inst_queue_impl.hh revision 7720:65d338a8dba4
1/*
2 * Copyright (c) 2004-2006 The Regents of The University of Michigan
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * Authors: Kevin Lim
29 *          Korey Sewell
30 */
31
32#include <limits>
33#include <vector>
34
35#include "cpu/o3/fu_pool.hh"
36#include "cpu/o3/inst_queue.hh"
37#include "enums/OpClass.hh"
38#include "params/DerivO3CPU.hh"
39#include "sim/core.hh"
40
41using namespace std;
42
43template <class Impl>
44InstructionQueue<Impl>::FUCompletion::FUCompletion(DynInstPtr &_inst,
45    int fu_idx, InstructionQueue<Impl> *iq_ptr)
46    : Event(Stat_Event_Pri), inst(_inst), fuIdx(fu_idx), iqPtr(iq_ptr),
47      freeFU(false)
48{
49    this->setFlags(Event::AutoDelete);
50}
51
52template <class Impl>
53void
54InstructionQueue<Impl>::FUCompletion::process()
55{
56    iqPtr->processFUCompletion(inst, freeFU ? fuIdx : -1);
57    inst = NULL;
58}
59
60
61template <class Impl>
62const char *
63InstructionQueue<Impl>::FUCompletion::description() const
64{
65    return "Functional unit completion";
66}
67
68template <class Impl>
69InstructionQueue<Impl>::InstructionQueue(O3CPU *cpu_ptr, IEW *iew_ptr,
70                                         DerivO3CPUParams *params)
71    : cpu(cpu_ptr),
72      iewStage(iew_ptr),
73      fuPool(params->fuPool),
74      numEntries(params->numIQEntries),
75      totalWidth(params->issueWidth),
76      numPhysIntRegs(params->numPhysIntRegs),
77      numPhysFloatRegs(params->numPhysFloatRegs),
78      commitToIEWDelay(params->commitToIEWDelay)
79{
80    assert(fuPool);
81
82    switchedOut = false;
83
84    numThreads = params->numThreads;
85
86    // Set the number of physical registers as the number of int + float
87    numPhysRegs = numPhysIntRegs + numPhysFloatRegs;
88
89    //Create an entry for each physical register within the
90    //dependency graph.
91    dependGraph.resize(numPhysRegs);
92
93    // Resize the register scoreboard.
94    regScoreboard.resize(numPhysRegs);
95
96    //Initialize Mem Dependence Units
97    for (ThreadID tid = 0; tid < numThreads; tid++) {
98        memDepUnit[tid].init(params, tid);
99        memDepUnit[tid].setIQ(this);
100    }
101
102    resetState();
103
104    std::string policy = params->smtIQPolicy;
105
106    //Convert string to lowercase
107    std::transform(policy.begin(), policy.end(), policy.begin(),
108                   (int(*)(int)) tolower);
109
110    //Figure out resource sharing policy
111    if (policy == "dynamic") {
112        iqPolicy = Dynamic;
113
114        //Set Max Entries to Total ROB Capacity
115        for (ThreadID tid = 0; tid < numThreads; tid++) {
116            maxEntries[tid] = numEntries;
117        }
118
119    } else if (policy == "partitioned") {
120        iqPolicy = Partitioned;
121
122        //@todo:make work if part_amt doesnt divide evenly.
123        int part_amt = numEntries / numThreads;
124
125        //Divide ROB up evenly
126        for (ThreadID tid = 0; tid < numThreads; tid++) {
127            maxEntries[tid] = part_amt;
128        }
129
130        DPRINTF(IQ, "IQ sharing policy set to Partitioned:"
131                "%i entries per thread.\n",part_amt);
132    } else if (policy == "threshold") {
133        iqPolicy = Threshold;
134
135        double threshold =  (double)params->smtIQThreshold / 100;
136
137        int thresholdIQ = (int)((double)threshold * numEntries);
138
139        //Divide up by threshold amount
140        for (ThreadID tid = 0; tid < numThreads; tid++) {
141            maxEntries[tid] = thresholdIQ;
142        }
143
144        DPRINTF(IQ, "IQ sharing policy set to Threshold:"
145                "%i entries per thread.\n",thresholdIQ);
146   } else {
147       assert(0 && "Invalid IQ Sharing Policy.Options Are:{Dynamic,"
148              "Partitioned, Threshold}");
149   }
150}
151
152template <class Impl>
153InstructionQueue<Impl>::~InstructionQueue()
154{
155    dependGraph.reset();
156#ifdef DEBUG
157    cprintf("Nodes traversed: %i, removed: %i\n",
158            dependGraph.nodesTraversed, dependGraph.nodesRemoved);
159#endif
160}
161
162template <class Impl>
163std::string
164InstructionQueue<Impl>::name() const
165{
166    return cpu->name() + ".iq";
167}
168
169template <class Impl>
170void
171InstructionQueue<Impl>::regStats()
172{
173    using namespace Stats;
174    iqInstsAdded
175        .name(name() + ".iqInstsAdded")
176        .desc("Number of instructions added to the IQ (excludes non-spec)")
177        .prereq(iqInstsAdded);
178
179    iqNonSpecInstsAdded
180        .name(name() + ".iqNonSpecInstsAdded")
181        .desc("Number of non-speculative instructions added to the IQ")
182        .prereq(iqNonSpecInstsAdded);
183
184    iqInstsIssued
185        .name(name() + ".iqInstsIssued")
186        .desc("Number of instructions issued")
187        .prereq(iqInstsIssued);
188
189    iqIntInstsIssued
190        .name(name() + ".iqIntInstsIssued")
191        .desc("Number of integer instructions issued")
