iew_impl.hh revision 4033 
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    int instSize = sizeof(TheISA::MachInst);
484#if ISA_HAS_DELAY_SLOT
485    bool branch_taken =
486        !(inst->readNextPC() + instSize == inst->readNextNPC() &&
487          (inst->readNextPC() == inst->readPC() + instSize ||
488           inst->readNextPC() == inst->readPC() + 2 * instSize));
489    DPRINTF(Sparc, "Branch taken = %s [sn:%i]\n",
490            branch_taken ? "true": "false", inst->seqNum);
491
492    toCommit->branchTaken[tid] = branch_taken;
493
494    bool squashDelaySlot = true;
495//	(inst->readNextPC() != inst->readPC() + sizeof(TheISA::MachInst));
496    DPRINTF(Sparc, "Squash delay slot = %s [sn:%i]\n",
497            squashDelaySlot ? "true": "false", inst->seqNum);
498    toCommit->squashDelaySlot[tid] = squashDelaySlot;
499    //If we're squashing the delay slot, we need to pick back up at NextPC.
500    //Otherwise, NextPC isn't being squashed, so we should pick back up at
501    //NextNPC.
502    if (squashDelaySlot) {
503        toCommit->nextPC[tid] = inst->readNextPC();
504        toCommit->nextNPC[tid] = inst->readNextNPC();
505    } else {
506        toCommit->nextPC[tid] = inst->readNextNPC();
507        toCommit->nextNPC[tid] = inst->readNextNPC() + instSize;
508    }
509#else
510    toCommit->branchTaken[tid] = inst->readNextPC() !=
511        (inst->readPC() + sizeof(TheISA::MachInst));
512    toCommit->nextPC[tid] = inst->readNextPC();
513    toCommit->nextNPC[tid] = inst->readNextPC() + instSize;
514#endif
515
516    toCommit->includeSquashInst[tid] = false;
517
518    wroteToTimeBuffer = true;
519}
520
521template<class Impl>
522void
523DefaultIEW<Impl>::squashDueToMemOrder(DynInstPtr &inst, unsigned tid)
524{
525    DPRINTF(IEW, "[tid:%i]: Squashing from a specific instruction, "
526            "PC: %#x [sn:%i].\n", tid, inst->readPC(), inst->seqNum);
527
528    toCommit->squash[tid] = true;
529    toCommit->squashedSeqNum[tid] = inst->seqNum;
530    toCommit->nextPC[tid] = inst->readNextPC();
531#if ISA_HAS_DELAY_SLOT
532    toCommit->nextNPC[tid] = inst->readNextNPC();
533#else
534    toCommit->nextNPC[tid] = inst->readNextPC() + sizeof(TheISA::MachInst);
535#endif
536    toCommit->branchMispredict[tid] = false;
537
538    toCommit->includeSquashInst[tid] = false;
539
540    wroteToTimeBuffer = true;
541}
542
543template<class Impl>
544void
545DefaultIEW<Impl>::squashDueToMemBlocked(DynInstPtr &inst, unsigned tid)
546{
547    DPRINTF(IEW, "[tid:%i]: Memory blocked, squashing load and younger insts, "
548            "PC: %#x [sn:%i].\n", tid, inst->readPC(), inst->seqNum);
549
550    toCommit->squash[tid] = true;
551    toCommit->squashedSeqNum[tid] = inst->seqNum;
552    toCommit->nextPC[tid] = inst->readPC();
553#if ISA_HAS_DELAY_SLOT
554    toCommit->nextNPC[tid] = inst->readNextPC();
555#else
556    toCommit->nextNPC[tid] = inst->readPC() + sizeof(TheISA::MachInst);
557#endif
558    toCommit->branchMispredict[tid] = false;
559
560    // Must include the broadcasted SN in the squash.
561    toCommit->includeSquashInst[tid] = true;
562
563    ldstQueue.setLoadBlockedHandled(tid);
564
565    wroteToTimeBuffer = true;
566}
567
568template<class Impl>
569void
570DefaultIEW<Impl>::block(unsigned tid)
571{
572    DPRINTF(IEW, "[tid:%u]: Blocking.\n", tid);
573
574    if (dispatchStatus[tid] != Blocked &&
575        dispatchStatus[tid] != Unblocking) {
576        toRename->iewBlock[tid] = true;
577        wroteToTimeBuffer = true;
578    }
579
580    // Add the current inputs to the skid buffer so they can be
581    // reprocessed when this stage unblocks.
582    skidInsert(tid);
583
584    dispatchStatus[tid] = Blocked;
585}
586
587template<class Impl>
588void
589DefaultIEW<Impl>::unblock(unsigned tid)
590{
591    DPRINTF(IEW, "[tid:%i]: Reading instructions out of the skid "
592            "buffer %u.\n",tid, tid);
593
594    // If the skid bufffer is empty, signal back to previous stages to unblock.
595    // Also switch status to running.
