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43 #ifndef __CPU_O3_INST_QUEUE_HH__
44 #define __CPU_O3_INST_QUEUE_HH__
51 #include "base/statistics.hh"
52 #include "base/types.hh"
53 #include "cpu/o3/dep_graph.hh"
54 #include "cpu/inst_seq.hh"
55 #include "cpu/op_class.hh"
56 #include "cpu/timebuf.hh"
57 #include "sim/eventq.hh"
59 struct DerivO3CPUParams;
64 * A standard instruction queue class. It holds ready instructions, in
65 * order, in seperate priority queues to facilitate the scheduling of
66 * instructions. The IQ uses a separate linked list to track dependencies.
67 * Similar to the rename map and the free list, it expects that
68 * floating point registers have their indices start after the integer
69 * registers (ie with 96 int and 96 fp registers, regs 0-95 are integer
70 * and 96-191 are fp). This remains true even for both logical and
71 * physical register indices. The IQ depends on the memory dependence unit to
72 * track when memory operations are ready in terms of ordering; register
73 * dependencies are tracked normally. Right now the IQ also handles the
74 * execution timing; this is mainly to allow back-to-back scheduling without
75 * requiring IEW to be able to peek into the IQ. At the end of the execution
76 * latency, the instruction is put into the queue to execute, where it will
77 * have the execute() function called on it.
78 * @todo: Make IQ able to handle multiple FU pools.
81 class InstructionQueue
84 //Typedefs from the Impl.
85 typedef typename Impl::O3CPU O3CPU;
86 typedef typename Impl::DynInstPtr DynInstPtr;
88 typedef typename Impl::CPUPol::IEW IEW;
89 typedef typename Impl::CPUPol::MemDepUnit MemDepUnit;
90 typedef typename Impl::CPUPol::IssueStruct IssueStruct;
91 typedef typename Impl::CPUPol::TimeStruct TimeStruct;
93 // Typedef of iterator through the list of instructions.
94 typedef typename std::list<DynInstPtr>::iterator ListIt;
96 /** FU completion event class. */
97 class FUCompletion : public Event {
99 /** Executing instruction. */
102 /** Index of the FU used for executing. */
105 /** Pointer back to the instruction queue. */
106 InstructionQueue<Impl> *iqPtr;
108 /** Should the FU be added to the list to be freed upon
109 * completing this event.
114 /** Construct a FU completion event. */
115 FUCompletion(DynInstPtr &_inst, int fu_idx,
116 InstructionQueue<Impl> *iq_ptr);
118 virtual void process();
119 virtual const char *description() const;
120 void setFreeFU() { freeFU = true; }
123 /** Constructs an IQ. */
124 InstructionQueue(O3CPU *cpu_ptr, IEW *iew_ptr, DerivO3CPUParams *params);
126 /** Destructs the IQ. */
129 /** Returns the name of the IQ. */
130 std::string name() const;
132 /** Registers statistics. */
135 /** Resets all instruction queue state. */
138 /** Sets active threads list. */
139 void setActiveThreads(std::list<ThreadID> *at_ptr);
141 /** Sets the timer buffer between issue and execute. */
142 void setIssueToExecuteQueue(TimeBuffer<IssueStruct> *i2eQueue);
144 /** Sets the global time buffer. */
145 void setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr);
147 /** Switches out the instruction queue. */
150 /** Takes over execution from another CPU's thread. */
153 /** Returns if the IQ is switched out. */
154 bool isSwitchedOut() { return switchedOut; }
156 /** Number of entries needed for given amount of threads. */
157 int entryAmount(ThreadID num_threads);
159 /** Resets max entries for all threads. */
162 /** Returns total number of free entries. */
163 unsigned numFreeEntries();
165 /** Returns number of free entries for a thread. */
166 unsigned numFreeEntries(ThreadID tid);
168 /** Returns whether or not the IQ is full. */
171 /** Returns whether or not the IQ is full for a specific thread. */
172 bool isFull(ThreadID tid);
174 /** Returns if there are any ready instructions in the IQ. */
175 bool hasReadyInsts();
177 /** Inserts a new instruction into the IQ. */
178 void insert(DynInstPtr &new_inst);
180 /** Inserts a new, non-speculative instruction into the IQ. */
181 void insertNonSpec(DynInstPtr &new_inst);
183 /** Inserts a memory or write barrier into the IQ to make sure
184 * loads and stores are ordered properly.
