A high-level variable modeled as a list of low-level variables, each written once. More...

#include <variable.hh>

Public Types
enum	{ flagsdirty = 1, namerepdirty = 2, typedirty = 4, coverdirty = 8, symboldirty = 0x10, copy_in1 = 0x20, copy_in2 = 0x40, type_finalized = 0x80, unmerged = 0x100 }
	Dirtiness flags for a HighVariable. More...

Public Member Functions
	HighVariable (Varnode *vn)
	Construct a HighVariable with a single member Varnode. More...

SymbolEntry *	getSymbolEntry (void) const

void	finalizeDatatype (Datatype *tp)
	Set a final datatype for this variable. More...

void	printCover (ostream &s) const
	Print details of the cover for this (for debug purposes) More...

void	printInfo (ostream &s) const
	Print information about this HighVariable to stream. More...

bool	hasName (void) const
	Check if this HighVariable can be named. More...

Varnode *	getTiedVarnode (void) const
	Find the first address tied member Varnode. More...

Varnode *	getInputVarnode (void) const
	Find (the) input member Varnode. More...

Varnode *	getTypeRepresentative (void) const
	Get a member Varnode with the strongest data-type. More...

Varnode *	getNameRepresentative (void) const
	Get a member Varnode that dictates the naming of this HighVariable. More...

bool	hasCover (void) const
	Determine if this HighVariable has an associated cover. More...

void	saveXml (ostream &s) const
	Save the variable to stream as an XML <high> tag. More...

Static Public Member Functions
static bool	compareName (Varnode vn1, Varnode vn2)
	Determine which given Varnode is most nameable. More...

static bool	compareJustLoc (const Varnode a, const Varnode b)
	Compare based on storage location. More...

static int4	markExpression (Varnode vn, vector< HighVariable > &highList)
	Mark and collect variables in expression. More...

Friends
class	Varnode

class	Merge

Detailed Description

A high-level variable modeled as a list of low-level variables, each written once.

In the Static Single Assignment (SSA) representation of a function's data-flow, the Varnode object represents a variable node. This is a low-level variable: it is written to at most once, and there is 1 or more reads. A high-level variable, in the source language may be written to multiple times. We model this idea as a list of Varnode objects, where a different Varnode holds the value of the variable for different parts of the code. The range(s) of code for which a single Varnode holds the high-level variable's value is the cover or range of that Varnode and is modeled by the class Cover. Within a high-level variable, HighVariable, the covers of member Varnode objects should not intersect, as that represents the variable holding two or more different values at the same place in the code. The HighVariable inherits a cover which is the union of the covers of its Varnodes.

Member Enumeration Documentation

◆ anonymous enum

anonymous enum

Dirtiness flags for a HighVariable.

The HighVariable inherits its Cover, its data-type, and other boolean properties from its Varnodes. The object holds these explicitly, but the values may become stale as the data-flow transforms. So we keep track of when these inherited values are dirty

Enumerator
flagsdirty	Boolean properties for the HighVariable are dirty.
namerepdirty	The name representative for the HighVariable is dirty.
typedirty	The data-type for the HighVariable is dirty.
coverdirty	The cover for the HighVariable is dirty.
symboldirty	The symbol attachment is dirty.
copy_in1	There exists at least 1 COPY into this HighVariable from other HighVariables.
copy_in2	There exists at least 2 COPYs into this HighVariable from other HighVariables.
type_finalized	Set if a final data-type is locked in and dirtying is disabled.
unmerged	Set if part of a multi-entry Symbol but did not get merged with other SymbolEntrys.

Constructor & Destructor Documentation

◆ HighVariable()

HighVariable::HighVariable ( Varnode * vn )

Construct a HighVariable with a single member Varnode.

The new instance starts off with no associate Symbol and all properties marked as dirty.

Parameters

vn	is the single Varnode member

Member Function Documentation

◆ compareJustLoc()

bool HighVariable::compareJustLoc	(	const Varnode *	a,
		const Varnode *	b
	)

static

Compare based on storage location.

Compare two Varnode objects based just on their storage address

Parameters

a	is the first Varnode to compare
b	is the second Varnode

Returns: true if the first Varnode should be ordered before the second

◆ compareName()

bool HighVariable::compareName	(	Varnode *	vn1,
		Varnode *	vn2
	)

static

Determine which given Varnode is most nameable.

