fetch_impl.hh revision 10244:d2deb51a4abf
1/* 2 * Copyright (c) 2010-2013 ARM Limited 3 * All rights reserved. 4 * 5 * The license below extends only to copyright in the software and shall 6 * not be construed as granting a license to any other intellectual 7 * property including but not limited to intellectual property relating 8 * to a hardware implementation of the functionality of the software 9 * licensed hereunder. You may use the software subject to the license 10 * terms below provided that you ensure that this notice is replicated 11 * unmodified and in its entirety in all distributions of the software, 12 * modified or unmodified, in source code or in binary form. 13 * 14 * Copyright (c) 2004-2006 The Regents of The University of Michigan 15 * All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions are 19 * met: redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer; 21 * redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution; 24 * neither the name of the copyright holders nor the names of its 25 * contributors may be used to endorse or promote products derived from 26 * this software without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 39 * 40 * Authors: Kevin Lim 41 * Korey Sewell 42 */ 43 44#ifndef __CPU_O3_FETCH_IMPL_HH__ 45#define __CPU_O3_FETCH_IMPL_HH__ 46 47#include <algorithm> 48#include <cstring> 49#include <list> 50#include <map> 51#include <queue> 52 53#include "arch/isa_traits.hh" 54#include "arch/tlb.hh" 55#include "arch/utility.hh" 56#include "arch/vtophys.hh" 57#include "base/types.hh" 58#include "config/the_isa.hh" 59#include "cpu/base.hh" 60//#include "cpu/checker/cpu.hh" 61#include "cpu/o3/fetch.hh" 62#include "cpu/exetrace.hh" 63#include "debug/Activity.hh" 64#include "debug/Drain.hh" 65#include "debug/Fetch.hh" 66#include "debug/O3PipeView.hh" 67#include "mem/packet.hh" 68#include "params/DerivO3CPU.hh" 69#include "sim/byteswap.hh" 70#include "sim/core.hh" 71#include "sim/eventq.hh" 72#include "sim/full_system.hh" 73#include "sim/system.hh" 74 75using namespace std; 76 77template<class Impl> 78DefaultFetch<Impl>::DefaultFetch(O3CPU *_cpu, DerivO3CPUParams *params) 79 : cpu(_cpu), 80 decodeToFetchDelay(params->decodeToFetchDelay), 81 renameToFetchDelay(params->renameToFetchDelay), 82 iewToFetchDelay(params->iewToFetchDelay), 83 commitToFetchDelay(params->commitToFetchDelay), 84 fetchWidth(params->fetchWidth), 85 retryPkt(NULL), 86 retryTid(InvalidThreadID), 87 cacheBlkSize(cpu->cacheLineSize()), 88 fetchBufferSize(params->fetchBufferSize), 89 fetchBufferMask(fetchBufferSize - 1), 90 numThreads(params->numThreads), 91 numFetchingThreads(params->smtNumFetchingThreads), 92 finishTranslationEvent(this) 93{ 94 if (numThreads > Impl::MaxThreads) 95 fatal("numThreads (%d) is larger than compiled limit (%d),\n" 96 "\tincrease MaxThreads in src/cpu/o3/impl.hh\n", 97 numThreads, static_cast<int>(Impl::MaxThreads)); 98 if (fetchWidth > Impl::MaxWidth) 99 fatal("fetchWidth (%d) is larger than compiled limit (%d),\n" 100 "\tincrease MaxWidth in src/cpu/o3/impl.hh\n", 101 fetchWidth, static_cast<int>(Impl::MaxWidth)); 102 if (fetchBufferSize > cacheBlkSize) 103 fatal("fetch buffer size (%u bytes) is greater than the cache " 104 "block size (%u bytes)\n", fetchBufferSize, cacheBlkSize); 105 if (cacheBlkSize % fetchBufferSize) 106 fatal("cache block (%u bytes) is not a multiple of the " 107 "fetch buffer (%u bytes)\n", cacheBlkSize, fetchBufferSize); 108 109 std::string policy = params->smtFetchPolicy; 110 111 // Convert string to lowercase 112 std::transform(policy.begin(), policy.end(), policy.begin(), 113 (int(*)(int)) tolower); 114 115 // Figure out fetch policy 116 if (policy == "singlethread") { 117 fetchPolicy = SingleThread; 118 if (numThreads > 1) 119 panic("Invalid Fetch Policy for a SMT workload."); 120 } else if (policy == "roundrobin") { 121 fetchPolicy = RoundRobin; 122 DPRINTF(Fetch, "Fetch policy set to Round Robin\n"); 123 } else if (policy == "branch") { 124 fetchPolicy = Branch; 125 DPRINTF(Fetch, "Fetch policy set to Branch Count\n"); 126 } else if (policy == "iqcount") { 127 fetchPolicy = IQ; 128 DPRINTF(Fetch, "Fetch policy set to IQ count\n"); 129 } else if (policy == "lsqcount") { 130 fetchPolicy = LSQ; 131 DPRINTF(Fetch, "Fetch policy set to LSQ count\n"); 132 } else { 133 fatal("Invalid Fetch Policy. Options Are: {SingleThread," 134 " RoundRobin,LSQcount,IQcount}\n"); 135 } 136 137 // Get the size of an instruction. 138 instSize = sizeof(TheISA::MachInst); 139 140 for (int i = 0; i < Impl::MaxThreads; i++) { 141 decoder[i] = NULL; 142 fetchBuffer[i] = NULL; 143 fetchBufferPC[i] = 0; 144 fetchBufferValid[i] = false; 145 } 146 147 branchPred = params->branchPred; 148 149 for (ThreadID tid = 0; tid < numThreads; tid++) { 150 decoder[tid] = new TheISA::Decoder; 151 // Create space to buffer the cache line data, 152 // which may not hold the entire cache line. 153 fetchBuffer[tid] = new uint8_t[fetchBufferSize]; 154 } 155} 156 157template <class Impl> 158std::string 159DefaultFetch<Impl>::name() const 160{ 161 return cpu->name() + ".fetch"; 162} 163 164template <class Impl> 165void 166DefaultFetch<Impl>::regProbePoints() 167{ 168 ppFetch = new ProbePointArg<DynInstPtr>(cpu->getProbeManager(), "Fetch"); 169} 170 171template <class Impl> 172void 173DefaultFetch<Impl>::regStats() 174{ 175 icacheStallCycles 176 .name(name() + ".icacheStallCycles") 177 .desc("Number of cycles fetch is stalled on an Icache miss") 178 .prereq(icacheStallCycles); 179 180 fetchedInsts 181 .name(name() + ".Insts") 182 .desc("Number of instructions fetch has processed") 183 .prereq(fetchedInsts); 184 185 fetchedBranches 186 .name(name() + ".Branches") 187 .desc("Number of branches that fetch encountered") 188 .prereq(fetchedBranches); 189 190 predictedBranches 191 .name(name() + ".predictedBranches") 192 .desc("Number of branches that fetch has predicted taken") 193 .prereq(predictedBranches); 194 195 fetchCycles 196 .name(name() + ".Cycles") 197 .desc("Number of cycles fetch has run and was not squashing or" 198 " blocked") 199 .prereq(fetchCycles); 