commit_impl.hh revision 5108:3b59ba14a7f3
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"; 71} 72 73template <class Impl> 74DefaultCommit<Impl>::DefaultCommit(O3CPU *_cpu, Params *params) 75 : cpu(_cpu), 76 squashCounter(0), 77 iewToCommitDelay(params->iewToCommitDelay), 78 commitToIEWDelay(params->commitToIEWDelay), 79 renameToROBDelay(params->renameToROBDelay), 80 fetchToCommitDelay(params->commitToFetchDelay), 81 renameWidth(params->renameWidth), 82 commitWidth(params->commitWidth), 83 numThreads(params->numberOfThreads), 84 drainPending(false), 85 switchedOut(false), 86 trapLatency(params->trapLatency) 87{ 88 _status = Active; 89 _nextStatus = Inactive; 90 std::string policy = params->smtCommitPolicy; 91 92 //Convert string to lowercase 93 std::transform(policy.begin(), policy.end(), policy.begin(), 94 (int(*)(int)) tolower); 95 96 //Assign commit policy 97 if (policy == "aggressive"){ 98 commitPolicy = Aggressive; 99 100 DPRINTF(Commit,"Commit Policy set to Aggressive."); 101 } else if (policy == "roundrobin"){ 102 commitPolicy = RoundRobin; 103 104 //Set-Up Priority List 105 for (int tid=0; tid < numThreads; tid++) { 106 priority_list.push_back(tid); 107 } 108 109 DPRINTF(Commit,"Commit Policy set to Round Robin."); 110 } else if (policy == "oldestready"){ 111 commitPolicy = OldestReady; 112 113 DPRINTF(Commit,"Commit Policy set to Oldest Ready."); 114 } else { 115 assert(0 && "Invalid SMT Commit Policy. Options Are: {Aggressive," 116 "RoundRobin,OldestReady}"); 117 } 118 119 for (int i=0; i < numThreads; i++) { 120 commitStatus[i] = Idle; 121 changedROBNumEntries[i] = false; 122 checkEmptyROB[i] = false; 123 trapInFlight[i] = false; 124 committedStores[i] = false; 125 trapSquash[i] = false; 126 tcSquash[i] = false; 127 microPC[i] = nextMicroPC[i] = PC[i] = nextPC[i] = nextNPC[i] = 0; 128 } 129#if FULL_SYSTEM 130 interrupt = NoFault; 131#endif 132} 133 134template <class Impl> 135std::string 136DefaultCommit<Impl>::name() const 137{ 138 return cpu->name() + ".commit"; 139} 140 141template <class Impl> 142void 143DefaultCommit<Impl>::regStats() 144{ 145 using namespace Stats; 146 commitCommittedInsts 147 .name(name() + ".commitCommittedInsts") 148 .desc("The number of committed instructions") 149 .prereq(commitCommittedInsts); 150 commitSquashedInsts 151 .name(name() + ".commitSquashedInsts") 152 .desc("The number of squashed insts skipped by commit") 153 .prereq(commitSquashedInsts); 154 commitSquashEvents 155 .name(name() + ".commitSquashEvents") 156 .desc("The number of times commit is told to squash") 157 .prereq(commitSquashEvents); 158 commitNonSpecStalls 159 .name(name() + ".commitNonSpecStalls") 160 .desc("The number of times commit has been forced to stall to " 161 "communicate backwards") 162 .prereq(commitNonSpecStalls); 163 branchMispredicts 164 .name(name() + ".branchMispredicts") 165 .desc("The number of times a branch was mispredicted") 166 .prereq(branchMispredicts); 167 numCommittedDist 168 .init(0,commitWidth,1) 169 .name(name() + ".COM:committed_per_cycle") 170 .desc("Number of insts commited each cycle") 171 .flags(Stats::pdf) 172 ; 173 174 statComInst 175 .init(cpu->number_of_threads) 176 .name(name() + ".COM:count") 177 .desc("Number of instructions committed") 178 .flags(total) 179 ; 180 181 statComSwp 182 .init(cpu->number_of_threads) 183 .name(name() + ".COM:swp_count") 184 .desc("Number of s/w prefetches committed") 185 .flags(total) 186 ; 187 188 statComRefs 189 .init(cpu->number_of_threads) 190 .name(name() + ".COM:refs") 191 .desc("Number of memory references committed") 192 .flags(total) 193 ; 194 195 statComLoads 196 .init(cpu->number_of_threads) 197 .name(name() + ".COM:loads") 198 .desc("Number of loads committed") 199 .flags(total) 200 ; 201 202 statComMembars 203 .init(cpu->number_of_threads) 204 .name(name() + ".COM:membars") 205 .desc("Number of memory barriers committed") 206 .flags(total) 207 ; 208 209 statComBranches 210 .init(cpu->number_of_threads) 211 .name(name() + ".COM:branches") 212 .desc("Number of branches committed") 213 .flags(total) 214 ; 215 216 commitEligible 217 .init(cpu->number_of_threads) 218 .name(name() + ".COM:bw_limited") 219 .desc("number of insts not committed due to BW limits") 220 .flags(total) 221 ; 222 223 commitEligibleSamples 224 .name(name() + ".COM:bw_lim_events") 225 .desc("number cycles where commit BW limit reached") 226 ; 227} 228 229template <class Impl> 230void 231DefaultCommit<Impl>::setThreads(std::vector<Thread *> &threads) 232{ 233 thread = threads; 234} 235 236template <class Impl> 237void 238DefaultCommit<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr) 239{ 240 timeBuffer = tb_ptr; 241 242 // Setup wire to send information back to IEW. 243 toIEW = timeBuffer->getWire(0); 244 245 // Setup wire to read data from IEW (for the ROB). 