| /* |
| * Copyright (c) 2007 MIPS Technologies, Inc. |
| * 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. |
| * |
| * Authors: Korey Sewell |
| * |
| */ |
| |
| #include "config/the_isa.hh" |
| #include "cpu/inorder/resources/fetch_seq_unit.hh" |
| #include "cpu/inorder/resource_pool.hh" |
| #include "debug/InOrderFetchSeq.hh" |
| #include "debug/InOrderStall.hh" |
| |
| using namespace std; |
| using namespace TheISA; |
| using namespace ThePipeline; |
| |
| FetchSeqUnit::FetchSeqUnit(std::string res_name, int res_id, int res_width, |
| Cycles res_latency, InOrderCPU *_cpu, |
| ThePipeline::Params *params) |
| : Resource(res_name, res_id, res_width, res_latency, _cpu), |
| instSize(sizeof(MachInst)) |
| { |
| for (ThreadID tid = 0; tid < ThePipeline::MaxThreads; tid++) { |
| pcValid[tid] = false; |
| pcBlockStage[tid] = 0; |
| |
| //@todo: Use CPU's squashSeqNum here instead of maintaining our own |
| // state |
| squashSeqNum[tid] = (InstSeqNum)-1; |
| lastSquashCycle[tid] = 0; |
| } |
| } |
| |
| FetchSeqUnit::~FetchSeqUnit() |
| { |
| delete [] resourceEvent; |
| } |
| |
| void |
| FetchSeqUnit::init() |
| { |
| resourceEvent = new FetchSeqEvent[width]; |
| |
| for (int i = 0; i < width; i++) { |
| reqs[i] = new ResourceRequest(this); |
| } |
| |
| initSlots(); |
| } |
| |
| void |
| FetchSeqUnit::execute(int slot_num) |
| { |
| ResourceRequest* fs_req = reqs[slot_num]; |
| DynInstPtr inst = fs_req->inst; |
| ThreadID tid = inst->readTid(); |
| int stage_num = fs_req->getStageNum(); |
| |
| if (inst->fault != NoFault) { |
| DPRINTF(InOrderFetchSeq, |
| "[tid:%i]: [sn:%i]: Detected %s fault @ %x. Forwarding to " |
| "next stage.\n", tid, inst->seqNum, inst->fault->name(), |
| inst->pcState()); |
| fs_req->done(); |
| return; |
| } |
| |
| switch (fs_req->cmd) |
| { |
| case AssignNextPC: |
| { |
| DPRINTF(InOrderFetchSeq, "[tid:%i]: Current PC is %s\n", tid, |
| pc[tid]); |
| |
| if (pcValid[tid]) { |
| inst->pcState(pc[tid]); |
| inst->setMemAddr(pc[tid].instAddr()); |
| |
| // Advance to next PC (typically PC + 4) |
| pc[tid].advance(); |
| |
| inst->setSeqNum(cpu->getAndIncrementInstSeq(tid)); |
| |
| DPRINTF(InOrderFetchSeq, "[tid:%i]: Assigning [sn:%i] to " |
| "PC %s\n", tid, inst->seqNum, inst->pcState()); |
| |
| fs_req->done(); |
| } else { |
| DPRINTF(InOrderStall, "STALL: [tid:%i]: NPC not valid\n", tid); |
| fs_req->done(false); |
| } |
| } |
| break; |
| |
| case UpdateTargetPC: |
| { |
| assert(!inst->isCondDelaySlot() && |
| "Not Handling Conditional Delay Slot"); |
| |
| if (inst->isControl()) { |
| if (inst->isReturn() && !inst->predTaken()) { |
| // If it's a return, then we must wait for resolved address. |
| // The Predictor will mark a return a false as "not taken" |
| // if there is no RAS entry |
| DPRINTF(InOrderFetchSeq, "[tid:%d]: Setting block signal " |
| "for stage %i.\n", |
