Commit handles single threaded and SMT commit. More...

#include <commit.hh>

Classes
struct	CommitStats

Public Types
enum	CommitStatus { Active , Inactive }
	Overall commit status. More...

enum	ThreadStatus { Running , Idle , ROBSquashing , TrapPending , FetchTrapPending , SquashAfterPending }
	Individual thread status. More...

Public Member Functions
	Commit (CPU *_cpu, const BaseO3CPUParams &params)
	Construct a Commit with the given parameters.

std::string	name () const
	Returns the name of the Commit.

void	regProbePoints ()
	Registers probes.

void	setThreads (std::vector< ThreadState * > &threads)
	Sets the list of threads.

void	setTimeBuffer (TimeBuffer< TimeStruct > *tb_ptr)
	Sets the main time buffer pointer, used for backwards communication.

void	setFetchQueue (TimeBuffer< FetchStruct > *fq_ptr)

void	setRenameQueue (TimeBuffer< RenameStruct > *rq_ptr)
	Sets the pointer to the queue coming from rename.

void	setIEWQueue (TimeBuffer< IEWStruct > *iq_ptr)
	Sets the pointer to the queue coming from IEW.

void	setIEWStage (IEW *iew_stage)
	Sets the pointer to the IEW stage.

void	setActiveThreads (std::list< ThreadID > *at_ptr)
	Sets pointer to list of active threads.

void	setRenameMap (UnifiedRenameMap::PerThreadUnifiedRenameMap &rm_ptr)
	Sets pointer to the commited state rename map.

void	setROB (ROB *rob_ptr)
	Sets pointer to the ROB.

void	startupStage ()
	Initializes stage by sending back the number of free entries.

void	clearStates (ThreadID tid)
	Clear all thread-specific states.

void	drain ()
	Initializes the draining of commit.

void	drainResume ()
	Resumes execution after draining.

void	drainSanityCheck () const
	Perform sanity checks after a drain.

bool	isDrained () const
	Has the stage drained?

void	takeOverFrom ()
	Takes over from another CPU's thread.

void	deactivateThread (ThreadID tid)
	Deschedules a thread from scheduling.

bool	executingHtmTransaction (ThreadID) const
	Is the CPU currently processing a HTM transaction?

void	resetHtmStartsStops (ThreadID)

void	tick ()
	Ticks the commit stage, which tries to commit instructions.

void	commit ()
	Handles any squashes that are sent from IEW, and adds instructions to the ROB and tries to commit instructions.

size_t	numROBFreeEntries (ThreadID tid)
	Returns the number of free ROB entries for a specific thread.

void	generateTrapEvent (ThreadID tid, Fault inst_fault)
	Generates an event to schedule a squash due to a trap.

void	generateTCEvent (ThreadID tid)
	Records that commit needs to initiate a squash due to an external state update through the TC.

const PCStateBase &	pcState (ThreadID tid)
	Reads the PC of a specific thread.

void	pcState (const PCStateBase &val, ThreadID tid)
	Sets the PC of a specific thread.

Public Attributes
IEW *	iewStage
	The pointer to the IEW stage.

ROB *	rob
	ROB interface.

Private Member Functions
void	processTrapEvent (ThreadID tid)
	Mark the thread as processing a trap.

void	updateStatus ()
	Updates the overall status of commit with the nextStatus, and tell the CPU if commit is active/inactive.

bool	changedROBEntries ()
	Returns if any of the threads have the number of ROB entries changed on this cycle.

void	squashAll (ThreadID tid)
	Squashes all in flight instructions.

void	squashFromTrap (ThreadID tid)
	Handles squashing due to a trap.

void	squashFromTC (ThreadID tid)
	Handles squashing due to an TC write.

void	squashFromSquashAfter (ThreadID tid)
	Handles a squash from a squashAfter() request.

void	squashAfter (ThreadID tid, const DynInstPtr &head_inst)
	Handle squashing from instruction with SquashAfter set.

void	handleInterrupt ()
	Handles processing an interrupt.

void	propagateInterrupt ()
	Get fetch redirecting so we can handle an interrupt.

void	commitInsts ()
	Commits as many instructions as possible.

bool	commitHead (const DynInstPtr &head_inst, unsigned inst_num)
	Tries to commit the head ROB instruction passed in.

void	getInsts ()
	Gets instructions from rename and inserts them into the ROB.

void	markCompletedInsts ()
	Marks completed instructions using information sent from IEW.

ThreadID	getCommittingThread ()
	Gets the thread to commit, based on the SMT policy.

ThreadID	roundRobin ()
	Returns the thread ID to use based on a round robin policy.

ThreadID	oldestReady ()
	Returns the thread ID to use based on an oldest instruction policy.

void	updateComInstStats (const DynInstPtr &inst)
	Updates commit stats based on this instruction.

Private Attributes
CommitStatus	_status
	Overall commit status.

CommitStatus	_nextStatus
	Next commit status, to be set at the end of the cycle.

ThreadStatus	commitStatus [MaxThreads]
	Per-thread status.

CommitPolicy	commitPolicy
	Commit policy used in SMT mode.

ProbePointArg< DynInstPtr > *	ppCommit
	Probe Points.

ProbePointArg< DynInstPtr > *	ppCommitStall

ProbePointArg< DynInstPtr > *	ppSquash
	To probe when an instruction is squashed.

TimeBuffer< TimeStruct > *	timeBuffer
	Time buffer interface.

TimeBuffer< TimeStruct >::wire	toIEW
	Wire to write information heading to previous stages.

TimeBuffer< TimeStruct >::wire	robInfoFromIEW
	Wire to read information from IEW (for ROB).

TimeBuffer< FetchStruct > *	fetchQueue

TimeBuffer< FetchStruct >::wire	fromFetch

TimeBuffer< IEWStruct > *	iewQueue
	IEW instruction queue interface.

TimeBuffer< IEWStruct >::wire	fromIEW
	Wire to read information from IEW queue.

TimeBuffer< RenameStruct > *	renameQueue
	Rename instruction queue interface, for ROB.

