commit_impl.hh revision 2669
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 29#include <algorithm> 30#include <string> 31 32#include "base/loader/symtab.hh" 33#include "base/timebuf.hh" 34#include "cpu/checker/cpu.hh" 35#include "cpu/exetrace.hh" 36#include "cpu/o3/commit.hh" 37#include "cpu/o3/thread_state.hh" 38 39using namespace std; 40 41template <class Impl> 42DefaultCommit<Impl>::TrapEvent::TrapEvent(DefaultCommit<Impl> *_commit, 43 unsigned _tid) 44 : Event(&mainEventQueue, CPU_Tick_Pri), commit(_commit), tid(_tid) 45{ 46 this->setFlags(Event::AutoDelete); 47} 48 49template <class Impl> 50void 51DefaultCommit<Impl>::TrapEvent::process() 52{ 53 // This will get reset by commit if it was switched out at the 54 // time of this event processing. 55 commit->trapSquash[tid] = true; 56} 57 58template <class Impl> 59const char * 60DefaultCommit<Impl>::TrapEvent::description() 61{ 62 return "Trap event"; 63} 64 65template <class Impl> 66DefaultCommit<Impl>::DefaultCommit(Params *params) 67 : squashCounter(0), 68 iewToCommitDelay(params->iewToCommitDelay), 69 commitToIEWDelay(params->commitToIEWDelay), 70 renameToROBDelay(params->renameToROBDelay), 71 fetchToCommitDelay(params->commitToFetchDelay), 72 renameWidth(params->renameWidth), 73 iewWidth(params->executeWidth), 74 commitWidth(params->commitWidth), 75 numThreads(params->numberOfThreads), 76 switchedOut(false), 77 trapLatency(params->trapLatency), 78 fetchTrapLatency(params->fetchTrapLatency) 79{ 80 _status = Active; 81 _nextStatus = Inactive; 82 string policy = params->smtCommitPolicy; 83 84 //Convert string to lowercase 85 std::transform(policy.begin(), policy.end(), policy.begin(), 86 (int(*)(int)) tolower); 87 88 //Assign commit policy 89 if (policy == "aggressive"){ 90 commitPolicy = Aggressive; 91 92 DPRINTF(Commit,"Commit Policy set to Aggressive."); 93 } else if (policy == "roundrobin"){ 94 commitPolicy = RoundRobin; 95 96 //Set-Up Priority List 97 for (int tid=0; tid < numThreads; tid++) { 98 priority_list.push_back(tid); 99 } 100 101 DPRINTF(Commit,"Commit Policy set to Round Robin."); 102 } else if (policy == "oldestready"){ 103 commitPolicy = OldestReady; 104 105 DPRINTF(Commit,"Commit Policy set to Oldest Ready."); 106 } else { 107 assert(0 && "Invalid SMT Commit Policy. Options Are: {Aggressive," 108 "RoundRobin,OldestReady}"); 109 } 110 111 for (int i=0; i < numThreads; i++) { 112 commitStatus[i] = Idle; 113 changedROBNumEntries[i] = false; 114 trapSquash[i] = false; 115 xcSquash[i] = false; 116 } 117 118 fetchFaultTick = 0; 119 fetchTrapWait = 0; 120} 121 122template <class Impl> 123std::string 124DefaultCommit<Impl>::name() const 125{ 126 return cpu->name() + ".commit"; 127} 128 129template <class Impl> 130void 131DefaultCommit<Impl>::regStats() 132{ 133 using namespace Stats; 134 commitCommittedInsts 135 .name(name() + ".commitCommittedInsts") 136 .desc("The number of committed instructions") 137 .prereq(commitCommittedInsts); 138 commitSquashedInsts 139 .name(name() + ".commitSquashedInsts") 140 .desc("The number of squashed insts skipped by commit") 141 .prereq(commitSquashedInsts); 142 commitSquashEvents 143 .name(name() + ".commitSquashEvents") 144 .desc("The number of times commit is told to squash") 145 .prereq(commitSquashEvents); 146 commitNonSpecStalls 147 .name(name() + ".commitNonSpecStalls") 148 .desc("The number of times commit has been forced to stall to " 149 "communicate backwards") 150 .prereq(commitNonSpecStalls); 151 branchMispredicts 152 .name(name() + ".branchMispredicts") 153 .desc("The number of times a branch was mispredicted") 154 .prereq(branchMispredicts); 155 numCommittedDist 156 .init(0,commitWidth,1) 157 .name(name() + ".COM:committed_per_cycle") 158 .desc("Number of insts commited each cycle") 159 .flags(Stats::pdf) 160 ; 161 162 statComInst 163 .init(cpu->number_of_threads) 164 .name(name() + ".COM:count") 165 .desc("Number of instructions committed") 166 .flags(total) 167 ; 168 169 statComSwp 170 .init(cpu->number_of_threads) 171 .name(name() + ".COM:swp_count") 172 .desc("Number of s/w prefetches committed") 173 .flags(total) 174 ; 175 176 statComRefs 177 .init(cpu->number_of_threads) 178 .name(name() + ".COM:refs") 179 .desc("Number of memory references committed") 180 .flags(total) 181 ; 182 183 statComLoads 184 .init(cpu->number_of_threads) 185 .name(name() + ".COM:loads") 186 .desc("Number of loads committed") 187 .flags(total) 188 ; 189 190 statComMembars 191 .init(cpu->number_of_threads) 192 .name(name() + ".COM:membars") 193 .desc("Number of memory barriers committed") 194 .flags(total) 195 ; 196 197 statComBranches 198 .init(cpu->number_of_threads) 199 .name(name() + ".COM:branches") 200 .desc("Number of branches committed") 201 .flags(total) 202 ; 203 204 // 205 // Commit-Eligible instructions... 