171 lines
6.3 KiB
Java
171 lines
6.3 KiB
Java
/*******************************************************************************
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* Copyright (c) 2013 IBM Corporation.
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* All rights reserved. This program and the accompanying materials
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* are made available under the terms of the Eclipse Public License v1.0
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* which accompanies this distribution, and is available at
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* http://www.eclipse.org/legal/epl-v10.html
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*
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* Contributors:
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* IBM Corporation - initial API and implementation
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*******************************************************************************/
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package com.ibm.wala.analysis.reflection;
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import java.util.Collection;
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import com.ibm.wala.analysis.typeInference.PointType;
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import com.ibm.wala.classLoader.CallSiteReference;
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import com.ibm.wala.classLoader.IClass;
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import com.ibm.wala.classLoader.IMethod;
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import com.ibm.wala.ipa.callgraph.CGNode;
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import com.ibm.wala.ipa.callgraph.Context;
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import com.ibm.wala.ipa.callgraph.ContextSelector;
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import com.ibm.wala.ipa.callgraph.propagation.ConstantKey;
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import com.ibm.wala.ipa.callgraph.propagation.InstanceKey;
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import com.ibm.wala.ipa.cha.IClassHierarchy;
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import com.ibm.wala.ssa.IR;
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import com.ibm.wala.ssa.SSAAbstractInvokeInstruction;
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import com.ibm.wala.ssa.SymbolTable;
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import com.ibm.wala.types.ClassLoaderReference;
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import com.ibm.wala.types.MethodReference;
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import com.ibm.wala.types.TypeReference;
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import com.ibm.wala.util.collections.HashSetFactory;
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import com.ibm.wala.util.intset.EmptyIntSet;
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import com.ibm.wala.util.intset.IntSet;
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import com.ibm.wala.util.intset.IntSetUtil;
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/**
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* Produces {@link com.ibm.wala.analysis.reflection.GetMethodContext} if appropriate.
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* @author Michael Heilmann
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* @see com.ibm.wala.analysis.reflection.GetMethodContext
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* @see com.ibm.wala.analysis.reflection.GetMethodContextInterpreter
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*/
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public class GetMethodContextSelector implements ContextSelector {
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/**
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* If <tt>true</tt>, debug information is emitted.
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*/
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protected static final boolean DEBUG = false;
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/**
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* whether to only follow get method calls on application classes, ignoring system ones
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*/
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private final boolean applicationClassesOnly;
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public GetMethodContextSelector(boolean applicationClassesOnly) {
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this.applicationClassesOnly = applicationClassesOnly;
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}
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/**
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* If
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* <ul>
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* <li>the {@link CallSiteReference} invokes either {@link java.lang.Class#getMethod} or {@link java.lang.Class#getDeclaredMethod},</li>
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* <li>and the receiver is a type constant and</li>
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* <li>the first argument is a constant,</li>
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* </ul>
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* then return a {@link GetMethodContextSelector}.
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*/
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@Override
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public Context getCalleeTarget(CGNode caller,CallSiteReference site,IMethod callee,InstanceKey[] receiver) {
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if (receiver != null && receiver.length > 0 && mayUnderstand(caller, site, callee, receiver[0])) {
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if (DEBUG) {
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System.out.print("site := " + site + ", receiver := " + receiver[0]);
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}
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// If the first argument is a constant ...
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IR ir = caller.getIR();
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SymbolTable symbolTable = ir.getSymbolTable();
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SSAAbstractInvokeInstruction[] invokeInstructions = caller.getIR().getCalls(site);
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if (invokeInstructions.length != 1) {
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return null;
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}
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int use = invokeInstructions[0].getUse(1);
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if (symbolTable.isStringConstant(invokeInstructions[0].getUse(1))) {
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String sym = symbolTable.getStringValue(use);
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if (DEBUG) {
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System.out.println(invokeInstructions);
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System.out.println(", with constant := `" + sym + "`");
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for (InstanceKey instanceKey:receiver) {
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System.out.println(" " + instanceKey);
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}
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}
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// ... return an GetMethodContext.
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ConstantKey ck = makeConstantKey(caller.getClassHierarchy(),sym);
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if (DEBUG) {
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System.out.println(ck);
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}
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IClass type = getTypeConstant(receiver[0]);
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if (!applicationClassesOnly ||
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!(type.getClassLoader().getReference().equals(ClassLoaderReference.Primordial) ||
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type.getClassLoader().getReference().equals(ClassLoaderReference.Extension))) {
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return new GetMethodContext(new PointType(type),ck);
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}
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}
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if (DEBUG) {
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System.out.println(", with constant := no");
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}
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// Otherwise, return null.
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// TODO Remove this, just fall-through.
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return null;
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}
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return null;
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}
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/**
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* If <tt>instance</tt> is a {@link ConstantKey} and its value is an instance of {@link IClass},
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* return that value. Otherwise, return <tt>null</tt>.
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*/
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private static IClass getTypeConstant(InstanceKey instance) {
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if (instance instanceof ConstantKey) {
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ConstantKey c = (ConstantKey) instance;
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if (c.getValue() instanceof IClass) {
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return (IClass) c.getValue();
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}
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}
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return null;
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}
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/**
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* Create a constant key for a string.
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* @param cha the class hierarchy
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* @param str the string
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* @return the constant key
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*/
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protected static ConstantKey<String> makeConstantKey(IClassHierarchy cha,String str) {
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IClass cls = cha.lookupClass(TypeReference.JavaLangString);
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ConstantKey<String> ck = new ConstantKey<String>(str,cls);
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return ck;
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}
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private static final Collection<MethodReference> UNDERSTOOD_METHOD_REFS = HashSetFactory.make();
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static {
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UNDERSTOOD_METHOD_REFS.add(GetMethodContextInterpreter.GET_METHOD);
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UNDERSTOOD_METHOD_REFS.add(GetMethodContextInterpreter.GET_DECLARED_METHOD);
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}
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/**
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* This object understands a dispatch to {@link java.lang.Class#getMethod(String, Class...)}
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* or {@link java.lang.Class#getDeclaredMethod} when the receiver is a type constant.
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*/
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private static boolean mayUnderstand(CGNode caller,CallSiteReference site,IMethod targetMethod,InstanceKey instance) {
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return UNDERSTOOD_METHOD_REFS.contains(targetMethod.getReference())
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&& getTypeConstant(instance) != null;
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}
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/**
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* TODO
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* MH: Shouldn't be the first TWO parameters be relevant?
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* Documentation is not too helpful about the implications.
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*/
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private static final IntSet thisParameter = IntSetUtil.make(new int[]{0});
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@Override
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public IntSet getRelevantParameters(CGNode caller, CallSiteReference site) {
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if (UNDERSTOOD_METHOD_REFS.contains(site.getDeclaredTarget())) {
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return thisParameter;
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} else {
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return EmptyIntSet.instance;
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}
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}
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}
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