246 robInfoFromIEW = timeBuffer->getWire(-iewToCommitDelay); 247} 248 249template <class Impl> 250void 251DefaultCommit<Impl>::setFetchQueue(TimeBuffer<FetchStruct> *fq_ptr) 252{ 253 fetchQueue = fq_ptr; 254 255 // Setup wire to get instructions from rename (for the ROB). 256 fromFetch = fetchQueue->getWire(-fetchToCommitDelay); 257} 258 259template <class Impl> 260void 261DefaultCommit<Impl>::setRenameQueue(TimeBuffer<RenameStruct> *rq_ptr) 262{ 263 renameQueue = rq_ptr; 264 265 // Setup wire to get instructions from rename (for the ROB). 266 fromRename = renameQueue->getWire(-renameToROBDelay); 267} 268 269template <class Impl> 270void 271DefaultCommit<Impl>::setIEWQueue(TimeBuffer<IEWStruct> *iq_ptr) 272{ 273 iewQueue = iq_ptr; 274 275 // Setup wire to get instructions from IEW. 276 fromIEW = iewQueue->getWire(-iewToCommitDelay); 277} 278 279template <class Impl> 280void 281DefaultCommit<Impl>::setIEWStage(IEW *iew_stage) 282{ 283 iewStage = iew_stage; 284} 285 286template<class Impl> 287void 288DefaultCommit<Impl>::setActiveThreads(std::list<unsigned> *at_ptr) 289{ 290 activeThreads = at_ptr; 291} 292 293template <class Impl> 294void 295DefaultCommit<Impl>::setRenameMap(RenameMap rm_ptr[]) 296{ 297 for (int i=0; i < numThreads; i++) { 298 renameMap[i] = &rm_ptr[i]; 299 } 300} 301 302template <class Impl> 303void 304DefaultCommit<Impl>::setROB(ROB *rob_ptr) 305{ 306 rob = rob_ptr; 307} 308 309template <class Impl> 310void 311DefaultCommit<Impl>::initStage() 312{ 313 rob->setActiveThreads(activeThreads); 314 rob->resetEntries(); 315 316 // Broadcast the number of free entries. 317 for (int i=0; i < numThreads; i++) { 318 toIEW->commitInfo[i].usedROB = true; 319 toIEW->commitInfo[i].freeROBEntries = rob->numFreeEntries(i); 320 toIEW->commitInfo[i].emptyROB = true; 321 } 322 323 // Commit must broadcast the number of free entries it has at the 324 // start of the simulation, so it starts as active. 325 cpu->activateStage(O3CPU::CommitIdx); 326 327 cpu->activityThisCycle(); 328 trapLatency = cpu->ticks(trapLatency); 329} 330 331template <class Impl> 332bool 333DefaultCommit<Impl>::drain() 334{ 335 drainPending = true; 336 337 return false; 338} 339 340template <class Impl> 341void 342DefaultCommit<Impl>::switchOut() 343{ 344 switchedOut = true; 345 drainPending = false; 346 rob->switchOut(); 347} 348 349template <class Impl> 350void 351DefaultCommit<Impl>::resume() 352{ 353 drainPending = false; 354} 355 356template <class Impl> 357void 358DefaultCommit<Impl>::takeOverFrom() 359{ 360 switchedOut = false; 361 _status = Active; 362 _nextStatus = Inactive; 363 for (int i=0; i < numThreads; i++) { 364 commitStatus[i] = Idle; 365 changedROBNumEntries[i] = false; 366 trapSquash[i] = false; 367 tcSquash[i] = false; 368 } 369 squashCounter = 0; 370 rob->takeOverFrom(); 371} 372 373template <class Impl> 374void 375DefaultCommit<Impl>::updateStatus() 376{ 377 // reset ROB changed variable 378 std::list<unsigned>::iterator threads = activeThreads->begin(); 379 std::list<unsigned>::iterator end = activeThreads->end(); 380 381 while (threads != end) { 382 unsigned tid = *threads++; 383 384 changedROBNumEntries[tid] = false; 385 386 // Also check if any of the threads has a trap pending 387 if (commitStatus[tid] == TrapPending || 388 commitStatus[tid] == FetchTrapPending) { 389 _nextStatus = Active; 390 } 391 } 392 393 if (_nextStatus == Inactive && _status == Active) { 394 DPRINTF(Activity, "Deactivating stage.\n"); 395 cpu->deactivateStage(O3CPU::CommitIdx); 396 } else if (_nextStatus == Active && _status == Inactive) { 397 DPRINTF(Activity, "Activating stage.