iew_impl.hh revision 3771:808a4c19cf34 
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 */
30
31// @todo: Fix the instantaneous communication among all the stages within
32// iew.  There's a clear delay between issue and execute, yet backwards
33// communication happens simultaneously.
34
35#include <queue>
36
37#include "base/timebuf.hh"
38#include "cpu/o3/fu_pool.hh"
39#include "cpu/o3/iew.hh"
40
41template<class Impl>
42DefaultIEW<Impl>::DefaultIEW(Params *params)
43    : issueToExecQueue(params->backComSize, params->forwardComSize),
44      instQueue(params),
45      ldstQueue(params),
46      fuPool(params->fuPool),
47      commitToIEWDelay(params->commitToIEWDelay),
48      renameToIEWDelay(params->renameToIEWDelay),
49      issueToExecuteDelay(params->issueToExecuteDelay),
50      dispatchWidth(params->dispatchWidth),
51      issueWidth(params->issueWidth),
52      wbOutstanding(0),
53      wbWidth(params->wbWidth),
54      numThreads(params->numberOfThreads),
55      switchedOut(false)
56{
57    _status = Active;
58    exeStatus = Running;
59    wbStatus = Idle;
60
61    // Setup wire to read instructions coming from issue.
62    fromIssue = issueToExecQueue.getWire(-issueToExecuteDelay);
63
64    // Instruction queue needs the queue between issue and execute.
65    instQueue.setIssueToExecuteQueue(&issueToExecQueue);
66
67    instQueue.setIEW(this);
68    ldstQueue.setIEW(this);
69
70    for (int i=0; i < numThreads; i++) {
71        dispatchStatus[i] = Running;
72        stalls[i].commit = false;
73        fetchRedirect[i] = false;
74        bdelayDoneSeqNum[i] = 0;
75    }
76
77    wbMax = wbWidth * params->wbDepth;
78
79    updateLSQNextCycle = false;
80
81    ableToIssue = true;
82
83    skidBufferMax = (3 * (renameToIEWDelay * params->renameWidth)) + issueWidth;
84}
85
86template <class Impl>
87std::string
88DefaultIEW<Impl>::name() const
89{
90    return cpu->name() + ".iew";
91}
92
93template <class Impl>
94void
95DefaultIEW<Impl>::regStats()
96{
97    using namespace Stats;
98
99    instQueue.regStats();
100    ldstQueue.regStats();
101
102    iewIdleCycles
103        .name(name() + ".iewIdleCycles")
104        .desc("Number of cycles IEW is idle");
105
106    iewSquashCycles
107        .name(name() + ".iewSquashCycles")
108        .desc("Number of cycles IEW is squashing");
109
110    iewBlockCycles
111        .name(name() + ".iewBlockCycles")
112        .desc("Number of cycles IEW is blocking");
113
114    iewUnblockCycles
115        .name(name() + ".iewUnblockCycles")
116        .desc("Number of cycles IEW is unblocking");
117
118    iewDispatchedInsts
119        .name(name() + ".iewDispatchedInsts")
120        .desc("Number of instructions dispatched to IQ");
121
122    iewDispSquashedInsts
123        .name(name() + ".iewDispSquashedInsts")
124        .desc("Number of squashed instructions skipped by dispatch");
125
126    iewDispLoadInsts
127        .name(name() + ".iewDispLoadInsts")
128        .desc("Number of dispatched load instructions");
129
130    iewDispStoreInsts
131        .name(name() + ".iewDispStoreInsts")
132        .desc("Number of dispatched store instructions");
133
134    iewDispNonSpecInsts
135        .name(name() + ".iewDispNonSpecInsts")
136        .desc("Number of dispatched non-speculative instructions");
137
138    iewIQFullEvents
139        .name(name() + ".iewIQFullEvents")
140        .desc("Number of times the IQ has become full, causing a stall");
141
142    iewLSQFullEvents
143        .name(name() + ".iewLSQFullEvents")
144        .desc("Number of times the LSQ has become full, causing a stall");
145
146    memOrderViolationEvents
147        .name(name() + ".memOrderViolationEvents")
148        .desc("Number of memory order violations");
149
150    predictedTakenIncorrect
151        .name(name() + ".predictedTakenIncorrect")
152        .desc("Number of branches that were predicted taken incorrectly");
153
154    predictedNotTakenIncorrect
155        .name(name() + ".predictedNotTakenIncorrect")
156        .desc("Number of branches that were predicted not taken incorrectly");
157
158    branchMispredicts
159        .name(name() + ".branchMispredicts")
160        .desc("Number of branch mispredicts detected at execute");
161
162    branchMispredicts = predictedTakenIncorrect + predictedNotTakenIncorrect;
163
164    iewExecutedInsts
165        .name(name() + ".iewExecutedInsts")
166        .desc("Number of executed instructions");
167
168    iewExecLoadInsts
169        .init(cpu->number_of_threads)
170        .name(name() + ".iewExecLoadInsts")
171        .desc("Number of load instructions executed")
172        .flags(total);
173
174    iewExecSquashedInsts
175        .name(name() + ".iewExecSquashedInsts")
176        .desc("Number of squashed instructions skipped in execute");
177
178    iewExecutedSwp
179        .init(cpu->number_of_threads)
180        .name(name() + ".EXEC:swp")
181        .desc("number of swp insts executed")
182        .flags(total);
183
184    iewExecutedNop
185        .init(cpu->number_of_threads)
186        .name(name() + ".EXEC:nop")
187        .desc("number of nop insts executed")
188        .flags(total);
189
190    iewExecutedRefs
191        .init(cpu->number_of_threads)
192        .name(name() + ".EXEC:refs")
193        .desc("number of memory reference insts executed")
194        .flags(total);
195
196    iewExecutedBranches
197        .init(cpu->number_of_threads)
198        .name(name() + ".EXEC:branches")
199        .desc("Number of branches executed")
200        .flags(total);
201
202    iewExecStoreInsts
203        .name(name() + ".EXEC:stores")
204        .desc("Number of stores executed")
205        .flags(total);
206    iewExecStoreInsts = iewExecutedRefs - iewExecLoadInsts;
207
208    iewExecRate
209        .name(name() + ".EXEC:rate")
210        .desc("Inst execution rate")
211        .flags(total);
212
213    iewExecRate = iewExecutedInsts / cpu->numCycles;
214
215    iewInstsToCommit
