commit_impl.hh revision 8137:48371b9fb929
1/* 2 * Copyright (c) 2010 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 <algorithm> 45#include <string> 46 47#include "arch/utility.hh" 48#include "base/cp_annotate.hh" 49#include "base/loader/symtab.hh" 50#include "cpu/timebuf.hh" 51#include "config/full_system.hh" 52#include "config/the_isa.hh" 53#include "config/use_checker.hh" 54#include "cpu/exetrace.hh" 55#include "cpu/o3/commit.hh" 56#include "cpu/o3/thread_state.hh" 57#include "params/DerivO3CPU.hh" 58 59#if USE_CHECKER 60#include "cpu/checker/cpu.hh" 61#endif 62 63using namespace std; 64 65template <class Impl> 66DefaultCommit<Impl>::TrapEvent::TrapEvent(DefaultCommit<Impl> *_commit, 67 ThreadID _tid) 68 : Event(CPU_Tick_Pri), commit(_commit), tid(_tid) 69{ 70 this->setFlags(AutoDelete); 71} 72 73template <class Impl> 74void 75DefaultCommit<Impl>::TrapEvent::process() 76{ 77 // This will get reset by commit if it was switched out at the 78 // time of this event processing. 79 commit->trapSquash[tid] = true; 80} 81 82template <class Impl> 83const char * 84DefaultCommit<Impl>::TrapEvent::description() const 85{ 86 return "Trap"; 87} 88 89template <class Impl> 90DefaultCommit<Impl>::DefaultCommit(O3CPU *_cpu, DerivO3CPUParams *params) 91 : cpu(_cpu), 92 squashCounter(0), 93 iewToCommitDelay(params->iewToCommitDelay), 94 commitToIEWDelay(params->commitToIEWDelay), 95 renameToROBDelay(params->renameToROBDelay), 96 fetchToCommitDelay(params->commitToFetchDelay), 97 renameWidth(params->renameWidth), 98 commitWidth(params->commitWidth), 99 numThreads(params->numThreads), 100 drainPending(false), 101 switchedOut(false), 102 trapLatency(params->trapLatency) 103{ 104 _status = Active; 105 _nextStatus = Inactive; 106 std::string policy = params->smtCommitPolicy; 107 108 //Convert string to lowercase 109 std::transform(policy.begin(), policy.end(), policy.begin(), 110 (int(*)(int)) tolower); 111 112 //Assign commit policy 113 if (policy == "aggressive"){ 114 commitPolicy = Aggressive; 115 116 DPRINTF(Commit,"Commit Policy set to Aggressive."); 117 } else if (policy == "roundrobin"){ 118 commitPolicy = RoundRobin; 119 120 //Set-Up Priority List 121 for (ThreadID tid = 0; tid < numThreads; tid++) { 122 priority_list.push_back(tid); 123 } 124 125 DPRINTF(Commit,"Commit Policy set to Round Robin."); 126 } else if (policy == "oldestready"){ 127 commitPolicy = OldestReady; 128 129 DPRINTF(Commit,"Commit Policy set to Oldest Ready."); 130 } else { 131 assert(0 && "Invalid SMT Commit Policy. Options Are: {Aggressive," 132 "RoundRobin,OldestReady}"); 133 } 134 135 for (ThreadID tid = 0; tid < numThreads; tid++) { 136 commitStatus[tid] = Idle; 137 changedROBNumEntries[tid] = false; 138 checkEmptyROB[tid] = false; 139 trapInFlight[tid] = false; 140 committedStores[tid] = false; 141 trapSquash[tid] = false; 142 tcSquash[tid] = false; 143 pc[tid].set(0); 144 lastCommitedSeqNum[tid] = 0; 145 } 146#if FULL_SYSTEM 147 interrupt = NoFault; 148#endif 149} 150 151template <class Impl> 152std::string 153DefaultCommit<Impl>::name() const 154{ 155 return cpu->name() + ".commit"; 156} 157 158template <class Impl> 159void 160DefaultCommit<Impl>::regStats() 161{ 162 using namespace Stats; 163 commitCommittedInsts 164 .name(name() + ".commitCommittedInsts") 165 .desc("The number of committed instructions") 166 .prereq(commitCommittedInsts); 167 commitSquashedInsts 168 .name(name() + ".commitSquashedInsts") 169 .desc("The number of squashed insts skipped by commit") 170 .prereq(commitSquashedInsts); 171 commitSquashEvents 172 .name(name() + ".commitSquashEvents") 173 .desc("The number of times commit is told to squash") 174 .prereq(commitSquashEvents); 175 commitNonSpecStalls 176 .name(name() + ".commitNonSpecStalls") 177 .desc("The number of times commit has been forced to stall to " 178 "communicate backwards") 179 .prereq(commitNonSpecStalls); 180 branchMispredicts 181 .name(name() + ".branchMispredicts") 182 .desc("The number of times a branch was mispredicted") 183 .prereq(branchMispredicts); 184 numCommittedDist 185 .init(0,commitWidth,1) 186 .name(name() + ".COM:committed_per_cycle") 187 .desc("Number of insts commited each cycle") 188 .flags(Stats::pdf) 189 ; 190 191 statComInst 192 .init(cpu->numThreads) 193 .name(name() + ".COM:count") 194 .desc("Number of instructions committed") 195 .flags(total) 196 ; 197 198 statComSwp 199 .init(cpu->numThreads) 200 .name(name() + ".COM:swp_count") 201 .desc("Number of s/w prefetches committed") 202 .flags(total) 203 ; 204 205 statComRefs 206 .init(cpu->numThreads) 207 .name(name() + ".COM:refs") 208 .desc("Number of memory references committed") 209 .flags(total) 210 ; 211 212 statComLoads 213 .init(cpu->numThreads) 214 .name(name() + ".COM:loads") 215 .desc("Number of loads committed") 216 .flags(total) 217 ; 218 219 statComMembars 220 .init(cpu->numThreads) 221 .name(name() + ".COM:membars") 222 .desc("Number of memory barriers committed") 223 .flags(total) 224 ; 225 226 statComBranches 227 .init(cpu->numThreads) 228 .name(name() + ".COM:branches") 229 .desc("Number of branches committed") 230 .flags(total) 231 ; 232 233 statComFloating 234 .init(cpu->numThreads) 235 .name(name() + ".COM:fp_insts") 236 .desc("Number of committed floating point instructions.") 