Implements a local predictor that uses the PC to index into a table of counters. More...

#include <2bit_local.hh>

Inheritance diagram for LocalBP:

Public Member Functions
	LocalBP (const LocalBPParams *params)
	Default branch predictor constructor. More...

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

bool	lookup (ThreadID tid, Addr branch_addr, void *&bp_history)
	Looks up the given address in the branch predictor and returns a true/false value as to whether it is taken. More...

void	btbUpdate (ThreadID tid, Addr branch_addr, void *&bp_history)
	Updates the branch predictor to Not Taken if a BTB entry is invalid or not found. More...

void	update (ThreadID tid, Addr branch_addr, bool taken, void *bp_history, bool squashed)
	Updates the branch predictor with the actual result of a branch. More...

void	squash (ThreadID tid, void *bp_history)

void	reset ()

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

void	regStats () override
	Registers statistics. More...

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...

virtual unsigned	getGHR (ThreadID tid, void *bp_history) const

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

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	resetStats ()
	Reset statistics associated with this object. More...

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

ProbeManager *	getProbeManager ()
	Get the probe manager for this object. 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
	EventManager (EventManager &em)

	EventManager (EventManager *em)

	EventManager (EventQueue *eq)

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)

void	setCurTick (Tick newVal)

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...

Private Member Functions
bool	getPrediction (uint8_t &count)
	Returns the taken/not taken prediction given the value of the counter. More...

unsigned	getLocalIndex (Addr &PC)
	Calculates the local index based on the PC. More...

Private Attributes
std::vector< SatCounter >	localCtrs
	Array of counters that make up the local predictor. More...

unsigned	localPredictorSize
	Size of the local predictor. More...

unsigned	localPredictorSets
	Number of sets. More...

unsigned	localCtrBits
	Number of bits of the local predictor's counters. More...

unsigned	indexMask
	Mask to get index bits. More...

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 ()
	Get the fully-qualified name of the active section. More...

static void	serializeAll (const std::string &cpt_dir)

static void	unserializeGlobals (CheckpointIn &cp)

Static Public Attributes inherited from Serializable
static int	ckptCount = 0

static int	ckptMaxCount = 0

static int	ckptPrevCount = -1

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 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...

Detailed Description

Implements a local predictor that uses the PC to index into a table of counters.

Note that any time a pointer to the bp_history is given, it should be NULL using this predictor because it does not have any branch predictor state that needs to be recorded or updated; the update can be determined solely by the branch being taken or not taken.

Definition at line 61 of file 2bit_local.hh.

Constructor & Destructor Documentation

LocalBP::LocalBP ( const LocalBPParams * params )

Default branch predictor constructor.

Definition at line 38 of file 2bit_local.cc.

References DPRINTF, fatal, ArmISA::i, indexMask, BPredUnit::instShiftAmt, isPowerOf2(), localCtrBits, localCtrs, localPredictorSets, and localPredictorSize.

Member Function Documentation

void LocalBP::btbUpdate	(	ThreadID	tid,
		Addr	branch_addr,
		void *&	bp_history
	)

virtual

Updates the branch predictor to Not Taken if a BTB entry is invalid or not found.

Parameters

branch_addr	The address of the branch to look up.
bp_history	Pointer to any bp history state.

Returns: Whether or not the branch is taken.

Implements BPredUnit.

Definition at line 82 of file 2bit_local.cc.

unsigned LocalBP::getLocalIndex ( Addr & PC )

inlineprivate

Calculates the local index based on the PC.

Definition at line 157 of file 2bit_local.cc.

References indexMask, and BPredUnit::instShiftAmt.

Referenced by lookup(), and update().

bool LocalBP::getPrediction ( uint8_t & count )

inlineprivate

Returns the taken/not taken prediction given the value of the counter.

Parameters

count The value of the counter.

Returns: The prediction based on the counter value.

Definition at line 149 of file 2bit_local.cc.

References localCtrBits.

Referenced by lookup().

bool LocalBP::lookup	(	ThreadID	tid,
		Addr	branch_addr,
		void *&	bp_history
	)

virtual

Looks up the given address in the branch predictor and returns a true/false value as to whether it is taken.

Parameters

branch_addr	The address of the branch to look up.
bp_history	Pointer to any bp history state.

Returns: Whether or not the branch is taken.

Implements BPredUnit.

Definition at line 90 of file 2bit_local.cc.

References DPRINTF, getLocalIndex(), getPrediction(), and localCtrs.

void LocalBP::reset ( )

Definition at line 74 of file 2bit_local.cc.

References ArmISA::i, localCtrs, and localPredictorSets.

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

inlinevirtual

Parameters

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

Implements BPredUnit.

Definition at line 97 of file 2bit_local.hh.

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

virtual

Implements BPredUnit.

Definition at line 163 of file 2bit_local.cc.

void LocalBP::update	(	ThreadID	tid,
		Addr	branch_addr,
		bool	taken,
		void *	bp_history,
		bool	squashed
	)

virtual

Updates the branch predictor with the actual result of a branch.

Parameters

branch_addr	The address of the branch to update.
taken	Whether or not the branch was taken.

Implements BPredUnit.

Definition at line 121 of file 2bit_local.cc.

References DPRINTF, getLocalIndex(), and localCtrs.

Member Data Documentation

unsigned LocalBP::indexMask

private

Mask to get index bits.

Definition at line 127 of file 2bit_local.hh.

Referenced by getLocalIndex(), and LocalBP().

unsigned LocalBP::localCtrBits

private

Number of bits of the local predictor's counters.

Definition at line 124 of file 2bit_local.hh.

Referenced by getPrediction(), and LocalBP().

std::vector<SatCounter> LocalBP::localCtrs

private

Array of counters that make up the local predictor.

Definition at line 115 of file 2bit_local.hh.

Referenced by LocalBP(), lookup(), reset(), and update().

unsigned LocalBP::localPredictorSets

private

Number of sets.

Definition at line 121 of file 2bit_local.hh.

Referenced by LocalBP(), and reset().

unsigned LocalBP::localPredictorSize

private

Size of the local predictor.

Definition at line 118 of file 2bit_local.hh.

Referenced by LocalBP().

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

cpu/pred/2bit_local.hh
cpu/pred/2bit_local.cc

Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation