commit_impl.hh revision 2674:6d4afef73a20
1/* 2 * Copyright (c) 2004-2006 The Regents of The University of Michigan 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions are 7 * met: redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer; 9 * redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution; 12 * neither the name of the copyright holders nor the names of its 13 * contributors may be used to endorse or promote products derived from 14 * this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 * 28 * Authors: Kevin Lim 29 */ 30 31#include <algorithm> 32#include <string> 33 34#include "base/loader/symtab.hh" 35#include "base/timebuf.hh" 36#include "cpu/checker/cpu.hh" 37#include "cpu/exetrace.hh" 38#include "cpu/o3/commit.hh" 39#include "cpu/o3/thread_state.hh" 40 41using namespace std; 42 43template <class Impl> 44DefaultCommit<Impl>::TrapEvent::TrapEvent(DefaultCommit<Impl> *_commit, 45 unsigned _tid) 46 : Event(&mainEventQueue, CPU_Tick_Pri), commit(_commit), tid(_tid) 47{ 48 this->setFlags(Event::AutoDelete); 49} 50 51template <class Impl> 52void 53DefaultCommit<Impl>::TrapEvent::process() 54{ 55 // This will get reset by commit if it was switched out at the 56 // time of this event processing. 57 commit->trapSquash[tid] = true; 58} 59 60template <class Impl> 61const char * 62DefaultCommit<Impl>::TrapEvent::description() 63{ 64 return "Trap event"; 65} 66 67template <class Impl> 68DefaultCommit<Impl>::DefaultCommit(Params *params) 69 : squashCounter(0), 70 iewToCommitDelay(params->iewToCommitDelay), 71 commitToIEWDelay(params->commitToIEWDelay), 72 renameToROBDelay(params->renameToROBDelay), 73 fetchToCommitDelay(params->commitToFetchDelay), 74 renameWidth(params->renameWidth), 75 iewWidth(params->executeWidth), 76 commitWidth(params->commitWidth), 77 numThreads(params->numberOfThreads), 78 switchedOut(false), 79 trapLatency(params->trapLatency), 80 fetchTrapLatency(params->fetchTrapLatency) 81{ 82 _status = Active; 83 _nextStatus = Inactive; 84 string policy = params->smtCommitPolicy; 85 86 //Convert string to lowercase 87 std::transform(policy.begin(), policy.end(), policy.begin(), 88 (int(*)(int)) tolower); 89 90 //Assign commit policy 91 if (policy == "aggressive"){ 92 commitPolicy = Aggressive; 93 94 DPRINTF(Commit,"Commit Policy set to Aggressive."); 95 } else if (policy == "roundrobin"){ 96 commitPolicy = RoundRobin; 97 98 //Set-Up Priority List 99 for (int tid=0; tid < numThreads; tid++) { 100 priority_list.push_back(tid); 101 } 102 103 DPRINTF(Commit,"Commit Policy set to Round Robin."); 104 } else if (policy == "oldestready"){ 105 commitPolicy = OldestReady; 106 107 DPRINTF(Commit,"Commit Policy set to Oldest Ready."); 108 } else { 109 assert(0 && "Invalid SMT Commit Policy. Options Are: {Aggressive," 110 "RoundRobin,OldestReady}"); 111 } 112 113 for (int i=0; i < numThreads; i++) { 114 commitStatus[i] = Idle; 115 changedROBNumEntries[i] = false; 116 trapSquash[i] = false; 117 xcSquash[i] = false; 118 } 119 120 fetchFaultTick = 0; 121 fetchTrapWait = 0; 122} 123 124template <class Impl> 125std::string 126DefaultCommit<Impl>::name() const 127{ 128 return cpu->name() + ".commit"; 129} 130 131template <class Impl> 132void 133DefaultCommit<Impl>::regStats() 134{ 135 using namespace Stats; 136 commitCommittedInsts 137 .name(name() + ".commitCommittedInsts") 138 .desc("The number of committed instructions") 139 .prereq(commitCommittedInsts); 140 commitSquashedInsts 141 .name(name() + ".commitSquashedInsts") 142 .desc("The number of squashed insts skipped by commit") 143 .prereq(commitSquashedInsts); 144 commitSquashEvents 145 .name(name() + ".commitSquashEvents") 146 .desc("The number of times commit is told to squash") 147 .prereq(commitSquashEvents); 148 commitNonSpecStalls 149 .name(name() + ".commitNonSpecStalls") 150 .desc("The number of times commit has been forced to stall to " 151 "communicate backwards") 152 .prereq(commitNonSpecStalls); 153 branchMispredicts 154 .name(name() + ".branchMispredicts") 155 .desc("The number of times a branch was mispredicted") 156 .prereq(branchMispredicts); 157 numCommittedDist 158 .init(0,commitWidth,1) 159 .name(name() + ".COM:committed_per_cycle") 160 .desc("Number of insts commited each cycle") 161 .flags(Stats::pdf) 162 ; 163 164 statComInst 165 .init(cpu->number_of_threads) 166 .name(name() + ".COM:count") 167 .desc("Number of instructions committed") 168 .flags(total) 169 ; 170 171 statComSwp 172 .init(cpu->number_of_threads) 173 .name(name() + ".COM:swp_count") 174 .desc("Number of s/w prefetches committed") 175 .flags(total) 176 ; 177 178 statComRefs 179 .init(cpu->number_of_threads) 180 .name(name() + ".COM:refs") 181 .desc("Number of memory references committed") 182 .flags(total) 183 ; 184 185 statComLoads 186 .init(cpu->number_of_threads) 187 .name(name() + ".COM:loads") 188 .desc("Number of loads committed") 189 .flags(total) 190 ; 191 192 statComMembars 193 .init(cpu->number_of_threads) 194 .name(name() + ".COM:membars") 195 .desc("Number of memory barriers committed") 196 .flags(total) 197 ; 198 199 statComBranches 200 .init(cpu->number_of_threads) 201 .name(name() + ".COM:branches") 202 .desc("Number of branches committed") 203 .flags(total) 204 ; 205 206 // 207 // Commit-Eligible instructions... 208 // 209 // -> The number of instructions eligible to commit in those 210 // cycles where we reached our commit BW limit (less the number 211 // actually committed) 212 // 213 // -> The average value is computed over ALL CYCLES... not just 214 // the BW limited cycles 215 // 216 // -> The standard deviation is computed only over cycles where 217 // we reached the BW limit 218 // 219 commitEligible 220 .init(cpu->number_of_threads) 221 .name(name() + ".COM:bw_limited") 222 .desc("number of insts not committed due to BW limits") 223 .flags(total) 224 ; 225 226 commitEligibleSamples 227 .name(name() + ".COM:bw_lim_events") 228 .desc("number cycles where commit BW limit reached") 229 ; 230} 231 232template <class Impl> 233void 234DefaultCommit<Impl>::setCPU(FullCPU *cpu_ptr) 235{ 236 DPRINTF(Commit, "Commit: Setting CPU pointer.\n"); 237 cpu = cpu_ptr; 238 239 // Commit must broadcast the number of free entries it has at the start of 240 // the simulation, so it starts as active. 241 cpu->activateStage(FullCPU::CommitIdx); 242 243 trapLatency = cpu->cycles(trapLatency); 244 fetchTrapLatency = cpu->cycles(fetchTrapLatency); 245} 246 247template <class Impl> 248void 249DefaultCommit<Impl>::setThreads(vector<Thread *> &threads) 250{ 251 thread = threads; 252} 253 254template <class Impl> 255void 256DefaultCommit<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr) 257{ 258 DPRINTF(Commit, "Commit: Setting time buffer pointer.\n"); 259 timeBuffer = tb_ptr; 260 261 // Setup wire to send information back to IEW. 262 toIEW = timeBuffer->getWire(0); 263 264 // Setup wire to read data from IEW (for the ROB). 265 robInfoFromIEW = timeBuffer->getWire(-iewToCommitDelay); 266} 267 268template <class Impl> 269void 270DefaultCommit<Impl>::setFetchQueue(TimeBuffer<FetchStruct> *fq_ptr) 271{ 272 DPRINTF(Commit, "Commit: Setting fetch queue pointer.\n"); 273 fetchQueue = fq_ptr; 274 275 // Setup wire to get instructions from rename (for the ROB). 276 fromFetch = fetchQueue->getWire(-fetchToCommitDelay); 277} 278 279template <class Impl> 280void 281DefaultCommit<Impl>::setRenameQueue(TimeBuffer<RenameStruct> *rq_ptr) 282{ 283 DPRINTF(Commit, "Commit: Setting rename queue pointer.\n"); 284 renameQueue = rq_ptr; 285 286 // Setup wire to get instructions from rename (for the ROB). 287 fromRename = renameQueue->getWire(-renameToROBDelay); 288} 289 290template <class Impl> 291void 292DefaultCommit<Impl>::setIEWQueue(TimeBuffer<IEWStruct> *iq_ptr) 293{ 294 DPRINTF(Commit, "Commit: Setting IEW queue pointer.\n"); 295 iewQueue = iq_ptr; 296 297 // Setup wire to get instructions from IEW. 298 fromIEW = iewQueue->getWire(-iewToCommitDelay); 299} 300 301template <class Impl> 302void 303DefaultCommit<Impl>::setFetchStage(Fetch *fetch_stage) 304{ 305 fetchStage = fetch_stage; 306} 307 308template <class Impl> 309void 310DefaultCommit<Impl>::setIEWStage(IEW *iew_stage) 311{ 312 iewStage = iew_stage; 313} 314 315template<class Impl> 316void 317DefaultCommit<Impl>::setActiveThreads(list<unsigned> *at_ptr) 318{ 319 DPRINTF(Commit, "Commit: Setting active threads list pointer.\n"); 320 activeThreads = at_ptr; 321} 322 323template <class Impl> 324void 325DefaultCommit<Impl>::setRenameMap(RenameMap rm_ptr[]) 326{ 327 DPRINTF(Commit, "Setting rename map pointers.\n"); 328 329 for (int i=0; i < numThreads; i++) { 330 renameMap[i] = &rm_ptr[i]; 331 } 332} 333 334template <class Impl> 335void 336DefaultCommit<Impl>::setROB(ROB *rob_ptr) 337{ 338 DPRINTF(Commit, "Commit: Setting ROB pointer.