237 .flags(total) 238 ; 239 240 statComInteger 241 .init(cpu->numThreads) 242 .name(name()+".COM:int_insts") 243 .desc("Number of committed integer instructions.") 244 .flags(total) 245 ; 246 247 statComFunctionCalls 248 .init(cpu->numThreads) 249 .name(name()+".COM:function_calls") 250 .desc("Number of function calls committed.") 251 .flags(total) 252 ; 253 254 commitEligible 255 .init(cpu->numThreads) 256 .name(name() + ".COM:bw_limited") 257 .desc("number of insts not committed due to BW limits") 258 .flags(total) 259 ; 260 261 commitEligibleSamples 262 .name(name() + ".COM:bw_lim_events") 263 .desc("number cycles where commit BW limit reached") 264 ; 265} 266 267template <class Impl> 268void 269DefaultCommit<Impl>::setThreads(std::vector<Thread *> &threads) 270{ 271 thread = threads; 272} 273 274template <class Impl> 275void 276DefaultCommit<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr) 277{ 278 timeBuffer = tb_ptr; 279 280 // Setup wire to send information back to IEW. 281 toIEW = timeBuffer->getWire(0); 282 283 // Setup wire to read data from IEW (for the ROB). 284 robInfoFromIEW = timeBuffer->getWire(-iewToCommitDelay); 285} 286 287template <class Impl> 288void 289DefaultCommit<Impl>::setFetchQueue(TimeBuffer<FetchStruct> *fq_ptr) 290{ 291 fetchQueue = fq_ptr; 292 293 // Setup wire to get instructions from rename (for the ROB). 294 fromFetch = fetchQueue->getWire(-fetchToCommitDelay); 295} 296 297template <class Impl> 298void 299DefaultCommit<Impl>::setRenameQueue(TimeBuffer<RenameStruct> *rq_ptr) 300{ 301 renameQueue = rq_ptr; 302 303 // Setup wire to get instructions from rename (for the ROB). 304 fromRename = renameQueue->getWire(-renameToROBDelay); 305} 306 307template <class Impl> 308void 309DefaultCommit<Impl>::setIEWQueue(TimeBuffer<IEWStruct> *iq_ptr) 310{ 311 iewQueue = iq_ptr; 312 313 // Setup wire to get instructions from IEW. 314 fromIEW = iewQueue->getWire(-iewToCommitDelay); 315} 316 317template <class Impl> 318void 319DefaultCommit<Impl>::setIEWStage(IEW *iew_stage) 320{ 321 iewStage = iew_stage; 322} 323 324template<class Impl> 325void 326DefaultCommit<Impl>::setActiveThreads(list<ThreadID> *at_ptr) 327{ 328 activeThreads = at_ptr; 329} 330 331template <class Impl> 332void 333DefaultCommit<Impl>::setRenameMap(RenameMap rm_ptr[]) 334{ 335 for (ThreadID tid = 0; tid < numThreads; tid++) 336 renameMap[tid] = &rm_ptr[tid]; 337} 338 339template <class Impl> 340void 341DefaultCommit<Impl>::setROB(ROB *rob_ptr) 342{ 343 rob = rob_ptr; 344} 345 346template <class Impl> 347void 348DefaultCommit<Impl>::initStage() 349{ 350 rob->setActiveThreads(activeThreads); 351 rob->resetEntries(); 352 353 // Broadcast the number of free entries. 354 for (ThreadID tid = 0; tid < numThreads; tid++) { 355 toIEW->commitInfo[tid].usedROB = true; 356 toIEW->commitInfo[tid].freeROBEntries = rob->numFreeEntries(tid); 357 toIEW->commitInfo[tid].emptyROB = true; 358 } 359 360 // Commit must broadcast the number of free entries it has at the 361 // start of the simulation, so it starts as active. 362 cpu->activateStage(O3CPU::CommitIdx); 363 364 cpu->activityThisCycle(); 365 trapLatency = cpu->ticks(trapLatency); 366} 367 368template <class Impl> 369bool 370DefaultCommit<Impl>::drain() 371{ 372 drainPending = true; 373 374 return false; 375} 376 377template <class Impl> 378void 379DefaultCommit<Impl>::switchOut() 380{ 381 switchedOut = true; 382 drainPending = false; 383 rob->switchOut(); 384} 385 386template <class Impl> 387void 388DefaultCommit<Impl>::resume() 389{ 390 drainPending = false; 391} 392 393template <class Impl> 394void 395DefaultCommit<Impl>::takeOverFrom() 396{ 397 switchedOut = false; 398 _status = Active; 399 _nextStatus = Inactive; 400 for (ThreadID tid = 0; tid < numThreads; tid++) { 401 commitStatus[tid] = Idle; 402 changedROBNumEntries[tid] = false; 403 trapSquash[tid] = false; 404 tcSquash[tid] = false; 405 } 406 squashCounter = 0; 407 rob->takeOverFrom(); 408} 409 410template <class Impl> 411void 412DefaultCommit<Impl>::updateStatus() 413{ 414 // reset ROB changed variable 415 list<ThreadID>::iterator threads = activeThreads->begin(); 416 list<ThreadID>::iterator end = activeThreads->end(); 417 418 while (threads != end) { 419 ThreadID tid = *threads++; 420 421 changedROBNumEntries[tid] = false; 422 423 // Also check if any of the threads has a trap pending 424 if (commitStatus[tid] == TrapPending || 425 commitStatus[tid] == FetchTrapPending) { 426 _nextStatus = Active; 427 } 428 } 429 430 if (_nextStatus == Inactive && _status == Active) { 431 DPRINTF(Activity, "Deactivating stage.