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/*
* Copyright (c) 2010-2014, 2017-2020 ARM Limited
* Copyright (c) 2013 Advanced Micro Devices, Inc.
* 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.
*
* Copyright (c) 2004-2005 The Regents of The University of Michigan
* All rights reserved.
*
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* 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;
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* this software without specific prior written permission.
*
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*/
#ifndef __CPU_O3_LSQ_UNIT_IMPL_HH__
#define __CPU_O3_LSQ_UNIT_IMPL_HH__
#include "arch/generic/debugfaults.hh"
#include "arch/locked_mem.hh"
#include "base/str.hh"
#include "config/the_isa.hh"
#include "cpu/checker/cpu.hh"
#include "cpu/o3/lsq.hh"
#include "cpu/o3/lsq_unit.hh"
#include "debug/Activity.hh"
#include "debug/HtmCpu.hh"
#include "debug/IEW.hh"
#include "debug/LSQUnit.hh"
#include "debug/O3PipeView.hh"
#include "mem/packet.hh"
#include "mem/request.hh"
template<class Impl>
LSQUnit<Impl>::WritebackEvent::WritebackEvent(const DynInstPtr &_inst,
PacketPtr _pkt, LSQUnit *lsq_ptr)
: Event(Default_Pri, AutoDelete),
inst(_inst), pkt(_pkt), lsqPtr(lsq_ptr)
{
assert(_inst->savedReq);
_inst->savedReq->writebackScheduled();
}
template<class Impl>
void
LSQUnit<Impl>::WritebackEvent::process()
{
assert(!lsqPtr->cpu->switchedOut());
lsqPtr->writeback(inst, pkt);
assert(inst->savedReq);
inst->savedReq->writebackDone();
delete pkt;
}
template<class Impl>
const char *
LSQUnit<Impl>::WritebackEvent::description() const
{
return "Store writeback";
}
template <class Impl>
bool
LSQUnit<Impl>::recvTimingResp(PacketPtr pkt)
{
auto senderState = dynamic_cast<LSQSenderState*>(pkt->senderState);
LSQRequest* req = senderState->request();
assert(req != nullptr);
bool ret = true;
/* Check that the request is still alive before any further action. */
if (senderState->alive()) {
ret = req->recvTimingResp(pkt);
} else {
senderState->outstanding--;
}
return ret;
}
template<class Impl>
void
LSQUnit<Impl>::completeDataAccess(PacketPtr pkt)
{
LSQSenderState *state = dynamic_cast<LSQSenderState *>(pkt->senderState);
DynInstPtr inst = state->inst;
// hardware transactional memory
// sanity check
if (pkt->isHtmTransactional() && !inst->isSquashed()) {
assert(inst->getHtmTransactionUid() == pkt->getHtmTransactionUid());
}
// if in a HTM transaction, it's possible
// to abort within the cache hierarchy.
// This is signalled back to the processor
// through responses to memory requests.
if (pkt->htmTransactionFailedInCache()) {
// cannot do this for write requests because
// they cannot tolerate faults
const HtmCacheFailure htm_rc =
pkt->getHtmTransactionFailedInCacheRC();
if(pkt->isWrite()) {
DPRINTF(HtmCpu,
"store notification (ignored) of HTM transaction failure "
"in cache - addr=0x%lx - rc=%s - htmUid=%d\n",
pkt->getAddr(), htmFailureToStr(htm_rc),
pkt->getHtmTransactionUid());
} else {
HtmFailureFaultCause fail_reason =
HtmFailureFaultCause::INVALID;
if (htm_rc == HtmCacheFailure::FAIL_SELF) {
fail_reason = HtmFailureFaultCause::SIZE;
} else if (htm_rc == HtmCacheFailure::FAIL_REMOTE) {
fail_reason = HtmFailureFaultCause::MEMORY;
} else if (htm_rc == HtmCacheFailure::FAIL_OTHER) {
// these are likely loads that were issued out of order
// they are faulted here, but it's unlikely that these will
// ever reach the commit head.
