1/*
2 * Copyright (c) 2010 ARM Limited
3 * All rights reserved.
4 *
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder. You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Copyright (c) 2004-2006 The Regents of The University of Michigan
15 * All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions are
19 * met: redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer;
21 * redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution;
24 * neither the name of the copyright holders nor the names of its
25 * contributors may be used to endorse or promote products derived from
26 * this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 *
40 * Authors: Kevin Lim
41 */
42
43// @todo: Fix the instantaneous communication among all the stages within
44// iew. There's a clear delay between issue and execute, yet backwards
45// communication happens simultaneously.
46
47#include <queue>
48
49#include "cpu/timebuf.hh"
50#include "config/the_isa.hh"
51#include "cpu/o3/fu_pool.hh"
52#include "cpu/o3/iew.hh"
53#include "params/DerivO3CPU.hh"
54
55using namespace std;
56
57template<class Impl>
58DefaultIEW<Impl>::DefaultIEW(O3CPU *_cpu, DerivO3CPUParams *params)
59 : issueToExecQueue(params->backComSize, params->forwardComSize),
60 cpu(_cpu),
61 instQueue(_cpu, this, params),
62 ldstQueue(_cpu, this, params),
63 fuPool(params->fuPool),
64 commitToIEWDelay(params->commitToIEWDelay),
65 renameToIEWDelay(params->renameToIEWDelay),
66 issueToExecuteDelay(params->issueToExecuteDelay),
67 dispatchWidth(params->dispatchWidth),
68 issueWidth(params->issueWidth),
69 wbOutstanding(0),
70 wbWidth(params->wbWidth),
71 numThreads(params->numThreads),
72 switchedOut(false)
73{
74 _status = Active;
75 exeStatus = Running;
76 wbStatus = Idle;
77
78 // Setup wire to read instructions coming from issue.
79 fromIssue = issueToExecQueue.getWire(-issueToExecuteDelay);
80
81 // Instruction queue needs the queue between issue and execute.
82 instQueue.setIssueToExecuteQueue(&issueToExecQueue);
83
84 for (ThreadID tid = 0; tid < numThreads; tid++) {
85 dispatchStatus[tid] = Running;
86 stalls[tid].commit = false;
87 fetchRedirect[tid] = false;
88 }
89
90 wbMax = wbWidth * params->wbDepth;
91
92 updateLSQNextCycle = false;
93
94 ableToIssue = true;
95
96 skidBufferMax = (3 * (renameToIEWDelay * params->renameWidth)) + issueWidth;
97}
98
99template <class Impl>
100std::string
101DefaultIEW<Impl>::name() const
102{
103 return cpu->name() + ".iew";
104}
105
106template <class Impl>
107void
108DefaultIEW<Impl>::regStats()
109{
110 using namespace Stats;
111
112 instQueue.regStats();
113 ldstQueue.regStats();
114
115 iewIdleCycles
116 .name(name() + ".iewIdleCycles")
117 .desc("Number of cycles IEW is idle");
118
119 iewSquashCycles
120 .name(name() + ".iewSquashCycles")
121 .desc("Number of cycles IEW is squashing");
122
123 iewBlockCycles
124 .name(name() + ".iewBlockCycles")
125 .desc("Number of cycles IEW is blocking");
126
127 iewUnblockCycles
128 .name(name() + ".iewUnblockCycles")
129 .desc("Number of cycles IEW is unblocking");
130
131 iewDispatchedInsts
132 .name(name() + ".iewDispatchedInsts")
133 .desc("Number of instructions dispatched to IQ");
134
135 iewDispSquashedInsts
136 .name(name() + ".iewDispSquashedInsts")
137 .desc("Number of squashed instructions skipped by dispatch");
138
139 iewDispLoadInsts
140 .name(name() + ".iewDispLoadInsts")
141 .desc("Number of dispatched load instructions");
142
143 iewDispStoreInsts
144 .name(name() + ".iewDispStoreInsts")
145 .desc("Number of dispatched store instructions");
146
147 iewDispNonSpecInsts
148 .name(name() + ".iewDispNonSpecInsts")
149 .desc("Number of dispatched non-speculative instructions");
150
151 iewIQFullEvents
152 .name(name() + ".iewIQFullEvents")
153 .desc("Number of times the IQ has become full, causing a stall");
154
155 iewLSQFullEvents
156 .name(name() + ".iewLSQFullEvents")
157 .desc("Number of times the LSQ has become full, causing a stall");
158
159 memOrderViolationEvents
160 .name(name() + ".memOrderViolationEvents")
161 .desc("Number of memory order violations");
162
163 predictedTakenIncorrect
164 .name(name() + ".predictedTakenIncorrect")
165 .desc("Number of branches that were predicted taken incorrectly");
166
167 predictedNotTakenIncorrect
168 .name(name() + ".predictedNotTakenIncorrect")
169 .desc("Number of branches that were predicted not taken incorrectly");
170
171 branchMispredicts
172 .name(name() + ".branchMispredicts")
173 .desc("Number of branch mispredicts detected at execute");
174
175 branchMispredicts = predictedTakenIncorrect + predictedNotTakenIncorrect;
176
177 iewExecutedInsts
178 .name(name() + ".iewExecutedInsts")
179 .desc("Number of executed instructions");
180
181 iewExecLoadInsts
182 .init(cpu->numThreads)
183 .name(name() + ".iewExecLoadInsts")
184 .desc("Number of load instructions executed")
185 .flags(total);
186
187 iewExecSquashedInsts
188 .name(name() + ".iewExecSquashedInsts")
189 .desc("Number of squashed instructions skipped in execute");
190
191 iewExecutedSwp
192 .init(cpu->numThreads)
193 .name(name() + ".EXEC:swp")
194 .desc("number of swp insts executed")
195 .flags(total);
196
197 iewExecutedNop
198 .init(cpu->numThreads)
199 .name(name() + ".EXEC:nop")
200 .desc("number of nop insts executed")
201 .flags(total);
202
203 iewExecutedRefs
204 .init(cpu->numThreads)
205 .name(name() + ".EXEC:refs")
206 .desc("number of memory reference insts executed")
207 .flags(total);
208
209 iewExecutedBranches
210 .init(cpu->numThreads)
211 .name(name() + ".EXEC:branches")
212 .desc("Number of branches executed")
213 .flags(total);
214
215 iewExecStoreInsts
216 .name(name() + ".EXEC:stores")
217 .desc("Number of stores executed")
218 .flags(total);
219 iewExecStoreInsts = iewExecutedRefs - iewExecLoadInsts;
220
221 iewExecRate
222 .name(name() + ".EXEC:rate")
223 .desc("Inst execution rate")
224 .flags(total);
225
226 iewExecRate = iewExecutedInsts / cpu->numCycles;
227
228 iewInstsToCommit
229 .init(cpu->numThreads)
230 .name(name() + ".WB:sent")
231 .desc("cumulative count of insts sent to commit")
232 .flags(total);
233
234 writebackCount
235 .init(cpu->numThreads)
236 .name(name() + ".WB:count")
237 .desc("cumulative count of insts written-back")
238 .flags(total);
239
240 producerInst
241 .init(cpu->numThreads)
242 .name(name() + ".WB:producers")
243 .desc("num instructions producing a value")
244 .flags(total);
245
246 consumerInst
247 .init(cpu->numThreads)
248 .name(name() + ".WB:consumers")
249 .desc("num instructions consuming a value")
250 .flags(total);
251
252 wbPenalized
253 .init(cpu->numThreads)
254 .name(name() + ".WB:penalized")
255 .desc("number of instrctions required to write to 'other' IQ")
256 .flags(total);
257
258 wbPenalizedRate
259 .name(name() + ".WB:penalized_rate")
260 .desc ("fraction of instructions written-back that wrote to 'other' IQ")
261 .flags(total);
262
263 wbPenalizedRate = wbPenalized / writebackCount;
264
265 wbFanout
266 .name(name() + ".WB:fanout")
267 .desc("average fanout of values written-back")
268 .flags(total);
269
270 wbFanout = producerInst / consumerInst;
271
272 wbRate
273 .name(name() + ".WB:rate")
274 .desc("insts written-back per cycle")
275 .flags(total);
276 wbRate = writebackCount / cpu->numCycles;
277}
278
279template<class Impl>
280void
281DefaultIEW<Impl>::initStage()
282{
283 for (ThreadID tid = 0; tid < numThreads; tid++) {
284 toRename->iewInfo[tid].usedIQ = true;
285 toRename->iewInfo[tid].freeIQEntries =
286 instQueue.numFreeEntries(tid);
287
288 toRename->iewInfo[tid].usedLSQ = true;
289 toRename->iewInfo[tid].freeLSQEntries =
290 ldstQueue.numFreeEntries(tid);
291 }
292
293 cpu->activateStage(O3CPU::IEWIdx);
294}
295
296template<class Impl>
297void
298DefaultIEW<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr)
299{
300 timeBuffer = tb_ptr;
301
302 // Setup wire to read information from time buffer, from commit.
303 fromCommit = timeBuffer->getWire(-commitToIEWDelay);
304
305 // Setup wire to write information back to previous stages.
306 toRename = timeBuffer->getWire(0);
307
308 toFetch = timeBuffer->getWire(0);
309
310 // Instruction queue also needs main time buffer.
311 instQueue.setTimeBuffer(tb_ptr);
312}
313
314template<class Impl>
315void
316DefaultIEW<Impl>::setRenameQueue(TimeBuffer<RenameStruct> *rq_ptr)
317{
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 iewQueue = iq_ptr;
329
330 // Setup wire to write instructions to commit.
331 toCommit = iewQueue->getWire(0);
332}
333
334template<class Impl>
335void
336DefaultIEW<Impl>::setActiveThreads(list<ThreadID> *at_ptr)
337{
338 activeThreads = at_ptr;
339
340 ldstQueue.setActiveThreads(at_ptr);
341 instQueue.setActiveThreads(at_ptr);
342}
343
344template<class Impl>
345void
346DefaultIEW<Impl>::setScoreboard(Scoreboard *sb_ptr)
347{
348 scoreboard = sb_ptr;
349}
350
351template <class Impl>
352bool
353DefaultIEW<Impl>::drain()
354{
355 // IEW is ready to drain at any time.
356 cpu->signalDrained();
357 return true;
358}
359
360template <class Impl>
361void
362DefaultIEW<Impl>::resume()
363{
364}
365
366template <class Impl>
367void
368DefaultIEW<Impl>::switchOut()
369{
370 // Clear any state.
371 switchedOut = true;
372 assert(insts[0].empty());
373 assert(skidBuffer[0].empty());
374
375 instQueue.switchOut();
376 ldstQueue.switchOut();
377 fuPool->switchOut();
378
379 for (ThreadID tid = 0; tid < numThreads; tid++) {
380 while (!insts[tid].empty())
381 insts[tid].pop();
382 while (!skidBuffer[tid].empty())
383 skidBuffer[tid].pop();
384 }
385}
386
387template <class Impl>
388void
389DefaultIEW<Impl>::takeOverFrom()
390{
391 // Reset all state.
392 _status = Active;
393 exeStatus = Running;
394 wbStatus = Idle;
395 switchedOut = false;
396
397 instQueue.takeOverFrom();
398 ldstQueue.takeOverFrom();
399 fuPool->takeOverFrom();
400
401 initStage();
402 cpu->activityThisCycle();
403
404 for (ThreadID tid = 0; tid < numThreads; tid++) {
405 dispatchStatus[tid] = Running;
406 stalls[tid].commit = false;
407 fetchRedirect[tid] = false;
408 }
409
410 updateLSQNextCycle = false;
411
412 for (int i = 0; i < issueToExecQueue.getSize(); ++i) {
413 issueToExecQueue.advance();
414 }
415}
416
417template<class Impl>
418void
419DefaultIEW<Impl>::squash(ThreadID tid)
420{
421 DPRINTF(IEW, "[tid:%i]: Squashing all instructions.\n", tid);
422
423 // Tell the IQ to start squashing.
424 instQueue.squash(tid);
425
426 // Tell the LDSTQ to start squashing.
427 ldstQueue.squash(fromCommit->commitInfo[tid].doneSeqNum, tid);
428 updatedQueues = true;
429
430 // Clear the skid buffer in case it has any data in it.
