1/*
2 * Copyright (c) 2012 ARM Limited
3 * All rights reserved
4 *
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder. You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Copyright (c) 2004-2006 The Regents of The University of Michigan
15 * All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions are
19 * met: redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer;
21 * redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution;
24 * neither the name of the copyright holders nor the names of its
25 * contributors may be used to endorse or promote products derived from
26 * this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 *
40 * Authors: Kevin Lim
41 * Korey Sewell
42 */
43
44#include <list>
45
46#include "cpu/o3/rob.hh"
47#include "debug/Fetch.hh"
48#include "debug/ROB.hh"
49
50using namespace std;
51
52template <class Impl>
53ROB<Impl>::ROB(O3CPU *_cpu, unsigned _numEntries, unsigned _squashWidth,
54 std::string _smtROBPolicy, unsigned _smtROBThreshold,
55 ThreadID _numThreads)
56 : cpu(_cpu),
57 numEntries(_numEntries),
58 squashWidth(_squashWidth),
59 numInstsInROB(0),
60 numThreads(_numThreads)
61{
62 std::string policy = _smtROBPolicy;
63
64 //Convert string to lowercase
65 std::transform(policy.begin(), policy.end(), policy.begin(),
66 (int(*)(int)) tolower);
67
68 //Figure out rob policy
69 if (policy == "dynamic") {
70 robPolicy = Dynamic;
71
72 //Set Max Entries to Total ROB Capacity
73 for (ThreadID tid = 0; tid < numThreads; tid++) {
74 maxEntries[tid] = numEntries;
75 }
76
77 } else if (policy == "partitioned") {
78 robPolicy = Partitioned;
79 DPRINTF(Fetch, "ROB sharing policy set to Partitioned\n");
80
81 //@todo:make work if part_amt doesnt divide evenly.
82 int part_amt = numEntries / numThreads;
83
84 //Divide ROB up evenly
85 for (ThreadID tid = 0; tid < numThreads; tid++) {
86 maxEntries[tid] = part_amt;
87 }
88
89 } else if (policy == "threshold") {
90 robPolicy = Threshold;
91 DPRINTF(Fetch, "ROB sharing policy set to Threshold\n");
92
93 int threshold = _smtROBThreshold;;
94
95 //Divide up by threshold amount
96 for (ThreadID tid = 0; tid < numThreads; tid++) {
97 maxEntries[tid] = threshold;
98 }
99 } else {
100 assert(0 && "Invalid ROB Sharing Policy.Options Are:{Dynamic,"
101 "Partitioned, Threshold}");
102 }
103
104 resetState();
105}
106
107template <class Impl>
108void
109ROB<Impl>::resetState()
110{
111 for (ThreadID tid = 0; tid < numThreads; tid++) {
112 doneSquashing[tid] = true;
113 threadEntries[tid] = 0;
114 squashIt[tid] = instList[tid].end();
115 squashedSeqNum[tid] = 0;
116 }
117 numInstsInROB = 0;
118
119 // Initialize the "universal" ROB head & tail point to invalid
120 // pointers
121 head = instList[0].end();
122 tail = instList[0].end();
123}
124
125template <class Impl>
126std::string
127ROB<Impl>::name() const
128{
129 return cpu->name() + ".rob";
130}
131
132template <class Impl>
133void
134ROB<Impl>::setActiveThreads(list<ThreadID> *at_ptr)
135{
136 DPRINTF(ROB, "Setting active threads list pointer.\n");
137 activeThreads = at_ptr;
138}
139
140template <class Impl>
141void
142ROB<Impl>::drainSanityCheck() const
143{
144 for (ThreadID tid = 0; tid < numThreads; tid++)
145 assert(instList[tid].empty());
146 assert(isEmpty());
147}
148
149template <class Impl>
150void
151ROB<Impl>::takeOverFrom()
152{
153 resetState();
154}
155
156template <class Impl>
157void
158ROB<Impl>::resetEntries()
159{
160 if (robPolicy != Dynamic || numThreads > 1) {
161 int active_threads = activeThreads->size();
162
163 list<ThreadID>::iterator threads = activeThreads->begin();
164 list<ThreadID>::iterator end = activeThreads->end();
165
166 while (threads != end) {
167 ThreadID tid = *threads++;
168
169 if (robPolicy == Partitioned) {
170 maxEntries[tid] = numEntries / active_threads;
171 } else if (robPolicy == Threshold && active_threads == 1) {
172 maxEntries[tid] = numEntries;
173 }
174 }
175 }
176}
177
178template <class Impl>
179int
180ROB<Impl>::entryAmount(ThreadID num_threads)
181{
