TAGEBase Class Reference

#include <tage_base.hh>

Inheritance diagram for TAGEBase:

Classes
struct	BranchInfo
struct	FoldedHistory
struct	TageEntry
struct	ThreadHistory

Public Types
enum	{   BIMODAL_ONLY = 0, TAGE_LONGEST_MATCH, BIMODAL_ALT_MATCH, TAGE_ALT_MATCH,   LAST_TAGE_PROVIDER_TYPE = TAGE_ALT_MATCH }
Public Types inherited from SimObject
typedef SimObjectParams	Params

Public Member Functions
	TAGEBase (const TAGEBaseParams *p)
void	regStats () override
	Callback to set stat parameters. More...
void	init () override
	init() is called after all C++ SimObjects have been created and all ports are connected. More...
virtual BranchInfo *	makeBranchInfo ()
virtual int	bindex (Addr pc_in) const
	Computes the index used to access the bimodal table. More...
virtual int	gindex (ThreadID tid, Addr pc, int bank) const
	Computes the index used to access a partially tagged table. More...
virtual int	F (int phist, int size, int bank) const
	Utility function to shuffle the path history depending on which tagged table we are accessing. More...
virtual uint16_t	gtag (ThreadID tid, Addr pc, int bank) const
	Computes the partial tag of a tagged table. More...
virtual bool	getBimodePred (Addr pc, BranchInfo *bi) const
	Get a branch prediction from the bimodal predictor. More...
void	baseUpdate (Addr pc, bool taken, BranchInfo *bi)
	Updates the bimodal predictor. More...
void	updateGHist (uint8_t *&h, bool dir, uint8_t *tab, int &PT)
	(Speculatively) updates the global branch history. More...
void	update (ThreadID tid, Addr branch_pc, bool taken, BranchInfo *bi)
	Update TAGE. More...
virtual void	updateHistories (ThreadID tid, Addr branch_pc, bool taken, BranchInfo *b, bool speculative, const StaticInstPtr &inst=StaticInst::nullStaticInstPtr, Addr target=MaxAddr)
	(Speculatively) updates global histories (path and direction). More...
virtual void	squash (ThreadID tid, bool taken, BranchInfo *bi, Addr target)
	Restores speculatively updated path and direction histories. More...
virtual void	condBranchUpdate (ThreadID tid, Addr branch_pc, bool taken, BranchInfo *bi, int nrand, Addr corrTarget, bool pred, bool preAdjustAlloc=false)
	Update TAGE for conditional branches. More...
bool	tagePredict (ThreadID tid, Addr branch_pc, bool cond_branch, BranchInfo *bi)
	TAGE prediction called from TAGE::predict. More...
virtual void	updateStats (bool taken, BranchInfo *bi)
	Update the stats. More...
virtual void	buildTageTables ()
	Instantiates the TAGE table entries. More...
virtual void	calculateParameters ()
	Calculates the history lengths and some other paramters in derived classes. More...
virtual void	calculateIndicesAndTags (ThreadID tid, Addr branch_pc, BranchInfo *bi)
	On a prediction, calculates the TAGE indices and tags for all the different history lengths. More...
virtual unsigned	getUseAltIdx (BranchInfo *bi, Addr branch_pc)
	Calculation of the index for useAltPredForNewlyAllocated On this base TAGE implementation it is always 0. More...
virtual void	adjustAlloc (bool &alloc, bool taken, bool pred_taken)
	Extra calculation to tell whether TAGE allocaitons may happen or not on an update For this base TAGE implementation it does nothing. More...
virtual void	handleAllocAndUReset (bool alloc, bool taken, BranchInfo *bi, int nrand)
	Handles Allocation and U bits reset on an update. More...
virtual void	handleUReset ()
	Handles the U bits reset. More...
virtual void	handleTAGEUpdate (Addr branch_pc, bool taken, BranchInfo *bi)
	Handles the update of the TAGE entries. More...
virtual void	resetUctr (uint8_t &u)
	Algorithm for resetting a single U counter. More...
virtual void	extraAltCalc (BranchInfo *bi)
	Extra steps for calculating altTaken For this base TAGE class it does nothing. More...
virtual bool	isHighConfidence (BranchInfo *bi) const
void	btbUpdate (ThreadID tid, Addr branch_addr, BranchInfo *&bi)
unsigned	getGHR (ThreadID tid, BranchInfo *bi) const
int8_t	getCtr (int hitBank, int hitBankIndex) const
unsigned	getTageCtrBits () const
int	getPathHist (ThreadID tid) const
bool	isSpeculativeUpdateEnabled () const
size_t	getSizeInBits () const
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	regProbePoints ()
	Register probe points for this object. 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
	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...
Public Member Functions inherited from Stats::Group
	Group ()=delete
	Group (const Group &)=delete
Group &	operator= (const Group &)=delete
	Group (Group *parent, const char *name=nullptr)
	Construct a new statistics group. More...
virtual	~Group ()
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...