431 DPRINTF(IEW, "[tid:%i]: Removing skidbuffer instructions until [sn:%i].\n",
432 tid, fromCommit->commitInfo[tid].doneSeqNum);
433
434 while (!skidBuffer[tid].empty()) {
435 if (skidBuffer[tid].front()->isLoad() ||
436 skidBuffer[tid].front()->isStore() ) {
437 toRename->iewInfo[tid].dispatchedToLSQ++;
438 }
439
440 toRename->iewInfo[tid].dispatched++;
441
442 skidBuffer[tid].pop();
443 }
444
445 emptyRenameInsts(tid);
446}
447
448template<class Impl>
449void
450DefaultIEW<Impl>::squashDueToBranch(DynInstPtr &inst, ThreadID tid)
451{
452 DPRINTF(IEW, "[tid:%i]: Squashing from a specific instruction, PC: %s "
453 "[sn:%i].\n", tid, inst->pcState(), inst->seqNum);
454
455 if (toCommit->squash[tid] == false ||
456 inst->seqNum < toCommit->squashedSeqNum[tid]) {
457 toCommit->squash[tid] = true;
458 toCommit->squashedSeqNum[tid] = inst->seqNum;
459 toCommit->mispredPC[tid] = inst->instAddr();
460 toCommit->branchMispredict[tid] = true;
461 toCommit->branchTaken[tid] = inst->pcState().branching();
462
463 TheISA::PCState pc = inst->pcState();
464 TheISA::advancePC(pc, inst->staticInst);
465
466 toCommit->pc[tid] = pc;
467 toCommit->mispredictInst[tid] = inst;
468 toCommit->includeSquashInst[tid] = false;
469
470 wroteToTimeBuffer = true;
471 }
472
473}
474
475template<class Impl>
476void
477DefaultIEW<Impl>::squashDueToMemOrder(DynInstPtr &inst, ThreadID tid)
478{
479 DPRINTF(IEW, "[tid:%i]: Squashing from a specific instruction, "
480 "PC: %s [sn:%i].\n", tid, inst->pcState(), inst->seqNum);
481
482 if (toCommit->squash[tid] == false ||
483 inst->seqNum < toCommit->squashedSeqNum[tid]) {
484 toCommit->squash[tid] = true;
485 toCommit->squashedSeqNum[tid] = inst->seqNum;
486 TheISA::PCState pc = inst->pcState();
487 TheISA::advancePC(pc, inst->staticInst);
488 toCommit->pc[tid] = pc;
489 toCommit->branchMispredict[tid] = false;
490
491 toCommit->includeSquashInst[tid] = false;
492
493 wroteToTimeBuffer = true;
494 }
495}
496
497template<class Impl>
498void
499DefaultIEW<Impl>::squashDueToMemBlocked(DynInstPtr &inst, ThreadID tid)
500{
501 DPRINTF(IEW, "[tid:%i]: Memory blocked, squashing load and younger insts, "
502 "PC: %s [sn:%i].\n", tid, inst->pcState(), inst->seqNum);
503 if (toCommit->squash[tid] == false ||
504 inst->seqNum < toCommit->squashedSeqNum[tid]) {
505 toCommit->squash[tid] = true;
506
507 toCommit->squashedSeqNum[tid] = inst->seqNum;
508 toCommit->pc[tid] = inst->pcState();
509 toCommit->branchMispredict[tid] = false;
510
511 // Must include the broadcasted SN in the squash.
512 toCommit->includeSquashInst[tid] = true;
513
514 ldstQueue.setLoadBlockedHandled(tid);
515
516 wroteToTimeBuffer = true;
517 }
518}
519
520template<class Impl>
521void
522DefaultIEW<Impl>::block(ThreadID tid)
523{
524 DPRINTF(IEW, "[tid:%u]: Blocking.\n", tid);
525
526 if (dispatchStatus[tid] != Blocked &&
527 dispatchStatus[tid] != Unblocking) {
528 toRename->iewBlock[tid] = true;
529 wroteToTimeBuffer = true;
530 }
531
532 // Add the current inputs to the skid buffer so they can be
533 // reprocessed when this stage unblocks.
534 skidInsert(tid);
535
536 dispatchStatus[tid] = Blocked;
537}
538
539template<class Impl>
540void
541DefaultIEW<Impl>::unblock(ThreadID tid)
542{
543 DPRINTF(IEW, "[tid:%i]: Reading instructions out of the skid "
544 "buffer %u.\n",tid, tid);
545
546 // If the skid bufffer is empty, signal back to previous stages to unblock.
547 // Also switch status to running.
548 if (skidBuffer[tid].empty()) {
549 toRename->iewUnblock[tid] = true;
550 wroteToTimeBuffer = true;
551 DPRINTF(IEW, "[tid:%i]: Done unblocking.\n",tid);
552 dispatchStatus[tid] = Running;
553 }
554}
555
556template<class Impl>
557void
558DefaultIEW<Impl>::wakeDependents(DynInstPtr &inst)
559{
560 instQueue.wakeDependents(inst);
561}
562
563template<class Impl>
564void
565DefaultIEW<Impl>::rescheduleMemInst(DynInstPtr &inst)
566{
567 instQueue.rescheduleMemInst(inst);
568}
569
570template<class Impl>
571void
572DefaultIEW<Impl>::replayMemInst(DynInstPtr &inst)
573{
574 instQueue.replayMemInst(inst);
575}
576
577template<class Impl>
578void
579DefaultIEW<Impl>::instToCommit(DynInstPtr &inst)
580{
581 // This function should not be called after writebackInsts in a
582 // single cycle. That will cause problems with an instruction
583 // being added to the queue to commit without being processed by
584 // writebackInsts prior to being sent to commit.
585
586 // First check the time slot that this instruction will write
587 // to. If there are free write ports at the time, then go ahead
588 // and write the instruction to that time. If there are not,
589 // keep looking back to see where's the first time there's a
590 // free slot.
591 while ((*iewQueue)[wbCycle].insts[wbNumInst]) {
592 ++wbNumInst;
593 if (wbNumInst == wbWidth) {
594 ++wbCycle;
595 wbNumInst = 0;
596 }
597
598 assert((wbCycle * wbWidth + wbNumInst) <= wbMax);
599 }
600
601 DPRINTF(IEW, "Current wb cycle: %i, width: %i, numInst: %i\nwbActual:%i\n",
602 wbCycle, wbWidth, wbNumInst, wbCycle * wbWidth + wbNumInst);
603 // Add finished instruction to queue to commit.
604 (*iewQueue)[wbCycle].insts[wbNumInst] = inst;
605 (*iewQueue)[wbCycle].size++;
606}
607
608template <class Impl>
609unsigned
610DefaultIEW<Impl>::validInstsFromRename()
611{
612 unsigned inst_count = 0;
613
614 for (int i=0; i<fromRename->size; i++) {
615 if (!fromRename->insts[i]->isSquashed())
616 inst_count++;
617 }
618
619 return inst_count;
620}
621
622template<class Impl>
623void
624DefaultIEW<Impl>::skidInsert(ThreadID tid)
625{
626 DynInstPtr inst = NULL;
627
628 while (!insts[tid].empty()) {
629 inst = insts[tid].front();
630
631 insts[tid].pop();
632
633 DPRINTF(Decode,"[tid:%i]: Inserting [sn:%lli] PC:%s into "
634 "dispatch skidBuffer %i\n",tid, inst->seqNum,
635 inst->pcState(),tid);
636
637 skidBuffer[tid].push(inst);
638 }
639
640 assert(skidBuffer[tid].size() <= skidBufferMax &&
641 "Skidbuffer Exceeded Max Size");
642}
643
644template<class Impl>
645int
646DefaultIEW<Impl>::skidCount()
647{
648 int max=0;
649
650 list<ThreadID>::iterator threads = activeThreads->begin();
651 list<ThreadID>::iterator end = activeThreads->end();
652
653 while (threads != end) {
654 ThreadID tid = *threads++;
655 unsigned thread_count = skidBuffer[tid].size();
656 if (max < thread_count)
657 max = thread_count;
658 }
659
660 return max;
661}
662
663template<class Impl>
664bool
665DefaultIEW<Impl>::skidsEmpty()
666{
667 list<ThreadID>::iterator threads = activeThreads->begin();
668 list<ThreadID>::iterator end = activeThreads->end();
669
670 while (threads != end) {
671 ThreadID tid = *threads++;
672
673 if (!skidBuffer[tid].empty())
674 return false;
675 }
676
677 return true;
678}
679
680template <class Impl>
681void
682DefaultIEW<Impl>::updateStatus()
683{
684 bool any_unblocking = false;
685
686 list<ThreadID>::iterator threads = activeThreads->begin();
687 list<ThreadID>::iterator end = activeThreads->end();
688
689 while (threads != end) {
690 ThreadID tid = *threads++;
691
692 if (dispatchStatus[tid] == Unblocking) {
693 any_unblocking = true;
694 break;
695 }
696 }
697
698 // If there are no ready instructions waiting to be scheduled by the IQ,
699 // and there's no stores waiting to write back, and dispatch is not
700 // unblocking, then there is no internal activity for the IEW stage.
701 instQueue.intInstQueueReads++;
702 if (_status == Active && !instQueue.hasReadyInsts() &&
703 !ldstQueue.willWB() && !any_unblocking) {
704 DPRINTF(IEW, "IEW switching to idle\n");
705
706 deactivateStage();
707
708 _status = Inactive;
709 } else if (_status == Inactive && (instQueue.hasReadyInsts() ||
710 ldstQueue.willWB() ||
711 any_unblocking)) {
712 // Otherwise there is internal activity. Set to active.
713 DPRINTF(IEW, "IEW switching to active\n");
714
715 activateStage();
716
717 _status = Active;
718 }
719}
720
721template <class Impl>
722void
723DefaultIEW<Impl>::resetEntries()
724{
725 instQueue.resetEntries();
726 ldstQueue.resetEntries();
727}
728
729template <class Impl>
730void
731DefaultIEW<Impl>::readStallSignals(ThreadID tid)
732{
733 if (fromCommit->commitBlock[tid]) {
734 stalls[tid].commit = true;
735 }
736
737 if (fromCommit->commitUnblock[tid]) {
738 assert(stalls[tid].commit);
739 stalls[tid].commit = false;
740 }
741}
742
743template <class Impl>
744bool
745DefaultIEW<Impl>::checkStall(ThreadID tid)
746{
747 bool ret_val(false);
748
749 if (stalls[tid].commit) {
750 DPRINTF(IEW,"[tid:%i]: Stall from Commit stage detected.\n",tid);
751 ret_val = true;
752 } else if (instQueue.isFull(tid)) {
753 DPRINTF(IEW,"[tid:%i]: Stall: IQ is full.\n",tid);
754 ret_val = true;
755 } else if (ldstQueue.isFull(tid)) {
756 DPRINTF(IEW,"[tid:%i]: Stall: LSQ is full\n",tid);
757
758 if (ldstQueue.numLoads(tid) > 0 ) {
759
760 DPRINTF(IEW,"[tid:%i]: LSQ oldest load: [sn:%i] \n",
761 tid,ldstQueue.getLoadHeadSeqNum(tid));
762 }
763
764 if (ldstQueue.numStores(tid) > 0) {
765
766 DPRINTF(IEW,"[tid:%i]: LSQ oldest store: [sn:%i] \n",
767 tid,ldstQueue.getStoreHeadSeqNum(tid));
768 }
769
770 ret_val = true;
771 } else if (ldstQueue.isStalled(tid)) {
772 DPRINTF(IEW,"[tid:%i]: Stall: LSQ stall detected.\n",tid);
773 ret_val = true;
774 }
775
776 return ret_val;
777}
778
779template <class Impl>
780void
781DefaultIEW<Impl>::checkSignalsAndUpdate(ThreadID tid)
782{
783 // Check if there's a squash signal, squash if there is
784 // Check stall signals, block if there is.
785 // If status was Blocked
786 // if so then go to unblocking
787 // If status was Squashing
788 // check if squashing is not high. Switch to running this cycle.
789
790 readStallSignals(tid);
791
792 if (fromCommit->commitInfo[tid].squash) {
793 squash(tid);
794
795 if (dispatchStatus[tid] == Blocked ||
796 dispatchStatus[tid] == Unblocking) {
797 toRename->iewUnblock[tid] = true;
798 wroteToTimeBuffer = true;
799 }
800
801 dispatchStatus[tid] = Squashing;
802 fetchRedirect[tid] = false;
803 return;
804 }
805
806 if (fromCommit->commitInfo[tid].robSquashing) {
807 DPRINTF(IEW, "[tid:%i]: ROB is still squashing.\n", tid);
808
809 dispatchStatus[tid] = Squashing;
810 emptyRenameInsts(tid);
811 wroteToTimeBuffer = true;
812 return;
813 }
814
815 if (checkStall(tid)) {
816 block(tid);
817 dispatchStatus[tid] = Blocked;
818 return;
819 }
820
821 if (dispatchStatus[tid] == Blocked) {
822 // Status from previous cycle was blocked, but there are no more stall
823 // conditions. Switch over to unblocking.
824 DPRINTF(IEW, "[tid:%i]: Done blocking, switching to unblocking.\n",
825 tid);
826
827 dispatchStatus[tid] = Unblocking;
828
829 unblock(tid);
830
831 return;
832 }
833
834 if (dispatchStatus[tid] == Squashing) {
835 // Switch status to running if rename isn't being told to block or
836 // squash this cycle.
837 DPRINTF(IEW, "[tid:%i]: Done squashing, switching to running.\n",
838 tid);
839
840 dispatchStatus[tid] = Running;
841
842 return;
843 }
844}
845
846template <class Impl>
847void
848DefaultIEW<Impl>::sortInsts()
849{
850 int insts_from_rename = fromRename->size;
851#ifdef DEBUG
852 for (ThreadID tid = 0; tid < numThreads; tid++)
853 assert(insts[tid].empty());
854#endif
855 for (int i = 0; i < insts_from_rename; ++i) {
856 insts[fromRename->insts[i]->threadNumber].push(fromRename->insts[i]);
857 }
858}
859
860template <class Impl>
861void
862DefaultIEW<Impl>::emptyRenameInsts(ThreadID tid)
863{
864 DPRINTF(IEW, "[tid:%i]: Removing incoming rename instructions\n", tid);
865
866 while (!insts[tid].empty()) {
867
868 if (insts[tid].front()->isLoad() ||
869 insts[tid].front()->isStore() ) {
870 toRename->iewInfo[tid].dispatchedToLSQ++;
871 }
872
873 toRename->iewInfo[tid].dispatched++;
874
875 insts[tid].pop();
876 }
877}
878
879template <class Impl>
880void
881DefaultIEW<Impl>::wakeCPU()
882{
883 cpu->wakeCPU();
884}
885
886template <class Impl>
887void
888DefaultIEW<Impl>::activityThisCycle()
889{
890 DPRINTF(Activity, "Activity this cycle.\n");
891 cpu->activityThisCycle();
892}
893
894template <class Impl>
895inline void
896DefaultIEW<Impl>::activateStage()
897{
898 DPRINTF(Activity, "Activating stage.\n");
899 cpu->activateStage(O3CPU::IEWIdx);
900}
901
902template <class Impl>
903inline void
904DefaultIEW<Impl>::deactivateStage()
905{
906 DPRINTF(Activity, "Deactivating stage.\n");
907 cpu->deactivateStage(O3CPU::IEWIdx);
908}
909
910template<class Impl>
911void
912DefaultIEW<Impl>::dispatch(ThreadID tid)
913{
914 // If status is Running or idle,
915 // call dispatchInsts()
916 // If status is Unblocking,
917 // buffer any instructions coming from rename
918 // continue trying to empty skid buffer
919 // check if stall conditions have passed
920
921 if (dispatchStatus[tid] == Blocked) {
922 ++iewBlockCycles;
923
924 } else if (dispatchStatus[tid] == Squashing) {
925 ++iewSquashCycles;
926 }
927
928 // Dispatch should try to dispatch as many instructions as its bandwidth
929 // will allow, as long as it is not currently blocked.