\n"); 398 cpu->activateStage(O3CPU::CommitIdx); 399 } 400 401 _status = _nextStatus; 402} 403 404template <class Impl> 405void 406DefaultCommit<Impl>::setNextStatus() 407{ 408 int squashes = 0; 409 410 std::list<unsigned>::iterator threads = activeThreads->begin(); 411 std::list<unsigned>::iterator end = activeThreads->end(); 412 413 while (threads != end) { 414 unsigned tid = *threads++; 415 416 if (commitStatus[tid] == ROBSquashing) { 417 squashes++; 418 } 419 } 420 421 squashCounter = squashes; 422 423 // If commit is currently squashing, then it will have activity for the 424 // next cycle. Set its next status as active. 425 if (squashCounter) { 426 _nextStatus = Active; 427 } 428} 429 430template <class Impl> 431bool 432DefaultCommit<Impl>::changedROBEntries() 433{ 434 std::list<unsigned>::iterator threads = activeThreads->begin(); 435 std::list<unsigned>::iterator end = activeThreads->end(); 436 437 while (threads != end) { 438 unsigned tid = *threads++; 439 440 if (changedROBNumEntries[tid]) { 441 return true; 442 } 443 } 444 445 return false; 446} 447 448template <class Impl> 449unsigned 450DefaultCommit<Impl>::numROBFreeEntries(unsigned tid) 451{ 452 return rob->numFreeEntries(tid); 453} 454 455template <class Impl> 456void 457DefaultCommit<Impl>::generateTrapEvent(unsigned tid) 458{ 459 DPRINTF(Commit, "Generating trap event for [tid:%i]\n", tid); 460 461 TrapEvent *trap = new TrapEvent(this, tid); 462 463 trap->schedule(curTick + trapLatency); 464 trapInFlight[tid] = true; 465} 466 467template <class Impl> 468void 469DefaultCommit<Impl>::generateTCEvent(unsigned tid) 470{ 471 assert(!trapInFlight[tid]); 472 DPRINTF(Commit, "Generating TC squash event for [tid:%i]\n", tid); 473 474 tcSquash[tid] = true; 475} 476 477template <class Impl> 478void 479DefaultCommit<Impl>::squashAll(unsigned tid) 480{ 481 // If we want to include the squashing instruction in the squash, 482 // then use one older sequence number. 483 // Hopefully this doesn't mess things up. Basically I want to squash 484 // all instructions of this thread. 485 InstSeqNum squashed_inst = rob->isEmpty() ? 486 0 : rob->readHeadInst(tid)->seqNum - 1; 487 488 // All younger instructions will be squashed. Set the sequence 489 // number as the youngest instruction in the ROB (0 in this case. 490 // Hopefully nothing breaks.) 491 youngestSeqNum[tid] = 0; 492 493 rob->squash(squashed_inst, tid); 494 changedROBNumEntries[tid] = true; 495 496 // Send back the sequence number of the squashed instruction. 497 toIEW->commitInfo[tid].doneSeqNum = squashed_inst; 498 499 // Send back the squash signal to tell stages that they should 500 // squash. 501 toIEW->commitInfo[tid].squash = true; 502 503 // Send back the rob squashing signal so other stages know that 504 // the ROB is in the process of squashing. 505 toIEW->commitInfo[tid].robSquashing = true; 506 507 toIEW->commitInfo[tid].branchMispredict = false; 508 509 toIEW->commitInfo[tid].nextPC = PC[tid]; 510 toIEW->commitInfo[tid].nextNPC = nextPC[tid]; 511 toIEW->commitInfo[tid].nextMicroPC = nextMicroPC[tid]; 512} 513 514template <class Impl> 515void 516DefaultCommit<Impl>::squashFromTrap(unsigned tid) 517{ 518 squashAll(tid); 519 520 DPRINTF(Commit, "Squashing from trap, restarting at PC %#x\n", PC[tid]); 521 522 thread[tid]->trapPending = false; 523 thread[tid]->inSyscall = false; 524 trapInFlight[tid] = false; 525 526 trapSquash[tid] = false; 527 528 commitStatus[tid] = ROBSquashing; 529 cpu->activityThisCycle(); 530} 531 532template <class Impl> 533void 534DefaultCommit<Impl>::squashFromTC(unsigned tid) 535{ 536 squashAll(tid); 537 538 DPRINTF(Commit, "Squashing from TC, restarting at PC %#x\n", PC[tid]); 539 540 thread[tid]->inSyscall = false; 541 assert(!thread[tid]->trapPending); 542 543 commitStatus[tid] = ROBSquashing; 544 cpu->activityThisCycle(); 545 546 tcSquash[tid] = false; 547} 548 549template <class Impl> 550void 551DefaultCommit<Impl>::tick() 552{ 553 wroteToTimeBuffer = false; 554 _nextStatus = Inactive; 555 556 if (drainPending && rob->isEmpty() && !iewStage->hasStoresToWB()) { 557 cpu->signalDrained(); 558 drainPending = false; 559 return; 560 } 561 562 if (activeThreads->empty()) 563 return; 564 565 std::list<unsigned>::iterator threads = activeThreads->begin(); 566 std::list<unsigned>::iterator end = activeThreads->end(); 567 568 // Check if any of the threads are done squashing. Change the 569 // status if they are done. 570 while (threads != end) { 571 unsigned tid = *threads++; 572 573 // Clear the bit saying if the thread has committed stores 574 // this cycle. 