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Diffstat (limited to 'cpu/o3/fetch_impl.hh')
| -rw-r--r-- | cpu/o3/fetch_impl.hh | 1221 |
1 files changed, 0 insertions, 1221 deletions
diff --git a/cpu/o3/fetch_impl.hh b/cpu/o3/fetch_impl.hh deleted file mode 100644 index a309bd49a..000000000 --- a/cpu/o3/fetch_impl.hh +++ /dev/null @@ -1,1221 +0,0 @@ -/* - * Copyright (c) 2004-2006 The Regents of The University of Michigan - * All rights reserved. - * - * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that the following conditions are - * met: redistributions of source code must retain the above copyright - * notice, this list of conditions and the following disclaimer; - * redistributions in binary form must reproduce the above copyright - * notice, this list of conditions and the following disclaimer in the - * documentation and/or other materials provided with the distribution; - * neither the name of the copyright holders nor the names of its - * contributors may be used to endorse or promote products derived from - * this software without specific prior written permission. - * - * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS - * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT - * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR - * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT - * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, - * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT - * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, - * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY - * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT - * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE - * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. - */ - -#include "arch/isa_traits.hh" -#include "cpu/exetrace.hh" -#include "cpu/o3/fetch.hh" -#include "mem/base_mem.hh" -#include "mem/mem_interface.hh" -#include "mem/mem_req.hh" -#include "sim/byteswap.hh" -#include "sim/root.hh" - -#if FULL_SYSTEM -#include "arch/tlb.hh" -#include "arch/vtophys.hh" -#include "base/remote_gdb.hh" -#include "mem/functional/memory_control.hh" -#include "mem/functional/physical.hh" -#include "sim/system.hh" -#else // !FULL_SYSTEM -#include "mem/functional/functional.hh" -#endif // FULL_SYSTEM - -#include <algorithm> - -using namespace std; - -template<class Impl> -DefaultFetch<Impl>::CacheCompletionEvent::CacheCompletionEvent(MemReqPtr &_req, - DefaultFetch *_fetch) - : Event(&mainEventQueue, Delayed_Writeback_Pri), - req(_req), - fetch(_fetch) -{ - this->setFlags(Event::AutoDelete); -} - -template<class Impl> -void -DefaultFetch<Impl>::CacheCompletionEvent::process() -{ - fetch->processCacheCompletion(req); -} - -template<class Impl> -const char * -DefaultFetch<Impl>::CacheCompletionEvent::description() -{ - return "DefaultFetch cache completion event"; -} - -template<class Impl> -DefaultFetch<Impl>::DefaultFetch(Params *params) - : icacheInterface(params->icacheInterface), - branchPred(params), - decodeToFetchDelay(params->decodeToFetchDelay), - renameToFetchDelay(params->renameToFetchDelay), - iewToFetchDelay(params->iewToFetchDelay), - commitToFetchDelay(params->commitToFetchDelay), - fetchWidth(params->fetchWidth), - numThreads(params->numberOfThreads), - numFetchingThreads(params->smtNumFetchingThreads), - interruptPending(false) -{ - if (numThreads > Impl::MaxThreads) - fatal("numThreads is not a valid value\n"); - - DPRINTF(Fetch, "Fetch constructor called\n"); - - // Set fetch stage's status to inactive. - _status = Inactive; - - string policy = params->smtFetchPolicy; - - // Convert string to lowercase - std::transform(policy.begin(), policy.end(), policy.begin(), - (int(*)(int)) tolower); - - // Figure out fetch policy - if (policy == "singlethread") { - fetchPolicy = SingleThread; - } else if (policy == "roundrobin") { - fetchPolicy = RoundRobin; - DPRINTF(Fetch, "Fetch policy set to Round Robin\n"); - } else if (policy == "branch") { - fetchPolicy = Branch; - DPRINTF(Fetch, "Fetch policy set to Branch Count\n"); - } else if (policy == "iqcount") { - fetchPolicy = IQ; - DPRINTF(Fetch, "Fetch policy set to IQ count\n"); - } else if (policy == "lsqcount") { - fetchPolicy = LSQ; - DPRINTF(Fetch, "Fetch policy set to LSQ count\n"); - } else { - fatal("Invalid Fetch Policy. Options Are: {SingleThread," - " RoundRobin,LSQcount,IQcount}\n"); - } - - // Size of cache block. - cacheBlkSize = icacheInterface ? icacheInterface->getBlockSize() : 64; - - // Create mask to get rid of offset bits. - cacheBlkMask = (cacheBlkSize - 1); - - for (int tid=0; tid < numThreads; tid++) { - - fetchStatus[tid] = Running; - - priorityList.push_back(tid); - - // Create a new memory request. - memReq[tid] = NULL; - - // Create space to store a cache line. - cacheData[tid] = new uint8_t[cacheBlkSize]; - - stalls[tid].decode = 0; - stalls[tid].rename = 0; - stalls[tid].iew = 0; - stalls[tid].commit = 0; - } - - // Get the size of an instruction. - instSize = sizeof(MachInst); -} - -template <class Impl> -std::string -DefaultFetch<Impl>::name() const -{ - return cpu->name() + ".fetch"; -} - -template <class Impl> -void -DefaultFetch<Impl>::regStats() -{ - icacheStallCycles - .name(name() + ".icacheStallCycles") - .desc("Number of cycles fetch is stalled on an Icache miss") - .prereq(icacheStallCycles); - - fetchedInsts - .name(name() + ".Insts") - .desc("Number of instructions fetch has processed") - .prereq(fetchedInsts); - - fetchedBranches - .name(name() + ".Branches") - .desc("Number of branches that fetch encountered") - .prereq(fetchedBranches); - - predictedBranches - .name(name() + ".predictedBranches") - .desc("Number of branches that fetch has predicted taken") - .prereq(predictedBranches); - - fetchCycles - .name(name() + ".Cycles") - .desc("Number of cycles fetch has run and was not squashing or" - " blocked") - .prereq(fetchCycles); - - fetchSquashCycles - .name(name() + ".SquashCycles") - .desc("Number of cycles fetch has spent squashing") - .prereq(fetchSquashCycles); - - fetchIdleCycles - .name(name() + ".IdleCycles") - .desc("Number of cycles fetch was idle") - .prereq(fetchIdleCycles); - - fetchBlockedCycles - .name(name() + ".BlockedCycles") - .desc("Number of cycles fetch has spent blocked") - .prereq(fetchBlockedCycles); - - fetchedCacheLines - .name(name() + ".CacheLines") - .desc("Number of cache lines fetched") - .prereq(fetchedCacheLines); - - fetchMiscStallCycles - .name(name() + ".MiscStallCycles") - .desc("Number of cycles fetch has spent waiting on interrupts, or " - "bad addresses, or out of MSHRs") - .prereq(fetchMiscStallCycles); - - fetchIcacheSquashes - .name(name() + ".IcacheSquashes") - .desc("Number of outstanding Icache misses that were squashed") - .prereq(fetchIcacheSquashes); - - fetchNisnDist - .init(/* base value */ 0, - /* last value */ fetchWidth, - /* bucket size */ 1) - .name(name() + ".rateDist") - .desc("Number of instructions fetched each cycle (Total)") - .flags(Stats::pdf); - - idleRate - .name(name() + ".idleRate") - .desc("Percent of cycles fetch was idle") - .prereq(idleRate); - idleRate = fetchIdleCycles * 100 / cpu->numCycles; - - branchRate - .name(name() + ".branchRate") - .desc("Number of branch fetches per cycle") - .flags(Stats::total); - branchRate = fetchedBranches / cpu->numCycles; - - fetchRate - .name(name() + ".rate") - .desc("Number of inst fetches per cycle") - .flags(Stats::total); - fetchRate = fetchedInsts / cpu->numCycles; - - branchPred.regStats(); -} - -template<class Impl> -void -DefaultFetch<Impl>::setCPU(FullCPU *cpu_ptr) -{ - DPRINTF(Fetch, "Setting the CPU pointer.