182 if (robPolicy == Partitioned) {
183 return numEntries / num_threads;
184 } else {
185 return 0;
186 }
187}
188
189template <class Impl>
190int
191ROB<Impl>::countInsts()
192{
193 int total = 0;
194
195 for (ThreadID tid = 0; tid < numThreads; tid++)
196 total += countInsts(tid);
197
198 return total;
199}
200
201template <class Impl>
202int
203ROB<Impl>::countInsts(ThreadID tid)
204{
205 return instList[tid].size();
206}
207
208template <class Impl>
209void
210ROB<Impl>::insertInst(DynInstPtr &inst)
211{
212 assert(inst);
213
214 robWrites++;
215
216 DPRINTF(ROB, "Adding inst PC %s to the ROB.\n", inst->pcState());
217
218 assert(numInstsInROB != numEntries);
219
220 ThreadID tid = inst->threadNumber;
221
222 instList[tid].push_back(inst);
223
224 //Set Up head iterator if this is the 1st instruction in the ROB
225 if (numInstsInROB == 0) {
226 head = instList[tid].begin();
227 assert((*head) == inst);
228 }
229
230 //Must Decrement for iterator to actually be valid since __.end()
231 //actually points to 1 after the last inst
232 tail = instList[tid].end();
233 tail--;
234
235 inst->setInROB();
236
237 ++numInstsInROB;
238 ++threadEntries[tid];
239
240 assert((*tail) == inst);
241
242 DPRINTF(ROB, "[tid:%i] Now has %d instructions.\n", tid, threadEntries[tid]);
243}
244
245template <class Impl>
246void
247ROB<Impl>::retireHead(ThreadID tid)
248{
249 robWrites++;
250
251 assert(numInstsInROB > 0);
252
253 // Get the head ROB instruction.
254 InstIt head_it = instList[tid].begin();
255
256 DynInstPtr head_inst = (*head_it);
257
258 assert(head_inst->readyToCommit());
259
260 DPRINTF(ROB, "[tid:%u]: Retiring head instruction, "
261 "instruction PC %s, [sn:%lli]\n", tid, head_inst->pcState(),
262 head_inst->seqNum);
263
264 --numInstsInROB;
265 --threadEntries[tid];
266
267 head_inst->clearInROB();
268 head_inst->setCommitted();
269
270 instList[tid].erase(head_it);
271
272 //Update "Global" Head of ROB
273 updateHead();
274
275 // @todo: A special case is needed if the instruction being
276 // retired is the only instruction in the ROB; otherwise the tail
277 // iterator will become invalidated.
278 cpu->removeFrontInst(head_inst);
279}
280
281template <class Impl>
282bool
283ROB<Impl>::isHeadReady(ThreadID tid)
284{
285 robReads++;
286 if (threadEntries[tid] != 0) {
287 return instList[tid].front()->readyToCommit();
288 }
289
290 return false;
291}
292
293template <class Impl>
294bool
295ROB<Impl>::canCommit()
296{
297 //@todo: set ActiveThreads through ROB or CPU
298 list<ThreadID>::iterator threads = activeThreads->begin();
299 list<ThreadID>::iterator end = activeThreads->end();
300
301 while (threads != end) {
302 ThreadID tid = *threads++;
303
304 if (isHeadReady(tid)) {
305 return true;
306 }
307 }
308
309 return false;
310}
311
312template <class Impl>
313unsigned
314ROB<Impl>::numFreeEntries()
315{
316 return numEntries - numInstsInROB;
317}
318
319template <class Impl>
320unsigned
321ROB<Impl>::numFreeEntries(ThreadID tid)
322{
323 return maxEntries[tid] - threadEntries[tid];
324}
325
326template <class Impl>
327void
328ROB<Impl>::doSquash(ThreadID tid)
329{
330 robWrites++;
331 DPRINTF(ROB, "[tid:%u]: Squashing instructions until [sn:%i].\n",
332 tid, squashedSeqNum[tid]);
333
334 assert(squashIt[tid] != instList[tid].end());
335
336 if ((*squashIt[tid])->seqNum < squashedSeqNum[tid]) {
337 DPRINTF(ROB, "[tid:%u]: Done squashing instructions.\n",
338 tid);
339
340 squashIt[tid] = instList[tid].end();
341
342 doneSquashing[tid] = true;
343 return;
344 }
345
346 bool robTailUpdate = false;
347
348 for (int numSquashed = 0;
349 numSquashed < squashWidth &&
350 squashIt[tid] != instList[tid].end() &&
351 (*squashIt[tid])->seqNum > squashedSeqNum[tid];
352 ++numSquashed)
353 {
354 DPRINTF(ROB, "[tid:%u]: Squashing instruction PC %s, seq num %i.\n",
355 (*squashIt[tid])->threadNumber,
356 (*squashIt[tid])->pcState(),
357 (*squashIt[tid])->seqNum);
358
359 // Mark the instruction as squashed, and ready to commit so that
360 // it can drain out of the pipeline.