930 if (dispatchStatus[tid] == Running ||
931 dispatchStatus[tid] == Idle) {
932 DPRINTF(IEW, "[tid:%i] Not blocked, so attempting to run "
933 "dispatch.\n", tid);
934
935 dispatchInsts(tid);
936 } else if (dispatchStatus[tid] == Unblocking) {
937 // Make sure that the skid buffer has something in it if the
938 // status is unblocking.
939 assert(!skidsEmpty());
940
941 // If the status was unblocking, then instructions from the skid
942 // buffer were used. Remove those instructions and handle
943 // the rest of unblocking.
944 dispatchInsts(tid);
945
946 ++iewUnblockCycles;
947
948 if (validInstsFromRename()) {
949 // Add the current inputs to the skid buffer so they can be
950 // reprocessed when this stage unblocks.
951 skidInsert(tid);
952 }
953
954 unblock(tid);
955 }
956}
957
958template <class Impl>
959void
960DefaultIEW<Impl>::dispatchInsts(ThreadID tid)
961{
962 // Obtain instructions from skid buffer if unblocking, or queue from rename
963 // otherwise.
964 std::queue<DynInstPtr> &insts_to_dispatch =
965 dispatchStatus[tid] == Unblocking ?
966 skidBuffer[tid] : insts[tid];
967
968 int insts_to_add = insts_to_dispatch.size();
969
970 DynInstPtr inst;
971 bool add_to_iq = false;
972 int dis_num_inst = 0;
973
974 // Loop through the instructions, putting them in the instruction
975 // queue.
976 for ( ; dis_num_inst < insts_to_add &&
977 dis_num_inst < dispatchWidth;
978 ++dis_num_inst)
979 {
980 inst = insts_to_dispatch.front();
981
982 if (dispatchStatus[tid] == Unblocking) {
983 DPRINTF(IEW, "[tid:%i]: Issue: Examining instruction from skid "
984 "buffer\n", tid);
985 }
986
987 // Make sure there's a valid instruction there.
988 assert(inst);
989
990 DPRINTF(IEW, "[tid:%i]: Issue: Adding PC %s [sn:%lli] [tid:%i] to "
991 "IQ.\n",
992 tid, inst->pcState(), inst->seqNum, inst->threadNumber);
993
994 // Be sure to mark these instructions as ready so that the
995 // commit stage can go ahead and execute them, and mark
996 // them as issued so the IQ doesn't reprocess them.
997
998 // Check for squashed instructions.
999 if (inst->isSquashed()) {
1000 DPRINTF(IEW, "[tid:%i]: Issue: Squashed instruction encountered, "
1001 "not adding to IQ.\n", tid);
1002
1003 ++iewDispSquashedInsts;
1004
1005 insts_to_dispatch.pop();
1006
1007 //Tell Rename That An Instruction has been processed
1008 if (inst->isLoad() || inst->isStore()) {
1009 toRename->iewInfo[tid].dispatchedToLSQ++;
1010 }
1011 toRename->iewInfo[tid].dispatched++;
1012
1013 continue;
1014 }
1015
1016 // Check for full conditions.
1017 if (instQueue.isFull(tid)) {
1018 DPRINTF(IEW, "[tid:%i]: Issue: IQ has become full.\n", tid);
1019
1020 // Call function to start blocking.
1021 block(tid);
1022
1023 // Set unblock to false. Special case where we are using
1024 // skidbuffer (unblocking) instructions but then we still
1025 // get full in the IQ.
1026 toRename->iewUnblock[tid] = false;
1027
1028 ++iewIQFullEvents;
1029 break;
1030 } else if (ldstQueue.isFull(tid)) {
1031 DPRINTF(IEW, "[tid:%i]: Issue: LSQ has become full.\n",tid);
1032
1033 // Call function to start blocking.
1034 block(tid);
1035
1036 // Set unblock to false. Special case where we are using
1037 // skidbuffer (unblocking) instructions but then we still
1038 // get full in the IQ.
1039 toRename->iewUnblock[tid] = false;
1040
1041 ++iewLSQFullEvents;
1042 break;
1043 }
1044
1045 // Otherwise issue the instruction just fine.
1046 if (inst->isLoad()) {
1047 DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1048 "encountered, adding to LSQ.\n", tid);
1049
1050 // Reserve a spot in the load store queue for this
1051 // memory access.
1052 ldstQueue.insertLoad(inst);
1053
1054 ++iewDispLoadInsts;
1055
1056 add_to_iq = true;
1057
1058 toRename->iewInfo[tid].dispatchedToLSQ++;
1059 } else if (inst->isStore()) {
1060 DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1061 "encountered, adding to LSQ.\n", tid);
1062
1063 ldstQueue.insertStore(inst);
1064
1065 ++iewDispStoreInsts;
1066
1067 if (inst->isStoreConditional()) {
1068 // Store conditionals need to be set as "canCommit()"
1069 // so that commit can process them when they reach the
1070 // head of commit.
1071 // @todo: This is somewhat specific to Alpha.
1072 inst->setCanCommit();
1073 instQueue.insertNonSpec(inst);
1074 add_to_iq = false;
1075
1076 ++iewDispNonSpecInsts;
1077 } else {
1078 add_to_iq = true;
1079 }
1080
1081 toRename->iewInfo[tid].dispatchedToLSQ++;
1082 } else if (inst->isMemBarrier() || inst->isWriteBarrier()) {
1083 // Same as non-speculative stores.
1084 inst->setCanCommit();
1085 instQueue.insertBarrier(inst);
1086 add_to_iq = false;
1087 } else if (inst->isNop()) {
1088 DPRINTF(IEW, "[tid:%i]: Issue: Nop instruction encountered, "
1089 "skipping.\n", tid);
1090
1091 inst->setIssued();
1092 inst->setExecuted();
1093 inst->setCanCommit();
1094
1095 instQueue.recordProducer(inst);
1096
1097 iewExecutedNop[tid]++;
1098
1099 add_to_iq = false;
1100 } else if (inst->isExecuted()) {
1101 assert(0 && "Instruction shouldn't be executed.\n");
1102 DPRINTF(IEW, "Issue: Executed branch encountered, "
1103 "skipping.\n");
1104
1105 inst->setIssued();
1106 inst->setCanCommit();
1107
1108 instQueue.recordProducer(inst);
1109
1110 add_to_iq = false;
1111 } else {
1112 add_to_iq = true;
1113 }
1114 if (inst->isNonSpeculative()) {
1115 DPRINTF(IEW, "[tid:%i]: Issue: Nonspeculative instruction "
1116 "encountered, skipping.\n", tid);
1117
1118 // Same as non-speculative stores.
1119 inst->setCanCommit();
1120
1121 // Specifically insert it as nonspeculative.
1122 instQueue.insertNonSpec(inst);
1123
1124 ++iewDispNonSpecInsts;
1125
1126 add_to_iq = false;
1127 }
1128
1129 // If the instruction queue is not full, then add the
1130 // instruction.
1131 if (add_to_iq) {
1132 instQueue.insert(inst);
1133 }
1134
1135 insts_to_dispatch.pop();
1136
1137 toRename->iewInfo[tid].dispatched++;
1138
1139 ++iewDispatchedInsts;
1140 }
1141
1142 if (!insts_to_dispatch.empty()) {
1143 DPRINTF(IEW,"[tid:%i]: Issue: Bandwidth Full. Blocking.\n", tid);
1144 block(tid);
1145 toRename->iewUnblock[tid] = false;
1146 }
1147
1148 if (dispatchStatus[tid] == Idle && dis_num_inst) {
1149 dispatchStatus[tid] = Running;
1150
1151 updatedQueues = true;
1152 }
1153
1154 dis_num_inst = 0;
1155}
1156
1157template <class Impl>
1158void
1159DefaultIEW<Impl>::printAvailableInsts()
1160{
1161 int inst = 0;
1162
1163 std::cout << "Available Instructions: ";
1164
1165 while (fromIssue->insts[inst]) {
1166
1167 if (inst%3==0) std::cout << "\n\t";
1168
1169 std::cout << "PC: " << fromIssue->insts[inst]->pcState()
1170 << " TN: " << fromIssue->insts[inst]->threadNumber
1171 << " SN: " << fromIssue->insts[inst]->seqNum << " | ";
1172
1173 inst++;
1174
1175 }
1176
1177 std::cout << "\n";
1178}
1179
1180template <class Impl>
1181void
1182DefaultIEW<Impl>::executeInsts()
1183{
1184 wbNumInst = 0;
1185 wbCycle = 0;
1186
1187 list<ThreadID>::iterator threads = activeThreads->begin();
1188 list<ThreadID>::iterator end = activeThreads->end();
1189
1190 while (threads != end) {
1191 ThreadID tid = *threads++;
1192 fetchRedirect[tid] = false;
1193 }
1194
1195 // Uncomment this if you want to see all available instructions.
1196 // @todo This doesn't actually work anymore, we should fix it.
1197// printAvailableInsts();
1198
1199 // Execute/writeback any instructions that are available.
1200 int insts_to_execute = fromIssue->size;
1201 int inst_num = 0;
1202 for (; inst_num < insts_to_execute;
1203 ++inst_num) {
1204
1205 DPRINTF(IEW, "Execute: Executing instructions from IQ.\n");
1206
1207 DynInstPtr inst = instQueue.getInstToExecute();
1208
1209 DPRINTF(IEW, "Execute: Processing PC %s, [tid:%i] [sn:%i].\n",
1210 inst->pcState(), inst->threadNumber,inst->seqNum);
1211
1212 // Check if the instruction is squashed; if so then skip it
1213 if (inst->isSquashed()) {
1214 DPRINTF(IEW, "Execute: Instruction was squashed.\n");
1215
1216 // Consider this instruction executed so that commit can go
1217 // ahead and retire the instruction.
1218 inst->setExecuted();
1219
1220 // Not sure if I should set this here or just let commit try to
1221 // commit any squashed instructions. I like the latter a bit more.
1222 inst->setCanCommit();
1223
1224 ++iewExecSquashedInsts;
1225
1226 decrWb(inst->seqNum);
1227 continue;
1228 }
1229
1230 Fault fault = NoFault;
1231
1232 // Execute instruction.
1233 // Note that if the instruction faults, it will be handled
1234 // at the commit stage.
1235 if (inst->isMemRef()) {
1236 DPRINTF(IEW, "Execute: Calculating address for memory "
1237 "reference.\n");
1238
1239 // Tell the LDSTQ to execute this instruction (if it is a load).
1240 if (inst->isLoad()) {
1241 // Loads will mark themselves as executed, and their writeback
1242 // event adds the instruction to the queue to commit
1243 fault = ldstQueue.executeLoad(inst);
1244
1245 if (inst->isTranslationDelayed() &&
1246 fault == NoFault) {
1247 // A hw page table walk is currently going on; the
1248 // instruction must be deferred.
1249 DPRINTF(IEW, "Execute: Delayed translation, deferring "
1250 "load.\n");
1251 instQueue.deferMemInst(inst);
1252 continue;
1253 }
1254
1255 if (inst->isDataPrefetch() || inst->isInstPrefetch()) {
1256 inst->fault = NoFault;
1257 }
1258 } else if (inst->isStore()) {
1259 fault = ldstQueue.executeStore(inst);
1260
1261 if (inst->isTranslationDelayed() &&
1262 fault == NoFault) {
1263 // A hw page table walk is currently going on; the
1264 // instruction must be deferred.
1265 DPRINTF(IEW, "Execute: Delayed translation, deferring "
1266 "store.\n");
1267 instQueue.deferMemInst(inst);
1268 continue;
1269 }
1270
1271 // If the store had a fault then it may not have a mem req
1272 if (fault != NoFault || inst->readPredicate() == false ||
1273 !inst->isStoreConditional()) {
1274 // If the instruction faulted, then we need to send it along
1275 // to commit without the instruction completing.
1276 // Send this instruction to commit, also make sure iew stage
1277 // realizes there is activity.
1278 inst->setExecuted();
1279 instToCommit(inst);
1280 activityThisCycle();
1281 }
1282
1283 // Store conditionals will mark themselves as
1284 // executed, and their writeback event will add the
1285 // instruction to the queue to commit.
1286 } else {
1287 panic("Unexpected memory type!\n");
1288 }
1289
1290 } else {
1291 // If the instruction has already faulted, then skip executing it.
1292 // Such case can happen when it faulted during ITLB translation.
1293 // If we execute the instruction (even if it's a nop) the fault
1294 // will be replaced and we will lose it.
