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 <algorithm>
32#include <string>
33
34#include "base/loader/symtab.hh"
35#include "base/timebuf.hh"
36#include "cpu/checker/cpu.hh"
37#include "cpu/exetrace.hh"
38#include "cpu/o3/commit.hh"
39#include "cpu/o3/thread_state.hh"
40
41using namespace std;
42
43template <class Impl>
44DefaultCommit<Impl>::TrapEvent::TrapEvent(DefaultCommit<Impl> *_commit,
45 unsigned _tid)
46 : Event(&mainEventQueue, CPU_Tick_Pri), commit(_commit), tid(_tid)
47{
48 this->setFlags(Event::AutoDelete);
49}
50
51template <class Impl>
52void
53DefaultCommit<Impl>::TrapEvent::process()
54{
55 // This will get reset by commit if it was switched out at the
56 // time of this event processing.
57 commit->trapSquash[tid] = true;
58}
59
60template <class Impl>
61const char *
62DefaultCommit<Impl>::TrapEvent::description()
63{
64 return "Trap event";
65}
66
67template <class Impl>
68DefaultCommit<Impl>::DefaultCommit(Params *params)
69 : squashCounter(0),
70 iewToCommitDelay(params->iewToCommitDelay),
71 commitToIEWDelay(params->commitToIEWDelay),
72 renameToROBDelay(params->renameToROBDelay),
73 fetchToCommitDelay(params->commitToFetchDelay),
74 renameWidth(params->renameWidth),
75 iewWidth(params->executeWidth),
76 commitWidth(params->commitWidth),
77 numThreads(params->numberOfThreads),
|
120 }
121
122 fetchFaultTick = 0;
123 fetchTrapWait = 0;
124}
125
126template <class Impl>
127std::string
128DefaultCommit<Impl>::name() const
129{
130 return cpu->name() + ".commit";
131}
132
133template <class Impl>
134void
135DefaultCommit<Impl>::regStats()
136{
137 using namespace Stats;
138 commitCommittedInsts
139 .name(name() + ".commitCommittedInsts")
140 .desc("The number of committed instructions")
141 .prereq(commitCommittedInsts);
142 commitSquashedInsts
143 .name(name() + ".commitSquashedInsts")
144 .desc("The number of squashed insts skipped by commit")
145 .prereq(commitSquashedInsts);
146 commitSquashEvents
147 .name(name() + ".commitSquashEvents")
148 .desc("The number of times commit is told to squash")
149 .prereq(commitSquashEvents);
150 commitNonSpecStalls
151 .name(name() + ".commitNonSpecStalls")
152 .desc("The number of times commit has been forced to stall to "
153 "communicate backwards")
154 .prereq(commitNonSpecStalls);
155 branchMispredicts
156 .name(name() + ".branchMispredicts")
157 .desc("The number of times a branch was mispredicted")
158 .prereq(branchMispredicts);
159 numCommittedDist
160 .init(0,commitWidth,1)
161 .name(name() + ".COM:committed_per_cycle")
162 .desc("Number of insts commited each cycle")
163 .flags(Stats::pdf)
164 ;
165
166 statComInst
167 .init(cpu->number_of_threads)
168 .name(name() + ".COM:count")
169 .desc("Number of instructions committed")
170 .flags(total)
171 ;
172
173 statComSwp
174 .init(cpu->number_of_threads)
175 .name(name() + ".COM:swp_count")
176 .desc("Number of s/w prefetches committed")
177 .flags(total)
178 ;
179
180 statComRefs
181 .init(cpu->number_of_threads)
182 .name(name() + ".COM:refs")
183 .desc("Number of memory references committed")
184 .flags(total)
185 ;
186
187 statComLoads
188 .init(cpu->number_of_threads)
189 .name(name() + ".COM:loads")
190 .desc("Number of loads committed")
191 .flags(total)
192 ;
193
194 statComMembars
195 .init(cpu->number_of_threads)
196 .name(name() + ".COM:membars")
197 .desc("Number of memory barriers committed")
198 .flags(total)
199 ;
200
201 statComBranches
202 .init(cpu->number_of_threads)
203 .name(name() + ".COM:branches")
204 .desc("Number of branches committed")
205 .flags(total)
206 ;
207
208 //
209 // Commit-Eligible instructions...
210 //
211 // -> The number of instructions eligible to commit in those
212 // cycles where we reached our commit BW limit (less the number
213 // actually committed)
214 //
215 // -> The average value is computed over ALL CYCLES... not just
216 // the BW limited cycles
217 //
218 // -> The standard deviation is computed only over cycles where
219 // we reached the BW limit
220 //
221 commitEligible
222 .init(cpu->number_of_threads)
223 .name(name() + ".COM:bw_limited")
224 .desc("number of insts not committed due to BW limits")
225 .flags(total)
226 ;
227
228 commitEligibleSamples
229 .name(name() + ".COM:bw_lim_events")
230 .desc("number cycles where commit BW limit reached")
231 ;
232}
233
234template <class Impl>
235void
236DefaultCommit<Impl>::setCPU(FullCPU *cpu_ptr)
237{
238 DPRINTF(Commit, "Commit: Setting CPU pointer.\n");
239 cpu = cpu_ptr;
240
241 // Commit must broadcast the number of free entries it has at the start of
242 // the simulation, so it starts as active.
