summaryrefslogtreecommitdiff
path: root/src/cpu/o3/mem_dep_unit_impl.hh
blob: c649ca3855eeaceec58817bbe8d153e0d91cfaec (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
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
/*
 * 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
 */

#include <map>

#include "cpu/o3/inst_queue.hh"
#include "cpu/o3/mem_dep_unit.hh"

template <class MemDepPred, class Impl>
MemDepUnit<MemDepPred, Impl>::MemDepUnit(Params *params)
    : depPred(params->SSITSize, params->LFSTSize), loadBarrier(false),
      loadBarrierSN(0), storeBarrier(false), storeBarrierSN(0), iqPtr(NULL)
{
    DPRINTF(MemDepUnit, "Creating MemDepUnit object.\n");
}

template <class MemDepPred, class Impl>
MemDepUnit<MemDepPred, Impl>::~MemDepUnit()
{
    for (int tid=0; tid < Impl::MaxThreads; tid++) {

        ListIt inst_list_it = instList[tid].begin();

        MemDepHashIt hash_it;

        while (!instList[tid].empty()) {
            hash_it = memDepHash.find((*inst_list_it)->seqNum);

            assert(hash_it != memDepHash.end());

            memDepHash.erase(hash_it);

            instList[tid].erase(inst_list_it++);
        }
    }

#ifdef DEBUG
    assert(MemDepEntry::memdep_count == 0);
#endif
}

template <class MemDepPred, class Impl>
std::string
MemDepUnit<MemDepPred, Impl>::name() const
{
    return "memdepunit";
}

template <class MemDepPred, class Impl>
void
MemDepUnit<MemDepPred, Impl>::init(Params *params, int tid)
{
    DPRINTF(MemDepUnit, "Creating MemDepUnit %i object.\n",tid);

    id = tid;

    depPred.init(params->SSITSize, params->LFSTSize);
}

template <class MemDepPred, class Impl>
void
MemDepUnit<MemDepPred, Impl>::regStats()
{
    insertedLoads
        .name(name() + ".memDep.insertedLoads")
        .desc("Number of loads inserted to the mem dependence unit.");

    insertedStores
        .name(name() + ".memDep.insertedStores")
        .desc("Number of stores inserted to the mem dependence unit.");

    conflictingLoads
        .name(name() + ".memDep.conflictingLoads")
        .desc("Number of conflicting loads.");

    conflictingStores
        .name(name() + ".memDep.conflictingStores")
        .desc("Number of conflicting stores.");
}

template <class MemDepPred, class Impl>
void
MemDepUnit<MemDepPred, Impl>::switchOut()
{
    assert(instList[0].empty());
    assert(instsToReplay.empty());
    assert(memDepHash.empty());
    // Clear any state.
    for (int i = 0; i < Impl::MaxThreads; ++i) {
        instList[i].clear();
    }
    instsToReplay.clear();
    memDepHash.clear();
}

template <class MemDepPred, class Impl>
void
MemDepUnit<MemDepPred, Impl>::takeOverFrom()
{
    // Be sure to reset all state.
    loadBarrier = storeBarrier = false;
    loadBarrierSN = storeBarrierSN = 0;
    depPred.clear();
}

template <class MemDepPred, class Impl>
void
MemDepUnit<MemDepPred, Impl>::setIQ(InstructionQueue<Impl> *iq_ptr)
{
    iqPtr = iq_ptr;
}

template <class MemDepPred, class Impl>
void
MemDepUnit<MemDepPred, Impl>::insert(DynInstPtr &inst)
{
    unsigned tid = inst->threadNumber;

    MemDepEntryPtr inst_entry = new MemDepEntry(inst);

    // Add the MemDepEntry to the hash.
    memDepHash.insert(
        std::pair<InstSeqNum, MemDepEntryPtr>(inst->seqNum, inst_entry));
#ifdef DEBUG
    MemDepEntry::memdep_insert++;
#endif

    instList[tid].push_back(inst);

    inst_entry->listIt = --(instList[tid].end());

    // Check any barriers and the dependence predictor for any
    // producing memrefs/stores.
    InstSeqNum producing_store;
    if (inst->isLoad() && loadBarrier) {
        producing_store = loadBarrierSN;
    } else if (inst->isStore() && storeBarrier) {
        producing_store = storeBarrierSN;
    } else {
        producing_store = depPred.checkInst(inst->readPC());
    }