\n"); 432 cpu->deactivateStage(O3CPU::CommitIdx); 433 } else if (_nextStatus == Active && _status == Inactive) { 434 DPRINTF(Activity, "Activating stage.\n"); 435 cpu->activateStage(O3CPU::CommitIdx); 436 } 437 438 _status = _nextStatus; 439} 440 441template <class Impl> 442void 443DefaultCommit<Impl>::setNextStatus() 444{ 445 int squashes = 0; 446 447 list<ThreadID>::iterator threads = activeThreads->begin(); 448 list<ThreadID>::iterator end = activeThreads->end(); 449 450 while (threads != end) { 451 ThreadID tid = *threads++; 452 453 if (commitStatus[tid] == ROBSquashing) { 454 squashes++; 455 } 456 } 457 458 squashCounter = squashes; 459 460 // If commit is currently squashing, then it will have activity for the 461 // next cycle. Set its next status as active. 462 if (squashCounter) { 463 _nextStatus = Active; 464 } 465} 466 467template <class Impl> 468bool 469DefaultCommit<Impl>::changedROBEntries() 470{ 471 list<ThreadID>::iterator threads = activeThreads->begin(); 472 list<ThreadID>::iterator end = activeThreads->end(); 473 474 while (threads != end) { 475 ThreadID tid = *threads++; 476 477 if (changedROBNumEntries[tid]) { 478 return true; 479 } 480 } 481 482 return false; 483} 484 485template <class Impl> 486size_t 487DefaultCommit<Impl>::numROBFreeEntries(ThreadID tid) 488{ 489 return rob->numFreeEntries(tid); 490} 491 492template <class Impl> 493void 494DefaultCommit<Impl>::generateTrapEvent(ThreadID tid) 495{ 496 DPRINTF(Commit, "Generating trap event for [tid:%i]\n", tid); 497 498 TrapEvent *trap = new TrapEvent(this, tid); 499 500 cpu->schedule(trap, curTick() + trapLatency); 501 trapInFlight[tid] = true; 502} 503 504template <class Impl> 505void 506DefaultCommit<Impl>::generateTCEvent(ThreadID tid) 507{ 508 assert(!trapInFlight[tid]); 509 DPRINTF(Commit, "Generating TC squash event for [tid:%i]\n", tid); 510 511 tcSquash[tid] = true; 512} 513 514template <class Impl> 515void 516DefaultCommit<Impl>::squashAll(ThreadID tid) 517{ 518 // If we want to include the squashing instruction in the squash, 519 // then use one older sequence number. 520 // Hopefully this doesn't mess things up. Basically I want to squash 521 // all instructions of this thread. 522 InstSeqNum squashed_inst = rob->isEmpty() ? 523 lastCommitedSeqNum[tid] : rob->readHeadInst(tid)->seqNum - 1; 524 525 // All younger instructions will be squashed. Set the sequence 526 // number as the youngest instruction in the ROB (0 in this case. 527 // Hopefully nothing breaks.) 528 youngestSeqNum[tid] = lastCommitedSeqNum[tid]; 529 530 rob->squash(squashed_inst, tid); 531 changedROBNumEntries[tid] = true; 532 533 // Send back the sequence number of the squashed instruction. 534 toIEW->commitInfo[tid].doneSeqNum = squashed_inst; 535 536 // Send back the squash signal to tell stages that they should 537 // squash. 538 toIEW->commitInfo[tid].squash = true; 539 540 // Send back the rob squashing signal so other stages know that 541 // the ROB is in the process of squashing. 542 toIEW->commitInfo[tid].robSquashing = true; 543 544 toIEW->commitInfo[tid].mispredictInst = NULL; 545 toIEW->commitInfo[tid].squashInst = NULL; 546 547 toIEW->commitInfo[tid].pc = pc[tid]; 548} 549 550template <class Impl> 551void 552DefaultCommit<Impl>::squashFromTrap(ThreadID tid) 553{ 554 squashAll(tid); 555 556 DPRINTF(Commit, "Squashing from trap, restarting at PC %s\n", pc[tid]); 557 558 thread[tid]->trapPending = false; 559 thread[tid]->inSyscall = false; 560 trapInFlight[tid] = false; 561 562 trapSquash[tid] = false; 563 564 commitStatus[tid] = ROBSquashing; 565 cpu->activityThisCycle(); 566} 567 568template <class Impl> 569void 570DefaultCommit<Impl>::squashFromTC(ThreadID tid) 571{ 572 squashAll(tid); 573 574 DPRINTF(Commit, "Squashing from TC, restarting at PC %s\n", pc[tid]); 575 576 thread[tid]->inSyscall = false; 577 assert(!thread[tid]->trapPending); 578 579 commitStatus[tid] = ROBSquashing; 580 cpu->activityThisCycle(); 581 582 tcSquash[tid] = false; 583} 584 585template <class Impl> 586void 587DefaultCommit<Impl>::squashAfter(ThreadID tid, DynInstPtr &head_inst, 588 uint64_t squash_after_seq_num) 589{ 590 youngestSeqNum[tid] = squash_after_seq_num; 591 592 rob->squash(squash_after_seq_num, tid); 593 changedROBNumEntries[tid] = true; 594 595 // Send back the sequence number of the squashed instruction. 596 toIEW->commitInfo[tid].doneSeqNum = squash_after_seq_num; 597 598 toIEW->commitInfo[tid].squashInst = head_inst; 599 // Send back the squash signal to tell stages that they should squash. 600 toIEW->commitInfo[tid].squash = true; 601 602 // Send back the rob squashing signal so other stages know that 603 // the ROB is in the process of squashing. 