243 cpu->activateStage(FullCPU::CommitIdx);
244
245 trapLatency = cpu->cycles(trapLatency);
246 fetchTrapLatency = cpu->cycles(fetchTrapLatency);
247}
248
249template <class Impl>
250void
251DefaultCommit<Impl>::setThreads(vector<Thread *> &threads)
252{
253 thread = threads;
254}
255
256template <class Impl>
257void
258DefaultCommit<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr)
259{
260 DPRINTF(Commit, "Commit: Setting time buffer pointer.\n");
261 timeBuffer = tb_ptr;
262
263 // Setup wire to send information back to IEW.
264 toIEW = timeBuffer->getWire(0);
265
266 // Setup wire to read data from IEW (for the ROB).
267 robInfoFromIEW = timeBuffer->getWire(-iewToCommitDelay);
268}
269
270template <class Impl>
271void
272DefaultCommit<Impl>::setFetchQueue(TimeBuffer<FetchStruct> *fq_ptr)
273{
274 DPRINTF(Commit, "Commit: Setting fetch queue pointer.\n");
275 fetchQueue = fq_ptr;
276
277 // Setup wire to get instructions from rename (for the ROB).
278 fromFetch = fetchQueue->getWire(-fetchToCommitDelay);
279}
280
281template <class Impl>
282void
283DefaultCommit<Impl>::setRenameQueue(TimeBuffer<RenameStruct> *rq_ptr)
284{
285 DPRINTF(Commit, "Commit: Setting rename queue pointer.\n");
286 renameQueue = rq_ptr;
287
288 // Setup wire to get instructions from rename (for the ROB).
289 fromRename = renameQueue->getWire(-renameToROBDelay);
290}
291
292template <class Impl>
293void
294DefaultCommit<Impl>::setIEWQueue(TimeBuffer<IEWStruct> *iq_ptr)
295{
296 DPRINTF(Commit, "Commit: Setting IEW queue pointer.\n");
297 iewQueue = iq_ptr;
298
299 // Setup wire to get instructions from IEW.
300 fromIEW = iewQueue->getWire(-iewToCommitDelay);
301}
302
303template <class Impl>
304void
305DefaultCommit<Impl>::setFetchStage(Fetch *fetch_stage)
306{
307 fetchStage = fetch_stage;
308}
309
310template <class Impl>
311void
312DefaultCommit<Impl>::setIEWStage(IEW *iew_stage)
313{
314 iewStage = iew_stage;
315}
316
317template<class Impl>
318void
319DefaultCommit<Impl>::setActiveThreads(list<unsigned> *at_ptr)
320{
321 DPRINTF(Commit, "Commit: Setting active threads list pointer.\n");
322 activeThreads = at_ptr;
323}
324
325template <class Impl>
326void
327DefaultCommit<Impl>::setRenameMap(RenameMap rm_ptr[])
328{
329 DPRINTF(Commit, "Setting rename map pointers.\n");
330
331 for (int i=0; i < numThreads; i++) {
332 renameMap[i] = &rm_ptr[i];
333 }
334}
335
336template <class Impl>
337void
338DefaultCommit<Impl>::setROB(ROB *rob_ptr)
339{
340 DPRINTF(Commit, "Commit: Setting ROB pointer.\n");
341 rob = rob_ptr;
342}
343
344template <class Impl>
345void
346DefaultCommit<Impl>::initStage()
347{
348 rob->setActiveThreads(activeThreads);
349 rob->resetEntries();
350
351 // Broadcast the number of free entries.
