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/*
* 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 <vector>
#include <list>
#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)
{ }
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;
DPRINTF(InOrderExecute, "[tid:%i] Executing [sn:%i] [PC:%s] %s.\n",
inst->readTid(), seq_num, inst->pcState(), inst->instName());
switch (exec_req->cmd)
{
case ExecuteInst:
{
if (curTick() != lastExecuteTick) {
lastExecuteTick = curTick();
}
if (inst->isMemRef()) {
panic("%s not configured to handle memory ops.\n", resName);
} else if (inst->isControl()) {
if (lastControlTick == curTick()) {
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);
}
}
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