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 "config/the_isa.hh"
39#include "cpu/o3/fu_pool.hh"
40#include "cpu/o3/iew.hh"
41#include "params/DerivO3CPU.hh"
42
43using namespace std;
44
45template<class Impl>
46DefaultIEW<Impl>::DefaultIEW(O3CPU *_cpu, DerivO3CPUParams *params)
47 : issueToExecQueue(params->backComSize, params->forwardComSize),
48 cpu(_cpu),
49 instQueue(_cpu, this, params),
50 ldstQueue(_cpu, this, params),
51 fuPool(params->fuPool),
52 commitToIEWDelay(params->commitToIEWDelay),
53 renameToIEWDelay(params->renameToIEWDelay),
54 issueToExecuteDelay(params->issueToExecuteDelay),
55 dispatchWidth(params->dispatchWidth),
56 issueWidth(params->issueWidth),
57 wbOutstanding(0),
58 wbWidth(params->wbWidth),
59 numThreads(params->numThreads),
60 switchedOut(false)
61{
62 _status = Active;
63 exeStatus = Running;
64 wbStatus = Idle;
65
66 // Setup wire to read instructions coming from issue.
67 fromIssue = issueToExecQueue.getWire(-issueToExecuteDelay);
68
69 // Instruction queue needs the queue between issue and execute.
70 instQueue.setIssueToExecuteQueue(&issueToExecQueue);
71
72 for (ThreadID tid = 0; tid < numThreads; tid++) {
73 dispatchStatus[tid] = Running;
74 stalls[tid].commit = false;
75 fetchRedirect[tid] = false;
76 }
77
78 wbMax = wbWidth * params->wbDepth;
79
80 updateLSQNextCycle = false;
81
82 ableToIssue = true;
83
84 skidBufferMax = (3 * (renameToIEWDelay * params->renameWidth)) + issueWidth;
85}
86
87template <class Impl>
88std::string
89DefaultIEW<Impl>::name() const
90{
91 return cpu->name() + ".iew";
92}
93
94template <class Impl>
95void
96DefaultIEW<Impl>::regStats()
97{
98 using namespace Stats;
99
100 instQueue.regStats();
101 ldstQueue.regStats();
102
103 iewIdleCycles
104 .name(name() + ".iewIdleCycles")
105 .desc("Number of cycles IEW is idle");
106
107 iewSquashCycles
108 .name(name() + ".iewSquashCycles")
109 .desc("Number of cycles IEW is squashing");
110
111 iewBlockCycles
112 .name(name() + ".iewBlockCycles")
113 .desc("Number of cycles IEW is blocking");
114
115 iewUnblockCycles
116 .name(name() + ".iewUnblockCycles")
117 .desc("Number of cycles IEW is unblocking");
118
119 iewDispatchedInsts
120 .name(name() + ".iewDispatchedInsts")
121 .desc("Number of instructions dispatched to IQ");
122
123 iewDispSquashedInsts
124 .name(name() + ".iewDispSquashedInsts")
125 .desc("Number of squashed instructions skipped by dispatch");
126
127 iewDispLoadInsts
128 .name(name() + ".iewDispLoadInsts")
129 .desc("Number of dispatched load instructions");
130
131 iewDispStoreInsts
132 .name(name() + ".iewDispStoreInsts")
133 .desc("Number of dispatched store instructions");
134
135 iewDispNonSpecInsts
136 .name(name() + ".iewDispNonSpecInsts")
137 .desc("Number of dispatched non-speculative instructions");
138
139 iewIQFullEvents
140 .name(name() + ".iewIQFullEvents")
141 .desc("Number of times the IQ has become full, causing a stall");
142
143 iewLSQFullEvents
144 .name(name() + ".iewLSQFullEvents")
145 .desc("Number of times the LSQ has become full, causing a stall");
146
147 memOrderViolationEvents
148 .name(name() + ".memOrderViolationEvents")
149 .desc("Number of memory order violations");
150
151 predictedTakenIncorrect
152 .name(name() + ".predictedTakenIncorrect")
153 .desc("Number of branches that were predicted taken incorrectly");
154
155 predictedNotTakenIncorrect
156 .name(name() + ".predictedNotTakenIncorrect")
157 .desc("Number of branches that were predicted not taken incorrectly");
158
159 branchMispredicts
160 .name(name() + ".branchMispredicts")
161 .desc("Number of branch mispredicts detected at execute");
162
163 branchMispredicts = predictedTakenIncorrect + predictedNotTakenIncorrect;
164
165 iewExecutedInsts
166 .name(name() + ".iewExecutedInsts")
167 .desc("Number of executed instructions");
168
169 iewExecLoadInsts
170 .init(cpu->numThreads)
171 .name(name() + ".iewExecLoadInsts")
172 .desc("Number of load instructions executed")
173 .flags(total);
174
175 iewExecSquashedInsts
176 .name(name() + ".iewExecSquashedInsts")
177 .desc("Number of squashed instructions skipped in execute");
178
179 iewExecutedSwp
180 .init(cpu->numThreads)
181 .name(name() + ".EXEC:swp")
182 .desc("number of swp insts executed")
183 .flags(total);
184
185 iewExecutedNop
186 .init(cpu->numThreads)
187 .name(name() + ".EXEC:nop")
188 .desc("number of nop insts executed")
189 .flags(total);
190
191 iewExecutedRefs
192 .init(cpu->numThreads)
193 .name(name() + ".EXEC:refs")
194 .desc("number of memory reference insts executed")
195 .flags(total);
196
197 iewExecutedBranches
198 .init(cpu->numThreads)
199 .name(name() + ".EXEC:branches")
200 .desc("Number of branches executed")
201 .flags(total);
202
203 iewExecStoreInsts
204 .name(name() + ".EXEC:stores")
205 .desc("Number of stores executed")
206 .flags(total);
207 iewExecStoreInsts = iewExecutedRefs - iewExecLoadInsts;
208
209 iewExecRate
210 .name(name() + ".EXEC:rate")
211 .desc("Inst execution rate")
212 .flags(total);
213
214 iewExecRate = iewExecutedInsts / cpu->numCycles;
215
216 iewInstsToCommit
217 .init(cpu->numThreads)
218 .name(name() + ".WB:sent")
219 .desc("cumulative count of insts sent to commit")
220 .flags(total);
221
222 writebackCount
223 .init(cpu->numThreads)
224 .name(name() + ".WB:count")
225 .desc("cumulative count of insts written-back")
226 .flags(total);
227
228 producerInst
229 .init(cpu->numThreads)
230 .name(name() + ".WB:producers")
231 .desc("num instructions producing a value")
232 .flags(total);
233
234 consumerInst
235 .init(cpu->numThreads)
236 .name(name() + ".WB:consumers")
237 .desc("num instructions consuming a value")
238 .flags(total);
239
240 wbPenalized
241 .init(cpu->numThreads)
242 .name(name() + ".WB:penalized")
243 .desc("number of instrctions required to write to 'other' IQ")
244 .flags(total);
245
246 wbPenalizedRate
247 .name(name() + ".WB:penalized_rate")
248 .desc ("fraction of instructions written-back that wrote to 'other' IQ")
249 .flags(total);
250
251 wbPenalizedRate = wbPenalized / writebackCount;
252
253 wbFanout
254 .name(name() + ".WB:fanout")
255 .desc("average fanout of values written-back")
256 .flags(total);
257
258 wbFanout = producerInst / consumerInst;
259
260 wbRate
261 .name(name() + ".WB:rate")
262 .desc("insts written-back per cycle")
263 .flags(total);
264 wbRate = writebackCount / cpu->numCycles;
265}
266
267template<class Impl>
268void
269DefaultIEW<Impl>::initStage()
270{
271 for (ThreadID tid = 0; tid < numThreads; tid++) {
272 toRename->iewInfo[tid].usedIQ = true;
273 toRename->iewInfo[tid].freeIQEntries =
274 instQueue.numFreeEntries(tid);
275
276 toRename->iewInfo[tid].usedLSQ = true;
277 toRename->iewInfo[tid].freeLSQEntries =
278 ldstQueue.numFreeEntries(tid);
279 }
280
281 cpu->activateStage(O3CPU::IEWIdx);
282}
283
284template<class Impl>
285void
286DefaultIEW<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr)
287{
288 timeBuffer = tb_ptr;
289
290 // Setup wire to read information from time buffer, from commit.
