/*******************************************************************************
* 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 java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import com.ibm.wala.classLoader.IClass;
import com.ibm.wala.classLoader.IField;
import com.ibm.wala.classLoader.NewSiteReference;
import com.ibm.wala.classLoader.ProgramCounter;
import com.ibm.wala.ipa.callgraph.AnalysisOptions;
import com.ibm.wala.ipa.callgraph.CGNode;
import com.ibm.wala.ipa.callgraph.propagation.AllocationSiteInNodeFactory;
import com.ibm.wala.ipa.callgraph.propagation.ClassBasedInstanceKeys;
import com.ibm.wala.ipa.callgraph.propagation.ConstantKey;
import com.ibm.wala.ipa.callgraph.propagation.InstanceKey;
import com.ibm.wala.ipa.callgraph.propagation.InstanceKeyFactory;
import com.ibm.wala.ipa.callgraph.propagation.SmushedAllocationSiteInstanceKeys;
import com.ibm.wala.ipa.callgraph.propagation.rta.RTAContextInterpreter;
import com.ibm.wala.ipa.cha.IClassHierarchy;
import com.ibm.wala.types.ClassLoaderReference;
import com.ibm.wala.types.TypeName;
import com.ibm.wala.types.TypeReference;
import com.ibm.wala.util.collections.HashMapFactory;
import com.ibm.wala.util.collections.HashSetFactory;
/**
* Flexible class to create {@link InstanceKey}s depending on various policies ranging from class-based (i.e. 0-CFA) to
* allocation-site-based (0-1-CFA variants).
*/
public class ZeroXInstanceKeys implements InstanceKeyFactory {
private final static TypeName JavaLangStringBufferName = TypeName.string2TypeName("Ljava/lang/StringBuffer");
public final static TypeReference JavaLangStringBuffer = TypeReference.findOrCreate(ClassLoaderReference.Primordial,
JavaLangStringBufferName);
private final static TypeName JavaLangStringBuilderName = TypeName.string2TypeName("Ljava/lang/StringBuilder");
public final static TypeReference JavaLangStringBuilder = TypeReference.findOrCreate(ClassLoaderReference.Primordial,
JavaLangStringBuilderName);
private final static TypeName JavaLangAbstractStringBuilderName = TypeName.string2TypeName("Ljava/lang/AbstractStringBuilder");
public final static TypeReference JavaLangAbstractStringBuilder = TypeReference.findOrCreate(ClassLoaderReference.Primordial,
JavaLangAbstractStringBuilderName);
/**
* The NONE policy is not allocation-site based
*/
public static final int NONE = 0;
/**
* An ALLOCATIONS - based policy distinguishes instances by allocation site. Otherwise, the policy distinguishes instances by
* type.
*/
public static final int ALLOCATIONS = 1;
/**
* A policy variant where String and StringBuffers are NOT disambiguated according to allocation site.
*/
public static final int SMUSH_STRINGS = 2;
/**
* A policy variant where {@link Throwable} instances are NOT disambiguated according to allocation site.
*
*/
public static final int SMUSH_THROWABLES = 4;
/**
* A policy variant where if a type T has only primitive instance fields, then instances of type T are NOT disambiguated by
* allocation site.
*/
public static final int SMUSH_PRIMITIVE_HOLDERS = 8;
/**
* This variant counts the N, number of allocation sites of a particular type T in each method. If N > SMUSH_LIMIT, then these N
* allocation sites are NOT distinguished ... instead there is a single abstract allocation site for <N,T>
*
* Probably the best choice in many cases.
*/
public static final int SMUSH_MANY = 16;
/**
* Should we use constant-specific keys?
*/
public static final int CONSTANT_SPECIFIC = 32;
/**
* When using smushing, how many sites in a node will be kept distinct before smushing?
