1/*
2 * Copyright (c) 2004-2006 The Regents of The University of Michigan
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * Authors: Kevin Lim
29 */
30
31// @todo: Fix the instantaneous communication among all the stages within
32// iew. There's a clear delay between issue and execute, yet backwards
33// communication happens simultaneously.
34
35#include <queue>
36
37#include "base/timebuf.hh"
38#include "cpu/o3/fu_pool.hh"
39#include "cpu/o3/iew.hh"
40
41using namespace std;
42
43template<class Impl>
44DefaultIEW<Impl>::DefaultIEW(Params *params)
45 : issueToExecQueue(params->backComSize, params->forwardComSize),
46 instQueue(params),
47 ldstQueue(params),
48 fuPool(params->fuPool),
49 commitToIEWDelay(params->commitToIEWDelay),
50 renameToIEWDelay(params->renameToIEWDelay),
51 issueToExecuteDelay(params->issueToExecuteDelay),
52 dispatchWidth(params->dispatchWidth),
53 issueWidth(params->issueWidth),
54 wbOutstanding(0),
55 wbWidth(params->wbWidth),
56 numThreads(params->numberOfThreads),
57 switchedOut(false)
58{
59 _status = Active;
60 exeStatus = Running;
61 wbStatus = Idle;
62
63 // Setup wire to read instructions coming from issue.
64 fromIssue = issueToExecQueue.getWire(-issueToExecuteDelay);
65
66 // Instruction queue needs the queue between issue and execute.
67 instQueue.setIssueToExecuteQueue(&issueToExecQueue);
68
69 instQueue.setIEW(this);
70 ldstQueue.setIEW(this);
71
72 for (int i=0; i < numThreads; i++) {
73 dispatchStatus[i] = Running;
74 stalls[i].commit = false;
75 fetchRedirect[i] = false;
76 bdelayDoneSeqNum[i] = 0;
77 }
78
79 wbMax = wbWidth * params->wbDepth;
80
81 updateLSQNextCycle = false;
82
83 ableToIssue = true;
84
85 skidBufferMax = (3 * (renameToIEWDelay * params->renameWidth)) + issueWidth;
86}
87
88template <class Impl>
89std::string
90DefaultIEW<Impl>::name() const
91{
92 return cpu->name() + ".iew";
93}
94
95template <class Impl>
96void
97DefaultIEW<Impl>::regStats()
98{
99 using namespace Stats;
100
101 instQueue.regStats();
102 ldstQueue.regStats();
103
104 iewIdleCycles
105 .name(name() + ".iewIdleCycles")
106 .desc("Number of cycles IEW is idle");
107
108 iewSquashCycles
109 .name(name() + ".iewSquashCycles")
110 .desc("Number of cycles IEW is squashing");
111
112 iewBlockCycles
113 .name(name() + ".iewBlockCycles")
114 .desc("Number of cycles IEW is blocking");
115
116 iewUnblockCycles
117 .name(name() + ".iewUnblockCycles")
118 .desc("Number of cycles IEW is unblocking");
119
120 iewDispatchedInsts
121 .name(name() + ".iewDispatchedInsts")
122 .desc("Number of instructions dispatched to IQ");
123
124 iewDispSquashedInsts
125 .name(name() + ".iewDispSquashedInsts")
126 .desc("Number of squashed instructions skipped by dispatch");
127
128 iewDispLoadInsts
129 .name(name() + ".iewDispLoadInsts")
130 .desc("Number of dispatched load instructions");
131
132 iewDispStoreInsts
133 .name(name() + ".iewDispStoreInsts")
134 .desc("Number of dispatched store instructions");
135
136 iewDispNonSpecInsts
137 .name(name() + ".iewDispNonSpecInsts")
138 .desc("Number of dispatched non-speculative instructions");
139
140 iewIQFullEvents
141 .name(name() + ".iewIQFullEvents")
142 .desc("Number of times the IQ has become full, causing a stall");
143
144 iewLSQFullEvents
145 .name(name() + ".iewLSQFullEvents")
146 .desc("Number of times the LSQ has become full, causing a stall");
147
148 memOrderViolationEvents
149 .name(name() + ".memOrderViolationEvents")
150 .desc("Number of memory order violations");
151
152 predictedTakenIncorrect
153 .name(name() + ".predictedTakenIncorrect")
154 .desc("Number of branches that were predicted taken incorrectly");
155
156 predictedNotTakenIncorrect
157 .name(name() + ".predictedNotTakenIncorrect")
158 .desc("Number of branches that were predicted not taken incorrectly");
159
160 branchMispredicts
161 .name(name() + ".branchMispredicts")
162 .desc("Number of branch mispredicts detected at execute");
163
164 branchMispredicts = predictedTakenIncorrect + predictedNotTakenIncorrect;
165
166 iewExecutedInsts
167 .name(name() + ".EXEC:insts")
168 .desc("Number of executed instructions");
169
170 iewExecLoadInsts
171 .init(cpu->number_of_threads)
172 .name(name() + ".EXEC:loads")
173 .desc("Number of load instructions executed")
174 .flags(total);
175
176 iewExecSquashedInsts
177 .name(name() + ".EXEC:squashedInsts")
178 .desc("Number of squashed instructions skipped in execute");
179
180 iewExecutedSwp
181 .init(cpu->number_of_threads)
182 .name(name() + ".EXEC:swp")
183 .desc("number of swp insts executed")
184 .flags(total);
185
186 iewExecutedNop
187 .init(cpu->number_of_threads)
188 .name(name() + ".EXEC:nop")
189 .desc("number of nop insts executed")
190 .flags(total);
191
192 iewExecutedRefs
193 .init(cpu->number_of_threads)
194 .name(name() + ".EXEC:refs")
195 .desc("number of memory reference insts executed")
196 .flags(total);
197
198 iewExecutedBranches
199 .init(cpu->number_of_threads)
200 .name(name() + ".EXEC:branches")
201 .desc("Number of branches executed")
202 .flags(total);
203
204 iewExecStoreInsts
205 .name(name() + ".EXEC:stores")
206 .desc("Number of stores executed")
207 .flags(total);
208 iewExecStoreInsts = iewExecutedRefs - iewExecLoadInsts;
209
210 iewExecRate
211 .name(name() + ".EXEC:rate")
212 .desc("Inst execution rate")
213 .flags(total);
214
215 iewExecRate = iewExecutedInsts / cpu->numCycles;
216
217 iewInstsToCommit
218 .init(cpu->number_of_threads)
219 .name(name() + ".WB:sent")
220 .desc("cumulative count of insts sent to commit")
221 .flags(total);
222
223 writebackCount
224 .init(cpu->number_of_threads)
225 .name(name() + ".WB:count")
226 .desc("cumulative count of insts written-back")
227 .flags(total);
228
229 producerInst
230 .init(cpu->number_of_threads)
231 .name(name() + ".WB:producers")
232 .desc("num instructions producing a value")
233 .flags(total);
234
235 consumerInst
236 .init(cpu->number_of_threads)
237 .name(name() + ".WB:consumers")
238 .desc("num instructions consuming a value")
239 .flags(total);
240
241 wbPenalized
242 .init(cpu->number_of_threads)
243 .name(name() + ".WB:penalized")
244 .desc("number of instrctions required to write to 'other' IQ")
245 .flags(total);
246
247 wbPenalizedRate
248 .name(name() + ".WB:penalized_rate")
249 .desc ("fraction of instructions written-back that wrote to 'other' IQ")
250 .flags(total);
251
252 wbPenalizedRate = wbPenalized / writebackCount;
253
254 wbFanout
255 .name(name() + ".WB:fanout")
256 .desc("average fanout of values written-back")
257 .flags(total);
258
259 wbFanout = producerInst / consumerInst;
260
261 wbRate
262 .name(name() + ".WB:rate")
263 .desc("insts written-back per cycle")
264 .flags(total);
265 wbRate = writebackCount / cpu->numCycles;
266}
267
268template<class Impl>
269void
270DefaultIEW<Impl>::initStage()
271{
272 for (int tid=0; tid < numThreads; tid++) {
273 toRename->iewInfo[tid].usedIQ = true;
274 toRename->iewInfo[tid].freeIQEntries =
275 instQueue.numFreeEntries(tid);
276
277 toRename->iewInfo[tid].usedLSQ = true;
278 toRename->iewInfo[tid].freeLSQEntries =
279 ldstQueue.numFreeEntries(tid);
280 }
281}
282
283template<class Impl>
284void
285DefaultIEW<Impl>::setCPU(O3CPU *cpu_ptr)
286{
287 DPRINTF(IEW, "Setting CPU pointer.\n");
288 cpu = cpu_ptr;
289
290 instQueue.setCPU(cpu_ptr);
291 ldstQueue.setCPU(cpu_ptr);
292
293 cpu->activateStage(O3CPU::IEWIdx);
294}
295
296template<class Impl>
297void
298DefaultIEW<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr)
299{
300 DPRINTF(IEW, "Setting time buffer pointer.\n");
301 timeBuffer = tb_ptr;
302
303 // Setup wire to read information from time buffer, from commit.
304 fromCommit = timeBuffer->getWire(-commitToIEWDelay);
305
306 // Setup wire to write information back to previous stages.
307 toRename = timeBuffer->getWire(0);
308
309 toFetch = timeBuffer->getWire(0);
310
311 // Instruction queue also needs main time buffer.
312 instQueue.setTimeBuffer(tb_ptr);
313}
314
315template<class Impl>
316void
317DefaultIEW<Impl>::setRenameQueue(TimeBuffer<RenameStruct> *rq_ptr)
318{
319 DPRINTF(IEW, "Setting rename queue pointer.\n");
320 renameQueue = rq_ptr;
321
322 // Setup wire to read information from rename queue.
323 fromRename = renameQueue->getWire(-renameToIEWDelay);
324}
325
326template<class Impl>
327void
328DefaultIEW<Impl>::setIEWQueue(TimeBuffer<IEWStruct> *iq_ptr)
329{
330 DPRINTF(IEW, "Setting IEW queue pointer.\n");
331 iewQueue = iq_ptr;
332
333 // Setup wire to write instructions to commit.
334 toCommit = iewQueue->getWire(0);
335}
336
337template<class Impl>
338void
339DefaultIEW<Impl>::setActiveThreads(list<unsigned> *at_ptr)
340{
341 DPRINTF(IEW, "Setting active threads list pointer.\n");
342 activeThreads = at_ptr;
343
344 ldstQueue.setActiveThreads(at_ptr);
345 instQueue.setActiveThreads(at_ptr);
346}
347
348template<class Impl>
349void
350DefaultIEW<Impl>::setScoreboard(Scoreboard *sb_ptr)
351{
352 DPRINTF(IEW, "Setting scoreboard pointer.\n");
353 scoreboard = sb_ptr;
354}
355
356template <class Impl>
357bool
358DefaultIEW<Impl>::drain()
359{
360 // IEW is ready to drain at any time.
361 cpu->signalDrained();
362 return true;
363}
364
365template <class Impl>
366void
367DefaultIEW<Impl>::resume()
368{
369}
370
371template <class Impl>
372void
373DefaultIEW<Impl>::switchOut()
374{
375 // Clear any state.
376 switchedOut = true;
377
378 instQueue.switchOut();
379 ldstQueue.switchOut();
380 fuPool->switchOut();
381
382 for (int i = 0; i < numThreads; i++) {
383 while (!insts[i].empty())
384 insts[i].pop();
385 while (!skidBuffer[i].empty())
386 skidBuffer[i].pop();
387 }
388}
389
390template <class Impl>
391void
392DefaultIEW<Impl>::takeOverFrom()
393{
394 // Reset all state.
395 _status = Active;
396 exeStatus = Running;
397 wbStatus = Idle;
398 switchedOut = false;
399
400 instQueue.takeOverFrom();
401 ldstQueue.takeOverFrom();
402 fuPool->takeOverFrom();
403
404 initStage();
405 cpu->activityThisCycle();
406
407 for (int i=0; i < numThreads; i++) {
408 dispatchStatus[i] = Running;
409 stalls[i].commit = false;
410 fetchRedirect[i] = false;
411 }
412
413 updateLSQNextCycle = false;
414
415 // @todo: Fix hardcoded number
416 for (int i = 0; i < issueToExecQueue.getSize(); ++i) {
417 issueToExecQueue.advance();
418 }
419}
420
421template<class Impl>
422void
423DefaultIEW<Impl>::squash(unsigned tid)
424{
425 DPRINTF(IEW, "[tid:%i]: Squashing all instructions.\n",
426 tid);
427
428 // Tell the IQ to start squashing.
429 instQueue.squash(tid);
430
431 // Tell the LDSTQ to start squashing.
432#if THE_ISA == ALPHA_ISA
433 ldstQueue.squash(fromCommit->commitInfo[tid].doneSeqNum, tid);
434#else
435 ldstQueue.squash(fromCommit->commitInfo[tid].bdelayDoneSeqNum, tid);
436#endif
437 updatedQueues = true;
438
439 // Clear the skid buffer in case it has any data in it.
