1/*
2 * Copyright (c) 2010-2013 ARM Limited
3 * Copyright (c) 2013 Advanced Micro Devices, Inc.
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 */
43
44#ifndef __CPU_O3_IEW_IMPL_IMPL_HH__
45#define __CPU_O3_IEW_IMPL_IMPL_HH__
46
47// @todo: Fix the instantaneous communication among all the stages within
48// iew. There's a clear delay between issue and execute, yet backwards
49// communication happens simultaneously.
50
51#include <queue>
52
53#include "arch/utility.hh"
54#include "config/the_isa.hh"
55#include "cpu/checker/cpu.hh"
56#include "cpu/o3/fu_pool.hh"
57#include "cpu/o3/iew.hh"
58#include "cpu/timebuf.hh"
59#include "debug/Activity.hh"
60#include "debug/Drain.hh"
61#include "debug/IEW.hh"
62#include "debug/O3PipeView.hh"
63#include "params/DerivO3CPU.hh"
64
65using namespace std;
66
67template<class Impl>
68DefaultIEW<Impl>::DefaultIEW(O3CPU *_cpu, DerivO3CPUParams *params)
69 : issueToExecQueue(params->backComSize, params->forwardComSize),
70 cpu(_cpu),
71 instQueue(_cpu, this, params),
72 ldstQueue(_cpu, this, params),
73 fuPool(params->fuPool),
74 commitToIEWDelay(params->commitToIEWDelay),
75 renameToIEWDelay(params->renameToIEWDelay),
76 issueToExecuteDelay(params->issueToExecuteDelay),
77 dispatchWidth(params->dispatchWidth),
78 issueWidth(params->issueWidth),
79 wbWidth(params->wbWidth),
80 numThreads(params->numThreads)
81{
82 if (dispatchWidth > Impl::MaxWidth)
83 fatal("dispatchWidth (%d) is larger than compiled limit (%d),\n"
84 "\tincrease MaxWidth in src/cpu/o3/impl.hh\n",
85 dispatchWidth, static_cast<int>(Impl::MaxWidth));
86 if (issueWidth > Impl::MaxWidth)
87 fatal("issueWidth (%d) is larger than compiled limit (%d),\n"
88 "\tincrease MaxWidth in src/cpu/o3/impl.hh\n",
89 issueWidth, static_cast<int>(Impl::MaxWidth));
90 if (wbWidth > Impl::MaxWidth)
91 fatal("wbWidth (%d) is larger than compiled limit (%d),\n"
92 "\tincrease MaxWidth in src/cpu/o3/impl.hh\n",
93 wbWidth, static_cast<int>(Impl::MaxWidth));
94
95 _status = Active;
96 exeStatus = Running;
97 wbStatus = Idle;
98
99 // Setup wire to read instructions coming from issue.
100 fromIssue = issueToExecQueue.getWire(-issueToExecuteDelay);
101
102 // Instruction queue needs the queue between issue and execute.
103 instQueue.setIssueToExecuteQueue(&issueToExecQueue);
104
105 for (ThreadID tid = 0; tid < numThreads; tid++) {
106 dispatchStatus[tid] = Running;
107 fetchRedirect[tid] = false;
108 }
109
110 updateLSQNextCycle = false;
111
112 skidBufferMax = (renameToIEWDelay + 1) * params->renameWidth;
113}
114
115template <class Impl>
116std::string
117DefaultIEW<Impl>::name() const
118{
119 return cpu->name() + ".iew";
120}
121
122template <class Impl>
123void
124DefaultIEW<Impl>::regProbePoints()
125{
126 ppDispatch = new ProbePointArg<DynInstPtr>(cpu->getProbeManager(), "Dispatch");
127 ppMispredict = new ProbePointArg<DynInstPtr>(cpu->getProbeManager(), "Mispredict");
128 /**
129 * Probe point with dynamic instruction as the argument used to probe when
130 * an instruction starts to execute.
131 */
132 ppExecute = new ProbePointArg<DynInstPtr>(cpu->getProbeManager(),
133 "Execute");
134 /**
135 * Probe point with dynamic instruction as the argument used to probe when
136 * an instruction execution completes and it is marked ready to commit.
137 */
138 ppToCommit = new ProbePointArg<DynInstPtr>(cpu->getProbeManager(),
139 "ToCommit");
140}
141
142template <class Impl>
143void
144DefaultIEW<Impl>::regStats()
145{
146 using namespace Stats;
147
148 instQueue.regStats();
149 ldstQueue.regStats();
150
151 iewIdleCycles
152 .name(name() + ".iewIdleCycles")
153 .desc("Number of cycles IEW is idle");
154
155 iewSquashCycles
156 .name(name() + ".iewSquashCycles")
157 .desc("Number of cycles IEW is squashing");
158
159 iewBlockCycles
160 .name(name() + ".iewBlockCycles")
161 .desc("Number of cycles IEW is blocking");
162
163 iewUnblockCycles
164 .name(name() + ".iewUnblockCycles")
165 .desc("Number of cycles IEW is unblocking");
166
167 iewDispatchedInsts
168 .name(name() + ".iewDispatchedInsts")
169 .desc("Number of instructions dispatched to IQ");
170
171 iewDispSquashedInsts
172 .name(name() + ".iewDispSquashedInsts")
173 .desc("Number of squashed instructions skipped by dispatch");
174
175 iewDispLoadInsts
176 .name(name() + ".iewDispLoadInsts")
177 .desc("Number of dispatched load instructions");
178
179 iewDispStoreInsts
180 .name(name() + ".iewDispStoreInsts")
181 .desc("Number of dispatched store instructions");
182
183 iewDispNonSpecInsts
184 .name(name() + ".iewDispNonSpecInsts")
185 .desc("Number of dispatched non-speculative instructions");
186
187 iewIQFullEvents
188 .name(name() + ".iewIQFullEvents")
189 .desc("Number of times the IQ has become full, causing a stall");
190
191 iewLSQFullEvents
192 .name(name() + ".iewLSQFullEvents")
193 .desc("Number of times the LSQ has become full, causing a stall");
194
195 memOrderViolationEvents
196 .name(name() + ".memOrderViolationEvents")
197 .desc("Number of memory order violations");
198
199 predictedTakenIncorrect
200 .name(name() + ".predictedTakenIncorrect")
201 .desc("Number of branches that were predicted taken incorrectly");
202
203 predictedNotTakenIncorrect
204 .name(name() + ".predictedNotTakenIncorrect")
205 .desc("Number of branches that were predicted not taken incorrectly");
206
207 branchMispredicts
208 .name(name() + ".branchMispredicts")
209 .desc("Number of branch mispredicts detected at execute");
210
211 branchMispredicts = predictedTakenIncorrect + predictedNotTakenIncorrect;
212
213 iewExecutedInsts
214 .name(name() + ".iewExecutedInsts")
215 .desc("Number of executed instructions");
216
217 iewExecLoadInsts
218 .init(cpu->numThreads)
219 .name(name() + ".iewExecLoadInsts")
220 .desc("Number of load instructions executed")
221 .flags(total);
222
223 iewExecSquashedInsts
224 .name(name() + ".iewExecSquashedInsts")
225 .desc("Number of squashed instructions skipped in execute");
226
227 iewExecutedSwp
228 .init(cpu->numThreads)
229 .name(name() + ".exec_swp")
230 .desc("number of swp insts executed")
231 .flags(total);
232
233 iewExecutedNop
234 .init(cpu->numThreads)
235 .name(name() + ".exec_nop")
236 .desc("number of nop insts executed")
237 .flags(total);
238
239 iewExecutedRefs
240 .init(cpu->numThreads)
241 .name(name() + ".exec_refs")
242 .desc("number of memory reference insts executed")
243 .flags(total);
244
245 iewExecutedBranches
246 .init(cpu->numThreads)
247 .name(name() + ".exec_branches")
248 .desc("Number of branches executed")
249 .flags(total);
250
251 iewExecStoreInsts
252 .name(name() + ".exec_stores")
253 .desc("Number of stores executed")
254 .flags(total);
255 iewExecStoreInsts = iewExecutedRefs - iewExecLoadInsts;
256
257 iewExecRate
258 .name(name() + ".exec_rate")
259 .desc("Inst execution rate")
260 .flags(total);
261
262 iewExecRate = iewExecutedInsts / cpu->numCycles;
263
264 iewInstsToCommit
265 .init(cpu->numThreads)
266 .name(name() + ".wb_sent")
267 .desc("cumulative count of insts sent to commit")
268 .flags(total);
269
270 writebackCount
271 .init(cpu->numThreads)
272 .name(name() + ".wb_count")
273 .desc("cumulative count of insts written-back")
274 .flags(total);
275
276 producerInst
277 .init(cpu->numThreads)
278 .name(name() + ".wb_producers")
279 .desc("num instructions producing a value")
280 .flags(total);
281
282 consumerInst
283 .init(cpu->numThreads)
284 .name(name() + ".wb_consumers")
285 .desc("num instructions consuming a value")
286 .flags(total);
287
288 wbFanout
289 .name(name() + ".wb_fanout")
290 .desc("average fanout of values written-back")
291 .flags(total);
292
293 wbFanout = producerInst / consumerInst;
294
295 wbRate
296 .name(name() + ".wb_rate")
297 .desc("insts written-back per cycle")
298 .flags(total);
299 wbRate = writebackCount / cpu->numCycles;
300}
301
302template<class Impl>
303void
304DefaultIEW<Impl>::startupStage()
305{
306 for (ThreadID tid = 0; tid < numThreads; tid++) {
307 toRename->iewInfo[tid].usedIQ = true;
308 toRename->iewInfo[tid].freeIQEntries =
309 instQueue.numFreeEntries(tid);
310
311 toRename->iewInfo[tid].usedLSQ = true;
312 toRename->iewInfo[tid].freeLQEntries = ldstQueue.numFreeLoadEntries(tid);
313 toRename->iewInfo[tid].freeSQEntries = ldstQueue.numFreeStoreEntries(tid);
314 }
315
316 // Initialize the checker's dcache port here
317 if (cpu->checker) {
318 cpu->checker->setDcachePort(&cpu->getDataPort());
319 }
320
321 cpu->activateStage(O3CPU::IEWIdx);
322}
323
324template<class Impl>
325void
326DefaultIEW<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr)
327{
328 timeBuffer = tb_ptr;
329
330 // Setup wire to read information from time buffer, from commit.
331 fromCommit = timeBuffer->getWire(-commitToIEWDelay);
332
333 // Setup wire to write information back to previous stages.
334 toRename = timeBuffer->getWire(0);
335
336 toFetch = timeBuffer->getWire(0);
337
338 // Instruction queue also needs main time buffer.
339 instQueue.setTimeBuffer(tb_ptr);
340}
341
342template<class Impl>
343void
344DefaultIEW<Impl>::setRenameQueue(TimeBuffer<RenameStruct> *rq_ptr)
345{
346 renameQueue = rq_ptr;
347
348 // Setup wire to read information from rename queue.
349 fromRename = renameQueue->getWire(-renameToIEWDelay);
350}
351
352template<class Impl>
353void
354DefaultIEW<Impl>::setIEWQueue(TimeBuffer<IEWStruct> *iq_ptr)
355{
356 iewQueue = iq_ptr;
357
358 // Setup wire to write instructions to commit.
