commit_impl.hh revision 3876:127c71cfe21a
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 std::list<unsigned>::iterator end = activeThreads->end(); 392 393 while (threads != end) { 394 unsigned tid = *threads++; 395 396 changedROBNumEntries[tid] = false; 397 398 // Also check if any of the threads has a trap pending 399 if (commitStatus[tid] == TrapPending || 400 commitStatus[tid] == FetchTrapPending) { 401 _nextStatus = Active; 402 } 403 } 404 405 if (_nextStatus == Inactive && _status == Active) { 406 DPRINTF(Activity, "Deactivating stage.\n"); 407 cpu->deactivateStage(O3CPU::CommitIdx); 408 } else if (_nextStatus == Active && _status == Inactive) { 409 DPRINTF(Activity, "Activating stage.\n"); 410 cpu->activateStage(O3CPU::CommitIdx); 411 } 412 413 _status = _nextStatus; 414} 415 416template <class Impl> 417void 418DefaultCommit<Impl>::setNextStatus() 419{ 420 int squashes = 0; 421 422 std::list<unsigned>::iterator threads = activeThreads->begin(); 423 std::list<unsigned>::iterator end = activeThreads->end(); 424 425 while (threads != end) { 426 unsigned tid = *threads++; 427 428 if (commitStatus[tid] == ROBSquashing) { 429 squashes++; 430 } 431 } 432 433 squashCounter = squashes; 434 435 // If commit is currently squashing, then it will have activity for the 436 // next cycle. Set its next status as active. 437 if (squashCounter) { 438 _nextStatus = Active; 439 } 440} 441 442template <class Impl> 443bool 444DefaultCommit<Impl>::changedROBEntries() 445{ 446 std::list<unsigned>::iterator threads = activeThreads->begin(); 447 std::list<unsigned>::iterator end = activeThreads->end(); 448 449 while (threads != end) { 450 unsigned tid = *threads++; 451 452 if (changedROBNumEntries[tid]) { 453 return true; 454 } 455 } 456 457 return false; 458} 459 460template <class Impl> 461unsigned 462DefaultCommit<Impl>::numROBFreeEntries(unsigned tid) 463{ 464 return rob->numFreeEntries(tid); 465} 466 467template <class Impl> 468void 469DefaultCommit<Impl>::generateTrapEvent(unsigned tid) 470{ 471 DPRINTF(Commit, "Generating trap event for [tid:%i]\n", tid); 472 473 TrapEvent *trap = new TrapEvent(this, tid); 474 475 trap->schedule(curTick + trapLatency); 476 477 thread[tid]->trapPending = true; 478} 479 480template <class Impl> 481void 482DefaultCommit<Impl>::generateTCEvent(unsigned tid) 483{ 484 DPRINTF(Commit, "Generating TC squash event for [tid:%i]\n", tid); 485 486 tcSquash[tid] = true; 487} 488 489template <class Impl> 490void 491DefaultCommit<Impl>::squashAll(unsigned tid) 492{ 493 // If we want to include the squashing instruction in the squash, 494 // then use one older sequence number. 495 // Hopefully this doesn't mess things up. Basically I want to squash 496 // all instructions of this thread. 497 InstSeqNum squashed_inst = rob->isEmpty() ? 498 0 : rob->readHeadInst(tid)->seqNum - 1;; 499 500 // All younger instructions will be squashed. Set the sequence 501 // number as the youngest instruction in the ROB (0 in this case. 502 // Hopefully nothing breaks.) 503 youngestSeqNum[tid] = 0; 504 505 rob->squash(squashed_inst, tid); 506 changedROBNumEntries[tid] = true; 507 508 // Send back the sequence number of the squashed instruction. 509 toIEW->commitInfo[tid].doneSeqNum = squashed_inst; 510 511 // Send back the squash signal to tell stages that they should 512 // squash. 513 toIEW->commitInfo[tid].squash = true; 514 515 // Send back the rob squashing signal so other stages know that 516 // the ROB is in the process of squashing. 