TimeBuffer< RenameStruct >::wire	fromRename
	Wire to read information from rename queue.

CPU *	cpu
	Pointer to O3CPU.

std::vector< ThreadState * >	thread
	Vector of all of the threads.

bool	wroteToTimeBuffer
	Records that commit has written to the time buffer this cycle.

bool	changedROBNumEntries [MaxThreads]
	Records if the number of ROB entries has changed this cycle.

bool	trapSquash [MaxThreads]
	Records if a thread has to squash this cycle due to a trap.

bool	tcSquash [MaxThreads]
	Records if a thread has to squash this cycle due to an XC write.

DynInstPtr	squashAfterInst [MaxThreads]
	Instruction passed to squashAfter().

std::list< ThreadID >	priority_list
	Priority List used for Commit Policy.

const Cycles	iewToCommitDelay
	IEW to Commit delay.

const Cycles	commitToIEWDelay
	Commit to IEW delay.

const Cycles	renameToROBDelay
	Rename to ROB delay.

const Cycles	fetchToCommitDelay

const unsigned	renameWidth
	Rename width, in instructions.

const unsigned	commitWidth
	Commit width, in instructions.

const ThreadID	numThreads
	Number of Active Threads.

bool	drainPending
	Is a drain pending? Commit is looking for an instruction boundary while there are no pending interrupts.

bool	drainImminent
	Is a drain imminent? Commit has found an instruction boundary while no interrupts were present or in flight.

const Cycles	trapLatency
	The latency to handle a trap.

Fault	interrupt
	The interrupt fault.

std::unique_ptr< PCStateBase >	pc [MaxThreads]
	The commit PC state of each thread.

InstSeqNum	youngestSeqNum [MaxThreads]
	The sequence number of the youngest valid instruction in the ROB.

InstSeqNum	lastCommitedSeqNum [MaxThreads]
	The sequence number of the last commited instruction.

bool	trapInFlight [MaxThreads]
	Records if there is a trap currently in flight.

bool	committedStores [MaxThreads]
	Records if there were any stores committed this cycle.

bool	checkEmptyROB [MaxThreads]
	Records if commit should check if the ROB is truly empty (see commit_impl.hh).

std::list< ThreadID > *	activeThreads
	Pointer to the list of active threads.

UnifiedRenameMap *	renameMap [MaxThreads]
	Rename map interface.

bool	canHandleInterrupts
	True if last committed microop can be followed by an interrupt.

bool	avoidQuiesceLiveLock
	Have we had an interrupt pending and then seen it de-asserted because of a masking change? In this case the variable is set and the next time interrupts are enabled and pending the pipeline will squash to avoid a possible livelock senario.

int	htmStarts [MaxThreads]

int	htmStops [MaxThreads]

gem5::o3::Commit::CommitStats	stats

Detailed Description

Commit handles single threaded and SMT commit.

Its width is specified by the parameters; each cycle it tries to commit that many instructions. The SMT policy decides which thread it tries to commit instructions from. Non- speculative instructions must reach the head of the ROB before they are ready to execute; once they reach the head, commit will broadcast the instruction's sequence number to the previous stages so that they can issue/ execute the instruction. Only one non-speculative instruction is handled per cycle. Commit is responsible for handling all back-end initiated redirects. It receives the redirect, and then broadcasts it to all stages, indicating the sequence number they should squash until, and any necessary branch misprediction information as well. It priortizes redirects by instruction's age, only broadcasting a redirect if it corresponds to an instruction that should currently be in the ROB. This is done by tracking the sequence number of the youngest instruction in the ROB, which gets updated to any squashing instruction's sequence number, and only broadcasting a redirect if it corresponds to an older instruction. Commit also supports multiple cycle squashing, to model a ROB that can only remove a certain number of instructions per cycle.

Definition at line 91 of file commit.hh.

Member Enumeration Documentation

◆ CommitStatus

enum gem5::o3::Commit::CommitStatus

Overall commit status.

Used to determine if the CPU can deschedule itself due to a lack of activity.

Enumerator
Active
Inactive

Definition at line 97 of file commit.hh.

◆ ThreadStatus

enum gem5::o3::Commit::ThreadStatus

Individual thread status.

Enumerator
Running
Idle
ROBSquashing
TrapPending
FetchTrapPending
SquashAfterPending

Definition at line 104 of file commit.hh.

Constructor & Destructor Documentation

◆ Commit()

gem5::o3::Commit::Commit	(	CPU *	_cpu,
		const BaseO3CPUParams &	params )

Construct a Commit with the given parameters.

Definition at line 84 of file commit.cc.

References _nextStatus, _status, Active, changedROBNumEntries, checkEmptyROB, commitPolicy, commitStatus, committedStores, commitWidth, fatal, htmStarts, htmStops, Idle, Inactive, interrupt, lastCommitedSeqNum, gem5::o3::MaxThreads, gem5::o3::MaxWidth, gem5::NoFault, numThreads, pc, priority_list, renameMap, squashAfterInst, tcSquash, trapInFlight, trapSquash, and youngestSeqNum.

Member Function Documentation

◆ changedROBEntries()

bool gem5::o3::Commit::changedROBEntries ( )

private

Returns if any of the threads have the number of ROB entries changed on this cycle.

Used to determine if the number of free ROB entries needs to be sent back to previous stages.

Definition at line 428 of file commit.cc.

References activeThreads, and changedROBNumEntries.

◆ clearStates()

void gem5::o3::Commit::clearStates ( ThreadID tid )

Clear all thread-specific states.

Definition at line 286 of file commit.cc.

References changedROBNumEntries, checkEmptyROB, commitStatus, committedStores, cpu, gem5::ThreadContext::getIsaPtr(), Idle, lastCommitedSeqNum, gem5::BaseISA::newPCState(), pc, squashAfterInst, gem5::o3::CPU::tcBase(), tcSquash, trapInFlight, and trapSquash.

Referenced by gem5::o3::CPU::removeThread().

◆ commit()

void gem5::o3::Commit::commit ( )

Handles any squashes that are sent from IEW, and adds instructions to the ROB and tries to commit instructions.