604 toIEW->commitInfo[tid].robSquashing = true; 605 606 toIEW->commitInfo[tid].mispredictInst = NULL; 607 608 toIEW->commitInfo[tid].pc = pc[tid]; 609 DPRINTF(Commit, "Executing squash after for [tid:%i] inst [sn:%lli]\n", 610 tid, squash_after_seq_num); 611 commitStatus[tid] = ROBSquashing; 612} 613 614template <class Impl> 615void 616DefaultCommit<Impl>::tick() 617{ 618 wroteToTimeBuffer = false; 619 _nextStatus = Inactive; 620 621 if (drainPending && rob->isEmpty() && !iewStage->hasStoresToWB()) { 622 cpu->signalDrained(); 623 drainPending = false; 624 return; 625 } 626 627 if (activeThreads->empty()) 628 return; 629 630 list<ThreadID>::iterator threads = activeThreads->begin(); 631 list<ThreadID>::iterator end = activeThreads->end(); 632 633 // Check if any of the threads are done squashing. Change the 634 // status if they are done. 635 while (threads != end) { 636 ThreadID tid = *threads++; 637 638 // Clear the bit saying if the thread has committed stores 639 // this cycle. 640 committedStores[tid] = false; 641 642 if (commitStatus[tid] == ROBSquashing) { 643 644 if (rob->isDoneSquashing(tid)) { 645 commitStatus[tid] = Running; 646 } else { 647 DPRINTF(Commit,"[tid:%u]: Still Squashing, cannot commit any" 648 " insts this cycle.\n", tid); 649 rob->doSquash(tid); 650 toIEW->commitInfo[tid].robSquashing = true; 651 wroteToTimeBuffer = true; 652 } 653 } 654 } 655 656 commit(); 657 658 markCompletedInsts(); 659 660 threads = activeThreads->begin(); 661 662 while (threads != end) { 663 ThreadID tid = *threads++; 664 665 if (!rob->isEmpty(tid) && rob->readHeadInst(tid)->readyToCommit()) { 666 // The ROB has more instructions it can commit. Its next status 667 // will be active. 668 _nextStatus = Active; 669 670 DynInstPtr inst = rob->readHeadInst(tid); 671 672 DPRINTF(Commit,"[tid:%i]: Instruction [sn:%lli] PC %s is head of" 673 " ROB and ready to commit\n", 674 tid, inst->seqNum, inst->pcState()); 675 676 } else if (!rob->isEmpty(tid)) { 677 DynInstPtr inst = rob->readHeadInst(tid); 678 679 DPRINTF(Commit,"[tid:%i]: Can't commit, Instruction [sn:%lli] PC " 680 "%s is head of ROB and not ready\n", 681 tid, inst->seqNum, inst->pcState()); 682 } 683 684 DPRINTF(Commit, "[tid:%i]: ROB has %d insts & %d free entries.\n", 685 tid, rob->countInsts(tid), rob->numFreeEntries(tid)); 686 } 687 688 689 if (wroteToTimeBuffer) { 690 DPRINTF(Activity, "Activity This Cycle.\n"); 691 cpu->activityThisCycle(); 692 } 693 694 updateStatus(); 695} 696 697#if FULL_SYSTEM 698template <class Impl> 699void 700DefaultCommit<Impl>::handleInterrupt() 701{ 702 // Verify that we still have an interrupt to handle 703 if (!cpu->checkInterrupts(cpu->tcBase(0))) { 704 DPRINTF(Commit, "Pending interrupt is cleared by master before " 705 "it got handled. Restart fetching from the orig path.\n"); 706 toIEW->commitInfo[0].clearInterrupt = true; 707 interrupt = NoFault; 708 return; 709 } 710 711 // Wait until the ROB is empty and all stores have drained in 712 // order to enter the interrupt. 713 if (rob->isEmpty() && !iewStage->hasStoresToWB()) { 714 // Squash or record that I need to squash this cycle if 715 // an interrupt needed to be handled. 716 DPRINTF(Commit, "Interrupt detected.\n"); 717 718 // Clear the interrupt now that it's going to be handled 719 toIEW->commitInfo[0].clearInterrupt = true; 720 721 assert(!thread[0]->inSyscall); 722 thread[0]->inSyscall = true; 723 724 // CPU will handle interrupt. 725 cpu->processInterrupts(interrupt); 726 727 thread[0]->inSyscall = false; 728 729 commitStatus[0] = TrapPending; 730 731 // Generate trap squash event. 732 generateTrapEvent(0); 733 734 interrupt = NoFault; 735 } else { 736 DPRINTF(Commit, "Interrupt pending, waiting for ROB to empty.\n"); 737 } 738} 739 740template <class Impl> 741void 742DefaultCommit<Impl>::propagateInterrupt() 743{ 744 if (commitStatus[0] == TrapPending || interrupt || trapSquash[0] || 745 tcSquash[0]) 746 return; 747 748 // Process interrupts if interrupts are enabled, not in PAL 749 // mode, and no other traps or external squashes are currently 750 // pending. 751 // @todo: Allow other threads to handle interrupts. 752 753 // Get any interrupt that happened 754 interrupt = cpu->getInterrupts(); 755 756 // Tell fetch that there is an interrupt pending. This 757 // will make fetch wait until it sees a non PAL-mode PC, 758 // at which point it stops fetching instructions. 759 if (interrupt != NoFault) 760 toIEW->commitInfo[0].interruptPending = true; 761} 762 763#endif // FULL_SYSTEM 764 765template <class Impl> 766void 767DefaultCommit<Impl>::commit() 768{ 769 770#if FULL_SYSTEM 771 // Check for any interrupt that we've already squashed for and start processing it. 772 if (interrupt != NoFault) 773 handleInterrupt(); 774 775 // Check if we have a interrupt and get read to handle it 776 if (cpu->checkInterrupts(cpu->tcBase(0))) 777 propagateInterrupt(); 778#endif // FULL_SYSTEM 779 780 //////////////////////////////////// 781 // Check for any possible squashes, handle them first 782 //////////////////////////////////// 783 list<ThreadID>::iterator threads = activeThreads->begin(); 784 list<ThreadID>::iterator end = activeThreads->end(); 785 786 while (threads != end) { 787 ThreadID tid = *threads++; 788 789 // Not sure which one takes priority. I think if we have 790 // both, that's a bad sign. 791 if (trapSquash[tid] == true) { 792 assert(!tcSquash[tid]); 793 squashFromTrap(tid); 794 } else if (tcSquash[tid] == true) { 795 assert(commitStatus[tid] != TrapPending); 796 squashFromTC(tid); 797 } 798 799 // Squashed sequence number must be older than youngest valid 800 // instruction in the ROB. This prevents squashes from younger 801 // instructions overriding squashes from older instructions. 