192        .prereq(iqIntInstsIssued);
193
194    iqFloatInstsIssued
195        .name(name() + ".iqFloatInstsIssued")
196        .desc("Number of float instructions issued")
197        .prereq(iqFloatInstsIssued);
198
199    iqBranchInstsIssued
200        .name(name() + ".iqBranchInstsIssued")
201        .desc("Number of branch instructions issued")
202        .prereq(iqBranchInstsIssued);
203
204    iqMemInstsIssued
205        .name(name() + ".iqMemInstsIssued")
206        .desc("Number of memory instructions issued")
207        .prereq(iqMemInstsIssued);
208
209    iqMiscInstsIssued
210        .name(name() + ".iqMiscInstsIssued")
211        .desc("Number of miscellaneous instructions issued")
212        .prereq(iqMiscInstsIssued);
213
214    iqSquashedInstsIssued
215        .name(name() + ".iqSquashedInstsIssued")
216        .desc("Number of squashed instructions issued")
217        .prereq(iqSquashedInstsIssued);
218
219    iqSquashedInstsExamined
220        .name(name() + ".iqSquashedInstsExamined")
221        .desc("Number of squashed instructions iterated over during squash;"
222              " mainly for profiling")
223        .prereq(iqSquashedInstsExamined);
224
225    iqSquashedOperandsExamined
226        .name(name() + ".iqSquashedOperandsExamined")
227        .desc("Number of squashed operands that are examined and possibly "
228              "removed from graph")
229        .prereq(iqSquashedOperandsExamined);
230
231    iqSquashedNonSpecRemoved
232        .name(name() + ".iqSquashedNonSpecRemoved")
233        .desc("Number of squashed non-spec instructions that were removed")
234        .prereq(iqSquashedNonSpecRemoved);
235/*
236    queueResDist
237        .init(Num_OpClasses, 0, 99, 2)
238        .name(name() + ".IQ:residence:")
239        .desc("cycles from dispatch to issue")
240        .flags(total | pdf | cdf )
241        ;
242    for (int i = 0; i < Num_OpClasses; ++i) {
243        queueResDist.subname(i, opClassStrings[i]);
244    }
245*/
246    numIssuedDist
247        .init(0,totalWidth,1)
248        .name(name() + ".ISSUE:issued_per_cycle")
249        .desc("Number of insts issued each cycle")
250        .flags(pdf)
251        ;
252/*
253    dist_unissued
254        .init(Num_OpClasses+2)
255        .name(name() + ".ISSUE:unissued_cause")
256        .desc("Reason ready instruction not issued")
257        .flags(pdf | dist)
258        ;
259    for (int i=0; i < (Num_OpClasses + 2); ++i) {
260        dist_unissued.subname(i, unissued_names[i]);
261    }
262*/
263    statIssuedInstType
264        .init(numThreads,Enums::Num_OpClass)
265        .name(name() + ".ISSUE:FU_type")
266        .desc("Type of FU issued")
267        .flags(total | pdf | dist)
268        ;
269    statIssuedInstType.ysubnames(Enums::OpClassStrings);
270
271    //
272    //  How long did instructions for a particular FU type wait prior to issue
273    //
274/*
275    issueDelayDist
276        .init(Num_OpClasses,0,99,2)
277        .name(name() + ".ISSUE:")
278        .desc("cycles from operands ready to issue")
279        .flags(pdf | cdf)
280        ;
281
282    for (int i=0; i<Num_OpClasses; ++i) {
283        std::stringstream subname;
284        subname << opClassStrings[i] << "_delay";
285        issueDelayDist.subname(i, subname.str());
286    }
287*/
288    issueRate
289        .name(name() + ".ISSUE:rate")
290        .desc("Inst issue rate")
291        .flags(total)
292        ;
293    issueRate = iqInstsIssued / cpu->numCycles;
294
295    statFuBusy
296        .init(Num_OpClasses)
297        .name(name() + ".ISSUE:fu_full")
298        .desc("attempts to use FU when none available")
299        .flags(pdf | dist)
300        ;
301    for (int i=0; i < Num_OpClasses; ++i) {
302        statFuBusy.subname(i, Enums::OpClassStrings[i]);
303    }
304
305    fuBusy
306        .init(numThreads)
307        .name(name() + ".ISSUE:fu_busy_cnt")
308        .desc("FU busy when requested")
309        .flags(total)
310        ;
311
312    fuBusyRate
313        .name(name() + ".ISSUE:fu_busy_rate")
314        .desc("FU busy rate (busy events/executed inst)")
315        .flags(total)
316        ;
317    fuBusyRate = fuBusy / iqInstsIssued;
318
319    for (ThreadID tid = 0; tid < numThreads; tid++) {
320        // Tell mem dependence unit to reg stats as well.
321        memDepUnit[tid].regStats();
322    }
323}
324
325template <class Impl>
326void
327InstructionQueue<Impl>::resetState()
328{
329    //Initialize thread IQ counts
330    for (ThreadID tid = 0; tid <numThreads; tid++) {
331        count[tid] = 0;
332        instList[tid].clear();
333    }
334
335    // Initialize the number of free IQ entries.
336    freeEntries = numEntries;
337
338    // Note that in actuality, the registers corresponding to the logical
339    // registers start off as ready.  However this doesn't matter for the
340    // IQ as the instruction should have been correctly told if those
341    // registers are ready in rename.  Thus it can all be initialized as
342    // unready.
