1/*
2 * Copyright (c) 2010-2014 ARM Limited
3 * Copyright (c) 2012-2013 AMD
4 * All rights reserved.
5 *
6 * The license below extends only to copyright in the software and shall
7 * not be construed as granting a license to any other intellectual
8 * property including but not limited to intellectual property relating
9 * to a hardware implementation of the functionality of the software
10 * licensed hereunder. You may use the software subject to the license
11 * terms below provided that you ensure that this notice is replicated
12 * unmodified and in its entirety in all distributions of the software,
13 * modified or unmodified, in source code or in binary form.
14 *
15 * Copyright (c) 2004-2006 The Regents of The University of Michigan
16 * All rights reserved.
17 *
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions are
20 * met: redistributions of source code must retain the above copyright
21 * notice, this list of conditions and the following disclaimer;
22 * redistributions in binary form must reproduce the above copyright
23 * notice, this list of conditions and the following disclaimer in the
24 * documentation and/or other materials provided with the distribution;
25 * neither the name of the copyright holders nor the names of its
26 * contributors may be used to endorse or promote products derived from
27 * this software without specific prior written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
30 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
31 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
32 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
33 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
34 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
35 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
36 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
37 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
38 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
39 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
40 *
41 * Authors: Kevin Lim
42 * Korey Sewell
43 */
44
45#ifndef __CPU_O3_FETCH_IMPL_HH__
46#define __CPU_O3_FETCH_IMPL_HH__
47
48#include <algorithm>
49#include <cstring>
50#include <list>
51#include <map>
52#include <queue>
53
54#include "arch/isa_traits.hh"
55#include "arch/tlb.hh"
56#include "arch/utility.hh"
57#include "arch/vtophys.hh"
58#include "base/random.hh"
59#include "base/types.hh"
60#include "config/the_isa.hh"
61#include "cpu/base.hh"
62//#include "cpu/checker/cpu.hh"
63#include "cpu/o3/fetch.hh"
64#include "cpu/exetrace.hh"
65#include "debug/Activity.hh"
66#include "debug/Drain.hh"
67#include "debug/Fetch.hh"
68#include "debug/O3PipeView.hh"
69#include "mem/packet.hh"
70#include "params/DerivO3CPU.hh"
71#include "sim/byteswap.hh"
72#include "sim/core.hh"
73#include "sim/eventq.hh"
74#include "sim/full_system.hh"
75#include "sim/system.hh"
76#include "cpu/o3/isa_specific.hh"
77
78using namespace std;
79
80template<class Impl>
81DefaultFetch<Impl>::DefaultFetch(O3CPU *_cpu, DerivO3CPUParams *params)
82 : cpu(_cpu),
83 decodeToFetchDelay(params->decodeToFetchDelay),
84 renameToFetchDelay(params->renameToFetchDelay),
85 iewToFetchDelay(params->iewToFetchDelay),
86 commitToFetchDelay(params->commitToFetchDelay),
87 fetchWidth(params->fetchWidth),
88 decodeWidth(params->decodeWidth),
89 retryPkt(NULL),
90 retryTid(InvalidThreadID),
91 cacheBlkSize(cpu->cacheLineSize()),
92 fetchBufferSize(params->fetchBufferSize),
93 fetchBufferMask(fetchBufferSize - 1),
94 fetchQueueSize(params->fetchQueueSize),
95 numThreads(params->numThreads),
96 numFetchingThreads(params->smtNumFetchingThreads),
97 finishTranslationEvent(this)
98{
99 if (numThreads > Impl::MaxThreads)
100 fatal("numThreads (%d) is larger than compiled limit (%d),\n"
101 "\tincrease MaxThreads in src/cpu/o3/impl.hh\n",
102 numThreads, static_cast<int>(Impl::MaxThreads));
103 if (fetchWidth > Impl::MaxWidth)
104 fatal("fetchWidth (%d) is larger than compiled limit (%d),\n"
105 "\tincrease MaxWidth in src/cpu/o3/impl.hh\n",
106 fetchWidth, static_cast<int>(Impl::MaxWidth));
107 if (fetchBufferSize > cacheBlkSize)
108 fatal("fetch buffer size (%u bytes) is greater than the cache "
109 "block size (%u bytes)\n", fetchBufferSize, cacheBlkSize);
110 if (cacheBlkSize % fetchBufferSize)
111 fatal("cache block (%u bytes) is not a multiple of the "
112 "fetch buffer (%u bytes)\n", cacheBlkSize, fetchBufferSize);
113
114 std::string policy = params->smtFetchPolicy;
115
116 // Convert string to lowercase
117 std::transform(policy.begin(), policy.end(), policy.begin(),
118 (int(*)(int)) tolower);
119
120 // Figure out fetch policy
121 if (policy == "singlethread") {
122 fetchPolicy = SingleThread;
123 if (numThreads > 1)
124 panic("Invalid Fetch Policy for a SMT workload.");
125 } else if (policy == "roundrobin") {
126 fetchPolicy = RoundRobin;
127 DPRINTF(Fetch, "Fetch policy set to Round Robin\n");
128 } else if (policy == "branch") {
129 fetchPolicy = Branch;
130 DPRINTF(Fetch, "Fetch policy set to Branch Count\n");
131 } else if (policy == "iqcount") {
132 fetchPolicy = IQ;
133 DPRINTF(Fetch, "Fetch policy set to IQ count\n");
134 } else if (policy == "lsqcount") {
135 fetchPolicy = LSQ;
136 DPRINTF(Fetch, "Fetch policy set to LSQ count\n");
137 } else {
138 fatal("Invalid Fetch Policy. Options Are: {SingleThread,"
139 " RoundRobin,LSQcount,IQcount}\n");
140 }
141
142 // Get the size of an instruction.
143 instSize = sizeof(TheISA::MachInst);
144
145 for (int i = 0; i < Impl::MaxThreads; i++) {
146 decoder[i] = NULL;
147 fetchBuffer[i] = NULL;
148 fetchBufferPC[i] = 0;
149 fetchBufferValid[i] = false;
150 }
151
152 branchPred = params->branchPred;
153
154 for (ThreadID tid = 0; tid < numThreads; tid++) {
155 decoder[tid] = new TheISA::Decoder(params->isa[tid]);
156 // Create space to buffer the cache line data,
157 // which may not hold the entire cache line.
