A template version of the dictionary compressor that allows to choose the dictionary size. More...

#include <dictionary_compressor.hh>

Inheritance diagram for gem5::compression::DictionaryCompressor< T >:

Classes
class	CompData

class	DeltaPattern
	A pattern that checks whether the difference of the value and the dictionary entries' is below a certain threshold. More...

struct	Factory
	Create a factory to determine if input matches a pattern. More...

struct	Factory< Head >
	Specialization to end the recursion. More...

class	LocatedMaskedPattern
	A pattern that narrows the MaskedPattern by allowing a only single possible dictionary entry to be matched against. More...

class	MaskedPattern
	A pattern that compares masked values against dictionary entries. More...

class	MaskedValuePattern
	A pattern that compares masked values to a masked portion of a fixed value. More...

class	Pattern
	The compressed data is composed of multiple pattern entries. More...

class	RepeatedValuePattern
	A pattern that checks if dictionary entry sized values are solely composed of multiple copies of a single value. More...

class	SignExtendedPattern
	A pattern that checks whether the value is an N bits sign-extended value, that is, all the MSB starting from the Nth are equal to the (N-1)th bit. More...

class	UncompressedPattern
	A pattern containing the original uncompressed data. More...

Public Types
typedef BaseDictionaryCompressorParams	Params

Public Types inherited from gem5::compression::BaseDictionaryCompressor
typedef BaseDictionaryCompressorParams	Params

Public Types inherited from gem5::compression::Base
typedef BaseCacheCompressorParams	Params

Public Types inherited from gem5::SimObject
typedef SimObjectParams	Params

Public Member Functions
	DictionaryCompressor (const Params &p)

	~DictionaryCompressor ()=default

Public Member Functions inherited from gem5::compression::BaseDictionaryCompressor
	BaseDictionaryCompressor (const Params &p)

	~BaseDictionaryCompressor ()=default

Public Member Functions inherited from gem5::compression::Base
	Base (const Params &p)

virtual	~Base ()=default

virtual void	setCache (BaseCache *_cache)
	The cache can only be set once.

std::unique_ptr< CompressionData >	compress (const uint64_t *data, Cycles &comp_lat, Cycles &decomp_lat)
	Apply the compression process to the cache line.

Cycles	getDecompressionLatency (const CacheBlk *blk)
	Get the decompression latency if the block is compressed.

Public Member Functions inherited from gem5::SimObject
const Params &	params () 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.

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

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

virtual void	regProbePoints ()
	Register probe points for this object.

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

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

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

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

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

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

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

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

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

Public Member Functions inherited from gem5::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.

void	setCurTick (Tick newVal)

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

	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.

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

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

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.

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

Public Member Functions inherited from gem5::statistics::Group
	Group (Group parent, const char name=nullptr)
	Construct a new statistics group.

virtual	~Group ()

virtual void	regStats ()
	Callback to set stat parameters.

virtual void	resetStats ()
	Callback to reset stats.

virtual void	preDumpStats ()
	Callback before stats are dumped.

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

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

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

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

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

void	mergeStatGroup (Group *block)
	Merge the contents (stats & children) of a block to this block.

	Group ()=delete

	Group (const Group &)=delete

Group &	operator= (const Group &)=delete

Public Member Functions inherited from gem5::Named
	Named (std::string_view name_)

virtual	~Named ()=default

virtual std::string	name () const

Protected Types
typedef std::array< uint8_t, sizeof(T)>	DictionaryEntry
	Convenience typedef for a dictionary entry.

Protected Types inherited from gem5::compression::Base
typedef uint64_t	Chunk
	A chunk is a basic lexical unit.

Protected Member Functions
virtual std::unique_ptr< Pattern >	getPattern (const DictionaryEntry &bytes, const DictionaryEntry &dict_bytes, const int match_location) const =0
	Since the factory cannot be instantiated here, classes that inherit from this base class have to implement the call to their factory's getPattern.

std::unique_ptr< Pattern >	compressValue (const T data)
	Compress data.

T	decompressValue (const Pattern *pattern)
	Decompress a pattern into a value that fits in a dictionary entry.

virtual void	resetDictionary ()
	Clear all dictionary entries.

virtual void	addToDictionary (const DictionaryEntry data)=0
	Add an entry to the dictionary.

virtual std::unique_ptr< DictionaryCompressor::CompData >	instantiateDictionaryCompData () const
	Instantiate a compression data of the sub-class compressor.

std::unique_ptr< Base::CompressionData >	compress (const std::vector< Chunk > &chunks)
	Apply compression.

std::unique_ptr< Base::CompressionData >	compress (const std::vector< Chunk > &chunks, Cycles &comp_lat, Cycles &decomp_lat) override
	Apply the compression process to the cache line.

void	decompress (const CompressionData comp_data, uint64_t data) override
	Apply the decompression process to the compressed data.

