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// Todo: add in statistics, only get the MachInst and let decode actually
// decode, think about SMT fetch,
// fix up branch prediction stuff into one thing,
// Figure out where to advance time buffer. Add a way to get a
// stage's current status.
#ifndef __SIMPLE_FETCH_HH__
#define __SIMPLE_FETCH_HH__
//Will want to include: time buffer, structs, MemInterface, Event,
//whatever class bzero uses, MemReqPtr
#include "base/timebuf.hh"
#include "sim/eventq.hh"
#include "cpu/pc_event.hh"
#include "cpu/beta_cpu/comm.hh"
#include "mem/mem_interface.hh"
using namespace std;
/**
* SimpleFetch class to fetch a single instruction each cycle. SimpleFetch
* will stall if there's an Icache miss, but otherwise assumes a one cycle
* Icache hit. This will be replaced with a more fleshed out class in the
* future.
*/
template <class Impl>
class SimpleFetch
{
public:
/** Typedefs from Impl. */
typedef typename Impl::ISA ISA;
typedef typename Impl::DynInst DynInst;
typedef typename Impl::FullCPU FullCPU;
typedef typename Impl::Params Params;
typedef typename Impl::FetchStruct FetchStruct;
typedef typename Impl::TimeStruct TimeStruct;
/** Typedefs from ISA. */
typedef typename ISA::MachInst MachInst;
public:
enum Status {
Running,
Idle,
Squashing,
Blocked,
IcacheMissStall,
IcacheMissComplete
};
// May eventually need statuses on a per thread basis.
Status _status;
bool stalled;
public:
/** SimpleFetch constructor. */
SimpleFetch(Params ¶ms);
void setCPU(FullCPU *cpu_ptr);
void setTimeBuffer(TimeBuffer<TimeStruct> *time_buffer);
void setFetchQueue(TimeBuffer<FetchStruct> *fq_ptr);
void tick();
void fetch();
void processCacheCompletion();
// private:
// Figure out PC vs next PC and how it should be updated
void squash(Addr newPC);
public:
class CacheCompletionEvent : public Event
{
private:
SimpleFetch *fetch;
public:
CacheCompletionEvent(SimpleFetch *_fetch);
virtual void process();
virtual const char *description();
};
CacheCompletionEvent cacheCompletionEvent;
private:
/** Pointer to the FullCPU. */
FullCPU *cpu;
/** Time buffer interface. */
TimeBuffer<TimeStruct> *timeBuffer;
/** Wire to get decode's information from backwards time buffer. */
typename TimeBuffer<TimeStruct>::wire fromDecode;
/** Wire to get rename's information from backwards time buffer. */
typename TimeBuffer<TimeStruct>::wire fromRename;
/** Wire to get iew's information from backwards time buffer. */
typename TimeBuffer<TimeStruct>::wire fromIEW;
/** Wire to get commit's information from backwards time buffer. */
typename TimeBuffer<TimeStruct>::wire fromCommit;
// Will probably have this sit in the FullCPU and just pass a pointr in.
// Simplifies the constructors of all stages.
/** Internal fetch instruction queue. */
TimeBuffer<FetchStruct> *fetchQueue;
//Might be annoying how this name is different than the queue.
/** Wire used to write any information heading to decode. */
typename TimeBuffer<FetchStruct>::wire toDecode;
/** Icache interface. */
MemInterface *icacheInterface;
/** Memory request used to access cache. */
MemReqPtr memReq;
/** Decode to fetch delay, in ticks. */
unsigned decodeToFetchDelay;
/** Rename to fetch delay, in ticks. */
unsigned renameToFetchDelay;
/** IEW to fetch delay, in ticks. */
unsigned iewToFetchDelay;
/** Commit to fetch delay, in ticks. */
unsigned commitToFetchDelay;
/** The width of fetch in instructions. */
unsigned fetchWidth;
/** Cache block size. */
int blkSize;
/** Mask to get a cache block's address. */
Addr cacheBlockMask;
/** The instruction being fetched. */
MachInst inst;
/** Size of instructions. */
int instSize;
/** Icache stall statistics. */
// Stats::Scalar<> icacheStallCycles;
// Counter lastIcacheStall;
};
#endif //__SIMPLE_FETCH_HH__
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