mem_dep_unit_impl.hh revision 7676:92274350b953 
1/*
2 * Copyright (c) 2004-2006 The Regents of The University of Michigan
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * Authors: Kevin Lim
29 */
30
31#include <map>
32
33#include "cpu/o3/inst_queue.hh"
34#include "cpu/o3/mem_dep_unit.hh"
35#include "params/DerivO3CPU.hh"
36
37template <class MemDepPred, class Impl>
38MemDepUnit<MemDepPred, Impl>::MemDepUnit()
39    : loadBarrier(false), loadBarrierSN(0), storeBarrier(false),
40      storeBarrierSN(0), iqPtr(NULL)
41{
42}
43
44template <class MemDepPred, class Impl>
45MemDepUnit<MemDepPred, Impl>::MemDepUnit(DerivO3CPUParams *params)
46    : _name(params->name + ".memdepunit"),
47      depPred(params->SSITSize, params->LFSTSize), loadBarrier(false),
48      loadBarrierSN(0), storeBarrier(false), storeBarrierSN(0), iqPtr(NULL)
49{
50    DPRINTF(MemDepUnit, "Creating MemDepUnit object.\n");
51}
52
53template <class MemDepPred, class Impl>
54MemDepUnit<MemDepPred, Impl>::~MemDepUnit()
55{
56    for (ThreadID tid = 0; tid < Impl::MaxThreads; tid++) {
57
58        ListIt inst_list_it = instList[tid].begin();
59
60        MemDepHashIt hash_it;
61
62        while (!instList[tid].empty()) {
63            hash_it = memDepHash.find((*inst_list_it)->seqNum);
64
65            assert(hash_it != memDepHash.end());
66
67            memDepHash.erase(hash_it);
68
69            instList[tid].erase(inst_list_it++);
70        }
71    }
72
73#ifdef DEBUG
74    assert(MemDepEntry::memdep_count == 0);
75#endif
76}
77
78template <class MemDepPred, class Impl>
79void
80MemDepUnit<MemDepPred, Impl>::init(DerivO3CPUParams *params, ThreadID tid)
81{
82    DPRINTF(MemDepUnit, "Creating MemDepUnit %i object.\n",tid);
83
84    _name = csprintf("%s.memDep%d", params->name, tid);
85    id = tid;
86
87    depPred.init(params->SSITSize, params->LFSTSize);
88}
89
90template <class MemDepPred, class Impl>
91void
92MemDepUnit<MemDepPred, Impl>::regStats()
93{
94    insertedLoads
95        .name(name() + ".insertedLoads")
96        .desc("Number of loads inserted to the mem dependence unit.");
97
98    insertedStores
99        .name(name() + ".insertedStores")
100        .desc("Number of stores inserted to the mem dependence unit.");
101
102    conflictingLoads
103        .name(name() + ".conflictingLoads")
104        .desc("Number of conflicting loads.");
105
106    conflictingStores
107        .name(name() + ".conflictingStores")
108        .desc("Number of conflicting stores.");
109}
110
111template <class MemDepPred, class Impl>
112void
113MemDepUnit<MemDepPred, Impl>::switchOut()
114{
115    assert(instList[0].empty());
116    assert(instsToReplay.empty());
117    assert(memDepHash.empty());
118    // Clear any state.
119    for (int i = 0; i < Impl::MaxThreads; ++i) {
120        instList[i].clear();
121    }
122    instsToReplay.clear();
123    memDepHash.clear();
124}
125
126template <class MemDepPred, class Impl>
127void
128MemDepUnit<MemDepPred, Impl>::takeOverFrom()
129{
130    // Be sure to reset all state.