291 fromCommit = timeBuffer->getWire(-commitToIEWDelay);
292
293 // Setup wire to write information back to previous stages.
294 toRename = timeBuffer->getWire(0);
295
296 toFetch = timeBuffer->getWire(0);
297
298 // Instruction queue also needs main time buffer.
299 instQueue.setTimeBuffer(tb_ptr);
300}
301
302template<class Impl>
303void
304DefaultIEW<Impl>::setRenameQueue(TimeBuffer<RenameStruct> *rq_ptr)
305{
306 renameQueue = rq_ptr;
307
308 // Setup wire to read information from rename queue.
309 fromRename = renameQueue->getWire(-renameToIEWDelay);
310}
311
312template<class Impl>
313void
314DefaultIEW<Impl>::setIEWQueue(TimeBuffer<IEWStruct> *iq_ptr)
315{
316 iewQueue = iq_ptr;
317
318 // Setup wire to write instructions to commit.
319 toCommit = iewQueue->getWire(0);
320}
321
322template<class Impl>
323void
324DefaultIEW<Impl>::setActiveThreads(list<ThreadID> *at_ptr)
325{
326 activeThreads = at_ptr;
327
328 ldstQueue.setActiveThreads(at_ptr);
329 instQueue.setActiveThreads(at_ptr);
330}
331
332template<class Impl>
333void
334DefaultIEW<Impl>::setScoreboard(Scoreboard *sb_ptr)
335{
336 scoreboard = sb_ptr;
337}
338
339template <class Impl>
340bool
341DefaultIEW<Impl>::drain()
342{
343 // IEW is ready to drain at any time.
344 cpu->signalDrained();
345 return true;
346}
347
348template <class Impl>
349void
350DefaultIEW<Impl>::resume()
351{
352}
353
354template <class Impl>
355void
356DefaultIEW<Impl>::switchOut()
357{
358 // Clear any state.
359 switchedOut = true;
360 assert(insts[0].empty());
361 assert(skidBuffer[0].empty());
362
363 instQueue.switchOut();
364 ldstQueue.switchOut();
365 fuPool->switchOut();
366
367 for (ThreadID tid = 0; tid < numThreads; tid++) {
368 while (!insts[tid].empty())
369 insts[tid].pop();
370 while (!skidBuffer[tid].empty())
371 skidBuffer[tid].pop();
372 }
373}
374
375template <class Impl>
376void
377DefaultIEW<Impl>::takeOverFrom()
378{
379 // Reset all state.
380 _status = Active;
381 exeStatus = Running;
382 wbStatus = Idle;
383 switchedOut = false;
384
385 instQueue.takeOverFrom();
386 ldstQueue.takeOverFrom();
387 fuPool->takeOverFrom();
388
389 initStage();
390 cpu->activityThisCycle();
391
392 for (ThreadID tid = 0; tid < numThreads; tid++) {
393 dispatchStatus[tid] = Running;
394 stalls[tid].commit = false;
395 fetchRedirect[tid] = false;
396 }
397
398 updateLSQNextCycle = false;
399
400 for (int i = 0; i < issueToExecQueue.getSize(); ++i) {
401 issueToExecQueue.advance();
402 }
403}
404
405template<class Impl>
406void
407DefaultIEW<Impl>::squash(ThreadID tid)
408{
409 DPRINTF(IEW, "[tid:%i]: Squashing all instructions.\n", tid);
410
411 // Tell the IQ to start squashing.
412 instQueue.squash(tid);
413
414 // Tell the LDSTQ to start squashing.
415 ldstQueue.squash(fromCommit->commitInfo[tid].doneSeqNum, tid);
416 updatedQueues = true;
417
418 // Clear the skid buffer in case it has any data in it.
419 DPRINTF(IEW, "[tid:%i]: Removing skidbuffer instructions until [sn:%i].\n",
420 tid, fromCommit->commitInfo[tid].doneSeqNum);
421
422 while (!skidBuffer[tid].empty()) {
423 if (skidBuffer[tid].front()->isLoad() ||
424 skidBuffer[tid].front()->isStore() ) {
425 toRename->iewInfo[tid].dispatchedToLSQ++;
426 }
427
428 toRename->iewInfo[tid].dispatched++;
429
430 skidBuffer[tid].pop();
431 }
432
433 emptyRenameInsts(tid);
434}
435
436template<class Impl>
437void
438DefaultIEW<Impl>::squashDueToBranch(DynInstPtr &inst, ThreadID tid)
439{
440 DPRINTF(IEW, "[tid:%i]: Squashing from a specific instruction, PC: %#x "
441 "[sn:%i].\n", tid, inst->readPC(), inst->seqNum);
442
443 toCommit->squash[tid] = true;
444 toCommit->squashedSeqNum[tid] = inst->seqNum;
445 toCommit->mispredPC[tid] = inst->readPC();
446 toCommit->branchMispredict[tid] = true;
447
448#if ISA_HAS_DELAY_SLOT
449 int instSize = sizeof(TheISA::MachInst);
450 toCommit->branchTaken[tid] =
451 !(inst->readNextPC() + instSize == inst->readNextNPC() &&
452 (inst->readNextPC() == inst->readPC() + instSize ||
453 inst->readNextPC() == inst->readPC() + 2 * instSize));
454#else
455 toCommit->branchTaken[tid] = inst->readNextPC() !=
456 (inst->readPC() + sizeof(TheISA::MachInst));
457#endif
458 toCommit->nextPC[tid] = inst->readNextPC();
459 toCommit->nextNPC[tid] = inst->readNextNPC();
460 toCommit->nextMicroPC[tid] = inst->readNextMicroPC();
461
462 toCommit->includeSquashInst[tid] = false;
463
464 wroteToTimeBuffer = true;
465}
466
467template<class Impl>
468void
469DefaultIEW<Impl>::squashDueToMemOrder(DynInstPtr &inst, ThreadID tid)
470{
471 DPRINTF(IEW, "[tid:%i]: Squashing from a specific instruction, "
472 "PC: %#x [sn:%i].\n", tid, inst->readPC(), inst->seqNum);
473
474 toCommit->squash[tid] = true;
475 toCommit->squashedSeqNum[tid] = inst->seqNum;
476 toCommit->nextPC[tid] = inst->readNextPC();
477 toCommit->nextNPC[tid] = inst->readNextNPC();
478 toCommit->branchMispredict[tid] = false;
479
480 toCommit->includeSquashInst[tid] = false;
481
482 wroteToTimeBuffer = true;
483}
484
485template<class Impl>
486void
487DefaultIEW<Impl>::squashDueToMemBlocked(DynInstPtr &inst, ThreadID tid)
488{
489 DPRINTF(IEW, "[tid:%i]: Memory blocked, squashing load and younger insts, "
490 "PC: %#x [sn:%i].\n", tid, inst->readPC(), inst->seqNum);
491
492 toCommit->squash[tid] = true;
493 toCommit->squashedSeqNum[tid] = inst->seqNum;
494 toCommit->nextPC[tid] = inst->readPC();
495 toCommit->nextNPC[tid] = inst->readNextPC();
496 toCommit->branchMispredict[tid] = false;
497
498 // Must include the broadcasted SN in the squash.
499 toCommit->includeSquashInst[tid] = true;
500
501 ldstQueue.setLoadBlockedHandled(tid);
502
503 wroteToTimeBuffer = true;
504}
505
506template<class Impl>
507void
508DefaultIEW<Impl>::block(ThreadID tid)
509{
510 DPRINTF(IEW, "[tid:%u]: Blocking.\n", tid);
511
512 if (dispatchStatus[tid] != Blocked &&
513 dispatchStatus[tid] != Unblocking) {
514 toRename->iewBlock[tid] = true;
515 wroteToTimeBuffer = true;
516 }
517
518 // Add the current inputs to the skid buffer so they can be
519 // reprocessed when this stage unblocks.
