commit_impl.hh revision 3957
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 * Korey Sewell 30 */ 31 32#include "config/full_system.hh" 33#include "config/use_checker.hh" 34 35#include <algorithm> 36#include <string> 37 38#include "arch/utility.hh" 39#include "base/loader/symtab.hh" 40#include "base/timebuf.hh" 41#include "cpu/exetrace.hh" 42#include "cpu/o3/commit.hh" 43#include "cpu/o3/thread_state.hh" 44 45#if USE_CHECKER 46#include "cpu/checker/cpu.hh" 47#endif 48 49template <class Impl> 50DefaultCommit<Impl>::TrapEvent::TrapEvent(DefaultCommit<Impl> *_commit, 51 unsigned _tid) 52 : Event(&mainEventQueue, CPU_Tick_Pri), commit(_commit), tid(_tid) 53{ 54 this->setFlags(Event::AutoDelete); 55} 56 57template <class Impl> 58void 59DefaultCommit<Impl>::TrapEvent::process() 60{ 61 // This will get reset by commit if it was switched out at the 62 // time of this event processing. 63 commit->trapSquash[tid] = true; 64} 65 66template <class Impl> 67const char * 68DefaultCommit<Impl>::TrapEvent::description() 69{ 70 return "Trap event"; 71} 72 73template <class Impl> 74DefaultCommit<Impl>::DefaultCommit(Params *params) 75 : squashCounter(0), 76 iewToCommitDelay(params->iewToCommitDelay), 77 commitToIEWDelay(params->commitToIEWDelay), 78 renameToROBDelay(params->renameToROBDelay), 79 fetchToCommitDelay(params->commitToFetchDelay), 80 renameWidth(params->renameWidth), 81 commitWidth(params->commitWidth), 82 numThreads(params->numberOfThreads), 83 drainPending(false), 84 switchedOut(false), 85 trapLatency(params->trapLatency) 86{ 87 _status = Active; 88 _nextStatus = Inactive; 89 std::string policy = params->smtCommitPolicy; 90 91 //Convert string to lowercase 92 std::transform(policy.begin(), policy.end(), policy.begin(), 93 (int(*)(int)) tolower); 94 95 //Assign commit policy 96 if (policy == "aggressive"){ 97 commitPolicy = Aggressive; 98 99 DPRINTF(Commit,"Commit Policy set to Aggressive."); 100 } else if (policy == "roundrobin"){ 101 commitPolicy = RoundRobin; 102 103 //Set-Up Priority List 104 for (int tid=0; tid < numThreads; tid++) { 105 priority_list.push_back(tid); 106 } 107 108 DPRINTF(Commit,"Commit Policy set to Round Robin."); 109 } else if (policy == "oldestready"){ 110 commitPolicy = OldestReady; 111 112 DPRINTF(Commit,"Commit Policy set to Oldest Ready."); 113 } else { 114 assert(0 && "Invalid SMT Commit Policy. Options Are: {Aggressive," 115 "RoundRobin,OldestReady}"); 116 } 117 118 for (int i=0; i < numThreads; i++) { 119 commitStatus[i] = Idle; 120 changedROBNumEntries[i] = false; 121 trapSquash[i] = false; 122 tcSquash[i] = false; 123 PC[i] = nextPC[i] = nextNPC[i] = 0; 124 } 125#if FULL_SYSTEM 126 interrupt = NoFault; 127#endif 128} 129 130template <class Impl> 131std::string 132DefaultCommit<Impl>::name() const 133{ 134 return cpu->name() + ".commit"; 135} 136 137template <class Impl> 138void 139DefaultCommit<Impl>::regStats() 140{ 141 using namespace Stats; 142 commitCommittedInsts 143 .name(name() + ".commitCommittedInsts") 144 .desc("The number of committed instructions") 145 .prereq(commitCommittedInsts); 146 commitSquashedInsts 147 .name(name() + ".commitSquashedInsts") 148 .desc("The number of squashed insts skipped by commit") 149 .prereq(commitSquashedInsts); 150 commitSquashEvents 151 .name(name() + ".commitSquashEvents") 152 .desc("The number of times commit is told to squash") 153 .prereq(commitSquashEvents); 154 commitNonSpecStalls 155 .name(name() + ".commitNonSpecStalls") 156 .desc("The number of times commit has been forced to stall to " 157 "communicate backwards") 158 .prereq(commitNonSpecStalls); 159 branchMispredicts 160 .name(name() + ".branchMispredicts") 161 .desc("The number of times a branch was mispredicted") 162 .prereq(branchMispredicts); 163 numCommittedDist 164 .init(0,commitWidth,1) 165 .name(name() + ".COM:committed_per_cycle") 166 .desc("Number of insts commited each cycle") 167 .flags(Stats::pdf) 168 ; 169 170 statComInst 171 .init(cpu->number_of_threads) 172 .name(name() + ".COM:count") 173 .desc("Number of instructions committed") 174 .flags(total) 175 ; 176 177 statComSwp 178 .init(cpu->number_of_threads) 179 .name(name() + ".COM:swp_count") 180 .desc("Number of s/w prefetches committed") 181 .flags(total) 182 ; 183 184 statComRefs 185 .init(cpu->number_of_threads) 186 .name(name() + ".COM:refs") 187 .desc("Number of memory references committed") 188 .flags(total) 189 ; 190 191 statComLoads 192 .init(cpu->number_of_threads) 193 .name(name() + ".COM:loads") 194 .desc("Number of loads committed") 195 .flags(total) 196 ; 197 198 statComMembars 199 .init(cpu->number_of_threads) 200 .name(name() + ".COM:membars") 201 .desc("Number of memory barriers committed") 202 .flags(total) 203 ; 204 205 statComBranches 206 .init(cpu->number_of_threads) 207 .name(name() + ".COM:branches") 208 .desc("Number of branches committed") 209 .flags(total) 210 ; 211 212 commitEligible 213 .init(cpu->number_of_threads) 214 .name(name() + ".COM:bw_limited") 215 .desc("number of insts not committed due to BW limits") 216 .flags(total) 217 ; 218 219 commitEligibleSamples 220 .name(name() + ".COM:bw_lim_events") 221 .desc("number cycles where commit BW limit reached") 222 ; 223} 224 225template <class Impl> 226void 227DefaultCommit<Impl>::setCPU(O3CPU *cpu_ptr) 228{ 229 DPRINTF(Commit, "Commit: Setting CPU pointer.