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Add client to count may-alias variable pairs (#149)
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‎src/main/java/pascal/taie/analysis/pta/client/MayAliasPair.java‎

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/*
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* Tai-e: A Static Analysis Framework for Java
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*
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* Copyright (C) 2022 Tian Tan <[email protected]>
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* Copyright (C) 2022 Yue Li <[email protected]>
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*
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* This file is part of Tai-e.
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*
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* Tai-e is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License
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* as published by the Free Software Foundation, either version 3
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* of the License, or (at your option) any later version.
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*
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* Tai-e is distributed in the hope that it will be useful,but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
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* Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Tai-e. If not, see <https://www.gnu.org/licenses/>.
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*/
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package pascal.taie.analysis.pta.client;
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import org.apache.logging.log4j.LogManager;
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import org.apache.logging.log4j.Logger;
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import pascal.taie.World;
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import pascal.taie.analysis.ProgramAnalysis;
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import pascal.taie.analysis.pta.PointerAnalysis;
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import pascal.taie.analysis.pta.PointerAnalysisResult;
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import pascal.taie.analysis.pta.core.heap.Obj;
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import pascal.taie.config.AnalysisConfig;
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import pascal.taie.ir.exp.Var;
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import pascal.taie.util.Indexer;
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import pascal.taie.util.collection.IndexerBitSet;
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import pascal.taie.util.collection.Maps;
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import pascal.taie.util.collection.Sets;
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import java.util.Collection;
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import java.util.Collections;
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import java.util.Map;
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import java.util.Set;
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import java.util.stream.Collectors;
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public class MayAliasPair extends ProgramAnalysis<MayAliasPair.MayAliasPairResult> {
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private static final Logger logger = LogManager.getLogger(MayAliasPair.class);
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public static final String ID = "may-alias-pair";
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private PointerAnalysisResult ptaResult;
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public MayAliasPair(AnalysisConfig config) {
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super(config);
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}
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@Override
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public MayAliasPairResult analyze() {
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ptaResult = World.get().getResult(PointerAnalysis.ID);
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Set<Var> vars = Sets.newSet(ptaResult.getVars());
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Set<Var> appVars = vars.stream()
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.filter(MayAliasPair::isApp)
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.collect(Collectors.toUnmodifiableSet());
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long nAliasPairs = computeMayAliasPairs(vars);
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long nVars = vars.size();
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long nAppAliasPairs = computeMayAliasPairs(appVars);
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long nAppVars = appVars.size();
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// Log statistics
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logger.info("#{}: found {} in {} variable pairs",
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ID, nAliasPairs, (nVars - 1) * nVars / 2);
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logger.info("#{}: found {} in {} variable pairs (app)",
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ID, nAppAliasPairs, (nAppVars - 1) * nAppVars / 2);
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return new MayAliasPairResult(nAliasPairs, nAppAliasPairs);
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}
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private long computeMayAliasPairs(Set<Var> vars) {
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VarIndexer indexer = new VarIndexer(vars);
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Map<Obj, Set<Var>> obj2Vars = Maps.newMap();
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vars.forEach(v -> {
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for (Obj obj : ptaResult.getPointsToSet(v)) {
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obj2Vars.computeIfAbsent(obj, k -> indexer.makeIndexerBitSet())
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.add(v);
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}
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});
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// mayAlias(u, v) if
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// exists o, s.t. in(o, pts(u)) and in(o, pts(v))
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long nAliasPairs = vars.parallelStream()
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.mapToLong(v -> {
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Set<Var> aliasVars = indexer.makeIndexerBitSet();
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for (Obj o : ptaResult.getPointsToSet(v)) {
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aliasVars.addAll(obj2Vars.getOrDefault(o, Collections.emptySet()));
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}
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// v may alias to itself, but we do not count in this case
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aliasVars.remove(v);
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return aliasVars.size();
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}).sum();
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// mayAlias(u, v) iff mayAlias(v, u), so a pair is counted twice
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return nAliasPairs / 2;
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}
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private static boolean isApp(Var v) {
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return v.getMethod().isApplication();
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}
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public record MayAliasPairResult(long aliasPairs, long appAliasPairs) {
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}
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// A global indexer for Vars
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private static class VarIndexer implements Indexer<Var> {
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private static final boolean IS_SPARSE = true;
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private final Var[] vars;
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private final Map<Var, Integer> varIndexMap = Maps.newMap();
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VarIndexer(Collection<Var> vars) {
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this.vars = vars.stream()
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.distinct()
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.toArray(Var[]::new);
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for (int index = 0; index < this.vars.length; index++) {
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varIndexMap.put(this.vars[index], index);
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}
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}
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public IndexerBitSet<Var> makeIndexerBitSet() {
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return new IndexerBitSet<>(this, IS_SPARSE);
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}
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@Override
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public int getIndex(Var o) {
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return varIndexMap.get(o);
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}
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@Override
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public Var getObject(int index) {
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return vars[index];
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}
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}
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}