216        .init(cpu->number_of_threads)
217        .name(name() + ".WB:sent")
218        .desc("cumulative count of insts sent to commit")
219        .flags(total);
220
221    writebackCount
222        .init(cpu->number_of_threads)
223        .name(name() + ".WB:count")
224        .desc("cumulative count of insts written-back")
225        .flags(total);
226
227    producerInst
228        .init(cpu->number_of_threads)
229        .name(name() + ".WB:producers")
230        .desc("num instructions producing a value")
231        .flags(total);
232
233    consumerInst
234        .init(cpu->number_of_threads)
235        .name(name() + ".WB:consumers")
236        .desc("num instructions consuming a value")
237        .flags(total);
238
239    wbPenalized
240        .init(cpu->number_of_threads)
241        .name(name() + ".WB:penalized")
242        .desc("number of instrctions required to write to 'other' IQ")
243        .flags(total);
244
245    wbPenalizedRate
246        .name(name() + ".WB:penalized_rate")
247        .desc ("fraction of instructions written-back that wrote to 'other' IQ")
248        .flags(total);
249
250    wbPenalizedRate = wbPenalized / writebackCount;
251
252    wbFanout
253        .name(name() + ".WB:fanout")
254        .desc("average fanout of values written-back")
255        .flags(total);
256
257    wbFanout = producerInst / consumerInst;
258
259    wbRate
260        .name(name() + ".WB:rate")
261        .desc("insts written-back per cycle")
262        .flags(total);
263    wbRate = writebackCount / cpu->numCycles;
264}
265
266template<class Impl>
267void
268DefaultIEW<Impl>::initStage()
269{
270    for (int tid=0; tid < numThreads; tid++) {
271        toRename->iewInfo[tid].usedIQ = true;
272        toRename->iewInfo[tid].freeIQEntries =
273            instQueue.numFreeEntries(tid);
274
275        toRename->iewInfo[tid].usedLSQ = true;
276        toRename->iewInfo[tid].freeLSQEntries =
277            ldstQueue.numFreeEntries(tid);
278    }
279}
280
281template<class Impl>
282void
283DefaultIEW<Impl>::setCPU(O3CPU *cpu_ptr)
284{
285    DPRINTF(IEW, "Setting CPU pointer.\n");
286    cpu = cpu_ptr;
287
288    instQueue.setCPU(cpu_ptr);
289    ldstQueue.setCPU(cpu_ptr);
290
291    cpu->activateStage(O3CPU::IEWIdx);
292}
293
294template<class Impl>
295void
296DefaultIEW<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr)
297{
298    DPRINTF(IEW, "Setting time buffer pointer.\n");
299    timeBuffer = tb_ptr;
300
301    // Setup wire to read information from time buffer, from commit.
302    fromCommit = timeBuffer->getWire(-commitToIEWDelay);
303
304    // Setup wire to write information back to previous stages.
305    toRename = timeBuffer->getWire(0);
306
307    toFetch = timeBuffer->getWire(0);
308
309    // Instruction queue also needs main time buffer.
310    instQueue.setTimeBuffer(tb_ptr);
311}
312
313template<class Impl>
314void
315DefaultIEW<Impl>::setRenameQueue(TimeBuffer<RenameStruct> *rq_ptr)
316{
317    DPRINTF(IEW, "Setting rename queue pointer.\n");
318    renameQueue = rq_ptr;
319
320    // Setup wire to read information from rename queue.
321    fromRename = renameQueue->getWire(-renameToIEWDelay);
322}
323
324template<class Impl>
325void
326DefaultIEW<Impl>::setIEWQueue(TimeBuffer<IEWStruct> *iq_ptr)
327{
328    DPRINTF(IEW, "Setting IEW queue pointer.\n");
329    iewQueue = iq_ptr;
330
331    // Setup wire to write instructions to commit.
332    toCommit = iewQueue->getWire(0);
333}
334
335template<class Impl>
336void
337DefaultIEW<Impl>::setActiveThreads(std::list<unsigned> *at_ptr)
338{
339    DPRINTF(IEW, "Setting active threads list pointer.\n");
340    activeThreads = at_ptr;
341
342    ldstQueue.setActiveThreads(at_ptr);
343    instQueue.setActiveThreads(at_ptr);
344}
345
346template<class Impl>
347void
348DefaultIEW<Impl>::setScoreboard(Scoreboard *sb_ptr)
349{
350    DPRINTF(IEW, "Setting scoreboard pointer.\n");
351    scoreboard = sb_ptr;
352}
353
354template <class Impl>
355bool
356DefaultIEW<Impl>::drain()
357{
358    // IEW is ready to drain at any time.
359    cpu->signalDrained();
360    return true;
361}
362
363template <class Impl>
364void
365DefaultIEW<Impl>::resume()
366{
367}
368
369template <class Impl>
370void
371DefaultIEW<Impl>::switchOut()
372{
373    // Clear any state.
374    switchedOut = true;
375    assert(insts[0].empty());
376    assert(skidBuffer[0].empty());
377
378    instQueue.switchOut();
379    ldstQueue.switchOut();
380    fuPool->switchOut();
381
382    for (int i = 0; i < numThreads; i++) {
383        while (!insts[i].empty())
384            insts[i].pop();
385        while (!skidBuffer[i].empty())
386            skidBuffer[i].pop();
387    }
388}
389
390template <class Impl>
391void
392DefaultIEW<Impl>::takeOverFrom()
393{
394    // Reset all state.
395    _status = Active;
396    exeStatus = Running;
397    wbStatus = Idle;
398    switchedOut = false;
399
400    instQueue.takeOverFrom();
401    ldstQueue.takeOverFrom();
402    fuPool->takeOverFrom();
403
404    initStage();
405    cpu->activityThisCycle();
406
407    for (int i=0; i < numThreads; i++) {
408        dispatchStatus[i] = Running;
409        stalls[i].commit = false;
410        fetchRedirect[i] = false;
411    }
412
413    updateLSQNextCycle = false;
414
415    for (int i = 0; i < issueToExecQueue.getSize(); ++i) {
416        issueToExecQueue.advance();
417    }
418}
419
420template<class Impl>
421void
422DefaultIEW<Impl>::squash(unsigned tid)
423{
424    DPRINTF(IEW, "[tid:%i]: Squashing all instructions.\n",
425            tid);
426
427    // Tell the IQ to start squashing.
428    instQueue.squash(tid);
429
430    // Tell the LDSTQ to start squashing.
431#if ISA_HAS_DELAY_SLOT
432    ldstQueue.squash(fromCommit->commitInfo[tid].bdelayDoneSeqNum, tid);
433#else
434    ldstQueue.squash(fromCommit->commitInfo[tid].doneSeqNum, tid);
435#endif
436    updatedQueues = true;
437
438    // Clear the skid buffer in case it has any data in it.