158 fetchBuffer[tid] = new uint8_t[fetchBufferSize];
159 }
160}
161
162template <class Impl>
163std::string
164DefaultFetch<Impl>::name() const
165{
166 return cpu->name() + ".fetch";
167}
168
169template <class Impl>
170void
171DefaultFetch<Impl>::regProbePoints()
172{
173 ppFetch = new ProbePointArg<DynInstPtr>(cpu->getProbeManager(), "Fetch");
174 ppFetchRequestSent = new ProbePointArg<RequestPtr>(cpu->getProbeManager(),
175 "FetchRequest");
176
177}
178
179template <class Impl>
180void
181DefaultFetch<Impl>::regStats()
182{
183 icacheStallCycles
184 .name(name() + ".icacheStallCycles")
185 .desc("Number of cycles fetch is stalled on an Icache miss")
186 .prereq(icacheStallCycles);
187
188 fetchedInsts
189 .name(name() + ".Insts")
190 .desc("Number of instructions fetch has processed")
191 .prereq(fetchedInsts);
192
193 fetchedBranches
194 .name(name() + ".Branches")
195 .desc("Number of branches that fetch encountered")
196 .prereq(fetchedBranches);
197
198 predictedBranches
199 .name(name() + ".predictedBranches")
200 .desc("Number of branches that fetch has predicted taken")
201 .prereq(predictedBranches);
202
203 fetchCycles
204 .name(name() + ".Cycles")
205 .desc("Number of cycles fetch has run and was not squashing or"
206 " blocked")
207 .prereq(fetchCycles);
208
209 fetchSquashCycles
210 .name(name() + ".SquashCycles")
211 .desc("Number of cycles fetch has spent squashing")
212 .prereq(fetchSquashCycles);
213
214 fetchTlbCycles
215 .name(name() + ".TlbCycles")
216 .desc("Number of cycles fetch has spent waiting for tlb")
217 .prereq(fetchTlbCycles);
218
219 fetchIdleCycles
220 .name(name() + ".IdleCycles")
221 .desc("Number of cycles fetch was idle")
222 .prereq(fetchIdleCycles);
223
224 fetchBlockedCycles
225 .name(name() + ".BlockedCycles")
226 .desc("Number of cycles fetch has spent blocked")
227 .prereq(fetchBlockedCycles);
228
229 fetchedCacheLines
230 .name(name() + ".CacheLines")
231 .desc("Number of cache lines fetched")
232 .prereq(fetchedCacheLines);
233
234 fetchMiscStallCycles
235 .name(name() + ".MiscStallCycles")
236 .desc("Number of cycles fetch has spent waiting on interrupts, or "
237 "bad addresses, or out of MSHRs")
238 .prereq(fetchMiscStallCycles);
239
240 fetchPendingDrainCycles
241 .name(name() + ".PendingDrainCycles")
242 .desc("Number of cycles fetch has spent waiting on pipes to drain")
243 .prereq(fetchPendingDrainCycles);
244
245 fetchNoActiveThreadStallCycles
246 .name(name() + ".NoActiveThreadStallCycles")
247 .desc("Number of stall cycles due to no active thread to fetch from")
248 .prereq(fetchNoActiveThreadStallCycles);
249
250 fetchPendingTrapStallCycles
251 .name(name() + ".PendingTrapStallCycles")
252 .desc("Number of stall cycles due to pending traps")
253 .prereq(fetchPendingTrapStallCycles);
254
255 fetchPendingQuiesceStallCycles
256 .name(name() + ".PendingQuiesceStallCycles")
257 .desc("Number of stall cycles due to pending quiesce instructions")
258 .prereq(fetchPendingQuiesceStallCycles);
259
260 fetchIcacheWaitRetryStallCycles
261 .name(name() + ".IcacheWaitRetryStallCycles")
262 .desc("Number of stall cycles due to full MSHR")
263 .prereq(fetchIcacheWaitRetryStallCycles);
264
265 fetchIcacheSquashes
266 .name(name() + ".IcacheSquashes")
267 .desc("Number of outstanding Icache misses that were squashed")
268 .prereq(fetchIcacheSquashes);
269
270 fetchTlbSquashes
271 .name(name() + ".ItlbSquashes")
272 .desc("Number of outstanding ITLB misses that were squashed")
273 .prereq(fetchTlbSquashes);
274
275 fetchNisnDist
276 .init(/* base value */ 0,
277 /* last value */ fetchWidth,
278 /* bucket size */ 1)
279 .name(name() + ".rateDist")
280 .desc("Number of instructions fetched each cycle (Total)")
281 .flags(Stats::pdf);
282
283 idleRate
284 .name(name() + ".idleRate")
285 .desc("Percent of cycles fetch was idle")
286 .prereq(idleRate);
287 idleRate = fetchIdleCycles * 100 / cpu->numCycles;
288
289 branchRate
290 .name(name() + ".branchRate")
291 .desc("Number of branch fetches per cycle")
292 .flags(Stats::total);
293 branchRate = fetchedBranches / cpu->numCycles;
294
295 fetchRate
296 .name(name() + ".rate")
297 .desc("Number of inst fetches per cycle")
298 .flags(Stats::total);
299 fetchRate = fetchedInsts / cpu->numCycles;
300}
301
302template<class Impl>
303void
304DefaultFetch<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *time_buffer)
305{
306 timeBuffer = time_buffer;
307
308 // Create wires to get information from proper places in time buffer.
309 fromDecode = timeBuffer->getWire(-decodeToFetchDelay);
310 fromRename = timeBuffer->getWire(-renameToFetchDelay);
311 fromIEW = timeBuffer->getWire(-iewToFetchDelay);
312 fromCommit = timeBuffer->getWire(-commitToFetchDelay);
313}
314
315template<class Impl>
316void
317DefaultFetch<Impl>::setActiveThreads(std::list<ThreadID> *at_ptr)
318{
319 activeThreads = at_ptr;
320}
321
322template<class Impl>
323void
324DefaultFetch<Impl>::setFetchQueue(TimeBuffer<FetchStruct> *ftb_ptr)
325{
326 // Create wire to write information to proper place in fetch time buf.
327 toDecode = ftb_ptr->getWire(0);
328}
329
330template<class Impl>
331void
332DefaultFetch<Impl>::startupStage()
333{
334 assert(priorityList.empty());
335 resetStage();
336
337 // Fetch needs to start fetching instructions at the very beginning,
338 // so it must start up in active state.
339 switchToActive();
340}
341
342template<class Impl>
343void
344DefaultFetch<Impl>::resetStage()
345{
346 numInst = 0;
347 interruptPending = false;
348 cacheBlocked = false;
349
350 priorityList.clear();
351
352 // Setup PC and nextPC with initial state.
353 for (ThreadID tid = 0; tid < numThreads; ++tid) {
354 fetchStatus[tid] = Running;
355 pc[tid] = cpu->pcState(tid);
356 fetchOffset[tid] = 0;
357 macroop[tid] = NULL;
358
359 delayedCommit[tid] = false;
360 memReq[tid] = NULL;
361
362 stalls[tid].decode = false;
363 stalls[tid].drain = false;
364
365 fetchBufferPC[tid] = 0;
366 fetchBufferValid[tid] = false;
367
368 fetchQueue[tid].clear();
369
370 priorityList.push_back(tid);
371 }
372
373 wroteToTimeBuffer = false;
374 _status = Inactive;
375}
376
377template<class Impl>
378void
379DefaultFetch<Impl>::processCacheCompletion(PacketPtr pkt)
380{
381 ThreadID tid = cpu->contextToThread(pkt->req->contextId());
382
383 DPRINTF(Fetch, "[tid:%u] Waking up from cache miss.\n", tid);
384 assert(!cpu->switchedOut());
385
386 // Only change the status if it's still waiting on the icache access
387 // to return.
388 if (fetchStatus[tid] != IcacheWaitResponse ||
389 pkt->req != memReq[tid]) {
390 ++fetchIcacheSquashes;
391 delete pkt->req;
392 delete pkt;
393 return;
394 }
395
396 memcpy(fetchBuffer[tid], pkt->getConstPtr<uint8_t>(), fetchBufferSize);
397 fetchBufferValid[tid] = true;
398
399 // Wake up the CPU (if it went to sleep and was waiting on
400 // this completion event).
401 cpu->wakeCPU();
402
403 DPRINTF(Activity, "[tid:%u] Activating fetch due to cache completion\n",
404 tid);
405
406 switchToActive();
407
408 // Only switch to IcacheAccessComplete if we're not stalled as well.
409 if (checkStall(tid)) {
410 fetchStatus[tid] = Blocked;
411 } else {
412 fetchStatus[tid] = IcacheAccessComplete;
413 }
414
415 pkt->req->setAccessLatency();
416 cpu->ppInstAccessComplete->notify(pkt);
417 // Reset the mem req to NULL.
