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 "base/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: %#x "
453 "[sn:%i].\n", tid, inst->readPC(), inst->seqNum);
454
455 toCommit->squash[tid] = true;
456 toCommit->squashedSeqNum[tid] = inst->seqNum;
457 toCommit->mispredPC[tid] = inst->readPC();
458 toCommit->branchMispredict[tid] = true;
459
460#if ISA_HAS_DELAY_SLOT
461 int instSize = sizeof(TheISA::MachInst);
462 toCommit->branchTaken[tid] =
463 !(inst->readNextPC() + instSize == inst->readNextNPC() &&
464 (inst->readNextPC() == inst->readPC() + instSize ||
465 inst->readNextPC() == inst->readPC() + 2 * instSize));
466#else
467 toCommit->branchTaken[tid] = inst->readNextPC() !=
468 (inst->readPC() + sizeof(TheISA::MachInst));
469#endif
470 toCommit->nextPC[tid] = inst->readNextPC();
471 toCommit->nextNPC[tid] = inst->readNextNPC();
472 toCommit->nextMicroPC[tid] = inst->readNextMicroPC();
473
474 toCommit->includeSquashInst[tid] = false;
475
476 wroteToTimeBuffer = true;
477}
478
479template<class Impl>
480void
481DefaultIEW<Impl>::squashDueToMemOrder(DynInstPtr &inst, ThreadID tid)
482{
483 DPRINTF(IEW, "[tid:%i]: Squashing from a specific instruction, "
484 "PC: %#x [sn:%i].\n", tid, inst->readPC(), inst->seqNum);
485
486 toCommit->squash[tid] = true;
487 toCommit->squashedSeqNum[tid] = inst->seqNum;
488 toCommit->nextPC[tid] = inst->readNextPC();
489 toCommit->nextNPC[tid] = inst->readNextNPC();
490 toCommit->branchMispredict[tid] = false;
491
492 toCommit->includeSquashInst[tid] = false;
493
494 wroteToTimeBuffer = true;
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: %#x [sn:%i].\n", tid, inst->readPC(), inst->seqNum);
503
504 toCommit->squash[tid] = true;
505 toCommit->squashedSeqNum[tid] = inst->seqNum;
506 toCommit->nextPC[tid] = inst->readPC();
507 toCommit->nextNPC[tid] = inst->readNextPC();
508 toCommit->branchMispredict[tid] = false;
509
510 // Must include the broadcasted SN in the squash.
511 toCommit->includeSquashInst[tid] = true;
512
513 ldstQueue.setLoadBlockedHandled(tid);
514
515 wroteToTimeBuffer = true;
516}
517
518template<class Impl>
519void
520DefaultIEW<Impl>::block(ThreadID tid)
521{
522 DPRINTF(IEW, "[tid:%u]: Blocking.\n", tid);
523
524 if (dispatchStatus[tid] != Blocked &&
525 dispatchStatus[tid] != Unblocking) {
526 toRename->iewBlock[tid] = true;
527 wroteToTimeBuffer = true;
528 }
529
530 // Add the current inputs to the skid buffer so they can be
531 // reprocessed when this stage unblocks.
532 skidInsert(tid);
533
534 dispatchStatus[tid] = Blocked;
535}
536
537template<class Impl>
538void
539DefaultIEW<Impl>::unblock(ThreadID tid)
540{
541 DPRINTF(IEW, "[tid:%i]: Reading instructions out of the skid "
542 "buffer %u.\n",tid, tid);
543
544 // If the skid bufffer is empty, signal back to previous stages to unblock.
545 // Also switch status to running.
546 if (skidBuffer[tid].empty()) {
547 toRename->iewUnblock[tid] = true;
548 wroteToTimeBuffer = true;
549 DPRINTF(IEW, "[tid:%i]: Done unblocking.\n",tid);
550 dispatchStatus[tid] = Running;
551 }
552}
553
554template<class Impl>
555void
556DefaultIEW<Impl>::wakeDependents(DynInstPtr &inst)
557{
558 instQueue.wakeDependents(inst);
559}
560
561template<class Impl>
562void
563DefaultIEW<Impl>::rescheduleMemInst(DynInstPtr &inst)
564{
565 instQueue.rescheduleMemInst(inst);
566}
567
568template<class Impl>
569void
570DefaultIEW<Impl>::replayMemInst(DynInstPtr &inst)
571{
572 instQueue.replayMemInst(inst);
573}
574
575template<class Impl>
576void
577DefaultIEW<Impl>::instToCommit(DynInstPtr &inst)
578{
579 // This function should not be called after writebackInsts in a
580 // single cycle. That will cause problems with an instruction
581 // being added to the queue to commit without being processed by
582 // writebackInsts prior to being sent to commit.
583
584 // First check the time slot that this instruction will write
585 // to. If there are free write ports at the time, then go ahead
586 // and write the instruction to that time. If there are not,
587 // keep looking back to see where's the first time there's a
588 // free slot.
589 while ((*iewQueue)[wbCycle].insts[wbNumInst]) {
590 ++wbNumInst;
591 if (wbNumInst == wbWidth) {
592 ++wbCycle;
593 wbNumInst = 0;
594 }
595
596 assert((wbCycle * wbWidth + wbNumInst) <= wbMax);
597 }
598
599 DPRINTF(IEW, "Current wb cycle: %i, width: %i, numInst: %i\nwbActual:%i\n",
600 wbCycle, wbWidth, wbNumInst, wbCycle * wbWidth + wbNumInst);
601 // Add finished instruction to queue to commit.
602 (*iewQueue)[wbCycle].insts[wbNumInst] = inst;
603 (*iewQueue)[wbCycle].size++;
604}
605
606template <class Impl>
607unsigned
608DefaultIEW<Impl>::validInstsFromRename()
609{
610 unsigned inst_count = 0;
611
612 for (int i=0; i<fromRename->size; i++) {
613 if (!fromRename->insts[i]->isSquashed())
614 inst_count++;
615 }
616
617 return inst_count;
618}
619
620template<class Impl>
621void
622DefaultIEW<Impl>::skidInsert(ThreadID tid)
623{
624 DynInstPtr inst = NULL;
625
626 while (!insts[tid].empty()) {
627 inst = insts[tid].front();
628
629 insts[tid].pop();
630
631 DPRINTF(Decode,"[tid:%i]: Inserting [sn:%lli] PC:%#x into "
632 "dispatch skidBuffer %i\n",tid, inst->seqNum,
633 inst->readPC(),tid);
634
635 skidBuffer[tid].push(inst);
636 }
637
638 assert(skidBuffer[tid].size() <= skidBufferMax &&
639 "Skidbuffer Exceeded Max Size");
640}
641
642template<class Impl>
643int
644DefaultIEW<Impl>::skidCount()
645{
646 int max=0;
647
648 list<ThreadID>::iterator threads = activeThreads->begin();
649 list<ThreadID>::iterator end = activeThreads->end();
650
651 while (threads != end) {
652 ThreadID tid = *threads++;
653 unsigned thread_count = skidBuffer[tid].size();
654 if (max < thread_count)
655 max = thread_count;
656 }
657
658 return max;
659}
660
661template<class Impl>
662bool
663DefaultIEW<Impl>::skidsEmpty()
664{
665 list<ThreadID>::iterator threads = activeThreads->begin();
666 list<ThreadID>::iterator end = activeThreads->end();
667
668 while (threads != end) {
669 ThreadID tid = *threads++;
670
671 if (!skidBuffer[tid].empty())
672 return false;
673 }
674
675 return true;
676}
677
678template <class Impl>
679void
680DefaultIEW<Impl>::updateStatus()
681{
682 bool any_unblocking = false;
683
684 list<ThreadID>::iterator threads = activeThreads->begin();
685 list<ThreadID>::iterator end = activeThreads->end();
686
687 while (threads != end) {
688 ThreadID tid = *threads++;
689
690 if (dispatchStatus[tid] == Unblocking) {
691 any_unblocking = true;
692 break;
693 }
694 }
695
696 // If there are no ready instructions waiting to be scheduled by the IQ,
697 // and there's no stores waiting to write back, and dispatch is not
698 // unblocking, then there is no internal activity for the IEW stage.
699 if (_status == Active && !instQueue.hasReadyInsts() &&
700 !ldstQueue.willWB() && !any_unblocking) {
701 DPRINTF(IEW, "IEW switching to idle\n");
702
703 deactivateStage();
704
705 _status = Inactive;
706 } else if (_status == Inactive && (instQueue.hasReadyInsts() ||
707 ldstQueue.willWB() ||
708 any_unblocking)) {
709 // Otherwise there is internal activity. Set to active.
710 DPRINTF(IEW, "IEW switching to active\n");
711
712 activateStage();
713
714 _status = Active;
715 }
716}
717
718template <class Impl>
719void
720DefaultIEW<Impl>::resetEntries()
721{
722 instQueue.resetEntries();
723 ldstQueue.resetEntries();
724}
725
726template <class Impl>
727void
728DefaultIEW<Impl>::readStallSignals(ThreadID tid)
729{
730 if (fromCommit->commitBlock[tid]) {
731 stalls[tid].commit = true;
732 }
733
734 if (fromCommit->commitUnblock[tid]) {
735 assert(stalls[tid].commit);
736 stalls[tid].commit = false;
737 }
738}
739
740template <class Impl>
741bool
742DefaultIEW<Impl>::checkStall(ThreadID tid)
743{
744 bool ret_val(false);
745
746 if (stalls[tid].commit) {
747 DPRINTF(IEW,"[tid:%i]: Stall from Commit stage detected.\n",tid);
748 ret_val = true;
749 } else if (instQueue.isFull(tid)) {
750 DPRINTF(IEW,"[tid:%i]: Stall: IQ is full.\n",tid);
751 ret_val = true;
752 } else if (ldstQueue.isFull(tid)) {
753 DPRINTF(IEW,"[tid:%i]: Stall: LSQ is full\n",tid);
754
755 if (ldstQueue.numLoads(tid) > 0 ) {
756
757 DPRINTF(IEW,"[tid:%i]: LSQ oldest load: [sn:%i] \n",
758 tid,ldstQueue.getLoadHeadSeqNum(tid));
759 }
760
761 if (ldstQueue.numStores(tid) > 0) {
762
763 DPRINTF(IEW,"[tid:%i]: LSQ oldest store: [sn:%i] \n",
764 tid,ldstQueue.getStoreHeadSeqNum(tid));
765 }
766
767 ret_val = true;
768 } else if (ldstQueue.isStalled(tid)) {
769 DPRINTF(IEW,"[tid:%i]: Stall: LSQ stall detected.\n",tid);
770 ret_val = true;
771 }
772
773 return ret_val;
774}
775
776template <class Impl>
777void
778DefaultIEW<Impl>::checkSignalsAndUpdate(ThreadID tid)
779{
780 // Check if there's a squash signal, squash if there is
781 // Check stall signals, block if there is.
