fetch_impl.hh revision 10023:91faf6649de0
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 == false); 434 assert(interruptPending == false); 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 memReq[tid] = mem_req; 608 609 // Initiate translation of the icache block 610 fetchStatus[tid] = ItlbWait; 611 FetchTranslation *trans = new FetchTranslation(this); 612 cpu->itb->translateTiming(mem_req, cpu->thread[tid]->getTC(), 613 trans, BaseTLB::Execute); 614 return true; 615} 616 617template <class Impl> 618void 619DefaultFetch<Impl>::finishTranslation(Fault fault, RequestPtr mem_req) 620{ 621 ThreadID tid = mem_req->threadId(); 622 Addr fetchBufferBlockPC = mem_req->getVaddr(); 623 624 assert(!cpu->switchedOut()); 625 626 // Wake up CPU if it was idle 627 cpu->wakeCPU(); 628 629 if (fetchStatus[tid] != ItlbWait || mem_req != memReq[tid] || 630 mem_req->getVaddr() != memReq[tid]->getVaddr()) { 631 DPRINTF(Fetch, "[tid:%i] Ignoring itlb completed after squash\n", 632 tid); 633 ++fetchTlbSquashes; 634 delete mem_req; 635 return; 636 } 637 638 639 // If translation was successful, attempt to read the icache block. 640 if (fault == NoFault) { 641 // Check that we're not going off into random memory 642 // If we have, just wait around for commit to squash something and put 643 // us on the right track 644 if (!cpu->system->isMemAddr(mem_req->getPaddr())) { 645 warn("Address %#x is outside of physical memory, stopping fetch\n", 646 mem_req->getPaddr()); 647 fetchStatus[tid] = NoGoodAddr; 648 delete mem_req; 649 memReq[tid] = NULL; 650 return; 651 } 652 653 // Build packet here. 654 PacketPtr data_pkt = new Packet(mem_req, MemCmd::ReadReq); 655 data_pkt->dataDynamicArray(new uint8_t[fetchBufferSize]); 656 657 fetchBufferPC[tid] = fetchBufferBlockPC; 658 fetchBufferValid[tid] = false; 659 DPRINTF(Fetch, "Fetch: Doing instruction read.\n"); 660 661 fetchedCacheLines++; 662 663 // Access the cache. 664 if (!cpu->getInstPort().sendTimingReq(data_pkt)) { 665 assert(retryPkt == NULL); 666 assert(retryTid == InvalidThreadID); 667 DPRINTF(Fetch, "[tid:%i] Out of MSHRs!\n", tid); 668 669 fetchStatus[tid] = IcacheWaitRetry; 670 retryPkt = data_pkt; 671 retryTid = tid; 672 cacheBlocked = true; 673 } else { 674 DPRINTF(Fetch, "[tid:%i]: Doing Icache access.\n", tid); 675 DPRINTF(Activity, "[tid:%i]: Activity: Waiting on I-cache " 676 "response.\n", tid); 677 lastIcacheStall[tid] = curTick(); 678 fetchStatus[tid] = IcacheWaitResponse; 679 } 680 } else { 681 if (!(numInst < fetchWidth)) { 682 assert(!finishTranslationEvent.scheduled()); 683 finishTranslationEvent.setFault(fault); 684 finishTranslationEvent.setReq(mem_req); 685 cpu->schedule(finishTranslationEvent, 686 cpu->clockEdge(Cycles(1))); 687 return; 688 } 689 DPRINTF(Fetch, "[tid:%i] Got back req with addr %#x but expected %#x\n", 690 tid, mem_req->getVaddr(), memReq[tid]->getVaddr()); 691 // Translation faulted, icache request won't be sent. 692 delete mem_req; 693 memReq[tid] = NULL; 694 695 // Send the fault to commit. This thread will not do anything 696 // until commit handles the fault. The only other way it can 697 // wake up is if a squash comes along and changes the PC. 698 TheISA::PCState fetchPC = pc[tid]; 699 700 DPRINTF(Fetch, "[tid:%i]: Translation faulted, building noop.\n", tid); 701 // We will use a nop in ordier to carry the fault. 702 DynInstPtr instruction = buildInst(tid, 703 decoder[tid]->decode(TheISA::NoopMachInst, fetchPC.instAddr()), 704 NULL, fetchPC, fetchPC, false); 705 706 instruction->setPredTarg(fetchPC); 707 instruction->fault = fault; 708 wroteToTimeBuffer = true; 709 710 DPRINTF(Activity, "Activity this cycle.\n"); 711 cpu->activityThisCycle(); 712 713 fetchStatus[tid] = TrapPending; 714 715 DPRINTF(Fetch, "[tid:%i]: Blocked, need to handle the trap.\n", tid); 716 DPRINTF(Fetch, "[tid:%i]: fault (%s) detected @ PC %s.