440 DPRINTF(IEW, "[tid:%i]: Removing skidbuffer instructions until [sn:%i].\n",
441 tid, fromCommit->commitInfo[tid].bdelayDoneSeqNum);
442
443 while (!skidBuffer[tid].empty()) {
444#if THE_ISA != ALPHA_ISA
445 if (skidBuffer[tid].front()->seqNum <=
446 fromCommit->commitInfo[tid].bdelayDoneSeqNum) {
447 DPRINTF(IEW, "[tid:%i]: Cannot remove skidbuffer instructions "
448 "that occur before delay slot [sn:%i].\n",
449 fromCommit->commitInfo[tid].bdelayDoneSeqNum,
450 tid);
451 break;
452 } else {
453 DPRINTF(IEW, "[tid:%i]: Removing instruction [sn:%i] from "
454 "skidBuffer.\n", tid, skidBuffer[tid].front()->seqNum);
455 }
456#endif
457 if (skidBuffer[tid].front()->isLoad() ||
458 skidBuffer[tid].front()->isStore() ) {
459 toRename->iewInfo[tid].dispatchedToLSQ++;
460 }
461
462 toRename->iewInfo[tid].dispatched++;
463
464 skidBuffer[tid].pop();
465 }
466
467 bdelayDoneSeqNum[tid] = fromCommit->commitInfo[tid].bdelayDoneSeqNum;
468
469 emptyRenameInsts(tid);
470}
471
472template<class Impl>
473void
474DefaultIEW<Impl>::squashDueToBranch(DynInstPtr &inst, unsigned tid)
475{
476 DPRINTF(IEW, "[tid:%i]: Squashing from a specific instruction, PC: %#x "
477 "[sn:%i].\n", tid, inst->readPC(), inst->seqNum);
478
479 toCommit->squash[tid] = true;
480 toCommit->squashedSeqNum[tid] = inst->seqNum;
481 toCommit->mispredPC[tid] = inst->readPC();
482 toCommit->branchMispredict[tid] = true;
483
484#if THE_ISA == ALPHA_ISA
485 toCommit->branchTaken[tid] = inst->readNextPC() !=
486 (inst->readPC() + sizeof(TheISA::MachInst));
487 toCommit->nextPC[tid] = inst->readNextPC();
488#else
489 bool branch_taken = inst->readNextNPC() !=
490 (inst->readNextPC() + sizeof(TheISA::MachInst));
491
492 toCommit->branchTaken[tid] = branch_taken;
493
494 toCommit->condDelaySlotBranch[tid] = inst->isCondDelaySlot();
495
496 if (inst->isCondDelaySlot() && branch_taken) {
497 toCommit->nextPC[tid] = inst->readNextPC();
498 } else {
499 toCommit->nextPC[tid] = inst->readNextNPC();
500 }
501#endif
502
503 toCommit->includeSquashInst[tid] = false;
504
505 wroteToTimeBuffer = true;
506}
507
508template<class Impl>
509void
510DefaultIEW<Impl>::squashDueToMemOrder(DynInstPtr &inst, unsigned tid)
511{
512 DPRINTF(IEW, "[tid:%i]: Squashing from a specific instruction, "
513 "PC: %#x [sn:%i].\n", tid, inst->readPC(), inst->seqNum);
514
515 toCommit->squash[tid] = true;
516 toCommit->squashedSeqNum[tid] = inst->seqNum;
517 toCommit->nextPC[tid] = inst->readNextPC();
518
519 toCommit->includeSquashInst[tid] = false;
520
521 wroteToTimeBuffer = true;
522}
523
524template<class Impl>
525void
526DefaultIEW<Impl>::squashDueToMemBlocked(DynInstPtr &inst, unsigned tid)
527{
528 DPRINTF(IEW, "[tid:%i]: Memory blocked, squashing load and younger insts, "
529 "PC: %#x [sn:%i].\n", tid, inst->readPC(), inst->seqNum);
530
531 toCommit->squash[tid] = true;
532 toCommit->squashedSeqNum[tid] = inst->seqNum;
533 toCommit->nextPC[tid] = inst->readPC();
534
535 // Must include the broadcasted SN in the squash.
536 toCommit->includeSquashInst[tid] = true;
537
538 ldstQueue.setLoadBlockedHandled(tid);
539
540 wroteToTimeBuffer = true;
541}
542
543template<class Impl>
544void
545DefaultIEW<Impl>::block(unsigned tid)
546{
547 DPRINTF(IEW, "[tid:%u]: Blocking.\n", tid);
548
549 if (dispatchStatus[tid] != Blocked &&
550 dispatchStatus[tid] != Unblocking) {
551 toRename->iewBlock[tid] = true;
552 wroteToTimeBuffer = true;
553 }
554
555 // Add the current inputs to the skid buffer so they can be
556 // reprocessed when this stage unblocks.
557 skidInsert(tid);
558
559 dispatchStatus[tid] = Blocked;
560}
561
562template<class Impl>
563void
564DefaultIEW<Impl>::unblock(unsigned tid)
565{
566 DPRINTF(IEW, "[tid:%i]: Reading instructions out of the skid "
567 "buffer %u.\n",tid, tid);
568
569 // If the skid bufffer is empty, signal back to previous stages to unblock.
570 // Also switch status to running.
571 if (skidBuffer[tid].empty()) {
572 toRename->iewUnblock[tid] = true;
573 wroteToTimeBuffer = true;
574 DPRINTF(IEW, "[tid:%i]: Done unblocking.\n",tid);
575 dispatchStatus[tid] = Running;
576 }
577}
578
579template<class Impl>
580void
581DefaultIEW<Impl>::wakeDependents(DynInstPtr &inst)
582{
583 instQueue.wakeDependents(inst);
584}
585
586template<class Impl>
587void
588DefaultIEW<Impl>::rescheduleMemInst(DynInstPtr &inst)
589{
590 instQueue.rescheduleMemInst(inst);
591}
592
593template<class Impl>
594void
595DefaultIEW<Impl>::replayMemInst(DynInstPtr &inst)
596{
597 instQueue.replayMemInst(inst);
598}
599
600template<class Impl>
601void
602DefaultIEW<Impl>::instToCommit(DynInstPtr &inst)
603{
604 // First check the time slot that this instruction will write
605 // to. If there are free write ports at the time, then go ahead
606 // and write the instruction to that time. If there are not,
607 // keep looking back to see where's the first time there's a
608 // free slot.
609 while ((*iewQueue)[wbCycle].insts[wbNumInst]) {
610 ++wbNumInst;
611 if (wbNumInst == wbWidth) {
612 ++wbCycle;
613 wbNumInst = 0;
614 }
615
616 assert((wbCycle * wbWidth + wbNumInst) < wbMax);
617 }
618
619 // Add finished instruction to queue to commit.
620 (*iewQueue)[wbCycle].insts[wbNumInst] = inst;
621 (*iewQueue)[wbCycle].size++;
622}
623
624template <class Impl>
625unsigned
626DefaultIEW<Impl>::validInstsFromRename()
627{
628 unsigned inst_count = 0;
629
630 for (int i=0; i<fromRename->size; i++) {
631 if (!fromRename->insts[i]->isSquashed())
632 inst_count++;
633 }
634
635 return inst_count;
636}
637
638template<class Impl>
639void
640DefaultIEW<Impl>::skidInsert(unsigned tid)
641{
642 DynInstPtr inst = NULL;
643
644 while (!insts[tid].empty()) {
645 inst = insts[tid].front();
646
647 insts[tid].pop();
648
649 DPRINTF(Decode,"[tid:%i]: Inserting [sn:%lli] PC:%#x into "
650 "dispatch skidBuffer %i\n",tid, inst->seqNum,
651 inst->readPC(),tid);
652
653 skidBuffer[tid].push(inst);
654 }
655
656 assert(skidBuffer[tid].size() <= skidBufferMax &&
657 "Skidbuffer Exceeded Max Size");
658}
659
660template<class Impl>
661int
662DefaultIEW<Impl>::skidCount()
663{
664 int max=0;
665
666 list<unsigned>::iterator threads = (*activeThreads).begin();
667
668 while (threads != (*activeThreads).end()) {
669 unsigned thread_count = skidBuffer[*threads++].size();
670 if (max < thread_count)
671 max = thread_count;
672 }
673
674 return max;
675}
676
677template<class Impl>
678bool
679DefaultIEW<Impl>::skidsEmpty()
680{
681 list<unsigned>::iterator threads = (*activeThreads).begin();
682
683 while (threads != (*activeThreads).end()) {
684 if (!skidBuffer[*threads++].empty())
685 return false;
686 }
687
688 return true;
689}
690
691template <class Impl>
692void
693DefaultIEW<Impl>::updateStatus()
694{
695 bool any_unblocking = false;
696
697 list<unsigned>::iterator threads = (*activeThreads).begin();
698
699 threads = (*activeThreads).begin();
700
701 while (threads != (*activeThreads).end()) {
702 unsigned tid = *threads++;
703
704 if (dispatchStatus[tid] == Unblocking) {
705 any_unblocking = true;
706 break;
707 }
708 }
709
710 // If there are no ready instructions waiting to be scheduled by the IQ,
711 // and there's no stores waiting to write back, and dispatch is not
712 // unblocking, then there is no internal activity for the IEW stage.
713 if (_status == Active && !instQueue.hasReadyInsts() &&
714 !ldstQueue.willWB() && !any_unblocking) {
715 DPRINTF(IEW, "IEW switching to idle\n");
716
717 deactivateStage();
718
719 _status = Inactive;
720 } else if (_status == Inactive && (instQueue.hasReadyInsts() ||
721 ldstQueue.willWB() ||
722 any_unblocking)) {
723 // Otherwise there is internal activity. Set to active.
724 DPRINTF(IEW, "IEW switching to active\n");
725
726 activateStage();
727
728 _status = Active;
729 }
730}
731
732template <class Impl>
733void
734DefaultIEW<Impl>::resetEntries()
735{
736 instQueue.resetEntries();
737 ldstQueue.resetEntries();
738}
739
740template <class Impl>
741void
742DefaultIEW<Impl>::readStallSignals(unsigned tid)
743{
744 if (fromCommit->commitBlock[tid]) {
745 stalls[tid].commit = true;
746 }
747
748 if (fromCommit->commitUnblock[tid]) {
749 assert(stalls[tid].commit);
750 stalls[tid].commit = false;
751 }
752}
753
754template <class Impl>
755bool
756DefaultIEW<Impl>::checkStall(unsigned tid)
757{
758 bool ret_val(false);
759
760 if (stalls[tid].commit) {
761 DPRINTF(IEW,"[tid:%i]: Stall from Commit stage detected.\n",tid);
762 ret_val = true;
763 } else if (instQueue.isFull(tid)) {
764 DPRINTF(IEW,"[tid:%i]: Stall: IQ is full.\n",tid);
765 ret_val = true;
766 } else if (ldstQueue.isFull(tid)) {
767 DPRINTF(IEW,"[tid:%i]: Stall: LSQ is full\n",tid);
768
769 if (ldstQueue.numLoads(tid) > 0 ) {
770
771 DPRINTF(IEW,"[tid:%i]: LSQ oldest load: [sn:%i] \n",
772 tid,ldstQueue.getLoadHeadSeqNum(tid));
773 }
774
775 if (ldstQueue.numStores(tid) > 0) {
776
777 DPRINTF(IEW,"[tid:%i]: LSQ oldest store: [sn:%i] \n",
778 tid,ldstQueue.getStoreHeadSeqNum(tid));
779 }
780
781 ret_val = true;
782 } else if (ldstQueue.isStalled(tid)) {
783 DPRINTF(IEW,"[tid:%i]: Stall: LSQ stall detected.\n",tid);
784 ret_val = true;
785 }
786
787 return ret_val;
788}
789
790template <class Impl>
791void
792DefaultIEW<Impl>::checkSignalsAndUpdate(unsigned tid)
793{
794 // Check if there's a squash signal, squash if there is
795 // Check stall signals, block if there is.
796 // If status was Blocked
797 // if so then go to unblocking
798 // If status was Squashing
799 // check if squashing is not high. Switch to running this cycle.
800
801 readStallSignals(tid);
802
803 if (fromCommit->commitInfo[tid].squash) {
804 squash(tid);
805
806 if (dispatchStatus[tid] == Blocked ||
807 dispatchStatus[tid] == Unblocking) {
808 toRename->iewUnblock[tid] = true;
809 wroteToTimeBuffer = true;
810 }
811
812 dispatchStatus[tid] = Squashing;
813
814 fetchRedirect[tid] = false;
815 return;
816 }
817
818 if (fromCommit->commitInfo[tid].robSquashing) {
819 DPRINTF(IEW, "[tid:%i]: ROB is still squashing.\n", tid);
820
821 dispatchStatus[tid] = Squashing;
822
823 emptyRenameInsts(tid);
824 wroteToTimeBuffer = true;
825 return;
826 }
827
828 if (checkStall(tid)) {
829 block(tid);
830 dispatchStatus[tid] = Blocked;
831 return;
832 }
833
834 if (dispatchStatus[tid] == Blocked) {
835 // Status from previous cycle was blocked, but there are no more stall
836 // conditions. Switch over to unblocking.