520 skidInsert(tid);
521
522 dispatchStatus[tid] = Blocked;
523}
524
525template<class Impl>
526void
527DefaultIEW<Impl>::unblock(ThreadID tid)
528{
529 DPRINTF(IEW, "[tid:%i]: Reading instructions out of the skid "
530 "buffer %u.\n",tid, tid);
531
532 // If the skid bufffer is empty, signal back to previous stages to unblock.
533 // Also switch status to running.
534 if (skidBuffer[tid].empty()) {
535 toRename->iewUnblock[tid] = true;
536 wroteToTimeBuffer = true;
537 DPRINTF(IEW, "[tid:%i]: Done unblocking.\n",tid);
538 dispatchStatus[tid] = Running;
539 }
540}
541
542template<class Impl>
543void
544DefaultIEW<Impl>::wakeDependents(DynInstPtr &inst)
545{
546 instQueue.wakeDependents(inst);
547}
548
549template<class Impl>
550void
551DefaultIEW<Impl>::rescheduleMemInst(DynInstPtr &inst)
552{
553 instQueue.rescheduleMemInst(inst);
554}
555
556template<class Impl>
557void
558DefaultIEW<Impl>::replayMemInst(DynInstPtr &inst)
559{
560 instQueue.replayMemInst(inst);
561}
562
563template<class Impl>
564void
565DefaultIEW<Impl>::instToCommit(DynInstPtr &inst)
566{
567 // This function should not be called after writebackInsts in a
568 // single cycle. That will cause problems with an instruction
569 // being added to the queue to commit without being processed by
570 // writebackInsts prior to being sent to commit.
571
572 // First check the time slot that this instruction will write
573 // to. If there are free write ports at the time, then go ahead
574 // and write the instruction to that time. If there are not,
575 // keep looking back to see where's the first time there's a
576 // free slot.
577 while ((*iewQueue)[wbCycle].insts[wbNumInst]) {
578 ++wbNumInst;
579 if (wbNumInst == wbWidth) {
580 ++wbCycle;
581 wbNumInst = 0;
582 }
583
584 assert((wbCycle * wbWidth + wbNumInst) <= wbMax);
585 }
586
587 DPRINTF(IEW, "Current wb cycle: %i, width: %i, numInst: %i\nwbActual:%i\n",
588 wbCycle, wbWidth, wbNumInst, wbCycle * wbWidth + wbNumInst);
589 // Add finished instruction to queue to commit.
590 (*iewQueue)[wbCycle].insts[wbNumInst] = inst;
591 (*iewQueue)[wbCycle].size++;
592}
593
594template <class Impl>
595unsigned
596DefaultIEW<Impl>::validInstsFromRename()
597{
598 unsigned inst_count = 0;
599
600 for (int i=0; i<fromRename->size; i++) {
601 if (!fromRename->insts[i]->isSquashed())
602 inst_count++;
603 }
604
605 return inst_count;
606}
607
608template<class Impl>
609void
610DefaultIEW<Impl>::skidInsert(ThreadID tid)
611{
612 DynInstPtr inst = NULL;
613
614 while (!insts[tid].empty()) {
615 inst = insts[tid].front();
616
617 insts[tid].pop();
618
619 DPRINTF(Decode,"[tid:%i]: Inserting [sn:%lli] PC:%#x into "
620 "dispatch skidBuffer %i\n",tid, inst->seqNum,
621 inst->readPC(),tid);
622
623 skidBuffer[tid].push(inst);
624 }
625
626 assert(skidBuffer[tid].size() <= skidBufferMax &&
627 "Skidbuffer Exceeded Max Size");
628}
629
630template<class Impl>
631int
632DefaultIEW<Impl>::skidCount()
633{
634 int max=0;
635
636 list<ThreadID>::iterator threads = activeThreads->begin();
637 list<ThreadID>::iterator end = activeThreads->end();
638
639 while (threads != end) {
640 ThreadID tid = *threads++;
641 unsigned thread_count = skidBuffer[tid].size();
642 if (max < thread_count)
643 max = thread_count;
644 }
645
646 return max;
647}
648
649template<class Impl>
650bool
651DefaultIEW<Impl>::skidsEmpty()
652{
653 list<ThreadID>::iterator threads = activeThreads->begin();
654 list<ThreadID>::iterator end = activeThreads->end();
655
656 while (threads != end) {
657 ThreadID tid = *threads++;
658
659 if (!skidBuffer[tid].empty())
660 return false;
661 }
662
663 return true;
664}
665
666template <class Impl>
667void
668DefaultIEW<Impl>::updateStatus()
669{
670 bool any_unblocking = false;
671
672 list<ThreadID>::iterator threads = activeThreads->begin();
673 list<ThreadID>::iterator end = activeThreads->end();
674
675 while (threads != end) {
676 ThreadID tid = *threads++;
677
678 if (dispatchStatus[tid] == Unblocking) {
679 any_unblocking = true;
680 break;
681 }
682 }
683
684 // If there are no ready instructions waiting to be scheduled by the IQ,
685 // and there's no stores waiting to write back, and dispatch is not
686 // unblocking, then there is no internal activity for the IEW stage.
687 if (_status == Active && !instQueue.hasReadyInsts() &&
688 !ldstQueue.willWB() && !any_unblocking) {
689 DPRINTF(IEW, "IEW switching to idle\n");
690
691 deactivateStage();
692
693 _status = Inactive;
694 } else if (_status == Inactive && (instQueue.hasReadyInsts() ||
695 ldstQueue.willWB() ||
696 any_unblocking)) {
697 // Otherwise there is internal activity. Set to active.
698 DPRINTF(IEW, "IEW switching to active\n");
699
700 activateStage();
701
702 _status = Active;
703 }
704}
705
706template <class Impl>
707void
708DefaultIEW<Impl>::resetEntries()
709{
710 instQueue.resetEntries();
711 ldstQueue.resetEntries();
712}
713
714template <class Impl>
715void
716DefaultIEW<Impl>::readStallSignals(ThreadID tid)
717{
718 if (fromCommit->commitBlock[tid]) {
719 stalls[tid].commit = true;
720 }
721
722 if (fromCommit->commitUnblock[tid]) {
723 assert(stalls[tid].commit);
724 stalls[tid].commit = false;
725 }
726}
727
728template <class Impl>
729bool
730DefaultIEW<Impl>::checkStall(ThreadID tid)
731{
732 bool ret_val(false);
733
734 if (stalls[tid].commit) {
735 DPRINTF(IEW,"[tid:%i]: Stall from Commit stage detected.\n",tid);
736 ret_val = true;
737 } else if (instQueue.isFull(tid)) {
738 DPRINTF(IEW,"[tid:%i]: Stall: IQ is full.\n",tid);
739 ret_val = true;
740 } else if (ldstQueue.isFull(tid)) {
741 DPRINTF(IEW,"[tid:%i]: Stall: LSQ is full\n",tid);
742
743 if (ldstQueue.numLoads(tid) > 0 ) {
744
745 DPRINTF(IEW,"[tid:%i]: LSQ oldest load: [sn:%i] \n",
746 tid,ldstQueue.getLoadHeadSeqNum(tid));
747 }
748
749 if (ldstQueue.numStores(tid) > 0) {
750
751 DPRINTF(IEW,"[tid:%i]: LSQ oldest store: [sn:%i] \n",
752 tid,ldstQueue.getStoreHeadSeqNum(tid));
753 }
754
755 ret_val = true;
756 } else if (ldstQueue.isStalled(tid)) {
757 DPRINTF(IEW,"[tid:%i]: Stall: LSQ stall detected.\n",tid);
758 ret_val = true;
759 }
760
761 return ret_val;
762}
763
764template <class Impl>
765void
766DefaultIEW<Impl>::checkSignalsAndUpdate(ThreadID tid)
767{
768 // Check if there's a squash signal, squash if there is
769 // Check stall signals, block if there is.
770 // If status was Blocked
771 // if so then go to unblocking
772 // If status was Squashing
773 // check if squashing is not high. Switch to running this cycle.
