#include <multiperspective_perceptron_tage.hh>

Inheritance diagram for MultiperspectivePerceptronTAGE:

Classes
struct	MPPTAGEBranchInfo
	Branch information data type. More...

Public Member Functions
	MultiperspectivePerceptronTAGE (const MultiperspectivePerceptronTAGEParams *p)

void	init () override
	init() is called after all C++ SimObjects have been created and all ports are connected. More...

bool	lookup (ThreadID tid, Addr instPC, void *&bp_history) override
	Looks up a given PC in the BP to see if it is taken or not taken. More...

void	update (ThreadID tid, Addr instPC, bool taken, void *bp_history, bool squashed, const StaticInstPtr &inst, Addr corrTarget) override
	Updates the BP with taken/not taken information. More...

void	uncondBranch (ThreadID tid, Addr pc, void *&bp_history) override

void	squash (ThreadID tid, void *bp_history) override

Public Member Functions inherited from MultiperspectivePerceptron
	MultiperspectivePerceptron (const MultiperspectivePerceptronParams *params)

void	setExtraBits (int bits)
	Sets the starting number of storage bits to compute the number of table entries. More...

void	btbUpdate (ThreadID tid, Addr branch_addr, void *&bp_history) override
	If a branch is not taken, because the BTB address is invalid or missing, this function sets the appropriate counter in the global and local predictors to not taken. More...

Public Member Functions inherited from BPredUnit
	BPredUnit (const Params *p)

void	regProbePoints () override
	Register probe points for this object. More...

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

bool	predict (const StaticInstPtr &inst, const InstSeqNum &seqNum, TheISA::PCState &pc, ThreadID tid)
	Predicts whether or not the instruction is a taken branch, and the target of the branch if it is taken. More...

void	update (const InstSeqNum &done_sn, ThreadID tid)
	Tells the branch predictor to commit any updates until the given sequence number. More...

void	squash (const InstSeqNum &squashed_sn, ThreadID tid)
	Squashes all outstanding updates until a given sequence number. More...

void	squash (const InstSeqNum &squashed_sn, const TheISA::PCState &corr_target, bool actually_taken, ThreadID tid)
	Squashes all outstanding updates until a given sequence number, and corrects that sn's update with the proper address and taken/not taken. More...

bool	BTBValid (Addr instPC)
	Looks up a given PC in the BTB to see if a matching entry exists. More...

TheISA::PCState	BTBLookup (Addr instPC)
	Looks up a given PC in the BTB to get the predicted target. More...

void	BTBUpdate (Addr instPC, const TheISA::PCState &target)
	Updates the BTB with the target of a branch. More...

void	dump ()

Public Member Functions inherited from SimObject
const Params *	params () const

	SimObject (const Params *_params)

virtual	~SimObject ()

virtual const std::string	name () const

virtual void	loadState (CheckpointIn &cp)
	loadState() is called on each SimObject when restoring from a checkpoint. More...

virtual void	initState ()
	initState() is called on each SimObject when not restoring from a checkpoint. More...

virtual void	regProbeListeners ()
	Register probe listeners for this object. More...

ProbeManager *	getProbeManager ()
	Get the probe manager for this object. More...

virtual Port &	getPort (const std::string &if_name, PortID idx=InvalidPortID)
	Get a port with a given name and index. More...

virtual void	startup ()
	startup() is the final initialization call before simulation. More...

DrainState	drain () override
	Provide a default implementation of the drain interface for objects that don't need draining. More...

virtual void	memWriteback ()
	Write back dirty buffers to memory using functional writes. More...

virtual void	memInvalidate ()
	Invalidate the contents of memory buffers. More...

void	serialize (CheckpointOut &cp) const override
	Serialize an object. More...

void	unserialize (CheckpointIn &cp) override
	Unserialize an object. More...