\n"); 230 cpu = cpu_ptr; 231 232 // Commit must broadcast the number of free entries it has at the start of 233 // the simulation, so it starts as active. 234 cpu->activateStage(O3CPU::CommitIdx); 235 236 trapLatency = cpu->cycles(trapLatency); 237} 238 239template <class Impl> 240void 241DefaultCommit<Impl>::setThreads(std::vector<Thread *> &threads) 242{ 243 thread = threads; 244} 245 246template <class Impl> 247void 248DefaultCommit<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr) 249{ 250 DPRINTF(Commit, "Commit: Setting time buffer pointer.\n"); 251 timeBuffer = tb_ptr; 252 253 // Setup wire to send information back to IEW. 254 toIEW = timeBuffer->getWire(0); 255 256 // Setup wire to read data from IEW (for the ROB). 257 robInfoFromIEW = timeBuffer->getWire(-iewToCommitDelay); 258} 259 260template <class Impl> 261void 262DefaultCommit<Impl>::setFetchQueue(TimeBuffer<FetchStruct> *fq_ptr) 263{ 264 DPRINTF(Commit, "Commit: Setting fetch queue pointer.\n"); 265 fetchQueue = fq_ptr; 266 267 // Setup wire to get instructions from rename (for the ROB). 268 fromFetch = fetchQueue->getWire(-fetchToCommitDelay); 269} 270 271template <class Impl> 272void 273DefaultCommit<Impl>::setRenameQueue(TimeBuffer<RenameStruct> *rq_ptr) 274{ 275 DPRINTF(Commit, "Commit: Setting rename queue pointer.\n"); 276 renameQueue = rq_ptr; 277 278 // Setup wire to get instructions from rename (for the ROB). 279 fromRename = renameQueue->getWire(-renameToROBDelay); 280} 281 282template <class Impl> 283void 284DefaultCommit<Impl>::setIEWQueue(TimeBuffer<IEWStruct> *iq_ptr) 285{ 286 DPRINTF(Commit, "Commit: Setting IEW queue pointer.\n"); 287 iewQueue = iq_ptr; 288 289 // Setup wire to get instructions from IEW. 290 fromIEW = iewQueue->getWire(-iewToCommitDelay); 291} 292 293template <class Impl> 294void 295DefaultCommit<Impl>::setIEWStage(IEW *iew_stage) 296{ 297 iewStage = iew_stage; 298} 299 300template<class Impl> 301void 302DefaultCommit<Impl>::setActiveThreads(std::list<unsigned> *at_ptr) 303{ 304 DPRINTF(Commit, "Commit: Setting active threads list pointer.\n"); 305 activeThreads = at_ptr; 306} 307 308template <class Impl> 309void 310DefaultCommit<Impl>::setRenameMap(RenameMap rm_ptr[]) 311{ 312 DPRINTF(Commit, "Setting rename map pointers.\n"); 313 314 for (int i=0; i < numThreads; i++) { 315 renameMap[i] = &rm_ptr[i]; 316 } 317} 318 319template <class Impl> 320void 321DefaultCommit<Impl>::setROB(ROB *rob_ptr) 322{ 323 DPRINTF(Commit, "Commit: Setting ROB pointer.\n"); 324 rob = rob_ptr; 325} 326 327template <class Impl> 328void 329DefaultCommit<Impl>::initStage() 330{ 331 rob->setActiveThreads(activeThreads); 332 rob->resetEntries(); 333 334 // Broadcast the number of free entries. 335 for (int i=0; i < numThreads; i++) { 336 toIEW->commitInfo[i].usedROB = true; 337 toIEW->commitInfo[i].freeROBEntries = rob->numFreeEntries(i); 338 } 339 340 cpu->activityThisCycle(); 341} 342 343template <class Impl> 344bool 345DefaultCommit<Impl>::drain() 346{ 347 drainPending = true; 348 349 return false; 350} 351 352template <class Impl> 353void 354DefaultCommit<Impl>::switchOut() 355{ 356 switchedOut = true; 357 drainPending = false; 358 rob->switchOut(); 359} 360 361template <class Impl> 362void 363DefaultCommit<Impl>::resume() 364{ 365 drainPending = false; 366} 367 368template <class Impl> 369void 370DefaultCommit<Impl>::takeOverFrom() 371{ 372 switchedOut = false; 373 _status = Active; 374 _nextStatus = Inactive; 375 for (int i=0; i < numThreads; i++) { 376 commitStatus[i] = Idle; 377 changedROBNumEntries[i] = false; 378 trapSquash[i] = false; 379 tcSquash[i] = false; 380 } 381 squashCounter = 0; 382 rob->takeOverFrom(); 383} 384 385template <class Impl> 386void 387DefaultCommit<Impl>::updateStatus() 388{ 389 // reset ROB changed variable 390 std::list<unsigned>::iterator threads = (*activeThreads).begin(); 391 while (threads != (*activeThreads).end()) { 392 unsigned tid = *threads++; 393 changedROBNumEntries[tid] = false; 394 395 // Also check if any of the threads has a trap pending 396 if (commitStatus[tid] == TrapPending || 397 commitStatus[tid] == FetchTrapPending) { 398 _nextStatus = Active; 399 } 400 } 401 402 if (_nextStatus == Inactive && _status == Active) { 403 DPRINTF(Activity, "Deactivating stage.