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|
/*
* Copyright (c) 2013 - 2015 ARM Limited
* All rights reserved
*
* The license below extends only to copyright in the software and shall
* not be construed as granting a license to any other intellectual
* property including but not limited to intellectual property relating
* to a hardware implementation of the functionality of the software
* licensed hereunder. You may use the software subject to the license
* terms below provided that you ensure that this notice is replicated
* unmodified and in its entirety in all distributions of the software,
* modified or unmodified, in source code or in binary form.
*
* 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: Radhika Jagtap
* Andreas Hansson
* Thomas Grass
*/
#include "cpu/o3/probe/elastic_trace.hh"
#include "base/callback.hh"
#include "base/output.hh"
#include "base/trace.hh"
#include "cpu/reg_class.hh"
#include "debug/ElasticTrace.hh"
#include "mem/packet.hh"
ElasticTrace::ElasticTrace(const ElasticTraceParams* params)
: ProbeListenerObject(params),
regEtraceListenersEvent([this]{ regEtraceListeners(); }, name()),
firstWin(true),
lastClearedSeqNum(0),
depWindowSize(params->depWindowSize),
dataTraceStream(nullptr),
instTraceStream(nullptr),
startTraceInst(params->startTraceInst),
allProbesReg(false),
traceVirtAddr(params->traceVirtAddr)
{
cpu = dynamic_cast<FullO3CPU<O3CPUImpl>*>(params->manager);
fatal_if(!cpu, "Manager of %s is not of type O3CPU and thus does not "\
"support dependency tracing.\n", name());
fatal_if(depWindowSize == 0, "depWindowSize parameter must be non-zero. "\
"Recommended size is 3x ROB size in the O3CPU.\n");
fatal_if(cpu->numThreads > 1, "numThreads = %i, %s supports tracing for"\
"single-threaded workload only", cpu->numThreads, name());
// Initialize the protobuf output stream
fatal_if(params->instFetchTraceFile == "", "Assign instruction fetch "\
"trace file path to instFetchTraceFile");
fatal_if(params->dataDepTraceFile == "", "Assign data dependency "\
"trace file path to dataDepTraceFile");
std::string filename = simout.resolve(name() + "." +
params->instFetchTraceFile);
instTraceStream = new ProtoOutputStream(filename);
filename = simout.resolve(name() + "." + params->dataDepTraceFile);
dataTraceStream = new ProtoOutputStream(filename);
// Create a protobuf message for the header and write it to the stream
ProtoMessage::PacketHeader inst_pkt_header;
inst_pkt_header.set_obj_id(name());
inst_pkt_header.set_tick_freq(SimClock::Frequency);
instTraceStream->write(inst_pkt_header);
// Create a protobuf message for the header and write it to
// the stream
ProtoMessage::InstDepRecordHeader data_rec_header;
data_rec_header.set_obj_id(name());
data_rec_header.set_tick_freq(SimClock::Frequency);
data_rec_header.set_window_size(depWindowSize);
dataTraceStream->write(data_rec_header);
// Register a callback to flush trace records and close the output streams.
Callback* cb = new MakeCallback<ElasticTrace,
&ElasticTrace::flushTraces>(this);
registerExitCallback(cb);
}
void
ElasticTrace::regProbeListeners()
{
inform("@%llu: regProbeListeners() called, startTraceInst = %llu",
curTick(), startTraceInst);
if (startTraceInst == 0) {
// If we want to start tracing from the start of the simulation,
// register all elastic trace probes now.
regEtraceListeners();
} else {
// Schedule an event to register all elastic trace probes when
// specified no. of instructions are committed.
cpu->getContext(0)->scheduleInstCountEvent(
®EtraceListenersEvent, startTraceInst);
}
}
void
ElasticTrace::regEtraceListeners()
{
assert(!allProbesReg);
inform("@%llu: No. of instructions committed = %llu, registering elastic"
" probe listeners", curTick(), cpu->numSimulatedInsts());
// Create new listeners: provide method to be called upon a notify() for
// each probe point.