517 toIEW->commitInfo[tid].robSquashing = true; 518 519 toIEW->commitInfo[tid].branchMispredict = false; 520 521 toIEW->commitInfo[tid].nextPC = PC[tid]; 522} 523 524template <class Impl> 525void 526DefaultCommit<Impl>::squashFromTrap(unsigned tid) 527{ 528 squashAll(tid); 529 530 DPRINTF(Commit, "Squashing from trap, restarting at PC %#x\n", PC[tid]); 531 532 thread[tid]->trapPending = false; 533 thread[tid]->inSyscall = false; 534 535 trapSquash[tid] = false; 536 537 commitStatus[tid] = ROBSquashing; 538 cpu->activityThisCycle(); 539} 540 541template <class Impl> 542void 543DefaultCommit<Impl>::squashFromTC(unsigned tid) 544{ 545 squashAll(tid); 546 547 DPRINTF(Commit, "Squashing from TC, restarting at PC %#x\n", PC[tid]); 548 549 thread[tid]->inSyscall = false; 550 assert(!thread[tid]->trapPending); 551 552 commitStatus[tid] = ROBSquashing; 553 cpu->activityThisCycle(); 554 555 tcSquash[tid] = false; 556} 557 558template <class Impl> 559void 560DefaultCommit<Impl>::tick() 561{ 562 wroteToTimeBuffer = false; 563 _nextStatus = Inactive; 564 565 if (drainPending && rob->isEmpty() && !iewStage->hasStoresToWB()) { 566 cpu->signalDrained(); 567 drainPending = false; 568 return; 569 } 570 571 if (activeThreads->empty()) 572 return; 573 574 std::list<unsigned>::iterator threads = activeThreads->begin(); 575 std::list<unsigned>::iterator end = activeThreads->end(); 576 577 // Check if any of the threads are done squashing. Change the 578 // status if they are done. 579 while (threads != end) { 580 unsigned tid = *threads++; 581 582 if (commitStatus[tid] == ROBSquashing) { 583 584 if (rob->isDoneSquashing(tid)) { 585 commitStatus[tid] = Running; 586 } else { 587 DPRINTF(Commit,"[tid:%u]: Still Squashing, cannot commit any" 588 " insts this cycle.\n", tid); 589 rob->doSquash(tid); 590 toIEW->commitInfo[tid].robSquashing = true; 591 wroteToTimeBuffer = true; 592 } 593 } 594 } 595 596 commit(); 597 598 markCompletedInsts(); 599 600 threads = activeThreads->begin(); 601 602 while (threads != end) { 603 unsigned tid = *threads++; 604 605 if (!rob->isEmpty(tid) && rob->readHeadInst(tid)->readyToCommit()) { 606 // The ROB has more instructions it can commit. Its next status 607 // will be active. 608 _nextStatus = Active; 609 610 DynInstPtr inst = rob->readHeadInst(tid); 611 612 DPRINTF(Commit,"[tid:%i]: Instruction [sn:%lli] PC %#x is head of" 613 " ROB and ready to commit\n", 614 tid, inst->seqNum, inst->readPC()); 615 616 } else if (!rob->isEmpty(tid)) { 617 DynInstPtr inst = rob->readHeadInst(tid); 618 619 DPRINTF(Commit,"[tid:%i]: Can't commit, Instruction [sn:%lli] PC " 620 "%#x is head of ROB and not ready\n", 621 tid, inst->seqNum, inst->readPC()); 622 } 623 624 DPRINTF(Commit, "[tid:%i]: ROB has %d insts & %d free entries.\n", 625 tid, rob->countInsts(tid), rob->numFreeEntries(tid)); 626 } 627 628 629 if (wroteToTimeBuffer) { 630 DPRINTF(Activity, "Activity This Cycle.\n"); 631 cpu->activityThisCycle(); 632 } 633 634 updateStatus(); 635} 636 637template <class Impl> 638void 639DefaultCommit<Impl>::commit() 640{ 641 642 ////////////////////////////////////// 643 // Check for interrupts 644 ////////////////////////////////////// 645 646#if FULL_SYSTEM 647 if (interrupt != NoFault) { 648 // Wait until the ROB is empty and all stores have drained in 649 // order to enter the interrupt. 650 if (rob->isEmpty() && !iewStage->hasStoresToWB()) { 651 // Squash or record that I need to squash this cycle if 652 // an interrupt needed to be handled. 653 DPRINTF(Commit, "Interrupt detected.\n"); 654 655 assert(!thread[0]->inSyscall); 656 thread[0]->inSyscall = true; 657 658 // CPU will handle interrupt. 659 cpu->processInterrupts(interrupt); 660 661 thread[0]->inSyscall = false; 662 663 commitStatus[0] = TrapPending; 664 665 // Generate trap squash event. 