\n"); 404 cpu->deactivateStage(O3CPU::CommitIdx); 405 } else if (_nextStatus == Active && _status == Inactive) { 406 DPRINTF(Activity, "Activating stage.\n"); 407 cpu->activateStage(O3CPU::CommitIdx); 408 } 409 410 _status = _nextStatus; 411} 412 413template <class Impl> 414void 415DefaultCommit<Impl>::setNextStatus() 416{ 417 int squashes = 0; 418 419 std::list<unsigned>::iterator threads = (*activeThreads).begin(); 420 421 while (threads != (*activeThreads).end()) { 422 unsigned tid = *threads++; 423 424 if (commitStatus[tid] == ROBSquashing) { 425 squashes++; 426 } 427 } 428 429 squashCounter = squashes; 430 431 // If commit is currently squashing, then it will have activity for the 432 // next cycle. Set its next status as active. 433 if (squashCounter) { 434 _nextStatus = Active; 435 } 436} 437 438template <class Impl> 439bool 440DefaultCommit<Impl>::changedROBEntries() 441{ 442 std::list<unsigned>::iterator threads = (*activeThreads).begin(); 443 444 while (threads != (*activeThreads).end()) { 445 unsigned tid = *threads++; 446 447 if (changedROBNumEntries[tid]) { 448 return true; 449 } 450 } 451 452 return false; 453} 454 455template <class Impl> 456unsigned 457DefaultCommit<Impl>::numROBFreeEntries(unsigned tid) 458{ 459 return rob->numFreeEntries(tid); 460} 461 462template <class Impl> 463void 464DefaultCommit<Impl>::generateTrapEvent(unsigned tid) 465{ 466 DPRINTF(Commit, "Generating trap event for [tid:%i]\n", tid); 467 468 TrapEvent *trap = new TrapEvent(this, tid); 469 470 trap->schedule(curTick + trapLatency); 471 472 thread[tid]->trapPending = true; 473} 474 475template <class Impl> 476void 477DefaultCommit<Impl>::generateTCEvent(unsigned tid) 478{ 479 DPRINTF(Commit, "Generating TC squash event for [tid:%i]\n", tid); 480 481 tcSquash[tid] = true; 482} 483 484template <class Impl> 485void 486DefaultCommit<Impl>::squashAll(unsigned tid) 487{ 488 // If we want to include the squashing instruction in the squash, 489 // then use one older sequence number. 490 // Hopefully this doesn't mess things up. Basically I want to squash 491 // all instructions of this thread. 492 InstSeqNum squashed_inst = rob->isEmpty() ? 493 0 : rob->readHeadInst(tid)->seqNum - 1;; 494 495 // All younger instructions will be squashed. Set the sequence 496 // number as the youngest instruction in the ROB (0 in this case. 497 // Hopefully nothing breaks.) 498 youngestSeqNum[tid] = 0; 499 500 rob->squash(squashed_inst, tid); 501 changedROBNumEntries[tid] = true; 502 503 // Send back the sequence number of the squashed instruction. 504 toIEW->commitInfo[tid].doneSeqNum = squashed_inst; 505 506 // Send back the squash signal to tell stages that they should 507 // squash. 508 toIEW->commitInfo[tid].squash = true; 509 510 // Send back the rob squashing signal so other stages know that 511 // the ROB is in the process of squashing. 512 toIEW->commitInfo[tid].robSquashing = true; 513 514 toIEW->commitInfo[tid].branchMispredict = false; 515 516 toIEW->commitInfo[tid].nextPC = PC[tid]; 517 toIEW->commitInfo[tid].nextNPC = nextPC[tid]; 518} 519 520template <class Impl> 521void 522DefaultCommit<Impl>::squashFromTrap(unsigned tid) 523{ 524 squashAll(tid); 525 526 DPRINTF(Commit, "Squashing from trap, restarting at PC %#x\n", PC[tid]); 527 528 thread[tid]->trapPending = false; 529 thread[tid]->inSyscall = false; 530 531 trapSquash[tid] = false; 532 533 commitStatus[tid] = ROBSquashing; 534 cpu->activityThisCycle(); 535} 536 537template <class Impl> 538void 539DefaultCommit<Impl>::squashFromTC(unsigned tid) 540{ 541 squashAll(tid); 542 543 DPRINTF(Commit, "Squashing from TC, restarting at PC %#x\n", PC[tid]); 544 545 thread[tid]->inSyscall = false; 546 assert(!thread[tid]->trapPending); 547 548 commitStatus[tid] = ROBSquashing; 549 cpu->activityThisCycle(); 550 551 tcSquash[tid] = false; 552} 553 554template <class Impl> 555void 556DefaultCommit<Impl>::tick() 557{ 558 wroteToTimeBuffer = false; 559 _nextStatus = Inactive; 560 561 if (drainPending && rob->isEmpty() && !iewStage->hasStoresToWB()) { 562 cpu->signalDrained(); 563 drainPending = false; 564 return; 565 } 566 567 if ((*activeThreads).size() <= 0) 568 return; 569 570 std::list<unsigned>::iterator threads = (*activeThreads).begin(); 571 572 // Check if any of the threads are done squashing. Change the 573 // status if they are done. 574 while (threads != (*activeThreads).end()) { 575 unsigned tid = *threads++; 576 577 if (commitStatus[tid] == ROBSquashing) { 578 579 if (rob->isDoneSquashing(tid)) { 580 commitStatus[tid] = Running; 581 } else { 582 DPRINTF(Commit,"[tid:%u]: Still Squashing, cannot commit any" 583 " insts this cycle.