 * Copyright (c) 2025 Arm Limited
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#ifndef __MEM_CACHE_PREFETCH_FDP_HH__
#define __MEM_CACHE_PREFETCH_FDP_HH__
 
#include <list>
 
#include "arch/generic/mmu.hh"
#include "cpu/base.hh"
#include "cpu/o3/ftq.hh"
#include "mem/cache/base.hh"
#include "mem/cache/prefetch/base.hh"
 
namespace gem5
{
 
struct FetchDirectedPrefetcherParams;
 
namespace prefetch
{
 
class FetchDirectedPrefetcher : public Base
{
 
  public:
    FetchDirectedPrefetcher(const FetchDirectedPrefetcherParams &p);
    ~FetchDirectedPrefetcher() = default;

    void regProbeListeners() override;
    void
    setCache(BaseCache *_cache)
    {
        cache = _cache;
    }

    PacketPtr getPacket() override;
 
    Tick
    nextPrefetchReadyTime() const override
    {
        return pfq.empty() ? MaxTick : pfq.front().readyTime;
    }

    void notify(const CacheAccessProbeArg &acc,
                const PrefetchInfo &pfi) override {};
 
  private:
    std::vector<ProbeListenerPtr<>> listeners;

    BaseCPU *cpu;

    BaseCache *cache;

    const bool markReqAsPrefetch;

    const bool squashPrefetches;

    const unsigned int latency;

    const unsigned int pfqSize;

    const unsigned int tqSize;

    const bool cacheSnoop;

    struct PrefetchRequest : public BaseMMU::Translation
    {
        PrefetchRequest(FetchDirectedPrefetcher &_owner, uint64_t _addr,
                        ThreadID tid, o3::FTSeqNum ftn);

        FetchDirectedPrefetcher &owner;

        const uint64_t addr;

        const o3::FTSeqNum ftn;

        RequestPtr req;
        PacketPtr pkt;

        Tick readyTime;

        bool canceled;
 
        bool
        operator==(const int &a) const
        {
            return this->addr == a;
        }

        void createPkt();
 
        void finish(const Fault &fault, const RequestPtr &req,
                    ThreadContext *tc, BaseMMU::Mode mode) override;

        void startTranslation();
 
        void
        markDelayed() override
        {}
 
        void
        markCanceled()
        {
            canceled = true;
        }
 
        bool
        isCanceled() const
        {
            return canceled;
        }
    };

    std::list<PrefetchRequest> pfq;
    std::list<PrefetchRequest> translationq;

    void notifyFTQInsert(const o3::FetchTargetPtr &ft);

    void notifyFTQRemove(const o3::FetchTargetPtr &ft);

    void translationComplete(PrefetchRequest *pf_req, const bool failed);
 
  protected:
    struct Stats : public statistics::Group
    {
        Stats(statistics::Group *parent, int pfq_size, int tq_size);
        statistics::Scalar fdipInsertions;
 
        statistics::Scalar pfIdentified;
        statistics::Scalar pfSquashed;
        statistics::Scalar pfInPFQ;
        statistics::Scalar pfInTQ;
        statistics::Scalar pfInCache;
        statistics::Scalar pfInCachePrefetched;
        statistics::Scalar pfPacketsCreated;
        statistics::Scalar pfCandidatesAdded;
 
        statistics::Scalar translationFail;
        statistics::Scalar translationSuccess;
 
        statistics::Distribution pfqSizeDistAtNotify;
        statistics::Distribution tqSizeDistAtNotify;
        statistics::Scalar pfqInserts;
        statistics::Scalar pfqPops;
        statistics::Scalar pfqDrops;
        statistics::Scalar tqInserts;
        statistics::Scalar tqPops;
        statistics::Scalar tqDrops;
    } stats;
};
 
} // namespace prefetch
} // namespace gem5
 
#endif // __MEM_CACHE_PREFETCH_FDP_HH__