837 DPRINTF(IEW, "[tid:%i]: Done blocking, switching to unblocking.\n",
838 tid);
839
840 dispatchStatus[tid] = Unblocking;
841
842 unblock(tid);
843
844 return;
845 }
846
847 if (dispatchStatus[tid] == Squashing) {
848 // Switch status to running if rename isn't being told to block or
849 // squash this cycle.
850 DPRINTF(IEW, "[tid:%i]: Done squashing, switching to running.\n",
851 tid);
852
853 dispatchStatus[tid] = Running;
854
855 return;
856 }
857}
858
859template <class Impl>
860void
861DefaultIEW<Impl>::sortInsts()
862{
863 int insts_from_rename = fromRename->size;
864#ifdef DEBUG
865#if THE_ISA == ALPHA_ISA
866 for (int i = 0; i < numThreads; i++)
867 assert(insts[i].empty());
868#endif
869#endif
870 for (int i = 0; i < insts_from_rename; ++i) {
871 insts[fromRename->insts[i]->threadNumber].push(fromRename->insts[i]);
872 }
873}
874
875template <class Impl>
876void
877DefaultIEW<Impl>::emptyRenameInsts(unsigned tid)
878{
879 DPRINTF(IEW, "[tid:%i]: Removing incoming rename instructions until "
880 "[sn:%i].\n", tid, bdelayDoneSeqNum[tid]);
881
882 while (!insts[tid].empty()) {
883
884#if THE_ISA != ALPHA_ISA
885 if (insts[tid].front()->seqNum <= bdelayDoneSeqNum[tid]) {
886 DPRINTF(IEW, "[tid:%i]: Done removing, cannot remove instruction"
887 " that occurs at or before delay slot [sn:%i].\n",
888 tid, bdelayDoneSeqNum[tid]);
889 break;
890 } else {
891 DPRINTF(IEW, "[tid:%i]: Removing incoming rename instruction "
892 "[sn:%i].\n", tid, insts[tid].front()->seqNum);
893 }
894#endif
895
896 if (insts[tid].front()->isLoad() ||
897 insts[tid].front()->isStore() ) {
898 toRename->iewInfo[tid].dispatchedToLSQ++;
899 }
900
901 toRename->iewInfo[tid].dispatched++;
902
903 insts[tid].pop();
904 }
905}
906
907template <class Impl>
908void
909DefaultIEW<Impl>::wakeCPU()
910{
911 cpu->wakeCPU();
912}
913
914template <class Impl>
915void
916DefaultIEW<Impl>::activityThisCycle()
917{
918 DPRINTF(Activity, "Activity this cycle.\n");
919 cpu->activityThisCycle();
920}
921
922template <class Impl>
923inline void
924DefaultIEW<Impl>::activateStage()
925{
926 DPRINTF(Activity, "Activating stage.\n");
927 cpu->activateStage(O3CPU::IEWIdx);
928}
929
930template <class Impl>
931inline void
932DefaultIEW<Impl>::deactivateStage()
933{
934 DPRINTF(Activity, "Deactivating stage.\n");
935 cpu->deactivateStage(O3CPU::IEWIdx);
936}
937
938template<class Impl>
939void
940DefaultIEW<Impl>::dispatch(unsigned tid)
941{
942 // If status is Running or idle,
943 // call dispatchInsts()
944 // If status is Unblocking,
945 // buffer any instructions coming from rename
946 // continue trying to empty skid buffer
947 // check if stall conditions have passed
948
949 if (dispatchStatus[tid] == Blocked) {
950 ++iewBlockCycles;
951
952 } else if (dispatchStatus[tid] == Squashing) {
953 ++iewSquashCycles;
954 }
955
956 // Dispatch should try to dispatch as many instructions as its bandwidth
957 // will allow, as long as it is not currently blocked.
958 if (dispatchStatus[tid] == Running ||
959 dispatchStatus[tid] == Idle) {
960 DPRINTF(IEW, "[tid:%i] Not blocked, so attempting to run "
961 "dispatch.\n", tid);
962
963 dispatchInsts(tid);
964 } else if (dispatchStatus[tid] == Unblocking) {
965 // Make sure that the skid buffer has something in it if the
966 // status is unblocking.
967 assert(!skidsEmpty());
968
969 // If the status was unblocking, then instructions from the skid
970 // buffer were used. Remove those instructions and handle
971 // the rest of unblocking.
972 dispatchInsts(tid);
973
974 ++iewUnblockCycles;
975
976 if (validInstsFromRename() && dispatchedAllInsts) {
977 // Add the current inputs to the skid buffer so they can be
978 // reprocessed when this stage unblocks.
979 skidInsert(tid);
980 }
981
982 unblock(tid);
983 }
984}
985
986template <class Impl>
987void
988DefaultIEW<Impl>::dispatchInsts(unsigned tid)
989{
990 dispatchedAllInsts = true;
991
992 // Obtain instructions from skid buffer if unblocking, or queue from rename
993 // otherwise.
994 std::queue<DynInstPtr> &insts_to_dispatch =
995 dispatchStatus[tid] == Unblocking ?
996 skidBuffer[tid] : insts[tid];
997
998 int insts_to_add = insts_to_dispatch.size();
999
1000 DynInstPtr inst;
1001 bool add_to_iq = false;
1002 int dis_num_inst = 0;
1003
1004 // Loop through the instructions, putting them in the instruction
1005 // queue.
1006 for ( ; dis_num_inst < insts_to_add &&
1007 dis_num_inst < dispatchWidth;
1008 ++dis_num_inst)
1009 {
1010 inst = insts_to_dispatch.front();
1011
1012 if (dispatchStatus[tid] == Unblocking) {
1013 DPRINTF(IEW, "[tid:%i]: Issue: Examining instruction from skid "
1014 "buffer\n", tid);
1015 }
1016
1017 // Make sure there's a valid instruction there.
1018 assert(inst);
1019
1020 DPRINTF(IEW, "[tid:%i]: Issue: Adding PC %#x [sn:%lli] [tid:%i] to "
1021 "IQ.\n",
1022 tid, inst->readPC(), inst->seqNum, inst->threadNumber);
1023
1024 // Be sure to mark these instructions as ready so that the
1025 // commit stage can go ahead and execute them, and mark
1026 // them as issued so the IQ doesn't reprocess them.
1027
1028 // Check for squashed instructions.
1029 if (inst->isSquashed()) {
1030 DPRINTF(IEW, "[tid:%i]: Issue: Squashed instruction encountered, "
1031 "not adding to IQ.\n", tid);
1032
1033 ++iewDispSquashedInsts;
1034
1035 insts_to_dispatch.pop();
1036
1037 //Tell Rename That An Instruction has been processed
1038 if (inst->isLoad() || inst->isStore()) {
1039 toRename->iewInfo[tid].dispatchedToLSQ++;
1040 }
1041 toRename->iewInfo[tid].dispatched++;
1042
1043 continue;
1044 }
1045
1046 // Check for full conditions.
1047 if (instQueue.isFull(tid)) {
1048 DPRINTF(IEW, "[tid:%i]: Issue: IQ has become full.\n", tid);
1049
1050 // Call function to start blocking.
1051 block(tid);
1052
1053 // Set unblock to false. Special case where we are using
1054 // skidbuffer (unblocking) instructions but then we still
1055 // get full in the IQ.
1056 toRename->iewUnblock[tid] = false;
1057
1058 dispatchedAllInsts = false;
1059
1060 ++iewIQFullEvents;
1061 break;
1062 } else if (ldstQueue.isFull(tid)) {
1063 DPRINTF(IEW, "[tid:%i]: Issue: LSQ has become full.\n",tid);
1064
1065 // Call function to start blocking.
1066 block(tid);
1067
1068 // Set unblock to false. Special case where we are using
1069 // skidbuffer (unblocking) instructions but then we still
1070 // get full in the IQ.
1071 toRename->iewUnblock[tid] = false;
1072
1073 dispatchedAllInsts = false;
1074
1075 ++iewLSQFullEvents;
1076 break;
1077 }
1078
1079 // Otherwise issue the instruction just fine.
1080 if (inst->isLoad()) {
1081 DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1082 "encountered, adding to LSQ.\n", tid);
1083
1084 // Reserve a spot in the load store queue for this
1085 // memory access.
1086 ldstQueue.insertLoad(inst);
1087
1088 ++iewDispLoadInsts;
1089
1090 add_to_iq = true;
1091
1092 toRename->iewInfo[tid].dispatchedToLSQ++;
1093 } else if (inst->isStore()) {
1094 DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1095 "encountered, adding to LSQ.\n", tid);
1096
1097 ldstQueue.insertStore(inst);
1098
1099 ++iewDispStoreInsts;
1100
1101 if (inst->isStoreConditional()) {
1102 // Store conditionals need to be set as "canCommit()"
1103 // so that commit can process them when they reach the
1104 // head of commit.
1105 // @todo: This is somewhat specific to Alpha.
1106 inst->setCanCommit();
1107 instQueue.insertNonSpec(inst);
1108 add_to_iq = false;
1109
1110 ++iewDispNonSpecInsts;
1111 } else {
1112 add_to_iq = true;
1113 }
1114
1115 toRename->iewInfo[tid].dispatchedToLSQ++;
1116#if FULL_SYSTEM
1117 } else if (inst->isMemBarrier() || inst->isWriteBarrier()) {
1118 // Same as non-speculative stores.
1119 inst->setCanCommit();
1120 instQueue.insertBarrier(inst);
1121 add_to_iq = false;
1122#endif
1123 } else if (inst->isNonSpeculative()) {
1124 DPRINTF(IEW, "[tid:%i]: Issue: Nonspeculative instruction "
1125 "encountered, skipping.\n", tid);
1126
1127 // Same as non-speculative stores.
1128 inst->setCanCommit();
1129
1130 // Specifically insert it as nonspeculative.
1131 instQueue.insertNonSpec(inst);
1132
1133 ++iewDispNonSpecInsts;
1134
1135 add_to_iq = false;
1136 } else if (inst->isNop()) {
1137 DPRINTF(IEW, "[tid:%i]: Issue: Nop instruction encountered, "
1138 "skipping.\n", tid);
1139
1140 inst->setIssued();
1141 inst->setExecuted();
1142 inst->setCanCommit();
1143
1144 instQueue.recordProducer(inst);
1145
1146 iewExecutedNop[tid]++;
1147
1148 add_to_iq = false;
1149 } else if (inst->isExecuted()) {
1150 assert(0 && "Instruction shouldn't be executed.\n");
1151 DPRINTF(IEW, "Issue: Executed branch encountered, "
1152 "skipping.\n");
1153
1154 inst->setIssued();
1155 inst->setCanCommit();
1156
1157 instQueue.recordProducer(inst);
1158
1159 add_to_iq = false;
1160 } else {
1161 add_to_iq = true;
1162 }
1163
1164 // If the instruction queue is not full, then add the
1165 // instruction.
1166 if (add_to_iq) {
1167 instQueue.insert(inst);
1168 }
1169
1170 insts_to_dispatch.pop();
1171
1172 toRename->iewInfo[tid].dispatched++;
1173
1174 ++iewDispatchedInsts;
1175 }
1176
1177 if (!insts_to_dispatch.empty()) {
1178 DPRINTF(IEW,"[tid:%i]: Issue: Bandwidth Full. Blocking.\n", tid);
1179 block(tid);
1180 toRename->iewUnblock[tid] = false;
1181 }
1182
1183 if (dispatchStatus[tid] == Idle && dis_num_inst) {
1184 dispatchStatus[tid] = Running;
1185
1186 updatedQueues = true;
1187 }
1188
1189 dis_num_inst = 0;
1190}
1191
1192template <class Impl>
1193void
1194DefaultIEW<Impl>::printAvailableInsts()
1195{
1196 int inst = 0;
1197
1198 cout << "Available Instructions: ";
1199
1200 while (fromIssue->insts[inst]) {
1201
1202 if (inst%3==0) cout << "\n\t";
1203
1204 cout << "PC: " << fromIssue->insts[inst]->readPC()
1205 << " TN: " << fromIssue->insts[inst]->threadNumber
1206 << " SN: " << fromIssue->insts[inst]->seqNum << " | ";
1207
1208 inst++;
1209
1210 }
1211
1212 cout << "\n";
1213}
1214
1215template <class Impl>
1216void
1217DefaultIEW<Impl>::executeInsts()
1218{
1219 wbNumInst = 0;
1220 wbCycle = 0;
1221
1222 list<unsigned>::iterator threads = (*activeThreads).begin();
1223
1224 while (threads != (*activeThreads).end()) {
1225 unsigned tid = *threads++;
1226 fetchRedirect[tid] = false;
1227 }
1228
1229 // Uncomment this if you want to see all available instructions.