‎src/main/resources/tai-e-analyses.yml‎

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id: poly-call
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requires: [ pta ]
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- description: identify variable pairs that may alias
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analysisClass: pascal.taie.analysis.pta.client.MayAliasPair
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id: may-alias-pair
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requires: [ pta ]
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- description: find modified objects of methods and statements
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analysisClass: pascal.taie.analysis.sideeffect.SideEffectAnalysis
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id: side-effect

‎src/test/java/pascal/taie/analysis/pta/client/MayAliasPairTest.java‎

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/*
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* Tai-e: A Static Analysis Framework for Java
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*
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* Copyright (C) 2022 Tian Tan <[email protected]>
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* Copyright (C) 2022 Yue Li <[email protected]>
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*
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* This file is part of Tai-e.
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*
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* Tai-e is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License
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* as published by the Free Software Foundation, either version 3
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* of the License, or (at your option) any later version.
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*
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* Tai-e is distributed in the hope that it will be useful,but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
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* Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Tai-e. If not, see <https://www.gnu.org/licenses/>.
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*/
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package pascal.taie.analysis.pta.client;
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import org.junit.jupiter.params.ParameterizedTest;
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import org.junit.jupiter.params.provider.ValueSource;
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import pascal.taie.Main;
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import pascal.taie.World;
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import pascal.taie.analysis.pta.PointerAnalysis;
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import pascal.taie.analysis.pta.PointerAnalysisResult;
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import pascal.taie.ir.exp.Var;
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import java.util.List;
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import static org.junit.jupiter.api.Assertions.assertEquals;
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public class MayAliasPairTest {
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static final String DIR = "basic";
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@ParameterizedTest
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@ValueSource(strings = {
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"New",
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"Assign",
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"StoreLoad",
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"Call",
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"InstanceField",
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"CallParamRet",
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"StaticCall",
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"MergeParam",
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})
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void test(String mainClass) {
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String ptaTestRoot = "src/test/resources/pta";
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String classPath = ptaTestRoot + "/" + DIR;
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List<String> args = List.of(
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// for loading class PTAAssert
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"-cp", ptaTestRoot,
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// for loading main class
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"-cp", classPath, "-m", mainClass,
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"-a", MayAliasPair.ID
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);
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Main.main(args.toArray(new String[0]));
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MayAliasPair.MayAliasPairResult resultByAnalysis = World.get().getResult(MayAliasPair.ID);
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long appResultByDefinition = computeByDefinition();
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assertEquals(appResultByDefinition, resultByAnalysis.appAliasPairs());
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}
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private static long computeByDefinition() {
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PointerAnalysisResult ptaResult = World.get().getResult(PointerAnalysis.ID);
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Var[] appVars = ptaResult.getVars().stream()
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.filter(v -> v.getMethod().isApplication())
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.toArray(Var[]::new);
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long aliasPairs = 0;
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for (int i = 0; i < appVars.length; i++) {
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for (int j = i + 1; j < appVars.length; j++) {
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Var v1 = appVars[i], v2 = appVars[j];
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if (ptaResult.mayAlias(v1, v2)) {
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aliasPairs++;
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}
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}
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}
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return aliasPairs;
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}
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}

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