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#include "arch/isa_traits.hh"
32#include "arch/utility.hh"
33#include "cpu/exetrace.hh"
34#include "cpu/o3/fetch.hh"
35#include "mem/packet.hh"
36#include "mem/request.hh"
37#include "sim/byteswap.hh"
38#include "sim/host.hh"
39#include "sim/root.hh"
40
41#if FULL_SYSTEM
42#include "arch/tlb.hh"
43#include "arch/vtophys.hh"
44#include "base/remote_gdb.hh"
45#include "mem/functional/memory_control.hh"
46#include "mem/functional/physical.hh"
47#include "sim/system.hh"
48#endif // FULL_SYSTEM
49
50#include <algorithm>
51
52using namespace std;
53using namespace TheISA;
54
55template<class Impl>
56Tick
57DefaultFetch<Impl>::IcachePort::recvAtomic(PacketPtr pkt)
58{
59 panic("DefaultFetch doesn't expect recvAtomic callback!");
60 return curTick;
61}
62
63template<class Impl>
64void
65DefaultFetch<Impl>::IcachePort::recvFunctional(PacketPtr pkt)
66{
67 panic("DefaultFetch doesn't expect recvFunctional callback!");
68}
69
70template<class Impl>
71void
72DefaultFetch<Impl>::IcachePort::recvStatusChange(Status status)
73{
74 if (status == RangeChange)
75 return;
76
77 panic("DefaultFetch doesn't expect recvStatusChange callback!");
78}
79
80template<class Impl>
81bool
82DefaultFetch<Impl>::IcachePort::recvTiming(Packet *pkt)
83{
84 fetch->processCacheCompletion(pkt);
85 return true;
86}
87
88template<class Impl>
89void
90DefaultFetch<Impl>::IcachePort::recvRetry()
91{
92 panic("DefaultFetch doesn't support retry yet.");
93 // we shouldn't get a retry unless we have a packet that we're
94 // waiting to transmit
95/*
96 assert(cpu->dcache_pkt != NULL);
97 assert(cpu->_status == DcacheRetry);
98 Packet *tmp = cpu->dcache_pkt;
99 if (sendTiming(tmp)) {
100 cpu->_status = DcacheWaitResponse;
101 cpu->dcache_pkt = NULL;
102 }
103*/
104}
105
106template<class Impl>
107DefaultFetch<Impl>::DefaultFetch(Params *params)
108 : branchPred(params),
109 decodeToFetchDelay(params->decodeToFetchDelay),
110 renameToFetchDelay(params->renameToFetchDelay),
111 iewToFetchDelay(params->iewToFetchDelay),
112 commitToFetchDelay(params->commitToFetchDelay),
113 fetchWidth(params->fetchWidth),
114 numThreads(params->numberOfThreads),
115 numFetchingThreads(params->smtNumFetchingThreads),
116 interruptPending(false)
117{
118 if (numThreads > Impl::MaxThreads)
119 fatal("numThreads is not a valid value\n");
120
121 DPRINTF(Fetch, "Fetch constructor called\n");
122
123 // Set fetch stage's status to inactive.
124 _status = Inactive;
125
126 string policy = params->smtFetchPolicy;
127
128 // Convert string to lowercase
129 std::transform(policy.begin(), policy.end(), policy.begin(),
130 (int(*)(int)) tolower);
131
132 // Figure out fetch policy
133 if (policy == "singlethread") {
134 fetchPolicy = SingleThread;
135 } else if (policy == "roundrobin") {
136 fetchPolicy = RoundRobin;
137 DPRINTF(Fetch, "Fetch policy set to Round Robin\n");
138 } else if (policy == "branch") {
139 fetchPolicy = Branch;
140 DPRINTF(Fetch, "Fetch policy set to Branch Count\n");
141 } else if (policy == "iqcount") {
142 fetchPolicy = IQ;
143 DPRINTF(Fetch, "Fetch policy set to IQ count\n");
144 } else if (policy == "lsqcount") {
145 fetchPolicy = LSQ;
146 DPRINTF(Fetch, "Fetch policy set to LSQ count\n");
147 } else {
148 fatal("Invalid Fetch Policy. Options Are: {SingleThread,"
149 " RoundRobin,LSQcount,IQcount}\n");
150 }
151
152 // Size of cache block.
153 cacheBlkSize = 64;
154
155 // Create mask to get rid of offset bits.
156 cacheBlkMask = (cacheBlkSize - 1);
157
158 for (int tid=0; tid < numThreads; tid++) {
159
160 fetchStatus[tid] = Running;
161
162 priorityList.push_back(tid);
163
164 memPkt[tid] = NULL;
165
166 // Create space to store a cache line.
167 cacheData[tid] = new uint8_t[cacheBlkSize];
168
169 stalls[tid].decode = 0;
170 stalls[tid].rename = 0;
171 stalls[tid].iew = 0;
172 stalls[tid].commit = 0;
173 }
174
175 // Get the size of an instruction.
176 instSize = sizeof(MachInst);
177}
178
179template <class Impl>
180std::string
181DefaultFetch<Impl>::name() const
182{
183 return cpu->name() + ".fetch";
184}
185
186template <class Impl>
187void
188DefaultFetch<Impl>::regStats()
189{
190 icacheStallCycles
191 .name(name() + ".icacheStallCycles")
192 .desc("Number of cycles fetch is stalled on an Icache miss")
193 .prereq(icacheStallCycles);
194
195 fetchedInsts
196 .name(name() + ".Insts")
197 .desc("Number of instructions fetch has processed")
198 .prereq(fetchedInsts);
199
200 fetchedBranches
201 .name(name() + ".Branches")
202 .desc("Number of branches that fetch encountered")
203 .prereq(fetchedBranches);
204
205 predictedBranches
206 .name(name() + ".predictedBranches")
207 .desc("Number of branches that fetch has predicted taken")
208 .prereq(predictedBranches);
209
210 fetchCycles
211 .name(name() + ".Cycles")
212 .desc("Number of cycles fetch has run and was not squashing or"
213 " blocked")
214 .prereq(fetchCycles);
215
216 fetchSquashCycles
217 .name(name() + ".SquashCycles")
218 .desc("Number of cycles fetch has spent squashing")
219 .prereq(fetchSquashCycles);
220
221 fetchIdleCycles
222 .name(name() + ".IdleCycles")
223 .desc("Number of cycles fetch was idle")
224 .prereq(fetchIdleCycles);
225
226 fetchBlockedCycles
227 .name(name() + ".BlockedCycles")
228 .desc("Number of cycles fetch has spent blocked")
229 .prereq(fetchBlockedCycles);
230
231 fetchedCacheLines
232 .name(name() + ".CacheLines")
233 .desc("Number of cache lines fetched")
234 .prereq(fetchedCacheLines);
235
236 fetchMiscStallCycles
237 .name(name() + ".MiscStallCycles")
238 .desc("Number of cycles fetch has spent waiting on interrupts, or "
239 "bad addresses, or out of MSHRs")
240 .prereq(fetchMiscStallCycles);
241
242 fetchIcacheSquashes
243 .name(name() + ".IcacheSquashes")
244 .desc("Number of outstanding Icache misses that were squashed")
245 .prereq(fetchIcacheSquashes);
246
247 fetchNisnDist
248 .init(/* base value */ 0,
249 /* last value */ fetchWidth,
250 /* bucket size */ 1)
251 .name(name() + ".rateDist")
252 .desc("Number of instructions fetched each cycle (Total)")
253 .flags(Stats::pdf);
254
255 idleRate
256 .name(name() + ".idleRate")
257 .desc("Percent of cycles fetch was idle")
258 .prereq(idleRate);
259 idleRate = fetchIdleCycles * 100 / cpu->numCycles;
260
261 branchRate
262 .name(name() + ".branchRate")
263 .desc("Number of branch fetches per cycle")
264 .flags(Stats::total);
265 branchRate = fetchedBranches / cpu->numCycles;
266
267 fetchRate
268 .name(name() + ".rate")
269 .desc("Number of inst fetches per cycle")
270 .flags(Stats::total);
271 fetchRate = fetchedInsts / cpu->numCycles;
272
273 branchPred.regStats();
274}
275
276template<class Impl>
277void
278DefaultFetch<Impl>::setCPU(FullCPU *cpu_ptr)
279{
280 DPRINTF(Fetch, "Setting the CPU pointer.\n");
281 cpu = cpu_ptr;
282
283 // Name is finally available, so create the port.
284 icachePort = new IcachePort(this);
285
286 // Fetch needs to start fetching instructions at the very beginning,
287 // so it must start up in active state.
288 switchToActive();
289}
290
291template<class Impl>
292void
293DefaultFetch<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *time_buffer)
294{
295 DPRINTF(Fetch, "Setting the time buffer pointer.\n");
296 timeBuffer = time_buffer;
297
298 // Create wires to get information from proper places in time buffer.
299 fromDecode = timeBuffer->getWire(-decodeToFetchDelay);
300 fromRename = timeBuffer->getWire(-renameToFetchDelay);
301 fromIEW = timeBuffer->getWire(-iewToFetchDelay);
302 fromCommit = timeBuffer->getWire(-commitToFetchDelay);
303}
304
305template<class Impl>
306void
307DefaultFetch<Impl>::setActiveThreads(list<unsigned> *at_ptr)
308{
309 DPRINTF(Fetch, "Setting active threads list pointer.\n");
310 activeThreads = at_ptr;
311}
312
313template<class Impl>
314void
315DefaultFetch<Impl>::setFetchQueue(TimeBuffer<FetchStruct> *fq_ptr)
316{
317 DPRINTF(Fetch, "Setting the fetch queue pointer.\n");
318 fetchQueue = fq_ptr;
319
320 // Create wire to write information to proper place in fetch queue.