\n"); 339 rob = rob_ptr; 340} 341 342template <class Impl> 343void 344DefaultCommit<Impl>::initStage() 345{ 346 rob->setActiveThreads(activeThreads); 347 rob->resetEntries(); 348 349 // Broadcast the number of free entries. 350 for (int i=0; i < numThreads; i++) { 351 toIEW->commitInfo[i].usedROB = true; 352 toIEW->commitInfo[i].freeROBEntries = rob->numFreeEntries(i); 353 } 354 355 cpu->activityThisCycle(); 356} 357 358template <class Impl> 359void 360DefaultCommit<Impl>::switchOut() 361{ 362 switchPending = true; 363} 364 365template <class Impl> 366void 367DefaultCommit<Impl>::doSwitchOut() 368{ 369 switchedOut = true; 370 switchPending = false; 371 rob->switchOut(); 372} 373 374template <class Impl> 375void 376DefaultCommit<Impl>::takeOverFrom() 377{ 378 switchedOut = false; 379 _status = Active; 380 _nextStatus = Inactive; 381 for (int i=0; i < numThreads; i++) { 382 commitStatus[i] = Idle; 383 changedROBNumEntries[i] = false; 384 trapSquash[i] = false; 385 xcSquash[i] = false; 386 } 387 squashCounter = 0; 388 rob->takeOverFrom(); 389} 390 391template <class Impl> 392void 393DefaultCommit<Impl>::updateStatus() 394{ 395 // reset ROB changed variable 396 list<unsigned>::iterator threads = (*activeThreads).begin(); 397 while (threads != (*activeThreads).end()) { 398 unsigned tid = *threads++; 399 changedROBNumEntries[tid] = false; 400 401 // Also check if any of the threads has a trap pending 402 if (commitStatus[tid] == TrapPending || 403 commitStatus[tid] == FetchTrapPending) { 404 _nextStatus = Active; 405 } 406 } 407 408 if (_nextStatus == Inactive && _status == Active) { 409 DPRINTF(Activity, "Deactivating stage.\n"); 410 cpu->deactivateStage(FullCPU::CommitIdx); 411 } else if (_nextStatus == Active && _status == Inactive) { 412 DPRINTF(Activity, "Activating stage.\n"); 413 cpu->activateStage(FullCPU::CommitIdx); 414 } 415 416 _status = _nextStatus; 417} 418 419template <class Impl> 420void 421DefaultCommit<Impl>::setNextStatus() 422{ 423 int squashes = 0; 424 425 list<unsigned>::iterator threads = (*activeThreads).begin(); 426 427 while (threads != (*activeThreads).end()) { 428 unsigned tid = *threads++; 429 430 if (commitStatus[tid] == ROBSquashing) { 431 squashes++; 432 } 433 } 434 435 assert(squashes == squashCounter); 436 437 // If commit is currently squashing, then it will have activity for the 438 // next cycle. Set its next status as active. 439 if (squashCounter) { 440 _nextStatus = Active; 441 } 442} 443 444template <class Impl> 445bool 446DefaultCommit<Impl>::changedROBEntries() 447{ 448 list<unsigned>::iterator threads = (*activeThreads).begin(); 449 450 while (threads != (*activeThreads).end()) { 451 unsigned tid = *threads++; 452 453 if (changedROBNumEntries[tid]) { 454 return true; 455 } 456 } 457 458 return false; 459} 460 461template <class Impl> 462unsigned 463DefaultCommit<Impl>::numROBFreeEntries(unsigned tid) 464{ 465 return rob->numFreeEntries(tid); 466} 467 468template <class Impl> 469void 470DefaultCommit<Impl>::generateTrapEvent(unsigned tid) 471{ 472 DPRINTF(Commit, "Generating trap event for [tid:%i]\n", tid); 473 474 TrapEvent *trap = new TrapEvent(this, tid); 475 476 trap->schedule(curTick + trapLatency); 477 478 thread[tid]->trapPending = true; 479} 480 481template <class Impl> 482void 483DefaultCommit<Impl>::generateXCEvent(unsigned tid) 484{ 485 DPRINTF(Commit, "Generating XC squash event for [tid:%i]\n", tid); 486 487 xcSquash[tid] = true; 488} 489 490template <class Impl> 491void 492DefaultCommit<Impl>::squashAll(unsigned tid) 493{ 494 // If we want to include the squashing instruction in the squash, 495 // then use one older sequence number. 496 // Hopefully this doesn't mess things up. Basically I want to squash 497 // all instructions of this thread. 498 InstSeqNum squashed_inst = rob->isEmpty() ? 499 0 : rob->readHeadInst(tid)->seqNum - 1;; 500 501 // All younger instructions will be squashed. Set the sequence 502 // number as the youngest instruction in the ROB (0 in this case. 503 // Hopefully nothing breaks.) 504 youngestSeqNum[tid] = 0; 505 506 rob->squash(squashed_inst, tid); 507 changedROBNumEntries[tid] = true; 508 509 // Send back the sequence number of the squashed instruction. 510 toIEW->commitInfo[tid].doneSeqNum = squashed_inst; 511 512 // Send back the squash signal to tell stages that they should 513 // squash. 514 toIEW->commitInfo[tid].squash = true; 515 516 // Send back the rob squashing signal so other stages know that 517 // the ROB is in the process of squashing. 