666 generateTrapEvent(0); 667 668 // Clear the interrupt now that it's been handled 669 toIEW->commitInfo[0].clearInterrupt = true; 670 interrupt = NoFault; 671 } else { 672 DPRINTF(Commit, "Interrupt pending, waiting for ROB to empty.\n"); 673 } 674 } else if (cpu->checkInterrupts && 675 cpu->check_interrupts(cpu->tcBase(0)) && 676 commitStatus[0] != TrapPending && 677 !trapSquash[0] && 678 !tcSquash[0]) { 679 // Process interrupts if interrupts are enabled, not in PAL 680 // mode, and no other traps or external squashes are currently 681 // pending. 682 // @todo: Allow other threads to handle interrupts. 683 684 // Get any interrupt that happened 685 interrupt = cpu->getInterrupts(); 686 687 if (interrupt != NoFault) { 688 // Tell fetch that there is an interrupt pending. This 689 // will make fetch wait until it sees a non PAL-mode PC, 690 // at which point it stops fetching instructions. 691 toIEW->commitInfo[0].interruptPending = true; 692 } 693 } 694 695#endif // FULL_SYSTEM 696 697 //////////////////////////////////// 698 // Check for any possible squashes, handle them first 699 //////////////////////////////////// 700 std::list<unsigned>::iterator threads = activeThreads->begin(); 701 std::list<unsigned>::iterator end = activeThreads->end(); 702 703 while (threads != end) { 704 unsigned tid = *threads++; 705 706 // Not sure which one takes priority. I think if we have 707 // both, that's a bad sign. 708 if (trapSquash[tid] == true) { 709 assert(!tcSquash[tid]); 710 squashFromTrap(tid); 711 } else if (tcSquash[tid] == true) { 712 squashFromTC(tid); 713 } 714 715 // Squashed sequence number must be older than youngest valid 716 // instruction in the ROB. This prevents squashes from younger 717 // instructions overriding squashes from older instructions. 718 if (fromIEW->squash[tid] && 719 commitStatus[tid] != TrapPending && 720 fromIEW->squashedSeqNum[tid] <= youngestSeqNum[tid]) { 721 722 DPRINTF(Commit, "[tid:%i]: Squashing due to PC %#x [sn:%i]\n", 723 tid, 724 fromIEW->mispredPC[tid], 725 fromIEW->squashedSeqNum[tid]); 726 727 DPRINTF(Commit, "[tid:%i]: Redirecting to PC %#x\n", 728 tid, 729 fromIEW->nextPC[tid]); 730 731 commitStatus[tid] = ROBSquashing; 732 733 // If we want to include the squashing instruction in the squash, 734 // then use one older sequence number. 735 InstSeqNum squashed_inst = fromIEW->squashedSeqNum[tid]; 736 737#if ISA_HAS_DELAY_SLOT 738 InstSeqNum bdelay_done_seq_num; 739 bool squash_bdelay_slot; 740 741 if (fromIEW->branchMispredict[tid]) { 742 if (fromIEW->branchTaken[tid] && 743 fromIEW->condDelaySlotBranch[tid]) { 744 DPRINTF(Commit, "[tid:%i]: Cond. delay slot branch" 745 "mispredicted as taken. Squashing after previous " 746 "inst, [sn:%i]\n", 747 tid, squashed_inst); 748 bdelay_done_seq_num = squashed_inst; 749 squash_bdelay_slot = true; 750 } else { 751 DPRINTF(Commit, "[tid:%i]: Branch Mispredict. Squashing " 752 "after delay slot [sn:%i]\n", tid, squashed_inst+1); 753 bdelay_done_seq_num = squashed_inst + 1; 754 squash_bdelay_slot = false; 755 } 756 } else { 757 bdelay_done_seq_num = squashed_inst; 758 squash_bdelay_slot = true; 759 } 760#endif 761 762 if (fromIEW->includeSquashInst[tid] == true) { 763 squashed_inst--; 764#if ISA_HAS_DELAY_SLOT 765 bdelay_done_seq_num--; 766#endif 767 } 768 // All younger instructions will be squashed. Set the sequence 769 // number as the youngest instruction in the ROB. 770 youngestSeqNum[tid] = squashed_inst; 771 772#if ISA_HAS_DELAY_SLOT 773 rob->squash(bdelay_done_seq_num, tid); 774 toIEW->commitInfo[tid].squashDelaySlot = squash_bdelay_slot; 775 toIEW->commitInfo[tid].bdelayDoneSeqNum = bdelay_done_seq_num; 776#else 777 rob->squash(squashed_inst, tid); 778 toIEW->commitInfo[tid].squashDelaySlot = true; 779#endif 780 changedROBNumEntries[tid] = true; 781 782 toIEW->commitInfo[tid].doneSeqNum = squashed_inst; 783 784 toIEW->commitInfo[tid].squash = true; 785 786 // Send back the rob squashing signal so other stages know that 787 // the ROB is in the process of squashing. 