/*******************************************************************************
* Copyright (c) 2002 - 2006 IBM Corporation.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package com.ibm.wala.ipa.callgraph.propagation.cfa;
import com.ibm.wala.classLoader.CallSiteReference;
import com.ibm.wala.classLoader.IClass;
import com.ibm.wala.classLoader.IMethod;
import com.ibm.wala.ipa.callgraph.CGNode;
import com.ibm.wala.ipa.callgraph.Context;
import com.ibm.wala.ipa.callgraph.ContextSelector;
import com.ibm.wala.ipa.callgraph.propagation.AllocationSiteInNode;
import com.ibm.wala.ipa.callgraph.propagation.ContainerUtil;
import com.ibm.wala.ipa.callgraph.propagation.InstanceKey;
import com.ibm.wala.ipa.callgraph.propagation.ReceiverInstanceContext;
import com.ibm.wala.ipa.cha.IClassHierarchy;
import com.ibm.wala.types.ClassLoaderReference;
import com.ibm.wala.types.Descriptor;
import com.ibm.wala.types.MethodReference;
import com.ibm.wala.types.TypeName;
import com.ibm.wala.types.TypeReference;
import com.ibm.wala.util.debug.Assertions;
import com.ibm.wala.util.intset.EmptyIntSet;
import com.ibm.wala.util.intset.IntSet;
import com.ibm.wala.util.intset.IntSetUtil;
import com.ibm.wala.util.strings.Atom;
/**
* This context selector returns a context customized for the {@link InstanceKey} of the receiver if
* <ul>
* <li>receiver is a container, or</li>
* was allocated in a node whose context was a {@link ReceiverInstanceContext}, and the type is interesting according to a delegate
* {@link ZeroXInstanceKeys}
* </ul>
*
* Additionally, we add one level of call string context to a few well-known static factory methods from the standard libraries.
*/
public class ContainerContextSelector implements ContextSelector {
private final static boolean DEBUG = false;
private final static TypeName SyntheticSystemName = TypeName.string2TypeName("Lcom/ibm/wala/model/java/lang/System");
public final static TypeReference SyntheticSystem = TypeReference.findOrCreate(ClassLoaderReference.Primordial,
SyntheticSystemName);
public final static TypeReference JavaUtilHashtable = TypeReference.findOrCreate(ClassLoaderReference.Primordial,
"Ljava/util/Hashtable");
public final static Atom arraycopyAtom = Atom.findOrCreateUnicodeAtom("arraycopy");
private final static Descriptor arraycopyDesc = Descriptor.findOrCreateUTF8("(Ljava/lang/Object;Ljava/lang/Object;)V");
public final static MethodReference synthArraycopy = MethodReference.findOrCreate(SyntheticSystem, arraycopyAtom, arraycopyDesc);
private final static TypeReference Arrays = TypeReference.findOrCreate(ClassLoaderReference.Primordial, "Ljava/util/Arrays");
private final static Atom asList = Atom.findOrCreateUnicodeAtom("asList");
private final static Atom copyOf = Atom.findOrCreateUnicodeAtom("copyOf");
private final static Atom copyOfRange = Atom.findOrCreateUnicodeAtom("copyOfRange");
private final static Atom toString = Atom.findOrCreateUnicodeAtom("toString");
private final static MethodReference StringValueOf = MethodReference.findOrCreate(TypeReference.JavaLangString, "valueOf",
"(Ljava/lang/Object;)Ljava/lang/String;");
private final static MethodReference HashtableNewEntry = MethodReference.findOrCreate(JavaUtilHashtable, "newEntry",
"(Ljava/lang/Object;Ljava/lang/Object;I)Ljava/util/Hashtable$Entry;");
/**
* The governing class hierarchy.