518 toIEW->commitInfo[tid].robSquashing = true; 519 520 toIEW->commitInfo[tid].branchMispredict = false; 521 522 toIEW->commitInfo[tid].nextPC = PC[tid]; 523} 524 525template <class Impl> 526void 527DefaultCommit<Impl>::squashFromTrap(unsigned tid) 528{ 529 squashAll(tid); 530 531 DPRINTF(Commit, "Squashing from trap, restarting at PC %#x\n", PC[tid]); 532 533 thread[tid]->trapPending = false; 534 thread[tid]->inSyscall = false; 535 536 trapSquash[tid] = false; 537 538 commitStatus[tid] = ROBSquashing; 539 cpu->activityThisCycle(); 540 541 ++squashCounter; 542} 543 544template <class Impl> 545void 546DefaultCommit<Impl>::squashFromXC(unsigned tid) 547{ 548 squashAll(tid); 549 550 DPRINTF(Commit, "Squashing from XC, restarting at PC %#x\n", PC[tid]); 551 552 thread[tid]->inSyscall = false; 553 assert(!thread[tid]->trapPending); 554 555 commitStatus[tid] = ROBSquashing; 556 cpu->activityThisCycle(); 557 558 xcSquash[tid] = false; 559 560 ++squashCounter; 561} 562 563template <class Impl> 564void 565DefaultCommit<Impl>::tick() 566{ 567 wroteToTimeBuffer = false; 568 _nextStatus = Inactive; 569 570 if (switchPending && rob->isEmpty() && !iewStage->hasStoresToWB()) { 571 cpu->signalSwitched(); 572 return; 573 } 574 575 list<unsigned>::iterator threads = (*activeThreads).begin(); 576 577 // Check if any of the threads are done squashing. Change the 578 // status if they are done. 579 while (threads != (*activeThreads).end()) { 580 unsigned tid = *threads++; 581 582 if (commitStatus[tid] == ROBSquashing) { 583 584 if (rob->isDoneSquashing(tid)) { 585 commitStatus[tid] = Running; 586 --squashCounter; 587 } else { 588 DPRINTF(Commit,"[tid:%u]: Still Squashing, cannot commit any" 589 "insts this cycle.\n", tid); 590 } 591 } 592 } 593 594 commit(); 595 596 markCompletedInsts(); 597 598 threads = (*activeThreads).begin(); 599 600 while (threads != (*activeThreads).end()) { 601 unsigned tid = *threads++; 602 603 if (!rob->isEmpty(tid) && rob->readHeadInst(tid)->readyToCommit()) { 604 // The ROB has more instructions it can commit. Its next status 605 // will be active. 606 _nextStatus = Active; 607 608 DynInstPtr inst = rob->readHeadInst(tid); 609 610 DPRINTF(Commit,"[tid:%i]: Instruction [sn:%lli] PC %#x is head of" 611 " ROB and ready to commit\n", 612 tid, inst->seqNum, inst->readPC()); 613 614 } else if (!rob->isEmpty(tid)) { 615 DynInstPtr inst = rob->readHeadInst(tid); 616 617 DPRINTF(Commit,"[tid:%i]: Can't commit, Instruction [sn:%lli] PC " 618 "%#x is head of ROB and not ready\n", 619 tid, inst->seqNum, inst->readPC()); 620 } 621 622 DPRINTF(Commit, "[tid:%i]: ROB has %d insts & %d free entries.\n", 623 tid, rob->countInsts(tid), rob->numFreeEntries(tid)); 624 } 625 626 627 if (wroteToTimeBuffer) { 628 DPRINTF(Activity, "Activity This Cycle.\n"); 629 cpu->activityThisCycle(); 630 } 631 632 updateStatus(); 633} 634 635template <class Impl> 636void 637DefaultCommit<Impl>::commit() 638{ 639 640 ////////////////////////////////////// 641 // Check for interrupts 642 ////////////////////////////////////// 643 644#if FULL_SYSTEM 645 // Process interrupts if interrupts are enabled, not in PAL mode, 646 // and no other traps or external squashes are currently pending. 647 // @todo: Allow other threads to handle interrupts. 648 if (cpu->checkInterrupts && 649 cpu->check_interrupts() && 650 !cpu->inPalMode(readPC()) && 651 !trapSquash[0] && 652 !xcSquash[0]) { 653 // Tell fetch that there is an interrupt pending. This will 654 // make fetch wait until it sees a non PAL-mode PC, at which 655 // point it stops fetching instructions. 656 toIEW->commitInfo[0].interruptPending = true; 657 658 // Wait until the ROB is empty and all stores have drained in 659 // order to enter the interrupt. 660 if (rob->isEmpty() && !iewStage->hasStoresToWB()) { 661 // Not sure which thread should be the one to interrupt. For now 662 // always do thread 0. 663 assert(!thread[0]->inSyscall); 664 thread[0]->inSyscall = true; 665 666 // CPU will handle implementation of the interrupt. 667 cpu->processInterrupts(); 668 669 // Now squash or record that I need to squash this cycle. 670 commitStatus[0] = TrapPending; 671 672 // Exit state update mode to avoid accidental updating. 673 thread[0]->inSyscall = false; 674 675 // Generate trap squash event. 