343    for (int i = 0; i < numPhysRegs; ++i) {
344        regScoreboard[i] = false;
345    }
346
347    for (ThreadID tid = 0; tid < numThreads; ++tid) {
348        squashedSeqNum[tid] = 0;
349    }
350
351    for (int i = 0; i < Num_OpClasses; ++i) {
352        while (!readyInsts[i].empty())
353            readyInsts[i].pop();
354        queueOnList[i] = false;
355        readyIt[i] = listOrder.end();
356    }
357    nonSpecInsts.clear();
358    listOrder.clear();
359}
360
361template <class Impl>
362void
363InstructionQueue<Impl>::setActiveThreads(list<ThreadID> *at_ptr)
364{
365    activeThreads = at_ptr;
366}
367
368template <class Impl>
369void
370InstructionQueue<Impl>::setIssueToExecuteQueue(TimeBuffer<IssueStruct> *i2e_ptr)
371{
372      issueToExecuteQueue = i2e_ptr;
373}
374
375template <class Impl>
376void
377InstructionQueue<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr)
378{
379    timeBuffer = tb_ptr;
380
381    fromCommit = timeBuffer->getWire(-commitToIEWDelay);
382}
383
384template <class Impl>
385void
386InstructionQueue<Impl>::switchOut()
387{
388/*
389    if (!instList[0].empty() || (numEntries != freeEntries) ||
390        !readyInsts[0].empty() || !nonSpecInsts.empty() || !listOrder.empty()) {
391        dumpInsts();
392//        assert(0);
393    }
394*/
395    resetState();
396    dependGraph.reset();
397    instsToExecute.clear();
398    switchedOut = true;
399    for (ThreadID tid = 0; tid < numThreads; ++tid) {
400        memDepUnit[tid].switchOut();
401    }
402}
403
404template <class Impl>
405void
406InstructionQueue<Impl>::takeOverFrom()
407{
408    switchedOut = false;
409}
410
411template <class Impl>
412int
413InstructionQueue<Impl>::entryAmount(ThreadID num_threads)
414{
415    if (iqPolicy == Partitioned) {
416        return numEntries / num_threads;
417    } else {
418        return 0;
419    }
420}
421
422
423template <class Impl>
424void
425InstructionQueue<Impl>::resetEntries()
426{
427    if (iqPolicy != Dynamic || numThreads > 1) {
428        int active_threads = activeThreads->size();
429
430        list<ThreadID>::iterator threads = activeThreads->begin();
431        list<ThreadID>::iterator end = activeThreads->end();
432
433        while (threads != end) {
434            ThreadID tid = *threads++;
435
436            if (iqPolicy == Partitioned) {
437                maxEntries[tid] = numEntries / active_threads;
438            } else if(iqPolicy == Threshold && active_threads == 1) {
439                maxEntries[tid] = numEntries;
440            }
441        }
442    }
443}
444
445template <class Impl>
446unsigned
447InstructionQueue<Impl>::numFreeEntries()
448{
449    return freeEntries;
450}
451
452template <class Impl>
453unsigned
454InstructionQueue<Impl>::numFreeEntries(ThreadID tid)
455{
456    return maxEntries[tid] - count[tid];
457}
458
459// Might want to do something more complex if it knows how many instructions
460// will be issued this cycle.
461template <class Impl>
462bool
463InstructionQueue<Impl>::isFull()
464{
465    if (freeEntries == 0) {
466        return(true);
467    } else {
468        return(false);
469    }
470}
471
472template <class Impl>
473bool
474InstructionQueue<Impl>::isFull(ThreadID tid)
475{
476    if (numFreeEntries(tid) == 0) {
477        return(true);
478    } else {
479        return(false);
480    }
481}
482
483template <class Impl>
484bool
485InstructionQueue<Impl>::hasReadyInsts()
486{
487    if (!listOrder.empty()) {
488        return true;
489    }
490
491    for (int i = 0; i < Num_OpClasses; ++i) {
492        if (!readyInsts[i].empty()) {
493            return true;
494        }
495    }
496
497    return false;
498}
499
500template <class Impl>
501void
502InstructionQueue<Impl>::insert(DynInstPtr &new_inst)
503{
504    // Make sure the instruction is valid
505    assert(new_inst);
506
507    DPRINTF(IQ, "Adding instruction [sn:%lli] PC %s to the IQ.\n",
508            new_inst->seqNum, new_inst->pcState());
509
510    assert(freeEntries != 0);
511
512    instList[new_inst->threadNumber].push_back(new_inst);
513
514    --freeEntries;
515
516    new_inst->setInIQ();
517
518    // Look through its source registers (physical regs), and mark any
519    // dependencies.
520    addToDependents(new_inst);
521
522    // Have this instruction set itself as the producer of its destination
523    // register(s).
524    addToProducers(new_inst);
525
526    if (new_inst->isMemRef()) {
527        memDepUnit[new_inst->threadNumber].insert(new_inst);
528    } else {
529        addIfReady(new_inst);
530    }
531
532    ++iqInstsAdded;
533
534    count[new_inst->threadNumber]++;
535
536    assert(freeEntries == (numEntries - countInsts()));
537}
538
539template <class Impl>
540void
541InstructionQueue<Impl>::insertNonSpec(DynInstPtr &new_inst)
542{
543    // @todo: Clean up this code; can do it by setting inst as unable
544    // to issue, then calling normal insert on the inst.
545
546    assert(new_inst);
547
548    nonSpecInsts[new_inst->seqNum] = new_inst;
549
550    DPRINTF(IQ, "Adding non-speculative instruction [sn:%lli] PC %s "
551            "to the IQ.\n",
552            new_inst->seqNum, new_inst->pcState());
553
554    assert(freeEntries != 0);
555
556    instList[new_inst->threadNumber].push_back(new_inst);
557
558    --freeEntries;
559
560    new_inst->setInIQ();
561
562    // Have this instruction set itself as the producer of its destination
563    // register(s).
564    addToProducers(new_inst);
565
566    // If it's a memory instruction, add it to the memory dependency
567    // unit.