186 void insertBarrier(DynInstPtr &barr_inst);
188 /** Returns the oldest scheduled instruction, and removes it from
189 * the list of instructions waiting to execute.
191 DynInstPtr getInstToExecute();
193 /** Returns a memory instruction that was referred due to a delayed DTB
194 * translation if it is now ready to execute.
196 DynInstPtr getDeferredMemInstToExecute();
199 * Records the instruction as the producer of a register without
200 * adding it to the rest of the IQ.
202 void recordProducer(DynInstPtr &inst)
203 { addToProducers(inst); }
205 /** Process FU completion event. */
206 void processFUCompletion(DynInstPtr &inst, int fu_idx);
209 * Schedules ready instructions, adding the ready ones (oldest first) to
210 * the queue to execute.
212 void scheduleReadyInsts();
214 /** Schedules a single specific non-speculative instruction. */
215 void scheduleNonSpec(const InstSeqNum &inst);
218 * Commits all instructions up to and including the given sequence number,
219 * for a specific thread.
221 void commit(const InstSeqNum &inst, ThreadID tid = 0);
223 /** Wakes all dependents of a completed instruction. */
224 int wakeDependents(DynInstPtr &completed_inst);
226 /** Adds a ready memory instruction to the ready list. */
227 void addReadyMemInst(DynInstPtr &ready_inst);
230 * Reschedules a memory instruction. It will be ready to issue once
231 * replayMemInst() is called.
233 void rescheduleMemInst(DynInstPtr &resched_inst);
235 /** Replays a memory instruction. It must be rescheduled first. */
236 void replayMemInst(DynInstPtr &replay_inst);
238 /** Completes a memory operation. */
239 void completeMemInst(DynInstPtr &completed_inst);
242 * Defers a memory instruction when its DTB translation incurs a hw
245 void deferMemInst(DynInstPtr &deferred_inst);
247 /** Indicates an ordering violation between a store and a load. */
248 void violation(DynInstPtr &store, DynInstPtr &faulting_load);
251 * Squashes instructions for a thread. Squashing information is obtained
252 * from the time buffer.
254 void squash(ThreadID tid);
256 /** Returns the number of used entries for a thread. */
257 unsigned getCount(ThreadID tid) { return count[tid]; };
259 /** Debug function to print all instructions. */
263 /** Does the actual squashing. */
264 void doSquash(ThreadID tid);
266 /////////////////////////
268 /////////////////////////
270 /** Pointer to the CPU. */
273 /** Cache interface. */
274 MemInterface *dcacheInterface;
276 /** Pointer to IEW stage. */
279 /** The memory dependence unit, which tracks/predicts memory dependences
280 * between instructions.
282 MemDepUnit memDepUnit[Impl::MaxThreads];
284 /** The queue to the execute stage. Issued instructions will be written
287 TimeBuffer<IssueStruct> *issueToExecuteQueue;
289 /** The backwards time buffer. */
290 TimeBuffer<TimeStruct> *timeBuffer;
292 /** Wire to read information from timebuffer. */
293 typename TimeBuffer<TimeStruct>::wire fromCommit;
295 /** Function unit pool. */
298 //////////////////////////////////////
299 // Instruction lists, ready queues, and ordering
300 //////////////////////////////////////
302 /** List of all the instructions in the IQ (some of which may be issued). */
303 std::list<DynInstPtr> instList[Impl::MaxThreads];
305 /** List of instructions that are ready to be executed. */
306 std::list<DynInstPtr> instsToExecute;
308 /** List of instructions waiting for their DTB translation to
309 * complete (hw page table walk in progress).