Static Public Member Functions
template<typename T >
static void	ctrUpdate (T &ctr, bool taken, int nbits)
	Updates a direction counter based on the actual branch outcome. More...
static void	unsignedCtrUpdate (uint8_t &ctr, bool up, unsigned nbits)
	Updates an unsigned counter based on up/down parameter. More...
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)

Protected Member Functions
virtual void	initFoldedHistories (ThreadHistory &history)
	Initialization of the folded histories. 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
const unsigned	logRatioBiModalHystEntries
const unsigned	nHistoryTables
const unsigned	tagTableCounterBits
const unsigned	tagTableUBits
const unsigned	histBufferSize
const unsigned	minHist
const unsigned	maxHist
const unsigned	pathHistBits
std::vector< unsigned >	tagTableTagWidths
std::vector< int >	logTagTableSizes
std::vector< bool >	btablePrediction
std::vector< bool >	btableHysteresis
TageEntry **	gtable
std::vector< ThreadHistory >	threadHistory
int *	histLengths
int *	tableIndices
int *	tableTags
std::vector< int8_t >	useAltPredForNewlyAllocated
int64_t	tCounter
uint64_t	logUResetPeriod
const int64_t	initialTCounterValue
unsigned	numUseAltOnNa
unsigned	useAltOnNaBits
unsigned	maxNumAlloc
std::vector< bool >	noSkip
const bool	speculativeHistUpdate
const unsigned	instShiftAmt
bool	initialized
Stats::Scalar	tageLongestMatchProviderCorrect
Stats::Scalar	tageAltMatchProviderCorrect
Stats::Scalar	bimodalAltMatchProviderCorrect
Stats::Scalar	tageBimodalProviderCorrect
Stats::Scalar	tageLongestMatchProviderWrong
Stats::Scalar	tageAltMatchProviderWrong
Stats::Scalar	bimodalAltMatchProviderWrong
Stats::Scalar	tageBimodalProviderWrong
Stats::Scalar	tageAltMatchProviderWouldHaveHit
Stats::Scalar	tageLongestMatchProviderWouldHaveHit
Stats::Vector	tageLongestMatchProvider
Stats::Vector	tageAltMatchProvider
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...

Additional Inherited Members
Static Public Attributes inherited from Serializable
static int	ckptCount = 0
static int	ckptMaxCount = 0
static int	ckptPrevCount = -1

Detailed Description

Definition at line 61 of file tage_base.hh.

Member Enumeration Documentation

anonymous enum

anonymous enum

Enumerator
BIMODAL_ONLY
TAGE_LONGEST_MATCH
BIMODAL_ALT_MATCH
TAGE_ALT_MATCH
LAST_TAGE_PROVIDER_TYPE

Definition at line 115 of file tage_base.hh.

Constructor & Destructor Documentation

TAGEBase()

TAGEBase::TAGEBase

(

const TAGEBaseParams *

p

)

Definition at line 48 of file tage_base.cc.

References nHistoryTables, and noSkip.

Referenced by getSizeInBits().

Member Function Documentation

adjustAlloc()

void TAGEBase::adjustAlloc ( bool &  alloc, bool  taken, bool  pred_taken  )

virtual

Extra calculation to tell whether TAGE allocaitons may happen or not on an update For this base TAGE implementation it does nothing.

Reimplemented in TAGE_SC_L_TAGE, and MPP_TAGE.

Definition at line 433 of file tage_base.cc.

Referenced by condBranchUpdate(), and TAGEBase::BranchInfo::~BranchInfo().

baseUpdate()

void TAGEBase::baseUpdate	(	Addr	pc,
		bool	taken,
		BranchInfo *	bi
	)

Updates the bimodal predictor.

Parameters

pc	The unshifted branch PC.
taken	The actual branch outcome.
bi	Pointer to information on the prediction recorded at prediction time.

Definition at line 297 of file tage_base.cc.

References TAGEBase::BranchInfo::bimodalIndex, btableHysteresis, btablePrediction, DPRINTF, and logRatioBiModalHystEntries.

Referenced by MPP_TAGE::handleTAGEUpdate(), handleTAGEUpdate(), and TAGEBase::BranchInfo::~BranchInfo().

bindex()

int TAGEBase::bindex ( Addr  pc_in ) const

virtual

Computes the index used to access the bimodal table.

Parameters

pc_in

The unshifted branch PC.

Reimplemented in TAGE_SC_L_TAGE, and MPP_TAGE.

Definition at line 202 of file tage_base.cc.

References instShiftAmt, logTagTableSizes, and ULL.

Referenced by tagePredict(), and TAGEBase::BranchInfo::~BranchInfo().

btbUpdate()

void TAGEBase::btbUpdate	(	ThreadID	tid,
		Addr	branch_addr,
		BranchInfo *&	bi
	)

Definition at line 183 of file tage_base.cc.

References TAGEBase::BranchInfo::ci, TAGEBase::FoldedHistory::comp, TAGEBase::ThreadHistory::computeIndices, TAGEBase::ThreadHistory::computeTags, TAGEBase::BranchInfo::ct0, TAGEBase::BranchInfo::ct1, DPRINTF, TAGEBase::ThreadHistory::gHist, TAGEBase::ThreadHistory::globalHistory, ArmISA::i, nHistoryTables, TAGEBase::ThreadHistory::ptGhist, speculativeHistUpdate, threadHistory, and TAGEBase::FoldedHistory::update().

Referenced by TAGE::btbUpdate(), and isHighConfidence().

buildTageTables()

void TAGEBase::buildTageTables ( )

virtual

Instantiates the TAGE table entries.

Reimplemented in TAGE_SC_L_TAGE.

Definition at line 161 of file tage_base.cc.

References gtable, ArmISA::i, logTagTableSizes, and nHistoryTables.

