abigail::hashing Namespace Reference

Namespace for hashing. More...

Enumerations
enum	hashing_state {   HASHING_NOT_DONE_STATE , HASHING_STARTED_STATE , HASHING_CYCLED_TYPE_STATE , HASHING_SUBTYPE_STATE ,   HASHING_FINISHED_STATE }
	Enumeration of the different hashing states of an IR node being hashed. More...

Functions
hash_t	combine_hashes (hash_t val1, hash_t val2)
	Combine two hash values to produce a third hash value.
bool	deserialize_hash (const string &input, uint64_t &hash)
	Read a string of characters representing a string of hexadecimal digits which itself represents a hash value that was computed using the XH64 algorithm from the xxhash project.
uint32_t	fnv_hash (const std::string &str)
	Compute a stable string hash.
hashing::hashing_state	get_hashing_state (const type_or_decl_base &tod)
	Get the hashing state of an IR node.
hash_t	hash (const std::string &str)
	Hash a string.
hash_t	hash (std::uint64_t v, std::uint64_t seed=0)
hash_t	hash (uint64_t v, uint64_t seed)
	Hash an integer value and combine it with a hash previously computed.
bool	is_recursive_artefact (const type_or_decl_base &t)
	Test if an artifact is recursive.
void	is_recursive_artefact (const type_or_decl_base &t, bool f)
	Set the property that flags an artifact as recursive.
bool	serialize_hash (uint64_t hash, string &output)
	Serialiaze a hash value computed using the XH64 algorithm (from the xxhash project) into a string of characters representing the digits of the hash in the canonical form requested by the xxhash project. That canonical form is basically a big endian representation of the hexadecimal hash number.
void	set_hashing_state (const type_or_decl_base &tod, hashing::hashing_state s)
	Set the hashing state of an IR node.

Detailed Description

Namespace for hashing.

Enumeration Type Documentation

hashing_state

enum hashing_state

Enumeration of the different hashing states of an IR node being hashed.

Enumerator
HASHING_NOT_DONE_STATE	No hashing has been done/started.
HASHING_STARTED_STATE	Hashing started but is not yet finished. Note that when a type_or_decl_base::priv::set_hash_value is invoked on an artifact which has this state, then the hash value is set/saved onto the artifact.
HASHING_CYCLED_TYPE_STATE	A cycle has been detected in the graph on the current node node. This means the hashing has started on the current IR node and while hashing its children nodes, this very same IR node is visited again to be hashed. This is a cycle and it needs to be broken otherwise the hashing continues forever. Note that when a type_or_decl_base::priv::set_hash_value is invoked on an artifact which has this state, then the hash value is set/saved onto the artifact.
HASHING_SUBTYPE_STATE	Hashing a sub-type while hashing another type. When a type_or_decl_base::hash_value() is invoked on an artifact which has this state, it means the hash value that is computed must NOT be set/saved onto the artifact. type_or_decl_base::priv::set_hash_value is where this is enforced.
HASHING_FINISHED_STATE	Hashing of given IR node started and is now done. If an ABI artifact is in this state, then it must have an hash value available and should be get by peek_hash_value or type_or_decl_base::hash_value().

Definition at line 24 of file abg-hash.h.

Function Documentation

combine_hashes()

hash_t combine_hashes	(	hash_t	val1,
		hash_t	val2 )

Combine two hash values to produce a third hash value.

If one of the hash values is empty then the other one is returned, intact. If the two hash values are empty then an empty hash value is returned as a result.

Parameters

val1	the first hash value.
val2	the second hash value.

Returns

a combination of the hash values val1 and val2.

Definition at line 172 of file abg-hash.cc.

deserialize_hash()

bool deserialize_hash	(	const string &	input,
		uint64_t &	hash )

Read a string of characters representing a string of hexadecimal digits which itself represents a hash value that was computed using the XH64 algorithm from the xxhash project.

That string of digit (characters) is laid out in the "canonical form" requested by the xxhash project. That form is basically the hash number, represented in big endian.

Parameters

input	the input string of characters to consider.
hash	the resulting hash value de-serialized from input. This is set by the function iff it returns true.

Returns

true iff the function could de-serialize the characters string input into the hash value hash.

Definition at line 99 of file abg-hash.cc.

fnv_hash()

uint32_t fnv_hash

(

const std::string &

str

)

Compute a stable string hash.

std::hash has no portability or stability guarantees so is unsuitable where reproducibility is a requirement such as in XML output.

This is the 32-bit FNV-1a algorithm. The algorithm, reference code and constants are all unencumbered. It is fast and has reasonable distribution properties.

https://en.wikipedia.org/wiki/Fowler-Noll-Vo_hash_function

Parameters

str	the string to hash.

Returns

an unsigned 32 bit hash value.

Definition at line 241 of file abg-hash.cc.

get_hashing_state()

hashing::hashing_state get_hashing_state

(

const type_or_decl_base &

tod

)

Get the hashing state of an IR node.

Parameters

tod	the type or decl IR node to get the hashing state for.

Returns

the hashing state of tod.

Definition at line 261 of file abg-hash.cc.

hash() [1/2]

hash_t hash

(

const std::string &

str

)

Hash a string.

Parameters

str	the string to hash.

Returns

the resulting hash value.

Definition at line 219 of file abg-hash.cc.

hash() [2/2]

hash_t hash	(	uint64_t	v,
		uint64_t	seed )

Hash an integer value and combine it with a hash previously computed.

Parameters

v	the value to hash.
seed	a previous hash value that is to be combined with the result of hashing v. This is can be zero if no previous hash value is available.

Returns

the resulting hash value.

Definition at line 196 of file abg-hash.cc.

is_recursive_artefact() [1/2]

bool is_recursive_artefact

(

const type_or_decl_base &

t

)

Test if an artifact is recursive.

For now, a recursive artifact is a type that contains a sub-type that refers to itself.

Parameters

t	the artifact to consider.

Returns

truf iff t is recursive.

Definition at line 302 of file abg-hash.cc.

is_recursive_artefact() [2/2]

void is_recursive_artefact	(	const type_or_decl_base &	t,
		bool	f )

Set the property that flags an artifact as recursive.

For now, a recursive artifact is a type that contains a sub-type that refers to itself.

Parameters

t	the artifact to consider.
f	the new value of the flag. If true, then the artefact t is considered recursive.

Definition at line 327 of file abg-hash.cc.

serialize_hash()

bool serialize_hash	(	uint64_t	hash,
		string &	output )

Serialiaze a hash value computed using the XH64 algorithm (from the xxhash project) into a string of characters representing the digits of the hash in the canonical form requested by the xxhash project. That canonical form is basically a big endian representation of the hexadecimal hash number.

Parameters

hash	the hash number to serialize.
output	the resulting string of characters representing the hash value hash in its serialized form. This is set iff the function return true.

Returns

true iff the function could serialize the hash value hash into a serialized form that is set into the output parameter output.

Definition at line 138 of file abg-hash.cc.

set_hashing_state()

void set_hashing_state	(	const type_or_decl_base &	tod,
		hashing::hashing_state	s )

Set the hashing state of an IR node.

Parameters

tod	the type or decl IR node to set the hashing state for.
s	the new hashing state to set.

Definition at line 280 of file abg-hash.cc.