596    if (skidBuffer[tid].empty()) {
597        toRename->iewUnblock[tid] = true;
598        wroteToTimeBuffer = true;
599        DPRINTF(IEW, "[tid:%i]: Done unblocking.\n",tid);
600        dispatchStatus[tid] = Running;
601    }
602}
603
604template<class Impl>
605void
606DefaultIEW<Impl>::wakeDependents(DynInstPtr &inst)
607{
608    instQueue.wakeDependents(inst);
609}
610
611template<class Impl>
612void
613DefaultIEW<Impl>::rescheduleMemInst(DynInstPtr &inst)
614{
615    instQueue.rescheduleMemInst(inst);
616}
617
618template<class Impl>
619void
620DefaultIEW<Impl>::replayMemInst(DynInstPtr &inst)
621{
622    instQueue.replayMemInst(inst);
623}
624
625template<class Impl>
626void
627DefaultIEW<Impl>::instToCommit(DynInstPtr &inst)
628{
629    // This function should not be called after writebackInsts in a
630    // single cycle.  That will cause problems with an instruction
631    // being added to the queue to commit without being processed by
632    // writebackInsts prior to being sent to commit.
633
634    // First check the time slot that this instruction will write
635    // to.  If there are free write ports at the time, then go ahead
636    // and write the instruction to that time.  If there are not,
637    // keep looking back to see where's the first time there's a
638    // free slot.
639    while ((*iewQueue)[wbCycle].insts[wbNumInst]) {
640        ++wbNumInst;
641        if (wbNumInst == wbWidth) {
642            ++wbCycle;
643            wbNumInst = 0;
644        }
645
646        assert((wbCycle * wbWidth + wbNumInst) <= wbMax);
647    }
648
649    DPRINTF(IEW, "Current wb cycle: %i, width: %i, numInst: %i\nwbActual:%i\n",
650            wbCycle, wbWidth, wbNumInst, wbCycle * wbWidth + wbNumInst);
651    // Add finished instruction to queue to commit.
652    (*iewQueue)[wbCycle].insts[wbNumInst] = inst;
653    (*iewQueue)[wbCycle].size++;
654}
655
656template <class Impl>
657unsigned
658DefaultIEW<Impl>::validInstsFromRename()
659{
660    unsigned inst_count = 0;
661
662    for (int i=0; i<fromRename->size; i++) {
663        if (!fromRename->insts[i]->isSquashed())
664            inst_count++;
665    }
666
667    return inst_count;
668}
669
670template<class Impl>
671void
672DefaultIEW<Impl>::skidInsert(unsigned tid)
673{
674    DynInstPtr inst = NULL;
675
676    while (!insts[tid].empty()) {
677        inst = insts[tid].front();
678
679        insts[tid].pop();
680
681        DPRINTF(Decode,"[tid:%i]: Inserting [sn:%lli] PC:%#x into "
682                "dispatch skidBuffer %i\n",tid, inst->seqNum,
683                inst->readPC(),tid);
684
685        skidBuffer[tid].push(inst);
686    }
687
688    assert(skidBuffer[tid].size() <= skidBufferMax &&
689           "Skidbuffer Exceeded Max Size");
690}
691
692template<class Impl>
693int
694DefaultIEW<Impl>::skidCount()
695{
696    int max=0;
697
698    std::list<unsigned>::iterator threads = activeThreads->begin();
699    std::list<unsigned>::iterator end = activeThreads->end();
700
701    while (threads != end) {
702        unsigned tid = *threads++;
703        unsigned thread_count = skidBuffer[tid].size();
704        if (max < thread_count)
705            max = thread_count;
706    }
707
708    return max;
709}
710
711template<class Impl>
712bool
713DefaultIEW<Impl>::skidsEmpty()
714{
715    std::list<unsigned>::iterator threads = activeThreads->begin();
716    std::list<unsigned>::iterator end = activeThreads->end();
717
718    while (threads != end) {
719        unsigned tid = *threads++;
720
721        if (!skidBuffer[tid].empty())
722            return false;
723    }
724
725    return true;
726}
727
728template <class Impl>
729void
730DefaultIEW<Impl>::updateStatus()
731{
732    bool any_unblocking = false;
733
734    std::list<unsigned>::iterator threads = activeThreads->begin();
735    std::list<unsigned>::iterator end = activeThreads->end();
736
737    while (threads != end) {
738        unsigned tid = *threads++;
739
740        if (dispatchStatus[tid] == Unblocking) {
741            any_unblocking = true;
742            break;
743        }
744    }
745
746    // If there are no ready instructions waiting to be scheduled by the IQ,
747    // and there's no stores waiting to write back, and dispatch is not
748    // unblocking, then there is no internal activity for the IEW stage.
749    if (_status == Active && !instQueue.hasReadyInsts() &&
750        !ldstQueue.willWB() && !any_unblocking) {
751        DPRINTF(IEW, "IEW switching to idle\n");
752
753        deactivateStage();
754
755        _status = Inactive;
756    } else if (_status == Inactive && (instQueue.hasReadyInsts() ||
757                                       ldstQueue.willWB() ||
758                                       any_unblocking)) {
759        // Otherwise there is internal activity.  Set to active.