1230// printAvailableInsts();
1231
1232 // Execute/writeback any instructions that are available.
1233 int insts_to_execute = fromIssue->size;
1234 int inst_num = 0;
1235 for (; inst_num < insts_to_execute;
1236 ++inst_num) {
1237
1238 DPRINTF(IEW, "Execute: Executing instructions from IQ.\n");
1239
1240 DynInstPtr inst = instQueue.getInstToExecute();
1241
1242 DPRINTF(IEW, "Execute: Processing PC %#x, [tid:%i] [sn:%i].\n",
1243 inst->readPC(), inst->threadNumber,inst->seqNum);
1244
1245 // Check if the instruction is squashed; if so then skip it
1246 if (inst->isSquashed()) {
1247 DPRINTF(IEW, "Execute: Instruction was squashed.\n");
1248
1249 // Consider this instruction executed so that commit can go
1250 // ahead and retire the instruction.
1251 inst->setExecuted();
1252
1253 // Not sure if I should set this here or just let commit try to
1254 // commit any squashed instructions. I like the latter a bit more.
1255 inst->setCanCommit();
1256
1257 ++iewExecSquashedInsts;
1258
1259 decrWb(inst->seqNum);
1260 continue;
1261 }
1262
1263 Fault fault = NoFault;
1264
1265 // Execute instruction.
1266 // Note that if the instruction faults, it will be handled
1267 // at the commit stage.
1268 if (inst->isMemRef() &&
1269 (!inst->isDataPrefetch() && !inst->isInstPrefetch())) {
1270 DPRINTF(IEW, "Execute: Calculating address for memory "
1271 "reference.\n");
1272
1273 // Tell the LDSTQ to execute this instruction (if it is a load).
1274 if (inst->isLoad()) {
1275 // Loads will mark themselves as executed, and their writeback
1276 // event adds the instruction to the queue to commit
1277 fault = ldstQueue.executeLoad(inst);
1278 } else if (inst->isStore()) {
1279 ldstQueue.executeStore(inst);
1280
1281 // If the store had a fault then it may not have a mem req
1282 if (inst->req && !(inst->req->getFlags() & LOCKED)) {
1283 inst->setExecuted();
1284
1285 instToCommit(inst);
1286 }
1287
1288 // Store conditionals will mark themselves as
1289 // executed, and their writeback event will add the
1290 // instruction to the queue to commit.
1291 } else {
1292 panic("Unexpected memory type!\n");
1293 }
1294
1295 } else {
1296 inst->execute();
1297
1298 inst->setExecuted();
1299
1300 instToCommit(inst);
1301 }
1302
1303 updateExeInstStats(inst);
1304
1305 // Check if branch prediction was correct, if not then we need
1306 // to tell commit to squash in flight instructions. Only
1307 // handle this if there hasn't already been something that
1308 // redirects fetch in this group of instructions.
1309
1310 // This probably needs to prioritize the redirects if a different
1311 // scheduler is used. Currently the scheduler schedules the oldest
1312 // instruction first, so the branch resolution order will be correct.
1313 unsigned tid = inst->threadNumber;
1314
1315 if (!fetchRedirect[tid]) {
1316
1317 if (inst->mispredicted()) {
1318 fetchRedirect[tid] = true;
1319
1320 DPRINTF(IEW, "Execute: Branch mispredict detected.\n");
1321#if THE_ISA == ALPHA_ISA
1322 DPRINTF(IEW, "Execute: Redirecting fetch to PC: %#x.\n",
1323 inst->nextPC);
1324#else
1325 DPRINTF(IEW, "Execute: Redirecting fetch to PC: %#x.\n",
1326 inst->nextNPC);
1327#endif
1328 // If incorrect, then signal the ROB that it must be squashed.
1329 squashDueToBranch(inst, tid);
1330
1331 if (inst->predTaken()) {
1332 predictedTakenIncorrect++;
1333 } else {
1334 predictedNotTakenIncorrect++;
1335 }
1336 } else if (ldstQueue.violation(tid)) {
1337 fetchRedirect[tid] = true;
1338
1339 // If there was an ordering violation, then get the
1340 // DynInst that caused the violation. Note that this
1341 // clears the violation signal.
1342 DynInstPtr violator;
1343 violator = ldstQueue.getMemDepViolator(tid);
1344
1345 DPRINTF(IEW, "LDSTQ detected a violation. Violator PC: "
1346 "%#x, inst PC: %#x. Addr is: %#x.\n",
1347 violator->readPC(), inst->readPC(), inst->physEffAddr);
1348
1349 // Tell the instruction queue that a violation has occured.
1350 instQueue.violation(inst, violator);
1351
1352 // Squash.
1353 squashDueToMemOrder(inst,tid);
1354
1355 ++memOrderViolationEvents;
1356 } else if (ldstQueue.loadBlocked(tid) &&
1357 !ldstQueue.isLoadBlockedHandled(tid)) {
1358 fetchRedirect[tid] = true;
1359
1360 DPRINTF(IEW, "Load operation couldn't execute because the "
1361 "memory system is blocked. PC: %#x [sn:%lli]\n",
1362 inst->readPC(), inst->seqNum);
1363
1364 squashDueToMemBlocked(inst, tid);
1365 }
1366 }
1367 }
1368
1369 // Update and record activity if we processed any instructions.
1370 if (inst_num) {
1371 if (exeStatus == Idle) {
1372 exeStatus = Running;
1373 }
1374
1375 updatedQueues = true;
1376
1377 cpu->activityThisCycle();
1378 }
1379
1380 // Need to reset this in case a writeback event needs to write into the
1381 // iew queue. That way the writeback event will write into the correct
1382 // spot in the queue.
1383 wbNumInst = 0;
1384}
1385
1386template <class Impl>
1387void
1388DefaultIEW<Impl>::writebackInsts()
1389{
1390 // Loop through the head of the time buffer and wake any
1391 // dependents. These instructions are about to write back. Also
1392 // mark scoreboard that this instruction is finally complete.
1393 // Either have IEW have direct access to scoreboard, or have this
1394 // as part of backwards communication.
1395 for (int inst_num = 0; inst_num < issueWidth &&
1396 toCommit->insts[inst_num]; inst_num++) {
1397 DynInstPtr inst = toCommit->insts[inst_num];
1398 int tid = inst->threadNumber;
1399
1400 DPRINTF(IEW, "Sending instructions to commit, [sn:%lli] PC %#x.\n",
1401 inst->seqNum, inst->readPC());
1402
1403 iewInstsToCommit[tid]++;
1404
1405 // Some instructions will be sent to commit without having
1406 // executed because they need commit to handle them.
1407 // E.g. Uncached loads have not actually executed when they
1408 // are first sent to commit. Instead commit must tell the LSQ
1409 // when it's ready to execute the uncached load.
1410 if (!inst->isSquashed() && inst->isExecuted()) {
1411 int dependents = instQueue.wakeDependents(inst);
1412
1413 for (int i = 0; i < inst->numDestRegs(); i++) {
1414 //mark as Ready
1415 DPRINTF(IEW,"Setting Destination Register %i\n",
1416 inst->renamedDestRegIdx(i));
1417 scoreboard->setReg(inst->renamedDestRegIdx(i));
1418 }
1419
1420 if (dependents) {
1421 producerInst[tid]++;
1422 consumerInst[tid]+= dependents;
1423 }
1424 writebackCount[tid]++;
1425 }
1426
1427 decrWb(inst->seqNum);
1428 }
1429}
1430
1431template<class Impl>
1432void
1433DefaultIEW<Impl>::tick()
1434{
1435 wbNumInst = 0;
1436 wbCycle = 0;
1437
1438 wroteToTimeBuffer = false;
1439 updatedQueues = false;
1440
1441 sortInsts();
1442
1443 // Free function units marked as being freed this cycle.
1444 fuPool->processFreeUnits();
1445
1446 list<unsigned>::iterator threads = (*activeThreads).begin();
1447
1448 // Check stall and squash signals, dispatch any instructions.
1449 while (threads != (*activeThreads).end()) {
1450 unsigned tid = *threads++;
1451
1452 DPRINTF(IEW,"Issue: Processing [tid:%i]\n",tid);
1453
1454 checkSignalsAndUpdate(tid);
1455 dispatch(tid);
1456 }
1457
1458 if (exeStatus != Squashing) {
1459 executeInsts();
1460
1461 writebackInsts();
1462
1463 // Have the instruction queue try to schedule any ready instructions.
1464 // (In actuality, this scheduling is for instructions that will
1465 // be executed next cycle.)
1466 instQueue.scheduleReadyInsts();
1467
1468 // Also should advance its own time buffers if the stage ran.
1469 // Not the best place for it, but this works (hopefully).
1470 issueToExecQueue.advance();
1471 }
1472
1473 bool broadcast_free_entries = false;
1474
1475 if (updatedQueues || exeStatus == Running || updateLSQNextCycle) {
1476 exeStatus = Idle;
1477 updateLSQNextCycle = false;
1478
1479 broadcast_free_entries = true;
1480 }
1481
1482 // Writeback any stores using any leftover bandwidth.
1483 ldstQueue.writebackStores();
1484
1485 // Check the committed load/store signals to see if there's a load
1486 // or store to commit. Also check if it's being told to execute a
1487 // nonspeculative instruction.
1488 // This is pretty inefficient...
1489
1490 threads = (*activeThreads).begin();
1491 while (threads != (*activeThreads).end()) {
1492 unsigned tid = (*threads++);
1493
1494 DPRINTF(IEW,"Processing [tid:%i]\n",tid);
1495
1496 // Update structures based on instructions committed.
1497 if (fromCommit->commitInfo[tid].doneSeqNum != 0 &&
1498 !fromCommit->commitInfo[tid].squash &&
1499 !fromCommit->commitInfo[tid].robSquashing) {
1500
1501 ldstQueue.commitStores(fromCommit->commitInfo[tid].doneSeqNum,tid);
1502
1503 ldstQueue.commitLoads(fromCommit->commitInfo[tid].doneSeqNum,tid);
1504
1505 updateLSQNextCycle = true;
1506 instQueue.commit(fromCommit->commitInfo[tid].doneSeqNum,tid);
1507 }
1508
1509 if (fromCommit->commitInfo[tid].nonSpecSeqNum != 0) {
1510
1511 //DPRINTF(IEW,"NonspecInst from thread %i",tid);
1512 if (fromCommit->commitInfo[tid].uncached) {
1513 instQueue.replayMemInst(fromCommit->commitInfo[tid].uncachedLoad);
1514 } else {
1515 instQueue.scheduleNonSpec(
1516 fromCommit->commitInfo[tid].nonSpecSeqNum);
1517 }
1518 }
1519
1520 if (broadcast_free_entries) {
1521 toFetch->iewInfo[tid].iqCount =
1522 instQueue.getCount(tid);
1523 toFetch->iewInfo[tid].ldstqCount =
1524 ldstQueue.getCount(tid);
1525
1526 toRename->iewInfo[tid].usedIQ = true;
1527 toRename->iewInfo[tid].freeIQEntries =
1528 instQueue.numFreeEntries();
1529 toRename->iewInfo[tid].usedLSQ = true;
1530 toRename->iewInfo[tid].freeLSQEntries =
1531 ldstQueue.numFreeEntries(tid);
1532
1533 wroteToTimeBuffer = true;
1534 }
1535
1536 DPRINTF(IEW, "[tid:%i], Dispatch dispatched %i instructions.\n",
1537 tid, toRename->iewInfo[tid].dispatched);
1538 }
1539
1540 DPRINTF(IEW, "IQ has %i free entries (Can schedule: %i). "
1541 "LSQ has %i free entries.\n",
1542 instQueue.numFreeEntries(), instQueue.hasReadyInsts(),
1543 ldstQueue.numFreeEntries());
1544
1545 updateStatus();
1546
1547 if (wroteToTimeBuffer) {
1548 DPRINTF(Activity, "Activity this cycle.\n");
1549 cpu->activityThisCycle();
1550 }
1551}
1552
1553template <class Impl>
1554void
1555DefaultIEW<Impl>::updateExeInstStats(DynInstPtr &inst)
1556{
1557 int thread_number = inst->threadNumber;
1558
1559 //
1560 // Pick off the software prefetches
1561 //
1562#ifdef TARGET_ALPHA
1563 if (inst->isDataPrefetch())
1564 iewExecutedSwp[thread_number]++;
1565 else
1566 iewIewExecutedcutedInsts++;
1567#else
1568 iewExecutedInsts++;
1569#endif
1570
1571 //
1572 // Control operations
1573 //
1574 if (inst->isControl())
1575 iewExecutedBranches[thread_number]++;
1576
1577 //
1578 // Memory operations
1579 //
1580 if (inst->isMemRef()) {
1581 iewExecutedRefs[thread_number]++;
1582
1583 if (inst->isLoad()) {
1584 iewExecLoadInsts[thread_number]++;
1585 }
1586 }
1587}
2 * Copyright (c) 2004-2006 The Regents of The University of Michigan
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * Authors: Kevin Lim
29 */
30
31// @todo: Fix the instantaneous communication among all the stages within
32// iew. There's a clear delay between issue and execute, yet backwards
33// communication happens simultaneously.