Definition at line 736 of file commit.cc.

References _nextStatus, Active, activeThreads, gem5::o3::Commit::CommitStats::branchMispredicts, changedROBNumEntries, checkEmptyROB, gem5::BaseCPU::checkInterrupts(), commitInsts(), commitStatus, committedStores, cpu, DPRINTF, gem5::o3::ROB::findInst(), fromIEW, gem5::FullSystem, getInsts(), gem5::o3::IEW::hasStoresToWB(), iewStage, gem5::PCStateBase::instAddr(), gem5::o3::ROB::isEmpty(), gem5::o3::CPU::isThreadExiting(), gem5::o3::ROB::numFreeEntries(), numThreads, pc, pcState(), propagateInterrupt(), rob, ROBSquashing, gem5::o3::CPU::scheduleThreadExitEvent(), gem5::ArmISA::set, gem5::o3::ROB::squash(), SquashAfterPending, squashFromSquashAfter(), squashFromTC(), squashFromTrap(), stats, tcSquash, toIEW, TrapPending, trapSquash, wroteToTimeBuffer, and youngestSeqNum.

Referenced by gem5::o3::Commit::CommitStats::CommitStats(), and tick().

◆ commitHead()

bool gem5::o3::Commit::commitHead	(	const DynInstPtr &	head_inst,
		unsigned	inst_num )

private

Tries to commit the head ROB instruction passed in.

Parameters

head_inst The instruction to be committed.

Definition at line 1098 of file commit.cc.

References gem5::o3::CPU::checker, gem5::o3::Commit::CommitStats::commitNonSpecStalls, commitStatus, committedStores, cpu, gem5::curTick(), DPRINTF, gem5::EXCEPTION, generateTrapEvent(), gem5::o3::IEW::hasStoresToWB(), gem5::ArmISA::i, iewStage, gem5::NoFault, gem5::nullStaticInstPtr, renameMap, gem5::o3::ROB::retireHead(), rob, gem5::o3::UnifiedRenameMap::setEntry(), gem5::o3::IEW::setLastRetiredHtmUid(), stats, thread, toIEW, gem5::o3::CPU::trap(), TrapPending, updateComInstStats(), and gem5::Checker< class >::verify().

Referenced by commitInsts().

◆ commitInsts()

void gem5::o3::Commit::commitInsts ( )

private

Commits as many instructions as possible.

Definition at line 897 of file commit.cc.

References avoidQuiesceLiveLock, canHandleInterrupts, changedROBNumEntries, gem5::o3::CPU::checker, gem5::BaseCPU::checkInterrupts(), gem5::BaseCPU::clearInterrupts(), gem5::o3::CPU::commitDrained(), gem5::o3::Commit::CommitStats::commitEligibleSamples, commitHead(), gem5::o3::Commit::CommitStats::commitSquashedInsts, gem5::BaseCPU::commitStats, gem5::o3::Commit::CommitStats::committedInstType, commitWidth, gem5::X86ISA::count, cpu, DPRINTF, drainImminent, drainPending, executingHtmTransaction(), getCommittingThread(), handleInterrupt(), htmStarts, htmStops, interrupt, gem5::o3::ROB::isHeadReady(), lastCommitedSeqNum, gem5::NoFault, gem5::o3::Commit::CommitStats::numCommittedDist, pc, ppCommit, ppSquash, gem5::o3::ROB::readHeadInst(), gem5::o3::ROB::retireHead(), rob, gem5::statistics::DistBase< Derived, Stor >::sample(), gem5::ArmISA::set, squashAfter(), stats, thread, toIEW, gem5::BaseCPU::traceFunctions(), and gem5::Checker< class >::verify().

Referenced by commit().

◆ deactivateThread()

void gem5::o3::Commit::deactivateThread ( ThreadID tid )

Deschedules a thread from scheduling.

Definition at line 367 of file commit.cc.

References priority_list.

Referenced by gem5::o3::CPU::deactivateThread().

◆ drain()

void gem5::o3::Commit::drain ( )

Initializes the draining of commit.

Definition at line 300 of file commit.cc.

References drainPending.

Referenced by gem5::o3::CPU::drain().

◆ drainResume()

void gem5::o3::Commit::drainResume ( )

Resumes execution after draining.

Definition at line 303 of file commit.cc.

References drainImminent, and drainPending.

Referenced by gem5::o3::CPU::drainResume().

◆ drainSanityCheck()

void gem5::o3::Commit::drainSanityCheck ( ) const

Perform sanity checks after a drain.

Definition at line 310 of file commit.cc.

References gem5::o3::ROB::drainSanityCheck(), executingHtmTransaction(), isDrained(), numThreads, panic, and rob.

Referenced by gem5::o3::CPU::drainSanityCheck().

◆ executingHtmTransaction()

bool gem5::o3::Commit::executingHtmTransaction ( ThreadID tid ) const

Is the CPU currently processing a HTM transaction?

Definition at line 378 of file commit.cc.

References htmStarts, htmStops, and gem5::InvalidThreadID.

Referenced by commitInsts(), gem5::o3::CPU::deactivateThread(), and drainSanityCheck().

◆ generateTCEvent()

void gem5::o3::Commit::generateTCEvent ( ThreadID tid )

Records that commit needs to initiate a squash due to an external state update through the TC.

Definition at line 476 of file commit.cc.

References DPRINTF, tcSquash, and trapInFlight.

Referenced by gem5::o3::CPU::squashFromTC().

◆ generateTrapEvent()

void gem5::o3::Commit::generateTrapEvent	(	ThreadID	tid,
		Fault	inst_fault )

Generates an event to schedule a squash due to a trap.

Definition at line 451 of file commit.cc.

References gem5::Clocked::clockEdge(), cpu, gem5::EventBase::CPU_Tick_Pri, DPRINTF, processTrapEvent(), gem5::EventManager::schedule(), gem5::BaseCPU::syscallRetryLatency, thread, trapInFlight, and trapLatency.

