gem5  v20.1.0.0
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MPP_TAGE Class Reference

#include <multiperspective_perceptron_tage.hh>

Inheritance diagram for MPP_TAGE:
TAGEBase SimObject EventManager Serializable Drainable Stats::Group MPP_TAGE_8KB

Classes

struct  BranchInfo
 

Public Member Functions

 MPP_TAGE (const MPP_TAGEParams *p)
 
void calculateParameters () override
 Calculates the history lengths and some other paramters in derived classes. More...
 
void handleTAGEUpdate (Addr branch_pc, bool taken, TAGEBase::BranchInfo *bi) override
 Handles the update of the TAGE entries. More...
 
void handleAllocAndUReset (bool alloc, bool taken, TAGEBase::BranchInfo *bi, int nrand) override
 Handles Allocation and U bits reset on an update. More...
 
void handleUReset () override
 Handles the U bits reset. More...
 
void resetUctr (uint8_t &u) override
 Algorithm for resetting a single U counter. More...
 
int bindex (Addr pc_in) const override
 Computes the index used to access the bimodal table. More...
 
bool isHighConfidence (TAGEBase::BranchInfo *bi) const override
 
unsigned getUseAltIdx (TAGEBase::BranchInfo *bi, Addr branch_pc) override
 Calculation of the index for useAltPredForNewlyAllocated On this base TAGE implementation it is always 0. More...
 
void adjustAlloc (bool &alloc, bool taken, bool pred_taken) override
 Extra calculation to tell whether TAGE allocaitons may happen or not on an update For this base TAGE implementation it does nothing. More...
 
void updateHistories (ThreadID tid, Addr branch_pc, bool taken, TAGEBase::BranchInfo *b, bool speculative, const StaticInstPtr &inst, Addr target) override
 (Speculatively) updates global histories (path and direction). More...
 
void updatePathAndGlobalHistory (ThreadHistory &tHist, int brtype, bool taken, Addr branch_pc, Addr target)
 
- Public Member Functions inherited from TAGEBase
 TAGEBase (const TAGEBaseParams *p)
 
void init () override
 init() is called after all C++ SimObjects have been created and all ports are connected. More...
 
virtual BranchInfomakeBranchInfo ()
 
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 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 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 void extraAltCalc (BranchInfo *bi)
 Extra steps for calculating altTaken For this base TAGE class it does nothing. More...
 
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 Paramsparams () 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...
 
ProbeManagergetProbeManager ()
 Get the probe manager for this object. More...
 
virtual PortgetPort (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
EventQueueeventQueue () 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 InforesolveStat (std::string name) const
 Resolve a stat by its name within this group. More...
 
 Group ()=delete
 
 Group (const Group &)=delete
 
Groupoperator= (const Group &)=delete
 

Private Attributes

std::vector< unsigned int > tunedHistoryLengths
 

Additional Inherited Members

- Public Types inherited from TAGEBase
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
 
- Static Public Member Functions inherited from TAGEBase
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 SimObjectfind (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 TAGEBase
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 inherited from TAGEBase
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< ThreadHistorythreadHistory
 
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
 
TAGEBase::TAGEBaseStats stats
 
- Protected Attributes inherited from SimObject
const SimObjectParams * _params
 Cached copy of the object parameters. More...
 
- Protected Attributes inherited from EventManager
EventQueueeventq
 A pointer to this object's event queue. More...
 

Detailed Description

Definition at line 51 of file multiperspective_perceptron_tage.hh.

Constructor & Destructor Documentation

◆ MPP_TAGE()

MPP_TAGE::MPP_TAGE ( const MPP_TAGEParams *  p)
inline

Definition at line 61 of file multiperspective_perceptron_tage.hh.

Member Function Documentation

◆ adjustAlloc()

void MPP_TAGE::adjustAlloc ( bool &  alloc,
bool  taken,
bool  pred_taken 
)
overridevirtual

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

Reimplemented from TAGEBase.

Definition at line 178 of file multiperspective_perceptron_tage.cc.

References Random::random(), and random_mt.

◆ bindex()

int MPP_TAGE::bindex ( Addr  pc_in) const
overridevirtual

Computes the index used to access the bimodal table.

Parameters
pc_inThe unshifted branch PC.

Reimplemented from TAGEBase.

Definition at line 161 of file multiperspective_perceptron_tage.cc.

References TAGEBase::logTagTableSizes, MipsISA::pc, and ULL.

◆ calculateParameters()

void MPP_TAGE::calculateParameters ( )
overridevirtual

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

Reimplemented from TAGEBase.

Definition at line 44 of file multiperspective_perceptron_tage.cc.

References TAGEBase::histLengths, ArmISA::i, TAGEBase::nHistoryTables, and tunedHistoryLengths.

◆ getUseAltIdx()

unsigned MPP_TAGE::getUseAltIdx ( TAGEBase::BranchInfo bi,
Addr  branch_pc 
)
overridevirtual

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

Reimplemented from TAGEBase.

Definition at line 169 of file multiperspective_perceptron_tage.cc.

References PowerISA::bi, TAGEBase::nHistoryTables, and TAGEBase::numUseAltOnNa.

◆ handleAllocAndUReset()

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

◆ handleTAGEUpdate()

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

◆ handleUReset()

void MPP_TAGE::handleUReset ( )
overridevirtual

◆ isHighConfidence()

bool MPP_TAGE::isHighConfidence ( TAGEBase::BranchInfo bi) const
overridevirtual

◆ resetUctr()

void MPP_TAGE::resetUctr ( uint8_t &  u)
overridevirtual

Algorithm for resetting a single U counter.

Reimplemented from TAGEBase.

Definition at line 151 of file multiperspective_perceptron_tage.cc.

References ArmISA::u.

Referenced by handleUReset().

◆ updateHistories()

void MPP_TAGE::updateHistories ( ThreadID  tid,
Addr  branch_pc,
bool  taken,
TAGEBase::BranchInfo b,
bool  speculative,
const StaticInstPtr inst,
Addr  target 
)
overridevirtual

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

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

Parameters
tidThe thread ID to select the histories to update.
branch_pcThe unshifted branch PC.
taken(Predicted) branch direction.
bWrapping pointer to BranchInfo (to allow storing derived class prediction information in the base class).

Reimplemented from TAGEBase.

Definition at line 187 of file multiperspective_perceptron_tage.cc.

References StaticInst::isDirectCtrl(), StaticInst::isUncondCtrl(), TAGEBase::speculativeHistUpdate, TAGEBase::threadHistory, and updatePathAndGlobalHistory().

◆ updatePathAndGlobalHistory()

void MPP_TAGE::updatePathAndGlobalHistory ( ThreadHistory tHist,
int  brtype,
bool  taken,
Addr  branch_pc,
Addr  target 
)

Member Data Documentation

◆ tunedHistoryLengths

std::vector<unsigned int> MPP_TAGE::tunedHistoryLengths
private

Definition at line 52 of file multiperspective_perceptron_tage.hh.

Referenced by calculateParameters().


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

Generated on Wed Sep 30 2020 14:02:28 for gem5 by doxygen 1.8.17