575 committedStores[tid] = false; 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 != 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} 631 632#if FULL_SYSTEM 633template <class Impl> 634void 635DefaultCommit<Impl>::handleInterrupt() 636{ 637 if (interrupt != NoFault) { 638 // Wait until the ROB is empty and all stores have drained in 639 // order to enter the interrupt. 640 if (rob->isEmpty() && !iewStage->hasStoresToWB()) { 641 // Squash or record that I need to squash this cycle if 642 // an interrupt needed to be handled. 643 DPRINTF(Commit, "Interrupt detected.\n"); 644 645 // Clear the interrupt now that it's going to be handled 646 toIEW->commitInfo[0].clearInterrupt = true; 647 648 assert(!thread[0]->inSyscall); 649 thread[0]->inSyscall = true; 650 651 // CPU will handle interrupt. 652 cpu->processInterrupts(interrupt); 653 654 thread[0]->inSyscall = false; 655 656 commitStatus[0] = TrapPending; 657 658 // Generate trap squash event. 659 generateTrapEvent(0); 660 661 interrupt = NoFault; 662 } else { 663 DPRINTF(Commit, "Interrupt pending, waiting for ROB to empty.\n"); 664 } 665 } else if (commitStatus[0] != TrapPending && 666 cpu->check_interrupts(cpu->tcBase(0)) && 667 !trapSquash[0] && 668 !tcSquash[0]) { 669 // Process interrupts if interrupts are enabled, not in PAL 670 // mode, and no other traps or external squashes are currently 671 // pending. 672 // @todo: Allow other threads to handle interrupts. 673 674 // Get any interrupt that happened 675 interrupt = cpu->getInterrupts(); 676 677 if (interrupt != NoFault) { 678 // Tell fetch that there is an interrupt pending. This 679 // will make fetch wait until it sees a non PAL-mode PC, 680 // at which point it stops fetching instructions. 681 toIEW->commitInfo[0].interruptPending = true; 682 } 683 } 684} 685#endif // FULL_SYSTEM 686 687template <class Impl> 688void 689DefaultCommit<Impl>::commit() 690{ 691 692#if FULL_SYSTEM 693 // Check for any interrupt, and start processing it. Or if we 694 // have an outstanding interrupt and are at a point when it is 695 // valid to take an interrupt, process it. 696 if (cpu->check_interrupts(cpu->tcBase(0))) { 697 handleInterrupt(); 698 } 699#endif // FULL_SYSTEM 700 701 //////////////////////////////////// 702 // Check for any possible squashes, handle them first 703 //////////////////////////////////// 704 std::list<unsigned>::iterator threads = activeThreads->begin(); 705 std::list<unsigned>::iterator end = activeThreads->end(); 706 707 while (threads != end) { 708 unsigned tid = *threads++; 709 710 // Not sure which one takes priority. I think if we have 711 // both, that's a bad sign. 712 if (trapSquash[tid] == true) { 713 assert(!tcSquash[tid]); 714 squashFromTrap(tid); 715 } else if (tcSquash[tid] == true) { 716 assert(commitStatus[tid] != TrapPending); 717 squashFromTC(tid); 718 } 719 720 // Squashed sequence number must be older than youngest valid 721 // instruction in the ROB. This prevents squashes from younger 722 // instructions overriding squashes from older instructions. 723 if (fromIEW->squash[tid] && 724 commitStatus[tid] != TrapPending && 725 fromIEW->squashedSeqNum[tid] <= youngestSeqNum[tid]) { 726 727 DPRINTF(Commit, "[tid:%i]: Squashing due to PC %#x [sn:%i]\n", 728 tid, 729 fromIEW->mispredPC[tid], 730 fromIEW->squashedSeqNum[tid]); 731 732 DPRINTF(Commit, "[tid:%i]: Redirecting to PC %#x\n", 733 tid, 734 fromIEW->nextPC[tid]); 735 736 commitStatus[tid] = ROBSquashing; 737 738 // If we want to include the squashing instruction in the squash, 739 // then use one older sequence number. 740 InstSeqNum squashed_inst = fromIEW->squashedSeqNum[tid]; 741 742 if (fromIEW->includeSquashInst[tid] == true) { 743 squashed_inst--; 744 } 745 746 // All younger instructions will be squashed. Set the sequence 747 // number as the youngest instruction in the ROB. 748 youngestSeqNum[tid] = squashed_inst; 749 750 rob->squash(squashed_inst, tid); 751 changedROBNumEntries[tid] = true; 752 753 toIEW->commitInfo[tid].doneSeqNum = squashed_inst; 754 755 toIEW->commitInfo[tid].squash = true; 756 757 // Send back the rob squashing signal so other stages know that 758 // the ROB is in the process of squashing. 