206 // 207 // -> The number of instructions eligible to commit in those 208 // cycles where we reached our commit BW limit (less the number 209 // actually committed) 210 // 211 // -> The average value is computed over ALL CYCLES... not just 212 // the BW limited cycles 213 // 214 // -> The standard deviation is computed only over cycles where 215 // we reached the BW limit 216 // 217 commitEligible 218 .init(cpu->number_of_threads) 219 .name(name() + ".COM:bw_limited") 220 .desc("number of insts not committed due to BW limits") 221 .flags(total) 222 ; 223 224 commitEligibleSamples 225 .name(name() + ".COM:bw_lim_events") 226 .desc("number cycles where commit BW limit reached") 227 ; 228} 229 230template <class Impl> 231void 232DefaultCommit<Impl>::setCPU(FullCPU *cpu_ptr) 233{ 234 DPRINTF(Commit, "Commit: Setting CPU pointer.\n"); 235 cpu = cpu_ptr; 236 237 // Commit must broadcast the number of free entries it has at the start of 238 // the simulation, so it starts as active. 239 cpu->activateStage(FullCPU::CommitIdx); 240 241 trapLatency = cpu->cycles(trapLatency); 242 fetchTrapLatency = cpu->cycles(fetchTrapLatency); 243} 244 245template <class Impl> 246void 247DefaultCommit<Impl>::setThreads(vector<Thread *> &threads) 248{ 249 thread = threads; 250} 251 252template <class Impl> 253void 254DefaultCommit<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *tb_ptr) 255{ 256 DPRINTF(Commit, "Commit: Setting time buffer pointer.\n"); 257 timeBuffer = tb_ptr; 258 259 // Setup wire to send information back to IEW. 260 toIEW = timeBuffer->getWire(0); 261 262 // Setup wire to read data from IEW (for the ROB). 263 robInfoFromIEW = timeBuffer->getWire(-iewToCommitDelay); 264} 265 266template <class Impl> 267void 268DefaultCommit<Impl>::setFetchQueue(TimeBuffer<FetchStruct> *fq_ptr) 269{ 270 DPRINTF(Commit, "Commit: Setting fetch queue pointer.\n"); 271 fetchQueue = fq_ptr; 272 273 // Setup wire to get instructions from rename (for the ROB). 274 fromFetch = fetchQueue->getWire(-fetchToCommitDelay); 275} 276 277template <class Impl> 278void 279DefaultCommit<Impl>::setRenameQueue(TimeBuffer<RenameStruct> *rq_ptr) 280{ 281 DPRINTF(Commit, "Commit: Setting rename queue pointer.\n"); 282 renameQueue = rq_ptr; 283 284 // Setup wire to get instructions from rename (for the ROB). 285 fromRename = renameQueue->getWire(-renameToROBDelay); 286} 287 288template <class Impl> 289void 290DefaultCommit<Impl>::setIEWQueue(TimeBuffer<IEWStruct> *iq_ptr) 291{ 292 DPRINTF(Commit, "Commit: Setting IEW queue pointer.\n"); 293 iewQueue = iq_ptr; 294 295 // Setup wire to get instructions from IEW. 296 fromIEW = iewQueue->getWire(-iewToCommitDelay); 297} 298 299template <class Impl> 300void 301DefaultCommit<Impl>::setFetchStage(Fetch *fetch_stage) 302{ 303 fetchStage = fetch_stage; 304} 305 306template <class Impl> 307void 308DefaultCommit<Impl>::setIEWStage(IEW *iew_stage) 309{ 310 iewStage = iew_stage; 311} 312 313template<class Impl> 314void 315DefaultCommit<Impl>::setActiveThreads(list<unsigned> *at_ptr) 316{ 317 DPRINTF(Commit, "Commit: Setting active threads list pointer.\n"); 318 activeThreads = at_ptr; 319} 320 321template <class Impl> 322void 323DefaultCommit<Impl>::setRenameMap(RenameMap rm_ptr[]) 324{ 325 DPRINTF(Commit, "Setting rename map pointers.\n"); 326 327 for (int i=0; i < numThreads; i++) { 328 renameMap[i] = &rm_ptr[i]; 329 } 330} 331 332template <class Impl> 333void 334DefaultCommit<Impl>::setROB(ROB *rob_ptr) 335{ 336 DPRINTF(Commit, "Commit: Setting ROB pointer.\n"); 337 rob = rob_ptr; 338} 339 340template <class Impl> 341void 342DefaultCommit<Impl>::initStage() 343{ 344 rob->setActiveThreads(activeThreads); 345 rob->resetEntries(); 346 347 // Broadcast the number of free entries. 