\n", 717 tid, fault->name(), pc[tid]); 718 } 719 _status = updateFetchStatus(); 720} 721 722template <class Impl> 723inline void 724DefaultFetch<Impl>::doSquash(const TheISA::PCState &newPC, 725 const DynInstPtr squashInst, ThreadID tid) 726{ 727 DPRINTF(Fetch, "[tid:%i]: Squashing, setting PC to: %s.\n", 728 tid, newPC); 729 730 pc[tid] = newPC; 731 fetchOffset[tid] = 0; 732 if (squashInst && squashInst->pcState().instAddr() == newPC.instAddr()) 733 macroop[tid] = squashInst->macroop; 734 else 735 macroop[tid] = NULL; 736 decoder[tid]->reset(); 737 738 // Clear the icache miss if it's outstanding. 739 if (fetchStatus[tid] == IcacheWaitResponse) { 740 DPRINTF(Fetch, "[tid:%i]: Squashing outstanding Icache miss.\n", 741 tid); 742 memReq[tid] = NULL; 743 } else if (fetchStatus[tid] == ItlbWait) { 744 DPRINTF(Fetch, "[tid:%i]: Squashing outstanding ITLB miss.\n", 745 tid); 746 memReq[tid] = NULL; 747 } 748 749 // Get rid of the retrying packet if it was from this thread. 750 if (retryTid == tid) { 751 assert(cacheBlocked); 752 if (retryPkt) { 753 delete retryPkt->req; 754 delete retryPkt; 755 } 756 retryPkt = NULL; 757 retryTid = InvalidThreadID; 758 } 759 760 fetchStatus[tid] = Squashing; 761 762 // microops are being squashed, it is not known wheather the 763 // youngest non-squashed microop was marked delayed commit 764 // or not. Setting the flag to true ensures that the 765 // interrupts are not handled when they cannot be, though 766 // some opportunities to handle interrupts may be missed. 767 delayedCommit[tid] = true; 768 769 ++fetchSquashCycles; 770} 771 772template<class Impl> 773void 774DefaultFetch<Impl>::squashFromDecode(const TheISA::PCState &newPC, 775 const DynInstPtr squashInst, 776 const InstSeqNum seq_num, ThreadID tid) 777{ 778 DPRINTF(Fetch, "[tid:%i]: Squashing from decode.\n", tid); 779 780 doSquash(newPC, squashInst, tid); 781 782 // Tell the CPU to remove any instructions that are in flight between 783 // fetch and decode. 784 cpu->removeInstsUntil(seq_num, tid); 785} 786 787template<class Impl> 788bool 789DefaultFetch<Impl>::checkStall(ThreadID tid) const 790{ 791 bool ret_val = false; 792 793 if (cpu->contextSwitch) { 794 DPRINTF(Fetch,"[tid:%i]: Stalling for a context switch.\n",tid); 795 ret_val = true; 796 } else if (stalls[tid].drain) { 797 assert(cpu->isDraining()); 798 DPRINTF(Fetch,"[tid:%i]: Drain stall detected.\n",tid); 799 ret_val = true; 800 } else if (stalls[tid].decode) { 801 DPRINTF(Fetch,"[tid:%i]: Stall from Decode stage detected.\n",tid); 802 ret_val = true; 803 } else if (stalls[tid].rename) { 804 DPRINTF(Fetch,"[tid:%i]: Stall from Rename stage detected.\n",tid); 805 ret_val = true; 806 } else if (stalls[tid].iew) { 807 DPRINTF(Fetch,"[tid:%i]: Stall from IEW stage detected.\n",tid); 808 ret_val = true; 809 } else if (stalls[tid].commit) { 810 DPRINTF(Fetch,"[tid:%i]: Stall from Commit stage detected.\n",tid); 811 ret_val = true; 812 } 813 814 return ret_val; 815} 816 817template<class Impl> 818typename DefaultFetch<Impl>::FetchStatus 819DefaultFetch<Impl>::updateFetchStatus() 820{ 821 //Check Running 822 list<ThreadID>::iterator threads = activeThreads->begin(); 823 list<ThreadID>::iterator end = activeThreads->end(); 824 825 while (threads != end) { 826 ThreadID tid = *threads++; 827 828 if (fetchStatus[tid] == Running || 829 fetchStatus[tid] == Squashing || 830 fetchStatus[tid] == IcacheAccessComplete) { 831 832 if (_status == Inactive) { 833 DPRINTF(Activity, "[tid:%i]: Activating stage.\n",tid); 834 835 if (fetchStatus[tid] == IcacheAccessComplete) { 836 DPRINTF(Activity, "[tid:%i]: Activating fetch due to cache" 837 "completion\n",tid); 838 } 839 840 cpu->activateStage(O3CPU::FetchIdx); 841 } 842 843 return Active; 844 } 845 } 846 847 // Stage is switching from active to inactive, notify CPU of it. 848 if (_status == Active) { 849 DPRINTF(Activity, "Deactivating stage.