131    loadBarrier = storeBarrier = false;
132    loadBarrierSN = storeBarrierSN = 0;
133    depPred.clear();
134}
135
136template <class MemDepPred, class Impl>
137void
138MemDepUnit<MemDepPred, Impl>::setIQ(InstructionQueue<Impl> *iq_ptr)
139{
140    iqPtr = iq_ptr;
141}
142
143template <class MemDepPred, class Impl>
144void
145MemDepUnit<MemDepPred, Impl>::insert(DynInstPtr &inst)
146{
147    ThreadID tid = inst->threadNumber;
148
149    MemDepEntryPtr inst_entry = new MemDepEntry(inst);
150
151    // Add the MemDepEntry to the hash.
152    memDepHash.insert(
153        std::pair<InstSeqNum, MemDepEntryPtr>(inst->seqNum, inst_entry));
154#ifdef DEBUG
155    MemDepEntry::memdep_insert++;
156#endif
157
158    instList[tid].push_back(inst);
159
160    inst_entry->listIt = --(instList[tid].end());
161
162    // Check any barriers and the dependence predictor for any
163    // producing memrefs/stores.
164    InstSeqNum producing_store;
165    if (inst->isLoad() && loadBarrier) {
166        DPRINTF(MemDepUnit, "Load barrier [sn:%lli] in flight\n",
167                loadBarrierSN);
168        producing_store = loadBarrierSN;
169    } else if (inst->isStore() && storeBarrier) {
170        DPRINTF(MemDepUnit, "Store barrier [sn:%lli] in flight\n",
171                storeBarrierSN);
172        producing_store = storeBarrierSN;
173    } else {
174        producing_store = depPred.checkInst(inst->readPC());
175    }
176
177    MemDepEntryPtr store_entry = NULL;
178
179    // If there is a producing store, try to find the entry.
180    if (producing_store != 0) {
181        DPRINTF(MemDepUnit, "Searching for producer\n");
182        MemDepHashIt hash_it = memDepHash.find(producing_store);
183
184        if (hash_it != memDepHash.end()) {
185            store_entry = (*hash_it).second;
186            DPRINTF(MemDepUnit, "Proucer found\n");
187        }
188    }
189
190    // If no store entry, then instruction can issue as soon as the registers
191    // are ready.
192    if (!store_entry) {
193        DPRINTF(MemDepUnit, "No dependency for inst PC "
194                "%#x [sn:%lli].\n", inst->readPC(), inst->seqNum);
195
196        inst_entry->memDepReady = true;
197
198        if (inst->readyToIssue()) {
199            inst_entry->regsReady = true;
200
201            moveToReady(inst_entry);
202        }
203    } else {
204        // Otherwise make the instruction dependent on the store/barrier.
205        DPRINTF(MemDepUnit, "Adding to dependency list; "
206                "inst PC %#x is dependent on [sn:%lli].\n",
207                inst->readPC(), producing_store);
208
209        if (inst->readyToIssue()) {
210            inst_entry->regsReady = true;
211        }
212
213        // Clear the bit saying this instruction can issue.
214        inst->clearCanIssue();
215
216        // Add this instruction to the list of dependents.
217        store_entry->dependInsts.push_back(inst_entry);
218
219        if (inst->isLoad()) {
220            ++conflictingLoads;
221        } else {
222            ++conflictingStores;
223        }
224    }
225
226    if (inst->isStore()) {
227        DPRINTF(MemDepUnit, "Inserting store PC %#x [sn:%lli].\n",
228                inst->readPC(), inst->seqNum);
229
230        depPred.insertStore(inst->readPC(), inst->seqNum, inst->threadNumber);
231
232        ++insertedStores;
233    } else if (inst->isLoad()) {
234        ++insertedLoads;
235    } else {
236        panic("Unknown type! (most likely a barrier).");
237    }
238}
239
240template <class MemDepPred, class Impl>
241void
242MemDepUnit<MemDepPred, Impl>::insertNonSpec(DynInstPtr &inst)
243{
244    ThreadID tid = inst->threadNumber;
245
246    MemDepEntryPtr inst_entry = new MemDepEntry(inst);
247
248    // Insert the MemDepEntry into the hash.