788 toIEW->commitInfo[tid].robSquashing = true; 789 790 toIEW->commitInfo[tid].branchMispredict = 791 fromIEW->branchMispredict[tid]; 792 793 toIEW->commitInfo[tid].branchTaken = 794 fromIEW->branchTaken[tid]; 795 796 toIEW->commitInfo[tid].nextPC = fromIEW->nextPC[tid]; 797 798 toIEW->commitInfo[tid].mispredPC = fromIEW->mispredPC[tid]; 799 800 if (toIEW->commitInfo[tid].branchMispredict) { 801 ++branchMispredicts; 802 } 803 } 804 805 } 806 807 setNextStatus(); 808 809 if (squashCounter != numThreads) { 810 // If we're not currently squashing, then get instructions. 811 getInsts(); 812 813 // Try to commit any instructions. 814 commitInsts(); 815 } else { 816#if ISA_HAS_DELAY_SLOT 817 skidInsert(); 818#endif 819 } 820 821 //Check for any activity 822 threads = activeThreads->begin(); 823 824 while (threads != end) { 825 unsigned tid = *threads++; 826 827 if (changedROBNumEntries[tid]) { 828 toIEW->commitInfo[tid].usedROB = true; 829 toIEW->commitInfo[tid].freeROBEntries = rob->numFreeEntries(tid); 830 831 if (rob->isEmpty(tid)) { 832 toIEW->commitInfo[tid].emptyROB = true; 833 } 834 835 wroteToTimeBuffer = true; 836 changedROBNumEntries[tid] = false; 837 } 838 } 839} 840 841template <class Impl> 842void 843DefaultCommit<Impl>::commitInsts() 844{ 845 //////////////////////////////////// 846 // Handle commit 847 // Note that commit will be handled prior to putting new 848 // instructions in the ROB so that the ROB only tries to commit 849 // instructions it has in this current cycle, and not instructions 850 // it is writing in during this cycle. Can't commit and squash 851 // things at the same time... 852 //////////////////////////////////// 853 854 DPRINTF(Commit, "Trying to commit instructions in the ROB.\n"); 855 856 unsigned num_committed = 0; 857 858 DynInstPtr head_inst; 859 860 // Commit as many instructions as possible until the commit bandwidth 861 // limit is reached, or it becomes impossible to commit any more. 862 while (num_committed < commitWidth) { 863 int commit_thread = getCommittingThread(); 864 865 if (commit_thread == -1 || !rob->isHeadReady(commit_thread)) 866 break; 867 868 head_inst = rob->readHeadInst(commit_thread); 869 870 int tid = head_inst->threadNumber; 871 872 assert(tid == commit_thread); 873 874 DPRINTF(Commit, "Trying to commit head instruction, [sn:%i] [tid:%i]\n", 875 head_inst->seqNum, tid); 876 877 // If the head instruction is squashed, it is ready to retire 878 // (be removed from the ROB) at any time. 879 if (head_inst->isSquashed()) { 880 881 DPRINTF(Commit, "Retiring squashed instruction from " 882 "ROB.\n"); 883 884 rob->retireHead(commit_thread); 885 886 ++commitSquashedInsts; 887 888 // Record that the number of ROB entries has changed. 889 changedROBNumEntries[tid] = true; 890 } else { 891 PC[tid] = head_inst->readPC(); 892 nextPC[tid] = head_inst->readNextPC(); 893 nextNPC[tid] = head_inst->readNextNPC(); 894 895 // Increment the total number of non-speculative instructions 896 // executed. 897 // Hack for now: it really shouldn't happen until after the 898 // commit is deemed to be successful, but this count is needed 899 // for syscalls. 900 thread[tid]->funcExeInst++; 901 902 // Try to commit the head instruction. 