759 toIEW->commitInfo[tid].robSquashing = true; 760 761 toIEW->commitInfo[tid].branchMispredict = 762 fromIEW->branchMispredict[tid]; 763 764 toIEW->commitInfo[tid].branchTaken = 765 fromIEW->branchTaken[tid]; 766 767 toIEW->commitInfo[tid].nextPC = fromIEW->nextPC[tid]; 768 toIEW->commitInfo[tid].nextNPC = fromIEW->nextNPC[tid]; 769 toIEW->commitInfo[tid].nextMicroPC = fromIEW->nextMicroPC[tid]; 770 771 toIEW->commitInfo[tid].mispredPC = fromIEW->mispredPC[tid]; 772 773 if (toIEW->commitInfo[tid].branchMispredict) { 774 ++branchMispredicts; 775 } 776 } 777 778 } 779 780 setNextStatus(); 781 782 if (squashCounter != numThreads) { 783 // If we're not currently squashing, then get instructions. 784 getInsts(); 785 786 // Try to commit any instructions. 787 commitInsts(); 788 } 789 790 //Check for any activity 791 threads = activeThreads->begin(); 792 793 while (threads != end) { 794 unsigned tid = *threads++; 795 796 if (changedROBNumEntries[tid]) { 797 toIEW->commitInfo[tid].usedROB = true; 798 toIEW->commitInfo[tid].freeROBEntries = rob->numFreeEntries(tid); 799 800 wroteToTimeBuffer = true; 801 changedROBNumEntries[tid] = false; 802 if (rob->isEmpty(tid)) 803 checkEmptyROB[tid] = true; 804 } 805 806 // ROB is only considered "empty" for previous stages if: a) 807 // ROB is empty, b) there are no outstanding stores, c) IEW 808 // stage has received any information regarding stores that 809 // committed. 810 // c) is checked by making sure to not consider the ROB empty 811 // on the same cycle as when stores have been committed. 812 // @todo: Make this handle multi-cycle communication between 813 // commit and IEW. 814 if (checkEmptyROB[tid] && rob->isEmpty(tid) && 815 !iewStage->hasStoresToWB() && !committedStores[tid]) { 816 checkEmptyROB[tid] = false; 817 toIEW->commitInfo[tid].usedROB = true; 818 toIEW->commitInfo[tid].emptyROB = true; 819 toIEW->commitInfo[tid].freeROBEntries = rob->numFreeEntries(tid); 820 wroteToTimeBuffer = true; 821 } 822 823 } 824} 825 826template <class Impl> 827void 828DefaultCommit<Impl>::commitInsts() 829{ 830 //////////////////////////////////// 831 // Handle commit 832 // Note that commit will be handled prior to putting new 833 // instructions in the ROB so that the ROB only tries to commit 834 // instructions it has in this current cycle, and not instructions 835 // it is writing in during this cycle. Can't commit and squash 836 // things at the same time... 837 //////////////////////////////////// 838 839 DPRINTF(Commit, "Trying to commit instructions in the ROB.\n"); 840 841 unsigned num_committed = 0; 842 843 DynInstPtr head_inst; 844 845 // Commit as many instructions as possible until the commit bandwidth 846 // limit is reached, or it becomes impossible to commit any more. 847 while (num_committed < commitWidth) { 848 int commit_thread = getCommittingThread(); 849 850 if (commit_thread == -1 || !rob->isHeadReady(commit_thread)) 851 break; 852 853 head_inst = rob->readHeadInst(commit_thread); 854 855 int tid = head_inst->threadNumber; 856 857 assert(tid == commit_thread); 858 859 DPRINTF(Commit, "Trying to commit head instruction, [sn:%i] [tid:%i]\n", 860 head_inst->seqNum, tid); 861 862 // If the head instruction is squashed, it is ready to retire 863 // (be removed from the ROB) at any time. 864 if (head_inst->isSquashed()) { 865 866 DPRINTF(Commit, "Retiring squashed instruction from " 867 "ROB.\n"); 868 869 rob->retireHead(commit_thread); 870 871 ++commitSquashedInsts; 872 873 // Record that the number of ROB entries has changed. 874 changedROBNumEntries[tid] = true; 875 } else { 876 PC[tid] = head_inst->readPC(); 877 nextPC[tid] = head_inst->readNextPC(); 878 nextNPC[tid] = head_inst->readNextNPC(); 879 nextMicroPC[tid] = head_inst->readNextMicroPC(); 880 881 // Increment the total number of non-speculative instructions 882 // executed. 883 // Hack for now: it really shouldn't happen until after the 884 // commit is deemed to be successful, but this count is needed 885 // for syscalls. 886 thread[tid]->funcExeInst++; 887 888 // Try to commit the head instruction. 889 bool commit_success = commitHead(head_inst, num_committed); 890 891 if (commit_success) { 892 ++num_committed; 893 894 changedROBNumEntries[tid] = true; 895 896 // Set the doneSeqNum to the youngest committed instruction. 