760        DPRINTF(IEW, "IEW switching to active\n");
761
762        activateStage();
763
764        _status = Active;
765    }
766}
767
768template <class Impl>
769void
770DefaultIEW<Impl>::resetEntries()
771{
772    instQueue.resetEntries();
773    ldstQueue.resetEntries();
774}
775
776template <class Impl>
777void
778DefaultIEW<Impl>::readStallSignals(unsigned tid)
779{
780    if (fromCommit->commitBlock[tid]) {
781        stalls[tid].commit = true;
782    }
783
784    if (fromCommit->commitUnblock[tid]) {
785        assert(stalls[tid].commit);
786        stalls[tid].commit = false;
787    }
788}
789
790template <class Impl>
791bool
792DefaultIEW<Impl>::checkStall(unsigned tid)
793{
794    bool ret_val(false);
795
796    if (stalls[tid].commit) {
797        DPRINTF(IEW,"[tid:%i]: Stall from Commit stage detected.\n",tid);
798        ret_val = true;
799    } else if (instQueue.isFull(tid)) {
800        DPRINTF(IEW,"[tid:%i]: Stall: IQ  is full.\n",tid);
801        ret_val = true;
802    } else if (ldstQueue.isFull(tid)) {
803        DPRINTF(IEW,"[tid:%i]: Stall: LSQ is full\n",tid);
804
805        if (ldstQueue.numLoads(tid) > 0 ) {
806
807            DPRINTF(IEW,"[tid:%i]: LSQ oldest load: [sn:%i] \n",
808                    tid,ldstQueue.getLoadHeadSeqNum(tid));
809        }
810
811        if (ldstQueue.numStores(tid) > 0) {
812
813            DPRINTF(IEW,"[tid:%i]: LSQ oldest store: [sn:%i] \n",
814                    tid,ldstQueue.getStoreHeadSeqNum(tid));
815        }
816
817        ret_val = true;
818    } else if (ldstQueue.isStalled(tid)) {
819        DPRINTF(IEW,"[tid:%i]: Stall: LSQ stall detected.\n",tid);
820        ret_val = true;
821    }
822
823    return ret_val;
824}
825
826template <class Impl>
827void
828DefaultIEW<Impl>::checkSignalsAndUpdate(unsigned tid)
829{
830    // Check if there's a squash signal, squash if there is
831    // Check stall signals, block if there is.
832    // If status was Blocked
833    //     if so then go to unblocking
834    // If status was Squashing
835    //     check if squashing is not high.  Switch to running this cycle.
836
837    readStallSignals(tid);
838
839    if (fromCommit->commitInfo[tid].squash) {
840        squash(tid);
841
842        if (dispatchStatus[tid] == Blocked ||
843            dispatchStatus[tid] == Unblocking) {
844            toRename->iewUnblock[tid] = true;
845            wroteToTimeBuffer = true;
846        }
847
848        dispatchStatus[tid] = Squashing;
849
850        fetchRedirect[tid] = false;
851        return;
852    }
853
854    if (fromCommit->commitInfo[tid].robSquashing) {
855        DPRINTF(IEW, "[tid:%i]: ROB is still squashing.\n", tid);
856
857        dispatchStatus[tid] = Squashing;
858
859        emptyRenameInsts(tid);
860        wroteToTimeBuffer = true;
861        return;
862    }
863
864    if (checkStall(tid)) {
865        block(tid);
866        dispatchStatus[tid] = Blocked;
867        return;
868    }
869
870    if (dispatchStatus[tid] == Blocked) {
871        // Status from previous cycle was blocked, but there are no more stall
872        // conditions.  Switch over to unblocking.
873        DPRINTF(IEW, "[tid:%i]: Done blocking, switching to unblocking.\n",
874                tid);
875
876        dispatchStatus[tid] = Unblocking;
877
878        unblock(tid);
879
880        return;
881    }
882
883    if (dispatchStatus[tid] == Squashing) {
884        // Switch status to running if rename isn't being told to block or
885        // squash this cycle.
886        DPRINTF(IEW, "[tid:%i]: Done squashing, switching to running.\n",
887                tid);
888
889        dispatchStatus[tid] = Running;
890
891        return;
892    }
893}
894
895template <class Impl>
896void
897DefaultIEW<Impl>::sortInsts()
898{
899    int insts_from_rename = fromRename->size;
900#ifdef DEBUG
901#if !ISA_HAS_DELAY_SLOT
902    for (int i = 0; i < numThreads; i++)
903        assert(insts[i].empty());
904#endif
905#endif
906    for (int i = 0; i < insts_from_rename; ++i) {
907        insts[fromRename->insts[i]->threadNumber].push(fromRename->insts[i]);
908    }
909}
910
911template <class Impl>
912void
913DefaultIEW<Impl>::emptyRenameInsts(unsigned tid)
914{
915    DPRINTF(IEW, "[tid:%i]: Removing incoming rename instructions until "
916            "[sn:%i].\n", tid, bdelayDoneSeqNum[tid]);
917
918    while (!insts[tid].empty()) {
919#if ISA_HAS_DELAY_SLOT
920        if (insts[tid].front()->seqNum <= bdelayDoneSeqNum[tid]) {
921            DPRINTF(IEW, "[tid:%i]: Done removing, cannot remove instruction"
922                    " that occurs at or before delay slot [sn:%i].\n",
923                    tid, bdelayDoneSeqNum[tid]);
924            break;
925        } else {
926            DPRINTF(IEW, "[tid:%i]: Removing incoming rename instruction "
927                    "[sn:%i].\n", tid, insts[tid].front()->seqNum);
928        }
929#endif
930
931        if (insts[tid].front()->isLoad() ||
932            insts[tid].front()->isStore() ) {