Referenced by commitHead(), and handleInterrupt().

◆ getCommittingThread()

ThreadID gem5::o3::Commit::getCommittingThread ( )

private

Gets the thread to commit, based on the SMT policy.

Definition at line 1403 of file commit.cc.

References activeThreads, commitPolicy, commitStatus, cpu, FetchTrapPending, Idle, gem5::InvalidThreadID, gem5::o3::ROB::isEmpty(), gem5::o3::ROB::isHeadReady(), gem5::o3::CPU::isThreadExiting(), numThreads, oldestReady(), gem5::o3::ROB::readHeadInst(), rob, roundRobin(), and Running.

Referenced by commitInsts().

◆ getInsts()

void gem5::o3::Commit::getInsts ( )

private

Gets instructions from rename and inserts them into the ROB.

Definition at line 1284 of file commit.cc.

References changedROBNumEntries, commitStatus, DPRINTF, fromRename, gem5::o3::ROB::getMaxEntries(), gem5::o3::ROB::getThreadEntries(), gem5::o3::ROB::insertInst(), renameWidth, rob, ROBSquashing, TrapPending, and youngestSeqNum.

Referenced by commit().

◆ handleInterrupt()

void gem5::o3::Commit::handleInterrupt ( )

private

Handles processing an interrupt.

Definition at line 659 of file commit.cc.

References avoidQuiesceLiveLock, canHandleInterrupts, gem5::o3::CPU::checker, gem5::BaseCPU::checkInterrupts(), commitStatus, cpu, DPRINTF, generateTrapEvent(), gem5::o3::CPU::getInterrupts(), gem5::Checker< class >::handlePendingInt(), gem5::o3::CPU::instList, interrupt, gem5::NoFault, gem5::o3::CPU::processInterrupts(), thread, toIEW, and TrapPending.

Referenced by commitInsts().

◆ isDrained()

bool gem5::o3::Commit::isDrained ( ) const

Has the stage drained?

Definition at line 325 of file commit.cc.

References interrupt, gem5::o3::ROB::isEmpty(), gem5::NoFault, numThreads, pc, and rob.

Referenced by drainSanityCheck(), and gem5::o3::CPU::isCpuDrained().

◆ markCompletedInsts()

void gem5::o3::Commit::markCompletedInsts ( )

private

Marks completed instructions using information sent from IEW.

Definition at line 1317 of file commit.cc.

References DPRINTF, fromIEW, and pcState().

Referenced by tick().

◆ name()

std::string gem5::o3::Commit::name ( ) const

Returns the name of the Commit.

Definition at line 135 of file commit.cc.

References cpu, and gem5::Named::name().

◆ numROBFreeEntries()

size_t gem5::o3::Commit::numROBFreeEntries ( ThreadID tid )

Returns the number of free ROB entries for a specific thread.

Definition at line 445 of file commit.cc.

References gem5::o3::ROB::numFreeEntries(), and rob.

Referenced by gem5::o3::Rename::clearStates(), and gem5::o3::Rename::resetStage().

◆ oldestReady()

ThreadID gem5::o3::Commit::oldestReady ( )

private

Returns the thread ID to use based on an oldest instruction policy.

Definition at line 1476 of file commit.cc.

References activeThreads, commitStatus, FetchTrapPending, Idle, gem5::InvalidThreadID, gem5::o3::ROB::isEmpty(), gem5::o3::ROB::isHeadReady(), gem5::o3::ROB::readHeadInst(), rob, and Running.

Referenced by getCommittingThread().

◆ pcState() [1/2]

void gem5::o3::Commit::pcState	(	const PCStateBase &	val,
		ThreadID	tid )

inline

Sets the PC of a specific thread.

Definition at line 312 of file commit.hh.

References pc, gem5::ArmISA::set, and gem5::X86ISA::val.

◆ pcState() [2/2]

const PCStateBase & gem5::o3::Commit::pcState ( ThreadID tid )

inline

Reads the PC of a specific thread.

Definition at line 309 of file commit.hh.

References pc.

Referenced by commit(), markCompletedInsts(), gem5::o3::CPU::pcState(), and gem5::o3::CPU::pcState().

◆ processTrapEvent()

void gem5::o3::Commit::processTrapEvent ( ThreadID tid )

private

Mark the thread as processing a trap.

Definition at line 77 of file commit.cc.

References trapSquash.

Referenced by generateTrapEvent().

◆ propagateInterrupt()

void gem5::o3::Commit::propagateInterrupt ( )

private

Get fetch redirecting so we can handle an interrupt.

Definition at line 712 of file commit.cc.

References commitStatus, cpu, drainImminent, gem5::o3::CPU::getInterrupts(), interrupt, gem5::NoFault, tcSquash, toIEW, TrapPending, and trapSquash.

Referenced by commit().

◆ regProbePoints()

void gem5::o3::Commit::regProbePoints ( )

Registers probes.

Definition at line 138 of file commit.cc.

References cpu, gem5::SimObject::getProbeManager(), ppCommit, ppCommitStall, and ppSquash.

Referenced by gem5::o3::CPU::regProbePoints().

◆ resetHtmStartsStops()

void gem5::o3::Commit::resetHtmStartsStops ( ThreadID tid )

Definition at line 387 of file commit.cc.

References htmStarts, htmStops, and gem5::InvalidThreadID.

Referenced by gem5::o3::CPU::htmSendAbortSignal().

◆ roundRobin()

ThreadID gem5::o3::Commit::roundRobin ( )

private

Returns the thread ID to use based on a round robin policy.

Definition at line 1449 of file commit.cc.

References commitStatus, FetchTrapPending, Idle, gem5::InvalidThreadID, gem5::o3::ROB::isHeadReady(), priority_list, rob, and Running.

Referenced by getCommittingThread().

◆ setActiveThreads()

void gem5::o3::Commit::setActiveThreads ( std::list< ThreadID > * at_ptr )

Sets pointer to list of active threads.

Definition at line 251 of file commit.cc.

References activeThreads.