*/
private final int SMUSH_LIMIT = 25;
/**
* The policy choice for instance disambiguation
*/
private final int policy;
/**
* A delegate object to create class-based abstract instances
*/
private final ClassBasedInstanceKeys classBased;
/**
* A delegate object to create allocation site-based abstract instances
*/
private final AllocationSiteInNodeFactory siteBased;
/**
* A delegate object to create "abstract allocation site" - based abstract instances
*/
private final SmushedAllocationSiteInstanceKeys smushed;
/**
* The governing class hierarchy
*/
private final IClassHierarchy cha;
/**
* An object which interprets nodes in context.
*/
final private RTAContextInterpreter contextInterpreter;
/**
* a Map from CGNode->Set<IClass> that should be smushed.
*/
protected final Map<CGNode, Set<IClass>> smushMap = HashMapFactory.make();
public ZeroXInstanceKeys(AnalysisOptions options, IClassHierarchy cha, RTAContextInterpreter contextInterpreter, int policy) {
if (options == null) {
throw new IllegalArgumentException("null options");
}
this.policy = policy;
if (disambiguateConstants()) {
// this is an ugly hack. TODO: clean it all up.
options.setUseConstantSpecificKeys(true);
}
classBased = new ClassBasedInstanceKeys(options, cha);
siteBased = new AllocationSiteInNodeFactory(options, cha);
smushed = new SmushedAllocationSiteInstanceKeys(options, cha);
this.cha = cha;
this.contextInterpreter = contextInterpreter;
}
/**
* @return true iff the policy smushes some allocation sites
*/
private boolean smushMany() {
return (policy & SMUSH_MANY) > 0;
}
private boolean allocationPolicy() {
return (policy & ALLOCATIONS) > 0;
}
private boolean smushStrings() {
return (policy & SMUSH_STRINGS) > 0;
}
public boolean smushThrowables() {
return (policy & SMUSH_THROWABLES) > 0;
}
private boolean smushPrimHolders() {
return (policy & SMUSH_PRIMITIVE_HOLDERS) > 0;
}
public boolean disambiguateConstants() {
return (policy & CONSTANT_SPECIFIC) > 0;
}
@Override
public InstanceKey getInstanceKeyForAllocation(CGNode node, NewSiteReference allocation) {
if (allocation == null) {
throw new IllegalArgumentException("allocation is null");
}
TypeReference t = allocation.getDeclaredType();
IClass C = cha.lookupClass(t);
if (C != null && isInteresting(C)) {
if (smushMany()) {
if (exceedsSmushLimit(C, node)) {
return smushed.getInstanceKeyForAllocation(node, allocation);
} else {
return siteBased.getInstanceKeyForAllocation(node, allocation);
}
} else {
return siteBased.getInstanceKeyForAllocation(node, allocation);
}
} else {
return classBased.getInstanceKeyForAllocation(node, allocation);
}
}
/**
* side effect: populates the smush map.
*
* @return true iff the node contains too many allocation sites of type c
*/
private boolean exceedsSmushLimit(IClass c, CGNode node) {
Set<IClass> s = smushMap.get(node);
if (s == null) {
Map<IClass, Integer> count = countAllocsByType(node);
HashSet<IClass> smushees = HashSetFactory.make(5);
for (Iterator<Map.Entry<IClass, Integer>> it = count.entrySet().iterator(); it.hasNext();) {
Map.Entry<IClass, Integer> e = it.next();
Integer i = e.getValue();
if (i.intValue() > SMUSH_LIMIT) {
smushees.add(e.getKey());
}
}
s = smushees.isEmpty() ? Collections.<IClass> emptySet() : smushees;
smushMap.put(node, s);
}
return s.contains(c);
}
/**
* @return Map: IClass -> Integer, the number of allocation sites for each type.