348 for (int i=0; i < numThreads; i++) { 349 toIEW->commitInfo[i].usedROB = true; 350 toIEW->commitInfo[i].freeROBEntries = rob->numFreeEntries(i); 351 } 352 353 cpu->activityThisCycle(); 354} 355 356template <class Impl> 357void 358DefaultCommit<Impl>::switchOut() 359{ 360 switchPending = true; 361} 362 363template <class Impl> 364void 365DefaultCommit<Impl>::doSwitchOut() 366{ 367 switchedOut = true; 368 switchPending = false; 369 rob->switchOut(); 370} 371 372template <class Impl> 373void 374DefaultCommit<Impl>::takeOverFrom() 375{ 376 switchedOut = false; 377 _status = Active; 378 _nextStatus = Inactive; 379 for (int i=0; i < numThreads; i++) { 380 commitStatus[i] = Idle; 381 changedROBNumEntries[i] = false; 382 trapSquash[i] = false; 383 xcSquash[i] = false; 384 } 385 squashCounter = 0; 386 rob->takeOverFrom(); 387} 388 389template <class Impl> 390void 391DefaultCommit<Impl>::updateStatus() 392{ 393 // reset ROB changed variable 394 list<unsigned>::iterator threads = (*activeThreads).begin(); 395 while (threads != (*activeThreads).end()) { 396 unsigned tid = *threads++; 397 changedROBNumEntries[tid] = false; 398 399 // Also check if any of the threads has a trap pending 400 if (commitStatus[tid] == TrapPending || 401 commitStatus[tid] == FetchTrapPending) { 402 _nextStatus = Active; 403 } 404 } 405 406 if (_nextStatus == Inactive && _status == Active) { 407 DPRINTF(Activity, "Deactivating stage.\n"); 408 cpu->deactivateStage(FullCPU::CommitIdx); 409 } else if (_nextStatus == Active && _status == Inactive) { 410 DPRINTF(Activity, "Activating stage.\n"); 411 cpu->activateStage(FullCPU::CommitIdx); 412 } 413 414 _status = _nextStatus; 415} 416 417template <class Impl> 418void 419DefaultCommit<Impl>::setNextStatus() 420{ 421 int squashes = 0; 422 423 list<unsigned>::iterator threads = (*activeThreads).begin(); 424 425 while (threads != (*activeThreads).end()) { 426 unsigned tid = *threads++; 427 428 if (commitStatus[tid] == ROBSquashing) { 429 squashes++; 430 } 431 } 432 433 assert(squashes == squashCounter); 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 list<unsigned>::iterator threads = (*activeThreads).begin(); 447 448 while (threads != (*activeThreads).end()) { 449 unsigned tid = *threads++; 450 451 if (changedROBNumEntries[tid]) { 452 return true; 453 } 454 } 455 456 return false; 457} 458 459template <class Impl> 460unsigned 461DefaultCommit<Impl>::numROBFreeEntries(unsigned tid) 462{ 463 return rob->numFreeEntries(tid); 464} 465 466template <class Impl> 467void 468DefaultCommit<Impl>::generateTrapEvent(unsigned tid) 469{ 470 DPRINTF(Commit, "Generating trap event for [tid:%i]\n", tid); 471 472 TrapEvent *trap = new TrapEvent(this, tid); 473 474 trap->schedule(curTick + trapLatency); 475 476 thread[tid]->trapPending = true; 477} 478 479template <class Impl> 480void 481DefaultCommit<Impl>::generateXCEvent(unsigned tid) 482{ 483 DPRINTF(Commit, "Generating XC squash event for [tid:%i]\n", tid); 484 485 xcSquash[tid] = true; 486} 487 488template <class Impl> 489void 490DefaultCommit<Impl>::squashAll(unsigned tid) 491{ 492 // If we want to include the squashing instruction in the squash, 493 // then use one older sequence number. 494 // Hopefully this doesn't mess things up. Basically I want to squash 495 // all instructions of this thread. 496 InstSeqNum squashed_inst = rob->isEmpty() ? 497 0 : rob->readHeadInst(tid)->seqNum - 1;; 498 499 // All younger instructions will be squashed. Set the sequence 500 // number as the youngest instruction in the ROB (0 in this case. 501 // Hopefully nothing breaks.) 502 youngestSeqNum[tid] = 0; 503 504 rob->squash(squashed_inst, tid); 505 changedROBNumEntries[tid] = true; 506 507 // Send back the sequence number of the squashed instruction. 508 toIEW->commitInfo[tid].doneSeqNum = squashed_inst; 509 510 // Send back the squash signal to tell stages that they should 511 // squash. 512 toIEW->commitInfo[tid].squash = true; 513 514 // Send back the rob squashing signal so other stages know that 515 // the ROB is in the process of squashing. 