359 toCommit = iewQueue->getWire(0);
360}
361
362template<class Impl>
363void
364DefaultIEW<Impl>::setActiveThreads(list<ThreadID> *at_ptr)
365{
366 activeThreads = at_ptr;
367
368 ldstQueue.setActiveThreads(at_ptr);
369 instQueue.setActiveThreads(at_ptr);
370}
371
372template<class Impl>
373void
374DefaultIEW<Impl>::setScoreboard(Scoreboard *sb_ptr)
375{
376 scoreboard = sb_ptr;
377}
378
379template <class Impl>
380bool
381DefaultIEW<Impl>::isDrained() const
382{
383 bool drained = ldstQueue.isDrained() && instQueue.isDrained();
384
385 for (ThreadID tid = 0; tid < numThreads; tid++) {
386 if (!insts[tid].empty()) {
387 DPRINTF(Drain, "%i: Insts not empty.\n", tid);
388 drained = false;
389 }
390 if (!skidBuffer[tid].empty()) {
391 DPRINTF(Drain, "%i: Skid buffer not empty.\n", tid);
392 drained = false;
393 }
394 drained = drained && dispatchStatus[tid] == Running;
395 }
396
397 // Also check the FU pool as instructions are "stored" in FU
398 // completion events until they are done and not accounted for
399 // above
400 if (drained && !fuPool->isDrained()) {
401 DPRINTF(Drain, "FU pool still busy.\n");
402 drained = false;
403 }
404
405 return drained;
406}
407
408template <class Impl>
409void
410DefaultIEW<Impl>::drainSanityCheck() const
411{
412 assert(isDrained());
413
414 instQueue.drainSanityCheck();
415 ldstQueue.drainSanityCheck();
416}
417
418template <class Impl>
419void
420DefaultIEW<Impl>::takeOverFrom()
421{
422 // Reset all state.
423 _status = Active;
424 exeStatus = Running;
425 wbStatus = Idle;
426
427 instQueue.takeOverFrom();
428 ldstQueue.takeOverFrom();
429 fuPool->takeOverFrom();
430
431 startupStage();
432 cpu->activityThisCycle();
433
434 for (ThreadID tid = 0; tid < numThreads; tid++) {
435 dispatchStatus[tid] = Running;
436 fetchRedirect[tid] = false;
437 }
438
439 updateLSQNextCycle = false;
440
441 for (int i = 0; i < issueToExecQueue.getSize(); ++i) {
442 issueToExecQueue.advance();
443 }
444}
445
446template<class Impl>
447void
448DefaultIEW<Impl>::squash(ThreadID tid)
449{
450 DPRINTF(IEW, "[tid:%i]: Squashing all instructions.\n", tid);
451
452 // Tell the IQ to start squashing.
453 instQueue.squash(tid);
454
455 // Tell the LDSTQ to start squashing.
456 ldstQueue.squash(fromCommit->commitInfo[tid].doneSeqNum, tid);
457 updatedQueues = true;
458
459 // Clear the skid buffer in case it has any data in it.
460 DPRINTF(IEW, "[tid:%i]: Removing skidbuffer instructions until [sn:%i].\n",
461 tid, fromCommit->commitInfo[tid].doneSeqNum);
462
463 while (!skidBuffer[tid].empty()) {
464 if (skidBuffer[tid].front()->isLoad()) {
465 toRename->iewInfo[tid].dispatchedToLQ++;
466 }
467 if (skidBuffer[tid].front()->isStore()) {
468 toRename->iewInfo[tid].dispatchedToSQ++;
469 }
470
471 toRename->iewInfo[tid].dispatched++;
472
473 skidBuffer[tid].pop();
474 }
475
476 emptyRenameInsts(tid);
477}
478
479template<class Impl>
480void
481DefaultIEW<Impl>::squashDueToBranch(DynInstPtr &inst, ThreadID tid)
482{
483 DPRINTF(IEW, "[tid:%i]: Squashing from a specific instruction, PC: %s "
484 "[sn:%i].\n", tid, inst->pcState(), inst->seqNum);
485
486 if (!toCommit->squash[tid] ||
487 inst->seqNum < toCommit->squashedSeqNum[tid]) {
488 toCommit->squash[tid] = true;
489 toCommit->squashedSeqNum[tid] = inst->seqNum;
490 toCommit->branchTaken[tid] = inst->pcState().branching();
491
492 TheISA::PCState pc = inst->pcState();
493 TheISA::advancePC(pc, inst->staticInst);
494
495 toCommit->pc[tid] = pc;
496 toCommit->mispredictInst[tid] = inst;
497 toCommit->includeSquashInst[tid] = false;
498
499 wroteToTimeBuffer = true;
500 }
501
502}
503
504template<class Impl>
505void
506DefaultIEW<Impl>::squashDueToMemOrder(DynInstPtr &inst, ThreadID tid)
507{
508 DPRINTF(IEW, "[tid:%i]: Memory violation, squashing violator and younger "
509 "insts, PC: %s [sn:%i].\n", tid, inst->pcState(), inst->seqNum);
510 // Need to include inst->seqNum in the following comparison to cover the
511 // corner case when a branch misprediction and a memory violation for the
512 // same instruction (e.g. load PC) are detected in the same cycle. In this
513 // case the memory violator should take precedence over the branch
514 // misprediction because it requires the violator itself to be included in
515 // the squash.
516 if (!toCommit->squash[tid] ||
517 inst->seqNum <= toCommit->squashedSeqNum[tid]) {
518 toCommit->squash[tid] = true;
519
520 toCommit->squashedSeqNum[tid] = inst->seqNum;
521 toCommit->pc[tid] = inst->pcState();
522 toCommit->mispredictInst[tid] = NULL;
523
524 // Must include the memory violator in the squash.
525 toCommit->includeSquashInst[tid] = true;
526
527 wroteToTimeBuffer = true;
528 }
529}
530
531template<class Impl>
532void
533DefaultIEW<Impl>::block(ThreadID tid)
534{
535 DPRINTF(IEW, "[tid:%u]: Blocking.\n", tid);
536
537 if (dispatchStatus[tid] != Blocked &&
538 dispatchStatus[tid] != Unblocking) {
539 toRename->iewBlock[tid] = true;
540 wroteToTimeBuffer = true;
541 }
542
543 // Add the current inputs to the skid buffer so they can be
544 // reprocessed when this stage unblocks.
545 skidInsert(tid);
546
547 dispatchStatus[tid] = Blocked;
548}
549
550template<class Impl>
551void
552DefaultIEW<Impl>::unblock(ThreadID tid)
553{
554 DPRINTF(IEW, "[tid:%i]: Reading instructions out of the skid "
555 "buffer %u.\n",tid, tid);
556
557 // If the skid bufffer is empty, signal back to previous stages to unblock.
558 // Also switch status to running.
559 if (skidBuffer[tid].empty()) {
560 toRename->iewUnblock[tid] = true;
561 wroteToTimeBuffer = true;
562 DPRINTF(IEW, "[tid:%i]: Done unblocking.\n",tid);
563 dispatchStatus[tid] = Running;
564 }
565}
566
567template<class Impl>
568void
569DefaultIEW<Impl>::wakeDependents(DynInstPtr &inst)
570{
571 instQueue.wakeDependents(inst);
572}
573
574template<class Impl>
575void
576DefaultIEW<Impl>::rescheduleMemInst(DynInstPtr &inst)
577{
578 instQueue.rescheduleMemInst(inst);
579}
580
581template<class Impl>
582void
583DefaultIEW<Impl>::replayMemInst(DynInstPtr &inst)
584{
585 instQueue.replayMemInst(inst);
586}
587
588template<class Impl>
589void
590DefaultIEW<Impl>::blockMemInst(DynInstPtr& inst)
591{
592 instQueue.blockMemInst(inst);
593}
594
595template<class Impl>
596void
597DefaultIEW<Impl>::cacheUnblocked()
598{
599 instQueue.cacheUnblocked();
600}
601
602template<class Impl>
603void
604DefaultIEW<Impl>::instToCommit(DynInstPtr &inst)
605{
606 // This function should not be called after writebackInsts in a
607 // single cycle. That will cause problems with an instruction
608 // being added to the queue to commit without being processed by
609 // writebackInsts prior to being sent to commit.
610
611 // First check the time slot that this instruction will write
612 // to. If there are free write ports at the time, then go ahead
613 // and write the instruction to that time. If there are not,
614 // keep looking back to see where's the first time there's a
615 // free slot.
616 while ((*iewQueue)[wbCycle].insts[wbNumInst]) {
617 ++wbNumInst;
618 if (wbNumInst == wbWidth) {
619 ++wbCycle;
620 wbNumInst = 0;
621 }
622 }
623
624 DPRINTF(IEW, "Current wb cycle: %i, width: %i, numInst: %i\nwbActual:%i\n",
625 wbCycle, wbWidth, wbNumInst, wbCycle * wbWidth + wbNumInst);
626 // Add finished instruction to queue to commit.
627 (*iewQueue)[wbCycle].insts[wbNumInst] = inst;
628 (*iewQueue)[wbCycle].size++;
629}
630
631template <class Impl>
632unsigned
633DefaultIEW<Impl>::validInstsFromRename()
634{
635 unsigned inst_count = 0;
636
637 for (int i=0; i<fromRename->size; i++) {
638 if (!fromRename->insts[i]->isSquashed())
639 inst_count++;
640 }
641
642 return inst_count;
643}
644
645template<class Impl>
646void
647DefaultIEW<Impl>::skidInsert(ThreadID tid)
648{
649 DynInstPtr inst = NULL;
650
651 while (!insts[tid].empty()) {
652 inst = insts[tid].front();
653
654 insts[tid].pop();
655
656 DPRINTF(IEW,"[tid:%i]: Inserting [sn:%lli] PC:%s into "
657 "dispatch skidBuffer %i\n",tid, inst->seqNum,
658 inst->pcState(),tid);
659
660 skidBuffer[tid].push(inst);
661 }
662
663 assert(skidBuffer[tid].size() <= skidBufferMax &&
664 "Skidbuffer Exceeded Max Size");
665}
666
667template<class Impl>
668int
669DefaultIEW<Impl>::skidCount()
670{
671 int max=0;
672
673 list<ThreadID>::iterator threads = activeThreads->begin();
674 list<ThreadID>::iterator end = activeThreads->end();
675
676 while (threads != end) {
677 ThreadID tid = *threads++;
678 unsigned thread_count = skidBuffer[tid].size();
679 if (max < thread_count)
680 max = thread_count;
681 }
682
683 return max;
684}
685
686template<class Impl>
687bool
688DefaultIEW<Impl>::skidsEmpty()
689{
690 list<ThreadID>::iterator threads = activeThreads->begin();
691 list<ThreadID>::iterator end = activeThreads->end();
692
693 while (threads != end) {
694 ThreadID tid = *threads++;
695
696 if (!skidBuffer[tid].empty())
697 return false;
698 }
699
700 return true;
701}
702
703template <class Impl>
704void
705DefaultIEW<Impl>::updateStatus()
706{
707 bool any_unblocking = false;
708
709 list<ThreadID>::iterator threads = activeThreads->begin();
710 list<ThreadID>::iterator end = activeThreads->end();
711
712 while (threads != end) {
713 ThreadID tid = *threads++;
714
715 if (dispatchStatus[tid] == Unblocking) {
716 any_unblocking = true;
717 break;
718 }
719 }
720
721 // If there are no ready instructions waiting to be scheduled by the IQ,
722 // and there's no stores waiting to write back, and dispatch is not
723 // unblocking, then there is no internal activity for the IEW stage.
724 instQueue.intInstQueueReads++;
725 if (_status == Active && !instQueue.hasReadyInsts() &&
726 !ldstQueue.willWB() && !any_unblocking) {
727 DPRINTF(IEW, "IEW switching to idle\n");
728
729 deactivateStage();
730
731 _status = Inactive;
732 } else if (_status == Inactive && (instQueue.hasReadyInsts() ||
733 ldstQueue.willWB() ||
734 any_unblocking)) {
735 // Otherwise there is internal activity. Set to active.