◆ setFetchQueue()

void gem5::o3::Commit::setFetchQueue ( TimeBuffer< FetchStruct > * fq_ptr )

Definition at line 218 of file commit.cc.

References fetchQueue, fetchToCommitDelay, fromFetch, and gem5::TimeBuffer< T >::getWire().

◆ setIEWQueue()

void gem5::o3::Commit::setIEWQueue ( TimeBuffer< IEWStruct > * iq_ptr )

Sets the pointer to the queue coming from IEW.

Definition at line 236 of file commit.cc.

References fromIEW, gem5::TimeBuffer< T >::getWire(), iewQueue, and iewToCommitDelay.

◆ setIEWStage()

void gem5::o3::Commit::setIEWStage ( IEW * iew_stage )

Sets the pointer to the IEW stage.

Definition at line 245 of file commit.cc.

References iewStage.

◆ setRenameMap()

void gem5::o3::Commit::setRenameMap ( UnifiedRenameMap::PerThreadUnifiedRenameMap & rm_ptr )

Sets pointer to the commited state rename map.

Definition at line 257 of file commit.cc.

References numThreads, and renameMap.

◆ setRenameQueue()

void gem5::o3::Commit::setRenameQueue ( TimeBuffer< RenameStruct > * rq_ptr )

Sets the pointer to the queue coming from rename.

Definition at line 227 of file commit.cc.

References fromRename, gem5::TimeBuffer< T >::getWire(), renameQueue, and renameToROBDelay.

◆ setROB()

void gem5::o3::Commit::setROB ( ROB * rob_ptr )

Sets pointer to the ROB.

Definition at line 263 of file commit.cc.

References rob.

◆ setThreads()

void gem5::o3::Commit::setThreads ( std::vector< ThreadState * > & threads )

Sets the list of threads.

Definition at line 200 of file commit.cc.

References thread.

Referenced by gem5::o3::CPU::init().

◆ setTimeBuffer()

void gem5::o3::Commit::setTimeBuffer ( TimeBuffer< TimeStruct > * tb_ptr )

Sets the main time buffer pointer, used for backwards communication.

Definition at line 206 of file commit.cc.

References gem5::TimeBuffer< T >::getWire(), iewToCommitDelay, robInfoFromIEW, timeBuffer, and toIEW.

◆ squashAfter()

void gem5::o3::Commit::squashAfter	(	ThreadID	tid,
		const DynInstPtr &	head_inst )

private

Handle squashing from instruction with SquashAfter set.

This differs from the other squashes as it squashes following instructions instead of the current instruction and doesn't clean up various status bits about traps/tc writes pending. Since there might have been instructions committed by the commit stage before the squashing instruction was reached and we can't commit and squash in the same cycle, we have to squash in two steps:

Immediately set the commit status of the thread of SquashAfterPending. This forces the thread to stop committing instructions in this cycle. The last instruction to be committed in this cycle will be the SquashAfter instruction.
In the next cycle, commit() checks for the SquashAfterPending state and squashes all in-flight instructions. Since the SquashAfter instruction was the last instruction to be committed in the previous cycle, this causes all subsequent instructions to be squashed.

Parameters

tid	ID of the thread to squash.
head_inst	Instruction that requested the squash.

Definition at line 570 of file commit.cc.

References commitStatus, DPRINTF, squashAfterInst, and SquashAfterPending.

Referenced by commitInsts().

◆ squashAll()

void gem5::o3::Commit::squashAll ( ThreadID tid )

private

Squashes all in flight instructions.

Definition at line 485 of file commit.cc.

References changedROBNumEntries, gem5::o3::ROB::isEmpty(), lastCommitedSeqNum, pc, gem5::o3::ROB::readHeadInst(), rob, gem5::ArmISA::set, gem5::o3::ROB::squash(), toIEW, and youngestSeqNum.

Referenced by squashFromSquashAfter(), squashFromTC(), and squashFromTrap().

◆ squashFromSquashAfter()

void gem5::o3::Commit::squashFromSquashAfter ( ThreadID tid )

private

Handles a squash from a squashAfter() request.

Definition at line 553 of file commit.cc.

References gem5::o3::CPU::activityThisCycle(), commitStatus, cpu, DPRINTF, pc, ROBSquashing, squashAfterInst, squashAll(), and toIEW.

Referenced by commit().

◆ squashFromTC()

void gem5::o3::Commit::squashFromTC ( ThreadID tid )

private

Handles squashing due to an TC write.

Definition at line 537 of file commit.cc.

References gem5::o3::CPU::activityThisCycle(), commitStatus, cpu, DPRINTF, pc, ROBSquashing, squashAll(), tcSquash, and thread.

Referenced by commit().

◆ squashFromTrap()

void gem5::o3::Commit::squashFromTrap ( ThreadID tid )

private

Handles squashing due to a trap.

Definition at line 520 of file commit.cc.

References gem5::o3::CPU::activityThisCycle(), commitStatus, cpu, DPRINTF, pc, ROBSquashing, squashAll(), thread, trapInFlight, and trapSquash.

Referenced by commit().

◆ startupStage()

void gem5::o3::Commit::startupStage ( )

Initializes stage by sending back the number of free entries.

Definition at line 266 of file commit.cc.

References gem5::o3::CPU::activateStage(), activeThreads, gem5::o3::CPU::activityThisCycle(), gem5::o3::CPU::CommitIdx, cpu, gem5::o3::ROB::numFreeEntries(), numThreads, gem5::o3::ROB::resetEntries(), rob, gem5::o3::ROB::setActiveThreads(), and toIEW.

Referenced by gem5::o3::CPU::startup().

◆ takeOverFrom()

void gem5::o3::Commit::takeOverFrom ( )

Takes over from another CPU's thread.

Definition at line 352 of file commit.cc.

References _nextStatus, _status, Active, changedROBNumEntries, commitStatus, Idle, Inactive, numThreads, rob, squashAfterInst, gem5::o3::ROB::takeOverFrom(), tcSquash, and trapSquash.

Referenced by gem5::o3::CPU::takeOverFrom().