321 toDecode = fetchQueue->getWire(0);
322}
323
324#if 0
325template<class Impl>
326void
327DefaultFetch<Impl>::setPageTable(PageTable *pt_ptr)
328{
329 DPRINTF(Fetch, "Setting the page table pointer.\n");
330#if !FULL_SYSTEM
331 pTable = pt_ptr;
332#endif
333}
334#endif
335
336template<class Impl>
337void
338DefaultFetch<Impl>::initStage()
339{
340 // Setup PC and nextPC with initial state.
341 for (int tid = 0; tid < numThreads; tid++) {
342 PC[tid] = cpu->readPC(tid);
343 nextPC[tid] = cpu->readNextPC(tid);
344 }
345}
346
347template<class Impl>
348void
349DefaultFetch<Impl>::processCacheCompletion(PacketPtr pkt)
350{
351 unsigned tid = pkt->req->getThreadNum();
352
353 DPRINTF(Fetch, "[tid:%u] Waking up from cache miss.\n",tid);
354
355 // Only change the status if it's still waiting on the icache access
356 // to return.
357 if (fetchStatus[tid] != IcacheWaitResponse ||
358 pkt != memPkt[tid] ||
359 isSwitchedOut()) {
360 ++fetchIcacheSquashes;
361 delete pkt;
362 return;
363 }
364
365 // Wake up the CPU (if it went to sleep and was waiting on this completion
366 // event).
367 cpu->wakeCPU();
368
369 DPRINTF(Activity, "[tid:%u] Activating fetch due to cache completion\n",
370 tid);
371
372 switchToActive();
373
374 // Only switch to IcacheAccessComplete if we're not stalled as well.
375 if (checkStall(tid)) {
376 fetchStatus[tid] = Blocked;
377 } else {
378 fetchStatus[tid] = IcacheAccessComplete;
379 }
380
381// memcpy(cacheData[tid], memReq[tid]->data, memReq[tid]->size);
382
383 // Reset the mem req to NULL.
384 delete pkt->req;
385 delete pkt;
386 memPkt[tid] = NULL;
387}
388
389template <class Impl>
390void
391DefaultFetch<Impl>::switchOut()
392{
393 // Fetch is ready to switch out at any time.
394 switchedOut = true;
395 cpu->signalSwitched();
396}
397
398template <class Impl>
399void
400DefaultFetch<Impl>::doSwitchOut()
401{
402 // Branch predictor needs to have its state cleared.
403 branchPred.switchOut();
404}
405
406template <class Impl>
407void
408DefaultFetch<Impl>::takeOverFrom()
409{
410 // Reset all state
411 for (int i = 0; i < Impl::MaxThreads; ++i) {
412 stalls[i].decode = 0;
413 stalls[i].rename = 0;
414 stalls[i].iew = 0;
415 stalls[i].commit = 0;
416 PC[i] = cpu->readPC(i);
417 nextPC[i] = cpu->readNextPC(i);
418 fetchStatus[i] = Running;
419 }
420 numInst = 0;
421 wroteToTimeBuffer = false;
422 _status = Inactive;
423 switchedOut = false;
424 branchPred.takeOverFrom();
425}
426
427template <class Impl>
428void
429DefaultFetch<Impl>::wakeFromQuiesce()
430{
431 DPRINTF(Fetch, "Waking up from quiesce\n");
432 // Hopefully this is safe
433 // @todo: Allow other threads to wake from quiesce.
434 fetchStatus[0] = Running;
435}
436
437template <class Impl>
438inline void
439DefaultFetch<Impl>::switchToActive()
440{
441 if (_status == Inactive) {
442 DPRINTF(Activity, "Activating stage.\n");
443
444 cpu->activateStage(FullCPU::FetchIdx);
445
446 _status = Active;
447 }
448}
449
450template <class Impl>
451inline void
452DefaultFetch<Impl>::switchToInactive()
453{
454 if (_status == Active) {
455 DPRINTF(Activity, "Deactivating stage.\n");
456
457 cpu->deactivateStage(FullCPU::FetchIdx);
458
459 _status = Inactive;
460 }
461}
462
463template <class Impl>
464bool
465DefaultFetch<Impl>::lookupAndUpdateNextPC(DynInstPtr &inst, Addr &next_PC)
466{
467 // Do branch prediction check here.
468 // A bit of a misnomer...next_PC is actually the current PC until
469 // this function updates it.
470 bool predict_taken;
471
472 if (!inst->isControl()) {
473 next_PC = next_PC + instSize;
474 inst->setPredTarg(next_PC);
475 return false;
476 }
477
478 predict_taken = branchPred.predict(inst, next_PC, inst->threadNumber);
479
480 ++fetchedBranches;
481
482 if (predict_taken) {
483 ++predictedBranches;
484 }
485
486 return predict_taken;
487}
488
489template <class Impl>
490bool
491DefaultFetch<Impl>::fetchCacheLine(Addr fetch_PC, Fault &ret_fault, unsigned tid)
492{
493 Fault fault = NoFault;
494
495#if FULL_SYSTEM
496 // Flag to say whether or not address is physical addr.
497 unsigned flags = cpu->inPalMode(fetch_PC) ? PHYSICAL : 0;
498#else
499 unsigned flags = 0;
500#endif // FULL_SYSTEM
501
502 if (interruptPending && flags == 0 || switchedOut) {
503 // Hold off fetch from getting new instructions while an interrupt
504 // is pending.
505 return false;
506 }
507
508 // Align the fetch PC so it's at the start of a cache block.
509 fetch_PC = icacheBlockAlignPC(fetch_PC);
510
511 // Setup the memReq to do a read of the first instruction's address.
512 // Set the appropriate read size and flags as well.
513 // Build request here.
514 RequestPtr mem_req = new Request(tid, fetch_PC, cacheBlkSize, flags,
515 fetch_PC, cpu->readCpuId(), tid);
516
517 memPkt[tid] = NULL;
518
519 // Translate the instruction request.
520//#if FULL_SYSTEM
521 fault = cpu->translateInstReq(mem_req);
522//#else
523// fault = pTable->translate(memReq[tid]);
524//#endif
525
526 // In the case of faults, the fetch stage may need to stall and wait
527 // for the ITB miss to be handled.
528
529 // If translation was successful, attempt to read the first
530 // instruction.
531 if (fault == NoFault) {
532#if FULL_SYSTEM
533 if (cpu->system->memctrl->badaddr(memReq[tid]->paddr) ||
534 memReq[tid]->flags & UNCACHEABLE) {
535 DPRINTF(Fetch, "Fetch: Bad address %#x (hopefully on a "
536 "misspeculating path)!",
537 memReq[tid]->paddr);
538 ret_fault = TheISA::genMachineCheckFault();
539 return false;
540 }
541#endif
542
543 // Build packet here.
544 PacketPtr data_pkt = new Packet(mem_req,
545 Packet::ReadReq, Packet::Broadcast);
546 data_pkt->dataStatic(cacheData[tid]);
547
548 DPRINTF(Fetch, "Fetch: Doing instruction read.\n");
549
550 fetchedCacheLines++;
551
552 // Now do the timing access to see whether or not the instruction
553 // exists within the cache.
554 if (!icachePort->sendTiming(data_pkt)) {
555 DPRINTF(Fetch, "[tid:%i] Out of MSHRs!\n", tid);
556 ret_fault = NoFault;
557 return false;
558 }
559
560 DPRINTF(Fetch, "Doing cache access.\n");
561
562 lastIcacheStall[tid] = curTick;
563
564 DPRINTF(Activity, "[tid:%i]: Activity: Waiting on I-cache "
565 "response.\n", tid);
566
567 fetchStatus[tid] = IcacheWaitResponse;
568 }
569
570 ret_fault = fault;
571 return true;
572}
573
574template <class Impl>
575inline void
576DefaultFetch<Impl>::doSquash(const Addr &new_PC, unsigned tid)
577{
578 DPRINTF(Fetch, "[tid:%i]: Squashing, setting PC to: %#x.\n",
579 tid, new_PC);
580
581 PC[tid] = new_PC;
582 nextPC[tid] = new_PC + instSize;
583
584 // Clear the icache miss if it's outstanding.
585 if (fetchStatus[tid] == IcacheWaitResponse) {
586 DPRINTF(Fetch, "[tid:%i]: Squashing outstanding Icache miss.\n",
587 tid);
588 delete memPkt[tid];
589 memPkt[tid] = NULL;
590 }
591
592 fetchStatus[tid] = Squashing;
593
594 ++fetchSquashCycles;
595}
596
597template<class Impl>
598void
599DefaultFetch<Impl>::squashFromDecode(const Addr &new_PC,
600 const InstSeqNum &seq_num,
601 unsigned tid)
602{
603 DPRINTF(Fetch, "[tid:%i]: Squashing from decode.\n",tid);
604
605 doSquash(new_PC, tid);
606
607 // Tell the CPU to remove any instructions that are in flight between
608 // fetch and decode.