Protected Member Functions inherited from gem5::compression::BaseDictionaryCompressor
virtual uint64_t	getNumPatterns () const =0
	Trick function to get the number of patterns.

virtual std::string	getName (int number) const =0
	Get meta-name assigned to the given pattern.

Protected Member Functions inherited from gem5::compression::Base
std::vector< Chunk >	toChunks (const uint64_t *data) const
	This function splits the raw data into chunks, so that it can be parsed by the compressor.

void	fromChunks (const std::vector< Chunk > &chunks, uint64_t *data) const
	This function re-joins the chunks to recreate the original data.

Protected Member Functions inherited from gem5::Drainable
	Drainable ()

virtual	~Drainable ()

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

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

Static Protected Member Functions
static DictionaryEntry	toDictionaryEntry (T value)
	Turn a value into a dictionary entry.

static T	fromDictionaryEntry (const DictionaryEntry &entry)
	Turn a dictionary entry into a value.

Protected Attributes
std::vector< DictionaryEntry >	dictionary
	The dictionary.

Protected Attributes inherited from gem5::compression::BaseDictionaryCompressor
const std::size_t	dictionarySize
	Dictionary size.

std::size_t	numEntries
	Number of valid entries in the dictionary.

gem5::compression::BaseDictionaryCompressor::DictionaryStats	dictionaryStats

Protected Attributes inherited from gem5::compression::Base
const std::size_t	blkSize
	Uncompressed cache line size (in bytes).

const unsigned	chunkSizeBits
	Chunk size, in number of bits.

const std::size_t	sizeThreshold
	Size in bytes at which a compression is classified as bad and therefore the compressed block is restored to its uncompressed format.

const Cycles	compChunksPerCycle
	Degree of parallelization of the compression process.

const Cycles	compExtraLatency
	Extra latency added to compression due to packaging, shifting or other operations.

const Cycles	decompChunksPerCycle
	Degree of parallelization of the decompression process.

const Cycles	decompExtraLatency
	Extra latency added to decompression due to packaging, shifting or other operations.

BaseCache *	cache
	Pointer to the parent cache.

gem5::compression::Base::BaseStats	stats

Protected Attributes inherited from gem5::SimObject
const SimObjectParams &	_params
	Cached copy of the object parameters.

Protected Attributes inherited from gem5::EventManager
EventQueue *	eventq
	A pointer to this object's event queue.

Additional Inherited Members
Static Public Member Functions inherited from gem5::compression::Base
static void	setDecompressionLatency (CacheBlk *blk, const Cycles lat)
	Set the decompression latency of compressed block.

static void	setSizeBits (CacheBlk *blk, const std::size_t size_bits)
	Set the size of the compressed block, in bits.

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.

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

static void	setSimObjectResolver (SimObjectResolver *resolver)
	There is a single object name resolver, and it is only set when simulation is restoring from checkpoints.

static SimObjectResolver *	getSimObjectResolver ()
	There is a single object name resolver, and it is only set when simulation is restoring from checkpoints.

Static Public Member Functions inherited from gem5::Serializable
static const std::string &	currentSection ()
	Gets the fully-qualified name of the active section.

static void	generateCheckpointOut (const std::string &cpt_dir, std::ofstream &outstream)
	Generate a checkpoint file so that the serialization can be routed to it.

Detailed Description

template<class T>
class gem5::compression::DictionaryCompressor< T >

A template version of the dictionary compressor that allows to choose the dictionary size.

Template Parameters

The	type of a dictionary entry (e.g., uint16_t, uint32_t, etc).

Definition at line 117 of file dictionary_compressor.hh.

Member Typedef Documentation

◆ DictionaryEntry

template<class T>

typedef std::array<uint8_t, sizeof(T)> gem5::compression::DictionaryCompressor< T >::DictionaryEntry

protected

Convenience typedef for a dictionary entry.

Definition at line 121 of file dictionary_compressor.hh.

◆ Params

template<class T>

typedef BaseDictionaryCompressorParams gem5::compression::DictionaryCompressor< T >::Params

Definition at line 273 of file dictionary_compressor.hh.

Constructor & Destructor Documentation

◆ DictionaryCompressor()

template<class T>

gem5::compression::DictionaryCompressor< T >::DictionaryCompressor ( const Params & p )

Definition at line 67 of file dictionary_compressor_impl.hh.

References gem5::compression::BaseDictionaryCompressor::BaseDictionaryCompressor(), dictionary, gem5::compression::BaseDictionaryCompressor::dictionarySize, gem5::MipsISA::p, and resetDictionary().