736 DPRINTF(IEW, "IEW switching to active\n");
737
738 activateStage();
739
740 _status = Active;
741 }
742}
743
744template <class Impl>
745void
746DefaultIEW<Impl>::resetEntries()
747{
748 instQueue.resetEntries();
749 ldstQueue.resetEntries();
750}
751
752template <class Impl>
753bool
754DefaultIEW<Impl>::checkStall(ThreadID tid)
755{
756 bool ret_val(false);
757
758 if (fromCommit->commitInfo[tid].robSquashing) {
759 DPRINTF(IEW,"[tid:%i]: Stall from Commit stage detected.\n",tid);
760 ret_val = true;
761 } else if (instQueue.isFull(tid)) {
762 DPRINTF(IEW,"[tid:%i]: Stall: IQ is full.\n",tid);
763 ret_val = true;
764 }
765
766 return ret_val;
767}
768
769template <class Impl>
770void
771DefaultIEW<Impl>::checkSignalsAndUpdate(ThreadID tid)
772{
773 // Check if there's a squash signal, squash if there is
774 // Check stall signals, block if there is.
775 // If status was Blocked
776 // if so then go to unblocking
777 // If status was Squashing
778 // check if squashing is not high. Switch to running this cycle.
779
780 if (fromCommit->commitInfo[tid].squash) {
781 squash(tid);
782
783 if (dispatchStatus[tid] == Blocked ||
784 dispatchStatus[tid] == Unblocking) {
785 toRename->iewUnblock[tid] = true;
786 wroteToTimeBuffer = true;
787 }
788
789 dispatchStatus[tid] = Squashing;
790 fetchRedirect[tid] = false;
791 return;
792 }
793
794 if (fromCommit->commitInfo[tid].robSquashing) {
795 DPRINTF(IEW, "[tid:%i]: ROB is still squashing.\n", tid);
796
797 dispatchStatus[tid] = Squashing;
798 emptyRenameInsts(tid);
799 wroteToTimeBuffer = true;
800 }
801
802 if (checkStall(tid)) {
803 block(tid);
804 dispatchStatus[tid] = Blocked;
805 return;
806 }
807
808 if (dispatchStatus[tid] == Blocked) {
809 // Status from previous cycle was blocked, but there are no more stall
810 // conditions. Switch over to unblocking.
811 DPRINTF(IEW, "[tid:%i]: Done blocking, switching to unblocking.\n",
812 tid);
813
814 dispatchStatus[tid] = Unblocking;
815
816 unblock(tid);
817
818 return;
819 }
820
821 if (dispatchStatus[tid] == Squashing) {
822 // Switch status to running if rename isn't being told to block or
823 // squash this cycle.
824 DPRINTF(IEW, "[tid:%i]: Done squashing, switching to running.\n",
825 tid);
826
827 dispatchStatus[tid] = Running;
828
829 return;
830 }
831}
832
833template <class Impl>
834void
835DefaultIEW<Impl>::sortInsts()
836{
837 int insts_from_rename = fromRename->size;
838#ifdef DEBUG
839 for (ThreadID tid = 0; tid < numThreads; tid++)
840 assert(insts[tid].empty());
841#endif
842 for (int i = 0; i < insts_from_rename; ++i) {
843 insts[fromRename->insts[i]->threadNumber].push(fromRename->insts[i]);
844 }
845}
846
847template <class Impl>
848void
849DefaultIEW<Impl>::emptyRenameInsts(ThreadID tid)
850{
851 DPRINTF(IEW, "[tid:%i]: Removing incoming rename instructions\n", tid);
852
853 while (!insts[tid].empty()) {
854
855 if (insts[tid].front()->isLoad()) {
856 toRename->iewInfo[tid].dispatchedToLQ++;
857 }
858 if (insts[tid].front()->isStore()) {
859 toRename->iewInfo[tid].dispatchedToSQ++;
860 }
861
862 toRename->iewInfo[tid].dispatched++;
863
864 insts[tid].pop();
865 }
866}
867
868template <class Impl>
869void
870DefaultIEW<Impl>::wakeCPU()
871{
872 cpu->wakeCPU();
873}
874
875template <class Impl>
876void
877DefaultIEW<Impl>::activityThisCycle()
878{
879 DPRINTF(Activity, "Activity this cycle.\n");
880 cpu->activityThisCycle();
881}
882
883template <class Impl>
884inline void
885DefaultIEW<Impl>::activateStage()
886{
887 DPRINTF(Activity, "Activating stage.\n");
888 cpu->activateStage(O3CPU::IEWIdx);
889}
890
891template <class Impl>
892inline void
893DefaultIEW<Impl>::deactivateStage()
894{
895 DPRINTF(Activity, "Deactivating stage.\n");
896 cpu->deactivateStage(O3CPU::IEWIdx);
897}
898
899template<class Impl>
900void
901DefaultIEW<Impl>::dispatch(ThreadID tid)
902{
903 // If status is Running or idle,
904 // call dispatchInsts()
905 // If status is Unblocking,
906 // buffer any instructions coming from rename
907 // continue trying to empty skid buffer
908 // check if stall conditions have passed
909
910 if (dispatchStatus[tid] == Blocked) {
911 ++iewBlockCycles;
912
913 } else if (dispatchStatus[tid] == Squashing) {
914 ++iewSquashCycles;
915 }
916
917 // Dispatch should try to dispatch as many instructions as its bandwidth
918 // will allow, as long as it is not currently blocked.
919 if (dispatchStatus[tid] == Running ||
920 dispatchStatus[tid] == Idle) {
921 DPRINTF(IEW, "[tid:%i] Not blocked, so attempting to run "
922 "dispatch.\n", tid);
923
924 dispatchInsts(tid);
925 } else if (dispatchStatus[tid] == Unblocking) {
926 // Make sure that the skid buffer has something in it if the
927 // status is unblocking.
928 assert(!skidsEmpty());
929
930 // If the status was unblocking, then instructions from the skid
931 // buffer were used. Remove those instructions and handle
932 // the rest of unblocking.
933 dispatchInsts(tid);
934
935 ++iewUnblockCycles;
936
937 if (validInstsFromRename()) {
938 // Add the current inputs to the skid buffer so they can be
939 // reprocessed when this stage unblocks.
940 skidInsert(tid);
941 }
942
943 unblock(tid);
944 }
945}
946
947template <class Impl>
948void
949DefaultIEW<Impl>::dispatchInsts(ThreadID tid)
950{
951 // Obtain instructions from skid buffer if unblocking, or queue from rename
952 // otherwise.
953 std::queue<DynInstPtr> &insts_to_dispatch =
954 dispatchStatus[tid] == Unblocking ?
955 skidBuffer[tid] : insts[tid];
956
957 int insts_to_add = insts_to_dispatch.size();
958
959 DynInstPtr inst;
960 bool add_to_iq = false;
961 int dis_num_inst = 0;
962
963 // Loop through the instructions, putting them in the instruction
964 // queue.
965 for ( ; dis_num_inst < insts_to_add &&
966 dis_num_inst < dispatchWidth;
967 ++dis_num_inst)
968 {
969 inst = insts_to_dispatch.front();
970
971 if (dispatchStatus[tid] == Unblocking) {
972 DPRINTF(IEW, "[tid:%i]: Issue: Examining instruction from skid "
973 "buffer\n", tid);
974 }
975
976 // Make sure there's a valid instruction there.
977 assert(inst);
978
979 DPRINTF(IEW, "[tid:%i]: Issue: Adding PC %s [sn:%lli] [tid:%i] to "
980 "IQ.\n",
981 tid, inst->pcState(), inst->seqNum, inst->threadNumber);
982
983 // Be sure to mark these instructions as ready so that the
984 // commit stage can go ahead and execute them, and mark
985 // them as issued so the IQ doesn't reprocess them.
986
987 // Check for squashed instructions.
988 if (inst->isSquashed()) {
989 DPRINTF(IEW, "[tid:%i]: Issue: Squashed instruction encountered, "
990 "not adding to IQ.\n", tid);
991
992 ++iewDispSquashedInsts;
993
994 insts_to_dispatch.pop();
995
996 //Tell Rename That An Instruction has been processed
997 if (inst->isLoad()) {
998 toRename->iewInfo[tid].dispatchedToLQ++;
999 }
1000 if (inst->isStore()) {
1001 toRename->iewInfo[tid].dispatchedToSQ++;
1002 }
1003
1004 toRename->iewInfo[tid].dispatched++;
1005
1006 continue;
1007 }
1008
1009 // Check for full conditions.
1010 if (instQueue.isFull(tid)) {
1011 DPRINTF(IEW, "[tid:%i]: Issue: IQ has become full.\n", tid);
1012
1013 // Call function to start blocking.
1014 block(tid);
1015
1016 // Set unblock to false. Special case where we are using
1017 // skidbuffer (unblocking) instructions but then we still
1018 // get full in the IQ.
1019 toRename->iewUnblock[tid] = false;
1020
1021 ++iewIQFullEvents;
1022 break;
1023 }
1024
1025 // Check LSQ if inst is LD/ST
1026 if ((inst->isLoad() && ldstQueue.lqFull(tid)) ||
1027 (inst->isStore() && ldstQueue.sqFull(tid))) {
1028 DPRINTF(IEW, "[tid:%i]: Issue: %s has become full.\n",tid,
1029 inst->isLoad() ? "LQ" : "SQ");
1030
1031 // Call function to start blocking.
1032 block(tid);
1033
1034 // Set unblock to false. Special case where we are using
1035 // skidbuffer (unblocking) instructions but then we still
1036 // get full in the IQ.
1037 toRename->iewUnblock[tid] = false;
1038
1039 ++iewLSQFullEvents;
1040 break;
1041 }
1042
1043 // Otherwise issue the instruction just fine.
1044 if (inst->isLoad()) {
1045 DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1046 "encountered, adding to LSQ.\n", tid);
1047
1048 // Reserve a spot in the load store queue for this
1049 // memory access.
1050 ldstQueue.insertLoad(inst);
1051
1052 ++iewDispLoadInsts;
1053
1054 add_to_iq = true;
1055
1056 toRename->iewInfo[tid].dispatchedToLQ++;
1057 } else if (inst->isStore()) {
1058 DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1059 "encountered, adding to LSQ.\n", tid);
1060
1061 ldstQueue.insertStore(inst);
1062
1063 ++iewDispStoreInsts;
1064
1065 if (inst->isStoreConditional()) {
1066 // Store conditionals need to be set as "canCommit()"
1067 // so that commit can process them when they reach the
1068 // head of commit.
1069 // @todo: This is somewhat specific to Alpha.
1070 inst->setCanCommit();
1071 instQueue.insertNonSpec(inst);
1072 add_to_iq = false;
1073
1074 ++iewDispNonSpecInsts;
1075 } else {
1076 add_to_iq = true;
1077 }
1078
1079 toRename->iewInfo[tid].dispatchedToSQ++;
1080 } else if (inst->isMemBarrier() || inst->isWriteBarrier()) {
1081 // Same as non-speculative stores.
1082 inst->setCanCommit();
1083 instQueue.insertBarrier(inst);
1084 add_to_iq = false;
1085 } else if (inst->isNop()) {
1086 DPRINTF(IEW, "[tid:%i]: Issue: Nop instruction encountered, "
1087 "skipping.\n", tid);
1088
1089 inst->setIssued();
1090 inst->setExecuted();
1091 inst->setCanCommit();
1092
1093 instQueue.recordProducer(inst);
1094
1095 iewExecutedNop[tid]++;
1096
1097 add_to_iq = false;
1098 } else {
1099 assert(!inst->isExecuted());
1100 add_to_iq = true;
1101 }
1102
1103 if (inst->isNonSpeculative()) {
1104 DPRINTF(IEW, "[tid:%i]: Issue: Nonspeculative instruction "
1105 "encountered, skipping.\n", tid);
1106
1107 // Same as non-speculative stores.