Referenced by init(), and TAGEBase::BranchInfo::~BranchInfo().

calculateIndicesAndTags()

void TAGEBase::calculateIndicesAndTags ( ThreadID  tid, Addr  branch_pc, BranchInfo *  bi  )

virtual

On a prediction, calculates the TAGE indices and tags for all the different history lengths.

Reimplemented in TAGE_SC_L_TAGE.

Definition at line 335 of file tage_base.cc.

References gindex(), gtag(), ArmISA::i, nHistoryTables, TAGEBase::BranchInfo::tableIndices, tableIndices, TAGEBase::BranchInfo::tableTags, and tableTags.

Referenced by tagePredict(), and TAGEBase::BranchInfo::~BranchInfo().

calculateParameters()

void TAGEBase::calculateParameters ( )

virtual

Calculates the history lengths and some other paramters in derived classes.

Reimplemented in TAGE_SC_L_TAGE, and MPP_TAGE.

Definition at line 169 of file tage_base.cc.

References histLengths, ArmISA::i, maxHist, minHist, and nHistoryTables.

Referenced by init(), and TAGEBase::BranchInfo::~BranchInfo().

condBranchUpdate()

void TAGEBase::condBranchUpdate ( ThreadID  tid, Addr  branch_pc, bool  taken, BranchInfo *  bi, int  nrand, Addr  corrTarget, bool  pred, bool  preAdjustAlloc = false  )

virtual

Update TAGE for conditional branches.

Parameters

branch_pc	The unshifted branch PC.
taken	Actual branch outcome.
bi	Pointer to information on the prediction recorded at prediction time. Random int number from 0 to 3
corrTarget	The correct branch target
pred	Final prediction for this branch
preAdjustAlloc	call adjustAlloc before checking pseudo newly allocated entries

Definition at line 509 of file tage_base.cc.

References adjustAlloc(), TAGEBase::BranchInfo::altTaken, ctrUpdate(), getUseAltIdx(), handleAllocAndUReset(), handleTAGEUpdate(), TAGEBase::BranchInfo::hitBank, TAGEBase::BranchInfo::longestMatchPred, nHistoryTables, TAGEBase::BranchInfo::pseudoNewAlloc, TAGEBase::BranchInfo::tagePred, useAltOnNaBits, and useAltPredForNewlyAllocated.

Referenced by LTAGE::update(), TAGE::update(), TAGE_SC_L::update(), MultiperspectivePerceptronTAGE::update(), MPP_StatisticalCorrector::BranchInfo::~BranchInfo(), and TAGEBase::BranchInfo::~BranchInfo().

ctrUpdate()

template<typename T >

template void TAGEBase::ctrUpdate ( T &  ctr, bool  taken, int  nbits  )

static

Updates a direction counter based on the actual branch outcome.

Parameters

ctr	Reference to counter to update.
taken	Actual branch outcome.
nbits	Counter width.

Definition at line 256 of file tage_base.cc.

Referenced by condBranchUpdate(), MPP_TAGE::handleTAGEUpdate(), handleTAGEUpdate(), and TAGEBase::BranchInfo::~BranchInfo().

extraAltCalc()

void TAGEBase::extraAltCalc ( BranchInfo *  bi )

virtual

Extra steps for calculating altTaken For this base TAGE class it does nothing.

Reimplemented in TAGE_SC_L_TAGE.

Definition at line 650 of file tage_base.cc.

Referenced by tagePredict(), and TAGEBase::BranchInfo::~BranchInfo().

F()

int TAGEBase::F ( int  phist, int  size, int  bank  ) const

virtual

Utility function to shuffle the path history depending on which tagged table we are accessing.

Parameters

phist	The path history.
size	Number of path history bits to use.
bank	The partially tagged table to access.

Reimplemented in TAGE_SC_L_TAGE.

Definition at line 208 of file tage_base.cc.

References logTagTableSizes, and ULL.

Referenced by gindex(), and TAGEBase::BranchInfo::~BranchInfo().

getBimodePred()

bool TAGEBase::getBimodePred ( Addr  pc, BranchInfo *  bi  ) const

virtual

Get a branch prediction from the bimodal predictor.

Parameters

pc	The unshifted branch PC.
bi	Pointer to information on the prediction.

Reimplemented in TAGE_SC_L_TAGE.

Definition at line 288 of file tage_base.cc.

References TAGEBase::BranchInfo::bimodalIndex, and btablePrediction.

Referenced by TAGE_SC_L_TAGE::getBimodePred(), tagePredict(), and TAGEBase::BranchInfo::~BranchInfo().

getCtr()

int8_t TAGEBase::getCtr	(	int	hitBank,
		int	hitBankIndex
	)		const

Definition at line 783 of file tage_base.cc.

References TAGEBase::TageEntry::ctr, and gtable.

Referenced by isHighConfidence(), and TAGE_SC_L::predict().

getGHR()

unsigned TAGEBase::getGHR	(	ThreadID	tid,
		BranchInfo *	bi
	)		const

Definition at line 704 of file tage_base.cc.

References histBufferSize, ArmISA::i, TAGEBase::BranchInfo::ptGhist, threadHistory, and X86ISA::val.

Referenced by isHighConfidence().

getPathHist()

int TAGEBase::getPathHist

(

ThreadID

tid

)

const

Definition at line 795 of file tage_base.cc.

References threadHistory.

Referenced by isHighConfidence(), MultiperspectivePerceptronTAGE::lookup(), TAGE_SC_L::predict(), TAGE_SC_L::update(), and MultiperspectivePerceptronTAGE::update().

getSizeInBits()

size_t TAGEBase::getSizeInBits

(

)

const

Definition at line 807 of file tage_base.cc.