200 201 fetchSquashCycles 202 .name(name() + ".SquashCycles") 203 .desc("Number of cycles fetch has spent squashing") 204 .prereq(fetchSquashCycles); 205 206 fetchTlbCycles 207 .name(name() + ".TlbCycles") 208 .desc("Number of cycles fetch has spent waiting for tlb") 209 .prereq(fetchTlbCycles); 210 211 fetchIdleCycles 212 .name(name() + ".IdleCycles") 213 .desc("Number of cycles fetch was idle") 214 .prereq(fetchIdleCycles); 215 216 fetchBlockedCycles 217 .name(name() + ".BlockedCycles") 218 .desc("Number of cycles fetch has spent blocked") 219 .prereq(fetchBlockedCycles); 220 221 fetchedCacheLines 222 .name(name() + ".CacheLines") 223 .desc("Number of cache lines fetched") 224 .prereq(fetchedCacheLines); 225 226 fetchMiscStallCycles 227 .name(name() + ".MiscStallCycles") 228 .desc("Number of cycles fetch has spent waiting on interrupts, or " 229 "bad addresses, or out of MSHRs") 230 .prereq(fetchMiscStallCycles); 231 232 fetchPendingDrainCycles 233 .name(name() + ".PendingDrainCycles") 234 .desc("Number of cycles fetch has spent waiting on pipes to drain") 235 .prereq(fetchPendingDrainCycles); 236 237 fetchNoActiveThreadStallCycles 238 .name(name() + ".NoActiveThreadStallCycles") 239 .desc("Number of stall cycles due to no active thread to fetch from") 240 .prereq(fetchNoActiveThreadStallCycles); 241 242 fetchPendingTrapStallCycles 243 .name(name() + ".PendingTrapStallCycles") 244 .desc("Number of stall cycles due to pending traps") 245 .prereq(fetchPendingTrapStallCycles); 246 247 fetchPendingQuiesceStallCycles 248 .name(name() + ".PendingQuiesceStallCycles") 249 .desc("Number of stall cycles due to pending quiesce instructions") 250 .prereq(fetchPendingQuiesceStallCycles); 251 252 fetchIcacheWaitRetryStallCycles 253 .name(name() + ".IcacheWaitRetryStallCycles") 254 .desc("Number of stall cycles due to full MSHR") 255 .prereq(fetchIcacheWaitRetryStallCycles); 256 257 fetchIcacheSquashes 258 .name(name() + ".IcacheSquashes") 259 .desc("Number of outstanding Icache misses that were squashed") 260 .prereq(fetchIcacheSquashes); 261 262 fetchTlbSquashes 263 .name(name() + ".ItlbSquashes") 264 .desc("Number of outstanding ITLB misses that were squashed") 265 .prereq(fetchTlbSquashes); 266 267 fetchNisnDist 268 .init(/* base value */ 0, 269 /* last value */ fetchWidth, 270 /* bucket size */ 1) 271 .name(name() + ".rateDist") 272 .desc("Number of instructions fetched each cycle (Total)") 273 .flags(Stats::pdf); 274 275 idleRate 276 .name(name() + ".idleRate") 277 .desc("Percent of cycles fetch was idle") 278 .prereq(idleRate); 279 idleRate = fetchIdleCycles * 100 / cpu->numCycles; 280 281 branchRate 282 .name(name() + ".branchRate") 283 .desc("Number of branch fetches per cycle") 284 .flags(Stats::total); 285 branchRate = fetchedBranches / cpu->numCycles; 286 287 fetchRate 288 .name(name() + ".rate") 289 .desc("Number of inst fetches per cycle") 290 .flags(Stats::total); 291 fetchRate = fetchedInsts / cpu->numCycles; 292} 293 294template<class Impl> 295void 296DefaultFetch<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *time_buffer) 297{ 298 timeBuffer = time_buffer; 299 300 // Create wires to get information from proper places in time buffer. 301 fromDecode = timeBuffer->getWire(-decodeToFetchDelay); 302 fromRename = timeBuffer->getWire(-renameToFetchDelay); 303 fromIEW = timeBuffer->getWire(-iewToFetchDelay); 304 fromCommit = timeBuffer->getWire(-commitToFetchDelay); 305} 306 307template<class Impl> 308void 309DefaultFetch<Impl>::setActiveThreads(std::list<ThreadID> *at_ptr) 310{ 311 activeThreads = at_ptr; 312} 313 314template<class Impl> 315void 316DefaultFetch<Impl>::setFetchQueue(TimeBuffer<FetchStruct> *fq_ptr) 317{ 318 fetchQueue = fq_ptr; 319 320 // Create wire to write information to proper place in fetch queue. 321 toDecode = fetchQueue->getWire(0); 322} 323 324template<class Impl> 325void 326DefaultFetch<Impl>::startupStage() 327{ 328 assert(priorityList.empty()); 329 resetStage(); 330 331 // Fetch needs to start fetching instructions at the very beginning, 332 // so it must start up in active state. 333 switchToActive(); 334} 335 336template<class Impl> 337void 338DefaultFetch<Impl>::resetStage() 339{ 340 numInst = 0; 341 interruptPending = false; 342 cacheBlocked = false; 343 344 priorityList.clear(); 345 346 // Setup PC and nextPC with initial state. 347 for (ThreadID tid = 0; tid < numThreads; ++tid) { 348 fetchStatus[tid] = Running; 349 pc[tid] = cpu->pcState(tid); 350 fetchOffset[tid] = 0; 351 macroop[tid] = NULL; 352 353 delayedCommit[tid] = false; 354 memReq[tid] = NULL; 355 356 stalls[tid].decode = false; 357 stalls[tid].rename = false; 358 stalls[tid].iew = false; 359 stalls[tid].commit = false; 360 stalls[tid].drain = false; 361 362 fetchBufferPC[tid] = 0; 363 fetchBufferValid[tid] = false; 364 365 priorityList.push_back(tid); 366 } 367 368 wroteToTimeBuffer = false; 369 _status = Inactive; 370} 371 372template<class Impl> 373void 374DefaultFetch<Impl>::processCacheCompletion(PacketPtr pkt) 375{ 376 ThreadID tid = pkt->req->threadId(); 377 378 DPRINTF(Fetch, "[tid:%u] Waking up from cache miss.\n", tid); 379 assert(!cpu->switchedOut()); 380 381 // Only change the status if it's still waiting on the icache access 382 // to return. 383 if (fetchStatus[tid] != IcacheWaitResponse || 384 pkt->req != memReq[tid]) { 385 ++fetchIcacheSquashes; 386 delete pkt->req; 387 delete pkt; 388 return; 389 } 390 391 memcpy(fetchBuffer[tid], pkt->getPtr<uint8_t>(), fetchBufferSize); 392 fetchBufferValid[tid] = true; 393 394 // Wake up the CPU (if it went to sleep and was waiting on 395 // this completion event). 