933            toRename->iewInfo[tid].dispatchedToLSQ++;
934        }
935
936        toRename->iewInfo[tid].dispatched++;
937
938        insts[tid].pop();
939    }
940}
941
942template <class Impl>
943void
944DefaultIEW<Impl>::wakeCPU()
945{
946    cpu->wakeCPU();
947}
948
949template <class Impl>
950void
951DefaultIEW<Impl>::activityThisCycle()
952{
953    DPRINTF(Activity, "Activity this cycle.\n");
954    cpu->activityThisCycle();
955}
956
957template <class Impl>
958inline void
959DefaultIEW<Impl>::activateStage()
960{
961    DPRINTF(Activity, "Activating stage.\n");
962    cpu->activateStage(O3CPU::IEWIdx);
963}
964
965template <class Impl>
966inline void
967DefaultIEW<Impl>::deactivateStage()
968{
969    DPRINTF(Activity, "Deactivating stage.\n");
970    cpu->deactivateStage(O3CPU::IEWIdx);
971}
972
973template<class Impl>
974void
975DefaultIEW<Impl>::dispatch(unsigned tid)
976{
977    // If status is Running or idle,
978    //     call dispatchInsts()
979    // If status is Unblocking,
980    //     buffer any instructions coming from rename
981    //     continue trying to empty skid buffer
982    //     check if stall conditions have passed
983
984    if (dispatchStatus[tid] == Blocked) {
985        ++iewBlockCycles;
986
987    } else if (dispatchStatus[tid] == Squashing) {
988        ++iewSquashCycles;
989    }
990
991    // Dispatch should try to dispatch as many instructions as its bandwidth
992    // will allow, as long as it is not currently blocked.
993    if (dispatchStatus[tid] == Running ||
994        dispatchStatus[tid] == Idle) {
995        DPRINTF(IEW, "[tid:%i] Not blocked, so attempting to run "
996                "dispatch.\n", tid);
997
998        dispatchInsts(tid);
999    } else if (dispatchStatus[tid] == Unblocking) {
1000        // Make sure that the skid buffer has something in it if the
1001        // status is unblocking.
1002        assert(!skidsEmpty());
1003
1004        // If the status was unblocking, then instructions from the skid
1005        // buffer were used.  Remove those instructions and handle
1006        // the rest of unblocking.
1007        dispatchInsts(tid);
1008
1009        ++iewUnblockCycles;
1010
1011        if (validInstsFromRename() && dispatchedAllInsts) {
1012            // Add the current inputs to the skid buffer so they can be
1013            // reprocessed when this stage unblocks.
1014            skidInsert(tid);
1015        }
1016
1017        unblock(tid);
1018    }
1019}
1020
1021template <class Impl>
1022void
1023DefaultIEW<Impl>::dispatchInsts(unsigned tid)
1024{
1025    dispatchedAllInsts = true;
1026
1027    // Obtain instructions from skid buffer if unblocking, or queue from rename
1028    // otherwise.
1029    std::queue<DynInstPtr> &insts_to_dispatch =
1030        dispatchStatus[tid] == Unblocking ?
1031        skidBuffer[tid] : insts[tid];
1032
1033    int insts_to_add = insts_to_dispatch.size();
1034
1035    DynInstPtr inst;
1036    bool add_to_iq = false;
1037    int dis_num_inst = 0;
1038
1039    // Loop through the instructions, putting them in the instruction
1040    // queue.
1041    for ( ; dis_num_inst < insts_to_add &&
1042              dis_num_inst < dispatchWidth;
1043          ++dis_num_inst)
1044    {
1045        inst = insts_to_dispatch.front();
1046
1047        if (dispatchStatus[tid] == Unblocking) {
1048            DPRINTF(IEW, "[tid:%i]: Issue: Examining instruction from skid "
1049                    "buffer\n", tid);
1050        }
1051
1052        // Make sure there's a valid instruction there.
1053        assert(inst);
1054
1055        DPRINTF(IEW, "[tid:%i]: Issue: Adding PC %#x [sn:%lli] [tid:%i] to "
1056                "IQ.\n",
1057                tid, inst->readPC(), inst->seqNum, inst->threadNumber);
1058
1059        // Be sure to mark these instructions as ready so that the
1060        // commit stage can go ahead and execute them, and mark
1061        // them as issued so the IQ doesn't reprocess them.
1062
1063        // Check for squashed instructions.
1064        if (inst->isSquashed()) {
1065            DPRINTF(IEW, "[tid:%i]: Issue: Squashed instruction encountered, "
1066                    "not adding to IQ.\n", tid);
1067
1068            ++iewDispSquashedInsts;
1069
1070            insts_to_dispatch.pop();
1071
1072            //Tell Rename That An Instruction has been processed
1073            if (inst->isLoad() || inst->isStore()) {
1074                toRename->iewInfo[tid].dispatchedToLSQ++;
1075            }
1076            toRename->iewInfo[tid].dispatched++;
1077
1078            continue;
1079        }
1080
1081        // Check for full conditions.
1082        if (instQueue.isFull(tid)) {
1083            DPRINTF(IEW, "[tid:%i]: Issue: IQ has become full.\n", tid);
1084
1085            // Call function to start blocking.
1086            block(tid);
1087
1088            // Set unblock to false. Special case where we are using
1089            // skidbuffer (unblocking) instructions but then we still
1090            // get full in the IQ.