\n"); - cpu = cpu_ptr; - - // Fetch needs to start fetching instructions at the very beginning, - // so it must start up in active state. - switchToActive(); -} - -template<class Impl> -void -DefaultFetch<Impl>::setTimeBuffer(TimeBuffer<TimeStruct> *time_buffer) -{ - DPRINTF(Fetch, "Setting the time buffer pointer.\n"); - timeBuffer = time_buffer; - - // Create wires to get information from proper places in time buffer. - fromDecode = timeBuffer->getWire(-decodeToFetchDelay); - fromRename = timeBuffer->getWire(-renameToFetchDelay); - fromIEW = timeBuffer->getWire(-iewToFetchDelay); - fromCommit = timeBuffer->getWire(-commitToFetchDelay); -} - -template<class Impl> -void -DefaultFetch<Impl>::setActiveThreads(list<unsigned> *at_ptr) -{ - DPRINTF(Fetch, "Setting active threads list pointer.\n"); - activeThreads = at_ptr; -} - -template<class Impl> -void -DefaultFetch<Impl>::setFetchQueue(TimeBuffer<FetchStruct> *fq_ptr) -{ - DPRINTF(Fetch, "Setting the fetch queue pointer.\n"); - fetchQueue = fq_ptr; - - // Create wire to write information to proper place in fetch queue. - toDecode = fetchQueue->getWire(0); -} - -#if 0 -template<class Impl> -void -DefaultFetch<Impl>::setPageTable(PageTable *pt_ptr) -{ - DPRINTF(Fetch, "Setting the page table pointer.\n"); -#if !FULL_SYSTEM - pTable = pt_ptr; -#endif -} -#endif - -template<class Impl> -void -DefaultFetch<Impl>::initStage() -{ - // Setup PC and nextPC with initial state. - for (int tid = 0; tid < numThreads; tid++) { - PC[tid] = cpu->readPC(tid); - nextPC[tid] = cpu->readNextPC(tid); - } -} - -template<class Impl> -void -DefaultFetch<Impl>::processCacheCompletion(MemReqPtr &req) -{ - unsigned tid = req->thread_num; - - DPRINTF(Fetch, "[tid:%u] Waking up from cache miss.\n",tid); - - // Only change the status if it's still waiting on the icache access - // to return. - if (fetchStatus[tid] != IcacheMissStall || - req != memReq[tid] || - isSwitchedOut()) { - ++fetchIcacheSquashes; - return; - } - - // Wake up the CPU (if it went to sleep and was waiting on this completion - // event). - cpu->wakeCPU(); - - DPRINTF(Activity, "[tid:%u] Activating fetch due to cache completion\n", - tid); - - switchToActive(); - - // Only switch to IcacheMissComplete if we're not stalled as well. - if (checkStall(tid)) { - fetchStatus[tid] = Blocked; - } else { - fetchStatus[tid] = IcacheMissComplete; - } - -// memcpy(cacheData[tid], memReq[tid]->data, memReq[tid]->size); - - // Reset the mem req to NULL. - memReq[tid] = NULL; -} - -template <class Impl> -void -DefaultFetch<Impl>::switchOut() -{ - // Fetch is ready to switch out at any time. - switchedOut = true; - cpu->signalSwitched(); -} - -template <class Impl> -void -DefaultFetch<Impl>::doSwitchOut() -{ - // Branch predictor needs to have its state cleared. - branchPred.switchOut(); -} - -template <class Impl> -void -DefaultFetch<Impl>::takeOverFrom() -{ - // Reset all state - for (int i = 0; i < Impl::MaxThreads; ++i) { - stalls[i].decode = 0; - stalls[i].rename = 0; - stalls[i].iew = 0; - stalls[i].commit = 0; - PC[i] = cpu->readPC(i); - nextPC[i] = cpu->readNextPC(i); - fetchStatus[i] = Running; - } - numInst = 0; - wroteToTimeBuffer = false; - _status = Inactive; - switchedOut = false; - branchPred.takeOverFrom(); -} - -template <class Impl> -void -DefaultFetch<Impl>::wakeFromQuiesce() -{ - DPRINTF(Fetch, "Waking up from quiesce\n"); - // Hopefully this is safe - // @todo: Allow other threads to wake from quiesce. - fetchStatus[0] = Running; -} - -template <class Impl> -inline void -DefaultFetch<Impl>::switchToActive() -{ - if (_status == Inactive) { - DPRINTF(Activity, "Activating stage.\n"); - - cpu->activateStage(FullCPU::FetchIdx); - - _status = Active; - } -} - -template <class Impl> -inline void -DefaultFetch<Impl>::switchToInactive() -{ - if (_status == Active) { - DPRINTF(Activity, "Deactivating stage.