897 toIEW->commitInfo[tid].doneSeqNum = head_inst->seqNum; 898 899 ++commitCommittedInsts; 900 901 // To match the old model, don't count nops and instruction 902 // prefetches towards the total commit count. 903 if (!head_inst->isNop() && !head_inst->isInstPrefetch()) { 904 cpu->instDone(tid); 905 } 906 907 PC[tid] = nextPC[tid]; 908 nextPC[tid] = nextNPC[tid]; 909 nextNPC[tid] = nextNPC[tid] + sizeof(TheISA::MachInst); 910 microPC[tid] = nextMicroPC[tid]; 911 nextMicroPC[tid] = microPC[tid] + 1; 912 913 int count = 0; 914 Addr oldpc; 915 // Debug statement. Checks to make sure we're not 916 // currently updating state while handling PC events. 917 assert(!thread[tid]->inSyscall && !thread[tid]->trapPending); 918 do { 919 oldpc = PC[tid]; 920 cpu->system->pcEventQueue.service(thread[tid]->getTC()); 921 count++; 922 } while (oldpc != PC[tid]); 923 if (count > 1) { 924 DPRINTF(Commit, 925 "PC skip function event, stopping commit\n"); 926 break; 927 } 928 } else { 929 DPRINTF(Commit, "Unable to commit head instruction PC:%#x " 930 "[tid:%i] [sn:%i].\n", 931 head_inst->readPC(), tid ,head_inst->seqNum); 932 break; 933 } 934 } 935 } 936 937 DPRINTF(CommitRate, "%i\n", num_committed); 938 numCommittedDist.sample(num_committed); 939 940 if (num_committed == commitWidth) { 941 commitEligibleSamples++; 942 } 943} 944 945template <class Impl> 946bool 947DefaultCommit<Impl>::commitHead(DynInstPtr &head_inst, unsigned inst_num) 948{ 949 assert(head_inst); 950 951 int tid = head_inst->threadNumber; 952 953 // If the instruction is not executed yet, then it will need extra 954 // handling. Signal backwards that it should be executed. 955 if (!head_inst->isExecuted()) { 956 // Keep this number correct. We have not yet actually executed 957 // and committed this instruction. 958 thread[tid]->funcExeInst--; 959 960 if (head_inst->isNonSpeculative() || 961 head_inst->isStoreConditional() || 962 head_inst->isMemBarrier() || 963 head_inst->isWriteBarrier()) { 964 965 DPRINTF(Commit, "Encountered a barrier or non-speculative " 966 "instruction [sn:%lli] at the head of the ROB, PC %#x.\n", 967 head_inst->seqNum, head_inst->readPC()); 968 969 if (inst_num > 0 || iewStage->hasStoresToWB()) { 970 DPRINTF(Commit, "Waiting for all stores to writeback.\n"); 971 return false; 972 } 973 974 toIEW->commitInfo[tid].nonSpecSeqNum = head_inst->seqNum; 975 976 // Change the instruction so it won't try to commit again until 977 // it is executed. 978 head_inst->clearCanCommit(); 979 980 ++commitNonSpecStalls; 981 982 return false; 983 } else if (head_inst->isLoad()) { 984 if (inst_num > 0 || iewStage->hasStoresToWB()) { 985 DPRINTF(Commit, "Waiting for all stores to writeback.\n"); 986 return false; 987 } 988 989 assert(head_inst->uncacheable()); 990 DPRINTF(Commit, "[sn:%lli]: Uncached load, PC %#x.\n", 991 head_inst->seqNum, head_inst->readPC()); 992 993 // Send back the non-speculative instruction's sequence 994 // number. Tell the lsq to re-execute the load. 995 toIEW->commitInfo[tid].nonSpecSeqNum = head_inst->seqNum; 996 toIEW->commitInfo[tid].uncached = true; 997 toIEW->commitInfo[tid].uncachedLoad = head_inst; 998 999 head_inst->clearCanCommit(); 1000 1001 return false; 1002 } else { 1003 panic("Trying to commit un-executed instruction " 1004 "of unknown type!\n"); 1005 } 1006 } 1007 1008 if (head_inst->isThreadSync()) { 1009 // Not handled for now. 1010 panic("Thread sync instructions are not handled yet.\n"); 1011 } 1012 1013 // Check if the instruction caused a fault. If so, trap. 1014 Fault inst_fault = head_inst->getFault(); 1015 1016 // Stores mark themselves as completed. 1017 if (!head_inst->isStore() && inst_fault == NoFault) { 1018 head_inst->setCompleted(); 1019 } 1020 1021#if USE_CHECKER 1022 // Use checker prior to updating anything due to traps or PC 1023 // based events. 1024 if (cpu->checker) { 1025 cpu->checker->verify(head_inst); 1026 } 1027#endif 1028 1029 // DTB will sometimes need the machine instruction for when 1030 // faults happen. So we will set it here, prior to the DTB 1031 // possibly needing it for its fault. 