676 generateTrapEvent(0); 677 678 toIEW->commitInfo[0].clearInterrupt = true; 679 680 DPRINTF(Commit, "Interrupt detected.\n"); 681 } else { 682 DPRINTF(Commit, "Interrupt pending, waiting for ROB to empty.\n"); 683 } 684 } 685#endif // FULL_SYSTEM 686 687 //////////////////////////////////// 688 // Check for any possible squashes, handle them first 689 //////////////////////////////////// 690 691 list<unsigned>::iterator threads = (*activeThreads).begin(); 692 693 while (threads != (*activeThreads).end()) { 694 unsigned tid = *threads++; 695/* 696 if (fromFetch->fetchFault && commitStatus[0] != TrapPending) { 697 // Record the fault. Wait until it's empty in the ROB. 698 // Then handle the trap. Ignore it if there's already a 699 // trap pending as fetch will be redirected. 700 fetchFault = fromFetch->fetchFault; 701 fetchFaultTick = curTick + fetchTrapLatency; 702 commitStatus[0] = FetchTrapPending; 703 DPRINTF(Commit, "Fault from fetch recorded. Will trap if the " 704 "ROB empties without squashing the fault.\n"); 705 fetchTrapWait = 0; 706 } 707 708 // Fetch may tell commit to clear the trap if it's been squashed. 709 if (fromFetch->clearFetchFault) { 710 DPRINTF(Commit, "Received clear fetch fault signal\n"); 711 fetchTrapWait = 0; 712 if (commitStatus[0] == FetchTrapPending) { 713 DPRINTF(Commit, "Clearing fault from fetch\n"); 714 commitStatus[0] = Running; 715 } 716 } 717*/ 718 // Not sure which one takes priority. I think if we have 719 // both, that's a bad sign. 720 if (trapSquash[tid] == true) { 721 assert(!xcSquash[tid]); 722 squashFromTrap(tid); 723 } else if (xcSquash[tid] == true) { 724 squashFromXC(tid); 725 } 726 727 // Squashed sequence number must be older than youngest valid 728 // instruction in the ROB. This prevents squashes from younger 729 // instructions overriding squashes from older instructions. 730 if (fromIEW->squash[tid] && 731 commitStatus[tid] != TrapPending && 732 fromIEW->squashedSeqNum[tid] <= youngestSeqNum[tid]) { 733 734 DPRINTF(Commit, "[tid:%i]: Squashing due to PC %#x [sn:%i]\n", 735 tid, 736 fromIEW->mispredPC[tid], 737 fromIEW->squashedSeqNum[tid]); 738 739 DPRINTF(Commit, "[tid:%i]: Redirecting to PC %#x\n", 740 tid, 741 fromIEW->nextPC[tid]); 742 743 commitStatus[tid] = ROBSquashing; 744 745 ++squashCounter; 746 747 // If we want to include the squashing instruction in the squash, 748 // then use one older sequence number. 749 InstSeqNum squashed_inst = fromIEW->squashedSeqNum[tid]; 750 751 if (fromIEW->includeSquashInst[tid] == true) 752 squashed_inst--; 753 754 // All younger instructions will be squashed. Set the sequence 755 // number as the youngest instruction in the ROB. 756 youngestSeqNum[tid] = squashed_inst; 757 758 rob->squash(squashed_inst, tid); 759 changedROBNumEntries[tid] = true; 760 761 toIEW->commitInfo[tid].doneSeqNum = squashed_inst; 762 763 toIEW->commitInfo[tid].squash = true; 764 765 // Send back the rob squashing signal so other stages know that 766 // the ROB is in the process of squashing. 767 toIEW->commitInfo[tid].robSquashing = true; 768 769 toIEW->commitInfo[tid].branchMispredict = 770 fromIEW->branchMispredict[tid]; 771 772 toIEW->commitInfo[tid].branchTaken = 773 fromIEW->branchTaken[tid]; 774 775 toIEW->commitInfo[tid].nextPC = fromIEW->nextPC[tid]; 776 777 toIEW->commitInfo[tid].mispredPC = fromIEW->mispredPC[tid]; 778 779 if (toIEW->commitInfo[tid].branchMispredict) { 780 ++branchMispredicts; 781 } 782 } 783 784 } 785 786 setNextStatus(); 787 788 if (squashCounter != numThreads) { 789 // If we're not currently squashing, then get instructions. 790 getInsts(); 791 792 // Try to commit any instructions. 793 commitInsts(); 794 } 795 796 //Check for any activity 797 threads = (*activeThreads).begin(); 798 799 while (threads != (*activeThreads).end()) { 800 unsigned tid = *threads++; 801 802 if (changedROBNumEntries[tid]) { 803 toIEW->commitInfo[tid].usedROB = true; 804 toIEW->commitInfo[tid].freeROBEntries = rob->numFreeEntries(tid); 805 806 if (rob->isEmpty(tid)) { 807 toIEW->commitInfo[tid].emptyROB = true; 808 } 809 810 wroteToTimeBuffer = true; 811 changedROBNumEntries[tid] = false; 812 } 813 } 814} 815 816template <class Impl> 817void 818DefaultCommit<Impl>::commitInsts() 819{ 820 //////////////////////////////////// 821 // Handle commit 822 // Note that commit will be handled prior to putting new 823 // instructions in the ROB so that the ROB only tries to commit 824 // instructions it has in this current cycle, and not instructions 825 // it is writing in during this cycle. Can't commit and squash 826 // things at the same time... 827 //////////////////////////////////// 828 829 DPRINTF(Commit, "Trying to commit instructions in the ROB.