\n"); - - cpu->deactivateStage(FullCPU::FetchIdx); - - _status = Inactive; - } -} - -template <class Impl> -bool -DefaultFetch<Impl>::lookupAndUpdateNextPC(DynInstPtr &inst, Addr &next_PC) -{ - // Do branch prediction check here. - // A bit of a misnomer...next_PC is actually the current PC until - // this function updates it. - bool predict_taken; - - if (!inst->isControl()) { - next_PC = next_PC + instSize; - inst->setPredTarg(next_PC); - return false; - } - - predict_taken = branchPred.predict(inst, next_PC, inst->threadNumber); - - ++fetchedBranches; - - if (predict_taken) { - ++predictedBranches; - } - - return predict_taken; -} - -template <class Impl> -bool -DefaultFetch<Impl>::fetchCacheLine(Addr fetch_PC, Fault &ret_fault, unsigned tid) -{ - Fault fault = NoFault; - -#if FULL_SYSTEM - // Flag to say whether or not address is physical addr. - unsigned flags = cpu->inPalMode(fetch_PC) ? PHYSICAL : 0; -#else - unsigned flags = 0; -#endif // FULL_SYSTEM - - if (interruptPending && flags == 0 || switchedOut) { - // Hold off fetch from getting new instructions while an interrupt - // is pending. - return false; - } - - // Align the fetch PC so it's at the start of a cache block. - fetch_PC = icacheBlockAlignPC(fetch_PC); - - // Setup the memReq to do a read of the first instruction's address. - // Set the appropriate read size and flags as well. - memReq[tid] = new MemReq(); - - memReq[tid]->asid = tid; - memReq[tid]->thread_num = tid; - memReq[tid]->data = new uint8_t[64]; - memReq[tid]->xc = cpu->xcBase(tid); - memReq[tid]->cmd = Read; - memReq[tid]->reset(fetch_PC, cacheBlkSize, flags); - - // Translate the instruction request. -//#if FULL_SYSTEM - fault = cpu->translateInstReq(memReq[tid]); -//#else -// fault = pTable->translate(memReq[tid]); -//#endif - - // In the case of faults, the fetch stage may need to stall and wait - // for the ITB miss to be handled. - - // If translation was successful, attempt to read the first - // instruction. - if (fault == NoFault) { -#if FULL_SYSTEM - if (cpu->system->memctrl->badaddr(memReq[tid]->paddr) || - memReq[tid]->flags & UNCACHEABLE) { - DPRINTF(Fetch, "Fetch: Bad address %#x (hopefully on a " - "misspeculating path)!", - memReq[tid]->paddr); - ret_fault = TheISA::genMachineCheckFault(); - return false; - } -#endif - - DPRINTF(Fetch, "Fetch: Doing instruction read.\n"); - fault = cpu->mem->read(memReq[tid], cacheData[tid]); - // This read may change when the mem interface changes. - - // Now do the timing access to see whether or not the instruction - // exists within the cache. - if (icacheInterface && !icacheInterface->isBlocked()) { - DPRINTF(Fetch, "Doing cache access.\n"); - - memReq[tid]->completionEvent = NULL; - - memReq[tid]->time = curTick; - - MemAccessResult result = icacheInterface->access(memReq[tid]); - - fetchedCacheLines++; - - // If the cache missed, then schedule an event to wake - // up this stage once the cache miss completes. - // @todo: Possibly allow for longer than 1 cycle cache hits. - if (result != MA_HIT && icacheInterface->doEvents()) { - - memReq[tid]->completionEvent = - new CacheCompletionEvent(memReq[tid], this); - - lastIcacheStall[tid] = curTick; - - DPRINTF(Activity, "[tid:%i]: Activity: Stalling due to I-cache " - "miss.\n", tid); - - fetchStatus[tid] = IcacheMissStall; - } else { - DPRINTF(Fetch, "[tid:%i]: I-Cache hit. Doing Instruction " - "read.\n", tid); - -// memcpy(cacheData[tid], memReq[tid]->data, memReq[tid]->size); - } - } else { - DPRINTF(Fetch, "[tid:%i] Out of MSHRs!\n", tid); - ret_fault = NoFault; - return false; - } - } - - ret_fault = fault; - return true; -} - -template <class Impl> -inline void -DefaultFetch<Impl>::doSquash(const Addr &new_PC, unsigned tid) -{ - DPRINTF(Fetch, "[tid:%i]: Squashing, setting PC to: %#x.\n", - tid, new_PC); - - PC[tid] = new_PC; - nextPC[tid] = new_PC + instSize; - - // Clear the icache miss if it's outstanding. - if (fetchStatus[tid] == IcacheMissStall && icacheInterface) { - DPRINTF(Fetch, "[tid:%i]: Squashing outstanding Icache miss.