gem5/cpu/o3/lsq_unit_impl.hh

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/*
* Copyright (c) 2004-2005 The Regents of The University of Michigan
* 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.
*/
#include "cpu/checker/cpu.hh"
#include "cpu/o3/lsq_unit.hh"
#include "base/str.hh"
template <class Impl>
LSQUnit<Impl>::StoreCompletionEvent::StoreCompletionEvent(int store_idx,
Event *wb_event,
LSQUnit<Impl> *lsq_ptr)
: Event(&mainEventQueue),
wbEvent(wb_event),
storeIdx(store_idx),
lsqPtr(lsq_ptr)
{
this->setFlags(Event::AutoDelete);
}
template <class Impl>
void
LSQUnit<Impl>::StoreCompletionEvent::process()
{
DPRINTF(LSQ, "Cache miss complete for store idx:%i\n", storeIdx);
DPRINTF(Activity, "Activity: st writeback event idx:%i\n", storeIdx);
//lsqPtr->removeMSHR(lsqPtr->storeQueue[storeIdx].inst->seqNum);
if (lsqPtr->isSwitchedOut())
return;
lsqPtr->cpu->wakeCPU();
if (wbEvent)
wbEvent->process();
lsqPtr->completeStore(storeIdx);
}
template <class Impl>
const char *
LSQUnit<Impl>::StoreCompletionEvent::description()
{
return "LSQ store completion event";
}
template <class Impl>
LSQUnit<Impl>::LSQUnit()
: loads(0), stores(0), storesToWB(0), stalled(false), isLoadBlocked(false),
loadBlockedHandled(false)
{
}
template<class Impl>
void
LSQUnit<Impl>::init(Params *params, unsigned maxLQEntries,
unsigned maxSQEntries, unsigned id)
{
DPRINTF(LSQUnit, "Creating LSQUnit%i object.\n",id);
switchedOut = false;
lsqID = id;
// Add 1 for the sentinel entry (they are circular queues).
LQEntries = maxLQEntries + 1;
SQEntries = maxSQEntries + 1;
loadQueue.resize(LQEntries);
storeQueue.resize(SQEntries);
loadHead = loadTail = 0;
storeHead = storeWBIdx = storeTail = 0;
usedPorts = 0;
cachePorts = params->cachePorts;
dcacheInterface = params->dcacheInterface;
memDepViolator = NULL;
blockedLoadSeqNum = 0;
}
template<class Impl>
std::string
LSQUnit<Impl>::name() const
{
if (Impl::MaxThreads == 1) {
return iewStage->name() + ".lsq";
} else {
return iewStage->name() + ".lsq.thread." + to_string(lsqID);
}
}
template<class Impl>
void
LSQUnit<Impl>::clearLQ()
{
loadQueue.clear();
}
template<class Impl>
void
LSQUnit<Impl>::clearSQ()
{
storeQueue.clear();
}
#if 0
template<class Impl>
void
LSQUnit<Impl>::setPageTable(PageTable *pt_ptr)
{
DPRINTF(LSQUnit, "Setting the page table pointer.\n");
pTable = pt_ptr;
}
#endif
template<class Impl>
void
LSQUnit<Impl>::switchOut()
{
switchedOut = true;
for (int i = 0; i < loadQueue.size(); ++i)
loadQueue[i] = NULL;
assert(storesToWB == 0);
while (storesToWB > 0 &&
storeWBIdx != storeTail &&
storeQueue[storeWBIdx].inst &&
storeQueue[storeWBIdx].canWB) {
if (storeQueue[storeWBIdx].size == 0 ||
storeQueue[storeWBIdx].inst->isDataPrefetch() ||
storeQueue[storeWBIdx].committed ||
storeQueue[storeWBIdx].req->flags & LOCKED) {
incrStIdx(storeWBIdx);
continue;
}
assert(storeQueue[storeWBIdx].req);
assert(!storeQueue[storeWBIdx].committed);
MemReqPtr req = storeQueue[storeWBIdx].req;
storeQueue[storeWBIdx].committed = true;
req->cmd = Write;
req->completionEvent = NULL;
req->time = curTick;
assert(!req->data);
req->data = new uint8_t[64];
memcpy(req->data, (uint8_t *)&storeQueue[storeWBIdx].data, req->size);
DPRINTF(LSQUnit, "D-Cache: Writing back store idx:%i PC:%#x "
"to Addr:%#x, data:%#x [sn:%lli]\n",
storeWBIdx,storeQueue[storeWBIdx].inst->readPC(),
req->paddr, *(req->data),
storeQueue[storeWBIdx].inst->seqNum);