Public Member Functions inherited from EventManager
EventQueue *	eventQueue () const

void	schedule (Event &event, Tick when)

void	deschedule (Event &event)

void	reschedule (Event &event, Tick when, bool always=false)

void	schedule (Event *event, Tick when)

void	deschedule (Event *event)

void	reschedule (Event *event, Tick when, bool always=false)

void	wakeupEventQueue (Tick when=(Tick) -1)
	This function is not needed by the usual gem5 event loop but may be necessary in derived EventQueues which host gem5 on other schedulers. More...

void	setCurTick (Tick newVal)

	EventManager (EventManager &em)
	Event manger manages events in the event queue. More...

	EventManager (EventManager *em)

	EventManager (EventQueue *eq)

Public Member Functions inherited from Serializable
	Serializable ()

virtual	~Serializable ()

void	serializeSection (CheckpointOut &cp, const char *name) const
	Serialize an object into a new section. More...

void	serializeSection (CheckpointOut &cp, const std::string &name) const

void	unserializeSection (CheckpointIn &cp, const char *name)
	Unserialize an a child object. More...

void	unserializeSection (CheckpointIn &cp, const std::string &name)

Public Member Functions inherited from Drainable
DrainState	drainState () const
	Return the current drain state of an object. More...

virtual void	notifyFork ()
	Notify a child process of a fork. More...

Public Member Functions inherited from Stats::Group
	Group (Group parent, const char name=nullptr)
	Construct a new statistics group. More...

virtual	~Group ()

virtual void	regStats ()
	Callback to set stat parameters. More...

virtual void	resetStats ()
	Callback to reset stats. More...

virtual void	preDumpStats ()
	Callback before stats are dumped. More...

void	addStat (Stats::Info *info)
	Register a stat with this group. More...

const std::map< std::string, Group * > &	getStatGroups () const
	Get all child groups associated with this object. More...

const std::vector< Info * > &	getStats () const
	Get all stats associated with this object. More...

void	addStatGroup (const char name, Group block)
	Add a stat block as a child of this block. More...

const Info *	resolveStat (std::string name) const
	Resolve a stat by its name within this group. More...

	Group ()=delete

	Group (const Group &)=delete

Group &	operator= (const Group &)=delete

Private Member Functions
unsigned int	getIndex (ThreadID tid, MPPTAGEBranchInfo &bi, const HistorySpec &spec, int index) const

int	computePartialSum (ThreadID tid, MPPTAGEBranchInfo &bi) const

void	updatePartial (ThreadID tid, MPPTAGEBranchInfo &bi, bool taken)

void	updateHistories (ThreadID tid, MPPTAGEBranchInfo &bi, bool taken)

Private Attributes
TAGEBase *	tage

LoopPredictor *	loopPredictor

StatisticalCorrector *	statisticalCorrector

Additional Inherited Members
Public Types inherited from BPredUnit
typedef BranchPredictorParams	Params

Public Types inherited from SimObject
typedef SimObjectParams	Params

Static Public Member Functions inherited from SimObject
static void	serializeAll (CheckpointOut &cp)
	Serialize all SimObjects in the system. More...

static SimObject *	find (const char *name)
	Find the SimObject with the given name and return a pointer to it. More...

Static Public Member Functions inherited from Serializable
static const std::string &	currentSection ()
	Gets the fully-qualified name of the active section. More...

static void	serializeAll (const std::string &cpt_dir)
	Serializes all the SimObjects. More...

static void	unserializeGlobals (CheckpointIn &cp)

Protected Member Functions inherited from MultiperspectivePerceptron
void	insertModhistSpec (int p1, int p2)
	Auxiliary function for MODHIST and GHISTMODPATH features. More...

void	insertModpathSpec (int p1, int p2)
	Auxiliary function for MODPATH and GHISTMODPATH features. More...

int	insert (std::vector< int > &v, int x)
	Auxiliary function used by insertModhistSpec and insertModpathSpec. More...

void	computeBits (int num_filter_entries, int nlocal_histories, int local_history_length, bool ignore_path_size)
	Computes the size in bits of the structures needed to keep track of the history and the predictor tables and assigns the sizes of those tables that did not had their size specified. More...

virtual void	createSpecs ()=0
	Creates the tables of the predictor. More...