249    memDepHash.insert(
250        std::pair<InstSeqNum, MemDepEntryPtr>(inst->seqNum, inst_entry));
251#ifdef DEBUG
252    MemDepEntry::memdep_insert++;
253#endif
254
255    // Add the instruction to the list.
256    instList[tid].push_back(inst);
257
258    inst_entry->listIt = --(instList[tid].end());
259
260    // Might want to turn this part into an inline function or something.
261    // It's shared between both insert functions.
262    if (inst->isStore()) {
263        DPRINTF(MemDepUnit, "Inserting store PC %#x [sn:%lli].\n",
264                inst->readPC(), inst->seqNum);
265
266        depPred.insertStore(inst->readPC(), inst->seqNum, inst->threadNumber);
267
268        ++insertedStores;
269    } else if (inst->isLoad()) {
270        ++insertedLoads;
271    } else {
272        panic("Unknown type! (most likely a barrier).");
273    }
274}
275
276template <class MemDepPred, class Impl>
277void
278MemDepUnit<MemDepPred, Impl>::insertBarrier(DynInstPtr &barr_inst)
279{
280    InstSeqNum barr_sn = barr_inst->seqNum;
281    // Memory barriers block loads and stores, write barriers only stores.
282    if (barr_inst->isMemBarrier()) {
283        loadBarrier = true;
284        loadBarrierSN = barr_sn;
285        storeBarrier = true;
286        storeBarrierSN = barr_sn;
287        DPRINTF(MemDepUnit, "Inserted a memory barrier\n");
288    } else if (barr_inst->isWriteBarrier()) {
289        storeBarrier = true;
290        storeBarrierSN = barr_sn;
291        DPRINTF(MemDepUnit, "Inserted a write barrier\n");
292    }
293
294    ThreadID tid = barr_inst->threadNumber;
295
296    MemDepEntryPtr inst_entry = new MemDepEntry(barr_inst);
297
298    // Add the MemDepEntry to the hash.
299    memDepHash.insert(
300        std::pair<InstSeqNum, MemDepEntryPtr>(barr_sn, inst_entry));
301#ifdef DEBUG
302    MemDepEntry::memdep_insert++;
303#endif
304
305    // Add the instruction to the instruction list.
306    instList[tid].push_back(barr_inst);
307
308    inst_entry->listIt = --(instList[tid].end());
309}
310
311template <class MemDepPred, class Impl>
312void
313MemDepUnit<MemDepPred, Impl>::regsReady(DynInstPtr &inst)
314{
315    DPRINTF(MemDepUnit, "Marking registers as ready for "
316            "instruction PC %#x [sn:%lli].\n",
317            inst->readPC(), inst->seqNum);
318
319    MemDepEntryPtr inst_entry = findInHash(inst);
320
321    inst_entry->regsReady = true;
322
323    if (inst_entry->memDepReady) {
324        DPRINTF(MemDepUnit, "Instruction has its memory "
325                "dependencies resolved, adding it to the ready list.\n");
326
327        moveToReady(inst_entry);
328    } else {
329        DPRINTF(MemDepUnit, "Instruction still waiting on "
330                "memory dependency.\n");
331    }
332}
333
334template <class MemDepPred, class Impl>
335void
336MemDepUnit<MemDepPred, Impl>::nonSpecInstReady(DynInstPtr &inst)
337{
338    DPRINTF(MemDepUnit, "Marking non speculative "
339            "instruction PC %#x as ready [sn:%lli].\n",
340            inst->readPC(), inst->seqNum);
341
342    MemDepEntryPtr inst_entry = findInHash(inst);
343
344    moveToReady(inst_entry);
345}
346
347template <class MemDepPred, class Impl>
348void
349MemDepUnit<MemDepPred, Impl>::reschedule(DynInstPtr &inst)
350{
351    instsToReplay.push_back(inst);
352}
353
354template <class MemDepPred, class Impl>
355void
356MemDepUnit<MemDepPred, Impl>::replay(DynInstPtr &inst)
357{
358    DynInstPtr temp_inst;
359
360    // For now this replay function replays all waiting memory ops.