609 cpu->removeInstsUntil(seq_num, tid);
610}
611
612template<class Impl>
613bool
614DefaultFetch<Impl>::checkStall(unsigned tid) const
615{
616 bool ret_val = false;
617
618 if (cpu->contextSwitch) {
619 DPRINTF(Fetch,"[tid:%i]: Stalling for a context switch.\n",tid);
620 ret_val = true;
621 } else if (stalls[tid].decode) {
622 DPRINTF(Fetch,"[tid:%i]: Stall from Decode stage detected.\n",tid);
623 ret_val = true;
624 } else if (stalls[tid].rename) {
625 DPRINTF(Fetch,"[tid:%i]: Stall from Rename stage detected.\n",tid);
626 ret_val = true;
627 } else if (stalls[tid].iew) {
628 DPRINTF(Fetch,"[tid:%i]: Stall from IEW stage detected.\n",tid);
629 ret_val = true;
630 } else if (stalls[tid].commit) {
631 DPRINTF(Fetch,"[tid:%i]: Stall from Commit stage detected.\n",tid);
632 ret_val = true;
633 }
634
635 return ret_val;
636}
637
638template<class Impl>
639typename DefaultFetch<Impl>::FetchStatus
640DefaultFetch<Impl>::updateFetchStatus()
641{
642 //Check Running
643 list<unsigned>::iterator threads = (*activeThreads).begin();
644
645 while (threads != (*activeThreads).end()) {
646
647 unsigned tid = *threads++;
648
649 if (fetchStatus[tid] == Running ||
650 fetchStatus[tid] == Squashing ||
651 fetchStatus[tid] == IcacheAccessComplete) {
652
653 if (_status == Inactive) {
654 DPRINTF(Activity, "[tid:%i]: Activating stage.\n",tid);
655
656 if (fetchStatus[tid] == IcacheAccessComplete) {
657 DPRINTF(Activity, "[tid:%i]: Activating fetch due to cache"
658 "completion\n",tid);
659 }
660
661 cpu->activateStage(FullCPU::FetchIdx);
662 }
663
664 return Active;
665 }
666 }
667
668 // Stage is switching from active to inactive, notify CPU of it.
669 if (_status == Active) {
670 DPRINTF(Activity, "Deactivating stage.\n");
671
672 cpu->deactivateStage(FullCPU::FetchIdx);
673 }
674
675 return Inactive;
676}
677
678template <class Impl>
679void
680DefaultFetch<Impl>::squash(const Addr &new_PC, unsigned tid)
681{
682 DPRINTF(Fetch, "[tid:%u]: Squash from commit.\n",tid);
683
684 doSquash(new_PC, tid);
685
686 // Tell the CPU to remove any instructions that are not in the ROB.
687 cpu->removeInstsNotInROB(tid);
688}
689
690template <class Impl>
691void
692DefaultFetch<Impl>::tick()
693{
694 list<unsigned>::iterator threads = (*activeThreads).begin();
695 bool status_change = false;
696
697 wroteToTimeBuffer = false;
698
699 while (threads != (*activeThreads).end()) {
700 unsigned tid = *threads++;
701
702 // Check the signals for each thread to determine the proper status
703 // for each thread.
704 bool updated_status = checkSignalsAndUpdate(tid);
705 status_change = status_change || updated_status;
706 }
707
708 DPRINTF(Fetch, "Running stage.\n");
709
710 // Reset the number of the instruction we're fetching.
711 numInst = 0;
712
713 if (fromCommit->commitInfo[0].interruptPending) {
714 interruptPending = true;
715 }
716 if (fromCommit->commitInfo[0].clearInterrupt) {
717 interruptPending = false;
718 }
719
720 for (threadFetched = 0; threadFetched < numFetchingThreads;
721 threadFetched++) {
722 // Fetch each of the actively fetching threads.
723 fetch(status_change);
724 }
725
726 // Record number of instructions fetched this cycle for distribution.
727 fetchNisnDist.sample(numInst);
728
729 if (status_change) {
730 // Change the fetch stage status if there was a status change.
731 _status = updateFetchStatus();
732 }
733
734 // If there was activity this cycle, inform the CPU of it.
735 if (wroteToTimeBuffer || cpu->contextSwitch) {
736 DPRINTF(Activity, "Activity this cycle.\n");
737
738 cpu->activityThisCycle();
739 }
740}
741
742template <class Impl>
743bool
744DefaultFetch<Impl>::checkSignalsAndUpdate(unsigned tid)
745{
746 // Update the per thread stall statuses.
747 if (fromDecode->decodeBlock[tid]) {
748 stalls[tid].decode = true;
749 }
750
751 if (fromDecode->decodeUnblock[tid]) {
752 assert(stalls[tid].decode);
753 assert(!fromDecode->decodeBlock[tid]);
754 stalls[tid].decode = false;
755 }
756
757 if (fromRename->renameBlock[tid]) {
758 stalls[tid].rename = true;
759 }
760
761 if (fromRename->renameUnblock[tid]) {
762 assert(stalls[tid].rename);
763 assert(!fromRename->renameBlock[tid]);
764 stalls[tid].rename = false;
765 }
766
767 if (fromIEW->iewBlock[tid]) {
768 stalls[tid].iew = true;
769 }
770
771 if (fromIEW->iewUnblock[tid]) {
772 assert(stalls[tid].iew);
773 assert(!fromIEW->iewBlock[tid]);
774 stalls[tid].iew = false;
775 }
776
777 if (fromCommit->commitBlock[tid]) {
778 stalls[tid].commit = true;
779 }
780
781 if (fromCommit->commitUnblock[tid]) {
782 assert(stalls[tid].commit);
783 assert(!fromCommit->commitBlock[tid]);
784 stalls[tid].commit = false;
785 }
786
787 // Check squash signals from commit.
788 if (fromCommit->commitInfo[tid].squash) {
789
790 DPRINTF(Fetch, "[tid:%u]: Squashing instructions due to squash "
791 "from commit.\n",tid);
792
793 // In any case, squash.
794 squash(fromCommit->commitInfo[tid].nextPC,tid);
795
796 // Also check if there's a mispredict that happened.
797 if (fromCommit->commitInfo[tid].branchMispredict) {
798 branchPred.squash(fromCommit->commitInfo[tid].doneSeqNum,
799 fromCommit->commitInfo[tid].nextPC,
800 fromCommit->commitInfo[tid].branchTaken,
801 tid);
802 } else {
803 branchPred.squash(fromCommit->commitInfo[tid].doneSeqNum,
804 tid);
805 }
806
807 return true;
808 } else if (fromCommit->commitInfo[tid].doneSeqNum) {
809 // Update the branch predictor if it wasn't a squashed instruction
810 // that was broadcasted.
811 branchPred.update(fromCommit->commitInfo[tid].doneSeqNum, tid);
812 }
813
814 // Check ROB squash signals from commit.
815 if (fromCommit->commitInfo[tid].robSquashing) {
816 DPRINTF(Fetch, "[tid:%u]: ROB is still squashing Thread %u.\n", tid);
817
818 // Continue to squash.
819 fetchStatus[tid] = Squashing;
820
821 return true;
822 }
823
824 // Check squash signals from decode.
825 if (fromDecode->decodeInfo[tid].squash) {
826 DPRINTF(Fetch, "[tid:%u]: Squashing instructions due to squash "
827 "from decode.\n",tid);
828
829 // Update the branch predictor.
830 if (fromDecode->decodeInfo[tid].branchMispredict) {
831 branchPred.squash(fromDecode->decodeInfo[tid].doneSeqNum,
832 fromDecode->decodeInfo[tid].nextPC,
833 fromDecode->decodeInfo[tid].branchTaken,
834 tid);
835 } else {
836 branchPred.squash(fromDecode->decodeInfo[tid].doneSeqNum,
837 tid);
838 }
839
840 if (fetchStatus[tid] != Squashing) {
841 // Squash unless we're already squashing
842 squashFromDecode(fromDecode->decodeInfo[tid].nextPC,
843 fromDecode->decodeInfo[tid].doneSeqNum,
844 tid);
845
846 return true;
847 }
848 }
849
850 if (checkStall(tid) && fetchStatus[tid] != IcacheWaitResponse) {
851 DPRINTF(Fetch, "[tid:%i]: Setting to blocked\n",tid);
852
853 fetchStatus[tid] = Blocked;
854
855 return true;
856 }
857
858 if (fetchStatus[tid] == Blocked ||
859 fetchStatus[tid] == Squashing) {
860 // Switch status to running if fetch isn't being told to block or
861 // squash this cycle.
862 DPRINTF(Fetch, "[tid:%i]: Done squashing, switching to running.\n",
863 tid);
864
865 fetchStatus[tid] = Running;
866
867 return true;
868 }
869
870 // If we've reached this point, we have not gotten any signals that
871 // cause fetch to change its status. Fetch remains the same as before.
872 return false;
873}
874
875template<class Impl>
876void
877DefaultFetch<Impl>::fetch(bool &status_change)
878{
879 //////////////////////////////////////////
880 // Start actual fetch
881 //////////////////////////////////////////
882 int tid = getFetchingThread(fetchPolicy);
883
884 if (tid == -1) {
885 DPRINTF(Fetch,"There are no more threads available to fetch from.\n");
886
887 // Breaks looping condition in tick()
888 threadFetched = numFetchingThreads;
889 return;
890 }
891
892 // The current PC.
893 Addr &fetch_PC = PC[tid];
894
895 // Fault code for memory access.
896 Fault fault = NoFault;
897
898 // If returning from the delay of a cache miss, then update the status
899 // to running, otherwise do the cache access. Possibly move this up
900 // to tick() function.
901 if (fetchStatus[tid] == IcacheAccessComplete) {
902 DPRINTF(Fetch, "[tid:%i]: Icache miss is complete.\n",
903 tid);
904
905 fetchStatus[tid] = Running;
906 status_change = true;
907 } else if (fetchStatus[tid] == Running) {
908 DPRINTF(Fetch, "[tid:%i]: Attempting to translate and read "
909 "instruction, starting at PC %08p.\n",
910 tid, fetch_PC);
911
912 bool fetch_success = fetchCacheLine(fetch_PC, fault, tid);
913 if (!fetch_success) {
914 ++fetchMiscStallCycles;
915 return;
916 }
917 } else {
918 if (fetchStatus[tid] == Idle) {
919 ++fetchIdleCycles;
920 } else if (fetchStatus[tid] == Blocked) {
921 ++fetchBlockedCycles;
922 } else if (fetchStatus[tid] == Squashing) {
923 ++fetchSquashCycles;
924 } else if (fetchStatus[tid] == IcacheWaitResponse) {
925 ++icacheStallCycles;
926 }
927
928 // Status is Idle, Squashing, Blocked, or IcacheWaitResponse, so
929 // fetch should do nothing.