References bits(), histLengths, ArmISA::i, logRatioBiModalHystEntries, logTagTableSizes, logUResetPeriod, nHistoryTables, numUseAltOnNa, pathHistBits, TAGEBase(), tagTableCounterBits, tagTableTagWidths, tagTableUBits, ULL, and useAltOnNaBits.

Referenced by MultiperspectivePerceptronTAGE::init(), and isHighConfidence().

getTageCtrBits()

unsigned TAGEBase::getTageCtrBits

(

)

const

Definition at line 789 of file tage_base.cc.

References tagTableCounterBits.

Referenced by isHighConfidence(), and TAGE_SC_L::predict().

getUseAltIdx()

unsigned TAGEBase::getUseAltIdx ( BranchInfo *  bi, Addr  branch_pc  )

virtual

Calculation of the index for useAltPredForNewlyAllocated On this base TAGE implementation it is always 0.

Reimplemented in TAGE_SC_L_TAGE, and MPP_TAGE.

Definition at line 348 of file tage_base.cc.

Referenced by condBranchUpdate(), tagePredict(), and TAGEBase::BranchInfo::~BranchInfo().

gindex()

int TAGEBase::gindex ( ThreadID  tid, Addr  pc, int  bank  ) const

virtual

Computes the index used to access a partially tagged table.

Parameters

tid	The thread ID used to select the global histories to use.
pc	The unshifted branch PC.
bank	The partially tagged table to access.

Reimplemented in TAGE_SC_L_TAGE.

Definition at line 225 of file tage_base.cc.

References F(), histLengths, MipsISA::index, instShiftAmt, logTagTableSizes, pathHistBits, threadHistory, and ULL.

Referenced by calculateIndicesAndTags(), and TAGEBase::BranchInfo::~BranchInfo().

gtag()

uint16_t TAGEBase::gtag ( ThreadID  tid, Addr  pc, int  bank  ) const

virtual

Computes the partial tag of a tagged table.

Parameters

tid	the thread ID used to select the global histories to use.
pc	The unshifted branch PC.
bank	The partially tagged table to access.

Reimplemented in TAGE_SC_L_TAGE, TAGE_SC_L_TAGE_64KB, and TAGE_SC_L_TAGE_8KB.

Definition at line 243 of file tage_base.cc.

References instShiftAmt, tagTableTagWidths, threadHistory, and ULL.

Referenced by calculateIndicesAndTags(), and TAGEBase::BranchInfo::~BranchInfo().

handleAllocAndUReset()

void TAGEBase::handleAllocAndUReset ( bool  alloc, bool  taken, BranchInfo *  bi, int  nrand  )

virtual

Handles Allocation and U bits reset on an update.

Reimplemented in TAGE_SC_L_TAGE, MPP_TAGE, TAGE_SC_L_TAGE_64KB, and TAGE_SC_L_TAGE_8KB.

Definition at line 439 of file tage_base.cc.

References TAGEBase::TageEntry::ctr, gtable, handleUReset(), TAGEBase::BranchInfo::hitBank, ArmISA::i, maxNumAlloc, nHistoryTables, TAGEBase::BranchInfo::tableIndices, TAGEBase::BranchInfo::tableTags, TAGEBase::TageEntry::tag, tCounter, TAGEBase::TageEntry::u, ULL, and X86ISA::X.

Referenced by condBranchUpdate(), and TAGEBase::BranchInfo::~BranchInfo().

handleTAGEUpdate()

void TAGEBase::handleTAGEUpdate ( Addr  branch_pc, bool  taken, BranchInfo *  bi  )

virtual

Handles the update of the TAGE entries.

Reimplemented in TAGE_SC_L_TAGE, MPP_TAGE, TAGE_SC_L_TAGE_64KB, and TAGE_SC_L_TAGE_8KB.

Definition at line 550 of file tage_base.cc.

References TAGEBase::BranchInfo::altBank, TAGEBase::BranchInfo::altBankIndex, TAGEBase::BranchInfo::altTaken, baseUpdate(), TAGEBase::TageEntry::ctr, ctrUpdate(), DPRINTF, gtable, TAGEBase::BranchInfo::hitBank, TAGEBase::BranchInfo::hitBankIndex, TAGEBase::BranchInfo::tagePred, tagTableCounterBits, tagTableUBits, TAGEBase::TageEntry::u, and unsignedCtrUpdate().

Referenced by condBranchUpdate(), and TAGEBase::BranchInfo::~BranchInfo().

handleUReset()

void TAGEBase::handleUReset ( )

virtual

Handles the U bits reset.

Reimplemented in TAGE_SC_L_TAGE, and MPP_TAGE.

Definition at line 488 of file tage_base.cc.

References gtable, ArmISA::i, ArmISA::j, logTagTableSizes, logUResetPeriod, nHistoryTables, resetUctr(), tCounter, ArmISA::u, and ULL.

Referenced by handleAllocAndUReset(), and TAGEBase::BranchInfo::~BranchInfo().

init()

void TAGEBase::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 SimObject.

Definition at line 83 of file tage_base.cc.