34
35#include <queue>
36
37#include "base/timebuf.hh"
38#include "cpu/o3/fu_pool.hh"
39#include "cpu/o3/iew.hh"
40
41using namespace std;
42
43template<class Impl>
44DefaultIEW<Impl>::DefaultIEW(Params *params)
45 : issueToExecQueue(params->backComSize, params->forwardComSize),
46 instQueue(params),
47 ldstQueue(params),
48 fuPool(params->fuPool),
49 commitToIEWDelay(params->commitToIEWDelay),
50 renameToIEWDelay(params->renameToIEWDelay),
51 issueToExecuteDelay(params->issueToExecuteDelay),
52 dispatchWidth(params->dispatchWidth),
53 issueWidth(params->issueWidth),
54 wbOutstanding(0),
55 wbWidth(params->wbWidth),
56 numThreads(params->numberOfThreads),
57 switchedOut(false)
58{
59 _status = Active;
60 exeStatus = Running;
61 wbStatus = Idle;
62
63 // Setup wire to read instructions coming from issue.
64 fromIssue = issueToExecQueue.getWire(-issueToExecuteDelay);
65
66 // Instruction queue needs the queue between issue and execute.
67 instQueue.setIssueToExecuteQueue(&issueToExecQueue);
68
69 instQueue.setIEW(this);
70 ldstQueue.setIEW(this);
71
72 for (int i=0; i < numThreads; i++) {
73 dispatchStatus[i] = Running;
74 stalls[i].commit = false;
75 fetchRedirect[i] = false;
76 bdelayDoneSeqNum[i] = 0;
77 }
78
79 wbMax = wbWidth * params->wbDepth;
80
81 updateLSQNextCycle = false;
82
83 ableToIssue = true;
84
85 skidBufferMax = (3 * (renameToIEWDelay * params->renameWidth)) + issueWidth;
86}
87
88template <class Impl>
89std::string
90DefaultIEW<Impl>::name() const
91{
92 return cpu->name() + ".iew";
93}
94
95template <class Impl>
96void
97DefaultIEW<Impl>::regStats()
98{
99 using namespace Stats;
100
101 instQueue.regStats();
102 ldstQueue.regStats();
103
104 iewIdleCycles
105 .name(name() + ".iewIdleCycles")
106 .desc("Number of cycles IEW is idle");
107
108 iewSquashCycles
109 .name(name() + ".iewSquashCycles")
110 .desc("Number of cycles IEW is squashing");
111
112 iewBlockCycles
113 .name(name() + ".iewBlockCycles")
114 .desc("Number of cycles IEW is blocking");
115
116 iewUnblockCycles
117 .name(name() + ".iewUnblockCycles")
118 .desc("Number of cycles IEW is unblocking");
119
120 iewDispatchedInsts
121 .name(name() + ".iewDispatchedInsts")
122 .desc("Number of instructions dispatched to IQ");
123
124 iewDispSquashedInsts
125 .name(name() + ".iewDispSquashedInsts")
126 .desc("Number of squashed instructions skipped by dispatch");
127
128 iewDispLoadInsts
129 .name(name() + ".iewDispLoadInsts")
130 .desc("Number of dispatched load instructions");
131
132 iewDispStoreInsts
133 .name(name() + ".iewDispStoreInsts")
134 .desc("Number of dispatched store instructions");
135
136 iewDispNonSpecInsts
137 .name(name() + ".iewDispNonSpecInsts")
138 .desc("Number of dispatched non-speculative instructions");
139
140 iewIQFullEvents
141 .name(name() + ".iewIQFullEvents")
142 .desc("Number of times the IQ has become full, causing a stall");
143
144 iewLSQFullEvents
145 .name(name() + ".iewLSQFullEvents")
146 .desc("Number of times the LSQ has become full, causing a stall");
147
148 memOrderViolationEvents
149 .name(name() + ".memOrderViolationEvents")
150 .desc("Number of memory order violations");
151
152 predictedTakenIncorrect
153 .name(name() + ".predictedTakenIncorrect")
154 .desc("Number of branches that were predicted taken incorrectly");
155
156 predictedNotTakenIncorrect
157 .name(name() + ".predictedNotTakenIncorrect")
158 .desc("Number of branches that were predicted not taken incorrectly");
159
160 branchMispredicts
161 .name(name() + ".branchMispredicts")
162 .desc("Number of branch mispredicts detected at execute");
163
164 branchMispredicts = predictedTakenIncorrect + predictedNotTakenIncorrect;
165
166 iewExecutedInsts
167 .name(name() + ".EXEC:insts")
168 .desc("Number of executed instructions");
169
170 iewExecLoadInsts
171 .init(cpu->number_of_threads)
172 .name(name() + ".EXEC:loads")
173 .desc("Number of load instructions executed")
174 .flags(total);
175
176 iewExecSquashedInsts
177 .name(name() + ".EXEC:squashedInsts")
178 .desc("Number of squashed instructions skipped in execute");
179
180 iewExecutedSwp
181 .init(cpu->number_of_threads)
182 .name(name() + ".EXEC:swp")
183 .desc("number of swp insts executed")
184 .flags(total);
185
186 iewExecutedNop
187 .init(cpu->number_of_threads)
188 .name(name() + ".EXEC:nop")
189 .desc("number of nop insts executed")
190 .flags(total);
191
192 iewExecutedRefs
193 .init(cpu->number_of_threads)
194 .name(name() + ".EXEC:refs")
195 .desc("number of memory reference insts executed")
196 .flags(total);
197
198 iewExecutedBranches
199 .init(cpu->number_of_threads)
200 .name(name() + ".EXEC:branches")
201 .desc("Number of branches executed")
202 .flags(total);
203
204 iewExecStoreInsts
205 .name(name() + ".EXEC:stores")
206 .desc("Number of stores executed")
207 .flags(total);
208 iewExecStoreInsts = iewExecutedRefs - iewExecLoadInsts;
209
210 iewExecRate
211 .name(name() + ".EXEC:rate")
212 .desc("Inst execution rate")
213 .flags(total);
214
215 iewExecRate = iewExecutedInsts / cpu->numCycles;
216
217 iewInstsToCommit
218 .init(cpu->number_of_threads)
219 .name(name() + ".WB:sent")
220 .desc("cumulative count of insts sent to commit")
221 .flags(total);
222
223 writebackCount
224 .init(cpu->number_of_threads)
225 .name(name() + ".WB:count")
226 .desc("cumulative count of insts written-back")
227 .flags(total);
228
229 producerInst
230 .init(cpu->number_of_threads)
231 .name(name() + ".WB:producers")
232 .desc("num instructions producing a value")
233 .flags(total);
234
235 consumerInst
236 .init(cpu->number_of_threads)
237 .name(name() + ".WB:consumers")
238 .desc("num instructions consuming a value")
239 .flags(total);
240
241 wbPenalized
242 .init(cpu->number_of_threads)
243 .name(name() + ".WB:penalized")
244 .desc("number of instrctions required to write to 'other' IQ")
245 .flags(total);
246
247 wbPenalizedRate
248 .name(name() + ".WB:penalized_rate")
249 .desc ("fraction of instructions written-back that wrote to 'other' IQ")
250 .flags(total);
251
252 wbPenalizedRate = wbPenalized / writebackCount;
253
254 wbFanout
255 .name(name() + ".WB:fanout")
256 .desc("average fanout of values written-back")
257 .flags(total);
258
259 wbFanout = producerInst / consumerInst;
260
261 wbRate
262 .name(name() + ".WB:rate")
263 .desc("insts written-back per cycle")
264 .flags(total);
265 wbRate = writebackCount / cpu->numCycles;
266}
267
268template<class Impl>
269void
270DefaultIEW<Impl>::initStage()
271{
272 for (int tid=0; tid < numThreads; tid++) {
273 toRename->iewInfo[tid].usedIQ = true;
274 toRename->iewInfo[tid].freeIQEntries =
275 instQueue.numFreeEntries(tid);
276
277 toRename->iewInfo[tid].usedLSQ = true;
278 toRename->iewInfo[tid].freeLSQEntries =
279 ldstQueue.numFreeEntries(tid);
280 }
281}
282
283template<class Impl>
284void
285DefaultIEW<Impl>::setCPU(O3CPU *cpu_ptr)
286{
287 DPRINTF(IEW, "Setting CPU pointer.\n");
288 cpu = cpu_ptr;
289
290 instQueue.setCPU(cpu_ptr);
291 ldstQueue.setCPU(cpu_ptr);
292
293 cpu->activateStage(O3CPU::IEWIdx);
294}
295
296template<class Impl>
297void
298DefaultIEW<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr)
299{
300 DPRINTF(IEW, "Setting time buffer pointer.\n");
301 timeBuffer = tb_ptr;
302
303 // Setup wire to read information from time buffer, from commit.
304 fromCommit = timeBuffer->getWire(-commitToIEWDelay);
305
306 // Setup wire to write information back to previous stages.
307 toRename = timeBuffer->getWire(0);
308
309 toFetch = timeBuffer->getWire(0);
310
311 // Instruction queue also needs main time buffer.
312 instQueue.setTimeBuffer(tb_ptr);
313}
314
315template<class Impl>
316void
317DefaultIEW<Impl>::setRenameQueue(TimeBuffer<RenameStruct> *rq_ptr)
318{
319 DPRINTF(IEW, "Setting rename queue pointer.\n");
320 renameQueue = rq_ptr;
321
322 // Setup wire to read information from rename queue.
323 fromRename = renameQueue->getWire(-renameToIEWDelay);
324}
325
326template<class Impl>
327void
328DefaultIEW<Impl>::setIEWQueue(TimeBuffer<IEWStruct> *iq_ptr)
329{
330 DPRINTF(IEW, "Setting IEW queue pointer.\n");
331 iewQueue = iq_ptr;
332
333 // Setup wire to write instructions to commit.
334 toCommit = iewQueue->getWire(0);
335}
336
337template<class Impl>
338void
339DefaultIEW<Impl>::setActiveThreads(list<unsigned> *at_ptr)
340{
341 DPRINTF(IEW, "Setting active threads list pointer.\n");
342 activeThreads = at_ptr;
343
344 ldstQueue.setActiveThreads(at_ptr);
345 instQueue.setActiveThreads(at_ptr);
346}
347
348template<class Impl>
349void
350DefaultIEW<Impl>::setScoreboard(Scoreboard *sb_ptr)
351{
352 DPRINTF(IEW, "Setting scoreboard pointer.\n");
353 scoreboard = sb_ptr;
354}
355
356template <class Impl>
357bool
358DefaultIEW<Impl>::drain()
359{
360 // IEW is ready to drain at any time.
361 cpu->signalDrained();
362 return true;
363}
364
365template <class Impl>
366void
367DefaultIEW<Impl>::resume()
368{
369}
370
371template <class Impl>
372void
373DefaultIEW<Impl>::switchOut()
374{
375 // Clear any state.
376 switchedOut = true;
377
378 instQueue.switchOut();
379 ldstQueue.switchOut();
380 fuPool->switchOut();
381
382 for (int i = 0; i < numThreads; i++) {
383 while (!insts[i].empty())
384 insts[i].pop();
385 while (!skidBuffer[i].empty())
386 skidBuffer[i].pop();
387 }
388}
389
390template <class Impl>
391void
392DefaultIEW<Impl>::takeOverFrom()
393{
394 // Reset all state.
395 _status = Active;
396 exeStatus = Running;
397 wbStatus = Idle;
398 switchedOut = false;
399
400 instQueue.takeOverFrom();
401 ldstQueue.takeOverFrom();
402 fuPool->takeOverFrom();
403
404 initStage();
405 cpu->activityThisCycle();
406
407 for (int i=0; i < numThreads; i++) {
408 dispatchStatus[i] = Running;
409 stalls[i].commit = false;
410 fetchRedirect[i] = false;
411 }
412
413 updateLSQNextCycle = false;
414
415 // @todo: Fix hardcoded number
416 for (int i = 0; i < issueToExecQueue.getSize(); ++i) {
417 issueToExecQueue.advance();
418 }
419}
420
421template<class Impl>
422void
423DefaultIEW<Impl>::squash(unsigned tid)
424{
425 DPRINTF(IEW, "[tid:%i]: Squashing all instructions.\n",
426 tid);
427
428 // Tell the IQ to start squashing.
429 instQueue.squash(tid);
430
431 // Tell the LDSTQ to start squashing.
432#if THE_ISA == ALPHA_ISA
433 ldstQueue.squash(fromCommit->commitInfo[tid].doneSeqNum, tid);
434#else
435 ldstQueue.squash(fromCommit->commitInfo[tid].bdelayDoneSeqNum, tid);
436#endif
437 updatedQueues = true;
438
439 // Clear the skid buffer in case it has any data in it.