361 (*squashIt[tid])->setSquashed();
362
363 (*squashIt[tid])->setCanCommit();
364
365
366 if (squashIt[tid] == instList[tid].begin()) {
367 DPRINTF(ROB, "Reached head of instruction list while "
368 "squashing.\n");
369
370 squashIt[tid] = instList[tid].end();
371
372 doneSquashing[tid] = true;
373
374 return;
375 }
376
377 InstIt tail_thread = instList[tid].end();
378 tail_thread--;
379
380 if ((*squashIt[tid]) == (*tail_thread))
381 robTailUpdate = true;
382
383 squashIt[tid]--;
384 }
385
386
387 // Check if ROB is done squashing.
388 if ((*squashIt[tid])->seqNum <= squashedSeqNum[tid]) {
389 DPRINTF(ROB, "[tid:%u]: Done squashing instructions.\n",
390 tid);
391
392 squashIt[tid] = instList[tid].end();
393
394 doneSquashing[tid] = true;
395 }
396
397 if (robTailUpdate) {
398 updateTail();
399 }
400}
401
402
403template <class Impl>
404void
405ROB<Impl>::updateHead()
406{
407 InstSeqNum lowest_num = 0;
408 bool first_valid = true;
409
410 // @todo: set ActiveThreads through ROB or CPU
411 list<ThreadID>::iterator threads = activeThreads->begin();
412 list<ThreadID>::iterator end = activeThreads->end();
413
414 while (threads != end) {
415 ThreadID tid = *threads++;
416
417 if (instList[tid].empty())
418 continue;
419
420 if (first_valid) {
421 head = instList[tid].begin();
422 lowest_num = (*head)->seqNum;
423 first_valid = false;
424 continue;
425 }
426
427 InstIt head_thread = instList[tid].begin();
428
429 DynInstPtr head_inst = (*head_thread);
430
431 assert(head_inst != 0);
432
433 if (head_inst->seqNum < lowest_num) {
434 head = head_thread;
435 lowest_num = head_inst->seqNum;
436 }
437 }
438
439 if (first_valid) {
440 head = instList[0].end();
441 }
442
443}
444
445template <class Impl>
446void
447ROB<Impl>::updateTail()
448{
449 tail = instList[0].end();
450 bool first_valid = true;
451
452 list<ThreadID>::iterator threads = activeThreads->begin();
453 list<ThreadID>::iterator end = activeThreads->end();
454
455 while (threads != end) {
456 ThreadID tid = *threads++;
457
458 if (instList[tid].empty()) {
459 continue;
460 }
461
462 // If this is the first valid then assign w/out
463 // comparison
464 if (first_valid) {
465 tail = instList[tid].end();
466 tail--;
467 first_valid = false;
468 continue;
469 }
470
471 // Assign new tail if this thread's tail is younger
472 // than our current "tail high"
473 InstIt tail_thread = instList[tid].end();
474 tail_thread--;
475
476 if ((*tail_thread)->seqNum > (*tail)->seqNum) {
477 tail = tail_thread;
478 }
479 }
480}
481
482
483template <class Impl>
484void
485ROB<Impl>::squash(InstSeqNum squash_num, ThreadID tid)
486{
487 if (isEmpty()) {
488 DPRINTF(ROB, "Does not need to squash due to being empty "
489 "[sn:%i]\n",
490 squash_num);
491
492 return;
493 }
494
495 DPRINTF(ROB, "Starting to squash within the ROB.\n");
496
497 robStatus[tid] = ROBSquashing;
498
499 doneSquashing[tid] = false;
500
501 squashedSeqNum[tid] = squash_num;
502
503 if (!instList[tid].empty()) {
504 InstIt tail_thread = instList[tid].end();
505 tail_thread--;
506
507 squashIt[tid] = tail_thread;
508
509 doSquash(tid);
510 }
511}
512
513template <class Impl>
514typename Impl::DynInstPtr
515ROB<Impl>::readHeadInst(ThreadID tid)
516{
517 if (threadEntries[tid] != 0) {
518 InstIt head_thread = instList[tid].begin();
519
520 assert((*head_thread)->isInROB()==true);
521
522 return *head_thread;
523 } else {
524 return dummyInst;
525 }
526}
527
528template <class Impl>
529typename Impl::DynInstPtr
530ROB<Impl>::readTailInst(ThreadID tid)
531{
532 InstIt tail_thread = instList[tid].end();
533 tail_thread--;
534
535 return *tail_thread;
536}
537
538template <class Impl>
539void
540ROB<Impl>::regStats()
541{
542 using namespace Stats;
543 robReads
544 .name(name() + ".rob_reads")
545 .desc("The number of ROB reads");
546
547 robWrites
548 .name(name() + ".rob_writes")
549 .desc("The number of ROB writes");
550}
551
552template <class Impl>
553typename Impl::DynInstPtr
554ROB<Impl>::findInst(ThreadID tid, InstSeqNum squash_inst)
555{
556 for (InstIt it = instList[tid].begin(); it != instList[tid].end(); it++) {
557 if ((*it)->seqNum == squash_inst) {
558 return *it;
559 }
560 }
561 return NULL;
562}