References btableHysteresis, btablePrediction, buildTageTables(), calculateParameters(), gtable, histBufferSize, histLengths, initFoldedHistories(), initialized, initialTCounterValue, logRatioBiModalHystEntries, logTagTableSizes, logUResetPeriod, maxHist, nHistoryTables, numUseAltOnNa, pathHistBits, tableIndices, tableTags, tagTableTagWidths, tagTableUBits, tCounter, threadHistory, ULL, and useAltPredForNewlyAllocated.

Referenced by MultiperspectivePerceptronTAGE::init(), and MultiperspectivePerceptronTAGE::MPPTAGEBranchInfo::~MPPTAGEBranchInfo().

initFoldedHistories()

void TAGEBase::initFoldedHistories ( ThreadHistory &  history )

protectedvirtual

Initialization of the folded histories.

Reimplemented in TAGE_SC_L_TAGE_8KB.

Definition at line 146 of file tage_base.cc.

References TAGEBase::ThreadHistory::computeIndices, TAGEBase::ThreadHistory::computeTags, DPRINTF, histLengths, ArmISA::i, TAGEBase::FoldedHistory::init(), logTagTableSizes, nHistoryTables, TAGEBase::FoldedHistory::origLength, and tagTableTagWidths.

Referenced by init().

isHighConfidence()

virtual bool TAGEBase::isHighConfidence ( BranchInfo *  bi ) const

inlinevirtual

Reimplemented in MPP_TAGE.

Definition at line 406 of file tage_base.hh.

References btbUpdate(), getCtr(), getGHR(), getPathHist(), getSizeInBits(), getTageCtrBits(), and isSpeculativeUpdateEnabled().

Referenced by MultiperspectivePerceptronTAGE::lookup().

isSpeculativeUpdateEnabled()

bool TAGEBase::isSpeculativeUpdateEnabled

(

)

const

Definition at line 801 of file tage_base.cc.

References speculativeHistUpdate.

Referenced by isHighConfidence(), MultiperspectivePerceptronTAGE::MultiperspectivePerceptronTAGE(), LTAGE::update(), TAGE_SC_L::update(), and MultiperspectivePerceptronTAGE::update().

makeBranchInfo()

TAGEBase::BranchInfo * TAGEBase::makeBranchInfo ( )

virtual

Reimplemented in TAGE_SC_L_TAGE.

Definition at line 78 of file tage_base.cc.

Referenced by TAGEBase::BranchInfo::~BranchInfo().

regStats()

void TAGEBase::regStats ( )

overridevirtual

Callback to set stat parameters.

This callback is typically used for complex stats (e.g., distributions) that need parameters in addition to a name and a description. Stat names and descriptions should typically be set from the constructor usingo from the constructor using the ADD_STAT macro.

Reimplemented from Stats::Group.

Definition at line 719 of file tage_base.cc.

References bimodalAltMatchProviderCorrect, bimodalAltMatchProviderWrong, Stats::DataWrap< Derived, InfoProxyType >::desc(), Stats::VectorBase< Derived, Stor >::init(), SimObject::name(), Stats::DataWrap< Derived, InfoProxyType >::name(), nHistoryTables, tageAltMatchProvider, tageAltMatchProviderCorrect, tageAltMatchProviderWouldHaveHit, tageAltMatchProviderWrong, tageBimodalProviderCorrect, tageBimodalProviderWrong, tageLongestMatchProvider, tageLongestMatchProviderCorrect, tageLongestMatchProviderWouldHaveHit, and tageLongestMatchProviderWrong.

resetUctr()

void TAGEBase::resetUctr ( uint8_t &  u )

virtual

Algorithm for resetting a single U counter.

Reimplemented in MPP_TAGE, and TAGE_SC_L_TAGE_8KB.

Definition at line 503 of file tage_base.cc.

Referenced by handleUReset(), and TAGEBase::BranchInfo::~BranchInfo().

squash()

void TAGEBase::squash ( ThreadID  tid, bool  taken, TAGEBase::BranchInfo *  bi, Addr  target  )

virtual

Restores speculatively updated path and direction histories.

Also recomputes compressed (folded) histories based on the correct branch outcome. This version of squash() is called once on a branch misprediction.

Parameters

tid	The Thread ID to select the histories to rollback.
taken	The correct branch outcome.
bp_history	Wrapping pointer to BranchInfo (to allow storing derived class prediction information in the base class).
target	The correct branch target

Postcondition

bp_history points to valid memory.

Reimplemented in TAGE_SC_L_TAGE.

Definition at line 624 of file tage_base.cc.

References TAGEBase::BranchInfo::branchPC, TAGEBase::BranchInfo::ci, TAGEBase::FoldedHistory::comp, TAGEBase::ThreadHistory::computeIndices, TAGEBase::ThreadHistory::computeTags, TAGEBase::BranchInfo::ct0, TAGEBase::BranchInfo::ct1, DPRINTF, TAGEBase::ThreadHistory::gHist, TAGEBase::ThreadHistory::globalHistory, ArmISA::i, nHistoryTables, TAGEBase::BranchInfo::pathHist, TAGEBase::ThreadHistory::pathHist, TAGEBase::BranchInfo::ptGhist, TAGEBase::ThreadHistory::ptGhist, speculativeHistUpdate, threadHistory, and TAGEBase::FoldedHistory::update().

Referenced by LTAGE::update(), TAGE::update(), TAGE_SC_L::update(), MultiperspectivePerceptronTAGE::update(), TAGEBase::BranchInfo::~BranchInfo(), and MultiperspectivePerceptronTAGE::MPPTAGEBranchInfo::~MPPTAGEBranchInfo().

tagePredict()

bool TAGEBase::tagePredict	(	ThreadID	tid,
		Addr	branch_pc,
		bool	cond_branch,
		BranchInfo *	bi
	)

TAGE prediction called from TAGE::predict.