439    DPRINTF(IEW, "[tid:%i]: Removing skidbuffer instructions until [sn:%i].\n",
440            tid, fromCommit->commitInfo[tid].bdelayDoneSeqNum);
441
442    while (!skidBuffer[tid].empty()) {
443#if ISA_HAS_DELAY_SLOT
444        if (skidBuffer[tid].front()->seqNum <=
445            fromCommit->commitInfo[tid].bdelayDoneSeqNum) {
446            DPRINTF(IEW, "[tid:%i]: Cannot remove skidbuffer instructions "
447                    "that occur before delay slot [sn:%i].\n",
448                    fromCommit->commitInfo[tid].bdelayDoneSeqNum,
449                    tid);
450            break;
451        } else {
452            DPRINTF(IEW, "[tid:%i]: Removing instruction [sn:%i] from "
453                    "skidBuffer.\n", tid, skidBuffer[tid].front()->seqNum);
454        }
455#endif
456        if (skidBuffer[tid].front()->isLoad() ||
457            skidBuffer[tid].front()->isStore() ) {
458            toRename->iewInfo[tid].dispatchedToLSQ++;
459        }
460
461        toRename->iewInfo[tid].dispatched++;
462
463        skidBuffer[tid].pop();
464    }
465
466    bdelayDoneSeqNum[tid] = fromCommit->commitInfo[tid].bdelayDoneSeqNum;
467
468    emptyRenameInsts(tid);
469}
470
471template<class Impl>
472void
473DefaultIEW<Impl>::squashDueToBranch(DynInstPtr &inst, unsigned tid)
474{
475    DPRINTF(IEW, "[tid:%i]: Squashing from a specific instruction, PC: %#x "
476            "[sn:%i].\n", tid, inst->readPC(), inst->seqNum);
477
478    toCommit->squash[tid] = true;
479    toCommit->squashedSeqNum[tid] = inst->seqNum;
480    toCommit->mispredPC[tid] = inst->readPC();
481    toCommit->branchMispredict[tid] = true;
482
483#if ISA_HAS_DELAY_SLOT
484    bool branch_taken =
485        (inst->readNextNPC() != (inst->readPC() + 2 * sizeof(TheISA::MachInst)) &&
486         inst->readNextNPC() != (inst->readPC() + 3 * sizeof(TheISA::MachInst)));
487    DPRINTF(Sparc, "Branch taken = %s [sn:%i]\n",
488            branch_taken ? "true": "false", inst->seqNum);
489
490    toCommit->branchTaken[tid] = branch_taken;
491
492    bool squashDelaySlot =
493        (inst->readNextPC() != inst->readPC() + sizeof(TheISA::MachInst));
494    DPRINTF(Sparc, "Squash delay slot = %s [sn:%i]\n",
495            squashDelaySlot ? "true": "false", inst->seqNum);
496    toCommit->squashDelaySlot[tid] = squashDelaySlot;
497    //If we're squashing the delay slot, we need to pick back up at NextPC.
498    //Otherwise, NextPC isn't being squashed, so we should pick back up at
499    //NextNPC.
500    if (squashDelaySlot)
501        toCommit->nextPC[tid] = inst->readNextPC();
502    else
503        toCommit->nextPC[tid] = inst->readNextNPC();
504#else
505    toCommit->branchTaken[tid] = inst->readNextPC() !=
506        (inst->readPC() + sizeof(TheISA::MachInst));
507    toCommit->nextPC[tid] = inst->readNextPC();
508#endif
509
510    toCommit->includeSquashInst[tid] = false;
511
512    wroteToTimeBuffer = true;
513}
514
515template<class Impl>
516void
517DefaultIEW<Impl>::squashDueToMemOrder(DynInstPtr &inst, unsigned tid)
518{
519    DPRINTF(IEW, "[tid:%i]: Squashing from a specific instruction, "
520            "PC: %#x [sn:%i].\n", tid, inst->readPC(), inst->seqNum);
521
522    toCommit->squash[tid] = true;
523    toCommit->squashedSeqNum[tid] = inst->seqNum;
524    toCommit->nextPC[tid] = inst->readNextPC();
525
526    toCommit->includeSquashInst[tid] = false;
527
528    wroteToTimeBuffer = true;
529}
530
531template<class Impl>
532void
533DefaultIEW<Impl>::squashDueToMemBlocked(DynInstPtr &inst, unsigned tid)
534{
535    DPRINTF(IEW, "[tid:%i]: Memory blocked, squashing load and younger insts, "
536            "PC: %#x [sn:%i].\n", tid, inst->readPC(), inst->seqNum);
537
538    toCommit->squash[tid] = true;
539    toCommit->squashedSeqNum[tid] = inst->seqNum;
540    toCommit->nextPC[tid] = inst->readPC();
541
542    // Must include the broadcasted SN in the squash.
543    toCommit->includeSquashInst[tid] = true;
544
545    ldstQueue.setLoadBlockedHandled(tid);
546
547    wroteToTimeBuffer = true;
548}
549
550template<class Impl>
551void
552DefaultIEW<Impl>::block(unsigned tid)
553{
554    DPRINTF(IEW, "[tid:%u]: Blocking.\n", tid);
555
556    if (dispatchStatus[tid] != Blocked &&
557        dispatchStatus[tid] != Unblocking) {
558        toRename->iewBlock[tid] = true;
559        wroteToTimeBuffer = true;
560    }
561
562    // Add the current inputs to the skid buffer so they can be
563    // reprocessed when this stage unblocks.
564    skidInsert(tid);
565
566    dispatchStatus[tid] = Blocked;
567}
568
569template<class Impl>
570void
571DefaultIEW<Impl>::unblock(unsigned tid)
572{
573    DPRINTF(IEW, "[tid:%i]: Reading instructions out of the skid "
574            "buffer %u.\n",tid, tid);
575
576    // If the skid bufffer is empty, signal back to previous stages to unblock.
577    // Also switch status to running.
578    if (skidBuffer[tid].empty()) {
579        toRename->iewUnblock[tid] = true;
580        wroteToTimeBuffer = true;
581        DPRINTF(IEW, "[tid:%i]: Done unblocking.\n",tid);
582        dispatchStatus[tid] = Running;
583    }
584}
585
586template<class Impl>
587void
588DefaultIEW<Impl>::wakeDependents(DynInstPtr &inst)
589{
590    instQueue.wakeDependents(inst);
591}
592
593template<class Impl>
594void
595DefaultIEW<Impl>::rescheduleMemInst(DynInstPtr &inst)
596{
597    instQueue.rescheduleMemInst(inst);
598}
599
600template<class Impl>
601void
602DefaultIEW<Impl>::replayMemInst(DynInstPtr &inst)
603{
604    instQueue.replayMemInst(inst);
605}
606
607template<class Impl>
608void
609DefaultIEW<Impl>::instToCommit(DynInstPtr &inst)
610{
611    // This function should not be called after writebackInsts in a
612    // single cycle.  That will cause problems with an instruction
613    // being added to the queue to commit without being processed by
614    // writebackInsts prior to being sent to commit.
615
616    // First check the time slot that this instruction will write
617    // to.  If there are free write ports at the time, then go ahead
618    // and write the instruction to that time.  If there are not,
619    // keep looking back to see where's the first time there's a
620    // free slot.