396 cpu->wakeCPU(); 397 398 DPRINTF(Activity, "[tid:%u] Activating fetch due to cache completion\n", 399 tid); 400 401 switchToActive(); 402 403 // Only switch to IcacheAccessComplete if we're not stalled as well. 404 if (checkStall(tid)) { 405 fetchStatus[tid] = Blocked; 406 } else { 407 fetchStatus[tid] = IcacheAccessComplete; 408 } 409 410 pkt->req->setAccessLatency(); 411 cpu->ppInstAccessComplete->notify(pkt); 412 // Reset the mem req to NULL. 413 delete pkt->req; 414 delete pkt; 415 memReq[tid] = NULL; 416} 417 418template <class Impl> 419void 420DefaultFetch<Impl>::drainResume() 421{ 422 for (ThreadID i = 0; i < Impl::MaxThreads; ++i) 423 stalls[i].drain = false; 424} 425 426template <class Impl> 427void 428DefaultFetch<Impl>::drainSanityCheck() const 429{ 430 assert(isDrained()); 431 assert(retryPkt == NULL); 432 assert(retryTid == InvalidThreadID); 433 assert(!cacheBlocked); 434 assert(!interruptPending); 435 436 for (ThreadID i = 0; i < numThreads; ++i) { 437 assert(!memReq[i]); 438 assert(!stalls[i].decode); 439 assert(!stalls[i].rename); 440 assert(!stalls[i].iew); 441 assert(!stalls[i].commit); 442 assert(fetchStatus[i] == Idle || stalls[i].drain); 443 } 444 445 branchPred->drainSanityCheck(); 446} 447 448template <class Impl> 449bool 450DefaultFetch<Impl>::isDrained() const 451{ 452 /* Make sure that threads are either idle of that the commit stage 453 * has signaled that draining has completed by setting the drain 454 * stall flag. This effectively forces the pipeline to be disabled 455 * until the whole system is drained (simulation may continue to 456 * drain other components). 457 */ 458 for (ThreadID i = 0; i < numThreads; ++i) { 459 if (!(fetchStatus[i] == Idle || 460 (fetchStatus[i] == Blocked && stalls[i].drain))) 461 return false; 462 } 463 464 /* The pipeline might start up again in the middle of the drain 465 * cycle if the finish translation event is scheduled, so make 466 * sure that's not the case. 467 */ 468 return !finishTranslationEvent.scheduled(); 469} 470 471template <class Impl> 472void 473DefaultFetch<Impl>::takeOverFrom() 474{ 475 assert(cpu->getInstPort().isConnected()); 476 resetStage(); 477 478} 479 480template <class Impl> 481void 482DefaultFetch<Impl>::drainStall(ThreadID tid) 483{ 484 assert(cpu->isDraining()); 485 assert(!stalls[tid].drain); 486 DPRINTF(Drain, "%i: Thread drained.\n", tid); 487 stalls[tid].drain = true; 488} 489 490template <class Impl> 491void 492DefaultFetch<Impl>::wakeFromQuiesce() 493{ 494 DPRINTF(Fetch, "Waking up from quiesce\n"); 495 // Hopefully this is safe 496 // @todo: Allow other threads to wake from quiesce. 497 fetchStatus[0] = Running; 498} 499 500template <class Impl> 501inline void 502DefaultFetch<Impl>::switchToActive() 503{ 504 if (_status == Inactive) { 505 DPRINTF(Activity, "Activating stage.\n"); 506 507 cpu->activateStage(O3CPU::FetchIdx); 508 509 _status = Active; 510 } 511} 512 513template <class Impl> 514inline void 515DefaultFetch<Impl>::switchToInactive() 516{ 517 if (_status == Active) { 518 DPRINTF(Activity, "Deactivating stage.\n"); 519 520 cpu->deactivateStage(O3CPU::FetchIdx); 521 522 _status = Inactive; 523 } 524} 525 526template <class Impl> 527bool 528DefaultFetch<Impl>::lookupAndUpdateNextPC( 529 DynInstPtr &inst, TheISA::PCState &nextPC) 530{ 531 // Do branch prediction check here. 532 // A bit of a misnomer...next_PC is actually the current PC until 533 // this function updates it. 534 bool predict_taken; 535 536 if (!inst->isControl()) { 537 TheISA::advancePC(nextPC, inst->staticInst); 538 inst->setPredTarg(nextPC); 539 inst->setPredTaken(false); 540 return false; 541 } 542 543 ThreadID tid = inst->threadNumber; 544 predict_taken = branchPred->predict(inst->staticInst, inst->seqNum, 545 nextPC, tid); 546 547 if (predict_taken) { 548 DPRINTF(Fetch, "[tid:%i]: [sn:%i]: Branch predicted to be taken to %s.\n", 549 tid, inst->seqNum, nextPC); 550 } else { 551 DPRINTF(Fetch, "[tid:%i]: [sn:%i]:Branch predicted to be not taken.\n", 552 tid, inst->seqNum); 553 } 554 555 DPRINTF(Fetch, "[tid:%i]: [sn:%i] Branch predicted to go to %s.\n", 556 tid, inst->seqNum, nextPC); 557 inst->setPredTarg(nextPC); 558 inst->setPredTaken(predict_taken); 559 560 ++fetchedBranches; 561 562 if (predict_taken) { 563 ++predictedBranches; 564 } 565 566 return predict_taken; 567} 568 569template <class Impl> 570bool 571DefaultFetch<Impl>::fetchCacheLine(Addr vaddr, ThreadID tid, Addr pc) 572{ 573 Fault fault = NoFault; 574 575 assert(!cpu->switchedOut()); 576 577 // @todo: not sure if these should block translation. 578 //AlphaDep 579 if (cacheBlocked) { 580 DPRINTF(Fetch, "[tid:%i] Can't fetch cache line, cache blocked\n", 581 tid); 582 return false; 583 } else if (checkInterrupt(pc) && !delayedCommit[tid]) { 584 // Hold off fetch from getting new instructions when: 585 // Cache is blocked, or 586 // while an interrupt is pending and we're not in PAL mode, or 587 // fetch is switched out. 588 DPRINTF(Fetch, "[tid:%i] Can't fetch cache line, interrupt pending\n", 589 tid); 590 return false; 591 } 592 593 // Align the fetch address to the start of a fetch buffer segment. 594 Addr fetchBufferBlockPC = fetchBufferAlignPC(vaddr); 595 596 DPRINTF(Fetch, "[tid:%i] Fetching cache line %#x for addr %#x\n", 597 tid, fetchBufferBlockPC, vaddr); 598 599 // Setup the memReq to do a read of the first instruction's address. 600 // Set the appropriate read size and flags as well. 601 // Build request here. 602 RequestPtr mem_req = 603 new Request(tid, fetchBufferBlockPC, fetchBufferSize, 604 Request::INST_FETCH, cpu->instMasterId(), pc, 605 cpu->thread[tid]->contextId(), tid); 606 607 mem_req->taskId(cpu->taskId()); 608 609 memReq[tid] = mem_req; 610 611 // Initiate translation of the icache block 612 fetchStatus[tid] = ItlbWait; 613 FetchTranslation *trans = new FetchTranslation(this); 614 cpu->itb->translateTiming(mem_req, cpu->thread[tid]->getTC(), 615 trans, BaseTLB::Execute); 616 return true; 617} 618 619template <class Impl> 620void 621DefaultFetch<Impl>::finishTranslation(Fault fault, RequestPtr mem_req) 622{ 623 ThreadID tid = mem_req->threadId(); 624 Addr fetchBufferBlockPC = mem_req->getVaddr(); 625 626 assert(!cpu->switchedOut()); 627 628 // Wake up CPU if it was idle 629 cpu->wakeCPU(); 630 631 if (fetchStatus[tid] != ItlbWait || mem_req != memReq[tid] || 632 mem_req->getVaddr() != memReq[tid]->getVaddr()) { 633 DPRINTF(Fetch, "[tid:%i] Ignoring itlb completed after squash\n", 634 tid); 635 ++fetchTlbSquashes; 636 delete mem_req; 637 return; 638 } 639 640 641 // If translation was successful, attempt to read the icache block. 