\n"); 850 851 cpu->deactivateStage(O3CPU::FetchIdx); 852 } 853 854 return Inactive; 855} 856 857template <class Impl> 858void 859DefaultFetch<Impl>::squash(const TheISA::PCState &newPC, 860 const InstSeqNum seq_num, DynInstPtr squashInst, 861 ThreadID tid) 862{ 863 DPRINTF(Fetch, "[tid:%u]: Squash from commit.\n", tid); 864 865 doSquash(newPC, squashInst, tid); 866 867 // Tell the CPU to remove any instructions that are not in the ROB. 868 cpu->removeInstsNotInROB(tid); 869} 870 871template <class Impl> 872void 873DefaultFetch<Impl>::tick() 874{ 875 list<ThreadID>::iterator threads = activeThreads->begin(); 876 list<ThreadID>::iterator end = activeThreads->end(); 877 bool status_change = false; 878 879 wroteToTimeBuffer = false; 880 881 for (ThreadID i = 0; i < Impl::MaxThreads; ++i) { 882 issuePipelinedIfetch[i] = false; 883 } 884 885 while (threads != end) { 886 ThreadID tid = *threads++; 887 888 // Check the signals for each thread to determine the proper status 889 // for each thread. 890 bool updated_status = checkSignalsAndUpdate(tid); 891 status_change = status_change || updated_status; 892 } 893 894 DPRINTF(Fetch, "Running stage.\n"); 895 896 if (FullSystem) { 897 if (fromCommit->commitInfo[0].interruptPending) { 898 interruptPending = true; 899 } 900 901 if (fromCommit->commitInfo[0].clearInterrupt) { 902 interruptPending = false; 903 } 904 } 905 906 for (threadFetched = 0; threadFetched < numFetchingThreads; 907 threadFetched++) { 908 // Fetch each of the actively fetching threads. 909 fetch(status_change); 910 } 911 912 // Record number of instructions fetched this cycle for distribution. 913 fetchNisnDist.sample(numInst); 914 915 if (status_change) { 916 // Change the fetch stage status if there was a status change. 917 _status = updateFetchStatus(); 918 } 919 920 // If there was activity this cycle, inform the CPU of it. 921 if (wroteToTimeBuffer || cpu->contextSwitch) { 922 DPRINTF(Activity, "Activity this cycle.\n"); 923 924 cpu->activityThisCycle(); 925 } 926 927 // Issue the next I-cache request if possible. 928 for (ThreadID i = 0; i < Impl::MaxThreads; ++i) { 929 if (issuePipelinedIfetch[i]) { 930 pipelineIcacheAccesses(i); 931 } 932 } 933 934 // Reset the number of the instruction we've fetched. 935 numInst = 0; 936} 937 938template <class Impl> 939bool 940DefaultFetch<Impl>::checkSignalsAndUpdate(ThreadID tid) 941{ 942 // Update the per thread stall statuses. 943 if (fromDecode->decodeBlock[tid]) { 944 stalls[tid].decode = true; 945 } 946 947 if (fromDecode->decodeUnblock[tid]) { 948 assert(stalls[tid].decode); 949 assert(!fromDecode->decodeBlock[tid]); 950 stalls[tid].decode = false; 951 } 952 953 if (fromRename->renameBlock[tid]) { 954 stalls[tid].rename = true; 955 } 956 957 if (fromRename->renameUnblock[tid]) { 958 assert(stalls[tid].rename); 959 assert(!fromRename->renameBlock[tid]); 960 stalls[tid].rename = false; 961 } 962 963 if (fromIEW->iewBlock[tid]) { 964 stalls[tid].iew = true; 965 } 966 967 if (fromIEW->iewUnblock[tid]) { 968 assert(stalls[tid].iew); 969 assert(!fromIEW->iewBlock[tid]); 970 stalls[tid].iew = false; 971 } 972 973 if (fromCommit->commitBlock[tid]) { 974 stalls[tid].commit = true; 975 } 976 977 if (fromCommit->commitUnblock[tid]) { 978 assert(stalls[tid].commit); 979 assert(!fromCommit->commitBlock[tid]); 980 stalls[tid].commit = false; 981 } 982 983 // Check squash signals from commit. 984 if (fromCommit->commitInfo[tid].squash) { 985 986 DPRINTF(Fetch, "[tid:%u]: Squashing instructions due to squash " 987 "from commit.\n",tid); 988 // In any case, squash. 989 squash(fromCommit->commitInfo[tid].pc, 990 fromCommit->commitInfo[tid].doneSeqNum, 991 fromCommit->commitInfo[tid].squashInst, tid); 992 993 // If it was a branch mispredict on a control instruction, update the 994 // branch predictor with that instruction, otherwise just kill the 995 // invalid state we generated in after sequence number 996 if (fromCommit->commitInfo[tid].mispredictInst && 997 fromCommit->commitInfo[tid].mispredictInst->isControl()) { 998 branchPred->squash(fromCommit->commitInfo[tid].doneSeqNum, 999 fromCommit->commitInfo[tid].pc, 1000 fromCommit->commitInfo[tid].branchTaken, 1001 tid); 1002 } else { 1003 branchPred->squash(fromCommit->commitInfo[tid].doneSeqNum, 1004 tid); 1005 } 1006 1007 return true; 1008 } else if (fromCommit->commitInfo[tid].doneSeqNum) { 1009 // Update the branch predictor if it wasn't a squashed instruction 1010 // that was broadcasted. 