782 // If status was Blocked
783 // if so then go to unblocking
784 // If status was Squashing
785 // check if squashing is not high. Switch to running this cycle.
786
787 readStallSignals(tid);
788
789 if (fromCommit->commitInfo[tid].squash) {
790 squash(tid);
791
792 if (dispatchStatus[tid] == Blocked ||
793 dispatchStatus[tid] == Unblocking) {
794 toRename->iewUnblock[tid] = true;
795 wroteToTimeBuffer = true;
796 }
797
798 dispatchStatus[tid] = Squashing;
799
800 fetchRedirect[tid] = false;
801 return;
802 }
803
804 if (fromCommit->commitInfo[tid].robSquashing) {
805 DPRINTF(IEW, "[tid:%i]: ROB is still squashing.\n", tid);
806
807 dispatchStatus[tid] = Squashing;
808
809 emptyRenameInsts(tid);
810 wroteToTimeBuffer = true;
811 return;
812 }
813
814 if (checkStall(tid)) {
815 block(tid);
816 dispatchStatus[tid] = Blocked;
817 return;
818 }
819
820 if (dispatchStatus[tid] == Blocked) {
821 // Status from previous cycle was blocked, but there are no more stall
822 // conditions. Switch over to unblocking.
823 DPRINTF(IEW, "[tid:%i]: Done blocking, switching to unblocking.\n",
824 tid);
825
826 dispatchStatus[tid] = Unblocking;
827
828 unblock(tid);
829
830 return;
831 }
832
833 if (dispatchStatus[tid] == Squashing) {
834 // Switch status to running if rename isn't being told to block or
835 // squash this cycle.
836 DPRINTF(IEW, "[tid:%i]: Done squashing, switching to running.\n",
837 tid);
838
839 dispatchStatus[tid] = Running;
840
841 return;
842 }
843}
844
845template <class Impl>
846void
847DefaultIEW<Impl>::sortInsts()
848{
849 int insts_from_rename = fromRename->size;
850#ifdef DEBUG
851 for (ThreadID tid = 0; tid < numThreads; tid++)
852 assert(insts[tid].empty());
853#endif
854 for (int i = 0; i < insts_from_rename; ++i) {
855 insts[fromRename->insts[i]->threadNumber].push(fromRename->insts[i]);
856 }
857}
858
859template <class Impl>
860void
861DefaultIEW<Impl>::emptyRenameInsts(ThreadID tid)
862{
863 DPRINTF(IEW, "[tid:%i]: Removing incoming rename instructions\n", tid);
864
865 while (!insts[tid].empty()) {
866
867 if (insts[tid].front()->isLoad() ||
868 insts[tid].front()->isStore() ) {
869 toRename->iewInfo[tid].dispatchedToLSQ++;
870 }
871
872 toRename->iewInfo[tid].dispatched++;
873
874 insts[tid].pop();
875 }
876}
877
878template <class Impl>
879void
880DefaultIEW<Impl>::wakeCPU()
881{
882 cpu->wakeCPU();
883}
884
885template <class Impl>
886void
887DefaultIEW<Impl>::activityThisCycle()
888{
889 DPRINTF(Activity, "Activity this cycle.\n");
890 cpu->activityThisCycle();
891}
892
893template <class Impl>
894inline void
895DefaultIEW<Impl>::activateStage()
896{
897 DPRINTF(Activity, "Activating stage.\n");
898 cpu->activateStage(O3CPU::IEWIdx);
899}
900
901template <class Impl>
902inline void
903DefaultIEW<Impl>::deactivateStage()
904{
905 DPRINTF(Activity, "Deactivating stage.\n");
906 cpu->deactivateStage(O3CPU::IEWIdx);
907}
908
909template<class Impl>
910void
911DefaultIEW<Impl>::dispatch(ThreadID tid)
912{
913 // If status is Running or idle,
914 // call dispatchInsts()
915 // If status is Unblocking,
916 // buffer any instructions coming from rename
917 // continue trying to empty skid buffer
918 // check if stall conditions have passed
919
920 if (dispatchStatus[tid] == Blocked) {
921 ++iewBlockCycles;
922
923 } else if (dispatchStatus[tid] == Squashing) {
924 ++iewSquashCycles;
925 }
926
927 // Dispatch should try to dispatch as many instructions as its bandwidth
928 // will allow, as long as it is not currently blocked.
929 if (dispatchStatus[tid] == Running ||
930 dispatchStatus[tid] == Idle) {
931 DPRINTF(IEW, "[tid:%i] Not blocked, so attempting to run "
932 "dispatch.\n", tid);
933
934 dispatchInsts(tid);
935 } else if (dispatchStatus[tid] == Unblocking) {
936 // Make sure that the skid buffer has something in it if the
937 // status is unblocking.
938 assert(!skidsEmpty());
939
940 // If the status was unblocking, then instructions from the skid
941 // buffer were used. Remove those instructions and handle
942 // the rest of unblocking.
943 dispatchInsts(tid);
944
945 ++iewUnblockCycles;
946
947 if (validInstsFromRename()) {
948 // Add the current inputs to the skid buffer so they can be
949 // reprocessed when this stage unblocks.
950 skidInsert(tid);
951 }
952
953 unblock(tid);
954 }
955}
956
957template <class Impl>
958void
959DefaultIEW<Impl>::dispatchInsts(ThreadID tid)
960{
961 // Obtain instructions from skid buffer if unblocking, or queue from rename
962 // otherwise.
963 std::queue<DynInstPtr> &insts_to_dispatch =
964 dispatchStatus[tid] == Unblocking ?
965 skidBuffer[tid] : insts[tid];
966
967 int insts_to_add = insts_to_dispatch.size();
968
969 DynInstPtr inst;
970 bool add_to_iq = false;
971 int dis_num_inst = 0;
972
973 // Loop through the instructions, putting them in the instruction
974 // queue.
975 for ( ; dis_num_inst < insts_to_add &&
976 dis_num_inst < dispatchWidth;
977 ++dis_num_inst)
978 {
979 inst = insts_to_dispatch.front();
980
981 if (dispatchStatus[tid] == Unblocking) {
982 DPRINTF(IEW, "[tid:%i]: Issue: Examining instruction from skid "
983 "buffer\n", tid);
984 }
985
986 // Make sure there's a valid instruction there.
987 assert(inst);
988
989 DPRINTF(IEW, "[tid:%i]: Issue: Adding PC %#x [sn:%lli] [tid:%i] to "
990 "IQ.\n",
991 tid, inst->readPC(), inst->seqNum, inst->threadNumber);
992
993 // Be sure to mark these instructions as ready so that the
994 // commit stage can go ahead and execute them, and mark
995 // them as issued so the IQ doesn't reprocess them.
996
997 // Check for squashed instructions.
998 if (inst->isSquashed()) {
999 DPRINTF(IEW, "[tid:%i]: Issue: Squashed instruction encountered, "
1000 "not adding to IQ.\n", tid);
1001
1002 ++iewDispSquashedInsts;
1003
1004 insts_to_dispatch.pop();
1005
1006 //Tell Rename That An Instruction has been processed
1007 if (inst->isLoad() || inst->isStore()) {
1008 toRename->iewInfo[tid].dispatchedToLSQ++;
1009 }
1010 toRename->iewInfo[tid].dispatched++;
1011
1012 continue;
1013 }
1014
1015 // Check for full conditions.
1016 if (instQueue.isFull(tid)) {
1017 DPRINTF(IEW, "[tid:%i]: Issue: IQ has become full.\n", tid);
1018
1019 // Call function to start blocking.
1020 block(tid);
1021
1022 // Set unblock to false. Special case where we are using
1023 // skidbuffer (unblocking) instructions but then we still
1024 // get full in the IQ.
1025 toRename->iewUnblock[tid] = false;
1026
1027 ++iewIQFullEvents;
1028 break;
1029 } else if (ldstQueue.isFull(tid)) {
1030 DPRINTF(IEW, "[tid:%i]: Issue: LSQ has become full.\n",tid);
1031
1032 // Call function to start blocking.
1033 block(tid);
1034
1035 // Set unblock to false. Special case where we are using
1036 // skidbuffer (unblocking) instructions but then we still
1037 // get full in the IQ.
1038 toRename->iewUnblock[tid] = false;
1039
1040 ++iewLSQFullEvents;
1041 break;
1042 }
1043
1044 // Otherwise issue the instruction just fine.
1045 if (inst->isLoad()) {
1046 DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1047 "encountered, adding to LSQ.\n", tid);
1048
1049 // Reserve a spot in the load store queue for this
1050 // memory access.
1051 ldstQueue.insertLoad(inst);
1052
1053 ++iewDispLoadInsts;
1054
1055 add_to_iq = true;
1056
1057 toRename->iewInfo[tid].dispatchedToLSQ++;
1058 } else if (inst->isStore()) {
1059 DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1060 "encountered, adding to LSQ.\n", tid);
1061
1062 ldstQueue.insertStore(inst);
1063
1064 ++iewDispStoreInsts;
1065
1066 if (inst->isStoreConditional()) {
1067 // Store conditionals need to be set as "canCommit()"
1068 // so that commit can process them when they reach the
1069 // head of commit.
