/*******************************************************************************
* 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.analysis.reflection;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import com.ibm.wala.cfg.ControlFlowGraph;
import com.ibm.wala.cfg.InducedCFG;
import com.ibm.wala.classLoader.ArrayClass;
import com.ibm.wala.classLoader.CallSiteReference;
import com.ibm.wala.classLoader.CodeScanner;
import com.ibm.wala.classLoader.IClass;
import com.ibm.wala.classLoader.IField;
import com.ibm.wala.classLoader.IMethod;
import com.ibm.wala.classLoader.Language;
import com.ibm.wala.classLoader.NewSiteReference;
import com.ibm.wala.ipa.callgraph.CGNode;
import com.ibm.wala.ipa.callgraph.Context;
import com.ibm.wala.ipa.callgraph.ContextUtil;
import com.ibm.wala.ipa.callgraph.propagation.SSAContextInterpreter;
import com.ibm.wala.ipa.summaries.SyntheticIR;
import com.ibm.wala.shrikeBT.IInvokeInstruction;
import com.ibm.wala.ssa.DefUse;
import com.ibm.wala.ssa.IR;
import com.ibm.wala.ssa.ISSABasicBlock;
import com.ibm.wala.ssa.SSAGetInstruction;
import com.ibm.wala.ssa.SSAInstruction;
import com.ibm.wala.ssa.SSAInstructionFactory;
import com.ibm.wala.ssa.SSAInvokeInstruction;
import com.ibm.wala.ssa.SSANewInstruction;
import com.ibm.wala.ssa.SSAOptions;
import com.ibm.wala.ssa.SSAPutInstruction;
import com.ibm.wala.ssa.SSAReturnInstruction;
import com.ibm.wala.types.ClassLoaderReference;
import com.ibm.wala.types.Descriptor;
import com.ibm.wala.types.FieldReference;
import com.ibm.wala.types.MethodReference;
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.NonNullSingletonIterator;
import com.ibm.wala.util.strings.Atom;
/**
* A context interpreter for java.lang.Object.clone
*
* TODO: The current implementation does not model CloneNotSupportedExceptions
*/
public class CloneInterpreter implements SSAContextInterpreter {
/**
* Comment for <code>cloneAtom</code>
*/
public final static Atom cloneAtom = Atom.findOrCreateUnicodeAtom("clone");
private final static Descriptor cloneDesc = Descriptor.findOrCreateUTF8("()Ljava/lang/Object;");
/**
* Comment for <code>CLONE</code>
*/
public final static MethodReference CLONE = MethodReference.findOrCreate(TypeReference.JavaLangObject, cloneAtom, cloneDesc);
private final static TypeReference SYNTHETIC_SYSTEM = TypeReference.findOrCreate(ClassLoaderReference.Primordial, TypeName
.string2TypeName("Lcom/ibm/wala/model/java/lang/System"));
private final static Atom arraycopyAtom = Atom.findOrCreateUnicodeAtom("arraycopy");
private final static Descriptor arraycopyDesc = Descriptor.findOrCreateUTF8("(Ljava/lang/Object;Ljava/lang/Object;)V");
private final static MethodReference SYNTHETIC_ARRAYCOPY = MethodReference.findOrCreate(SYNTHETIC_SYSTEM, arraycopyAtom,
arraycopyDesc);
/**
* If the type is an array, the program counter of the synthesized call to arraycopy. Doesn't really matter what it is.
*/
private final static int ARRAYCOPY_PC = 3;
private final static CallSiteReference ARRAYCOPY_SITE = CallSiteReference.make(ARRAYCOPY_PC, SYNTHETIC_ARRAYCOPY,
IInvokeInstruction.Dispatch.STATIC);
private final static int NEW_PC = 0;
/**
* Mapping from TypeReference -> IR TODO: Soft references?
*/
final private Map<TypeReference, IR> IRCache = HashMapFactory.make();
private final SSAInstructionFactory insts = Language.JAVA.instructionFactory();
@Override
public IR getIR(CGNode node) {
if (node == null) {
throw new IllegalArgumentException("node is null");
}
assert understands(node);
IClass cls = ContextUtil.getConcreteClassFromContext(node.getContext());
IR result = IRCache.get(cls.getReference());
if (result == null) {
result = makeIR(node.getMethod(), node.getContext(), cls);
IRCache.put(cls.getReference(), result);
}
return result;
}
@Override
public int getNumberOfStatements(CGNode node) {
assert understands(node);
return getIR(node).getInstructions().length;
}
@Override
public boolean understands(CGNode node) {
if (node == null) {
throw new IllegalArgumentException("node is null");
}
return (node.getMethod().getReference().equals(CLONE) && ContextUtil.getConcreteClassFromContext(node.getContext()) != null);
}
@Override
public Iterator<NewSiteReference> iterateNewSites(CGNode node) {
if (node == null) {
throw new IllegalArgumentException("node is null");
}
assert understands(node);
IClass cls = ContextUtil.getConcreteClassFromContext(node.getContext());
return new NonNullSingletonIterator<NewSiteReference>(NewSiteReference.make(NEW_PC, cls.getReference()));
}
@Override
public Iterator<CallSiteReference> iterateCallSites(CGNode node) {
assert understands(node);
return new NonNullSingletonIterator<CallSiteReference>(ARRAYCOPY_SITE);
}
/**
* @return an array of statements that encode the behavior of the clone method for a given type.