516 toIEW->commitInfo[tid].robSquashing = true; 517 518 toIEW->commitInfo[tid].branchMispredict = false; 519 520 toIEW->commitInfo[tid].nextPC = PC[tid]; 521} 522 523template <class Impl> 524void 525DefaultCommit<Impl>::squashFromTrap(unsigned tid) 526{ 527 squashAll(tid); 528 529 DPRINTF(Commit, "Squashing from trap, restarting at PC %#x\n", PC[tid]); 530 531 thread[tid]->trapPending = false; 532 thread[tid]->inSyscall = false; 533 534 trapSquash[tid] = false; 535 536 commitStatus[tid] = ROBSquashing; 537 cpu->activityThisCycle(); 538 539 ++squashCounter; 540} 541 542template <class Impl> 543void 544DefaultCommit<Impl>::squashFromXC(unsigned tid) 545{ 546 squashAll(tid); 547 548 DPRINTF(Commit, "Squashing from XC, restarting at PC %#x\n", PC[tid]); 549 550 thread[tid]->inSyscall = false; 551 assert(!thread[tid]->trapPending); 552 553 commitStatus[tid] = ROBSquashing; 554 cpu->activityThisCycle(); 555 556 xcSquash[tid] = false; 557 558 ++squashCounter; 559} 560 561template <class Impl> 562void 563DefaultCommit<Impl>::tick() 564{ 565 wroteToTimeBuffer = false; 566 _nextStatus = Inactive; 567 568 if (switchPending && rob->isEmpty() && !iewStage->hasStoresToWB()) { 569 cpu->signalSwitched(); 570 return; 571 } 572 573 list<unsigned>::iterator threads = (*activeThreads).begin(); 574 575 // Check if any of the threads are done squashing. Change the 576 // status if they are done. 577 while (threads != (*activeThreads).end()) { 578 unsigned tid = *threads++; 579 580 if (commitStatus[tid] == ROBSquashing) { 581 582 if (rob->isDoneSquashing(tid)) { 583 commitStatus[tid] = Running; 584 --squashCounter; 585 } else { 586 DPRINTF(Commit,"[tid:%u]: Still Squashing, cannot commit any" 587 "insts this cycle.\n", tid); 588 } 589 } 590 } 591 592 commit(); 593 594 markCompletedInsts(); 595 596 threads = (*activeThreads).begin(); 597 598 while (threads != (*activeThreads).end()) { 599 unsigned tid = *threads++; 600 601 if (!rob->isEmpty(tid) && rob->readHeadInst(tid)->readyToCommit()) { 602 // The ROB has more instructions it can commit. Its next status 603 // will be active. 604 _nextStatus = Active; 605 606 DynInstPtr inst = rob->readHeadInst(tid); 607 608 DPRINTF(Commit,"[tid:%i]: Instruction [sn:%lli] PC %#x is head of" 609 " ROB and ready to commit\n", 610 tid, inst->seqNum, inst->readPC()); 611 612 } else if (!rob->isEmpty(tid)) { 613 DynInstPtr inst = rob->readHeadInst(tid); 614 615 DPRINTF(Commit,"[tid:%i]: Can't commit, Instruction [sn:%lli] PC " 616 "%#x is head of ROB and not ready\n", 617 tid, inst->seqNum, inst->readPC()); 618 } 619 620 DPRINTF(Commit, "[tid:%i]: ROB has %d insts & %d free entries.\n", 621 tid, rob->countInsts(tid), rob->numFreeEntries(tid)); 622 } 623 624 625 if (wroteToTimeBuffer) { 626 DPRINTF(Activity, "Activity This Cycle.\n"); 627 cpu->activityThisCycle(); 628 } 629 630 updateStatus(); 631} 632 633template <class Impl> 634void 635DefaultCommit<Impl>::commit() 636{ 637 638 ////////////////////////////////////// 639 // Check for interrupts 640 ////////////////////////////////////// 641 642#if FULL_SYSTEM 643 // Process interrupts if interrupts are enabled, not in PAL mode, 644 // and no other traps or external squashes are currently pending. 645 // @todo: Allow other threads to handle interrupts. 646 if (cpu->checkInterrupts && 647 cpu->check_interrupts() && 648 !cpu->inPalMode(readPC()) && 649 !trapSquash[0] && 650 !xcSquash[0]) { 651 // Tell fetch that there is an interrupt pending. This will 652 // make fetch wait until it sees a non PAL-mode PC, at which 653 // point it stops fetching instructions. 654 toIEW->commitInfo[0].interruptPending = true; 655 656 // Wait until the ROB is empty and all stores have drained in 657 // order to enter the interrupt. 658 if (rob->isEmpty() && !iewStage->hasStoresToWB()) { 659 // Not sure which thread should be the one to interrupt. For now 660 // always do thread 0. 661 assert(!thread[0]->inSyscall); 662 thread[0]->inSyscall = true; 663 664 // CPU will handle implementation of the interrupt. 665 cpu->processInterrupts(); 666 667 // Now squash or record that I need to squash this cycle. 668 commitStatus[0] = TrapPending; 669 670 // Exit state update mode to avoid accidental updating. 671 thread[0]->inSyscall = false; 672 673 // Generate trap squash event. 674 generateTrapEvent(0); 675 676 toIEW->commitInfo[0].clearInterrupt = true; 677 678 DPRINTF(Commit, "Interrupt detected.\n"); 679 } else { 680 DPRINTF(Commit, "Interrupt pending, waiting for ROB to empty.