1011 branchPred->update(fromCommit->commitInfo[tid].doneSeqNum, tid); 1012 } 1013 1014 // Check ROB squash signals from commit. 1015 if (fromCommit->commitInfo[tid].robSquashing) { 1016 DPRINTF(Fetch, "[tid:%u]: ROB is still squashing.\n", tid); 1017 1018 // Continue to squash. 1019 fetchStatus[tid] = Squashing; 1020 1021 return true; 1022 } 1023 1024 // Check squash signals from decode. 1025 if (fromDecode->decodeInfo[tid].squash) { 1026 DPRINTF(Fetch, "[tid:%u]: Squashing instructions due to squash " 1027 "from decode.\n",tid); 1028 1029 // Update the branch predictor. 1030 if (fromDecode->decodeInfo[tid].branchMispredict) { 1031 branchPred->squash(fromDecode->decodeInfo[tid].doneSeqNum, 1032 fromDecode->decodeInfo[tid].nextPC, 1033 fromDecode->decodeInfo[tid].branchTaken, 1034 tid); 1035 } else { 1036 branchPred->squash(fromDecode->decodeInfo[tid].doneSeqNum, 1037 tid); 1038 } 1039 1040 if (fetchStatus[tid] != Squashing) { 1041 1042 DPRINTF(Fetch, "Squashing from decode with PC = %s\n", 1043 fromDecode->decodeInfo[tid].nextPC); 1044 // Squash unless we're already squashing 1045 squashFromDecode(fromDecode->decodeInfo[tid].nextPC, 1046 fromDecode->decodeInfo[tid].squashInst, 1047 fromDecode->decodeInfo[tid].doneSeqNum, 1048 tid); 1049 1050 return true; 1051 } 1052 } 1053 1054 if (checkStall(tid) && 1055 fetchStatus[tid] != IcacheWaitResponse && 1056 fetchStatus[tid] != IcacheWaitRetry && 1057 fetchStatus[tid] != ItlbWait && 1058 fetchStatus[tid] != QuiescePending) { 1059 DPRINTF(Fetch, "[tid:%i]: Setting to blocked\n",tid); 1060 1061 fetchStatus[tid] = Blocked; 1062 1063 return true; 1064 } 1065 1066 if (fetchStatus[tid] == Blocked || 1067 fetchStatus[tid] == Squashing) { 1068 // Switch status to running if fetch isn't being told to block or 1069 // squash this cycle. 1070 DPRINTF(Fetch, "[tid:%i]: Done squashing, switching to running.\n", 1071 tid); 1072 1073 fetchStatus[tid] = Running; 1074 1075 return true; 1076 } 1077 1078 // If we've reached this point, we have not gotten any signals that 1079 // cause fetch to change its status. Fetch remains the same as before. 1080 return false; 1081} 1082 1083template<class Impl> 1084typename Impl::DynInstPtr 1085DefaultFetch<Impl>::buildInst(ThreadID tid, StaticInstPtr staticInst, 1086 StaticInstPtr curMacroop, TheISA::PCState thisPC, 1087 TheISA::PCState nextPC, bool trace) 1088{ 1089 // Get a sequence number. 1090 InstSeqNum seq = cpu->getAndIncrementInstSeq(); 1091 1092 // Create a new DynInst from the instruction fetched. 1093 DynInstPtr instruction = 1094 new DynInst(staticInst, curMacroop, thisPC, nextPC, seq, cpu); 1095 instruction->setTid(tid); 1096 1097 instruction->setASID(tid); 1098 1099 instruction->setThreadState(cpu->thread[tid]); 1100 1101 DPRINTF(Fetch, "[tid:%i]: Instruction PC %#x (%d) created " 1102 "[sn:%lli].\n", tid, thisPC.instAddr(), 1103 thisPC.microPC(), seq); 1104 1105 DPRINTF(Fetch, "[tid:%i]: Instruction is: %s\n", tid, 1106 instruction->staticInst-> 1107 disassemble(thisPC.instAddr())); 1108 1109#if TRACING_ON 1110 if (trace) { 1111 instruction->traceData = 1112 cpu->getTracer()->getInstRecord(curTick(), cpu->tcBase(tid), 1113 instruction->staticInst, thisPC, curMacroop); 1114 } 1115#else 1116 instruction->traceData = NULL; 1117#endif 1118 1119 // Add instruction to the CPU's list of instructions. 1120 instruction->setInstListIt(cpu->addInst(instruction)); 1121 1122 // Write the instruction to the first slot in the queue 1123 // that heads to decode. 