802 if (fromIEW->squash[tid] && 803 commitStatus[tid] != TrapPending && 804 fromIEW->squashedSeqNum[tid] <= youngestSeqNum[tid]) { 805 806 if (fromIEW->mispredictInst[tid]) { 807 DPRINTF(Commit, 808 "[tid:%i]: Squashing due to branch mispred PC:%#x [sn:%i]\n", 809 tid, 810 fromIEW->mispredictInst[tid]->instAddr(), 811 fromIEW->squashedSeqNum[tid]); 812 } else { 813 DPRINTF(Commit, 814 "[tid:%i]: Squashing due to order violation [sn:%i]\n", 815 tid, fromIEW->squashedSeqNum[tid]); 816 } 817 818 DPRINTF(Commit, "[tid:%i]: Redirecting to PC %#x\n", 819 tid, 820 fromIEW->pc[tid].nextInstAddr()); 821 822 commitStatus[tid] = ROBSquashing; 823 824 // If we want to include the squashing instruction in the squash, 825 // then use one older sequence number. 826 InstSeqNum squashed_inst = fromIEW->squashedSeqNum[tid]; 827 828 if (fromIEW->includeSquashInst[tid] == true) { 829 squashed_inst--; 830 } 831 832 // All younger instructions will be squashed. Set the sequence 833 // number as the youngest instruction in the ROB. 834 youngestSeqNum[tid] = squashed_inst; 835 836 rob->squash(squashed_inst, tid); 837 changedROBNumEntries[tid] = true; 838 839 toIEW->commitInfo[tid].doneSeqNum = squashed_inst; 840 841 toIEW->commitInfo[tid].squash = true; 842 843 // Send back the rob squashing signal so other stages know that 844 // the ROB is in the process of squashing. 845 toIEW->commitInfo[tid].robSquashing = true; 846 847 toIEW->commitInfo[tid].mispredictInst = 848 fromIEW->mispredictInst[tid]; 849 toIEW->commitInfo[tid].branchTaken = 850 fromIEW->branchTaken[tid]; 851 toIEW->commitInfo[tid].squashInst = NULL; 852 853 toIEW->commitInfo[tid].pc = fromIEW->pc[tid]; 854 855 if (toIEW->commitInfo[tid].mispredictInst) { 856 ++branchMispredicts; 857 } 858 } 859 860 } 861 862 setNextStatus(); 863 864 if (squashCounter != numThreads) { 865 // If we're not currently squashing, then get instructions. 866 getInsts(); 867 868 // Try to commit any instructions. 869 commitInsts(); 870 } 871 872 //Check for any activity 873 threads = activeThreads->begin(); 874 875 while (threads != end) { 876 ThreadID tid = *threads++; 877 878 if (changedROBNumEntries[tid]) { 879 toIEW->commitInfo[tid].usedROB = true; 880 toIEW->commitInfo[tid].freeROBEntries = rob->numFreeEntries(tid); 881 882 wroteToTimeBuffer = true; 883 changedROBNumEntries[tid] = false; 884 if (rob->isEmpty(tid)) 885 checkEmptyROB[tid] = true; 886 } 887 888 // ROB is only considered "empty" for previous stages if: a) 889 // ROB is empty, b) there are no outstanding stores, c) IEW 890 // stage has received any information regarding stores that 891 // committed. 892 // c) is checked by making sure to not consider the ROB empty 893 // on the same cycle as when stores have been committed. 894 // @todo: Make this handle multi-cycle communication between 895 // commit and IEW. 896 if (checkEmptyROB[tid] && rob->isEmpty(tid) && 897 !iewStage->hasStoresToWB(tid) && !committedStores[tid]) { 898 checkEmptyROB[tid] = false; 899 toIEW->commitInfo[tid].usedROB = true; 900 toIEW->commitInfo[tid].emptyROB = true; 901 toIEW->commitInfo[tid].freeROBEntries = rob->numFreeEntries(tid); 902 wroteToTimeBuffer = true; 903 } 904 905 } 906} 907 908template <class Impl> 909void 910DefaultCommit<Impl>::commitInsts() 911{ 912 //////////////////////////////////// 913 // Handle commit 914 // Note that commit will be handled prior to putting new 915 // instructions in the ROB so that the ROB only tries to commit 916 // instructions it has in this current cycle, and not instructions 917 // it is writing in during this cycle. Can't commit and squash 918 // things at the same time... 919 //////////////////////////////////// 920 921 DPRINTF(Commit, "Trying to commit instructions in the ROB.\n"); 922 923 unsigned num_committed = 0; 924 925 DynInstPtr head_inst; 926 927 // Commit as many instructions as possible until the commit bandwidth 928 // limit is reached, or it becomes impossible to commit any more. 929 while (num_committed < commitWidth) { 930 int commit_thread = getCommittingThread(); 931 932 if (commit_thread == -1 || !rob->isHeadReady(commit_thread)) 933 break; 934 935 head_inst = rob->readHeadInst(commit_thread); 936 937 ThreadID tid = head_inst->threadNumber; 938 939 assert(tid == commit_thread); 940 941 DPRINTF(Commit, "Trying to commit head instruction, [sn:%i] [tid:%i]\n", 942 head_inst->seqNum, tid); 943 944 // If the head instruction is squashed, it is ready to retire 945 // (be removed from the ROB) at any time. 946 if (head_inst->isSquashed()) { 947 948 DPRINTF(Commit, "Retiring squashed instruction from " 949 "ROB.