listeners.push_back(new ProbeListenerArg<ElasticTrace, RequestPtr>(this,
"FetchRequest", &ElasticTrace::fetchReqTrace));
listeners.push_back(new ProbeListenerArg<ElasticTrace,
DynInstConstPtr>(this, "Execute",
&ElasticTrace::recordExecTick));
listeners.push_back(new ProbeListenerArg<ElasticTrace,
DynInstConstPtr>(this, "ToCommit",
&ElasticTrace::recordToCommTick));
listeners.push_back(new ProbeListenerArg<ElasticTrace,
DynInstConstPtr>(this, "Rename",
&ElasticTrace::updateRegDep));
listeners.push_back(new ProbeListenerArg<ElasticTrace, SeqNumRegPair>(this,
"SquashInRename", &ElasticTrace::removeRegDepMapEntry));
listeners.push_back(new ProbeListenerArg<ElasticTrace,
DynInstConstPtr>(this, "Squash",
&ElasticTrace::addSquashedInst));
listeners.push_back(new ProbeListenerArg<ElasticTrace,
DynInstConstPtr>(this, "Commit",
&ElasticTrace::addCommittedInst));
allProbesReg = true;
}
void
ElasticTrace::fetchReqTrace(const RequestPtr &req)
{
DPRINTFR(ElasticTrace, "Fetch Req %i,(%lli,%lli,%lli),%i,%i,%lli\n",
(MemCmd::ReadReq),
req->getPC(), req->getVaddr(), req->getPaddr(),
req->getFlags(), req->getSize(), curTick());
// Create a protobuf message including the request fields necessary to
// recreate the request in the TraceCPU.
ProtoMessage::Packet inst_fetch_pkt;
inst_fetch_pkt.set_tick(curTick());
inst_fetch_pkt.set_cmd(MemCmd::ReadReq);
inst_fetch_pkt.set_pc(req->getPC());
inst_fetch_pkt.set_flags(req->getFlags());
inst_fetch_pkt.set_addr(req->getPaddr());
inst_fetch_pkt.set_size(req->getSize());
// Write the message to the stream.
instTraceStream->write(inst_fetch_pkt);
}
void
ElasticTrace::recordExecTick(const DynInstConstPtr& dyn_inst)
{
// In a corner case, a retired instruction is propagated backward to the
// IEW instruction queue to handle some side-channel information. But we
// must not process an instruction again. So we test the sequence number
// against the lastClearedSeqNum and skip adding the instruction for such
// corner cases.
if (dyn_inst->seqNum <= lastClearedSeqNum) {
DPRINTFR(ElasticTrace, "[sn:%lli] Ignoring in execute as instruction \
has already retired (mostly squashed)", dyn_inst->seqNum);
// Do nothing as program has proceeded and this inst has been
// propagated backwards to handle something.
return;
}
DPRINTFR(ElasticTrace, "[sn:%lli] Execute Tick = %i\n", dyn_inst->seqNum,
curTick());
// Either the execution info object will already exist if this
// instruction had a register dependency recorded in the rename probe
// listener before entering execute stage or it will not exist and will
// need to be created here.
InstExecInfo* exec_info_ptr;
auto itr_exec_info = tempStore.find(dyn_inst->seqNum);
if (itr_exec_info != tempStore.end()) {
exec_info_ptr = itr_exec_info->second;
} else {
exec_info_ptr = new InstExecInfo;
tempStore[dyn_inst->seqNum] = exec_info_ptr;
}
exec_info_ptr->executeTick = curTick();
maxTempStoreSize = std::max(tempStore.size(),
(std::size_t)maxTempStoreSize.value());
}
void
ElasticTrace::recordToCommTick(const DynInstConstPtr& dyn_inst)
{
// If tracing has just been enabled then the instruction at this stage of
// execution is far enough that we cannot gather info about its past like
// the tick it started execution. Simply return until we see an instruction
// that is found in the tempStore.
auto itr_exec_info = tempStore.find(dyn_inst->seqNum);
if (itr_exec_info == tempStore.end()) {
DPRINTFR(ElasticTrace, "recordToCommTick: [sn:%lli] Not in temp store,"
" skipping.\n", dyn_inst->seqNum);
return;
}
DPRINTFR(ElasticTrace, "[sn:%lli] To Commit Tick = %i\n", dyn_inst->seqNum,
curTick());
InstExecInfo* exec_info_ptr = itr_exec_info->second;
exec_info_ptr->toCommitTick = curTick();
}
void
ElasticTrace::updateRegDep(const DynInstConstPtr& dyn_inst)
{
// Get the sequence number of the instruction
InstSeqNum seq_num = dyn_inst->seqNum;
assert(dyn_inst->seqNum > lastClearedSeqNum);
// Since this is the first probe activated in the pipeline, create
// a new execution info object to track this instruction as it
// progresses through the pipeline.