\n", tid); 584 rob->doSquash(tid); 585 toIEW->commitInfo[tid].robSquashing = true; 586 wroteToTimeBuffer = true; 587 } 588 } 589 } 590 591 commit(); 592 593 markCompletedInsts(); 594 595 threads = (*activeThreads).begin(); 596 597 while (threads != (*activeThreads).end()) { 598 unsigned tid = *threads++; 599 600 if (!rob->isEmpty(tid) && rob->readHeadInst(tid)->readyToCommit()) { 601 // The ROB has more instructions it can commit. Its next status 602 // will be active. 603 _nextStatus = Active; 604 605 DynInstPtr inst = rob->readHeadInst(tid); 606 607 DPRINTF(Commit,"[tid:%i]: Instruction [sn:%lli] PC %#x is head of" 608 " ROB and ready to commit\n", 609 tid, inst->seqNum, inst->readPC()); 610 611 } else if (!rob->isEmpty(tid)) { 612 DynInstPtr inst = rob->readHeadInst(tid); 613 614 DPRINTF(Commit,"[tid:%i]: Can't commit, Instruction [sn:%lli] PC " 615 "%#x is head of ROB and not ready\n", 616 tid, inst->seqNum, inst->readPC()); 617 } 618 619 DPRINTF(Commit, "[tid:%i]: ROB has %d insts & %d free entries.\n", 620 tid, rob->countInsts(tid), rob->numFreeEntries(tid)); 621 } 622 623 624 if (wroteToTimeBuffer) { 625 DPRINTF(Activity, "Activity This Cycle.\n"); 626 cpu->activityThisCycle(); 627 } 628 629 updateStatus(); 630} 631 632template <class Impl> 633void 634DefaultCommit<Impl>::commit() 635{ 636 637 ////////////////////////////////////// 638 // Check for interrupts 639 ////////////////////////////////////// 640 641#if FULL_SYSTEM 642 if (interrupt != NoFault) { 643 // Wait until the ROB is empty and all stores have drained in 644 // order to enter the interrupt. 645 if (rob->isEmpty() && !iewStage->hasStoresToWB()) { 646 // Squash or record that I need to squash this cycle if 647 // an interrupt needed to be handled. 648 DPRINTF(Commit, "Interrupt detected.\n"); 649 650 assert(!thread[0]->inSyscall); 651 thread[0]->inSyscall = true; 652 653 // CPU will handle interrupt. 654 cpu->processInterrupts(interrupt); 655 656 thread[0]->inSyscall = false; 657 658 commitStatus[0] = TrapPending; 659 660 // Generate trap squash event. 661 generateTrapEvent(0); 662 663 // Clear the interrupt now that it's been handled 664 toIEW->commitInfo[0].clearInterrupt = true; 665 interrupt = NoFault; 666 } else { 667 DPRINTF(Commit, "Interrupt pending, waiting for ROB to empty.\n"); 668 } 669 } else if (cpu->checkInterrupts && 670 cpu->check_interrupts(cpu->tcBase(0)) && 671 commitStatus[0] != TrapPending && 672 !trapSquash[0] && 673 !tcSquash[0]) { 674 // Process interrupts if interrupts are enabled, not in PAL 675 // mode, and no other traps or external squashes are currently 676 // pending. 677 // @todo: Allow other threads to handle interrupts. 678 679 // Get any interrupt that happened 680 interrupt = cpu->getInterrupts(); 681 682 if (interrupt != NoFault) { 683 // Tell fetch that there is an interrupt pending. This 684 // will make fetch wait until it sees a non PAL-mode PC, 685 // at which point it stops fetching instructions. 686 toIEW->commitInfo[0].interruptPending = true; 687 } 688 } 689 690#endif // FULL_SYSTEM 691 692 //////////////////////////////////// 693 // Check for any possible squashes, handle them first 694 //////////////////////////////////// 695 std::list<unsigned>::iterator threads = (*activeThreads).begin(); 696 697 while (threads != (*activeThreads).end()) { 698 unsigned tid = *threads++; 699 700 // Not sure which one takes priority. I think if we have 701 // both, that's a bad sign. 702 if (trapSquash[tid] == true) { 703 assert(!tcSquash[tid]); 704 squashFromTrap(tid); 705 } else if (tcSquash[tid] == true) { 706 squashFromTC(tid); 707 } 708 709 // Squashed sequence number must be older than youngest valid 710 // instruction in the ROB. This prevents squashes from younger 711 // instructions overriding squashes from older instructions. 712 if (fromIEW->squash[tid] && 713 commitStatus[tid] != TrapPending && 714 fromIEW->squashedSeqNum[tid] <= youngestSeqNum[tid]) { 715 716 DPRINTF(Commit, "[tid:%i]: Squashing due to PC %#x [sn:%i]\n", 717 tid, 718 fromIEW->mispredPC[tid], 719 fromIEW->squashedSeqNum[tid]); 720 721 DPRINTF(Commit, "[tid:%i]: Redirecting to PC %#x\n", 722 tid, 723 fromIEW->nextPC[tid]); 724 725 commitStatus[tid] = ROBSquashing; 726 727 // If we want to include the squashing instruction in the squash, 728 // then use one older sequence number. 729 InstSeqNum squashed_inst = fromIEW->squashedSeqNum[tid]; 730 731#if ISA_HAS_DELAY_SLOT 732 InstSeqNum bdelay_done_seq_num = squashed_inst; 733 bool squash_bdelay_slot = fromIEW->squashDelaySlot[tid]; 734 bool branchMispredict = fromIEW->branchMispredict[tid]; 735 736 // Squashing/not squashing the branch delay slot only makes 737 // sense when you're squashing from a branch, ie from a branch 738 // mispredict. 