unsigned int	getIndex (ThreadID tid, const MPPBranchInfo &bi, const HistorySpec &spec, int index) const
	Get the position index of a predictor table. More...

void	findBest (ThreadID tid, std::vector< int > &best_preds) const
	Finds the best subset of features to use in case of a low-confidence branch, returns the result as an ordered vector of the indices to the predictor tables. More...

int	computeOutput (ThreadID tid, MPPBranchInfo &bi)
	Computes the output of the predictor for a given branch and the resulting best value in case the prediction has low confidence. More...

void	train (ThreadID tid, MPPBranchInfo &bi, bool taken)
	Trains the branch predictor with the given branch and direction. More...

void	satIncDec (bool taken, bool &sign, int &c, int max_weight) const
	Auxiliary function to increase a table counter depending on the direction of the branch. More...

void	addSpec (HistorySpec *spec)
	Add a table spec to the prefetcher. More...

Protected Member Functions inherited from BPredUnit
ProbePoints::PMUUPtr	pmuProbePoint (const char *name)
	Helper method to instantiate probe points belonging to this object. More...

Protected Member Functions inherited from Drainable
	Drainable ()

virtual	~Drainable ()

virtual void	drainResume ()
	Resume execution after a successful drain. More...

void	signalDrainDone () const
	Signal that an object is drained. More...

Protected Attributes inherited from MultiperspectivePerceptron
const int	blockSize
	Predictor parameters. More...

const int	pcshift

const int	threshold

const int	bias0

const int	bias1

const int	biasmostly0

const int	biasmostly1

const int	nbest

const int	tunebits

const int	hshift

const unsigned long long int	imli_mask1

const unsigned long long int	imli_mask4

const unsigned long long int	recencypos_mask

const double	fudge

const int	n_sign_bits

const int	pcbit

const int	decay

const unsigned int	record_mask

const bool	hash_taken

const bool	tuneonly

const int	extra_rounds

const int	speed

const int	budgetbits

const bool	speculative_update

std::vector< ThreadData * >	threadData

std::vector< HistorySpec * >	specs
	Predictor tables. More...

std::vector< int >	table_sizes

bool	doing_local
	runtime values and data used to count the size in bits More...

bool	doing_recency

int	assoc

int	ghist_length

int	modghist_length

int	path_length

int	thresholdCounter

int	theta

int	extrabits

std::vector< int >	imli_counter_bits

std::vector< int >	modhist_indices

std::vector< int >	modhist_lengths

std::vector< int >	modpath_indices

std::vector< int >	modpath_lengths

std::vector< std::vector< int > >	blurrypath_bits

std::vector< std::vector< std::vector< bool > > >	acyclic_bits

Protected Attributes inherited from BPredUnit
const unsigned	instShiftAmt
	Number of bits to shift instructions by for predictor addresses. More...

ProbePoints::PMUUPtr	ppBranches
	Branches seen by the branch predictor. More...

ProbePoints::PMUUPtr	ppMisses
	Miss-predicted branches. More...

Protected Attributes inherited from SimObject
const SimObjectParams *	_params
	Cached copy of the object parameters. More...

Protected Attributes inherited from EventManager
EventQueue *	eventq
	A pointer to this object's event queue. More...

Static Protected Attributes inherited from MultiperspectivePerceptron
static int	xlat []
	Transfer function for 6-width tables. More...

static int	xlat4 []
	Transfer function for 5-width tables. More...

Detailed Description

Definition at line 182 of file multiperspective_perceptron_tage.hh.

Constructor & Destructor Documentation

◆ MultiperspectivePerceptronTAGE()

MultiperspectivePerceptronTAGE::MultiperspectivePerceptronTAGE ( const MultiperspectivePerceptronTAGEParams * p )

Definition at line 387 of file multiperspective_perceptron_tage.cc.

References fatal_if, TAGEBase::isSpeculativeUpdateEnabled(), and tage.

Member Function Documentation

◆ computePartialSum()

int MultiperspectivePerceptronTAGE::computePartialSum	(	ThreadID	tid,
		MPPTAGEBranchInfo &	bi
	)		const

private

Definition at line 435 of file multiperspective_perceptron_tage.cc.