621    while ((*iewQueue)[wbCycle].insts[wbNumInst]) {
622        ++wbNumInst;
623        if (wbNumInst == wbWidth) {
624            ++wbCycle;
625            wbNumInst = 0;
626        }
627
628        assert((wbCycle * wbWidth + wbNumInst) <= wbMax);
629    }
630
631    DPRINTF(IEW, "Current wb cycle: %i, width: %i, numInst: %i\nwbActual:%i\n",
632            wbCycle, wbWidth, wbNumInst, wbCycle * wbWidth + wbNumInst);
633    // Add finished instruction to queue to commit.
634    (*iewQueue)[wbCycle].insts[wbNumInst] = inst;
635    (*iewQueue)[wbCycle].size++;
636}
637
638template <class Impl>
639unsigned
640DefaultIEW<Impl>::validInstsFromRename()
641{
642    unsigned inst_count = 0;
643
644    for (int i=0; i<fromRename->size; i++) {
645        if (!fromRename->insts[i]->isSquashed())
646            inst_count++;
647    }
648
649    return inst_count;
650}
651
652template<class Impl>
653void
654DefaultIEW<Impl>::skidInsert(unsigned tid)
655{
656    DynInstPtr inst = NULL;
657
658    while (!insts[tid].empty()) {
659        inst = insts[tid].front();
660
661        insts[tid].pop();
662
663        DPRINTF(Decode,"[tid:%i]: Inserting [sn:%lli] PC:%#x into "
664                "dispatch skidBuffer %i\n",tid, inst->seqNum,
665                inst->readPC(),tid);
666
667        skidBuffer[tid].push(inst);
668    }
669
670    assert(skidBuffer[tid].size() <= skidBufferMax &&
671           "Skidbuffer Exceeded Max Size");
672}
673
674template<class Impl>
675int
676DefaultIEW<Impl>::skidCount()
677{
678    int max=0;
679
680    std::list<unsigned>::iterator threads = (*activeThreads).begin();
681
682    while (threads != (*activeThreads).end()) {
683        unsigned thread_count = skidBuffer[*threads++].size();
684        if (max < thread_count)
685            max = thread_count;
686    }
687
688    return max;
689}
690
691template<class Impl>
692bool
693DefaultIEW<Impl>::skidsEmpty()
694{
695    std::list<unsigned>::iterator threads = (*activeThreads).begin();
696
697    while (threads != (*activeThreads).end()) {
698        if (!skidBuffer[*threads++].empty())
699            return false;
700    }
701
702    return true;
703}
704
705template <class Impl>
706void
707DefaultIEW<Impl>::updateStatus()
708{
709    bool any_unblocking = false;
710
711    std::list<unsigned>::iterator threads = (*activeThreads).begin();
712
713    threads = (*activeThreads).begin();
714
715    while (threads != (*activeThreads).end()) {
716        unsigned tid = *threads++;
717
718        if (dispatchStatus[tid] == Unblocking) {
719            any_unblocking = true;
720            break;
721        }
722    }
723
724    // If there are no ready instructions waiting to be scheduled by the IQ,
725    // and there's no stores waiting to write back, and dispatch is not
726    // unblocking, then there is no internal activity for the IEW stage.
727    if (_status == Active && !instQueue.hasReadyInsts() &&
728        !ldstQueue.willWB() && !any_unblocking) {
729        DPRINTF(IEW, "IEW switching to idle\n");
730
731        deactivateStage();
732
733        _status = Inactive;
734    } else if (_status == Inactive && (instQueue.hasReadyInsts() ||
735                                       ldstQueue.willWB() ||
736                                       any_unblocking)) {
737        // Otherwise there is internal activity.  Set to active.
738        DPRINTF(IEW, "IEW switching to active\n");
739
740        activateStage();
741
742        _status = Active;
743    }
744}
745
746template <class Impl>
747void
748DefaultIEW<Impl>::resetEntries()
749{
750    instQueue.resetEntries();
751    ldstQueue.resetEntries();
752}
753
754template <class Impl>
755void
756DefaultIEW<Impl>::readStallSignals(unsigned tid)
757{
758    if (fromCommit->commitBlock[tid]) {
759        stalls[tid].commit = true;
760    }
761
762    if (fromCommit->commitUnblock[tid]) {
763        assert(stalls[tid].commit);
764        stalls[tid].commit = false;
765    }
766}
767
768template <class Impl>
769bool
770DefaultIEW<Impl>::checkStall(unsigned tid)
771{
772    bool ret_val(false);
773
774    if (stalls[tid].commit) {
775        DPRINTF(IEW,"[tid:%i]: Stall from Commit stage detected.\n",tid);
776        ret_val = true;
777    } else if (instQueue.isFull(tid)) {
778        DPRINTF(IEW,"[tid:%i]: Stall: IQ  is full.\n",tid);
779        ret_val = true;
780    } else if (ldstQueue.isFull(tid)) {
781        DPRINTF(IEW,"[tid:%i]: Stall: LSQ is full\n",tid);
782
783        if (ldstQueue.numLoads(tid) > 0 ) {
784
785            DPRINTF(IEW,"[tid:%i]: LSQ oldest load: [sn:%i] \n",
786                    tid,ldstQueue.getLoadHeadSeqNum(tid));
787        }
788
789        if (ldstQueue.numStores(tid) > 0) {
790
791            DPRINTF(IEW,"[tid:%i]: LSQ oldest store: [sn:%i] \n",
792                    tid,ldstQueue.getStoreHeadSeqNum(tid));
793        }
794
795        ret_val = true;
796    } else if (ldstQueue.isStalled(tid)) {
797        DPRINTF(IEW,"[tid:%i]: Stall: LSQ stall detected.\n",tid);
798        ret_val = true;
799    }
800
801    return ret_val;
802}
803
804template <class Impl>
805void
806DefaultIEW<Impl>::checkSignalsAndUpdate(unsigned tid)
807{
808    // Check if there's a squash signal, squash if there is
809    // Check stall signals, block if there is.
810    // If status was Blocked
811    //     if so then go to unblocking
812    // If status was Squashing
813    //     check if squashing is not high.  Switch to running this cycle.
814
815    readStallSignals(tid);
816
817    if (fromCommit->commitInfo[tid].squash) {
818        squash(tid);
819
820        if (dispatchStatus[tid] == Blocked ||
821            dispatchStatus[tid] == Unblocking) {
822            toRename->iewUnblock[tid] = true;
823            wroteToTimeBuffer = true;
824        }
825
826        dispatchStatus[tid] = Squashing;
827
828        fetchRedirect[tid] = false;
829        return;
830    }
831
832    if (fromCommit->commitInfo[tid].robSquashing) {
833        DPRINTF(IEW, "[tid:%i]: ROB is still squashing.\n", tid);
834
835        dispatchStatus[tid] = Squashing;
836
837        emptyRenameInsts(tid);
838        wroteToTimeBuffer = true;
839        return;
840    }
841
842    if (checkStall(tid)) {
843        block(tid);
844        dispatchStatus[tid] = Blocked;
845        return;
846    }
847
848    if (dispatchStatus[tid] == Blocked) {
849        // Status from previous cycle was blocked, but there are no more stall
850        // conditions.  Switch over to unblocking.