739 if (branchMispredict && !squash_bdelay_slot) { 740 bdelay_done_seq_num++; 741 } 742#endif 743 744 if (fromIEW->includeSquashInst[tid] == true) { 745 squashed_inst--; 746#if ISA_HAS_DELAY_SLOT 747 bdelay_done_seq_num--; 748#endif 749 } 750 // All younger instructions will be squashed. Set the sequence 751 // number as the youngest instruction in the ROB. 752 youngestSeqNum[tid] = squashed_inst; 753 754#if ISA_HAS_DELAY_SLOT 755 rob->squash(bdelay_done_seq_num, tid); 756 toIEW->commitInfo[tid].squashDelaySlot = squash_bdelay_slot; 757 toIEW->commitInfo[tid].bdelayDoneSeqNum = bdelay_done_seq_num; 758#else 759 rob->squash(squashed_inst, tid); 760 toIEW->commitInfo[tid].squashDelaySlot = true; 761#endif 762 changedROBNumEntries[tid] = true; 763 764 toIEW->commitInfo[tid].doneSeqNum = squashed_inst; 765 766 toIEW->commitInfo[tid].squash = true; 767 768 // Send back the rob squashing signal so other stages know that 769 // the ROB is in the process of squashing. 770 toIEW->commitInfo[tid].robSquashing = true; 771 772 toIEW->commitInfo[tid].branchMispredict = 773 fromIEW->branchMispredict[tid]; 774 775 toIEW->commitInfo[tid].branchTaken = 776 fromIEW->branchTaken[tid]; 777 778 toIEW->commitInfo[tid].nextPC = fromIEW->nextPC[tid]; 779 toIEW->commitInfo[tid].nextNPC = fromIEW->nextNPC[tid]; 780 781 toIEW->commitInfo[tid].mispredPC = fromIEW->mispredPC[tid]; 782 783 if (toIEW->commitInfo[tid].branchMispredict) { 784 ++branchMispredicts; 785 } 786 } 787 788 } 789 790 setNextStatus(); 791 792 if (squashCounter != numThreads) { 793 // If we're not currently squashing, then get instructions. 794 getInsts(); 795 796 // Try to commit any instructions. 797 commitInsts(); 798 } else { 799#if ISA_HAS_DELAY_SLOT 800 skidInsert(); 801#endif 802 } 803 804 //Check for any activity 805 threads = (*activeThreads).begin(); 806 807 while (threads != (*activeThreads).end()) { 808 unsigned tid = *threads++; 809 810 if (changedROBNumEntries[tid]) { 811 toIEW->commitInfo[tid].usedROB = true; 812 toIEW->commitInfo[tid].freeROBEntries = rob->numFreeEntries(tid); 813 814 if (rob->isEmpty(tid)) { 815 toIEW->commitInfo[tid].emptyROB = true; 816 } 817 818 wroteToTimeBuffer = true; 819 changedROBNumEntries[tid] = false; 820 } 821 } 822} 823 824template <class Impl> 825void 826DefaultCommit<Impl>::commitInsts() 827{ 828 //////////////////////////////////// 829 // Handle commit 830 // Note that commit will be handled prior to putting new 831 // instructions in the ROB so that the ROB only tries to commit 832 // instructions it has in this current cycle, and not instructions 833 // it is writing in during this cycle. Can't commit and squash 834 // things at the same time... 835 //////////////////////////////////// 836 837 DPRINTF(Commit, "Trying to commit instructions in the ROB.\n"); 838 839 unsigned num_committed = 0; 840 841 DynInstPtr head_inst; 842 843 // Commit as many instructions as possible until the commit bandwidth 844 // limit is reached, or it becomes impossible to commit any more. 845 while (num_committed < commitWidth) { 846 int commit_thread = getCommittingThread(); 847 848 if (commit_thread == -1 || !rob->isHeadReady(commit_thread)) 849 break; 850 851 head_inst = rob->readHeadInst(commit_thread); 852 853 int tid = head_inst->threadNumber; 854 855 assert(tid == commit_thread); 856 857 DPRINTF(Commit, "Trying to commit head instruction, [sn:%i] [tid:%i]\n", 858 head_inst->seqNum, tid); 859 860 // If the head instruction is squashed, it is ready to retire 861 // (be removed from the ROB) at any time. 862 if (head_inst->isSquashed()) { 863 864 DPRINTF(Commit, "Retiring squashed instruction from " 865 "ROB.\n"); 866 867 rob->retireHead(commit_thread); 868 869 ++commitSquashedInsts; 870 871 // Record that the number of ROB entries has changed. 872 changedROBNumEntries[tid] = true; 873 } else { 874 PC[tid] = head_inst->readPC(); 875 nextPC[tid] = head_inst->readNextPC(); 876 nextNPC[tid] = head_inst->readNextNPC(); 877 878 // Increment the total number of non-speculative instructions 879 // executed. 880 // Hack for now: it really shouldn't happen until after the 881 // commit is deemed to be successful, but this count is needed 882 // for syscalls. 883 thread[tid]->funcExeInst++; 884 885 // Try to commit the head instruction. 886 bool commit_success = commitHead(head_inst, num_committed); 887 888 if (commit_success) { 889 ++num_committed; 890 891 changedROBNumEntries[tid] = true; 892 893 // Set the doneSeqNum to the youngest committed instruction. 894 toIEW->commitInfo[tid].doneSeqNum = head_inst->seqNum; 895 896 ++commitCommittedInsts; 897 898 // To match the old model, don't count nops and instruction 899 // prefetches towards the total commit count. 