\n", - tid); - memReq[tid] = NULL; - } - - fetchStatus[tid] = Squashing; - - ++fetchSquashCycles; -} - -template<class Impl> -void -DefaultFetch<Impl>::squashFromDecode(const Addr &new_PC, - const InstSeqNum &seq_num, - unsigned tid) -{ - DPRINTF(Fetch, "[tid:%i]: Squashing from decode.\n",tid); - - doSquash(new_PC, tid); - - // Tell the CPU to remove any instructions that are in flight between - // fetch and decode. - cpu->removeInstsUntil(seq_num, tid); -} - -template<class Impl> -bool -DefaultFetch<Impl>::checkStall(unsigned tid) const -{ - bool ret_val = false; - - if (cpu->contextSwitch) { - DPRINTF(Fetch,"[tid:%i]: Stalling for a context switch.\n",tid); - ret_val = true; - } else if (stalls[tid].decode) { - DPRINTF(Fetch,"[tid:%i]: Stall from Decode stage detected.\n",tid); - ret_val = true; - } else if (stalls[tid].rename) { - DPRINTF(Fetch,"[tid:%i]: Stall from Rename stage detected.\n",tid); - ret_val = true; - } else if (stalls[tid].iew) { - DPRINTF(Fetch,"[tid:%i]: Stall from IEW stage detected.\n",tid); - ret_val = true; - } else if (stalls[tid].commit) { - DPRINTF(Fetch,"[tid:%i]: Stall from Commit stage detected.\n",tid); - ret_val = true; - } - - return ret_val; -} - -template<class Impl> -typename DefaultFetch<Impl>::FetchStatus -DefaultFetch<Impl>::updateFetchStatus() -{ - //Check Running - list<unsigned>::iterator threads = (*activeThreads).begin(); - - while (threads != (*activeThreads).end()) { - - unsigned tid = *threads++; - - if (fetchStatus[tid] == Running || - fetchStatus[tid] == Squashing || - fetchStatus[tid] == IcacheMissComplete) { - - if (_status == Inactive) { - DPRINTF(Activity, "[tid:%i]: Activating stage.\n",tid); - - if (fetchStatus[tid] == IcacheMissComplete) { - DPRINTF(Activity, "[tid:%i]: Activating fetch due to cache" - "completion\n",tid); - } - - cpu->activateStage(FullCPU::FetchIdx); - } - - return Active; - } - } - - // Stage is switching from active to inactive, notify CPU of it. - if (_status == Active) { - DPRINTF(Activity, "Deactivating stage.\n"); - - cpu->deactivateStage(FullCPU::FetchIdx); - } - - return Inactive; -} - -template <class Impl> -void -DefaultFetch<Impl>::squash(const Addr &new_PC, unsigned tid) -{ - DPRINTF(Fetch, "[tid:%u]: Squash from commit.\n",tid); - - doSquash(new_PC, tid); - - // Tell the CPU to remove any instructions that are not in the ROB. - cpu->removeInstsNotInROB(tid); -} - -template <class Impl> -void -DefaultFetch<Impl>::tick() -{ - list<unsigned>::iterator threads = (*activeThreads).begin(); - bool status_change = false; - - wroteToTimeBuffer = false; - - while (threads != (*activeThreads).end()) { - unsigned tid = *threads++; - - // Check the signals for each thread to determine the proper status - // for each thread. - bool updated_status = checkSignalsAndUpdate(tid); - status_change = status_change || updated_status; - } - - DPRINTF(Fetch, "Running stage.\n"); - - // Reset the number of the instruction we're fetching. - numInst = 0; - - if (fromCommit->commitInfo[0].interruptPending) { - interruptPending = true; - } - if (fromCommit->commitInfo[0].clearInterrupt) { - interruptPending = false; - } - - for (threadFetched = 0; threadFetched < numFetchingThreads; - threadFetched++) { - // Fetch each of the actively fetching threads. - fetch(status_change); - } - - // Record number of instructions fetched this cycle for distribution. - fetchNisnDist.sample(numInst); - - if (status_change) { - // Change the fetch stage status if there was a status change. - _status = updateFetchStatus(); - } - - // If there was activity this cycle, inform the CPU of it. - if (wroteToTimeBuffer || cpu->contextSwitch) { - DPRINTF(Activity, "Activity this cycle.