\n"); 830 831 unsigned num_committed = 0; 832 833 DynInstPtr head_inst; 834 835 // Commit as many instructions as possible until the commit bandwidth 836 // limit is reached, or it becomes impossible to commit any more. 837 while (num_committed < commitWidth) { 838 int commit_thread = getCommittingThread(); 839 840 if (commit_thread == -1 || !rob->isHeadReady(commit_thread)) 841 break; 842 843 head_inst = rob->readHeadInst(commit_thread); 844 845 int tid = head_inst->threadNumber; 846 847 assert(tid == commit_thread); 848 849 DPRINTF(Commit, "Trying to commit head instruction, [sn:%i] [tid:%i]\n", 850 head_inst->seqNum, tid); 851 852 // If the head instruction is squashed, it is ready to retire 853 // (be removed from the ROB) at any time. 854 if (head_inst->isSquashed()) { 855 856 DPRINTF(Commit, "Retiring squashed instruction from " 857 "ROB.\n"); 858 859 rob->retireHead(commit_thread); 860 861 ++commitSquashedInsts; 862 863 // Record that the number of ROB entries has changed. 864 changedROBNumEntries[tid] = true; 865 } else { 866 PC[tid] = head_inst->readPC(); 867 nextPC[tid] = head_inst->readNextPC(); 868 869 // Increment the total number of non-speculative instructions 870 // executed. 871 // Hack for now: it really shouldn't happen until after the 872 // commit is deemed to be successful, but this count is needed 873 // for syscalls. 874 thread[tid]->funcExeInst++; 875 876 // Try to commit the head instruction. 877 bool commit_success = commitHead(head_inst, num_committed); 878 879 if (commit_success) { 880 ++num_committed; 881 882 changedROBNumEntries[tid] = true; 883 884 // Set the doneSeqNum to the youngest committed instruction. 885 toIEW->commitInfo[tid].doneSeqNum = head_inst->seqNum; 886 887 ++commitCommittedInsts; 888 889 // To match the old model, don't count nops and instruction 890 // prefetches towards the total commit count. 891 if (!head_inst->isNop() && !head_inst->isInstPrefetch()) { 892 cpu->instDone(tid); 893 } 894 895 PC[tid] = nextPC[tid]; 896 nextPC[tid] = nextPC[tid] + sizeof(TheISA::MachInst); 897#if FULL_SYSTEM 898 int count = 0; 899 Addr oldpc; 900 do { 901 // Debug statement. Checks to make sure we're not 902 // currently updating state while handling PC events. 903 if (count == 0) 904 assert(!thread[tid]->inSyscall && 905 !thread[tid]->trapPending); 906 oldpc = PC[tid]; 907 cpu->system->pcEventQueue.service( 908 thread[tid]->getXCProxy()); 909 count++; 910 } while (oldpc != PC[tid]); 911 if (count > 1) { 912 DPRINTF(Commit, "PC skip function event, stopping commit\n"); 913 break; 914 } 915#endif 916 } else { 917 DPRINTF(Commit, "Unable to commit head instruction PC:%#x " 918 "[tid:%i] [sn:%i].\n", 919 head_inst->readPC(), tid ,head_inst->seqNum); 920 break; 921 } 922 } 923 } 924 925 DPRINTF(CommitRate, "%i\n", num_committed); 926 numCommittedDist.sample(num_committed); 927 928 if (num_committed == commitWidth) { 929 commitEligibleSamples++; 930 } 931} 932 933template <class Impl> 934bool 935DefaultCommit<Impl>::commitHead(DynInstPtr &head_inst, unsigned inst_num) 936{ 937 assert(head_inst); 938 939 int tid = head_inst->threadNumber; 940 941 // If the instruction is not executed yet, then it will need extra 942 // handling. Signal backwards that it should be executed. 943 if (!head_inst->isExecuted()) { 944 // Keep this number correct. We have not yet actually executed 945 // and committed this instruction. 946 thread[tid]->funcExeInst--; 947 948 head_inst->reachedCommit = true; 949 950 if (head_inst->isNonSpeculative() || 951 head_inst->isStoreConditional() || 952 head_inst->isMemBarrier() || 953 head_inst->isWriteBarrier()) { 954 955 DPRINTF(Commit, "Encountered a barrier or non-speculative " 956 "instruction [sn:%lli] at the head of the ROB, PC %#x.\n", 957 head_inst->seqNum, head_inst->readPC()); 958 959#if !FULL_SYSTEM 960 // Hack to make sure syscalls/memory barriers/quiesces 961 // aren't executed until all stores write back their data. 962 // This direct communication shouldn't be used for 963 // anything other than this. 964 if (inst_num > 0 || iewStage->hasStoresToWB()) 965#else 966 if ((head_inst->isMemBarrier() || head_inst->isWriteBarrier() || 967 head_inst->isQuiesce()) && 968 iewStage->hasStoresToWB()) 969#endif 970 { 971 DPRINTF(Commit, "Waiting for all stores to writeback.