\n"); 681 } 682 } 683#endif // FULL_SYSTEM 684 685 //////////////////////////////////// 686 // Check for any possible squashes, handle them first 687 //////////////////////////////////// 688 689 list<unsigned>::iterator threads = (*activeThreads).begin(); 690 691 while (threads != (*activeThreads).end()) { 692 unsigned tid = *threads++; 693 694 if (fromFetch->fetchFault && commitStatus[0] != TrapPending) { 695 // Record the fault. Wait until it's empty in the ROB. 696 // Then handle the trap. Ignore it if there's already a 697 // trap pending as fetch will be redirected. 698 fetchFault = fromFetch->fetchFault; 699 fetchFaultTick = curTick + fetchTrapLatency; 700 commitStatus[0] = FetchTrapPending; 701 DPRINTF(Commit, "Fault from fetch recorded. Will trap if the " 702 "ROB empties without squashing the fault.\n"); 703 fetchTrapWait = 0; 704 } 705 706 // Fetch may tell commit to clear the trap if it's been squashed. 707 if (fromFetch->clearFetchFault) { 708 DPRINTF(Commit, "Received clear fetch fault signal\n"); 709 fetchTrapWait = 0; 710 if (commitStatus[0] == FetchTrapPending) { 711 DPRINTF(Commit, "Clearing fault from fetch\n"); 712 commitStatus[0] = Running; 713 } 714 } 715 716 // Not sure which one takes priority. I think if we have 717 // both, that's a bad sign. 718 if (trapSquash[tid] == true) { 719 assert(!xcSquash[tid]); 720 squashFromTrap(tid); 721 } else if (xcSquash[tid] == true) { 722 squashFromXC(tid); 723 } 724 725 // Squashed sequence number must be older than youngest valid 726 // instruction in the ROB. This prevents squashes from younger 727 // instructions overriding squashes from older instructions. 728 if (fromIEW->squash[tid] && 729 commitStatus[tid] != TrapPending && 730 fromIEW->squashedSeqNum[tid] <= youngestSeqNum[tid]) { 731 732 DPRINTF(Commit, "[tid:%i]: Squashing due to PC %#x [sn:%i]\n", 733 tid, 734 fromIEW->mispredPC[tid], 735 fromIEW->squashedSeqNum[tid]); 736 737 DPRINTF(Commit, "[tid:%i]: Redirecting to PC %#x\n", 738 tid, 739 fromIEW->nextPC[tid]); 740 741 commitStatus[tid] = ROBSquashing; 742 743 ++squashCounter; 744 745 // If we want to include the squashing instruction in the squash, 746 // then use one older sequence number. 747 InstSeqNum squashed_inst = fromIEW->squashedSeqNum[tid]; 748 749 if (fromIEW->includeSquashInst[tid] == true) 750 squashed_inst--; 751 752 // All younger instructions will be squashed. Set the sequence 753 // number as the youngest instruction in the ROB. 754 youngestSeqNum[tid] = squashed_inst; 755 756 rob->squash(squashed_inst, tid); 757 changedROBNumEntries[tid] = true; 758 759 toIEW->commitInfo[tid].doneSeqNum = squashed_inst; 760 761 toIEW->commitInfo[tid].squash = true; 762 763 // Send back the rob squashing signal so other stages know that 764 // the ROB is in the process of squashing. 765 toIEW->commitInfo[tid].robSquashing = true; 766 767 toIEW->commitInfo[tid].branchMispredict = 768 fromIEW->branchMispredict[tid]; 769 770 toIEW->commitInfo[tid].branchTaken = 771 fromIEW->branchTaken[tid]; 772 773 toIEW->commitInfo[tid].nextPC = fromIEW->nextPC[tid]; 774 775 toIEW->commitInfo[tid].mispredPC = fromIEW->mispredPC[tid]; 776 777 if (toIEW->commitInfo[tid].branchMispredict) { 778 ++branchMispredicts; 779 } 780 } 781 782 } 783 784 setNextStatus(); 785 786 if (squashCounter != numThreads) { 787 // If we're not currently squashing, then get instructions. 788 getInsts(); 789 790 // Try to commit any instructions. 791 commitInsts(); 792 } 793 794 //Check for any activity 795 threads = (*activeThreads).begin(); 796 797 while (threads != (*activeThreads).end()) { 798 unsigned tid = *threads++; 799 800 if (changedROBNumEntries[tid]) { 801 toIEW->commitInfo[tid].usedROB = true; 802 toIEW->commitInfo[tid].freeROBEntries = rob->numFreeEntries(tid); 803 804 if (rob->isEmpty(tid)) { 805 toIEW->commitInfo[tid].emptyROB = true; 806 } 807 808 wroteToTimeBuffer = true; 809 changedROBNumEntries[tid] = false; 810 } 811 } 812} 813 814template <class Impl> 815void 816DefaultCommit<Impl>::commitInsts() 817{ 818 //////////////////////////////////// 819 // Handle commit 820 // Note that commit will be handled prior to putting new 821 // instructions in the ROB so that the ROB only tries to commit 822 // instructions it has in this current cycle, and not instructions 823 // it is writing in during this cycle. Can't commit and squash 824 // things at the same time... 825 //////////////////////////////////// 826 827 DPRINTF(Commit, "Trying to commit instructions in the ROB.