1108 inst->setCanCommit();
1109
1110 // Specifically insert it as nonspeculative.
1111 instQueue.insertNonSpec(inst);
1112
1113 ++iewDispNonSpecInsts;
1114
1115 add_to_iq = false;
1116 }
1117
1118 // If the instruction queue is not full, then add the
1119 // instruction.
1120 if (add_to_iq) {
1121 instQueue.insert(inst);
1122 }
1123
1124 insts_to_dispatch.pop();
1125
1126 toRename->iewInfo[tid].dispatched++;
1127
1128 ++iewDispatchedInsts;
1129
1130#if TRACING_ON
1131 inst->dispatchTick = curTick() - inst->fetchTick;
1132#endif
1133 ppDispatch->notify(inst);
1134 }
1135
1136 if (!insts_to_dispatch.empty()) {
1137 DPRINTF(IEW,"[tid:%i]: Issue: Bandwidth Full. Blocking.\n", tid);
1138 block(tid);
1139 toRename->iewUnblock[tid] = false;
1140 }
1141
1142 if (dispatchStatus[tid] == Idle && dis_num_inst) {
1143 dispatchStatus[tid] = Running;
1144
1145 updatedQueues = true;
1146 }
1147
1148 dis_num_inst = 0;
1149}
1150
1151template <class Impl>
1152void
1153DefaultIEW<Impl>::printAvailableInsts()
1154{
1155 int inst = 0;
1156
1157 std::cout << "Available Instructions: ";
1158
1159 while (fromIssue->insts[inst]) {
1160
1161 if (inst%3==0) std::cout << "\n\t";
1162
1163 std::cout << "PC: " << fromIssue->insts[inst]->pcState()
1164 << " TN: " << fromIssue->insts[inst]->threadNumber
1165 << " SN: " << fromIssue->insts[inst]->seqNum << " | ";
1166
1167 inst++;
1168
1169 }
1170
1171 std::cout << "\n";
1172}
1173
1174template <class Impl>
1175void
1176DefaultIEW<Impl>::executeInsts()
1177{
1178 wbNumInst = 0;
1179 wbCycle = 0;
1180
1181 list<ThreadID>::iterator threads = activeThreads->begin();
1182 list<ThreadID>::iterator end = activeThreads->end();
1183
1184 while (threads != end) {
1185 ThreadID tid = *threads++;
1186 fetchRedirect[tid] = false;
1187 }
1188
1189 // Uncomment this if you want to see all available instructions.
1190 // @todo This doesn't actually work anymore, we should fix it.
1191// printAvailableInsts();
1192
1193 // Execute/writeback any instructions that are available.
1194 int insts_to_execute = fromIssue->size;
1195 int inst_num = 0;
1196 for (; inst_num < insts_to_execute;
1197 ++inst_num) {
1198
1199 DPRINTF(IEW, "Execute: Executing instructions from IQ.\n");
1200
1201 DynInstPtr inst = instQueue.getInstToExecute();
1202
1203 DPRINTF(IEW, "Execute: Processing PC %s, [tid:%i] [sn:%i].\n",
1204 inst->pcState(), inst->threadNumber,inst->seqNum);
1205
1206 // Notify potential listeners that this instruction has started
1207 // executing
1208 ppExecute->notify(inst);
1209
1210 // Check if the instruction is squashed; if so then skip it
1211 if (inst->isSquashed()) {
1212 DPRINTF(IEW, "Execute: Instruction was squashed. PC: %s, [tid:%i]"
1213 " [sn:%i]\n", inst->pcState(), inst->threadNumber,
1214 inst->seqNum);
1215
1216 // Consider this instruction executed so that commit can go
1217 // ahead and retire the instruction.
1218 inst->setExecuted();
1219
1220 // Not sure if I should set this here or just let commit try to
1221 // commit any squashed instructions. I like the latter a bit more.
1222 inst->setCanCommit();
1223
1224 ++iewExecSquashedInsts;
1225
1226 continue;
1227 }
1228
1229 Fault fault = NoFault;
1230
1231 // Execute instruction.
1232 // Note that if the instruction faults, it will be handled
1233 // at the commit stage.
1234 if (inst->isMemRef()) {
1235 DPRINTF(IEW, "Execute: Calculating address for memory "
1236 "reference.\n");
1237
1238 // Tell the LDSTQ to execute this instruction (if it is a load).
1239 if (inst->isLoad()) {
1240 // Loads will mark themselves as executed, and their writeback
1241 // event adds the instruction to the queue to commit
1242 fault = ldstQueue.executeLoad(inst);
1243
1244 if (inst->isTranslationDelayed() &&
1245 fault == NoFault) {
1246 // A hw page table walk is currently going on; the
1247 // instruction must be deferred.
1248 DPRINTF(IEW, "Execute: Delayed translation, deferring "
1249 "load.\n");
1250 instQueue.deferMemInst(inst);
1251 continue;
1252 }
1253
1254 if (inst->isDataPrefetch() || inst->isInstPrefetch()) {
1255 inst->fault = NoFault;
1256 }
1257 } else if (inst->isStore()) {
1258 fault = ldstQueue.executeStore(inst);
1259
1260 if (inst->isTranslationDelayed() &&
1261 fault == NoFault) {
1262 // A hw page table walk is currently going on; the
1263 // instruction must be deferred.
1264 DPRINTF(IEW, "Execute: Delayed translation, deferring "
1265 "store.\n");
1266 instQueue.deferMemInst(inst);
1267 continue;
1268 }
1269
1270 // If the store had a fault then it may not have a mem req
1271 if (fault != NoFault || !inst->readPredicate() ||
1272 !inst->isStoreConditional()) {
1273 // If the instruction faulted, then we need to send it along
1274 // to commit without the instruction completing.
1275 // Send this instruction to commit, also make sure iew stage
1276 // realizes there is activity.
1277 inst->setExecuted();
1278 instToCommit(inst);
1279 activityThisCycle();
1280 }
1281
1282 // Store conditionals will mark themselves as
1283 // executed, and their writeback event will add the
1284 // instruction to the queue to commit.
1285 } else {
1286 panic("Unexpected memory type!\n");
1287 }
1288
1289 } else {
1290 // If the instruction has already faulted, then skip executing it.
1291 // Such case can happen when it faulted during ITLB translation.
1292 // If we execute the instruction (even if it's a nop) the fault
1293 // will be replaced and we will lose it.
1294 if (inst->getFault() == NoFault) {
1295 inst->execute();
1296 if (!inst->readPredicate())
1297 inst->forwardOldRegs();
1298 }
1299
1300 inst->setExecuted();
1301
1302 instToCommit(inst);
1303 }
1304
1305 updateExeInstStats(inst);
1306
1307 // Check if branch prediction was correct, if not then we need
1308 // to tell commit to squash in flight instructions. Only
1309 // handle this if there hasn't already been something that
1310 // redirects fetch in this group of instructions.
1311
1312 // This probably needs to prioritize the redirects if a different
1313 // scheduler is used. Currently the scheduler schedules the oldest
1314 // instruction first, so the branch resolution order will be correct.
1315 ThreadID tid = inst->threadNumber;
1316
1317 if (!fetchRedirect[tid] ||
1318 !toCommit->squash[tid] ||
1319 toCommit->squashedSeqNum[tid] > inst->seqNum) {
1320
1321 // Prevent testing for misprediction on load instructions,
1322 // that have not been executed.
1323 bool loadNotExecuted = !inst->isExecuted() && inst->isLoad();
1324
1325 if (inst->mispredicted() && !loadNotExecuted) {
1326 fetchRedirect[tid] = true;
1327
1328 DPRINTF(IEW, "Execute: Branch mispredict detected.\n");
1329 DPRINTF(IEW, "Predicted target was PC: %s.\n",
1330 inst->readPredTarg());
1331 DPRINTF(IEW, "Execute: Redirecting fetch to PC: %s.\n",
1332 inst->pcState());
1333 // If incorrect, then signal the ROB that it must be squashed.
1334 squashDueToBranch(inst, tid);
1335
1336 ppMispredict->notify(inst);
1337
1338 if (inst->readPredTaken()) {
1339 predictedTakenIncorrect++;
1340 } else {
1341 predictedNotTakenIncorrect++;
1342 }
1343 } else if (ldstQueue.violation(tid)) {
1344 assert(inst->isMemRef());
1345 // If there was an ordering violation, then get the
1346 // DynInst that caused the violation. Note that this
1347 // clears the violation signal.
1348 DynInstPtr violator;
1349 violator = ldstQueue.getMemDepViolator(tid);
1350
1351 DPRINTF(IEW, "LDSTQ detected a violation. Violator PC: %s "
1352 "[sn:%lli], inst PC: %s [sn:%lli]. Addr is: %#x.\n",
1353 violator->pcState(), violator->seqNum,
1354 inst->pcState(), inst->seqNum, inst->physEffAddrLow);
1355
1356 fetchRedirect[tid] = true;
1357
1358 // Tell the instruction queue that a violation has occured.
1359 instQueue.violation(inst, violator);
1360
1361 // Squash.
1362 squashDueToMemOrder(violator, tid);
1363
1364 ++memOrderViolationEvents;
1365 }
1366 } else {
1367 // Reset any state associated with redirects that will not
1368 // be used.
1369 if (ldstQueue.violation(tid)) {
1370 assert(inst->isMemRef());
1371
1372 DynInstPtr violator = ldstQueue.getMemDepViolator(tid);
1373
1374 DPRINTF(IEW, "LDSTQ detected a violation. Violator PC: "
1375 "%s, inst PC: %s. Addr is: %#x.\n",
1376 violator->pcState(), inst->pcState(),
1377 inst->physEffAddrLow);
1378 DPRINTF(IEW, "Violation will not be handled because "
1379 "already squashing\n");
1380
1381 ++memOrderViolationEvents;
1382 }
1383 }
1384 }
1385
1386 // Update and record activity if we processed any instructions.
1387 if (inst_num) {
1388 if (exeStatus == Idle) {
1389 exeStatus = Running;
1390 }
1391
1392 updatedQueues = true;
1393
1394 cpu->activityThisCycle();
1395 }
1396
1397 // Need to reset this in case a writeback event needs to write into the
1398 // iew queue. That way the writeback event will write into the correct
1399 // spot in the queue.
1400 wbNumInst = 0;
1401
1402}
1403
1404template <class Impl>
1405void
1406DefaultIEW<Impl>::writebackInsts()
1407{
1408 // Loop through the head of the time buffer and wake any
1409 // dependents. These instructions are about to write back. Also
1410 // mark scoreboard that this instruction is finally complete.
1411 // Either have IEW have direct access to scoreboard, or have this
1412 // as part of backwards communication.
1413 for (int inst_num = 0; inst_num < wbWidth &&
1414 toCommit->insts[inst_num]; inst_num++) {
1415 DynInstPtr inst = toCommit->insts[inst_num];
1416 ThreadID tid = inst->threadNumber;
1417
1418 DPRINTF(IEW, "Sending instructions to commit, [sn:%lli] PC %s.\n",
1419 inst->seqNum, inst->pcState());
1420
1421 iewInstsToCommit[tid]++;
1422 // Notify potential listeners that execution is complete for this
1423 // instruction.
1424 ppToCommit->notify(inst);
1425
1426 // Some instructions will be sent to commit without having
1427 // executed because they need commit to handle them.
1428 // E.g. Strictly ordered loads have not actually executed when they
1429 // are first sent to commit. Instead commit must tell the LSQ
1430 // when it's ready to execute the strictly ordered load.
1431 if (!inst->isSquashed() && inst->isExecuted() && inst->getFault() == NoFault) {
1432 int dependents = instQueue.wakeDependents(inst);
1433
1434 for (int i = 0; i < inst->numDestRegs(); i++) {
1435 //mark as Ready
| 1/*
2 * Copyright (c) 2010-2013 ARM Limited
3 * Copyright (c) 2013 Advanced Micro Devices, Inc.
