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#ifndef __MEM_DEP_UNIT_HH__
#define __MEM_DEP_UNIT_HH__
#include <set>
#include <map>
#include "cpu/inst_seq.hh"
#include "base/statistics.hh"
/**
* Memory dependency unit class. This holds the memory dependence predictor.
* As memory operations are issued to the IQ, they are also issued to this
* unit, which then looks up the prediction as to what they are dependent
* upon. This unit must be checked prior to a memory operation being able
* to issue. Although this is templated, it's somewhat hard to make a generic
* memory dependence unit. This one is mostly for store sets; it will be
* quite limited in what other memory dependence predictions it can also
* utilize. Thus this class should be most likely be rewritten for other
* dependence prediction schemes.
*/
template <class MemDepPred, class Impl>
class MemDepUnit {
public:
typedef typename Impl::Params Params;
typedef typename Impl::DynInstPtr DynInstPtr;
public:
MemDepUnit(Params ¶ms);
void regStats();
void insert(DynInstPtr &inst);
void insertNonSpec(DynInstPtr &inst);
void regsReady(DynInstPtr &inst);
void nonSpecInstReady(DynInstPtr &inst);
void issue(DynInstPtr &inst);
void wakeDependents(DynInstPtr &inst);
void squash(const InstSeqNum &squashed_num);
void violation(DynInstPtr &store_inst, DynInstPtr &violating_load);
// Will want to make this operation relatively fast. Right now it
// kind of sucks.
DynInstPtr &top();
void pop();
inline bool empty()
{ return readyInsts.empty(); }
private:
typedef typename std::set<InstSeqNum>::iterator sn_it_t;
typedef typename std::map<InstSeqNum, DynInstPtr>::iterator dyn_it_t;
// Forward declarations so that the following two typedefs work.
class Dependency;
class ltDependency;
typedef typename std::set<Dependency, ltDependency>::iterator dep_it_t;
typedef typename std::map<InstSeqNum, vector<dep_it_t> >::iterator
sd_it_t;
struct Dependency {
Dependency(const InstSeqNum &_seqNum)
: seqNum(_seqNum), regsReady(0), memDepReady(0)
{ }
Dependency(const InstSeqNum &_seqNum, bool _regsReady,
bool _memDepReady)
: seqNum(_seqNum), regsReady(_regsReady),
memDepReady(_memDepReady)
{ }
InstSeqNum seqNum;
mutable bool regsReady;
mutable bool memDepReady;
mutable sd_it_t storeDep;
};
struct ltDependency {
bool operator() (const Dependency &lhs, const Dependency &rhs)
{
return lhs.seqNum < rhs.seqNum;
}
};
private:
inline void moveToReady(dep_it_t &woken_inst);
private:
/** List of instructions that have passed through rename, yet are still
* waiting on either a memory dependence to resolve or source registers to
* become available before they can issue.
*/
std::set<Dependency, ltDependency> waitingInsts;
/** List of instructions that have all their predicted memory dependences
* resolved and their source registers ready.
*/
std::set<InstSeqNum> readyInsts;
// Change this to hold a vector of iterators, which will point to the
// entry of the waiting instructions.
/** List of stores' sequence numbers, each of which has a vector of
* iterators. The iterators point to the appropriate node within
* waitingInsts that has the depenendent instruction.
*/
std::map<InstSeqNum, vector<dep_it_t> > storeDependents;
// For now will implement this as a map...hash table might not be too
// bad, or could move to something that mimics the current dependency
// graph.
std::map<InstSeqNum, DynInstPtr> memInsts;
// Iterator pointer to the top instruction which has is ready.
// Is set by the top() call.
dyn_it_t topInst;
/** The memory dependence predictor. It is accessed upon new
* instructions being added to the IQ, and responds by telling
* this unit what instruction the newly added instruction is dependent
* upon.
*/
MemDepPred depPred;
Stats::Scalar<> insertedLoads;
Stats::Scalar<> insertedStores;
Stats::Scalar<> conflictingLoads;
Stats::Scalar<> conflictingStores;
};
#endif
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