switch(storeQueue[storeWBIdx].size) {
case 1:
cpu->write(req, (uint8_t &)storeQueue[storeWBIdx].data);
break;
case 2:
cpu->write(req, (uint16_t &)storeQueue[storeWBIdx].data);
break;
case 4:
cpu->write(req, (uint32_t &)storeQueue[storeWBIdx].data);
break;
case 8:
cpu->write(req, (uint64_t &)storeQueue[storeWBIdx].data);
break;
default:
panic("Unexpected store size!\n");
}
incrStIdx(storeWBIdx);
}
}
template<class Impl>
void
LSQUnit<Impl>::takeOverFrom()
{
switchedOut = false;
loads = stores = storesToWB = 0;
loadHead = loadTail = 0;
storeHead = storeWBIdx = storeTail = 0;
usedPorts = 0;
memDepViolator = NULL;
blockedLoadSeqNum = 0;
stalled = false;
isLoadBlocked = false;
loadBlockedHandled = false;
}
template<class Impl>
void
LSQUnit<Impl>::resizeLQ(unsigned size)
{
unsigned size_plus_sentinel = size + 1;
assert(size_plus_sentinel >= LQEntries);
if (size_plus_sentinel > LQEntries) {
while (size_plus_sentinel > loadQueue.size()) {
DynInstPtr dummy;
loadQueue.push_back(dummy);
LQEntries++;
}
} else {
LQEntries = size_plus_sentinel;
}
}
template<class Impl>
void
LSQUnit<Impl>::resizeSQ(unsigned size)
{
unsigned size_plus_sentinel = size + 1;
if (size_plus_sentinel > SQEntries) {
while (size_plus_sentinel > storeQueue.size()) {
SQEntry dummy;
storeQueue.push_back(dummy);
SQEntries++;
}
} else {
SQEntries = size_plus_sentinel;
}
}
template <class Impl>
void
LSQUnit<Impl>::insert(DynInstPtr &inst)
{
assert(inst->isMemRef());
assert(inst->isLoad() || inst->isStore());
if (inst->isLoad()) {
insertLoad(inst);
} else {
insertStore(inst);
}
inst->setInLSQ();
}
template <class Impl>
void
LSQUnit<Impl>::insertLoad(DynInstPtr &load_inst)
{
assert((loadTail + 1) % LQEntries != loadHead);
assert(loads < LQEntries);
DPRINTF(LSQUnit, "Inserting load PC %#x, idx:%i [sn:%lli]\n",
load_inst->readPC(), loadTail, load_inst->seqNum);
load_inst->lqIdx = loadTail;
if (stores == 0) {
load_inst->sqIdx = -1;
} else {
load_inst->sqIdx = storeTail;
}
loadQueue[loadTail] = load_inst;
incrLdIdx(loadTail);
++loads;
}
template <class Impl>
void
LSQUnit<Impl>::insertStore(DynInstPtr &store_inst)
{
// Make sure it is not full before inserting an instruction.
assert((storeTail + 1) % SQEntries != storeHead);
assert(stores < SQEntries);
DPRINTF(LSQUnit, "Inserting store PC %#x, idx:%i [sn:%lli]\n",
store_inst->readPC(), storeTail, store_inst->seqNum);
store_inst->sqIdx = storeTail;
store_inst->lqIdx = loadTail;
storeQueue[storeTail] = SQEntry(store_inst);
incrStIdx(storeTail);
++stores;
}
template <class Impl>
typename Impl::DynInstPtr
LSQUnit<Impl>::getMemDepViolator()
{
DynInstPtr temp = memDepViolator;
memDepViolator = NULL;
return temp;
}
template <class Impl>
unsigned
LSQUnit<Impl>::numFreeEntries()
{
unsigned free_lq_entries = LQEntries - loads;
unsigned free_sq_entries = SQEntries - stores;
// Both the LQ and SQ entries have an extra dummy entry to differentiate
// empty/full conditions. Subtract 1 from the free entries.
if (free_lq_entries < free_sq_entries) {
return free_lq_entries - 1;
} else {
return free_sq_entries - 1;
}
}
template <class Impl>
int
LSQUnit<Impl>::numLoadsReady()
{
int load_idx = loadHead;
int retval = 0;
while (load_idx != loadTail) {
assert(loadQueue[load_idx]);
if (loadQueue[load_idx]->readyToIssue()) {
++retval;
}
}
return retval;
}
template <class Impl>
Fault
LSQUnit<Impl>::executeLoad(DynInstPtr &inst)
{
// Execute a specific load.