\n"); 950 951 rob->retireHead(commit_thread); 952 953 ++commitSquashedInsts; 954 955 // Record that the number of ROB entries has changed. 956 changedROBNumEntries[tid] = true; 957 } else { 958 pc[tid] = head_inst->pcState(); 959 960 // Increment the total number of non-speculative instructions 961 // executed. 962 // Hack for now: it really shouldn't happen until after the 963 // commit is deemed to be successful, but this count is needed 964 // for syscalls. 965 thread[tid]->funcExeInst++; 966 967 // Try to commit the head instruction. 968 bool commit_success = commitHead(head_inst, num_committed); 969 970 if (commit_success) { 971 ++num_committed; 972 973 changedROBNumEntries[tid] = true; 974 975 // Set the doneSeqNum to the youngest committed instruction. 976 toIEW->commitInfo[tid].doneSeqNum = head_inst->seqNum; 977 978 ++commitCommittedInsts; 979 980 // To match the old model, don't count nops and instruction 981 // prefetches towards the total commit count. 982 if (!head_inst->isNop() && !head_inst->isInstPrefetch()) { 983 cpu->instDone(tid); 984 } 985 986 // Updates misc. registers. 987 head_inst->updateMiscRegs(); 988 989 TheISA::advancePC(pc[tid], head_inst->staticInst); 990 991 // Keep track of the last sequence number commited 992 lastCommitedSeqNum[tid] = head_inst->seqNum; 993 994 // If this is an instruction that doesn't play nicely with 995 // others squash everything and restart fetch 996 if (head_inst->isSquashAfter()) 997 squashAfter(tid, head_inst, head_inst->seqNum); 998 999 int count = 0; 1000 Addr oldpc; 1001 // Debug statement. Checks to make sure we're not 1002 // currently updating state while handling PC events. 1003 assert(!thread[tid]->inSyscall && !thread[tid]->trapPending); 1004 do { 1005 oldpc = pc[tid].instAddr(); 1006 cpu->system->pcEventQueue.service(thread[tid]->getTC()); 1007 count++; 1008 } while (oldpc != pc[tid].instAddr()); 1009 if (count > 1) { 1010 DPRINTF(Commit, 1011 "PC skip function event, stopping commit\n"); 1012 break; 1013 } 1014 } else { 1015 DPRINTF(Commit, "Unable to commit head instruction PC:%s " 1016 "[tid:%i] [sn:%i].\n", 1017 head_inst->pcState(), tid ,head_inst->seqNum); 1018 break; 1019 } 1020 } 1021 } 1022 1023 DPRINTF(CommitRate, "%i\n", num_committed); 1024 numCommittedDist.sample(num_committed); 1025 1026 if (num_committed == commitWidth) { 1027 commitEligibleSamples++; 1028 } 1029} 1030 1031template <class Impl> 1032bool 1033DefaultCommit<Impl>::commitHead(DynInstPtr &head_inst, unsigned inst_num) 1034{ 1035 assert(head_inst); 1036 1037 ThreadID tid = head_inst->threadNumber; 1038 1039 // If the instruction is not executed yet, then it will need extra 1040 // handling. Signal backwards that it should be executed. 1041 if (!head_inst->isExecuted()) { 1042 // Keep this number correct. We have not yet actually executed 1043 // and committed this instruction. 1044 thread[tid]->funcExeInst--; 1045 1046 if (head_inst->isNonSpeculative() || 1047 head_inst->isStoreConditional() || 1048 head_inst->isMemBarrier() || 1049 head_inst->isWriteBarrier()) { 1050 1051 DPRINTF(Commit, "Encountered a barrier or non-speculative " 1052 "instruction [sn:%lli] at the head of the ROB, PC %s.\n", 1053 head_inst->seqNum, head_inst->pcState()); 1054 1055 if (inst_num > 0 || iewStage->hasStoresToWB(tid)) { 1056 DPRINTF(Commit, "Waiting for all stores to writeback.\n"); 1057 return false; 1058 } 1059 1060 toIEW->commitInfo[tid].nonSpecSeqNum = head_inst->seqNum; 1061 1062 // Change the instruction so it won't try to commit again until 1063 // it is executed. 1064 head_inst->clearCanCommit(); 1065 1066 ++commitNonSpecStalls; 1067 1068 return false; 1069 } else if (head_inst->isLoad()) { 1070 if (inst_num > 0 || iewStage->hasStoresToWB(tid)) { 1071 DPRINTF(Commit, "Waiting for all stores to writeback.\n"); 1072 return false; 1073 } 1074 1075 assert(head_inst->uncacheable()); 1076 DPRINTF(Commit, "[sn:%lli]: Uncached load, PC %s.\n", 1077 head_inst->seqNum, head_inst->pcState()); 1078 1079 // Send back the non-speculative instruction's sequence 1080 // number. Tell the lsq to re-execute the load. 1081 toIEW->commitInfo[tid].nonSpecSeqNum = head_inst->seqNum; 1082 toIEW->commitInfo[tid].uncached = true; 1083 toIEW->commitInfo[tid].uncachedLoad = head_inst; 1084 1085 head_inst->clearCanCommit(); 1086 1087 return false; 1088 } else { 1089 panic("Trying to commit un-executed instruction " 1090 "of unknown type!\n"); 1091 } 1092 } 1093 1094 if (head_inst->isThreadSync()) { 1095 // Not handled for now. 1096 panic("Thread sync instructions are not handled yet.