Class Verifier

java.lang.Object

com.ibm.wala.shrike.shrikeBT.analysis.Analyzer

com.ibm.wala.shrike.shrikeBT.analysis.Verifier

public final class Verifier
extends Analyzer

This class typechecks intermediate code. It's very easy to use:

     MethodData md = ...;
     try {
         (new Verifier(md)).verify();
     } catch (Verifier.FailureException ex) {
         System.out.println("Verification failed at instruction "
             + ex.getOffset() + ": " + ex.getReason());
     }

For full verification you need to provide class hierarchy information using setClassHierarchy. Without this information, we can't compute the exact types of variables at control flow merge points. If you don't provide a hierarchy, or the hierarchy you provide is partial, then the Verifier will be optimistic.

This method can also be used to gather type information for every stack and local variable at every program point. Just call computeTypes() instead of verify() and then retrieve the results with getLocalTypes() and getStackTypes().

Nested Class Summary

Nested classes/interfaces inherited from class Analyzer

Analyzer.FailureException, Analyzer.PathElement, Analyzer.TypeVisitor

Modifier and Type	Class	Description
static final class	Analyzer.FailureException	This exception is thrown by verify() when it fails.
static final class	Analyzer.PathElement
static class	Analyzer.TypeVisitor

Field Summary

Fields inherited from class Analyzer

backEdges, basicBlockStarts, classType, handlers, hierarchy, instructions, instToBC, isConstructor, isStatic, locals, maxLocals, maxStack, noEdges, noStrings, signature, stacks, stackSizes, thisType, topType, varTypes

Modifier and Type	Field	Description
protected int[][]	backEdges
protected BitSet	basicBlockStarts
protected final String	classType
protected final ExceptionHandler[][]	handlers
protected ClassHierarchyProvider	hierarchy
protected final IInstruction[]	instructions
protected int[]	instToBC
protected final boolean	isConstructor
protected final boolean	isStatic
protected String[][]	locals
protected int	maxLocals
protected int	maxStack
protected static final int[]	noEdges
protected static final String[]	noStrings
protected final String	signature
protected String[][]	stacks
protected int[]	stackSizes
static final String	thisType
static final String	topType
protected String[][]	varTypes

Constructor Summary

Constructors

Constructor	Description
Verifier(boolean isConstructor, boolean isStatic, String classType, String signature, IInstruction[] instructions, ExceptionHandler[][] handlers, int[] instToBC, String[][] vars)	Initialize a verifier.
Verifier(MethodData info)	Initialize a verifier.
Verifier(MethodData info, int[] instToBC, String[][] vars)

Method Summary

Modifier and Type	Method	Description
void	computeTypes()
void	verify()	Try to verify the method.
void	verifyCollectAll()

Methods inherited from class Analyzer

computeTypes, createAnalyzer, findCommonSupertype, getBackEdges, getBasicBlockStarts, getInstructions, getLocalTypes, getReachableFrom, getReachableFrom, getReachableFromUpdate, getReachingToUpdate, getStackSizes, getStackTypes, initTypeInfo, isSubtypeOf, setClassHierarchy, stripSharp

Modifier and Type	Method	Description
final void	computeTypes(Analyzer.TypeVisitor v, BitSet makeTypesAt, boolean wantPath)	Verify the method and compute types at every program point.
static Analyzer	createAnalyzer(MethodData info)
final String	findCommonSupertype(String t1, String t2)
final int[][]	getBackEdges()
final BitSet	getBasicBlockStarts()
final IInstruction[]	getInstructions()
final String[][]	getLocalTypes()
final BitSet	getReachableFrom(int from)
final BitSet	getReachableFrom(int from, boolean followHandlers, BitSet mask)
final void	getReachableFromUpdate(int from, BitSet reachable, boolean followHandlers, BitSet mask)
final void	getReachingToUpdate(int to, BitSet reaching, BitSet mask)
int[]	getStackSizes()
final String[][]	getStackTypes()
protected final void	initTypeInfo()
final boolean	isSubtypeOf(String t1, String t2)
final void	setClassHierarchy(ClassHierarchyProvider h)	Use class hierarchy information in 'h'.
static String	stripSharp(String type)

Methods inherited from class Object

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

Constructor Details

Verifier

public Verifier(boolean isConstructor,
 boolean isStatic,
 String classType,
 String signature,
 IInstruction[] instructions,
 ExceptionHandler[][] handlers,
 int[] instToBC,
 String[][] vars)

Initialize a verifier.

Verifier

public Verifier(MethodData info)
         throws NullPointerException

Initialize a verifier.

Throws:

NullPointerException - if info is null

Verifier

public Verifier(MethodData info,
 int[] instToBC,
 String[][] vars)
         throws NullPointerException

Throws:

NullPointerException

Method Details

verify

public void verify()
            throws Analyzer.FailureException

Try to verify the method. If verification is unsuccessful, we throw an exception.

Throws:

Analyzer.FailureException - the method contains invalid bytecode

verifyCollectAll

public void verifyCollectAll()
                      throws Analyzer.FailureException

Throws:

Analyzer.FailureException

computeTypes

public void computeTypes()
                  throws Analyzer.FailureException

Throws:

Analyzer.FailureException