361    while (!instsToReplay.empty()) {
362        temp_inst = instsToReplay.front();
363
364        MemDepEntryPtr inst_entry = findInHash(temp_inst);
365
366        DPRINTF(MemDepUnit, "Replaying mem instruction PC %#x "
367                "[sn:%lli].\n",
368                temp_inst->readPC(), temp_inst->seqNum);
369
370        moveToReady(inst_entry);
371
372        instsToReplay.pop_front();
373    }
374}
375
376template <class MemDepPred, class Impl>
377void
378MemDepUnit<MemDepPred, Impl>::completed(DynInstPtr &inst)
379{
380    DPRINTF(MemDepUnit, "Completed mem instruction PC %#x "
381            "[sn:%lli].\n",
382            inst->readPC(), inst->seqNum);
383
384    ThreadID tid = inst->threadNumber;
385
386    // Remove the instruction from the hash and the list.
387    MemDepHashIt hash_it = memDepHash.find(inst->seqNum);
388
389    assert(hash_it != memDepHash.end());
390
391    instList[tid].erase((*hash_it).second->listIt);
392
393    (*hash_it).second = NULL;
394
395    memDepHash.erase(hash_it);
396#ifdef DEBUG
397    MemDepEntry::memdep_erase++;
398#endif
399}
400
401template <class MemDepPred, class Impl>
402void
403MemDepUnit<MemDepPred, Impl>::completeBarrier(DynInstPtr &inst)
404{
405    wakeDependents(inst);
406    completed(inst);
407
408    InstSeqNum barr_sn = inst->seqNum;
409
410    if (inst->isMemBarrier()) {
411        assert(loadBarrier && storeBarrier);
412        if (loadBarrierSN == barr_sn)
413            loadBarrier = false;
414        if (storeBarrierSN == barr_sn)
415            storeBarrier = false;
416    } else if (inst->isWriteBarrier()) {
417        assert(storeBarrier);
418        if (storeBarrierSN == barr_sn)
419            storeBarrier = false;
420    }
421}
422
423template <class MemDepPred, class Impl>
424void
425MemDepUnit<MemDepPred, Impl>::wakeDependents(DynInstPtr &inst)
426{
427    // Only stores and barriers have dependents.
428    if (!inst->isStore() && !inst->isMemBarrier() && !inst->isWriteBarrier()) {
429        return;
430    }
431
432    MemDepEntryPtr inst_entry = findInHash(inst);
433
434    for (int i = 0; i < inst_entry->dependInsts.size(); ++i ) {
435        MemDepEntryPtr woken_inst = inst_entry->dependInsts[i];
436
437        if (!woken_inst->inst) {
438            // Potentially removed mem dep entries could be on this list
439            continue;
440        }
441
442        DPRINTF(MemDepUnit, "Waking up a dependent inst, "
443                "[sn:%lli].\n",
444                woken_inst->inst->seqNum);
445
446        if (woken_inst->regsReady && !woken_inst->squashed) {
447            moveToReady(woken_inst);
448        } else {
449            woken_inst->memDepReady = true;
450        }
451    }
452
453    inst_entry->dependInsts.clear();
454}
455
456template <class MemDepPred, class Impl>
457void
458MemDepUnit<MemDepPred, Impl>::squash(const InstSeqNum &squashed_num,
459                                     ThreadID tid)
460{
461    if (!instsToReplay.empty()) {
462        ListIt replay_it = instsToReplay.begin();
463        while (replay_it != instsToReplay.end()) {
464            if ((*replay_it)->threadNumber == tid &&
465                (*replay_it)->seqNum > squashed_num) {
466                instsToReplay.erase(replay_it++);
467            } else {
468                ++replay_it;
469            }
470        }
471    }
472
473    ListIt squash_it = instList[tid].end();
474    --squash_it;
475
476    MemDepHashIt hash_it;
477
478    while (!instList[tid].empty() &&
479           (*squash_it)->seqNum > squashed_num) {
480
481        DPRINTF(MemDepUnit, "Squashing inst [sn:%lli]\n",
482                (*squash_it)->seqNum);
483
484        hash_it = memDepHash.find((*squash_it)->seqNum);
485
486        assert(hash_it != memDepHash.end());
487
488        (*hash_it).second->squashed = true;
489
490        (*hash_it).second = NULL;
491
492        memDepHash.erase(hash_it);
493#ifdef DEBUG
494        MemDepEntry::memdep_erase++;
495#endif
496
497        instList[tid].erase(squash_it--);
498    }
499
500    // Tell the dependency predictor to squash as well.