*/
private final IClassHierarchy cha;
/**
* An object that determines object naming policy
*/
private final ZeroXInstanceKeys delegate;
/**
* @param cha governing class hierarchy
* @param delegate object which determines which classes are "interesting"
*/
public ContainerContextSelector(IClassHierarchy cha, ZeroXInstanceKeys delegate) {
this.cha = cha;
this.delegate = delegate;
if (delegate == null) {
throw new IllegalArgumentException("null delegate");
}
}
/*
* @see com.ibm.wala.ipa.callgraph.ContextSelector#getCalleeTarget(com.ibm.wala.ipa.callgraph.CGNode,
* com.ibm.wala.classLoader.CallSiteReference, com.ibm.wala.classLoader.IMethod,
* com.ibm.wala.ipa.callgraph.propagation.InstanceKey)
*/
@Override
public Context getCalleeTarget(CGNode caller, CallSiteReference site, IMethod callee, InstanceKey[] keys) {
if (DEBUG) {
System.err.println("ContainerContextSelector: getCalleeTarget " + callee);
}
InstanceKey receiver = null;
if (keys != null && keys.length > 0 && keys[0] != null) {
receiver = keys[0];
}
if (mayUnderstand(caller, site, callee, receiver)) {
if (DEBUG) {
System.err.println("May Understand: " + callee + " recv " + receiver);
}
if (isWellKnownStaticFactory(callee.getReference())) {
return new CallerSiteContext(caller, site);
} else {
if (receiver == null) {
Assertions.UNREACHABLE("null receiver for " + site);
}
return new ReceiverInstanceContext(receiver);
}
} else {
return null;
}
}
/**
* Does m represent a static factory method we know about from the standard libraries, that we usually wish to model with one
* level of call-string context?
*/
public static boolean isWellKnownStaticFactory(MethodReference m) {
if (isArrayCopyingMethod(m)) {
return true;
}
if (isArrayToStringMethod(m)) {
return true;
}
if (m.equals(StringValueOf)) {
return true;
}
if (m.equals(HashtableNewEntry)) {
return true;
}
return false;
}
/**
* Does m represent a library method that copies arrays?
*/
public static boolean isArrayCopyingMethod(MethodReference m) {
if (m == null) {
throw new IllegalArgumentException("null m");
}
if (m.getDeclaringClass().equals(TypeReference.JavaLangSystem)) {
if (m.getName().toString().equals("arraycopy")) {
return true;
}
}
if (m.equals(synthArraycopy)) {
return true;
}
if (isArrayCopyMethod(m)) {
return true;
}
return false;
}
/**
* return true iff m represents one of the well-known methods in
* java.lang.reflect.Arrays that do some sort of arraycopy
*/
private static boolean isArrayCopyMethod(MethodReference m) {
if (m.getDeclaringClass().equals(Arrays)) {
if (m.getName().equals(asList) || m.getName().equals(copyOf) || m.getName().equals(copyOfRange)) {
return true;
}
}
return false;
}
/**
* return true iff m represents one of the well-known methods in java.lang.reflect.Arrays that do toString() on an array
*/
private static boolean isArrayToStringMethod(MethodReference m) {
if (m.getDeclaringClass().equals(Arrays)) {
if (m.getName().equals(toString)) {
return true;
}
}
return false;
}
/**
* This method walks recursively up the definition of a context C, to see if
* the chain of contexts that give rise to C a) includes the method M. or b)
* includes the method in which the receiver was allocated
*
* @return the matching context if found, null otherwise
*/
public static Context findRecursiveMatchingContext(IMethod M, Context C, InstanceKey receiver) {
if (DEBUG) {
System.err.println("findRecursiveMatchingContext for " + M + " in context " + C + " receiver " + receiver);
}
Context result = findRecursiveMatchingContext(M, C);
if (result != null) {
return result;
} else {
if (receiver instanceof AllocationSiteInNode) {
AllocationSiteInNode a = (AllocationSiteInNode) receiver;
IMethod m = a.getNode().getMethod();
return findRecursiveMatchingContext(m, C);
} else {
return null;
}
}
}
/**
* This method walks recursively up the definition of a context C, to see if
* the chain of contexts that give rise to C includes the method M.