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 */
43
44#ifndef __CPU_O3_IEW_IMPL_IMPL_HH__
45#define __CPU_O3_IEW_IMPL_IMPL_HH__
46
47// @todo: Fix the instantaneous communication among all the stages within
48// iew. There's a clear delay between issue and execute, yet backwards
49// communication happens simultaneously.
50
51#include <queue>
52
53#include "arch/utility.hh"
54#include "config/the_isa.hh"
55#include "cpu/checker/cpu.hh"
56#include "cpu/o3/fu_pool.hh"
57#include "cpu/o3/iew.hh"
58#include "cpu/timebuf.hh"
59#include "debug/Activity.hh"
60#include "debug/Drain.hh"
61#include "debug/IEW.hh"
62#include "debug/O3PipeView.hh"
63#include "params/DerivO3CPU.hh"
64
65using namespace std;
66
67template<class Impl>
68DefaultIEW<Impl>::DefaultIEW(O3CPU *_cpu, DerivO3CPUParams *params)
69 : issueToExecQueue(params->backComSize, params->forwardComSize),
70 cpu(_cpu),
71 instQueue(_cpu, this, params),
72 ldstQueue(_cpu, this, params),
73 fuPool(params->fuPool),
74 commitToIEWDelay(params->commitToIEWDelay),
75 renameToIEWDelay(params->renameToIEWDelay),
76 issueToExecuteDelay(params->issueToExecuteDelay),
77 dispatchWidth(params->dispatchWidth),
78 issueWidth(params->issueWidth),
79 wbWidth(params->wbWidth),
80 numThreads(params->numThreads)
81{
82 if (dispatchWidth > Impl::MaxWidth)
83 fatal("dispatchWidth (%d) is larger than compiled limit (%d),\n"
84 "\tincrease MaxWidth in src/cpu/o3/impl.hh\n",
85 dispatchWidth, static_cast<int>(Impl::MaxWidth));
86 if (issueWidth > Impl::MaxWidth)
87 fatal("issueWidth (%d) is larger than compiled limit (%d),\n"
88 "\tincrease MaxWidth in src/cpu/o3/impl.hh\n",
89 issueWidth, static_cast<int>(Impl::MaxWidth));
90 if (wbWidth > Impl::MaxWidth)
91 fatal("wbWidth (%d) is larger than compiled limit (%d),\n"
92 "\tincrease MaxWidth in src/cpu/o3/impl.hh\n",
93 wbWidth, static_cast<int>(Impl::MaxWidth));
94
95 _status = Active;
96 exeStatus = Running;
97 wbStatus = Idle;
98
99 // Setup wire to read instructions coming from issue.
100 fromIssue = issueToExecQueue.getWire(-issueToExecuteDelay);
101
102 // Instruction queue needs the queue between issue and execute.
103 instQueue.setIssueToExecuteQueue(&issueToExecQueue);
104
105 for (ThreadID tid = 0; tid < numThreads; tid++) {
106 dispatchStatus[tid] = Running;
107 fetchRedirect[tid] = false;
108 }
109
110 updateLSQNextCycle = false;
111
112 skidBufferMax = (renameToIEWDelay + 1) * params->renameWidth;
113}
114
115template <class Impl>
116std::string
117DefaultIEW<Impl>::name() const
118{
119 return cpu->name() + ".iew";
120}
121
122template <class Impl>
123void
124DefaultIEW<Impl>::regProbePoints()
125{
126 ppDispatch = new ProbePointArg<DynInstPtr>(cpu->getProbeManager(), "Dispatch");
127 ppMispredict = new ProbePointArg<DynInstPtr>(cpu->getProbeManager(), "Mispredict");
128 /**
129 * Probe point with dynamic instruction as the argument used to probe when
130 * an instruction starts to execute.
131 */
132 ppExecute = new ProbePointArg<DynInstPtr>(cpu->getProbeManager(),
133 "Execute");
134 /**
135 * Probe point with dynamic instruction as the argument used to probe when
136 * an instruction execution completes and it is marked ready to commit.
137 */
138 ppToCommit = new ProbePointArg<DynInstPtr>(cpu->getProbeManager(),
139 "ToCommit");
140}
141
142template <class Impl>
143void
144DefaultIEW<Impl>::regStats()
145{
146 using namespace Stats;
147
148 instQueue.regStats();
149 ldstQueue.regStats();
150
151 iewIdleCycles
152 .name(name() + ".iewIdleCycles")
153 .desc("Number of cycles IEW is idle");
154
155 iewSquashCycles
156 .name(name() + ".iewSquashCycles")
157 .desc("Number of cycles IEW is squashing");
158
159 iewBlockCycles
160 .name(name() + ".iewBlockCycles")
161 .desc("Number of cycles IEW is blocking");
162
163 iewUnblockCycles
164 .name(name() + ".iewUnblockCycles")
165 .desc("Number of cycles IEW is unblocking");
166
167 iewDispatchedInsts
168 .name(name() + ".iewDispatchedInsts")
169 .desc("Number of instructions dispatched to IQ");
170
171 iewDispSquashedInsts
172 .name(name() + ".iewDispSquashedInsts")
173 .desc("Number of squashed instructions skipped by dispatch");
174
175 iewDispLoadInsts
176 .name(name() + ".iewDispLoadInsts")
177 .desc("Number of dispatched load instructions");
178
179 iewDispStoreInsts
180 .name(name() + ".iewDispStoreInsts")
181 .desc("Number of dispatched store instructions");
182
183 iewDispNonSpecInsts
184 .name(name() + ".iewDispNonSpecInsts")
185 .desc("Number of dispatched non-speculative instructions");
186
187 iewIQFullEvents
188 .name(name() + ".iewIQFullEvents")
189 .desc("Number of times the IQ has become full, causing a stall");
190
191 iewLSQFullEvents
192 .name(name() + ".iewLSQFullEvents")
193 .desc("Number of times the LSQ has become full, causing a stall");
194
195 memOrderViolationEvents
196 .name(name() + ".memOrderViolationEvents")
197 .desc("Number of memory order violations");
198
199 predictedTakenIncorrect
200 .name(name() + ".predictedTakenIncorrect")
201 .desc("Number of branches that were predicted taken incorrectly");
202
203 predictedNotTakenIncorrect
204 .name(name() + ".predictedNotTakenIncorrect")
205 .desc("Number of branches that were predicted not taken incorrectly");
206
207 branchMispredicts
208 .name(name() + ".branchMispredicts")
209 .desc("Number of branch mispredicts detected at execute");
210
211 branchMispredicts = predictedTakenIncorrect + predictedNotTakenIncorrect;
212
213 iewExecutedInsts
214 .name(name() + ".iewExecutedInsts")
215 .desc("Number of executed instructions");
216
217 iewExecLoadInsts
218 .init(cpu->numThreads)
219 .name(name() + ".iewExecLoadInsts")
220 .desc("Number of load instructions executed")
221 .flags(total);
222
223 iewExecSquashedInsts
224 .name(name() + ".iewExecSquashedInsts")
225 .desc("Number of squashed instructions skipped in execute");
226
227 iewExecutedSwp
228 .init(cpu->numThreads)
229 .name(name() + ".exec_swp")
230 .desc("number of swp insts executed")
231 .flags(total);
232
233 iewExecutedNop
234 .init(cpu->numThreads)
235 .name(name() + ".exec_nop")
236 .desc("number of nop insts executed")
237 .flags(total);
238
239 iewExecutedRefs
240 .init(cpu->numThreads)
241 .name(name() + ".exec_refs")
242 .desc("number of memory reference insts executed")
243 .flags(total);
244
245 iewExecutedBranches
246 .init(cpu->numThreads)
247 .name(name() + ".exec_branches")
248 .desc("Number of branches executed")
249 .flags(total);
250
251 iewExecStoreInsts
252 .name(name() + ".exec_stores")
253 .desc("Number of stores executed")
254 .flags(total);
255 iewExecStoreInsts = iewExecutedRefs - iewExecLoadInsts;
256
257 iewExecRate
258 .name(name() + ".exec_rate")
259 .desc("Inst execution rate")
260 .flags(total);
261
262 iewExecRate = iewExecutedInsts / cpu->numCycles;
263
264 iewInstsToCommit
265 .init(cpu->numThreads)
266 .name(name() + ".wb_sent")
267 .desc("cumulative count of insts sent to commit")
268 .flags(total);
269
270 writebackCount
271 .init(cpu->numThreads)
272 .name(name() + ".wb_count")
273 .desc("cumulative count of insts written-back")
274 .flags(total);
275
276 producerInst
277 .init(cpu->numThreads)
278 .name(name() + ".wb_producers")
279 .desc("num instructions producing a value")
280 .flags(total);
281
282 consumerInst
283 .init(cpu->numThreads)
284 .name(name() + ".wb_consumers")
285 .desc("num instructions consuming a value")
286 .flags(total);
287
288 wbFanout
289 .name(name() + ".wb_fanout")
290 .desc("average fanout of values written-back")
291 .flags(total);
292
293 wbFanout = producerInst / consumerInst;
294
295 wbRate
296 .name(name() + ".wb_rate")
297 .desc("insts written-back per cycle")
298 .flags(total);
299 wbRate = writebackCount / cpu->numCycles;
300}
301
302template<class Impl>
303void
304DefaultIEW<Impl>::startupStage()
305{
306 for (ThreadID tid = 0; tid < numThreads; tid++) {
307 toRename->iewInfo[tid].usedIQ = true;
308 toRename->iewInfo[tid].freeIQEntries =
309 instQueue.numFreeEntries(tid);
310
311 toRename->iewInfo[tid].usedLSQ = true;
312 toRename->iewInfo[tid].freeLQEntries = ldstQueue.numFreeLoadEntries(tid);
313 toRename->iewInfo[tid].freeSQEntries = ldstQueue.numFreeStoreEntries(tid);
314 }
315
316 // Initialize the checker's dcache port here
317 if (cpu->checker) {
318 cpu->checker->setDcachePort(&cpu->getDataPort());
319 }
320
321 cpu->activateStage(O3CPU::IEWIdx);
322}
323
324template<class Impl>
325void
326DefaultIEW<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr)
327{
328 timeBuffer = tb_ptr;
329
330 // Setup wire to read information from time buffer, from commit.
331 fromCommit = timeBuffer->getWire(-commitToIEWDelay);
332
333 // Setup wire to write information back to previous stages.
334 toRename = timeBuffer->getWire(0);
335
336 toFetch = timeBuffer->getWire(0);
337
338 // Instruction queue also needs main time buffer.
339 instQueue.setTimeBuffer(tb_ptr);
340}
341
342template<class Impl>
343void
344DefaultIEW<Impl>::setRenameQueue(TimeBuffer<RenameStruct> *rq_ptr)
345{
346 renameQueue = rq_ptr;
347
348 // Setup wire to read information from rename queue.
349 fromRename = renameQueue->getWire(-renameToIEWDelay);
350}
351
352template<class Impl>
353void
354DefaultIEW<Impl>::setIEWQueue(TimeBuffer<IEWStruct> *iq_ptr)
355{
356 iewQueue = iq_ptr;
357
358 // Setup wire to write instructions to commit.