1091            toRename->iewUnblock[tid] = false;
1092
1093            dispatchedAllInsts = false;
1094
1095            ++iewIQFullEvents;
1096            break;
1097        } else if (ldstQueue.isFull(tid)) {
1098            DPRINTF(IEW, "[tid:%i]: Issue: LSQ has become full.\n",tid);
1099
1100            // Call function to start blocking.
1101            block(tid);
1102
1103            // Set unblock to false. Special case where we are using
1104            // skidbuffer (unblocking) instructions but then we still
1105            // get full in the IQ.
1106            toRename->iewUnblock[tid] = false;
1107
1108            dispatchedAllInsts = false;
1109
1110            ++iewLSQFullEvents;
1111            break;
1112        }
1113
1114        // Otherwise issue the instruction just fine.
1115        if (inst->isLoad()) {
1116            DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1117                    "encountered, adding to LSQ.\n", tid);
1118
1119            // Reserve a spot in the load store queue for this
1120            // memory access.
1121            ldstQueue.insertLoad(inst);
1122
1123            ++iewDispLoadInsts;
1124
1125            add_to_iq = true;
1126
1127            toRename->iewInfo[tid].dispatchedToLSQ++;
1128        } else if (inst->isStore()) {
1129            DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1130                    "encountered, adding to LSQ.\n", tid);
1131
1132            ldstQueue.insertStore(inst);
1133
1134            ++iewDispStoreInsts;
1135
1136            if (inst->isStoreConditional()) {
1137                // Store conditionals need to be set as "canCommit()"
1138                // so that commit can process them when they reach the
1139                // head of commit.
1140                // @todo: This is somewhat specific to Alpha.
1141                inst->setCanCommit();
1142                instQueue.insertNonSpec(inst);
1143                add_to_iq = false;
1144
1145                ++iewDispNonSpecInsts;
1146            } else {
1147                add_to_iq = true;
1148            }
1149
1150            toRename->iewInfo[tid].dispatchedToLSQ++;
1151        } else if (inst->isMemBarrier() || inst->isWriteBarrier()) {
1152            // Same as non-speculative stores.
1153            inst->setCanCommit();
1154            instQueue.insertBarrier(inst);
1155            add_to_iq = false;
1156        } else if (inst->isNop()) {
1157            DPRINTF(IEW, "[tid:%i]: Issue: Nop instruction encountered, "
1158                    "skipping.\n", tid);
1159
1160            inst->setIssued();
1161            inst->setExecuted();
1162            inst->setCanCommit();
1163
1164            instQueue.recordProducer(inst);
1165
1166            iewExecutedNop[tid]++;
1167
1168            add_to_iq = false;
1169        } else if (inst->isExecuted()) {
1170            assert(0 && "Instruction shouldn't be executed.\n");
1171            DPRINTF(IEW, "Issue: Executed branch encountered, "
1172                    "skipping.\n");
1173
1174            inst->setIssued();
1175            inst->setCanCommit();
1176
1177            instQueue.recordProducer(inst);
1178
1179            add_to_iq = false;
1180        } else {
1181            add_to_iq = true;
1182        }
1183        if (inst->isNonSpeculative()) {
1184            DPRINTF(IEW, "[tid:%i]: Issue: Nonspeculative instruction "
1185                    "encountered, skipping.\n", tid);
1186
1187            // Same as non-speculative stores.
1188            inst->setCanCommit();
1189
1190            // Specifically insert it as nonspeculative.
1191            instQueue.insertNonSpec(inst);
1192
1193            ++iewDispNonSpecInsts;
1194
1195            add_to_iq = false;
1196        }
1197
1198        // If the instruction queue is not full, then add the
1199        // instruction.
1200        if (add_to_iq) {
1201            instQueue.insert(inst);
1202        }
1203
1204        insts_to_dispatch.pop();
1205
1206        toRename->iewInfo[tid].dispatched++;
1207
1208        ++iewDispatchedInsts;
1209    }
1210
1211    if (!insts_to_dispatch.empty()) {
1212        DPRINTF(IEW,"[tid:%i]: Issue: Bandwidth Full. Blocking.\n", tid);
1213        block(tid);
1214        toRename->iewUnblock[tid] = false;
1215    }
1216
1217    if (dispatchStatus[tid] == Idle && dis_num_inst) {
1218        dispatchStatus[tid] = Running;
1219
1220        updatedQueues = true;
1221    }
1222
1223    dis_num_inst = 0;
1224}
1225
1226template <class Impl>
1227void
1228DefaultIEW<Impl>::printAvailableInsts()
1229{
1230    int inst = 0;
1231
1232    std::cout << "Available Instructions: ";
1233
1234    while (fromIssue->insts[inst]) {
1235
1236        if (inst%3==0) std::cout << "\n\t";
1237
1238        std::cout << "PC: " << fromIssue->insts[inst]->readPC()
1239             << " TN: " << fromIssue->insts[inst]->threadNumber
1240             << " SN: " << fromIssue->insts[inst]->seqNum << " | ";
1241
1242        inst++;
1243
1244    }
1245
1246    std::cout << "\n";
1247}
1248
1249template <class Impl>
1250void
1251DefaultIEW<Impl>::executeInsts()
1252{
1253    wbNumInst = 0;
1254    wbCycle = 0;
1255
1256    std::list<unsigned>::iterator threads = activeThreads->begin();
1257    std::list<unsigned>::iterator end = activeThreads->end();
1258
1259    while (threads != end) {
1260        unsigned tid = *threads++;
1261        fetchRedirect[tid] = false;
1262    }
1263
1264    // Uncomment this if you want to see all available instructions.