774
775 readStallSignals(tid);
776
777 if (fromCommit->commitInfo[tid].squash) {
778 squash(tid);
779
780 if (dispatchStatus[tid] == Blocked ||
781 dispatchStatus[tid] == Unblocking) {
782 toRename->iewUnblock[tid] = true;
783 wroteToTimeBuffer = true;
784 }
785
786 dispatchStatus[tid] = Squashing;
787
788 fetchRedirect[tid] = false;
789 return;
790 }
791
792 if (fromCommit->commitInfo[tid].robSquashing) {
793 DPRINTF(IEW, "[tid:%i]: ROB is still squashing.\n", tid);
794
795 dispatchStatus[tid] = Squashing;
796
797 emptyRenameInsts(tid);
798 wroteToTimeBuffer = true;
799 return;
800 }
801
802 if (checkStall(tid)) {
803 block(tid);
804 dispatchStatus[tid] = Blocked;
805 return;
806 }
807
808 if (dispatchStatus[tid] == Blocked) {
809 // Status from previous cycle was blocked, but there are no more stall
810 // conditions. Switch over to unblocking.
811 DPRINTF(IEW, "[tid:%i]: Done blocking, switching to unblocking.\n",
812 tid);
813
814 dispatchStatus[tid] = Unblocking;
815
816 unblock(tid);
817
818 return;
819 }
820
821 if (dispatchStatus[tid] == Squashing) {
822 // Switch status to running if rename isn't being told to block or
823 // squash this cycle.
824 DPRINTF(IEW, "[tid:%i]: Done squashing, switching to running.\n",
825 tid);
826
827 dispatchStatus[tid] = Running;
828
829 return;
830 }
831}
832
833template <class Impl>
834void
835DefaultIEW<Impl>::sortInsts()
836{
837 int insts_from_rename = fromRename->size;
838#ifdef DEBUG
839 for (ThreadID tid = 0; tid < numThreads; tid++)
840 assert(insts[tid].empty());
841#endif
842 for (int i = 0; i < insts_from_rename; ++i) {
843 insts[fromRename->insts[i]->threadNumber].push(fromRename->insts[i]);
844 }
845}
846
847template <class Impl>
848void
849DefaultIEW<Impl>::emptyRenameInsts(ThreadID tid)
850{
851 DPRINTF(IEW, "[tid:%i]: Removing incoming rename instructions\n", tid);
852
853 while (!insts[tid].empty()) {
854
855 if (insts[tid].front()->isLoad() ||
856 insts[tid].front()->isStore() ) {
857 toRename->iewInfo[tid].dispatchedToLSQ++;
858 }
859
860 toRename->iewInfo[tid].dispatched++;
861
862 insts[tid].pop();
863 }
864}
865
866template <class Impl>
867void
868DefaultIEW<Impl>::wakeCPU()
869{
870 cpu->wakeCPU();
871}
872
873template <class Impl>
874void
875DefaultIEW<Impl>::activityThisCycle()
876{
877 DPRINTF(Activity, "Activity this cycle.\n");
878 cpu->activityThisCycle();
879}
880
881template <class Impl>
882inline void
883DefaultIEW<Impl>::activateStage()
884{
885 DPRINTF(Activity, "Activating stage.\n");
886 cpu->activateStage(O3CPU::IEWIdx);
887}
888
889template <class Impl>
890inline void
891DefaultIEW<Impl>::deactivateStage()
892{
893 DPRINTF(Activity, "Deactivating stage.\n");
894 cpu->deactivateStage(O3CPU::IEWIdx);
895}
896
897template<class Impl>
898void
899DefaultIEW<Impl>::dispatch(ThreadID tid)
900{
901 // If status is Running or idle,
902 // call dispatchInsts()
903 // If status is Unblocking,
904 // buffer any instructions coming from rename
905 // continue trying to empty skid buffer
906 // check if stall conditions have passed
907
908 if (dispatchStatus[tid] == Blocked) {
909 ++iewBlockCycles;
910
911 } else if (dispatchStatus[tid] == Squashing) {
912 ++iewSquashCycles;
913 }
914
915 // Dispatch should try to dispatch as many instructions as its bandwidth
916 // will allow, as long as it is not currently blocked.
917 if (dispatchStatus[tid] == Running ||
918 dispatchStatus[tid] == Idle) {
919 DPRINTF(IEW, "[tid:%i] Not blocked, so attempting to run "
920 "dispatch.\n", tid);
921
922 dispatchInsts(tid);
923 } else if (dispatchStatus[tid] == Unblocking) {
924 // Make sure that the skid buffer has something in it if the
925 // status is unblocking.
926 assert(!skidsEmpty());
927
928 // If the status was unblocking, then instructions from the skid
929 // buffer were used. Remove those instructions and handle
930 // the rest of unblocking.
931 dispatchInsts(tid);
932
933 ++iewUnblockCycles;
934
935 if (validInstsFromRename()) {
936 // Add the current inputs to the skid buffer so they can be
937 // reprocessed when this stage unblocks.
938 skidInsert(tid);
939 }
940
941 unblock(tid);
942 }
943}
944
945template <class Impl>
946void
947DefaultIEW<Impl>::dispatchInsts(ThreadID tid)
948{
949 // Obtain instructions from skid buffer if unblocking, or queue from rename
950 // otherwise.
951 std::queue<DynInstPtr> &insts_to_dispatch =
952 dispatchStatus[tid] == Unblocking ?
953 skidBuffer[tid] : insts[tid];
954
955 int insts_to_add = insts_to_dispatch.size();
956
957 DynInstPtr inst;
958 bool add_to_iq = false;
959 int dis_num_inst = 0;
960
961 // Loop through the instructions, putting them in the instruction
962 // queue.
963 for ( ; dis_num_inst < insts_to_add &&
964 dis_num_inst < dispatchWidth;
965 ++dis_num_inst)
966 {
967 inst = insts_to_dispatch.front();
968
969 if (dispatchStatus[tid] == Unblocking) {
970 DPRINTF(IEW, "[tid:%i]: Issue: Examining instruction from skid "
971 "buffer\n", tid);
972 }
973
974 // Make sure there's a valid instruction there.
975 assert(inst);
976
977 DPRINTF(IEW, "[tid:%i]: Issue: Adding PC %#x [sn:%lli] [tid:%i] to "
978 "IQ.\n",
979 tid, inst->readPC(), inst->seqNum, inst->threadNumber);
980
981 // Be sure to mark these instructions as ready so that the
982 // commit stage can go ahead and execute them, and mark
983 // them as issued so the IQ doesn't reprocess them.
984
985 // Check for squashed instructions.
986 if (inst->isSquashed()) {
987 DPRINTF(IEW, "[tid:%i]: Issue: Squashed instruction encountered, "
988 "not adding to IQ.\n", tid);
989
990 ++iewDispSquashedInsts;
991
992 insts_to_dispatch.pop();
993
994 //Tell Rename That An Instruction has been processed
995 if (inst->isLoad() || inst->isStore()) {
996 toRename->iewInfo[tid].dispatchedToLSQ++;
997 }
998 toRename->iewInfo[tid].dispatched++;
999
1000 continue;
1001 }
1002
1003 // Check for full conditions.
1004 if (instQueue.isFull(tid)) {
1005 DPRINTF(IEW, "[tid:%i]: Issue: IQ has become full.\n", tid);
1006
1007 // Call function to start blocking.
1008 block(tid);
1009
1010 // Set unblock to false. Special case where we are using
1011 // skidbuffer (unblocking) instructions but then we still
1012 // get full in the IQ.
1013 toRename->iewUnblock[tid] = false;
1014
1015 ++iewIQFullEvents;
1016 break;
1017 } else if (ldstQueue.isFull(tid)) {
1018 DPRINTF(IEW, "[tid:%i]: Issue: LSQ has become full.\n",tid);
1019
1020 // Call function to start blocking.
1021 block(tid);
1022
1023 // Set unblock to false. Special case where we are using
1024 // skidbuffer (unblocking) instructions but then we still
1025 // get full in the IQ.
1026 toRename->iewUnblock[tid] = false;
1027
1028 ++iewLSQFullEvents;
1029 break;
1030 }
1031
1032 // Otherwise issue the instruction just fine.
1033 if (inst->isLoad()) {
1034 DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1035 "encountered, adding to LSQ.\n", tid);
1036
1037 // Reserve a spot in the load store queue for this
1038 // memory access.