*
* If C is a ReceiverInstanceContext, Let N be the node that allocated
* C.instance. If N.method == M, return N. Else return
* findRecursiveMatchingContext(M, N.context) Else return null
*/
public static CGNode findNodeRecursiveMatchingContext(IMethod m, Context c) {
if (DEBUG) {
System.err.println("findNodeRecursiveMatchingContext " + m + " in context " + c);
}
if (c instanceof ReceiverInstanceContext) {
ReceiverInstanceContext ric = (ReceiverInstanceContext) c;
if (!(ric.getReceiver() instanceof AllocationSiteInNode)) {
return null;
}
AllocationSiteInNode i = (AllocationSiteInNode) ric.getReceiver();
CGNode n = i.getNode();
if (n.getMethod().equals(m)) {
return n;
} else {
return findNodeRecursiveMatchingContext(m, n.getContext());
}
} else if (c instanceof CallerContext) {
CallerContext cc = (CallerContext) c;
CGNode n = cc.getCaller();
if (n.getMethod().equals(m)) {
return n;
} else {
return findNodeRecursiveMatchingContext(m, n.getContext());
}
} else {
return null;
}
}
/**
* This method walks recursively up the definition of a context C, to see if
* the chain of contexts that give rise to C includes the method M.
*
* If C is a ReceiverInstanceContext, Let N be the node that allocated
* C.instance. If N.method == M, return N.context. Else return
* findRecursiveMatchingContext(M, N.context) Else return null
*/
public static Context findRecursiveMatchingContext(IMethod M, Context C) {
CGNode n = findNodeRecursiveMatchingContext(M, C);
return (n == null) ? null : n.getContext();
}
public boolean mayUnderstand(CGNode caller, CallSiteReference site, IMethod targetMethod, InstanceKey receiver) {
if (targetMethod == null) {
throw new IllegalArgumentException("targetMethod is null");
}
if (isWellKnownStaticFactory(targetMethod.getReference())) {
return true;
} else {
if (site.isStatic()) {
return false;
}
if (receiver == null) {
return false;
}
if (targetMethod.getDeclaringClass().getReference().equals(TypeReference.JavaLangObject)) {
// ramp down context: assuming methods on java.lang.Object don't cause pollution
// important for containers that invoke reflection
return false;
}
if (isContainer(targetMethod.getDeclaringClass())) {
return true;
}
// TODO MS disabling logic below; it has been disabled anyway
// for a while since we were avoiding calling this method with
// receiver == null. Should we delete it?
// if (receiver == null) {
// // any possible receiver. However, we will only handle this call
// // if the concrete receiver type is interesting.
// IClass klass = targetMethod.getDeclaringClass();
// int n = cha.getNumberOfImmediateSubclasses(klass);
// if (n > 0) {
// // the receiver is not "effectively final".
// // give up and assume we might see an interesting subclass.
// return true;
// }
// // only one possible receiver class
// if (delegate.isInteresting(klass)) {
// // we may create a receiver instance context for this call
// return true;
// } else {
// // we will never create a receiver instance context for this call
// return false;
// }
// }
if (!delegate.isInteresting(receiver.getConcreteType())) {
return false;
}
if (receiver instanceof AllocationSiteInNode) {
AllocationSiteInNode I = (AllocationSiteInNode) receiver;
CGNode N = I.getNode();
if (N.getContext() instanceof ReceiverInstanceContext) {
return true;
}
}
return false;
}
}
/**
* @return true iff C is a container class
*/
protected boolean isContainer(IClass C) {
if (DEBUG) {
System.err.println("isContainer? " + C + " " + ContainerUtil.isContainer(C));
}
return ContainerUtil.isContainer(C);
}
protected IClassHierarchy getClassHierarchy() {
return cha;
}
private static final IntSet thisParameter = IntSetUtil.make(new int[]{0});
@Override
public IntSet getRelevantParameters(CGNode caller, CallSiteReference site) {
if (site.isDispatch() || site.getDeclaredTarget().getNumberOfParameters() > 0) {
return thisParameter;
} else {
return EmptyIntSet.instance;
}
}
}