1295 if (inst->getFault() == NoFault) {
1296 inst->execute();
1297 if (inst->readPredicate() == false)
1298 inst->forwardOldRegs();
1299 }
1300
1301 inst->setExecuted();
1302
1303 instToCommit(inst);
1304 }
1305
1306 updateExeInstStats(inst);
1307
1308 // Check if branch prediction was correct, if not then we need
1309 // to tell commit to squash in flight instructions. Only
1310 // handle this if there hasn't already been something that
1311 // redirects fetch in this group of instructions.
1312
1313 // This probably needs to prioritize the redirects if a different
1314 // scheduler is used. Currently the scheduler schedules the oldest
1315 // instruction first, so the branch resolution order will be correct.
1316 ThreadID tid = inst->threadNumber;
1317
1318 if (!fetchRedirect[tid] ||
1319 !toCommit->squash[tid] ||
1320 toCommit->squashedSeqNum[tid] > inst->seqNum) {
1321
1322 // Prevent testing for misprediction on load instructions,
1323 // that have not been executed.
1324 bool loadNotExecuted = !inst->isExecuted() && inst->isLoad();
1325
1326 if (inst->mispredicted() && !loadNotExecuted) {
1327 fetchRedirect[tid] = true;
1328
1329 DPRINTF(IEW, "Execute: Branch mispredict detected.\n");
1330 DPRINTF(IEW, "Predicted target was PC:%#x, NPC:%#x.\n",
1331 inst->predInstAddr(), inst->predNextInstAddr());
1332 DPRINTF(IEW, "Execute: Redirecting fetch to PC: %s.\n",
1333 inst->pcState(), inst->nextInstAddr());
1334 // If incorrect, then signal the ROB that it must be squashed.
1335 squashDueToBranch(inst, tid);
1336
1337 if (inst->readPredTaken()) {
1338 predictedTakenIncorrect++;
1339 } else {
1340 predictedNotTakenIncorrect++;
1341 }
1342 } else if (ldstQueue.violation(tid)) {
1343 assert(inst->isMemRef());
1344 // If there was an ordering violation, then get the
1345 // DynInst that caused the violation. Note that this
1346 // clears the violation signal.
1347 DynInstPtr violator;
1348 violator = ldstQueue.getMemDepViolator(tid);
1349
1350 DPRINTF(IEW, "LDSTQ detected a violation. Violator PC: %s "
1351 "[sn:%lli], inst PC: %s [sn:%lli]. Addr is: %#x.\n",
1352 violator->pcState(), violator->seqNum,
1353 inst->pcState(), inst->seqNum, inst->physEffAddr);
1354
1355 fetchRedirect[tid] = true;
1356
1357 // Tell the instruction queue that a violation has occured.
1358 instQueue.violation(inst, violator);
1359
1360 // Squash.
1361 squashDueToMemOrder(inst,tid);
1362
1363 ++memOrderViolationEvents;
1364 } else if (ldstQueue.loadBlocked(tid) &&
1365 !ldstQueue.isLoadBlockedHandled(tid)) {
1366 fetchRedirect[tid] = true;
1367
1368 DPRINTF(IEW, "Load operation couldn't execute because the "
1369 "memory system is blocked. PC: %s [sn:%lli]\n",
1370 inst->pcState(), inst->seqNum);
1371
1372 squashDueToMemBlocked(inst, tid);
1373 }
1374 } else {
1375 // Reset any state associated with redirects that will not
1376 // be used.
1377 if (ldstQueue.violation(tid)) {
1378 assert(inst->isMemRef());
1379
1380 DynInstPtr violator = ldstQueue.getMemDepViolator(tid);
1381
1382 DPRINTF(IEW, "LDSTQ detected a violation. Violator PC: "
1383 "%s, inst PC: %s. Addr is: %#x.\n",
1384 violator->pcState(), inst->pcState(),
1385 inst->physEffAddr);
1386 DPRINTF(IEW, "Violation will not be handled because "
1387 "already squashing\n");
1388
1389 ++memOrderViolationEvents;
1390 }
1391 if (ldstQueue.loadBlocked(tid) &&
1392 !ldstQueue.isLoadBlockedHandled(tid)) {
1393 DPRINTF(IEW, "Load operation couldn't execute because the "
1394 "memory system is blocked. PC: %s [sn:%lli]\n",
1395 inst->pcState(), inst->seqNum);
1396 DPRINTF(IEW, "Blocked load will not be handled because "
1397 "already squashing\n");
1398
1399 ldstQueue.setLoadBlockedHandled(tid);
1400 }
1401
1402 }
1403 }
1404
1405 // Update and record activity if we processed any instructions.
1406 if (inst_num) {
1407 if (exeStatus == Idle) {
1408 exeStatus = Running;
1409 }
1410
1411 updatedQueues = true;
1412
1413 cpu->activityThisCycle();
1414 }
1415
1416 // Need to reset this in case a writeback event needs to write into the
1417 // iew queue. That way the writeback event will write into the correct
1418 // spot in the queue.
1419 wbNumInst = 0;
1420
1421}
1422
1423template <class Impl>
1424void
1425DefaultIEW<Impl>::writebackInsts()
1426{
1427 // Loop through the head of the time buffer and wake any
1428 // dependents. These instructions are about to write back. Also
1429 // mark scoreboard that this instruction is finally complete.
1430 // Either have IEW have direct access to scoreboard, or have this
1431 // as part of backwards communication.
1432 for (int inst_num = 0; inst_num < wbWidth &&
1433 toCommit->insts[inst_num]; inst_num++) {
1434 DynInstPtr inst = toCommit->insts[inst_num];
1435 ThreadID tid = inst->threadNumber;
1436
1437 DPRINTF(IEW, "Sending instructions to commit, [sn:%lli] PC %s.\n",
1438 inst->seqNum, inst->pcState());
1439
1440 iewInstsToCommit[tid]++;
1441
1442 // Some instructions will be sent to commit without having
1443 // executed because they need commit to handle them.
1444 // E.g. Uncached loads have not actually executed when they
1445 // are first sent to commit. Instead commit must tell the LSQ
1446 // when it's ready to execute the uncached load.
1447 if (!inst->isSquashed() && inst->isExecuted() && inst->getFault() == NoFault) {
1448 int dependents = instQueue.wakeDependents(inst);
1449
1450 for (int i = 0; i < inst->numDestRegs(); i++) {
1451 //mark as Ready
1452 DPRINTF(IEW,"Setting Destination Register %i\n",
1453 inst->renamedDestRegIdx(i));
1454 scoreboard->setReg(inst->renamedDestRegIdx(i));
1455 }
1456
1457 if (dependents) {
1458 producerInst[tid]++;
1459 consumerInst[tid]+= dependents;
1460 }
1461 writebackCount[tid]++;
1462 }
1463
1464 decrWb(inst->seqNum);
1465 }
1466}
1467
1468template<class Impl>
1469void
1470DefaultIEW<Impl>::tick()
1471{
1472 wbNumInst = 0;
1473 wbCycle = 0;
1474
1475 wroteToTimeBuffer = false;
1476 updatedQueues = false;
1477
1478 sortInsts();
1479
1480 // Free function units marked as being freed this cycle.
1481 fuPool->processFreeUnits();
1482
1483 list<ThreadID>::iterator threads = activeThreads->begin();
1484 list<ThreadID>::iterator end = activeThreads->end();
1485
1486 // Check stall and squash signals, dispatch any instructions.
1487 while (threads != end) {
1488 ThreadID tid = *threads++;
1489
1490 DPRINTF(IEW,"Issue: Processing [tid:%i]\n",tid);
1491
1492 checkSignalsAndUpdate(tid);
1493 dispatch(tid);
1494 }
1495
1496 if (exeStatus != Squashing) {
1497 executeInsts();
1498
1499 writebackInsts();
1500
1501 // Have the instruction queue try to schedule any ready instructions.
1502 // (In actuality, this scheduling is for instructions that will
1503 // be executed next cycle.)
1504 instQueue.scheduleReadyInsts();
1505
1506 // Also should advance its own time buffers if the stage ran.
1507 // Not the best place for it, but this works (hopefully).
1508 issueToExecQueue.advance();
1509 }
1510
1511 bool broadcast_free_entries = false;
1512
1513 if (updatedQueues || exeStatus == Running || updateLSQNextCycle) {
1514 exeStatus = Idle;
1515 updateLSQNextCycle = false;
1516
1517 broadcast_free_entries = true;
1518 }
1519
1520 // Writeback any stores using any leftover bandwidth.
1521 ldstQueue.writebackStores();
1522
1523 // Check the committed load/store signals to see if there's a load
1524 // or store to commit. Also check if it's being told to execute a
1525 // nonspeculative instruction.
1526 // This is pretty inefficient...
1527
1528 threads = activeThreads->begin();
1529 while (threads != end) {
1530 ThreadID tid = (*threads++);
1531
1532 DPRINTF(IEW,"Processing [tid:%i]\n",tid);
1533
1534 // Update structures based on instructions committed.
1535 if (fromCommit->commitInfo[tid].doneSeqNum != 0 &&
1536 !fromCommit->commitInfo[tid].squash &&
1537 !fromCommit->commitInfo[tid].robSquashing) {
1538
1539 ldstQueue.commitStores(fromCommit->commitInfo[tid].doneSeqNum,tid);
1540
1541 ldstQueue.commitLoads(fromCommit->commitInfo[tid].doneSeqNum,tid);
1542
1543 updateLSQNextCycle = true;
1544 instQueue.commit(fromCommit->commitInfo[tid].doneSeqNum,tid);
1545 }
1546
1547 if (fromCommit->commitInfo[tid].nonSpecSeqNum != 0) {
1548
1549 //DPRINTF(IEW,"NonspecInst from thread %i",tid);
1550 if (fromCommit->commitInfo[tid].uncached) {
1551 instQueue.replayMemInst(fromCommit->commitInfo[tid].uncachedLoad);
1552 fromCommit->commitInfo[tid].uncachedLoad->setAtCommit();
1553 } else {
1554 instQueue.scheduleNonSpec(
1555 fromCommit->commitInfo[tid].nonSpecSeqNum);
1556 }
1557 }
1558
1559 if (broadcast_free_entries) {
1560 toFetch->iewInfo[tid].iqCount =
1561 instQueue.getCount(tid);
1562 toFetch->iewInfo[tid].ldstqCount =
1563 ldstQueue.getCount(tid);
1564
1565 toRename->iewInfo[tid].usedIQ = true;
1566 toRename->iewInfo[tid].freeIQEntries =
1567 instQueue.numFreeEntries();
1568 toRename->iewInfo[tid].usedLSQ = true;
1569 toRename->iewInfo[tid].freeLSQEntries =
1570 ldstQueue.numFreeEntries(tid);
1571
1572 wroteToTimeBuffer = true;
1573 }
1574
1575 DPRINTF(IEW, "[tid:%i], Dispatch dispatched %i instructions.\n",
1576 tid, toRename->iewInfo[tid].dispatched);
1577 }
1578
1579 DPRINTF(IEW, "IQ has %i free entries (Can schedule: %i). "
1580 "LSQ has %i free entries.\n",
1581 instQueue.numFreeEntries(), instQueue.hasReadyInsts(),
1582 ldstQueue.numFreeEntries());
1583
1584 updateStatus();
1585
1586 if (wroteToTimeBuffer) {
1587 DPRINTF(Activity, "Activity this cycle.\n");
1588 cpu->activityThisCycle();
1589 }
1590}
1591
1592template <class Impl>
1593void
1594DefaultIEW<Impl>::updateExeInstStats(DynInstPtr &inst)
1595{
1596 ThreadID tid = inst->threadNumber;
1597
1598 //
1599 // Pick off the software prefetches
1600 //
1601#ifdef TARGET_ALPHA
1602 if (inst->isDataPrefetch())
1603 iewExecutedSwp[tid]++;
1604 else
1605 iewIewExecutedcutedInsts++;
1606#else
1607 iewExecutedInsts++;
1608#endif
1609
1610 //
1611 // Control operations
1612 //
1613 if (inst->isControl())
1614 iewExecutedBranches[tid]++;
1615
1616 //
1617 // Memory operations
1618 //
1619 if (inst->isMemRef()) {
1620 iewExecutedRefs[tid]++;
1621
1622 if (inst->isLoad()) {
1623 iewExecLoadInsts[tid]++;
1624 }
1625 }
1626}
1627
1628template <class Impl>
1629void
1630DefaultIEW<Impl>::checkMisprediction(DynInstPtr &inst)
1631{
1632 ThreadID tid = inst->threadNumber;
1633
1634 if (!fetchRedirect[tid] ||
1635 !toCommit->squash[tid] ||
1636 toCommit->squashedSeqNum[tid] > inst->seqNum) {
1637
1638 if (inst->mispredicted()) {
1639 fetchRedirect[tid] = true;
1640
1641 DPRINTF(IEW, "Execute: Branch mispredict detected.\n");
1642 DPRINTF(IEW, "Predicted target was PC:%#x, NPC:%#x.\n",
1643 inst->predInstAddr(), inst->predNextInstAddr());
1644 DPRINTF(IEW, "Execute: Redirecting fetch to PC: %#x,"
1645 " NPC: %#x.\n", inst->nextInstAddr(),
1646 inst->nextInstAddr());
1647 // If incorrect, then signal the ROB that it must be squashed.
1648 squashDueToBranch(inst, tid);
1649
1650 if (inst->readPredTaken()) {
1651 predictedTakenIncorrect++;
1652 } else {
1653 predictedNotTakenIncorrect++;
1654 }
1655 }
1656 }
1657}
2 * Copyright (c) 2010 ARM Limited
3 * All rights reserved.