1265//    printAvailableInsts();
1266
1267    // Execute/writeback any instructions that are available.
1268    int insts_to_execute = fromIssue->size;
1269    int inst_num = 0;
1270    for (; inst_num < insts_to_execute;
1271          ++inst_num) {
1272
1273        DPRINTF(IEW, "Execute: Executing instructions from IQ.\n");
1274
1275        DynInstPtr inst = instQueue.getInstToExecute();
1276
1277        DPRINTF(IEW, "Execute: Processing PC %#x, [tid:%i] [sn:%i].\n",
1278                inst->readPC(), inst->threadNumber,inst->seqNum);
1279
1280        // Check if the instruction is squashed; if so then skip it
1281        if (inst->isSquashed()) {
1282            DPRINTF(IEW, "Execute: Instruction was squashed.\n");
1283
1284            // Consider this instruction executed so that commit can go
1285            // ahead and retire the instruction.
1286            inst->setExecuted();
1287
1288            // Not sure if I should set this here or just let commit try to
1289            // commit any squashed instructions.  I like the latter a bit more.
1290            inst->setCanCommit();
1291
1292            ++iewExecSquashedInsts;
1293
1294            decrWb(inst->seqNum);
1295            continue;
1296        }
1297
1298        Fault fault = NoFault;
1299
1300        // Execute instruction.
1301        // Note that if the instruction faults, it will be handled
1302        // at the commit stage.
1303        if (inst->isMemRef() &&
1304            (!inst->isDataPrefetch() && !inst->isInstPrefetch())) {
1305            DPRINTF(IEW, "Execute: Calculating address for memory "
1306                    "reference.\n");
1307
1308            // Tell the LDSTQ to execute this instruction (if it is a load).
1309            if (inst->isLoad()) {
1310                // Loads will mark themselves as executed, and their writeback
1311                // event adds the instruction to the queue to commit
1312                fault = ldstQueue.executeLoad(inst);
1313            } else if (inst->isStore()) {
1314                fault = ldstQueue.executeStore(inst);
1315
1316                // If the store had a fault then it may not have a mem req
1317                if (!inst->isStoreConditional() && fault == NoFault) {
1318                    inst->setExecuted();
1319
1320                    instToCommit(inst);
1321                } else if (fault != NoFault) {
1322                    // If the instruction faulted, then we need to send it along to commit
1323                    // without the instruction completing.
1324                    DPRINTF(IEW, "Store has fault %s! [sn:%lli]\n",
1325                            fault->name(), inst->seqNum);
1326
1327                    // Send this instruction to commit, also make sure iew stage
1328                    // realizes there is activity.
1329                    inst->setExecuted();
1330
1331                    instToCommit(inst);
1332                    activityThisCycle();
1333                }
1334
1335                // Store conditionals will mark themselves as
1336                // executed, and their writeback event will add the
1337                // instruction to the queue to commit.
1338            } else {
1339                panic("Unexpected memory type!\n");
1340            }
1341
1342        } else {
1343            inst->execute();
1344
1345            inst->setExecuted();
1346
1347            instToCommit(inst);
1348        }
1349
1350        updateExeInstStats(inst);
1351
1352        // Check if branch prediction was correct, if not then we need
1353        // to tell commit to squash in flight instructions.  Only
1354        // handle this if there hasn't already been something that
1355        // redirects fetch in this group of instructions.
1356
1357        // This probably needs to prioritize the redirects if a different
1358        // scheduler is used.  Currently the scheduler schedules the oldest
1359        // instruction first, so the branch resolution order will be correct.
1360        unsigned tid = inst->threadNumber;
1361
1362        if (!fetchRedirect[tid] ||
1363            toCommit->squashedSeqNum[tid] > inst->seqNum) {
1364
1365            if (inst->mispredicted()) {
1366                fetchRedirect[tid] = true;
1367
1368                DPRINTF(IEW, "Execute: Branch mispredict detected.\n");
1369                DPRINTF(IEW, "Predicted target was %#x, %#x.\n",
1370                        inst->readPredPC(), inst->readPredNPC());
1371                DPRINTF(IEW, "Execute: Redirecting fetch to PC: %#x,"
1372                        " NPC: %#x.\n", inst->readNextPC(),
1373                        inst->readNextNPC());
1374                // If incorrect, then signal the ROB that it must be squashed.
1375                squashDueToBranch(inst, tid);
1376
1377                if (inst->readPredTaken()) {
1378                    predictedTakenIncorrect++;
1379                } else {
1380                    predictedNotTakenIncorrect++;
1381                }
1382            } else if (ldstQueue.violation(tid)) {
1383                assert(inst->isMemRef());
1384                // If there was an ordering violation, then get the
1385                // DynInst that caused the violation.  Note that this
1386                // clears the violation signal.