◆ ~DictionaryCompressor()

template<class T>

gem5::compression::DictionaryCompressor< T >::~DictionaryCompressor ( )

default

Member Function Documentation

◆ addToDictionary()

template<class T>

virtual void gem5::compression::DictionaryCompressor< T >::addToDictionary ( const DictionaryEntry data )

protectedpure virtual

Add an entry to the dictionary.

Parameters

data	The new entry.

Referenced by compressValue(), and decompressValue().

◆ compress() [1/2]

template<class T>

std::unique_ptr< Base::CompressionData > gem5::compression::DictionaryCompressor< T >::compress ( const std::vector< Chunk > & chunks )

protected

Apply compression.

Parameters

chunks The cache line to be compressed.

Returns: Cache line after compression.

Definition at line 130 of file dictionary_compressor_impl.hh.

References gem5::compression::DictionaryCompressor< T >::CompData::addEntry(), compressValue(), DPRINTF, instantiateDictionaryCompData(), and resetDictionary().

Referenced by gem5::compression::BaseDelta< BaseType, DeltaSizeBits >::compress(), compress(), gem5::compression::RepeatedQwords::compress(), and gem5::compression::Zero::compress().

◆ compress() [2/2]

template<class T>

std::unique_ptr< Base::CompressionData > gem5::compression::DictionaryCompressor< T >::compress	(	const std::vector< Chunk > &	chunks,
		Cycles &	comp_lat,
		Cycles &	decomp_lat )

overrideprotectedvirtual

Apply the compression process to the cache line.

Returns the number of cycles used by the compressor, however it is usually covered by a good pipelined execution, and is currently ignored. The decompression latency is also returned, in order to avoid increasing simulation time and memory consumption.

Parameters

chunks	The cache line to be compressed, divided into chunks.
comp_lat	Compression latency in number of cycles.
decomp_lat	Decompression latency in number of cycles.

Returns: Cache line after compression.

Implements gem5::compression::Base.

Definition at line 153 of file dictionary_compressor_impl.hh.

References gem5::compression::Base::compChunksPerCycle, gem5::compression::Base::compExtraLatency, compress(), gem5::compression::Base::decompChunksPerCycle, and gem5::compression::Base::decompExtraLatency.

◆ compressValue()

template<typename T>

std::unique_ptr< typename DictionaryCompressor< T >::Pattern > gem5::compression::DictionaryCompressor< T >::compressValue ( const T data )

protected

Compress data.

Parameters

data	Data to be compressed.

Returns: The pattern this data matches.

Definition at line 95 of file dictionary_compressor_impl.hh.

References addToDictionary(), data, dictionary, gem5::compression::BaseDictionaryCompressor::dictionaryStats, getPattern(), gem5::ArmISA::i, gem5::compression::BaseDictionaryCompressor::numEntries, and toDictionaryEntry().

Referenced by compress().

◆ decompress()

template<class T>

void gem5::compression::DictionaryCompressor< T >::decompress	(	const CompressionData *	comp_data,
		uint64_t *	cache_line )

overrideprotectedvirtual

Apply the decompression process to the compressed data.

Parameters

comp_data	Compressed cache line.
cache_line	The cache line to be decompressed.

Implements gem5::compression::Base.

Reimplemented in gem5::compression::DictionaryCompressor< T >::MaskedValuePattern< value, mask >, gem5::compression::DictionaryCompressor< T >::MaskedValuePattern< 0, 0xFFFFFFFFFFFFFFFF >, gem5::compression::DictionaryCompressor< T >::MaskedValuePattern< 0, 0xFFFFFFFFFFFFFFFF >, gem5::compression::DictionaryCompressor< T >::RepeatedValuePattern< RepT >, gem5::compression::DictionaryCompressor< T >::SignExtendedPattern< N >, and gem5::compression::DictionaryCompressor< T >::UncompressedPattern.

Definition at line 187 of file dictionary_compressor_impl.hh.

References gem5::compression::Base::blkSize, data, decompressValue(), DPRINTF, gem5::compression::DictionaryCompressor< T >::CompData::entries, gem5::ArmISA::i, and resetDictionary().

◆ decompressValue()

template<class T>

T gem5::compression::DictionaryCompressor< T >::decompressValue ( const Pattern * pattern )

protected

Decompress a pattern into a value that fits in a dictionary entry.

Parameters

pattern The pattern to be decompressed.

Returns: The decompressed word.

Definition at line 168 of file dictionary_compressor_impl.hh.

References addToDictionary(), data, gem5::compression::DictionaryCompressor< T >::Pattern::decompress(), dictionary, fromDictionaryEntry(), gem5::compression::DictionaryCompressor< T >::Pattern::getMatchLocation(), and gem5::compression::DictionaryCompressor< T >::Pattern::shouldAllocate().

