gem5  v21.1.0.2
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gem5::branch_prediction::TAGE Class Reference

#include <tage.hh>

Inheritance diagram for gem5::branch_prediction::TAGE:
gem5::branch_prediction::BPredUnit gem5::SimObject gem5::EventManager gem5::Serializable gem5::Drainable gem5::statistics::Group gem5::Named gem5::branch_prediction::LTAGE gem5::branch_prediction::TAGE_SC_L gem5::branch_prediction::TAGE_SC_L_64KB gem5::branch_prediction::TAGE_SC_L_8KB

Classes

struct  TageBranchInfo
 

Public Member Functions

 TAGE (const TAGEParams &params)
 
void uncondBranch (ThreadID tid, Addr br_pc, void *&bp_history) override
 
bool lookup (ThreadID tid, Addr branch_addr, void *&bp_history) override
 Looks up a given PC in the BP to see if it is taken or not taken. 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...
 
void update (ThreadID tid, Addr branch_addr, bool taken, void *bp_history, bool squashed, const StaticInstPtr &inst, Addr corrTarget) override
 Updates the BP with taken/not taken information. More...
 
virtual void squash (ThreadID tid, void *bp_history) override
 
- Public Member Functions inherited from gem5::branch_prediction::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 gem5::SimObject
const Paramsparams () const
 
 SimObject (const Params &p)
 
virtual ~SimObject ()
 
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 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 gem5::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 gem5::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 gem5::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 gem5::statistics::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 (statistics::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...
 
void mergeStatGroup (Group *block)
 Merge the contents (stats & children) of a block to this block. More...
 
 Group ()=delete
 
 Group (const Group &)=delete
 
Groupoperator= (const Group &)=delete
 
- Public Member Functions inherited from gem5::Named
 Named (const std::string &name_)
 
virtual ~Named ()=default
 
virtual std::string name () const
 

Protected Member Functions

virtual bool predict (ThreadID tid, Addr branch_pc, bool cond_branch, void *&b)
 
- Protected Member Functions inherited from gem5::branch_prediction::BPredUnit
probing::PMUUPtr pmuProbePoint (const char *name)
 Helper method to instantiate probe points belonging to this object. More...
 
- Protected Member Functions inherited from gem5::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

TAGEBasetage
 
- Protected Attributes inherited from gem5::branch_prediction::BPredUnit
const unsigned instShiftAmt
 Number of bits to shift instructions by for predictor addresses. More...
 
probing::PMUUPtr ppBranches
 Branches seen by the branch predictor. More...
 
probing::PMUUPtr ppMisses
 Miss-predicted branches. More...
 
- Protected Attributes inherited from gem5::SimObject
const SimObjectParams & _params
 Cached copy of the object parameters. More...
 
- Protected Attributes inherited from gem5::EventManager
EventQueueeventq
 A pointer to this object's event queue. More...
 

Additional Inherited Members

- Public Types inherited from gem5::branch_prediction::BPredUnit
typedef BranchPredictorParams Params
 
- Public Types inherited from gem5::SimObject
typedef SimObjectParams Params
 
- Static Public Member Functions inherited from gem5::SimObject
static void serializeAll (const std::string &cpt_dir)
 Create a checkpoint by serializing 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 void setSimObjectResolver (SimObjectResolver *resolver)
 There is a single object name resolver, and it is only set when simulation is restoring from checkpoints. More...
 
static SimObjectResolvergetSimObjectResolver ()
 There is a single object name resolver, and it is only set when simulation is restoring from checkpoints. More...
 
- Static Public Member Functions inherited from gem5::Serializable
static const std::string & currentSection ()
 Gets the fully-qualified name of the active section. More...
 
static void generateCheckpointOut (const std::string &cpt_dir, std::ofstream &outstream)
 Generate a checkpoint file so that the serialization can be routed to it. More...
 

Detailed Description

Definition at line 64 of file tage.hh.

Constructor & Destructor Documentation

◆ TAGE()

gem5::branch_prediction::TAGE::TAGE ( const TAGEParams &  params)

Definition at line 53 of file tage.cc.

Member Function Documentation

◆ btbUpdate()

void gem5::branch_prediction::TAGE::btbUpdate ( ThreadID  tid,
Addr  instPC,
void *&  bp_history 
)
overridevirtual

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.

Parameters
inst_PCThe PC to look up the local predictor.
bp_historyPointer that will be set to an object that has the branch predictor state associated with the lookup.

Implements gem5::branch_prediction::BPredUnit.

Definition at line 120 of file tage.cc.

References gem5::PowerISA::bi, gem5::branch_prediction::TAGEBase::btbUpdate(), and tage.

◆ lookup()

bool gem5::branch_prediction::TAGE::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_PCThe PC to look up.
bp_historyPointer 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.

Implements gem5::branch_prediction::BPredUnit.

Definition at line 106 of file tage.cc.

References gem5::PowerISA::bi, DPRINTF, predict(), tage, and gem5::branch_prediction::TAGEBase::updateHistories().

◆ predict()

bool gem5::branch_prediction::TAGE::predict ( ThreadID  tid,
Addr  branch_pc,
bool  cond_branch,
void *&  b 
)
protectedvirtual

◆ squash()

void gem5::branch_prediction::TAGE::squash ( ThreadID  tid,
void *  bp_history 
)
overridevirtual
Parameters
bp_historyPointer to the history object. The predictor will need to update any state and delete the object.

Implements gem5::branch_prediction::BPredUnit.

Reimplemented in gem5::branch_prediction::LTAGE.

Definition at line 90 of file tage.cc.

References gem5::PowerISA::bi, and DPRINTF.

Referenced by gem5::branch_prediction::LTAGE::squash().

◆ uncondBranch()

void gem5::branch_prediction::TAGE::uncondBranch ( ThreadID  tid,
Addr  br_pc,
void *&  bp_history 
)
overridevirtual

◆ update()

void gem5::branch_prediction::TAGE::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_PCThe branch's PC that will be updated.
takenWhether the branch was taken or not taken.
bp_historyPointer to the branch predictor state that is associated with the branch lookup that is being updated.
squashedSet to true when this function is called during a squash operation.
instStatic instruction information
corrTargetThe resolved target of the branch (only needed for squashed branches)
Todo:
Make this update flexible enough to handle a global predictor.

Implements gem5::branch_prediction::BPredUnit.

Reimplemented in gem5::branch_prediction::TAGE_SC_L.

Definition at line 59 of file tage.cc.

References gem5::PowerISA::bi, gem5::branch_prediction::TAGEBase::condBranchUpdate(), DPRINTF, gem5::Random::random(), gem5::random_mt, gem5::branch_prediction::TAGEBase::squash(), tage, gem5::branch_prediction::TAGEBase::updateHistories(), and gem5::branch_prediction::TAGEBase::updateStats().

Member Data Documentation

◆ tage

TAGEBase* gem5::branch_prediction::TAGE::tage
protected

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

Generated on Tue Sep 21 2021 12:28:49 for gem5 by doxygen 1.8.17