352 for (int i=0; i < numThreads; i++) {
353 toIEW->commitInfo[i].usedROB = true;
354 toIEW->commitInfo[i].freeROBEntries = rob->numFreeEntries(i);
355 }
356
357 cpu->activityThisCycle();
358}
359
360template <class Impl>
361void
362DefaultCommit<Impl>::switchOut()
363{
364 switchPending = true;
365}
366
367template <class Impl>
368void
369DefaultCommit<Impl>::doSwitchOut()
370{
371 switchedOut = true;
372 switchPending = false;
373 rob->switchOut();
374}
375
376template <class Impl>
377void
378DefaultCommit<Impl>::takeOverFrom()
379{
380 switchedOut = false;
381 _status = Active;
382 _nextStatus = Inactive;
383 for (int i=0; i < numThreads; i++) {
384 commitStatus[i] = Idle;
385 changedROBNumEntries[i] = false;
386 trapSquash[i] = false;
387 xcSquash[i] = false;
388 }
389 squashCounter = 0;
390 rob->takeOverFrom();
391}
392
393template <class Impl>
394void
395DefaultCommit<Impl>::updateStatus()
396{
397 // reset ROB changed variable
398 list<unsigned>::iterator threads = (*activeThreads).begin();
399 while (threads != (*activeThreads).end()) {
400 unsigned tid = *threads++;
401 changedROBNumEntries[tid] = false;
402
403 // Also check if any of the threads has a trap pending
404 if (commitStatus[tid] == TrapPending ||
405 commitStatus[tid] == FetchTrapPending) {
406 _nextStatus = Active;
407 }
408 }
409
410 if (_nextStatus == Inactive && _status == Active) {
411 DPRINTF(Activity, "Deactivating stage.\n");
412 cpu->deactivateStage(FullCPU::CommitIdx);
413 } else if (_nextStatus == Active && _status == Inactive) {
414 DPRINTF(Activity, "Activating stage.\n");
415 cpu->activateStage(FullCPU::CommitIdx);
416 }
417
418 _status = _nextStatus;
419}
420
421template <class Impl>
422void
423DefaultCommit<Impl>::setNextStatus()
424{
425 int squashes = 0;
426
427 list<unsigned>::iterator threads = (*activeThreads).begin();
428
429 while (threads != (*activeThreads).end()) {
430 unsigned tid = *threads++;
431
432 if (commitStatus[tid] == ROBSquashing) {
433 squashes++;
434 }
435 }
436
437 assert(squashes == squashCounter);
438
439 // If commit is currently squashing, then it will have activity for the
440 // next cycle. Set its next status as active.
441 if (squashCounter) {
442 _nextStatus = Active;
443 }
444}
445
446template <class Impl>
447bool
448DefaultCommit<Impl>::changedROBEntries()
449{
450 list<unsigned>::iterator threads = (*activeThreads).begin();
451
452 while (threads != (*activeThreads).end()) {
453 unsigned tid = *threads++;
454
455 if (changedROBNumEntries[tid]) {
456 return true;
457 }
458 }
459
460 return false;
461}
462
463template <class Impl>
464unsigned
465DefaultCommit<Impl>::numROBFreeEntries(unsigned tid)
466{
467 return rob->numFreeEntries(tid);
468}
469
470template <class Impl>
471void
472DefaultCommit<Impl>::generateTrapEvent(unsigned tid)
473{
474 DPRINTF(Commit, "Generating trap event for [tid:%i]\n", tid);
475
476 TrapEvent *trap = new TrapEvent(this, tid);
477
478 trap->schedule(curTick + trapLatency);
479
480 thread[tid]->trapPending = true;
481}
482
483template <class Impl>
484void
485DefaultCommit<Impl>::generateXCEvent(unsigned tid)
486{
487 DPRINTF(Commit, "Generating XC squash event for [tid:%i]\n", tid);
488
489 xcSquash[tid] = true;
490}
491
492template <class Impl>
493void
494DefaultCommit<Impl>::squashAll(unsigned tid)
495{
496 // If we want to include the squashing instruction in the squash,
497 // then use one older sequence number.
498 // Hopefully this doesn't mess things up. Basically I want to squash
499 // all instructions of this thread.
500 InstSeqNum squashed_inst = rob->isEmpty() ?
501 0 : rob->readHeadInst(tid)->seqNum - 1;;
502
503 // All younger instructions will be squashed. Set the sequence
504 // number as the youngest instruction in the ROB (0 in this case.
505 // Hopefully nothing breaks.)
506 youngestSeqNum[tid] = 0;
507
508 rob->squash(squashed_inst, tid);
509 changedROBNumEntries[tid] = true;
510
511 // Send back the sequence number of the squashed instruction.
512 toIEW->commitInfo[tid].doneSeqNum = squashed_inst;
513
514 // Send back the squash signal to tell stages that they should
515 // squash.
516 toIEW->commitInfo[tid].squash = true;
517
518 // Send back the rob squashing signal so other stages know that
519 // the ROB is in the process of squashing.
520 toIEW->commitInfo[tid].robSquashing = true;
521
522 toIEW->commitInfo[tid].branchMispredict = false;
523
524 toIEW->commitInfo[tid].nextPC = PC[tid];
525}
526
527template <class Impl>
528void
529DefaultCommit<Impl>::squashFromTrap(unsigned tid)
530{
531 squashAll(tid);
532
533 DPRINTF(Commit, "Squashing from trap, restarting at PC %#x\n", PC[tid]);
534
535 thread[tid]->trapPending = false;
536 thread[tid]->inSyscall = false;
537
538 trapSquash[tid] = false;
539
540 commitStatus[tid] = ROBSquashing;
541 cpu->activityThisCycle();
542
543 ++squashCounter;
544}
545
546template <class Impl>
547void
548DefaultCommit<Impl>::squashFromXC(unsigned tid)
549{
550 squashAll(tid);
551
552 DPRINTF(Commit, "Squashing from XC, restarting at PC %#x\n", PC[tid]);
553
554 thread[tid]->inSyscall = false;
555 assert(!thread[tid]->trapPending);
556
557 commitStatus[tid] = ROBSquashing;
558 cpu->activityThisCycle();
559
560 xcSquash[tid] = false;
561
562 ++squashCounter;
563}
564
565template <class Impl>
566void
567DefaultCommit<Impl>::tick()
568{
569 wroteToTimeBuffer = false;
570 _nextStatus = Inactive;
571
572 if (switchPending && rob->isEmpty() && !iewStage->hasStoresToWB()) {
573 cpu->signalSwitched();
574 return;
575 }
576
577 list<unsigned>::iterator threads = (*activeThreads).begin();
578
579 // Check if any of the threads are done squashing. Change the
580 // status if they are done.