Referenced by decompress().

◆ fromDictionaryEntry()

template<class T>

T gem5::compression::DictionaryCompressor< T >::fromDictionaryEntry ( const DictionaryEntry & entry )

staticprotected

Turn a dictionary entry into a value.

Parameters

The	dictionary entry to turn.

Returns: The value that the dictionary entry contained.

Definition at line 229 of file dictionary_compressor_impl.hh.

References gem5::ArmISA::i.

Referenced by gem5::compression::DictionaryCompressor< T >::MaskedPattern< mask >::decompress(), decompressValue(), gem5::compression::DictionaryCompressor< T >::MaskedPattern< mask >::isPattern(), gem5::compression::DictionaryCompressor< T >::MaskedValuePattern< value, mask >::isPattern(), gem5::compression::DictionaryCompressor< T >::RepeatedValuePattern< RepT >::isPattern(), gem5::compression::DictionaryCompressor< T >::SignExtendedPattern< N >::isPattern(), and gem5::compression::DictionaryCompressor< T >::DeltaPattern< DeltaSizeBits >::isValidDelta().

◆ getPattern()

template<class T>

virtual std::unique_ptr< Pattern > gem5::compression::DictionaryCompressor< T >::getPattern	(	const DictionaryEntry &	bytes,
		const DictionaryEntry &	dict_bytes,
		const int	match_location ) const

protectedpure virtual

Since the factory cannot be instantiated here, classes that inherit from this base class have to implement the call to their factory's getPattern.

Referenced by compressValue().

◆ instantiateDictionaryCompData()

template<typename T>

std::unique_ptr< typename DictionaryCompressor< T >::CompData > gem5::compression::DictionaryCompressor< T >::instantiateDictionaryCompData ( ) const

protectedvirtual

Instantiate a compression data of the sub-class compressor.

Returns: The new compression data entry.

Definition at line 88 of file dictionary_compressor_impl.hh.

Referenced by compress().

◆ resetDictionary()

template<class T>

void gem5::compression::DictionaryCompressor< T >::resetDictionary ( )

protectedvirtual

Clear all dictionary entries.

Definition at line 77 of file dictionary_compressor_impl.hh.

References dictionary, gem5::compression::BaseDictionaryCompressor::numEntries, and toDictionaryEntry().

Referenced by compress(), decompress(), DictionaryCompressor(), and gem5::compression::BaseDelta< BaseType, DeltaSizeBits >::resetDictionary().

◆ toDictionaryEntry()

template<class T>

DictionaryCompressor< T >::DictionaryEntry gem5::compression::DictionaryCompressor< T >::toDictionaryEntry ( T value )

staticprotected

Turn a value into a dictionary entry.

Parameters

value The value to turn.

Returns: A dictionary entry containing the value.

Definition at line 217 of file dictionary_compressor_impl.hh.

Referenced by compressValue(), gem5::compression::DictionaryCompressor< T >::MaskedPattern< mask >::decompress(), gem5::compression::DictionaryCompressor< T >::MaskedValuePattern< value, mask >::decompress(), gem5::compression::DictionaryCompressor< T >::RepeatedValuePattern< RepT >::decompress(), gem5::compression::DictionaryCompressor< T >::SignExtendedPattern< N >::decompress(), gem5::compression::BaseDelta< BaseType, DeltaSizeBits >::resetDictionary(), and resetDictionary().

Member Data Documentation

◆ dictionary

template<class T>

std::vector<DictionaryEntry> gem5::compression::DictionaryCompressor< T >::dictionary

protected

The dictionary.

Definition at line 194 of file dictionary_compressor.hh.

Referenced by gem5::compression::BaseDelta< BaseType, DeltaSizeBits >::addToDictionary(), compressValue(), decompressValue(), DictionaryCompressor(), and resetDictionary().

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

mem/cache/compressors/dictionary_compressor.hh
mem/cache/compressors/dictionary_compressor_impl.hh

Classes

Public Types

Public Member Functions

Protected Types

Protected Member Functions

Static Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Member Typedef Documentation

◆ DictionaryEntry

◆ Params

Constructor & Destructor Documentation

◆ DictionaryCompressor()

◆ ~DictionaryCompressor()

Member Function Documentation

◆ addToDictionary()

◆ compress() [1/2]

◆ compress() [2/2]

◆ compressValue()

◆ decompress()

◆ decompressValue()

◆ fromDictionaryEntry()

◆ getPattern()

◆ instantiateDictionaryCompData()

◆ resetDictionary()

◆ toDictionaryEntry()

Member Data Documentation

◆ dictionary