1070 // @todo: This is somewhat specific to Alpha.
1071 inst->setCanCommit();
1072 instQueue.insertNonSpec(inst);
1073 add_to_iq = false;
1074
1075 ++iewDispNonSpecInsts;
1076 } else {
1077 add_to_iq = true;
1078 }
1079
1080 toRename->iewInfo[tid].dispatchedToLSQ++;
1081 } else if (inst->isMemBarrier() || inst->isWriteBarrier()) {
1082 // Same as non-speculative stores.
1083 inst->setCanCommit();
1084 instQueue.insertBarrier(inst);
1085 add_to_iq = false;
1086 } else if (inst->isNop()) {
1087 DPRINTF(IEW, "[tid:%i]: Issue: Nop instruction encountered, "
1088 "skipping.\n", tid);
1089
1090 inst->setIssued();
1091 inst->setExecuted();
1092 inst->setCanCommit();
1093
1094 instQueue.recordProducer(inst);
1095
1096 iewExecutedNop[tid]++;
1097
1098 add_to_iq = false;
1099 } else if (inst->isExecuted()) {
1100 assert(0 && "Instruction shouldn't be executed.\n");
1101 DPRINTF(IEW, "Issue: Executed branch encountered, "
1102 "skipping.\n");
1103
1104 inst->setIssued();
1105 inst->setCanCommit();
1106
1107 instQueue.recordProducer(inst);
1108
1109 add_to_iq = false;
1110 } else {
1111 add_to_iq = true;
1112 }
1113 if (inst->isNonSpeculative()) {
1114 DPRINTF(IEW, "[tid:%i]: Issue: Nonspeculative instruction "
1115 "encountered, skipping.\n", tid);
1116
1117 // Same as non-speculative stores.
1118 inst->setCanCommit();
1119
1120 // Specifically insert it as nonspeculative.
1121 instQueue.insertNonSpec(inst);
1122
1123 ++iewDispNonSpecInsts;
1124
1125 add_to_iq = false;
1126 }
1127
1128 // If the instruction queue is not full, then add the
1129 // instruction.
1130 if (add_to_iq) {
1131 instQueue.insert(inst);
1132 }
1133
1134 insts_to_dispatch.pop();
1135
1136 toRename->iewInfo[tid].dispatched++;
1137
1138 ++iewDispatchedInsts;
1139 }
1140
1141 if (!insts_to_dispatch.empty()) {
1142 DPRINTF(IEW,"[tid:%i]: Issue: Bandwidth Full. Blocking.\n", tid);
1143 block(tid);
1144 toRename->iewUnblock[tid] = false;
1145 }
1146
1147 if (dispatchStatus[tid] == Idle && dis_num_inst) {
1148 dispatchStatus[tid] = Running;
1149
1150 updatedQueues = true;
1151 }
1152
1153 dis_num_inst = 0;
1154}
1155
1156template <class Impl>
1157void
1158DefaultIEW<Impl>::printAvailableInsts()
1159{
1160 int inst = 0;
1161
1162 std::cout << "Available Instructions: ";
1163
1164 while (fromIssue->insts[inst]) {
1165
1166 if (inst%3==0) std::cout << "\n\t";
1167
1168 std::cout << "PC: " << fromIssue->insts[inst]->readPC()
1169 << " TN: " << fromIssue->insts[inst]->threadNumber
1170 << " SN: " << fromIssue->insts[inst]->seqNum << " | ";
1171
1172 inst++;
1173
1174 }
1175
1176 std::cout << "\n";
1177}
1178
1179template <class Impl>
1180void
1181DefaultIEW<Impl>::executeInsts()
1182{
1183 wbNumInst = 0;
1184 wbCycle = 0;
1185
1186 list<ThreadID>::iterator threads = activeThreads->begin();
1187 list<ThreadID>::iterator end = activeThreads->end();
1188
1189 while (threads != end) {
1190 ThreadID tid = *threads++;
1191 fetchRedirect[tid] = false;
1192 }
1193
1194 // Uncomment this if you want to see all available instructions.
1195 // @todo This doesn't actually work anymore, we should fix it.
1196// printAvailableInsts();
1197
1198 // Execute/writeback any instructions that are available.
1199 int insts_to_execute = fromIssue->size;
1200 int inst_num = 0;
1201 for (; inst_num < insts_to_execute;
1202 ++inst_num) {
1203
1204 DPRINTF(IEW, "Execute: Executing instructions from IQ.\n");
1205
1206 DynInstPtr inst = instQueue.getInstToExecute();
1207
1208 DPRINTF(IEW, "Execute: Processing PC %#x, [tid:%i] [sn:%i].\n",
1209 inst->readPC(), inst->threadNumber,inst->seqNum);
1210
1211 // Check if the instruction is squashed; if so then skip it
1212 if (inst->isSquashed()) {
1213 DPRINTF(IEW, "Execute: Instruction was squashed.\n");
1214
1215 // Consider this instruction executed so that commit can go
1216 // ahead and retire the instruction.
1217 inst->setExecuted();
1218
1219 // Not sure if I should set this here or just let commit try to
1220 // commit any squashed instructions. I like the latter a bit more.
1221 inst->setCanCommit();
1222
1223 ++iewExecSquashedInsts;
1224
1225 decrWb(inst->seqNum);
1226 continue;
1227 }
1228
1229 Fault fault = NoFault;
1230
1231 // Execute instruction.
1232 // Note that if the instruction faults, it will be handled
1233 // at the commit stage.
1234 if (inst->isMemRef() &&
1235 (!inst->isDataPrefetch() && !inst->isInstPrefetch())) {
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 } else if (inst->isStore()) {
1245 fault = ldstQueue.executeStore(inst);
1246
1247 // If the store had a fault then it may not have a mem req
1248 if (!inst->isStoreConditional() && fault == NoFault) {
1249 inst->setExecuted();
1250
1251 instToCommit(inst);
1252 } else if (fault != NoFault) {
1253 // If the instruction faulted, then we need to send it along to commit
1254 // without the instruction completing.
1255 DPRINTF(IEW, "Store has fault %s! [sn:%lli]\n",
1256 fault->name(), inst->seqNum);
1257
1258 // Send this instruction to commit, also make sure iew stage
1259 // realizes there is activity.
1260 inst->setExecuted();
1261
1262 instToCommit(inst);
1263 activityThisCycle();
1264 }
1265
1266 // Store conditionals will mark themselves as
1267 // executed, and their writeback event will add the
1268 // instruction to the queue to commit.
1269 } else {
1270 panic("Unexpected memory type!\n");
1271 }
1272
1273 } else {
1274 inst->execute();
1275
1276 inst->setExecuted();
1277
1278 instToCommit(inst);
1279 }
1280
1281 updateExeInstStats(inst);
1282
1283 // Check if branch prediction was correct, if not then we need
1284 // to tell commit to squash in flight instructions. Only
1285 // handle this if there hasn't already been something that
1286 // redirects fetch in this group of instructions.
1287
1288 // This probably needs to prioritize the redirects if a different
1289 // scheduler is used. Currently the scheduler schedules the oldest
1290 // instruction first, so the branch resolution order will be correct.
1291 ThreadID tid = inst->threadNumber;
1292
1293 if (!fetchRedirect[tid] ||
1294 toCommit->squashedSeqNum[tid] > inst->seqNum) {
1295
1296 if (inst->mispredicted()) {
1297 fetchRedirect[tid] = true;
1298
1299 DPRINTF(IEW, "Execute: Branch mispredict detected.\n");
1300 DPRINTF(IEW, "Predicted target was PC:%#x, NPC:%#x.\n",
1301 inst->readPredPC(), inst->readPredNPC());
1302 DPRINTF(IEW, "Execute: Redirecting fetch to PC: %#x,"
1303 " NPC: %#x.\n", inst->readNextPC(),
1304 inst->readNextNPC());
1305 // If incorrect, then signal the ROB that it must be squashed.
1306 squashDueToBranch(inst, tid);
1307
1308 if (inst->readPredTaken()) {
1309 predictedTakenIncorrect++;
1310 } else {
1311 predictedNotTakenIncorrect++;
1312 }
1313 } else if (ldstQueue.violation(tid)) {
1314 assert(inst->isMemRef());
1315 // If there was an ordering violation, then get the
1316 // DynInst that caused the violation. Note that this
1317 // clears the violation signal.
1318 DynInstPtr violator;
1319 violator = ldstQueue.getMemDepViolator(tid);
1320
| 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 "base/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: %#x "
453 "[sn:%i].\n", tid, inst->readPC(), inst->seqNum);
454
455 toCommit->squash[tid] = true;
456 toCommit->squashedSeqNum[tid] = inst->seqNum;
457 toCommit->mispredPC[tid] = inst->readPC();
458 toCommit->branchMispredict[tid] = true;
459
460#if ISA_HAS_DELAY_SLOT
461 int instSize = sizeof(TheISA::MachInst);
462 toCommit->branchTaken[tid] =
463 !(inst->readNextPC() + instSize == inst->readNextNPC() &&
464 (inst->readNextPC() == inst->readPC() + instSize ||
465 inst->readNextPC() == inst->readPC() + 2 * instSize));
466#else
467 toCommit->branchTaken[tid] = inst->readNextPC() !=
468 (inst->readPC() + sizeof(TheISA::MachInst));
469#endif
470 toCommit->nextPC[tid] = inst->readNextPC();
471 toCommit->nextNPC[tid] = inst->readNextNPC();
472 toCommit->nextMicroPC[tid] = inst->readNextMicroPC();
473
474 toCommit->includeSquashInst[tid] = false;
475
476 wroteToTimeBuffer = true;
477}
478
479template<class Impl>
480void
481DefaultIEW<Impl>::squashDueToMemOrder(DynInstPtr &inst, ThreadID tid)
482{
483 DPRINTF(IEW, "[tid:%i]: Squashing from a specific instruction, "
484 "PC: %#x [sn:%i].\n", tid, inst->readPC(), inst->seqNum);
485
486 toCommit->squash[tid] = true;
487 toCommit->squashedSeqNum[tid] = inst->seqNum;
488 toCommit->nextPC[tid] = inst->readNextPC();
489 toCommit->nextNPC[tid] = inst->readNextNPC();
490 toCommit->branchMispredict[tid] = false;
491
492 toCommit->includeSquashInst[tid] = false;
493
494 wroteToTimeBuffer = true;
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: %#x [sn:%i].\n", tid, inst->readPC(), inst->seqNum);
503
504 toCommit->squash[tid] = true;
505 toCommit->squashedSeqNum[tid] = inst->seqNum;
506 toCommit->nextPC[tid] = inst->readPC();
507 toCommit->nextNPC[tid] = inst->readNextPC();
508 toCommit->branchMispredict[tid] = false;
509
510 // Must include the broadcasted SN in the squash.