581 while (threads != (*activeThreads).end()) {
582 unsigned tid = *threads++;
583
584 if (commitStatus[tid] == ROBSquashing) {
585
586 if (rob->isDoneSquashing(tid)) {
587 commitStatus[tid] = Running;
588 --squashCounter;
589 } else {
590 DPRINTF(Commit,"[tid:%u]: Still Squashing, cannot commit any"
591 "insts this cycle.\n", tid);
592 }
593 }
594 }
595
596 commit();
597
598 markCompletedInsts();
599
600 threads = (*activeThreads).begin();
601
602 while (threads != (*activeThreads).end()) {
603 unsigned tid = *threads++;
604
605 if (!rob->isEmpty(tid) && rob->readHeadInst(tid)->readyToCommit()) {
606 // The ROB has more instructions it can commit. Its next status
607 // will be active.
608 _nextStatus = Active;
609
610 DynInstPtr inst = rob->readHeadInst(tid);
611
612 DPRINTF(Commit,"[tid:%i]: Instruction [sn:%lli] PC %#x is head of"
613 " ROB and ready to commit\n",
614 tid, inst->seqNum, inst->readPC());
615
616 } else if (!rob->isEmpty(tid)) {
617 DynInstPtr inst = rob->readHeadInst(tid);
618
619 DPRINTF(Commit,"[tid:%i]: Can't commit, Instruction [sn:%lli] PC "
620 "%#x is head of ROB and not ready\n",
621 tid, inst->seqNum, inst->readPC());
622 }
623
624 DPRINTF(Commit, "[tid:%i]: ROB has %d insts & %d free entries.\n",
625 tid, rob->countInsts(tid), rob->numFreeEntries(tid));
626 }
627
628
629 if (wroteToTimeBuffer) {
630 DPRINTF(Activity, "Activity This Cycle.\n");
631 cpu->activityThisCycle();
632 }
633
634 updateStatus();
635}
636
637template <class Impl>
638void
639DefaultCommit<Impl>::commit()
640{
641
642 //////////////////////////////////////
643 // Check for interrupts
644 //////////////////////////////////////
645
646#if FULL_SYSTEM
647 // Process interrupts if interrupts are enabled, not in PAL mode,
648 // and no other traps or external squashes are currently pending.
649 // @todo: Allow other threads to handle interrupts.
650 if (cpu->checkInterrupts &&
651 cpu->check_interrupts() &&
652 !cpu->inPalMode(readPC()) &&
653 !trapSquash[0] &&
654 !xcSquash[0]) {
655 // Tell fetch that there is an interrupt pending. This will
656 // make fetch wait until it sees a non PAL-mode PC, at which
657 // point it stops fetching instructions.
658 toIEW->commitInfo[0].interruptPending = true;
659
660 // Wait until the ROB is empty and all stores have drained in
661 // order to enter the interrupt.
662 if (rob->isEmpty() && !iewStage->hasStoresToWB()) {
663 // Not sure which thread should be the one to interrupt. For now
664 // always do thread 0.
665 assert(!thread[0]->inSyscall);
666 thread[0]->inSyscall = true;
667
668 // CPU will handle implementation of the interrupt.
669 cpu->processInterrupts();
670
671 // Now squash or record that I need to squash this cycle.
672 commitStatus[0] = TrapPending;
673
674 // Exit state update mode to avoid accidental updating.
675 thread[0]->inSyscall = false;
676
677 // Generate trap squash event.
678 generateTrapEvent(0);
679
680 toIEW->commitInfo[0].clearInterrupt = true;
681
682 DPRINTF(Commit, "Interrupt detected.\n");
683 } else {
684 DPRINTF(Commit, "Interrupt pending, waiting for ROB to empty.\n");
685 }
686 }
687#endif // FULL_SYSTEM
688
689 ////////////////////////////////////
690 // Check for any possible squashes, handle them first
691 ////////////////////////////////////
692
693 list<unsigned>::iterator threads = (*activeThreads).begin();
694
695 while (threads != (*activeThreads).end()) {
696 unsigned tid = *threads++;
697/*
698 if (fromFetch->fetchFault && commitStatus[0] != TrapPending) {
699 // Record the fault. Wait until it's empty in the ROB.
700 // Then handle the trap. Ignore it if there's already a
701 // trap pending as fetch will be redirected.
702 fetchFault = fromFetch->fetchFault;
703 fetchFaultTick = curTick + fetchTrapLatency;
704 commitStatus[0] = FetchTrapPending;
705 DPRINTF(Commit, "Fault from fetch recorded. Will trap if the "
706 "ROB empties without squashing the fault.\n");
707 fetchTrapWait = 0;
708 }
709
710 // Fetch may tell commit to clear the trap if it's been squashed.