fail_reason = HtmFailureFaultCause::OTHER;
} else {
panic("HTM error - unhandled return code from cache (%s)",
htmFailureToStr(htm_rc));
}
inst->fault =
std::make_shared<GenericHtmFailureFault>(
inst->getHtmTransactionUid(),
fail_reason);
DPRINTF(HtmCpu,
"load notification of HTM transaction failure "
"in cache - pc=%s - addr=0x%lx - "
"rc=%u - htmUid=%d\n",
inst->pcState(), pkt->getAddr(),
htmFailureToStr(htm_rc), pkt->getHtmTransactionUid());
}
}
cpu->ppDataAccessComplete->notify(std::make_pair(inst, pkt));
/* Notify the sender state that the access is complete (for ownership
* tracking). */
state->complete();
assert(!cpu->switchedOut());
if (!inst->isSquashed()) {
if (state->needWB) {
// Only loads, store conditionals and atomics perform the writeback
// after receving the response from the memory
assert(inst->isLoad() || inst->isStoreConditional() ||
inst->isAtomic());
// hardware transactional memory
if (pkt->htmTransactionFailedInCache()) {
state->request()->mainPacket()->setHtmTransactionFailedInCache(
pkt->getHtmTransactionFailedInCacheRC() );
}
writeback(inst, state->request()->mainPacket());
if (inst->isStore() || inst->isAtomic()) {
auto ss = dynamic_cast<SQSenderState*>(state);
ss->writebackDone();
completeStore(ss->idx);
}
} else if (inst->isStore()) {
// This is a regular store (i.e., not store conditionals and
// atomics), so it can complete without writing back
completeStore(dynamic_cast<SQSenderState*>(state)->idx);
}
}
}
template <class Impl>
LSQUnit<Impl>::LSQUnit(uint32_t lqEntries, uint32_t sqEntries)
: lsqID(-1), storeQueue(sqEntries+1), loadQueue(lqEntries+1),
loads(0), stores(0), storesToWB(0),
htmStarts(0), htmStops(0),
lastRetiredHtmUid(0),
cacheBlockMask(0), stalled(false),
isStoreBlocked(false), storeInFlight(false), hasPendingRequest(false),
pendingRequest(nullptr), stats(nullptr)
{
}
template<class Impl>
void
LSQUnit<Impl>::init(O3CPU *cpu_ptr, IEW *iew_ptr,
const DerivO3CPUParams &params, LSQ *lsq_ptr, unsigned id)
{
lsqID = id;
cpu = cpu_ptr;
iewStage = iew_ptr;
lsq = lsq_ptr;
cpu->addStatGroup(csprintf("lsq%i", lsqID).c_str(), &stats);
DPRINTF(LSQUnit, "Creating LSQUnit%i object.\n",lsqID);
depCheckShift = params.LSQDepCheckShift;
checkLoads = params.LSQCheckLoads;
needsTSO = params.needsTSO;
resetState();
}
template<class Impl>
void
LSQUnit<Impl>::resetState()
{
loads = stores = storesToWB = 0;
// hardware transactional memory
// nesting depth
htmStarts = htmStops = 0;
storeWBIt = storeQueue.begin();
retryPkt = NULL;
memDepViolator = NULL;
stalled = false;
cacheBlockMask = ~(cpu->cacheLineSize() - 1);
}
template<class Impl>
std::string
LSQUnit<Impl>::name() const
{
if (Impl::MaxThreads == 1) {
return iewStage->name() + ".lsq";
} else {
return iewStage->name() + ".lsq.thread" + std::to_string(lsqID);
}
}
template <class Impl>
LSQUnit<Impl>::LSQUnitStats::LSQUnitStats(Stats::Group *parent)
: Stats::Group(parent),
ADD_STAT(forwLoads, UNIT_COUNT,
"Number of loads that had data forwarded from stores"),
ADD_STAT(squashedLoads, UNIT_COUNT,
"Number of loads squashed"),
ADD_STAT(ignoredResponses, UNIT_COUNT,
"Number of memory responses ignored because the instruction is "
"squashed"),
ADD_STAT(memOrderViolation, UNIT_COUNT,
"Number of memory ordering violations"),
ADD_STAT(squashedStores, UNIT_COUNT, "Number of stores squashed"),
ADD_STAT(rescheduledLoads, UNIT_COUNT,
"Number of loads that were rescheduled"),
ADD_STAT(blockedByCache, UNIT_COUNT,
"Number of times an access to memory failed due to the cache "
"being blocked")
{
}
template<class Impl>
void
LSQUnit<Impl>::setDcachePort(RequestPort *dcache_port)
{
dcachePort = dcache_port;
}
template<class Impl>
void
LSQUnit<Impl>::drainSanityCheck() const
{
for (int i = 0; i < loadQueue.capacity(); ++i)
assert(!loadQueue[i].valid());
assert(storesToWB == 0);
assert(!retryPkt);
}
template<class Impl>
void
LSQUnit<Impl>::takeOverFrom()
{
resetState();
}
template <class Impl>
void
LSQUnit<Impl>::insert(const DynInstPtr &inst)
{
assert(inst->isMemRef());
assert(inst->isLoad() || inst->isStore() || inst->isAtomic());
if (inst->isLoad()) {
insertLoad(inst);
} else {
insertStore(inst);
}
inst->setInLSQ();
}
template <class Impl>
void
LSQUnit<Impl>::insertLoad(const DynInstPtr &load_inst)
{
assert(!loadQueue.full());
assert(loads < loadQueue.capacity());
DPRINTF(LSQUnit, "Inserting load PC %s, idx:%i [sn:%lli]\n",
load_inst->pcState(), loadQueue.tail(), load_inst->seqNum);
/* Grow the queue. */
loadQueue.advance_tail();
load_inst->sqIt = storeQueue.end();
assert(!loadQueue.back().valid());
loadQueue.back().set(load_inst);
load_inst->lqIdx = loadQueue.tail();
assert(load_inst->lqIdx > 0);
load_inst->lqIt = loadQueue.getIterator(load_inst->lqIdx);
++loads;
// hardware transactional memory
// transactional state and nesting depth must be tracked
// in the in-order part of the core.