\n"); 972 return false; 973 } 974 975 toIEW->commitInfo[tid].nonSpecSeqNum = head_inst->seqNum; 976 977 // Change the instruction so it won't try to commit again until 978 // it is executed. 979 head_inst->clearCanCommit(); 980 981 ++commitNonSpecStalls; 982 983 return false; 984 } else if (head_inst->isLoad()) { 985 DPRINTF(Commit, "[sn:%lli]: Uncached load, PC %#x.\n", 986 head_inst->seqNum, head_inst->readPC()); 987 988 // Send back the non-speculative instruction's sequence 989 // number. Tell the lsq to re-execute the load. 990 toIEW->commitInfo[tid].nonSpecSeqNum = head_inst->seqNum; 991 toIEW->commitInfo[tid].uncached = true; 992 toIEW->commitInfo[tid].uncachedLoad = head_inst; 993 994 head_inst->clearCanCommit(); 995 996 return false; 997 } else { 998 panic("Trying to commit un-executed instruction " 999 "of unknown type!\n"); 1000 } 1001 } 1002 1003 if (head_inst->isThreadSync()) { 1004 // Not handled for now. 1005 panic("Thread sync instructions are not handled yet.\n"); 1006 } 1007 1008 // Stores mark themselves as completed. 1009 if (!head_inst->isStore()) { 1010 head_inst->setCompleted(); 1011 } 1012 1013 // Use checker prior to updating anything due to traps or PC 1014 // based events. 1015 if (cpu->checker) { 1016 cpu->checker->tick(head_inst); 1017 } 1018 1019 // Check if the instruction caused a fault. If so, trap. 1020 Fault inst_fault = head_inst->getFault(); 1021 1022 if (inst_fault != NoFault) { 1023 head_inst->setCompleted(); 1024#if FULL_SYSTEM 1025 DPRINTF(Commit, "Inst [sn:%lli] PC %#x has a fault\n", 1026 head_inst->seqNum, head_inst->readPC()); 1027 1028 if (iewStage->hasStoresToWB() || inst_num > 0) { 1029 DPRINTF(Commit, "Stores outstanding, fault must wait.\n"); 1030 return false; 1031 } 1032 1033 if (cpu->checker && head_inst->isStore()) { 1034 cpu->checker->tick(head_inst); 1035 } 1036 1037 assert(!thread[tid]->inSyscall); 1038 1039 // Mark that we're in state update mode so that the trap's 1040 // execution doesn't generate extra squashes. 1041 thread[tid]->inSyscall = true; 1042 1043 // DTB will sometimes need the machine instruction for when 1044 // faults happen. So we will set it here, prior to the DTB 1045 // possibly needing it for its fault. 1046 thread[tid]->setInst( 1047 static_cast<TheISA::MachInst>(head_inst->staticInst->machInst)); 1048 1049 // Execute the trap. Although it's slightly unrealistic in 1050 // terms of timing (as it doesn't wait for the full timing of 1051 // the trap event to complete before updating state), it's 1052 // needed to update the state as soon as possible. This 1053 // prevents external agents from changing any specific state 1054 // that the trap need. 1055 cpu->trap(inst_fault, tid); 1056 1057 // Exit state update mode to avoid accidental updating. 1058 thread[tid]->inSyscall = false; 1059 1060 commitStatus[tid] = TrapPending; 1061 1062 // Generate trap squash event. 1063 generateTrapEvent(tid); 1064 1065 return false; 1066#else // !FULL_SYSTEM 1067 panic("fault (%d) detected @ PC %08p", inst_fault, 1068 head_inst->PC); 1069#endif // FULL_SYSTEM 1070 } 1071 1072 updateComInstStats(head_inst); 1073 1074 if (head_inst->traceData) { 1075 head_inst->traceData->setFetchSeq(head_inst->seqNum); 1076 head_inst->traceData->setCPSeq(thread[tid]->numInst); 1077 head_inst->traceData->finalize(); 1078 head_inst->traceData = NULL; 1079 } 1080 1081 // Update the commit rename map 1082 for (int i = 0; i < head_inst->numDestRegs(); i++) { 1083 renameMap[tid]->setEntry(head_inst->destRegIdx(i), 1084 head_inst->renamedDestRegIdx(i)); 1085 } 1086 1087 // Finally clear the head ROB entry. 1088 rob->retireHead(tid); 1089 1090 // Return true to indicate that we have committed an instruction. 1091 return true; 1092} 1093 1094template <class Impl> 1095void 1096DefaultCommit<Impl>::getInsts() 1097{ 1098 // Read any renamed instructions and place them into the ROB. 1099 int insts_to_process = min((int)renameWidth, fromRename->size); 1100 1101 for (int inst_num = 0; inst_num < insts_to_process; ++inst_num) 1102 { 1103 DynInstPtr inst = fromRename->insts[inst_num]; 1104 int tid = inst->threadNumber; 1105 1106 if (!inst->isSquashed() && 1107 commitStatus[tid] != ROBSquashing) { 1108 changedROBNumEntries[tid] = true; 1109 1110 DPRINTF(Commit, "Inserting PC %#x [sn:%i] [tid:%i] into ROB.