/* * 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 #include #include "cpu/inorder/resources/execution_unit.hh" #include "cpu/inorder/resource_pool.hh" #include "cpu/inorder/cpu.hh" using namespace std; using namespace ThePipeline; ExecutionUnit::ExecutionUnit(string res_name, int res_id, int res_width, int res_latency, InOrderCPU *_cpu, ThePipeline::Params *params) : Resource(res_name, res_id, res_width, res_latency, _cpu), lastExecuteTick(0), lastControlTick(0), serializeTick(0) { } void ExecutionUnit::regStats() { predictedTakenIncorrect .name(name() + ".predictedTakenIncorrect") .desc("Number of Branches Incorrectly Predicted As Taken."); predictedNotTakenIncorrect .name(name() + ".predictedNotTakenIncorrect") .desc("Number of Branches Incorrectly Predicted As Not Taken)."); executions .name(name() + ".executions") .desc("Number of Instructions Executed."); predictedIncorrect .name(name() + ".mispredicted") .desc("Number of Branches Incorrectly Predicted"); predictedCorrect .name(name() + ".predicted") .desc("Number of Branches Incorrectly Predicted"); mispredictPct .name(name() + ".mispredictPct") .desc("Percentage of Incorrect Branches Predicts") .precision(6); mispredictPct = (predictedIncorrect / (predictedCorrect + predictedIncorrect)) * 100; Resource::regStats(); } void ExecutionUnit::execute(int slot_num) { ResourceRequest* exec_req = reqs[slot_num]; DynInstPtr inst = reqs[slot_num]->inst; Fault fault = NoFault; int seq_num = inst->seqNum; Tick cur_tick = curTick(); if (cur_tick == serializeTick) { DPRINTF(InOrderExecute, "Can not execute [tid:%i][sn:%i][PC:%s] %s. " "All instructions are being serialized this cycle\n", inst->readTid(), seq_num, inst->pcState(), inst->instName()); exec_req->done(false); return; } switch (exec_req->cmd) { case ExecuteInst: { DPRINTF(InOrderExecute, "[tid:%i] Executing [sn:%i] [PC:%s] %s.\n", inst->readTid(), seq_num, inst->pcState(), inst->instName()); if (cur_tick != lastExecuteTick) { lastExecuteTick = cur_tick; } assert(!inst->isMemRef()); if (inst->isSerializeAfter()) { serializeTick = cur_tick; DPRINTF(InOrderExecute, "Serializing execution after [tid:%i] " "[sn:%i] [PC:%s] %s.\n", inst->readTid(), seq_num, inst->pcState(), inst->instName()); } if (inst->isControl()) { if (lastControlTick == cur_tick) { DPRINTF(InOrderExecute, "Can not Execute More than One Control " "Inst Per Cycle. Blocking Request.\n"); exec_req->done(false); return; } lastControlTick = curTick(); // Evaluate Branch fault = inst->execute(); executions++; inst->setExecuted(); if (fault == NoFault) { // If branch is mispredicted, then signal squash // throughout all stages behind the pipeline stage // that got squashed. if (inst->mispredicted()) { int stage_num = exec_req->getStageNum(); ThreadID tid = inst->readTid(); // If it's a branch ... if (inst->isDirectCtrl()) { assert(!inst->isIndirectCtrl()); TheISA::PCState pc = inst->pcState(); TheISA::advancePC(pc, inst->staticInst); inst->setPredTarg(pc); if (inst->predTaken() && inst->isCondDelaySlot()) { inst->bdelaySeqNum = seq_num; DPRINTF(InOrderExecute, "[tid:%i]: Conditional" " branch inst [sn:%i] PC %s mis" "predicted as taken.\n", tid, seq_num, inst->pcState()); } else if (!inst->predTaken() && inst->isCondDelaySlot()) { inst->bdelaySeqNum = seq_num; inst->procDelaySlotOnMispred = true; DPRINTF(InOrderExecute, "[tid:%i]: Conditional" " branch inst [sn:%i] PC %s mis" "predicted as not taken.\n", tid, seq_num, inst->pcState()); } else { #if ISA_HAS_DELAY_SLOT inst->bdelaySeqNum = seq_num + 1; #else inst->bdelaySeqNum = seq_num; #endif DPRINTF(InOrderExecute, "[tid:%i]: " "Misprediction detected at " "[sn:%i] PC %s,\n\t squashing after " "delay slot instruction [sn:%i].\n", tid, seq_num, inst->pcState(), inst->bdelaySeqNum); DPRINTF(InOrderStall, "STALL: [tid:%i]: Branch" " misprediction at %s\n", tid, inst->pcState()); } DPRINTF(InOrderExecute, "[tid:%i] Redirecting " "fetch to %s.\n", tid, inst->readPredTarg()); } else if (inst->isIndirectCtrl()){ TheISA::PCState pc = inst->pcState(); TheISA::advancePC(pc, inst->staticInst); inst->seqNum = seq_num; inst->setPredTarg(pc); #if ISA_HAS_DELAY_SLOT inst->bdelaySeqNum = seq_num + 1; #else inst->bdelaySeqNum = seq_num; #endif DPRINTF(InOrderExecute, "[tid:%i] Redirecting" " fetch to %s.\n", tid, inst->readPredTarg()); } else { panic("Non-control instruction (%s) mispredict" "ing?!!", inst->staticInst->getName()); } DPRINTF(InOrderExecute, "[tid:%i] Squashing will " "start from stage %i.\n", tid, stage_num); cpu->pipelineStage[stage_num]->squashDueToBranch(inst, tid); inst->squashingStage = stage_num; // Squash throughout other resources cpu->resPool->scheduleEvent((InOrderCPU::CPUEventType) ResourcePool::SquashAll, inst, 0, 0, tid); if (inst->predTaken()) { predictedTakenIncorrect++; DPRINTF(InOrderExecute, "[tid:%i] [sn:%i] %s ..." "PC %s ... Mispredicts! (Taken)\n", tid, inst->seqNum, inst->staticInst->disassemble( inst->instAddr()), inst->pcState()); } else { predictedNotTakenIncorrect++; DPRINTF(InOrderExecute, "[tid:%i] [sn:%i] %s ..." "PC %s ... Mispredicts! (Not Taken)\n", tid, inst->seqNum, inst->staticInst->disassemble( inst->instAddr()), inst->pcState()); } predictedIncorrect++; } else { DPRINTF(InOrderExecute, "[tid:%i]: [sn:%i]: Prediction" "Correct.\n", inst->readTid(), seq_num); predictedCorrect++; } exec_req->done(); } else { warn("inst [sn:%i] had a %s fault", seq_num, fault->name()); } } else { // Regular ALU instruction fault = inst->execute(); executions++; if (fault == NoFault) { inst->setExecuted(); DPRINTF(InOrderExecute, "[tid:%i]: [sn:%i]: The result " "of execution is 0x%x.\n", inst->readTid(), seq_num, (inst->resultType(0) == InOrderDynInst::Float) ? inst->readFloatResult(0) : inst->readIntResult(0)); } else { DPRINTF(InOrderExecute, "[tid:%i]: [sn:%i]: had a %s " "fault.\n", inst->readTid(), seq_num, fault->name()); inst->fault = fault; } exec_req->done(); } } break; default: fatal("Unrecognized command to %s", resName); } }