359 toCommit = iewQueue->getWire(0);
360}
361
362template<class Impl>
363void
364DefaultIEW<Impl>::setActiveThreads(list<ThreadID> *at_ptr)
365{
366 activeThreads = at_ptr;
367
368 ldstQueue.setActiveThreads(at_ptr);
369 instQueue.setActiveThreads(at_ptr);
370}
371
372template<class Impl>
373void
374DefaultIEW<Impl>::setScoreboard(Scoreboard *sb_ptr)
375{
376 scoreboard = sb_ptr;
377}
378
379template <class Impl>
380bool
381DefaultIEW<Impl>::isDrained() const
382{
383 bool drained = ldstQueue.isDrained() && instQueue.isDrained();
384
385 for (ThreadID tid = 0; tid < numThreads; tid++) {
386 if (!insts[tid].empty()) {
387 DPRINTF(Drain, "%i: Insts not empty.\n", tid);
388 drained = false;
389 }
390 if (!skidBuffer[tid].empty()) {
391 DPRINTF(Drain, "%i: Skid buffer not empty.\n", tid);
392 drained = false;
393 }
394 drained = drained && dispatchStatus[tid] == Running;
395 }
396
397 // Also check the FU pool as instructions are "stored" in FU
398 // completion events until they are done and not accounted for
399 // above
400 if (drained && !fuPool->isDrained()) {
401 DPRINTF(Drain, "FU pool still busy.\n");
402 drained = false;
403 }
404
405 return drained;
406}
407
408template <class Impl>
409void
410DefaultIEW<Impl>::drainSanityCheck() const
411{
412 assert(isDrained());
413
414 instQueue.drainSanityCheck();
415 ldstQueue.drainSanityCheck();
416}
417
418template <class Impl>
419void
420DefaultIEW<Impl>::takeOverFrom()
421{
422 // Reset all state.
423 _status = Active;
424 exeStatus = Running;
425 wbStatus = Idle;
426
427 instQueue.takeOverFrom();
428 ldstQueue.takeOverFrom();
429 fuPool->takeOverFrom();
430
431 startupStage();
432 cpu->activityThisCycle();
433
434 for (ThreadID tid = 0; tid < numThreads; tid++) {
435 dispatchStatus[tid] = Running;
436 fetchRedirect[tid] = false;
437 }
438
439 updateLSQNextCycle = false;
440
441 for (int i = 0; i < issueToExecQueue.getSize(); ++i) {
442 issueToExecQueue.advance();
443 }
444}
445
446template<class Impl>
447void
448DefaultIEW<Impl>::squash(ThreadID tid)
449{
450 DPRINTF(IEW, "[tid:%i]: Squashing all instructions.\n", tid);
451
452 // Tell the IQ to start squashing.
453 instQueue.squash(tid);
454
455 // Tell the LDSTQ to start squashing.
456 ldstQueue.squash(fromCommit->commitInfo[tid].doneSeqNum, tid);
457 updatedQueues = true;
458
459 // Clear the skid buffer in case it has any data in it.
460 DPRINTF(IEW, "[tid:%i]: Removing skidbuffer instructions until [sn:%i].\n",
461 tid, fromCommit->commitInfo[tid].doneSeqNum);
462
463 while (!skidBuffer[tid].empty()) {
464 if (skidBuffer[tid].front()->isLoad()) {
465 toRename->iewInfo[tid].dispatchedToLQ++;
466 }
467 if (skidBuffer[tid].front()->isStore()) {
468 toRename->iewInfo[tid].dispatchedToSQ++;
469 }
470
471 toRename->iewInfo[tid].dispatched++;
472
473 skidBuffer[tid].pop();
474 }
475
476 emptyRenameInsts(tid);
477}
478
479template<class Impl>
480void
481DefaultIEW<Impl>::squashDueToBranch(DynInstPtr &inst, ThreadID tid)
482{
483 DPRINTF(IEW, "[tid:%i]: Squashing from a specific instruction, PC: %s "
484 "[sn:%i].\n", tid, inst->pcState(), inst->seqNum);
485
486 if (!toCommit->squash[tid] ||
487 inst->seqNum < toCommit->squashedSeqNum[tid]) {
488 toCommit->squash[tid] = true;
489 toCommit->squashedSeqNum[tid] = inst->seqNum;
490 toCommit->branchTaken[tid] = inst->pcState().branching();
491
492 TheISA::PCState pc = inst->pcState();
493 TheISA::advancePC(pc, inst->staticInst);
494
495 toCommit->pc[tid] = pc;
496 toCommit->mispredictInst[tid] = inst;
497 toCommit->includeSquashInst[tid] = false;
498
499 wroteToTimeBuffer = true;
500 }
501
502}
503
504template<class Impl>
505void
506DefaultIEW<Impl>::squashDueToMemOrder(DynInstPtr &inst, ThreadID tid)
507{
508 DPRINTF(IEW, "[tid:%i]: Memory violation, squashing violator and younger "
509 "insts, PC: %s [sn:%i].\n", tid, inst->pcState(), inst->seqNum);
510 // Need to include inst->seqNum in the following comparison to cover the
511 // corner case when a branch misprediction and a memory violation for the
512 // same instruction (e.g. load PC) are detected in the same cycle. In this
513 // case the memory violator should take precedence over the branch
514 // misprediction because it requires the violator itself to be included in
515 // the squash.
516 if (!toCommit->squash[tid] ||
517 inst->seqNum <= toCommit->squashedSeqNum[tid]) {
518 toCommit->squash[tid] = true;
519
520 toCommit->squashedSeqNum[tid] = inst->seqNum;
521 toCommit->pc[tid] = inst->pcState();
522 toCommit->mispredictInst[tid] = NULL;
523
524 // Must include the memory violator in the squash.
525 toCommit->includeSquashInst[tid] = true;
526
527 wroteToTimeBuffer = true;
528 }
529}
530
531template<class Impl>
532void
533DefaultIEW<Impl>::block(ThreadID tid)
534{
535 DPRINTF(IEW, "[tid:%u]: Blocking.\n", tid);
536
537 if (dispatchStatus[tid] != Blocked &&
538 dispatchStatus[tid] != Unblocking) {
539 toRename->iewBlock[tid] = true;
540 wroteToTimeBuffer = true;
541 }
542
543 // Add the current inputs to the skid buffer so they can be
544 // reprocessed when this stage unblocks.
545 skidInsert(tid);
546
547 dispatchStatus[tid] = Blocked;
548}
549
550template<class Impl>
551void
552DefaultIEW<Impl>::unblock(ThreadID tid)
553{
554 DPRINTF(IEW, "[tid:%i]: Reading instructions out of the skid "
555 "buffer %u.\n",tid, tid);
556
557 // If the skid bufffer is empty, signal back to previous stages to unblock.
558 // Also switch status to running.
559 if (skidBuffer[tid].empty()) {
560 toRename->iewUnblock[tid] = true;
561 wroteToTimeBuffer = true;
562 DPRINTF(IEW, "[tid:%i]: Done unblocking.\n",tid);
563 dispatchStatus[tid] = Running;
564 }
565}
566
567template<class Impl>
568void
569DefaultIEW<Impl>::wakeDependents(DynInstPtr &inst)
570{
571 instQueue.wakeDependents(inst);
572}
573
574template<class Impl>
575void
576DefaultIEW<Impl>::rescheduleMemInst(DynInstPtr &inst)
577{
578 instQueue.rescheduleMemInst(inst);
579}
580
581template<class Impl>
582void
583DefaultIEW<Impl>::replayMemInst(DynInstPtr &inst)
584{
585 instQueue.replayMemInst(inst);
586}
587
588template<class Impl>
589void
590DefaultIEW<Impl>::blockMemInst(DynInstPtr& inst)
591{
592 instQueue.blockMemInst(inst);
593}
594
595template<class Impl>
596void
597DefaultIEW<Impl>::cacheUnblocked()
598{
599 instQueue.cacheUnblocked();
600}
601
602template<class Impl>
603void
604DefaultIEW<Impl>::instToCommit(DynInstPtr &inst)
605{
606 // This function should not be called after writebackInsts in a
607 // single cycle. That will cause problems with an instruction
608 // being added to the queue to commit without being processed by
609 // writebackInsts prior to being sent to commit.
610
611 // First check the time slot that this instruction will write
612 // to. If there are free write ports at the time, then go ahead
613 // and write the instruction to that time. If there are not,
614 // keep looking back to see where's the first time there's a
615 // free slot.
616 while ((*iewQueue)[wbCycle].insts[wbNumInst]) {
617 ++wbNumInst;
618 if (wbNumInst == wbWidth) {
619 ++wbCycle;
620 wbNumInst = 0;
621 }
622 }
623
624 DPRINTF(IEW, "Current wb cycle: %i, width: %i, numInst: %i\nwbActual:%i\n",
625 wbCycle, wbWidth, wbNumInst, wbCycle * wbWidth + wbNumInst);
626 // Add finished instruction to queue to commit.
627 (*iewQueue)[wbCycle].insts[wbNumInst] = inst;
628 (*iewQueue)[wbCycle].size++;
629}
630
631template <class Impl>
632unsigned
633DefaultIEW<Impl>::validInstsFromRename()
634{
635 unsigned inst_count = 0;
636
637 for (int i=0; i<fromRename->size; i++) {
638 if (!fromRename->insts[i]->isSquashed())
639 inst_count++;
640 }
641
642 return inst_count;
643}
644
645template<class Impl>
646void
647DefaultIEW<Impl>::skidInsert(ThreadID tid)
648{
649 DynInstPtr inst = NULL;
650
651 while (!insts[tid].empty()) {
652 inst = insts[tid].front();
653
654 insts[tid].pop();
655
656 DPRINTF(IEW,"[tid:%i]: Inserting [sn:%lli] PC:%s into "
657 "dispatch skidBuffer %i\n",tid, inst->seqNum,
658 inst->pcState(),tid);
659
660 skidBuffer[tid].push(inst);
661 }
662
663 assert(skidBuffer[tid].size() <= skidBufferMax &&
664 "Skidbuffer Exceeded Max Size");
665}
666
667template<class Impl>
668int
669DefaultIEW<Impl>::skidCount()
670{
671 int max=0;
672
673 list<ThreadID>::iterator threads = activeThreads->begin();
674 list<ThreadID>::iterator end = activeThreads->end();
675
676 while (threads != end) {
677 ThreadID tid = *threads++;
678 unsigned thread_count = skidBuffer[tid].size();
679 if (max < thread_count)
680 max = thread_count;
681 }
682
683 return max;
684}
685
686template<class Impl>
687bool
688DefaultIEW<Impl>::skidsEmpty()
689{
690 list<ThreadID>::iterator threads = activeThreads->begin();
691 list<ThreadID>::iterator end = activeThreads->end();
692
693 while (threads != end) {
694 ThreadID tid = *threads++;
695
696 if (!skidBuffer[tid].empty())
697 return false;
698 }
699
700 return true;
701}
702
703template <class Impl>
704void
705DefaultIEW<Impl>::updateStatus()
706{
707 bool any_unblocking = false;
708
709 list<ThreadID>::iterator threads = activeThreads->begin();
710 list<ThreadID>::iterator end = activeThreads->end();
711
712 while (threads != end) {
713 ThreadID tid = *threads++;
714
715 if (dispatchStatus[tid] == Unblocking) {
716 any_unblocking = true;
717 break;
718 }
719 }
720
721 // If there are no ready instructions waiting to be scheduled by the IQ,
722 // and there's no stores waiting to write back, and dispatch is not
723 // unblocking, then there is no internal activity for the IEW stage.
724 instQueue.intInstQueueReads++;
725 if (_status == Active && !instQueue.hasReadyInsts() &&
726 !ldstQueue.willWB() && !any_unblocking) {
727 DPRINTF(IEW, "IEW switching to idle\n");
728
729 deactivateStage();
730
731 _status = Inactive;
732 } else if (_status == Inactive && (instQueue.hasReadyInsts() ||
733 ldstQueue.willWB() ||
734 any_unblocking)) {
735 // Otherwise there is internal activity. Set to active.