568    if (new_inst->isMemRef()) {
569        memDepUnit[new_inst->threadNumber].insertNonSpec(new_inst);
570    }
571
572    ++iqNonSpecInstsAdded;
573
574    count[new_inst->threadNumber]++;
575
576    assert(freeEntries == (numEntries - countInsts()));
577}
578
579template <class Impl>
580void
581InstructionQueue<Impl>::insertBarrier(DynInstPtr &barr_inst)
582{
583    memDepUnit[barr_inst->threadNumber].insertBarrier(barr_inst);
584
585    insertNonSpec(barr_inst);
586}
587
588template <class Impl>
589typename Impl::DynInstPtr
590InstructionQueue<Impl>::getInstToExecute()
591{
592    assert(!instsToExecute.empty());
593    DynInstPtr inst = instsToExecute.front();
594    instsToExecute.pop_front();
595    return inst;
596}
597
598template <class Impl>
599void
600InstructionQueue<Impl>::addToOrderList(OpClass op_class)
601{
602    assert(!readyInsts[op_class].empty());
603
604    ListOrderEntry queue_entry;
605
606    queue_entry.queueType = op_class;
607
608    queue_entry.oldestInst = readyInsts[op_class].top()->seqNum;
609
610    ListOrderIt list_it = listOrder.begin();
611    ListOrderIt list_end_it = listOrder.end();
612
613    while (list_it != list_end_it) {
614        if ((*list_it).oldestInst > queue_entry.oldestInst) {
615            break;
616        }
617
618        list_it++;
619    }
620
621    readyIt[op_class] = listOrder.insert(list_it, queue_entry);
622    queueOnList[op_class] = true;
623}
624
625template <class Impl>
626void
627InstructionQueue<Impl>::moveToYoungerInst(ListOrderIt list_order_it)
628{
629    // Get iterator of next item on the list
630    // Delete the original iterator
631    // Determine if the next item is either the end of the list or younger
632    // than the new instruction.  If so, then add in a new iterator right here.
633    // If not, then move along.
634    ListOrderEntry queue_entry;
635    OpClass op_class = (*list_order_it).queueType;
636    ListOrderIt next_it = list_order_it;
637
638    ++next_it;
639
640    queue_entry.queueType = op_class;
641    queue_entry.oldestInst = readyInsts[op_class].top()->seqNum;
642
643    while (next_it != listOrder.end() &&
644           (*next_it).oldestInst < queue_entry.oldestInst) {
645        ++next_it;
646    }
647
648    readyIt[op_class] = listOrder.insert(next_it, queue_entry);
649}
650
651template <class Impl>
652void
653InstructionQueue<Impl>::processFUCompletion(DynInstPtr &inst, int fu_idx)
654{
655    DPRINTF(IQ, "Processing FU completion [sn:%lli]\n", inst->seqNum);
656    // The CPU could have been sleeping until this op completed (*extremely*
657    // long latency op).  Wake it if it was.  This may be overkill.
658    if (isSwitchedOut()) {
659        DPRINTF(IQ, "FU completion not processed, IQ is switched out [sn:%lli]\n",
660                inst->seqNum);
661        return;
662    }
663
664    iewStage->wakeCPU();
665
666    if (fu_idx > -1)
667        fuPool->freeUnitNextCycle(fu_idx);
668
669    // @todo: Ensure that these FU Completions happen at the beginning
670    // of a cycle, otherwise they could add too many instructions to
671    // the queue.
672    issueToExecuteQueue->access(-1)->size++;
673    instsToExecute.push_back(inst);
674}
675
676// @todo: Figure out a better way to remove the squashed items from the
677// lists.  Checking the top item of each list to see if it's squashed
678// wastes time and forces jumps.
679template <class Impl>
680void
681InstructionQueue<Impl>::scheduleReadyInsts()
682{
683    DPRINTF(IQ, "Attempting to schedule ready instructions from "
684            "the IQ.\n");
685
686    IssueStruct *i2e_info = issueToExecuteQueue->access(0);
687
688    // Have iterator to head of the list
689    // While I haven't exceeded bandwidth or reached the end of the list,
690    // Try to get a FU that can do what this op needs.
691    // If successful, change the oldestInst to the new top of the list, put
692    // the queue in the proper place in the list.
693    // Increment the iterator.
694    // This will avoid trying to schedule a certain op class if there are no
695    // FUs that handle it.
696    ListOrderIt order_it = listOrder.begin();
697    ListOrderIt order_end_it = listOrder.end();
698    int total_issued = 0;
699
700    while (total_issued < totalWidth &&
701           iewStage->canIssue() &&
702           order_it != order_end_it) {
703        OpClass op_class = (*order_it).queueType;
704
705        assert(!readyInsts[op_class].empty());
706
707        DynInstPtr issuing_inst = readyInsts[op_class].top();
708
709        assert(issuing_inst->seqNum == (*order_it).oldestInst);
710
711        if (issuing_inst->isSquashed()) {
712            readyInsts[op_class].pop();
713
714            if (!readyInsts[op_class].empty()) {
715                moveToYoungerInst(order_it);
716            } else {
717                readyIt[op_class] = listOrder.end();
718                queueOnList[op_class] = false;
719            }
720
721            listOrder.erase(order_it++);
722
723            ++iqSquashedInstsIssued;
724
725            continue;
726        }
727
728        int idx = -2;
729        int op_latency = 1;
730        ThreadID tid = issuing_inst->threadNumber;
731
732        if (op_class != No_OpClass) {
733            idx = fuPool->getUnit(op_class);
734
735            if (idx > -1) {
736                op_latency = fuPool->getOpLatency(op_class);
737            }
738        }
739
740        // If we have an instruction that doesn't require a FU, or a
741        // valid FU, then schedule for execution.
742        if (idx == -2 || idx != -1) {
743            if (op_latency == 1) {
744                i2e_info->size++;
745                instsToExecute.push_back(issuing_inst);
746
747                // Add the FU onto the list of FU's to be freed next
748                // cycle if we used one.
749                if (idx >= 0)
750                    fuPool->freeUnitNextCycle(idx);
751            } else {
752                int issue_latency = fuPool->getIssueLatency(op_class);
753                // Generate completion event for the FU
754                FUCompletion *execution = new FUCompletion(issuing_inst,
755                                                           idx, this);
756
757                cpu->schedule(execution, curTick + cpu->ticks(op_latency - 1));
758
759                // @todo: Enforce that issue_latency == 1 or op_latency
760                if (issue_latency > 1) {
761                    // If FU isn't pipelined, then it must be freed
762                    // upon the execution completing.