900 if (!head_inst->isNop() && !head_inst->isInstPrefetch()) { 901 cpu->instDone(tid); 902 } 903 904 PC[tid] = nextPC[tid]; 905#if ISA_HAS_DELAY_SLOT 906 nextPC[tid] = nextNPC[tid]; 907 nextNPC[tid] = nextNPC[tid] + sizeof(TheISA::MachInst); 908#else 909 nextPC[tid] = nextPC[tid] + sizeof(TheISA::MachInst); 910#endif 911 912#if FULL_SYSTEM 913 int count = 0; 914 Addr oldpc; 915 do { 916 // Debug statement. Checks to make sure we're not 917 // currently updating state while handling PC events. 918 if (count == 0) 919 assert(!thread[tid]->inSyscall && 920 !thread[tid]->trapPending); 921 oldpc = PC[tid]; 922 cpu->system->pcEventQueue.service( 923 thread[tid]->getTC()); 924 count++; 925 } while (oldpc != PC[tid]); 926 if (count > 1) { 927 DPRINTF(Commit, "PC skip function event, stopping commit\n"); 928 break; 929 } 930#endif 931 } else { 932 DPRINTF(Commit, "Unable to commit head instruction PC:%#x " 933 "[tid:%i] [sn:%i].\n", 934 head_inst->readPC(), tid ,head_inst->seqNum); 935 break; 936 } 937 } 938 } 939 940 DPRINTF(CommitRate, "%i\n", num_committed); 941 numCommittedDist.sample(num_committed); 942 943 if (num_committed == commitWidth) { 944 commitEligibleSamples++; 945 } 946} 947 948template <class Impl> 949bool 950DefaultCommit<Impl>::commitHead(DynInstPtr &head_inst, unsigned inst_num) 951{ 952 assert(head_inst); 953 954 int tid = head_inst->threadNumber; 955 956 // If the instruction is not executed yet, then it will need extra 957 // handling. Signal backwards that it should be executed. 958 if (!head_inst->isExecuted()) { 959 // Keep this number correct. We have not yet actually executed 960 // and committed this instruction. 961 thread[tid]->funcExeInst--; 962 963 head_inst->setAtCommit(); 964 965 if (head_inst->isNonSpeculative() || 966 head_inst->isStoreConditional() || 967 head_inst->isMemBarrier() || 968 head_inst->isWriteBarrier()) { 969 970 DPRINTF(Commit, "Encountered a barrier or non-speculative " 971 "instruction [sn:%lli] at the head of the ROB, PC %#x.\n", 972 head_inst->seqNum, head_inst->readPC()); 973 974#if !FULL_SYSTEM 975 // Hack to make sure syscalls/memory barriers/quiesces 976 // aren't executed until all stores write back their data. 977 // This direct communication shouldn't be used for 978 // anything other than this. 979 if (inst_num > 0 || iewStage->hasStoresToWB()) 980#else 981 if ((head_inst->isMemBarrier() || head_inst->isWriteBarrier() || 982 head_inst->isQuiesce()) && 983 iewStage->hasStoresToWB()) 984#endif 985 { 986 DPRINTF(Commit, "Waiting for all stores to writeback.\n"); 987 return false; 988 } 989 990 toIEW->commitInfo[tid].nonSpecSeqNum = head_inst->seqNum; 991 992 // Change the instruction so it won't try to commit again until 993 // it is executed. 994 head_inst->clearCanCommit(); 995 996 ++commitNonSpecStalls; 997 998 return false; 999 } else if (head_inst->isLoad()) { 1000 DPRINTF(Commit, "[sn:%lli]: Uncached load, PC %#x.\n", 1001 head_inst->seqNum, head_inst->readPC()); 1002 1003 // Send back the non-speculative instruction's sequence 1004 // number. Tell the lsq to re-execute the load. 1005 toIEW->commitInfo[tid].nonSpecSeqNum = head_inst->seqNum; 1006 toIEW->commitInfo[tid].uncached = true; 1007 toIEW->commitInfo[tid].uncachedLoad = head_inst; 1008 1009 head_inst->clearCanCommit(); 1010 1011 return false; 1012 } else { 1013 panic("Trying to commit un-executed instruction " 1014 "of unknown type!\n"); 1015 } 1016 } 1017 1018 if (head_inst->isThreadSync()) { 1019 // Not handled for now. 1020 panic("Thread sync instructions are not handled yet.\n"); 1021 } 1022 1023 // Stores mark themselves as completed. 1024 if (!head_inst->isStore()) { 1025 head_inst->setCompleted(); 1026 } 1027 1028#if USE_CHECKER 1029 // Use checker prior to updating anything due to traps or PC 1030 // based events. 1031 if (cpu->checker) { 1032 cpu->checker->verify(head_inst); 1033 } 1034#endif 1035 1036 // Check if the instruction caused a fault. If so, trap. 1037 Fault inst_fault = head_inst->getFault(); 1038 1039 // DTB will sometimes need the machine instruction for when 1040 // faults happen. So we will set it here, prior to the DTB 1041 // possibly needing it for its fault. 1042 thread[tid]->setInst( 1043 static_cast<TheISA::MachInst>(head_inst->staticInst->machInst)); 1044 1045 if (inst_fault != NoFault) { 1046 head_inst->setCompleted(); 1047 DPRINTF(Commit, "Inst [sn:%lli] PC %#x has a fault\n", 1048 head_inst->seqNum, head_inst->readPC()); 1049 1050 if (iewStage->hasStoresToWB() || inst_num > 0) { 1051 DPRINTF(Commit, "Stores outstanding, fault must wait.