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java.lang.Objectsoot.toolkits.graph.UnitGraph
soot.toolkits.graph.ExceptionalUnitGraph
public class ExceptionalUnitGraph
Represents a control flow graph for a Body instance
where the nodes are Unit instances, and where control flow
associated with exceptions is taken into account.
To describe precisely the circumstances under which exceptional
edges are added to the graph, we need to distinguish the
exceptions thrown explicitly by a throw instruction
from the exceptions which are thrown implicitly by the VM to
signal an error it encounters in the course of executing
an instruction, which need not be a throw.
For every ThrowInst or ThrowStmt
Unit which may explicitly throw an exception that
would be caught by a Trap in the Body, there
will be an edge from the throw Unit to
the Trap handler's first Unit.
For every Unit which may implicitly throw an
exception that could be caught by a Trap in the
Body, there will be an edge from each of the
excepting Unit's predecessors to the
Trap handler's first Unit (since any of
those predecessors may have been the last Unit to
complete execution before the handler starts execution). If the
excepting Unit might have the side effect of changing
some field, then there will definitely be an edge from the excepting
Unit itself to its handlers, since the side effect
might occur before the exception is raised. If the excepting
Unit has no side effects, then parameters passed to
the ExceptionalUnitGraph constructor determine
whether or not there is an edge from the excepting
Unit itself to the handler Unit.
| Nested Class Summary | |
|---|---|
static class |
ExceptionalUnitGraph.ExceptionDest
|
| Field Summary | |
|---|---|
protected ThrowAnalysis |
throwAnalysis
|
protected Map<Unit,List<Unit>> |
unitToExceptionalPreds
|
protected Map<Unit,List<Unit>> |
unitToExceptionalSuccs
|
protected Map<Unit,Collection<ExceptionalUnitGraph.ExceptionDest>> |
unitToExceptionDests
|
protected Map<Unit,List<Unit>> |
unitToUnexceptionalPreds
|
protected Map<Unit,List<Unit>> |
unitToUnexceptionalSuccs
|
| Fields inherited from class soot.toolkits.graph.UnitGraph |
|---|
body, heads, method, tails, unitChain, unitToPreds, unitToSuccs |
| Constructor Summary | |
|---|---|
|
ExceptionalUnitGraph(Body body)
Constructs the graph from a given Body instance, using the Scene's default ThrowAnalysis to estimate the
set of exceptions that each Unit might throw and a
default value, provided by the Options class, for the
omitExceptingUnitEdges parameter. |
protected |
ExceptionalUnitGraph(Body body,
boolean ignoredBogusParameter)
Allocates an ExceptionalUnitGraph object
without initializing it. |
|
ExceptionalUnitGraph(Body body,
ThrowAnalysis throwAnalysis)
Constructs the graph from a given Body instance using the passed ThrowAnalysis and a default value, provided by
the Options class, for the
omitExceptingUnitEdges parameter. |
|
ExceptionalUnitGraph(Body body,
ThrowAnalysis throwAnalysis,
boolean omitExceptingUnitEdges)
Constructs the graph for a given Body instance, using the ThrowAnalysis and omitExceptingUnitEdges
value that are passed as parameters. |
| Method Summary | |
|---|---|
protected Set<Unit> |
buildExceptionalEdges(ThrowAnalysis throwAnalysis,
Map<Unit,Collection<ExceptionalUnitGraph.ExceptionDest>> unitToExceptionDests,
Map<Unit,List<Unit>> unitToSuccs,
Map<Unit,List<Unit>> unitToPreds,
boolean omitExceptingUnitEdges)
Method to compute the edges corresponding to exceptional control flow. |
protected Map<Unit,Collection<ExceptionalUnitGraph.ExceptionDest>> |
buildExceptionDests(ThrowAnalysis throwAnalysis)
Utility method used in the construction of UnitGraph
variants which include exceptional control flow. |
protected void |
buildHeadsAndTails()
A placeholder that overrides UnitGraph.buildHeadsAndTails()
with a method which always throws an exception. |
List<Unit> |
getExceptionalPredsOf(Unit u)
Returns a list of nodes which are predecessors of a given node when only exceptional control flow is considered. |
List<Unit> |
getExceptionalSuccsOf(Unit u)
Returns a list of nodes which are successors of a given node when only exceptional control flow is considered. |
Collection<ExceptionalUnitGraph.ExceptionDest> |
getExceptionDests(Unit u)
Returns a collection of ExceptionDest
objects which represent how exceptions thrown by a specified
unit will be handled. |
List<Unit> |
getUnexceptionalPredsOf(Unit u)
Returns a list of nodes which are predecessors of a given node when only unexceptional control flow is considered. |
List<Unit> |
getUnexceptionalSuccsOf(Unit u)
Returns a list of nodes which are successors of a given node when only unexceptional control flow is considered. |
protected void |
initialize(ThrowAnalysis throwAnalysis,
boolean omitExceptingUnitEdges)
Performs the real work of constructing an ExceptionalUnitGraph, factored out of the
constructors so that subclasses have the option to delay
creating the graph's edges until after they have performed
some subclass-specific initialization. |
String |
toString()
|
| Methods inherited from class soot.toolkits.graph.UnitGraph |