903 bool commit_success = commitHead(head_inst, num_committed); 904 905 if (commit_success) { 906 ++num_committed; 907 908 changedROBNumEntries[tid] = true; 909 910 // Set the doneSeqNum to the youngest committed instruction. 911 toIEW->commitInfo[tid].doneSeqNum = head_inst->seqNum; 912 913 ++commitCommittedInsts; 914 915 // To match the old model, don't count nops and instruction 916 // prefetches towards the total commit count. 917 if (!head_inst->isNop() && !head_inst->isInstPrefetch()) { 918 cpu->instDone(tid); 919 } 920 921 PC[tid] = nextPC[tid]; 922#if ISA_HAS_DELAY_SLOT 923 nextPC[tid] = nextNPC[tid]; 924 nextNPC[tid] = nextNPC[tid] + sizeof(TheISA::MachInst); 925#else 926 nextPC[tid] = nextPC[tid] + sizeof(TheISA::MachInst); 927#endif 928 929#if FULL_SYSTEM 930 int count = 0; 931 Addr oldpc; 932 do { 933 // Debug statement. Checks to make sure we're not 934 // currently updating state while handling PC events. 935 if (count == 0) 936 assert(!thread[tid]->inSyscall && 937 !thread[tid]->trapPending); 938 oldpc = PC[tid]; 939 cpu->system->pcEventQueue.service( 940 thread[tid]->getTC()); 941 count++; 942 } while (oldpc != PC[tid]); 943 if (count > 1) { 944 DPRINTF(Commit, "PC skip function event, stopping commit\n"); 945 break; 946 } 947#endif 948 } else { 949 DPRINTF(Commit, "Unable to commit head instruction PC:%#x " 950 "[tid:%i] [sn:%i].\n", 951 head_inst->readPC(), tid ,head_inst->seqNum); 952 break; 953 } 954 } 955 } 956 957 DPRINTF(CommitRate, "%i\n", num_committed); 958 numCommittedDist.sample(num_committed); 959 960 if (num_committed == commitWidth) { 961 commitEligibleSamples++; 962 } 963} 964 965template <class Impl> 966bool 967DefaultCommit<Impl>::commitHead(DynInstPtr &head_inst, unsigned inst_num) 968{ 969 assert(head_inst); 970 971 int tid = head_inst->threadNumber; 972 973 // If the instruction is not executed yet, then it will need extra 974 // handling. Signal backwards that it should be executed. 975 if (!head_inst->isExecuted()) { 976 // Keep this number correct. We have not yet actually executed 977 // and committed this instruction. 978 thread[tid]->funcExeInst--; 979 980 head_inst->setAtCommit(); 981 982 if (head_inst->isNonSpeculative() || 983 head_inst->isStoreConditional() || 984 head_inst->isMemBarrier() || 985 head_inst->isWriteBarrier()) { 986 987 DPRINTF(Commit, "Encountered a barrier or non-speculative " 988 "instruction [sn:%lli] at the head of the ROB, PC %#x.\n", 989 head_inst->seqNum, head_inst->readPC()); 990 991 // Hack to make sure syscalls/memory barriers/quiesces 992 // aren't executed until all stores write back their data. 993 // This direct communication shouldn't be used for 994 // anything other than this. 995 if ((head_inst->isMemBarrier() || head_inst->isWriteBarrier() || 996 head_inst->isQuiesce()) && 997 iewStage->hasStoresToWB()) 998 { 999 DPRINTF(Commit, "Waiting for all stores to writeback.\n"); 1000 return false; 1001 } else if (inst_num > 0) { 1002 DPRINTF(Commit, "Waiting to become head of commit.\n"); 1003 return false; 1004 } 1005 1006 toIEW->commitInfo[tid].nonSpecSeqNum = head_inst->seqNum; 1007 1008 // Change the instruction so it won't try to commit again until 1009 // it is executed. 1010 head_inst->clearCanCommit(); 1011 1012 ++commitNonSpecStalls; 1013 1014 return false; 1015 } else if (head_inst->isLoad()) { 1016 DPRINTF(Commit, "[sn:%lli]: Uncached load, PC %#x.\n", 1017 head_inst->seqNum, head_inst->readPC()); 1018 1019 // Send back the non-speculative instruction's sequence 1020 // number. Tell the lsq to re-execute the load. 1021 toIEW->commitInfo[tid].nonSpecSeqNum = head_inst->seqNum; 1022 toIEW->commitInfo[tid].uncached = true; 1023 toIEW->commitInfo[tid].uncachedLoad = head_inst; 1024 1025 head_inst->clearCanCommit(); 1026 1027 return false; 1028 } else { 1029 panic("Trying to commit un-executed instruction " 1030 "of unknown type!