| tid, stage_num); |
| cpu->pipelineStage[stage_num]-> |
| toPrevStages->stageBlock[stage_num][tid] = true; |
| pcValid[tid] = false; |
| pcBlockStage[tid] = stage_num; |
| } else if (inst->predTaken()) { |
| // Taken Control |
| inst->setSquashInfo(stage_num); |
| setupSquash(inst, stage_num, tid); |
| |
| DPRINTF(InOrderFetchSeq, "[tid:%i] Setting up squash to " |
| "start from stage %i, after [sn:%i].\n", |
| tid, stage_num, inst->squashSeqNum); |
| } |
| } else { |
| DPRINTF(InOrderFetchSeq, "[tid:%i]: [sn:%i]: Ignoring branch " |
| "target update since then is not a control " |
| "instruction.\n", tid, inst->seqNum); |
| } |
| |
| fs_req->done(); |
| } |
| break; |
| |
| default: |
| fatal("Unrecognized command to %s", resName); |
| } |
| } |
| |
| void |
| FetchSeqUnit::squash(DynInstPtr inst, int squash_stage, |
| InstSeqNum squash_seq_num, ThreadID tid) |
| { |
| DPRINTF(InOrderFetchSeq, "[tid:%i]: Updating due to squash from %s (%s) " |
| "stage %i.\n", tid, inst->instName(), inst->pcState(), |
| squash_stage); |
| |
| if (lastSquashCycle[tid] == curTick() && |
| squashSeqNum[tid] <= squash_seq_num) { |
| DPRINTF(InOrderFetchSeq, "[tid:%i]: Ignoring squash from stage %i, " |
| "since there is an outstanding squash that is older.\n", |
| tid, squash_stage); |
| } else { |
| squashSeqNum[tid] = squash_seq_num; |
| lastSquashCycle[tid] = curTick(); |
| |
| if (inst->staticInst) { |
| if (inst->fault != NoFault) { |
| // A Trap Caused This Fault and will update the pc state |
| // when done trapping |
| DPRINTF(InOrderFetchSeq, "[tid:%i] Blocking due to fault @ " |
| "[sn:%i].%s %s \n", tid, inst->seqNum, |
| inst->instName(), inst->pcState()); |
| pcValid[tid] = false; |
| } else { |
| TheISA::PCState nextPC; |
| assert(inst->staticInst); |
| if (inst->isControl()) { |
| nextPC = inst->readPredTarg(); |
| |
| // If we are already fetching this PC then advance to next PC |
| // ======= |
| // This should handle ISAs w/delay slots and annulled delay |
| // slots to figure out which is the next PC to fetch after |
| // a mispredict |
| DynInstPtr bdelay_inst = NULL; |
| ListIt bdelay_it; |
| if (inst->onInstList) { |
| bdelay_it = inst->getInstListIt(); |
| bdelay_it++; |
| } else { |
| InstSeqNum branch_delay_num = inst->seqNum + 1; |
| bdelay_it = cpu->findInst(branch_delay_num, tid); |
| } |
| |
| if (bdelay_it != cpu->instList[tid].end()) { |
| bdelay_inst = (*bdelay_it); |
| } |
| |
| if (bdelay_inst) { |
| if (bdelay_inst->pc.instAddr() == nextPC.instAddr()) { |
| bdelay_inst->pc = nextPC; |
| advancePC(nextPC, inst->staticInst); |
| DPRINTF(InOrderFetchSeq, "Advanced PC to %s\n", nextPC); |
| } |
| } |
| } else { |
| nextPC = inst->pcState(); |
| advancePC(nextPC, inst->staticInst); |
| } |
| |
| |
| DPRINTF(InOrderFetchSeq, "[tid:%i]: Setting PC to %s.\n", |
| tid, nextPC); |
| pc[tid] = nextPC; |