|---|
addEdge, buildUnexceptionalEdges, combineMapValues, getBody, getExtendedBasicBlockPathBetween, getHeads, getPredsOf, getSuccsOf, getTails, iterator, makeMappedListsUnmodifiable, size |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
| Methods inherited from interface soot.toolkits.graph.ExceptionalGraph |
|---|
getBody |
| Methods inherited from interface soot.toolkits.graph.DirectedGraph |
|---|
getHeads, getPredsOf, getSuccsOf, getTails, iterator, size |
| Field Detail |
|---|
protected Map<Unit,List<Unit>> unitToUnexceptionalSuccs
protected Map<Unit,List<Unit>> unitToUnexceptionalPreds
protected Map<Unit,List<Unit>> unitToExceptionalSuccs
protected Map<Unit,List<Unit>> unitToExceptionalPreds
protected Map<Unit,Collection<ExceptionalUnitGraph.ExceptionDest>> unitToExceptionDests
protected ThrowAnalysis throwAnalysis
| Constructor Detail |
|---|
public ExceptionalUnitGraph(Body body,
ThrowAnalysis throwAnalysis,
boolean omitExceptingUnitEdges)
ThrowAnalysis and omitExceptingUnitEdges
value that are passed as parameters.
body - the Body from which to build a graph.throwAnalysis - the source of information about the exceptions
which each Unit may throw.omitExceptingUnitEdges - indicates whether the CFG should
omit edges to a handler from trapped
Units which may implicitly throw an
exception which the handler catches but
which have no potential side effects.
The CFG will contain edges to the handler
from all predecessors of
Units which may implicitly throw
a caught exception regardless of the setting for
this parameter. If this parameter is
false, there will also be
edges to the handler from all the
potentially excepting Units
themselves. If this parameter is
true, there will be edges to
the handler from the excepting
Units themselves only if they
have potential side effects (or if they
are themselves the predecessors of other
potentially excepting Units).
A setting of true produces
CFGs which allow for more precise
analyses, since a Unit without
side effects has no effect on the
computational state when it throws an
exception. Use settings of
false for compatibility with
more conservative analyses, or to cater
to conservative bytecode verifiers.
public ExceptionalUnitGraph(Body body,
ThrowAnalysis throwAnalysis)
ThrowAnalysis and a default value, provided by
the Options class, for the
omitExceptingUnitEdges parameter.
body - the Body from which to build a graph.throwAnalysis - the source of information about the exceptions
which each Unit may throw.public ExceptionalUnitGraph(Body body)
Scene's default ThrowAnalysis to estimate the
set of exceptions that each Unit might throw and a
default value, provided by the Options class, for the
omitExceptingUnitEdges parameter.
body - the Body from which to build a graph.
protected ExceptionalUnitGraph(Body body,
boolean ignoredBogusParameter)
Allocates an ExceptionalUnitGraph object
without initializing it. This “partial
constructor” is provided for the benefit of subclasses
whose constructors need to perform some subclass-specific
processing before actually creating the graph edges (because,
for example, the subclass overrides a utility method like
buildExceptionDests(ThrowAnalysis) or buildExceptionalEdges(ThrowAnalysis, Map, Map, Map, boolean)
with a replacement method that depends on additional
parameters passed to the subclass's constructor). The
subclass constructor is responsible for calling initialize(ThrowAnalysis, boolean), or otherwise performing
the initialization required to implement
ExceptionalUnitGraph's interface.
Clients who opt to extend ExceptionalUnitGraph
should be warned that the class has not been carefully
designed for inheritance; code that uses the
protected members of this class may need to be
rewritten for each new Soot release.
body - the Body from which to build a graph.ignoredBogusParameter - a meaningless placeholder, which exists
solely to distinguish this
constructor from the public
ExceptionalUnitGraph(Body)
constructor.| Method Detail |
|---|
protected void initialize(ThrowAnalysis throwAnalysis,
boolean omitExceptingUnitEdges)
ExceptionalUnitGraph, factored out of the
constructors so that subclasses have the option to delay
creating the graph's edges until after they have performed
some subclass-specific initialization.
throwAnalysis - the source of information about the exceptions
which each Unit may throw.omitExceptingUnitEdges - indicates whether the CFG should
omit edges to a handler from trapped
Units which may throw an
exception which the handler catches but
which have no potential side effects.protected Map<Unit,Collection<ExceptionalUnitGraph.ExceptionDest>> buildExceptionDests(ThrowAnalysis throwAnalysis)
Utility method used in the construction of
UnitGraph
variants which include exceptional control flow. It determines
which Units may throw exceptions that would be caught
by Traps within the method.
throwAnalysis - The source of information about which
exceptions each Unit may throw.
null if no Units in the method throw
any exceptions caught within the method. Otherwise, a
Map from Units to Collections of ExceptionalUnitGraph.ExceptionDests.