\n"); 1031 } 1032 } 1033 1034 if (head_inst->isThreadSync()) { 1035 // Not handled for now. 1036 panic("Thread sync instructions are not handled yet.\n"); 1037 } 1038 1039 // Stores mark themselves as completed. 1040 if (!head_inst->isStore()) { 1041 head_inst->setCompleted(); 1042 } 1043 1044#if USE_CHECKER 1045 // Use checker prior to updating anything due to traps or PC 1046 // based events. 1047 if (cpu->checker) { 1048 cpu->checker->verify(head_inst); 1049 } 1050#endif 1051 1052 // Check if the instruction caused a fault. If so, trap. 1053 Fault inst_fault = head_inst->getFault(); 1054 1055 // DTB will sometimes need the machine instruction for when 1056 // faults happen. So we will set it here, prior to the DTB 1057 // possibly needing it for its fault. 1058 thread[tid]->setInst( 1059 static_cast<TheISA::MachInst>(head_inst->staticInst->machInst)); 1060 1061 if (inst_fault != NoFault) { 1062 head_inst->setCompleted(); 1063 DPRINTF(Commit, "Inst [sn:%lli] PC %#x has a fault\n", 1064 head_inst->seqNum, head_inst->readPC()); 1065 1066 if (iewStage->hasStoresToWB() || inst_num > 0) { 1067 DPRINTF(Commit, "Stores outstanding, fault must wait.\n"); 1068 return false; 1069 } 1070 1071#if USE_CHECKER 1072 if (cpu->checker && head_inst->isStore()) { 1073 cpu->checker->verify(head_inst); 1074 } 1075#endif 1076 1077 assert(!thread[tid]->inSyscall); 1078 1079 // Mark that we're in state update mode so that the trap's 1080 // execution doesn't generate extra squashes. 1081 thread[tid]->inSyscall = true; 1082 1083 // Execute the trap. Although it's slightly unrealistic in 1084 // terms of timing (as it doesn't wait for the full timing of 1085 // the trap event to complete before updating state), it's 1086 // needed to update the state as soon as possible. This 1087 // prevents external agents from changing any specific state 1088 // that the trap need. 1089 cpu->trap(inst_fault, tid); 1090 1091 // Exit state update mode to avoid accidental updating. 1092 thread[tid]->inSyscall = false; 1093 1094 commitStatus[tid] = TrapPending; 1095 1096 // Generate trap squash event. 1097 generateTrapEvent(tid); 1098// warn("%lli fault (%d) handled @ PC %08p", curTick, inst_fault->name(), head_inst->readPC()); 1099 return false; 1100 } 1101 1102 updateComInstStats(head_inst); 1103 1104#if FULL_SYSTEM 1105 if (thread[tid]->profile) { 1106// bool usermode = TheISA::inUserMode(thread[tid]->getTC()); 1107// thread[tid]->profilePC = usermode ? 1 : head_inst->readPC(); 1108 thread[tid]->profilePC = head_inst->readPC(); 1109 ProfileNode *node = thread[tid]->profile->consume(thread[tid]->getTC(), 1110 head_inst->staticInst); 1111 1112 if (node) 1113 thread[tid]->profileNode = node; 1114 } 1115#endif 1116 1117 if (head_inst->traceData) { 1118 head_inst->traceData->setFetchSeq(head_inst->seqNum); 1119 head_inst->traceData->setCPSeq(thread[tid]->numInst); 1120 head_inst->traceData->finalize(); 1121 head_inst->traceData = NULL; 1122 } 1123 1124 // Update the commit rename map 1125 for (int i = 0; i < head_inst->numDestRegs(); i++) { 1126 renameMap[tid]->setEntry(head_inst->destRegIdx(i), 1127 head_inst->renamedDestRegIdx(i)); 1128 } 1129 1130 if (head_inst->isCopy()) 1131 panic("Should not commit any copy instructions!"); 1132 1133 // Finally clear the head ROB entry. 1134 rob->retireHead(tid); 1135 1136 // Return true to indicate that we have committed an instruction. 1137 return true; 1138} 1139 1140template <class Impl> 1141void 1142DefaultCommit<Impl>::getInsts() 1143{ 1144 DPRINTF(Commit, "Getting instructions from Rename stage.