1039 ldstQueue.insertLoad(inst);
1040
1041 ++iewDispLoadInsts;
1042
1043 add_to_iq = true;
1044
1045 toRename->iewInfo[tid].dispatchedToLSQ++;
1046 } else if (inst->isStore()) {
1047 DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1048 "encountered, adding to LSQ.\n", tid);
1049
1050 ldstQueue.insertStore(inst);
1051
1052 ++iewDispStoreInsts;
1053
1054 if (inst->isStoreConditional()) {
1055 // Store conditionals need to be set as "canCommit()"
1056 // so that commit can process them when they reach the
1057 // head of commit.
1058 // @todo: This is somewhat specific to Alpha.
1059 inst->setCanCommit();
1060 instQueue.insertNonSpec(inst);
1061 add_to_iq = false;
1062
1063 ++iewDispNonSpecInsts;
1064 } else {
1065 add_to_iq = true;
1066 }
1067
1068 toRename->iewInfo[tid].dispatchedToLSQ++;
1069 } else if (inst->isMemBarrier() || inst->isWriteBarrier()) {
1070 // Same as non-speculative stores.
1071 inst->setCanCommit();
1072 instQueue.insertBarrier(inst);
1073 add_to_iq = false;
1074 } else if (inst->isNop()) {
1075 DPRINTF(IEW, "[tid:%i]: Issue: Nop instruction encountered, "
1076 "skipping.\n", tid);
1077
1078 inst->setIssued();
1079 inst->setExecuted();
1080 inst->setCanCommit();
1081
1082 instQueue.recordProducer(inst);
1083
1084 iewExecutedNop[tid]++;
1085
1086 add_to_iq = false;
1087 } else if (inst->isExecuted()) {
1088 assert(0 && "Instruction shouldn't be executed.\n");
1089 DPRINTF(IEW, "Issue: Executed branch encountered, "
1090 "skipping.\n");
1091
1092 inst->setIssued();
1093 inst->setCanCommit();
1094
1095 instQueue.recordProducer(inst);
1096
1097 add_to_iq = false;
1098 } else {
1099 add_to_iq = true;
1100 }
1101 if (inst->isNonSpeculative()) {
1102 DPRINTF(IEW, "[tid:%i]: Issue: Nonspeculative instruction "
1103 "encountered, skipping.\n", tid);
1104
1105 // Same as non-speculative stores.
1106 inst->setCanCommit();
1107
1108 // Specifically insert it as nonspeculative.
1109 instQueue.insertNonSpec(inst);
1110
1111 ++iewDispNonSpecInsts;
1112
1113 add_to_iq = false;
1114 }
1115
1116 // If the instruction queue is not full, then add the
1117 // instruction.
1118 if (add_to_iq) {
1119 instQueue.insert(inst);
1120 }
1121
1122 insts_to_dispatch.pop();
1123
1124 toRename->iewInfo[tid].dispatched++;
1125
1126 ++iewDispatchedInsts;
1127 }
1128
1129 if (!insts_to_dispatch.empty()) {
1130 DPRINTF(IEW,"[tid:%i]: Issue: Bandwidth Full. Blocking.\n", tid);
1131 block(tid);
1132 toRename->iewUnblock[tid] = false;
1133 }
1134
1135 if (dispatchStatus[tid] == Idle && dis_num_inst) {
1136 dispatchStatus[tid] = Running;
1137
1138 updatedQueues = true;
1139 }
1140
1141 dis_num_inst = 0;
1142}
1143
1144template <class Impl>
1145void
1146DefaultIEW<Impl>::printAvailableInsts()
1147{
1148 int inst = 0;
1149
1150 std::cout << "Available Instructions: ";
1151
1152 while (fromIssue->insts[inst]) {
1153
1154 if (inst%3==0) std::cout << "\n\t";
1155
1156 std::cout << "PC: " << fromIssue->insts[inst]->readPC()
1157 << " TN: " << fromIssue->insts[inst]->threadNumber
1158 << " SN: " << fromIssue->insts[inst]->seqNum << " | ";
1159
1160 inst++;
1161
1162 }
1163
1164 std::cout << "\n";
1165}
1166
1167template <class Impl>
1168void
1169DefaultIEW<Impl>::executeInsts()
1170{
1171 wbNumInst = 0;
1172 wbCycle = 0;
1173
1174 list<ThreadID>::iterator threads = activeThreads->begin();
1175 list<ThreadID>::iterator end = activeThreads->end();
1176
1177 while (threads != end) {
1178 ThreadID tid = *threads++;
1179 fetchRedirect[tid] = false;
1180 }
1181
1182 // Uncomment this if you want to see all available instructions.
1183// printAvailableInsts();
1184
1185 // Execute/writeback any instructions that are available.
1186 int insts_to_execute = fromIssue->size;
1187 int inst_num = 0;
1188 for (; inst_num < insts_to_execute;
1189 ++inst_num) {
1190
1191 DPRINTF(IEW, "Execute: Executing instructions from IQ.\n");
1192
1193 DynInstPtr inst = instQueue.getInstToExecute();
1194
1195 DPRINTF(IEW, "Execute: Processing PC %#x, [tid:%i] [sn:%i].\n",
1196 inst->readPC(), inst->threadNumber,inst->seqNum);
1197
1198 // Check if the instruction is squashed; if so then skip it
1199 if (inst->isSquashed()) {
1200 DPRINTF(IEW, "Execute: Instruction was squashed.\n");
1201
1202 // Consider this instruction executed so that commit can go
1203 // ahead and retire the instruction.
1204 inst->setExecuted();
1205
1206 // Not sure if I should set this here or just let commit try to
1207 // commit any squashed instructions. I like the latter a bit more.
1208 inst->setCanCommit();
1209
1210 ++iewExecSquashedInsts;
1211
1212 decrWb(inst->seqNum);
1213 continue;
1214 }
1215
1216 Fault fault = NoFault;
1217
1218 // Execute instruction.
1219 // Note that if the instruction faults, it will be handled
1220 // at the commit stage.
1221 if (inst->isMemRef() &&
1222 (!inst->isDataPrefetch() && !inst->isInstPrefetch())) {
1223 DPRINTF(IEW, "Execute: Calculating address for memory "
1224 "reference.\n");
1225
1226 // Tell the LDSTQ to execute this instruction (if it is a load).
1227 if (inst->isLoad()) {
1228 // Loads will mark themselves as executed, and their writeback
1229 // event adds the instruction to the queue to commit
1230 fault = ldstQueue.executeLoad(inst);
1231 } else if (inst->isStore()) {
1232 fault = ldstQueue.executeStore(inst);
1233
1234 // If the store had a fault then it may not have a mem req
1235 if (!inst->isStoreConditional() && fault == NoFault) {
1236 inst->setExecuted();
1237
1238 instToCommit(inst);
1239 } else if (fault != NoFault) {
1240 // If the instruction faulted, then we need to send it along to commit
1241 // without the instruction completing.
1242 DPRINTF(IEW, "Store has fault %s! [sn:%lli]\n",
1243 fault->name(), inst->seqNum);
1244
1245 // Send this instruction to commit, also make sure iew stage
1246 // realizes there is activity.
1247 inst->setExecuted();
1248
1249 instToCommit(inst);
1250 activityThisCycle();
1251 }
1252
1253 // Store conditionals will mark themselves as
1254 // executed, and their writeback event will add the
1255 // instruction to the queue to commit.
1256 } else {
1257 panic("Unexpected memory type!\n");
1258 }
1259
1260 } else {
1261 inst->execute();
1262
1263 inst->setExecuted();
1264
1265 instToCommit(inst);
1266 }
1267
1268 updateExeInstStats(inst);
1269
1270 // Check if branch prediction was correct, if not then we need
1271 // to tell commit to squash in flight instructions. Only
1272 // handle this if there hasn't already been something that
1273 // redirects fetch in this group of instructions.
1274
1275 // This probably needs to prioritize the redirects if a different
1276 // scheduler is used. Currently the scheduler schedules the oldest
1277 // instruction first, so the branch resolution order will be correct.