501    depPred.squash(squashed_num, tid);
502}
503
504template <class MemDepPred, class Impl>
505void
506MemDepUnit<MemDepPred, Impl>::violation(DynInstPtr &store_inst,
507                                        DynInstPtr &violating_load)
508{
509    DPRINTF(MemDepUnit, "Passing violating PCs to store sets,"
510            " load: %#x, store: %#x\n", violating_load->readPC(),
511            store_inst->readPC());
512    // Tell the memory dependence unit of the violation.
513    depPred.violation(violating_load->readPC(), store_inst->readPC());
514}
515
516template <class MemDepPred, class Impl>
517void
518MemDepUnit<MemDepPred, Impl>::issue(DynInstPtr &inst)
519{
520    DPRINTF(MemDepUnit, "Issuing instruction PC %#x [sn:%lli].\n",
521            inst->readPC(), inst->seqNum);
522
523    depPred.issued(inst->readPC(), inst->seqNum, inst->isStore());
524}
525
526template <class MemDepPred, class Impl>
527inline typename MemDepUnit<MemDepPred,Impl>::MemDepEntryPtr &
528MemDepUnit<MemDepPred, Impl>::findInHash(const DynInstPtr &inst)
529{
530    MemDepHashIt hash_it = memDepHash.find(inst->seqNum);
531
532    assert(hash_it != memDepHash.end());
533
534    return (*hash_it).second;
535}
536
537template <class MemDepPred, class Impl>
538inline void
539MemDepUnit<MemDepPred, Impl>::moveToReady(MemDepEntryPtr &woken_inst_entry)
540{
541    DPRINTF(MemDepUnit, "Adding instruction [sn:%lli] "
542            "to the ready list.\n", woken_inst_entry->inst->seqNum);
543
544    assert(!woken_inst_entry->squashed);
545
546    iqPtr->addReadyMemInst(woken_inst_entry->inst);
547}
548
549
550template <class MemDepPred, class Impl>
551void
552MemDepUnit<MemDepPred, Impl>::dumpLists()
553{
554    for (ThreadID tid = 0; tid < Impl::MaxThreads; tid++) {
555        cprintf("Instruction list %i size: %i\n",
556                tid, instList[tid].size());
557
558        ListIt inst_list_it = instList[tid].begin();
559        int num = 0;
560
561        while (inst_list_it != instList[tid].end()) {
562            cprintf("Instruction:%i\nPC:%#x\n[sn:%i]\n[tid:%i]\nIssued:%i\n"
563                    "Squashed:%i\n\n",
564                    num, (*inst_list_it)->readPC(),
565                    (*inst_list_it)->seqNum,
566                    (*inst_list_it)->threadNumber,
567                    (*inst_list_it)->isIssued(),
568                    (*inst_list_it)->isSquashed());
569            inst_list_it++;
570            ++num;
571        }
572    }
573
574    cprintf("Memory dependence hash size: %i\n", memDepHash.size());
575
576#ifdef DEBUG
577    cprintf("Memory dependence entries: %i\n", MemDepEntry::memdep_count);
578#endif
579}
580