1124 assert(numInst < fetchWidth); 1125 toDecode->insts[toDecode->size++] = instruction; 1126 1127 // Keep track of if we can take an interrupt at this boundary 1128 delayedCommit[tid] = instruction->isDelayedCommit(); 1129 1130 return instruction; 1131} 1132 1133template<class Impl> 1134void 1135DefaultFetch<Impl>::fetch(bool &status_change) 1136{ 1137 ////////////////////////////////////////// 1138 // Start actual fetch 1139 ////////////////////////////////////////// 1140 ThreadID tid = getFetchingThread(fetchPolicy); 1141 1142 assert(!cpu->switchedOut()); 1143 1144 if (tid == InvalidThreadID) { 1145 // Breaks looping condition in tick() 1146 threadFetched = numFetchingThreads; 1147 1148 if (numThreads == 1) { // @todo Per-thread stats 1149 profileStall(0); 1150 } 1151 1152 return; 1153 } 1154 1155 DPRINTF(Fetch, "Attempting to fetch from [tid:%i]\n", tid); 1156 1157 // The current PC. 1158 TheISA::PCState thisPC = pc[tid]; 1159 1160 Addr pcOffset = fetchOffset[tid]; 1161 Addr fetchAddr = (thisPC.instAddr() + pcOffset) & BaseCPU::PCMask; 1162 1163 bool inRom = isRomMicroPC(thisPC.microPC()); 1164 1165 // If returning from the delay of a cache miss, then update the status 1166 // to running, otherwise do the cache access. Possibly move this up 1167 // to tick() function. 1168 if (fetchStatus[tid] == IcacheAccessComplete) { 1169 DPRINTF(Fetch, "[tid:%i]: Icache miss is complete.\n", tid); 1170 1171 fetchStatus[tid] = Running; 1172 status_change = true; 1173 } else if (fetchStatus[tid] == Running) { 1174 // Align the fetch PC so its at the start of a fetch buffer segment. 1175 Addr fetchBufferBlockPC = fetchBufferAlignPC(fetchAddr); 1176 1177 // If buffer is no longer valid or fetchAddr has moved to point 1178 // to the next cache block, AND we have no remaining ucode 1179 // from a macro-op, then start fetch from icache. 1180 if (!(fetchBufferValid[tid] && fetchBufferBlockPC == fetchBufferPC[tid]) 1181 && !inRom && !macroop[tid]) { 1182 DPRINTF(Fetch, "[tid:%i]: Attempting to translate and read " 1183 "instruction, starting at PC %s.\n", tid, thisPC); 1184 1185 fetchCacheLine(fetchAddr, tid, thisPC.instAddr()); 1186 1187 if (fetchStatus[tid] == IcacheWaitResponse) 1188 ++icacheStallCycles; 1189 else if (fetchStatus[tid] == ItlbWait) 1190 ++fetchTlbCycles; 1191 else 1192 ++fetchMiscStallCycles; 1193 return; 1194 } else if ((checkInterrupt(thisPC.instAddr()) && !delayedCommit[tid])) { 1195 // Stall CPU if an interrupt is posted and we're not issuing 1196 // an delayed commit micro-op currently (delayed commit instructions 1197 // are not interruptable by interrupts, only faults) 1198 ++fetchMiscStallCycles; 1199 DPRINTF(Fetch, "[tid:%i]: Fetch is stalled!\n", tid); 1200 return; 1201 } 1202 } else { 1203 if (fetchStatus[tid] == Idle) { 1204 ++fetchIdleCycles; 1205 DPRINTF(Fetch, "[tid:%i]: Fetch is idle!\n", tid); 1206 } 1207 1208 // Status is Idle, so fetch should do nothing. 1209 return; 1210 } 1211 1212 ++fetchCycles; 1213 1214 TheISA::PCState nextPC = thisPC; 1215 1216 StaticInstPtr staticInst = NULL; 1217 StaticInstPtr curMacroop = macroop[tid]; 1218 1219 // If the read of the first instruction was successful, then grab the 1220 // instructions from the rest of the cache line and put them into the 1221 // queue heading to decode. 1222 1223 DPRINTF(Fetch, "[tid:%i]: Adding instructions to queue to " 1224 "decode.\n", tid); 1225 1226 // Need to keep track of whether or not a predicted branch 1227 // ended this fetch block. 1228 bool predictedBranch = false; 1229 1230 TheISA::MachInst *cacheInsts = 1231 reinterpret_cast<TheISA::MachInst *>(fetchBuffer[tid]); 1232 1233 const unsigned numInsts = fetchBufferSize / instSize; 1234 unsigned blkOffset = (fetchAddr - fetchBufferPC[tid]) / instSize; 1235 1236 // Loop through instruction memory from the cache. 1237 // Keep issuing while fetchWidth is available and branch is not 1238 // predicted taken 1239 while (numInst < fetchWidth && !predictedBranch) { 1240 1241 // We need to process more memory if we aren't going to get a 1242 // StaticInst from the rom, the current macroop, or what's already 1243 // in the decoder. 