1278 ThreadID tid = inst->threadNumber;
1279
1280 if (!fetchRedirect[tid] ||
1281 toCommit->squashedSeqNum[tid] > inst->seqNum) {
1282
1283 if (inst->mispredicted()) {
1284 fetchRedirect[tid] = true;
1285
1286 DPRINTF(IEW, "Execute: Branch mispredict detected.\n");
1287 DPRINTF(IEW, "Predicted target was PC:%#x, NPC:%#x.\n",
1288 inst->readPredPC(), inst->readPredNPC());
1289 DPRINTF(IEW, "Execute: Redirecting fetch to PC: %#x,"
1290 " NPC: %#x.\n", inst->readNextPC(),
1291 inst->readNextNPC());
1292 // If incorrect, then signal the ROB that it must be squashed.
1293 squashDueToBranch(inst, tid);
1294
1295 if (inst->readPredTaken()) {
1296 predictedTakenIncorrect++;
1297 } else {
1298 predictedNotTakenIncorrect++;
1299 }
1300 } else if (ldstQueue.violation(tid)) {
1301 assert(inst->isMemRef());
1302 // If there was an ordering violation, then get the
1303 // DynInst that caused the violation. Note that this
1304 // clears the violation signal.
1305 DynInstPtr violator;
1306 violator = ldstQueue.getMemDepViolator(tid);
1307
1308 DPRINTF(IEW, "LDSTQ detected a violation. Violator PC: "
1309 "%#x, inst PC: %#x. Addr is: %#x.\n",
1310 violator->readPC(), inst->readPC(), inst->physEffAddr);
1311
1312 // Ensure the violating instruction is older than
1313 // current squash
1314/* if (fetchRedirect[tid] &&
1315 violator->seqNum >= toCommit->squashedSeqNum[tid] + 1)
1316 continue;
1317*/
1318 fetchRedirect[tid] = true;
1319
1320 // Tell the instruction queue that a violation has occured.
1321 instQueue.violation(inst, violator);
1322
1323 // Squash.
1324 squashDueToMemOrder(inst,tid);
1325
1326 ++memOrderViolationEvents;
1327 } else if (ldstQueue.loadBlocked(tid) &&
1328 !ldstQueue.isLoadBlockedHandled(tid)) {
1329 fetchRedirect[tid] = true;
1330
1331 DPRINTF(IEW, "Load operation couldn't execute because the "
1332 "memory system is blocked. PC: %#x [sn:%lli]\n",
1333 inst->readPC(), inst->seqNum);
1334
1335 squashDueToMemBlocked(inst, tid);
1336 }
1337 } else {
1338 // Reset any state associated with redirects that will not
1339 // be used.
1340 if (ldstQueue.violation(tid)) {
1341 assert(inst->isMemRef());
1342
1343 DynInstPtr 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 DPRINTF(IEW, "Violation will not be handled because "
1349 "already squashing\n");
1350
1351 ++memOrderViolationEvents;
1352 }
1353 if (ldstQueue.loadBlocked(tid) &&
1354 !ldstQueue.isLoadBlockedHandled(tid)) {
1355 DPRINTF(IEW, "Load operation couldn't execute because the "
1356 "memory system is blocked. PC: %#x [sn:%lli]\n",
1357 inst->readPC(), inst->seqNum);
1358 DPRINTF(IEW, "Blocked load will not be handled because "
1359 "already squashing\n");
1360
1361 ldstQueue.setLoadBlockedHandled(tid);
1362 }
1363
1364 }
1365 }
1366
1367 // Update and record activity if we processed any instructions.
1368 if (inst_num) {
1369 if (exeStatus == Idle) {
1370 exeStatus = Running;
1371 }
1372
1373 updatedQueues = true;
1374
1375 cpu->activityThisCycle();
1376 }
1377
1378 // Need to reset this in case a writeback event needs to write into the
1379 // iew queue. That way the writeback event will write into the correct
1380 // spot in the queue.
1381 wbNumInst = 0;
1382}
1383
1384template <class Impl>
1385void
1386DefaultIEW<Impl>::writebackInsts()
1387{
1388 // Loop through the head of the time buffer and wake any
1389 // dependents. These instructions are about to write back. Also
1390 // mark scoreboard that this instruction is finally complete.
1391 // Either have IEW have direct access to scoreboard, or have this
1392 // as part of backwards communication.
1393 for (int inst_num = 0; inst_num < wbWidth &&
1394 toCommit->insts[inst_num]; inst_num++) {
1395 DynInstPtr inst = toCommit->insts[inst_num];
1396 ThreadID tid = inst->threadNumber;
1397
1398 DPRINTF(IEW, "Sending instructions to commit, [sn:%lli] PC %#x.\n",
1399 inst->seqNum, inst->readPC());
1400
1401 iewInstsToCommit[tid]++;
1402
1403 // Some instructions will be sent to commit without having
1404 // executed because they need commit to handle them.
1405 // E.g. Uncached loads have not actually executed when they
1406 // are first sent to commit. Instead commit must tell the LSQ
1407 // when it's ready to execute the uncached load.
1408 if (!inst->isSquashed() && inst->isExecuted() && inst->getFault() == NoFault) {
1409 int dependents = instQueue.wakeDependents(inst);
1410
1411 for (int i = 0; i < inst->numDestRegs(); i++) {
1412 //mark as Ready
1413 DPRINTF(IEW,"Setting Destination Register %i\n",
1414 inst->renamedDestRegIdx(i));
1415 scoreboard->setReg(inst->renamedDestRegIdx(i));
1416 }
1417
1418 if (dependents) {
1419 producerInst[tid]++;
1420 consumerInst[tid]+= dependents;
1421 }
1422 writebackCount[tid]++;
1423 }
1424
1425 decrWb(inst->seqNum);
1426 }
1427}
1428
1429template<class Impl>
1430void
1431DefaultIEW<Impl>::tick()
1432{
1433 wbNumInst = 0;
1434 wbCycle = 0;
1435
1436 wroteToTimeBuffer = false;
1437 updatedQueues = false;
1438
1439 sortInsts();
1440
1441 // Free function units marked as being freed this cycle.
1442 fuPool->processFreeUnits();
1443
1444 list<ThreadID>::iterator threads = activeThreads->begin();
1445 list<ThreadID>::iterator end = activeThreads->end();
1446
1447 // Check stall and squash signals, dispatch any instructions.
1448 while (threads != end) {
1449 ThreadID tid = *threads++;
1450
1451 DPRINTF(IEW,"Issue: Processing [tid:%i]\n",tid);
1452
1453 checkSignalsAndUpdate(tid);
1454 dispatch(tid);
1455 }
1456
1457 if (exeStatus != Squashing) {
1458 executeInsts();
1459
1460 writebackInsts();
1461
1462 // Have the instruction queue try to schedule any ready instructions.
1463 // (In actuality, this scheduling is for instructions that will
1464 // be executed next cycle.)
1465 instQueue.scheduleReadyInsts();
1466
1467 // Also should advance its own time buffers if the stage ran.
1468 // Not the best place for it, but this works (hopefully).
1469 issueToExecQueue.advance();
1470 }
1471
1472 bool broadcast_free_entries = false;
1473
1474 if (updatedQueues || exeStatus == Running || updateLSQNextCycle) {
1475 exeStatus = Idle;
1476 updateLSQNextCycle = false;
1477
1478 broadcast_free_entries = true;
1479 }
1480
1481 // Writeback any stores using any leftover bandwidth.
1482 ldstQueue.writebackStores();
1483
1484 // Check the committed load/store signals to see if there's a load
1485 // or store to commit. Also check if it's being told to execute a
1486 // nonspeculative instruction.
1487 // This is pretty inefficient...
1488
1489 threads = activeThreads->begin();
1490 while (threads != end) {
1491 ThreadID tid = (*threads++);
1492
1493 DPRINTF(IEW,"Processing [tid:%i]\n",tid);
1494
1495 // Update structures based on instructions committed.