418 delete pkt->req;
419 delete pkt;
420 memReq[tid] = NULL;
421}
422
423template <class Impl>
424void
425DefaultFetch<Impl>::drainResume()
426{
427 for (ThreadID i = 0; i < numThreads; ++i)
428 stalls[i].drain = false;
429}
430
431template <class Impl>
432void
433DefaultFetch<Impl>::drainSanityCheck() const
434{
435 assert(isDrained());
436 assert(retryPkt == NULL);
437 assert(retryTid == InvalidThreadID);
438 assert(!cacheBlocked);
439 assert(!interruptPending);
440
441 for (ThreadID i = 0; i < numThreads; ++i) {
442 assert(!memReq[i]);
443 assert(fetchStatus[i] == Idle || stalls[i].drain);
444 }
445
446 branchPred->drainSanityCheck();
447}
448
449template <class Impl>
450bool
451DefaultFetch<Impl>::isDrained() const
452{
453 /* Make sure that threads are either idle of that the commit stage
454 * has signaled that draining has completed by setting the drain
455 * stall flag. This effectively forces the pipeline to be disabled
456 * until the whole system is drained (simulation may continue to
457 * drain other components).
458 */
459 for (ThreadID i = 0; i < numThreads; ++i) {
460 // Verify fetch queues are drained
461 if (!fetchQueue[i].empty())
462 return false;
463
464 // Return false if not idle or drain stalled
465 if (fetchStatus[i] != Idle) {
466 if (fetchStatus[i] == Blocked && stalls[i].drain)
467 continue;
468 else
469 return false;
470 }
471 }
472
473 /* The pipeline might start up again in the middle of the drain
474 * cycle if the finish translation event is scheduled, so make
475 * sure that's not the case.
476 */
477 return !finishTranslationEvent.scheduled();
478}
479
480template <class Impl>
481void
482DefaultFetch<Impl>::takeOverFrom()
483{
484 assert(cpu->getInstPort().isConnected());
485 resetStage();
486
487}
488
489template <class Impl>
490void
491DefaultFetch<Impl>::drainStall(ThreadID tid)
492{
493 assert(cpu->isDraining());
494 assert(!stalls[tid].drain);
495 DPRINTF(Drain, "%i: Thread drained.\n", tid);
496 stalls[tid].drain = true;
497}
498
499template <class Impl>
500void
501DefaultFetch<Impl>::wakeFromQuiesce()
502{
503 DPRINTF(Fetch, "Waking up from quiesce\n");
504 // Hopefully this is safe
505 // @todo: Allow other threads to wake from quiesce.
506 fetchStatus[0] = Running;
507}
508
509template <class Impl>
510inline void
511DefaultFetch<Impl>::switchToActive()
512{
513 if (_status == Inactive) {
514 DPRINTF(Activity, "Activating stage.\n");
515
516 cpu->activateStage(O3CPU::FetchIdx);
517
518 _status = Active;
519 }
520}
521
522template <class Impl>
523inline void
524DefaultFetch<Impl>::switchToInactive()
525{
526 if (_status == Active) {
527 DPRINTF(Activity, "Deactivating stage.\n");
528
529 cpu->deactivateStage(O3CPU::FetchIdx);
530
531 _status = Inactive;
532 }
533}
534
535template <class Impl>
536void
537DefaultFetch<Impl>::deactivateThread(ThreadID tid)
538{
539 // Update priority list
540 auto thread_it = std::find(priorityList.begin(), priorityList.end(), tid);
541 if (thread_it != priorityList.end()) {
542 priorityList.erase(thread_it);
543 }
544}
545
546template <class Impl>
547bool
548DefaultFetch<Impl>::lookupAndUpdateNextPC(
549 DynInstPtr &inst, TheISA::PCState &nextPC)
550{
551 // Do branch prediction check here.
552 // A bit of a misnomer...next_PC is actually the current PC until
553 // this function updates it.
554 bool predict_taken;
555
556 if (!inst->isControl()) {
557 TheISA::advancePC(nextPC, inst->staticInst);
558 inst->setPredTarg(nextPC);
559 inst->setPredTaken(false);
560 return false;
561 }
562
563 ThreadID tid = inst->threadNumber;
564 predict_taken = branchPred->predict(inst->staticInst, inst->seqNum,
565 nextPC, tid);
566
567 if (predict_taken) {
568 DPRINTF(Fetch, "[tid:%i]: [sn:%i]: Branch predicted to be taken to %s.\n",
569 tid, inst->seqNum, nextPC);
570 } else {
571 DPRINTF(Fetch, "[tid:%i]: [sn:%i]:Branch predicted to be not taken.\n",
572 tid, inst->seqNum);
573 }
574
575 DPRINTF(Fetch, "[tid:%i]: [sn:%i] Branch predicted to go to %s.\n",
576 tid, inst->seqNum, nextPC);
577 inst->setPredTarg(nextPC);
578 inst->setPredTaken(predict_taken);
579
580 ++fetchedBranches;
581
582 if (predict_taken) {
583 ++predictedBranches;
584 }
585
586 return predict_taken;
587}
588
589template <class Impl>
590bool
591DefaultFetch<Impl>::fetchCacheLine(Addr vaddr, ThreadID tid, Addr pc)
592{
593 Fault fault = NoFault;
594
595 assert(!cpu->switchedOut());
596
597 // @todo: not sure if these should block translation.
598 //AlphaDep
599 if (cacheBlocked) {
600 DPRINTF(Fetch, "[tid:%i] Can't fetch cache line, cache blocked\n",
601 tid);
602 return false;
603 } else if (checkInterrupt(pc) && !delayedCommit[tid]) {
604 // Hold off fetch from getting new instructions when:
605 // Cache is blocked, or
606 // while an interrupt is pending and we're not in PAL mode, or
607 // fetch is switched out.
608 DPRINTF(Fetch, "[tid:%i] Can't fetch cache line, interrupt pending\n",
609 tid);
610 return false;
611 }
612
613 // Align the fetch address to the start of a fetch buffer segment.
614 Addr fetchBufferBlockPC = fetchBufferAlignPC(vaddr);
615
616 DPRINTF(Fetch, "[tid:%i] Fetching cache line %#x for addr %#x\n",
617 tid, fetchBufferBlockPC, vaddr);
618
619 // Setup the memReq to do a read of the first instruction's address.
620 // Set the appropriate read size and flags as well.
621 // Build request here.
622 RequestPtr mem_req =
623 new Request(tid, fetchBufferBlockPC, fetchBufferSize,
624 Request::INST_FETCH, cpu->instMasterId(), pc,
625 cpu->thread[tid]->contextId());
626
627 mem_req->taskId(cpu->taskId());
628
629 memReq[tid] = mem_req;
630
631 // Initiate translation of the icache block
632 fetchStatus[tid] = ItlbWait;
633 FetchTranslation *trans = new FetchTranslation(this);
634 cpu->itb->translateTiming(mem_req, cpu->thread[tid]->getTC(),
635 trans, BaseTLB::Execute);
636 return true;
637}
638
639template <class Impl>
640void
641DefaultFetch<Impl>::finishTranslation(const Fault &fault, RequestPtr mem_req)
642{
643 ThreadID tid = cpu->contextToThread(mem_req->contextId());
644 Addr fetchBufferBlockPC = mem_req->getVaddr();
645
646 assert(!cpu->switchedOut());
647
648 // Wake up CPU if it was idle
649 cpu->wakeCPU();
650
651 if (fetchStatus[tid] != ItlbWait || mem_req != memReq[tid] ||
652 mem_req->getVaddr() != memReq[tid]->getVaddr()) {
653 DPRINTF(Fetch, "[tid:%i] Ignoring itlb completed after squash\n",
654 tid);
655 ++fetchTlbSquashes;
656 delete mem_req;
657 return;
658 }
659
660
661 // If translation was successful, attempt to read the icache block.
662 if (fault == NoFault) {
663 // Check that we're not going off into random memory
664 // If we have, just wait around for commit to squash something and put
665 // us on the right track
666 if (!cpu->system->isMemAddr(mem_req->getPaddr())) {
667 warn("Address %#x is outside of physical memory, stopping fetch\n",
668 mem_req->getPaddr());
669 fetchStatus[tid] = NoGoodAddr;
670 delete mem_req;
671 memReq[tid] = NULL;
672 return;
673 }
674
675 // Build packet here.