851        DPRINTF(IEW, "[tid:%i]: Done blocking, switching to unblocking.\n",
852                tid);
853
854        dispatchStatus[tid] = Unblocking;
855
856        unblock(tid);
857
858        return;
859    }
860
861    if (dispatchStatus[tid] == Squashing) {
862        // Switch status to running if rename isn't being told to block or
863        // squash this cycle.
864        DPRINTF(IEW, "[tid:%i]: Done squashing, switching to running.\n",
865                tid);
866
867        dispatchStatus[tid] = Running;
868
869        return;
870    }
871}
872
873template <class Impl>
874void
875DefaultIEW<Impl>::sortInsts()
876{
877    int insts_from_rename = fromRename->size;
878#ifdef DEBUG
879#if !ISA_HAS_DELAY_SLOT
880    for (int i = 0; i < numThreads; i++)
881        assert(insts[i].empty());
882#endif
883#endif
884    for (int i = 0; i < insts_from_rename; ++i) {
885        insts[fromRename->insts[i]->threadNumber].push(fromRename->insts[i]);
886    }
887}
888
889template <class Impl>
890void
891DefaultIEW<Impl>::emptyRenameInsts(unsigned tid)
892{
893    DPRINTF(IEW, "[tid:%i]: Removing incoming rename instructions until "
894            "[sn:%i].\n", tid, bdelayDoneSeqNum[tid]);
895
896    while (!insts[tid].empty()) {
897#if ISA_HAS_DELAY_SLOT
898        if (insts[tid].front()->seqNum <= bdelayDoneSeqNum[tid]) {
899            DPRINTF(IEW, "[tid:%i]: Done removing, cannot remove instruction"
900                    " that occurs at or before delay slot [sn:%i].\n",
901                    tid, bdelayDoneSeqNum[tid]);
902            break;
903        } else {
904            DPRINTF(IEW, "[tid:%i]: Removing incoming rename instruction "
905                    "[sn:%i].\n", tid, insts[tid].front()->seqNum);
906        }
907#endif
908
909        if (insts[tid].front()->isLoad() ||
910            insts[tid].front()->isStore() ) {
911            toRename->iewInfo[tid].dispatchedToLSQ++;
912        }
913
914        toRename->iewInfo[tid].dispatched++;
915
916        insts[tid].pop();
917    }
918}
919
920template <class Impl>
921void
922DefaultIEW<Impl>::wakeCPU()
923{
924    cpu->wakeCPU();
925}
926
927template <class Impl>
928void
929DefaultIEW<Impl>::activityThisCycle()
930{
931    DPRINTF(Activity, "Activity this cycle.\n");
932    cpu->activityThisCycle();
933}
934
935template <class Impl>
936inline void
937DefaultIEW<Impl>::activateStage()
938{
939    DPRINTF(Activity, "Activating stage.\n");
940    cpu->activateStage(O3CPU::IEWIdx);
941}
942
943template <class Impl>
944inline void
945DefaultIEW<Impl>::deactivateStage()
946{
947    DPRINTF(Activity, "Deactivating stage.\n");
948    cpu->deactivateStage(O3CPU::IEWIdx);
949}
950
951template<class Impl>
952void
953DefaultIEW<Impl>::dispatch(unsigned tid)
954{
955    // If status is Running or idle,
956    //     call dispatchInsts()
957    // If status is Unblocking,
958    //     buffer any instructions coming from rename
959    //     continue trying to empty skid buffer
960    //     check if stall conditions have passed
961
962    if (dispatchStatus[tid] == Blocked) {
963        ++iewBlockCycles;
964
965    } else if (dispatchStatus[tid] == Squashing) {
966        ++iewSquashCycles;
967    }
968
969    // Dispatch should try to dispatch as many instructions as its bandwidth
970    // will allow, as long as it is not currently blocked.
971    if (dispatchStatus[tid] == Running ||
972        dispatchStatus[tid] == Idle) {
973        DPRINTF(IEW, "[tid:%i] Not blocked, so attempting to run "
974                "dispatch.\n", tid);
975
976        dispatchInsts(tid);
977    } else if (dispatchStatus[tid] == Unblocking) {
978        // Make sure that the skid buffer has something in it if the
979        // status is unblocking.
980        assert(!skidsEmpty());
981
982        // If the status was unblocking, then instructions from the skid
983        // buffer were used.  Remove those instructions and handle
984        // the rest of unblocking.
985        dispatchInsts(tid);
986
987        ++iewUnblockCycles;
988
989        if (validInstsFromRename() && dispatchedAllInsts) {
990            // Add the current inputs to the skid buffer so they can be
991            // reprocessed when this stage unblocks.
992            skidInsert(tid);
993        }
994
995        unblock(tid);
996    }
997}
998
999template <class Impl>
1000void
1001DefaultIEW<Impl>::dispatchInsts(unsigned tid)
1002{
1003    dispatchedAllInsts = true;
1004
1005    // Obtain instructions from skid buffer if unblocking, or queue from rename
1006    // otherwise.
1007    std::queue<DynInstPtr> &insts_to_dispatch =
1008        dispatchStatus[tid] == Unblocking ?
1009        skidBuffer[tid] : insts[tid];
1010
1011    int insts_to_add = insts_to_dispatch.size();
1012
1013    DynInstPtr inst;
1014    bool add_to_iq = false;
1015    int dis_num_inst = 0;
1016
1017    // Loop through the instructions, putting them in the instruction
1018    // queue.
1019    for ( ; dis_num_inst < insts_to_add &&
1020              dis_num_inst < dispatchWidth;
1021          ++dis_num_inst)
1022    {
1023        inst = insts_to_dispatch.front();
1024
1025        if (dispatchStatus[tid] == Unblocking) {
1026            DPRINTF(IEW, "[tid:%i]: Issue: Examining instruction from skid "
1027                    "buffer\n", tid);
1028        }
1029
1030        // Make sure there's a valid instruction there.
1031        assert(inst);
1032
1033        DPRINTF(IEW, "[tid:%i]: Issue: Adding PC %#x [sn:%lli] [tid:%i] to "
1034                "IQ.\n",
1035                tid, inst->readPC(), inst->seqNum, inst->threadNumber);
1036
1037        // Be sure to mark these instructions as ready so that the
1038        // commit stage can go ahead and execute them, and mark
1039        // them as issued so the IQ doesn't reprocess them.