763                    execution->setFreeFU();
764                } else {
765                    // Add the FU onto the list of FU's to be freed next cycle.
766                    fuPool->freeUnitNextCycle(idx);
767                }
768            }
769
770            DPRINTF(IQ, "Thread %i: Issuing instruction PC %s "
771                    "[sn:%lli]\n",
772                    tid, issuing_inst->pcState(),
773                    issuing_inst->seqNum);
774
775            readyInsts[op_class].pop();
776
777            if (!readyInsts[op_class].empty()) {
778                moveToYoungerInst(order_it);
779            } else {
780                readyIt[op_class] = listOrder.end();
781                queueOnList[op_class] = false;
782            }
783
784            issuing_inst->setIssued();
785            ++total_issued;
786
787            if (!issuing_inst->isMemRef()) {
788                // Memory instructions can not be freed from the IQ until they
789                // complete.
790                ++freeEntries;
791                count[tid]--;
792                issuing_inst->clearInIQ();
793            } else {
794                memDepUnit[tid].issue(issuing_inst);
795            }
796
797            listOrder.erase(order_it++);
798            statIssuedInstType[tid][op_class]++;
799            iewStage->incrWb(issuing_inst->seqNum);
800        } else {
801            statFuBusy[op_class]++;
802            fuBusy[tid]++;
803            ++order_it;
804        }
805    }
806
807    numIssuedDist.sample(total_issued);
808    iqInstsIssued+= total_issued;
809
810    // If we issued any instructions, tell the CPU we had activity.
811    if (total_issued) {
812        cpu->activityThisCycle();
813    } else {
814        DPRINTF(IQ, "Not able to schedule any instructions.\n");
815    }
816}
817
818template <class Impl>
819void
820InstructionQueue<Impl>::scheduleNonSpec(const InstSeqNum &inst)
821{
822    DPRINTF(IQ, "Marking nonspeculative instruction [sn:%lli] as ready "
823            "to execute.\n", inst);
824
825    NonSpecMapIt inst_it = nonSpecInsts.find(inst);
826
827    assert(inst_it != nonSpecInsts.end());
828
829    ThreadID tid = (*inst_it).second->threadNumber;
830
831    (*inst_it).second->setAtCommit();
832
833    (*inst_it).second->setCanIssue();
834
835    if (!(*inst_it).second->isMemRef()) {
836        addIfReady((*inst_it).second);
837    } else {
838        memDepUnit[tid].nonSpecInstReady((*inst_it).second);
839    }
840
841    (*inst_it).second = NULL;
842
843    nonSpecInsts.erase(inst_it);
844}
845
846template <class Impl>
847void
848InstructionQueue<Impl>::commit(const InstSeqNum &inst, ThreadID tid)
849{
850    DPRINTF(IQ, "[tid:%i]: Committing instructions older than [sn:%i]\n",
851            tid,inst);
852
853    ListIt iq_it = instList[tid].begin();
854
855    while (iq_it != instList[tid].end() &&
856           (*iq_it)->seqNum <= inst) {
857        ++iq_it;
858        instList[tid].pop_front();
859    }
860
861    assert(freeEntries == (numEntries - countInsts()));
862}
863
864template <class Impl>
865int
866InstructionQueue<Impl>::wakeDependents(DynInstPtr &completed_inst)
867{
868    int dependents = 0;
869
870    DPRINTF(IQ, "Waking dependents of completed instruction.\n");
871
872    assert(!completed_inst->isSquashed());
873
874    // Tell the memory dependence unit to wake any dependents on this
875    // instruction if it is a memory instruction.  Also complete the memory
876    // instruction at this point since we know it executed without issues.
877    // @todo: Might want to rename "completeMemInst" to something that
878    // indicates that it won't need to be replayed, and call this
879    // earlier.  Might not be a big deal.
880    if (completed_inst->isMemRef()) {
881        memDepUnit[completed_inst->threadNumber].wakeDependents(completed_inst);
882        completeMemInst(completed_inst);
883    } else if (completed_inst->isMemBarrier() ||
884               completed_inst->isWriteBarrier()) {
885        memDepUnit[completed_inst->threadNumber].completeBarrier(completed_inst);
886    }
887
888    for (int dest_reg_idx = 0;
889         dest_reg_idx < completed_inst->numDestRegs();
890         dest_reg_idx++)
891    {
892        PhysRegIndex dest_reg =
893            completed_inst->renamedDestRegIdx(dest_reg_idx);
894
895        // Special case of uniq or control registers.  They are not
896        // handled by the IQ and thus have no dependency graph entry.
897        // @todo Figure out a cleaner way to handle this.
898        if (dest_reg >= numPhysRegs) {
899            DPRINTF(IQ, "dest_reg :%d, numPhysRegs: %d\n", dest_reg,
900                    numPhysRegs);
901            continue;
902        }
903
904        DPRINTF(IQ, "Waking any dependents on register %i.\n",
905                (int) dest_reg);
906
907        //Go through the dependency chain, marking the registers as
908        //ready within the waiting instructions.
909        DynInstPtr dep_inst = dependGraph.pop(dest_reg);
910
911        while (dep_inst) {
912            DPRINTF(IQ, "Waking up a dependent instruction, [sn:%lli] "
913                    "PC %s.\n", dep_inst->seqNum, dep_inst->pcState());
914
915            // Might want to give more information to the instruction
916            // so that it knows which of its source registers is
917            // ready.  However that would mean that the dependency
918            // graph entries would need to hold the src_reg_idx.
919            dep_inst->markSrcRegReady();
920
921            addIfReady(dep_inst);
922
923            dep_inst = dependGraph.pop(dest_reg);
924
925            ++dependents;
926        }
927
928        // Reset the head node now that all of its dependents have
929        // been woken up.