Fault load_fault = NoFault;
DPRINTF(LSQUnit, "Executing load PC %#x, [sn:%lli]\n",
inst->readPC(),inst->seqNum);
// load_fault = inst->initiateAcc();
load_fault = inst->execute();
// If the instruction faulted, then we need to send it along to commit
// without the instruction completing.
if (load_fault != NoFault) {
// Send this instruction to commit, also make sure iew stage
// realizes there is activity.
iewStage->instToCommit(inst);
iewStage->activityThisCycle();
}
return load_fault;
}
template <class Impl>
Fault
LSQUnit<Impl>::executeStore(DynInstPtr &store_inst)
{
using namespace TheISA;
// Make sure that a store exists.
assert(stores != 0);
int store_idx = store_inst->sqIdx;
DPRINTF(LSQUnit, "Executing store PC %#x [sn:%lli]\n",
store_inst->readPC(), store_inst->seqNum);
// Check the recently completed loads to see if any match this store's
// address. If so, then we have a memory ordering violation.
int load_idx = store_inst->lqIdx;
Fault store_fault = store_inst->initiateAcc();
// Fault store_fault = store_inst->execute();
if (storeQueue[store_idx].size == 0) {
DPRINTF(LSQUnit,"Fault on Store PC %#x, [sn:%lli],Size = 0\n",
store_inst->readPC(),store_inst->seqNum);
return store_fault;
}
assert(store_fault == NoFault);
if (store_inst->isStoreConditional()) {
// Store conditionals need to set themselves as able to
// writeback if we haven't had a fault by here.
storeQueue[store_idx].canWB = true;
++storesToWB;
}
if (!memDepViolator) {
while (load_idx != loadTail) {
// Really only need to check loads that have actually executed
// It's safe to check all loads because effAddr is set to
// InvalAddr when the dyn inst is created.
// @todo: For now this is extra conservative, detecting a
// violation if the addresses match assuming all accesses
// are quad word accesses.
// @todo: Fix this, magic number being used here
if ((loadQueue[load_idx]->effAddr >> 8) ==
(store_inst->effAddr >> 8)) {
// A load incorrectly passed this store. Squash and refetch.
// For now return a fault to show that it was unsuccessful.
memDepViolator = loadQueue[load_idx];
return genMachineCheckFault();
}
incrLdIdx(load_idx);
}
// If we've reached this point, there was no violation.
memDepViolator = NULL;
}
return store_fault;
}
template <class Impl>
void
LSQUnit<Impl>::commitLoad()
{
assert(loadQueue[loadHead]);
DPRINTF(LSQUnit, "Committing head load instruction, PC %#x\n",
loadQueue[loadHead]->readPC());
loadQueue[loadHead] = NULL;
incrLdIdx(loadHead);
--loads;
}
template <class Impl>
void
LSQUnit<Impl>::commitLoads(InstSeqNum &youngest_inst)
{
assert(loads == 0 || loadQueue[loadHead]);
while (loads != 0 && loadQueue[loadHead]->seqNum <= youngest_inst) {
commitLoad();
}
}
template <class Impl>
void
LSQUnit<Impl>::commitStores(InstSeqNum &youngest_inst)
{
assert(stores == 0 || storeQueue[storeHead].inst);
int store_idx = storeHead;
while (store_idx != storeTail) {
assert(storeQueue[store_idx].inst);
// Mark any stores that are now committed and have not yet
// been marked as able to write back.
if (!storeQueue[store_idx].canWB) {
if (storeQueue[store_idx].inst->seqNum > youngest_inst) {
break;
}
DPRINTF(LSQUnit, "Marking store as able to write back, PC "
"%#x [sn:%lli]\n",
storeQueue[store_idx].inst->readPC(),
storeQueue[store_idx].inst->seqNum);
storeQueue[store_idx].canWB = true;
++storesToWB;
}
incrStIdx(store_idx);
}
}
template <class Impl>
void
LSQUnit<Impl>::writebackStores()
{
while (storesToWB > 0 &&
storeWBIdx != storeTail &&
storeQueue[storeWBIdx].inst &&
storeQueue[storeWBIdx].canWB &&
usedPorts < cachePorts) {
// Store didn't write any data so no need to write it back to
// memory.