736 DPRINTF(IEW, "IEW switching to active\n");
737
738 activateStage();
739
740 _status = Active;
741 }
742}
743
744template <class Impl>
745void
746DefaultIEW<Impl>::resetEntries()
747{
748 instQueue.resetEntries();
749 ldstQueue.resetEntries();
750}
751
752template <class Impl>
753bool
754DefaultIEW<Impl>::checkStall(ThreadID tid)
755{
756 bool ret_val(false);
757
758 if (fromCommit->commitInfo[tid].robSquashing) {
759 DPRINTF(IEW,"[tid:%i]: Stall from Commit stage detected.\n",tid);
760 ret_val = true;
761 } else if (instQueue.isFull(tid)) {
762 DPRINTF(IEW,"[tid:%i]: Stall: IQ is full.\n",tid);
763 ret_val = true;
764 }
765
766 return ret_val;
767}
768
769template <class Impl>
770void
771DefaultIEW<Impl>::checkSignalsAndUpdate(ThreadID tid)
772{
773 // Check if there's a squash signal, squash if there is
774 // Check stall signals, block if there is.
775 // If status was Blocked
776 // if so then go to unblocking
777 // If status was Squashing
778 // check if squashing is not high. Switch to running this cycle.
779
780 if (fromCommit->commitInfo[tid].squash) {
781 squash(tid);
782
783 if (dispatchStatus[tid] == Blocked ||
784 dispatchStatus[tid] == Unblocking) {
785 toRename->iewUnblock[tid] = true;
786 wroteToTimeBuffer = true;
787 }
788
789 dispatchStatus[tid] = Squashing;
790 fetchRedirect[tid] = false;
791 return;
792 }
793
794 if (fromCommit->commitInfo[tid].robSquashing) {
795 DPRINTF(IEW, "[tid:%i]: ROB is still squashing.\n", tid);
796
797 dispatchStatus[tid] = Squashing;
798 emptyRenameInsts(tid);
799 wroteToTimeBuffer = true;
800 }
801
802 if (checkStall(tid)) {
803 block(tid);
804 dispatchStatus[tid] = Blocked;
805 return;
806 }
807
808 if (dispatchStatus[tid] == Blocked) {
809 // Status from previous cycle was blocked, but there are no more stall
810 // conditions. Switch over to unblocking.
811 DPRINTF(IEW, "[tid:%i]: Done blocking, switching to unblocking.\n",
812 tid);
813
814 dispatchStatus[tid] = Unblocking;
815
816 unblock(tid);
817
818 return;
819 }
820
821 if (dispatchStatus[tid] == Squashing) {
822 // Switch status to running if rename isn't being told to block or
823 // squash this cycle.
824 DPRINTF(IEW, "[tid:%i]: Done squashing, switching to running.\n",
825 tid);
826
827 dispatchStatus[tid] = Running;
828
829 return;
830 }
831}
832
833template <class Impl>
834void
835DefaultIEW<Impl>::sortInsts()
836{
837 int insts_from_rename = fromRename->size;
838#ifdef DEBUG
839 for (ThreadID tid = 0; tid < numThreads; tid++)
840 assert(insts[tid].empty());
841#endif
842 for (int i = 0; i < insts_from_rename; ++i) {
843 insts[fromRename->insts[i]->threadNumber].push(fromRename->insts[i]);
844 }
845}
846
847template <class Impl>
848void
849DefaultIEW<Impl>::emptyRenameInsts(ThreadID tid)
850{
851 DPRINTF(IEW, "[tid:%i]: Removing incoming rename instructions\n", tid);
852
853 while (!insts[tid].empty()) {
854
855 if (insts[tid].front()->isLoad()) {
856 toRename->iewInfo[tid].dispatchedToLQ++;
857 }
858 if (insts[tid].front()->isStore()) {
859 toRename->iewInfo[tid].dispatchedToSQ++;
860 }
861
862 toRename->iewInfo[tid].dispatched++;
863
864 insts[tid].pop();
865 }
866}
867
868template <class Impl>
869void
870DefaultIEW<Impl>::wakeCPU()
871{
872 cpu->wakeCPU();
873}
874
875template <class Impl>
876void
877DefaultIEW<Impl>::activityThisCycle()
878{
879 DPRINTF(Activity, "Activity this cycle.\n");
880 cpu->activityThisCycle();
881}
882
883template <class Impl>
884inline void
885DefaultIEW<Impl>::activateStage()
886{
887 DPRINTF(Activity, "Activating stage.\n");
888 cpu->activateStage(O3CPU::IEWIdx);
889}
890
891template <class Impl>
892inline void
893DefaultIEW<Impl>::deactivateStage()
894{
895 DPRINTF(Activity, "Deactivating stage.\n");
896 cpu->deactivateStage(O3CPU::IEWIdx);
897}
898
899template<class Impl>
900void
901DefaultIEW<Impl>::dispatch(ThreadID tid)
902{
903 // If status is Running or idle,
904 // call dispatchInsts()
905 // If status is Unblocking,
906 // buffer any instructions coming from rename
907 // continue trying to empty skid buffer
908 // check if stall conditions have passed
909
910 if (dispatchStatus[tid] == Blocked) {
911 ++iewBlockCycles;
912
913 } else if (dispatchStatus[tid] == Squashing) {
914 ++iewSquashCycles;
915 }
916
917 // Dispatch should try to dispatch as many instructions as its bandwidth
918 // will allow, as long as it is not currently blocked.
919 if (dispatchStatus[tid] == Running ||
920 dispatchStatus[tid] == Idle) {
921 DPRINTF(IEW, "[tid:%i] Not blocked, so attempting to run "
922 "dispatch.\n", tid);
923
924 dispatchInsts(tid);
925 } else if (dispatchStatus[tid] == Unblocking) {
926 // Make sure that the skid buffer has something in it if the
927 // status is unblocking.
928 assert(!skidsEmpty());
929
930 // If the status was unblocking, then instructions from the skid
931 // buffer were used. Remove those instructions and handle
932 // the rest of unblocking.
933 dispatchInsts(tid);
934
935 ++iewUnblockCycles;
936
937 if (validInstsFromRename()) {
938 // Add the current inputs to the skid buffer so they can be
939 // reprocessed when this stage unblocks.
940 skidInsert(tid);
941 }
942
943 unblock(tid);
944 }
945}
946
947template <class Impl>
948void
949DefaultIEW<Impl>::dispatchInsts(ThreadID tid)
950{
951 // Obtain instructions from skid buffer if unblocking, or queue from rename
952 // otherwise.
953 std::queue<DynInstPtr> &insts_to_dispatch =
954 dispatchStatus[tid] == Unblocking ?
955 skidBuffer[tid] : insts[tid];
956
957 int insts_to_add = insts_to_dispatch.size();
958
959 DynInstPtr inst;
960 bool add_to_iq = false;
961 int dis_num_inst = 0;
962
963 // Loop through the instructions, putting them in the instruction
964 // queue.
965 for ( ; dis_num_inst < insts_to_add &&
966 dis_num_inst < dispatchWidth;
967 ++dis_num_inst)
968 {
969 inst = insts_to_dispatch.front();
970
971 if (dispatchStatus[tid] == Unblocking) {
972 DPRINTF(IEW, "[tid:%i]: Issue: Examining instruction from skid "
973 "buffer\n", tid);
974 }
975
976 // Make sure there's a valid instruction there.
977 assert(inst);
978
979 DPRINTF(IEW, "[tid:%i]: Issue: Adding PC %s [sn:%lli] [tid:%i] to "
980 "IQ.\n",
981 tid, inst->pcState(), inst->seqNum, inst->threadNumber);
982
983 // Be sure to mark these instructions as ready so that the
984 // commit stage can go ahead and execute them, and mark
985 // them as issued so the IQ doesn't reprocess them.
986
987 // Check for squashed instructions.
988 if (inst->isSquashed()) {
989 DPRINTF(IEW, "[tid:%i]: Issue: Squashed instruction encountered, "
990 "not adding to IQ.\n", tid);
991
992 ++iewDispSquashedInsts;
993
994 insts_to_dispatch.pop();
995
996 //Tell Rename That An Instruction has been processed
997 if (inst->isLoad()) {
998 toRename->iewInfo[tid].dispatchedToLQ++;
999 }
1000 if (inst->isStore()) {
1001 toRename->iewInfo[tid].dispatchedToSQ++;
1002 }
1003
1004 toRename->iewInfo[tid].dispatched++;
1005
1006 continue;
1007 }
1008
1009 // Check for full conditions.
1010 if (instQueue.isFull(tid)) {
1011 DPRINTF(IEW, "[tid:%i]: Issue: IQ has become full.\n", tid);
1012
1013 // Call function to start blocking.
1014 block(tid);
1015
1016 // Set unblock to false. Special case where we are using
1017 // skidbuffer (unblocking) instructions but then we still
1018 // get full in the IQ.
1019 toRename->iewUnblock[tid] = false;
1020
1021 ++iewIQFullEvents;
1022 break;
1023 }
1024
1025 // Check LSQ if inst is LD/ST
1026 if ((inst->isLoad() && ldstQueue.lqFull(tid)) ||
1027 (inst->isStore() && ldstQueue.sqFull(tid))) {
1028 DPRINTF(IEW, "[tid:%i]: Issue: %s has become full.\n",tid,
1029 inst->isLoad() ? "LQ" : "SQ");
1030
1031 // Call function to start blocking.
1032 block(tid);
1033
1034 // Set unblock to false. Special case where we are using
1035 // skidbuffer (unblocking) instructions but then we still
1036 // get full in the IQ.
1037 toRename->iewUnblock[tid] = false;
1038
1039 ++iewLSQFullEvents;
1040 break;
1041 }
1042
1043 // Otherwise issue the instruction just fine.
1044 if (inst->isLoad()) {
1045 DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1046 "encountered, adding to LSQ.\n", tid);
1047
1048 // Reserve a spot in the load store queue for this
1049 // memory access.
1050 ldstQueue.insertLoad(inst);
1051
1052 ++iewDispLoadInsts;
1053
1054 add_to_iq = true;
1055
1056 toRename->iewInfo[tid].dispatchedToLQ++;
1057 } else if (inst->isStore()) {
1058 DPRINTF(IEW, "[tid:%i]: Issue: Memory instruction "
1059 "encountered, adding to LSQ.\n", tid);
1060
1061 ldstQueue.insertStore(inst);
1062
1063 ++iewDispStoreInsts;
1064
1065 if (inst->isStoreConditional()) {
1066 // Store conditionals need to be set as "canCommit()"
1067 // so that commit can process them when they reach the
1068 // head of commit.
1069 // @todo: This is somewhat specific to Alpha.
1070 inst->setCanCommit();
1071 instQueue.insertNonSpec(inst);
1072 add_to_iq = false;
1073
1074 ++iewDispNonSpecInsts;
1075 } else {
1076 add_to_iq = true;
1077 }
1078
1079 toRename->iewInfo[tid].dispatchedToSQ++;
1080 } else if (inst->isMemBarrier() || inst->isWriteBarrier()) {
1081 // Same as non-speculative stores.
1082 inst->setCanCommit();
1083 instQueue.insertBarrier(inst);
1084 add_to_iq = false;
1085 } else if (inst->isNop()) {
1086 DPRINTF(IEW, "[tid:%i]: Issue: Nop instruction encountered, "
1087 "skipping.\n", tid);
1088
1089 inst->setIssued();
1090 inst->setExecuted();
1091 inst->setCanCommit();
1092
1093 instQueue.recordProducer(inst);
1094
1095 iewExecutedNop[tid]++;
1096
1097 add_to_iq = false;
1098 } else {
1099 assert(!inst->isExecuted());
1100 add_to_iq = true;
1101 }
1102
1103 if (inst->isNonSpeculative()) {
1104 DPRINTF(IEW, "[tid:%i]: Issue: Nonspeculative instruction "
1105 "encountered, skipping.\n", tid);
1106
1107 // Same as non-speculative stores.