1244 bool needMem = !inRom && !curMacroop && 1245 !decoder[tid]->instReady(); 1246 fetchAddr = (thisPC.instAddr() + pcOffset) & BaseCPU::PCMask; 1247 Addr fetchBufferBlockPC = fetchBufferAlignPC(fetchAddr); 1248 1249 if (needMem) { 1250 // If buffer is no longer valid or fetchAddr has moved to point 1251 // to the next cache block then start fetch from icache. 1252 if (!fetchBufferValid[tid] || 1253 fetchBufferBlockPC != fetchBufferPC[tid]) 1254 break; 1255 1256 if (blkOffset >= numInsts) { 1257 // We need to process more memory, but we've run out of the 1258 // current block. 1259 break; 1260 } 1261 1262 if (ISA_HAS_DELAY_SLOT && pcOffset == 0) { 1263 // Walk past any annulled delay slot instructions. 1264 Addr pcAddr = thisPC.instAddr() & BaseCPU::PCMask; 1265 while (fetchAddr != pcAddr && blkOffset < numInsts) { 1266 blkOffset++; 1267 fetchAddr += instSize; 1268 } 1269 if (blkOffset >= numInsts) 1270 break; 1271 } 1272 1273 MachInst inst = TheISA::gtoh(cacheInsts[blkOffset]); 1274 decoder[tid]->moreBytes(thisPC, fetchAddr, inst); 1275 1276 if (decoder[tid]->needMoreBytes()) { 1277 blkOffset++; 1278 fetchAddr += instSize; 1279 pcOffset += instSize; 1280 } 1281 } 1282 1283 // Extract as many instructions and/or microops as we can from 1284 // the memory we've processed so far. 1285 do { 1286 if (!(curMacroop || inRom)) { 1287 if (decoder[tid]->instReady()) { 1288 staticInst = decoder[tid]->decode(thisPC); 1289 1290 // Increment stat of fetched instructions. 1291 ++fetchedInsts; 1292 1293 if (staticInst->isMacroop()) { 1294 curMacroop = staticInst; 1295 } else { 1296 pcOffset = 0; 1297 } 1298 } else { 1299 // We need more bytes for this instruction so blkOffset and 1300 // pcOffset will be updated 1301 break; 1302 } 1303 } 1304 // Whether we're moving to a new macroop because we're at the 1305 // end of the current one, or the branch predictor incorrectly 1306 // thinks we are... 1307 bool newMacro = false; 1308 if (curMacroop || inRom) { 1309 if (inRom) { 1310 staticInst = cpu->microcodeRom.fetchMicroop( 1311 thisPC.microPC(), curMacroop); 1312 } else { 1313 staticInst = curMacroop->fetchMicroop(thisPC.microPC()); 1314 } 1315 newMacro |= staticInst->isLastMicroop(); 1316 } 1317 1318 DynInstPtr instruction = 1319 buildInst(tid, staticInst, curMacroop, 1320 thisPC, nextPC, true); 1321 1322 ppFetch->notify(instruction); 1323 numInst++; 1324 1325#if TRACING_ON 1326 if (DTRACE(O3PipeView)) { 1327 instruction->fetchTick = curTick(); 1328 } 1329#endif 1330 1331 nextPC = thisPC; 1332 1333 // If we're branching after this instruction, quite fetching 1334 // from the same block then. 1335 predictedBranch |= thisPC.branching(); 1336 predictedBranch |= 1337 lookupAndUpdateNextPC(instruction, nextPC); 1338 if (predictedBranch) { 1339 DPRINTF(Fetch, "Branch detected with PC = %s\n", thisPC); 1340 } 1341 1342 newMacro |= thisPC.instAddr() != nextPC.instAddr(); 1343 1344 // Move to the next instruction, unless we have a branch. 1345 thisPC = nextPC; 1346 inRom = isRomMicroPC(thisPC.microPC()); 1347 1348 if (newMacro) { 1349 fetchAddr = thisPC.instAddr() & BaseCPU::PCMask; 1350 blkOffset = (fetchAddr - fetchBufferPC[tid]) / instSize; 1351 pcOffset = 0; 1352 curMacroop = NULL; 1353 } 1354 1355 if (instruction->isQuiesce()) { 1356 DPRINTF(Fetch, 1357 "Quiesce instruction encountered, halting fetch!"); 1358 fetchStatus[tid] = QuiescePending; 1359 status_change = true; 1360 break; 1361 } 1362 } while ((curMacroop || decoder[tid]->instReady()) && 1363 numInst < fetchWidth); 1364 } 1365 1366 if (predictedBranch) { 1367 DPRINTF(Fetch, "[tid:%i]: Done fetching, predicted branch " 1368 "instruction encountered.\n", tid); 1369 } else if (numInst >= fetchWidth) { 1370 DPRINTF(Fetch, "[tid:%i]: Done fetching, reached fetch bandwidth " 1371 "for this cycle.