\n"); 1145 1146#if ISA_HAS_DELAY_SLOT 1147 // Read any renamed instructions and place them into the ROB. 1148 int insts_to_process = std::min((int)renameWidth, 1149 (int)(fromRename->size + skidBuffer.size())); 1150 int rename_idx = 0; 1151 1152 DPRINTF(Commit, "%i insts available to process. Rename Insts:%i " 1153 "SkidBuffer Insts:%i\n", insts_to_process, fromRename->size, 1154 skidBuffer.size()); 1155#else 1156 // Read any renamed instructions and place them into the ROB. 1157 int insts_to_process = std::min((int)renameWidth, fromRename->size); 1158#endif 1159 1160 1161 for (int inst_num = 0; inst_num < insts_to_process; ++inst_num) { 1162 DynInstPtr inst; 1163 1164#if ISA_HAS_DELAY_SLOT 1165 // Get insts from skidBuffer or from Rename 1166 if (skidBuffer.size() > 0) { 1167 DPRINTF(Commit, "Grabbing skidbuffer inst.\n"); 1168 inst = skidBuffer.front(); 1169 skidBuffer.pop(); 1170 } else { 1171 DPRINTF(Commit, "Grabbing rename inst.\n"); 1172 inst = fromRename->insts[rename_idx++]; 1173 } 1174#else 1175 inst = fromRename->insts[inst_num]; 1176#endif 1177 int tid = inst->threadNumber; 1178 1179 if (!inst->isSquashed() && 1180 commitStatus[tid] != ROBSquashing) { 1181 changedROBNumEntries[tid] = true; 1182 1183 DPRINTF(Commit, "Inserting PC %#x [sn:%i] [tid:%i] into ROB.\n", 1184 inst->readPC(), inst->seqNum, tid); 1185 1186 rob->insertInst(inst); 1187 1188 assert(rob->getThreadEntries(tid) <= rob->getMaxEntries(tid)); 1189 1190 youngestSeqNum[tid] = inst->seqNum; 1191 } else { 1192 DPRINTF(Commit, "Instruction PC %#x [sn:%i] [tid:%i] was " 1193 "squashed, skipping.\n", 1194 inst->readPC(), inst->seqNum, tid); 1195 } 1196 } 1197 1198#if ISA_HAS_DELAY_SLOT 1199 if (rename_idx < fromRename->size) { 1200 DPRINTF(Commit,"Placing Rename Insts into skidBuffer.\n"); 1201 1202 for (; 1203 rename_idx < fromRename->size; 1204 rename_idx++) { 1205 DynInstPtr inst = fromRename->insts[rename_idx]; 1206 1207 if (!inst->isSquashed()) { 1208 DPRINTF(Commit, "Inserting PC %#x [sn:%i] [tid:%i] into ", 1209 "skidBuffer.\n", inst->readPC(), inst->seqNum, 1210 inst->threadNumber); 1211 skidBuffer.push(inst); 1212 } else { 1213 DPRINTF(Commit, "Instruction PC %#x [sn:%i] [tid:%i] was " 1214 "squashed, skipping.\n", 1215 inst->readPC(), inst->seqNum, inst->threadNumber); 1216 } 1217 } 1218 } 1219#endif 1220 1221} 1222 1223template <class Impl> 1224void 1225DefaultCommit<Impl>::skidInsert() 1226{ 1227 DPRINTF(Commit, "Attempting to any instructions from rename into " 1228 "skidBuffer.\n"); 1229 1230 for (int inst_num = 0; inst_num < fromRename->size; ++inst_num) { 1231 DynInstPtr inst = fromRename->insts[inst_num]; 1232 1233 if (!inst->isSquashed()) { 1234 DPRINTF(Commit, "Inserting PC %#x [sn:%i] [tid:%i] into ", 1235 "skidBuffer.\n", inst->readPC(), inst->seqNum, 1236 inst->threadNumber); 1237 skidBuffer.push(inst); 1238 } else { 1239 DPRINTF(Commit, "Instruction PC %#x [sn:%i] [tid:%i] was " 1240 "squashed, skipping.\n", 1241 inst->readPC(), inst->seqNum, inst->threadNumber); 1242 } 1243 } 1244} 1245 1246template <class Impl> 1247void 1248DefaultCommit<Impl>::markCompletedInsts() 1249{ 1250 // Grab completed insts out of the IEW instruction queue, and mark 1251 // instructions completed within the ROB. 1252 for (int inst_num = 0; 1253 inst_num < fromIEW->size && fromIEW->insts[inst_num]; 1254 ++inst_num) 1255 { 1256 if (!fromIEW->insts[inst_num]->isSquashed()) { 1257 DPRINTF(Commit, "[tid:%i]: Marking PC %#x, [sn:%lli] ready " 1258 "within ROB.