1032 thread[tid]->setInst( 1033 static_cast<TheISA::MachInst>(head_inst->staticInst->machInst)); 1034 1035 if (inst_fault != NoFault) { 1036 DPRINTF(Commit, "Inst [sn:%lli] PC %#x has a fault\n", 1037 head_inst->seqNum, head_inst->readPC()); 1038 1039 if (iewStage->hasStoresToWB() || inst_num > 0) { 1040 DPRINTF(Commit, "Stores outstanding, fault must wait.\n"); 1041 return false; 1042 } 1043 1044 head_inst->setCompleted(); 1045 1046#if USE_CHECKER 1047 if (cpu->checker && head_inst->isStore()) { 1048 cpu->checker->verify(head_inst); 1049 } 1050#endif 1051 1052 assert(!thread[tid]->inSyscall); 1053 1054 // Mark that we're in state update mode so that the trap's 1055 // execution doesn't generate extra squashes. 1056 thread[tid]->inSyscall = true; 1057 1058 // Execute the trap. Although it's slightly unrealistic in 1059 // terms of timing (as it doesn't wait for the full timing of 1060 // the trap event to complete before updating state), it's 1061 // needed to update the state as soon as possible. This 1062 // prevents external agents from changing any specific state 1063 // that the trap need. 1064 cpu->trap(inst_fault, tid); 1065 1066 // Exit state update mode to avoid accidental updating. 1067 thread[tid]->inSyscall = false; 1068 1069 commitStatus[tid] = TrapPending; 1070 1071 if (head_inst->traceData) { 1072 head_inst->traceData->setFetchSeq(head_inst->seqNum); 1073 head_inst->traceData->setCPSeq(thread[tid]->numInst); 1074 head_inst->traceData->dump(); 1075 delete head_inst->traceData; 1076 head_inst->traceData = NULL; 1077 } 1078 1079 // Generate trap squash event. 1080 generateTrapEvent(tid); 1081// warn("%lli fault (%d) handled @ PC %08p", curTick, inst_fault->name(), head_inst->readPC()); 1082 return false; 1083 } 1084 1085 updateComInstStats(head_inst); 1086 1087#if FULL_SYSTEM 1088 if (thread[tid]->profile) { 1089// bool usermode = TheISA::inUserMode(thread[tid]->getTC()); 1090// thread[tid]->profilePC = usermode ? 1 : head_inst->readPC(); 1091 thread[tid]->profilePC = head_inst->readPC(); 1092 ProfileNode *node = thread[tid]->profile->consume(thread[tid]->getTC(), 1093 head_inst->staticInst); 1094 1095 if (node) 1096 thread[tid]->profileNode = node; 1097 } 1098#endif 1099 1100 if (head_inst->traceData) { 1101 head_inst->traceData->setFetchSeq(head_inst->seqNum); 1102 head_inst->traceData->setCPSeq(thread[tid]->numInst); 1103 head_inst->traceData->dump(); 1104 delete head_inst->traceData; 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 // If this was a store, record it for this cycle. 1121 if (head_inst->isStore()) 1122 committedStores[tid] = true; 1123 1124 // Return true to indicate that we have committed an instruction. 1125 return true; 1126} 1127 1128template <class Impl> 1129void 1130DefaultCommit<Impl>::getInsts() 1131{ 1132 DPRINTF(Commit, "Getting instructions from Rename stage.\n"); 1133 1134 // Read any renamed instructions and place them into the ROB. 1135 int insts_to_process = std::min((int)renameWidth, fromRename->size); 1136 1137 for (int inst_num = 0; inst_num < insts_to_process; ++inst_num) { 1138 DynInstPtr inst; 1139 1140 inst = fromRename->insts[inst_num]; 1141 int tid = inst->threadNumber; 1142 1143 if (!inst->isSquashed() && 1144 commitStatus[tid] != ROBSquashing && 1145 commitStatus[tid] != TrapPending) { 1146 changedROBNumEntries[tid] = true; 1147 1148 DPRINTF(Commit, "Inserting PC %#x [sn:%i] [tid:%i] into ROB.\n", 1149 inst->readPC(), inst->seqNum, tid); 1150 1151 rob->insertInst(inst); 1152 1153 assert(rob->getThreadEntries(tid) <= rob->getMaxEntries(tid)); 1154 1155 youngestSeqNum[tid] = inst->seqNum; 1156 } else { 1157 DPRINTF(Commit, "Instruction PC %#x [sn:%i] [tid:%i] was " 1158 "squashed, skipping.\n", 1159 inst->readPC(), inst->seqNum, tid); 1160 } 1161 } 1162} 1163 1164template <class Impl> 1165void 1166DefaultCommit<Impl>::skidInsert() 1167{ 1168 DPRINTF(Commit, "Attempting to any instructions from rename into " 1169 "skidBuffer.\n"); 1170 1171 for (int inst_num = 0; inst_num < fromRename->size; ++inst_num) { 1172 DynInstPtr inst = fromRename->insts[inst_num]; 1173 1174 if (!inst->isSquashed()) { 1175 DPRINTF(Commit, "Inserting PC %#x [sn:%i] [tid:%i] into ", 1176 "skidBuffer.\n", inst->readPC(), inst->seqNum, 1177 inst->threadNumber); 1178 skidBuffer.push(inst); 1179 } else { 1180 DPRINTF(Commit, "Instruction PC %#x [sn:%i] [tid:%i] was " 1181 "squashed, skipping.