*/
private SSAInstruction[] makeStatements(IClass klass) {
assert klass != null;
ArrayList<SSAInstruction> statements = new ArrayList<SSAInstruction>();
// value number 1 is "this".
int nextLocal = 2;
int retValue = nextLocal++;
// value number of the result of the clone()
NewSiteReference ref = NewSiteReference.make(NEW_PC, klass.getReference());
SSANewInstruction N = null;
if (klass.isArrayClass()) {
int length = nextLocal++;
statements.add(insts.ArrayLengthInstruction(statements.size(), length, 1));
int[] sizes = new int[((ArrayClass)klass).getDimensionality()];
Arrays.fill(sizes, length);
N = insts.NewInstruction(statements.size(), retValue, ref, sizes);
} else {
N = insts.NewInstruction(statements.size(), retValue, ref);
}
statements.add(N);
int exceptionValue = nextLocal++;
if (klass.getReference().isArrayType()) {
// generate a synthetic arraycopy from this (v.n. 1) to the clone
int[] params = new int[2];
params[0] = 1;
params[1] = retValue;
SSAInvokeInstruction S = insts.InvokeInstruction(statements.size(), params, exceptionValue, ARRAYCOPY_SITE);
statements.add(S);
} else {
// copy the fields over, one by one.
// TODO:
IClass k = klass;
while (k != null) {
for (Iterator<IField> it = klass.getDeclaredInstanceFields().iterator(); it.hasNext();) {
IField f = it.next();
int tempValue = nextLocal++;
SSAGetInstruction G = insts.GetInstruction(statements.size(), tempValue, 1, f.getReference());
statements.add(G);
SSAPutInstruction P = insts.PutInstruction(statements.size(), retValue, tempValue, f.getReference());
statements.add(P);
}
k = k.getSuperclass();
}
}
SSAReturnInstruction R = insts.ReturnInstruction(statements.size(), retValue, false);
statements.add(R);
SSAInstruction[] result = new SSAInstruction[statements.size()];
Iterator<SSAInstruction> it = statements.iterator();
for (int i = 0; i < result.length; i++) {
result[i] = it.next();
}
return result;
}
/**
* @return an IR that encodes the behavior of the clone method for a given type.
*/
private IR makeIR(IMethod method, Context context, IClass klass) {
assert klass != null;
SSAInstruction instrs[] = makeStatements(klass);
return new SyntheticIR(method, context, new InducedCFG(instrs, method, context), instrs, SSAOptions.defaultOptions(), null);
}
/*
* @see com.ibm.wala.ipa.callgraph.propagation.cfa.CFAContextInterpreter#recordFactoryType(com.ibm.wala.ipa.callgraph.CGNode,
* com.ibm.wala.classLoader.IClass)
*/
@Override
public boolean recordFactoryType(CGNode node, IClass klass) {
return false;
}
@Override
public Iterator<FieldReference> iterateFieldsRead(CGNode node) {
SSAInstruction[] statements = getIR(node).getInstructions();
return CodeScanner.getFieldsRead(statements).iterator();
}
@Override
public Iterator<FieldReference> iterateFieldsWritten(CGNode node) {
SSAInstruction[] statements = getIR(node).getInstructions();
return CodeScanner.getFieldsWritten(statements).iterator();
}
public Set getCaughtExceptions(CGNode node) {
SSAInstruction[] statements = getIR(node).getInstructions();
return CodeScanner.getCaughtExceptions(node.getMethod().getDeclaringClass().getClassLoader().getLanguage(), statements);
}
public boolean hasObjectArrayLoad(CGNode node) {
SSAInstruction[] statements = getIR(node).getInstructions();
return CodeScanner.hasObjectArrayLoad(statements);
}
public boolean hasObjectArrayStore(CGNode node) {
SSAInstruction[] statements = getIR(node).getInstructions();
return CodeScanner.hasObjectArrayStore(statements);
}
public Iterator iterateCastTypes(CGNode node) {
SSAInstruction[] statements = getIR(node).getInstructions();
return CodeScanner.iterateCastTypes(statements);
}
@Override
public ControlFlowGraph<SSAInstruction, ISSABasicBlock> getCFG(CGNode N) {
return getIR(N).getControlFlowGraph();
}
@Override
public DefUse getDU(CGNode node) {
return new DefUse(getIR(node));
}
}