◆ tick()

void gem5::o3::Commit::tick ( )

Ticks the commit stage, which tries to commit instructions.

Definition at line 581 of file commit.cc.

References _nextStatus, Active, activeThreads, gem5::o3::CPU::activityThisCycle(), commit(), commitStatus, committedStores, gem5::o3::ROB::countInsts(), cpu, gem5::o3::ROB::doSquash(), DPRINTF, Inactive, gem5::o3::ROB::isDoneSquashing(), gem5::o3::ROB::isEmpty(), markCompletedInsts(), gem5::o3::ROB::numFreeEntries(), ppCommitStall, gem5::o3::ROB::readHeadInst(), rob, ROBSquashing, Running, toIEW, updateStatus(), and wroteToTimeBuffer.

Referenced by gem5::o3::CPU::tick().

◆ updateComInstStats()

void gem5::o3::Commit::updateComInstStats ( const DynInstPtr & inst )

private

Updates commit stats based on this instruction.

Definition at line 1337 of file commit.cc.

References gem5::BaseCPU::baseStats, gem5::BaseCPU::commitStats, cpu, gem5::o3::Commit::CommitStats::functionCalls, gem5::o3::CPU::instDone(), gem5::o3::Commit::CommitStats::membars, gem5::BaseCPU::BaseCPUStats::numInsts, and stats.

Referenced by commitHead().

◆ updateStatus()

void gem5::o3::Commit::updateStatus ( )

private

Updates the overall status of commit with the nextStatus, and tell the CPU if commit is active/inactive.

Definition at line 398 of file commit.cc.

References _nextStatus, _status, gem5::o3::CPU::activateStage(), Active, activeThreads, changedROBNumEntries, gem5::o3::CPU::CommitIdx, commitStatus, cpu, gem5::o3::CPU::deactivateStage(), DPRINTF, FetchTrapPending, Inactive, and TrapPending.

Referenced by tick().

Member Data Documentation

◆ _nextStatus

CommitStatus gem5::o3::Commit::_nextStatus

private

Next commit status, to be set at the end of the cycle.

Definition at line 118 of file commit.hh.

Referenced by Commit(), commit(), takeOverFrom(), tick(), and updateStatus().

◆ _status

CommitStatus gem5::o3::Commit::_status

private

Overall commit status.

Definition at line 116 of file commit.hh.

Referenced by Commit(), takeOverFrom(), and updateStatus().

◆ activeThreads

std::list<ThreadID>* gem5::o3::Commit::activeThreads

private

Pointer to the list of active threads.

Definition at line 443 of file commit.hh.

Referenced by changedROBEntries(), commit(), getCommittingThread(), oldestReady(), setActiveThreads(), startupStage(), tick(), and updateStatus().

◆ avoidQuiesceLiveLock

bool gem5::o3::Commit::avoidQuiesceLiveLock

private

Have we had an interrupt pending and then seen it de-asserted because of a masking change? In this case the variable is set and the next time interrupts are enabled and pending the pipeline will squash to avoid a possible livelock senario.

Definition at line 455 of file commit.hh.

Referenced by commitInsts(), and handleInterrupt().

◆ canHandleInterrupts

bool gem5::o3::Commit::canHandleInterrupts

private

True if last committed microop can be followed by an interrupt.

Definition at line 449 of file commit.hh.

Referenced by commitInsts(), and handleInterrupt().

◆ changedROBNumEntries

bool gem5::o3::Commit::changedROBNumEntries[MaxThreads]

private

Records if the number of ROB entries has changed this cycle.

If it has, then the number of free entries must be re-broadcast.

Definition at line 359 of file commit.hh.

Referenced by changedROBEntries(), clearStates(), Commit(), commit(), commitInsts(), getInsts(), squashAll(), takeOverFrom(), and updateStatus().

◆ checkEmptyROB

bool gem5::o3::Commit::checkEmptyROB[MaxThreads]

private

Records if commit should check if the ROB is truly empty (see commit_impl.hh).

Definition at line 440 of file commit.hh.

Referenced by clearStates(), Commit(), and commit().

◆ commitPolicy

CommitPolicy gem5::o3::Commit::commitPolicy

private

Commit policy used in SMT mode.

Definition at line 122 of file commit.hh.

Referenced by Commit(), and getCommittingThread().

◆ commitStatus

ThreadStatus gem5::o3::Commit::commitStatus[MaxThreads]

private

Per-thread status.

Definition at line 120 of file commit.hh.

Referenced by clearStates(), Commit(), commit(), commitHead(), getCommittingThread(), getInsts(), handleInterrupt(), oldestReady(), propagateInterrupt(), roundRobin(), squashAfter(), squashFromSquashAfter(), squashFromTC(), squashFromTrap(), takeOverFrom(), tick(), and updateStatus().

◆ committedStores

bool gem5::o3::Commit::committedStores[MaxThreads]

private

Records if there were any stores committed this cycle.

Definition at line 436 of file commit.hh.

Referenced by clearStates(), Commit(), commit(), commitHead(), and tick().

◆ commitToIEWDelay

const Cycles gem5::o3::Commit::commitToIEWDelay

private

Commit to IEW delay.

Definition at line 383 of file commit.hh.

◆ commitWidth

const unsigned gem5::o3::Commit::commitWidth

private

Commit width, in instructions.

Definition at line 396 of file commit.hh.

Referenced by Commit(), and commitInsts().

◆ cpu

CPU* gem5::o3::Commit::cpu

private

Pointer to O3CPU.

Definition at line 346 of file commit.hh.

Referenced by clearStates(), commit(), commitHead(), commitInsts(), gem5::o3::Commit::CommitStats::CommitStats(), generateTrapEvent(), getCommittingThread(), handleInterrupt(), name(), propagateInterrupt(), regProbePoints(), squashFromSquashAfter(), squashFromTC(), squashFromTrap(), startupStage(), tick(), updateComInstStats(), and updateStatus().

◆ drainImminent

bool gem5::o3::Commit::drainImminent

private

Is a drain imminent? Commit has found an instruction boundary while no interrupts were present or in flight.