711 if (fromFetch->clearFetchFault) {
712 DPRINTF(Commit, "Received clear fetch fault signal\n");
713 fetchTrapWait = 0;
714 if (commitStatus[0] == FetchTrapPending) {
715 DPRINTF(Commit, "Clearing fault from fetch\n");
716 commitStatus[0] = Running;
717 }
718 }
719*/
720 // Not sure which one takes priority. I think if we have
721 // both, that's a bad sign.
722 if (trapSquash[tid] == true) {
723 assert(!xcSquash[tid]);
724 squashFromTrap(tid);
725 } else if (xcSquash[tid] == true) {
726 squashFromXC(tid);
727 }
728
729 // Squashed sequence number must be older than youngest valid
730 // instruction in the ROB. This prevents squashes from younger
731 // instructions overriding squashes from older instructions.
732 if (fromIEW->squash[tid] &&
733 commitStatus[tid] != TrapPending &&
734 fromIEW->squashedSeqNum[tid] <= youngestSeqNum[tid]) {
735
736 DPRINTF(Commit, "[tid:%i]: Squashing due to PC %#x [sn:%i]\n",
737 tid,
738 fromIEW->mispredPC[tid],
739 fromIEW->squashedSeqNum[tid]);
740
741 DPRINTF(Commit, "[tid:%i]: Redirecting to PC %#x\n",
742 tid,
743 fromIEW->nextPC[tid]);
744
745 commitStatus[tid] = ROBSquashing;
746
747 ++squashCounter;
748
749 // If we want to include the squashing instruction in the squash,
750 // then use one older sequence number.
751 InstSeqNum squashed_inst = fromIEW->squashedSeqNum[tid];
752
753 if (fromIEW->includeSquashInst[tid] == true)
754 squashed_inst--;
755
756 // All younger instructions will be squashed. Set the sequence
757 // number as the youngest instruction in the ROB.
758 youngestSeqNum[tid] = squashed_inst;
759
760 rob->squash(squashed_inst, tid);
761 changedROBNumEntries[tid] = true;
762
763 toIEW->commitInfo[tid].doneSeqNum = squashed_inst;
764
765 toIEW->commitInfo[tid].squash = true;
766
767 // Send back the rob squashing signal so other stages know that
768 // the ROB is in the process of squashing.
769 toIEW->commitInfo[tid].robSquashing = true;
770
771 toIEW->commitInfo[tid].branchMispredict =
772 fromIEW->branchMispredict[tid];
773
774 toIEW->commitInfo[tid].branchTaken =
775 fromIEW->branchTaken[tid];
776
777 toIEW->commitInfo[tid].nextPC = fromIEW->nextPC[tid];
778
779 toIEW->commitInfo[tid].mispredPC = fromIEW->mispredPC[tid];
780
781 if (toIEW->commitInfo[tid].branchMispredict) {
782 ++branchMispredicts;
783 }
784 }
785
786 }
787
788 setNextStatus();
789
790 if (squashCounter != numThreads) {
791 // If we're not currently squashing, then get instructions.
792 getInsts();
793
794 // Try to commit any instructions.
795 commitInsts();
796 }
797
798 //Check for any activity
799 threads = (*activeThreads).begin();
800
801 while (threads != (*activeThreads).end()) {
802 unsigned tid = *threads++;
803
804 if (changedROBNumEntries[tid]) {
805 toIEW->commitInfo[tid].usedROB = true;
806 toIEW->commitInfo[tid].freeROBEntries = rob->numFreeEntries(tid);
807
808 if (rob->isEmpty(tid)) {
809 toIEW->commitInfo[tid].emptyROB = true;
810 }
811
812 wroteToTimeBuffer = true;
813 changedROBNumEntries[tid] = false;
814 }
815 }
816}
817
818template <class Impl>
819void
820DefaultCommit<Impl>::commitInsts()
821{
822 ////////////////////////////////////
823 // Handle commit
824 // Note that commit will be handled prior to putting new
825 // instructions in the ROB so that the ROB only tries to commit
826 // instructions it has in this current cycle, and not instructions
827 // it is writing in during this cycle. Can't commit and squash
828 // things at the same time...
829 ////////////////////////////////////
830
831 DPRINTF(Commit, "Trying to commit instructions in the ROB.\n");
832
833 unsigned num_committed = 0;
834
835 DynInstPtr head_inst;
836
837 // Commit as many instructions as possible until the commit bandwidth
838 // limit is reached, or it becomes impossible to commit any more.
839 while (num_committed < commitWidth) {
840 int commit_thread = getCommittingThread();
841
842 if (commit_thread == -1 || !rob->isHeadReady(commit_thread))
843 break;
844
845 head_inst = rob->readHeadInst(commit_thread);
846
847 int tid = head_inst->threadNumber;
848
849 assert(tid == commit_thread);
850
851 DPRINTF(Commit, "Trying to commit head instruction, [sn:%i] [tid:%i]\n",
852 head_inst->seqNum, tid);
853
854 // If the head instruction is squashed, it is ready to retire
855 // (be removed from the ROB) at any time.