1108 inst->setCanCommit();
1109
1110 // Specifically insert it as nonspeculative.
1111 instQueue.insertNonSpec(inst);
1112
1113 ++iewDispNonSpecInsts;
1114
1115 add_to_iq = false;
1116 }
1117
1118 // If the instruction queue is not full, then add the
1119 // instruction.
1120 if (add_to_iq) {
1121 instQueue.insert(inst);
1122 }
1123
1124 insts_to_dispatch.pop();
1125
1126 toRename->iewInfo[tid].dispatched++;
1127
1128 ++iewDispatchedInsts;
1129
1130#if TRACING_ON
1131 inst->dispatchTick = curTick() - inst->fetchTick;
1132#endif
1133 ppDispatch->notify(inst);
1134 }
1135
1136 if (!insts_to_dispatch.empty()) {
1137 DPRINTF(IEW,"[tid:%i]: Issue: Bandwidth Full. Blocking.\n", tid);
1138 block(tid);
1139 toRename->iewUnblock[tid] = false;
1140 }
1141
1142 if (dispatchStatus[tid] == Idle && dis_num_inst) {
1143 dispatchStatus[tid] = Running;
1144
1145 updatedQueues = true;
1146 }
1147
1148 dis_num_inst = 0;
1149}
1150
1151template <class Impl>
1152void
1153DefaultIEW<Impl>::printAvailableInsts()
1154{
1155 int inst = 0;
1156
1157 std::cout << "Available Instructions: ";
1158
1159 while (fromIssue->insts[inst]) {
1160
1161 if (inst%3==0) std::cout << "\n\t";
1162
1163 std::cout << "PC: " << fromIssue->insts[inst]->pcState()
1164 << " TN: " << fromIssue->insts[inst]->threadNumber
1165 << " SN: " << fromIssue->insts[inst]->seqNum << " | ";
1166
1167 inst++;
1168
1169 }
1170
1171 std::cout << "\n";
1172}
1173
1174template <class Impl>
1175void
1176DefaultIEW<Impl>::executeInsts()
1177{
1178 wbNumInst = 0;
1179 wbCycle = 0;
1180
1181 list<ThreadID>::iterator threads = activeThreads->begin();
1182 list<ThreadID>::iterator end = activeThreads->end();
1183
1184 while (threads != end) {
1185 ThreadID tid = *threads++;
1186 fetchRedirect[tid] = false;
1187 }
1188
1189 // Uncomment this if you want to see all available instructions.
1190 // @todo This doesn't actually work anymore, we should fix it.
1191// printAvailableInsts();
1192
1193 // Execute/writeback any instructions that are available.
1194 int insts_to_execute = fromIssue->size;
1195 int inst_num = 0;
1196 for (; inst_num < insts_to_execute;
1197 ++inst_num) {
1198
1199 DPRINTF(IEW, "Execute: Executing instructions from IQ.\n");
1200
1201 DynInstPtr inst = instQueue.getInstToExecute();
1202
1203 DPRINTF(IEW, "Execute: Processing PC %s, [tid:%i] [sn:%i].\n",
1204 inst->pcState(), inst->threadNumber,inst->seqNum);
1205
1206 // Notify potential listeners that this instruction has started
1207 // executing
1208 ppExecute->notify(inst);
1209
1210 // Check if the instruction is squashed; if so then skip it
1211 if (inst->isSquashed()) {
1212 DPRINTF(IEW, "Execute: Instruction was squashed. PC: %s, [tid:%i]"
1213 " [sn:%i]\n", inst->pcState(), inst->threadNumber,
1214 inst->seqNum);
1215
1216 // Consider this instruction executed so that commit can go
1217 // ahead and retire the instruction.
1218 inst->setExecuted();
1219
1220 // Not sure if I should set this here or just let commit try to
1221 // commit any squashed instructions. I like the latter a bit more.
1222 inst->setCanCommit();
1223
1224 ++iewExecSquashedInsts;
1225
1226 continue;
1227 }
1228
1229 Fault fault = NoFault;
1230
1231 // Execute instruction.
1232 // Note that if the instruction faults, it will be handled
1233 // at the commit stage.
1234 if (inst->isMemRef()) {
1235 DPRINTF(IEW, "Execute: Calculating address for memory "
1236 "reference.\n");
1237
1238 // Tell the LDSTQ to execute this instruction (if it is a load).
1239 if (inst->isLoad()) {
1240 // Loads will mark themselves as executed, and their writeback
1241 // event adds the instruction to the queue to commit
1242 fault = ldstQueue.executeLoad(inst);
1243
1244 if (inst->isTranslationDelayed() &&
1245 fault == NoFault) {
1246 // A hw page table walk is currently going on; the
1247 // instruction must be deferred.
1248 DPRINTF(IEW, "Execute: Delayed translation, deferring "
1249 "load.\n");
1250 instQueue.deferMemInst(inst);
1251 continue;
1252 }
1253
1254 if (inst->isDataPrefetch() || inst->isInstPrefetch()) {
1255 inst->fault = NoFault;
1256 }
1257 } else if (inst->isStore()) {
1258 fault = ldstQueue.executeStore(inst);
1259
1260 if (inst->isTranslationDelayed() &&
1261 fault == NoFault) {
1262 // A hw page table walk is currently going on; the
1263 // instruction must be deferred.
1264 DPRINTF(IEW, "Execute: Delayed translation, deferring "
1265 "store.\n");
1266 instQueue.deferMemInst(inst);
1267 continue;
1268 }
1269
1270 // If the store had a fault then it may not have a mem req
1271 if (fault != NoFault || !inst->readPredicate() ||
1272 !inst->isStoreConditional()) {
1273 // If the instruction faulted, then we need to send it along
1274 // to commit without the instruction completing.
1275 // Send this instruction to commit, also make sure iew stage
1276 // realizes there is activity.
1277 inst->setExecuted();
1278 instToCommit(inst);
1279 activityThisCycle();
1280 }
1281
1282 // Store conditionals will mark themselves as
1283 // executed, and their writeback event will add the
1284 // instruction to the queue to commit.
1285 } else {
1286 panic("Unexpected memory type!\n");
1287 }
1288
1289 } else {
1290 // If the instruction has already faulted, then skip executing it.
1291 // Such case can happen when it faulted during ITLB translation.
1292 // If we execute the instruction (even if it's a nop) the fault
1293 // will be replaced and we will lose it.
1294 if (inst->getFault() == NoFault) {
1295 inst->execute();
1296 if (!inst->readPredicate())
1297 inst->forwardOldRegs();
1298 }
1299
1300 inst->setExecuted();
1301
1302 instToCommit(inst);
1303 }
1304
1305 updateExeInstStats(inst);
1306
1307 // Check if branch prediction was correct, if not then we need
1308 // to tell commit to squash in flight instructions. Only
1309 // handle this if there hasn't already been something that
1310 // redirects fetch in this group of instructions.
1311
1312 // This probably needs to prioritize the redirects if a different
1313 // scheduler is used. Currently the scheduler schedules the oldest
1314 // instruction first, so the branch resolution order will be correct.
1315 ThreadID tid = inst->threadNumber;
1316
1317 if (!fetchRedirect[tid] ||
1318 !toCommit->squash[tid] ||
1319 toCommit->squashedSeqNum[tid] > inst->seqNum) {
1320
1321 // Prevent testing for misprediction on load instructions,
1322 // that have not been executed.
1323 bool loadNotExecuted = !inst->isExecuted() && inst->isLoad();
1324
1325 if (inst->mispredicted() && !loadNotExecuted) {
1326 fetchRedirect[tid] = true;
1327
1328 DPRINTF(IEW, "Execute: Branch mispredict detected.\n");
1329 DPRINTF(IEW, "Predicted target was PC: %s.\n",
1330 inst->readPredTarg());
1331 DPRINTF(IEW, "Execute: Redirecting fetch to PC: %s.\n",
1332 inst->pcState());
1333 // If incorrect, then signal the ROB that it must be squashed.
1334 squashDueToBranch(inst, tid);
1335
1336 ppMispredict->notify(inst);
1337
1338 if (inst->readPredTaken()) {
1339 predictedTakenIncorrect++;
1340 } else {
1341 predictedNotTakenIncorrect++;
1342 }
1343 } else if (ldstQueue.violation(tid)) {
1344 assert(inst->isMemRef());
1345 // If there was an ordering violation, then get the
1346 // DynInst that caused the violation. Note that this
1347 // clears the violation signal.
1348 DynInstPtr violator;
1349 violator = ldstQueue.getMemDepViolator(tid);
1350
1351 DPRINTF(IEW, "LDSTQ detected a violation. Violator PC: %s "
1352 "[sn:%lli], inst PC: %s [sn:%lli]. Addr is: %#x.\n",
1353 violator->pcState(), violator->seqNum,
1354 inst->pcState(), inst->seqNum, inst->physEffAddrLow);
1355
1356 fetchRedirect[tid] = true;
1357
1358 // Tell the instruction queue that a violation has occured.
1359 instQueue.violation(inst, violator);
1360
1361 // Squash.
1362 squashDueToMemOrder(violator, tid);
1363
1364 ++memOrderViolationEvents;
1365 }
1366 } else {
1367 // Reset any state associated with redirects that will not
1368 // be used.
1369 if (ldstQueue.violation(tid)) {
1370 assert(inst->isMemRef());
1371
1372 DynInstPtr violator = ldstQueue.getMemDepViolator(tid);
1373
1374 DPRINTF(IEW, "LDSTQ detected a violation. Violator PC: "
1375 "%s, inst PC: %s. Addr is: %#x.\n",
1376 violator->pcState(), inst->pcState(),
1377 inst->physEffAddrLow);
1378 DPRINTF(IEW, "Violation will not be handled because "
1379 "already squashing\n");
1380
1381 ++memOrderViolationEvents;
1382 }
1383 }
1384 }
1385
1386 // Update and record activity if we processed any instructions.
1387 if (inst_num) {
1388 if (exeStatus == Idle) {
1389 exeStatus = Running;
1390 }
1391
1392 updatedQueues = true;
1393
1394 cpu->activityThisCycle();
1395 }
1396
1397 // Need to reset this in case a writeback event needs to write into the
1398 // iew queue. That way the writeback event will write into the correct
1399 // spot in the queue.
1400 wbNumInst = 0;
1401
1402}
1403
1404template <class Impl>
1405void
1406DefaultIEW<Impl>::writebackInsts()
1407{
1408 // Loop through the head of the time buffer and wake any
1409 // dependents. These instructions are about to write back. Also
1410 // mark scoreboard that this instruction is finally complete.
1411 // Either have IEW have direct access to scoreboard, or have this
1412 // as part of backwards communication.
1413 for (int inst_num = 0; inst_num < wbWidth &&
1414 toCommit->insts[inst_num]; inst_num++) {
1415 DynInstPtr inst = toCommit->insts[inst_num];
1416 ThreadID tid = inst->threadNumber;
1417
1418 DPRINTF(IEW, "Sending instructions to commit, [sn:%lli] PC %s.\n",
1419 inst->seqNum, inst->pcState());
1420
1421 iewInstsToCommit[tid]++;
1422 // Notify potential listeners that execution is complete for this
1423 // instruction.
1424 ppToCommit->notify(inst);
1425
1426 // Some instructions will be sent to commit without having
1427 // executed because they need commit to handle them.
1428 // E.g. Strictly ordered loads have not actually executed when they
1429 // are first sent to commit. Instead commit must tell the LSQ
1430 // when it's ready to execute the strictly ordered load.
1431 if (!inst->isSquashed() && inst->isExecuted() && inst->getFault() == NoFault) {
1432 int dependents = instQueue.wakeDependents(inst);
1433
1434 for (int i = 0; i < inst->numDestRegs(); i++) {
1435 //mark as Ready
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