    MemDepEntryPtr store_entry = NULL;

    // If there is a producing store, try to find the entry.
    if (producing_store != 0) {
        MemDepHashIt hash_it = memDepHash.find(producing_store);

        if (hash_it != memDepHash.end()) {
            store_entry = (*hash_it).second;
        }
    }

    // If no store entry, then instruction can issue as soon as the registers
    // are ready.
    if (!store_entry) {
        DPRINTF(MemDepUnit, "No dependency for inst PC "
                "%#x [sn:%lli].\n", inst->readPC(), inst->seqNum);

        inst_entry->memDepReady = true;

        if (inst->readyToIssue()) {
            inst_entry->regsReady = true;

            moveToReady(inst_entry);
        }
    } else {
        // Otherwise make the instruction dependent on the store/barrier.
        DPRINTF(MemDepUnit, "Adding to dependency list; "
                "inst PC %#x is dependent on [sn:%lli].\n",
                inst->readPC(), producing_store);

        if (inst->readyToIssue()) {
            inst_entry->regsReady = true;
        }

        // Add this instruction to the list of dependents.
        store_entry->dependInsts.push_back(inst_entry);

        if (inst->isLoad()) {
            ++conflictingLoads;
        } else {
            ++conflictingStores;
        }
    }

    if (inst->isStore()) {
        DPRINTF(MemDepUnit, "Inserting store PC %#x [sn:%lli].\n",
                inst->readPC(), inst->seqNum);

        depPred.insertStore(inst->readPC(), inst->seqNum, inst->threadNumber);

        ++insertedStores;
    } else if (inst->isLoad()) {
        ++insertedLoads;
    } else {
        panic("Unknown type! (most likely a barrier).");
    }
}

template <class MemDepPred, class Impl>
void
MemDepUnit<MemDepPred, Impl>::insertNonSpec(DynInstPtr &inst)
{
    unsigned tid = inst->threadNumber;

    MemDepEntryPtr inst_entry = new MemDepEntry(inst);

    // Insert the MemDepEntry into the hash.
    memDepHash.insert(
        std::pair<InstSeqNum, MemDepEntryPtr>(inst->seqNum, inst_entry));
#ifdef DEBUG
    MemDepEntry::memdep_insert++;
#endif

    // Add the instruction to the list.
    instList[tid].push_back(inst);

    inst_entry->listIt = --(instList[tid].end());

    // Might want to turn this part into an inline function or something.
    // It's shared between both insert functions.
    if (inst->isStore()) {
        DPRINTF(MemDepUnit, "Inserting store PC %#x [sn:%lli].\n",
                inst->readPC(), inst->seqNum);

        depPred.insertStore(inst->readPC(), inst->seqNum, inst->threadNumber);

        ++insertedStores;
    } else if (inst->isLoad()) {
        ++insertedLoads;
    } else {
        panic("Unknown type! (most likely a barrier).");
    }
}

template <class MemDepPred, class Impl>
void
MemDepUnit<MemDepPred, Impl>::insertBarrier(DynInstPtr &barr_inst)
{
    InstSeqNum barr_sn = barr_inst->seqNum;
    // Memory barriers block loads and stores, write barriers only stores.
    if (barr_inst->isMemBarrier()) {
        loadBarrier = true;
        loadBarrierSN = barr_sn;
        storeBarrier = true;
        storeBarrierSN = barr_sn;
        DPRINTF(MemDepUnit, "Inserted a memory barrier\n");
    } else if (barr_inst->isWriteBarrier()) {
        storeBarrier = true;
        storeBarrierSN = barr_sn;
        DPRINTF(MemDepUnit, "Inserted a write barrier\n");
    }

    unsigned tid = barr_inst->threadNumber;

    MemDepEntryPtr inst_entry = new MemDepEntry(barr_inst);

    // Add the MemDepEntry to the hash.
    memDepHash.insert(
        std::pair<InstSeqNum, MemDepEntryPtr>(barr_sn, inst_entry));
#ifdef DEBUG
    MemDepEntry::memdep_insert++;
#endif