if (storeQueue[storeWBIdx].size == 0) {
completeStore(storeWBIdx);
incrStIdx(storeWBIdx);
continue;
}
if (dcacheInterface && dcacheInterface->isBlocked()) {
DPRINTF(LSQUnit, "Unable to write back any more stores, cache"
" is blocked!\n");
break;
}
++usedPorts;
if (storeQueue[storeWBIdx].inst->isDataPrefetch()) {
incrStIdx(storeWBIdx);
continue;
}
assert(storeQueue[storeWBIdx].req);
assert(!storeQueue[storeWBIdx].committed);
MemReqPtr req = storeQueue[storeWBIdx].req;
storeQueue[storeWBIdx].committed = true;
req->cmd = Write;
req->completionEvent = NULL;
req->time = curTick;
assert(!req->data);
req->data = new uint8_t[64];
memcpy(req->data, (uint8_t *)&storeQueue[storeWBIdx].data, req->size);
DPRINTF(LSQUnit, "D-Cache: Writing back store idx:%i PC:%#x "
"to Addr:%#x, data:%#x [sn:%lli]\n",
storeWBIdx,storeQueue[storeWBIdx].inst->readPC(),
req->paddr, *(req->data),
storeQueue[storeWBIdx].inst->seqNum);
switch(storeQueue[storeWBIdx].size) {
case 1:
cpu->write(req, (uint8_t &)storeQueue[storeWBIdx].data);
break;
case 2:
cpu->write(req, (uint16_t &)storeQueue[storeWBIdx].data);
break;
case 4:
cpu->write(req, (uint32_t &)storeQueue[storeWBIdx].data);
break;
case 8:
cpu->write(req, (uint64_t &)storeQueue[storeWBIdx].data);
break;
default:
panic("Unexpected store size!\n");
}
// Stores other than store conditionals are completed at this
// time. Mark them as completed and, if we have a checker,
// tell it that the instruction is completed.
// @todo: Figure out what time I can say stores are complete in
// the timing memory.
if (!(req->flags & LOCKED)) {
storeQueue[storeWBIdx].inst->setCompleted();
if (cpu->checker) {
cpu->checker->tick(storeQueue[storeWBIdx].inst);
}
}
if (dcacheInterface) {
assert(!req->completionEvent);
StoreCompletionEvent *store_event = new
StoreCompletionEvent(storeWBIdx, NULL, this);
req->completionEvent = store_event;
MemAccessResult result = dcacheInterface->access(req);
if (isStalled() &&
storeQueue[storeWBIdx].inst->seqNum == stallingStoreIsn) {
DPRINTF(LSQUnit, "Unstalling, stalling store [sn:%lli] "
"load idx:%i\n",
stallingStoreIsn, stallingLoadIdx);
stalled = false;
stallingStoreIsn = 0;
iewStage->replayMemInst(loadQueue[stallingLoadIdx]);
}
typename IEW::LdWritebackEvent *wb = NULL;
if (req->flags & LOCKED) {
// Stx_C should not generate a system port transaction
// if it misses in the cache, but that might be hard
// to accomplish without explicit cache support.
wb = new typename
IEW::LdWritebackEvent(storeQueue[storeWBIdx].inst,
iewStage);
store_event->wbEvent = wb;
}
if (result != MA_HIT && dcacheInterface->doEvents()) {
DPRINTF(LSQUnit,"D-Cache Write Miss on idx:%i!\n",
storeWBIdx);
DPRINTF(Activity, "Active st accessing mem miss [sn:%lli]\n",
storeQueue[storeWBIdx].inst->seqNum);
//mshrSeqNums.push_back(storeQueue[storeWBIdx].inst->seqNum);
//DPRINTF(LSQUnit, "Added MSHR. count = %i\n",mshrSeqNums.size());
// @todo: Increment stat here.
} else {
DPRINTF(LSQUnit,"D-Cache: Write Hit on idx:%i !\n",
storeWBIdx);
DPRINTF(Activity, "Active st accessing mem hit [sn:%lli]\n",
storeQueue[storeWBIdx].inst->seqNum);
}
incrStIdx(storeWBIdx);
} else {
panic("Must HAVE DCACHE!!!!!\n");
}
}
// Not sure this should set it to 0.
usedPorts = 0;
assert(stores >= 0 && storesToWB >= 0);
}
/*template <class Impl>
void
LSQUnit<Impl>::removeMSHR(InstSeqNum seqNum)
{
list<InstSeqNum>::iterator mshr_it = find(mshrSeqNums.begin(),
mshrSeqNums.end(),
seqNum);
if (mshr_it != mshrSeqNums.end()) {
mshrSeqNums.erase(mshr_it);
DPRINTF(LSQUnit, "Removing MSHR. count = %i\n",mshrSeqNums.size());
}
}*/
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);
int load_idx = loadTail;
decrLdIdx(load_idx);
while (loads != 0 && loadQueue[load_idx]->seqNum > squashed_num) {
DPRINTF(LSQUnit,"Load Instruction PC %#x squashed, "
"[sn:%lli]\n",
loadQueue[load_idx]->readPC(),
loadQueue[load_idx]->seqNum);
if (isStalled() && load_idx == stallingLoadIdx) {
stalled = false;
stallingStoreIsn = 0;
stallingLoadIdx = 0;
}
// Clear the smart pointer to make sure it is decremented.