1496 if (fromCommit->commitInfo[tid].doneSeqNum != 0 &&
1497 !fromCommit->commitInfo[tid].squash &&
1498 !fromCommit->commitInfo[tid].robSquashing) {
1499
1500 ldstQueue.commitStores(fromCommit->commitInfo[tid].doneSeqNum,tid);
1501
1502 ldstQueue.commitLoads(fromCommit->commitInfo[tid].doneSeqNum,tid);
1503
1504 updateLSQNextCycle = true;
1505 instQueue.commit(fromCommit->commitInfo[tid].doneSeqNum,tid);
1506 }
1507
1508 if (fromCommit->commitInfo[tid].nonSpecSeqNum != 0) {
1509
1510 //DPRINTF(IEW,"NonspecInst from thread %i",tid);
1511 if (fromCommit->commitInfo[tid].uncached) {
1512 instQueue.replayMemInst(fromCommit->commitInfo[tid].uncachedLoad);
1513 fromCommit->commitInfo[tid].uncachedLoad->setAtCommit();
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 ThreadID tid = inst->threadNumber;
1558
1559 //
1560 // Pick off the software prefetches
1561 //
1562#ifdef TARGET_ALPHA
1563 if (inst->isDataPrefetch())
1564 iewExecutedSwp[tid]++;
1565 else
1566 iewIewExecutedcutedInsts++;
1567#else
1568 iewExecutedInsts++;
1569#endif
1570
1571 //
1572 // Control operations
1573 //
1574 if (inst->isControl())
1575 iewExecutedBranches[tid]++;
1576
1577 //
1578 // Memory operations
1579 //
1580 if (inst->isMemRef()) {
1581 iewExecutedRefs[tid]++;
1582
1583 if (inst->isLoad()) {
1584 iewExecLoadInsts[tid]++;
1585 }
1586 }
1587}
| 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// printAvailableInsts();
1196
1197 // Execute/writeback any instructions that are available.
1198 int insts_to_execute = fromIssue->size;
1199 int inst_num = 0;
1200 for (; inst_num < insts_to_execute;
1201 ++inst_num) {
1202
1203 DPRINTF(IEW, "Execute: Executing instructions from IQ.\n");
1204
1205 DynInstPtr inst = instQueue.getInstToExecute();
1206
1207 DPRINTF(IEW, "Execute: Processing PC %#x, [tid:%i] [sn:%i].\n",
1208 inst->readPC(), inst->threadNumber,inst->seqNum);
1209
1210 // Check if the instruction is squashed; if so then skip it
1211 if (inst->isSquashed()) {
1212 DPRINTF(IEW, "Execute: Instruction was squashed.\n");
1213
1214 // Consider this instruction executed so that commit can go
1215 // ahead and retire the instruction.
1216 inst->setExecuted();
1217
1218 // Not sure if I should set this here or just let commit try to
1219 // commit any squashed instructions. I like the latter a bit more.
1220 inst->setCanCommit();
1221
1222 ++iewExecSquashedInsts;
1223
1224 decrWb(inst->seqNum);
1225 continue;
1226 }
1227
1228 Fault fault = NoFault;
1229
1230 // Execute instruction.
1231 // Note that if the instruction faults, it will be handled
1232 // at the commit stage.
1233 if (inst->isMemRef() &&
1234 (!inst->isDataPrefetch() && !inst->isInstPrefetch())) {
1235 DPRINTF(IEW, "Execute: Calculating address for memory "
1236 "reference.\n");
1237
1238 // Tell the LDSTQ to execute this instruction (if it is a load).
1239 if (inst->isLoad()) {
1240 // Loads will mark themselves as executed, and their writeback
1241 // event adds the instruction to the queue to commit
1242 fault = ldstQueue.executeLoad(inst);
1243 } else if (inst->isStore()) {
1244 fault = ldstQueue.executeStore(inst);
1245
1246 // If the store had a fault then it may not have a mem req
1247 if (!inst->isStoreConditional() && fault == NoFault) {
1248 inst->setExecuted();
1249
1250 instToCommit(inst);
1251 } else if (fault != NoFault) {
1252 // If the instruction faulted, then we need to send it along to commit
1253 // without the instruction completing.
1254 DPRINTF(IEW, "Store has fault %s! [sn:%lli]\n",
1255 fault->name(), inst->seqNum);
1256
1257 // Send this instruction to commit, also make sure iew stage
1258 // realizes there is activity.
1259 inst->setExecuted();
1260
1261 instToCommit(inst);
1262 activityThisCycle();
1263 }
1264
1265 // Store conditionals will mark themselves as
1266 // executed, and their writeback event will add the
1267 // instruction to the queue to commit.
1268 } else {
1269 panic("Unexpected memory type!\n");
1270 }
1271
1272 } else {
1273 inst->execute();
1274
1275 inst->setExecuted();
1276
1277 instToCommit(inst);
1278 }
1279
1280 updateExeInstStats(inst);
1281
1282 // Check if branch prediction was correct, if not then we need
1283 // to tell commit to squash in flight instructions. Only
1284 // handle this if there hasn't already been something that
1285 // redirects fetch in this group of instructions.
1286
1287 // This probably needs to prioritize the redirects if a different
1288 // scheduler is used. Currently the scheduler schedules the oldest
1289 // instruction first, so the branch resolution order will be correct.
1290 ThreadID tid = inst->threadNumber;
1291
1292 if (!fetchRedirect[tid] ||
1293 toCommit->squashedSeqNum[tid] > inst->seqNum) {
1294
1295 if (inst->mispredicted()) {
1296 fetchRedirect[tid] = true;
1297
1298 DPRINTF(IEW, "Execute: Branch mispredict detected.\n");
1299 DPRINTF(IEW, "Predicted target was PC:%#x, NPC:%#x.\n",
1300 inst->readPredPC(), inst->readPredNPC());
1301 DPRINTF(IEW, "Execute: Redirecting fetch to PC: %#x,"
1302 " NPC: %#x.\n", inst->readNextPC(),
1303 inst->readNextNPC());
1304 // If incorrect, then signal the ROB that it must be squashed.
1305 squashDueToBranch(inst, tid);
1306
1307 if (inst->readPredTaken()) {
1308 predictedTakenIncorrect++;
1309 } else {
1310 predictedNotTakenIncorrect++;
1311 }
1312 } else if (ldstQueue.violation(tid)) {
1313 assert(inst->isMemRef());
1314 // If there was an ordering violation, then get the
1315 // DynInst that caused the violation. Note that this
1316 // clears the violation signal.
1317 DynInstPtr violator;
1318 violator = ldstQueue.getMemDepViolator(tid);
1319
1320 DPRINTF(IEW, "LDSTQ detected a violation. Violator PC: "
1321 "%#x, inst PC: %#x. Addr is: %#x.\n",
1322 violator->readPC(), inst->readPC(), inst->physEffAddr);
1323
1324 // Ensure the violating instruction is older than
1325 // current squash
1326/* if (fetchRedirect[tid] &&
1327 violator->seqNum >= toCommit->squashedSeqNum[tid] + 1)
1328 continue;
1329*/
1330 fetchRedirect[tid] = true;
1331
1332 // Tell the instruction queue that a violation has occured.
1333 instQueue.violation(inst, violator);
1334
1335 // Squash.
1336 squashDueToMemOrder(inst,tid);
1337
1338 ++memOrderViolationEvents;
1339 } else if (ldstQueue.loadBlocked(tid) &&
1340 !ldstQueue.isLoadBlockedHandled(tid)) {
1341 fetchRedirect[tid] = true;
1342
1343 DPRINTF(IEW, "Load operation couldn't execute because the "
1344 "memory system is blocked. PC: %#x [sn:%lli]\n",
1345 inst->readPC(), inst->seqNum);
1346
1347 squashDueToMemBlocked(inst, tid);
1348 }
1349 } else {
1350 // Reset any state associated with redirects that will not
1351 // be used.
1352 if (ldstQueue.violation(tid)) {
1353 assert(inst->isMemRef());
1354
1355 DynInstPtr violator = ldstQueue.getMemDepViolator(tid);
1356
1357 DPRINTF(IEW, "LDSTQ detected a violation. Violator PC: "
1358 "%#x, inst PC: %#x. Addr is: %#x.\n",
1359 violator->readPC(), inst->readPC(), inst->physEffAddr);
1360 DPRINTF(IEW, "Violation will not be handled because "
1361 "already squashing\n");
1362
1363 ++memOrderViolationEvents;
1364 }
1365 if (ldstQueue.loadBlocked(tid) &&
1366 !ldstQueue.isLoadBlockedHandled(tid)) {
1367 DPRINTF(IEW, "Load operation couldn't execute because the "
1368 "memory system is blocked. PC: %#x [sn:%lli]\n",
1369 inst->readPC(), inst->seqNum);
1370 DPRINTF(IEW, "Blocked load will not be handled because "
1371 "already squashing\n");
1372
1373 ldstQueue.setLoadBlockedHandled(tid);
1374 }
1375
1376 }
1377 }
1378
1379 // Update and record activity if we processed any instructions.