\n"); - - cpu->activityThisCycle(); - } -} - -template <class Impl> -bool -DefaultFetch<Impl>::checkSignalsAndUpdate(unsigned tid) -{ - // Update the per thread stall statuses. - if (fromDecode->decodeBlock[tid]) { - stalls[tid].decode = true; - } - - if (fromDecode->decodeUnblock[tid]) { - assert(stalls[tid].decode); - assert(!fromDecode->decodeBlock[tid]); - stalls[tid].decode = false; - } - - if (fromRename->renameBlock[tid]) { - stalls[tid].rename = true; - } - - if (fromRename->renameUnblock[tid]) { - assert(stalls[tid].rename); - assert(!fromRename->renameBlock[tid]); - stalls[tid].rename = false; - } - - if (fromIEW->iewBlock[tid]) { - stalls[tid].iew = true; - } - - if (fromIEW->iewUnblock[tid]) { - assert(stalls[tid].iew); - assert(!fromIEW->iewBlock[tid]); - stalls[tid].iew = false; - } - - if (fromCommit->commitBlock[tid]) { - stalls[tid].commit = true; - } - - if (fromCommit->commitUnblock[tid]) { - assert(stalls[tid].commit); - assert(!fromCommit->commitBlock[tid]); - stalls[tid].commit = false; - } - - // Check squash signals from commit. - if (fromCommit->commitInfo[tid].squash) { - - DPRINTF(Fetch, "[tid:%u]: Squashing instructions due to squash " - "from commit.\n",tid); - - // In any case, squash. - squash(fromCommit->commitInfo[tid].nextPC,tid); - - // Also check if there's a mispredict that happened. - if (fromCommit->commitInfo[tid].branchMispredict) { - branchPred.squash(fromCommit->commitInfo[tid].doneSeqNum, - fromCommit->commitInfo[tid].nextPC, - fromCommit->commitInfo[tid].branchTaken, - tid); - } else { - branchPred.squash(fromCommit->commitInfo[tid].doneSeqNum, - tid); - } - - return true; - } else if (fromCommit->commitInfo[tid].doneSeqNum) { - // Update the branch predictor if it wasn't a squashed instruction - // that was broadcasted. - branchPred.update(fromCommit->commitInfo[tid].doneSeqNum, tid); - } - - // Check ROB squash signals from commit. - if (fromCommit->commitInfo[tid].robSquashing) { - DPRINTF(Fetch, "[tid:%u]: ROB is still squashing Thread %u.\n", tid); - - // Continue to squash. - fetchStatus[tid] = Squashing; - - return true; - } - - // Check squash signals from decode. - if (fromDecode->decodeInfo[tid].squash) { - DPRINTF(Fetch, "[tid:%u]: Squashing instructions due to squash " - "from decode.\n",tid); - - // Update the branch predictor. - if (fromDecode->decodeInfo[tid].branchMispredict) { - branchPred.squash(fromDecode->decodeInfo[tid].doneSeqNum, - fromDecode->decodeInfo[tid].nextPC, - fromDecode->decodeInfo[tid].branchTaken, - tid); - } else { - branchPred.squash(fromDecode->decodeInfo[tid].doneSeqNum, - tid); - } - - if (fetchStatus[tid] != Squashing) { - // Squash unless we're already squashing - squashFromDecode(fromDecode->decodeInfo[tid].nextPC, - fromDecode->decodeInfo[tid].doneSeqNum, - tid); - - return true; - } - } - - if (fetchStatus[tid] != IcacheMissStall && checkStall(tid)) { - DPRINTF(Fetch, "[tid:%i]: Setting to blocked\n",tid); - - fetchStatus[tid] = Blocked; - - return true; - } - - if (fetchStatus[tid] == Blocked || - fetchStatus[tid] == Squashing) { - // Switch status to running if fetch isn't being told to block or - // squash this cycle. - DPRINTF(Fetch, "[tid:%i]: Done squashing, switching to running.\n", - tid); - - fetchStatus[tid] = Running; - - return true; - } - - // If we've reached this point, we have not gotten any signals that - // cause fetch to change its status. Fetch remains the same as before. - return false; -} - -template<class Impl> -void -DefaultFetch<Impl>::fetch(bool &status_change) -{ - ////////////////////////////////////////// - // Start actual fetch - ////////////////////////////////////////// - int tid = getFetchingThread(fetchPolicy); - - if (tid == -1) { - DPRINTF(Fetch,"There are no more threads available to fetch from.