\n", 1182 inst->readPC(), inst->seqNum, inst->threadNumber); 1183 } 1184 } 1185} 1186 1187template <class Impl> 1188void 1189DefaultCommit<Impl>::markCompletedInsts() 1190{ 1191 // Grab completed insts out of the IEW instruction queue, and mark 1192 // instructions completed within the ROB. 1193 for (int inst_num = 0; 1194 inst_num < fromIEW->size && fromIEW->insts[inst_num]; 1195 ++inst_num) 1196 { 1197 if (!fromIEW->insts[inst_num]->isSquashed()) { 1198 DPRINTF(Commit, "[tid:%i]: Marking PC %#x, [sn:%lli] ready " 1199 "within ROB.\n", 1200 fromIEW->insts[inst_num]->threadNumber, 1201 fromIEW->insts[inst_num]->readPC(), 1202 fromIEW->insts[inst_num]->seqNum); 1203 1204 // Mark the instruction as ready to commit. 1205 fromIEW->insts[inst_num]->setCanCommit(); 1206 } 1207 } 1208} 1209 1210template <class Impl> 1211bool 1212DefaultCommit<Impl>::robDoneSquashing() 1213{ 1214 std::list<unsigned>::iterator threads = activeThreads->begin(); 1215 std::list<unsigned>::iterator end = activeThreads->end(); 1216 1217 while (threads != end) { 1218 unsigned tid = *threads++; 1219 1220 if (!rob->isDoneSquashing(tid)) 1221 return false; 1222 } 1223 1224 return true; 1225} 1226 1227template <class Impl> 1228void 1229DefaultCommit<Impl>::updateComInstStats(DynInstPtr &inst) 1230{ 1231 unsigned thread = inst->threadNumber; 1232 1233 // 1234 // Pick off the software prefetches 1235 // 1236#ifdef TARGET_ALPHA 1237 if (inst->isDataPrefetch()) { 1238 statComSwp[thread]++; 1239 } else { 1240 statComInst[thread]++; 1241 } 1242#else 1243 statComInst[thread]++; 1244#endif 1245 1246 // 1247 // Control Instructions 1248 // 1249 if (inst->isControl()) 1250 statComBranches[thread]++; 1251 1252 // 1253 // Memory references 1254 // 1255 if (inst->isMemRef()) { 1256 statComRefs[thread]++; 1257 1258 if (inst->isLoad()) { 1259 statComLoads[thread]++; 1260 } 1261 } 1262 1263 if (inst->isMemBarrier()) { 1264 statComMembars[thread]++; 1265 } 1266} 1267 1268//////////////////////////////////////// 1269// // 1270// SMT COMMIT POLICY MAINTAINED HERE // 1271// // 1272//////////////////////////////////////// 1273template <class Impl> 1274int 1275DefaultCommit<Impl>::getCommittingThread() 1276{ 1277 if (numThreads > 1) { 1278 switch (commitPolicy) { 1279 1280 case Aggressive: 1281 //If Policy is Aggressive, commit will call 1282 //this function multiple times per 1283 //cycle 1284 return oldestReady(); 1285 1286 case RoundRobin: 1287 return roundRobin(); 1288 1289 case OldestReady: 1290 return oldestReady(); 1291 1292 default: 1293 return -1; 1294 } 1295 } else { 1296 assert(!activeThreads->empty()); 1297 int tid = activeThreads->front(); 1298 1299 if (commitStatus[tid] == Running || 1300 commitStatus[tid] == Idle || 1301 commitStatus[tid] == FetchTrapPending) { 1302 return tid; 1303 } else { 1304 return -1; 1305 } 1306 } 1307} 1308 1309template<class Impl> 1310int 1311DefaultCommit<Impl>::roundRobin() 1312{ 1313 std::list<unsigned>::iterator pri_iter = priority_list.begin(); 1314 std::list<unsigned>::iterator end = priority_list.end(); 1315 1316 while (pri_iter != end) { 1317 unsigned tid = *pri_iter; 1318 1319 if (commitStatus[tid] == Running || 1320 commitStatus[tid] == Idle || 1321 commitStatus[tid] == FetchTrapPending) { 1322 1323 if (rob->isHeadReady(tid)) { 1324 priority_list.erase(pri_iter); 1325 priority_list.push_back(tid); 1326 1327 return tid; 1328 } 1329 } 1330 1331 pri_iter++; 1332 } 1333 1334 return -1; 1335} 1336 1337template<class Impl> 1338int 1339DefaultCommit<Impl>::oldestReady() 1340{ 1341 unsigned oldest = 0; 1342 bool first = true; 1343 1344 std::list<unsigned>::iterator threads = activeThreads->begin(); 1345 std::list<unsigned>::iterator end = activeThreads->end(); 1346 1347 while (threads != end) { 1348 unsigned tid = *threads++; 1349 1350 if (!rob->isEmpty(tid) && 1351 (commitStatus[tid] == Running || 1352 commitStatus[tid] == Idle || 1353 commitStatus[tid] == FetchTrapPending)) { 1354 1355 if (rob->isHeadReady(tid)) { 1356 1357 DynInstPtr head_inst = rob->readHeadInst(tid); 1358 1359 if (first) { 1360 oldest = tid; 1361 first = false; 1362 } else if (head_inst->seqNum < oldest) { 1363 oldest = tid; 1364 } 1365 } 1366 } 1367 } 1368 1369 if (!first) { 1370 return oldest; 1371 } else { 1372 return -1; 1373 } 1374} 1375