4 *
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder. You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Copyright (c) 2004-2006 The Regents of The University of Michigan
15 * All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions are
19 * met: redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer;
21 * redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution;
24 * neither the name of the copyright holders nor the names of its
25 * contributors may be used to endorse or promote products derived from
26 * this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 *
40 * Authors: Kevin Lim
41 */
42
43// @todo: Fix the instantaneous communication among all the stages within
44// iew. There's a clear delay between issue and execute, yet backwards
45// communication happens simultaneously.
46
47#include <queue>
48
49#include "cpu/timebuf.hh"
50#include "config/the_isa.hh"
51#include "cpu/o3/fu_pool.hh"
52#include "cpu/o3/iew.hh"
53#include "params/DerivO3CPU.hh"
54
55using namespace std;
56
57template<class Impl>
58DefaultIEW<Impl>::DefaultIEW(O3CPU *_cpu, DerivO3CPUParams *params)
59 : issueToExecQueue(params->backComSize, params->forwardComSize),
60 cpu(_cpu),
61 instQueue(_cpu, this, params),
62 ldstQueue(_cpu, this, params),
63 fuPool(params->fuPool),
64 commitToIEWDelay(params->commitToIEWDelay),
65 renameToIEWDelay(params->renameToIEWDelay),
66 issueToExecuteDelay(params->issueToExecuteDelay),
67 dispatchWidth(params->dispatchWidth),
68 issueWidth(params->issueWidth),
69 wbOutstanding(0),
70 wbWidth(params->wbWidth),
71 numThreads(params->numThreads),
72 switchedOut(false)
73{
74 _status = Active;
75 exeStatus = Running;
76 wbStatus = Idle;
77
78 // Setup wire to read instructions coming from issue.
79 fromIssue = issueToExecQueue.getWire(-issueToExecuteDelay);
80
81 // Instruction queue needs the queue between issue and execute.
82 instQueue.setIssueToExecuteQueue(&issueToExecQueue);
83
84 for (ThreadID tid = 0; tid < numThreads; tid++) {
85 dispatchStatus[tid] = Running;
86 stalls[tid].commit = false;
87 fetchRedirect[tid] = false;
88 }
89
90 wbMax = wbWidth * params->wbDepth;
91
92 updateLSQNextCycle = false;
93
94 ableToIssue = true;
95
96 skidBufferMax = (3 * (renameToIEWDelay * params->renameWidth)) + issueWidth;
97}
98
99template <class Impl>
100std::string
101DefaultIEW<Impl>::name() const
102{
103 return cpu->name() + ".iew";
104}
105
106template <class Impl>
107void
108DefaultIEW<Impl>::regStats()
109{
110 using namespace Stats;
111
112 instQueue.regStats();
113 ldstQueue.regStats();
114
115 iewIdleCycles
116 .name(name() + ".iewIdleCycles")
117 .desc("Number of cycles IEW is idle");
118
119 iewSquashCycles
120 .name(name() + ".iewSquashCycles")
121 .desc("Number of cycles IEW is squashing");
122
123 iewBlockCycles
124 .name(name() + ".iewBlockCycles")
125 .desc("Number of cycles IEW is blocking");
126
127 iewUnblockCycles
128 .name(name() + ".iewUnblockCycles")
129 .desc("Number of cycles IEW is unblocking");
130
131 iewDispatchedInsts
132 .name(name() + ".iewDispatchedInsts")
133 .desc("Number of instructions dispatched to IQ");
134
135 iewDispSquashedInsts
136 .name(name() + ".iewDispSquashedInsts")
137 .desc("Number of squashed instructions skipped by dispatch");
138
139 iewDispLoadInsts
140 .name(name() + ".iewDispLoadInsts")
141 .desc("Number of dispatched load instructions");
142
143 iewDispStoreInsts
144 .name(name() + ".iewDispStoreInsts")
145 .desc("Number of dispatched store instructions");
146
147 iewDispNonSpecInsts
148 .name(name() + ".iewDispNonSpecInsts")
149 .desc("Number of dispatched non-speculative instructions");
150
151 iewIQFullEvents
152 .name(name() + ".iewIQFullEvents")
153 .desc("Number of times the IQ has become full, causing a stall");
154
155 iewLSQFullEvents
156 .name(name() + ".iewLSQFullEvents")
157 .desc("Number of times the LSQ has become full, causing a stall");
158
159 memOrderViolationEvents
160 .name(name() + ".memOrderViolationEvents")
161 .desc("Number of memory order violations");
162
163 predictedTakenIncorrect
164 .name(name() + ".predictedTakenIncorrect")
165 .desc("Number of branches that were predicted taken incorrectly");
166
167 predictedNotTakenIncorrect
168 .name(name() + ".predictedNotTakenIncorrect")
169 .desc("Number of branches that were predicted not taken incorrectly");
170
171 branchMispredicts
172 .name(name() + ".branchMispredicts")
173 .desc("Number of branch mispredicts detected at execute");
174
175 branchMispredicts = predictedTakenIncorrect + predictedNotTakenIncorrect;
176
177 iewExecutedInsts
178 .name(name() + ".iewExecutedInsts")
179 .desc("Number of executed instructions");
180
181 iewExecLoadInsts
182 .init(cpu->numThreads)
183 .name(name() + ".iewExecLoadInsts")
184 .desc("Number of load instructions executed")
185 .flags(total);
186
187 iewExecSquashedInsts
188 .name(name() + ".iewExecSquashedInsts")
189 .desc("Number of squashed instructions skipped in execute");
190
191 iewExecutedSwp
192 .init(cpu->numThreads)
193 .name(name() + ".EXEC:swp")
194 .desc("number of swp insts executed")
195 .flags(total);
196
197 iewExecutedNop
198 .init(cpu->numThreads)
199 .name(name() + ".EXEC:nop")
200 .desc("number of nop insts executed")
201 .flags(total);
202
203 iewExecutedRefs
204 .init(cpu->numThreads)
205 .name(name() + ".EXEC:refs")
206 .desc("number of memory reference insts executed")
207 .flags(total);
208
209 iewExecutedBranches
210 .init(cpu->numThreads)
211 .name(name() + ".EXEC:branches")
212 .desc("Number of branches executed")
213 .flags(total);
214
215 iewExecStoreInsts
216 .name(name() + ".EXEC:stores")
217 .desc("Number of stores executed")
218 .flags(total);
219 iewExecStoreInsts = iewExecutedRefs - iewExecLoadInsts;
220
221 iewExecRate
222 .name(name() + ".EXEC:rate")
223 .desc("Inst execution rate")
224 .flags(total);
225
226 iewExecRate = iewExecutedInsts / cpu->numCycles;
227
228 iewInstsToCommit
229 .init(cpu->numThreads)
230 .name(name() + ".WB:sent")
231 .desc("cumulative count of insts sent to commit")
232 .flags(total);
233
234 writebackCount
235 .init(cpu->numThreads)
236 .name(name() + ".WB:count")
237 .desc("cumulative count of insts written-back")
238 .flags(total);
239
240 producerInst
241 .init(cpu->numThreads)
242 .name(name() + ".WB:producers")
243 .desc("num instructions producing a value")
244 .flags(total);
245
246 consumerInst
247 .init(cpu->numThreads)
248 .name(name() + ".WB:consumers")
249 .desc("num instructions consuming a value")
250 .flags(total);
251
252 wbPenalized
253 .init(cpu->numThreads)
254 .name(name() + ".WB:penalized")
255 .desc("number of instrctions required to write to 'other' IQ")
256 .flags(total);
257
258 wbPenalizedRate
259 .name(name() + ".WB:penalized_rate")
260 .desc ("fraction of instructions written-back that wrote to 'other' IQ")
261 .flags(total);
262
263 wbPenalizedRate = wbPenalized / writebackCount;
264
265 wbFanout
266 .name(name() + ".WB:fanout")
267 .desc("average fanout of values written-back")
268 .flags(total);
269
270 wbFanout = producerInst / consumerInst;
271
272 wbRate
273 .name(name() + ".WB:rate")
274 .desc("insts written-back per cycle")
275 .flags(total);
276 wbRate = writebackCount / cpu->numCycles;
277}
278
279template<class Impl>
280void
281DefaultIEW<Impl>::initStage()
282{
283 for (ThreadID tid = 0; tid < numThreads; tid++) {
284 toRename->iewInfo[tid].usedIQ = true;
285 toRename->iewInfo[tid].freeIQEntries =
286 instQueue.numFreeEntries(tid);
287
288 toRename->iewInfo[tid].usedLSQ = true;
289 toRename->iewInfo[tid].freeLSQEntries =
290 ldstQueue.numFreeEntries(tid);
291 }
292
293 cpu->activateStage(O3CPU::IEWIdx);
294}
295
296template<class Impl>
297void
298DefaultIEW<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr)
299{
300 timeBuffer = tb_ptr;
301
302 // Setup wire to read information from time buffer, from commit.
303 fromCommit = timeBuffer->getWire(-commitToIEWDelay);
304
305 // Setup wire to write information back to previous stages.
306 toRename = timeBuffer->getWire(0);
307
308 toFetch = timeBuffer->getWire(0);
309
310 // Instruction queue also needs main time buffer.
311 instQueue.setTimeBuffer(tb_ptr);
312}
313
314template<class Impl>
315void
316DefaultIEW<Impl>::setRenameQueue(TimeBuffer<RenameStruct> *rq_ptr)
317{
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 iewQueue = iq_ptr;
329
330 // Setup wire to write instructions to commit.
331 toCommit = iewQueue->getWire(0);
332}
333
334template<class Impl>
335void
336DefaultIEW<Impl>::setActiveThreads(list<ThreadID> *at_ptr)
337{
338 activeThreads = at_ptr;
339
340 ldstQueue.setActiveThreads(at_ptr);
341 instQueue.setActiveThreads(at_ptr);
342}
343
344template<class Impl>
345void
346DefaultIEW<Impl>::setScoreboard(Scoreboard *sb_ptr)
347{
348 scoreboard = sb_ptr;
349}
350
351template <class Impl>
352bool
353DefaultIEW<Impl>::drain()
354{
355 // IEW is ready to drain at any time.
356 cpu->signalDrained();
357 return true;
358}
359
360template <class Impl>
361void
362DefaultIEW<Impl>::resume()
363{
364}
365
366template <class Impl>
367void
368DefaultIEW<Impl>::switchOut()
369{
370 // Clear any state.
371 switchedOut = true;
372 assert(insts[0].empty());
373 assert(skidBuffer[0].empty());
374
375 instQueue.switchOut();
376 ldstQueue.switchOut();
377 fuPool->switchOut();
378
379 for (ThreadID tid = 0; tid < numThreads; tid++) {
380 while (!insts[tid].empty())
381 insts[tid].pop();
382 while (!skidBuffer[tid].empty())
383 skidBuffer[tid].pop();
384 }
385}
386
387template <class Impl>
388void
389DefaultIEW<Impl>::takeOverFrom()
390{
391 // Reset all state.
392 _status = Active;
393 exeStatus = Running;
394 wbStatus = Idle;
395 switchedOut = false;
396
397 instQueue.takeOverFrom();
398 ldstQueue.takeOverFrom();
399 fuPool->takeOverFrom();
400
401 initStage();
402 cpu->activityThisCycle();
403
404 for (ThreadID tid = 0; tid < numThreads; tid++) {
405 dispatchStatus[tid] = Running;
406 stalls[tid].commit = false;
407 fetchRedirect[tid] = false;
408 }
409
410 updateLSQNextCycle = false;
411
412 for (int i = 0; i < issueToExecQueue.getSize(); ++i) {
413 issueToExecQueue.advance();
414 }
415}
416
417template<class Impl>
418void
419DefaultIEW<Impl>::squash(ThreadID tid)
420{
421 DPRINTF(IEW, "[tid:%i]: Squashing all instructions.\n", tid);
422
423 // Tell the IQ to start squashing.
424 instQueue.squash(tid);
425
426 // Tell the LDSTQ to start squashing.
427 ldstQueue.squash(fromCommit->commitInfo[tid].doneSeqNum, tid);
428 updatedQueues = true;
429
430 // Clear the skid buffer in case it has any data in it.