1040
1041        // Check for squashed instructions.
1042        if (inst->isSquashed()) {
1043            DPRINTF(IEW, "[tid:%i]: Issue: Squashed instruction encountered, "
1044                    "not adding to IQ.\n", tid);
1045
1046            ++iewDispSquashedInsts;
1047
1048            insts_to_dispatch.pop();
1049
1050            //Tell Rename That An Instruction has been processed
1051            if (inst->isLoad() || inst->isStore()) {
1052                toRename->iewInfo[tid].dispatchedToLSQ++;
1053            }
1054            toRename->iewInfo[tid].dispatched++;
1055
1056            continue;
1057        }
1058
1059        // Check for full conditions.
1060        if (instQueue.isFull(tid)) {
1061            DPRINTF(IEW, "[tid:%i]: Issue: IQ has become full.\n", tid);
1062
1063            // Call function to start blocking.
1064            block(tid);
1065
1066            // Set unblock to false. Special case where we are using
1067            // skidbuffer (unblocking) instructions but then we still
1068            // get full in the IQ.
1069            toRename->iewUnblock[tid] = false;
1070
1071            dispatchedAllInsts = false;
1072
1073            ++iewIQFullEvents;
1074            break;
1075        } else if (ldstQueue.isFull(tid)) {
1076            DPRINTF(IEW, "[tid:%i]: Issue: LSQ has become full.\n",tid);
1077
1078            // Call function to start blocking.
1079            block(tid);
1080
1081            // Set unblock to false. Special case where we are using
1082            // skidbuffer (unblocking) instructions but then we still
1083            // get full in the IQ.
1084            toRename->iewUnblock[tid] = false;
1085
1086            dispatchedAllInsts = false;
1087
1088            ++iewLSQFullEvents;
1089            break;
1090        }
1091
1092        // Otherwise issue the instruction just fine.
1093        if (inst->isLoad()) {
1094            DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1095                    "encountered, adding to LSQ.\n", tid);
1096
1097            // Reserve a spot in the load store queue for this
1098            // memory access.
1099            ldstQueue.insertLoad(inst);
1100
1101            ++iewDispLoadInsts;
1102
1103            add_to_iq = true;
1104
1105            toRename->iewInfo[tid].dispatchedToLSQ++;
1106        } else if (inst->isStore()) {
1107            DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1108                    "encountered, adding to LSQ.\n", tid);
1109
1110            ldstQueue.insertStore(inst);
1111
1112            ++iewDispStoreInsts;
1113
1114            if (inst->isStoreConditional()) {
1115                // Store conditionals need to be set as "canCommit()"
1116                // so that commit can process them when they reach the
1117                // head of commit.
1118                // @todo: This is somewhat specific to Alpha.
1119                inst->setCanCommit();
1120                instQueue.insertNonSpec(inst);
1121                add_to_iq = false;
1122
1123                ++iewDispNonSpecInsts;
1124            } else {
1125                add_to_iq = true;
1126            }
1127
1128            toRename->iewInfo[tid].dispatchedToLSQ++;
1129#if FULL_SYSTEM
1130        } else if (inst->isMemBarrier() || inst->isWriteBarrier()) {
1131            // Same as non-speculative stores.
1132            inst->setCanCommit();
1133            instQueue.insertBarrier(inst);
1134            add_to_iq = false;
1135#endif
1136        } else if (inst->isNonSpeculative()) {
1137            DPRINTF(IEW, "[tid:%i]: Issue: Nonspeculative instruction "
1138                    "encountered, skipping.\n", tid);
1139
1140            // Same as non-speculative stores.
1141            inst->setCanCommit();
1142
1143            // Specifically insert it as nonspeculative.
1144            instQueue.insertNonSpec(inst);
1145
1146            ++iewDispNonSpecInsts;
1147
1148            add_to_iq = false;
1149        } else if (inst->isNop()) {
1150            DPRINTF(IEW, "[tid:%i]: Issue: Nop instruction encountered, "
1151                    "skipping.\n", tid);
1152
1153            inst->setIssued();
1154            inst->setExecuted();
1155            inst->setCanCommit();
1156
1157            instQueue.recordProducer(inst);
1158
1159            iewExecutedNop[tid]++;
1160
1161            add_to_iq = false;
1162        } else if (inst->isExecuted()) {
1163            assert(0 && "Instruction shouldn't be executed.\n");
1164            DPRINTF(IEW, "Issue: Executed branch encountered, "
1165                    "skipping.\n");
1166
1167            inst->setIssued();
1168            inst->setCanCommit();
1169
1170            instQueue.recordProducer(inst);
1171
1172            add_to_iq = false;
1173        } else {
1174            add_to_iq = true;
1175        }
1176
1177        // If the instruction queue is not full, then add the
1178        // instruction.
1179        if (add_to_iq) {
1180            instQueue.insert(inst);
1181        }
1182
1183        insts_to_dispatch.pop();
1184
1185        toRename->iewInfo[tid].dispatched++;
1186
1187        ++iewDispatchedInsts;
1188    }
1189
1190    if (!insts_to_dispatch.empty()) {
1191        DPRINTF(IEW,"[tid:%i]: Issue: Bandwidth Full. Blocking.\n", tid);
1192        block(tid);
1193        toRename->iewUnblock[tid] = false;
1194    }
1195
1196    if (dispatchStatus[tid] == Idle && dis_num_inst) {
1197        dispatchStatus[tid] = Running;
1198
1199        updatedQueues = true;
1200    }
1201
1202    dis_num_inst = 0;
1203}
1204
1205template <class Impl>
1206void
1207DefaultIEW<Impl>::printAvailableInsts()
1208{
1209    int inst = 0;
1210
1211    std::cout << "Available Instructions: ";
1212
1213    while (fromIssue->insts[inst]) {
1214
1215        if (inst%3==0) std::cout << "\n\t";
1216
1217        std::cout << "PC: " << fromIssue->insts[inst]->readPC()
1218             << " TN: " << fromIssue->insts[inst]->threadNumber
1219             << " SN: " << fromIssue->insts[inst]->seqNum << " | ";
1220
1221        inst++;
1222
1223    }
1224
1225    std::cout << "\n";
1226}
1227
1228template <class Impl>
1229void
1230DefaultIEW<Impl>::executeInsts()
1231{
1232    wbNumInst = 0;
1233    wbCycle = 0;
1234
1235    std::list<unsigned>::iterator threads = (*activeThreads).begin();
1236
1237    while (threads != (*activeThreads).end()) {
1238        unsigned tid = *threads++;
1239        fetchRedirect[tid] = false;
1240    }
1241
1242    // Uncomment this if you want to see all available instructions.
1243//    printAvailableInsts();
1244
1245    // Execute/writeback any instructions that are available.