\n"); 1052 return false; 1053 } 1054 1055#if USE_CHECKER 1056 if (cpu->checker && head_inst->isStore()) { 1057 cpu->checker->verify(head_inst); 1058 } 1059#endif 1060 1061 assert(!thread[tid]->inSyscall); 1062 1063 // Mark that we're in state update mode so that the trap's 1064 // execution doesn't generate extra squashes. 1065 thread[tid]->inSyscall = true; 1066 1067 // Execute the trap. Although it's slightly unrealistic in 1068 // terms of timing (as it doesn't wait for the full timing of 1069 // the trap event to complete before updating state), it's 1070 // needed to update the state as soon as possible. This 1071 // prevents external agents from changing any specific state 1072 // that the trap need. 1073 cpu->trap(inst_fault, tid); 1074 1075 // Exit state update mode to avoid accidental updating. 1076 thread[tid]->inSyscall = false; 1077 1078 commitStatus[tid] = TrapPending; 1079 1080 // Generate trap squash event. 1081 generateTrapEvent(tid); 1082// warn("%lli fault (%d) handled @ PC %08p", curTick, inst_fault->name(), head_inst->readPC()); 1083 return false; 1084 } 1085 1086 updateComInstStats(head_inst); 1087 1088#if FULL_SYSTEM 1089 if (thread[tid]->profile) { 1090// bool usermode = TheISA::inUserMode(thread[tid]->getTC()); 1091// thread[tid]->profilePC = usermode ? 1 : head_inst->readPC(); 1092 thread[tid]->profilePC = head_inst->readPC(); 1093 ProfileNode *node = thread[tid]->profile->consume(thread[tid]->getTC(), 1094 head_inst->staticInst); 1095 1096 if (node) 1097 thread[tid]->profileNode = node; 1098 } 1099#endif 1100 1101 if (head_inst->traceData) { 1102 head_inst->traceData->setFetchSeq(head_inst->seqNum); 1103 head_inst->traceData->setCPSeq(thread[tid]->numInst); 1104 head_inst->traceData->finalize(); 1105 head_inst->traceData = NULL; 1106 } 1107 1108 // Update the commit rename map 1109 for (int i = 0; i < head_inst->numDestRegs(); i++) { 1110 renameMap[tid]->setEntry(head_inst->flattenedDestRegIdx(i), 1111 head_inst->renamedDestRegIdx(i)); 1112 } 1113 1114 if (head_inst->isCopy()) 1115 panic("Should not commit any copy instructions!"); 1116 1117 // Finally clear the head ROB entry. 1118 rob->retireHead(tid); 1119 1120 // Return true to indicate that we have committed an instruction. 1121 return true; 1122} 1123 1124template <class Impl> 1125void 1126DefaultCommit<Impl>::getInsts() 1127{ 1128 DPRINTF(Commit, "Getting instructions from Rename stage.\n"); 1129 1130#if ISA_HAS_DELAY_SLOT 1131 // Read any renamed instructions and place them into the ROB. 1132 int insts_to_process = std::min((int)renameWidth, 1133 (int)(fromRename->size + skidBuffer.size())); 1134 int rename_idx = 0; 1135 1136 DPRINTF(Commit, "%i insts available to process. Rename Insts:%i " 1137 "SkidBuffer Insts:%i\n", insts_to_process, fromRename->size, 1138 skidBuffer.size()); 1139#else 1140 // Read any renamed instructions and place them into the ROB. 1141 int insts_to_process = std::min((int)renameWidth, fromRename->size); 1142#endif 1143 1144 1145 for (int inst_num = 0; inst_num < insts_to_process; ++inst_num) { 1146 DynInstPtr inst; 1147 1148#if ISA_HAS_DELAY_SLOT 1149 // Get insts from skidBuffer or from Rename 1150 if (skidBuffer.size() > 0) { 1151 DPRINTF(Commit, "Grabbing skidbuffer inst.\n"); 1152 inst = skidBuffer.front(); 1153 skidBuffer.pop(); 1154 } else { 1155 DPRINTF(Commit, "Grabbing rename inst.\n"); 1156 inst = fromRename->insts[rename_idx++]; 1157 } 1158#else 1159 inst = fromRename->insts[inst_num]; 1160#endif 1161 int tid = inst->threadNumber; 1162 1163 if (!inst->isSquashed() && 1164 commitStatus[tid] != ROBSquashing) { 1165 changedROBNumEntries[tid] = true; 1166 1167 DPRINTF(Commit, "Inserting PC %#x [sn:%i] [tid:%i] into ROB.\n", 1168 inst->readPC(), inst->seqNum, tid); 1169 1170 rob->insertInst(inst); 1171 1172 assert(rob->getThreadEntries(tid) <= rob->getMaxEntries(tid)); 1173 1174 youngestSeqNum[tid] = inst->seqNum; 1175 } else { 1176 DPRINTF(Commit, "Instruction PC %#x [sn:%i] [tid:%i] was " 1177 "squashed, skipping.\n", 1178 inst->readPC(), inst->seqNum, tid); 1179 } 1180 } 1181 1182#if ISA_HAS_DELAY_SLOT 1183 if (rename_idx < fromRename->size) { 1184 DPRINTF(Commit,"Placing Rename Insts into skidBuffer.\n"); 1185 1186 for (; 1187 rename_idx < fromRename->size; 1188 rename_idx++) { 1189 DynInstPtr inst = fromRename->insts[rename_idx]; 1190 1191 if (!inst->isSquashed()) { 1192 DPRINTF(Commit, "Inserting PC %#x [sn:%i] [tid:%i] into ", 1193 "skidBuffer.\n", inst->readPC(), inst->seqNum, 1194 inst->threadNumber); 1195 skidBuffer.push(inst); 1196 } else { 1197 DPRINTF(Commit, "Instruction PC %#x [sn:%i] [tid:%i] was " 1198 "squashed, skipping.\n", 1199 inst->readPC(), inst->seqNum, inst->threadNumber); 1200 } 1201 } 1202 } 1203#endif 1204 1205} 1206 1207template <class Impl> 1208void 1209DefaultCommit<Impl>::skidInsert() 1210{ 1211 DPRINTF(Commit, "Attempting to any instructions from rename into " 1212 "skidBuffer.