642 if (fault == NoFault) { 643 // Check that we're not going off into random memory 644 // If we have, just wait around for commit to squash something and put 645 // us on the right track 646 if (!cpu->system->isMemAddr(mem_req->getPaddr())) { 647 warn("Address %#x is outside of physical memory, stopping fetch\n", 648 mem_req->getPaddr()); 649 fetchStatus[tid] = NoGoodAddr; 650 delete mem_req; 651 memReq[tid] = NULL; 652 return; 653 } 654 655 // Build packet here. 656 PacketPtr data_pkt = new Packet(mem_req, MemCmd::ReadReq); 657 data_pkt->dataDynamicArray(new uint8_t[fetchBufferSize]); 658 659 fetchBufferPC[tid] = fetchBufferBlockPC; 660 fetchBufferValid[tid] = false; 661 DPRINTF(Fetch, "Fetch: Doing instruction read.\n"); 662 663 fetchedCacheLines++; 664 665 // Access the cache. 666 if (!cpu->getInstPort().sendTimingReq(data_pkt)) { 667 assert(retryPkt == NULL); 668 assert(retryTid == InvalidThreadID); 669 DPRINTF(Fetch, "[tid:%i] Out of MSHRs!\n", tid); 670 671 fetchStatus[tid] = IcacheWaitRetry; 672 retryPkt = data_pkt; 673 retryTid = tid; 674 cacheBlocked = true; 675 } else { 676 DPRINTF(Fetch, "[tid:%i]: Doing Icache access.\n", tid); 677 DPRINTF(Activity, "[tid:%i]: Activity: Waiting on I-cache " 678 "response.\n", tid); 679 lastIcacheStall[tid] = curTick(); 680 fetchStatus[tid] = IcacheWaitResponse; 681 } 682 } else { 683 if (!(numInst < fetchWidth)) { 684 assert(!finishTranslationEvent.scheduled()); 685 finishTranslationEvent.setFault(fault); 686 finishTranslationEvent.setReq(mem_req); 687 cpu->schedule(finishTranslationEvent, 688 cpu->clockEdge(Cycles(1))); 689 return; 690 } 691 DPRINTF(Fetch, "[tid:%i] Got back req with addr %#x but expected %#x\n", 692 tid, mem_req->getVaddr(), memReq[tid]->getVaddr()); 693 // Translation faulted, icache request won't be sent. 694 delete mem_req; 695 memReq[tid] = NULL; 696 697 // Send the fault to commit. This thread will not do anything 698 // until commit handles the fault. The only other way it can 699 // wake up is if a squash comes along and changes the PC. 700 TheISA::PCState fetchPC = pc[tid]; 701 702 DPRINTF(Fetch, "[tid:%i]: Translation faulted, building noop.\n", tid); 703 // We will use a nop in ordier to carry the fault. 704 DynInstPtr instruction = buildInst(tid, 705 decoder[tid]->decode(TheISA::NoopMachInst, fetchPC.instAddr()), 706 NULL, fetchPC, fetchPC, false); 707 708 instruction->setPredTarg(fetchPC); 709 instruction->fault = fault; 710 wroteToTimeBuffer = true; 711 712 DPRINTF(Activity, "Activity this cycle.\n"); 713 cpu->activityThisCycle(); 714 715 fetchStatus[tid] = TrapPending; 716 717 DPRINTF(Fetch, "[tid:%i]: Blocked, need to handle the trap.\n", tid); 718 DPRINTF(Fetch, "[tid:%i]: fault (%s) detected @ PC %s.\n", 719 tid, fault->name(), pc[tid]); 720 } 721 _status = updateFetchStatus(); 722} 723 724template <class Impl> 725inline void 726DefaultFetch<Impl>::doSquash(const TheISA::PCState &newPC, 727 const DynInstPtr squashInst, ThreadID tid) 728{ 729 DPRINTF(Fetch, "[tid:%i]: Squashing, setting PC to: %s.\n", 730 tid, newPC); 731 732 pc[tid] = newPC; 733 fetchOffset[tid] = 0; 734 if (squashInst && squashInst->pcState().instAddr() == newPC.instAddr()) 735 macroop[tid] = squashInst->macroop; 736 else 737 macroop[tid] = NULL; 738 decoder[tid]->reset(); 739 740 // Clear the icache miss if it's outstanding. 741 if (fetchStatus[tid] == IcacheWaitResponse) { 742 DPRINTF(Fetch, "[tid:%i]: Squashing outstanding Icache miss.\n", 743 tid); 744 memReq[tid] = NULL; 745 } else if (fetchStatus[tid] == ItlbWait) { 746 DPRINTF(Fetch, "[tid:%i]: Squashing outstanding ITLB miss.\n", 747 tid); 748 memReq[tid] = NULL; 749 } 750 751 // Get rid of the retrying packet if it was from this thread. 752 if (retryTid == tid) { 753 assert(cacheBlocked); 754 if (retryPkt) { 755 delete retryPkt->req; 756 delete retryPkt; 757 } 758 retryPkt = NULL; 759 retryTid = InvalidThreadID; 760 } 761 762 fetchStatus[tid] = Squashing; 763 764 // microops are being squashed, it is not known wheather the 765 // youngest non-squashed microop was marked delayed commit 766 // or not. Setting the flag to true ensures that the 767 // interrupts are not handled when they cannot be, though 768 // some opportunities to handle interrupts may be missed. 769 delayedCommit[tid] = true; 770 771 ++fetchSquashCycles; 772} 773 774template<class Impl> 775void 776DefaultFetch<Impl>::squashFromDecode(const TheISA::PCState &newPC, 777 const DynInstPtr squashInst, 778 const InstSeqNum seq_num, ThreadID tid) 779{ 780 DPRINTF(Fetch, "[tid:%i]: Squashing from decode.\n", tid); 781 782 doSquash(newPC, squashInst, tid); 783 784 // Tell the CPU to remove any instructions that are in flight between 785 // fetch and decode. 786 cpu->removeInstsUntil(seq_num, tid); 787} 788 789template<class Impl> 790bool 791DefaultFetch<Impl>::checkStall(ThreadID tid) const 792{ 793 bool ret_val = false; 794 795 if (cpu->contextSwitch) { 796 DPRINTF(Fetch,"[tid:%i]: Stalling for a context switch.\n",tid); 797 ret_val = true; 798 } else if (stalls[tid].drain) { 799 assert(cpu->isDraining()); 800 DPRINTF(Fetch,"[tid:%i]: Drain stall detected.\n",tid); 801 ret_val = true; 802 } else if (stalls[tid].decode) { 803 DPRINTF(Fetch,"[tid:%i]: Stall from Decode stage detected.\n",tid); 804 ret_val = true; 805 } else if (stalls[tid].rename) { 806 DPRINTF(Fetch,"[tid:%i]: Stall from Rename stage detected.\n",tid); 807 ret_val = true; 808 } else if (stalls[tid].iew) { 809 DPRINTF(Fetch,"[tid:%i]: Stall from IEW stage detected.\n",tid); 810 ret_val = true; 811 } else if (stalls[tid].commit) { 812 DPRINTF(Fetch,"[tid:%i]: Stall from Commit stage detected.\n",tid); 813 ret_val = true; 814 } 815 816 return ret_val; 817} 818 819template<class Impl> 820typename DefaultFetch<Impl>::FetchStatus 821DefaultFetch<Impl>::updateFetchStatus() 822{ 823 //Check Running 824 list<ThreadID>::iterator threads = activeThreads->begin(); 825 list<ThreadID>::iterator end = activeThreads->end(); 826 827 while (threads != end) { 828 ThreadID tid = *threads++; 829 830 if (fetchStatus[tid] == Running || 831 fetchStatus[tid] == Squashing || 832 fetchStatus[tid] == IcacheAccessComplete) { 833 834 if (_status == Inactive) { 835 DPRINTF(Activity, "[tid:%i]: Activating stage.