\n"); 1097 } 1098 1099 // Check if the instruction caused a fault. If so, trap. 1100 Fault inst_fault = head_inst->getFault(); 1101 1102 // Stores mark themselves as completed. 1103 if (!head_inst->isStore() && inst_fault == NoFault) { 1104 head_inst->setCompleted(); 1105 } 1106 1107#if USE_CHECKER 1108 // Use checker prior to updating anything due to traps or PC 1109 // based events. 1110 if (cpu->checker) { 1111 cpu->checker->verify(head_inst); 1112 } 1113#endif 1114 1115 if (inst_fault != NoFault) { 1116 DPRINTF(Commit, "Inst [sn:%lli] PC %s has a fault\n", 1117 head_inst->seqNum, head_inst->pcState()); 1118 1119 if (iewStage->hasStoresToWB(tid) || inst_num > 0) { 1120 DPRINTF(Commit, "Stores outstanding, fault must wait.\n"); 1121 return false; 1122 } 1123 1124 head_inst->setCompleted(); 1125 1126#if USE_CHECKER 1127 if (cpu->checker && head_inst->isStore()) { 1128 cpu->checker->verify(head_inst); 1129 } 1130#endif 1131 1132 assert(!thread[tid]->inSyscall); 1133 1134 // Mark that we're in state update mode so that the trap's 1135 // execution doesn't generate extra squashes. 1136 thread[tid]->inSyscall = true; 1137 1138 // Execute the trap. Although it's slightly unrealistic in 1139 // terms of timing (as it doesn't wait for the full timing of 1140 // the trap event to complete before updating state), it's 1141 // needed to update the state as soon as possible. This 1142 // prevents external agents from changing any specific state 1143 // that the trap need. 1144 cpu->trap(inst_fault, tid, head_inst->staticInst); 1145 1146 // Exit state update mode to avoid accidental updating. 1147 thread[tid]->inSyscall = false; 1148 1149 commitStatus[tid] = TrapPending; 1150 1151 DPRINTF(Commit, "Committing instruction with fault [sn:%lli]\n", 1152 head_inst->seqNum); 1153 if (head_inst->traceData) { 1154 if (DTRACE(ExecFaulting)) { 1155 head_inst->traceData->setFetchSeq(head_inst->seqNum); 1156 head_inst->traceData->setCPSeq(thread[tid]->numInst); 1157 head_inst->traceData->dump(); 1158 } 1159 delete head_inst->traceData; 1160 head_inst->traceData = NULL; 1161 } 1162 1163 // Generate trap squash event. 1164 generateTrapEvent(tid); 1165 return false; 1166 } 1167 1168 updateComInstStats(head_inst); 1169 1170#if FULL_SYSTEM 1171 if (thread[tid]->profile) { 1172 thread[tid]->profilePC = head_inst->instAddr(); 1173 ProfileNode *node = thread[tid]->profile->consume(thread[tid]->getTC(), 1174 head_inst->staticInst); 1175 1176 if (node) 1177 thread[tid]->profileNode = node; 1178 } 1179 if (CPA::available()) { 1180 if (head_inst->isControl()) { 1181 ThreadContext *tc = thread[tid]->getTC(); 1182 CPA::cpa()->swAutoBegin(tc, head_inst->nextInstAddr()); 1183 } 1184 } 1185#endif 1186 DPRINTF(Commit, "Committing instruction with [sn:%lli]\n", 1187 head_inst->seqNum); 1188 if (head_inst->traceData) { 1189 head_inst->traceData->setFetchSeq(head_inst->seqNum); 1190 head_inst->traceData->setCPSeq(thread[tid]->numInst); 1191 head_inst->traceData->dump(); 1192 delete head_inst->traceData; 1193 head_inst->traceData = NULL; 1194 } 1195 1196 // Update the commit rename map 1197 for (int i = 0; i < head_inst->numDestRegs(); i++) { 1198 renameMap[tid]->setEntry(head_inst->flattenedDestRegIdx(i), 1199 head_inst->renamedDestRegIdx(i)); 1200 } 1201 1202 if (head_inst->isCopy()) 1203 panic("Should not commit any copy instructions!"); 1204 1205 // Finally clear the head ROB entry. 1206 rob->retireHead(tid); 1207 1208 // If this was a store, record it for this cycle. 1209 if (head_inst->isStore()) 1210 committedStores[tid] = true; 1211 1212 // Return true to indicate that we have committed an instruction. 1213 return true; 1214} 1215 1216template <class Impl> 1217void 1218DefaultCommit<Impl>::getInsts() 1219{ 1220 DPRINTF(Commit, "Getting instructions from Rename stage.\n"); 1221 1222 // Read any renamed instructions and place them into the ROB. 1223 int insts_to_process = std::min((int)renameWidth, fromRename->size); 1224 1225 for (int inst_num = 0; inst_num < insts_to_process; ++inst_num) { 1226 DynInstPtr inst; 1227 1228 inst = fromRename->insts[inst_num]; 1229 ThreadID tid = inst->threadNumber; 1230 1231 if (!inst->isSquashed() && 1232 commitStatus[tid] != ROBSquashing && 1233 commitStatus[tid] != TrapPending) { 1234 changedROBNumEntries[tid] = true; 1235 1236 DPRINTF(Commit, "Inserting PC %s [sn:%i] [tid:%i] into ROB.\n", 1237 inst->pcState(), inst->seqNum, tid); 1238 1239 rob->insertInst(inst); 1240 1241 assert(rob->getThreadEntries(tid) <= rob->getMaxEntries(tid)); 1242 1243 youngestSeqNum[tid] = inst->seqNum; 1244 } else { 1245 DPRINTF(Commit, "Instruction PC %s [sn:%i] [tid:%i] was " 1246 "squashed, skipping.\n", 1247 inst->pcState(), inst->seqNum, tid); 1248 } 1249 } 1250} 1251 1252template <class Impl> 1253void 1254DefaultCommit<Impl>::skidInsert() 1255{ 1256 DPRINTF(Commit, "Attempting to any instructions from rename into " 1257 "skidBuffer.