if (load_inst->isHtmStart()) {
htmStarts++;
DPRINTF(HtmCpu, ">> htmStarts++ (%d) : htmStops (%d)\n",
htmStarts, htmStops);
const int htm_depth = htmStarts - htmStops;
const auto& htm_cpt = cpu->tcBase(lsqID)->getHtmCheckpointPtr();
auto htm_uid = htm_cpt->getHtmUid();
// for debugging purposes
if (!load_inst->inHtmTransactionalState()) {
htm_uid = htm_cpt->newHtmUid();
DPRINTF(HtmCpu, "generating new htmUid=%u\n", htm_uid);
if (htm_depth != 1) {
DPRINTF(HtmCpu,
"unusual HTM transactional depth (%d)"
" possibly caused by mispeculation - htmUid=%u\n",
htm_depth, htm_uid);
}
}
load_inst->setHtmTransactionalState(htm_uid, htm_depth);
}
if (load_inst->isHtmStop()) {
htmStops++;
DPRINTF(HtmCpu, ">> htmStarts (%d) : htmStops++ (%d)\n",
htmStarts, htmStops);
if (htmStops==1 && htmStarts==0) {
DPRINTF(HtmCpu,
"htmStops==1 && htmStarts==0. "
"This generally shouldn't happen "
"(unless due to misspeculation)\n");
}
}
}
template <class Impl>
void
LSQUnit<Impl>::insertStore(const DynInstPtr& store_inst)
{
// Make sure it is not full before inserting an instruction.
assert(!storeQueue.full());
assert(stores < storeQueue.capacity());
DPRINTF(LSQUnit, "Inserting store PC %s, idx:%i [sn:%lli]\n",
store_inst->pcState(), storeQueue.tail(), store_inst->seqNum);
storeQueue.advance_tail();
store_inst->sqIdx = storeQueue.tail();
store_inst->lqIdx = loadQueue.tail() + 1;
assert(store_inst->lqIdx > 0);
store_inst->lqIt = loadQueue.end();
storeQueue.back().set(store_inst);
++stores;
}
template <class Impl>
typename Impl::DynInstPtr
LSQUnit<Impl>::getMemDepViolator()
{
DynInstPtr temp = memDepViolator;
memDepViolator = NULL;
return temp;
}
template <class Impl>
unsigned
LSQUnit<Impl>::numFreeLoadEntries()
{
//LQ has an extra dummy entry to differentiate
//empty/full conditions. Subtract 1 from the free entries.
DPRINTF(LSQUnit, "LQ size: %d, #loads occupied: %d\n",
1 + loadQueue.capacity(), loads);
return loadQueue.capacity() - loads;
}
template <class Impl>
unsigned
LSQUnit<Impl>::numFreeStoreEntries()
{
//SQ has an extra dummy entry to differentiate
//empty/full conditions. Subtract 1 from the free entries.
DPRINTF(LSQUnit, "SQ size: %d, #stores occupied: %d\n",
1 + storeQueue.capacity(), stores);
return storeQueue.capacity() - stores;
}
template <class Impl>
void
LSQUnit<Impl>::checkSnoop(PacketPtr pkt)
{
// Should only ever get invalidations in here
assert(pkt->isInvalidate());
DPRINTF(LSQUnit, "Got snoop for address %#x\n", pkt->getAddr());
for (int x = 0; x < cpu->numContexts(); x++) {
ThreadContext *tc = cpu->getContext(x);
bool no_squash = cpu->thread[x]->noSquashFromTC;
cpu->thread[x]->noSquashFromTC = true;
TheISA::handleLockedSnoop(tc, pkt, cacheBlockMask);
cpu->thread[x]->noSquashFromTC = no_squash;
}
if (loadQueue.empty())
return;
auto iter = loadQueue.begin();
Addr invalidate_addr = pkt->getAddr() & cacheBlockMask;
DynInstPtr ld_inst = iter->instruction();
assert(ld_inst);
LSQRequest *req = iter->request();
// Check that this snoop didn't just invalidate our lock flag
if (ld_inst->effAddrValid() &&
req->isCacheBlockHit(invalidate_addr, cacheBlockMask)
&& ld_inst->memReqFlags & Request::LLSC)
TheISA::handleLockedSnoopHit(ld_inst.get());
bool force_squash = false;
while (++iter != loadQueue.end()) {
ld_inst = iter->instruction();
assert(ld_inst);
req = iter->request();
if (!ld_inst->effAddrValid() || ld_inst->strictlyOrdered())
continue;
DPRINTF(LSQUnit, "-- inst [sn:%lli] to pktAddr:%#x\n",
ld_inst->seqNum, invalidate_addr);
if (force_squash ||
req->isCacheBlockHit(invalidate_addr, cacheBlockMask)) {
if (needsTSO) {
// If we have a TSO system, as all loads must be ordered with
// all other loads, this load as well as *all* subsequent loads
// need to be squashed to prevent possible load reordering.