930        assert(dependGraph.empty(dest_reg));
931        dependGraph.clearInst(dest_reg);
932
933        // Mark the scoreboard as having that register ready.
934        regScoreboard[dest_reg] = true;
935    }
936    return dependents;
937}
938
939template <class Impl>
940void
941InstructionQueue<Impl>::addReadyMemInst(DynInstPtr &ready_inst)
942{
943    OpClass op_class = ready_inst->opClass();
944
945    readyInsts[op_class].push(ready_inst);
946
947    // Will need to reorder the list if either a queue is not on the list,
948    // or it has an older instruction than last time.
949    if (!queueOnList[op_class]) {
950        addToOrderList(op_class);
951    } else if (readyInsts[op_class].top()->seqNum  <
952               (*readyIt[op_class]).oldestInst) {
953        listOrder.erase(readyIt[op_class]);
954        addToOrderList(op_class);
955    }
956
957    DPRINTF(IQ, "Instruction is ready to issue, putting it onto "
958            "the ready list, PC %s opclass:%i [sn:%lli].\n",
959            ready_inst->pcState(), op_class, ready_inst->seqNum);
960}
961
962template <class Impl>
963void
964InstructionQueue<Impl>::rescheduleMemInst(DynInstPtr &resched_inst)
965{
966    DPRINTF(IQ, "Rescheduling mem inst [sn:%lli]\n", resched_inst->seqNum);
967    resched_inst->clearCanIssue();
968    memDepUnit[resched_inst->threadNumber].reschedule(resched_inst);
969}
970
971template <class Impl>
972void
973InstructionQueue<Impl>::replayMemInst(DynInstPtr &replay_inst)
974{
975    memDepUnit[replay_inst->threadNumber].replay(replay_inst);
976}
977
978template <class Impl>
979void
980InstructionQueue<Impl>::completeMemInst(DynInstPtr &completed_inst)
981{
982    ThreadID tid = completed_inst->threadNumber;
983
984    DPRINTF(IQ, "Completing mem instruction PC: %s [sn:%lli]\n",
985            completed_inst->pcState(), completed_inst->seqNum);
986
987    ++freeEntries;
988
989    completed_inst->memOpDone = true;
990
991    memDepUnit[tid].completed(completed_inst);
992    count[tid]--;
993}
994
995template <class Impl>
996void
997InstructionQueue<Impl>::violation(DynInstPtr &store,
998                                  DynInstPtr &faulting_load)
999{
1000    memDepUnit[store->threadNumber].violation(store, faulting_load);
1001}
1002
1003template <class Impl>
1004void
1005InstructionQueue<Impl>::squash(ThreadID tid)
1006{
1007    DPRINTF(IQ, "[tid:%i]: Starting to squash instructions in "
1008            "the IQ.\n", tid);
1009
1010    // Read instruction sequence number of last instruction out of the
1011    // time buffer.
1012    squashedSeqNum[tid] = fromCommit->commitInfo[tid].doneSeqNum;
1013
1014    // Call doSquash if there are insts in the IQ
1015    if (count[tid] > 0) {
1016        doSquash(tid);
1017    }
1018
1019    // Also tell the memory dependence unit to squash.
1020    memDepUnit[tid].squash(squashedSeqNum[tid], tid);
1021}
1022
1023template <class Impl>
1024void
1025InstructionQueue<Impl>::doSquash(ThreadID tid)
1026{
1027    // Start at the tail.
1028    ListIt squash_it = instList[tid].end();
1029    --squash_it;
1030
1031    DPRINTF(IQ, "[tid:%i]: Squashing until sequence number %i!\n",
1032            tid, squashedSeqNum[tid]);
1033
1034    // Squash any instructions younger than the squashed sequence number
1035    // given.
1036    while (squash_it != instList[tid].end() &&
1037           (*squash_it)->seqNum > squashedSeqNum[tid]) {
1038
1039        DynInstPtr squashed_inst = (*squash_it);
1040
1041        // Only handle the instruction if it actually is in the IQ and
1042        // hasn't already been squashed in the IQ.
1043        if (squashed_inst->threadNumber != tid ||
1044            squashed_inst->isSquashedInIQ()) {
1045            --squash_it;
1046            continue;
1047        }
1048
1049        if (!squashed_inst->isIssued() ||
1050            (squashed_inst->isMemRef() &&
1051             !squashed_inst->memOpDone)) {
1052
1053            DPRINTF(IQ, "[tid:%i]: Instruction [sn:%lli] PC %s squashed.\n",
1054                    tid, squashed_inst->seqNum, squashed_inst->pcState());
1055
1056            // Remove the instruction from the dependency list.
1057            if (!squashed_inst->isNonSpeculative() &&
1058                !squashed_inst->isStoreConditional() &&
1059                !squashed_inst->isMemBarrier() &&
1060                !squashed_inst->isWriteBarrier()) {
1061
1062                for (int src_reg_idx = 0;
1063                     src_reg_idx < squashed_inst->numSrcRegs();
1064                     src_reg_idx++)
1065                {
1066                    PhysRegIndex src_reg =
1067                        squashed_inst->renamedSrcRegIdx(src_reg_idx);
1068
1069                    // Only remove it from the dependency graph if it
1070                    // was placed there in the first place.
1071
1072                    // Instead of doing a linked list traversal, we
1073                    // can just remove these squashed instructions
1074                    // either at issue time, or when the register is
1075                    // overwritten.  The only downside to this is it
1076                    // leaves more room for error.