\n", tid); 1372 } else if (blkOffset >= fetchBufferSize) { 1373 DPRINTF(Fetch, "[tid:%i]: Done fetching, reached the end of the" 1374 "fetch buffer.\n", tid); 1375 } 1376 1377 macroop[tid] = curMacroop; 1378 fetchOffset[tid] = pcOffset; 1379 1380 if (numInst > 0) { 1381 wroteToTimeBuffer = true; 1382 } 1383 1384 pc[tid] = thisPC; 1385 1386 // pipeline a fetch if we're crossing a fetch buffer boundary and not in 1387 // a state that would preclude fetching 1388 fetchAddr = (thisPC.instAddr() + pcOffset) & BaseCPU::PCMask; 1389 Addr fetchBufferBlockPC = fetchBufferAlignPC(fetchAddr); 1390 issuePipelinedIfetch[tid] = fetchBufferBlockPC != fetchBufferPC[tid] && 1391 fetchStatus[tid] != IcacheWaitResponse && 1392 fetchStatus[tid] != ItlbWait && 1393 fetchStatus[tid] != IcacheWaitRetry && 1394 fetchStatus[tid] != QuiescePending && 1395 !curMacroop; 1396} 1397 1398template<class Impl> 1399void 1400DefaultFetch<Impl>::recvRetry() 1401{ 1402 if (retryPkt != NULL) { 1403 assert(cacheBlocked); 1404 assert(retryTid != InvalidThreadID); 1405 assert(fetchStatus[retryTid] == IcacheWaitRetry); 1406 1407 if (cpu->getInstPort().sendTimingReq(retryPkt)) { 1408 fetchStatus[retryTid] = IcacheWaitResponse; 1409 retryPkt = NULL; 1410 retryTid = InvalidThreadID; 1411 cacheBlocked = false; 1412 } 1413 } else { 1414 assert(retryTid == InvalidThreadID); 1415 // Access has been squashed since it was sent out. Just clear 1416 // the cache being blocked. 1417 cacheBlocked = false; 1418 } 1419} 1420 1421/////////////////////////////////////// 1422// // 1423// SMT FETCH POLICY MAINTAINED HERE // 1424// // 1425/////////////////////////////////////// 1426template<class Impl> 1427ThreadID 1428DefaultFetch<Impl>::getFetchingThread(FetchPriority &fetch_priority) 1429{ 1430 if (numThreads > 1) { 1431 switch (fetch_priority) { 1432 1433 case SingleThread: 1434 return 0; 1435 1436 case RoundRobin: 1437 return roundRobin(); 1438 1439 case IQ: 1440 return iqCount(); 1441 1442 case LSQ: 1443 return lsqCount(); 1444 1445 case Branch: 1446 return branchCount(); 1447 1448 default: 1449 return InvalidThreadID; 1450 } 1451 } else { 1452 list<ThreadID>::iterator thread = activeThreads->begin(); 1453 if (thread == activeThreads->end()) { 1454 return InvalidThreadID; 1455 } 1456 1457 ThreadID tid = *thread; 1458 1459 if (fetchStatus[tid] == Running || 1460 fetchStatus[tid] == IcacheAccessComplete || 1461 fetchStatus[tid] == Idle) { 1462 return tid; 1463 } else { 1464 return InvalidThreadID; 1465 } 1466 } 1467} 1468 1469 1470template<class Impl> 1471ThreadID 1472DefaultFetch<Impl>::roundRobin() 1473{ 1474 list<ThreadID>::iterator pri_iter = priorityList.begin(); 1475 list<ThreadID>::iterator end = priorityList.end(); 1476 1477 ThreadID high_pri; 1478 1479 while (pri_iter != end) { 1480 high_pri = *pri_iter; 1481 1482 assert(high_pri <= numThreads); 1483 1484 if (fetchStatus[high_pri] == Running || 1485 fetchStatus[high_pri] == IcacheAccessComplete || 1486 fetchStatus[high_pri] == Idle) { 1487 1488 priorityList.erase(pri_iter); 1489 priorityList.push_back(high_pri); 1490 1491 return high_pri; 1492 } 1493 1494 pri_iter++; 1495 } 1496 1497 return InvalidThreadID; 1498} 1499 1500template<class Impl> 1501ThreadID 1502DefaultFetch<Impl>::iqCount() 1503{ 1504 std::priority_queue<unsigned> PQ; 1505 std::map<unsigned, ThreadID> threadMap; 1506 1507 list<ThreadID>::iterator threads = activeThreads->begin(); 1508 list<ThreadID>::iterator end = activeThreads->end(); 1509 1510 while (threads != end) { 1511 ThreadID tid = *threads++; 1512 unsigned iqCount = fromIEW->iewInfo[tid].iqCount; 1513 1514 PQ.push(iqCount); 1515 threadMap[iqCount] = tid; 1516 } 1517 1518 while (!PQ.empty()) { 1519 ThreadID high_pri = threadMap[PQ.top()]; 1520 1521 if (fetchStatus[high_pri] == Running || 1522 fetchStatus[high_pri] == IcacheAccessComplete || 1523 fetchStatus[high_pri] == Idle) 1524 return high_pri; 1525 else 1526 PQ.pop(); 1527 1528 } 1529 1530 return InvalidThreadID; 1531} 1532 1533template<class