The returned map has an idiosyncracy which is hidden
from most client code, but which is exposed to
subclasses extending ExceptionalUnitGraph.
If a Unit throws one or more exceptions
which are caught within the method, it will be mapped
to a Collection of
ExceptionDests describing the sets of
exceptions that the Unit might throw to
each Trap. But if all of a Unit's
exceptions escape the method, it will be mapped to
nullCollection containing a single
ExceptionDest with a null
trap. (The special case for Units with
no caught exceptions allows
buildExceptionDests() to ignore completely
Units which are outside the scope of all
Traps.)
protected Set<Unit> buildExceptionalEdges(ThrowAnalysis throwAnalysis,
Map<Unit,Collection<ExceptionalUnitGraph.ExceptionDest>> unitToExceptionDests,
Map<Unit,List<Unit>> unitToSuccs,
Map<Unit,List<Unit>> unitToPreds,
boolean omitExceptingUnitEdges)
throwAnalysis - the source of information about the exceptions
which each Unit may throw.unitToExceptionDests2 - A Map from Units to
Collections of ExceptionDests which represent the handlers
that might catch exceptions thrown by the
Unit. This is an ``in
parameter''.unitToSuccs - A Map from Units to
Lists of Units. This is
an ``out parameter'';
buildExceptionalEdges will add
a mapping from every Unit in
the body that may throw an exception that
could be caught by a Trap in the
body to a list of its exceptional
successors.unitToPreds - A Map from Units to
Lists of
Units. This is an ``out
parameter'';
buildExceptionalEdges will add
a mapping from each handler unit that may
catch an exception to the list of
Units whose exceptions it may
catch.omitExceptingUnitEdges - Indicates whether to omit
exceptional edges from excepting units which
lack side effects
Set of trap Units that might catch
exceptions thrown by the first Unit in the
Body associated with the graph being
constructed. Such trap Units may need to
be added to the list of heads (depending on your
definition of heads), since they can be the first
Unit in the Body which
actually completes execution.
protected void buildHeadsAndTails()
throws IllegalStateException
A placeholder that overrides UnitGraph.buildHeadsAndTails()
with a method which always throws an exception. The placeholder serves
to indicate that ExceptionalUnitGraph does not use
buildHeadsAndTails(), and to document the conditions under
which ExceptionalUnitGraph considers a node to be a head or
tail.
ExceptionalUnitGraph defines the graph's set of
heads to include the first Unit in the graph's body,
together with the first Unit in any exception
handler which might catch an exception thrown by the first
Unit in the body (because any of those
Units might be the first to successfully complete
execution). ExceptionalUnitGraph defines the
graph's set of tails to include all Units which
represent some variety of return bytecode or an
athrow bytecode whose argument might escape the
method.
buildHeadsAndTails in class UnitGraphIllegalStateExceptionpublic Collection<ExceptionalUnitGraph.ExceptionDest> getExceptionDests(Unit u)
ExceptionDest
objects which represent how exceptions thrown by a specified
unit will be handled.
getExceptionDests in interface ExceptionalGraph<Unit>u - The unit for which to provide exception information.
(u must be a Unit, though the parameter is
declared as an Object to satisfy the interface of
ExceptionalGraph.
ExceptionDest objects describing
the traps, if any, which catch the exceptions
which may be thrown by u.public List<Unit> getUnexceptionalPredsOf(Unit u)
ExceptionalGraph
getUnexceptionalPredsOf in interface ExceptionalGraph<Unit>u - The node whose predecessors are to be returned.
List of the nodes in this graph from which
there is an unexceptional edge to n.public List<Unit> getUnexceptionalSuccsOf(Unit u)
ExceptionalGraph
getUnexceptionalSuccsOf in interface ExceptionalGraph<Unit>u - The node whose successors are to be returned.
List of nodes in this graph to which
there is an unexceptional edge from n.public List<Unit> getExceptionalPredsOf(Unit u)
ExceptionalGraph
getExceptionalPredsOf in interface ExceptionalGraph<Unit>u - The node whose predecessors are to be returned.
List of nodes in this graph from which
there is an exceptional edge to n.public List<Unit> getExceptionalSuccsOf(Unit u)
ExceptionalGraph
getExceptionalSuccsOf in interface ExceptionalGraph<Unit>u - The node whose successors are to be returned.
List of nodes in this graph to which
there is an exceptional edge from n.public String toString()
toString in class UnitGraph
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