1380 if (inst_num) {
1381 if (exeStatus == Idle) {
1382 exeStatus = Running;
1383 }
1384
1385 updatedQueues = true;
1386
1387 cpu->activityThisCycle();
1388 }
1389
1390 // Need to reset this in case a writeback event needs to write into the
1391 // iew queue. That way the writeback event will write into the correct
1392 // spot in the queue.
1393 wbNumInst = 0;
1394}
1395
1396template <class Impl>
1397void
1398DefaultIEW<Impl>::writebackInsts()
1399{
1400 // Loop through the head of the time buffer and wake any
1401 // dependents. These instructions are about to write back. Also
1402 // mark scoreboard that this instruction is finally complete.
1403 // Either have IEW have direct access to scoreboard, or have this
1404 // as part of backwards communication.
1405 for (int inst_num = 0; inst_num < wbWidth &&
1406 toCommit->insts[inst_num]; inst_num++) {
1407 DynInstPtr inst = toCommit->insts[inst_num];
1408 ThreadID tid = inst->threadNumber;
1409
1410 DPRINTF(IEW, "Sending instructions to commit, [sn:%lli] PC %#x.\n",
1411 inst->seqNum, inst->readPC());
1412
1413 iewInstsToCommit[tid]++;
1414
1415 // Some instructions will be sent to commit without having
1416 // executed because they need commit to handle them.
1417 // E.g. Uncached loads have not actually executed when they
1418 // are first sent to commit. Instead commit must tell the LSQ
1419 // when it's ready to execute the uncached load.
1420 if (!inst->isSquashed() && inst->isExecuted() && inst->getFault() == NoFault) {
1421 int dependents = instQueue.wakeDependents(inst);
1422
1423 for (int i = 0; i < inst->numDestRegs(); i++) {
1424 //mark as Ready
1425 DPRINTF(IEW,"Setting Destination Register %i\n",
1426 inst->renamedDestRegIdx(i));
1427 scoreboard->setReg(inst->renamedDestRegIdx(i));
1428 }
1429
1430 if (dependents) {
1431 producerInst[tid]++;
1432 consumerInst[tid]+= dependents;
1433 }
1434 writebackCount[tid]++;
1435 }
1436
1437 decrWb(inst->seqNum);
1438 }
1439}
1440
1441template<class Impl>
1442void
1443DefaultIEW<Impl>::tick()
1444{
1445 wbNumInst = 0;
1446 wbCycle = 0;
1447
1448 wroteToTimeBuffer = false;
1449 updatedQueues = false;
1450
1451 sortInsts();
1452
1453 // Free function units marked as being freed this cycle.
1454 fuPool->processFreeUnits();
1455
1456 list<ThreadID>::iterator threads = activeThreads->begin();
1457 list<ThreadID>::iterator end = activeThreads->end();
1458
1459 // Check stall and squash signals, dispatch any instructions.
1460 while (threads != end) {
1461 ThreadID tid = *threads++;
1462
1463 DPRINTF(IEW,"Issue: Processing [tid:%i]\n",tid);
1464
1465 checkSignalsAndUpdate(tid);
1466 dispatch(tid);
1467 }
1468
1469 if (exeStatus != Squashing) {
1470 executeInsts();
1471
1472 writebackInsts();
1473
1474 // Have the instruction queue try to schedule any ready instructions.
1475 // (In actuality, this scheduling is for instructions that will
1476 // be executed next cycle.)
1477 instQueue.scheduleReadyInsts();
1478
1479 // Also should advance its own time buffers if the stage ran.
1480 // Not the best place for it, but this works (hopefully).
1481 issueToExecQueue.advance();
1482 }
1483
1484 bool broadcast_free_entries = false;
1485
1486 if (updatedQueues || exeStatus == Running || updateLSQNextCycle) {
1487 exeStatus = Idle;
1488 updateLSQNextCycle = false;
1489
1490 broadcast_free_entries = true;
1491 }
1492
1493 // Writeback any stores using any leftover bandwidth.
1494 ldstQueue.writebackStores();
1495
1496 // Check the committed load/store signals to see if there's a load
1497 // or store to commit. Also check if it's being told to execute a
1498 // nonspeculative instruction.
1499 // This is pretty inefficient...
1500
1501 threads = activeThreads->begin();
1502 while (threads != end) {
1503 ThreadID tid = (*threads++);
1504
1505 DPRINTF(IEW,"Processing [tid:%i]\n",tid);
1506
1507 // Update structures based on instructions committed.
1508 if (fromCommit->commitInfo[tid].doneSeqNum != 0 &&
1509 !fromCommit->commitInfo[tid].squash &&
1510 !fromCommit->commitInfo[tid].robSquashing) {
1511
1512 ldstQueue.commitStores(fromCommit->commitInfo[tid].doneSeqNum,tid);
1513
1514 ldstQueue.commitLoads(fromCommit->commitInfo[tid].doneSeqNum,tid);
1515
1516 updateLSQNextCycle = true;
1517 instQueue.commit(fromCommit->commitInfo[tid].doneSeqNum,tid);
1518 }
1519
1520 if (fromCommit->commitInfo[tid].nonSpecSeqNum != 0) {
1521
1522 //DPRINTF(IEW,"NonspecInst from thread %i",tid);
1523 if (fromCommit->commitInfo[tid].uncached) {
1524 instQueue.replayMemInst(fromCommit->commitInfo[tid].uncachedLoad);
1525 fromCommit->commitInfo[tid].uncachedLoad->setAtCommit();
1526 } else {
1527 instQueue.scheduleNonSpec(
1528 fromCommit->commitInfo[tid].nonSpecSeqNum);
1529 }
1530 }
1531
1532 if (broadcast_free_entries) {
1533 toFetch->iewInfo[tid].iqCount =
1534 instQueue.getCount(tid);
1535 toFetch->iewInfo[tid].ldstqCount =
1536 ldstQueue.getCount(tid);
1537
1538 toRename->iewInfo[tid].usedIQ = true;
1539 toRename->iewInfo[tid].freeIQEntries =
1540 instQueue.numFreeEntries();
1541 toRename->iewInfo[tid].usedLSQ = true;
1542 toRename->iewInfo[tid].freeLSQEntries =
1543 ldstQueue.numFreeEntries(tid);
1544
1545 wroteToTimeBuffer = true;
1546 }
1547
1548 DPRINTF(IEW, "[tid:%i], Dispatch dispatched %i instructions.\n",
1549 tid, toRename->iewInfo[tid].dispatched);
1550 }
1551
1552 DPRINTF(IEW, "IQ has %i free entries (Can schedule: %i). "
1553 "LSQ has %i free entries.\n",
1554 instQueue.numFreeEntries(), instQueue.hasReadyInsts(),
1555 ldstQueue.numFreeEntries());
1556
1557 updateStatus();
1558
1559 if (wroteToTimeBuffer) {
1560 DPRINTF(Activity, "Activity this cycle.\n");
1561 cpu->activityThisCycle();
1562 }
1563}
1564
1565template <class Impl>
1566void
1567DefaultIEW<Impl>::updateExeInstStats(DynInstPtr &inst)
1568{
1569 ThreadID tid = inst->threadNumber;
1570
1571 //
1572 // Pick off the software prefetches
1573 //
1574#ifdef TARGET_ALPHA
1575 if (inst->isDataPrefetch())
1576 iewExecutedSwp[tid]++;
1577 else
1578 iewIewExecutedcutedInsts++;
1579#else
1580 iewExecutedInsts++;
1581#endif
1582
1583 //
1584 // Control operations
1585 //
1586 if (inst->isControl())
1587 iewExecutedBranches[tid]++;
1588
1589 //
1590 // Memory operations
1591 //
1592 if (inst->isMemRef()) {
1593 iewExecutedRefs[tid]++;
1594
1595 if (inst->isLoad()) {
1596 iewExecLoadInsts[tid]++;
1597 }
1598 }
1599}
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