summaryrefslogtreecommitdiff
path: root/src/cpu/o3/rob_impl.hh
blob: d9d1daded20e287e846b40ae9a87ff4701d39d05 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
/*
 * Copyright (c) 2004-2006 The Regents of The University of Michigan
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: Kevin Lim
 *          Korey Sewell
 */

#include <list>

#include "config/full_system.hh"
#include "cpu/o3/rob.hh"

using namespace std;

template <class Impl>
ROB<Impl>::ROB(O3CPU *_cpu, unsigned _numEntries, unsigned _squashWidth,
               std::string _smtROBPolicy, unsigned _smtROBThreshold,
               ThreadID _numThreads)
    : cpu(_cpu),
      numEntries(_numEntries),
      squashWidth(_squashWidth),
      numInstsInROB(0),
      numThreads(_numThreads)
{
    for (ThreadID tid = 0; tid  < numThreads; tid++) {
        squashedSeqNum[tid] = 0;
        doneSquashing[tid] = true;
        threadEntries[tid] = 0;
    }

    std::string policy = _smtROBPolicy;

    //Convert string to lowercase
    std::transform(policy.begin(), policy.end(), policy.begin(),
                   (int(*)(int)) tolower);

    //Figure out rob policy
    if (policy == "dynamic") {
        robPolicy = Dynamic;

        //Set Max Entries to Total ROB Capacity
        for (ThreadID tid = 0; tid < numThreads; tid++) {
            maxEntries[tid] = numEntries;
        }

    } else if (policy == "partitioned") {
        robPolicy = Partitioned;
        DPRINTF(Fetch, "ROB sharing policy set to Partitioned\n");

        //@todo:make work if part_amt doesnt divide evenly.
        int part_amt = numEntries / numThreads;

        //Divide ROB up evenly
        for (ThreadID tid = 0; tid < numThreads; tid++) {
            maxEntries[tid] = part_amt;
        }

    } else if (policy == "threshold") {
        robPolicy = Threshold;
        DPRINTF(Fetch, "ROB sharing policy set to Threshold\n");

        int threshold =  _smtROBThreshold;;

        //Divide up by threshold amount
        for (ThreadID tid = 0; tid < numThreads; tid++) {
            maxEntries[tid] = threshold;
        }
    } else {
        assert(0 && "Invalid ROB Sharing Policy.Options Are:{Dynamic,"
                    "Partitioned, Threshold}");
    }

    // Set the per-thread iterators to the end of the instruction list.
    for (ThreadID tid = 0; tid < numThreads; tid++) {
        squashIt[tid] = instList[tid].end();
    }

    // Initialize the "universal" ROB head & tail point to invalid
    // pointers
    head = instList[0].end();
    tail = instList[0].end();
}

template <class Impl>
std::string
ROB<Impl>::name() const
{
    return cpu->name() + ".rob";
}

template <class Impl>
void
ROB<Impl>::setActiveThreads(list<ThreadID> *at_ptr)
{
    DPRINTF(ROB, "Setting active threads list pointer.\n");
    activeThreads = at_ptr;
}

template <class Impl>
void
ROB<Impl>::switchOut()
{
    for (ThreadID tid = 0; tid < numThreads; tid++) {
        instList[tid].clear();
    }
}

template <class Impl>
void
ROB<Impl>::takeOverFrom()
{
    for (ThreadID tid = 0; tid  < numThreads; tid++) {
        doneSquashing[tid] = true;
        threadEntries[tid] = 0;
        squashIt[tid] = instList[tid].end();
    }
    numInstsInROB = 0;

    // Initialize the "universal" ROB head & tail point to invalid
    // pointers
    head = instList[0].end();
    tail = instList[0].end();
}

template <class Impl>
void
ROB<Impl>::resetEntries()
{
    if (robPolicy != Dynamic || numThreads > 1) {
        int active_threads = activeThreads->size();

        list<ThreadID>::iterator threads = activeThreads->begin();
        list<ThreadID>::iterator end = activeThreads->end();

        while (threads != end) {
            ThreadID tid = *threads++;

            if (robPolicy == Partitioned) {
                maxEntries[tid] = numEntries / active_threads;
            } else if (robPolicy == Threshold && active_threads == 1) {
                maxEntries[tid] = numEntries;
            }
        }
    }
}

template <class Impl>
int
ROB<Impl>::entryAmount(ThreadID num_threads)
{
    if (robPolicy == Partitioned) {
        return numEntries / num_threads;
    } else {
        return 0;
    }
}

template <class Impl>
int
ROB<Impl>::countInsts()
{
    int total = 0;

    for (ThreadID tid = 0; tid < numThreads; tid++)
        total += countInsts(tid);

    return total;
}

template <class Impl>
int
ROB<Impl>::countInsts(ThreadID tid)
{
    return instList[tid].size();
}

template <class Impl>
void
ROB<Impl>::insertInst(DynInstPtr &inst)
{
    assert(inst);

    robWrites++;