440 DPRINTF(IEW, "[tid:%i]: Removing skidbuffer instructions until [sn:%i].\n",
441 tid, fromCommit->commitInfo[tid].bdelayDoneSeqNum);
442
443 while (!skidBuffer[tid].empty()) {
444#if THE_ISA != ALPHA_ISA
445 if (skidBuffer[tid].front()->seqNum <=
446 fromCommit->commitInfo[tid].bdelayDoneSeqNum) {
447 DPRINTF(IEW, "[tid:%i]: Cannot remove skidbuffer instructions "
448 "that occur before delay slot [sn:%i].\n",
449 fromCommit->commitInfo[tid].bdelayDoneSeqNum,
450 tid);
451 break;
452 } else {
453 DPRINTF(IEW, "[tid:%i]: Removing instruction [sn:%i] from "
454 "skidBuffer.\n", tid, skidBuffer[tid].front()->seqNum);
455 }
456#endif
457 if (skidBuffer[tid].front()->isLoad() ||
458 skidBuffer[tid].front()->isStore() ) {
459 toRename->iewInfo[tid].dispatchedToLSQ++;
460 }
461
462 toRename->iewInfo[tid].dispatched++;
463
464 skidBuffer[tid].pop();
465 }
466
467 bdelayDoneSeqNum[tid] = fromCommit->commitInfo[tid].bdelayDoneSeqNum;
468
469 emptyRenameInsts(tid);
470}
471
472template<class Impl>
473void
474DefaultIEW<Impl>::squashDueToBranch(DynInstPtr &inst, unsigned tid)
475{
476 DPRINTF(IEW, "[tid:%i]: Squashing from a specific instruction, PC: %#x "
477 "[sn:%i].\n", tid, inst->readPC(), inst->seqNum);
478
479 toCommit->squash[tid] = true;
480 toCommit->squashedSeqNum[tid] = inst->seqNum;
481 toCommit->mispredPC[tid] = inst->readPC();
482 toCommit->branchMispredict[tid] = true;
483
484#if THE_ISA == ALPHA_ISA
485 toCommit->branchTaken[tid] = inst->readNextPC() !=
486 (inst->readPC() + sizeof(TheISA::MachInst));
487 toCommit->nextPC[tid] = inst->readNextPC();
488#else
489 bool branch_taken = inst->readNextNPC() !=
490 (inst->readNextPC() + sizeof(TheISA::MachInst));
491
492 toCommit->branchTaken[tid] = branch_taken;
493
494 toCommit->condDelaySlotBranch[tid] = inst->isCondDelaySlot();
495
496 if (inst->isCondDelaySlot() && branch_taken) {
497 toCommit->nextPC[tid] = inst->readNextPC();
498 } else {
499 toCommit->nextPC[tid] = inst->readNextNPC();
500 }
501#endif
502
503 toCommit->includeSquashInst[tid] = false;
504
505 wroteToTimeBuffer = true;
506}
507
508template<class Impl>
509void
510DefaultIEW<Impl>::squashDueToMemOrder(DynInstPtr &inst, unsigned tid)
511{
512 DPRINTF(IEW, "[tid:%i]: Squashing from a specific instruction, "
513 "PC: %#x [sn:%i].\n", tid, inst->readPC(), inst->seqNum);
514
515 toCommit->squash[tid] = true;
516 toCommit->squashedSeqNum[tid] = inst->seqNum;
517 toCommit->nextPC[tid] = inst->readNextPC();
518
519 toCommit->includeSquashInst[tid] = false;
520
521 wroteToTimeBuffer = true;
522}
523
524template<class Impl>
525void
526DefaultIEW<Impl>::squashDueToMemBlocked(DynInstPtr &inst, unsigned tid)
527{
528 DPRINTF(IEW, "[tid:%i]: Memory blocked, squashing load and younger insts, "
529 "PC: %#x [sn:%i].\n", tid, inst->readPC(), inst->seqNum);
530
531 toCommit->squash[tid] = true;
532 toCommit->squashedSeqNum[tid] = inst->seqNum;
533 toCommit->nextPC[tid] = inst->readPC();
534
535 // Must include the broadcasted SN in the squash.
536 toCommit->includeSquashInst[tid] = true;
537
538 ldstQueue.setLoadBlockedHandled(tid);
539
540 wroteToTimeBuffer = true;
541}
542
543template<class Impl>
544void
545DefaultIEW<Impl>::block(unsigned tid)
546{
547 DPRINTF(IEW, "[tid:%u]: Blocking.\n", tid);
548
549 if (dispatchStatus[tid] != Blocked &&
550 dispatchStatus[tid] != Unblocking) {
551 toRename->iewBlock[tid] = true;
552 wroteToTimeBuffer = true;
553 }
554
555 // Add the current inputs to the skid buffer so they can be
556 // reprocessed when this stage unblocks.
557 skidInsert(tid);
558
559 dispatchStatus[tid] = Blocked;
560}
561
562template<class Impl>
563void
564DefaultIEW<Impl>::unblock(unsigned tid)
565{
566 DPRINTF(IEW, "[tid:%i]: Reading instructions out of the skid "
567 "buffer %u.\n",tid, tid);
568
569 // If the skid bufffer is empty, signal back to previous stages to unblock.
570 // Also switch status to running.
571 if (skidBuffer[tid].empty()) {
572 toRename->iewUnblock[tid] = true;
573 wroteToTimeBuffer = true;
574 DPRINTF(IEW, "[tid:%i]: Done unblocking.\n",tid);
575 dispatchStatus[tid] = Running;
576 }
577}
578
579template<class Impl>
580void
581DefaultIEW<Impl>::wakeDependents(DynInstPtr &inst)
582{
583 instQueue.wakeDependents(inst);
584}
585
586template<class Impl>
587void
588DefaultIEW<Impl>::rescheduleMemInst(DynInstPtr &inst)
589{
590 instQueue.rescheduleMemInst(inst);
591}
592
593template<class Impl>
594void
595DefaultIEW<Impl>::replayMemInst(DynInstPtr &inst)
596{
597 instQueue.replayMemInst(inst);
598}
599
600template<class Impl>
601void
602DefaultIEW<Impl>::instToCommit(DynInstPtr &inst)
603{
604 // First check the time slot that this instruction will write
605 // to. If there are free write ports at the time, then go ahead
606 // and write the instruction to that time. If there are not,
607 // keep looking back to see where's the first time there's a
608 // free slot.
609 while ((*iewQueue)[wbCycle].insts[wbNumInst]) {
610 ++wbNumInst;
611 if (wbNumInst == wbWidth) {
612 ++wbCycle;
613 wbNumInst = 0;
614 }
615
616 assert((wbCycle * wbWidth + wbNumInst) < wbMax);
617 }
618
619 // Add finished instruction to queue to commit.
620 (*iewQueue)[wbCycle].insts[wbNumInst] = inst;
621 (*iewQueue)[wbCycle].size++;
622}
623
624template <class Impl>
625unsigned
626DefaultIEW<Impl>::validInstsFromRename()
627{
628 unsigned inst_count = 0;
629
630 for (int i=0; i<fromRename->size; i++) {
631 if (!fromRename->insts[i]->isSquashed())
632 inst_count++;
633 }
634
635 return inst_count;
636}
637
638template<class Impl>
639void
640DefaultIEW<Impl>::skidInsert(unsigned tid)
641{
642 DynInstPtr inst = NULL;
643
644 while (!insts[tid].empty()) {
645 inst = insts[tid].front();
646
647 insts[tid].pop();
648
649 DPRINTF(Decode,"[tid:%i]: Inserting [sn:%lli] PC:%#x into "
650 "dispatch skidBuffer %i\n",tid, inst->seqNum,
651 inst->readPC(),tid);
652
653 skidBuffer[tid].push(inst);
654 }
655
656 assert(skidBuffer[tid].size() <= skidBufferMax &&
657 "Skidbuffer Exceeded Max Size");
658}
659
660template<class Impl>
661int
662DefaultIEW<Impl>::skidCount()
663{
664 int max=0;
665
666 list<unsigned>::iterator threads = (*activeThreads).begin();
667
668 while (threads != (*activeThreads).end()) {
669 unsigned thread_count = skidBuffer[*threads++].size();
670 if (max < thread_count)
671 max = thread_count;
672 }
673
674 return max;
675}
676
677template<class Impl>
678bool
679DefaultIEW<Impl>::skidsEmpty()
680{
681 list<unsigned>::iterator threads = (*activeThreads).begin();
682
683 while (threads != (*activeThreads).end()) {
684 if (!skidBuffer[*threads++].empty())
685 return false;
686 }
687
688 return true;
689}
690
691template <class Impl>
692void
693DefaultIEW<Impl>::updateStatus()
694{
695 bool any_unblocking = false;
696
697 list<unsigned>::iterator threads = (*activeThreads).begin();
698
699 threads = (*activeThreads).begin();
700
701 while (threads != (*activeThreads).end()) {
702 unsigned tid = *threads++;
703
704 if (dispatchStatus[tid] == Unblocking) {
705 any_unblocking = true;
706 break;
707 }
708 }
709
710 // If there are no ready instructions waiting to be scheduled by the IQ,
711 // and there's no stores waiting to write back, and dispatch is not
712 // unblocking, then there is no internal activity for the IEW stage.
713 if (_status == Active && !instQueue.hasReadyInsts() &&
714 !ldstQueue.willWB() && !any_unblocking) {
715 DPRINTF(IEW, "IEW switching to idle\n");
716
717 deactivateStage();
718
719 _status = Inactive;
720 } else if (_status == Inactive && (instQueue.hasReadyInsts() ||
721 ldstQueue.willWB() ||
722 any_unblocking)) {
723 // Otherwise there is internal activity. Set to active.
724 DPRINTF(IEW, "IEW switching to active\n");
725
726 activateStage();
727
728 _status = Active;
729 }
730}
731
732template <class Impl>
733void
734DefaultIEW<Impl>::resetEntries()
735{
736 instQueue.resetEntries();
737 ldstQueue.resetEntries();
738}
739
740template <class Impl>
741void
742DefaultIEW<Impl>::readStallSignals(unsigned tid)
743{
744 if (fromCommit->commitBlock[tid]) {
745 stalls[tid].commit = true;
746 }
747
748 if (fromCommit->commitUnblock[tid]) {
749 assert(stalls[tid].commit);
750 stalls[tid].commit = false;
751 }
752}
753
754template <class Impl>
755bool
756DefaultIEW<Impl>::checkStall(unsigned tid)
757{
758 bool ret_val(false);
759
760 if (stalls[tid].commit) {
761 DPRINTF(IEW,"[tid:%i]: Stall from Commit stage detected.\n",tid);
762 ret_val = true;
763 } else if (instQueue.isFull(tid)) {
764 DPRINTF(IEW,"[tid:%i]: Stall: IQ is full.\n",tid);
765 ret_val = true;
766 } else if (ldstQueue.isFull(tid)) {
767 DPRINTF(IEW,"[tid:%i]: Stall: LSQ is full\n",tid);
768
769 if (ldstQueue.numLoads(tid) > 0 ) {
770
771 DPRINTF(IEW,"[tid:%i]: LSQ oldest load: [sn:%i] \n",
772 tid,ldstQueue.getLoadHeadSeqNum(tid));
773 }
774
775 if (ldstQueue.numStores(tid) > 0) {
776
777 DPRINTF(IEW,"[tid:%i]: LSQ oldest store: [sn:%i] \n",
778 tid,ldstQueue.getStoreHeadSeqNum(tid));
779 }
780
781 ret_val = true;
782 } else if (ldstQueue.isStalled(tid)) {
783 DPRINTF(IEW,"[tid:%i]: Stall: LSQ stall detected.\n",tid);
784 ret_val = true;
785 }
786
787 return ret_val;
788}
789
790template <class Impl>
791void
792DefaultIEW<Impl>::checkSignalsAndUpdate(unsigned tid)
793{
794 // Check if there's a squash signal, squash if there is
795 // Check stall signals, block if there is.
796 // If status was Blocked
797 // if so then go to unblocking
798 // If status was Squashing
799 // check if squashing is not high. Switch to running this cycle.
800
801 readStallSignals(tid);
802
803 if (fromCommit->commitInfo[tid].squash) {
804 squash(tid);
805
806 if (dispatchStatus[tid] == Blocked ||
807 dispatchStatus[tid] == Unblocking) {
808 toRename->iewUnblock[tid] = true;
809 wroteToTimeBuffer = true;
810 }
811
812 dispatchStatus[tid] = Squashing;
813
814 fetchRedirect[tid] = false;
815 return;
816 }
817
818 if (fromCommit->commitInfo[tid].robSquashing) {
819 DPRINTF(IEW, "[tid:%i]: ROB is still squashing.\n", tid);
820
821 dispatchStatus[tid] = Squashing;
822
823 emptyRenameInsts(tid);
824 wroteToTimeBuffer = true;
825 return;
826 }
827
828 if (checkStall(tid)) {
829 block(tid);
830 dispatchStatus[tid] = Blocked;
831 return;
832 }
833
834 if (dispatchStatus[tid] == Blocked) {
835 // Status from previous cycle was blocked, but there are no more stall
836 // conditions. Switch over to unblocking.