856 if (head_inst->isSquashed()) {
857
858 DPRINTF(Commit, "Retiring squashed instruction from "
859 "ROB.\n");
860
861 rob->retireHead(commit_thread);
862
863 ++commitSquashedInsts;
864
865 // Record that the number of ROB entries has changed.
866 changedROBNumEntries[tid] = true;
867 } else {
868 PC[tid] = head_inst->readPC();
869 nextPC[tid] = head_inst->readNextPC();
870
871 // Increment the total number of non-speculative instructions
872 // executed.
873 // Hack for now: it really shouldn't happen until after the
874 // commit is deemed to be successful, but this count is needed
875 // for syscalls.
876 thread[tid]->funcExeInst++;
877
878 // Try to commit the head instruction.
879 bool commit_success = commitHead(head_inst, num_committed);
880
881 if (commit_success) {
882 ++num_committed;
883
884 changedROBNumEntries[tid] = true;
885
886 // Set the doneSeqNum to the youngest committed instruction.
887 toIEW->commitInfo[tid].doneSeqNum = head_inst->seqNum;
888
889 ++commitCommittedInsts;
890
891 // To match the old model, don't count nops and instruction
892 // prefetches towards the total commit count.
893 if (!head_inst->isNop() && !head_inst->isInstPrefetch()) {
894 cpu->instDone(tid);
895 }
896
897 PC[tid] = nextPC[tid];
898 nextPC[tid] = nextPC[tid] + sizeof(TheISA::MachInst);
899#if FULL_SYSTEM
900 int count = 0;
901 Addr oldpc;
902 do {
903 // Debug statement. Checks to make sure we're not
904 // currently updating state while handling PC events.
905 if (count == 0)
906 assert(!thread[tid]->inSyscall &&
907 !thread[tid]->trapPending);
908 oldpc = PC[tid];
909 cpu->system->pcEventQueue.service(
910 thread[tid]->getXCProxy());
911 count++;
912 } while (oldpc != PC[tid]);
913 if (count > 1) {
914 DPRINTF(Commit, "PC skip function event, stopping commit\n");
915 break;
916 }
917#endif
918 } else {
919 DPRINTF(Commit, "Unable to commit head instruction PC:%#x "
920 "[tid:%i] [sn:%i].\n",
921 head_inst->readPC(), tid ,head_inst->seqNum);
922 break;
923 }
924 }
925 }
926
927 DPRINTF(CommitRate, "%i\n", num_committed);
928 numCommittedDist.sample(num_committed);
929
930 if (num_committed == commitWidth) {
931 commitEligibleSamples++;
932 }
933}
934
935template <class Impl>
936bool
937DefaultCommit<Impl>::commitHead(DynInstPtr &head_inst, unsigned inst_num)
938{
939 assert(head_inst);
940
941 int tid = head_inst->threadNumber;
942
943 // If the instruction is not executed yet, then it will need extra
944 // handling. Signal backwards that it should be executed.
945 if (!head_inst->isExecuted()) {
946 // Keep this number correct. We have not yet actually executed
947 // and committed this instruction.
948 thread[tid]->funcExeInst--;
949
950 head_inst->reachedCommit = true;
951
952 if (head_inst->isNonSpeculative() ||
953 head_inst->isStoreConditional() ||
954 head_inst->isMemBarrier() ||
955 head_inst->isWriteBarrier()) {
956
957 DPRINTF(Commit, "Encountered a barrier or non-speculative "
958 "instruction [sn:%lli] at the head of the ROB, PC %#x.\n",
959 head_inst->seqNum, head_inst->readPC());
960
961#if !FULL_SYSTEM
962 // Hack to make sure syscalls/memory barriers/quiesces
963 // aren't executed until all stores write back their data.
964 // This direct communication shouldn't be used for
965 // anything other than this.
966 if (inst_num > 0 || iewStage->hasStoresToWB())
967#else
968 if ((head_inst->isMemBarrier() || head_inst->isWriteBarrier() ||
969 head_inst->isQuiesce()) &&
970 iewStage->hasStoresToWB())
971#endif
972 {
973 DPRINTF(Commit, "Waiting for all stores to writeback.\n");
974 return false;
975 }
976
977 toIEW->commitInfo[tid].nonSpecSeqNum = head_inst->seqNum;
978
979 // Change the instruction so it won't try to commit again until
980 // it is executed.
981 head_inst->clearCanCommit();
982
983 ++commitNonSpecStalls;
984
985 return false;
986 } else if (head_inst->isLoad()) {
987 DPRINTF(Commit, "[sn:%lli]: Uncached load, PC %#x.\n",
988 head_inst->seqNum, head_inst->readPC());
989
990 // Send back the non-speculative instruction's sequence
991 // number. Tell the lsq to re-execute the load.