\n"); 828 829 unsigned num_committed = 0; 830 831 DynInstPtr head_inst; 832 833 // Commit as many instructions as possible until the commit bandwidth 834 // limit is reached, or it becomes impossible to commit any more. 835 while (num_committed < commitWidth) { 836 int commit_thread = getCommittingThread(); 837 838 if (commit_thread == -1 || !rob->isHeadReady(commit_thread)) 839 break; 840 841 head_inst = rob->readHeadInst(commit_thread); 842 843 int tid = head_inst->threadNumber; 844 845 assert(tid == commit_thread); 846 847 DPRINTF(Commit, "Trying to commit head instruction, [sn:%i] [tid:%i]\n", 848 head_inst->seqNum, tid); 849 850 // If the head instruction is squashed, it is ready to retire 851 // (be removed from the ROB) at any time. 852 if (head_inst->isSquashed()) { 853 854 DPRINTF(Commit, "Retiring squashed instruction from " 855 "ROB.\n"); 856 857 rob->retireHead(commit_thread); 858 859 ++commitSquashedInsts; 860 861 // Record that the number of ROB entries has changed. 862 changedROBNumEntries[tid] = true; 863 } else { 864 PC[tid] = head_inst->readPC(); 865 nextPC[tid] = head_inst->readNextPC(); 866 867 // Increment the total number of non-speculative instructions 868 // executed. 869 // Hack for now: it really shouldn't happen until after the 870 // commit is deemed to be successful, but this count is needed 871 // for syscalls. 872 thread[tid]->funcExeInst++; 873 874 // Try to commit the head instruction. 875 bool commit_success = commitHead(head_inst, num_committed); 876 877 if (commit_success) { 878 ++num_committed; 879 880 changedROBNumEntries[tid] = true; 881 882 // Set the doneSeqNum to the youngest committed instruction. 883 toIEW->commitInfo[tid].doneSeqNum = head_inst->seqNum; 884 885 ++commitCommittedInsts; 886 887 // To match the old model, don't count nops and instruction 888 // prefetches towards the total commit count. 889 if (!head_inst->isNop() && !head_inst->isInstPrefetch()) { 890 cpu->instDone(tid); 891 } 892 893 PC[tid] = nextPC[tid]; 894 nextPC[tid] = nextPC[tid] + sizeof(TheISA::MachInst); 895#if FULL_SYSTEM 896 int count = 0; 897 Addr oldpc; 898 do { 899 // Debug statement. Checks to make sure we're not 900 // currently updating state while handling PC events. 901 if (count == 0) 902 assert(!thread[tid]->inSyscall && 903 !thread[tid]->trapPending); 904 oldpc = PC[tid]; 905 cpu->system->pcEventQueue.service( 906 thread[tid]->getXCProxy()); 907 count++; 908 } while (oldpc != PC[tid]); 909 if (count > 1) { 910 DPRINTF(Commit, "PC skip function event, stopping commit\n"); 911 break; 912 } 913#endif 914 } else { 915 DPRINTF(Commit, "Unable to commit head instruction PC:%#x " 916 "[tid:%i] [sn:%i].\n", 917 head_inst->readPC(), tid ,head_inst->seqNum); 918 break; 919 } 920 } 921 } 922 923 DPRINTF(CommitRate, "%i\n", num_committed); 924 numCommittedDist.sample(num_committed); 925 926 if (num_committed == commitWidth) { 927 commitEligible[0]++; 928 } 929} 930 931template <class Impl> 932bool 933DefaultCommit<Impl>::commitHead(DynInstPtr &head_inst, unsigned inst_num) 934{ 935 assert(head_inst); 936 937 int tid = head_inst->threadNumber; 938 939 // If the instruction is not executed yet, then it will need extra 940 // handling. Signal backwards that it should be executed. 941 if (!head_inst->isExecuted()) { 942 // Keep this number correct. We have not yet actually executed 943 // and committed this instruction. 944 thread[tid]->funcExeInst--; 945 946 head_inst->reachedCommit = true; 947 948 if (head_inst->isNonSpeculative() || 949 head_inst->isMemBarrier() || 950 head_inst->isWriteBarrier()) { 951 952 DPRINTF(Commit, "Encountered a barrier or non-speculative " 953 "instruction [sn:%lli] at the head of the ROB, PC %#x.\n", 954 head_inst->seqNum, head_inst->readPC()); 955 956#if !FULL_SYSTEM 957 // Hack to make sure syscalls/memory barriers/quiesces 958 // aren't executed until all stores write back their data. 959 // This direct communication shouldn't be used for 960 // anything other than this. 961 if (inst_num > 0 || iewStage->hasStoresToWB()) 962#else 963 if ((head_inst->isMemBarrier() || head_inst->isWriteBarrier() || 964 head_inst->isQuiesce()) && 965 iewStage->hasStoresToWB()) 966#endif 967 { 968 DPRINTF(Commit, "Waiting for all stores to writeback.