930 return;
931 }
932
933 ++fetchCycles;
934
935 // If we had a stall due to an icache miss, then return.
936 if (fetchStatus[tid] == IcacheWaitResponse) {
937 ++icacheStallCycles;
938 status_change = true;
939 return;
940 }
941
942 Addr next_PC = fetch_PC;
943 InstSeqNum inst_seq;
944 MachInst inst;
945 ExtMachInst ext_inst;
946 // @todo: Fix this hack.
947 unsigned offset = (fetch_PC & cacheBlkMask) & ~3;
948
949 if (fault == NoFault) {
950 // If the read of the first instruction was successful, then grab the
951 // instructions from the rest of the cache line and put them into the
952 // queue heading to decode.
953
954 DPRINTF(Fetch, "[tid:%i]: Adding instructions to queue to "
955 "decode.\n",tid);
956
957 // Need to keep track of whether or not a predicted branch
958 // ended this fetch block.
959 bool predicted_branch = false;
960
961 for (;
962 offset < cacheBlkSize &&
963 numInst < fetchWidth &&
964 !predicted_branch;
965 ++numInst) {
966
967 // Get a sequence number.
968 inst_seq = cpu->getAndIncrementInstSeq();
969
970 // Make sure this is a valid index.
971 assert(offset <= cacheBlkSize - instSize);
972
973 // Get the instruction from the array of the cache line.
974 inst = gtoh(*reinterpret_cast<MachInst *>
975 (&cacheData[tid][offset]));
976
977 ext_inst = TheISA::makeExtMI(inst, fetch_PC);
978
979 // Create a new DynInst from the instruction fetched.
980 DynInstPtr instruction = new DynInst(ext_inst, fetch_PC,
981 next_PC,
982 inst_seq, cpu);
983 instruction->setThread(tid);
984
985 instruction->setASID(tid);
986
987 instruction->setState(cpu->thread[tid]);
988
989 DPRINTF(Fetch, "[tid:%i]: Instruction PC %#x created "
990 "[sn:%lli]\n",
991 tid, instruction->readPC(), inst_seq);
992
993 DPRINTF(Fetch, "[tid:%i]: Instruction is: %s\n",
994 tid, instruction->staticInst->disassemble(fetch_PC));
995
996 instruction->traceData =
997 Trace::getInstRecord(curTick, cpu->xcBase(tid), cpu,
998 instruction->staticInst,
999 instruction->readPC(),tid);
1000
1001 predicted_branch = lookupAndUpdateNextPC(instruction, next_PC);
1002
1003 // Add instruction to the CPU's list of instructions.
1004 instruction->setInstListIt(cpu->addInst(instruction));
1005
1006 // Write the instruction to the first slot in the queue
1007 // that heads to decode.
1008 toDecode->insts[numInst] = instruction;
1009
1010 toDecode->size++;
1011
1012 // Increment stat of fetched instructions.
1013 ++fetchedInsts;
1014
1015 // Move to the next instruction, unless we have a branch.
1016 fetch_PC = next_PC;
1017
1018 if (instruction->isQuiesce()) {
1019 warn("%lli: Quiesce instruction encountered, halting fetch!",
1020 curTick);
1021 fetchStatus[tid] = QuiescePending;
1022 ++numInst;
1023 status_change = true;
1024 break;
1025 }
1026
1027 offset+= instSize;
1028 }
1029 }
1030
1031 if (numInst > 0) {
1032 wroteToTimeBuffer = true;
1033 }
1034
1035 // Now that fetching is completed, update the PC to signify what the next
1036 // cycle will be.
1037 if (fault == NoFault) {
1038 DPRINTF(Fetch, "[tid:%i]: Setting PC to %08p.\n",tid, next_PC);
1039
1040 PC[tid] = next_PC;
1041 nextPC[tid] = next_PC + instSize;
1042 } else {
1043 // We shouldn't be in an icache miss and also have a fault (an ITB
1044 // miss)
1045 if (fetchStatus[tid] == IcacheWaitResponse) {
1046 panic("Fetch should have exited prior to this!");
1047 }
1048
1049 // Send the fault to commit. This thread will not do anything
1050 // until commit handles the fault. The only other way it can
1051 // wake up is if a squash comes along and changes the PC.
1052#if FULL_SYSTEM
1053 assert(numInst != fetchWidth);
1054 // Get a sequence number.
1055 inst_seq = cpu->getAndIncrementInstSeq();
1056 // We will use a nop in order to carry the fault.
1057 ext_inst = TheISA::NoopMachInst;
1058
1059 // Create a new DynInst from the dummy nop.
1060 DynInstPtr instruction = new DynInst(ext_inst, fetch_PC,
1061 next_PC,
1062 inst_seq, cpu);
1063 instruction->setPredTarg(next_PC + instSize);
1064 instruction->setThread(tid);
1065
1066 instruction->setASID(tid);
1067
1068 instruction->setState(cpu->thread[tid]);
1069
1070 instruction->traceData = NULL;
1071
1072 instruction->setInstListIt(cpu->addInst(instruction));
1073
1074 instruction->fault = fault;
1075
1076 toDecode->insts[numInst] = instruction;
1077 toDecode->size++;
1078
1079 DPRINTF(Fetch, "[tid:%i]: Blocked, need to handle the trap.\n",tid);
1080
1081 fetchStatus[tid] = TrapPending;
1082 status_change = true;
1083
1084 warn("%lli fault (%d) detected @ PC %08p", curTick, fault, PC[tid]);
1085#else // !FULL_SYSTEM
1086 fatal("fault (%d) detected @ PC %08p", fault, PC[tid]);
1087#endif // FULL_SYSTEM
1088 }
1089}
1090
1091
1092///////////////////////////////////////
1093// //
1094// SMT FETCH POLICY MAINTAINED HERE //
1095// //
1096///////////////////////////////////////
1097template<class Impl>
1098int
1099DefaultFetch<Impl>::getFetchingThread(FetchPriority &fetch_priority)
1100{
1101 if (numThreads > 1) {
1102 switch (fetch_priority) {
1103
1104 case SingleThread:
1105 return 0;
1106
1107 case RoundRobin:
1108 return roundRobin();
1109
1110 case IQ:
1111 return iqCount();
1112
1113 case LSQ:
1114 return lsqCount();
1115
1116 case Branch:
1117 return branchCount();
1118
1119 default:
1120 return -1;
1121 }
1122 } else {
1123 int tid = *((*activeThreads).begin());
1124
1125 if (fetchStatus[tid] == Running ||
1126 fetchStatus[tid] == IcacheAccessComplete ||
1127 fetchStatus[tid] == Idle) {
1128 return tid;
1129 } else {
1130 return -1;
1131 }
1132 }
1133
1134}
1135
1136
1137template<class Impl>
1138int
1139DefaultFetch<Impl>::roundRobin()
1140{
1141 list<unsigned>::iterator pri_iter = priorityList.begin();
1142 list<unsigned>::iterator end = priorityList.end();
1143
1144 int high_pri;
1145
1146 while (pri_iter != end) {
1147 high_pri = *pri_iter;
1148
1149 assert(high_pri <= numThreads);
1150
1151 if (fetchStatus[high_pri] == Running ||
1152 fetchStatus[high_pri] == IcacheAccessComplete ||
1153 fetchStatus[high_pri] == Idle) {
1154
1155 priorityList.erase(pri_iter);
1156 priorityList.push_back(high_pri);
1157
1158 return high_pri;
1159 }
1160
1161 pri_iter++;
1162 }
1163
1164 return -1;
1165}
1166
1167template<class Impl>
1168int
1169DefaultFetch<Impl>::iqCount()
1170{
1171 priority_queue<unsigned> PQ;
1172
1173 list<unsigned>::iterator threads = (*activeThreads).begin();
1174
1175 while (threads != (*activeThreads).end()) {
1176 unsigned tid = *threads++;
1177
1178 PQ.push(fromIEW->iewInfo[tid].iqCount);
1179 }
1180
1181 while (!PQ.empty()) {
1182
1183 unsigned high_pri = PQ.top();
1184
1185 if (fetchStatus[high_pri] == Running ||
1186 fetchStatus[high_pri] == IcacheAccessComplete ||
1187 fetchStatus[high_pri] == Idle)
1188 return high_pri;
1189 else
1190 PQ.pop();
1191
1192 }
1193
1194 return -1;
1195}
1196
1197template<class Impl>
1198int
1199DefaultFetch<Impl>::lsqCount()
1200{
1201 priority_queue<unsigned> PQ;
1202
1203
1204 list<unsigned>::iterator threads = (*activeThreads).begin();
1205
1206 while (threads != (*activeThreads).end()) {
1207 unsigned tid = *threads++;
1208
1209 PQ.push(fromIEW->iewInfo[tid].ldstqCount);
1210 }
1211
1212 while (!PQ.empty()) {
1213
1214 unsigned high_pri = PQ.top();
1215
1216 if (fetchStatus[high_pri] == Running ||
1217 fetchStatus[high_pri] == IcacheAccessComplete ||
1218 fetchStatus[high_pri] == Idle)
1219 return high_pri;
1220 else
1221 PQ.pop();
1222
1223 }
1224
1225 return -1;
1226}
1227
1228template<class Impl>
1229int
1230DefaultFetch<Impl>::branchCount()
1231{
1232 list<unsigned>::iterator threads = (*activeThreads).begin();
1233
1234 return *threads;
1235}
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#include "arch/isa_traits.hh"
32#include "arch/utility.hh"
33#include "cpu/exetrace.hh"
34#include "cpu/o3/fetch.hh"
35#include "mem/packet.hh"
36#include "mem/request.hh"