992 toIEW->commitInfo[tid].nonSpecSeqNum = head_inst->seqNum;
993 toIEW->commitInfo[tid].uncached = true;
994 toIEW->commitInfo[tid].uncachedLoad = head_inst;
995
996 head_inst->clearCanCommit();
997
998 return false;
999 } else {
1000 panic("Trying to commit un-executed instruction "
1001 "of unknown type!\n");
1002 }
1003 }
1004
1005 if (head_inst->isThreadSync()) {
1006 // Not handled for now.
1007 panic("Thread sync instructions are not handled yet.\n");
1008 }
1009
1010 // Stores mark themselves as completed.
1011 if (!head_inst->isStore()) {
1012 head_inst->setCompleted();
1013 }
1014
1015 // Use checker prior to updating anything due to traps or PC
1016 // based events.
1017 if (cpu->checker) {
1018 cpu->checker->tick(head_inst);
1019 }
1020
1021 // Check if the instruction caused a fault. If so, trap.
1022 Fault inst_fault = head_inst->getFault();
1023
1024 if (inst_fault != NoFault) {
1025 head_inst->setCompleted();
1026#if FULL_SYSTEM
1027 DPRINTF(Commit, "Inst [sn:%lli] PC %#x has a fault\n",
1028 head_inst->seqNum, head_inst->readPC());
1029
1030 if (iewStage->hasStoresToWB() || inst_num > 0) {
1031 DPRINTF(Commit, "Stores outstanding, fault must wait.\n");
1032 return false;
1033 }
1034
1035 if (cpu->checker && head_inst->isStore()) {
1036 cpu->checker->tick(head_inst);
1037 }
1038
1039 assert(!thread[tid]->inSyscall);
1040
1041 // Mark that we're in state update mode so that the trap's
1042 // execution doesn't generate extra squashes.
1043 thread[tid]->inSyscall = true;
1044
1045 // DTB will sometimes need the machine instruction for when
1046 // faults happen. So we will set it here, prior to the DTB
1047 // possibly needing it for its fault.
1048 thread[tid]->setInst(
1049 static_cast<TheISA::MachInst>(head_inst->staticInst->machInst));
1050
1051 // Execute the trap. Although it's slightly unrealistic in
1052 // terms of timing (as it doesn't wait for the full timing of
1053 // the trap event to complete before updating state), it's
1054 // needed to update the state as soon as possible. This
1055 // prevents external agents from changing any specific state
1056 // that the trap need.
1057 cpu->trap(inst_fault, tid);
1058
1059 // Exit state update mode to avoid accidental updating.
1060 thread[tid]->inSyscall = false;
1061
1062 commitStatus[tid] = TrapPending;
1063
1064 // Generate trap squash event.
1065 generateTrapEvent(tid);
1066
1067 return false;
1068#else // !FULL_SYSTEM
1069 panic("fault (%d) detected @ PC %08p", inst_fault,
1070 head_inst->PC);
1071#endif // FULL_SYSTEM
1072 }
1073
1074 updateComInstStats(head_inst);
1075
1076 if (head_inst->traceData) {
1077 head_inst->traceData->setFetchSeq(head_inst->seqNum);
1078 head_inst->traceData->setCPSeq(thread[tid]->numInst);
1079 head_inst->traceData->finalize();
1080 head_inst->traceData = NULL;
1081 }
1082
1083 // Update the commit rename map
1084 for (int i = 0; i < head_inst->numDestRegs(); i++) {
1085 renameMap[tid]->setEntry(head_inst->destRegIdx(i),
1086 head_inst->renamedDestRegIdx(i));
1087 }
1088
1089 // Finally clear the head ROB entry.
1090 rob->retireHead(tid);
1091
1092 // Return true to indicate that we have committed an instruction.
1093 return true;
1094}
1095
1096template <class Impl>
1097void
1098DefaultCommit<Impl>::getInsts()
1099{
1100 // Read any renamed instructions and place them into the ROB.
1101 int insts_to_process = min((int)renameWidth, fromRename->size);
1102
1103 for (int inst_num = 0; inst_num < insts_to_process; ++inst_num)
1104 {
1105 DynInstPtr inst = fromRename->insts[inst_num];
1106 int tid = inst->threadNumber;
1107
1108 if (!inst->isSquashed() &&
1109 commitStatus[tid] != ROBSquashing) {
1110 changedROBNumEntries[tid] = true;
1111
1112 DPRINTF(Commit, "Inserting PC %#x [sn:%i] [tid:%i] into ROB.\n",
1113 inst->readPC(), inst->seqNum, tid);
1114
1115 rob->insertInst(inst);
1116
1117 assert(rob->getThreadEntries(tid) <= rob->getMaxEntries(tid));
1118
1119 youngestSeqNum[tid] = inst->seqNum;
1120 } else {
1121 DPRINTF(Commit, "Instruction PC %#x [sn:%i] [tid:%i] was "
1122 "squashed, skipping.\n",
1123 inst->readPC(), inst->seqNum, tid);
1124 }
1125 }
1126}
1127
1128template <class Impl>
1129void
1130DefaultCommit<Impl>::markCompletedInsts()
1131{
1132 // Grab completed insts out of the IEW instruction queue, and mark
1133 // instructions completed within the ROB.