\n",tid); 836 837 if (fetchStatus[tid] == IcacheAccessComplete) { 838 DPRINTF(Activity, "[tid:%i]: Activating fetch due to cache" 839 "completion\n",tid); 840 } 841 842 cpu->activateStage(O3CPU::FetchIdx); 843 } 844 845 return Active; 846 } 847 } 848 849 // Stage is switching from active to inactive, notify CPU of it. 850 if (_status == Active) { 851 DPRINTF(Activity, "Deactivating stage.\n"); 852 853 cpu->deactivateStage(O3CPU::FetchIdx); 854 } 855 856 return Inactive; 857} 858 859template <class Impl> 860void 861DefaultFetch<Impl>::squash(const TheISA::PCState &newPC, 862 const InstSeqNum seq_num, DynInstPtr squashInst, 863 ThreadID tid) 864{ 865 DPRINTF(Fetch, "[tid:%u]: Squash from commit.\n", tid); 866 867 doSquash(newPC, squashInst, tid); 868 869 // Tell the CPU to remove any instructions that are not in the ROB. 870 cpu->removeInstsNotInROB(tid); 871} 872 873template <class Impl> 874void 875DefaultFetch<Impl>::tick() 876{ 877 list<ThreadID>::iterator threads = activeThreads->begin(); 878 list<ThreadID>::iterator end = activeThreads->end(); 879 bool status_change = false; 880 881 wroteToTimeBuffer = false; 882 883 for (ThreadID i = 0; i < Impl::MaxThreads; ++i) { 884 issuePipelinedIfetch[i] = false; 885 } 886 887 while (threads != end) { 888 ThreadID tid = *threads++; 889 890 // Check the signals for each thread to determine the proper status 891 // for each thread. 892 bool updated_status = checkSignalsAndUpdate(tid); 893 status_change = status_change || updated_status; 894 } 895 896 DPRINTF(Fetch, "Running stage.\n"); 897 898 if (FullSystem) { 899 if (fromCommit->commitInfo[0].interruptPending) { 900 interruptPending = true; 901 } 902 903 if (fromCommit->commitInfo[0].clearInterrupt) { 904 interruptPending = false; 905 } 906 } 907 908 for (threadFetched = 0; threadFetched < numFetchingThreads; 909 threadFetched++) { 910 // Fetch each of the actively fetching threads. 911 fetch(status_change); 912 } 913 914 // Record number of instructions fetched this cycle for distribution. 915 fetchNisnDist.sample(numInst); 916 917 if (status_change) { 918 // Change the fetch stage status if there was a status change. 919 _status = updateFetchStatus(); 920 } 921 922 // If there was activity this cycle, inform the CPU of it. 923 if (wroteToTimeBuffer || cpu->contextSwitch) { 924 DPRINTF(Activity, "Activity this cycle.\n"); 925 926 cpu->activityThisCycle(); 927 } 928 929 // Issue the next I-cache request if possible. 930 for (ThreadID i = 0; i < Impl::MaxThreads; ++i) { 931 if (issuePipelinedIfetch[i]) { 932 pipelineIcacheAccesses(i); 933 } 934 } 935 936 // Reset the number of the instruction we've fetched. 937 numInst = 0; 938} 939 940template <class Impl> 941bool 942DefaultFetch<Impl>::checkSignalsAndUpdate(ThreadID tid) 943{ 944 // Update the per thread stall statuses. 945 if (fromDecode->decodeBlock[tid]) { 946 stalls[tid].decode = true; 947 } 948 949 if (fromDecode->decodeUnblock[tid]) { 950 assert(stalls[tid].decode); 951 assert(!fromDecode->decodeBlock[tid]); 952 stalls[tid].decode = false; 953 } 954 955 if (fromRename->renameBlock[tid]) { 956 stalls[tid].rename = true; 957 } 958 959 if (fromRename->renameUnblock[tid]) { 960 assert(stalls[tid].rename); 961 assert(!fromRename->renameBlock[tid]); 962 stalls[tid].rename = false; 963 } 964 965 if (fromIEW->iewBlock[tid]) { 966 stalls[tid].iew = true; 967 } 968 969 if (fromIEW->iewUnblock[tid]) { 970 assert(stalls[tid].iew); 971 assert(!fromIEW->iewBlock[tid]); 972 stalls[tid].iew = false; 973 } 974 975 if (fromCommit->commitBlock[tid]) { 976 stalls[tid].commit = true; 977 } 978 979 if (fromCommit->commitUnblock[tid]) { 980 assert(stalls[tid].commit); 981 assert(!fromCommit->commitBlock[tid]); 982 stalls[tid].commit = false; 983 } 984 985 // Check squash signals from commit. 986 if (fromCommit->commitInfo[tid].squash) { 987 988 DPRINTF(Fetch, "[tid:%u]: Squashing instructions due to squash " 989 "from commit.\n",tid); 990 // In any case, squash. 991 squash(fromCommit->commitInfo[tid].pc, 992 fromCommit->commitInfo[tid].doneSeqNum, 993 fromCommit->commitInfo[tid].squashInst, tid); 994 995 // If it was a branch mispredict on a control instruction, update the 996 // branch predictor with that instruction, otherwise just kill the 997 // invalid state we generated in after sequence number 998 if (fromCommit->commitInfo[tid].mispredictInst && 999 fromCommit->commitInfo[tid].mispredictInst->isControl()) { 1000 branchPred->squash(fromCommit->commitInfo[tid].doneSeqNum, 1001 fromCommit->commitInfo[tid].pc, 1002 fromCommit->commitInfo[tid].branchTaken, 1003 tid); 1004 } else { 1005 branchPred->squash(fromCommit->commitInfo[tid].doneSeqNum, 1006 tid); 1007 } 1008 1009 return true; 1010 } else if (fromCommit->commitInfo[tid].doneSeqNum) { 1011 // Update the branch predictor if it wasn't a squashed instruction 1012 // that was broadcasted. 1013 branchPred->update(fromCommit->commitInfo[tid].doneSeqNum, tid); 1014 } 1015 1016 // Check ROB squash signals from commit. 1017 if (fromCommit->commitInfo[tid].robSquashing) { 1018 DPRINTF(Fetch, "[tid:%u]: ROB is still squashing.\n", tid); 1019 1020 // Continue to squash. 1021 fetchStatus[tid] = Squashing; 1022 1023 return true; 1024 } 1025 1026 // Check squash signals from decode. 1027 if (fromDecode->decodeInfo[tid].squash) { 1028 DPRINTF(Fetch, "[tid:%u]: Squashing instructions due to squash " 1029 "from decode.\n",tid); 1030 1031 // Update the branch predictor. 