311 std::list<DynInstPtr> deferredMemInsts;
314 * Struct for comparing entries to be added to the priority queue.
315 * This gives reverse ordering to the instructions in terms of
316 * sequence numbers: the instructions with smaller sequence
317 * numbers (and hence are older) will be at the top of the
321 bool operator() (const DynInstPtr &lhs, const DynInstPtr &rhs) const
323 return lhs->seqNum > rhs->seqNum;
327 typedef std::priority_queue<DynInstPtr, std::vector<DynInstPtr>, pqCompare>
330 /** List of ready instructions, per op class. They are separated by op
331 * class to allow for easy mapping to FUs.
333 ReadyInstQueue readyInsts[Num_OpClasses];
335 /** List of non-speculative instructions that will be scheduled
336 * once the IQ gets a signal from commit. While it's redundant to
337 * have the key be a part of the value (the sequence number is stored
338 * inside of DynInst), when these instructions are woken up only
339 * the sequence number will be available. Thus it is most efficient to be
340 * able to search by the sequence number alone.
342 std::map<InstSeqNum, DynInstPtr> nonSpecInsts;
344 typedef typename std::map<InstSeqNum, DynInstPtr>::iterator NonSpecMapIt;
346 /** Entry for the list age ordering by op class. */
347 struct ListOrderEntry {
349 InstSeqNum oldestInst;
352 /** List that contains the age order of the oldest instruction of each
353 * ready queue. Used to select the oldest instruction available
355 * @todo: Might be better to just move these entries around instead
356 * of creating new ones every time the position changes due to an
357 * instruction issuing. Not sure std::list supports this.
359 std::list<ListOrderEntry> listOrder;
361 typedef typename std::list<ListOrderEntry>::iterator ListOrderIt;
363 /** Tracks if each ready queue is on the age order list. */
364 bool queueOnList[Num_OpClasses];
366 /** Iterators of each ready queue. Points to their spot in the age order
369 ListOrderIt readyIt[Num_OpClasses];
371 /** Add an op class to the age order list. */
372 void addToOrderList(OpClass op_class);
375 * Called when the oldest instruction has been removed from a ready queue;
376 * this places that ready queue into the proper spot in the age order list.
378 void moveToYoungerInst(ListOrderIt age_order_it);
380 DependencyGraph<DynInstPtr> dependGraph;
382 //////////////////////////////////////
383 // Various parameters
384 //////////////////////////////////////
386 /** IQ Resource Sharing Policy */
393 /** IQ sharing policy for SMT. */
396 /** Number of Total Threads*/
399 /** Pointer to list of active threads. */
400 std::list<ThreadID> *activeThreads;
402 /** Per Thread IQ count */
403 unsigned count[Impl::MaxThreads];
405 /** Max IQ Entries Per Thread */
406 unsigned maxEntries[Impl::MaxThreads];
408 /** Number of free IQ entries left. */
409 unsigned freeEntries;
411 /** The number of entries in the instruction queue. */
414 /** The total number of instructions that can be issued in one cycle. */
417 /** The number of physical registers in the CPU. */
418 unsigned numPhysRegs;
420 /** The number of physical integer registers in the CPU. */
421 unsigned numPhysIntRegs;
423 /** The number of floating point registers in the CPU. */
424 unsigned numPhysFloatRegs;
426 /** Delay between commit stage and the IQ.
427 * @todo: Make there be a distinction between the delays within IEW.