1134 for (int inst_num = 0;
1135 inst_num < fromIEW->size && fromIEW->insts[inst_num];
1136 ++inst_num)
1137 {
1138 if (!fromIEW->insts[inst_num]->isSquashed()) {
1139 DPRINTF(Commit, "[tid:%i]: Marking PC %#x, [sn:%lli] ready "
1140 "within ROB.\n",
1141 fromIEW->insts[inst_num]->threadNumber,
1142 fromIEW->insts[inst_num]->readPC(),
1143 fromIEW->insts[inst_num]->seqNum);
1144
1145 // Mark the instruction as ready to commit.
1146 fromIEW->insts[inst_num]->setCanCommit();
1147 }
1148 }
1149}
1150
1151template <class Impl>
1152bool
1153DefaultCommit<Impl>::robDoneSquashing()
1154{
1155 list<unsigned>::iterator threads = (*activeThreads).begin();
1156
1157 while (threads != (*activeThreads).end()) {
1158 unsigned tid = *threads++;
1159
1160 if (!rob->isDoneSquashing(tid))
1161 return false;
1162 }
1163
1164 return true;
1165}
1166
1167template <class Impl>
1168void
1169DefaultCommit<Impl>::updateComInstStats(DynInstPtr &inst)
1170{
1171 unsigned thread = inst->threadNumber;
1172
1173 //
1174 // Pick off the software prefetches
1175 //
1176#ifdef TARGET_ALPHA
1177 if (inst->isDataPrefetch()) {
1178 statComSwp[thread]++;
1179 } else {
1180 statComInst[thread]++;
1181 }
1182#else
1183 statComInst[thread]++;
1184#endif
1185
1186 //
1187 // Control Instructions
1188 //
1189 if (inst->isControl())
1190 statComBranches[thread]++;
1191
1192 //
1193 // Memory references
1194 //
1195 if (inst->isMemRef()) {
1196 statComRefs[thread]++;
1197
1198 if (inst->isLoad()) {
1199 statComLoads[thread]++;
1200 }
1201 }
1202
1203 if (inst->isMemBarrier()) {
1204 statComMembars[thread]++;
1205 }
1206}
1207
1208////////////////////////////////////////
1209// //
1210// SMT COMMIT POLICY MAINTAINED HERE //
1211// //
1212////////////////////////////////////////
1213template <class Impl>
1214int
1215DefaultCommit<Impl>::getCommittingThread()
1216{
1217 if (numThreads > 1) {
1218 switch (commitPolicy) {
1219
1220 case Aggressive:
1221 //If Policy is Aggressive, commit will call
1222 //this function multiple times per
1223 //cycle
1224 return oldestReady();
1225
1226 case RoundRobin:
1227 return roundRobin();
1228
1229 case OldestReady:
1230 return oldestReady();
1231
1232 default:
1233 return -1;
1234 }
1235 } else {
1236 int tid = (*activeThreads).front();
1237
1238 if (commitStatus[tid] == Running ||
1239 commitStatus[tid] == Idle ||
1240 commitStatus[tid] == FetchTrapPending) {
1241 return tid;
1242 } else {
1243 return -1;
1244 }
1245 }
1246}
1247
1248template<class Impl>
1249int
1250DefaultCommit<Impl>::roundRobin()
1251{
1252 list<unsigned>::iterator pri_iter = priority_list.begin();
1253 list<unsigned>::iterator end = priority_list.end();
1254
1255 while (pri_iter != end) {
1256 unsigned tid = *pri_iter;
1257
1258 if (commitStatus[tid] == Running ||
1259 commitStatus[tid] == Idle) {
1260
1261 if (rob->isHeadReady(tid)) {
1262 priority_list.erase(pri_iter);
1263 priority_list.push_back(tid);
1264
1265 return tid;
1266 }
1267 }
1268
1269 pri_iter++;
1270 }
1271
1272 return -1;
1273}
1274
1275template<class Impl>
1276int
1277DefaultCommit<Impl>::oldestReady()
1278{
1279 unsigned oldest = 0;
1280 bool first = true;
1281
1282 list<unsigned>::iterator threads = (*activeThreads).begin();
1283
1284 while (threads != (*activeThreads).end()) {
1285 unsigned tid = *threads++;
1286
1287 if (!rob->isEmpty(tid) &&
1288 (commitStatus[tid] == Running ||
1289 commitStatus[tid] == Idle ||
1290 commitStatus[tid] == FetchTrapPending)) {
1291
1292 if (rob->isHeadReady(tid)) {
1293
1294 DynInstPtr head_inst = rob->readHeadInst(tid);
1295
1296 if (first) {
1297 oldest = tid;
1298 first = false;
1299 } else if (head_inst->seqNum < oldest) {
1300 oldest = tid;
1301 }
1302 }
1303 }
1304 }
1305
1306 if (!first) {
1307 return oldest;
1308 } else {
1309 return -1;
1310 }
1311}
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