1032 if (fromDecode->decodeInfo[tid].branchMispredict) { 1033 branchPred->squash(fromDecode->decodeInfo[tid].doneSeqNum, 1034 fromDecode->decodeInfo[tid].nextPC, 1035 fromDecode->decodeInfo[tid].branchTaken, 1036 tid); 1037 } else { 1038 branchPred->squash(fromDecode->decodeInfo[tid].doneSeqNum, 1039 tid); 1040 } 1041 1042 if (fetchStatus[tid] != Squashing) { 1043 1044 DPRINTF(Fetch, "Squashing from decode with PC = %s\n", 1045 fromDecode->decodeInfo[tid].nextPC); 1046 // Squash unless we're already squashing 1047 squashFromDecode(fromDecode->decodeInfo[tid].nextPC, 1048 fromDecode->decodeInfo[tid].squashInst, 1049 fromDecode->decodeInfo[tid].doneSeqNum, 1050 tid); 1051 1052 return true; 1053 } 1054 } 1055 1056 if (checkStall(tid) && 1057 fetchStatus[tid] != IcacheWaitResponse && 1058 fetchStatus[tid] != IcacheWaitRetry && 1059 fetchStatus[tid] != ItlbWait && 1060 fetchStatus[tid] != QuiescePending) { 1061 DPRINTF(Fetch, "[tid:%i]: Setting to blocked\n",tid); 1062 1063 fetchStatus[tid] = Blocked; 1064 1065 return true; 1066 } 1067 1068 if (fetchStatus[tid] == Blocked || 1069 fetchStatus[tid] == Squashing) { 1070 // Switch status to running if fetch isn't being told to block or 1071 // squash this cycle. 1072 DPRINTF(Fetch, "[tid:%i]: Done squashing, switching to running.\n", 1073 tid); 1074 1075 fetchStatus[tid] = Running; 1076 1077 return true; 1078 } 1079 1080 // If we've reached this point, we have not gotten any signals that 1081 // cause fetch to change its status. Fetch remains the same as before. 1082 return false; 1083} 1084 1085template<class Impl> 1086typename Impl::DynInstPtr 1087DefaultFetch<Impl>::buildInst(ThreadID tid, StaticInstPtr staticInst, 1088 StaticInstPtr curMacroop, TheISA::PCState thisPC, 1089 TheISA::PCState nextPC, bool trace) 1090{ 1091 // Get a sequence number. 1092 InstSeqNum seq = cpu->getAndIncrementInstSeq(); 1093 1094 // Create a new DynInst from the instruction fetched. 1095 DynInstPtr instruction = 1096 new DynInst(staticInst, curMacroop, thisPC, nextPC, seq, cpu); 1097 instruction->setTid(tid); 1098 1099 instruction->setASID(tid); 1100 1101 instruction->setThreadState(cpu->thread[tid]); 1102 1103 DPRINTF(Fetch, "[tid:%i]: Instruction PC %#x (%d) created " 1104 "[sn:%lli].\n", tid, thisPC.instAddr(), 1105 thisPC.microPC(), seq); 1106 1107 DPRINTF(Fetch, "[tid:%i]: Instruction is: %s\n", tid, 1108 instruction->staticInst-> 1109 disassemble(thisPC.instAddr())); 1110 1111#if TRACING_ON 1112 if (trace) { 1113 instruction->traceData = 1114 cpu->getTracer()->getInstRecord(curTick(), cpu->tcBase(tid), 1115 instruction->staticInst, thisPC, curMacroop); 1116 } 1117#else 1118 instruction->traceData = NULL; 1119#endif 1120 1121 // Add instruction to the CPU's list of instructions. 1122 instruction->setInstListIt(cpu->addInst(instruction)); 1123 1124 // Write the instruction to the first slot in the queue 1125 // that heads to decode. 1126 assert(numInst < fetchWidth); 1127 toDecode->insts[toDecode->size++] = instruction; 1128 1129 // Keep track of if we can take an interrupt at this boundary 1130 delayedCommit[tid] = instruction->isDelayedCommit(); 1131 1132 return instruction; 1133} 1134 1135template<class Impl> 1136void 1137DefaultFetch<Impl>::fetch(bool &status_change) 1138{ 1139 ////////////////////////////////////////// 1140 // Start actual fetch 1141 ////////////////////////////////////////// 1142 ThreadID tid = getFetchingThread(fetchPolicy); 1143 1144 assert(!cpu->switchedOut()); 1145 1146 if (tid == InvalidThreadID) { 1147 // Breaks looping condition in tick() 1148 threadFetched = numFetchingThreads; 1149 1150 if (numThreads == 1) { // @todo Per-thread stats 1151 profileStall(0); 1152 } 1153 1154 return; 1155 } 1156 1157 DPRINTF(Fetch, "Attempting to fetch from [tid:%i]\n", tid); 1158 1159 // The current PC. 1160 TheISA::PCState thisPC = pc[tid]; 1161 1162 Addr pcOffset = fetchOffset[tid]; 1163 Addr fetchAddr = (thisPC.instAddr() + pcOffset) & BaseCPU::PCMask; 1164 1165 bool inRom = isRomMicroPC(thisPC.microPC()); 1166 1167 // If returning from the delay of a cache miss, then update the status 1168 // to running, otherwise do the cache access. Possibly move this up 1169 // to tick() function. 1170 if (fetchStatus[tid] == IcacheAccessComplete) { 1171 DPRINTF(Fetch, "[tid:%i]: Icache miss is complete.\n", tid); 1172 1173 fetchStatus[tid] = Running; 1174 status_change = true; 1175 } else if (fetchStatus[tid] == Running) { 1176 // Align the fetch PC so its at the start of a fetch buffer segment. 1177 Addr fetchBufferBlockPC = fetchBufferAlignPC(fetchAddr); 1178 1179 // If buffer is no longer valid or fetchAddr has moved to point 1180 // to the next cache block, AND we have no remaining ucode 1181 // from a macro-op, then start fetch from icache. 1182 if (!(fetchBufferValid[tid] && fetchBufferBlockPC == fetchBufferPC[tid]) 1183 && !inRom && !macroop[tid]) { 1184 DPRINTF(Fetch, "[tid:%i]: Attempting to translate and read " 1185 "instruction, starting at PC %s.\n", tid, thisPC); 1186 1187 fetchCacheLine(fetchAddr, tid, thisPC.instAddr()); 1188 1189 if (fetchStatus[tid] == IcacheWaitResponse) 1190 ++icacheStallCycles; 1191 else if (fetchStatus[tid] == ItlbWait) 1192 ++fetchTlbCycles; 1193 else 1194 ++fetchMiscStallCycles; 1195 return; 1196 } else if ((checkInterrupt(thisPC.instAddr()) && !delayedCommit[tid])) { 1197 // Stall CPU if an interrupt is posted and we're not issuing 1198 // an delayed commit micro-op currently (delayed commit instructions 1199 // are not interruptable by interrupts, only faults) 1200 ++fetchMiscStallCycles; 1201 DPRINTF(Fetch, "[tid:%i]: Fetch is stalled!\n", tid); 1202 return; 1203 } 1204 } else { 1205 if (fetchStatus[tid] == Idle) { 1206 ++fetchIdleCycles; 1207 DPRINTF(Fetch, "[tid:%i]: Fetch is idle!\n", tid); 1208 } 1209 1210 // Status is Idle, so fetch should do nothing. 1211 return; 1212 } 1213 1214 ++fetchCycles; 1215 1216 TheISA::PCState nextPC = thisPC; 1217 1218 StaticInstPtr staticInst = NULL; 1219 StaticInstPtr curMacroop = macroop[tid]; 1220 1221 // If the read of the first instruction was successful, then grab the 1222 // instructions from the rest of the cache line and put them into the 1223 // queue heading to decode. 1224 1225 DPRINTF(Fetch, "[tid:%i]: Adding instructions to queue to " 1226 "decode.\n", tid); 1227 1228 // Need to keep track of whether or not a predicted branch 1229 // ended this fetch block. 1230 bool predictedBranch = false; 1231 1232 TheISA::MachInst *cacheInsts = 1233 reinterpret_cast<TheISA::MachInst *>(fetchBuffer[tid]); 1234 1235 const unsigned numInsts = fetchBufferSize / instSize; 1236 unsigned blkOffset = (fetchAddr - fetchBufferPC[tid]) / instSize; 1237 1238 // Loop through instruction memory from the cache. 