\n"); 1213 1214 for (int inst_num = 0; inst_num < fromRename->size; ++inst_num) { 1215 DynInstPtr inst = fromRename->insts[inst_num]; 1216 1217 if (!inst->isSquashed()) { 1218 DPRINTF(Commit, "Inserting PC %#x [sn:%i] [tid:%i] into ", 1219 "skidBuffer.\n", inst->readPC(), inst->seqNum, 1220 inst->threadNumber); 1221 skidBuffer.push(inst); 1222 } else { 1223 DPRINTF(Commit, "Instruction PC %#x [sn:%i] [tid:%i] was " 1224 "squashed, skipping.\n", 1225 inst->readPC(), inst->seqNum, inst->threadNumber); 1226 } 1227 } 1228} 1229 1230template <class Impl> 1231void 1232DefaultCommit<Impl>::markCompletedInsts() 1233{ 1234 // Grab completed insts out of the IEW instruction queue, and mark 1235 // instructions completed within the ROB. 1236 for (int inst_num = 0; 1237 inst_num < fromIEW->size && fromIEW->insts[inst_num]; 1238 ++inst_num) 1239 { 1240 if (!fromIEW->insts[inst_num]->isSquashed()) { 1241 DPRINTF(Commit, "[tid:%i]: Marking PC %#x, [sn:%lli] ready " 1242 "within ROB.\n", 1243 fromIEW->insts[inst_num]->threadNumber, 1244 fromIEW->insts[inst_num]->readPC(), 1245 fromIEW->insts[inst_num]->seqNum); 1246 1247 // Mark the instruction as ready to commit. 1248 fromIEW->insts[inst_num]->setCanCommit(); 1249 } 1250 } 1251} 1252 1253template <class Impl> 1254bool 1255DefaultCommit<Impl>::robDoneSquashing() 1256{ 1257 std::list<unsigned>::iterator threads = (*activeThreads).begin(); 1258 1259 while (threads != (*activeThreads).end()) { 1260 unsigned tid = *threads++; 1261 1262 if (!rob->isDoneSquashing(tid)) 1263 return false; 1264 } 1265 1266 return true; 1267} 1268 1269template <class Impl> 1270void 1271DefaultCommit<Impl>::updateComInstStats(DynInstPtr &inst) 1272{ 1273 unsigned thread = inst->threadNumber; 1274 1275 // 1276 // Pick off the software prefetches 1277 // 1278#ifdef TARGET_ALPHA 1279 if (inst->isDataPrefetch()) { 1280 statComSwp[thread]++; 1281 } else { 1282 statComInst[thread]++; 1283 } 1284#else 1285 statComInst[thread]++; 1286#endif 1287 1288 // 1289 // Control Instructions 1290 // 1291 if (inst->isControl()) 1292 statComBranches[thread]++; 1293 1294 // 1295 // Memory references 1296 // 1297 if (inst->isMemRef()) { 1298 statComRefs[thread]++; 1299 1300 if (inst->isLoad()) { 1301 statComLoads[thread]++; 1302 } 1303 } 1304 1305 if (inst->isMemBarrier()) { 1306 statComMembars[thread]++; 1307 } 1308} 1309 1310//////////////////////////////////////// 1311// // 1312// SMT COMMIT POLICY MAINTAINED HERE // 1313// // 1314//////////////////////////////////////// 1315template <class Impl> 1316int 1317DefaultCommit<Impl>::getCommittingThread() 1318{ 1319 if (numThreads > 1) { 1320 switch (commitPolicy) { 1321 1322 case Aggressive: 1323 //If Policy is Aggressive, commit will call 1324 //this function multiple times per 1325 //cycle 1326 return oldestReady(); 1327 1328 case RoundRobin: 1329 return roundRobin(); 1330 1331 case OldestReady: 1332 return oldestReady(); 1333 1334 default: 1335 return -1; 1336 } 1337 } else { 1338 int tid = (*activeThreads).front(); 1339 1340 if (commitStatus[tid] == Running || 1341 commitStatus[tid] == Idle || 1342 commitStatus[tid] == FetchTrapPending) { 1343 return tid; 1344 } else { 1345 return -1; 1346 } 1347 } 1348} 1349 1350template<class Impl> 1351int 1352DefaultCommit<Impl>::roundRobin() 1353{ 1354 std::list<unsigned>::iterator pri_iter = priority_list.begin(); 1355 std::list<unsigned>::iterator end = priority_list.end(); 1356 1357 while (pri_iter != end) { 1358 unsigned tid = *pri_iter; 1359 1360 if (commitStatus[tid] == Running || 1361 commitStatus[tid] == Idle || 1362 commitStatus[tid] == FetchTrapPending) { 1363 1364 if (rob->isHeadReady(tid)) { 1365 priority_list.erase(pri_iter); 1366 priority_list.push_back(tid); 1367 1368 return tid; 1369 } 1370 } 1371 1372 pri_iter++; 1373 } 1374 1375 return -1; 1376} 1377 1378template<class Impl> 1379int 1380DefaultCommit<Impl>::oldestReady() 1381{ 1382 unsigned oldest = 0; 1383 bool first = true; 1384 1385 std::list<unsigned>::iterator threads = (*activeThreads).begin(); 1386 1387 while (threads != (*activeThreads).end()) { 1388 unsigned tid = *threads++; 1389 1390 if (!rob->isEmpty(tid) && 1391 (commitStatus[tid] == Running || 1392 commitStatus[tid] == Idle || 1393 commitStatus[tid] == FetchTrapPending)) { 1394 1395 if (rob->isHeadReady(tid)) { 1396 1397 DynInstPtr head_inst = rob->readHeadInst(tid); 1398 1399 if (first) { 1400 oldest = tid; 1401 first = false; 1402 } else if (head_inst->seqNum < oldest) { 1403 oldest = tid; 1404 } 1405 } 1406 } 1407 } 1408 1409 if (!first) { 1410 return oldest; 1411 } else { 1412 return -1; 1413 } 1414} 1415