511 toCommit->includeSquashInst[tid] = true;
512
513 ldstQueue.setLoadBlockedHandled(tid);
514
515 wroteToTimeBuffer = true;
516}
517
518template<class Impl>
519void
520DefaultIEW<Impl>::block(ThreadID tid)
521{
522 DPRINTF(IEW, "[tid:%u]: Blocking.\n", tid);
523
524 if (dispatchStatus[tid] != Blocked &&
525 dispatchStatus[tid] != Unblocking) {
526 toRename->iewBlock[tid] = true;
527 wroteToTimeBuffer = true;
528 }
529
530 // Add the current inputs to the skid buffer so they can be
531 // reprocessed when this stage unblocks.
532 skidInsert(tid);
533
534 dispatchStatus[tid] = Blocked;
535}
536
537template<class Impl>
538void
539DefaultIEW<Impl>::unblock(ThreadID tid)
540{
541 DPRINTF(IEW, "[tid:%i]: Reading instructions out of the skid "
542 "buffer %u.\n",tid, tid);
543
544 // If the skid bufffer is empty, signal back to previous stages to unblock.
545 // Also switch status to running.
546 if (skidBuffer[tid].empty()) {
547 toRename->iewUnblock[tid] = true;
548 wroteToTimeBuffer = true;
549 DPRINTF(IEW, "[tid:%i]: Done unblocking.\n",tid);
550 dispatchStatus[tid] = Running;
551 }
552}
553
554template<class Impl>
555void
556DefaultIEW<Impl>::wakeDependents(DynInstPtr &inst)
557{
558 instQueue.wakeDependents(inst);
559}
560
561template<class Impl>
562void
563DefaultIEW<Impl>::rescheduleMemInst(DynInstPtr &inst)
564{
565 instQueue.rescheduleMemInst(inst);
566}
567
568template<class Impl>
569void
570DefaultIEW<Impl>::replayMemInst(DynInstPtr &inst)
571{
572 instQueue.replayMemInst(inst);
573}
574
575template<class Impl>
576void
577DefaultIEW<Impl>::instToCommit(DynInstPtr &inst)
578{
579 // This function should not be called after writebackInsts in a
580 // single cycle. That will cause problems with an instruction
581 // being added to the queue to commit without being processed by
582 // writebackInsts prior to being sent to commit.
583
584 // First check the time slot that this instruction will write
585 // to. If there are free write ports at the time, then go ahead
586 // and write the instruction to that time. If there are not,
587 // keep looking back to see where's the first time there's a
588 // free slot.
589 while ((*iewQueue)[wbCycle].insts[wbNumInst]) {
590 ++wbNumInst;
591 if (wbNumInst == wbWidth) {
592 ++wbCycle;
593 wbNumInst = 0;
594 }
595
596 assert((wbCycle * wbWidth + wbNumInst) <= wbMax);
597 }
598
599 DPRINTF(IEW, "Current wb cycle: %i, width: %i, numInst: %i\nwbActual:%i\n",
600 wbCycle, wbWidth, wbNumInst, wbCycle * wbWidth + wbNumInst);
601 // Add finished instruction to queue to commit.
602 (*iewQueue)[wbCycle].insts[wbNumInst] = inst;
603 (*iewQueue)[wbCycle].size++;
604}
605
606template <class Impl>
607unsigned
608DefaultIEW<Impl>::validInstsFromRename()
609{
610 unsigned inst_count = 0;
611
612 for (int i=0; i<fromRename->size; i++) {
613 if (!fromRename->insts[i]->isSquashed())
614 inst_count++;
615 }
616
617 return inst_count;
618}
619
620template<class Impl>
621void
622DefaultIEW<Impl>::skidInsert(ThreadID tid)
623{
624 DynInstPtr inst = NULL;
625
626 while (!insts[tid].empty()) {
627 inst = insts[tid].front();
628
629 insts[tid].pop();
630
631 DPRINTF(Decode,"[tid:%i]: Inserting [sn:%lli] PC:%#x into "
632 "dispatch skidBuffer %i\n",tid, inst->seqNum,
633 inst->readPC(),tid);
634
635 skidBuffer[tid].push(inst);
636 }
637
638 assert(skidBuffer[tid].size() <= skidBufferMax &&
639 "Skidbuffer Exceeded Max Size");
640}
641
642template<class Impl>
643int
644DefaultIEW<Impl>::skidCount()
645{
646 int max=0;
647
648 list<ThreadID>::iterator threads = activeThreads->begin();
649 list<ThreadID>::iterator end = activeThreads->end();
650
651 while (threads != end) {
652 ThreadID tid = *threads++;
653 unsigned thread_count = skidBuffer[tid].size();
654 if (max < thread_count)
655 max = thread_count;
656 }
657
658 return max;
659}
660
661template<class Impl>
662bool
663DefaultIEW<Impl>::skidsEmpty()
664{
665 list<ThreadID>::iterator threads = activeThreads->begin();
666 list<ThreadID>::iterator end = activeThreads->end();
667
668 while (threads != end) {
669 ThreadID tid = *threads++;
670
671 if (!skidBuffer[tid].empty())
672 return false;
673 }
674
675 return true;
676}
677
678template <class Impl>
679void
680DefaultIEW<Impl>::updateStatus()
681{
682 bool any_unblocking = false;
683
684 list<ThreadID>::iterator threads = activeThreads->begin();
685 list<ThreadID>::iterator end = activeThreads->end();
686
687 while (threads != end) {
688 ThreadID tid = *threads++;
689
690 if (dispatchStatus[tid] == Unblocking) {
691 any_unblocking = true;
692 break;
693 }
694 }
695
696 // If there are no ready instructions waiting to be scheduled by the IQ,
697 // and there's no stores waiting to write back, and dispatch is not
698 // unblocking, then there is no internal activity for the IEW stage.
699 if (_status == Active && !instQueue.hasReadyInsts() &&
700 !ldstQueue.willWB() && !any_unblocking) {
701 DPRINTF(IEW, "IEW switching to idle\n");
702
703 deactivateStage();
704
705 _status = Inactive;
706 } else if (_status == Inactive && (instQueue.hasReadyInsts() ||
707 ldstQueue.willWB() ||
708 any_unblocking)) {
709 // Otherwise there is internal activity. Set to active.
710 DPRINTF(IEW, "IEW switching to active\n");
711
712 activateStage();
713
714 _status = Active;
715 }
716}
717
718template <class Impl>
719void
720DefaultIEW<Impl>::resetEntries()
721{
722 instQueue.resetEntries();
723 ldstQueue.resetEntries();
724}
725
726template <class Impl>
727void
728DefaultIEW<Impl>::readStallSignals(ThreadID tid)
729{
730 if (fromCommit->commitBlock[tid]) {
731 stalls[tid].commit = true;
732 }
733
734 if (fromCommit->commitUnblock[tid]) {
735 assert(stalls[tid].commit);
736 stalls[tid].commit = false;
737 }
738}
739
740template <class Impl>
741bool
742DefaultIEW<Impl>::checkStall(ThreadID tid)
743{
744 bool ret_val(false);
745
746 if (stalls[tid].commit) {
747 DPRINTF(IEW,"[tid:%i]: Stall from Commit stage detected.\n",tid);
748 ret_val = true;
749 } else if (instQueue.isFull(tid)) {
750 DPRINTF(IEW,"[tid:%i]: Stall: IQ is full.\n",tid);
751 ret_val = true;
752 } else if (ldstQueue.isFull(tid)) {
753 DPRINTF(IEW,"[tid:%i]: Stall: LSQ is full\n",tid);
754
755 if (ldstQueue.numLoads(tid) > 0 ) {
756
757 DPRINTF(IEW,"[tid:%i]: LSQ oldest load: [sn:%i] \n",
758 tid,ldstQueue.getLoadHeadSeqNum(tid));
759 }
760
761 if (ldstQueue.numStores(tid) > 0) {
762
763 DPRINTF(IEW,"[tid:%i]: LSQ oldest store: [sn:%i] \n",
764 tid,ldstQueue.getStoreHeadSeqNum(tid));
765 }
766
767 ret_val = true;
768 } else if (ldstQueue.isStalled(tid)) {
769 DPRINTF(IEW,"[tid:%i]: Stall: LSQ stall detected.\n",tid);
770 ret_val = true;
771 }
772
773 return ret_val;
774}
775
776template <class Impl>
777void
778DefaultIEW<Impl>::checkSignalsAndUpdate(ThreadID tid)
779{
780 // Check if there's a squash signal, squash if there is
781 // Check stall signals, block if there is.
782 // If status was Blocked
783 // if so then go to unblocking
784 // If status was Squashing
785 // check if squashing is not high. Switch to running this cycle.