loadQueue[load_idx]->squashed = true;
loadQueue[load_idx] = NULL;
--loads;
// Inefficient!
loadTail = load_idx;
decrLdIdx(load_idx);
}
if (isLoadBlocked) {
if (squashed_num < blockedLoadSeqNum) {
isLoadBlocked = false;
loadBlockedHandled = false;
blockedLoadSeqNum = 0;
}
}
int store_idx = storeTail;
decrStIdx(store_idx);
while (stores != 0 &&
storeQueue[store_idx].inst->seqNum > squashed_num) {
// Instructions marked as can WB are already committed.
if (storeQueue[store_idx].canWB) {
break;
}
DPRINTF(LSQUnit,"Store Instruction PC %#x squashed, "
"idx:%i [sn:%lli]\n",
storeQueue[store_idx].inst->readPC(),
store_idx, storeQueue[store_idx].inst->seqNum);
// I don't think this can happen. It should have been cleared
// by the stalling load.
if (isStalled() &&
storeQueue[store_idx].inst->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[store_idx].inst->squashed = true;
storeQueue[store_idx].inst = NULL;
storeQueue[store_idx].canWB = 0;
if (storeQueue[store_idx].req) {
// There should not be a completion event if the store has
// not yet committed.
assert(!storeQueue[store_idx].req->completionEvent);
}
storeQueue[store_idx].req = NULL;
--stores;
// Inefficient!
storeTail = store_idx;
decrStIdx(store_idx);
}
}
template <class Impl>
void
LSQUnit<Impl>::completeStore(int store_idx)
{
assert(storeQueue[store_idx].inst);
storeQueue[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->activityThisCycle();
if (store_idx == storeHead) {
do {
incrStIdx(storeHead);
--stores;
} while (storeQueue[storeHead].completed &&
storeHead != storeTail);
iewStage->updateLSQNextCycle = true;
}
DPRINTF(LSQUnit, "Completing store [sn:%lli], idx:%i, store head "
"idx:%i\n",
storeQueue[store_idx].inst->seqNum, store_idx, storeHead);
if (isStalled() &&
storeQueue[store_idx].inst->seqNum == stallingStoreIsn) {
DPRINTF(LSQUnit, "Unstalling, stalling store [sn:%lli] "
"load idx:%i\n",
stallingStoreIsn, stallingLoadIdx);
stalled = false;
stallingStoreIsn = 0;
iewStage->replayMemInst(loadQueue[stallingLoadIdx]);
}
storeQueue[store_idx].inst->setCompleted();
// Tell the checker we've completed this instruction. Some stores
// may get reported twice to the checker, but the checker can
// handle that case.
if (cpu->checker) {
cpu->checker->tick(storeQueue[store_idx].inst);
}
}
template <class Impl>
inline void
LSQUnit<Impl>::incrStIdx(int &store_idx)
{
if (++store_idx >= SQEntries)
store_idx = 0;
}
template <class Impl>
inline void
LSQUnit<Impl>::decrStIdx(int &store_idx)
{
if (--store_idx < 0)
store_idx += SQEntries;
}
template <class Impl>
inline void
LSQUnit<Impl>::incrLdIdx(int &load_idx)
{
if (++load_idx >= LQEntries)
load_idx = 0;
}
template <class Impl>
inline void
LSQUnit<Impl>::decrLdIdx(int &load_idx)
{
if (--load_idx < 0)
load_idx += LQEntries;
}
template <class Impl>
void
LSQUnit<Impl>::dumpInsts()
{
cprintf("Load store queue: Dumping instructions.\n");
cprintf("Load queue size: %i\n", loads);
cprintf("Load queue: ");
int load_idx = loadHead;
while (load_idx != loadTail && loadQueue[load_idx]) {
cprintf("%#x ", loadQueue[load_idx]->readPC());
incrLdIdx(load_idx);
}
cprintf("Store queue size: %i\n", stores);
cprintf("Store queue: ");
int store_idx = storeHead;
while (store_idx != storeTail && storeQueue[store_idx].inst) {
cprintf("%#x ", storeQueue[store_idx].inst->readPC());
incrStIdx(store_idx);
}
cprintf("\n");
}