Parameters

tid	The thread ID to select the global histories to use.
branch_pc	The unshifted branch PC.
cond_branch	True if the branch is conditional.
bi	Pointer to the BranchInfo

Definition at line 355 of file tage_base.cc.

References TAGEBase::BranchInfo::altBank, TAGEBase::BranchInfo::altBankIndex, TAGEBase::BranchInfo::altTaken, BIMODAL_ALT_MATCH, BIMODAL_ONLY, TAGEBase::BranchInfo::bimodalIndex, bindex(), TAGEBase::BranchInfo::branchPC, calculateIndicesAndTags(), TAGEBase::BranchInfo::condBranch, TAGEBase::TageEntry::ctr, DPRINTF, extraAltCalc(), getBimodePred(), getUseAltIdx(), gtable, TAGEBase::BranchInfo::hitBank, TAGEBase::BranchInfo::hitBankIndex, ArmISA::i, TAGEBase::BranchInfo::longestMatchPred, nHistoryTables, noSkip, MipsISA::pc, TAGEBase::BranchInfo::provider, TAGEBase::BranchInfo::pseudoNewAlloc, tableIndices, tableTags, TAGE_ALT_MATCH, TAGE_LONGEST_MATCH, TAGEBase::BranchInfo::tagePred, and useAltPredForNewlyAllocated.

Referenced by MultiperspectivePerceptronTAGE::lookup(), TAGE::predict(), LTAGE::predict(), TAGE_SC_L::predict(), and TAGEBase::BranchInfo::~BranchInfo().

unsignedCtrUpdate()

void TAGEBase::unsignedCtrUpdate ( uint8_t &  ctr, bool  up, unsigned  nbits  )

static

Updates an unsigned counter based on up/down parameter.

Parameters

ctr	Reference to counter to update.
up	Boolean indicating if the counter is incremented/decremented If true it is incremented, if false it is decremented
nbits	Counter width.

Definition at line 274 of file tage_base.cc.

Referenced by handleTAGEUpdate(), and TAGEBase::BranchInfo::~BranchInfo().

update()

void TAGEBase::update	(	ThreadID	tid,
		Addr	branch_pc,
		bool	taken,
		BranchInfo *	bi
	)

Update TAGE.

Called at execute to repair histories on a misprediction and at commit to update the tables.

Parameters

tid	The thread ID to select the global histories to use.
branch_pc	The unshifted branch PC.
taken	Actual branch outcome.
bi	Pointer to information on the prediction recorded at prediction time.

Referenced by TAGEBase::BranchInfo::~BranchInfo(), and MultiperspectivePerceptronTAGE::MPPTAGEBranchInfo::~MPPTAGEBranchInfo().

updateGHist()

void TAGEBase::updateGHist	(	uint8_t *&	h,
		bool	dir,
		uint8_t *	tab,
		int &	PT
	)

(Speculatively) updates the global branch history.

Parameters

h	Reference to pointer to global branch history.
dir	(Predicted) outcome to update the histories with.
tab
PT	Reference to path history.

Definition at line 317 of file tage_base.cc.

References DPRINTF, histBufferSize, ArmISA::i, and maxHist.

Referenced by updateHistories(), MPP_TAGE::updatePathAndGlobalHistory(), and TAGEBase::BranchInfo::~BranchInfo().

updateHistories()

void TAGEBase::updateHistories ( ThreadID  tid, Addr  branch_pc, bool  taken, BranchInfo *  b, bool  speculative, const StaticInstPtr &  inst = StaticInst::nullStaticInstPtr, Addr  target = MaxAddr  )

virtual

(Speculatively) updates global histories (path and direction).

Also recomputes compressed (folded) histories based on the branch direction.

Parameters

tid	The thread ID to select the histories to update.
branch_pc	The unshifted branch PC.
taken	(Predicted) branch direction.
b	Wrapping pointer to BranchInfo (to allow storing derived class prediction information in the base class).

Reimplemented in TAGE_SC_L_TAGE, and MPP_TAGE.

Definition at line 583 of file tage_base.cc.

References TAGEBase::BranchInfo::ci, TAGEBase::FoldedHistory::comp, TAGEBase::ThreadHistory::computeIndices, TAGEBase::ThreadHistory::computeTags, TAGEBase::BranchInfo::ct0, TAGEBase::BranchInfo::ct1, DPRINTF, TAGEBase::ThreadHistory::gHist, TAGEBase::ThreadHistory::globalHistory, ArmISA::i, instShiftAmt, nHistoryTables, TAGEBase::BranchInfo::pathHist, TAGEBase::ThreadHistory::pathHist, pathHistBits, TAGEBase::BranchInfo::ptGhist, TAGEBase::ThreadHistory::ptGhist, speculativeHistUpdate, threadHistory, ULL, TAGEBase::FoldedHistory::update(), and updateGHist().

Referenced by TAGE::lookup(), TAGE::uncondBranch(), LTAGE::update(), TAGE::update(), TAGE_SC_L::update(), MultiperspectivePerceptronTAGE::update(), and TAGEBase::BranchInfo::~BranchInfo().

updateStats()

void TAGEBase::updateStats ( bool  taken, BranchInfo *  bi  )

virtual

Update the stats.