This was the last architecturally committed instruction. Interrupts disabled and pipeline flushed. Waiting for structures to finish draining.

Definition at line 411 of file commit.hh.

Referenced by commitInsts(), drainResume(), and propagateInterrupt().

◆ drainPending

bool gem5::o3::Commit::drainPending

private

Is a drain pending? Commit is looking for an instruction boundary while there are no pending interrupts.

Definition at line 404 of file commit.hh.

Referenced by commitInsts(), drain(), and drainResume().

◆ fetchQueue

TimeBuffer<FetchStruct>* gem5::o3::Commit::fetchQueue

private

Definition at line 324 of file commit.hh.

Referenced by setFetchQueue().

◆ fetchToCommitDelay

const Cycles gem5::o3::Commit::fetchToCommitDelay

private

Definition at line 388 of file commit.hh.

Referenced by setFetchQueue().

◆ fromFetch

TimeBuffer<FetchStruct>::wire gem5::o3::Commit::fromFetch

private

Definition at line 326 of file commit.hh.

Referenced by setFetchQueue().

◆ fromIEW

TimeBuffer<IEWStruct>::wire gem5::o3::Commit::fromIEW

private

Wire to read information from IEW queue.

Definition at line 332 of file commit.hh.

Referenced by commit(), markCompletedInsts(), and setIEWQueue().

◆ fromRename

TimeBuffer<RenameStruct>::wire gem5::o3::Commit::fromRename

private

Wire to read information from rename queue.

Definition at line 338 of file commit.hh.

Referenced by getInsts(), and setRenameQueue().

◆ htmStarts

int gem5::o3::Commit::htmStarts[MaxThreads]

private

Definition at line 461 of file commit.hh.

Referenced by Commit(), commitInsts(), executingHtmTransaction(), and resetHtmStartsStops().

◆ htmStops

int gem5::o3::Commit::htmStops[MaxThreads]

private

Definition at line 462 of file commit.hh.

Referenced by Commit(), commitInsts(), executingHtmTransaction(), and resetHtmStartsStops().

◆ iewQueue

TimeBuffer<IEWStruct>* gem5::o3::Commit::iewQueue

private

IEW instruction queue interface.

Definition at line 329 of file commit.hh.

Referenced by setIEWQueue().

◆ iewStage

IEW* gem5::o3::Commit::iewStage

The pointer to the IEW stage.

Used solely to ensure that various events (traps, interrupts, syscalls) do not occur until all stores have written back.

Definition at line 164 of file commit.hh.

Referenced by commit(), commitHead(), and setIEWStage().

◆ iewToCommitDelay

const Cycles gem5::o3::Commit::iewToCommitDelay

private

IEW to Commit delay.

Definition at line 380 of file commit.hh.

Referenced by setIEWQueue(), and setTimeBuffer().

◆ interrupt

Fault gem5::o3::Commit::interrupt

private

The interrupt fault.

Definition at line 419 of file commit.hh.

Referenced by Commit(), commitInsts(), handleInterrupt(), isDrained(), and propagateInterrupt().

◆ lastCommitedSeqNum

InstSeqNum gem5::o3::Commit::lastCommitedSeqNum[MaxThreads]

private

The sequence number of the last commited instruction.

Definition at line 430 of file commit.hh.

Referenced by clearStates(), Commit(), commitInsts(), and squashAll().

◆ numThreads

const ThreadID gem5::o3::Commit::numThreads

private

Number of Active Threads.

Definition at line 399 of file commit.hh.

Referenced by Commit(), commit(), drainSanityCheck(), getCommittingThread(), isDrained(), setRenameMap(), startupStage(), and takeOverFrom().

◆ pc

std::unique_ptr<PCStateBase> gem5::o3::Commit::pc[MaxThreads]

private

The commit PC state of each thread.

Refers to the instruction that is currently being processed/committed.

Definition at line 424 of file commit.hh.

Referenced by clearStates(), Commit(), commit(), commitInsts(), isDrained(), pcState(), pcState(), squashAll(), squashFromSquashAfter(), squashFromTC(), and squashFromTrap().

◆ ppCommit

ProbePointArg<DynInstPtr>* gem5::o3::Commit::ppCommit

private

Probe Points.

Definition at line 125 of file commit.hh.

Referenced by commitInsts(), and regProbePoints().

◆ ppCommitStall

ProbePointArg<DynInstPtr>* gem5::o3::Commit::ppCommitStall

private

Definition at line 126 of file commit.hh.

Referenced by regProbePoints(), and tick().

◆ ppSquash

ProbePointArg<DynInstPtr>* gem5::o3::Commit::ppSquash

private

To probe when an instruction is squashed.

Definition at line 128 of file commit.hh.

Referenced by commitInsts(), and regProbePoints().

◆ priority_list

std::list<ThreadID> gem5::o3::Commit::priority_list

private

Priority List used for Commit Policy.

Definition at line 377 of file commit.hh.

Referenced by Commit(), deactivateThread(), and roundRobin().

◆ renameMap

UnifiedRenameMap* gem5::o3::Commit::renameMap[MaxThreads]

private

Rename map interface.

Definition at line 446 of file commit.hh.

Referenced by Commit(), commitHead(), and setRenameMap().

◆ renameQueue

TimeBuffer<RenameStruct>* gem5::o3::Commit::renameQueue

private

Rename instruction queue interface, for ROB.

Definition at line 335 of file commit.hh.

Referenced by setRenameQueue().

◆ renameToROBDelay

const Cycles gem5::o3::Commit::renameToROBDelay

private

Rename to ROB delay.

Definition at line 386 of file commit.hh.

Referenced by setRenameQueue().

◆ renameWidth

const unsigned gem5::o3::Commit::renameWidth

private

Rename width, in instructions.

Used so ROB knows how many instructions to get from the rename instruction queue.

Definition at line 393 of file commit.hh.

Referenced by getInsts().

◆ rob

ROB* gem5::o3::Commit::rob

ROB interface.

Definition at line 342 of file commit.hh.