37#include "sim/byteswap.hh"
38#include "sim/host.hh"
39#include "sim/root.hh"
40
41#if FULL_SYSTEM
42#include "arch/tlb.hh"
43#include "arch/vtophys.hh"
44#include "base/remote_gdb.hh"
45#include "mem/functional/memory_control.hh"
46#include "mem/functional/physical.hh"
47#include "sim/system.hh"
48#endif // FULL_SYSTEM
49
50#include <algorithm>
51
52using namespace std;
53using namespace TheISA;
54
55template<class Impl>
56Tick
57DefaultFetch<Impl>::IcachePort::recvAtomic(PacketPtr pkt)
58{
59 panic("DefaultFetch doesn't expect recvAtomic callback!");
60 return curTick;
61}
62
63template<class Impl>
64void
65DefaultFetch<Impl>::IcachePort::recvFunctional(PacketPtr pkt)
66{
67 panic("DefaultFetch doesn't expect recvFunctional callback!");
68}
69
70template<class Impl>
71void
72DefaultFetch<Impl>::IcachePort::recvStatusChange(Status status)
73{
74 if (status == RangeChange)
75 return;
76
77 panic("DefaultFetch doesn't expect recvStatusChange callback!");
78}
79
80template<class Impl>
81bool
82DefaultFetch<Impl>::IcachePort::recvTiming(Packet *pkt)
83{
84 fetch->processCacheCompletion(pkt);
85 return true;
86}
87
88template<class Impl>
89void
90DefaultFetch<Impl>::IcachePort::recvRetry()
91{
92 panic("DefaultFetch doesn't support retry yet.");
93 // we shouldn't get a retry unless we have a packet that we're
94 // waiting to transmit
95/*
96 assert(cpu->dcache_pkt != NULL);
97 assert(cpu->_status == DcacheRetry);
98 Packet *tmp = cpu->dcache_pkt;
99 if (sendTiming(tmp)) {
100 cpu->_status = DcacheWaitResponse;
101 cpu->dcache_pkt = NULL;
102 }
103*/
104}
105
106template<class Impl>
107DefaultFetch<Impl>::DefaultFetch(Params *params)
108 : branchPred(params),
109 decodeToFetchDelay(params->decodeToFetchDelay),
110 renameToFetchDelay(params->renameToFetchDelay),
111 iewToFetchDelay(params->iewToFetchDelay),
112 commitToFetchDelay(params->commitToFetchDelay),
113 fetchWidth(params->fetchWidth),
114 numThreads(params->numberOfThreads),
115 numFetchingThreads(params->smtNumFetchingThreads),
116 interruptPending(false)
117{
118 if (numThreads > Impl::MaxThreads)
119 fatal("numThreads is not a valid value\n");
120
121 DPRINTF(Fetch, "Fetch constructor called\n");
122
123 // Set fetch stage's status to inactive.
124 _status = Inactive;
125
126 string policy = params->smtFetchPolicy;
127
128 // Convert string to lowercase
129 std::transform(policy.begin(), policy.end(), policy.begin(),
130 (int(*)(int)) tolower);
131
132 // Figure out fetch policy
133 if (policy == "singlethread") {
134 fetchPolicy = SingleThread;
135 } else if (policy == "roundrobin") {
136 fetchPolicy = RoundRobin;
137 DPRINTF(Fetch, "Fetch policy set to Round Robin\n");
138 } else if (policy == "branch") {
139 fetchPolicy = Branch;
140 DPRINTF(Fetch, "Fetch policy set to Branch Count\n");
141 } else if (policy == "iqcount") {
142 fetchPolicy = IQ;
143 DPRINTF(Fetch, "Fetch policy set to IQ count\n");
144 } else if (policy == "lsqcount") {
145 fetchPolicy = LSQ;
146 DPRINTF(Fetch, "Fetch policy set to LSQ count\n");
147 } else {
148 fatal("Invalid Fetch Policy. Options Are: {SingleThread,"
149 " RoundRobin,LSQcount,IQcount}\n");
150 }
151
152 // Size of cache block.
153 cacheBlkSize = 64;
154
155 // Create mask to get rid of offset bits.
156 cacheBlkMask = (cacheBlkSize - 1);
157
158 for (int tid=0; tid < numThreads; tid++) {
159
160 fetchStatus[tid] = Running;
161
162 priorityList.push_back(tid);
163
164 memPkt[tid] = NULL;
165
166 // Create space to store a cache line.
167 cacheData[tid] = new uint8_t[cacheBlkSize];
168
169 stalls[tid].decode = 0;
170 stalls[tid].rename = 0;
171 stalls[tid].iew = 0;
172 stalls[tid].commit = 0;
173 }
174
175 // Get the size of an instruction.
176 instSize = sizeof(MachInst);
177}
178
179template <class Impl>
180std::string
181DefaultFetch<Impl>::name() const
182{
183 return cpu->name() + ".fetch";
184}
185
186template <class Impl>
187void
188DefaultFetch<Impl>::regStats()
189{
190 icacheStallCycles
191 .name(name() + ".icacheStallCycles")
192 .desc("Number of cycles fetch is stalled on an Icache miss")
193 .prereq(icacheStallCycles);
194
195 fetchedInsts
196 .name(name() + ".Insts")
197 .desc("Number of instructions fetch has processed")
198 .prereq(fetchedInsts);
199
200 fetchedBranches
201 .name(name() + ".Branches")
202 .desc("Number of branches that fetch encountered")
203 .prereq(fetchedBranches);
204
205 predictedBranches
206 .name(name() + ".predictedBranches")
207 .desc("Number of branches that fetch has predicted taken")
208 .prereq(predictedBranches);
209
210 fetchCycles
211 .name(name() + ".Cycles")
212 .desc("Number of cycles fetch has run and was not squashing or"
213 " blocked")
214 .prereq(fetchCycles);
215
216 fetchSquashCycles
217 .name(name() + ".SquashCycles")
218 .desc("Number of cycles fetch has spent squashing")
219 .prereq(fetchSquashCycles);
220
221 fetchIdleCycles
222 .name(name() + ".IdleCycles")
223 .desc("Number of cycles fetch was idle")
224 .prereq(fetchIdleCycles);
225
226 fetchBlockedCycles
227 .name(name() + ".BlockedCycles")
228 .desc("Number of cycles fetch has spent blocked")
229 .prereq(fetchBlockedCycles);
230
231 fetchedCacheLines
232 .name(name() + ".CacheLines")
233 .desc("Number of cache lines fetched")
234 .prereq(fetchedCacheLines);
235
236 fetchMiscStallCycles
237 .name(name() + ".MiscStallCycles")
238 .desc("Number of cycles fetch has spent waiting on interrupts, or "
239 "bad addresses, or out of MSHRs")
240 .prereq(fetchMiscStallCycles);
241
242 fetchIcacheSquashes
243 .name(name() + ".IcacheSquashes")
244 .desc("Number of outstanding Icache misses that were squashed")
245 .prereq(fetchIcacheSquashes);
246
247 fetchNisnDist
248 .init(/* base value */ 0,
249 /* last value */ fetchWidth,
250 /* bucket size */ 1)
251 .name(name() + ".rateDist")
252 .desc("Number of instructions fetched each cycle (Total)")
253 .flags(Stats::pdf);
254
255 idleRate
256 .name(name() + ".idleRate")
257 .desc("Percent of cycles fetch was idle")
258 .prereq(idleRate);
259 idleRate = fetchIdleCycles * 100 / cpu->numCycles;
260
261 branchRate
262 .name(name() + ".branchRate")
263 .desc("Number of branch fetches per cycle")
264 .flags(Stats::total);
265 branchRate = fetchedBranches / cpu->numCycles;
266
267 fetchRate
268 .name(name() + ".rate")
269 .desc("Number of inst fetches per cycle")
270 .flags(Stats::total);
271 fetchRate = fetchedInsts / cpu->numCycles;
272
273 branchPred.regStats();
274}
275
276template<class Impl>
277void
278DefaultFetch<Impl>::setCPU(FullCPU *cpu_ptr)
279{
280 DPRINTF(Fetch, "Setting the CPU pointer.\n");
281 cpu = cpu_ptr;
282
283 // Name is finally available, so create the port.
284 icachePort = new IcachePort(this);
285
286 // Fetch needs to start fetching instructions at the very beginning,
287 // so it must start up in active state.
288 switchToActive();
289}
290
291template<class Impl>
292void
293DefaultFetch<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *time_buffer)
294{
295 DPRINTF(Fetch, "Setting the time buffer pointer.\n");
296 timeBuffer = time_buffer;
297
298 // Create wires to get information from proper places in time buffer.
299 fromDecode = timeBuffer->getWire(-decodeToFetchDelay);
300 fromRename = timeBuffer->getWire(-renameToFetchDelay);
301 fromIEW = timeBuffer->getWire(-iewToFetchDelay);
302 fromCommit = timeBuffer->getWire(-commitToFetchDelay);
303}
304
305template<class Impl>
306void
307DefaultFetch<Impl>::setActiveThreads(list<unsigned> *at_ptr)
308{
309 DPRINTF(Fetch, "Setting active threads list pointer.\n");
310 activeThreads = at_ptr;
311}
312
313template<class Impl>
314void
315DefaultFetch<Impl>::setFetchQueue(TimeBuffer<FetchStruct> *fq_ptr)
316{
317 DPRINTF(Fetch, "Setting the fetch queue pointer.\n");
318 fetchQueue = fq_ptr;
319
320 // Create wire to write information to proper place in fetch queue.