837 DPRINTF(IEW, "[tid:%i]: Done blocking, switching to unblocking.\n",
838 tid);
839
840 dispatchStatus[tid] = Unblocking;
841
842 unblock(tid);
843
844 return;
845 }
846
847 if (dispatchStatus[tid] == Squashing) {
848 // Switch status to running if rename isn't being told to block or
849 // squash this cycle.
850 DPRINTF(IEW, "[tid:%i]: Done squashing, switching to running.\n",
851 tid);
852
853 dispatchStatus[tid] = Running;
854
855 return;
856 }
857}
858
859template <class Impl>
860void
861DefaultIEW<Impl>::sortInsts()
862{
863 int insts_from_rename = fromRename->size;
864#ifdef DEBUG
865#if THE_ISA == ALPHA_ISA
866 for (int i = 0; i < numThreads; i++)
867 assert(insts[i].empty());
868#endif
869#endif
870 for (int i = 0; i < insts_from_rename; ++i) {
871 insts[fromRename->insts[i]->threadNumber].push(fromRename->insts[i]);
872 }
873}
874
875template <class Impl>
876void
877DefaultIEW<Impl>::emptyRenameInsts(unsigned tid)
878{
879 DPRINTF(IEW, "[tid:%i]: Removing incoming rename instructions until "
880 "[sn:%i].\n", tid, bdelayDoneSeqNum[tid]);
881
882 while (!insts[tid].empty()) {
883
884#if THE_ISA != ALPHA_ISA
885 if (insts[tid].front()->seqNum <= bdelayDoneSeqNum[tid]) {
886 DPRINTF(IEW, "[tid:%i]: Done removing, cannot remove instruction"
887 " that occurs at or before delay slot [sn:%i].\n",
888 tid, bdelayDoneSeqNum[tid]);
889 break;
890 } else {
891 DPRINTF(IEW, "[tid:%i]: Removing incoming rename instruction "
892 "[sn:%i].\n", tid, insts[tid].front()->seqNum);
893 }
894#endif
895
896 if (insts[tid].front()->isLoad() ||
897 insts[tid].front()->isStore() ) {
898 toRename->iewInfo[tid].dispatchedToLSQ++;
899 }
900
901 toRename->iewInfo[tid].dispatched++;
902
903 insts[tid].pop();
904 }
905}
906
907template <class Impl>
908void
909DefaultIEW<Impl>::wakeCPU()
910{
911 cpu->wakeCPU();
912}
913
914template <class Impl>
915void
916DefaultIEW<Impl>::activityThisCycle()
917{
918 DPRINTF(Activity, "Activity this cycle.\n");
919 cpu->activityThisCycle();
920}
921
922template <class Impl>
923inline void
924DefaultIEW<Impl>::activateStage()
925{
926 DPRINTF(Activity, "Activating stage.\n");
927 cpu->activateStage(O3CPU::IEWIdx);
928}
929
930template <class Impl>
931inline void
932DefaultIEW<Impl>::deactivateStage()
933{
934 DPRINTF(Activity, "Deactivating stage.\n");
935 cpu->deactivateStage(O3CPU::IEWIdx);
936}
937
938template<class Impl>
939void
940DefaultIEW<Impl>::dispatch(unsigned tid)
941{
942 // If status is Running or idle,
943 // call dispatchInsts()
944 // If status is Unblocking,
945 // buffer any instructions coming from rename
946 // continue trying to empty skid buffer
947 // check if stall conditions have passed
948
949 if (dispatchStatus[tid] == Blocked) {
950 ++iewBlockCycles;
951
952 } else if (dispatchStatus[tid] == Squashing) {
953 ++iewSquashCycles;
954 }
955
956 // Dispatch should try to dispatch as many instructions as its bandwidth
957 // will allow, as long as it is not currently blocked.
958 if (dispatchStatus[tid] == Running ||
959 dispatchStatus[tid] == Idle) {
960 DPRINTF(IEW, "[tid:%i] Not blocked, so attempting to run "
961 "dispatch.\n", tid);
962
963 dispatchInsts(tid);
964 } else if (dispatchStatus[tid] == Unblocking) {
965 // Make sure that the skid buffer has something in it if the
966 // status is unblocking.
967 assert(!skidsEmpty());
968
969 // If the status was unblocking, then instructions from the skid
970 // buffer were used. Remove those instructions and handle
971 // the rest of unblocking.
972 dispatchInsts(tid);
973
974 ++iewUnblockCycles;
975
976 if (validInstsFromRename() && dispatchedAllInsts) {
977 // Add the current inputs to the skid buffer so they can be
978 // reprocessed when this stage unblocks.
979 skidInsert(tid);
980 }
981
982 unblock(tid);
983 }
984}
985
986template <class Impl>
987void
988DefaultIEW<Impl>::dispatchInsts(unsigned tid)
989{
990 dispatchedAllInsts = true;
991
992 // Obtain instructions from skid buffer if unblocking, or queue from rename
993 // otherwise.
994 std::queue<DynInstPtr> &insts_to_dispatch =
995 dispatchStatus[tid] == Unblocking ?
996 skidBuffer[tid] : insts[tid];
997
998 int insts_to_add = insts_to_dispatch.size();
999
1000 DynInstPtr inst;
1001 bool add_to_iq = false;
1002 int dis_num_inst = 0;
1003
1004 // Loop through the instructions, putting them in the instruction
1005 // queue.
1006 for ( ; dis_num_inst < insts_to_add &&
1007 dis_num_inst < dispatchWidth;
1008 ++dis_num_inst)
1009 {
1010 inst = insts_to_dispatch.front();
1011
1012 if (dispatchStatus[tid] == Unblocking) {
1013 DPRINTF(IEW, "[tid:%i]: Issue: Examining instruction from skid "
1014 "buffer\n", tid);
1015 }
1016
1017 // Make sure there's a valid instruction there.
1018 assert(inst);
1019
1020 DPRINTF(IEW, "[tid:%i]: Issue: Adding PC %#x [sn:%lli] [tid:%i] to "
1021 "IQ.\n",
1022 tid, inst->readPC(), inst->seqNum, inst->threadNumber);
1023
1024 // Be sure to mark these instructions as ready so that the
1025 // commit stage can go ahead and execute them, and mark
1026 // them as issued so the IQ doesn't reprocess them.
1027
1028 // Check for squashed instructions.
1029 if (inst->isSquashed()) {
1030 DPRINTF(IEW, "[tid:%i]: Issue: Squashed instruction encountered, "
1031 "not adding to IQ.\n", tid);
1032
1033 ++iewDispSquashedInsts;
1034
1035 insts_to_dispatch.pop();
1036
1037 //Tell Rename That An Instruction has been processed
1038 if (inst->isLoad() || inst->isStore()) {
1039 toRename->iewInfo[tid].dispatchedToLSQ++;
1040 }
1041 toRename->iewInfo[tid].dispatched++;
1042
1043 continue;
1044 }
1045
1046 // Check for full conditions.
1047 if (instQueue.isFull(tid)) {
1048 DPRINTF(IEW, "[tid:%i]: Issue: IQ has become full.\n", tid);
1049
1050 // Call function to start blocking.
1051 block(tid);
1052
1053 // Set unblock to false. Special case where we are using
1054 // skidbuffer (unblocking) instructions but then we still
1055 // get full in the IQ.
1056 toRename->iewUnblock[tid] = false;
1057
1058 dispatchedAllInsts = false;
1059
1060 ++iewIQFullEvents;
1061 break;
1062 } else if (ldstQueue.isFull(tid)) {
1063 DPRINTF(IEW, "[tid:%i]: Issue: LSQ has become full.\n",tid);
1064
1065 // Call function to start blocking.
1066 block(tid);
1067
1068 // Set unblock to false. Special case where we are using
1069 // skidbuffer (unblocking) instructions but then we still
1070 // get full in the IQ.
1071 toRename->iewUnblock[tid] = false;
1072
1073 dispatchedAllInsts = false;
1074
1075 ++iewLSQFullEvents;
1076 break;
1077 }
1078
1079 // Otherwise issue the instruction just fine.
1080 if (inst->isLoad()) {
1081 DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1082 "encountered, adding to LSQ.\n", tid);
1083
1084 // Reserve a spot in the load store queue for this
1085 // memory access.
1086 ldstQueue.insertLoad(inst);
1087
1088 ++iewDispLoadInsts;
1089
1090 add_to_iq = true;
1091
1092 toRename->iewInfo[tid].dispatchedToLSQ++;
1093 } else if (inst->isStore()) {
1094 DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1095 "encountered, adding to LSQ.\n", tid);
1096
1097 ldstQueue.insertStore(inst);
1098
1099 ++iewDispStoreInsts;
1100
1101 if (inst->isStoreConditional()) {
1102 // Store conditionals need to be set as "canCommit()"
1103 // so that commit can process them when they reach the
1104 // head of commit.
1105 // @todo: This is somewhat specific to Alpha.
1106 inst->setCanCommit();
1107 instQueue.insertNonSpec(inst);
1108 add_to_iq = false;
1109
1110 ++iewDispNonSpecInsts;
1111 } else {
1112 add_to_iq = true;
1113 }
1114
1115 toRename->iewInfo[tid].dispatchedToLSQ++;
1116#if FULL_SYSTEM
1117 } else if (inst->isMemBarrier() || inst->isWriteBarrier()) {
1118 // Same as non-speculative stores.
1119 inst->setCanCommit();
1120 instQueue.insertBarrier(inst);
1121 add_to_iq = false;
1122#endif
1123 } else if (inst->isNonSpeculative()) {
1124 DPRINTF(IEW, "[tid:%i]: Issue: Nonspeculative instruction "
1125 "encountered, skipping.\n", tid);
1126
1127 // Same as non-speculative stores.
1128 inst->setCanCommit();
1129
1130 // Specifically insert it as nonspeculative.
1131 instQueue.insertNonSpec(inst);
1132
1133 ++iewDispNonSpecInsts;
1134
1135 add_to_iq = false;
1136 } else if (inst->isNop()) {
1137 DPRINTF(IEW, "[tid:%i]: Issue: Nop instruction encountered, "
1138 "skipping.\n", tid);
1139
1140 inst->setIssued();
1141 inst->setExecuted();
1142 inst->setCanCommit();
1143
1144 instQueue.recordProducer(inst);
1145
1146 iewExecutedNop[tid]++;
1147
1148 add_to_iq = false;
1149 } else if (inst->isExecuted()) {
1150 assert(0 && "Instruction shouldn't be executed.\n");
1151 DPRINTF(IEW, "Issue: Executed branch encountered, "
1152 "skipping.\n");
1153
1154 inst->setIssued();
1155 inst->setCanCommit();
1156
1157 instQueue.recordProducer(inst);
1158
1159 add_to_iq = false;
1160 } else {
1161 add_to_iq = true;
1162 }
1163
1164 // If the instruction queue is not full, then add the
1165 // instruction.
1166 if (add_to_iq) {
1167 instQueue.insert(inst);
1168 }
1169
1170 insts_to_dispatch.pop();
1171
1172 toRename->iewInfo[tid].dispatched++;
1173
1174 ++iewDispatchedInsts;
1175 }
1176
1177 if (!insts_to_dispatch.empty()) {
1178 DPRINTF(IEW,"[tid:%i]: Issue: Bandwidth Full. Blocking.\n", tid);
1179 block(tid);
1180 toRename->iewUnblock[tid] = false;
1181 }
1182
1183 if (dispatchStatus[tid] == Idle && dis_num_inst) {
1184 dispatchStatus[tid] = Running;
1185
1186 updatedQueues = true;
1187 }
1188
1189 dis_num_inst = 0;
1190}
1191
1192template <class Impl>
1193void
1194DefaultIEW<Impl>::printAvailableInsts()
1195{
1196 int inst = 0;
1197
1198 cout << "Available Instructions: ";
1199
1200 while (fromIssue->insts[inst]) {
1201
1202 if (inst%3==0) cout << "\n\t";
1203
1204 cout << "PC: " << fromIssue->insts[inst]->readPC()
1205 << " TN: " << fromIssue->insts[inst]->threadNumber
1206 << " SN: " << fromIssue->insts[inst]->seqNum << " | ";
1207
1208 inst++;
1209
1210 }
1211
1212 cout << "\n";
1213}
1214
1215template <class Impl>
1216void
1217DefaultIEW<Impl>::executeInsts()
1218{
1219 wbNumInst = 0;
1220 wbCycle = 0;
1221
1222 list<unsigned>::iterator threads = (*activeThreads).begin();
1223
1224 while (threads != (*activeThreads).end()) {
1225 unsigned tid = *threads++;
1226 fetchRedirect[tid] = false;
1227 }
1228
1229 // Uncomment this if you want to see all available instructions.