Referenced by commit(), commitHead(), commitInsts(), drainSanityCheck(), getCommittingThread(), getInsts(), gem5::o3::CPU::insertThread(), isDrained(), numROBFreeEntries(), oldestReady(), gem5::o3::CPU::removeThread(), roundRobin(), setROB(), squashAll(), startupStage(), takeOverFrom(), and tick().

◆ robInfoFromIEW

TimeBuffer<TimeStruct>::wire gem5::o3::Commit::robInfoFromIEW

private

Wire to read information from IEW (for ROB).

Definition at line 322 of file commit.hh.

Referenced by setTimeBuffer().

◆ squashAfterInst

DynInstPtr gem5::o3::Commit::squashAfterInst[MaxThreads]

private

Instruction passed to squashAfter().

The squash after implementation needs to buffer the instruction that caused a squash since this needs to be passed to the fetch stage once squashing starts.

Definition at line 374 of file commit.hh.

Referenced by clearStates(), Commit(), squashAfter(), squashFromSquashAfter(), and takeOverFrom().

◆ stats

gem5::o3::Commit::CommitStats gem5::o3::Commit::stats

private

Referenced by commit(), commitHead(), commitInsts(), and updateComInstStats().

◆ tcSquash

bool gem5::o3::Commit::tcSquash[MaxThreads]

private

Records if a thread has to squash this cycle due to an XC write.

Definition at line 365 of file commit.hh.

Referenced by clearStates(), Commit(), commit(), generateTCEvent(), propagateInterrupt(), squashFromTC(), and takeOverFrom().

◆ thread

std::vector<ThreadState *> gem5::o3::Commit::thread

private

Vector of all of the threads.

Definition at line 349 of file commit.hh.

Referenced by commitHead(), commitInsts(), generateTrapEvent(), handleInterrupt(), setThreads(), squashFromTC(), and squashFromTrap().

◆ timeBuffer

TimeBuffer<TimeStruct>* gem5::o3::Commit::timeBuffer

private

Time buffer interface.

Definition at line 316 of file commit.hh.

Referenced by setTimeBuffer().

◆ toIEW

TimeBuffer<TimeStruct>::wire gem5::o3::Commit::toIEW

private

Wire to write information heading to previous stages.

Definition at line 319 of file commit.hh.

Referenced by commit(), commitHead(), commitInsts(), handleInterrupt(), propagateInterrupt(), setTimeBuffer(), squashAll(), squashFromSquashAfter(), startupStage(), and tick().

◆ trapInFlight

bool gem5::o3::Commit::trapInFlight[MaxThreads]

private

Records if there is a trap currently in flight.

Definition at line 433 of file commit.hh.

Referenced by clearStates(), Commit(), generateTCEvent(), generateTrapEvent(), and squashFromTrap().

◆ trapLatency

const Cycles gem5::o3::Commit::trapLatency

private

The latency to handle a trap.

Used when scheduling trap squash event.

Definition at line 416 of file commit.hh.

Referenced by generateTrapEvent().

◆ trapSquash

bool gem5::o3::Commit::trapSquash[MaxThreads]

private

Records if a thread has to squash this cycle due to a trap.

Definition at line 362 of file commit.hh.

Referenced by clearStates(), Commit(), commit(), processTrapEvent(), propagateInterrupt(), squashFromTrap(), and takeOverFrom().

◆ wroteToTimeBuffer

bool gem5::o3::Commit::wroteToTimeBuffer

private

Records that commit has written to the time buffer this cycle.

Used for the CPU to determine if it can deschedule itself if there is no activity.

Definition at line 354 of file commit.hh.

Referenced by commit(), and tick().

◆ youngestSeqNum

InstSeqNum gem5::o3::Commit::youngestSeqNum[MaxThreads]

private

The sequence number of the youngest valid instruction in the ROB.

Definition at line 427 of file commit.hh.

Referenced by Commit(), commit(), getInsts(), and squashAll().

The documentation for this class was generated from the following files:

cpu/o3/commit.hh
cpu/o3/commit.cc

Classes

Public Types

Public Member Functions

Public Attributes

Private Member Functions

Private Attributes

Detailed Description

Member Enumeration Documentation

◆ CommitStatus

◆ ThreadStatus

Constructor & Destructor Documentation

◆ Commit()

Member Function Documentation

◆ changedROBEntries()

◆ clearStates()

◆ commit()

◆ commitHead()

◆ commitInsts()

◆ deactivateThread()

◆ drain()

◆ drainResume()

◆ drainSanityCheck()

◆ executingHtmTransaction()

◆ generateTCEvent()

◆ generateTrapEvent()

◆ getCommittingThread()

◆ getInsts()

◆ handleInterrupt()

◆ isDrained()

◆ markCompletedInsts()

◆ name()

◆ numROBFreeEntries()

◆ oldestReady()

◆ pcState() [1/2]

◆ pcState() [2/2]

◆ processTrapEvent()

◆ propagateInterrupt()

◆ regProbePoints()

◆ resetHtmStartsStops()

◆ roundRobin()

◆ setActiveThreads()

◆ setFetchQueue()

◆ setIEWQueue()

◆ setIEWStage()

◆ setRenameMap()

◆ setRenameQueue()

◆ setROB()

◆ setThreads()

◆ setTimeBuffer()

◆ squashAfter()

◆ squashAll()

◆ squashFromSquashAfter()

◆ squashFromTC()

◆ squashFromTrap()

◆ startupStage()

◆ takeOverFrom()

◆ tick()

◆ updateComInstStats()

◆ updateStatus()

Member Data Documentation

◆ _nextStatus

◆ _status

◆ activeThreads

◆ avoidQuiesceLiveLock

◆ canHandleInterrupts

◆ changedROBNumEntries

◆ checkEmptyROB

◆ commitPolicy

◆ commitStatus

◆ committedStores

◆ commitToIEWDelay

◆ commitWidth

◆ cpu

◆ drainImminent

◆ drainPending

◆ fetchQueue

◆ fetchToCommitDelay

◆ fromFetch

◆ fromIEW

◆ fromRename