321 toDecode = fetchQueue->getWire(0);
322}
323
324#if 0
325template<class Impl>
326void
327DefaultFetch<Impl>::setPageTable(PageTable *pt_ptr)
328{
329 DPRINTF(Fetch, "Setting the page table pointer.\n");
330#if !FULL_SYSTEM
331 pTable = pt_ptr;
332#endif
333}
334#endif
335
336template<class Impl>
337void
338DefaultFetch<Impl>::initStage()
339{
340 // Setup PC and nextPC with initial state.
341 for (int tid = 0; tid < numThreads; tid++) {
342 PC[tid] = cpu->readPC(tid);
343 nextPC[tid] = cpu->readNextPC(tid);
344 }
345}
346
347template<class Impl>
348void
349DefaultFetch<Impl>::processCacheCompletion(PacketPtr pkt)
350{
351 unsigned tid = pkt->req->getThreadNum();
352
353 DPRINTF(Fetch, "[tid:%u] Waking up from cache miss.\n",tid);
354
355 // Only change the status if it's still waiting on the icache access
356 // to return.
357 if (fetchStatus[tid] != IcacheWaitResponse ||
358 pkt != memPkt[tid] ||
359 isSwitchedOut()) {
360 ++fetchIcacheSquashes;
361 delete pkt;
362 return;
363 }
364
365 // Wake up the CPU (if it went to sleep and was waiting on this completion
366 // event).
367 cpu->wakeCPU();
368
369 DPRINTF(Activity, "[tid:%u] Activating fetch due to cache completion\n",
370 tid);
371
372 switchToActive();
373
374 // Only switch to IcacheAccessComplete if we're not stalled as well.
375 if (checkStall(tid)) {
376 fetchStatus[tid] = Blocked;
377 } else {
378 fetchStatus[tid] = IcacheAccessComplete;
379 }
380
381// memcpy(cacheData[tid], memReq[tid]->data, memReq[tid]->size);
382
383 // Reset the mem req to NULL.
384 delete pkt->req;
385 delete pkt;
386 memPkt[tid] = NULL;
387}
388
389template <class Impl>
390void
391DefaultFetch<Impl>::switchOut()
392{
393 // Fetch is ready to switch out at any time.
394 switchedOut = true;
395 cpu->signalSwitched();
396}
397
398template <class Impl>
399void
400DefaultFetch<Impl>::doSwitchOut()
401{
402 // Branch predictor needs to have its state cleared.
403 branchPred.switchOut();
404}
405
406template <class Impl>
407void
408DefaultFetch<Impl>::takeOverFrom()
409{
410 // Reset all state
411 for (int i = 0; i < Impl::MaxThreads; ++i) {
412 stalls[i].decode = 0;
413 stalls[i].rename = 0;
414 stalls[i].iew = 0;
415 stalls[i].commit = 0;
416 PC[i] = cpu->readPC(i);
417 nextPC[i] = cpu->readNextPC(i);
418 fetchStatus[i] = Running;
419 }
420 numInst = 0;
421 wroteToTimeBuffer = false;
422 _status = Inactive;
423 switchedOut = false;
424 branchPred.takeOverFrom();
425}
426
427template <class Impl>
428void
429DefaultFetch<Impl>::wakeFromQuiesce()
430{
431 DPRINTF(Fetch, "Waking up from quiesce\n");
432 // Hopefully this is safe
433 // @todo: Allow other threads to wake from quiesce.
434 fetchStatus[0] = Running;
435}
436
437template <class Impl>
438inline void
439DefaultFetch<Impl>::switchToActive()
440{
441 if (_status == Inactive) {
442 DPRINTF(Activity, "Activating stage.\n");
443
444 cpu->activateStage(FullCPU::FetchIdx);
445
446 _status = Active;
447 }
448}
449
450template <class Impl>
451inline void
452DefaultFetch<Impl>::switchToInactive()
453{
454 if (_status == Active) {
455 DPRINTF(Activity, "Deactivating stage.\n");
456
457 cpu->deactivateStage(FullCPU::FetchIdx);
458
459 _status = Inactive;
460 }
461}
462
463template <class Impl>
464bool
465DefaultFetch<Impl>::lookupAndUpdateNextPC(DynInstPtr &inst, Addr &next_PC)
466{
467 // Do branch prediction check here.
468 // A bit of a misnomer...next_PC is actually the current PC until
469 // this function updates it.
470 bool predict_taken;
471
472 if (!inst->isControl()) {
473 next_PC = next_PC + instSize;
474 inst->setPredTarg(next_PC);
475 return false;
476 }
477
478 predict_taken = branchPred.predict(inst, next_PC, inst->threadNumber);
479
480 ++fetchedBranches;
481
482 if (predict_taken) {
483 ++predictedBranches;
484 }
485
486 return predict_taken;
487}
488
489template <class Impl>
490bool
491DefaultFetch<Impl>::fetchCacheLine(Addr fetch_PC, Fault &ret_fault, unsigned tid)
492{
493 Fault fault = NoFault;
494
495#if FULL_SYSTEM
496 // Flag to say whether or not address is physical addr.
497 unsigned flags = cpu->inPalMode(fetch_PC) ? PHYSICAL : 0;
498#else
499 unsigned flags = 0;
500#endif // FULL_SYSTEM
501
502 if (interruptPending && flags == 0 || switchedOut) {
503 // Hold off fetch from getting new instructions while an interrupt
504 // is pending.
505 return false;
506 }
507
508 // Align the fetch PC so it's at the start of a cache block.
509 fetch_PC = icacheBlockAlignPC(fetch_PC);
510
511 // Setup the memReq to do a read of the first instruction's address.
512 // Set the appropriate read size and flags as well.
513 // Build request here.
514 RequestPtr mem_req = new Request(tid, fetch_PC, cacheBlkSize, flags,
515 fetch_PC, cpu->readCpuId(), tid);
516
517 memPkt[tid] = NULL;
518
519 // Translate the instruction request.
520//#if FULL_SYSTEM
521 fault = cpu->translateInstReq(mem_req);
522//#else
523// fault = pTable->translate(memReq[tid]);
524//#endif
525
526 // In the case of faults, the fetch stage may need to stall and wait
527 // for the ITB miss to be handled.
528
529 // If translation was successful, attempt to read the first
530 // instruction.
531 if (fault == NoFault) {
532#if FULL_SYSTEM
533 if (cpu->system->memctrl->badaddr(memReq[tid]->paddr) ||
534 memReq[tid]->flags & UNCACHEABLE) {
535 DPRINTF(Fetch, "Fetch: Bad address %#x (hopefully on a "
536 "misspeculating path)!",
537 memReq[tid]->paddr);
538 ret_fault = TheISA::genMachineCheckFault();
539 return false;
540 }
541#endif
542
543 // Build packet here.
544 PacketPtr data_pkt = new Packet(mem_req,
545 Packet::ReadReq, Packet::Broadcast);
546 data_pkt->dataStatic(cacheData[tid]);
547
548 DPRINTF(Fetch, "Fetch: Doing instruction read.\n");
549
550 fetchedCacheLines++;
551
552 // Now do the timing access to see whether or not the instruction
553 // exists within the cache.
554 if (!icachePort->sendTiming(data_pkt)) {
555 DPRINTF(Fetch, "[tid:%i] Out of MSHRs!\n", tid);
556 ret_fault = NoFault;
557 return false;
558 }
559
560 DPRINTF(Fetch, "Doing cache access.\n");
561
562 lastIcacheStall[tid] = curTick;
563
564 DPRINTF(Activity, "[tid:%i]: Activity: Waiting on I-cache "
565 "response.\n", tid);
566
567 fetchStatus[tid] = IcacheWaitResponse;
568 }
569
570 ret_fault = fault;
571 return true;
572}
573
574template <class Impl>
575inline void
576DefaultFetch<Impl>::doSquash(const Addr &new_PC, unsigned tid)
577{
578 DPRINTF(Fetch, "[tid:%i]: Squashing, setting PC to: %#x.\n",
579 tid, new_PC);
580
581 PC[tid] = new_PC;
582 nextPC[tid] = new_PC + instSize;
583
584 // Clear the icache miss if it's outstanding.
585 if (fetchStatus[tid] == IcacheWaitResponse) {
586 DPRINTF(Fetch, "[tid:%i]: Squashing outstanding Icache miss.\n",
587 tid);
588 delete memPkt[tid];
589 memPkt[tid] = NULL;
590 }
591
592 fetchStatus[tid] = Squashing;
593
594 ++fetchSquashCycles;
595}
596
597template<class Impl>
598void
599DefaultFetch<Impl>::squashFromDecode(const Addr &new_PC,
600 const InstSeqNum &seq_num,
601 unsigned tid)
602{
603 DPRINTF(Fetch, "[tid:%i]: Squashing from decode.\n",tid);
604
605 doSquash(new_PC, tid);
606
607 // Tell the CPU to remove any instructions that are in flight between
608 // fetch and decode.
