Cover Class Reference

A description of the topological scope of a single variable object. More...

#include <cover.hh>

Public Member Functions
int4	compareTo (const Cover &op2) const
	Give ordering of this and another Cover. More...
const CoverBlock &	getCoverBlock (int4 i) const
	Get the CoverBlock corresponding to the i-th block. More...
int4	intersect (const Cover &op2) const
	Characterize the intersection between this and another Cover. More...
int4	intersectByBlock (int4 blk, const Cover &op2) const
	Characterize the intersection on a specific block. More...
void	intersectList (vector< int4 > &listout, const Cover &op2, int4 level) const
	Generate a list of blocks that intersect. More...
bool	contain (const PcodeOp *op, int4 max) const
	Does this contain the given PcodeOp. More...
int4	containVarnodeDef (const Varnode *vn) const
	Check the definition of a Varnode for containment. More...
void	merge (const Cover &op2)
	Merge this with another Cover block by block. More...
void	rebuild (const Varnode *vn)
	Reset this based on def-use of a single Varnode. More...
void	addDefPoint (const Varnode *vn)
	Reset to the single point where the given Varnode is defined. More...
void	addRefPoint (const PcodeOp *ref, const Varnode *vn)
	Add a variable read to this Cover. More...
void	print (ostream &s) const
	Dump a description of this cover to stream. More...

Detailed Description

A description of the topological scope of a single variable object.

The topological scope of a variable within a function is the set of locations within the code of the function where that variable holds a variable. For the decompiler, a high-level variable in this sense, HighVariable, is a collection of Varnode objects. In order to merge Varnodes into a HighVariable, the topological scope of each Varnode must not intersect because that would mean the high-level variable holds different values at the same point in the function.

Internally this is implemented as a map from basic block to their non-empty CoverBlock

Member Function Documentation

addDefPoint()

void Cover::addDefPoint

(

const Varnode *

vn

)

Reset to the single point where the given Varnode is defined.

Any previous cover is removed. Calling this with an input Varnode still produces a valid Cover.

Parameters

vn	is the Varnode

addRefPoint()

void Cover::addRefPoint	(	const PcodeOp *	ref,
		const Varnode *	vn
	)

Add a variable read to this Cover.

Given a Varnode being read and the PcodeOp which reads it, add the point of the read to this and recursively fill in backwards until we run into existing cover.

Parameters

ref	is the reading PcodeOp
vn	is the Varnode being read

compareTo()

int4 Cover::compareTo

(

const Cover &

op2

)

const

Give ordering of this and another Cover.

Compare this with another Cover by comparing just the indices of the first blocks respectively that are partly covered. Return -1, 0, or 1 if this Cover's first block has a smaller, equal, or bigger index than the other Cover's first block.

Parameters

op2	is the other Cover

Returns

the comparison value

contain()

bool Cover::contain	(	const PcodeOp *	op,
		int4	max
	)		const

Does this contain the given PcodeOp.

Parameters

op	is the given PcodeOp
max	is 1 to test for any containment, 2 to force interior containment

Returns

true if there is containment

containVarnodeDef()

int4 Cover::containVarnodeDef

(

const Varnode *

vn

)

const

Check the definition of a Varnode for containment.

If the given Varnode has a defining PcodeOp this is checked for containment. If the Varnode is an input, check if this covers the start of the function.

Return:

• 0 if cover does not contain varnode definition
• 1 if there if it is contained in interior
• 2 if the defining points intersect
• 3 if Cover's tail is the varnode definition

Parameters

vn	is the given Varnode

Returns

the containment characterization

getCoverBlock()

const CoverBlock & Cover::getCoverBlock

(

int4

i

)

const

Get the CoverBlock corresponding to the i-th block.

Return a representative CoverBlock describing how much of the given block is covered by this

Parameters

i	is the index of the given block

Returns

a reference to the corresponding CoverBlock

intersect()

int4 Cover::intersect

(

const Cover &

op2

)

const

Characterize the intersection between this and another Cover.

Return

• 0 if there is no intersection
• 1 if the only intersection is on a boundary point
• 2 if the intersection contains a range of p-code ops

Parameters

op2	is the other Cover

Returns

the intersection characterization

intersectByBlock()

int4 Cover::intersectByBlock	(	int4	blk,
		const Cover &	op2
	)		const

Characterize the intersection on a specific block.

Looking only at the given block, Return

• 0 if there is no intersection
• 1 if the only intersection is on a boundary point
• 2 if the intersection contains a range of p-code ops

Parameters

blk	is the index of the given block
op2	is the other Cover

Returns

the characterization

intersectList()

void Cover::intersectList	(	vector< int4 > &	listout,
		const Cover &	op2,
		int4	level
	)		const

Generate a list of blocks that intersect.

For each block for which this and another Cover intersect, and the block's index to a result list if the type of intersection exceeds a characterization level.

Parameters

listout	will hold the list of intersecting block indices
op2	is the other Cover
level	is the characterization threshold which must be exceeded

merge()

void Cover::merge

(

const Cover &

op2

)

Merge this with another Cover block by block.

Parameters

op2	is the other Cover

print()

void Cover::print

(

ostream &

s

)

const

Dump a description of this cover to stream.

Parameters

s	is the output stream

rebuild()

void Cover::rebuild

(

const Varnode *

vn

)

Reset this based on def-use of a single Varnode.

The cover is set to all p-code ops between the point where the Varnode is defined and all the points where it is read

Parameters

vn	is the single Varnode

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

• cover.hh
• cover.cc