Class BetterCFGBuilder2

java.lang.Object

edu.umd.cs.findbugs.ba.BetterCFGBuilder2

All Implemented Interfaces:

CFGBuilder, Debug, EdgeTypes

public class BetterCFGBuilder2
extends Object
implements CFGBuilder, EdgeTypes, Debug

A CFGBuilder that really tries to construct accurate control flow graphs. The CFGs it creates have accurate exception edges, and have accurately inlined JSR subroutines.

See Also:

• CFG

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	BetterCFGBuilder2.Context	Inlining context.
private static class	BetterCFGBuilder2.EscapeTarget	A placeholder for a control edge that escapes its subroutine to return control back to an outer (calling) subroutine.
private class	BetterCFGBuilder2.Subroutine	JSR subroutine.
private static class	BetterCFGBuilder2.WorkListItem	A work list item for creating the CFG for a subroutine.

Field Summary

Fields

Modifier and Type	Field	Description
private final Map<FieldDescriptor, Integer>	addedFields
private final Map<MethodDescriptor, Integer>	addedMethods
private CFG	cfg
private final org.apache.bcel.generic.ConstantPoolGen	cpg
private static final boolean	DEBUG
private final ExceptionHandlerMap	exceptionHandlerMap
private final IdentityHashMap<org.apache.bcel.generic.InstructionHandle, BetterCFGBuilder2.Subroutine>	jsrSubroutineMap
private final org.apache.bcel.generic.MethodGen	methodGen
private final LinkedList<BetterCFGBuilder2.Subroutine>	subroutineWorkList
private BetterCFGBuilder2.Subroutine	topLevelSubroutine
private final BitSet	usedInstructionSet

Fields inherited from interface Debug

VERIFY_INTEGRITY

Fields inherited from interface EdgeTypes

BACKEDGE_SOURCE_EDGE, BACKEDGE_TARGET_EDGE, CHECKED_EXCEPTIONS_FLAG, EXIT_EDGE, EXPLICIT_EXCEPTIONS_FLAG, FALL_THROUGH_EDGE, GOTO_EDGE, HANDLED_EXCEPTION_EDGE, IFCMP_EDGE, JSR_EDGE, RET_EDGE, RETURN_EDGE, START_EDGE, SWITCH_DEFAULT_EDGE, SWITCH_EDGE, UNHANDLED_EXCEPTION_EDGE, UNKNOWN_EDGE

Constructor Summary

Constructors

Constructor	Description
BetterCFGBuilder2(MethodDescriptor descriptor, org.apache.bcel.generic.MethodGen methodGen)	Constructor.

Method Summary

Modifier and Type	Method	Description
void	build()	Build the CFG.
private void	build(BetterCFGBuilder2.Subroutine subroutine)	Build a subroutine.
CFG	getCFG()	Get the CFG built by this object.
int	getIndex(FieldDescriptor f)
private int	getIndex(MethodDescriptor method)
private void	handleExceptions(BetterCFGBuilder2.Subroutine subroutine, org.apache.bcel.generic.InstructionHandle pei, BasicBlock etb)	Add exception edges for given instruction.
void	inline(BetterCFGBuilder2.Context context)	Inline a subroutine into a calling context.
private CFG	inlineAll()	Inline all JSR subroutines into the top-level subroutine.
private static boolean	isMerge(org.apache.bcel.generic.InstructionHandle handle)	Determine whether or not the given instruction is a control flow merge.
private boolean	isPEI(org.apache.bcel.generic.InstructionHandle handle)	Return whether or not the given instruction can throw exceptions.
private boolean	isSafeFieldSource(org.apache.bcel.generic.InstructionHandle handle)
static void	main(String[] argv)	Test driver.
void	optimize(org.apache.bcel.generic.InstructionList instructionList)

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

DEBUG

private static final boolean DEBUG

methodGen

private final org.apache.bcel.generic.MethodGen methodGen

cpg

private final org.apache.bcel.generic.ConstantPoolGen cpg

exceptionHandlerMap

private final ExceptionHandlerMap exceptionHandlerMap

usedInstructionSet

private final BitSet usedInstructionSet

subroutineWorkList

private final LinkedList<BetterCFGBuilder2.Subroutine> subroutineWorkList

jsrSubroutineMap

private final IdentityHashMap<org.apache.bcel.generic.InstructionHandle, BetterCFGBuilder2.Subroutine> jsrSubroutineMap

addedFields

private final Map<FieldDescriptor, Integer> addedFields

addedMethods

private final Map<MethodDescriptor, Integer> addedMethods

topLevelSubroutine

private BetterCFGBuilder2.Subroutine topLevelSubroutine

cfg

private CFG cfg

Constructor Details

BetterCFGBuilder2

public BetterCFGBuilder2(@Nonnull
 MethodDescriptor descriptor,
 @Nonnull
 org.apache.bcel.generic.MethodGen methodGen)

Constructor.

Parameters:

methodGen - the method to build a CFG for

Method Details

getIndex

public int getIndex(FieldDescriptor f)

getIndex

private int getIndex(MethodDescriptor method)

optimize

public void optimize(org.apache.bcel.generic.InstructionList instructionList)

build

public void build()
           throws CFGBuilderException

Description copied from interface: CFGBuilder

Build the CFG.

Specified by:

build in interface CFGBuilder

Throws:

CFGBuilderException

getCFG

public CFG getCFG()

Description copied from interface: CFGBuilder

Get the CFG built by this object. Assumes that the build() method has already been called.

Specified by:

getCFG in interface CFGBuilder

Returns:

the CFG

build

private void build(BetterCFGBuilder2.Subroutine subroutine)
            throws CFGBuilderException

Build a subroutine. We iteratively add basic blocks to the subroutine until there are no more blocks reachable from the calling context. As JSR instructions are encountered, new Subroutines are added to the subroutine work list.

Parameters:

subroutine - the subroutine

Throws:

CFGBuilderException

handleExceptions

private void handleExceptions(BetterCFGBuilder2.Subroutine subroutine,
 org.apache.bcel.generic.InstructionHandle pei,
 BasicBlock etb)

Add exception edges for given instruction.

Parameters:

subroutine - the subroutine containing the instruction

pei - the instruction which throws an exception

etb - the exception thrower block (ETB) for the instruction

isPEI

private boolean isPEI(org.apache.bcel.generic.InstructionHandle handle)
               throws CFGBuilderException

Return whether or not the given instruction can throw exceptions.

Parameters:

handle - the instruction

Returns:

true if the instruction can throw an exception, false otherwise

Throws:

CFGBuilderException

isSafeFieldSource

private boolean isSafeFieldSource(org.apache.bcel.generic.InstructionHandle handle)

Parameters:

handle - instruction handle which loads the object for further GETFIELD/PUTFIELD operation

Returns:

true if this object is known to be non-null

isMerge

private static boolean isMerge(org.apache.bcel.generic.InstructionHandle handle)

Determine whether or not the given instruction is a control flow merge.

Parameters:

handle - the instruction

Returns:

true if the instruction is a control merge, false otherwise

inlineAll

private CFG inlineAll()
               throws CFGBuilderException

Inline all JSR subroutines into the top-level subroutine. This produces a complete CFG for the entire method, in which all JSR subroutines are inlined.

Returns:

the CFG for the method

Throws:

CFGBuilderException

inline

public void inline(BetterCFGBuilder2.Context context)
            throws CFGBuilderException

Inline a subroutine into a calling context.

Parameters:

context - the Context

Throws:

CFGBuilderException

main

public static void main(String[] argv)
                 throws Exception

Test driver.

Throws:

Exception