\n"); 969 return false; 970 } 971 972 toIEW->commitInfo[tid].nonSpecSeqNum = head_inst->seqNum; 973 974 // Change the instruction so it won't try to commit again until 975 // it is executed. 976 head_inst->clearCanCommit(); 977 978 ++commitNonSpecStalls; 979 980 return false; 981 } else if (head_inst->isLoad()) { 982 DPRINTF(Commit, "[sn:%lli]: Uncached load, PC %#x.\n", 983 head_inst->seqNum, head_inst->readPC()); 984 985 // Send back the non-speculative instruction's sequence 986 // number. Tell the lsq to re-execute the load. 987 toIEW->commitInfo[tid].nonSpecSeqNum = head_inst->seqNum; 988 toIEW->commitInfo[tid].uncached = true; 989 toIEW->commitInfo[tid].uncachedLoad = head_inst; 990 991 head_inst->clearCanCommit(); 992 993 return false; 994 } else { 995 panic("Trying to commit un-executed instruction " 996 "of unknown type!\n"); 997 } 998 } 999 1000 if (head_inst->isThreadSync()) { 1001 // Not handled for now. 1002 panic("Thread sync instructions are not handled yet.\n"); 1003 } 1004 1005 // Stores mark themselves as completed. 1006 if (!head_inst->isStore()) { 1007 head_inst->setCompleted(); 1008 } 1009 1010 // Use checker prior to updating anything due to traps or PC 1011 // based events. 1012 if (cpu->checker) { 1013 cpu->checker->tick(head_inst); 1014 } 1015 1016 // Check if the instruction caused a fault. If so, trap. 1017 Fault inst_fault = head_inst->getFault(); 1018 1019 if (inst_fault != NoFault) { 1020 head_inst->setCompleted(); 1021#if FULL_SYSTEM 1022 DPRINTF(Commit, "Inst [sn:%lli] PC %#x has a fault\n", 1023 head_inst->seqNum, head_inst->readPC()); 1024 1025 if (iewStage->hasStoresToWB() || inst_num > 0) { 1026 DPRINTF(Commit, "Stores outstanding, fault must wait.\n"); 1027 return false; 1028 } 1029 1030 if (cpu->checker && head_inst->isStore()) { 1031 cpu->checker->tick(head_inst); 1032 } 1033 1034 assert(!thread[tid]->inSyscall); 1035 1036 // Mark that we're in state update mode so that the trap's 1037 // execution doesn't generate extra squashes. 1038 thread[tid]->inSyscall = true; 1039 1040 // DTB will sometimes need the machine instruction for when 1041 // faults happen. So we will set it here, prior to the DTB 1042 // possibly needing it for its fault. 1043 thread[tid]->setInst( 1044 static_cast<TheISA::MachInst>(head_inst->staticInst->machInst)); 1045 1046 // Execute the trap. Although it's slightly unrealistic in 1047 // terms of timing (as it doesn't wait for the full timing of 1048 // the trap event to complete before updating state), it's 1049 // needed to update the state as soon as possible. This 1050 // prevents external agents from changing any specific state 1051 // that the trap need. 1052 cpu->trap(inst_fault, tid); 1053 1054 // Exit state update mode to avoid accidental updating. 1055 thread[tid]->inSyscall = false; 1056 1057 commitStatus[tid] = TrapPending; 1058 1059 // Generate trap squash event. 1060 generateTrapEvent(tid); 1061 1062 return false; 1063#else // !FULL_SYSTEM 1064 panic("fault (%d) detected @ PC %08p", inst_fault, 1065 head_inst->PC); 1066#endif // FULL_SYSTEM 1067 } 1068 1069 updateComInstStats(head_inst); 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->finalize(); 1075 head_inst->traceData = NULL; 1076 } 1077 1078 // Update the commit rename map 1079 for (int i = 0; i < head_inst->numDestRegs(); i++) { 1080 renameMap[tid]->setEntry(head_inst->destRegIdx(i), 1081 head_inst->renamedDestRegIdx(i)); 1082 } 1083 1084 // Finally clear the head ROB entry. 1085 rob->retireHead(tid); 1086 1087 // Return true to indicate that we have committed an instruction. 1088 return true; 1089} 1090 1091template <class Impl> 1092void 1093DefaultCommit<Impl>::getInsts() 1094{ 1095 // Read any renamed instructions and place them into the ROB. 1096 int insts_to_process = min((int)renameWidth, fromRename->size); 1097 1098 for (int inst_num = 0; inst_num < insts_to_process; ++inst_num) 1099 { 1100 DynInstPtr inst = fromRename->insts[inst_num]; 1101 int tid = inst->threadNumber; 1102 1103 if (!inst->isSquashed() && 1104 commitStatus[tid] != ROBSquashing) { 1105 changedROBNumEntries[tid] = true; 1106 1107 DPRINTF(Commit, "Inserting PC %#x [sn:%i] [tid:%i] into ROB.