786
787 readStallSignals(tid);
788
789 if (fromCommit->commitInfo[tid].squash) {
790 squash(tid);
791
792 if (dispatchStatus[tid] == Blocked ||
793 dispatchStatus[tid] == Unblocking) {
794 toRename->iewUnblock[tid] = true;
795 wroteToTimeBuffer = true;
796 }
797
798 dispatchStatus[tid] = Squashing;
799
800 fetchRedirect[tid] = false;
801 return;
802 }
803
804 if (fromCommit->commitInfo[tid].robSquashing) {
805 DPRINTF(IEW, "[tid:%i]: ROB is still squashing.\n", tid);
806
807 dispatchStatus[tid] = Squashing;
808
809 emptyRenameInsts(tid);
810 wroteToTimeBuffer = true;
811 return;
812 }
813
814 if (checkStall(tid)) {
815 block(tid);
816 dispatchStatus[tid] = Blocked;
817 return;
818 }
819
820 if (dispatchStatus[tid] == Blocked) {
821 // Status from previous cycle was blocked, but there are no more stall
822 // conditions. Switch over to unblocking.
823 DPRINTF(IEW, "[tid:%i]: Done blocking, switching to unblocking.\n",
824 tid);
825
826 dispatchStatus[tid] = Unblocking;
827
828 unblock(tid);
829
830 return;
831 }
832
833 if (dispatchStatus[tid] == Squashing) {
834 // Switch status to running if rename isn't being told to block or
835 // squash this cycle.
836 DPRINTF(IEW, "[tid:%i]: Done squashing, switching to running.\n",
837 tid);
838
839 dispatchStatus[tid] = Running;
840
841 return;
842 }
843}
844
845template <class Impl>
846void
847DefaultIEW<Impl>::sortInsts()
848{
849 int insts_from_rename = fromRename->size;
850#ifdef DEBUG
851 for (ThreadID tid = 0; tid < numThreads; tid++)
852 assert(insts[tid].empty());
853#endif
854 for (int i = 0; i < insts_from_rename; ++i) {
855 insts[fromRename->insts[i]->threadNumber].push(fromRename->insts[i]);
856 }
857}
858
859template <class Impl>
860void
861DefaultIEW<Impl>::emptyRenameInsts(ThreadID tid)
862{
863 DPRINTF(IEW, "[tid:%i]: Removing incoming rename instructions\n", tid);
864
865 while (!insts[tid].empty()) {
866
867 if (insts[tid].front()->isLoad() ||
868 insts[tid].front()->isStore() ) {
869 toRename->iewInfo[tid].dispatchedToLSQ++;
870 }
871
872 toRename->iewInfo[tid].dispatched++;
873
874 insts[tid].pop();
875 }
876}
877
878template <class Impl>
879void
880DefaultIEW<Impl>::wakeCPU()
881{
882 cpu->wakeCPU();
883}
884
885template <class Impl>
886void
887DefaultIEW<Impl>::activityThisCycle()
888{
889 DPRINTF(Activity, "Activity this cycle.\n");
890 cpu->activityThisCycle();
891}
892
893template <class Impl>
894inline void
895DefaultIEW<Impl>::activateStage()
896{
897 DPRINTF(Activity, "Activating stage.\n");
898 cpu->activateStage(O3CPU::IEWIdx);
899}
900
901template <class Impl>
902inline void
903DefaultIEW<Impl>::deactivateStage()
904{
905 DPRINTF(Activity, "Deactivating stage.\n");
906 cpu->deactivateStage(O3CPU::IEWIdx);
907}
908
909template<class Impl>
910void
911DefaultIEW<Impl>::dispatch(ThreadID tid)
912{
913 // If status is Running or idle,
914 // call dispatchInsts()
915 // If status is Unblocking,
916 // buffer any instructions coming from rename
917 // continue trying to empty skid buffer
918 // check if stall conditions have passed
919
920 if (dispatchStatus[tid] == Blocked) {
921 ++iewBlockCycles;
922
923 } else if (dispatchStatus[tid] == Squashing) {
924 ++iewSquashCycles;
925 }
926
927 // Dispatch should try to dispatch as many instructions as its bandwidth
928 // will allow, as long as it is not currently blocked.
929 if (dispatchStatus[tid] == Running ||
930 dispatchStatus[tid] == Idle) {
931 DPRINTF(IEW, "[tid:%i] Not blocked, so attempting to run "
932 "dispatch.\n", tid);
933
934 dispatchInsts(tid);
935 } else if (dispatchStatus[tid] == Unblocking) {
936 // Make sure that the skid buffer has something in it if the
937 // status is unblocking.
938 assert(!skidsEmpty());
939
940 // If the status was unblocking, then instructions from the skid
941 // buffer were used. Remove those instructions and handle
942 // the rest of unblocking.
943 dispatchInsts(tid);
944
945 ++iewUnblockCycles;
946
947 if (validInstsFromRename()) {
948 // Add the current inputs to the skid buffer so they can be
949 // reprocessed when this stage unblocks.
950 skidInsert(tid);
951 }
952
953 unblock(tid);
954 }
955}
956
957template <class Impl>
958void
959DefaultIEW<Impl>::dispatchInsts(ThreadID tid)
960{
961 // Obtain instructions from skid buffer if unblocking, or queue from rename
962 // otherwise.
963 std::queue<DynInstPtr> &insts_to_dispatch =
964 dispatchStatus[tid] == Unblocking ?
965 skidBuffer[tid] : insts[tid];
966
967 int insts_to_add = insts_to_dispatch.size();
968
969 DynInstPtr inst;
970 bool add_to_iq = false;
971 int dis_num_inst = 0;
972
973 // Loop through the instructions, putting them in the instruction
974 // queue.
975 for ( ; dis_num_inst < insts_to_add &&
976 dis_num_inst < dispatchWidth;
977 ++dis_num_inst)
978 {
979 inst = insts_to_dispatch.front();
980
981 if (dispatchStatus[tid] == Unblocking) {
982 DPRINTF(IEW, "[tid:%i]: Issue: Examining instruction from skid "
983 "buffer\n", tid);
984 }
985
986 // Make sure there's a valid instruction there.
987 assert(inst);
988
989 DPRINTF(IEW, "[tid:%i]: Issue: Adding PC %#x [sn:%lli] [tid:%i] to "
990 "IQ.\n",
991 tid, inst->readPC(), inst->seqNum, inst->threadNumber);
992
993 // Be sure to mark these instructions as ready so that the
994 // commit stage can go ahead and execute them, and mark
995 // them as issued so the IQ doesn't reprocess them.
996
997 // Check for squashed instructions.
998 if (inst->isSquashed()) {
999 DPRINTF(IEW, "[tid:%i]: Issue: Squashed instruction encountered, "
1000 "not adding to IQ.\n", tid);
1001
1002 ++iewDispSquashedInsts;
1003
1004 insts_to_dispatch.pop();
1005
1006 //Tell Rename That An Instruction has been processed
1007 if (inst->isLoad() || inst->isStore()) {
1008 toRename->iewInfo[tid].dispatchedToLSQ++;
1009 }
1010 toRename->iewInfo[tid].dispatched++;
1011
1012 continue;
1013 }
1014
1015 // Check for full conditions.
1016 if (instQueue.isFull(tid)) {
1017 DPRINTF(IEW, "[tid:%i]: Issue: IQ has become full.\n", tid);
1018
1019 // Call function to start blocking.
1020 block(tid);
1021
1022 // Set unblock to false. Special case where we are using
1023 // skidbuffer (unblocking) instructions but then we still
1024 // get full in the IQ.
1025 toRename->iewUnblock[tid] = false;
1026
1027 ++iewIQFullEvents;
1028 break;
1029 } else if (ldstQueue.isFull(tid)) {
1030 DPRINTF(IEW, "[tid:%i]: Issue: LSQ has become full.\n",tid);
1031
1032 // Call function to start blocking.
1033 block(tid);
1034
1035 // Set unblock to false. Special case where we are using
1036 // skidbuffer (unblocking) instructions but then we still
1037 // get full in the IQ.
1038 toRename->iewUnblock[tid] = false;
1039
1040 ++iewLSQFullEvents;
1041 break;
1042 }
1043
1044 // Otherwise issue the instruction just fine.
1045 if (inst->isLoad()) {
1046 DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1047 "encountered, adding to LSQ.\n", tid);
1048
1049 // Reserve a spot in the load store queue for this
1050 // memory access.
1051 ldstQueue.insertLoad(inst);
1052
1053 ++iewDispLoadInsts;
1054
1055 add_to_iq = true;
1056
1057 toRename->iewInfo[tid].dispatchedToLSQ++;
1058 } else if (inst->isStore()) {
1059 DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1060 "encountered, adding to LSQ.\n", tid);
1061
1062 ldstQueue.insertStore(inst);
1063
1064 ++iewDispStoreInsts;
1065
1066 if (inst->isStoreConditional()) {
1067 // Store conditionals need to be set as "canCommit()"
1068 // so that commit can process them when they reach the
1069 // head of commit.
1070 // @todo: This is somewhat specific to Alpha.
1071 inst->setCanCommit();
1072 instQueue.insertNonSpec(inst);
1073 add_to_iq = false;
1074
1075 ++iewDispNonSpecInsts;
1076 } else {
1077 add_to_iq = true;
1078 }
1079
1080 toRename->iewInfo[tid].dispatchedToLSQ++;
1081 } else if (inst->isMemBarrier() || inst->isWriteBarrier()) {
1082 // Same as non-speculative stores.
1083 inst->setCanCommit();
1084 instQueue.insertBarrier(inst);
1085 add_to_iq = false;
1086 } else if (inst->isNop()) {
1087 DPRINTF(IEW, "[tid:%i]: Issue: Nop instruction encountered, "
1088 "skipping.\n", tid);
1089
1090 inst->setIssued();
1091 inst->setExecuted();
1092 inst->setCanCommit();
1093
1094 instQueue.recordProducer(inst);
1095
1096 iewExecutedNop[tid]++;
1097
1098 add_to_iq = false;
1099 } else if (inst->isExecuted()) {
1100 assert(0 && "Instruction shouldn't be executed.\n");
1101 DPRINTF(IEW, "Issue: Executed branch encountered, "
1102 "skipping.\n");
1103
1104 inst->setIssued();
1105 inst->setCanCommit();
1106
1107 instQueue.recordProducer(inst);
1108
1109 add_to_iq = false;
1110 } else {
1111 add_to_iq = true;
1112 }
1113 if (inst->isNonSpeculative()) {
1114 DPRINTF(IEW, "[tid:%i]: Issue: Nonspeculative instruction "
1115 "encountered, skipping.\n", tid);
1116
1117 // Same as non-speculative stores.