609 cpu->removeInstsUntil(seq_num, tid);
610}
611
612template<class Impl>
613bool
614DefaultFetch<Impl>::checkStall(unsigned tid) const
615{
616 bool ret_val = false;
617
618 if (cpu->contextSwitch) {
619 DPRINTF(Fetch,"[tid:%i]: Stalling for a context switch.\n",tid);
620 ret_val = true;
621 } else if (stalls[tid].decode) {
622 DPRINTF(Fetch,"[tid:%i]: Stall from Decode stage detected.\n",tid);
623 ret_val = true;
624 } else if (stalls[tid].rename) {
625 DPRINTF(Fetch,"[tid:%i]: Stall from Rename stage detected.\n",tid);
626 ret_val = true;
627 } else if (stalls[tid].iew) {
628 DPRINTF(Fetch,"[tid:%i]: Stall from IEW stage detected.\n",tid);
629 ret_val = true;
630 } else if (stalls[tid].commit) {
631 DPRINTF(Fetch,"[tid:%i]: Stall from Commit stage detected.\n",tid);
632 ret_val = true;
633 }
634
635 return ret_val;
636}
637
638template<class Impl>
639typename DefaultFetch<Impl>::FetchStatus
640DefaultFetch<Impl>::updateFetchStatus()
641{
642 //Check Running
643 list<unsigned>::iterator threads = (*activeThreads).begin();
644
645 while (threads != (*activeThreads).end()) {
646
647 unsigned tid = *threads++;
648
649 if (fetchStatus[tid] == Running ||
650 fetchStatus[tid] == Squashing ||
651 fetchStatus[tid] == IcacheAccessComplete) {
652
653 if (_status == Inactive) {
654 DPRINTF(Activity, "[tid:%i]: Activating stage.\n",tid);
655
656 if (fetchStatus[tid] == IcacheAccessComplete) {
657 DPRINTF(Activity, "[tid:%i]: Activating fetch due to cache"
658 "completion\n",tid);
659 }
660
661 cpu->activateStage(FullCPU::FetchIdx);
662 }
663
664 return Active;
665 }
666 }
667
668 // Stage is switching from active to inactive, notify CPU of it.
669 if (_status == Active) {
670 DPRINTF(Activity, "Deactivating stage.\n");
671
672 cpu->deactivateStage(FullCPU::FetchIdx);
673 }
674
675 return Inactive;
676}
677
678template <class Impl>
679void
680DefaultFetch<Impl>::squash(const Addr &new_PC, unsigned tid)
681{
682 DPRINTF(Fetch, "[tid:%u]: Squash from commit.\n",tid);
683
684 doSquash(new_PC, tid);
685
686 // Tell the CPU to remove any instructions that are not in the ROB.
687 cpu->removeInstsNotInROB(tid);
688}
689
690template <class Impl>
691void
692DefaultFetch<Impl>::tick()
693{
694 list<unsigned>::iterator threads = (*activeThreads).begin();
695 bool status_change = false;
696
697 wroteToTimeBuffer = false;
698
699 while (threads != (*activeThreads).end()) {
700 unsigned tid = *threads++;
701
702 // Check the signals for each thread to determine the proper status
703 // for each thread.
704 bool updated_status = checkSignalsAndUpdate(tid);
705 status_change = status_change || updated_status;
706 }
707
708 DPRINTF(Fetch, "Running stage.\n");
709
710 // Reset the number of the instruction we're fetching.
711 numInst = 0;
712
713 if (fromCommit->commitInfo[0].interruptPending) {
714 interruptPending = true;
715 }
716 if (fromCommit->commitInfo[0].clearInterrupt) {
717 interruptPending = false;
718 }
719
720 for (threadFetched = 0; threadFetched < numFetchingThreads;
721 threadFetched++) {
722 // Fetch each of the actively fetching threads.
723 fetch(status_change);
724 }
725
726 // Record number of instructions fetched this cycle for distribution.
727 fetchNisnDist.sample(numInst);
728
729 if (status_change) {
730 // Change the fetch stage status if there was a status change.
731 _status = updateFetchStatus();
732 }
733
734 // If there was activity this cycle, inform the CPU of it.
735 if (wroteToTimeBuffer || cpu->contextSwitch) {
736 DPRINTF(Activity, "Activity this cycle.\n");
737
738 cpu->activityThisCycle();
739 }
740}
741
742template <class Impl>
743bool
744DefaultFetch<Impl>::checkSignalsAndUpdate(unsigned tid)
745{
746 // Update the per thread stall statuses.
747 if (fromDecode->decodeBlock[tid]) {
748 stalls[tid].decode = true;
749 }
750
751 if (fromDecode->decodeUnblock[tid]) {
752 assert(stalls[tid].decode);
753 assert(!fromDecode->decodeBlock[tid]);
754 stalls[tid].decode = false;
755 }
756
757 if (fromRename->renameBlock[tid]) {
758 stalls[tid].rename = true;
759 }
760
761 if (fromRename->renameUnblock[tid]) {
762 assert(stalls[tid].rename);
763 assert(!fromRename->renameBlock[tid]);
764 stalls[tid].rename = false;
765 }
766
767 if (fromIEW->iewBlock[tid]) {
768 stalls[tid].iew = true;
769 }
770
771 if (fromIEW->iewUnblock[tid]) {
772 assert(stalls[tid].iew);
773 assert(!fromIEW->iewBlock[tid]);
774 stalls[tid].iew = false;
775 }
776
777 if (fromCommit->commitBlock[tid]) {
778 stalls[tid].commit = true;
779 }
780
781 if (fromCommit->commitUnblock[tid]) {
782 assert(stalls[tid].commit);
783 assert(!fromCommit->commitBlock[tid]);
784 stalls[tid].commit = false;
785 }
786
787 // Check squash signals from commit.
788 if (fromCommit->commitInfo[tid].squash) {
789
790 DPRINTF(Fetch, "[tid:%u]: Squashing instructions due to squash "
791 "from commit.\n",tid);
792
793 // In any case, squash.
794 squash(fromCommit->commitInfo[tid].nextPC,tid);
795
796 // Also check if there's a mispredict that happened.
797 if (fromCommit->commitInfo[tid].branchMispredict) {
798 branchPred.squash(fromCommit->commitInfo[tid].doneSeqNum,
799 fromCommit->commitInfo[tid].nextPC,
800 fromCommit->commitInfo[tid].branchTaken,
801 tid);
802 } else {
803 branchPred.squash(fromCommit->commitInfo[tid].doneSeqNum,
804 tid);
805 }
806
807 return true;
808 } else if (fromCommit->commitInfo[tid].doneSeqNum) {
809 // Update the branch predictor if it wasn't a squashed instruction
810 // that was broadcasted.
811 branchPred.update(fromCommit->commitInfo[tid].doneSeqNum, tid);
812 }
813
814 // Check ROB squash signals from commit.
815 if (fromCommit->commitInfo[tid].robSquashing) {
816 DPRINTF(Fetch, "[tid:%u]: ROB is still squashing Thread %u.\n", tid);
817
818 // Continue to squash.
819 fetchStatus[tid] = Squashing;
820
821 return true;
822 }
823
824 // Check squash signals from decode.
825 if (fromDecode->decodeInfo[tid].squash) {
826 DPRINTF(Fetch, "[tid:%u]: Squashing instructions due to squash "
827 "from decode.\n",tid);
828
829 // Update the branch predictor.
830 if (fromDecode->decodeInfo[tid].branchMispredict) {
831 branchPred.squash(fromDecode->decodeInfo[tid].doneSeqNum,
832 fromDecode->decodeInfo[tid].nextPC,
833 fromDecode->decodeInfo[tid].branchTaken,
834 tid);
835 } else {
836 branchPred.squash(fromDecode->decodeInfo[tid].doneSeqNum,
837 tid);
838 }
839
840 if (fetchStatus[tid] != Squashing) {
841 // Squash unless we're already squashing
842 squashFromDecode(fromDecode->decodeInfo[tid].nextPC,
843 fromDecode->decodeInfo[tid].doneSeqNum,
844 tid);
845
846 return true;
847 }
848 }
849
850 if (checkStall(tid) && fetchStatus[tid] != IcacheWaitResponse) {
851 DPRINTF(Fetch, "[tid:%i]: Setting to blocked\n",tid);
852
853 fetchStatus[tid] = Blocked;
854
855 return true;
856 }
857
858 if (fetchStatus[tid] == Blocked ||
859 fetchStatus[tid] == Squashing) {
860 // Switch status to running if fetch isn't being told to block or
861 // squash this cycle.
862 DPRINTF(Fetch, "[tid:%i]: Done squashing, switching to running.\n",
863 tid);
864
865 fetchStatus[tid] = Running;
866
867 return true;
868 }
869
870 // If we've reached this point, we have not gotten any signals that
871 // cause fetch to change its status. Fetch remains the same as before.
872 return false;
873}
874
875template<class Impl>
876void
877DefaultFetch<Impl>::fetch(bool &status_change)
878{
879 //////////////////////////////////////////
880 // Start actual fetch
881 //////////////////////////////////////////
882 int tid = getFetchingThread(fetchPolicy);
883
884 if (tid == -1) {
885 DPRINTF(Fetch,"There are no more threads available to fetch from.\n");
886
887 // Breaks looping condition in tick()
888 threadFetched = numFetchingThreads;
889 return;
890 }
891
892 // The current PC.
893 Addr &fetch_PC = PC[tid];
894
895 // Fault code for memory access.
896 Fault fault = NoFault;
897
898 // If returning from the delay of a cache miss, then update the status
899 // to running, otherwise do the cache access. Possibly move this up
900 // to tick() function.
901 if (fetchStatus[tid] == IcacheAccessComplete) {
902 DPRINTF(Fetch, "[tid:%i]: Icache miss is complete.\n",
903 tid);
904
905 fetchStatus[tid] = Running;
906 status_change = true;
907 } else if (fetchStatus[tid] == Running) {
908 DPRINTF(Fetch, "[tid:%i]: Attempting to translate and read "
909 "instruction, starting at PC %08p.\n",
910 tid, fetch_PC);
911
912 bool fetch_success = fetchCacheLine(fetch_PC, fault, tid);
913 if (!fetch_success) {
914 ++fetchMiscStallCycles;
915 return;
916 }
917 } else {
918 if (fetchStatus[tid] == Idle) {
919 ++fetchIdleCycles;
920 } else if (fetchStatus[tid] == Blocked) {
921 ++fetchBlockedCycles;
922 } else if (fetchStatus[tid] == Squashing) {
923 ++fetchSquashCycles;
924 } else if (fetchStatus[tid] == IcacheWaitResponse) {
925 ++icacheStallCycles;
926 }
927
928 // Status is Idle, Squashing, Blocked, or IcacheWaitResponse, so
929 // fetch should do nothing.