InstExecInfo* exec_info_ptr = new InstExecInfo;
tempStore[seq_num] = exec_info_ptr;
// Loop through the source registers and look up the dependency map. If
// the source register entry is found in the dependency map, add a
// dependency on the last writer.
int8_t max_regs = dyn_inst->numSrcRegs();
for (int src_idx = 0; src_idx < max_regs; src_idx++) {
const RegId& src_reg = dyn_inst->srcRegIdx(src_idx);
if (!src_reg.isMiscReg() &&
!src_reg.isZeroReg()) {
// Get the physical register index of the i'th source register.
PhysRegIdPtr phys_src_reg = dyn_inst->renamedSrcRegIdx(src_idx);
DPRINTFR(ElasticTrace, "[sn:%lli] Check map for src reg"
" %i (%s)\n", seq_num,
phys_src_reg->flatIndex(), phys_src_reg->className());
auto itr_writer = physRegDepMap.find(phys_src_reg->flatIndex());
if (itr_writer != physRegDepMap.end()) {
InstSeqNum last_writer = itr_writer->second;
// Additionally the dependency distance is kept less than the
// window size parameter to limit the memory allocation to
// nodes in the graph. If the window were tending to infinite
// we would have to load a large number of node objects during
// replay.
if (seq_num - last_writer < depWindowSize) {
// Record a physical register dependency.
exec_info_ptr->physRegDepSet.insert(last_writer);
}
}
}
}
// Loop through the destination registers of this instruction and update
// the physical register dependency map for last writers to registers.
max_regs = dyn_inst->numDestRegs();
for (int dest_idx = 0; dest_idx < max_regs; dest_idx++) {
// For data dependency tracking the register must be an int, float or
// CC register and not a Misc register.
const RegId& dest_reg = dyn_inst->destRegIdx(dest_idx);
if (!dest_reg.isMiscReg() &&
!dest_reg.isZeroReg()) {
// Get the physical register index of the i'th destination
// register.
PhysRegIdPtr phys_dest_reg = dyn_inst->renamedDestRegIdx(dest_idx);
DPRINTFR(ElasticTrace, "[sn:%lli] Update map for dest reg"
" %i (%s)\n", seq_num, phys_dest_reg->flatIndex(),
dest_reg.className());
physRegDepMap[phys_dest_reg->flatIndex()] = seq_num;
}
}
maxPhysRegDepMapSize = std::max(physRegDepMap.size(),
(std::size_t)maxPhysRegDepMapSize.value());
}
void
ElasticTrace::removeRegDepMapEntry(const SeqNumRegPair &inst_reg_pair)
{
DPRINTFR(ElasticTrace, "Remove Map entry for Reg %i\n",
inst_reg_pair.second);
auto itr_regdep_map = physRegDepMap.find(inst_reg_pair.second);
if (itr_regdep_map != physRegDepMap.end())
physRegDepMap.erase(itr_regdep_map);
}
void
ElasticTrace::addSquashedInst(const DynInstConstPtr& head_inst)
{
// If the squashed instruction was squashed before being processed by
// execute stage then it will not be in the temporary store. In this case
// do nothing and return.
auto itr_exec_info = tempStore.find(head_inst->seqNum);
if (itr_exec_info == tempStore.end())
return;
// If there is a squashed load for which a read request was
// sent before it got squashed then add it to the trace.
DPRINTFR(ElasticTrace, "Attempt to add squashed inst [sn:%lli]\n",
head_inst->seqNum);
// Get pointer to the execution info object corresponding to the inst.
InstExecInfo* exec_info_ptr = itr_exec_info->second;
if (head_inst->isLoad() && exec_info_ptr->executeTick != MaxTick &&
exec_info_ptr->toCommitTick != MaxTick &&
head_inst->hasRequest() &&
head_inst->getFault() == NoFault) {
// Add record to depTrace with commit parameter as false.
addDepTraceRecord(head_inst, exec_info_ptr, false);
}
// As the information contained is no longer needed, remove the execution
// info object from the temporary store.
clearTempStoreUntil(head_inst);
}
void
ElasticTrace::addCommittedInst(const DynInstConstPtr& head_inst)
{
DPRINTFR(ElasticTrace, "Attempt to add committed inst [sn:%lli]\n",
head_inst->seqNum);
// Add the instruction to the depTrace.
if (!head_inst->isNop()) {
// If tracing has just been enabled then the instruction at this stage
// of execution is far enough that we cannot gather info about its past
// like the tick it started execution. Simply return until we see an
// instruction that is found in the tempStore.
auto itr_temp_store = tempStore.find(head_inst->seqNum);
if (itr_temp_store == tempStore.end()) {
DPRINTFR(ElasticTrace, "addCommittedInst: [sn:%lli] Not in temp "
"store, skipping.\n", head_inst->seqNum);
return;
}
// Get pointer to the execution info object corresponding to the inst.
