112 lines
4.5 KiB
Java
112 lines
4.5 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.cast.js.ipa.callgraph;
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import com.ibm.wala.analysis.reflection.InstanceKeyWithNode;
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import com.ibm.wala.cast.ipa.callgraph.ScopeMappingInstanceKeys.ScopeMappingInstanceKey;
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import com.ibm.wala.cast.js.ipa.callgraph.JavaScriptConstructTargetSelector.JavaScriptConstructor;
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import com.ibm.wala.classLoader.CallSiteReference;
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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.ContextKey;
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import com.ibm.wala.ipa.callgraph.ContextSelector;
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import com.ibm.wala.ipa.callgraph.impl.Everywhere;
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import com.ibm.wala.ipa.callgraph.propagation.FilteredPointerKey;
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import com.ibm.wala.ipa.callgraph.propagation.FilteredPointerKey.SingleInstanceFilter;
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import com.ibm.wala.ipa.callgraph.propagation.InstanceKey;
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import com.ibm.wala.ipa.callgraph.propagation.cfa.CallString;
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import com.ibm.wala.ipa.callgraph.propagation.cfa.CallStringContext;
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import com.ibm.wala.util.intset.IntSet;
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/**
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* A context selector that attempts to detect recursion beyond some depth in a
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* base selector. If such recursion is detected, the base selector's context is
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* replaced with {@link Everywhere#EVERYWHERE}.
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*/
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public class RecursionBoundContextSelector implements ContextSelector {
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private final ContextSelector base;
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private final int recursionBound;
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/**
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* the highest parameter index that we'll check . this is a HACK. ideally,
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* given a context, we'd have some way to know all the {@link ContextKey}s
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* that it knows about.
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*
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* @see ContextKey#PARAMETERS
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*/
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private static final int MAX_INTERESTING_PARAM = 5;
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/**
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* @param base
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* @param recursionBound
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* bound on recursion depth, with the top level of the context
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* returned by the base selector being depth 0. The
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* {@link Everywhere#EVERYWHERE} context is returned if the base
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* context <em>exceeds</em> this bound.
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*/
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public RecursionBoundContextSelector(ContextSelector base, int recursionBound) {
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this.base = base;
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this.recursionBound = recursionBound;
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}
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@Override
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public Context getCalleeTarget(CGNode caller, CallSiteReference site, IMethod callee, InstanceKey[] actualParameters) {
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Context baseContext = base.getCalleeTarget(caller, site, callee, actualParameters);
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final boolean exceedsRecursionBound = exceedsRecursionBound(baseContext, 0);
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if (!exceedsRecursionBound) {
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return baseContext;
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} else if (callee instanceof JavaScriptConstructor) {
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// for constructors, we want to keep some basic context sensitivity to
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// avoid horrible imprecision
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return new CallStringContext(new CallString(site, caller.getMethod()));
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} else {
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// TODO somehow k-limit more smartly?
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return Everywhere.EVERYWHERE;
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}
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}
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private boolean exceedsRecursionBound(Context baseContext, int curLevel) {
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if (curLevel > recursionBound) {
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return true;
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}
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// we just do a case analysis here. we might have to add cases later to
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// account for new types of context / recursion.
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CGNode callerNode = (CGNode) baseContext.get(ContextKey.CALLER);
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if (callerNode != null && exceedsRecursionBound(callerNode.getContext(), curLevel + 1)) {
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return true;
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}
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for (int i = 0; i < MAX_INTERESTING_PARAM; i++) {
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FilteredPointerKey.SingleInstanceFilter filter = (SingleInstanceFilter) baseContext.get(ContextKey.PARAMETERS[i]);
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if (filter != null) {
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InstanceKey ik = filter.getInstance();
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if (ik instanceof ScopeMappingInstanceKey) {
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ik = ((ScopeMappingInstanceKey) ik).getBase();
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}
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if (ik instanceof InstanceKeyWithNode) {
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if (exceedsRecursionBound(((InstanceKeyWithNode) ik).getNode().getContext(), curLevel + 1)) {
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return true;
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}
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}
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}
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}
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return false;
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}
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@Override
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public IntSet getRelevantParameters(CGNode caller, CallSiteReference site) {
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return base.getRelevantParameters(caller, site);
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}
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}
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