429 Cycles commitToIEWDelay;
431 /** Is the IQ switched out. */
434 /** The sequence number of the squashed instruction. */
435 InstSeqNum squashedSeqNum[Impl::MaxThreads];
437 /** A cache of the recently woken registers. It is 1 if the register
438 * has been woken up recently, and 0 if the register has been added
439 * to the dependency graph and has not yet received its value. It
440 * is basically a secondary scoreboard, and should pretty much mirror
441 * the scoreboard that exists in the rename map.
443 std::vector<bool> regScoreboard;
445 /** Adds an instruction to the dependency graph, as a consumer. */
446 bool addToDependents(DynInstPtr &new_inst);
448 /** Adds an instruction to the dependency graph, as a producer. */
449 void addToProducers(DynInstPtr &new_inst);
451 /** Moves an instruction to the ready queue if it is ready. */
452 void addIfReady(DynInstPtr &inst);
454 /** Debugging function to count how many entries are in the IQ. It does
455 * a linear walk through the instructions, so do not call this function
456 * during normal execution.
460 /** Debugging function to dump all the list sizes, as well as print
461 * out the list of nonspeculative instructions. Should not be used
462 * in any other capacity, but it has no harmful sideaffects.
466 /** Debugging function to dump out all instructions that are in the
471 /** Stat for number of instructions added. */
472 Stats::Scalar iqInstsAdded;
473 /** Stat for number of non-speculative instructions added. */
474 Stats::Scalar iqNonSpecInstsAdded;
476 Stats::Scalar iqInstsIssued;
477 /** Stat for number of integer instructions issued. */
478 Stats::Scalar iqIntInstsIssued;
479 /** Stat for number of floating point instructions issued. */
480 Stats::Scalar iqFloatInstsIssued;
481 /** Stat for number of branch instructions issued. */
482 Stats::Scalar iqBranchInstsIssued;
483 /** Stat for number of memory instructions issued. */
484 Stats::Scalar iqMemInstsIssued;
485 /** Stat for number of miscellaneous instructions issued. */
486 Stats::Scalar iqMiscInstsIssued;
487 /** Stat for number of squashed instructions that were ready to issue. */
488 Stats::Scalar iqSquashedInstsIssued;
489 /** Stat for number of squashed instructions examined when squashing. */
490 Stats::Scalar iqSquashedInstsExamined;
491 /** Stat for number of squashed instruction operands examined when
494 Stats::Scalar iqSquashedOperandsExamined;
495 /** Stat for number of non-speculative instructions removed due to a squash.
497 Stats::Scalar iqSquashedNonSpecRemoved;
498 // Also include number of instructions rescheduled and replayed.
500 /** Distribution of number of instructions in the queue.
501 * @todo: Need to create struct to track the entry time for each
503 // Stats::VectorDistribution queueResDist;
504 /** Distribution of the number of instructions issued. */
505 Stats::Distribution numIssuedDist;
506 /** Distribution of the cycles it takes to issue an instruction.
507 * @todo: Need to create struct to track the ready time for each
509 // Stats::VectorDistribution issueDelayDist;
511 /** Number of times an instruction could not be issued because a
514 Stats::Vector statFuBusy;
515 // Stats::Vector dist_unissued;
516 /** Stat for total number issued for each instruction type. */
517 Stats::Vector2d statIssuedInstType;
519 /** Number of instructions issued per cycle. */
520 Stats::Formula issueRate;
522 /** Number of times the FU was busy. */
523 Stats::Vector fuBusy;
524 /** Number of times the FU was busy per instruction issued. */
525 Stats::Formula fuBusyRate;
527 Stats::Scalar intInstQueueReads;
528 Stats::Scalar intInstQueueWrites;
529 Stats::Scalar intInstQueueWakeupAccesses;
530 Stats::Scalar fpInstQueueReads;
531 Stats::Scalar fpInstQueueWrites;
532 Stats::Scalar fpInstQueueWakeupQccesses;
534 Stats::Scalar intAluAccesses;
535 Stats::Scalar fpAluAccesses;
538 #endif //__CPU_O3_INST_QUEUE_HH__