InstExecInfo* exec_info_ptr = itr_temp_store->second;
assert(exec_info_ptr->executeTick != MaxTick);
assert(exec_info_ptr->toCommitTick != MaxTick);
// Check if the instruction had a fault, if it predicated false and
// thus previous register values were restored or if it was a
// load/store that did not have a request (e.g. when the size of the
// request is zero). In all these cases the instruction is set as
// executed and is picked up by the commit probe listener. But a
// request is not issued and registers are not written. So practically,
// skipping these should not hurt as execution would not stall on them.
// Alternatively, these could be included merely as a compute node in
// the graph. Removing these for now. If correlation accuracy needs to
// be improved in future these can be turned into comp nodes at the
// cost of bigger traces.
if (head_inst->getFault() != NoFault) {
DPRINTF(ElasticTrace, "%s [sn:%lli] has faulted so "
"skip adding it to the trace\n",
(head_inst->isMemRef() ? "Load/store" : "Comp inst."),
head_inst->seqNum);
} else if (head_inst->isMemRef() && !head_inst->hasRequest()) {
DPRINTF(ElasticTrace, "Load/store [sn:%lli] has no request so "
"skip adding it to the trace\n", head_inst->seqNum);
} else if (!head_inst->readPredicate()) {
DPRINTF(ElasticTrace, "%s [sn:%lli] is predicated false so "
"skip adding it to the trace\n",
(head_inst->isMemRef() ? "Load/store" : "Comp inst."),
head_inst->seqNum);
} else {
// Add record to depTrace with commit parameter as true.
addDepTraceRecord(head_inst, exec_info_ptr, true);
}
}
// As the information contained is no longer needed, remove the execution
// info object from the temporary store.
clearTempStoreUntil(head_inst);
}
void
ElasticTrace::addDepTraceRecord(const DynInstConstPtr& head_inst,
InstExecInfo* exec_info_ptr, bool commit)
{
// Create a record to assign dynamic intruction related fields.
TraceInfo* new_record = new TraceInfo;
// Add to map for sequence number look up to retrieve the TraceInfo pointer
traceInfoMap[head_inst->seqNum] = new_record;
// Assign fields from the instruction
new_record->instNum = head_inst->seqNum;
new_record->commit = commit;
new_record->type = head_inst->isLoad() ? Record::LOAD :
(head_inst->isStore() ? Record::STORE :
Record::COMP);
// Assign fields for creating a request in case of a load/store
new_record->reqFlags = head_inst->memReqFlags;
new_record->virtAddr = head_inst->effAddr;
new_record->asid = head_inst->asid;
new_record->physAddr = head_inst->physEffAddr;
// Currently the tracing does not support split requests.
new_record->size = head_inst->effSize;
new_record->pc = head_inst->instAddr();
// Assign the timing information stored in the execution info object
new_record->executeTick = exec_info_ptr->executeTick;
new_record->toCommitTick = exec_info_ptr->toCommitTick;
new_record->commitTick = curTick();
// Assign initial values for number of dependents and computational delay
new_record->numDepts = 0;
new_record->compDelay = -1;
// The physical register dependency set of the first instruction is
// empty. Since there are no records in the depTrace at this point, the
// case of adding an ROB dependency by using a reverse iterator is not
// applicable. Thus, populate the fields of the record corresponding to the
// first instruction and return.
if (depTrace.empty()) {
// Store the record in depTrace.
depTrace.push_back(new_record);
DPRINTF(ElasticTrace, "Added first inst record %lli to DepTrace.\n",
new_record->instNum);
return;
}
// Clear register dependencies for squashed loads as they may be dependent
// on squashed instructions and we do not add those to the trace.