force_squash = true;
}
if (ld_inst->possibleLoadViolation() || force_squash) {
DPRINTF(LSQUnit, "Conflicting load at addr %#x [sn:%lli]\n",
pkt->getAddr(), ld_inst->seqNum);
// Mark the load for re-execution
ld_inst->fault = std::make_shared<ReExec>();
req->setStateToFault();
} else {
DPRINTF(LSQUnit, "HitExternal Snoop for addr %#x [sn:%lli]\n",
pkt->getAddr(), ld_inst->seqNum);
// Make sure that we don't lose a snoop hitting a LOCKED
// address since the LOCK* flags don't get updated until
// commit.
if (ld_inst->memReqFlags & Request::LLSC)
TheISA::handleLockedSnoopHit(ld_inst.get());
// If a older load checks this and it's true
// then we might have missed the snoop
// in which case we need to invalidate to be sure
ld_inst->hitExternalSnoop(true);
}
}
}
return;
}
template <class Impl>
Fault
LSQUnit<Impl>::checkViolations(typename LoadQueue::iterator& loadIt,
const DynInstPtr& inst)
{
Addr inst_eff_addr1 = inst->effAddr >> depCheckShift;
Addr inst_eff_addr2 = (inst->effAddr + inst->effSize - 1) >> depCheckShift;
/** @todo in theory you only need to check an instruction that has executed
* however, there isn't a good way in the pipeline at the moment to check
* all instructions that will execute before the store writes back. Thus,
* like the implementation that came before it, we're overly conservative.
*/
while (loadIt != loadQueue.end()) {
DynInstPtr ld_inst = loadIt->instruction();
if (!ld_inst->effAddrValid() || ld_inst->strictlyOrdered()) {
++loadIt;
continue;
}
Addr ld_eff_addr1 = ld_inst->effAddr >> depCheckShift;
Addr ld_eff_addr2 =
(ld_inst->effAddr + ld_inst->effSize - 1) >> depCheckShift;
if (inst_eff_addr2 >= ld_eff_addr1 && inst_eff_addr1 <= ld_eff_addr2) {
if (inst->isLoad()) {
// If this load is to the same block as an external snoop
// invalidate that we've observed then the load needs to be
// squashed as it could have newer data
if (ld_inst->hitExternalSnoop()) {
if (!memDepViolator ||
ld_inst->seqNum < memDepViolator->seqNum) {
DPRINTF(LSQUnit, "Detected fault with inst [sn:%lli] "
"and [sn:%lli] at address %#x\n",
inst->seqNum, ld_inst->seqNum, ld_eff_addr1);
memDepViolator = ld_inst;
++stats.memOrderViolation;
return std::make_shared<GenericISA::M5PanicFault>(
"Detected fault with inst [sn:%lli] and "
"[sn:%lli] at address %#x\n",
inst->seqNum, ld_inst->seqNum, ld_eff_addr1);
}
}
// Otherwise, mark the load has a possible load violation
// and if we see a snoop before it's commited, we need to squash
ld_inst->possibleLoadViolation(true);
DPRINTF(LSQUnit, "Found possible load violation at addr: %#x"
" between instructions [sn:%lli] and [sn:%lli]\n",
inst_eff_addr1, inst->seqNum, ld_inst->seqNum);
} else {
// A load/store incorrectly passed this store.
// Check if we already have a violator, or if it's newer
// squash and refetch.
if (memDepViolator && ld_inst->seqNum > memDepViolator->seqNum)
break;
DPRINTF(LSQUnit, "Detected fault with inst [sn:%lli] and "
"[sn:%lli] at address %#x\n",
inst->seqNum, ld_inst->seqNum, ld_eff_addr1);
memDepViolator = ld_inst;
++stats.memOrderViolation;
return std::make_shared<GenericISA::M5PanicFault>(
"Detected fault with "
"inst [sn:%lli] and [sn:%lli] at address %#x\n",
inst->seqNum, ld_inst->seqNum, ld_eff_addr1);
}
}
++loadIt;
}
return NoFault;
}
template <class Impl>
Fault
LSQUnit<Impl>::executeLoad(const DynInstPtr &inst)
{
// Execute a specific load.