\n", 1259 fromIEW->insts[inst_num]->threadNumber, 1260 fromIEW->insts[inst_num]->readPC(), 1261 fromIEW->insts[inst_num]->seqNum); 1262 1263 // Mark the instruction as ready to commit. 1264 fromIEW->insts[inst_num]->setCanCommit(); 1265 } 1266 } 1267} 1268 1269template <class Impl> 1270bool 1271DefaultCommit<Impl>::robDoneSquashing() 1272{ 1273 std::list<unsigned>::iterator threads = activeThreads->begin(); 1274 std::list<unsigned>::iterator end = activeThreads->end(); 1275 1276 while (threads != end) { 1277 unsigned tid = *threads++; 1278 1279 if (!rob->isDoneSquashing(tid)) 1280 return false; 1281 } 1282 1283 return true; 1284} 1285 1286template <class Impl> 1287void 1288DefaultCommit<Impl>::updateComInstStats(DynInstPtr &inst) 1289{ 1290 unsigned thread = inst->threadNumber; 1291 1292 // 1293 // Pick off the software prefetches 1294 // 1295#ifdef TARGET_ALPHA 1296 if (inst->isDataPrefetch()) { 1297 statComSwp[thread]++; 1298 } else { 1299 statComInst[thread]++; 1300 } 1301#else 1302 statComInst[thread]++; 1303#endif 1304 1305 // 1306 // Control Instructions 1307 // 1308 if (inst->isControl()) 1309 statComBranches[thread]++; 1310 1311 // 1312 // Memory references 1313 // 1314 if (inst->isMemRef()) { 1315 statComRefs[thread]++; 1316 1317 if (inst->isLoad()) { 1318 statComLoads[thread]++; 1319 } 1320 } 1321 1322 if (inst->isMemBarrier()) { 1323 statComMembars[thread]++; 1324 } 1325} 1326 1327//////////////////////////////////////// 1328// // 1329// SMT COMMIT POLICY MAINTAINED HERE // 1330// // 1331//////////////////////////////////////// 1332template <class Impl> 1333int 1334DefaultCommit<Impl>::getCommittingThread() 1335{ 1336 if (numThreads > 1) { 1337 switch (commitPolicy) { 1338 1339 case Aggressive: 1340 //If Policy is Aggressive, commit will call 1341 //this function multiple times per 1342 //cycle 1343 return oldestReady(); 1344 1345 case RoundRobin: 1346 return roundRobin(); 1347 1348 case OldestReady: 1349 return oldestReady(); 1350 1351 default: 1352 return -1; 1353 } 1354 } else { 1355 assert(!activeThreads->empty()); 1356 int tid = activeThreads->front(); 1357 1358 if (commitStatus[tid] == Running || 1359 commitStatus[tid] == Idle || 1360 commitStatus[tid] == FetchTrapPending) { 1361 return tid; 1362 } else { 1363 return -1; 1364 } 1365 } 1366} 1367 1368template<class Impl> 1369int 1370DefaultCommit<Impl>::roundRobin() 1371{ 1372 std::list<unsigned>::iterator pri_iter = priority_list.begin(); 1373 std::list<unsigned>::iterator end = priority_list.end(); 1374 1375 while (pri_iter != end) { 1376 unsigned tid = *pri_iter; 1377 1378 if (commitStatus[tid] == Running || 1379 commitStatus[tid] == Idle || 1380 commitStatus[tid] == FetchTrapPending) { 1381 1382 if (rob->isHeadReady(tid)) { 1383 priority_list.erase(pri_iter); 1384 priority_list.push_back(tid); 1385 1386 return tid; 1387 } 1388 } 1389 1390 pri_iter++; 1391 } 1392 1393 return -1; 1394} 1395 1396template<class Impl> 1397int 1398DefaultCommit<Impl>::oldestReady() 1399{ 1400 unsigned oldest = 0; 1401 bool first = true; 1402 1403 std::list<unsigned>::iterator threads = activeThreads->begin(); 1404 std::list<unsigned>::iterator end = activeThreads->end(); 1405 1406 while (threads != end) { 1407 unsigned tid = *threads++; 1408 1409 if (!rob->isEmpty(tid) && 1410 (commitStatus[tid] == Running || 1411 commitStatus[tid] == Idle || 1412 commitStatus[tid] == FetchTrapPending)) { 1413 1414 if (rob->isHeadReady(tid)) { 1415 1416 DynInstPtr head_inst = rob->readHeadInst(tid); 1417 1418 if (first) { 1419 oldest = tid; 1420 first = false; 1421 } else if (head_inst->seqNum < oldest) { 1422 oldest = tid; 1423 } 1424 } 1425 } 1426 } 1427 1428 if (!first) { 1429 return oldest; 1430 } else { 1431 return -1; 1432 } 1433} 1434