if (head_inst->isLoad() && !commit) {
(exec_info_ptr->physRegDepSet).clear();
}
// Assign the register dependencies stored in the execution info object
std::set<InstSeqNum>::const_iterator dep_set_it;
for (dep_set_it = (exec_info_ptr->physRegDepSet).begin();
dep_set_it != (exec_info_ptr->physRegDepSet).end();
++dep_set_it) {
auto trace_info_itr = traceInfoMap.find(*dep_set_it);
if (trace_info_itr != traceInfoMap.end()) {
// The register dependency is valid. Assign it and calculate
// computational delay
new_record->physRegDepList.push_back(*dep_set_it);
DPRINTF(ElasticTrace, "Inst %lli has register dependency on "
"%lli\n", new_record->instNum, *dep_set_it);
TraceInfo* reg_dep = trace_info_itr->second;
reg_dep->numDepts++;
compDelayPhysRegDep(reg_dep, new_record);
++numRegDep;
} else {
// The instruction that this has a register dependency on was
// not added to the trace because of one of the following
// 1. it was an instruction that had a fault
// 2. it was an instruction that was predicated false and
// previous register values were restored
// 3. it was load/store that did not have a request (e.g. when
// the size of the request is zero but this may not be a fault)
// In all these cases the instruction is set as executed and is
// picked up by the commit probe listener. But a request is not
// issued and registers are not written to in these cases.
DPRINTF(ElasticTrace, "Inst %lli has register dependency on "
"%lli is skipped\n",new_record->instNum, *dep_set_it);
}
}
// Check for and assign an ROB dependency in addition to register
// dependency before adding the record to the trace.
// As stores have to commit in order a store is dependent on the last
// committed load/store. This is recorded in the ROB dependency.
if (head_inst->isStore()) {
// Look up store-after-store order dependency
updateCommitOrderDep(new_record, false);
// Look up store-after-load order dependency
updateCommitOrderDep(new_record, true);
}
// In case a node is dependency-free or its dependency got discarded
// because it was outside the window, it is marked ready in the ROB at the
// time of issue. A request is sent as soon as possible. To model this, a
// node is assigned an issue order dependency on a committed instruction
// that completed earlier than it. This is done to avoid the problem of
// determining the issue times of such dependency-free nodes during replay
// which could lead to too much parallelism, thinking conservatively.
if (new_record->robDepList.empty() && new_record->physRegDepList.empty()) {
updateIssueOrderDep(new_record);
}
// Store the record in depTrace.
depTrace.push_back(new_record);
DPRINTF(ElasticTrace, "Added %s inst %lli to DepTrace.\n",
(commit ? "committed" : "squashed"), new_record->instNum);
// To process the number of records specified by depWindowSize in the
// forward direction, the depTrace must have twice as many records
// to check for dependencies.
if (depTrace.size() == 2 * depWindowSize) {
DPRINTF(ElasticTrace, "Writing out trace...\n");
// Write out the records which have been processed to the trace
// and remove them from the depTrace.
writeDepTrace(depWindowSize);
// After the first window, writeDepTrace() must check for valid
// compDelay.
firstWin = false;
}
}
void
ElasticTrace::updateCommitOrderDep(TraceInfo* new_record,
bool find_load_not_store)
{
assert(new_record->isStore());
// Iterate in reverse direction to search for the last committed
// load/store that completed earlier than the new record
depTraceRevItr from_itr(depTrace.end());
depTraceRevItr until_itr(depTrace.begin());
TraceInfo* past_record = *from_itr;
uint32_t num_go_back = 0;
// The execution time of this store is when it is sent, that is committed
Tick execute_tick = curTick();
// Search for store-after-load or store-after-store order dependency
while (num_go_back < depWindowSize && from_itr != until_itr) {
if (find_load_not_store) {
// Check if previous inst is a load completed earlier by comparing
// with execute tick
if (hasLoadCompleted(past_record, execute_tick)) {
// Assign rob dependency and calculate the computational delay
assignRobDep(past_record, new_record);
++numOrderDepStores;
return;
}
} else {
// Check if previous inst is a store sent earlier by comparing with
// execute tick
if (hasStoreCommitted(past_record, execute_tick)) {
// Assign rob dependency and calculate the computational delay
assignRobDep(past_record, new_record);
++numOrderDepStores;
return;
}
}
++from_itr;
past_record = *from_itr;
++num_go_back;
}
}
void
ElasticTrace::updateIssueOrderDep(TraceInfo* new_record)
{
// Interate in reverse direction to search for the last committed
// record that completed earlier than the new record
depTraceRevItr from_itr(depTrace.end());
depTraceRevItr until_itr(depTrace.begin());
TraceInfo* past_record = *from_itr;
uint32_t num_go_back = 0;
Tick execute_tick = 0;
if (new_record->isLoad()) {
// The execution time of a load is when a request is sent
execute_tick = new_record->executeTick;
++numIssueOrderDepLoads;
} else if (new_record->isStore()) {
// The execution time of a store is when it is sent, i.e. committed
execute_tick = curTick();
++numIssueOrderDepStores;
} else {
// The execution time of a non load/store is when it completes
execute_tick = new_record->toCommitTick;
++numIssueOrderDepOther;
}
// We search if this record has an issue order dependency on a past record.