| |
| // Unblock Any Stages Waiting for this information to be updated ... |
| if (!pcValid[tid]) { |
| DPRINTF(InOrderFetchSeq, "[tid:%d]: Setting unblock signal " |
| "for stage %i.\n", |
| tid, pcBlockStage[tid]); |
| |
| // Need to use "fromNextStages" instead of "toPrevStages" |
| // because the timebuffer will have already have advanced |
| // in the tick function and this squash function will happen after |
| // the tick |
| cpu->pipelineStage[pcBlockStage[tid]]-> |
| fromNextStages->stageUnblock[pcBlockStage[tid]][tid] = true; |
| } |
| |
| pcValid[tid] = true; |
| } |
| } |
| } |
| |
| Resource::squash(inst, squash_stage, squash_seq_num, tid); |
| } |
| |
| FetchSeqUnit::FetchSeqEvent::FetchSeqEvent() |
| : ResourceEvent() |
| { } |
| |
| void |
| FetchSeqUnit::FetchSeqEvent::process() |
| { |
| FetchSeqUnit* fs_res = dynamic_cast<FetchSeqUnit*>(resource); |
| assert(fs_res); |
| |
| for (int i = 0; i < MaxThreads; i++) { |
| fs_res->pc[i] = fs_res->cpu->pcState(i); |
| DPRINTF(InOrderFetchSeq, "[tid:%i]: Setting PC: %s.\n", |
| fs_res->pc[i]); |
| |
| fs_res->pcValid[i] = true; |
| } |
| } |
| |
| |
| void |
| FetchSeqUnit::activateThread(ThreadID tid) |
| { |
| pcValid[tid] = true; |
| |
| pc[tid] = cpu->pcState(tid); |
| |
| cpu->fetchPriorityList.push_back(tid); |
| |
| DPRINTF(InOrderFetchSeq, "[tid:%i]: Reading PC: %s.\n", |
| tid, pc[tid]); |
| } |
| |
| void |
| FetchSeqUnit::deactivateThread(ThreadID tid) |
| { |
| pcValid[tid] = false; |
| pcBlockStage[tid] = 0; |
| |
| squashSeqNum[tid] = (InstSeqNum)-1; |
| lastSquashCycle[tid] = 0; |
| |
| list<ThreadID>::iterator thread_it = find(cpu->fetchPriorityList.begin(), |
| cpu->fetchPriorityList.end(), |
| tid); |
| |
| if (thread_it != cpu->fetchPriorityList.end()) |
| cpu->fetchPriorityList.erase(thread_it); |
| } |
| |
| void |
| FetchSeqUnit::suspendThread(ThreadID tid) |
| { |
| deactivateThread(tid); |
| } |
| |
| void |
| FetchSeqUnit::trap(Fault fault, ThreadID tid, DynInstPtr inst) |
| { |
| pcValid[tid] = true; |
| pc[tid] = cpu->pcState(tid); |
| DPRINTF(InOrderFetchSeq, "[tid:%i]: Trap updating to PC: " |
| "%s.\n", tid, pc[tid]); |
| } |
| |
| void |
| FetchSeqUnit::updateAfterContextSwitch(DynInstPtr inst, ThreadID tid) |
| { |
| pcValid[tid] = true; |
| |
| if (cpu->thread[tid]->lastGradIsBranch) { |
| /** This function assumes that the instruction causing the context |
| * switch was right after the branch. Thus, if it's not, then |
| * we are updating incorrectly here |
| */ |
| assert(cpu->nextInstAddr(tid) == inst->instAddr()); |
| pc[tid] = cpu->thread[tid]->lastBranchPC; |
| } else { |
| pc[tid] = inst->pcState(); |
| } |
| assert(inst->staticInst); |
| advancePC(pc[tid], inst->staticInst); |
| |
| DPRINTF(InOrderFetchSeq, "[tid:%i]: Updating PCs due to Context Switch." |
| "Assigning PC: %s.\n", tid, pc[tid]); |
| } |