1239 // Keep issuing while fetchWidth is available and branch is not 1240 // predicted taken 1241 while (numInst < fetchWidth && !predictedBranch) { 1242 1243 // We need to process more memory if we aren't going to get a 1244 // StaticInst from the rom, the current macroop, or what's already 1245 // in the decoder. 1246 bool needMem = !inRom && !curMacroop && 1247 !decoder[tid]->instReady(); 1248 fetchAddr = (thisPC.instAddr() + pcOffset) & BaseCPU::PCMask; 1249 Addr fetchBufferBlockPC = fetchBufferAlignPC(fetchAddr); 1250 1251 if (needMem) { 1252 // If buffer is no longer valid or fetchAddr has moved to point 1253 // to the next cache block then start fetch from icache. 1254 if (!fetchBufferValid[tid] || 1255 fetchBufferBlockPC != fetchBufferPC[tid]) 1256 break; 1257 1258 if (blkOffset >= numInsts) { 1259 // We need to process more memory, but we've run out of the 1260 // current block. 1261 break; 1262 } 1263 1264 if (ISA_HAS_DELAY_SLOT && pcOffset == 0) { 1265 // Walk past any annulled delay slot instructions. 1266 Addr pcAddr = thisPC.instAddr() & BaseCPU::PCMask; 1267 while (fetchAddr != pcAddr && blkOffset < numInsts) { 1268 blkOffset++; 1269 fetchAddr += instSize; 1270 } 1271 if (blkOffset >= numInsts) 1272 break; 1273 } 1274 1275 MachInst inst = TheISA::gtoh(cacheInsts[blkOffset]); 1276 decoder[tid]->moreBytes(thisPC, fetchAddr, inst); 1277 1278 if (decoder[tid]->needMoreBytes()) { 1279 blkOffset++; 1280 fetchAddr += instSize; 1281 pcOffset += instSize; 1282 } 1283 } 1284 1285 // Extract as many instructions and/or microops as we can from 1286 // the memory we've processed so far. 1287 do { 1288 if (!(curMacroop || inRom)) { 1289 if (decoder[tid]->instReady()) { 1290 staticInst = decoder[tid]->decode(thisPC); 1291 1292 // Increment stat of fetched instructions. 1293 ++fetchedInsts; 1294 1295 if (staticInst->isMacroop()) { 1296 curMacroop = staticInst; 1297 } else { 1298 pcOffset = 0; 1299 } 1300 } else { 1301 // We need more bytes for this instruction so blkOffset and 1302 // pcOffset will be updated 1303 break; 1304 } 1305 } 1306 // Whether we're moving to a new macroop because we're at the 1307 // end of the current one, or the branch predictor incorrectly 1308 // thinks we are... 1309 bool newMacro = false; 1310 if (curMacroop || inRom) { 1311 if (inRom) { 1312 staticInst = cpu->microcodeRom.fetchMicroop( 1313 thisPC.microPC(), curMacroop); 1314 } else { 1315 staticInst = curMacroop->fetchMicroop(thisPC.microPC()); 1316 } 1317 newMacro |= staticInst->isLastMicroop(); 1318 } 1319 1320 DynInstPtr instruction = 1321 buildInst(tid, staticInst, curMacroop, 1322 thisPC, nextPC, true); 1323 1324 ppFetch->notify(instruction); 1325 numInst++; 1326 1327#if TRACING_ON 1328 if (DTRACE(O3PipeView)) { 1329 instruction->fetchTick = curTick(); 1330 } 1331#endif 1332 1333 nextPC = thisPC; 1334 1335 // If we're branching after this instruction, quit fetching 1336 // from the same block. 1337 predictedBranch |= thisPC.branching(); 1338 predictedBranch |= 1339 lookupAndUpdateNextPC(instruction, nextPC); 1340 if (predictedBranch) { 1341 DPRINTF(Fetch, "Branch detected with PC = %s\n", thisPC); 1342 } 1343 1344 newMacro |= thisPC.instAddr() != nextPC.instAddr(); 1345 1346 // Move to the next instruction, unless we have a branch. 1347 thisPC = nextPC; 1348 inRom = isRomMicroPC(thisPC.microPC()); 1349 1350 if (newMacro) { 1351 fetchAddr = thisPC.instAddr() & BaseCPU::PCMask; 1352 blkOffset = (fetchAddr - fetchBufferPC[tid]) / instSize; 1353 pcOffset = 0; 1354 curMacroop = NULL; 1355 } 1356 1357 if (instruction->isQuiesce()) { 1358 DPRINTF(Fetch, 1359 "Quiesce instruction encountered, halting fetch!"); 1360 fetchStatus[tid] = QuiescePending; 1361 status_change = true; 1362 break; 1363 } 1364 } while ((curMacroop || decoder[tid]->instReady()) && 1365 numInst < fetchWidth); 1366 } 1367 1368 if (predictedBranch) { 1369 DPRINTF(Fetch, "[tid:%i]: Done fetching, predicted branch " 1370 "instruction encountered.\n", tid); 1371 } else if (numInst >= fetchWidth) { 1372 DPRINTF(Fetch, "[tid:%i]: Done fetching, reached fetch bandwidth " 1373 "for this cycle.\n", tid); 1374 } else if (blkOffset >= fetchBufferSize) { 1375 DPRINTF(Fetch, "[tid:%i]: Done fetching, reached the end of the" 1376 "fetch buffer.\n", tid); 1377 } 1378 1379 macroop[tid] = curMacroop; 1380 fetchOffset[tid] = pcOffset; 1381 1382 if (numInst > 0) { 1383 wroteToTimeBuffer = true; 1384 } 1385 1386 pc[tid] = thisPC; 1387 1388 // pipeline a fetch if we're crossing a fetch buffer boundary and not in 1389 // a state that would preclude fetching 1390 fetchAddr = (thisPC.instAddr() + pcOffset) & BaseCPU::PCMask; 1391 Addr fetchBufferBlockPC = fetchBufferAlignPC(fetchAddr); 1392 issuePipelinedIfetch[tid] = fetchBufferBlockPC != fetchBufferPC[tid] && 1393 fetchStatus[tid] != IcacheWaitResponse && 1394 fetchStatus[tid] != ItlbWait && 1395 fetchStatus[tid] != IcacheWaitRetry && 1396 fetchStatus[tid] != QuiescePending && 1397 !curMacroop; 1398} 1399 1400template<class Impl> 1401void 1402DefaultFetch<Impl>::recvRetry() 1403{ 1404 if (retryPkt != NULL) { 1405 assert(cacheBlocked); 1406 assert(retryTid != InvalidThreadID); 1407 assert(fetchStatus[retryTid] == IcacheWaitRetry); 1408 1409 if (cpu->getInstPort().sendTimingReq(retryPkt)) { 1410 fetchStatus[retryTid] = IcacheWaitResponse; 1411 retryPkt = NULL; 1412 retryTid = InvalidThreadID; 1413 cacheBlocked = false; 1414 } 1415 } else { 1416 assert(retryTid == InvalidThreadID); 1417 // Access has been squashed since it was sent out. Just clear 1418 // the cache being blocked. 