\n"); - - // Breaks looping condition in tick() - threadFetched = numFetchingThreads; - return; - } - - // The current PC. - Addr &fetch_PC = PC[tid]; - - // Fault code for memory access. - Fault fault = NoFault; - - // If returning from the delay of a cache miss, then update the status - // to running, otherwise do the cache access. Possibly move this up - // to tick() function. - if (fetchStatus[tid] == IcacheMissComplete) { - DPRINTF(Fetch, "[tid:%i]: Icache miss is complete.\n", - tid); - - fetchStatus[tid] = Running; - status_change = true; - } else if (fetchStatus[tid] == Running) { - DPRINTF(Fetch, "[tid:%i]: Attempting to translate and read " - "instruction, starting at PC %08p.\n", - tid, fetch_PC); - - bool fetch_success = fetchCacheLine(fetch_PC, fault, tid); - if (!fetch_success) { - ++fetchMiscStallCycles; - return; - } - } else { - if (fetchStatus[tid] == Idle) { - ++fetchIdleCycles; - } else if (fetchStatus[tid] == Blocked) { - ++fetchBlockedCycles; - } else if (fetchStatus[tid] == Squashing) { - ++fetchSquashCycles; - } else if (fetchStatus[tid] == IcacheMissStall) { - ++icacheStallCycles; - } - - // Status is Idle, Squashing, Blocked, or IcacheMissStall, so - // fetch should do nothing. - return; - } - - ++fetchCycles; - - // If we had a stall due to an icache miss, then return. - if (fetchStatus[tid] == IcacheMissStall) { - ++icacheStallCycles; - status_change = true; - return; - } - - Addr next_PC = fetch_PC; - InstSeqNum inst_seq; - MachInst inst; - ExtMachInst ext_inst; - // @todo: Fix this hack. - unsigned offset = (fetch_PC & cacheBlkMask) & ~3; - - if (fault == NoFault) { - // If the read of the first instruction was successful, then grab the - // instructions from the rest of the cache line and put them into the - // queue heading to decode. - - DPRINTF(Fetch, "[tid:%i]: Adding instructions to queue to " - "decode.\n",tid); - - // Need to keep track of whether or not a predicted branch - // ended this fetch block. - bool predicted_branch = false; - - for (; - offset < cacheBlkSize && - numInst < fetchWidth && - !predicted_branch; - ++numInst) { - - // Get a sequence number. - inst_seq = cpu->getAndIncrementInstSeq(); - - // Make sure this is a valid index. - assert(offset <= cacheBlkSize - instSize); - - // Get the instruction from the array of the cache line. - inst = gtoh(*reinterpret_cast<MachInst *> - (&cacheData[tid][offset])); - - ext_inst = TheISA::makeExtMI(inst, fetch_PC); - - // Create a new DynInst from the instruction fetched. - DynInstPtr instruction = new DynInst(ext_inst, fetch_PC, - next_PC, - inst_seq, cpu); - instruction->setThread(tid); - - instruction->setASID(tid); - - instruction->setState(cpu->thread[tid]); - - DPRINTF(Fetch, "[tid:%i]: Instruction PC %#x created " - "[sn:%lli]\n", - tid, instruction->readPC(), inst_seq); - - DPRINTF(Fetch, "[tid:%i]: Instruction is: %s\n", - tid, instruction->staticInst->disassemble(fetch_PC)); - - instruction->traceData = - Trace::getInstRecord(curTick, cpu->xcBase(tid), cpu, - instruction->staticInst, - instruction->readPC(),tid); - - predicted_branch = lookupAndUpdateNextPC(instruction, next_PC); - - // Add instruction to the CPU's list of instructions. - instruction->setInstListIt(cpu->addInst(instruction)); - - // Write the instruction to the first slot in the queue - // that heads to decode. - toDecode->insts[numInst] = instruction; - - toDecode->size++; - - // Increment stat of fetched instructions. - ++fetchedInsts; - - // Move to the next instruction, unless we have a branch. - fetch_PC = next_PC; - - if (instruction->isQuiesce()) { - warn("%lli: Quiesce instruction encountered, halting fetch!", - curTick); - fetchStatus[tid] = QuiescePending; - ++numInst; - status_change = true; - break; - } - - offset+= instSize; - } - } - - if (numInst > 0) { - wroteToTimeBuffer = true; - } - - // Now that fetching is completed, update the PC to signify what the next - // cycle will be. - if (fault == NoFault) { - DPRINTF(Fetch, "[tid:%i]: Setting PC to %08p.