676 PacketPtr data_pkt = new Packet(mem_req, MemCmd::ReadReq);
677 data_pkt->dataDynamic(new uint8_t[fetchBufferSize]);
678
679 fetchBufferPC[tid] = fetchBufferBlockPC;
680 fetchBufferValid[tid] = false;
681 DPRINTF(Fetch, "Fetch: Doing instruction read.\n");
682
683 fetchedCacheLines++;
684
685 // Access the cache.
686 if (!cpu->getInstPort().sendTimingReq(data_pkt)) {
687 assert(retryPkt == NULL);
688 assert(retryTid == InvalidThreadID);
689 DPRINTF(Fetch, "[tid:%i] Out of MSHRs!\n", tid);
690
691 fetchStatus[tid] = IcacheWaitRetry;
692 retryPkt = data_pkt;
693 retryTid = tid;
694 cacheBlocked = true;
695 } else {
696 DPRINTF(Fetch, "[tid:%i]: Doing Icache access.\n", tid);
697 DPRINTF(Activity, "[tid:%i]: Activity: Waiting on I-cache "
698 "response.\n", tid);
699 lastIcacheStall[tid] = curTick();
700 fetchStatus[tid] = IcacheWaitResponse;
701 // Notify Fetch Request probe when a packet containing a fetch
702 // request is successfully sent
703 ppFetchRequestSent->notify(mem_req);
704 }
705 } else {
706 // Don't send an instruction to decode if we can't handle it.
707 if (!(numInst < fetchWidth) || !(fetchQueue[tid].size() < fetchQueueSize)) {
708 assert(!finishTranslationEvent.scheduled());
709 finishTranslationEvent.setFault(fault);
710 finishTranslationEvent.setReq(mem_req);
711 cpu->schedule(finishTranslationEvent,
712 cpu->clockEdge(Cycles(1)));
713 return;
714 }
715 DPRINTF(Fetch, "[tid:%i] Got back req with addr %#x but expected %#x\n",
716 tid, mem_req->getVaddr(), memReq[tid]->getVaddr());
717 // Translation faulted, icache request won't be sent.
718 delete mem_req;
719 memReq[tid] = NULL;
720
721 // Send the fault to commit. This thread will not do anything
722 // until commit handles the fault. The only other way it can
723 // wake up is if a squash comes along and changes the PC.
724 TheISA::PCState fetchPC = pc[tid];
725
726 DPRINTF(Fetch, "[tid:%i]: Translation faulted, building noop.\n", tid);
727 // We will use a nop in ordier to carry the fault.
728 DynInstPtr instruction = buildInst(tid,
729 decoder[tid]->decode(TheISA::NoopMachInst, fetchPC.instAddr()),
730 NULL, fetchPC, fetchPC, false);
731
732 instruction->setPredTarg(fetchPC);
733 instruction->fault = fault;
734 wroteToTimeBuffer = true;
735
736 DPRINTF(Activity, "Activity this cycle.\n");
737 cpu->activityThisCycle();
738
739 fetchStatus[tid] = TrapPending;
740
741 DPRINTF(Fetch, "[tid:%i]: Blocked, need to handle the trap.\n", tid);
742 DPRINTF(Fetch, "[tid:%i]: fault (%s) detected @ PC %s.\n",
743 tid, fault->name(), pc[tid]);
744 }
745 _status = updateFetchStatus();
746}
747
748template <class Impl>
749inline void
750DefaultFetch<Impl>::doSquash(const TheISA::PCState &newPC,
751 const DynInstPtr squashInst, ThreadID tid)
752{
753 DPRINTF(Fetch, "[tid:%i]: Squashing, setting PC to: %s.\n",
754 tid, newPC);
755
756 pc[tid] = newPC;
757 fetchOffset[tid] = 0;
758 if (squashInst && squashInst->pcState().instAddr() == newPC.instAddr())
759 macroop[tid] = squashInst->macroop;
760 else
761 macroop[tid] = NULL;
762 decoder[tid]->reset();
763
764 // Clear the icache miss if it's outstanding.
765 if (fetchStatus[tid] == IcacheWaitResponse) {
766 DPRINTF(Fetch, "[tid:%i]: Squashing outstanding Icache miss.\n",
767 tid);
768 memReq[tid] = NULL;
769 } else if (fetchStatus[tid] == ItlbWait) {
770 DPRINTF(Fetch, "[tid:%i]: Squashing outstanding ITLB miss.\n",
771 tid);
772 memReq[tid] = NULL;
773 }
774
775 // Get rid of the retrying packet if it was from this thread.
776 if (retryTid == tid) {
777 assert(cacheBlocked);
778 if (retryPkt) {
779 delete retryPkt->req;
780 delete retryPkt;
781 }
782 retryPkt = NULL;
783 retryTid = InvalidThreadID;
784 }
785
786 fetchStatus[tid] = Squashing;
787
788 // Empty fetch queue
789 fetchQueue[tid].clear();
790
791 // microops are being squashed, it is not known wheather the
792 // youngest non-squashed microop was marked delayed commit
793 // or not. Setting the flag to true ensures that the
794 // interrupts are not handled when they cannot be, though
795 // some opportunities to handle interrupts may be missed.
796 delayedCommit[tid] = true;
797
798 ++fetchSquashCycles;
799}
800
801template<class Impl>
802void
803DefaultFetch<Impl>::squashFromDecode(const TheISA::PCState &newPC,
804 const DynInstPtr squashInst,
805 const InstSeqNum seq_num, ThreadID tid)
806{
807 DPRINTF(Fetch, "[tid:%i]: Squashing from decode.\n", tid);
808
809 doSquash(newPC, squashInst, tid);
810
811 // Tell the CPU to remove any instructions that are in flight between
812 // fetch and decode.
813 cpu->removeInstsUntil(seq_num, tid);
814}
815
816template<class Impl>
817bool
818DefaultFetch<Impl>::checkStall(ThreadID tid) const
819{
820 bool ret_val = false;
821
822 if (stalls[tid].drain) {
823 assert(cpu->isDraining());
824 DPRINTF(Fetch,"[tid:%i]: Drain stall detected.\n",tid);
825 ret_val = true;
826 }
827
828 return ret_val;
829}
830
831template<class Impl>
832typename DefaultFetch<Impl>::FetchStatus
833DefaultFetch<Impl>::updateFetchStatus()
834{
835 //Check Running
836 list<ThreadID>::iterator threads = activeThreads->begin();
837 list<ThreadID>::iterator end = activeThreads->end();
838
839 while (threads != end) {
840 ThreadID tid = *threads++;
841
842 if (fetchStatus[tid] == Running ||
843 fetchStatus[tid] == Squashing ||
844 fetchStatus[tid] == IcacheAccessComplete) {
845
846 if (_status == Inactive) {
847 DPRINTF(Activity, "[tid:%i]: Activating stage.\n",tid);
848
849 if (fetchStatus[tid] == IcacheAccessComplete) {
850 DPRINTF(Activity, "[tid:%i]: Activating fetch due to cache"
851 "completion\n",tid);
852 }
853
854 cpu->activateStage(O3CPU::FetchIdx);
855 }
856
857 return Active;
858 }
859 }
860
861 // Stage is switching from active to inactive, notify CPU of it.
862 if (_status == Active) {
863 DPRINTF(Activity, "Deactivating stage.\n");
864
865 cpu->deactivateStage(O3CPU::FetchIdx);
866 }
867
868 return Inactive;
869}
870
871template <class Impl>
872void
873DefaultFetch<Impl>::squash(const TheISA::PCState &newPC,
874 const InstSeqNum seq_num, DynInstPtr squashInst,
875 ThreadID tid)
876{
877 DPRINTF(Fetch, "[tid:%u]: Squash from commit.\n", tid);
878
879 doSquash(newPC, squashInst, tid);
880
881 // Tell the CPU to remove any instructions that are not in the ROB.