// Once we find it, we update both the new record and the record it depends
// on and return.
while (num_go_back < depWindowSize && from_itr != until_itr) {
// Check if a previous inst is a load sent earlier, or a store sent
// earlier, or a comp inst completed earlier by comparing with execute
// tick
if (hasLoadBeenSent(past_record, execute_tick) ||
hasStoreCommitted(past_record, execute_tick) ||
hasCompCompleted(past_record, execute_tick)) {
// Assign rob dependency and calculate the computational delay
assignRobDep(past_record, new_record);
return;
}
++from_itr;
past_record = *from_itr;
++num_go_back;
}
}
void
ElasticTrace::assignRobDep(TraceInfo* past_record, TraceInfo* new_record) {
DPRINTF(ElasticTrace, "%s %lli has ROB dependency on %lli\n",
new_record->typeToStr(), new_record->instNum,
past_record->instNum);
// Add dependency on past record
new_record->robDepList.push_back(past_record->instNum);
// Update new_record's compute delay with respect to the past record
compDelayRob(past_record, new_record);
// Increment number of dependents of the past record
++(past_record->numDepts);
// Update stat to log max number of dependents
maxNumDependents = std::max(past_record->numDepts,
(uint32_t)maxNumDependents.value());
}
bool
ElasticTrace::hasStoreCommitted(TraceInfo* past_record,
Tick execute_tick) const
{
return (past_record->isStore() && past_record->commitTick <= execute_tick);
}
bool
ElasticTrace::hasLoadCompleted(TraceInfo* past_record,
Tick execute_tick) const
{
return(past_record->isLoad() && past_record->commit &&
past_record->toCommitTick <= execute_tick);
}
bool
ElasticTrace::hasLoadBeenSent(TraceInfo* past_record,
Tick execute_tick) const
{
// Check if previous inst is a load sent earlier than this
return (past_record->isLoad() && past_record->commit &&
past_record->executeTick <= execute_tick);
}
bool
ElasticTrace::hasCompCompleted(TraceInfo* past_record,
Tick execute_tick) const
{
return(past_record->isComp() && past_record->toCommitTick <= execute_tick);
}
void
ElasticTrace::clearTempStoreUntil(const DynInstConstPtr& head_inst)
{
// Clear from temp store starting with the execution info object
// corresponding the head_inst and continue clearing by decrementing the
// sequence number until the last cleared sequence number.
InstSeqNum temp_sn = (head_inst->seqNum);
while (temp_sn > lastClearedSeqNum) {
auto itr_exec_info = tempStore.find(temp_sn);
if (itr_exec_info != tempStore.end()) {
InstExecInfo* exec_info_ptr = itr_exec_info->second;
// Free allocated memory for the info object
delete exec_info_ptr;
// Remove entry from temporary store
tempStore.erase(itr_exec_info);
}
temp_sn--;
}
// Update the last cleared sequence number to that of the head_inst
lastClearedSeqNum = head_inst->seqNum;
}
void
ElasticTrace::compDelayRob(TraceInfo* past_record, TraceInfo* new_record)
{
// The computation delay is the delay between the completion tick of the
// inst. pointed to by past_record and the execution tick of its dependent
// inst. pointed to by new_record.
int64_t comp_delay = -1;
Tick execution_tick = 0, completion_tick = 0;
DPRINTF(ElasticTrace, "Seq num %lli has ROB dependency on seq num %lli.\n",
new_record->instNum, past_record->instNum);
// Get the tick when the node is executed as per the modelling of
// computation delay
execution_tick = new_record->getExecuteTick();
if (past_record->isLoad()) {
if (new_record->isStore()) {
completion_tick = past_record->toCommitTick;
} else {
completion_tick = past_record->executeTick;
}
} else if (past_record->isStore()) {
completion_tick = past_record->commitTick;
} else if (past_record->isComp()){
completion_tick = past_record->toCommitTick;
}
assert(execution_tick >= completion_tick);
comp_delay = execution_tick - completion_tick;
DPRINTF(ElasticTrace, "Computational delay is %lli - %lli = %lli\n",
execution_tick, completion_tick, comp_delay);
// Assign the computational delay with respect to the dependency which
// completes the latest.