Given two Varnode (members), sort them based on naming properties:

A Varnode with an assigned name is preferred
An unaffected Varnode is preferred
A global Varnode is preferred
An input Varnode is preferred
An address tied Varnode is preferred
A non-temporary Varnode is preferred
A written Varnode is preferred
An earlier Varnode is preferred

Returns: true if the second Varnode's name would override the first's

◆ finalizeDatatype()

void HighVariable::finalizeDatatype ( Datatype * tp )

Set a final datatype for this variable.

The data-type its dirtying mechanism is disabled. The data-type will not change, unless this method is called again.

Parameters

tp	is the data-type to set

◆ getInputVarnode()

Varnode * HighVariable::getInputVarnode ( void ) const

Find (the) input member Varnode.

This should only be called if isInput() returns true. If there is no input member, this will throw an exception.

Returns: the input Varnode member

◆ getNameRepresentative()

Varnode * HighVariable::getNameRepresentative ( void ) const

Get a member Varnode that dictates the naming of this HighVariable.

Members are scored based the properties that are most dominating in choosing a name.

Returns: the highest scoring Varnode member

◆ getSymbolEntry()

SymbolEntry * HighVariable::getSymbolEntry ( void ) const

Assuming there is a Symbol attached to this, run through the Varnode members until we find one with a SymbolEntry corresponding to the Symbol and return it.

Returns: the SymbolEntry that mapped the Symbol to this or null if no Symbol is attached

◆ getTiedVarnode()

Varnode * HighVariable::getTiedVarnode ( void ) const

Find the first address tied member Varnode.

This should only be called if isAddrTied() returns true. If there is no address tied member, this will throw an exception.

Returns: the first address tied member

◆ getTypeRepresentative()

Varnode * HighVariable::getTypeRepresentative ( void ) const

Get a member Varnode with the strongest data-type.

Find the member Varnode with the most specialized data-type, handling bool specially. Boolean data-types are specialized in the data-type lattice, but not all byte values are boolean values. Within the Varnode/PcodeOp tree, the bool data-type can only propagate to a Varnode if it is verified to only take the boolean values 0 and 1. Since the data-type representative represents the type of all instances, if any instance is not boolean, then the HighVariable cannot be boolean, even though bool is more specialized. This method uses Datatype::typeOrderBool() to implement the special handling.

Returns: the representative member

◆ hasCover()

bool HighVariable::hasCover ( void ) const

inline

Determine if this HighVariable has an associated cover.

Constant and annotation variables do not have a cover

Returns: true if this has a cover

◆ hasName()

bool HighVariable::hasName ( void ) const

Check if this HighVariable can be named.

All Varnode objects are assigned a HighVariable, including those that don't get names like indirect variables, constants, and annotations. Determine if this, as inherited from its member Varnodes, can have a name.

Returns: true if this can have a name

◆ markExpression()

int4 HighVariable::markExpression	(	Varnode *	vn,
		vector< HighVariable * > &	highList
	)

static

Mark and collect variables in expression.

Given a Varnode at the root of an expression, we collect all the explicit HighVariables involved in the expression. This should only be run after explicit and implicit properties have been computed on Varnodes. The expression is traced back from the root until explicit Varnodes are encountered; then their HighVariable is marked and added to the list. The routine returns a value based on PcodeOps encountered in the expression:

1 for call instructions
2 for LOAD instructions
3 for both call and LOAD
0 for no calls or LOADS

Parameters

vn	is the given root Varnode of the expression
highList	will hold the collected HighVariables

Returns: a value based on call and LOAD instructions in the expression

◆ printCover()

void HighVariable::printCover ( ostream & s ) const

inline

Print details of the cover for this (for debug purposes)

Parameters

s	is the output stream

◆ printInfo()

void HighVariable::printInfo ( ostream & s ) const

Print information about this HighVariable to stream.

This is generally used for debug purposes.

Parameters

s	is the output stream

◆ saveXml()

void HighVariable::saveXml ( ostream & s ) const

Save the variable to stream as an XML <high> tag.

Parameters

s	is the output stream to write XML to

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

variable.hh
variable.cc

Public Types

Public Member Functions

Static Public Member Functions

Friends

Detailed Description

Member Enumeration Documentation

◆ anonymous enum

Constructor & Destructor Documentation

◆ HighVariable()

Member Function Documentation

◆ compareJustLoc()

◆ compareName()

◆ finalizeDatatype()

◆ getInputVarnode()

◆ getNameRepresentative()

◆ getSymbolEntry()

◆ getTiedVarnode()

◆ getTypeRepresentative()

◆ hasCover()

◆ hasName()

◆ markExpression()

◆ printCover()

◆ printInfo()

◆ saveXml()