1118 inst->setCanCommit();
1119
1120 // Specifically insert it as nonspeculative.
1121 instQueue.insertNonSpec(inst);
1122
1123 ++iewDispNonSpecInsts;
1124
1125 add_to_iq = false;
1126 }
1127
1128 // If the instruction queue is not full, then add the
1129 // instruction.
1130 if (add_to_iq) {
1131 instQueue.insert(inst);
1132 }
1133
1134 insts_to_dispatch.pop();
1135
1136 toRename->iewInfo[tid].dispatched++;
1137
1138 ++iewDispatchedInsts;
1139 }
1140
1141 if (!insts_to_dispatch.empty()) {
1142 DPRINTF(IEW,"[tid:%i]: Issue: Bandwidth Full. Blocking.\n", tid);
1143 block(tid);
1144 toRename->iewUnblock[tid] = false;
1145 }
1146
1147 if (dispatchStatus[tid] == Idle && dis_num_inst) {
1148 dispatchStatus[tid] = Running;
1149
1150 updatedQueues = true;
1151 }
1152
1153 dis_num_inst = 0;
1154}
1155
1156template <class Impl>
1157void
1158DefaultIEW<Impl>::printAvailableInsts()
1159{
1160 int inst = 0;
1161
1162 std::cout << "Available Instructions: ";
1163
1164 while (fromIssue->insts[inst]) {
1165
1166 if (inst%3==0) std::cout << "\n\t";
1167
1168 std::cout << "PC: " << fromIssue->insts[inst]->readPC()
1169 << " TN: " << fromIssue->insts[inst]->threadNumber
1170 << " SN: " << fromIssue->insts[inst]->seqNum << " | ";
1171
1172 inst++;
1173
1174 }
1175
1176 std::cout << "\n";
1177}
1178
1179template <class Impl>
1180void
1181DefaultIEW<Impl>::executeInsts()
1182{
1183 wbNumInst = 0;
1184 wbCycle = 0;
1185
1186 list<ThreadID>::iterator threads = activeThreads->begin();
1187 list<ThreadID>::iterator end = activeThreads->end();
1188
1189 while (threads != end) {
1190 ThreadID tid = *threads++;
1191 fetchRedirect[tid] = false;
1192 }
1193
1194 // Uncomment this if you want to see all available instructions.
1195 // @todo This doesn't actually work anymore, we should fix it.
1196// printAvailableInsts();
1197
1198 // Execute/writeback any instructions that are available.
1199 int insts_to_execute = fromIssue->size;
1200 int inst_num = 0;
1201 for (; inst_num < insts_to_execute;
1202 ++inst_num) {
1203
1204 DPRINTF(IEW, "Execute: Executing instructions from IQ.\n");
1205
1206 DynInstPtr inst = instQueue.getInstToExecute();
1207
1208 DPRINTF(IEW, "Execute: Processing PC %#x, [tid:%i] [sn:%i].\n",
1209 inst->readPC(), inst->threadNumber,inst->seqNum);
1210
1211 // Check if the instruction is squashed; if so then skip it
1212 if (inst->isSquashed()) {
1213 DPRINTF(IEW, "Execute: Instruction was squashed.\n");
1214
1215 // Consider this instruction executed so that commit can go
1216 // ahead and retire the instruction.
1217 inst->setExecuted();
1218
1219 // Not sure if I should set this here or just let commit try to
1220 // commit any squashed instructions. I like the latter a bit more.
1221 inst->setCanCommit();
1222
1223 ++iewExecSquashedInsts;
1224
1225 decrWb(inst->seqNum);
1226 continue;
1227 }
1228
1229 Fault fault = NoFault;
1230
1231 // Execute instruction.
1232 // Note that if the instruction faults, it will be handled
1233 // at the commit stage.
1234 if (inst->isMemRef() &&
1235 (!inst->isDataPrefetch() && !inst->isInstPrefetch())) {
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 } else if (inst->isStore()) {
1245 fault = ldstQueue.executeStore(inst);
1246
1247 // If the store had a fault then it may not have a mem req
1248 if (!inst->isStoreConditional() && fault == NoFault) {
1249 inst->setExecuted();
1250
1251 instToCommit(inst);
1252 } else if (fault != NoFault) {
1253 // If the instruction faulted, then we need to send it along to commit
1254 // without the instruction completing.
1255 DPRINTF(IEW, "Store has fault %s! [sn:%lli]\n",
1256 fault->name(), inst->seqNum);
1257
1258 // Send this instruction to commit, also make sure iew stage
1259 // realizes there is activity.
1260 inst->setExecuted();
1261
1262 instToCommit(inst);
1263 activityThisCycle();
1264 }
1265
1266 // Store conditionals will mark themselves as
1267 // executed, and their writeback event will add the
1268 // instruction to the queue to commit.
1269 } else {
1270 panic("Unexpected memory type!\n");
1271 }
1272
1273 } else {
1274 inst->execute();
1275
1276 inst->setExecuted();
1277
1278 instToCommit(inst);
1279 }
1280
1281 updateExeInstStats(inst);
1282
1283 // Check if branch prediction was correct, if not then we need
1284 // to tell commit to squash in flight instructions. Only
1285 // handle this if there hasn't already been something that
1286 // redirects fetch in this group of instructions.
1287
1288 // This probably needs to prioritize the redirects if a different
1289 // scheduler is used. Currently the scheduler schedules the oldest
1290 // instruction first, so the branch resolution order will be correct.
1291 ThreadID tid = inst->threadNumber;
1292
1293 if (!fetchRedirect[tid] ||
1294 toCommit->squashedSeqNum[tid] > inst->seqNum) {
1295
1296 if (inst->mispredicted()) {
1297 fetchRedirect[tid] = true;
1298
1299 DPRINTF(IEW, "Execute: Branch mispredict detected.\n");
1300 DPRINTF(IEW, "Predicted target was PC:%#x, NPC:%#x.\n",
1301 inst->readPredPC(), inst->readPredNPC());
1302 DPRINTF(IEW, "Execute: Redirecting fetch to PC: %#x,"
1303 " NPC: %#x.\n", inst->readNextPC(),
1304 inst->readNextNPC());
1305 // If incorrect, then signal the ROB that it must be squashed.
1306 squashDueToBranch(inst, tid);
1307
1308 if (inst->readPredTaken()) {
1309 predictedTakenIncorrect++;
1310 } else {
1311 predictedNotTakenIncorrect++;
1312 }
1313 } else if (ldstQueue.violation(tid)) {
1314 assert(inst->isMemRef());
1315 // If there was an ordering violation, then get the
1316 // DynInst that caused the violation. Note that this
1317 // clears the violation signal.
1318 DynInstPtr violator;
1319 violator = ldstQueue.getMemDepViolator(tid);
1320
|
1325 // Ensure the violating instruction is older than
1326 // current squash
1327/* if (fetchRedirect[tid] &&
1328 violator->seqNum >= toCommit->squashedSeqNum[tid] + 1)
1329 continue;
1330*/
1331 fetchRedirect[tid] = true;
1332
1333 // Tell the instruction queue that a violation has occured.
1334 instQueue.violation(inst, violator);
1335
1336 // Squash.
1337 squashDueToMemOrder(inst,tid);
1338
1339 ++memOrderViolationEvents;
1340 } else if (ldstQueue.loadBlocked(tid) &&
1341 !ldstQueue.isLoadBlockedHandled(tid)) {
1342 fetchRedirect[tid] = true;
1343
1344 DPRINTF(IEW, "Load operation couldn't execute because the "
1345 "memory system is blocked. PC: %#x [sn:%lli]\n",
1346 inst->readPC(), inst->seqNum);
1347
1348 squashDueToMemBlocked(inst, tid);
1349 }
1350 } else {
1351 // Reset any state associated with redirects that will not
1352 // be used.
1353 if (ldstQueue.violation(tid)) {
1354 assert(inst->isMemRef());
1355
1356 DynInstPtr violator = ldstQueue.getMemDepViolator(tid);
1357
1358 DPRINTF(IEW, "LDSTQ detected a violation. Violator PC: "
1359 "%#x, inst PC: %#x. Addr is: %#x.\n",
1360 violator->readPC(), inst->readPC(), inst->physEffAddr);
1361 DPRINTF(IEW, "Violation will not be handled because "
1362 "already squashing\n");
1363
1364 ++memOrderViolationEvents;
1365 }
1366 if (ldstQueue.loadBlocked(tid) &&
1367 !ldstQueue.isLoadBlockedHandled(tid)) {
1368 DPRINTF(IEW, "Load operation couldn't execute because the "
1369 "memory system is blocked. PC: %#x [sn:%lli]\n",
1370 inst->readPC(), inst->seqNum);
1371 DPRINTF(IEW, "Blocked load will not be handled because "
1372 "already squashing\n");
1373
1374 ldstQueue.setLoadBlockedHandled(tid);
1375 }
1376
1377 }
1378 }
1379
1380 // Update and record activity if we processed any instructions.
1381 if (inst_num) {
1382 if (exeStatus == Idle) {
1383 exeStatus = Running;
1384 }
1385
1386 updatedQueues = true;
1387
1388 cpu->activityThisCycle();
1389 }
1390
1391 // Need to reset this in case a writeback event needs to write into the
1392 // iew queue. That way the writeback event will write into the correct
1393 // spot in the queue.