    DPRINTF(ROB, "Adding inst PC %s to the ROB.\n", inst->pcState());

    assert(numInstsInROB != numEntries);

    ThreadID tid = inst->threadNumber;

    instList[tid].push_back(inst);

    //Set Up head iterator if this is the 1st instruction in the ROB
    if (numInstsInROB == 0) {
        head = instList[tid].begin();
        assert((*head) == inst);
    }

    //Must Decrement for iterator to actually be valid  since __.end()
    //actually points to 1 after the last inst
    tail = instList[tid].end();
    tail--;

    inst->setInROB();

    ++numInstsInROB;
    ++threadEntries[tid];

    assert((*tail) == inst);

    DPRINTF(ROB, "[tid:%i] Now has %d instructions.\n", tid, threadEntries[tid]);
}

template <class Impl>
void
ROB<Impl>::retireHead(ThreadID tid)
{
    robWrites++;

    assert(numInstsInROB > 0);

    // Get the head ROB instruction.
    InstIt head_it = instList[tid].begin();

    DynInstPtr head_inst = (*head_it);

    assert(head_inst->readyToCommit());

    DPRINTF(ROB, "[tid:%u]: Retiring head instruction, "
            "instruction PC %s, [sn:%lli]\n", tid, head_inst->pcState(),
            head_inst->seqNum);

    --numInstsInROB;
    --threadEntries[tid];

    head_inst->clearInROB();
    head_inst->setCommitted();

    instList[tid].erase(head_it);

    //Update "Global" Head of ROB
    updateHead();

    // @todo: A special case is needed if the instruction being
    // retired is the only instruction in the ROB; otherwise the tail
    // iterator will become invalidated.
    cpu->removeFrontInst(head_inst);
}

template <class Impl>
bool
ROB<Impl>::isHeadReady(ThreadID tid)
{
    robReads++;
    if (threadEntries[tid] != 0) {
        return instList[tid].front()->readyToCommit();
    }

    return false;
}

template <class Impl>
bool
ROB<Impl>::canCommit()
{
    //@todo: set ActiveThreads through ROB or CPU
    list<ThreadID>::iterator threads = activeThreads->begin();
    list<ThreadID>::iterator end = activeThreads->end();

    while (threads != end) {
        ThreadID tid = *threads++;

        if (isHeadReady(tid)) {
            return true;
        }
    }

    return false;
}

template <class Impl>
unsigned
ROB<Impl>::numFreeEntries()
{
    return numEntries - numInstsInROB;
}

template <class Impl>
unsigned
ROB<Impl>::numFreeEntries(ThreadID tid)
{
    return maxEntries[tid] - threadEntries[tid];
}

template <class Impl>
void
ROB<Impl>::doSquash(ThreadID tid)
{
    robWrites++;
    DPRINTF(ROB, "[tid:%u]: Squashing instructions until [sn:%i].\n",
            tid, squashedSeqNum[tid]);

    assert(squashIt[tid] != instList[tid].end());

    if ((*squashIt[tid])->seqNum < squashedSeqNum[tid]) {
        DPRINTF(ROB, "[tid:%u]: Done squashing instructions.\n",
                tid);

        squashIt[tid] = instList[tid].end();

        doneSquashing[tid] = true;
        return;
    }

    bool robTailUpdate = false;

    for (int numSquashed = 0;
         numSquashed < squashWidth &&
         squashIt[tid] != instList[tid].end() &&
         (*squashIt[tid])->seqNum > squashedSeqNum[tid];
         ++numSquashed)
    {
        DPRINTF(ROB, "[tid:%u]: Squashing instruction PC %s, seq num %i.\n",
                (*squashIt[tid])->threadNumber,
                (*squashIt[tid])->pcState(),
                (*squashIt[tid])->seqNum);

