gem5/src/mem/ruby/structures/CacheMemory.hh

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 * Copyright (c) 1999-2012 Mark D. Hill and David A. Wood
 * Copyright (c) 2013 Advanced Micro Devices, Inc.
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#ifndef __MEM_RUBY_STRUCTURES_CACHEMEMORY_HH__
#define __MEM_RUBY_STRUCTURES_CACHEMEMORY_HH__

#include <string>
#include <unordered_map>
#include <vector>

#include "base/statistics.hh"
#include "mem/cache/replacement_policies/base.hh"
#include "mem/cache/replacement_policies/replaceable_entry.hh"
#include "mem/ruby/common/DataBlock.hh"
#include "mem/ruby/protocol/CacheRequestType.hh"
#include "mem/ruby/protocol/CacheResourceType.hh"
#include "mem/ruby/protocol/RubyRequest.hh"
#include "mem/ruby/slicc_interface/AbstractCacheEntry.hh"
#include "mem/ruby/slicc_interface/RubySlicc_ComponentMapping.hh"
#include "mem/ruby/structures/BankedArray.hh"
#include "mem/ruby/system/CacheRecorder.hh"
#include "params/RubyCache.hh"
#include "sim/sim_object.hh"

namespace gem5
{

class CacheMemory : public SimObject
{
  public:
    typedef RubyCacheParams Params;
    typedef std::shared_ptr<replacement_policy::ReplacementData> ReplData;
    CacheMemory(const Params &p);
    ~CacheMemory();

    void init();

    // Public Methods
    // perform a cache access and see if we hit or not.  Return true on a hit.
    bool tryCacheAccess(Addr address, RubyRequestType type,
                        DataBlock*& data_ptr);

    // similar to above, but doesn't require full access check
    bool testCacheAccess(Addr address, RubyRequestType type,
                         DataBlock*& data_ptr);

    // tests to see if an address is present in the cache
    bool isTagPresent(Addr address) const;

    // Returns true if there is:
    //   a) a tag match on this address or there is
    //   b) an unused line in the same cache "way"
    bool cacheAvail(Addr address) const;

    // Returns a NULL entry that acts as a placeholder for invalid lines
    AbstractCacheEntry*
    getNullEntry() const
    {
        return nullptr;
    }

    // find an unused entry and sets the tag appropriate for the address
    AbstractCacheEntry* allocate(Addr address, AbstractCacheEntry* new_entry);
    void allocateVoid(Addr address, AbstractCacheEntry* new_entry)
    {
        allocate(address, new_entry);
    }

    // Explicitly free up this address
    void deallocate(Addr address);

    // Returns with the physical address of the conflicting cache line
    Addr cacheProbe(Addr address) const;

    // looks an address up in the cache
    AbstractCacheEntry* lookup(Addr address);
    const AbstractCacheEntry* lookup(Addr address) const;

    Cycles getTagLatency() const { return tagArray.getLatency(); }
    Cycles getDataLatency() const { return dataArray.getLatency(); }

    bool isBlockInvalid(int64_t cache_set, int64_t loc);
    bool isBlockNotBusy(int64_t cache_set, int64_t loc);

    // Hook for checkpointing the contents of the cache
    void recordCacheContents(int cntrl, CacheRecorder* tr) const;

    // Set this address to most recently used
    void setMRU(Addr address);
    void setMRU(Addr addr, int occupancy);
    void setMRU(AbstractCacheEntry* entry);
    int getReplacementWeight(int64_t set, int64_t loc);

    // Functions for locking and unlocking cache lines corresponding to the
    // provided address.  These are required for supporting atomic memory
    // accesses.  These are to be used when only the address of the cache entry
    // is available.  In case the entry itself is available. use the functions
    // provided by the AbstractCacheEntry class.
    void setLocked (Addr addr, int context);
    void clearLocked (Addr addr);
    void clearLockedAll (int context);
    bool isLocked (Addr addr, int context);

    // Print cache contents
    void print(std::ostream& out) const;
    void printData(std::ostream& out) const;

    bool checkResourceAvailable(CacheResourceType res, Addr addr);
    void recordRequestType(CacheRequestType requestType, Addr addr);

    // hardware transactional memory
    void htmAbortTransaction();
    void htmCommitTransaction();

  public:
    int getCacheSize() const { return m_cache_size; }
    int getCacheAssoc() const { return m_cache_assoc; }
    int getNumBlocks() const { return m_cache_num_sets * m_cache_assoc; }
    Addr getAddressAtIdx(int idx) const;

  private:
    // convert a Address to its location in the cache
    int64_t addressToCacheSet(Addr address) const;

    // Given a cache tag: returns the index of the tag in a set.
    // returns -1 if the tag is not found.
    int findTagInSet(int64_t line, Addr tag) const;
    int findTagInSetIgnorePermissions(int64_t cacheSet, Addr tag) const;

    // Private copy constructor and assignment operator
    CacheMemory(const CacheMemory& obj);
    CacheMemory& operator=(const CacheMemory& obj);

  private:
    // Data Members (m_prefix)
    bool m_is_instruction_only_cache;

    // The first index is the # of cache lines.
    // The second index is the the amount associativity.
    std::unordered_map<Addr, int> m_tag_index;
    std::vector<std::vector<AbstractCacheEntry*> > m_cache;

    /** We use the replacement policies from the Classic memory system. */
    replacement_policy::Base *m_replacementPolicy_ptr;

    BankedArray dataArray;
    BankedArray tagArray;

    int m_cache_size;
    int m_cache_num_sets;
    int m_cache_num_set_bits;
    int m_cache_assoc;
    int m_start_index_bit;
    bool m_resource_stalls;
    int m_block_size;

    /**
     * We store all the ReplacementData in a 2-dimensional array. By doing
     * this, we can use all replacement policies from Classic system. Ruby
     * cache will deallocate cache entry every time we evict the cache block
     * so we cannot store the ReplacementData inside the cache entry.
     * Instantiate ReplacementData for multiple times will break replacement
     * policy like TreePLRU.
     */
    std::vector<std::vector<ReplData> > replacement_data;

    /**
     * Set to true when using WeightedLRU replacement policy, otherwise, set to
     * false.
     */
    bool m_use_occupancy;

    private:
      struct CacheMemoryStats : public statistics::Group
      {
          CacheMemoryStats(statistics::Group *parent);

          statistics::Scalar numDataArrayReads;
          statistics::Scalar numDataArrayWrites;
          statistics::Scalar numTagArrayReads;
          statistics::Scalar numTagArrayWrites;

          statistics::Scalar numTagArrayStalls;
          statistics::Scalar numDataArrayStalls;

          // hardware transactional memory
          statistics::Histogram htmTransCommitReadSet;
          statistics::Histogram htmTransCommitWriteSet;
          statistics::Histogram htmTransAbortReadSet;
          statistics::Histogram htmTransAbortWriteSet;

          statistics::Scalar m_demand_hits;
          statistics::Scalar m_demand_misses;
          statistics::Formula m_demand_accesses;

          statistics::Scalar m_prefetch_hits;
          statistics::Scalar m_prefetch_misses;
          statistics::Formula m_prefetch_accesses;

          statistics::Vector m_accessModeType;
      } cacheMemoryStats;

    public:
      // These function increment the number of demand hits/misses by one
      // each time they are called
      void profileDemandHit();
      void profileDemandMiss();
      void profilePrefetchHit();
      void profilePrefetchMiss();
};

std::ostream& operator<<(std::ostream& out, const CacheMemory& obj);

} // namespace gem5

#endif // __MEM_RUBY_STRUCTURES_CACHEMEMORY_HH__