1394 wbNumInst = 0;
1395}
1396
1397template <class Impl>
1398void
1399DefaultIEW<Impl>::writebackInsts()
1400{
1401 // Loop through the head of the time buffer and wake any
1402 // dependents. These instructions are about to write back. Also
1403 // mark scoreboard that this instruction is finally complete.
1404 // Either have IEW have direct access to scoreboard, or have this
1405 // as part of backwards communication.
1406 for (int inst_num = 0; inst_num < wbWidth &&
1407 toCommit->insts[inst_num]; inst_num++) {
1408 DynInstPtr inst = toCommit->insts[inst_num];
1409 ThreadID tid = inst->threadNumber;
1410
1411 DPRINTF(IEW, "Sending instructions to commit, [sn:%lli] PC %#x.\n",
1412 inst->seqNum, inst->readPC());
1413
1414 iewInstsToCommit[tid]++;
1415
1416 // Some instructions will be sent to commit without having
1417 // executed because they need commit to handle them.
1418 // E.g. Uncached loads have not actually executed when they
1419 // are first sent to commit. Instead commit must tell the LSQ
1420 // when it's ready to execute the uncached load.
1421 if (!inst->isSquashed() && inst->isExecuted() && inst->getFault() == NoFault) {
1422 int dependents = instQueue.wakeDependents(inst);
1423
1424 for (int i = 0; i < inst->numDestRegs(); i++) {
1425 //mark as Ready
1426 DPRINTF(IEW,"Setting Destination Register %i\n",
1427 inst->renamedDestRegIdx(i));
1428 scoreboard->setReg(inst->renamedDestRegIdx(i));
1429 }
1430
1431 if (dependents) {
1432 producerInst[tid]++;
1433 consumerInst[tid]+= dependents;
1434 }
1435 writebackCount[tid]++;
1436 }
1437
1438 decrWb(inst->seqNum);
1439 }
1440}
1441
1442template<class Impl>
1443void
1444DefaultIEW<Impl>::tick()
1445{
1446 wbNumInst = 0;
1447 wbCycle = 0;
1448
1449 wroteToTimeBuffer = false;
1450 updatedQueues = false;
1451
1452 sortInsts();
1453
1454 // Free function units marked as being freed this cycle.
1455 fuPool->processFreeUnits();
1456
1457 list<ThreadID>::iterator threads = activeThreads->begin();
1458 list<ThreadID>::iterator end = activeThreads->end();
1459
1460 // Check stall and squash signals, dispatch any instructions.
1461 while (threads != end) {
1462 ThreadID tid = *threads++;
1463
1464 DPRINTF(IEW,"Issue: Processing [tid:%i]\n",tid);
1465
1466 checkSignalsAndUpdate(tid);
1467 dispatch(tid);
1468 }
1469
1470 if (exeStatus != Squashing) {
1471 executeInsts();
1472
1473 writebackInsts();
1474
1475 // Have the instruction queue try to schedule any ready instructions.
1476 // (In actuality, this scheduling is for instructions that will
1477 // be executed next cycle.)
1478 instQueue.scheduleReadyInsts();
1479
1480 // Also should advance its own time buffers if the stage ran.
1481 // Not the best place for it, but this works (hopefully).
1482 issueToExecQueue.advance();
1483 }
1484
1485 bool broadcast_free_entries = false;
1486
1487 if (updatedQueues || exeStatus == Running || updateLSQNextCycle) {
1488 exeStatus = Idle;
1489 updateLSQNextCycle = false;
1490
1491 broadcast_free_entries = true;
1492 }
1493
1494 // Writeback any stores using any leftover bandwidth.
1495 ldstQueue.writebackStores();
1496
1497 // Check the committed load/store signals to see if there's a load
1498 // or store to commit. Also check if it's being told to execute a
1499 // nonspeculative instruction.
1500 // This is pretty inefficient...
1501
1502 threads = activeThreads->begin();
1503 while (threads != end) {
1504 ThreadID tid = (*threads++);
1505
1506 DPRINTF(IEW,"Processing [tid:%i]\n",tid);
1507
1508 // Update structures based on instructions committed.
1509 if (fromCommit->commitInfo[tid].doneSeqNum != 0 &&
1510 !fromCommit->commitInfo[tid].squash &&
1511 !fromCommit->commitInfo[tid].robSquashing) {
1512
1513 ldstQueue.commitStores(fromCommit->commitInfo[tid].doneSeqNum,tid);
1514
1515 ldstQueue.commitLoads(fromCommit->commitInfo[tid].doneSeqNum,tid);
1516
1517 updateLSQNextCycle = true;
1518 instQueue.commit(fromCommit->commitInfo[tid].doneSeqNum,tid);
1519 }
1520
1521 if (fromCommit->commitInfo[tid].nonSpecSeqNum != 0) {
1522
1523 //DPRINTF(IEW,"NonspecInst from thread %i",tid);
1524 if (fromCommit->commitInfo[tid].uncached) {
1525 instQueue.replayMemInst(fromCommit->commitInfo[tid].uncachedLoad);
1526 fromCommit->commitInfo[tid].uncachedLoad->setAtCommit();
1527 } else {
1528 instQueue.scheduleNonSpec(
1529 fromCommit->commitInfo[tid].nonSpecSeqNum);
1530 }
1531 }
1532
1533 if (broadcast_free_entries) {
1534 toFetch->iewInfo[tid].iqCount =
1535 instQueue.getCount(tid);
1536 toFetch->iewInfo[tid].ldstqCount =
1537 ldstQueue.getCount(tid);
1538
1539 toRename->iewInfo[tid].usedIQ = true;
1540 toRename->iewInfo[tid].freeIQEntries =
1541 instQueue.numFreeEntries();
1542 toRename->iewInfo[tid].usedLSQ = true;
1543 toRename->iewInfo[tid].freeLSQEntries =
1544 ldstQueue.numFreeEntries(tid);
1545
1546 wroteToTimeBuffer = true;
1547 }
1548
1549 DPRINTF(IEW, "[tid:%i], Dispatch dispatched %i instructions.\n",
1550 tid, toRename->iewInfo[tid].dispatched);
1551 }
1552
1553 DPRINTF(IEW, "IQ has %i free entries (Can schedule: %i). "
1554 "LSQ has %i free entries.\n",
1555 instQueue.numFreeEntries(), instQueue.hasReadyInsts(),
1556 ldstQueue.numFreeEntries());
1557
1558 updateStatus();
1559
1560 if (wroteToTimeBuffer) {
1561 DPRINTF(Activity, "Activity this cycle.\n");
1562 cpu->activityThisCycle();
1563 }
1564}
1565
1566template <class Impl>
1567void
1568DefaultIEW<Impl>::updateExeInstStats(DynInstPtr &inst)
1569{
1570 ThreadID tid = inst->threadNumber;
1571
1572 //
1573 // Pick off the software prefetches
1574 //
1575#ifdef TARGET_ALPHA
1576 if (inst->isDataPrefetch())
1577 iewExecutedSwp[tid]++;
1578 else
1579 iewIewExecutedcutedInsts++;
1580#else
1581 iewExecutedInsts++;
1582#endif
1583
1584 //
1585 // Control operations
1586 //
1587 if (inst->isControl())
1588 iewExecutedBranches[tid]++;
1589
1590 //
1591 // Memory operations
1592 //
1593 if (inst->isMemRef()) {
1594 iewExecutedRefs[tid]++;
1595
1596 if (inst->isLoad()) {
1597 iewExecLoadInsts[tid]++;
1598 }
1599 }
1600}
1601
1602template <class Impl>
1603void
1604DefaultIEW<Impl>::checkMisprediction(DynInstPtr &inst)
1605{
1606 ThreadID tid = inst->threadNumber;
1607
1608 if (!fetchRedirect[tid] ||
1609 toCommit->squashedSeqNum[tid] > inst->seqNum) {
1610
1611 if (inst->mispredicted()) {
1612 fetchRedirect[tid] = true;
1613
1614 DPRINTF(IEW, "Execute: Branch mispredict detected.\n");
1615 DPRINTF(IEW, "Predicted target was PC:%#x, NPC:%#x.\n",
1616 inst->readPredPC(), inst->readPredNPC());
1617 DPRINTF(IEW, "Execute: Redirecting fetch to PC: %#x,"
1618 " NPC: %#x.\n", inst->readNextPC(),
1619 inst->readNextNPC());
1620 // If incorrect, then signal the ROB that it must be squashed.
1621 squashDueToBranch(inst, tid);
1622
1623 if (inst->readPredTaken()) {
1624 predictedTakenIncorrect++;
1625 } else {
1626 predictedNotTakenIncorrect++;
1627 }
1628 }
1629 }
1630}
| 1325 // Ensure the violating instruction is older than
1326 // current squash
1327/* if (fetchRedirect[tid] &&
1328 violator->seqNum >= toCommit->squashedSeqNum[tid] + 1)
1329 continue;
1330*/
1331 fetchRedirect[tid] = true;
1332
1333 // Tell the instruction queue that a violation has occured.
1334 instQueue.violation(inst, violator);
1335
1336 // Squash.
1337 squashDueToMemOrder(inst,tid);
1338
1339 ++memOrderViolationEvents;
1340 } else if (ldstQueue.loadBlocked(tid) &&
1341 !ldstQueue.isLoadBlockedHandled(tid)) {
1342 fetchRedirect[tid] = true;
1343
1344 DPRINTF(IEW, "Load operation couldn't execute because the "
1345 "memory system is blocked. PC: %#x [sn:%lli]\n",
1346 inst->readPC(), inst->seqNum);
1347
1348 squashDueToMemBlocked(inst, tid);
1349 }
1350 } else {
1351 // Reset any state associated with redirects that will not
1352 // be used.