\n", 1108 inst->readPC(), inst->seqNum, tid); 1109 1110 rob->insertInst(inst); 1111 1112 assert(rob->getThreadEntries(tid) <= rob->getMaxEntries(tid)); 1113 1114 youngestSeqNum[tid] = inst->seqNum; 1115 } else { 1116 DPRINTF(Commit, "Instruction PC %#x [sn:%i] [tid:%i] was " 1117 "squashed, skipping.\n", 1118 inst->readPC(), inst->seqNum, tid); 1119 } 1120 } 1121} 1122 1123template <class Impl> 1124void 1125DefaultCommit<Impl>::markCompletedInsts() 1126{ 1127 // Grab completed insts out of the IEW instruction queue, and mark 1128 // instructions completed within the ROB. 1129 for (int inst_num = 0; 1130 inst_num < fromIEW->size && fromIEW->insts[inst_num]; 1131 ++inst_num) 1132 { 1133 if (!fromIEW->insts[inst_num]->isSquashed()) { 1134 DPRINTF(Commit, "[tid:%i]: Marking PC %#x, [sn:%lli] ready " 1135 "within ROB.\n", 1136 fromIEW->insts[inst_num]->threadNumber, 1137 fromIEW->insts[inst_num]->readPC(), 1138 fromIEW->insts[inst_num]->seqNum); 1139 1140 // Mark the instruction as ready to commit. 1141 fromIEW->insts[inst_num]->setCanCommit(); 1142 } 1143 } 1144} 1145 1146template <class Impl> 1147bool 1148DefaultCommit<Impl>::robDoneSquashing() 1149{ 1150 list<unsigned>::iterator threads = (*activeThreads).begin(); 1151 1152 while (threads != (*activeThreads).end()) { 1153 unsigned tid = *threads++; 1154 1155 if (!rob->isDoneSquashing(tid)) 1156 return false; 1157 } 1158 1159 return true; 1160} 1161 1162template <class Impl> 1163void 1164DefaultCommit<Impl>::updateComInstStats(DynInstPtr &inst) 1165{ 1166 unsigned thread = inst->threadNumber; 1167 1168 // 1169 // Pick off the software prefetches 1170 // 1171#ifdef TARGET_ALPHA 1172 if (inst->isDataPrefetch()) { 1173 statComSwp[thread]++; 1174 } else { 1175 statComInst[thread]++; 1176 } 1177#else 1178 statComInst[thread]++; 1179#endif 1180 1181 // 1182 // Control Instructions 1183 // 1184 if (inst->isControl()) 1185 statComBranches[thread]++; 1186 1187 // 1188 // Memory references 1189 // 1190 if (inst->isMemRef()) { 1191 statComRefs[thread]++; 1192 1193 if (inst->isLoad()) { 1194 statComLoads[thread]++; 1195 } 1196 } 1197 1198 if (inst->isMemBarrier()) { 1199 statComMembars[thread]++; 1200 } 1201} 1202 1203//////////////////////////////////////// 1204// // 1205// SMT COMMIT POLICY MAINTAINED HERE // 1206// // 1207//////////////////////////////////////// 1208template <class Impl> 1209int 1210DefaultCommit<Impl>::getCommittingThread() 1211{ 1212 if (numThreads > 1) { 1213 switch (commitPolicy) { 1214 1215 case Aggressive: 1216 //If Policy is Aggressive, commit will call 1217 //this function multiple times per 1218 //cycle 1219 return oldestReady(); 1220 1221 case RoundRobin: 1222 return roundRobin(); 1223 1224 case OldestReady: 1225 return oldestReady(); 1226 1227 default: 1228 return -1; 1229 } 1230 } else { 1231 int tid = (*activeThreads).front(); 1232 1233 if (commitStatus[tid] == Running || 1234 commitStatus[tid] == Idle || 1235 commitStatus[tid] == FetchTrapPending) { 1236 return tid; 1237 } else { 1238 return -1; 1239 } 1240 } 1241} 1242 1243template<class Impl> 1244int 1245DefaultCommit<Impl>::roundRobin() 1246{ 1247 list<unsigned>::iterator pri_iter = priority_list.begin(); 1248 list<unsigned>::iterator end = priority_list.end(); 1249 1250 while (pri_iter != end) { 1251 unsigned tid = *pri_iter; 1252 1253 if (commitStatus[tid] == Running || 1254 commitStatus[tid] == Idle) { 1255 1256 if (rob->isHeadReady(tid)) { 1257 priority_list.erase(pri_iter); 1258 priority_list.push_back(tid); 1259 1260 return tid; 1261 } 1262 } 1263 1264 pri_iter++; 1265 } 1266 1267 return -1; 1268} 1269 1270template<class Impl> 1271int 1272DefaultCommit<Impl>::oldestReady() 1273{ 1274 unsigned oldest = 0; 1275 bool first = true; 1276 1277 list<unsigned>::iterator threads = (*activeThreads).begin(); 1278 1279 while (threads != (*activeThreads).end()) { 1280 unsigned tid = *threads++; 1281 1282 if (!rob->isEmpty(tid) && 1283 (commitStatus[tid] == Running || 1284 commitStatus[tid] == Idle || 1285 commitStatus[tid] == FetchTrapPending)) { 1286 1287 if (rob->isHeadReady(tid)) { 1288 1289 DynInstPtr head_inst = rob->readHeadInst(tid); 1290 1291 if (first) { 1292 oldest = tid; 1293 first = false; 1294 } else if (head_inst->seqNum < oldest) { 1295 oldest = tid; 1296 } 1297 } 1298 } 1299 } 1300 1301 if (!first) { 1302 return oldest; 1303 } else { 1304 return -1; 1305 } 1306} 1307