Parameters

taken	Actual branch outcome
bi	Pointer to information on the prediction recorded at prediction time.

Definition at line 657 of file tage_base.cc.

References TAGEBase::BranchInfo::altBank, TAGEBase::BranchInfo::altTaken, BIMODAL_ALT_MATCH, BIMODAL_ONLY, bimodalAltMatchProviderCorrect, bimodalAltMatchProviderWrong, TAGEBase::BranchInfo::hitBank, TAGEBase::BranchInfo::longestMatchPred, TAGEBase::BranchInfo::provider, TAGE_ALT_MATCH, TAGE_LONGEST_MATCH, tageAltMatchProvider, tageAltMatchProviderCorrect, tageAltMatchProviderWouldHaveHit, tageAltMatchProviderWrong, tageBimodalProviderCorrect, tageBimodalProviderWrong, tageLongestMatchProvider, tageLongestMatchProviderCorrect, tageLongestMatchProviderWouldHaveHit, tageLongestMatchProviderWrong, and TAGEBase::BranchInfo::tagePred.

Referenced by LTAGE::update(), TAGE::update(), TAGE_SC_L::update(), MultiperspectivePerceptronTAGE::update(), and TAGEBase::BranchInfo::~BranchInfo().

Member Data Documentation

bimodalAltMatchProviderCorrect

Stats::Scalar TAGEBase::bimodalAltMatchProviderCorrect

protected

Definition at line 492 of file tage_base.hh.

Referenced by regStats(), and updateStats().

bimodalAltMatchProviderWrong

Stats::Scalar TAGEBase::bimodalAltMatchProviderWrong

protected

Definition at line 496 of file tage_base.hh.

Referenced by regStats(), and updateStats().

btableHysteresis

std::vector<bool> TAGEBase::btableHysteresis

protected

Definition at line 433 of file tage_base.hh.

Referenced by baseUpdate(), init(), and MPP_TAGE::isHighConfidence().

btablePrediction

std::vector<bool> TAGEBase::btablePrediction

protected

Definition at line 432 of file tage_base.hh.

Referenced by baseUpdate(), getBimodePred(), init(), and MPP_TAGE::isHighConfidence().

gtable

TageEntry** TAGEBase::gtable

protected

Definition at line 434 of file tage_base.hh.

Referenced by buildTageTables(), getCtr(), MPP_TAGE::handleAllocAndUReset(), handleAllocAndUReset(), MPP_TAGE::handleTAGEUpdate(), handleTAGEUpdate(), MPP_TAGE::handleUReset(), handleUReset(), init(), MPP_TAGE::isHighConfidence(), and tagePredict().

histBufferSize

const unsigned TAGEBase::histBufferSize

protected

Definition at line 424 of file tage_base.hh.

Referenced by getGHR(), init(), and updateGHist().

histLengths

int* TAGEBase::histLengths

protected

Definition at line 466 of file tage_base.hh.

Referenced by MPP_TAGE::calculateParameters(), calculateParameters(), getSizeInBits(), gindex(), init(), and initFoldedHistories().

initialized

bool TAGEBase::initialized

protected

Definition at line 487 of file tage_base.hh.

Referenced by init().

initialTCounterValue

const int64_t TAGEBase::initialTCounterValue

protected

Definition at line 473 of file tage_base.hh.

Referenced by init().

instShiftAmt

const unsigned TAGEBase::instShiftAmt

protected

Definition at line 485 of file tage_base.hh.

Referenced by bindex(), gindex(), gtag(), and updateHistories().

logRatioBiModalHystEntries

const unsigned TAGEBase::logRatioBiModalHystEntries

protected

Definition at line 420 of file tage_base.hh.

Referenced by baseUpdate(), getSizeInBits(), init(), and MPP_TAGE::isHighConfidence().

logTagTableSizes

std::vector<int> TAGEBase::logTagTableSizes

protected

Definition at line 430 of file tage_base.hh.

Referenced by MPP_TAGE::bindex(), bindex(), buildTageTables(), F(), getSizeInBits(), gindex(), MPP_TAGE::handleUReset(), handleUReset(), init(), and initFoldedHistories().

logUResetPeriod

uint64_t TAGEBase::logUResetPeriod

protected

Definition at line 472 of file tage_base.hh.

Referenced by getSizeInBits(), MPP_TAGE::handleUReset(), handleUReset(), and init().

maxHist

const unsigned TAGEBase::maxHist

protected

Definition at line 426 of file tage_base.hh.

Referenced by calculateParameters(), init(), and updateGHist().

maxNumAlloc

unsigned TAGEBase::maxNumAlloc

protected

Definition at line 476 of file tage_base.hh.

Referenced by handleAllocAndUReset().

minHist

const unsigned TAGEBase::minHist

protected

Definition at line 425 of file tage_base.hh.

Referenced by calculateParameters().

nHistoryTables

const unsigned TAGEBase::nHistoryTables

protected

Definition at line 421 of file tage_base.hh.

Referenced by TAGEBase::BranchInfo::BranchInfo(), btbUpdate(), buildTageTables(), calculateIndicesAndTags(), MPP_TAGE::calculateParameters(), calculateParameters(), condBranchUpdate(), getSizeInBits(), MPP_TAGE::getUseAltIdx(), MPP_TAGE::handleAllocAndUReset(), handleAllocAndUReset(), MPP_TAGE::handleUReset(), handleUReset(), init(), initFoldedHistories(), regStats(), squash(), TAGEBase(), tagePredict(), updateHistories(), and MPP_TAGE::updatePathAndGlobalHistory().

noSkip

std::vector<bool> TAGEBase::noSkip

protected

Definition at line 481 of file tage_base.hh.