1353 if (ldstQueue.violation(tid)) {
1354 assert(inst->isMemRef());
1355
1356 DynInstPtr violator = ldstQueue.getMemDepViolator(tid);
1357
1358 DPRINTF(IEW, "LDSTQ detected a violation. Violator PC: "
1359 "%#x, inst PC: %#x. Addr is: %#x.\n",
1360 violator->readPC(), inst->readPC(), inst->physEffAddr);
1361 DPRINTF(IEW, "Violation will not be handled because "
1362 "already squashing\n");
1363
1364 ++memOrderViolationEvents;
1365 }
1366 if (ldstQueue.loadBlocked(tid) &&
1367 !ldstQueue.isLoadBlockedHandled(tid)) {
1368 DPRINTF(IEW, "Load operation couldn't execute because the "
1369 "memory system is blocked. PC: %#x [sn:%lli]\n",
1370 inst->readPC(), inst->seqNum);
1371 DPRINTF(IEW, "Blocked load will not be handled because "
1372 "already squashing\n");
1373
1374 ldstQueue.setLoadBlockedHandled(tid);
1375 }
1376
1377 }
1378 }
1379
1380 // Update and record activity if we processed any instructions.
1381 if (inst_num) {
1382 if (exeStatus == Idle) {
1383 exeStatus = Running;
1384 }
1385
1386 updatedQueues = true;
1387
1388 cpu->activityThisCycle();
1389 }
1390
1391 // Need to reset this in case a writeback event needs to write into the
1392 // iew queue. That way the writeback event will write into the correct
1393 // spot in the queue.
1394 wbNumInst = 0;
1395}
1396
1397template <class Impl>
1398void
1399DefaultIEW<Impl>::writebackInsts()
1400{
1401 // Loop through the head of the time buffer and wake any
1402 // dependents. These instructions are about to write back. Also
1403 // mark scoreboard that this instruction is finally complete.
1404 // Either have IEW have direct access to scoreboard, or have this
1405 // as part of backwards communication.
1406 for (int inst_num = 0; inst_num < wbWidth &&
1407 toCommit->insts[inst_num]; inst_num++) {
1408 DynInstPtr inst = toCommit->insts[inst_num];
1409 ThreadID tid = inst->threadNumber;
1410
1411 DPRINTF(IEW, "Sending instructions to commit, [sn:%lli] PC %#x.\n",
1412 inst->seqNum, inst->readPC());
1413
1414 iewInstsToCommit[tid]++;
1415
1416 // Some instructions will be sent to commit without having
1417 // executed because they need commit to handle them.
1418 // E.g. Uncached loads have not actually executed when they
1419 // are first sent to commit. Instead commit must tell the LSQ
1420 // when it's ready to execute the uncached load.
1421 if (!inst->isSquashed() && inst->isExecuted() && inst->getFault() == NoFault) {
1422 int dependents = instQueue.wakeDependents(inst);
1423
1424 for (int i = 0; i < inst->numDestRegs(); i++) {
1425 //mark as Ready
1426 DPRINTF(IEW,"Setting Destination Register %i\n",
1427 inst->renamedDestRegIdx(i));
1428 scoreboard->setReg(inst->renamedDestRegIdx(i));
1429 }
1430
1431 if (dependents) {
1432 producerInst[tid]++;
1433 consumerInst[tid]+= dependents;
1434 }
1435 writebackCount[tid]++;
1436 }
1437
1438 decrWb(inst->seqNum);
1439 }
1440}
1441
1442template<class Impl>
1443void
1444DefaultIEW<Impl>::tick()
1445{
1446 wbNumInst = 0;
1447 wbCycle = 0;
1448
1449 wroteToTimeBuffer = false;
1450 updatedQueues = false;
1451
1452 sortInsts();
1453
1454 // Free function units marked as being freed this cycle.
1455 fuPool->processFreeUnits();
1456
1457 list<ThreadID>::iterator threads = activeThreads->begin();
1458 list<ThreadID>::iterator end = activeThreads->end();
1459
1460 // Check stall and squash signals, dispatch any instructions.
1461 while (threads != end) {
1462 ThreadID tid = *threads++;
1463
1464 DPRINTF(IEW,"Issue: Processing [tid:%i]\n",tid);
1465
1466 checkSignalsAndUpdate(tid);
1467 dispatch(tid);
1468 }
1469
1470 if (exeStatus != Squashing) {
1471 executeInsts();
1472
1473 writebackInsts();
1474
1475 // Have the instruction queue try to schedule any ready instructions.
1476 // (In actuality, this scheduling is for instructions that will
1477 // be executed next cycle.)
1478 instQueue.scheduleReadyInsts();
1479
1480 // Also should advance its own time buffers if the stage ran.
1481 // Not the best place for it, but this works (hopefully).
1482 issueToExecQueue.advance();
1483 }
1484
1485 bool broadcast_free_entries = false;
1486
1487 if (updatedQueues || exeStatus == Running || updateLSQNextCycle) {
1488 exeStatus = Idle;
1489 updateLSQNextCycle = false;
1490
1491 broadcast_free_entries = true;
1492 }
1493
1494 // Writeback any stores using any leftover bandwidth.
1495 ldstQueue.writebackStores();
1496
1497 // Check the committed load/store signals to see if there's a load
1498 // or store to commit. Also check if it's being told to execute a
1499 // nonspeculative instruction.
1500 // This is pretty inefficient...
1501
1502 threads = activeThreads->begin();
1503 while (threads != end) {
1504 ThreadID tid = (*threads++);
1505
1506 DPRINTF(IEW,"Processing [tid:%i]\n",tid);
1507
1508 // Update structures based on instructions committed.
1509 if (fromCommit->commitInfo[tid].doneSeqNum != 0 &&
1510 !fromCommit->commitInfo[tid].squash &&
1511 !fromCommit->commitInfo[tid].robSquashing) {
1512
1513 ldstQueue.commitStores(fromCommit->commitInfo[tid].doneSeqNum,tid);
1514
1515 ldstQueue.commitLoads(fromCommit->commitInfo[tid].doneSeqNum,tid);
1516
1517 updateLSQNextCycle = true;
1518 instQueue.commit(fromCommit->commitInfo[tid].doneSeqNum,tid);
1519 }
1520
1521 if (fromCommit->commitInfo[tid].nonSpecSeqNum != 0) {
1522
1523 //DPRINTF(IEW,"NonspecInst from thread %i",tid);
1524 if (fromCommit->commitInfo[tid].uncached) {
1525 instQueue.replayMemInst(fromCommit->commitInfo[tid].uncachedLoad);
1526 fromCommit->commitInfo[tid].uncachedLoad->setAtCommit();
1527 } else {
1528 instQueue.scheduleNonSpec(
1529 fromCommit->commitInfo[tid].nonSpecSeqNum);
1530 }
1531 }
1532
1533 if (broadcast_free_entries) {
1534 toFetch->iewInfo[tid].iqCount =
1535 instQueue.getCount(tid);
1536 toFetch->iewInfo[tid].ldstqCount =
1537 ldstQueue.getCount(tid);
1538
1539 toRename->iewInfo[tid].usedIQ = true;
1540 toRename->iewInfo[tid].freeIQEntries =
1541 instQueue.numFreeEntries();
1542 toRename->iewInfo[tid].usedLSQ = true;
1543 toRename->iewInfo[tid].freeLSQEntries =
1544 ldstQueue.numFreeEntries(tid);
1545
1546 wroteToTimeBuffer = true;
1547 }
1548
1549 DPRINTF(IEW, "[tid:%i], Dispatch dispatched %i instructions.\n",
1550 tid, toRename->iewInfo[tid].dispatched);
1551 }
1552
1553 DPRINTF(IEW, "IQ has %i free entries (Can schedule: %i). "
1554 "LSQ has %i free entries.\n",
1555 instQueue.numFreeEntries(), instQueue.hasReadyInsts(),
1556 ldstQueue.numFreeEntries());
1557
1558 updateStatus();
1559
1560 if (wroteToTimeBuffer) {
1561 DPRINTF(Activity, "Activity this cycle.\n");
1562 cpu->activityThisCycle();
1563 }
1564}
1565
1566template <class Impl>
1567void
1568DefaultIEW<Impl>::updateExeInstStats(DynInstPtr &inst)
1569{
1570 ThreadID tid = inst->threadNumber;
1571
1572 //
1573 // Pick off the software prefetches
1574 //
1575#ifdef TARGET_ALPHA
1576 if (inst->isDataPrefetch())
1577 iewExecutedSwp[tid]++;
1578 else
1579 iewIewExecutedcutedInsts++;
1580#else
1581 iewExecutedInsts++;
1582#endif
1583
1584 //
1585 // Control operations
1586 //
1587 if (inst->isControl())
1588 iewExecutedBranches[tid]++;
1589
1590 //
1591 // Memory operations
1592 //
1593 if (inst->isMemRef()) {
1594 iewExecutedRefs[tid]++;
1595
1596 if (inst->isLoad()) {
1597 iewExecLoadInsts[tid]++;
1598 }
1599 }
1600}
1601
1602template <class Impl>
1603void
1604DefaultIEW<Impl>::checkMisprediction(DynInstPtr &inst)
1605{
1606 ThreadID tid = inst->threadNumber;
1607
1608 if (!fetchRedirect[tid] ||
1609 toCommit->squashedSeqNum[tid] > inst->seqNum) {
1610
1611 if (inst->mispredicted()) {
1612 fetchRedirect[tid] = true;
1613
1614 DPRINTF(IEW, "Execute: Branch mispredict detected.\n");
1615 DPRINTF(IEW, "Predicted target was PC:%#x, NPC:%#x.\n",
1616 inst->readPredPC(), inst->readPredNPC());
1617 DPRINTF(IEW, "Execute: Redirecting fetch to PC: %#x,"
1618 " NPC: %#x.\n", inst->readNextPC(),
1619 inst->readNextNPC());
1620 // If incorrect, then signal the ROB that it must be squashed.
1621 squashDueToBranch(inst, tid);
1622
1623 if (inst->readPredTaken()) {
1624 predictedTakenIncorrect++;
1625 } else {
1626 predictedNotTakenIncorrect++;
1627 }
1628 }
1629 }
1630}
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