882 cpu->removeInstsNotInROB(tid);
883}
884
885template <class Impl>
886void
887DefaultFetch<Impl>::tick()
888{
889 list<ThreadID>::iterator threads = activeThreads->begin();
890 list<ThreadID>::iterator end = activeThreads->end();
891 bool status_change = false;
892
893 wroteToTimeBuffer = false;
894
895 for (ThreadID i = 0; i < numThreads; ++i) {
896 issuePipelinedIfetch[i] = false;
897 }
898
899 while (threads != end) {
900 ThreadID tid = *threads++;
901
902 // Check the signals for each thread to determine the proper status
903 // for each thread.
904 bool updated_status = checkSignalsAndUpdate(tid);
905 status_change = status_change || updated_status;
906 }
907
908 DPRINTF(Fetch, "Running stage.\n");
909
910 if (FullSystem) {
911 if (fromCommit->commitInfo[0].interruptPending) {
912 interruptPending = true;
913 }
914
915 if (fromCommit->commitInfo[0].clearInterrupt) {
916 interruptPending = false;
917 }
918 }
919
920 for (threadFetched = 0; threadFetched < numFetchingThreads;
921 threadFetched++) {
922 // Fetch each of the actively fetching threads.
923 fetch(status_change);
924 }
925
926 // Record number of instructions fetched this cycle for distribution.
927 fetchNisnDist.sample(numInst);
928
929 if (status_change) {
930 // Change the fetch stage status if there was a status change.
931 _status = updateFetchStatus();
932 }
933
934 // Issue the next I-cache request if possible.
935 for (ThreadID i = 0; i < numThreads; ++i) {
936 if (issuePipelinedIfetch[i]) {
937 pipelineIcacheAccesses(i);
938 }
939 }
940
941 // Send instructions enqueued into the fetch queue to decode.
942 // Limit rate by fetchWidth. Stall if decode is stalled.
943 unsigned insts_to_decode = 0;
944 unsigned available_insts = 0;
945
946 for (auto tid : *activeThreads) {
947 if (!stalls[tid].decode) {
948 available_insts += fetchQueue[tid].size();
949 }
950 }
951
952 // Pick a random thread to start trying to grab instructions from
953 auto tid_itr = activeThreads->begin();
954 std::advance(tid_itr, random_mt.random<uint8_t>(0, activeThreads->size() - 1));
955
956 while (available_insts != 0 && insts_to_decode < decodeWidth) {
957 ThreadID tid = *tid_itr;
958 if (!stalls[tid].decode && !fetchQueue[tid].empty()) {
959 auto inst = fetchQueue[tid].front();
960 toDecode->insts[toDecode->size++] = inst;
961 DPRINTF(Fetch, "[tid:%i][sn:%i]: Sending instruction to decode from "
962 "fetch queue. Fetch queue size: %i.\n",
963 tid, inst->seqNum, fetchQueue[tid].size());
964
965 wroteToTimeBuffer = true;
966 fetchQueue[tid].pop_front();
967 insts_to_decode++;
968 available_insts--;
969 }
970
971 tid_itr++;
972 // Wrap around if at end of active threads list
973 if (tid_itr == activeThreads->end())
974 tid_itr = activeThreads->begin();
975 }
976
977 // If there was activity this cycle, inform the CPU of it.
978 if (wroteToTimeBuffer) {
979 DPRINTF(Activity, "Activity this cycle.\n");
980 cpu->activityThisCycle();
981 }
982
983 // Reset the number of the instruction we've fetched.
984 numInst = 0;
985}
986
987template <class Impl>
988bool
989DefaultFetch<Impl>::checkSignalsAndUpdate(ThreadID tid)
990{
991 // Update the per thread stall statuses.
992 if (fromDecode->decodeBlock[tid]) {
993 stalls[tid].decode = true;
994 }
995
996 if (fromDecode->decodeUnblock[tid]) {
997 assert(stalls[tid].decode);
998 assert(!fromDecode->decodeBlock[tid]);
999 stalls[tid].decode = false;
1000 }
1001
1002 // Check squash signals from commit.
1003 if (fromCommit->commitInfo[tid].squash) {
1004
1005 DPRINTF(Fetch, "[tid:%u]: Squashing instructions due to squash "
1006 "from commit.\n",tid);
1007 // In any case, squash.
1008 squash(fromCommit->commitInfo[tid].pc,
1009 fromCommit->commitInfo[tid].doneSeqNum,
1010 fromCommit->commitInfo[tid].squashInst, tid);
1011
1012 // If it was a branch mispredict on a control instruction, update the
1013 // branch predictor with that instruction, otherwise just kill the
1014 // invalid state we generated in after sequence number
1015 if (fromCommit->commitInfo[tid].mispredictInst &&
1016 fromCommit->commitInfo[tid].mispredictInst->isControl()) {
1017 branchPred->squash(fromCommit->commitInfo[tid].doneSeqNum,
1018 fromCommit->commitInfo[tid].pc,
1019 fromCommit->commitInfo[tid].branchTaken,
1020 tid);
1021 } else {
1022 branchPred->squash(fromCommit->commitInfo[tid].doneSeqNum,
1023 tid);
1024 }
1025
1026 return true;
1027 } else if (fromCommit->commitInfo[tid].doneSeqNum) {
1028 // Update the branch predictor if it wasn't a squashed instruction
1029 // that was broadcasted.
1030 branchPred->update(fromCommit->commitInfo[tid].doneSeqNum, tid);
1031 }
1032
1033 // Check squash signals from decode.
1034 if (fromDecode->decodeInfo[tid].squash) {
1035 DPRINTF(Fetch, "[tid:%u]: Squashing instructions due to squash "
1036 "from decode.\n",tid);
1037
1038 // Update the branch predictor.
1039 if (fromDecode->decodeInfo[tid].branchMispredict) {
1040 branchPred->squash(fromDecode->decodeInfo[tid].doneSeqNum,
1041 fromDecode->decodeInfo[tid].nextPC,
1042 fromDecode->decodeInfo[tid].branchTaken,
1043 tid);
1044 } else {
1045 branchPred->squash(fromDecode->decodeInfo[tid].doneSeqNum,
1046 tid);
1047 }
1048
1049 if (fetchStatus[tid] != Squashing) {
1050
1051 DPRINTF(Fetch, "Squashing from decode with PC = %s\n",
1052 fromDecode->decodeInfo[tid].nextPC);
1053 // Squash unless we're already squashing
1054 squashFromDecode(fromDecode->decodeInfo[tid].nextPC,
1055 fromDecode->decodeInfo[tid].squashInst,
1056 fromDecode->decodeInfo[tid].doneSeqNum,
1057 tid);
1058
1059 return true;
1060 }
1061 }
1062
1063 if (checkStall(tid) &&
1064 fetchStatus[tid] != IcacheWaitResponse &&
1065 fetchStatus[tid] != IcacheWaitRetry &&
1066 fetchStatus[tid] != ItlbWait &&
1067 fetchStatus[tid] != QuiescePending) {
1068 DPRINTF(Fetch, "[tid:%i]: Setting to blocked\n",tid);
1069
1070 fetchStatus[tid] = Blocked;
1071
1072 return true;
1073 }
1074
1075 if (fetchStatus[tid] == Blocked ||
1076 fetchStatus[tid] == Squashing) {
1077 // Switch status to running if fetch isn't being told to block or
1078 // squash this cycle.
1079 DPRINTF(Fetch, "[tid:%i]: Done squashing, switching to running.\n",
1080 tid);
1081
1082 fetchStatus[tid] = Running;
1083
1084 return true;
1085 }
1086
1087 // If we've reached this point, we have not gotten any signals that
1088 // cause fetch to change its status. Fetch remains the same as before.