*/
private Map<IClass, Integer> countAllocsByType(CGNode node) {
Map<IClass, Integer> count = HashMapFactory.make();
for (Iterator it = contextInterpreter.iterateNewSites(node); it.hasNext();) {
NewSiteReference n = (NewSiteReference) it.next();
IClass alloc = cha.lookupClass(n.getDeclaredType());
if (alloc != null) {
Integer old = count.get(alloc);
if (old == null) {
count.put(alloc, new Integer(1));
} else {
count.put(alloc, new Integer(old.intValue() + 1));
}
}
}
return count;
}
@Override
public InstanceKey getInstanceKeyForMultiNewArray(CGNode node, NewSiteReference allocation, int dim) {
if (allocationPolicy()) {
return siteBased.getInstanceKeyForMultiNewArray(node, allocation, dim);
} else {
return classBased.getInstanceKeyForMultiNewArray(node, allocation, dim);
}
}
@Override
public <T> InstanceKey getInstanceKeyForConstant(TypeReference type, T S) {
if (type == null) {
throw new IllegalArgumentException("null type");
}
if (disambiguateConstants() || isReflectiveType(type)) {
return new ConstantKey<T>(S, getClassHierarchy().lookupClass(type));
} else {
return classBased.getInstanceKeyForConstant(type, S);
}
}
private boolean isReflectiveType(TypeReference type) {
return type.equals(TypeReference.JavaLangReflectConstructor) || type.equals(TypeReference.JavaLangReflectMethod);
}
/*
* @see com.ibm.wala.ipa.callgraph.propagation.InstanceKeyFactory#getInstanceKeyForPEI(com.ibm.wala.ipa.callgraph.CGNode,
* com.ibm.wala.classLoader.ProgramCounter, com.ibm.wala.types.TypeReference)
*/
@Override
public InstanceKey getInstanceKeyForPEI(CGNode node, ProgramCounter pei, TypeReference type) {
return classBased.getInstanceKeyForPEI(node, pei, type);
}
@Override
public InstanceKey getInstanceKeyForMetadataObject(Object obj, TypeReference objType) {
return classBased.getInstanceKeyForMetadataObject(obj, objType);
}
/**
* A class is "interesting" iff we distinguish instances of the class
*/
public boolean isInteresting(IClass C) {
if (!allocationPolicy()) {
return false;
} else {
if (smushStrings() && isStringish(C)) {
return false;
} else if (smushThrowables() && (isThrowable(C) || isStackTraceElement(C))) {
return false;
} else if (smushPrimHolders() && allFieldsArePrimitive(C)) {
return false;
}
return true;
}
}
public static boolean isStringish(IClass C) {
if (C == null) {
throw new IllegalArgumentException("C is null");
}
return C.getReference().equals(TypeReference.JavaLangString) || C.getReference().equals(JavaLangStringBuffer)
|| C.getReference().equals(JavaLangStringBuilder) || C.getReference().equals(JavaLangAbstractStringBuilder);
}
public static boolean isThrowable(IClass c) {
if (c == null) {
throw new IllegalArgumentException("null c");
}
return c.getClassHierarchy().isSubclassOf(c, c.getClassHierarchy().lookupClass(TypeReference.JavaLangThrowable));
}
/** BEGIN Custom Change: make this method static (like isThrowable) */
public static boolean isStackTraceElement(IClass c) {
if (c == null) {
throw new IllegalArgumentException("C is null");
}
return c.getReference().equals(TypeReference.JavaLangStackTraceElement);
}
/** END Custom Change: make this method static (like isThrowable) */
private boolean allFieldsArePrimitive(IClass c) {
if (c.isArrayClass()) {
TypeReference t = c.getReference().getArrayElementType();
return t.isPrimitiveType();
} else {
if (c.getReference().equals(TypeReference.JavaLangObject)) {
return true;
} else {
for (Iterator<IField> it = c.getDeclaredInstanceFields().iterator(); it.hasNext();) {
IField f = it.next();
if (f.getReference().getFieldType().isReferenceType()) {
return false;
}
}
return allFieldsArePrimitive(c.getSuperclass());
}
}
}
protected IClassHierarchy getClassHierarchy() {
return cha;
}
public ClassBasedInstanceKeys getClassBasedInstanceKeys() {
return classBased;
}
}