Fault load_fault = NoFault;
DPRINTF(LSQUnit, "Executing load PC %s, [sn:%lli]\n",
inst->pcState(), inst->seqNum);
assert(!inst->isSquashed());
load_fault = inst->initiateAcc();
if (load_fault == NoFault && !inst->readMemAccPredicate()) {
assert(inst->readPredicate());
inst->setExecuted();
inst->completeAcc(nullptr);
iewStage->instToCommit(inst);
iewStage->activityThisCycle();
return NoFault;
}
if (inst->isTranslationDelayed() && load_fault == NoFault)
return load_fault;
if (load_fault != NoFault && inst->translationCompleted() &&
inst->savedReq->isPartialFault() && !inst->savedReq->isComplete()) {
assert(inst->savedReq->isSplit());
// If we have a partial fault where the mem access is not complete yet
// then the cache must have been blocked. This load will be re-executed
// when the cache gets unblocked. We will handle the fault when the
// mem access is complete.
return NoFault;
}
// If the instruction faulted or predicated false, then we need to send it
// along to commit without the instruction completing.
if (load_fault != NoFault || !inst->readPredicate()) {
// Send this instruction to commit, also make sure iew stage
// realizes there is activity. Mark it as executed unless it
// is a strictly ordered load that needs to hit the head of
// commit.
if (!inst->readPredicate())
inst->forwardOldRegs();
DPRINTF(LSQUnit, "Load [sn:%lli] not executed from %s\n",
inst->seqNum,
(load_fault != NoFault ? "fault" : "predication"));
if (!(inst->hasRequest() && inst->strictlyOrdered()) ||
inst->isAtCommit()) {
inst->setExecuted();
}
iewStage->instToCommit(inst);
iewStage->activityThisCycle();
} else {
if (inst->effAddrValid()) {
auto it = inst->lqIt;
++it;
if (checkLoads)
return checkViolations(it, inst);
}
}
return load_fault;
}
template <class Impl>
Fault
LSQUnit<Impl>::executeStore(const DynInstPtr &store_inst)
{
// Make sure that a store exists.
assert(stores != 0);
int store_idx = store_inst->sqIdx;
DPRINTF(LSQUnit, "Executing store PC %s [sn:%lli]\n",
store_inst->pcState(), store_inst->seqNum);
assert(!store_inst->isSquashed());
// Check the recently completed loads to see if any match this store's
// address. If so, then we have a memory ordering violation.
typename LoadQueue::iterator loadIt = store_inst->lqIt;
Fault store_fault = store_inst->initiateAcc();
if (store_inst->isTranslationDelayed() &&
store_fault == NoFault)
return store_fault;
if (!store_inst->readPredicate()) {
DPRINTF(LSQUnit, "Store [sn:%lli] not executed from predication\n",
store_inst->seqNum);
store_inst->forwardOldRegs();
return store_fault;
}
if (storeQueue[store_idx].size() == 0) {
DPRINTF(LSQUnit,"Fault on Store PC %s, [sn:%lli], Size = 0\n",
store_inst->pcState(), store_inst->seqNum);
return store_fault;
}
assert(store_fault == NoFault);
if (store_inst->isStoreConditional() || store_inst->isAtomic()) {
// Store conditionals and Atomics need to set themselves as able to
// writeback if we haven't had a fault by here.
storeQueue[store_idx].canWB() = true;
++storesToWB;
}
return checkViolations(loadIt, store_inst);
}
template <class Impl>
void
LSQUnit<Impl>::commitLoad()
{
assert(loadQueue.front().valid());
DPRINTF(LSQUnit, "Committing head load instruction, PC %s\n",
loadQueue.front().instruction()->pcState());
loadQueue.front().clear();
loadQueue.pop_front();
--loads;
}
template <class Impl>
void
LSQUnit<Impl>::commitLoads(InstSeqNum &youngest_inst)
{
assert(loads == 0 || loadQueue.front().valid());
while (loads != 0 && loadQueue.front().instruction()->seqNum
<= youngest_inst) {
commitLoad();
}
}
template <class Impl>
void
LSQUnit<Impl>::commitStores(InstSeqNum &youngest_inst)
{
assert(stores == 0 || storeQueue.front().valid());
/* Forward iterate the store queue (age order). */
for (auto& x : storeQueue) {
assert(x.valid());
// Mark any stores that are now committed and have not yet
// been marked as able to write back.
if (!x.canWB()) {
if (x.instruction()->seqNum > youngest_inst) {
break;
}
DPRINTF(LSQUnit, "Marking store as able to write back, PC "
"%s [sn:%lli]\n",
x.instruction()->pcState(),
x.instruction()->seqNum);
x.canWB() = true;
++storesToWB;
}
}
}
template <class Impl>
void
LSQUnit<Impl>::writebackBlockedStore()
{
assert(isStoreBlocked);
storeWBIt->request()->sendPacketToCache();
if (storeWBIt->request()->isSent()){
storePostSend();
}
}
template <class Impl>
void
LSQUnit<Impl>::writebackStores()
{
if (isStoreBlocked) {
DPRINTF(LSQUnit, "Writing back blocked store\n");
writebackBlockedStore();
}
while (storesToWB > 0 &&
storeWBIt.dereferenceable() &&
storeWBIt->valid() &&
storeWBIt->canWB() &&
((!needsTSO) || (!storeInFlight)) &&
lsq->cachePortAvailable(false)) {
if (isStoreBlocked) {
DPRINTF(LSQUnit, "Unable to write back any more stores, cache"
" is blocked!\n");
break;
}
// Store didn't write any data so no need to write it back to
// memory.