431 DPRINTF(IEW, "[tid:%i]: Removing skidbuffer instructions until [sn:%i].\n",
432 tid, fromCommit->commitInfo[tid].doneSeqNum);
433
434 while (!skidBuffer[tid].empty()) {
435 if (skidBuffer[tid].front()->isLoad() ||
436 skidBuffer[tid].front()->isStore() ) {
437 toRename->iewInfo[tid].dispatchedToLSQ++;
438 }
439
440 toRename->iewInfo[tid].dispatched++;
441
442 skidBuffer[tid].pop();
443 }
444
445 emptyRenameInsts(tid);
446}
447
448template<class Impl>
449void
450DefaultIEW<Impl>::squashDueToBranch(DynInstPtr &inst, ThreadID tid)
451{
452 DPRINTF(IEW, "[tid:%i]: Squashing from a specific instruction, PC: %s "
453 "[sn:%i].\n", tid, inst->pcState(), inst->seqNum);
454
455 if (toCommit->squash[tid] == false ||
456 inst->seqNum < toCommit->squashedSeqNum[tid]) {
457 toCommit->squash[tid] = true;
458 toCommit->squashedSeqNum[tid] = inst->seqNum;
459 toCommit->mispredPC[tid] = inst->instAddr();
460 toCommit->branchMispredict[tid] = true;
461 toCommit->branchTaken[tid] = inst->pcState().branching();
462
463 TheISA::PCState pc = inst->pcState();
464 TheISA::advancePC(pc, inst->staticInst);
465
466 toCommit->pc[tid] = pc;
467 toCommit->mispredictInst[tid] = inst;
468 toCommit->includeSquashInst[tid] = false;
469
470 wroteToTimeBuffer = true;
471 }
472
473}
474
475template<class Impl>
476void
477DefaultIEW<Impl>::squashDueToMemOrder(DynInstPtr &inst, ThreadID tid)
478{
479 DPRINTF(IEW, "[tid:%i]: Squashing from a specific instruction, "
480 "PC: %s [sn:%i].\n", tid, inst->pcState(), inst->seqNum);
481
482 if (toCommit->squash[tid] == false ||
483 inst->seqNum < toCommit->squashedSeqNum[tid]) {
484 toCommit->squash[tid] = true;
485 toCommit->squashedSeqNum[tid] = inst->seqNum;
486 TheISA::PCState pc = inst->pcState();
487 TheISA::advancePC(pc, inst->staticInst);
488 toCommit->pc[tid] = pc;
489 toCommit->branchMispredict[tid] = false;
490
491 toCommit->includeSquashInst[tid] = false;
492
493 wroteToTimeBuffer = true;
494 }
495}
496
497template<class Impl>
498void
499DefaultIEW<Impl>::squashDueToMemBlocked(DynInstPtr &inst, ThreadID tid)
500{
501 DPRINTF(IEW, "[tid:%i]: Memory blocked, squashing load and younger insts, "
502 "PC: %s [sn:%i].\n", tid, inst->pcState(), inst->seqNum);
503 if (toCommit->squash[tid] == false ||
504 inst->seqNum < toCommit->squashedSeqNum[tid]) {
505 toCommit->squash[tid] = true;
506
507 toCommit->squashedSeqNum[tid] = inst->seqNum;
508 toCommit->pc[tid] = inst->pcState();
509 toCommit->branchMispredict[tid] = false;
510
511 // Must include the broadcasted SN in the squash.
512 toCommit->includeSquashInst[tid] = true;
513
514 ldstQueue.setLoadBlockedHandled(tid);
515
516 wroteToTimeBuffer = true;
517 }
518}
519
520template<class Impl>
521void
522DefaultIEW<Impl>::block(ThreadID tid)
523{
524 DPRINTF(IEW, "[tid:%u]: Blocking.\n", tid);
525
526 if (dispatchStatus[tid] != Blocked &&
527 dispatchStatus[tid] != Unblocking) {
528 toRename->iewBlock[tid] = true;
529 wroteToTimeBuffer = true;
530 }
531
532 // Add the current inputs to the skid buffer so they can be
533 // reprocessed when this stage unblocks.
534 skidInsert(tid);
535
536 dispatchStatus[tid] = Blocked;
537}
538
539template<class Impl>
540void
541DefaultIEW<Impl>::unblock(ThreadID tid)
542{
543 DPRINTF(IEW, "[tid:%i]: Reading instructions out of the skid "
544 "buffer %u.\n",tid, tid);
545
546 // If the skid bufffer is empty, signal back to previous stages to unblock.
547 // Also switch status to running.
548 if (skidBuffer[tid].empty()) {
549 toRename->iewUnblock[tid] = true;
550 wroteToTimeBuffer = true;
551 DPRINTF(IEW, "[tid:%i]: Done unblocking.\n",tid);
552 dispatchStatus[tid] = Running;
553 }
554}
555
556template<class Impl>
557void
558DefaultIEW<Impl>::wakeDependents(DynInstPtr &inst)
559{
560 instQueue.wakeDependents(inst);
561}
562
563template<class Impl>
564void
565DefaultIEW<Impl>::rescheduleMemInst(DynInstPtr &inst)
566{
567 instQueue.rescheduleMemInst(inst);
568}
569
570template<class Impl>
571void
572DefaultIEW<Impl>::replayMemInst(DynInstPtr &inst)
573{
574 instQueue.replayMemInst(inst);
575}
576
577template<class Impl>
578void
579DefaultIEW<Impl>::instToCommit(DynInstPtr &inst)
580{
581 // This function should not be called after writebackInsts in a
582 // single cycle. That will cause problems with an instruction
583 // being added to the queue to commit without being processed by
584 // writebackInsts prior to being sent to commit.
585
586 // First check the time slot that this instruction will write
587 // to. If there are free write ports at the time, then go ahead
588 // and write the instruction to that time. If there are not,
589 // keep looking back to see where's the first time there's a
590 // free slot.
591 while ((*iewQueue)[wbCycle].insts[wbNumInst]) {
592 ++wbNumInst;
593 if (wbNumInst == wbWidth) {
594 ++wbCycle;
595 wbNumInst = 0;
596 }
597
598 assert((wbCycle * wbWidth + wbNumInst) <= wbMax);
599 }
600
601 DPRINTF(IEW, "Current wb cycle: %i, width: %i, numInst: %i\nwbActual:%i\n",
602 wbCycle, wbWidth, wbNumInst, wbCycle * wbWidth + wbNumInst);
603 // Add finished instruction to queue to commit.
604 (*iewQueue)[wbCycle].insts[wbNumInst] = inst;
605 (*iewQueue)[wbCycle].size++;
606}
607
608template <class Impl>
609unsigned
610DefaultIEW<Impl>::validInstsFromRename()
611{
612 unsigned inst_count = 0;
613
614 for (int i=0; i<fromRename->size; i++) {
615 if (!fromRename->insts[i]->isSquashed())
616 inst_count++;
617 }
618
619 return inst_count;
620}
621
622template<class Impl>
623void
624DefaultIEW<Impl>::skidInsert(ThreadID tid)
625{
626 DynInstPtr inst = NULL;
627
628 while (!insts[tid].empty()) {
629 inst = insts[tid].front();
630
631 insts[tid].pop();
632
633 DPRINTF(Decode,"[tid:%i]: Inserting [sn:%lli] PC:%s into "
634 "dispatch skidBuffer %i\n",tid, inst->seqNum,
635 inst->pcState(),tid);
636
637 skidBuffer[tid].push(inst);
638 }
639
640 assert(skidBuffer[tid].size() <= skidBufferMax &&
641 "Skidbuffer Exceeded Max Size");
642}
643
644template<class Impl>
645int
646DefaultIEW<Impl>::skidCount()
647{
648 int max=0;
649
650 list<ThreadID>::iterator threads = activeThreads->begin();
651 list<ThreadID>::iterator end = activeThreads->end();
652
653 while (threads != end) {
654 ThreadID tid = *threads++;
655 unsigned thread_count = skidBuffer[tid].size();
656 if (max < thread_count)
657 max = thread_count;
658 }
659
660 return max;
661}
662
663template<class Impl>
664bool
665DefaultIEW<Impl>::skidsEmpty()
666{
667 list<ThreadID>::iterator threads = activeThreads->begin();
668 list<ThreadID>::iterator end = activeThreads->end();
669
670 while (threads != end) {
671 ThreadID tid = *threads++;
672
673 if (!skidBuffer[tid].empty())
674 return false;
675 }
676
677 return true;
678}
679
680template <class Impl>
681void
682DefaultIEW<Impl>::updateStatus()
683{
684 bool any_unblocking = false;
685
686 list<ThreadID>::iterator threads = activeThreads->begin();
687 list<ThreadID>::iterator end = activeThreads->end();
688
689 while (threads != end) {
690 ThreadID tid = *threads++;
691
692 if (dispatchStatus[tid] == Unblocking) {
693 any_unblocking = true;
694 break;
695 }
696 }
697
698 // If there are no ready instructions waiting to be scheduled by the IQ,
699 // and there's no stores waiting to write back, and dispatch is not
700 // unblocking, then there is no internal activity for the IEW stage.
701 instQueue.intInstQueueReads++;
702 if (_status == Active && !instQueue.hasReadyInsts() &&
703 !ldstQueue.willWB() && !any_unblocking) {
704 DPRINTF(IEW, "IEW switching to idle\n");
705
706 deactivateStage();
707
708 _status = Inactive;
709 } else if (_status == Inactive && (instQueue.hasReadyInsts() ||
710 ldstQueue.willWB() ||
711 any_unblocking)) {
712 // Otherwise there is internal activity. Set to active.
713 DPRINTF(IEW, "IEW switching to active\n");
714
715 activateStage();
716
717 _status = Active;
718 }
719}
720
721template <class Impl>
722void
723DefaultIEW<Impl>::resetEntries()
724{
725 instQueue.resetEntries();
726 ldstQueue.resetEntries();
727}
728
729template <class Impl>
730void
731DefaultIEW<Impl>::readStallSignals(ThreadID tid)
732{
733 if (fromCommit->commitBlock[tid]) {
734 stalls[tid].commit = true;
735 }
736
737 if (fromCommit->commitUnblock[tid]) {
738 assert(stalls[tid].commit);
739 stalls[tid].commit = false;
740 }
741}
742
743template <class Impl>
744bool
745DefaultIEW<Impl>::checkStall(ThreadID tid)
746{
747 bool ret_val(false);
748
749 if (stalls[tid].commit) {
750 DPRINTF(IEW,"[tid:%i]: Stall from Commit stage detected.\n",tid);
751 ret_val = true;
752 } else if (instQueue.isFull(tid)) {
753 DPRINTF(IEW,"[tid:%i]: Stall: IQ is full.\n",tid);
754 ret_val = true;
755 } else if (ldstQueue.isFull(tid)) {
756 DPRINTF(IEW,"[tid:%i]: Stall: LSQ is full\n",tid);
757
758 if (ldstQueue.numLoads(tid) > 0 ) {
759
760 DPRINTF(IEW,"[tid:%i]: LSQ oldest load: [sn:%i] \n",
761 tid,ldstQueue.getLoadHeadSeqNum(tid));
762 }
763
764 if (ldstQueue.numStores(tid) > 0) {
765
766 DPRINTF(IEW,"[tid:%i]: LSQ oldest store: [sn:%i] \n",
767 tid,ldstQueue.getStoreHeadSeqNum(tid));
768 }
769
770 ret_val = true;
771 } else if (ldstQueue.isStalled(tid)) {
772 DPRINTF(IEW,"[tid:%i]: Stall: LSQ stall detected.\n",tid);
773 ret_val = true;
774 }
775
776 return ret_val;
777}
778
779template <class Impl>
780void
781DefaultIEW<Impl>::checkSignalsAndUpdate(ThreadID tid)
782{
783 // Check if there's a squash signal, squash if there is
784 // Check stall signals, block if there is.
785 // If status was Blocked
786 // if so then go to unblocking
787 // If status was Squashing
788 // check if squashing is not high. Switch to running this cycle.
789
790 readStallSignals(tid);
791
792 if (fromCommit->commitInfo[tid].squash) {
793 squash(tid);
794
795 if (dispatchStatus[tid] == Blocked ||
796 dispatchStatus[tid] == Unblocking) {
797 toRename->iewUnblock[tid] = true;
798 wroteToTimeBuffer = true;
799 }
800
801 dispatchStatus[tid] = Squashing;
802 fetchRedirect[tid] = false;
803 return;
804 }
805
806 if (fromCommit->commitInfo[tid].robSquashing) {
807 DPRINTF(IEW, "[tid:%i]: ROB is still squashing.\n", tid);
808
809 dispatchStatus[tid] = Squashing;
810 emptyRenameInsts(tid);
811 wroteToTimeBuffer = true;
812 return;
813 }
814
815 if (checkStall(tid)) {
816 block(tid);
817 dispatchStatus[tid] = Blocked;
818 return;
819 }
820
821 if (dispatchStatus[tid] == Blocked) {
822 // Status from previous cycle was blocked, but there are no more stall
823 // conditions. Switch over to unblocking.
824 DPRINTF(IEW, "[tid:%i]: Done blocking, switching to unblocking.\n",
825 tid);
826
827 dispatchStatus[tid] = Unblocking;
828
829 unblock(tid);
830
831 return;
832 }
833
834 if (dispatchStatus[tid] == Squashing) {
835 // Switch status to running if rename isn't being told to block or
836 // squash this cycle.
837 DPRINTF(IEW, "[tid:%i]: Done squashing, switching to running.\n",
838 tid);
839
840 dispatchStatus[tid] = Running;
841
842 return;
843 }
844}
845
846template <class Impl>
847void
848DefaultIEW<Impl>::sortInsts()
849{
850 int insts_from_rename = fromRename->size;
851#ifdef DEBUG
852 for (ThreadID tid = 0; tid < numThreads; tid++)
853 assert(insts[tid].empty());
854#endif
855 for (int i = 0; i < insts_from_rename; ++i) {
856 insts[fromRename->insts[i]->threadNumber].push(fromRename->insts[i]);
857 }
858}
859
860template <class Impl>
861void
862DefaultIEW<Impl>::emptyRenameInsts(ThreadID tid)
863{
864 DPRINTF(IEW, "[tid:%i]: Removing incoming rename instructions\n", tid);
865
866 while (!insts[tid].empty()) {
867
868 if (insts[tid].front()->isLoad() ||
869 insts[tid].front()->isStore() ) {
870 toRename->iewInfo[tid].dispatchedToLSQ++;
871 }
872
873 toRename->iewInfo[tid].dispatched++;
874
875 insts[tid].pop();
876 }
877}
878
879template <class Impl>
880void
881DefaultIEW<Impl>::wakeCPU()
882{
883 cpu->wakeCPU();
884}
885
886template <class Impl>
887void
888DefaultIEW<Impl>::activityThisCycle()
889{
890 DPRINTF(Activity, "Activity this cycle.\n");
891 cpu->activityThisCycle();
892}
893
894template <class Impl>
895inline void
896DefaultIEW<Impl>::activateStage()
897{
898 DPRINTF(Activity, "Activating stage.\n");
899 cpu->activateStage(O3CPU::IEWIdx);
900}
901
902template <class Impl>
903inline void
904DefaultIEW<Impl>::deactivateStage()
905{
906 DPRINTF(Activity, "Deactivating stage.\n");
907 cpu->deactivateStage(O3CPU::IEWIdx);
908}
909
910template<class Impl>
911void
912DefaultIEW<Impl>::dispatch(ThreadID tid)
913{
914 // If status is Running or idle,
915 // call dispatchInsts()
916 // If status is Unblocking,
917 // buffer any instructions coming from rename
918 // continue trying to empty skid buffer
919 // check if stall conditions have passed
920
921 if (dispatchStatus[tid] == Blocked) {
922 ++iewBlockCycles;
923
924 } else if (dispatchStatus[tid] == Squashing) {
925 ++iewSquashCycles;
926 }
927
928 // Dispatch should try to dispatch as many instructions as its bandwidth
929 // will allow, as long as it is not currently blocked.