1077
1078                    if (!squashed_inst->isReadySrcRegIdx(src_reg_idx) &&
1079                        src_reg < numPhysRegs) {
1080                        dependGraph.remove(src_reg, squashed_inst);
1081                    }
1082
1083
1084                    ++iqSquashedOperandsExamined;
1085                }
1086            } else if (!squashed_inst->isStoreConditional() ||
1087                       !squashed_inst->isCompleted()) {
1088                NonSpecMapIt ns_inst_it =
1089                    nonSpecInsts.find(squashed_inst->seqNum);
1090                assert(ns_inst_it != nonSpecInsts.end());
1091                if (ns_inst_it == nonSpecInsts.end()) {
1092                    assert(squashed_inst->getFault() != NoFault);
1093                } else {
1094
1095                    (*ns_inst_it).second = NULL;
1096
1097                    nonSpecInsts.erase(ns_inst_it);
1098
1099                    ++iqSquashedNonSpecRemoved;
1100                }
1101            }
1102
1103            // Might want to also clear out the head of the dependency graph.
1104
1105            // Mark it as squashed within the IQ.
1106            squashed_inst->setSquashedInIQ();
1107
1108            // @todo: Remove this hack where several statuses are set so the
1109            // inst will flow through the rest of the pipeline.
1110            squashed_inst->setIssued();
1111            squashed_inst->setCanCommit();
1112            squashed_inst->clearInIQ();
1113
1114            //Update Thread IQ Count
1115            count[squashed_inst->threadNumber]--;
1116
1117            ++freeEntries;
1118        }
1119
1120        instList[tid].erase(squash_it--);
1121        ++iqSquashedInstsExamined;
1122    }
1123}
1124
1125template <class Impl>
1126bool
1127InstructionQueue<Impl>::addToDependents(DynInstPtr &new_inst)
1128{
1129    // Loop through the instruction's source registers, adding
1130    // them to the dependency list if they are not ready.
1131    int8_t total_src_regs = new_inst->numSrcRegs();
1132    bool return_val = false;
1133
1134    for (int src_reg_idx = 0;
1135         src_reg_idx < total_src_regs;
1136         src_reg_idx++)
1137    {
1138        // Only add it to the dependency graph if it's not ready.
1139        if (!new_inst->isReadySrcRegIdx(src_reg_idx)) {
1140            PhysRegIndex src_reg = new_inst->renamedSrcRegIdx(src_reg_idx);
1141
1142            // Check the IQ's scoreboard to make sure the register
1143            // hasn't become ready while the instruction was in flight
1144            // between stages.  Only if it really isn't ready should
1145            // it be added to the dependency graph.
1146            if (src_reg >= numPhysRegs) {
1147                continue;
1148            } else if (regScoreboard[src_reg] == false) {
1149                DPRINTF(IQ, "Instruction PC %s has src reg %i that "
1150                        "is being added to the dependency chain.\n",
1151                        new_inst->pcState(), src_reg);
1152
1153                dependGraph.insert(src_reg, new_inst);
1154
1155                // Change the return value to indicate that something
1156                // was added to the dependency graph.
1157                return_val = true;
1158            } else {
1159                DPRINTF(IQ, "Instruction PC %s has src reg %i that "
1160                        "became ready before it reached the IQ.\n",
1161                        new_inst->pcState(), src_reg);
1162                // Mark a register ready within the instruction.
1163                new_inst->markSrcRegReady(src_reg_idx);
1164            }
1165        }
1166    }
1167
1168    return return_val;
1169}
1170
1171template <class Impl>
1172void
1173InstructionQueue<Impl>::addToProducers(DynInstPtr &new_inst)
1174{
1175    // Nothing really needs to be marked when an instruction becomes
1176    // the producer of a register's value, but for convenience a ptr
1177    // to the producing instruction will be placed in the head node of
1178    // the dependency links.
1179    int8_t total_dest_regs = new_inst->numDestRegs();
1180
1181    for (int dest_reg_idx = 0;
1182         dest_reg_idx < total_dest_regs;
1183         dest_reg_idx++)
1184    {
1185        PhysRegIndex dest_reg = new_inst->renamedDestRegIdx(dest_reg_idx);
1186
1187        // Instructions that use the misc regs will have a reg number
1188        // higher than the normal physical registers.  In this case these
1189        // registers are not renamed, and there is no need to track
1190        // dependencies as these instructions must be executed at commit.
1191        if (dest_reg >= numPhysRegs) {
1192            continue;
1193        }
1194
1195        if (!dependGraph.empty(dest_reg)) {
1196            dependGraph.dump();
1197            panic("Dependency graph %i not empty!", dest_reg);
1198        }
1199
1200        dependGraph.setInst(dest_reg, new_inst);
1201
1202        // Mark the scoreboard to say it's not yet ready.
1203        regScoreboard[dest_reg] = false;
1204    }
1205}
1206
1207template <class Impl>
1208void
1209InstructionQueue<Impl>::addIfReady(DynInstPtr &inst)
1210{
1211    // If the instruction now has all of its source registers
1212    // available, then add it to the list of ready instructions.
1213    if (inst->readyToIssue()) {
1214
1215        //Add the instruction to the proper ready list.
1216        if (inst->isMemRef()) {
1217
1218            DPRINTF(IQ, "Checking if memory instruction can issue.\n");
1219
1220            // Message to the mem dependence unit that this instruction has
1221            // its registers ready.
1222            memDepUnit[inst->threadNumber].regsReady(inst);
1223
1224            return;
1225        }
1226
1227        OpClass op_class = inst->opClass();
1228
1229        DPRINTF(IQ, "Instruction is ready to issue, putting it onto "
1230                "the ready list, PC %s opclass:%i [sn:%lli].\n",
1231                inst->pcState(), op_class, inst->seqNum);
1232
1233        readyInsts[op_class].push(inst);
1234
1235        // Will need to reorder the list if either a queue is not on the list,
1236        // or it has an older instruction than last time.