1387                DynInstPtr violator;
1388                violator = ldstQueue.getMemDepViolator(tid);
1389
1390                DPRINTF(IEW, "LDSTQ detected a violation.  Violator PC: "
1391                        "%#x, inst PC: %#x.  Addr is: %#x.\n",
1392                        violator->readPC(), inst->readPC(), inst->physEffAddr);
1393
1394                // Ensure the violating instruction is older than
1395                // current squash
1396/*                if (fetchRedirect[tid] &&
1397                    violator->seqNum >= toCommit->squashedSeqNum[tid] + 1)
1398                    continue;
1399*/
1400                fetchRedirect[tid] = true;
1401
1402                // Tell the instruction queue that a violation has occured.
1403                instQueue.violation(inst, violator);
1404
1405                // Squash.
1406                squashDueToMemOrder(inst,tid);
1407
1408                ++memOrderViolationEvents;
1409            } else if (ldstQueue.loadBlocked(tid) &&
1410                       !ldstQueue.isLoadBlockedHandled(tid)) {
1411                fetchRedirect[tid] = true;
1412
1413                DPRINTF(IEW, "Load operation couldn't execute because the "
1414                        "memory system is blocked.  PC: %#x [sn:%lli]\n",
1415                        inst->readPC(), inst->seqNum);
1416
1417                squashDueToMemBlocked(inst, tid);
1418            }
1419        } else {
1420            // Reset any state associated with redirects that will not
1421            // be used.
1422            if (ldstQueue.violation(tid)) {
1423                assert(inst->isMemRef());
1424
1425                DynInstPtr violator = ldstQueue.getMemDepViolator(tid);
1426
1427                DPRINTF(IEW, "LDSTQ detected a violation.  Violator PC: "
1428                        "%#x, inst PC: %#x.  Addr is: %#x.\n",
1429                        violator->readPC(), inst->readPC(), inst->physEffAddr);
1430                DPRINTF(IEW, "Violation will not be handled because "
1431                        "already squashing\n");
1432
1433                ++memOrderViolationEvents;
1434            }
1435            if (ldstQueue.loadBlocked(tid) &&
1436                !ldstQueue.isLoadBlockedHandled(tid)) {
1437                DPRINTF(IEW, "Load operation couldn't execute because the "
1438                        "memory system is blocked.  PC: %#x [sn:%lli]\n",
1439                        inst->readPC(), inst->seqNum);
1440                DPRINTF(IEW, "Blocked load will not be handled because "
1441                        "already squashing\n");
1442
1443                ldstQueue.setLoadBlockedHandled(tid);
1444            }
1445
1446        }
1447    }
1448
1449    // Update and record activity if we processed any instructions.
1450    if (inst_num) {
1451        if (exeStatus == Idle) {
1452            exeStatus = Running;
1453        }
1454
1455        updatedQueues = true;
1456
1457        cpu->activityThisCycle();
1458    }
1459
1460    // Need to reset this in case a writeback event needs to write into the
1461    // iew queue.  That way the writeback event will write into the correct
1462    // spot in the queue.
1463    wbNumInst = 0;
1464}
1465
1466template <class Impl>
1467void
1468DefaultIEW<Impl>::writebackInsts()
1469{
1470    // Loop through the head of the time buffer and wake any
1471    // dependents.  These instructions are about to write back.  Also
1472    // mark scoreboard that this instruction is finally complete.
1473    // Either have IEW have direct access to scoreboard, or have this
1474    // as part of backwards communication.
1475    for (int inst_num = 0; inst_num < wbWidth &&
1476             toCommit->insts[inst_num]; inst_num++) {
1477        DynInstPtr inst = toCommit->insts[inst_num];
1478        int tid = inst->threadNumber;
1479
1480        DPRINTF(IEW, "Sending instructions to commit, [sn:%lli] PC %#x.\n",
1481                inst->seqNum, inst->readPC());
1482
1483        iewInstsToCommit[tid]++;
1484
1485        // Some instructions will be sent to commit without having
1486        // executed because they need commit to handle them.
1487        // E.g. Uncached loads have not actually executed when they
1488        // are first sent to commit.  Instead commit must tell the LSQ
1489        // when it's ready to execute the uncached load.
1490        if (!inst->isSquashed() && inst->isExecuted() && inst->getFault() == NoFault) {
1491            int dependents = instQueue.wakeDependents(inst);
1492
1493            for (int i = 0; i < inst->numDestRegs(); i++) {
1494                //mark as Ready
1495                DPRINTF(IEW,"Setting Destination Register %i\n",
1496                        inst->renamedDestRegIdx(i));
1497                scoreboard->setReg(inst->renamedDestRegIdx(i));
1498            }
1499
1500            if (dependents) {
1501                producerInst[tid]++;
1502                consumerInst[tid]+= dependents;
1503            }
1504            writebackCount[tid]++;
1505        }
1506
1507        decrWb(inst->seqNum);
1508    }
1509}
1510
1511template<class Impl>
1512void
1513DefaultIEW<Impl>::tick()
1514{
1515    wbNumInst = 0;
1516    wbCycle = 0;
1517
1518    wroteToTimeBuffer = false;
1519    updatedQueues = false;
1520
1521    sortInsts();
1522
1523    // Free function units marked as being freed this cycle.