Impl> 1534ThreadID 1535DefaultFetch<Impl>::lsqCount() 1536{ 1537 std::priority_queue<unsigned> PQ; 1538 std::map<unsigned, ThreadID> threadMap; 1539 1540 list<ThreadID>::iterator threads = activeThreads->begin(); 1541 list<ThreadID>::iterator end = activeThreads->end(); 1542 1543 while (threads != end) { 1544 ThreadID tid = *threads++; 1545 unsigned ldstqCount = fromIEW->iewInfo[tid].ldstqCount; 1546 1547 PQ.push(ldstqCount); 1548 threadMap[ldstqCount] = tid; 1549 } 1550 1551 while (!PQ.empty()) { 1552 ThreadID high_pri = threadMap[PQ.top()]; 1553 1554 if (fetchStatus[high_pri] == Running || 1555 fetchStatus[high_pri] == IcacheAccessComplete || 1556 fetchStatus[high_pri] == Idle) 1557 return high_pri; 1558 else 1559 PQ.pop(); 1560 } 1561 1562 return InvalidThreadID; 1563} 1564 1565template<class Impl> 1566ThreadID 1567DefaultFetch<Impl>::branchCount() 1568{ 1569#if 0 1570 list<ThreadID>::iterator thread = activeThreads->begin(); 1571 assert(thread != activeThreads->end()); 1572 ThreadID tid = *thread; 1573#endif 1574 1575 panic("Branch Count Fetch policy unimplemented\n"); 1576 return InvalidThreadID; 1577} 1578 1579template<class Impl> 1580void 1581DefaultFetch<Impl>::pipelineIcacheAccesses(ThreadID tid) 1582{ 1583 if (!issuePipelinedIfetch[tid]) { 1584 return; 1585 } 1586 1587 // The next PC to access. 1588 TheISA::PCState thisPC = pc[tid]; 1589 1590 if (isRomMicroPC(thisPC.microPC())) { 1591 return; 1592 } 1593 1594 Addr pcOffset = fetchOffset[tid]; 1595 Addr fetchAddr = (thisPC.instAddr() + pcOffset) & BaseCPU::PCMask; 1596 1597 // Align the fetch PC so its at the start of a fetch buffer segment. 1598 Addr fetchBufferBlockPC = fetchBufferAlignPC(fetchAddr); 1599 1600 // Unless buffer already got the block, fetch it from icache. 1601 if (!(fetchBufferValid[tid] && fetchBufferBlockPC == fetchBufferPC[tid])) { 1602 DPRINTF(Fetch, "[tid:%i]: Issuing a pipelined I-cache access, " 1603 "starting at PC %s.\n", tid, thisPC); 1604 1605 fetchCacheLine(fetchAddr, tid, thisPC.instAddr()); 1606 } 1607} 1608 1609template<class Impl> 1610void 1611DefaultFetch<Impl>::profileStall(ThreadID tid) { 1612 DPRINTF(Fetch,"There are no more threads available to fetch from.\n"); 1613 1614 // @todo Per-thread stats 1615 1616 if (stalls[tid].drain) { 1617 ++fetchPendingDrainCycles; 1618 DPRINTF(Fetch, "Fetch is waiting for a drain!\n"); 1619 } else if (activeThreads->empty()) { 1620 ++fetchNoActiveThreadStallCycles; 1621 DPRINTF(Fetch, "Fetch has no active thread!\n"); 1622 } else if (fetchStatus[tid] == Blocked) { 1623 ++fetchBlockedCycles; 1624 DPRINTF(Fetch, "[tid:%i]: Fetch is blocked!\n", tid); 1625 } else if (fetchStatus[tid] == Squashing) { 1626 ++fetchSquashCycles; 1627 DPRINTF(Fetch, "[tid:%i]: Fetch is squashing!\n", tid); 1628 } else if (fetchStatus[tid] == IcacheWaitResponse) { 1629 ++icacheStallCycles; 1630 DPRINTF(Fetch, "[tid:%i]: Fetch is waiting cache response!\n", 1631 tid); 1632 } else if (fetchStatus[tid] == ItlbWait) { 1633 ++fetchTlbCycles; 1634 DPRINTF(Fetch, "[tid:%i]: Fetch is waiting ITLB walk to " 1635 "finish!\n", tid); 1636 } else if (fetchStatus[tid] == TrapPending) { 1637 ++fetchPendingTrapStallCycles; 1638 DPRINTF(Fetch, "[tid:%i]: Fetch is waiting for a pending trap!\n", 1639 tid); 1640 } else if (fetchStatus[tid] == QuiescePending) { 1641 ++fetchPendingQuiesceStallCycles; 1642 DPRINTF(Fetch, "[tid:%i]: Fetch is waiting for a pending quiesce " 1643 "instruction!\n", tid); 1644 } else if (fetchStatus[tid] == IcacheWaitRetry) { 1645 ++fetchIcacheWaitRetryStallCycles; 1646 DPRINTF(Fetch, "[tid:%i]: Fetch is waiting for an I-cache retry!\n", 1647 tid); 1648 } else if (fetchStatus[tid] == NoGoodAddr) { 1649 DPRINTF(Fetch, "[tid:%i]: Fetch predicted non-executable address\n", 1650 tid); 1651 } else { 1652 DPRINTF(Fetch, "[tid:%i]: Unexpected fetch stall reason (Status: %i).\n", 1653 tid, fetchStatus[tid]); 1654 } 1655} 1656 1657#endif//__CPU_O3_FETCH_IMPL_HH__ 1658