1089 return false;
1090}
1091
1092template<class Impl>
1093typename Impl::DynInstPtr
1094DefaultFetch<Impl>::buildInst(ThreadID tid, StaticInstPtr staticInst,
1095 StaticInstPtr curMacroop, TheISA::PCState thisPC,
1096 TheISA::PCState nextPC, bool trace)
1097{
1098 // Get a sequence number.
1099 InstSeqNum seq = cpu->getAndIncrementInstSeq();
1100
1101 // Create a new DynInst from the instruction fetched.
1102 DynInstPtr instruction =
1103 new DynInst(staticInst, curMacroop, thisPC, nextPC, seq, cpu);
1104 instruction->setTid(tid);
1105
1106 instruction->setASID(tid);
1107
1108 instruction->setThreadState(cpu->thread[tid]);
1109
1110 DPRINTF(Fetch, "[tid:%i]: Instruction PC %#x (%d) created "
1111 "[sn:%lli].\n", tid, thisPC.instAddr(),
1112 thisPC.microPC(), seq);
1113
1114 DPRINTF(Fetch, "[tid:%i]: Instruction is: %s\n", tid,
1115 instruction->staticInst->
1116 disassemble(thisPC.instAddr()));
1117
1118#if TRACING_ON
1119 if (trace) {
1120 instruction->traceData =
1121 cpu->getTracer()->getInstRecord(curTick(), cpu->tcBase(tid),
1122 instruction->staticInst, thisPC, curMacroop);
1123 }
1124#else
1125 instruction->traceData = NULL;
1126#endif
1127
1128 // Add instruction to the CPU's list of instructions.
1129 instruction->setInstListIt(cpu->addInst(instruction));
1130
1131 // Write the instruction to the first slot in the queue
1132 // that heads to decode.
1133 assert(numInst < fetchWidth);
1134 fetchQueue[tid].push_back(instruction);
1135 assert(fetchQueue[tid].size() <= fetchQueueSize);
1136 DPRINTF(Fetch, "[tid:%i]: Fetch queue entry created (%i/%i).\n",
1137 tid, fetchQueue[tid].size(), fetchQueueSize);
1138 //toDecode->insts[toDecode->size++] = instruction;
1139
1140 // Keep track of if we can take an interrupt at this boundary
1141 delayedCommit[tid] = instruction->isDelayedCommit();
1142
1143 return instruction;
1144}
1145
1146template<class Impl>
1147void
1148DefaultFetch<Impl>::fetch(bool &status_change)
1149{
1150 //////////////////////////////////////////
1151 // Start actual fetch
1152 //////////////////////////////////////////
1153 ThreadID tid = getFetchingThread(fetchPolicy);
1154
1155 assert(!cpu->switchedOut());
1156
1157 if (tid == InvalidThreadID) {
1158 // Breaks looping condition in tick()
1159 threadFetched = numFetchingThreads;
1160
1161 if (numThreads == 1) { // @todo Per-thread stats
1162 profileStall(0);
1163 }
1164
1165 return;
1166 }
1167
1168 DPRINTF(Fetch, "Attempting to fetch from [tid:%i]\n", tid);
1169
1170 // The current PC.
1171 TheISA::PCState thisPC = pc[tid];
1172
1173 Addr pcOffset = fetchOffset[tid];
1174 Addr fetchAddr = (thisPC.instAddr() + pcOffset) & BaseCPU::PCMask;
1175
1176 bool inRom = isRomMicroPC(thisPC.microPC());
1177
1178 // If returning from the delay of a cache miss, then update the status
1179 // to running, otherwise do the cache access. Possibly move this up
1180 // to tick() function.
1181 if (fetchStatus[tid] == IcacheAccessComplete) {
1182 DPRINTF(Fetch, "[tid:%i]: Icache miss is complete.\n", tid);
1183
1184 fetchStatus[tid] = Running;
1185 status_change = true;
1186 } else if (fetchStatus[tid] == Running) {
1187 // Align the fetch PC so its at the start of a fetch buffer segment.
1188 Addr fetchBufferBlockPC = fetchBufferAlignPC(fetchAddr);
1189
1190 // If buffer is no longer valid or fetchAddr has moved to point
1191 // to the next cache block, AND we have no remaining ucode
1192 // from a macro-op, then start fetch from icache.
1193 if (!(fetchBufferValid[tid] && fetchBufferBlockPC == fetchBufferPC[tid])
1194 && !inRom && !macroop[tid]) {
1195 DPRINTF(Fetch, "[tid:%i]: Attempting to translate and read "
1196 "instruction, starting at PC %s.\n", tid, thisPC);
1197
1198 fetchCacheLine(fetchAddr, tid, thisPC.instAddr());
1199
1200 if (fetchStatus[tid] == IcacheWaitResponse)
1201 ++icacheStallCycles;
1202 else if (fetchStatus[tid] == ItlbWait)
1203 ++fetchTlbCycles;
1204 else
1205 ++fetchMiscStallCycles;
1206 return;
1207 } else if ((checkInterrupt(thisPC.instAddr()) && !delayedCommit[tid])) {
1208 // Stall CPU if an interrupt is posted and we're not issuing
1209 // an delayed commit micro-op currently (delayed commit instructions
1210 // are not interruptable by interrupts, only faults)
1211 ++fetchMiscStallCycles;
1212 DPRINTF(Fetch, "[tid:%i]: Fetch is stalled!\n", tid);
1213 return;
1214 }
1215 } else {
1216 if (fetchStatus[tid] == Idle) {
1217 ++fetchIdleCycles;
1218 DPRINTF(Fetch, "[tid:%i]: Fetch is idle!\n", tid);
1219 }
1220
1221 // Status is Idle, so fetch should do nothing.
1222 return;
1223 }
1224
1225 ++fetchCycles;
1226
1227 TheISA::PCState nextPC = thisPC;
1228
1229 StaticInstPtr staticInst = NULL;
1230 StaticInstPtr curMacroop = macroop[tid];
1231
1232 // If the read of the first instruction was successful, then grab the
1233 // instructions from the rest of the cache line and put them into the
1234 // queue heading to decode.
1235
1236 DPRINTF(Fetch, "[tid:%i]: Adding instructions to queue to "
1237 "decode.\n", tid);
1238
1239 // Need to keep track of whether or not a predicted branch
1240 // ended this fetch block.
1241 bool predictedBranch = false;
1242
1243 // Need to halt fetch if quiesce instruction detected
1244 bool quiesce = false;
1245
1246 TheISA::MachInst *cacheInsts =
1247 reinterpret_cast<TheISA::MachInst *>(fetchBuffer[tid]);
1248
1249 const unsigned numInsts = fetchBufferSize / instSize;
1250 unsigned blkOffset = (fetchAddr - fetchBufferPC[tid]) / instSize;
1251
1252 // Loop through instruction memory from the cache.
1253 // Keep issuing while fetchWidth is available and branch is not
1254 // predicted taken
1255 while (numInst < fetchWidth && fetchQueue[tid].size() < fetchQueueSize
1256 && !predictedBranch && !quiesce) {
1257 // We need to process more memory if we aren't going to get a
1258 // StaticInst from the rom, the current macroop, or what's already
1259 // in the decoder.
1260 bool needMem = !inRom && !curMacroop &&
1261 !decoder[tid]->instReady();
1262 fetchAddr = (thisPC.instAddr() + pcOffset) & BaseCPU::PCMask;
1263 Addr fetchBufferBlockPC = fetchBufferAlignPC(fetchAddr);
1264
1265 if (needMem) {
1266 // If buffer is no longer valid or fetchAddr has moved to point
1267 // to the next cache block then start fetch from icache.
1268 if (!fetchBufferValid[tid] ||
1269 fetchBufferBlockPC != fetchBufferPC[tid])
1270 break;
1271
1272 if (blkOffset >= numInsts) {
1273 // We need to process more memory, but we've run out of the
1274 // current block.