1524    fuPool->processFreeUnits();
1525
1526    std::list<unsigned>::iterator threads = activeThreads->begin();
1527    std::list<unsigned>::iterator end = activeThreads->end();
1528
1529    // Check stall and squash signals, dispatch any instructions.
1530    while (threads != end) {
1531        unsigned tid = *threads++;
1532
1533        DPRINTF(IEW,"Issue: Processing [tid:%i]\n",tid);
1534
1535        checkSignalsAndUpdate(tid);
1536        dispatch(tid);
1537    }
1538
1539    if (exeStatus != Squashing) {
1540        executeInsts();
1541
1542        writebackInsts();
1543
1544        // Have the instruction queue try to schedule any ready instructions.
1545        // (In actuality, this scheduling is for instructions that will
1546        // be executed next cycle.)
1547        instQueue.scheduleReadyInsts();
1548
1549        // Also should advance its own time buffers if the stage ran.
1550        // Not the best place for it, but this works (hopefully).
1551        issueToExecQueue.advance();
1552    }
1553
1554    bool broadcast_free_entries = false;
1555
1556    if (updatedQueues || exeStatus == Running || updateLSQNextCycle) {
1557        exeStatus = Idle;
1558        updateLSQNextCycle = false;
1559
1560        broadcast_free_entries = true;
1561    }
1562
1563    // Writeback any stores using any leftover bandwidth.
1564    ldstQueue.writebackStores();
1565
1566    // Check the committed load/store signals to see if there's a load
1567    // or store to commit.  Also check if it's being told to execute a
1568    // nonspeculative instruction.
1569    // This is pretty inefficient...
1570
1571    threads = activeThreads->begin();
1572    while (threads != end) {
1573        unsigned tid = (*threads++);
1574
1575        DPRINTF(IEW,"Processing [tid:%i]\n",tid);
1576
1577        // Update structures based on instructions committed.
1578        if (fromCommit->commitInfo[tid].doneSeqNum != 0 &&
1579            !fromCommit->commitInfo[tid].squash &&
1580            !fromCommit->commitInfo[tid].robSquashing) {
1581
1582            ldstQueue.commitStores(fromCommit->commitInfo[tid].doneSeqNum,tid);
1583
1584            ldstQueue.commitLoads(fromCommit->commitInfo[tid].doneSeqNum,tid);
1585
1586            updateLSQNextCycle = true;
1587            instQueue.commit(fromCommit->commitInfo[tid].doneSeqNum,tid);
1588        }
1589
1590        if (fromCommit->commitInfo[tid].nonSpecSeqNum != 0) {
1591
1592            //DPRINTF(IEW,"NonspecInst from thread %i",tid);
1593            if (fromCommit->commitInfo[tid].uncached) {
1594                instQueue.replayMemInst(fromCommit->commitInfo[tid].uncachedLoad);
1595                fromCommit->commitInfo[tid].uncachedLoad->setAtCommit();
1596            } else {
1597                instQueue.scheduleNonSpec(
1598                    fromCommit->commitInfo[tid].nonSpecSeqNum);
1599            }
1600        }
1601
1602        if (broadcast_free_entries) {
1603            toFetch->iewInfo[tid].iqCount =
1604                instQueue.getCount(tid);
1605            toFetch->iewInfo[tid].ldstqCount =
1606                ldstQueue.getCount(tid);
1607
1608            toRename->iewInfo[tid].usedIQ = true;
1609            toRename->iewInfo[tid].freeIQEntries =
1610                instQueue.numFreeEntries();
1611            toRename->iewInfo[tid].usedLSQ = true;
1612            toRename->iewInfo[tid].freeLSQEntries =
1613                ldstQueue.numFreeEntries(tid);
1614
1615            wroteToTimeBuffer = true;
1616        }
1617
1618        DPRINTF(IEW, "[tid:%i], Dispatch dispatched %i instructions.\n",
1619                tid, toRename->iewInfo[tid].dispatched);
1620    }
1621
1622    DPRINTF(IEW, "IQ has %i free entries (Can schedule: %i).  "
1623            "LSQ has %i free entries.\n",
1624            instQueue.numFreeEntries(), instQueue.hasReadyInsts(),
1625            ldstQueue.numFreeEntries());
1626
1627    updateStatus();
1628
1629    if (wroteToTimeBuffer) {
1630        DPRINTF(Activity, "Activity this cycle.\n");
1631        cpu->activityThisCycle();
1632    }
1633}
1634
1635template <class Impl>
1636void
1637DefaultIEW<Impl>::updateExeInstStats(DynInstPtr &inst)
1638{
1639    int thread_number = inst->threadNumber;
1640
1641    //
1642    //  Pick off the software prefetches
1643    //
1644#ifdef TARGET_ALPHA
1645    if (inst->isDataPrefetch())
1646        iewExecutedSwp[thread_number]++;
1647    else
1648        iewIewExecutedcutedInsts++;
1649#else
1650    iewExecutedInsts++;
1651#endif
1652
1653    //
1654    //  Control operations
1655    //
1656    if (inst->isControl())
1657        iewExecutedBranches[thread_number]++;
1658
1659    //
1660    //  Memory operations
1661    //
1662    if (inst->isMemRef()) {
1663        iewExecutedRefs[thread_number]++;
1664
1665        if (inst->isLoad()) {
1666            iewExecLoadInsts[thread_number]++;
1667        }
1668    }
1669}
1670