if (storeWBIt->size() == 0) {
/* It is important that the preincrement happens at (or before)
* the call, as the the code of completeStore checks
* storeWBIt. */
completeStore(storeWBIt++);
continue;
}
if (storeWBIt->instruction()->isDataPrefetch()) {
storeWBIt++;
continue;
}
assert(storeWBIt->hasRequest());
assert(!storeWBIt->committed());
DynInstPtr inst = storeWBIt->instruction();
LSQRequest* req = storeWBIt->request();
// Process store conditionals or store release after all previous
// stores are completed
if ((req->mainRequest()->isLLSC() ||
req->mainRequest()->isRelease()) &&
(storeWBIt.idx() != storeQueue.head())) {
DPRINTF(LSQUnit, "Store idx:%i PC:%s to Addr:%#x "
"[sn:%lli] is %s%s and not head of the queue\n",
storeWBIt.idx(), inst->pcState(),
req->request()->getPaddr(), inst->seqNum,
req->mainRequest()->isLLSC() ? "SC" : "",
req->mainRequest()->isRelease() ? "/Release" : "");
break;
}
storeWBIt->committed() = true;
assert(!inst->memData);
inst->memData = new uint8_t[req->_size];
if (storeWBIt->isAllZeros())
memset(inst->memData, 0, req->_size);
else
memcpy(inst->memData, storeWBIt->data(), req->_size);
if (req->senderState() == nullptr) {
SQSenderState *state = new SQSenderState(storeWBIt);
state->isLoad = false;
state->needWB = false;
state->inst = inst;
req->senderState(state);
if (inst->isStoreConditional() || inst->isAtomic()) {
/* Only store conditionals and atomics need a writeback. */
state->needWB = true;
}
}
req->buildPackets();
DPRINTF(LSQUnit, "D-Cache: Writing back store idx:%i PC:%s "
"to Addr:%#x, data:%#x [sn:%lli]\n",
storeWBIt.idx(), inst->pcState(),
req->request()->getPaddr(), (int)*(inst->memData),
inst->seqNum);
// @todo: Remove this SC hack once the memory system handles it.
if (inst->isStoreConditional()) {
// Disable recording the result temporarily. Writing to
// misc regs normally updates the result, but this is not
// the desired behavior when handling store conditionals.
inst->recordResult(false);
bool success = TheISA::handleLockedWrite(inst.get(),
req->request(), cacheBlockMask);
inst->recordResult(true);
req->packetSent();
if (!success) {
req->complete();
// Instantly complete this store.
DPRINTF(LSQUnit, "Store conditional [sn:%lli] failed. "
"Instantly completing it.\n",
inst->seqNum);
PacketPtr new_pkt = new Packet(*req->packet());
WritebackEvent *wb = new WritebackEvent(inst,
new_pkt, this);
cpu->schedule(wb, curTick() + 1);
completeStore(storeWBIt);
if (!storeQueue.empty())
storeWBIt++;
else
storeWBIt = storeQueue.end();
continue;
}
}
if (req->request()->isLocalAccess()) {
assert(!inst->isStoreConditional());
assert(!inst->inHtmTransactionalState());
ThreadContext *thread = cpu->tcBase(lsqID);
PacketPtr main_pkt = new Packet(req->mainRequest(),
MemCmd::WriteReq);
main_pkt->dataStatic(inst->memData);
req->request()->localAccessor(thread, main_pkt);
delete main_pkt;
completeStore(storeWBIt);
storeWBIt++;
continue;
}
/* Send to cache */
req->sendPacketToCache();
/* If successful, do the post send */
if (req->isSent()) {
storePostSend();
} else {
DPRINTF(LSQUnit, "D-Cache became blocked when writing [sn:%lli], "
"will retry later\n",
inst->seqNum);
}
}
assert(stores >= 0 && storesToWB >= 0);
}
template <class Impl>
void
LSQUnit<Impl>::squash(const InstSeqNum &squashed_num)
{
DPRINTF(LSQUnit, "Squashing until [sn:%lli]!"
"(Loads:%i Stores:%i)\n", squashed_num, loads, stores);
while (loads != 0 &&
loadQueue.back().instruction()->seqNum > squashed_num) {
DPRINTF(LSQUnit,"Load Instruction PC %s squashed, "
"[sn:%lli]\n",
loadQueue.back().instruction()->pcState(),
loadQueue.back().instruction()->seqNum);
if (isStalled() && loadQueue.tail() == stallingLoadIdx) {
stalled = false;
stallingStoreIsn = 0;
stallingLoadIdx = 0;
}
// hardware transactional memory
// Squashing instructions can alter the transaction nesting depth
// and must be corrected before fetching resumes.