        // Mark the instruction as squashed, and ready to commit so that
        // it can drain out of the pipeline.
        (*squashIt[tid])->setSquashed();

        (*squashIt[tid])->setCanCommit();


        if (squashIt[tid] == instList[tid].begin()) {
            DPRINTF(ROB, "Reached head of instruction list while "
                    "squashing.\n");

            squashIt[tid] = instList[tid].end();

            doneSquashing[tid] = true;

            return;
        }

        InstIt tail_thread = instList[tid].end();
        tail_thread--;

        if ((*squashIt[tid]) == (*tail_thread))
            robTailUpdate = true;

        squashIt[tid]--;
    }


    // Check if ROB is done squashing.
    if ((*squashIt[tid])->seqNum <= squashedSeqNum[tid]) {
        DPRINTF(ROB, "[tid:%u]: Done squashing instructions.\n",
                tid);

        squashIt[tid] = instList[tid].end();

        doneSquashing[tid] = true;
    }

    if (robTailUpdate) {
        updateTail();
    }
}


template <class Impl>
void
ROB<Impl>::updateHead()
{
    DynInstPtr head_inst;
    InstSeqNum lowest_num = 0;
    bool first_valid = true;

    // @todo: set ActiveThreads through ROB or CPU
    list<ThreadID>::iterator threads = activeThreads->begin();
    list<ThreadID>::iterator end = activeThreads->end();

    while (threads != end) {
        ThreadID tid = *threads++;

        if (instList[tid].empty())
            continue;

        if (first_valid) {
            head = instList[tid].begin();
            lowest_num = (*head)->seqNum;
            first_valid = false;
            continue;
        }

        InstIt head_thread = instList[tid].begin();

        DynInstPtr head_inst = (*head_thread);

        assert(head_inst != 0);

        if (head_inst->seqNum < lowest_num) {
            head = head_thread;
            lowest_num = head_inst->seqNum;
        }
    }

    if (first_valid) {
        head = instList[0].end();
    }

}

template <class Impl>
void
ROB<Impl>::updateTail()
{
    tail = instList[0].end();
    bool first_valid = true;

    list<ThreadID>::iterator threads = activeThreads->begin();
    list<ThreadID>::iterator end = activeThreads->end();

    while (threads != end) {
        ThreadID tid = *threads++;

        if (instList[tid].empty()) {
            continue;
        }

        // If this is the first valid then assign w/out
        // comparison
        if (first_valid) {
            tail = instList[tid].end();
            tail--;
            first_valid = false;
            continue;
        }

        // Assign new tail if this thread's tail is younger
        // than our current "tail high"
        InstIt tail_thread = instList[tid].end();
        tail_thread--;

        if ((*tail_thread)->seqNum > (*tail)->seqNum) {
            tail = tail_thread;
        }
    }
}


template <class Impl>
void
ROB<Impl>::squash(InstSeqNum squash_num, ThreadID tid)
{
    if (isEmpty()) {
        DPRINTF(ROB, "Does not need to squash due to being empty "
                "[sn:%i]\n",
                squash_num);

        return;
    }

    DPRINTF(ROB, "Starting to squash within the ROB.\n");

    robStatus[tid] = ROBSquashing;

    doneSquashing[tid] = false;

    squashedSeqNum[tid] = squash_num;

    if (!instList[tid].empty()) {
        InstIt tail_thread = instList[tid].end();
        tail_thread--;

        squashIt[tid] = tail_thread;

        doSquash(tid);
    }
}

template <class Impl>
typename Impl::DynInstPtr
ROB<Impl>::readHeadInst(ThreadID tid)
{
    if (threadEntries[tid] != 0) {
        InstIt head_thread = instList[tid].begin();

        assert((*head_thread)->isInROB()==true);

        return *head_thread;
    } else {
        return dummyInst;
    }
}

template <class Impl>
typename Impl::DynInstPtr
ROB<Impl>::readTailInst(ThreadID tid)
{
    InstIt tail_thread = instList[tid].end();
    tail_thread--;

    return *tail_thread;
}

template <class Impl>
void
ROB<Impl>::regStats()
{
    using namespace Stats;
    robReads
        .name(name() + ".rob_reads")
        .desc("The number of ROB reads");

    robWrites
        .name(name() + ".rob_writes")
        .desc("The number of ROB writes");
}