930 if (dispatchStatus[tid] == Running ||
931 dispatchStatus[tid] == Idle) {
932 DPRINTF(IEW, "[tid:%i] Not blocked, so attempting to run "
933 "dispatch.\n", tid);
934
935 dispatchInsts(tid);
936 } else if (dispatchStatus[tid] == Unblocking) {
937 // Make sure that the skid buffer has something in it if the
938 // status is unblocking.
939 assert(!skidsEmpty());
940
941 // If the status was unblocking, then instructions from the skid
942 // buffer were used. Remove those instructions and handle
943 // the rest of unblocking.
944 dispatchInsts(tid);
945
946 ++iewUnblockCycles;
947
948 if (validInstsFromRename()) {
949 // Add the current inputs to the skid buffer so they can be
950 // reprocessed when this stage unblocks.
951 skidInsert(tid);
952 }
953
954 unblock(tid);
955 }
956}
957
958template <class Impl>
959void
960DefaultIEW<Impl>::dispatchInsts(ThreadID tid)
961{
962 // Obtain instructions from skid buffer if unblocking, or queue from rename
963 // otherwise.
964 std::queue<DynInstPtr> &insts_to_dispatch =
965 dispatchStatus[tid] == Unblocking ?
966 skidBuffer[tid] : insts[tid];
967
968 int insts_to_add = insts_to_dispatch.size();
969
970 DynInstPtr inst;
971 bool add_to_iq = false;
972 int dis_num_inst = 0;
973
974 // Loop through the instructions, putting them in the instruction
975 // queue.
976 for ( ; dis_num_inst < insts_to_add &&
977 dis_num_inst < dispatchWidth;
978 ++dis_num_inst)
979 {
980 inst = insts_to_dispatch.front();
981
982 if (dispatchStatus[tid] == Unblocking) {
983 DPRINTF(IEW, "[tid:%i]: Issue: Examining instruction from skid "
984 "buffer\n", tid);
985 }
986
987 // Make sure there's a valid instruction there.
988 assert(inst);
989
990 DPRINTF(IEW, "[tid:%i]: Issue: Adding PC %s [sn:%lli] [tid:%i] to "
991 "IQ.\n",
992 tid, inst->pcState(), inst->seqNum, inst->threadNumber);
993
994 // Be sure to mark these instructions as ready so that the
995 // commit stage can go ahead and execute them, and mark
996 // them as issued so the IQ doesn't reprocess them.
997
998 // Check for squashed instructions.
999 if (inst->isSquashed()) {
1000 DPRINTF(IEW, "[tid:%i]: Issue: Squashed instruction encountered, "
1001 "not adding to IQ.\n", tid);
1002
1003 ++iewDispSquashedInsts;
1004
1005 insts_to_dispatch.pop();
1006
1007 //Tell Rename That An Instruction has been processed
1008 if (inst->isLoad() || inst->isStore()) {
1009 toRename->iewInfo[tid].dispatchedToLSQ++;
1010 }
1011 toRename->iewInfo[tid].dispatched++;
1012
1013 continue;
1014 }
1015
1016 // Check for full conditions.
1017 if (instQueue.isFull(tid)) {
1018 DPRINTF(IEW, "[tid:%i]: Issue: IQ has become full.\n", tid);
1019
1020 // Call function to start blocking.
1021 block(tid);
1022
1023 // Set unblock to false. Special case where we are using
1024 // skidbuffer (unblocking) instructions but then we still
1025 // get full in the IQ.
1026 toRename->iewUnblock[tid] = false;
1027
1028 ++iewIQFullEvents;
1029 break;
1030 } else if (ldstQueue.isFull(tid)) {
1031 DPRINTF(IEW, "[tid:%i]: Issue: LSQ has become full.\n",tid);
1032
1033 // Call function to start blocking.
1034 block(tid);
1035
1036 // Set unblock to false. Special case where we are using
1037 // skidbuffer (unblocking) instructions but then we still
1038 // get full in the IQ.
1039 toRename->iewUnblock[tid] = false;
1040
1041 ++iewLSQFullEvents;
1042 break;
1043 }
1044
1045 // Otherwise issue the instruction just fine.
1046 if (inst->isLoad()) {
1047 DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1048 "encountered, adding to LSQ.\n", tid);
1049
1050 // Reserve a spot in the load store queue for this
1051 // memory access.
1052 ldstQueue.insertLoad(inst);
1053
1054 ++iewDispLoadInsts;
1055
1056 add_to_iq = true;
1057
1058 toRename->iewInfo[tid].dispatchedToLSQ++;
1059 } else if (inst->isStore()) {
1060 DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1061 "encountered, adding to LSQ.\n", tid);
1062
1063 ldstQueue.insertStore(inst);
1064
1065 ++iewDispStoreInsts;
1066
1067 if (inst->isStoreConditional()) {
1068 // Store conditionals need to be set as "canCommit()"
1069 // so that commit can process them when they reach the
1070 // head of commit.
1071 // @todo: This is somewhat specific to Alpha.
1072 inst->setCanCommit();
1073 instQueue.insertNonSpec(inst);
1074 add_to_iq = false;
1075
1076 ++iewDispNonSpecInsts;
1077 } else {
1078 add_to_iq = true;
1079 }
1080
1081 toRename->iewInfo[tid].dispatchedToLSQ++;
1082 } else if (inst->isMemBarrier() || inst->isWriteBarrier()) {
1083 // Same as non-speculative stores.
1084 inst->setCanCommit();
1085 instQueue.insertBarrier(inst);
1086 add_to_iq = false;
1087 } else if (inst->isNop()) {
1088 DPRINTF(IEW, "[tid:%i]: Issue: Nop instruction encountered, "
1089 "skipping.\n", tid);
1090
1091 inst->setIssued();
1092 inst->setExecuted();
1093 inst->setCanCommit();
1094
1095 instQueue.recordProducer(inst);
1096
1097 iewExecutedNop[tid]++;
1098
1099 add_to_iq = false;
1100 } else if (inst->isExecuted()) {
1101 assert(0 && "Instruction shouldn't be executed.\n");
1102 DPRINTF(IEW, "Issue: Executed branch encountered, "
1103 "skipping.\n");
1104
1105 inst->setIssued();
1106 inst->setCanCommit();
1107
1108 instQueue.recordProducer(inst);
1109
1110 add_to_iq = false;
1111 } else {
1112 add_to_iq = true;
1113 }
1114 if (inst->isNonSpeculative()) {
1115 DPRINTF(IEW, "[tid:%i]: Issue: Nonspeculative instruction "
1116 "encountered, skipping.\n", tid);
1117
1118 // Same as non-speculative stores.
1119 inst->setCanCommit();
1120
1121 // Specifically insert it as nonspeculative.
1122 instQueue.insertNonSpec(inst);
1123
1124 ++iewDispNonSpecInsts;
1125
1126 add_to_iq = false;
1127 }
1128
1129 // If the instruction queue is not full, then add the
1130 // instruction.
1131 if (add_to_iq) {
1132 instQueue.insert(inst);
1133 }
1134
1135 insts_to_dispatch.pop();
1136
1137 toRename->iewInfo[tid].dispatched++;
1138
1139 ++iewDispatchedInsts;
1140 }
1141
1142 if (!insts_to_dispatch.empty()) {
1143 DPRINTF(IEW,"[tid:%i]: Issue: Bandwidth Full. Blocking.\n", tid);
1144 block(tid);
1145 toRename->iewUnblock[tid] = false;
1146 }
1147
1148 if (dispatchStatus[tid] == Idle && dis_num_inst) {
1149 dispatchStatus[tid] = Running;
1150
1151 updatedQueues = true;
1152 }
1153
1154 dis_num_inst = 0;
1155}
1156
1157template <class Impl>
1158void
1159DefaultIEW<Impl>::printAvailableInsts()
1160{
1161 int inst = 0;
1162
1163 std::cout << "Available Instructions: ";
1164
1165 while (fromIssue->insts[inst]) {
1166
1167 if (inst%3==0) std::cout << "\n\t";
1168
1169 std::cout << "PC: " << fromIssue->insts[inst]->pcState()
1170 << " TN: " << fromIssue->insts[inst]->threadNumber
1171 << " SN: " << fromIssue->insts[inst]->seqNum << " | ";
1172
1173 inst++;
1174
1175 }
1176
1177 std::cout << "\n";
1178}
1179
1180template <class Impl>
1181void
1182DefaultIEW<Impl>::executeInsts()
1183{
1184 wbNumInst = 0;
1185 wbCycle = 0;
1186
1187 list<ThreadID>::iterator threads = activeThreads->begin();
1188 list<ThreadID>::iterator end = activeThreads->end();
1189
1190 while (threads != end) {
1191 ThreadID tid = *threads++;
1192 fetchRedirect[tid] = false;
1193 }
1194
1195 // Uncomment this if you want to see all available instructions.
1196 // @todo This doesn't actually work anymore, we should fix it.
1197// printAvailableInsts();
1198
1199 // Execute/writeback any instructions that are available.
1200 int insts_to_execute = fromIssue->size;
1201 int inst_num = 0;
1202 for (; inst_num < insts_to_execute;
1203 ++inst_num) {
1204
1205 DPRINTF(IEW, "Execute: Executing instructions from IQ.\n");
1206
1207 DynInstPtr inst = instQueue.getInstToExecute();
1208
1209 DPRINTF(IEW, "Execute: Processing PC %s, [tid:%i] [sn:%i].\n",
1210 inst->pcState(), inst->threadNumber,inst->seqNum);
1211
1212 // Check if the instruction is squashed; if so then skip it
1213 if (inst->isSquashed()) {
1214 DPRINTF(IEW, "Execute: Instruction was squashed.\n");
1215
1216 // Consider this instruction executed so that commit can go
1217 // ahead and retire the instruction.
1218 inst->setExecuted();
1219
1220 // Not sure if I should set this here or just let commit try to
1221 // commit any squashed instructions. I like the latter a bit more.
1222 inst->setCanCommit();
1223
1224 ++iewExecSquashedInsts;
1225
1226 decrWb(inst->seqNum);
1227 continue;
1228 }
1229
1230 Fault fault = NoFault;
1231
1232 // Execute instruction.
1233 // Note that if the instruction faults, it will be handled
1234 // at the commit stage.
1235 if (inst->isMemRef()) {
1236 DPRINTF(IEW, "Execute: Calculating address for memory "
1237 "reference.\n");
1238
1239 // Tell the LDSTQ to execute this instruction (if it is a load).
1240 if (inst->isLoad()) {
1241 // Loads will mark themselves as executed, and their writeback
1242 // event adds the instruction to the queue to commit
1243 fault = ldstQueue.executeLoad(inst);
1244
1245 if (inst->isTranslationDelayed() &&
1246 fault == NoFault) {
1247 // A hw page table walk is currently going on; the
1248 // instruction must be deferred.
1249 DPRINTF(IEW, "Execute: Delayed translation, deferring "
1250 "load.\n");
1251 instQueue.deferMemInst(inst);
1252 continue;
1253 }
1254
1255 if (inst->isDataPrefetch() || inst->isInstPrefetch()) {
1256 inst->fault = NoFault;
1257 }
1258 } else if (inst->isStore()) {
1259 fault = ldstQueue.executeStore(inst);
1260
1261 if (inst->isTranslationDelayed() &&
1262 fault == NoFault) {
1263 // A hw page table walk is currently going on; the
1264 // instruction must be deferred.
1265 DPRINTF(IEW, "Execute: Delayed translation, deferring "
1266 "store.\n");
1267 instQueue.deferMemInst(inst);
1268 continue;
1269 }
1270
1271 // If the store had a fault then it may not have a mem req
1272 if (fault != NoFault || inst->readPredicate() == false ||
1273 !inst->isStoreConditional()) {
1274 // If the instruction faulted, then we need to send it along
1275 // to commit without the instruction completing.
1276 // Send this instruction to commit, also make sure iew stage
1277 // realizes there is activity.
1278 inst->setExecuted();
1279 instToCommit(inst);
1280 activityThisCycle();
1281 }
1282
1283 // Store conditionals will mark themselves as
1284 // executed, and their writeback event will add the
1285 // instruction to the queue to commit.
1286 } else {
1287 panic("Unexpected memory type!\n");
1288 }
1289
1290 } else {
1291 // If the instruction has already faulted, then skip executing it.
1292 // Such case can happen when it faulted during ITLB translation.
1293 // If we execute the instruction (even if it's a nop) the fault
1294 // will be replaced and we will lose it.