if (loadQueue.back().instruction()->isHtmStart())
{
htmStarts = (--htmStarts < 0) ? 0 : htmStarts;
DPRINTF(HtmCpu, ">> htmStarts-- (%d) : htmStops (%d)\n",
htmStarts, htmStops);
}
if (loadQueue.back().instruction()->isHtmStop())
{
htmStops = (--htmStops < 0) ? 0 : htmStops;
DPRINTF(HtmCpu, ">> htmStarts (%d) : htmStops-- (%d)\n",
htmStarts, htmStops);
}
// Clear the smart pointer to make sure it is decremented.
loadQueue.back().instruction()->setSquashed();
loadQueue.back().clear();
--loads;
loadQueue.pop_back();
++stats.squashedLoads;
}
// hardware transactional memory
// scan load queue (from oldest to youngest) for most recent valid htmUid
auto scan_it = loadQueue.begin();
uint64_t in_flight_uid = 0;
while (scan_it != loadQueue.end()) {
if (scan_it->instruction()->isHtmStart() &&
!scan_it->instruction()->isSquashed()) {
in_flight_uid = scan_it->instruction()->getHtmTransactionUid();
DPRINTF(HtmCpu, "loadQueue[%d]: found valid HtmStart htmUid=%u\n",
scan_it._idx, in_flight_uid);
}
scan_it++;
}
// If there's a HtmStart in the pipeline then use its htmUid,
// otherwise use the most recently committed uid
const auto& htm_cpt = cpu->tcBase(lsqID)->getHtmCheckpointPtr();
if (htm_cpt) {
const uint64_t old_local_htm_uid = htm_cpt->getHtmUid();
uint64_t new_local_htm_uid;
if (in_flight_uid > 0)
new_local_htm_uid = in_flight_uid;
else
new_local_htm_uid = lastRetiredHtmUid;
if (old_local_htm_uid != new_local_htm_uid) {
DPRINTF(HtmCpu, "flush: lastRetiredHtmUid=%u\n",
lastRetiredHtmUid);
DPRINTF(HtmCpu, "flush: resetting localHtmUid=%u\n",
new_local_htm_uid);
htm_cpt->setHtmUid(new_local_htm_uid);
}
}
if (memDepViolator && squashed_num < memDepViolator->seqNum) {
memDepViolator = NULL;
}
while (stores != 0 &&
storeQueue.back().instruction()->seqNum > squashed_num) {
// Instructions marked as can WB are already committed.
if (storeQueue.back().canWB()) {
break;
}
DPRINTF(LSQUnit,"Store Instruction PC %s squashed, "
"idx:%i [sn:%lli]\n",
storeQueue.back().instruction()->pcState(),
storeQueue.tail(), storeQueue.back().instruction()->seqNum);
// I don't think this can happen. It should have been cleared
// by the stalling load.
if (isStalled() &&
storeQueue.back().instruction()->seqNum == stallingStoreIsn) {
panic("Is stalled should have been cleared by stalling load!\n");
stalled = false;
stallingStoreIsn = 0;
}
// Clear the smart pointer to make sure it is decremented.
storeQueue.back().instruction()->setSquashed();
// Must delete request now that it wasn't handed off to
// memory. This is quite ugly. @todo: Figure out the proper
// place to really handle request deletes.
storeQueue.back().clear();
--stores;
storeQueue.pop_back();
++stats.squashedStores;
}
}
template <class Impl>
void
LSQUnit<Impl>::storePostSend()
{
if (isStalled() &&
storeWBIt->instruction()->seqNum == stallingStoreIsn) {
DPRINTF(LSQUnit, "Unstalling, stalling store [sn:%lli] "
"load idx:%i\n",
stallingStoreIsn, stallingLoadIdx);
stalled = false;
stallingStoreIsn = 0;
iewStage->replayMemInst(loadQueue[stallingLoadIdx].instruction());
}
if (!storeWBIt->instruction()->isStoreConditional()) {
// The store is basically completed at this time. This
// only works so long as the checker doesn't try to
// verify the value in memory for stores.
storeWBIt->instruction()->setCompleted();
if (cpu->checker) {
cpu->checker->verify(storeWBIt->instruction());
}
}
if (needsTSO) {
storeInFlight = true;
}
storeWBIt++;
}
template <class Impl>
void
LSQUnit<Impl>::writeback(const DynInstPtr &inst, PacketPtr pkt)
{
iewStage->wakeCPU();
// Squashed instructions do not need to complete their access.
if (inst->isSquashed()) {
assert (!inst->isStore() || inst->isStoreConditional());
++stats.ignoredResponses;
return;
}
if (!inst->isExecuted()) {
inst->setExecuted();
if (inst->fault == NoFault) {
// Complete access to copy data to proper place.
inst->completeAcc(pkt);
} else {
// If the instruction has an outstanding fault, we cannot complete
// the access as this discards the current fault.
// If we have an outstanding fault, the fault should only be of
// type ReExec or - in case of a SplitRequest - a partial
// translation fault
// Unless it's a hardware transactional memory fault
auto htm_fault = std::dynamic_pointer_cast<
GenericHtmFailureFault>(inst->fault);
if (!htm_fault) {
assert(dynamic_cast<ReExec*>(inst->fault.get()) != nullptr ||
inst->savedReq->isPartialFault());
} else if (!pkt->htmTransactionFailedInCache()) {
// Situation in which the instruction has a hardware transactional
// memory fault but not the packet itself. This can occur with
// ldp_uop microops since access is spread over multiple packets.