1246    int insts_to_execute = fromIssue->size;
1247    int inst_num = 0;
1248    for (; inst_num < insts_to_execute;
1249          ++inst_num) {
1250
1251        DPRINTF(IEW, "Execute: Executing instructions from IQ.\n");
1252
1253        DynInstPtr inst = instQueue.getInstToExecute();
1254
1255        DPRINTF(IEW, "Execute: Processing PC %#x, [tid:%i] [sn:%i].\n",
1256                inst->readPC(), inst->threadNumber,inst->seqNum);
1257
1258        // Check if the instruction is squashed; if so then skip it
1259        if (inst->isSquashed()) {
1260            DPRINTF(IEW, "Execute: Instruction was squashed.\n");
1261
1262            // Consider this instruction executed so that commit can go
1263            // ahead and retire the instruction.
1264            inst->setExecuted();
1265
1266            // Not sure if I should set this here or just let commit try to
1267            // commit any squashed instructions.  I like the latter a bit more.
1268            inst->setCanCommit();
1269
1270            ++iewExecSquashedInsts;
1271
1272            decrWb(inst->seqNum);
1273            continue;
1274        }
1275
1276        Fault fault = NoFault;
1277
1278        // Execute instruction.
1279        // Note that if the instruction faults, it will be handled
1280        // at the commit stage.
1281        if (inst->isMemRef() &&
1282            (!inst->isDataPrefetch() && !inst->isInstPrefetch())) {
1283            DPRINTF(IEW, "Execute: Calculating address for memory "
1284                    "reference.\n");
1285
1286            // Tell the LDSTQ to execute this instruction (if it is a load).
1287            if (inst->isLoad()) {
1288                // Loads will mark themselves as executed, and their writeback
1289                // event adds the instruction to the queue to commit
1290                fault = ldstQueue.executeLoad(inst);
1291            } else if (inst->isStore()) {
1292                fault = ldstQueue.executeStore(inst);
1293
1294                // If the store had a fault then it may not have a mem req
1295                if (!inst->isStoreConditional() && fault == NoFault) {
1296                    inst->setExecuted();
1297
1298                    instToCommit(inst);
1299                } else if (fault != NoFault) {
1300                    // If the instruction faulted, then we need to send it along to commit
1301                    // without the instruction completing.
1302                    DPRINTF(IEW, "Store has fault! [sn:%lli]\n", inst->seqNum);
1303
1304                    // Send this instruction to commit, also make sure iew stage
1305                    // realizes there is activity.
1306                    inst->setExecuted();
1307
1308                    instToCommit(inst);
1309                    activityThisCycle();
1310                }
1311
1312                // Store conditionals will mark themselves as
1313                // executed, and their writeback event will add the
1314                // instruction to the queue to commit.
1315            } else {
1316                panic("Unexpected memory type!\n");
1317            }
1318
1319        } else {
1320            inst->execute();
1321
1322            inst->setExecuted();
1323
1324            instToCommit(inst);
1325        }
1326
1327        updateExeInstStats(inst);
1328
1329        // Check if branch prediction was correct, if not then we need
1330        // to tell commit to squash in flight instructions.  Only
1331        // handle this if there hasn't already been something that
1332        // redirects fetch in this group of instructions.
1333
1334        // This probably needs to prioritize the redirects if a different
1335        // scheduler is used.  Currently the scheduler schedules the oldest
1336        // instruction first, so the branch resolution order will be correct.
1337        unsigned tid = inst->threadNumber;
1338
1339        if (!fetchRedirect[tid]) {
1340
1341            if (inst->mispredicted()) {
1342                fetchRedirect[tid] = true;
1343
1344                DPRINTF(IEW, "Execute: Branch mispredict detected.\n");
1345#if ISA_HAS_DELAY_SLOT
1346                DPRINTF(IEW, "Execute: Redirecting fetch to PC: %#x.\n",
1347                        inst->nextNPC);
1348#else
1349                DPRINTF(IEW, "Execute: Redirecting fetch to PC: %#x.\n",
1350                        inst->nextPC);
1351#endif
1352                // If incorrect, then signal the ROB that it must be squashed.
1353                squashDueToBranch(inst, tid);
1354
1355                if (inst->predTaken()) {
1356                    predictedTakenIncorrect++;
1357                } else {
1358                    predictedNotTakenIncorrect++;
1359                }
1360            } else if (ldstQueue.violation(tid)) {
1361                fetchRedirect[tid] = true;
1362
1363                // If there was an ordering violation, then get the
1364                // DynInst that caused the violation.  Note that this
1365                // clears the violation signal.
1366                DynInstPtr violator;
1367                violator = ldstQueue.getMemDepViolator(tid);
1368
1369                DPRINTF(IEW, "LDSTQ detected a violation.  Violator PC: "
1370                        "%#x, inst PC: %#x.  Addr is: %#x.\n",
1371                        violator->readPC(), inst->readPC(), inst->physEffAddr);
1372
1373                // Tell the instruction queue that a violation has occured.
1374                instQueue.violation(inst, violator);
1375
1376                // Squash.
1377                squashDueToMemOrder(inst,tid);
1378
1379                ++memOrderViolationEvents;
1380            } else if (ldstQueue.loadBlocked(tid) &&
1381                       !ldstQueue.isLoadBlockedHandled(tid)) {
1382                fetchRedirect[tid] = true;
1383
1384                DPRINTF(IEW, "Load operation couldn't execute because the "
1385                        "memory system is blocked.  PC: %#x [sn:%lli]\n",
1386                        inst->readPC(), inst->seqNum);
1387
1388                squashDueToMemBlocked(inst, tid);
1389            }
1390        }
1391    }
1392
1393    // Update and record activity if we processed any instructions.
1394    if (inst_num) {
1395        if (exeStatus == Idle) {
1396            exeStatus = Running;
1397        }
1398
1399        updatedQueues = true;
1400
1401        cpu->activityThisCycle();
1402    }
1403
1404    // Need to reset this in case a writeback event needs to write into the
1405    // iew queue.  That way the writeback event will write into the correct
1406    // spot in the queue.
1407    wbNumInst = 0;
1408}
1409
1410template <class Impl>
1411void
1412DefaultIEW<Impl>::writebackInsts()
1413{
1414    // Loop through the head of the time buffer and wake any
1415    // dependents.  These instructions are about to write back.  Also
1416    // mark scoreboard that this instruction is finally complete.
1417    // Either have IEW have direct access to scoreboard, or have this
1418    // as part of backwards communication.
1419    for (int inst_num = 0; inst_num < issueWidth &&
1420             toCommit->insts[inst_num]; inst_num++) {
1421        DynInstPtr inst = toCommit->insts[inst_num];
1422        int tid = inst->threadNumber;
1423
1424        DPRINTF(IEW, "Sending instructions to commit, [sn:%lli] PC %#x.\n",
1425                inst->seqNum, inst->readPC());
1426
1427        iewInstsToCommit[tid]++;
1428
1429        // Some instructions will be sent to commit without having
1430        // executed because they need commit to handle them.