1275 break;
1276 }
1277
1278 if (ISA_HAS_DELAY_SLOT && pcOffset == 0) {
1279 // Walk past any annulled delay slot instructions.
1280 Addr pcAddr = thisPC.instAddr() & BaseCPU::PCMask;
1281 while (fetchAddr != pcAddr && blkOffset < numInsts) {
1282 blkOffset++;
1283 fetchAddr += instSize;
1284 }
1285 if (blkOffset >= numInsts)
1286 break;
1287 }
1288
1289 MachInst inst = TheISA::gtoh(cacheInsts[blkOffset]);
1290 decoder[tid]->moreBytes(thisPC, fetchAddr, inst);
1291
1292 if (decoder[tid]->needMoreBytes()) {
1293 blkOffset++;
1294 fetchAddr += instSize;
1295 pcOffset += instSize;
1296 }
1297 }
1298
1299 // Extract as many instructions and/or microops as we can from
1300 // the memory we've processed so far.
1301 do {
1302 if (!(curMacroop || inRom)) {
1303 if (decoder[tid]->instReady()) {
1304 staticInst = decoder[tid]->decode(thisPC);
1305
1306 // Increment stat of fetched instructions.
1307 ++fetchedInsts;
1308
1309 if (staticInst->isMacroop()) {
1310 curMacroop = staticInst;
1311 } else {
1312 pcOffset = 0;
1313 }
1314 } else {
1315 // We need more bytes for this instruction so blkOffset and
1316 // pcOffset will be updated
1317 break;
1318 }
1319 }
1320 // Whether we're moving to a new macroop because we're at the
1321 // end of the current one, or the branch predictor incorrectly
1322 // thinks we are...
1323 bool newMacro = false;
1324 if (curMacroop || inRom) {
1325 if (inRom) {
1326 staticInst = cpu->microcodeRom.fetchMicroop(
1327 thisPC.microPC(), curMacroop);
1328 } else {
1329 staticInst = curMacroop->fetchMicroop(thisPC.microPC());
1330 }
1331 newMacro |= staticInst->isLastMicroop();
1332 }
1333
1334 DynInstPtr instruction =
1335 buildInst(tid, staticInst, curMacroop,
1336 thisPC, nextPC, true);
1337
1338 ppFetch->notify(instruction);
1339 numInst++;
1340
1341#if TRACING_ON
1342 if (DTRACE(O3PipeView)) {
1343 instruction->fetchTick = curTick();
1344 }
1345#endif
1346
1347 nextPC = thisPC;
1348
1349 // If we're branching after this instruction, quit fetching
1350 // from the same block.
1351 predictedBranch |= thisPC.branching();
1352 predictedBranch |=
1353 lookupAndUpdateNextPC(instruction, nextPC);
1354 if (predictedBranch) {
1355 DPRINTF(Fetch, "Branch detected with PC = %s\n", thisPC);
1356 }
1357
1358 newMacro |= thisPC.instAddr() != nextPC.instAddr();
1359
1360 // Move to the next instruction, unless we have a branch.
1361 thisPC = nextPC;
1362 inRom = isRomMicroPC(thisPC.microPC());
1363
1364 if (newMacro) {
1365 fetchAddr = thisPC.instAddr() & BaseCPU::PCMask;
1366 blkOffset = (fetchAddr - fetchBufferPC[tid]) / instSize;
1367 pcOffset = 0;
1368 curMacroop = NULL;
1369 }
1370
1371 if (instruction->isQuiesce()) {
1372 DPRINTF(Fetch,
1373 "Quiesce instruction encountered, halting fetch!\n");
1374 fetchStatus[tid] = QuiescePending;
1375 status_change = true;
1376 quiesce = true;
1377 break;
1378 }
1379 } while ((curMacroop || decoder[tid]->instReady()) &&
1380 numInst < fetchWidth &&
1381 fetchQueue[tid].size() < fetchQueueSize);
1382
1383 // Re-evaluate whether the next instruction to fetch is in micro-op ROM
1384 // or not.
1385 inRom = isRomMicroPC(thisPC.microPC());
1386 }
1387
1388 if (predictedBranch) {
1389 DPRINTF(Fetch, "[tid:%i]: Done fetching, predicted branch "
1390 "instruction encountered.\n", tid);
1391 } else if (numInst >= fetchWidth) {
1392 DPRINTF(Fetch, "[tid:%i]: Done fetching, reached fetch bandwidth "
1393 "for this cycle.\n", tid);
1394 } else if (blkOffset >= fetchBufferSize) {
1395 DPRINTF(Fetch, "[tid:%i]: Done fetching, reached the end of the"
1396 "fetch buffer.\n", tid);
1397 }
1398
1399 macroop[tid] = curMacroop;
1400 fetchOffset[tid] = pcOffset;
1401
1402 if (numInst > 0) {
1403 wroteToTimeBuffer = true;
1404 }
1405
1406 pc[tid] = thisPC;
1407
1408 // pipeline a fetch if we're crossing a fetch buffer boundary and not in
1409 // a state that would preclude fetching
1410 fetchAddr = (thisPC.instAddr() + pcOffset) & BaseCPU::PCMask;
1411 Addr fetchBufferBlockPC = fetchBufferAlignPC(fetchAddr);
1412 issuePipelinedIfetch[tid] = fetchBufferBlockPC != fetchBufferPC[tid] &&
1413 fetchStatus[tid] != IcacheWaitResponse &&
1414 fetchStatus[tid] != ItlbWait &&
1415 fetchStatus[tid] != IcacheWaitRetry &&
1416 fetchStatus[tid] != QuiescePending &&
1417 !curMacroop;
1418}
1419
1420template<class Impl>
1421void
1422DefaultFetch<Impl>::recvReqRetry()
1423{
1424 if (retryPkt != NULL) {
1425 assert(cacheBlocked);
1426 assert(retryTid != InvalidThreadID);
1427 assert(fetchStatus[retryTid] == IcacheWaitRetry);
1428
1429 if (cpu->getInstPort().sendTimingReq(retryPkt)) {
1430 fetchStatus[retryTid] = IcacheWaitResponse;
1431 // Notify Fetch Request probe when a retryPkt is successfully sent.
1432 // Note that notify must be called before retryPkt is set to NULL.
1433 ppFetchRequestSent->notify(retryPkt->req);
1434 retryPkt = NULL;
1435 retryTid = InvalidThreadID;
1436 cacheBlocked = false;
1437 }
1438 } else {
1439 assert(retryTid == InvalidThreadID);
1440 // Access has been squashed since it was sent out. Just clear
1441 // the cache being blocked.