Referenced by MPP_TAGE::handleAllocAndUReset(), TAGEBase(), and tagePredict().

numUseAltOnNa

unsigned TAGEBase::numUseAltOnNa

protected

Definition at line 474 of file tage_base.hh.

Referenced by getSizeInBits(), MPP_TAGE::getUseAltIdx(), and init().

pathHistBits

const unsigned TAGEBase::pathHistBits

protected

Definition at line 427 of file tage_base.hh.

Referenced by getSizeInBits(), gindex(), init(), and updateHistories().

speculativeHistUpdate

const bool TAGEBase::speculativeHistUpdate

protected

Definition at line 483 of file tage_base.hh.

Referenced by btbUpdate(), isSpeculativeUpdateEnabled(), squash(), MPP_TAGE::updateHistories(), and updateHistories().

tableIndices

int* TAGEBase::tableIndices

protected

Definition at line 467 of file tage_base.hh.

Referenced by calculateIndicesAndTags(), init(), and tagePredict().

tableTags

int* TAGEBase::tableTags

protected

Definition at line 468 of file tage_base.hh.

Referenced by calculateIndicesAndTags(), init(), and tagePredict().

tageAltMatchProvider

Stats::Vector TAGEBase::tageAltMatchProvider

protected

Definition at line 502 of file tage_base.hh.

Referenced by regStats(), and updateStats().

tageAltMatchProviderCorrect

Stats::Scalar TAGEBase::tageAltMatchProviderCorrect

protected

Definition at line 491 of file tage_base.hh.

Referenced by regStats(), and updateStats().

tageAltMatchProviderWouldHaveHit

Stats::Scalar TAGEBase::tageAltMatchProviderWouldHaveHit

protected

Definition at line 498 of file tage_base.hh.

Referenced by regStats(), and updateStats().

tageAltMatchProviderWrong

Stats::Scalar TAGEBase::tageAltMatchProviderWrong

protected

Definition at line 495 of file tage_base.hh.

Referenced by regStats(), and updateStats().

tageBimodalProviderCorrect

Stats::Scalar TAGEBase::tageBimodalProviderCorrect

protected

Definition at line 493 of file tage_base.hh.

Referenced by regStats(), and updateStats().

tageBimodalProviderWrong

Stats::Scalar TAGEBase::tageBimodalProviderWrong

protected

Definition at line 497 of file tage_base.hh.

Referenced by regStats(), and updateStats().

tageLongestMatchProvider

Stats::Vector TAGEBase::tageLongestMatchProvider

protected

Definition at line 501 of file tage_base.hh.

Referenced by regStats(), and updateStats().

tageLongestMatchProviderCorrect

Stats::Scalar TAGEBase::tageLongestMatchProviderCorrect

protected

Definition at line 490 of file tage_base.hh.

Referenced by regStats(), and updateStats().

tageLongestMatchProviderWouldHaveHit

Stats::Scalar TAGEBase::tageLongestMatchProviderWouldHaveHit

protected

Definition at line 499 of file tage_base.hh.

Referenced by regStats(), and updateStats().

tageLongestMatchProviderWrong

Stats::Scalar TAGEBase::tageLongestMatchProviderWrong

protected

Definition at line 494 of file tage_base.hh.

Referenced by regStats(), and updateStats().

tagTableCounterBits

const unsigned TAGEBase::tagTableCounterBits

protected

Definition at line 422 of file tage_base.hh.

Referenced by getSizeInBits(), getTageCtrBits(), MPP_TAGE::handleTAGEUpdate(), handleTAGEUpdate(), and MPP_TAGE::isHighConfidence().

tagTableTagWidths

std::vector<unsigned> TAGEBase::tagTableTagWidths

protected

Definition at line 429 of file tage_base.hh.

Referenced by getSizeInBits(), gtag(), init(), and initFoldedHistories().

tagTableUBits

const unsigned TAGEBase::tagTableUBits

protected

Definition at line 423 of file tage_base.hh.

Referenced by getSizeInBits(), MPP_TAGE::handleTAGEUpdate(), handleTAGEUpdate(), and init().

tCounter

int64_t TAGEBase::tCounter

protected

Definition at line 471 of file tage_base.hh.

Referenced by MPP_TAGE::handleAllocAndUReset(), handleAllocAndUReset(), MPP_TAGE::handleUReset(), handleUReset(), and init().

threadHistory

std::vector<ThreadHistory> TAGEBase::threadHistory

protected

Definition at line 459 of file tage_base.hh.

Referenced by btbUpdate(), getGHR(), getPathHist(), gindex(), gtag(), init(), squash(), MPP_TAGE::updateHistories(), and updateHistories().

useAltOnNaBits

unsigned TAGEBase::useAltOnNaBits

protected

Definition at line 475 of file tage_base.hh.

Referenced by condBranchUpdate(), and getSizeInBits().

useAltPredForNewlyAllocated

std::vector<int8_t> TAGEBase::useAltPredForNewlyAllocated

protected

Definition at line 470 of file tage_base.hh.

Referenced by condBranchUpdate(), init(), and tagePredict().

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

• cpu/pred/tage_base.hh
• cpu/pred/tage_base.cc