    // Add the instruction to the instruction list.
    instList[tid].push_back(barr_inst);

    inst_entry->listIt = --(instList[tid].end());
}

template <class MemDepPred, class Impl>
void
MemDepUnit<MemDepPred, Impl>::regsReady(DynInstPtr &inst)
{
    DPRINTF(MemDepUnit, "Marking registers as ready for "
            "instruction PC %#x [sn:%lli].\n",
            inst->readPC(), inst->seqNum);

    MemDepEntryPtr inst_entry = findInHash(inst);

    inst_entry->regsReady = true;

    if (inst_entry->memDepReady) {
        DPRINTF(MemDepUnit, "Instruction has its memory "
                "dependencies resolved, adding it to the ready list.\n");

        moveToReady(inst_entry);
    } else {
        DPRINTF(MemDepUnit, "Instruction still waiting on "
                "memory dependency.\n");
    }
}

template <class MemDepPred, class Impl>
void
MemDepUnit<MemDepPred, Impl>::nonSpecInstReady(DynInstPtr &inst)
{
    DPRINTF(MemDepUnit, "Marking non speculative "
            "instruction PC %#x as ready [sn:%lli].\n",
            inst->readPC(), inst->seqNum);

    MemDepEntryPtr inst_entry = findInHash(inst);

    moveToReady(inst_entry);
}

template <class MemDepPred, class Impl>
void
MemDepUnit<MemDepPred, Impl>::reschedule(DynInstPtr &inst)
{
    instsToReplay.push_back(inst);
}

template <class MemDepPred, class Impl>
void
MemDepUnit<MemDepPred, Impl>::replay(DynInstPtr &inst)
{
    DynInstPtr temp_inst;
    bool found_inst = false;

    // For now this replay function replays all waiting memory ops.
    while (!instsToReplay.empty()) {
        temp_inst = instsToReplay.front();

        MemDepEntryPtr inst_entry = findInHash(temp_inst);

        DPRINTF(MemDepUnit, "Replaying mem instruction PC %#x "
                "[sn:%lli].\n",
                temp_inst->readPC(), temp_inst->seqNum);

        moveToReady(inst_entry);

        if (temp_inst == inst) {
            found_inst = true;
        }

        instsToReplay.pop_front();
    }

    assert(found_inst);
}

template <class MemDepPred, class Impl>
void
MemDepUnit<MemDepPred, Impl>::completed(DynInstPtr &inst)
{
    DPRINTF(MemDepUnit, "Completed mem instruction PC %#x "
            "[sn:%lli].\n",
            inst->readPC(), inst->seqNum);

    unsigned tid = inst->threadNumber;

    // Remove the instruction from the hash and the list.
    MemDepHashIt hash_it = memDepHash.find(inst->seqNum);

    assert(hash_it != memDepHash.end());

    instList[tid].erase((*hash_it).second->listIt);

    (*hash_it).second = NULL;

    memDepHash.erase(hash_it);
#ifdef DEBUG
    MemDepEntry::memdep_erase++;
#endif
}

template <class MemDepPred, class Impl>
void
MemDepUnit<MemDepPred, Impl>::completeBarrier(DynInstPtr &inst)
{
    wakeDependents(inst);
    completed(inst);

    InstSeqNum barr_sn = inst->seqNum;

    if (inst->isMemBarrier()) {
        assert(loadBarrier && storeBarrier);
        if (loadBarrierSN == barr_sn)
            loadBarrier = false;
        if (storeBarrierSN == barr_sn)
            storeBarrier = false;
    } else if (inst->isWriteBarrier()) {
        assert(storeBarrier);
        if (storeBarrierSN == barr_sn)
            storeBarrier = false;
    }
}

template <class MemDepPred, class Impl>
void
MemDepUnit<MemDepPred, Impl>::wakeDependents(DynInstPtr &inst)
{
    // Only stores and barriers have dependents.
    if (!inst->isStore() && !inst->isMemBarrier() && !inst->isWriteBarrier()) {
        return;
    }

    MemDepEntryPtr inst_entry = findInHash(inst);

    for (int i = 0; i < inst_entry->dependInsts.size(); ++i ) {
        MemDepEntryPtr woken_inst = inst_entry->dependInsts[i];

        if (!woken_inst->inst) {
            // Potentially removed mem dep entries could be on this list
            continue;
        }

        DPRINTF(MemDepUnit, "Waking up a dependent inst, "
                "[sn:%lli].\n",
                woken_inst->inst->seqNum);

        if (woken_inst->regsReady && !woken_inst->squashed) {
            moveToReady(woken_inst);
        } else {
            woken_inst->memDepReady = true;
        }
    }

    inst_entry->dependInsts.clear();
}

template <class MemDepPred, class Impl>
void
MemDepUnit<MemDepPred, Impl>::squash(const InstSeqNum &squashed_num,
                                     unsigned tid)
{
    if (!instsToReplay.empty()) {
        ListIt replay_it = instsToReplay.begin();
        while (replay_it != instsToReplay.end()) {
            if ((*replay_it)->threadNumber == tid &&
                (*replay_it)->seqNum > squashed_num) {
                instsToReplay.erase(replay_it++);
            } else {
                ++replay_it;
            }
        }
    }

    ListIt squash_it = instList[tid].end();
    --squash_it;

    MemDepHashIt hash_it;

    while (!instList[tid].empty() &&
           (*squash_it)->seqNum > squashed_num) {

        DPRINTF(MemDepUnit, "Squashing inst [sn:%lli]\n",
                (*squash_it)->seqNum);

        hash_it = memDepHash.find((*squash_it)->seqNum);

        assert(hash_it != memDepHash.end());

        (*hash_it).second->squashed = true;

        (*hash_it).second = NULL;

        memDepHash.erase(hash_it);
#ifdef DEBUG
        MemDepEntry::memdep_erase++;
#endif

        instList[tid].erase(squash_it--);
    }

    // Tell the dependency predictor to squash as well.
    depPred.squash(squashed_num, tid);
}

template <class MemDepPred, class Impl>
void
MemDepUnit<MemDepPred, Impl>::violation(DynInstPtr &store_inst,
                                        DynInstPtr &violating_load)
{
    DPRINTF(MemDepUnit, "Passing violating PCs to store sets,"
            " load: %#x, store: %#x\n", violating_load->readPC(),
            store_inst->readPC());
    // Tell the memory dependence unit of the violation.
    depPred.violation(violating_load->readPC(), store_inst->readPC());
}

template <class MemDepPred, class Impl>
void
MemDepUnit<MemDepPred, Impl>::issue(DynInstPtr &inst)
{
    DPRINTF(MemDepUnit, "Issuing instruction PC %#x [sn:%lli].\n",
            inst->readPC(), inst->seqNum);

    depPred.issued(inst->readPC(), inst->seqNum, inst->isStore());
}

template <class MemDepPred, class Impl>
inline typename MemDepUnit<MemDepPred,Impl>::MemDepEntryPtr &
MemDepUnit<MemDepPred, Impl>::findInHash(const DynInstPtr &inst)
{
    MemDepHashIt hash_it = memDepHash.find(inst->seqNum);

    assert(hash_it != memDepHash.end());

    return (*hash_it).second;
}

template <class MemDepPred, class Impl>
inline void
MemDepUnit<MemDepPred, Impl>::moveToReady(MemDepEntryPtr &woken_inst_entry)
{
    DPRINTF(MemDepUnit, "Adding instruction [sn:%lli] "
            "to the ready list.\n", woken_inst_entry->inst->seqNum);

    assert(!woken_inst_entry->squashed);

    iqPtr->addReadyMemInst(woken_inst_entry->inst);
}


template <class MemDepPred, class Impl>
void
MemDepUnit<MemDepPred, Impl>::dumpLists()
{
    for (unsigned tid=0; tid < Impl::MaxThreads; tid++) {
        cprintf("Instruction list %i size: %i\n",
                tid, instList[tid].size());

        ListIt inst_list_it = instList[tid].begin();
        int num = 0;

        while (inst_list_it != instList[tid].end()) {
            cprintf("Instruction:%i\nPC:%#x\n[sn:%i]\n[tid:%i]\nIssued:%i\n"
                    "Squashed:%i\n\n",
                    num, (*inst_list_it)->readPC(),
                    (*inst_list_it)->seqNum,
                    (*inst_list_it)->threadNumber,
                    (*inst_list_it)->isIssued(),
                    (*inst_list_it)->isSquashed());
            inst_list_it++;
            ++num;
        }
    }

    cprintf("Memory dependence hash size: %i\n", memDepHash.size());

#ifdef DEBUG
    cprintf("Memory dependence entries: %i\n", MemDepEntry::memdep_count);
#endif
}