fa_lru.hh

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#ifndef __MEM_CACHE_TAGS_FA_LRU_HH__
#define __MEM_CACHE_TAGS_FA_LRU_HH__

#include <cstdint>
#include <functional>
#include <string>
#include <unordered_map>
#include <vector>

#include "base/bitfield.hh"
#include "base/intmath.hh"
#include "base/logging.hh"
#include "base/statistics.hh"
#include "base/types.hh"
#include "mem/cache/cache_blk.hh"
#include "mem/cache/tags/base.hh"
#include "mem/packet.hh"
#include "params/FALRU.hh"

// Uncomment to enable sanity checks for the FALRU cache and the
// TrackedCaches class
//#define FALRU_DEBUG

class BaseCache;
class ReplaceableEntry;

// A bitmask of the caches we are keeping track of. Currently the
// lowest bit is the smallest cache we are tracking, as it is
// specified by the corresponding parameter. The rest of the bits are
// for exponentially growing cache sizes.
typedef uint32_t CachesMask;

class FALRUBlk : public CacheBlk
{
  public:
    FALRUBlk() : CacheBlk(), prev(nullptr), next(nullptr), inCachesMask(0) {}

    FALRUBlk *prev;
    FALRUBlk *next;

    CachesMask inCachesMask;

    std::string print() const override;
};

class FALRU : public BaseTags
{
  public:
    typedef FALRUBlk BlkType;

  protected:
    FALRUBlk *blks;

    FALRUBlk *head;
    FALRUBlk *tail;

    struct PairHash
    {
        template <class T1, class T2>
        std::size_t operator()(const std::pair<T1, T2> &p) const
        {
            return std::hash<T1>()(p.first) ^ std::hash<T2>()(p.second);
        }
    };
    typedef std::pair<Addr, bool> TagHashKey;
    typedef std::unordered_map<TagHashKey, FALRUBlk *, PairHash> TagHash;

    TagHash tagHash;

    void moveToHead(FALRUBlk *blk);

    void moveToTail(FALRUBlk *blk);

  public:
    typedef FALRUParams Params;

    FALRU(const Params *p);
    ~FALRU();

    void tagsInit() override;

    void regStats() override;

    void invalidate(CacheBlk *blk) override;

    CacheBlk* accessBlock(Addr addr, bool is_secure, Cycles &lat,
                          CachesMask *in_cache_mask);

    CacheBlk* accessBlock(Addr addr, bool is_secure, Cycles &lat) override;

    CacheBlk* findBlock(Addr addr, bool is_secure) const override;

    ReplaceableEntry* findBlockBySetAndWay(int set, int way) const override;

    CacheBlk* findVictim(Addr addr, const bool is_secure,
                         const std::size_t size,
                         std::vector<CacheBlk*>& evict_blks) override;

    void insertBlock(const PacketPtr pkt, CacheBlk *blk) override;

    Addr extractTag(Addr addr) const override
    {
        return blkAlign(addr);
    }

    Addr regenerateBlkAddr(const CacheBlk* blk) const override
    {
        return blk->tag;
    }

    void forEachBlk(std::function<void(CacheBlk &)> visitor) override {
        for (int i = 0; i < numBlocks; i++) {
            visitor(blks[i]);
        }
    }

    bool anyBlk(std::function<bool(CacheBlk &)> visitor) override {
        for (int i = 0; i < numBlocks; i++) {
            if (visitor(blks[i])) {
                return true;
            }
        }
        return false;
    }

  private:
    class CacheTracking
    {
      public:
        CacheTracking(unsigned min_size, unsigned max_size,
                      unsigned block_size)
            : blkSize(block_size),
              minTrackedSize(min_size),
              numTrackedCaches(max_size > min_size ?
                               floorLog2(max_size) - floorLog2(min_size) : 0),
              inAllCachesMask(mask(numTrackedCaches)),
              boundaries(numTrackedCaches)
        {
            fatal_if(numTrackedCaches > sizeof(CachesMask) * 8,
                     "Not enough bits (%s) in type CachesMask type to keep "
                     "track of %d caches\n", sizeof(CachesMask),
                     numTrackedCaches);
        }

        void init(FALRUBlk *head, FALRUBlk *tail);

        void moveBlockToHead(FALRUBlk *blk);

        void moveBlockToTail(FALRUBlk *blk);

        void recordAccess(FALRUBlk *blk);

        void check(const FALRUBlk *head, const FALRUBlk *tail) const;

        void regStats(std::string name);

      private:
        const unsigned blkSize;
        const unsigned minTrackedSize;
        const int numTrackedCaches;
        const CachesMask inAllCachesMask;
        std::vector<FALRUBlk*> boundaries;

      protected:
        Stats::Vector hits;
        Stats::Vector misses;
        Stats::Scalar accesses;

    };
    CacheTracking cacheTracking;
};

#endif // __MEM_CACHE_TAGS_FA_LRU_HH__