if (new_record->compDelay == -1)
new_record->compDelay = comp_delay;
else
new_record->compDelay = std::min(comp_delay, new_record->compDelay);
DPRINTF(ElasticTrace, "Final computational delay = %lli.\n",
new_record->compDelay);
}
void
ElasticTrace::compDelayPhysRegDep(TraceInfo* past_record,
TraceInfo* new_record)
{
// The computation delay is the delay between the completion tick of the
// inst. pointed to by past_record and the execution tick of its dependent
// inst. pointed to by new_record.
int64_t comp_delay = -1;
Tick execution_tick = 0, completion_tick = 0;
DPRINTF(ElasticTrace, "Seq. num %lli has register dependency on seq. num"
" %lli.\n", new_record->instNum, past_record->instNum);
// Get the tick when the node is executed as per the modelling of
// computation delay
execution_tick = new_record->getExecuteTick();
// When there is a physical register dependency on an instruction, the
// completion tick of that instruction is when it wrote to the register,
// that is toCommitTick. In case, of a store updating a destination
// register, this is approximated to commitTick instead
if (past_record->isStore()) {
completion_tick = past_record->commitTick;
} else {
completion_tick = past_record->toCommitTick;
}
assert(execution_tick >= completion_tick);
comp_delay = execution_tick - completion_tick;
DPRINTF(ElasticTrace, "Computational delay is %lli - %lli = %lli\n",
execution_tick, completion_tick, comp_delay);
// Assign the computational delay with respect to the dependency which
// completes the latest.
if (new_record->compDelay == -1)
new_record->compDelay = comp_delay;
else
new_record->compDelay = std::min(comp_delay, new_record->compDelay);
DPRINTF(ElasticTrace, "Final computational delay = %lli.\n",
new_record->compDelay);
}
Tick
ElasticTrace::TraceInfo::getExecuteTick() const
{
if (isLoad()) {
// Execution tick for a load instruction is when the request was sent,
// that is executeTick.
return executeTick;
} else if (isStore()) {
// Execution tick for a store instruction is when the request was sent,
// that is commitTick.
return commitTick;
} else {
// Execution tick for a non load/store instruction is when the register
// value was written to, that is commitTick.
return toCommitTick;
}
}
void
ElasticTrace::writeDepTrace(uint32_t num_to_write)
{
// Write the trace with fields as follows:
// Instruction sequence number
// If instruction was a load
// If instruction was a store
// If instruction has addr
// If instruction has size
// If instruction has flags
// List of order dependencies - optional, repeated
// Computational delay with respect to last completed dependency
// List of physical register RAW dependencies - optional, repeated
// Weight of a node equal to no. of filtered nodes before it - optional
uint16_t num_filtered_nodes = 0;
depTraceItr dep_trace_itr(depTrace.begin());
depTraceItr dep_trace_itr_start = dep_trace_itr;
while (num_to_write > 0) {
TraceInfo* temp_ptr = *dep_trace_itr;
assert(temp_ptr->type != Record::INVALID);
// If no node dependends on a comp node then there is no reason to
// track the comp node in the dependency graph. We filter out such
// nodes but count them and add a weight field to the subsequent node
// that we do include in the trace.