1295 if (inst->getFault() == NoFault) {
1296 inst->execute();
1297 if (inst->readPredicate() == false)
1298 inst->forwardOldRegs();
1299 }
1300
1301 inst->setExecuted();
1302
1303 instToCommit(inst);
1304 }
1305
1306 updateExeInstStats(inst);
1307
1308 // Check if branch prediction was correct, if not then we need
1309 // to tell commit to squash in flight instructions. Only
1310 // handle this if there hasn't already been something that
1311 // redirects fetch in this group of instructions.
1312
1313 // This probably needs to prioritize the redirects if a different
1314 // scheduler is used. Currently the scheduler schedules the oldest
1315 // instruction first, so the branch resolution order will be correct.
1316 ThreadID tid = inst->threadNumber;
1317
1318 if (!fetchRedirect[tid] ||
1319 !toCommit->squash[tid] ||
1320 toCommit->squashedSeqNum[tid] > inst->seqNum) {
1321
1322 // Prevent testing for misprediction on load instructions,
1323 // that have not been executed.
1324 bool loadNotExecuted = !inst->isExecuted() && inst->isLoad();
1325
1326 if (inst->mispredicted() && !loadNotExecuted) {
1327 fetchRedirect[tid] = true;
1328
1329 DPRINTF(IEW, "Execute: Branch mispredict detected.\n");
1330 DPRINTF(IEW, "Predicted target was PC:%#x, NPC:%#x.\n",
1331 inst->predInstAddr(), inst->predNextInstAddr());
1332 DPRINTF(IEW, "Execute: Redirecting fetch to PC: %s.\n",
1333 inst->pcState(), inst->nextInstAddr());
1334 // If incorrect, then signal the ROB that it must be squashed.
1335 squashDueToBranch(inst, tid);
1336
1337 if (inst->readPredTaken()) {
1338 predictedTakenIncorrect++;
1339 } else {
1340 predictedNotTakenIncorrect++;
1341 }
1342 } else if (ldstQueue.violation(tid)) {
1343 assert(inst->isMemRef());
1344 // If there was an ordering violation, then get the
1345 // DynInst that caused the violation. Note that this
1346 // clears the violation signal.
1347 DynInstPtr violator;
1348 violator = ldstQueue.getMemDepViolator(tid);
1349
1350 DPRINTF(IEW, "LDSTQ detected a violation. Violator PC: %s "
1351 "[sn:%lli], inst PC: %s [sn:%lli]. Addr is: %#x.\n",
1352 violator->pcState(), violator->seqNum,
1353 inst->pcState(), inst->seqNum, inst->physEffAddr);
1354
1355 fetchRedirect[tid] = true;
1356
1357 // Tell the instruction queue that a violation has occured.
1358 instQueue.violation(inst, violator);
1359
1360 // Squash.
1361 squashDueToMemOrder(inst,tid);
1362
1363 ++memOrderViolationEvents;
1364 } else if (ldstQueue.loadBlocked(tid) &&
1365 !ldstQueue.isLoadBlockedHandled(tid)) {
1366 fetchRedirect[tid] = true;
1367
1368 DPRINTF(IEW, "Load operation couldn't execute because the "
1369 "memory system is blocked. PC: %s [sn:%lli]\n",
1370 inst->pcState(), inst->seqNum);
1371
1372 squashDueToMemBlocked(inst, tid);
1373 }
1374 } else {
1375 // Reset any state associated with redirects that will not
1376 // be used.
1377 if (ldstQueue.violation(tid)) {
1378 assert(inst->isMemRef());
1379
1380 DynInstPtr violator = ldstQueue.getMemDepViolator(tid);
1381
1382 DPRINTF(IEW, "LDSTQ detected a violation. Violator PC: "
1383 "%s, inst PC: %s. Addr is: %#x.\n",
1384 violator->pcState(), inst->pcState(),
1385 inst->physEffAddr);
1386 DPRINTF(IEW, "Violation will not be handled because "
1387 "already squashing\n");
1388
1389 ++memOrderViolationEvents;
1390 }
1391 if (ldstQueue.loadBlocked(tid) &&
1392 !ldstQueue.isLoadBlockedHandled(tid)) {
1393 DPRINTF(IEW, "Load operation couldn't execute because the "
1394 "memory system is blocked. PC: %s [sn:%lli]\n",
1395 inst->pcState(), inst->seqNum);
1396 DPRINTF(IEW, "Blocked load will not be handled because "
1397 "already squashing\n");
1398
1399 ldstQueue.setLoadBlockedHandled(tid);
1400 }
1401
1402 }
1403 }
1404
1405 // Update and record activity if we processed any instructions.
1406 if (inst_num) {
1407 if (exeStatus == Idle) {
1408 exeStatus = Running;
1409 }
1410
1411 updatedQueues = true;
1412
1413 cpu->activityThisCycle();
1414 }
1415
1416 // Need to reset this in case a writeback event needs to write into the
1417 // iew queue. That way the writeback event will write into the correct
1418 // spot in the queue.
1419 wbNumInst = 0;
1420
1421}
1422
1423template <class Impl>
1424void
1425DefaultIEW<Impl>::writebackInsts()
1426{
1427 // Loop through the head of the time buffer and wake any
1428 // dependents. These instructions are about to write back. Also
1429 // mark scoreboard that this instruction is finally complete.
1430 // Either have IEW have direct access to scoreboard, or have this
1431 // as part of backwards communication.
1432 for (int inst_num = 0; inst_num < wbWidth &&
1433 toCommit->insts[inst_num]; inst_num++) {
1434 DynInstPtr inst = toCommit->insts[inst_num];
1435 ThreadID tid = inst->threadNumber;
1436
1437 DPRINTF(IEW, "Sending instructions to commit, [sn:%lli] PC %s.\n",
1438 inst->seqNum, inst->pcState());
1439
1440 iewInstsToCommit[tid]++;
1441
1442 // Some instructions will be sent to commit without having
1443 // executed because they need commit to handle them.
1444 // E.g. Uncached loads have not actually executed when they
1445 // are first sent to commit. Instead commit must tell the LSQ
1446 // when it's ready to execute the uncached load.
1447 if (!inst->isSquashed() && inst->isExecuted() && inst->getFault() == NoFault) {
1448 int dependents = instQueue.wakeDependents(inst);
1449
1450 for (int i = 0; i < inst->numDestRegs(); i++) {
1451 //mark as Ready
1452 DPRINTF(IEW,"Setting Destination Register %i\n",
1453 inst->renamedDestRegIdx(i));
1454 scoreboard->setReg(inst->renamedDestRegIdx(i));
1455 }
1456
1457 if (dependents) {
1458 producerInst[tid]++;
1459 consumerInst[tid]+= dependents;
1460 }
1461 writebackCount[tid]++;
1462 }
1463
1464 decrWb(inst->seqNum);
1465 }
1466}
1467
1468template<class Impl>
1469void
1470DefaultIEW<Impl>::tick()
1471{
1472 wbNumInst = 0;
1473 wbCycle = 0;
1474
1475 wroteToTimeBuffer = false;
1476 updatedQueues = false;
1477
1478 sortInsts();
1479
1480 // Free function units marked as being freed this cycle.
1481 fuPool->processFreeUnits();
1482
1483 list<ThreadID>::iterator threads = activeThreads->begin();
1484 list<ThreadID>::iterator end = activeThreads->end();
1485
1486 // Check stall and squash signals, dispatch any instructions.
1487 while (threads != end) {
1488 ThreadID tid = *threads++;
1489
1490 DPRINTF(IEW,"Issue: Processing [tid:%i]\n",tid);
1491
1492 checkSignalsAndUpdate(tid);
1493 dispatch(tid);
1494 }
1495
1496 if (exeStatus != Squashing) {
1497 executeInsts();
1498
1499 writebackInsts();
1500
1501 // Have the instruction queue try to schedule any ready instructions.
1502 // (In actuality, this scheduling is for instructions that will
1503 // be executed next cycle.)
1504 instQueue.scheduleReadyInsts();
1505
1506 // Also should advance its own time buffers if the stage ran.
1507 // Not the best place for it, but this works (hopefully).
1508 issueToExecQueue.advance();
1509 }
1510
1511 bool broadcast_free_entries = false;
1512
1513 if (updatedQueues || exeStatus == Running || updateLSQNextCycle) {
1514 exeStatus = Idle;
1515 updateLSQNextCycle = false;
1516
1517 broadcast_free_entries = true;
1518 }
1519
1520 // Writeback any stores using any leftover bandwidth.
1521 ldstQueue.writebackStores();
1522
1523 // Check the committed load/store signals to see if there's a load
1524 // or store to commit. Also check if it's being told to execute a
1525 // nonspeculative instruction.
1526 // This is pretty inefficient...
1527
1528 threads = activeThreads->begin();
1529 while (threads != end) {
1530 ThreadID tid = (*threads++);
1531
1532 DPRINTF(IEW,"Processing [tid:%i]\n",tid);
1533
1534 // Update structures based on instructions committed.
1535 if (fromCommit->commitInfo[tid].doneSeqNum != 0 &&
1536 !fromCommit->commitInfo[tid].squash &&
1537 !fromCommit->commitInfo[tid].robSquashing) {
1538
1539 ldstQueue.commitStores(fromCommit->commitInfo[tid].doneSeqNum,tid);
1540
1541 ldstQueue.commitLoads(fromCommit->commitInfo[tid].doneSeqNum,tid);
1542
1543 updateLSQNextCycle = true;
1544 instQueue.commit(fromCommit->commitInfo[tid].doneSeqNum,tid);
1545 }
1546
1547 if (fromCommit->commitInfo[tid].nonSpecSeqNum != 0) {
1548
1549 //DPRINTF(IEW,"NonspecInst from thread %i",tid);
1550 if (fromCommit->commitInfo[tid].uncached) {
1551 instQueue.replayMemInst(fromCommit->commitInfo[tid].uncachedLoad);
1552 fromCommit->commitInfo[tid].uncachedLoad->setAtCommit();
1553 } else {
1554 instQueue.scheduleNonSpec(
1555 fromCommit->commitInfo[tid].nonSpecSeqNum);
1556 }
1557 }
1558
1559 if (broadcast_free_entries) {
1560 toFetch->iewInfo[tid].iqCount =
1561 instQueue.getCount(tid);
1562 toFetch->iewInfo[tid].ldstqCount =
1563 ldstQueue.getCount(tid);
1564
1565 toRename->iewInfo[tid].usedIQ = true;
1566 toRename->iewInfo[tid].freeIQEntries =
1567 instQueue.numFreeEntries();
1568 toRename->iewInfo[tid].usedLSQ = true;
1569 toRename->iewInfo[tid].freeLSQEntries =
1570 ldstQueue.numFreeEntries(tid);
1571
1572 wroteToTimeBuffer = true;
1573 }
1574
1575 DPRINTF(IEW, "[tid:%i], Dispatch dispatched %i instructions.\n",
1576 tid, toRename->iewInfo[tid].dispatched);
1577 }
1578
1579 DPRINTF(IEW, "IQ has %i free entries (Can schedule: %i). "
1580 "LSQ has %i free entries.\n",
1581 instQueue.numFreeEntries(), instQueue.hasReadyInsts(),
1582 ldstQueue.numFreeEntries());
1583
1584 updateStatus();
1585
1586 if (wroteToTimeBuffer) {
1587 DPRINTF(Activity, "Activity this cycle.\n");
1588 cpu->activityThisCycle();
1589 }
1590}
1591
1592template <class Impl>
1593void
1594DefaultIEW<Impl>::updateExeInstStats(DynInstPtr &inst)
1595{
1596 ThreadID tid = inst->threadNumber;
1597
1598 //
1599 // Pick off the software prefetches
1600 //
1601#ifdef TARGET_ALPHA
1602 if (inst->isDataPrefetch())
1603 iewExecutedSwp[tid]++;
1604 else
1605 iewIewExecutedcutedInsts++;
1606#else
1607 iewExecutedInsts++;
1608#endif
1609
1610 //
1611 // Control operations
1612 //
1613 if (inst->isControl())
1614 iewExecutedBranches[tid]++;
1615
1616 //
1617 // Memory operations
1618 //
1619 if (inst->isMemRef()) {
1620 iewExecutedRefs[tid]++;
1621
1622 if (inst->isLoad()) {
1623 iewExecLoadInsts[tid]++;
1624 }
1625 }
1626}
1627
1628template <class Impl>
1629void
1630DefaultIEW<Impl>::checkMisprediction(DynInstPtr &inst)
1631{
1632 ThreadID tid = inst->threadNumber;
1633
1634 if (!fetchRedirect[tid] ||
1635 !toCommit->squash[tid] ||
1636 toCommit->squashedSeqNum[tid] > inst->seqNum) {
1637
1638 if (inst->mispredicted()) {
1639 fetchRedirect[tid] = true;
1640
1641 DPRINTF(IEW, "Execute: Branch mispredict detected.\n");
1642 DPRINTF(IEW, "Predicted target was PC:%#x, NPC:%#x.\n",
1643 inst->predInstAddr(), inst->predNextInstAddr());
1644 DPRINTF(IEW, "Execute: Redirecting fetch to PC: %#x,"
1645 " NPC: %#x.\n", inst->nextInstAddr(),
1646 inst->nextInstAddr());
1647 // If incorrect, then signal the ROB that it must be squashed.
1648 squashDueToBranch(inst, tid);
1649
1650 if (inst->readPredTaken()) {
1651 predictedTakenIncorrect++;
1652 } else {
1653 predictedNotTakenIncorrect++;
1654 }
1655 }
1656 }
1657}