1431        // E.g. Uncached loads have not actually executed when they
1432        // are first sent to commit.  Instead commit must tell the LSQ
1433        // when it's ready to execute the uncached load.
1434        if (!inst->isSquashed() && inst->isExecuted() && inst->getFault() == NoFault) {
1435            int dependents = instQueue.wakeDependents(inst);
1436
1437            for (int i = 0; i < inst->numDestRegs(); i++) {
1438                //mark as Ready
1439                DPRINTF(IEW,"Setting Destination Register %i\n",
1440                        inst->renamedDestRegIdx(i));
1441                scoreboard->setReg(inst->renamedDestRegIdx(i));
1442            }
1443
1444            if (dependents) {
1445                producerInst[tid]++;
1446                consumerInst[tid]+= dependents;
1447            }
1448            writebackCount[tid]++;
1449        }
1450
1451        decrWb(inst->seqNum);
1452    }
1453}
1454
1455template<class Impl>
1456void
1457DefaultIEW<Impl>::tick()
1458{
1459    wbNumInst = 0;
1460    wbCycle = 0;
1461
1462    wroteToTimeBuffer = false;
1463    updatedQueues = false;
1464
1465    sortInsts();
1466
1467    // Free function units marked as being freed this cycle.
1468    fuPool->processFreeUnits();
1469
1470    std::list<unsigned>::iterator threads = (*activeThreads).begin();
1471
1472    // Check stall and squash signals, dispatch any instructions.
1473    while (threads != (*activeThreads).end()) {
1474           unsigned tid = *threads++;
1475
1476        DPRINTF(IEW,"Issue: Processing [tid:%i]\n",tid);
1477
1478        checkSignalsAndUpdate(tid);
1479        dispatch(tid);
1480    }
1481
1482    if (exeStatus != Squashing) {
1483        executeInsts();
1484
1485        writebackInsts();
1486
1487        // Have the instruction queue try to schedule any ready instructions.
1488        // (In actuality, this scheduling is for instructions that will
1489        // be executed next cycle.)
1490        instQueue.scheduleReadyInsts();
1491
1492        // Also should advance its own time buffers if the stage ran.
1493        // Not the best place for it, but this works (hopefully).
1494        issueToExecQueue.advance();
1495    }
1496
1497    bool broadcast_free_entries = false;
1498
1499    if (updatedQueues || exeStatus == Running || updateLSQNextCycle) {
1500        exeStatus = Idle;
1501        updateLSQNextCycle = false;
1502
1503        broadcast_free_entries = true;
1504    }
1505
1506    // Writeback any stores using any leftover bandwidth.
1507    ldstQueue.writebackStores();
1508
1509    // Check the committed load/store signals to see if there's a load
1510    // or store to commit.  Also check if it's being told to execute a
1511    // nonspeculative instruction.
1512    // This is pretty inefficient...
1513
1514    threads = (*activeThreads).begin();
1515    while (threads != (*activeThreads).end()) {
1516        unsigned tid = (*threads++);
1517
1518        DPRINTF(IEW,"Processing [tid:%i]\n",tid);
1519
1520        // Update structures based on instructions committed.
1521        if (fromCommit->commitInfo[tid].doneSeqNum != 0 &&
1522            !fromCommit->commitInfo[tid].squash &&
1523            !fromCommit->commitInfo[tid].robSquashing) {
1524
1525            ldstQueue.commitStores(fromCommit->commitInfo[tid].doneSeqNum,tid);
1526
1527            ldstQueue.commitLoads(fromCommit->commitInfo[tid].doneSeqNum,tid);
1528
1529            updateLSQNextCycle = true;
1530            instQueue.commit(fromCommit->commitInfo[tid].doneSeqNum,tid);
1531        }
1532
1533        if (fromCommit->commitInfo[tid].nonSpecSeqNum != 0) {
1534
1535            //DPRINTF(IEW,"NonspecInst from thread %i",tid);
1536            if (fromCommit->commitInfo[tid].uncached) {
1537                instQueue.replayMemInst(fromCommit->commitInfo[tid].uncachedLoad);
1538            } else {
1539                instQueue.scheduleNonSpec(
1540                    fromCommit->commitInfo[tid].nonSpecSeqNum);
1541            }
1542        }
1543
1544        if (broadcast_free_entries) {
1545            toFetch->iewInfo[tid].iqCount =
1546                instQueue.getCount(tid);
1547            toFetch->iewInfo[tid].ldstqCount =
1548                ldstQueue.getCount(tid);
1549
1550            toRename->iewInfo[tid].usedIQ = true;
1551            toRename->iewInfo[tid].freeIQEntries =
1552                instQueue.numFreeEntries();
1553            toRename->iewInfo[tid].usedLSQ = true;
1554            toRename->iewInfo[tid].freeLSQEntries =
1555                ldstQueue.numFreeEntries(tid);
1556
1557            wroteToTimeBuffer = true;
1558        }
1559
1560        DPRINTF(IEW, "[tid:%i], Dispatch dispatched %i instructions.\n",
1561                tid, toRename->iewInfo[tid].dispatched);
1562    }
1563
1564    DPRINTF(IEW, "IQ has %i free entries (Can schedule: %i).  "
1565            "LSQ has %i free entries.\n",
1566            instQueue.numFreeEntries(), instQueue.hasReadyInsts(),
1567            ldstQueue.numFreeEntries());
1568
1569    updateStatus();
1570
1571    if (wroteToTimeBuffer) {
1572        DPRINTF(Activity, "Activity this cycle.\n");
1573        cpu->activityThisCycle();
1574    }
1575}
1576
1577template <class Impl>
1578void
1579DefaultIEW<Impl>::updateExeInstStats(DynInstPtr &inst)
1580{
1581    int thread_number = inst->threadNumber;
1582
1583    //
1584    //  Pick off the software prefetches
1585    //
1586#ifdef TARGET_ALPHA
1587    if (inst->isDataPrefetch())
1588        iewExecutedSwp[thread_number]++;
1589    else
1590        iewIewExecutedcutedInsts++;
1591#else
1592    iewExecutedInsts++;
1593#endif
1594
1595    //
1596    //  Control operations
1597    //
1598    if (inst->isControl())
1599        iewExecutedBranches[thread_number]++;
1600
1601    //
1602    //  Memory operations
1603    //
1604    if (inst->isMemRef()) {
1605        iewExecutedRefs[thread_number]++;
1606
1607        if (inst->isLoad()) {
1608            iewExecLoadInsts[thread_number]++;
1609        }
1610    }
1611}
1612