\n"); 1258 1259 for (int inst_num = 0; inst_num < fromRename->size; ++inst_num) { 1260 DynInstPtr inst = fromRename->insts[inst_num]; 1261 1262 if (!inst->isSquashed()) { 1263 DPRINTF(Commit, "Inserting PC %s [sn:%i] [tid:%i] into ", 1264 "skidBuffer.\n", inst->pcState(), inst->seqNum, 1265 inst->threadNumber); 1266 skidBuffer.push(inst); 1267 } else { 1268 DPRINTF(Commit, "Instruction PC %s [sn:%i] [tid:%i] was " 1269 "squashed, skipping.\n", 1270 inst->pcState(), inst->seqNum, inst->threadNumber); 1271 } 1272 } 1273} 1274 1275template <class Impl> 1276void 1277DefaultCommit<Impl>::markCompletedInsts() 1278{ 1279 // Grab completed insts out of the IEW instruction queue, and mark 1280 // instructions completed within the ROB. 1281 for (int inst_num = 0; 1282 inst_num < fromIEW->size && fromIEW->insts[inst_num]; 1283 ++inst_num) 1284 { 1285 if (!fromIEW->insts[inst_num]->isSquashed()) { 1286 DPRINTF(Commit, "[tid:%i]: Marking PC %s, [sn:%lli] ready " 1287 "within ROB.\n", 1288 fromIEW->insts[inst_num]->threadNumber, 1289 fromIEW->insts[inst_num]->pcState(), 1290 fromIEW->insts[inst_num]->seqNum); 1291 1292 // Mark the instruction as ready to commit. 1293 fromIEW->insts[inst_num]->setCanCommit(); 1294 } 1295 } 1296} 1297 1298template <class Impl> 1299bool 1300DefaultCommit<Impl>::robDoneSquashing() 1301{ 1302 list<ThreadID>::iterator threads = activeThreads->begin(); 1303 list<ThreadID>::iterator end = activeThreads->end(); 1304 1305 while (threads != end) { 1306 ThreadID tid = *threads++; 1307 1308 if (!rob->isDoneSquashing(tid)) 1309 return false; 1310 } 1311 1312 return true; 1313} 1314 1315template <class Impl> 1316void 1317DefaultCommit<Impl>::updateComInstStats(DynInstPtr &inst) 1318{ 1319 ThreadID tid = inst->threadNumber; 1320 1321 // 1322 // Pick off the software prefetches 1323 // 1324#ifdef TARGET_ALPHA 1325 if (inst->isDataPrefetch()) { 1326 statComSwp[tid]++; 1327 } else { 1328 statComInst[tid]++; 1329 } 1330#else 1331 statComInst[tid]++; 1332#endif 1333 1334 // 1335 // Control Instructions 1336 // 1337 if (inst->isControl()) 1338 statComBranches[tid]++; 1339 1340 // 1341 // Memory references 1342 // 1343 if (inst->isMemRef()) { 1344 statComRefs[tid]++; 1345 1346 if (inst->isLoad()) { 1347 statComLoads[tid]++; 1348 } 1349 } 1350 1351 if (inst->isMemBarrier()) { 1352 statComMembars[tid]++; 1353 } 1354 1355 // Integer Instruction 1356 if (inst->isInteger()) 1357 statComInteger[tid]++; 1358 1359 // Floating Point Instruction 1360 if (inst->isFloating()) 1361 statComFloating[tid]++; 1362 1363 // Function Calls 1364 if (inst->isCall()) 1365 statComFunctionCalls[tid]++; 1366 1367} 1368 1369//////////////////////////////////////// 1370// // 1371// SMT COMMIT POLICY MAINTAINED HERE // 1372// // 1373//////////////////////////////////////// 1374template <class Impl> 1375ThreadID 1376DefaultCommit<Impl>::getCommittingThread() 1377{ 1378 if (numThreads > 1) { 1379 switch (commitPolicy) { 1380 1381 case Aggressive: 1382 //If Policy is Aggressive, commit will call 1383 //this function multiple times per 1384 //cycle 1385 return oldestReady(); 1386 1387 case RoundRobin: 1388 return roundRobin(); 1389 1390 case OldestReady: 1391 return oldestReady(); 1392 1393 default: 1394 return InvalidThreadID; 1395 } 1396 } else { 1397 assert(!activeThreads->empty()); 1398 ThreadID tid = activeThreads->front(); 1399 1400 if (commitStatus[tid] == Running || 1401 commitStatus[tid] == Idle || 1402 commitStatus[tid] == FetchTrapPending) { 1403 return tid; 1404 } else { 1405 return InvalidThreadID; 1406 } 1407 } 1408} 1409 1410template<class Impl> 1411ThreadID 1412DefaultCommit<Impl>::roundRobin() 1413{ 1414 list<ThreadID>::iterator pri_iter = priority_list.begin(); 1415 list<ThreadID>::iterator end = priority_list.end(); 1416 1417 while (pri_iter != end) { 1418 ThreadID tid = *pri_iter; 1419 1420 if (commitStatus[tid] == Running || 1421 commitStatus[tid] == Idle || 1422 commitStatus[tid] == FetchTrapPending) { 1423 1424 if (rob->isHeadReady(tid)) { 1425 priority_list.erase(pri_iter); 1426 priority_list.push_back(tid); 1427 1428 return tid; 1429 } 1430 } 1431 1432 pri_iter++; 1433 } 1434 1435 return InvalidThreadID; 1436} 1437 1438template<class Impl> 1439ThreadID 1440DefaultCommit<Impl>::oldestReady() 1441{ 1442 unsigned oldest = 0; 1443 bool first = true; 1444 1445 list<ThreadID>::iterator threads = activeThreads->begin(); 1446 list<ThreadID>::iterator end = activeThreads->end(); 1447 1448 while (threads != end) { 1449 ThreadID tid = *threads++; 1450 1451 if (!rob->isEmpty(tid) && 1452 (commitStatus[tid] == Running || 1453 commitStatus[tid] == Idle || 1454 commitStatus[tid] == FetchTrapPending)) { 1455 1456 if (rob->isHeadReady(tid)) { 1457 1458 DynInstPtr head_inst = rob->readHeadInst(tid); 1459 1460 if (first) { 1461 oldest = tid; 1462 first = false; 1463 } else if (head_inst->seqNum < oldest) { 1464 oldest = tid; 1465 } 1466 } 1467 } 1468 } 1469 1470 if (!first) { 1471 return oldest; 1472 } else { 1473 return InvalidThreadID; 1474 } 1475} 1476