References PowerISA::bi, getIndex(), ArmISA::i, MultiperspectivePerceptron::specs, and MultiperspectivePerceptron::threadData.

Referenced by lookup().

◆ getIndex()

unsigned int MultiperspectivePerceptronTAGE::getIndex	(	ThreadID	tid,
		MPPTAGEBranchInfo &	bi,
		const HistorySpec &	spec,
		int	index
	)		const

private

Definition at line 411 of file multiperspective_perceptron_tage.cc.

References PowerISA::bi, MipsISA::g, MultiperspectivePerceptron::HistorySpec::getHash(), MultiperspectivePerceptron::imli_mask1, MultiperspectivePerceptron::imli_mask4, MipsISA::index, MultiperspectivePerceptron::table_sizes, and MultiperspectivePerceptron::threadData.

Referenced by computePartialSum(), and updatePartial().

◆ init()

void MultiperspectivePerceptronTAGE::init ( )

overridevirtual

init() is called after all C++ SimObjects have been created and all ports are connected.

Initializations that are independent of unserialization but rely on a fully instantiated and connected SimObject graph should be done here.

Reimplemented from MultiperspectivePerceptron.

Definition at line 398 of file multiperspective_perceptron_tage.cc.

References LoopPredictor::getSizeInBits(), StatisticalCorrector::getSizeInBits(), TAGEBase::getSizeInBits(), TAGEBase::init(), MultiperspectivePerceptron::init(), loopPredictor, MultiperspectivePerceptron::setExtraBits(), statisticalCorrector, and tage.

◆ lookup()

bool MultiperspectivePerceptronTAGE::lookup	(	ThreadID	tid,
		Addr	instPC,
		void *&	bp_history
	)

overridevirtual

Looks up a given PC in the BP to see if it is taken or not taken.

Parameters

inst_PC	The PC to look up.
bp_history	Pointer that will be set to an object that has the branch predictor state associated with the lookup.

Returns: Whether the branch is taken or not taken.

Reimplemented from MultiperspectivePerceptron.

Definition at line 527 of file multiperspective_perceptron_tage.cc.

References PowerISA::bi, computePartialSum(), TAGEBase::getPathHist(), BPredUnit::instShiftAmt, TAGEBase::isHighConfidence(), LoopPredictor::loopPredict(), loopPredictor, MultiperspectivePerceptron::pcshift, StatisticalCorrector::scPredict(), statisticalCorrector, tage, and TAGEBase::tagePredict().

◆ squash()

void MultiperspectivePerceptronTAGE::squash	(	ThreadID	tid,
		void *	bp_history
	)

overridevirtual

Parameters

bp_history Pointer to the history object. The predictor will need to update any state and delete the object.

Reimplemented from MultiperspectivePerceptron.

Definition at line 690 of file multiperspective_perceptron_tage.cc.

References PowerISA::bi.

◆ uncondBranch()

void MultiperspectivePerceptronTAGE::uncondBranch	(	ThreadID	tid,
		Addr	pc,
		void *&	bp_history
	)

overridevirtual

Reimplemented from MultiperspectivePerceptron.

Definition at line 680 of file multiperspective_perceptron_tage.cc.

References PowerISA::bi, loopPredictor, MipsISA::pc, MultiperspectivePerceptron::pcshift, statisticalCorrector, and tage.

◆ update()

void MultiperspectivePerceptronTAGE::update	(	ThreadID	tid,
		Addr	instPC,
		bool	taken,
		void *	bp_history,
		bool	squashed,
		const StaticInstPtr &	inst,
		Addr	corrTarget
	)

overridevirtual

Updates the BP with taken/not taken information.

Parameters

inst_PC	The branch's PC that will be updated.
taken	Whether the branch was taken or not taken.
bp_history	Pointer to the branch predictor state that is associated with the branch lookup that is being updated.
squashed	Set to true when this function is called during a squash operation.
inst	Static instruction information
corrTarget	The resolved target of the branch (only needed for squashed branches)