\n", 1111 inst->readPC(), inst->seqNum, tid); 1112 1113 rob->insertInst(inst); 1114 1115 assert(rob->getThreadEntries(tid) <= rob->getMaxEntries(tid)); 1116 1117 youngestSeqNum[tid] = inst->seqNum; 1118 } else { 1119 DPRINTF(Commit, "Instruction PC %#x [sn:%i] [tid:%i] was " 1120 "squashed, skipping.\n", 1121 inst->readPC(), inst->seqNum, tid); 1122 } 1123 } 1124} 1125 1126template <class Impl> 1127void 1128DefaultCommit<Impl>::markCompletedInsts() 1129{ 1130 // Grab completed insts out of the IEW instruction queue, and mark 1131 // instructions completed within the ROB. 1132 for (int inst_num = 0; 1133 inst_num < fromIEW->size && fromIEW->insts[inst_num]; 1134 ++inst_num) 1135 { 1136 if (!fromIEW->insts[inst_num]->isSquashed()) { 1137 DPRINTF(Commit, "[tid:%i]: Marking PC %#x, [sn:%lli] ready " 1138 "within ROB.\n", 1139 fromIEW->insts[inst_num]->threadNumber, 1140 fromIEW->insts[inst_num]->readPC(), 1141 fromIEW->insts[inst_num]->seqNum); 1142 1143 // Mark the instruction as ready to commit. 1144 fromIEW->insts[inst_num]->setCanCommit(); 1145 } 1146 } 1147} 1148 1149template <class Impl> 1150bool 1151DefaultCommit<Impl>::robDoneSquashing() 1152{ 1153 list<unsigned>::iterator threads = (*activeThreads).begin(); 1154 1155 while (threads != (*activeThreads).end()) { 1156 unsigned tid = *threads++; 1157 1158 if (!rob->isDoneSquashing(tid)) 1159 return false; 1160 } 1161 1162 return true; 1163} 1164 1165template <class Impl> 1166void 1167DefaultCommit<Impl>::updateComInstStats(DynInstPtr &inst) 1168{ 1169 unsigned thread = inst->threadNumber; 1170 1171 // 1172 // Pick off the software prefetches 1173 // 1174#ifdef TARGET_ALPHA 1175 if (inst->isDataPrefetch()) { 1176 statComSwp[thread]++; 1177 } else { 1178 statComInst[thread]++; 1179 } 1180#else 1181 statComInst[thread]++; 1182#endif 1183 1184 // 1185 // Control Instructions 1186 // 1187 if (inst->isControl()) 1188 statComBranches[thread]++; 1189 1190 // 1191 // Memory references 1192 // 1193 if (inst->isMemRef()) { 1194 statComRefs[thread]++; 1195 1196 if (inst->isLoad()) { 1197 statComLoads[thread]++; 1198 } 1199 } 1200 1201 if (inst->isMemBarrier()) { 1202 statComMembars[thread]++; 1203 } 1204} 1205 1206//////////////////////////////////////// 1207// // 1208// SMT COMMIT POLICY MAINTAINED HERE // 1209// // 1210//////////////////////////////////////// 1211template <class Impl> 1212int 1213DefaultCommit<Impl>::getCommittingThread() 1214{ 1215 if (numThreads > 1) { 1216 switch (commitPolicy) { 1217 1218 case Aggressive: 1219 //If Policy is Aggressive, commit will call 1220 //this function multiple times per 1221 //cycle 1222 return oldestReady(); 1223 1224 case RoundRobin: 1225 return roundRobin(); 1226 1227 case OldestReady: 1228 return oldestReady(); 1229 1230 default: 1231 return -1; 1232 } 1233 } else { 1234 int tid = (*activeThreads).front(); 1235 1236 if (commitStatus[tid] == Running || 1237 commitStatus[tid] == Idle || 1238 commitStatus[tid] == FetchTrapPending) { 1239 return tid; 1240 } else { 1241 return -1; 1242 } 1243 } 1244} 1245 1246template<class Impl> 1247int 1248DefaultCommit<Impl>::roundRobin() 1249{ 1250 list<unsigned>::iterator pri_iter = priority_list.begin(); 1251 list<unsigned>::iterator end = priority_list.end(); 1252 1253 while (pri_iter != end) { 1254 unsigned tid = *pri_iter; 1255 1256 if (commitStatus[tid] == Running || 1257 commitStatus[tid] == Idle) { 1258 1259 if (rob->isHeadReady(tid)) { 1260 priority_list.erase(pri_iter); 1261 priority_list.push_back(tid); 1262 1263 return tid; 1264 } 1265 } 1266 1267 pri_iter++; 1268 } 1269 1270 return -1; 1271} 1272 1273template<class Impl> 1274int 1275DefaultCommit<Impl>::oldestReady() 1276{ 1277 unsigned oldest = 0; 1278 bool first = true; 1279 1280 list<unsigned>::iterator threads = (*activeThreads).begin(); 1281 1282 while (threads != (*activeThreads).end()) { 1283 unsigned tid = *threads++; 1284 1285 if (!rob->isEmpty(tid) && 1286 (commitStatus[tid] == Running || 1287 commitStatus[tid] == Idle || 1288 commitStatus[tid] == FetchTrapPending)) { 1289 1290 if (rob->isHeadReady(tid)) { 1291 1292 DynInstPtr head_inst = rob->readHeadInst(tid); 1293 1294 if (first) { 1295 oldest = tid; 1296 first = false; 1297 } else if (head_inst->seqNum < oldest) { 1298 oldest = tid; 1299 } 1300 } 1301 } 1302 } 1303 1304 if (!first) { 1305 return oldest; 1306 } else { 1307 return -1; 1308 } 1309} 1310