DPRINTF(HtmCpu,
"%s writeback with HTM failure fault, "
"however, completing packet is not aware of "
"transaction failure. cause=%s htmUid=%u\n",
inst->staticInst->getName(),
htmFailureToStr(htm_fault->getHtmFailureFaultCause()),
htm_fault->getHtmUid());
}
DPRINTF(LSQUnit, "Not completing instruction [sn:%lli] access "
"due to pending fault.\n", inst->seqNum);
}
}
// Need to insert instruction into queue to commit
iewStage->instToCommit(inst);
iewStage->activityThisCycle();
// see if this load changed the PC
iewStage->checkMisprediction(inst);
}
template <class Impl>
void
LSQUnit<Impl>::completeStore(typename StoreQueue::iterator store_idx)
{
assert(store_idx->valid());
store_idx->completed() = true;
--storesToWB;
// A bit conservative because a store completion may not free up entries,
// but hopefully avoids two store completions in one cycle from making
// the CPU tick twice.
cpu->wakeCPU();
cpu->activityThisCycle();
/* We 'need' a copy here because we may clear the entry from the
* store queue. */
DynInstPtr store_inst = store_idx->instruction();
if (store_idx == storeQueue.begin()) {
do {
storeQueue.front().clear();
storeQueue.pop_front();
--stores;
} while (storeQueue.front().completed() &&
!storeQueue.empty());
iewStage->updateLSQNextCycle = true;
}
DPRINTF(LSQUnit, "Completing store [sn:%lli], idx:%i, store head "
"idx:%i\n",
store_inst->seqNum, store_idx.idx() - 1, storeQueue.head() - 1);
#if TRACING_ON
if (DTRACE(O3PipeView)) {
store_inst->storeTick =
curTick() - store_inst->fetchTick;
}
#endif
if (isStalled() &&
store_inst->seqNum == stallingStoreIsn) {
DPRINTF(LSQUnit, "Unstalling, stalling store [sn:%lli] "
"load idx:%i\n",
stallingStoreIsn, stallingLoadIdx);
stalled = false;
stallingStoreIsn = 0;
iewStage->replayMemInst(loadQueue[stallingLoadIdx].instruction());
}
store_inst->setCompleted();
if (needsTSO) {
storeInFlight = false;
}
// Tell the checker we've completed this instruction. Some stores
// may get reported twice to the checker, but the checker can
// handle that case.
// Store conditionals cannot be sent to the checker yet, they have
// to update the misc registers first which should take place
// when they commit
if (cpu->checker && !store_inst->isStoreConditional()) {
cpu->checker->verify(store_inst);
}
}
template <class Impl>
bool
LSQUnit<Impl>::trySendPacket(bool isLoad, PacketPtr data_pkt)
{
bool ret = true;
bool cache_got_blocked = false;
auto state = dynamic_cast<LSQSenderState*>(data_pkt->senderState);
if (!lsq->cacheBlocked() &&
lsq->cachePortAvailable(isLoad)) {
if (!dcachePort->sendTimingReq(data_pkt)) {
ret = false;
cache_got_blocked = true;
}
} else {
ret = false;
}
if (ret) {
if (!isLoad) {
isStoreBlocked = false;
}
lsq->cachePortBusy(isLoad);
state->outstanding++;
state->request()->packetSent();
} else {
if (cache_got_blocked) {
lsq->cacheBlocked(true);
++stats.blockedByCache;
}
if (!isLoad) {
assert(state->request() == storeWBIt->request());
isStoreBlocked = true;
}
state->request()->packetNotSent();
}
return ret;
}
template <class Impl>
void
LSQUnit<Impl>::recvRetry()
{
if (isStoreBlocked) {
DPRINTF(LSQUnit, "Receiving retry: blocked store\n");
writebackBlockedStore();
}
}
template <class Impl>
void
LSQUnit<Impl>::dumpInsts() const
{
cprintf("Load store queue: Dumping instructions.\n");
cprintf("Load queue size: %i\n", loads);
cprintf("Load queue: ");
for (const auto& e: loadQueue) {
const DynInstPtr &inst(e.instruction());
cprintf("%s.[sn:%llu] ", inst->pcState(), inst->seqNum);
}
cprintf("\n");
cprintf("Store queue size: %i\n", stores);
cprintf("Store queue: ");
for (const auto& e: storeQueue) {
const DynInstPtr &inst(e.instruction());
cprintf("%s.[sn:%llu] ", inst->pcState(), inst->seqNum);
}
cprintf("\n");
}
template <class Impl>
unsigned int
LSQUnit<Impl>::cacheLineSize()
{
return cpu->cacheLineSize();
}
#endif//__CPU_O3_LSQ_UNIT_IMPL_HH__