1442 cacheBlocked = false;
1443 }
1444}
1445
1446///////////////////////////////////////
1447// //
1448// SMT FETCH POLICY MAINTAINED HERE //
1449// //
1450///////////////////////////////////////
1451template<class Impl>
1452ThreadID
1453DefaultFetch<Impl>::getFetchingThread(FetchPriority &fetch_priority)
1454{
1455 if (numThreads > 1) {
1456 switch (fetch_priority) {
1457
1458 case SingleThread:
1459 return 0;
1460
1461 case RoundRobin:
1462 return roundRobin();
1463
1464 case IQ:
1465 return iqCount();
1466
1467 case LSQ:
1468 return lsqCount();
1469
1470 case Branch:
1471 return branchCount();
1472
1473 default:
1474 return InvalidThreadID;
1475 }
1476 } else {
1477 list<ThreadID>::iterator thread = activeThreads->begin();
1478 if (thread == activeThreads->end()) {
1479 return InvalidThreadID;
1480 }
1481
1482 ThreadID tid = *thread;
1483
1484 if (fetchStatus[tid] == Running ||
1485 fetchStatus[tid] == IcacheAccessComplete ||
1486 fetchStatus[tid] == Idle) {
1487 return tid;
1488 } else {
1489 return InvalidThreadID;
1490 }
1491 }
1492}
1493
1494
1495template<class Impl>
1496ThreadID
1497DefaultFetch<Impl>::roundRobin()
1498{
1499 list<ThreadID>::iterator pri_iter = priorityList.begin();
1500 list<ThreadID>::iterator end = priorityList.end();
1501
1502 ThreadID high_pri;
1503
1504 while (pri_iter != end) {
1505 high_pri = *pri_iter;
1506
1507 assert(high_pri <= numThreads);
1508
1509 if (fetchStatus[high_pri] == Running ||
1510 fetchStatus[high_pri] == IcacheAccessComplete ||
1511 fetchStatus[high_pri] == Idle) {
1512
1513 priorityList.erase(pri_iter);
1514 priorityList.push_back(high_pri);
1515
1516 return high_pri;
1517 }
1518
1519 pri_iter++;
1520 }
1521
1522 return InvalidThreadID;
1523}
1524
1525template<class Impl>
1526ThreadID
1527DefaultFetch<Impl>::iqCount()
1528{
1529 //sorted from lowest->highest
1530 std::priority_queue<unsigned,vector<unsigned>,
1531 std::greater<unsigned> > PQ;
1532 std::map<unsigned, ThreadID> threadMap;
1533
1534 list<ThreadID>::iterator threads = activeThreads->begin();
1535 list<ThreadID>::iterator end = activeThreads->end();
1536
1537 while (threads != end) {
1538 ThreadID tid = *threads++;
1539 unsigned iqCount = fromIEW->iewInfo[tid].iqCount;
1540
1541 //we can potentially get tid collisions if two threads
1542 //have the same iqCount, but this should be rare.
1543 PQ.push(iqCount);
1544 threadMap[iqCount] = tid;
1545 }
1546
1547 while (!PQ.empty()) {
1548 ThreadID high_pri = threadMap[PQ.top()];
1549
1550 if (fetchStatus[high_pri] == Running ||
1551 fetchStatus[high_pri] == IcacheAccessComplete ||
1552 fetchStatus[high_pri] == Idle)
1553 return high_pri;
1554 else
1555 PQ.pop();
1556
1557 }
1558
1559 return InvalidThreadID;
1560}
1561
1562template<class Impl>
1563ThreadID
1564DefaultFetch<Impl>::lsqCount()
1565{
1566 //sorted from lowest->highest
1567 std::priority_queue<unsigned,vector<unsigned>,
1568 std::greater<unsigned> > PQ;
1569 std::map<unsigned, ThreadID> threadMap;
1570
1571 list<ThreadID>::iterator threads = activeThreads->begin();
1572 list<ThreadID>::iterator end = activeThreads->end();
1573
1574 while (threads != end) {
1575 ThreadID tid = *threads++;
1576 unsigned ldstqCount = fromIEW->iewInfo[tid].ldstqCount;
1577
1578 //we can potentially get tid collisions if two threads
1579 //have the same iqCount, but this should be rare.
1580 PQ.push(ldstqCount);
1581 threadMap[ldstqCount] = tid;
1582 }
1583
1584 while (!PQ.empty()) {
1585 ThreadID high_pri = threadMap[PQ.top()];
1586
1587 if (fetchStatus[high_pri] == Running ||
1588 fetchStatus[high_pri] == IcacheAccessComplete ||
1589 fetchStatus[high_pri] == Idle)
1590 return high_pri;
1591 else
1592 PQ.pop();
1593 }
1594
1595 return InvalidThreadID;
1596}
1597
1598template<class Impl>
1599ThreadID
1600DefaultFetch<Impl>::branchCount()
1601{
1602#if 0
1603 list<ThreadID>::iterator thread = activeThreads->begin();
1604 assert(thread != activeThreads->end());
1605 ThreadID tid = *thread;
1606#endif
1607
1608 panic("Branch Count Fetch policy unimplemented\n");
1609 return InvalidThreadID;
1610}
1611
1612template<class Impl>
1613void
1614DefaultFetch<Impl>::pipelineIcacheAccesses(ThreadID tid)
1615{
1616 if (!issuePipelinedIfetch[tid]) {
1617 return;
1618 }
1619
1620 // The next PC to access.
1621 TheISA::PCState thisPC = pc[tid];
1622
1623 if (isRomMicroPC(thisPC.microPC())) {
1624 return;
1625 }
1626
1627 Addr pcOffset = fetchOffset[tid];
1628 Addr fetchAddr = (thisPC.instAddr() + pcOffset) & BaseCPU::PCMask;
1629
1630 // Align the fetch PC so its at the start of a fetch buffer segment.
1631 Addr fetchBufferBlockPC = fetchBufferAlignPC(fetchAddr);
1632
1633 // Unless buffer already got the block, fetch it from icache.
1634 if (!(fetchBufferValid[tid] && fetchBufferBlockPC == fetchBufferPC[tid])) {
1635 DPRINTF(Fetch, "[tid:%i]: Issuing a pipelined I-cache access, "
1636 "starting at PC %s.\n", tid, thisPC);
1637
1638 fetchCacheLine(fetchAddr, tid, thisPC.instAddr());
1639 }
1640}
1641
1642template<class Impl>
1643void
1644DefaultFetch<Impl>::profileStall(ThreadID tid) {
1645 DPRINTF(Fetch,"There are no more threads available to fetch from.\n");
1646
1647 // @todo Per-thread stats
1648
1649 if (stalls[tid].drain) {
1650 ++fetchPendingDrainCycles;
1651 DPRINTF(Fetch, "Fetch is waiting for a drain!\n");
1652 } else if (activeThreads->empty()) {
1653 ++fetchNoActiveThreadStallCycles;
1654 DPRINTF(Fetch, "Fetch has no active thread!\n");
1655 } else if (fetchStatus[tid] == Blocked) {
1656 ++fetchBlockedCycles;
1657 DPRINTF(Fetch, "[tid:%i]: Fetch is blocked!\n", tid);
1658 } else if (fetchStatus[tid] == Squashing) {
1659 ++fetchSquashCycles;
1660 DPRINTF(Fetch, "[tid:%i]: Fetch is squashing!\n", tid);
1661 } else if (fetchStatus[tid] == IcacheWaitResponse) {
1662 ++icacheStallCycles;
1663 DPRINTF(Fetch, "[tid:%i]: Fetch is waiting cache response!\n",
1664 tid);
1665 } else if (fetchStatus[tid] == ItlbWait) {
1666 ++fetchTlbCycles;
1667 DPRINTF(Fetch, "[tid:%i]: Fetch is waiting ITLB walk to "
1668 "finish!\n", tid);
1669 } else if (fetchStatus[tid] == TrapPending) {
1670 ++fetchPendingTrapStallCycles;
1671 DPRINTF(Fetch, "[tid:%i]: Fetch is waiting for a pending trap!\n",
1672 tid);
1673 } else if (fetchStatus[tid] == QuiescePending) {
1674 ++fetchPendingQuiesceStallCycles;
1675 DPRINTF(Fetch, "[tid:%i]: Fetch is waiting for a pending quiesce "
1676 "instruction!\n", tid);
1677 } else if (fetchStatus[tid] == IcacheWaitRetry) {
1678 ++fetchIcacheWaitRetryStallCycles;
1679 DPRINTF(Fetch, "[tid:%i]: Fetch is waiting for an I-cache retry!\n",
1680 tid);
1681 } else if (fetchStatus[tid] == NoGoodAddr) {
1682 DPRINTF(Fetch, "[tid:%i]: Fetch predicted non-executable address\n",
1683 tid);
1684 } else {
1685 DPRINTF(Fetch, "[tid:%i]: Unexpected fetch stall reason (Status: %i).\n",
1686 tid, fetchStatus[tid]);
1687 }
1688}
1689
1690#endif//__CPU_O3_FETCH_IMPL_HH__