1237        if (!queueOnList[op_class]) {
1238            addToOrderList(op_class);
1239        } else if (readyInsts[op_class].top()->seqNum  <
1240                   (*readyIt[op_class]).oldestInst) {
1241            listOrder.erase(readyIt[op_class]);
1242            addToOrderList(op_class);
1243        }
1244    }
1245}
1246
1247template <class Impl>
1248int
1249InstructionQueue<Impl>::countInsts()
1250{
1251#if 0
1252    //ksewell:This works but definitely could use a cleaner write
1253    //with a more intuitive way of counting. Right now it's
1254    //just brute force ....
1255    // Change the #if if you want to use this method.
1256    int total_insts = 0;
1257
1258    for (ThreadID tid = 0; tid < numThreads; ++tid) {
1259        ListIt count_it = instList[tid].begin();
1260
1261        while (count_it != instList[tid].end()) {
1262            if (!(*count_it)->isSquashed() && !(*count_it)->isSquashedInIQ()) {
1263                if (!(*count_it)->isIssued()) {
1264                    ++total_insts;
1265                } else if ((*count_it)->isMemRef() &&
1266                           !(*count_it)->memOpDone) {
1267                    // Loads that have not been marked as executed still count
1268                    // towards the total instructions.
1269                    ++total_insts;
1270                }
1271            }
1272
1273            ++count_it;
1274        }
1275    }
1276
1277    return total_insts;
1278#else
1279    return numEntries - freeEntries;
1280#endif
1281}
1282
1283template <class Impl>
1284void
1285InstructionQueue<Impl>::dumpLists()
1286{
1287    for (int i = 0; i < Num_OpClasses; ++i) {
1288        cprintf("Ready list %i size: %i\n", i, readyInsts[i].size());
1289
1290        cprintf("\n");
1291    }
1292
1293    cprintf("Non speculative list size: %i\n", nonSpecInsts.size());
1294
1295    NonSpecMapIt non_spec_it = nonSpecInsts.begin();
1296    NonSpecMapIt non_spec_end_it = nonSpecInsts.end();
1297
1298    cprintf("Non speculative list: ");
1299
1300    while (non_spec_it != non_spec_end_it) {
1301        cprintf("%s [sn:%lli]", (*non_spec_it).second->pcState(),
1302                (*non_spec_it).second->seqNum);
1303        ++non_spec_it;
1304    }
1305
1306    cprintf("\n");
1307
1308    ListOrderIt list_order_it = listOrder.begin();
1309    ListOrderIt list_order_end_it = listOrder.end();
1310    int i = 1;
1311
1312    cprintf("List order: ");
1313
1314    while (list_order_it != list_order_end_it) {
1315        cprintf("%i OpClass:%i [sn:%lli] ", i, (*list_order_it).queueType,
1316                (*list_order_it).oldestInst);
1317
1318        ++list_order_it;
1319        ++i;
1320    }
1321
1322    cprintf("\n");
1323}
1324
1325
1326template <class Impl>
1327void
1328InstructionQueue<Impl>::dumpInsts()
1329{
1330    for (ThreadID tid = 0; tid < numThreads; ++tid) {
1331        int num = 0;
1332        int valid_num = 0;
1333        ListIt inst_list_it = instList[tid].begin();
1334
1335        while (inst_list_it != instList[tid].end()) {
1336            cprintf("Instruction:%i\n", num);
1337            if (!(*inst_list_it)->isSquashed()) {
1338                if (!(*inst_list_it)->isIssued()) {
1339                    ++valid_num;
1340                    cprintf("Count:%i\n", valid_num);
1341                } else if ((*inst_list_it)->isMemRef() &&
1342                           !(*inst_list_it)->memOpDone) {
1343                    // Loads that have not been marked as executed
1344                    // still count towards the total instructions.
1345                    ++valid_num;
1346                    cprintf("Count:%i\n", valid_num);
1347                }
1348            }
1349
1350            cprintf("PC: %s\n[sn:%lli]\n[tid:%i]\n"
1351                    "Issued:%i\nSquashed:%i\n",
1352                    (*inst_list_it)->pcState(),
1353                    (*inst_list_it)->seqNum,
1354                    (*inst_list_it)->threadNumber,
1355                    (*inst_list_it)->isIssued(),
1356                    (*inst_list_it)->isSquashed());
1357
1358            if ((*inst_list_it)->isMemRef()) {
1359                cprintf("MemOpDone:%i\n", (*inst_list_it)->memOpDone);
1360            }
1361
1362            cprintf("\n");
1363
1364            inst_list_it++;
1365            ++num;
1366        }
1367    }
1368
1369    cprintf("Insts to Execute list:\n");
1370
1371    int num = 0;
1372    int valid_num = 0;
1373    ListIt inst_list_it = instsToExecute.begin();
1374
1375    while (inst_list_it != instsToExecute.end())
1376    {
1377        cprintf("Instruction:%i\n",
1378                num);
1379        if (!(*inst_list_it)->isSquashed()) {
1380            if (!(*inst_list_it)->isIssued()) {
1381                ++valid_num;
1382                cprintf("Count:%i\n", valid_num);
1383            } else if ((*inst_list_it)->isMemRef() &&
1384                       !(*inst_list_it)->memOpDone) {
1385                // Loads that have not been marked as executed
1386                // still count towards the total instructions.
1387                ++valid_num;
1388                cprintf("Count:%i\n", valid_num);
1389            }
1390        }
1391
1392        cprintf("PC: %s\n[sn:%lli]\n[tid:%i]\n"
1393                "Issued:%i\nSquashed:%i\n",
1394                (*inst_list_it)->pcState(),
1395                (*inst_list_it)->seqNum,
1396                (*inst_list_it)->threadNumber,
1397                (*inst_list_it)->isIssued(),
1398                (*inst_list_it)->isSquashed());
1399
1400        if ((*inst_list_it)->isMemRef()) {
1401            cprintf("MemOpDone:%i\n", (*inst_list_it)->memOpDone);
1402        }
1403
1404        cprintf("\n");
1405
1406        inst_list_it++;
1407        ++num;
1408    }
1409}
1410