\n",tid, next_PC); - - PC[tid] = next_PC; - nextPC[tid] = next_PC + instSize; - } else { - // We shouldn't be in an icache miss and also have a fault (an ITB - // miss) - if (fetchStatus[tid] == IcacheMissStall) { - panic("Fetch should have exited prior to this!"); - } - - // Send the fault to commit. This thread will not do anything - // until commit handles the fault. The only other way it can - // wake up is if a squash comes along and changes the PC. -#if FULL_SYSTEM - assert(numInst != fetchWidth); - // Get a sequence number. - inst_seq = cpu->getAndIncrementInstSeq(); - // We will use a nop in order to carry the fault. - ext_inst = TheISA::NoopMachInst; - - // Create a new DynInst from the dummy nop. - DynInstPtr instruction = new DynInst(ext_inst, fetch_PC, - next_PC, - inst_seq, cpu); - instruction->setPredTarg(next_PC + instSize); - instruction->setThread(tid); - - instruction->setASID(tid); - - instruction->setState(cpu->thread[tid]); - - instruction->traceData = NULL; - - instruction->setInstListIt(cpu->addInst(instruction)); - - instruction->fault = fault; - - toDecode->insts[numInst] = instruction; - toDecode->size++; - - DPRINTF(Fetch, "[tid:%i]: Blocked, need to handle the trap.\n",tid); - - fetchStatus[tid] = TrapPending; - status_change = true; - - warn("%lli fault (%d) detected @ PC %08p", curTick, fault, PC[tid]); -#else // !FULL_SYSTEM - fatal("fault (%d) detected @ PC %08p", fault, PC[tid]); -#endif // FULL_SYSTEM - } -} - - -/////////////////////////////////////// -// // -// SMT FETCH POLICY MAINTAINED HERE // -// // -/////////////////////////////////////// -template<class Impl> -int -DefaultFetch<Impl>::getFetchingThread(FetchPriority &fetch_priority) -{ - if (numThreads > 1) { - switch (fetch_priority) { - - case SingleThread: - return 0; - - case RoundRobin: - return roundRobin(); - - case IQ: - return iqCount(); - - case LSQ: - return lsqCount(); - - case Branch: - return branchCount(); - - default: - return -1; - } - } else { - int tid = *((*activeThreads).begin()); - - if (fetchStatus[tid] == Running || - fetchStatus[tid] == IcacheMissComplete || - fetchStatus[tid] == Idle) { - return tid; - } else { - return -1; - } - } - -} - - -template<class Impl> -int -DefaultFetch<Impl>::roundRobin() -{ - list<unsigned>::iterator pri_iter = priorityList.begin(); - list<unsigned>::iterator end = priorityList.end(); - - int high_pri; - - while (pri_iter != end) { - high_pri = *pri_iter; - - assert(high_pri <= numThreads); - - if (fetchStatus[high_pri] == Running || - fetchStatus[high_pri] == IcacheMissComplete || - fetchStatus[high_pri] == Idle) { - - priorityList.erase(pri_iter); - priorityList.push_back(high_pri); - - return high_pri; - } - - pri_iter++; - } - - return -1; -} - -template<class Impl> -int -DefaultFetch<Impl>::iqCount() -{ - priority_queue<unsigned> PQ; - - list<unsigned>::iterator threads = (*activeThreads).begin(); - - while (threads != (*activeThreads).end()) { - unsigned tid = *threads++; - - PQ.push(fromIEW->iewInfo[tid].iqCount); - } - - while (!PQ.empty()) { - - unsigned high_pri = PQ.top(); - - if (fetchStatus[high_pri] == Running || - fetchStatus[high_pri] == IcacheMissComplete || - fetchStatus[high_pri] == Idle) - return high_pri; - else - PQ.pop(); - - } - - return -1; -} - -template<class Impl> -int -DefaultFetch<Impl>::lsqCount() -{ - priority_queue<unsigned> PQ; - - - list<unsigned>::iterator threads = (*activeThreads).begin(); - - while (threads != (*activeThreads).end()) { - unsigned tid = *threads++; - - PQ.push(fromIEW->iewInfo[tid].ldstqCount); - } - - while (!PQ.empty()) { - - unsigned high_pri = PQ.top(); - - if (fetchStatus[high_pri] == Running || - fetchStatus[high_pri] == IcacheMissComplete || - fetchStatus[high_pri] == Idle) - return high_pri; - else - PQ.pop(); - - } - - return -1; -} - -template<class Impl> -int -DefaultFetch<Impl>::branchCount() -{ - list<unsigned>::iterator threads = (*activeThreads).begin(); - - return *threads; -} |