930 return;
931 }
932
933 ++fetchCycles;
934
935 // If we had a stall due to an icache miss, then return.
936 if (fetchStatus[tid] == IcacheWaitResponse) {
937 ++icacheStallCycles;
938 status_change = true;
939 return;
940 }
941
942 Addr next_PC = fetch_PC;
943 InstSeqNum inst_seq;
944 MachInst inst;
945 ExtMachInst ext_inst;
946 // @todo: Fix this hack.
947 unsigned offset = (fetch_PC & cacheBlkMask) & ~3;
948
949 if (fault == NoFault) {
950 // If the read of the first instruction was successful, then grab the
951 // instructions from the rest of the cache line and put them into the
952 // queue heading to decode.
953
954 DPRINTF(Fetch, "[tid:%i]: Adding instructions to queue to "
955 "decode.\n",tid);
956
957 // Need to keep track of whether or not a predicted branch
958 // ended this fetch block.
959 bool predicted_branch = false;
960
961 for (;
962 offset < cacheBlkSize &&
963 numInst < fetchWidth &&
964 !predicted_branch;
965 ++numInst) {
966
967 // Get a sequence number.
968 inst_seq = cpu->getAndIncrementInstSeq();
969
970 // Make sure this is a valid index.
971 assert(offset <= cacheBlkSize - instSize);
972
973 // Get the instruction from the array of the cache line.
974 inst = gtoh(*reinterpret_cast<MachInst *>
975 (&cacheData[tid][offset]));
976
977 ext_inst = TheISA::makeExtMI(inst, fetch_PC);
978
979 // Create a new DynInst from the instruction fetched.
980 DynInstPtr instruction = new DynInst(ext_inst, fetch_PC,
981 next_PC,
982 inst_seq, cpu);
983 instruction->setThread(tid);
984
985 instruction->setASID(tid);
986
987 instruction->setState(cpu->thread[tid]);
988
989 DPRINTF(Fetch, "[tid:%i]: Instruction PC %#x created "
990 "[sn:%lli]\n",
991 tid, instruction->readPC(), inst_seq);
992
993 DPRINTF(Fetch, "[tid:%i]: Instruction is: %s\n",
994 tid, instruction->staticInst->disassemble(fetch_PC));
995
996 instruction->traceData =
997 Trace::getInstRecord(curTick, cpu->xcBase(tid), cpu,
998 instruction->staticInst,
999 instruction->readPC(),tid);
1000
1001 predicted_branch = lookupAndUpdateNextPC(instruction, next_PC);
1002
1003 // Add instruction to the CPU's list of instructions.
1004 instruction->setInstListIt(cpu->addInst(instruction));
1005
1006 // Write the instruction to the first slot in the queue
1007 // that heads to decode.
1008 toDecode->insts[numInst] = instruction;
1009
1010 toDecode->size++;
1011
1012 // Increment stat of fetched instructions.
1013 ++fetchedInsts;
1014
1015 // Move to the next instruction, unless we have a branch.
1016 fetch_PC = next_PC;
1017
1018 if (instruction->isQuiesce()) {
1019 warn("%lli: Quiesce instruction encountered, halting fetch!",
1020 curTick);
1021 fetchStatus[tid] = QuiescePending;
1022 ++numInst;
1023 status_change = true;
1024 break;
1025 }
1026
1027 offset+= instSize;
1028 }
1029 }
1030
1031 if (numInst > 0) {
1032 wroteToTimeBuffer = true;
1033 }
1034
1035 // Now that fetching is completed, update the PC to signify what the next
1036 // cycle will be.
1037 if (fault == NoFault) {
1038 DPRINTF(Fetch, "[tid:%i]: Setting PC to %08p.\n",tid, next_PC);
1039
1040 PC[tid] = next_PC;
1041 nextPC[tid] = next_PC + instSize;
1042 } else {
1043 // We shouldn't be in an icache miss and also have a fault (an ITB
1044 // miss)
1045 if (fetchStatus[tid] == IcacheWaitResponse) {
1046 panic("Fetch should have exited prior to this!");
1047 }
1048
1049 // Send the fault to commit. This thread will not do anything
1050 // until commit handles the fault. The only other way it can
1051 // wake up is if a squash comes along and changes the PC.
1052#if FULL_SYSTEM
1053 assert(numInst != fetchWidth);
1054 // Get a sequence number.
1055 inst_seq = cpu->getAndIncrementInstSeq();
1056 // We will use a nop in order to carry the fault.
1057 ext_inst = TheISA::NoopMachInst;
1058
1059 // Create a new DynInst from the dummy nop.
1060 DynInstPtr instruction = new DynInst(ext_inst, fetch_PC,
1061 next_PC,
1062 inst_seq, cpu);
1063 instruction->setPredTarg(next_PC + instSize);
1064 instruction->setThread(tid);
1065
1066 instruction->setASID(tid);
1067
1068 instruction->setState(cpu->thread[tid]);
1069
1070 instruction->traceData = NULL;
1071
1072 instruction->setInstListIt(cpu->addInst(instruction));
1073
1074 instruction->fault = fault;
1075
1076 toDecode->insts[numInst] = instruction;
1077 toDecode->size++;
1078
1079 DPRINTF(Fetch, "[tid:%i]: Blocked, need to handle the trap.\n",tid);
1080
1081 fetchStatus[tid] = TrapPending;
1082 status_change = true;
1083
1084 warn("%lli fault (%d) detected @ PC %08p", curTick, fault, PC[tid]);
1085#else // !FULL_SYSTEM
1086 fatal("fault (%d) detected @ PC %08p", fault, PC[tid]);
1087#endif // FULL_SYSTEM
1088 }
1089}
1090
1091
1092///////////////////////////////////////
1093// //
1094// SMT FETCH POLICY MAINTAINED HERE //
1095// //
1096///////////////////////////////////////
1097template<class Impl>
1098int
1099DefaultFetch<Impl>::getFetchingThread(FetchPriority &fetch_priority)
1100{
1101 if (numThreads > 1) {
1102 switch (fetch_priority) {
1103
1104 case SingleThread:
1105 return 0;
1106
1107 case RoundRobin:
1108 return roundRobin();
1109
1110 case IQ:
1111 return iqCount();
1112
1113 case LSQ:
1114 return lsqCount();
1115
1116 case Branch:
1117 return branchCount();
1118
1119 default:
1120 return -1;
1121 }
1122 } else {
1123 int tid = *((*activeThreads).begin());
1124
1125 if (fetchStatus[tid] == Running ||
1126 fetchStatus[tid] == IcacheAccessComplete ||
1127 fetchStatus[tid] == Idle) {
1128 return tid;
1129 } else {
1130 return -1;
1131 }
1132 }
1133
1134}
1135
1136
1137template<class Impl>
1138int
1139DefaultFetch<Impl>::roundRobin()
1140{
1141 list<unsigned>::iterator pri_iter = priorityList.begin();
1142 list<unsigned>::iterator end = priorityList.end();
1143
1144 int high_pri;
1145
1146 while (pri_iter != end) {
1147 high_pri = *pri_iter;
1148
1149 assert(high_pri <= numThreads);
1150
1151 if (fetchStatus[high_pri] == Running ||
1152 fetchStatus[high_pri] == IcacheAccessComplete ||
1153 fetchStatus[high_pri] == Idle) {
1154
1155 priorityList.erase(pri_iter);
1156 priorityList.push_back(high_pri);
1157
1158 return high_pri;
1159 }
1160
1161 pri_iter++;
1162 }
1163
1164 return -1;
1165}
1166
1167template<class Impl>
1168int
1169DefaultFetch<Impl>::iqCount()
1170{
1171 priority_queue<unsigned> PQ;
1172
1173 list<unsigned>::iterator threads = (*activeThreads).begin();
1174
1175 while (threads != (*activeThreads).end()) {
1176 unsigned tid = *threads++;
1177
1178 PQ.push(fromIEW->iewInfo[tid].iqCount);
1179 }
1180
1181 while (!PQ.empty()) {
1182
1183 unsigned high_pri = PQ.top();
1184
1185 if (fetchStatus[high_pri] == Running ||
1186 fetchStatus[high_pri] == IcacheAccessComplete ||
1187 fetchStatus[high_pri] == Idle)
1188 return high_pri;
1189 else
1190 PQ.pop();
1191
1192 }
1193
1194 return -1;
1195}
1196
1197template<class Impl>
1198int
1199DefaultFetch<Impl>::lsqCount()
1200{
1201 priority_queue<unsigned> PQ;
1202
1203
1204 list<unsigned>::iterator threads = (*activeThreads).begin();
1205
1206 while (threads != (*activeThreads).end()) {
1207 unsigned tid = *threads++;
1208
1209 PQ.push(fromIEW->iewInfo[tid].ldstqCount);
1210 }
1211
1212 while (!PQ.empty()) {
1213
1214 unsigned high_pri = PQ.top();
1215
1216 if (fetchStatus[high_pri] == Running ||
1217 fetchStatus[high_pri] == IcacheAccessComplete ||
1218 fetchStatus[high_pri] == Idle)
1219 return high_pri;
1220 else
1221 PQ.pop();
1222
1223 }
1224
1225 return -1;
1226}
1227
1228template<class Impl>
1229int
1230DefaultFetch<Impl>::branchCount()
1231{
1232 list<unsigned>::iterator threads = (*activeThreads).begin();
1233
1234 return *threads;
1235}