if (!temp_ptr->isComp() || temp_ptr->numDepts != 0) {
DPRINTFR(ElasticTrace, "Instruction with seq. num %lli "
"is as follows:\n", temp_ptr->instNum);
if (temp_ptr->isLoad() || temp_ptr->isStore()) {
DPRINTFR(ElasticTrace, "\tis a %s\n", temp_ptr->typeToStr());
DPRINTFR(ElasticTrace, "\thas a request with phys addr %i, "
"size %i, flags %i\n", temp_ptr->physAddr,
temp_ptr->size, temp_ptr->reqFlags);
} else {
DPRINTFR(ElasticTrace, "\tis a %s\n", temp_ptr->typeToStr());
}
if (firstWin && temp_ptr->compDelay == -1) {
if (temp_ptr->isLoad()) {
temp_ptr->compDelay = temp_ptr->executeTick;
} else if (temp_ptr->isStore()) {
temp_ptr->compDelay = temp_ptr->commitTick;
} else {
temp_ptr->compDelay = temp_ptr->toCommitTick;
}
}
assert(temp_ptr->compDelay != -1);
DPRINTFR(ElasticTrace, "\thas computational delay %lli\n",
temp_ptr->compDelay);
// Create a protobuf message for the dependency record
ProtoMessage::InstDepRecord dep_pkt;
dep_pkt.set_seq_num(temp_ptr->instNum);
dep_pkt.set_type(temp_ptr->type);
dep_pkt.set_pc(temp_ptr->pc);
if (temp_ptr->isLoad() || temp_ptr->isStore()) {
dep_pkt.set_flags(temp_ptr->reqFlags);
dep_pkt.set_p_addr(temp_ptr->physAddr);
// If tracing of virtual addresses is enabled, set the optional
// field for it
if (traceVirtAddr) {
dep_pkt.set_v_addr(temp_ptr->virtAddr);
dep_pkt.set_asid(temp_ptr->asid);
}
dep_pkt.set_size(temp_ptr->size);
}
dep_pkt.set_comp_delay(temp_ptr->compDelay);
if (temp_ptr->robDepList.empty()) {
DPRINTFR(ElasticTrace, "\thas no order (rob) dependencies\n");
}
while (!temp_ptr->robDepList.empty()) {
DPRINTFR(ElasticTrace, "\thas order (rob) dependency on %lli\n",
temp_ptr->robDepList.front());
dep_pkt.add_rob_dep(temp_ptr->robDepList.front());
temp_ptr->robDepList.pop_front();
}
if (temp_ptr->physRegDepList.empty()) {
DPRINTFR(ElasticTrace, "\thas no register dependencies\n");
}
while (!temp_ptr->physRegDepList.empty()) {
DPRINTFR(ElasticTrace, "\thas register dependency on %lli\n",
temp_ptr->physRegDepList.front());
dep_pkt.add_reg_dep(temp_ptr->physRegDepList.front());
temp_ptr->physRegDepList.pop_front();
}
if (num_filtered_nodes != 0) {
// Set the weight of this node as the no. of filtered nodes
// between this node and the last node that we wrote to output
// stream. The weight will be used during replay to model ROB
// occupancy of filtered nodes.
dep_pkt.set_weight(num_filtered_nodes);
num_filtered_nodes = 0;
}
// Write the message to the protobuf output stream
dataTraceStream->write(dep_pkt);
} else {
// Don't write the node to the trace but note that we have filtered
// out a node.
++numFilteredNodes;
++num_filtered_nodes;
}
dep_trace_itr++;
traceInfoMap.erase(temp_ptr->instNum);
delete temp_ptr;
num_to_write--;
}
depTrace.erase(dep_trace_itr_start, dep_trace_itr);
}
void
ElasticTrace::regStats() {
ProbeListenerObject::regStats();
using namespace Stats;
numRegDep
.name(name() + ".numRegDep")
.desc("Number of register dependencies recorded during tracing")
;
numOrderDepStores
.name(name() + ".numOrderDepStores")
.desc("Number of commit order (rob) dependencies for a store recorded"
" on a past load/store during tracing")
;
numIssueOrderDepLoads
.name(name() + ".numIssueOrderDepLoads")
.desc("Number of loads that got assigned issue order dependency"
" because they were dependency-free")
;
numIssueOrderDepStores
.name(name() + ".numIssueOrderDepStores")
.desc("Number of stores that got assigned issue order dependency"
" because they were dependency-free")
;
numIssueOrderDepOther
.name(name() + ".numIssueOrderDepOther")
.desc("Number of non load/store insts that got assigned issue order"
" dependency because they were dependency-free")
;
numFilteredNodes
.name(name() + ".numFilteredNodes")
.desc("No. of nodes filtered out before writing the output trace")
;
maxNumDependents
.name(name() + ".maxNumDependents")
.desc("Maximum number or dependents on any instruction")
;
maxTempStoreSize
.name(name() + ".maxTempStoreSize")
.desc("Maximum size of the temporary store during the run")
;
maxPhysRegDepMapSize
.name(name() + ".maxPhysRegDepMapSize")
.desc("Maximum size of register dependency map")
;
}
const std::string&
ElasticTrace::TraceInfo::typeToStr() const
{
return Record::RecordType_Name(type);
}
const std::string
ElasticTrace::name() const
{
return ProbeListenerObject::name();
}
void
ElasticTrace::flushTraces()
{
// Write to trace all records in the depTrace.
writeDepTrace(depTrace.size());
// Delete the stream objects
delete dataTraceStream;
delete instTraceStream;
}
ElasticTrace*
ElasticTraceParams::create()
{
return new ElasticTrace(this);
}
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