1230// printAvailableInsts();
1231
1232 // Execute/writeback any instructions that are available.
1233 int insts_to_execute = fromIssue->size;
1234 int inst_num = 0;
1235 for (; inst_num < insts_to_execute;
1236 ++inst_num) {
1237
1238 DPRINTF(IEW, "Execute: Executing instructions from IQ.\n");
1239
1240 DynInstPtr inst = instQueue.getInstToExecute();
1241
1242 DPRINTF(IEW, "Execute: Processing PC %#x, [tid:%i] [sn:%i].\n",
1243 inst->readPC(), inst->threadNumber,inst->seqNum);
1244
1245 // Check if the instruction is squashed; if so then skip it
1246 if (inst->isSquashed()) {
1247 DPRINTF(IEW, "Execute: Instruction was squashed.\n");
1248
1249 // Consider this instruction executed so that commit can go
1250 // ahead and retire the instruction.
1251 inst->setExecuted();
1252
1253 // Not sure if I should set this here or just let commit try to
1254 // commit any squashed instructions. I like the latter a bit more.
1255 inst->setCanCommit();
1256
1257 ++iewExecSquashedInsts;
1258
1259 decrWb(inst->seqNum);
1260 continue;
1261 }
1262
1263 Fault fault = NoFault;
1264
1265 // Execute instruction.
1266 // Note that if the instruction faults, it will be handled
1267 // at the commit stage.
1268 if (inst->isMemRef() &&
1269 (!inst->isDataPrefetch() && !inst->isInstPrefetch())) {
1270 DPRINTF(IEW, "Execute: Calculating address for memory "
1271 "reference.\n");
1272
1273 // Tell the LDSTQ to execute this instruction (if it is a load).
1274 if (inst->isLoad()) {
1275 // Loads will mark themselves as executed, and their writeback
1276 // event adds the instruction to the queue to commit
1277 fault = ldstQueue.executeLoad(inst);
1278 } else if (inst->isStore()) {
1279 ldstQueue.executeStore(inst);
1280
1281 // If the store had a fault then it may not have a mem req
1282 if (inst->req && !(inst->req->getFlags() & LOCKED)) {
1283 inst->setExecuted();
1284
1285 instToCommit(inst);
1286 }
1287
1288 // Store conditionals will mark themselves as
1289 // executed, and their writeback event will add the
1290 // instruction to the queue to commit.
1291 } else {
1292 panic("Unexpected memory type!\n");
1293 }
1294
1295 } else {
1296 inst->execute();
1297
1298 inst->setExecuted();
1299
1300 instToCommit(inst);
1301 }
1302
1303 updateExeInstStats(inst);
1304
1305 // Check if branch prediction was correct, if not then we need
1306 // to tell commit to squash in flight instructions. Only
1307 // handle this if there hasn't already been something that
1308 // redirects fetch in this group of instructions.
1309
1310 // This probably needs to prioritize the redirects if a different
1311 // scheduler is used. Currently the scheduler schedules the oldest
1312 // instruction first, so the branch resolution order will be correct.
1313 unsigned tid = inst->threadNumber;
1314
1315 if (!fetchRedirect[tid]) {
1316
1317 if (inst->mispredicted()) {
1318 fetchRedirect[tid] = true;
1319
1320 DPRINTF(IEW, "Execute: Branch mispredict detected.\n");
1321#if THE_ISA == ALPHA_ISA
1322 DPRINTF(IEW, "Execute: Redirecting fetch to PC: %#x.\n",
1323 inst->nextPC);
1324#else
1325 DPRINTF(IEW, "Execute: Redirecting fetch to PC: %#x.\n",
1326 inst->nextNPC);
1327#endif
1328 // If incorrect, then signal the ROB that it must be squashed.
1329 squashDueToBranch(inst, tid);
1330
1331 if (inst->predTaken()) {
1332 predictedTakenIncorrect++;
1333 } else {
1334 predictedNotTakenIncorrect++;
1335 }
1336 } else if (ldstQueue.violation(tid)) {
1337 fetchRedirect[tid] = true;
1338
1339 // If there was an ordering violation, then get the
1340 // DynInst that caused the violation. Note that this
1341 // clears the violation signal.
1342 DynInstPtr violator;
1343 violator = ldstQueue.getMemDepViolator(tid);
1344
1345 DPRINTF(IEW, "LDSTQ detected a violation. Violator PC: "
1346 "%#x, inst PC: %#x. Addr is: %#x.\n",
1347 violator->readPC(), inst->readPC(), inst->physEffAddr);
1348
1349 // Tell the instruction queue that a violation has occured.
1350 instQueue.violation(inst, violator);
1351
1352 // Squash.
1353 squashDueToMemOrder(inst,tid);
1354
1355 ++memOrderViolationEvents;
1356 } else if (ldstQueue.loadBlocked(tid) &&
1357 !ldstQueue.isLoadBlockedHandled(tid)) {
1358 fetchRedirect[tid] = true;
1359
1360 DPRINTF(IEW, "Load operation couldn't execute because the "
1361 "memory system is blocked. PC: %#x [sn:%lli]\n",
1362 inst->readPC(), inst->seqNum);
1363
1364 squashDueToMemBlocked(inst, tid);
1365 }
1366 }
1367 }
1368
1369 // Update and record activity if we processed any instructions.
1370 if (inst_num) {
1371 if (exeStatus == Idle) {
1372 exeStatus = Running;
1373 }
1374
1375 updatedQueues = true;
1376
1377 cpu->activityThisCycle();
1378 }
1379
1380 // Need to reset this in case a writeback event needs to write into the
1381 // iew queue. That way the writeback event will write into the correct
1382 // spot in the queue.
1383 wbNumInst = 0;
1384}
1385
1386template <class Impl>
1387void
1388DefaultIEW<Impl>::writebackInsts()
1389{
1390 // Loop through the head of the time buffer and wake any
1391 // dependents. These instructions are about to write back. Also
1392 // mark scoreboard that this instruction is finally complete.
1393 // Either have IEW have direct access to scoreboard, or have this
1394 // as part of backwards communication.
1395 for (int inst_num = 0; inst_num < issueWidth &&
1396 toCommit->insts[inst_num]; inst_num++) {
1397 DynInstPtr inst = toCommit->insts[inst_num];
1398 int tid = inst->threadNumber;
1399
1400 DPRINTF(IEW, "Sending instructions to commit, [sn:%lli] PC %#x.\n",
1401 inst->seqNum, inst->readPC());
1402
1403 iewInstsToCommit[tid]++;
1404
1405 // Some instructions will be sent to commit without having
1406 // executed because they need commit to handle them.
1407 // E.g. Uncached loads have not actually executed when they
1408 // are first sent to commit. Instead commit must tell the LSQ
1409 // when it's ready to execute the uncached load.
1410 if (!inst->isSquashed() && inst->isExecuted()) {
1411 int dependents = instQueue.wakeDependents(inst);
1412
1413 for (int i = 0; i < inst->numDestRegs(); i++) {
1414 //mark as Ready
1415 DPRINTF(IEW,"Setting Destination Register %i\n",
1416 inst->renamedDestRegIdx(i));
1417 scoreboard->setReg(inst->renamedDestRegIdx(i));
1418 }
1419
1420 if (dependents) {
1421 producerInst[tid]++;
1422 consumerInst[tid]+= dependents;
1423 }
1424 writebackCount[tid]++;
1425 }
1426
1427 decrWb(inst->seqNum);
1428 }
1429}
1430
1431template<class Impl>
1432void
1433DefaultIEW<Impl>::tick()
1434{
1435 wbNumInst = 0;
1436 wbCycle = 0;
1437
1438 wroteToTimeBuffer = false;
1439 updatedQueues = false;
1440
1441 sortInsts();
1442
1443 // Free function units marked as being freed this cycle.
1444 fuPool->processFreeUnits();
1445
1446 list<unsigned>::iterator threads = (*activeThreads).begin();
1447
1448 // Check stall and squash signals, dispatch any instructions.
1449 while (threads != (*activeThreads).end()) {
1450 unsigned tid = *threads++;
1451
1452 DPRINTF(IEW,"Issue: Processing [tid:%i]\n",tid);
1453
1454 checkSignalsAndUpdate(tid);
1455 dispatch(tid);
1456 }
1457
1458 if (exeStatus != Squashing) {
1459 executeInsts();
1460
1461 writebackInsts();
1462
1463 // Have the instruction queue try to schedule any ready instructions.
1464 // (In actuality, this scheduling is for instructions that will
1465 // be executed next cycle.)
1466 instQueue.scheduleReadyInsts();
1467
1468 // Also should advance its own time buffers if the stage ran.
1469 // Not the best place for it, but this works (hopefully).
1470 issueToExecQueue.advance();
1471 }
1472
1473 bool broadcast_free_entries = false;
1474
1475 if (updatedQueues || exeStatus == Running || updateLSQNextCycle) {
1476 exeStatus = Idle;
1477 updateLSQNextCycle = false;
1478
1479 broadcast_free_entries = true;
1480 }
1481
1482 // Writeback any stores using any leftover bandwidth.
1483 ldstQueue.writebackStores();
1484
1485 // Check the committed load/store signals to see if there's a load
1486 // or store to commit. Also check if it's being told to execute a
1487 // nonspeculative instruction.
1488 // This is pretty inefficient...
1489
1490 threads = (*activeThreads).begin();
1491 while (threads != (*activeThreads).end()) {
1492 unsigned tid = (*threads++);
1493
1494 DPRINTF(IEW,"Processing [tid:%i]\n",tid);
1495
1496 // Update structures based on instructions committed.
1497 if (fromCommit->commitInfo[tid].doneSeqNum != 0 &&
1498 !fromCommit->commitInfo[tid].squash &&
1499 !fromCommit->commitInfo[tid].robSquashing) {
1500
1501 ldstQueue.commitStores(fromCommit->commitInfo[tid].doneSeqNum,tid);
1502
1503 ldstQueue.commitLoads(fromCommit->commitInfo[tid].doneSeqNum,tid);
1504
1505 updateLSQNextCycle = true;
1506 instQueue.commit(fromCommit->commitInfo[tid].doneSeqNum,tid);
1507 }
1508
1509 if (fromCommit->commitInfo[tid].nonSpecSeqNum != 0) {
1510
1511 //DPRINTF(IEW,"NonspecInst from thread %i",tid);
1512 if (fromCommit->commitInfo[tid].uncached) {
1513 instQueue.replayMemInst(fromCommit->commitInfo[tid].uncachedLoad);
1514 } else {
1515 instQueue.scheduleNonSpec(
1516 fromCommit->commitInfo[tid].nonSpecSeqNum);
1517 }
1518 }
1519
1520 if (broadcast_free_entries) {
1521 toFetch->iewInfo[tid].iqCount =
1522 instQueue.getCount(tid);
1523 toFetch->iewInfo[tid].ldstqCount =
1524 ldstQueue.getCount(tid);
1525
1526 toRename->iewInfo[tid].usedIQ = true;
1527 toRename->iewInfo[tid].freeIQEntries =
1528 instQueue.numFreeEntries();
1529 toRename->iewInfo[tid].usedLSQ = true;
1530 toRename->iewInfo[tid].freeLSQEntries =
1531 ldstQueue.numFreeEntries(tid);
1532
1533 wroteToTimeBuffer = true;
1534 }
1535
1536 DPRINTF(IEW, "[tid:%i], Dispatch dispatched %i instructions.\n",
1537 tid, toRename->iewInfo[tid].dispatched);
1538 }
1539
1540 DPRINTF(IEW, "IQ has %i free entries (Can schedule: %i). "
1541 "LSQ has %i free entries.\n",
1542 instQueue.numFreeEntries(), instQueue.hasReadyInsts(),
1543 ldstQueue.numFreeEntries());
1544
1545 updateStatus();
1546
1547 if (wroteToTimeBuffer) {
1548 DPRINTF(Activity, "Activity this cycle.\n");
1549 cpu->activityThisCycle();
1550 }
1551}
1552
1553template <class Impl>
1554void
1555DefaultIEW<Impl>::updateExeInstStats(DynInstPtr &inst)
1556{
1557 int thread_number = inst->threadNumber;
1558
1559 //
1560 // Pick off the software prefetches
1561 //
1562#ifdef TARGET_ALPHA
1563 if (inst->isDataPrefetch())
1564 iewExecutedSwp[thread_number]++;
1565 else
1566 iewIewExecutedcutedInsts++;
1567#else
1568 iewExecutedInsts++;
1569#endif
1570
1571 //
1572 // Control operations
1573 //
1574 if (inst->isControl())
1575 iewExecutedBranches[thread_number]++;
1576
1577 //
1578 // Memory operations
1579 //
1580 if (inst->isMemRef()) {
1581 iewExecutedRefs[thread_number]++;
1582
1583 if (inst->isLoad()) {
1584 iewExecLoadInsts[thread_number]++;
1585 }
1586 }
1587}