1419 cacheBlocked = false; 1420 } 1421} 1422 1423/////////////////////////////////////// 1424// // 1425// SMT FETCH POLICY MAINTAINED HERE // 1426// // 1427/////////////////////////////////////// 1428template<class Impl> 1429ThreadID 1430DefaultFetch<Impl>::getFetchingThread(FetchPriority &fetch_priority) 1431{ 1432 if (numThreads > 1) { 1433 switch (fetch_priority) { 1434 1435 case SingleThread: 1436 return 0; 1437 1438 case RoundRobin: 1439 return roundRobin(); 1440 1441 case IQ: 1442 return iqCount(); 1443 1444 case LSQ: 1445 return lsqCount(); 1446 1447 case Branch: 1448 return branchCount(); 1449 1450 default: 1451 return InvalidThreadID; 1452 } 1453 } else { 1454 list<ThreadID>::iterator thread = activeThreads->begin(); 1455 if (thread == activeThreads->end()) { 1456 return InvalidThreadID; 1457 } 1458 1459 ThreadID tid = *thread; 1460 1461 if (fetchStatus[tid] == Running || 1462 fetchStatus[tid] == IcacheAccessComplete || 1463 fetchStatus[tid] == Idle) { 1464 return tid; 1465 } else { 1466 return InvalidThreadID; 1467 } 1468 } 1469} 1470 1471 1472template<class Impl> 1473ThreadID 1474DefaultFetch<Impl>::roundRobin() 1475{ 1476 list<ThreadID>::iterator pri_iter = priorityList.begin(); 1477 list<ThreadID>::iterator end = priorityList.end(); 1478 1479 ThreadID high_pri; 1480 1481 while (pri_iter != end) { 1482 high_pri = *pri_iter; 1483 1484 assert(high_pri <= numThreads); 1485 1486 if (fetchStatus[high_pri] == Running || 1487 fetchStatus[high_pri] == IcacheAccessComplete || 1488 fetchStatus[high_pri] == Idle) { 1489 1490 priorityList.erase(pri_iter); 1491 priorityList.push_back(high_pri); 1492 1493 return high_pri; 1494 } 1495 1496 pri_iter++; 1497 } 1498 1499 return InvalidThreadID; 1500} 1501 1502template<class Impl> 1503ThreadID 1504DefaultFetch<Impl>::iqCount() 1505{ 1506 std::priority_queue<unsigned> PQ; 1507 std::map<unsigned, ThreadID> threadMap; 1508 1509 list<ThreadID>::iterator threads = activeThreads->begin(); 1510 list<ThreadID>::iterator end = activeThreads->end(); 1511 1512 while (threads != end) { 1513 ThreadID tid = *threads++; 1514 unsigned iqCount = fromIEW->iewInfo[tid].iqCount; 1515 1516 PQ.push(iqCount); 1517 threadMap[iqCount] = tid; 1518 } 1519 1520 while (!PQ.empty()) { 1521 ThreadID high_pri = threadMap[PQ.top()]; 1522 1523 if (fetchStatus[high_pri] == Running || 1524 fetchStatus[high_pri] == IcacheAccessComplete || 1525 fetchStatus[high_pri] == Idle) 1526 return high_pri; 1527 else 1528 PQ.pop(); 1529 1530 } 1531 1532 return InvalidThreadID; 1533} 1534 1535template<class Impl> 1536ThreadID 1537DefaultFetch<Impl>::lsqCount() 1538{ 1539 std::priority_queue<unsigned> PQ; 1540 std::map<unsigned, ThreadID> threadMap; 1541 1542 list<ThreadID>::iterator threads = activeThreads->begin(); 1543 list<ThreadID>::iterator end = activeThreads->end(); 1544 1545 while (threads != end) { 1546 ThreadID tid = *threads++; 1547 unsigned ldstqCount = fromIEW->iewInfo[tid].ldstqCount; 1548 1549 PQ.push(ldstqCount); 1550 threadMap[ldstqCount] = tid; 1551 } 1552 1553 while (!PQ.empty()) { 1554 ThreadID high_pri = threadMap[PQ.top()]; 1555 1556 if (fetchStatus[high_pri] == Running || 1557 fetchStatus[high_pri] == IcacheAccessComplete || 1558 fetchStatus[high_pri] == Idle) 1559 return high_pri; 1560 else 1561 PQ.pop(); 1562 } 1563 1564 return InvalidThreadID; 1565} 1566 1567template<class Impl> 1568ThreadID 1569DefaultFetch<Impl>::branchCount() 1570{ 1571#if 0 1572 list<ThreadID>::iterator thread = activeThreads->begin(); 1573 assert(thread != activeThreads->end()); 1574 ThreadID tid = *thread; 1575#endif 1576 1577 panic("Branch Count Fetch policy unimplemented\n"); 1578 return InvalidThreadID; 1579} 1580 1581template<class Impl> 1582void 1583DefaultFetch<Impl>::pipelineIcacheAccesses(ThreadID tid) 1584{ 1585 if (!issuePipelinedIfetch[tid]) { 1586 return; 1587 } 1588 1589 // The next PC to access. 1590 TheISA::PCState thisPC = pc[tid]; 1591 1592 if (isRomMicroPC(thisPC.microPC())) { 1593 return; 1594 } 1595 1596 Addr pcOffset = fetchOffset[tid]; 1597 Addr fetchAddr = (thisPC.instAddr() + pcOffset) & BaseCPU::PCMask; 1598 1599 // Align the fetch PC so its at the start of a fetch buffer segment. 1600 Addr fetchBufferBlockPC = fetchBufferAlignPC(fetchAddr); 1601 1602 // Unless buffer already got the block, fetch it from icache. 1603 if (!(fetchBufferValid[tid] && fetchBufferBlockPC == fetchBufferPC[tid])) { 1604 DPRINTF(Fetch, "[tid:%i]: Issuing a pipelined I-cache access, " 1605 "starting at PC %s.\n", tid, thisPC); 1606 1607 fetchCacheLine(fetchAddr, tid, thisPC.instAddr()); 1608 } 1609} 1610 1611template<class Impl> 1612void 1613DefaultFetch<Impl>::profileStall(ThreadID tid) { 1614 DPRINTF(Fetch,"There are no more threads available to fetch from.\n"); 1615 1616 // @todo Per-thread stats 1617 1618 if (stalls[tid].drain) { 1619 ++fetchPendingDrainCycles; 1620 DPRINTF(Fetch, "Fetch is waiting for a drain!\n"); 1621 } else if (activeThreads->empty()) { 1622 ++fetchNoActiveThreadStallCycles; 1623 DPRINTF(Fetch, "Fetch has no active thread!\n"); 1624 } else if (fetchStatus[tid] == Blocked) { 1625 ++fetchBlockedCycles; 1626 DPRINTF(Fetch, "[tid:%i]: Fetch is blocked!\n", tid); 1627 } else if (fetchStatus[tid] == Squashing) { 1628 ++fetchSquashCycles; 1629 DPRINTF(Fetch, "[tid:%i]: Fetch is squashing!\n", tid); 1630 } else if (fetchStatus[tid] == IcacheWaitResponse) { 1631 ++icacheStallCycles; 1632 DPRINTF(Fetch, "[tid:%i]: Fetch is waiting cache response!\n", 1633 tid); 1634 } else if (fetchStatus[tid] == ItlbWait) { 1635 ++fetchTlbCycles; 1636 DPRINTF(Fetch, "[tid:%i]: Fetch is waiting ITLB walk to " 1637 "finish!\n", tid); 1638 } else if (fetchStatus[tid] == TrapPending) { 1639 ++fetchPendingTrapStallCycles; 1640 DPRINTF(Fetch, "[tid:%i]: Fetch is waiting for a pending trap!\n", 1641 tid); 1642 } else if (fetchStatus[tid] == QuiescePending) { 1643 ++fetchPendingQuiesceStallCycles; 1644 DPRINTF(Fetch, "[tid:%i]: Fetch is waiting for a pending quiesce " 1645 "instruction!\n", tid); 1646 } else if (fetchStatus[tid] == IcacheWaitRetry) { 1647 ++fetchIcacheWaitRetryStallCycles; 1648 DPRINTF(Fetch, "[tid:%i]: Fetch is waiting for an I-cache retry!\n", 1649 tid); 1650 } else if (fetchStatus[tid] == NoGoodAddr) { 1651 DPRINTF(Fetch, "[tid:%i]: Fetch predicted non-executable address\n", 1652 tid); 1653 } else { 1654 DPRINTF(Fetch, "[tid:%i]: Unexpected fetch stall reason (Status: %i).\n", 1655 tid, fetchStatus[tid]); 1656 } 1657} 1658 1659#endif//__CPU_O3_FETCH_IMPL_HH__ 1660