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1
19
20 package edu.umd.cs.findbugs.ba;
21
22 import org.apache.bcel.Constants;
23 import org.apache.bcel.classfile.Method;
24 import org.apache.bcel.generic.Instruction;
25 import org.apache.bcel.generic.InstructionHandle;
26 import org.apache.bcel.generic.MethodGen;
27 import org.apache.bcel.generic.ReturnInstruction;
28
29 import edu.umd.cs.findbugs.SystemProperties;
30 import edu.umd.cs.findbugs.ba.vna.ValueNumber;
31 import edu.umd.cs.findbugs.ba.vna.ValueNumberAnalysis;
32 import edu.umd.cs.findbugs.ba.vna.ValueNumberDataflow;
33 import edu.umd.cs.findbugs.ba.vna.ValueNumberFrame;
34
35
43 public class LockAnalysis extends ForwardDataflowAnalysis<LockSet> {
44 private static final boolean DEBUG = SystemProperties.getBoolean("la.debug");
45
46 private MethodGen methodGen;
47 private ValueNumberDataflow vnaDataflow;
48 private ValueNumberAnalysis vna;
49 private boolean isSynchronized;
50 private boolean isStatic;
51
52 public LockAnalysis(MethodGen methodGen, ValueNumberDataflow vnaDataflow, DepthFirstSearch dfs) {
53 super(dfs);
54 this.methodGen = methodGen;
55 this.vnaDataflow = vnaDataflow;
56 this.vna = vnaDataflow.getAnalysis();
57 this.isSynchronized = methodGen.isSynchronized();
58 this.isStatic = methodGen.isStatic();
59 if (DEBUG) System.out.println("Analyzing Locks in " + methodGen.getClassName() + "." + methodGen.getName());
60 }
61
62 public LockSet createFact() {
63 return new LockSet();
64 }
65
66 public void copy(LockSet source, LockSet dest) {
67 dest.copyFrom(source);
68 }
69
70 public void initEntryFact(LockSet result) {
71 result.clear();
72 result.setDefaultLockCount(0);
73
74 if (isSynchronized && !isStatic) {
75 ValueNumber thisValue = vna.getThisValue();
76 result.setLockCount(thisValue.getNumber(), 1);
77 } else if (isSynchronized && isStatic) {
78 ValueNumber thisValue = vna.getClassObjectValue(methodGen.getClassName());
79 result.setLockCount(thisValue.getNumber(), 1);
80 }
81 }
82
83 public void initResultFact(LockSet result) {
84 result.clear();
85 result.setDefaultLockCount(LockSet.TOP);
86 }
87
88 public void makeFactTop(LockSet fact) {
89 fact.clear();
90 fact.setDefaultLockCount(LockSet.TOP);
91 }
92 public boolean isTop(LockSet fact) {
93 return fact.isTop();
94 }
95 public boolean same(LockSet fact1, LockSet fact2) {
96 return fact1.sameAs(fact2);
97 }
98
99 public void meetInto(LockSet fact, Edge edge, LockSet result) throws DataflowAnalysisException {
100 result.meetWith(fact);
101 }
102
103 @Override 
104 public void transferInstruction(InstructionHandle handle, BasicBlock basicBlock, LockSet fact)
105 throws DataflowAnalysisException {
106
107 Instruction ins = handle.getInstruction();
108 short opcode = ins.getOpcode();
109 if (opcode == Constants.MONITORENTER || opcode == Constants.MONITOREXIT) {
110 ValueNumberFrame frame = vnaDataflow.getFactAtLocation(new Location(handle, basicBlock));
111
112 if (frame.isValid()) {
115 int lockNumber = frame.getTopValue().getNumber();
116 lockOp(fact, lockNumber, opcode == Constants.MONITORENTER ? 1 : -1);
117 }
118 } else if ((ins instanceof ReturnInstruction) && isSynchronized && !isStatic) {
119 lockOp(fact, vna.getThisValue().getNumber(), -1);
120 }
121 }
122
123 private void lockOp(LockSet fact, int lockNumber, int delta) {
124 int value = fact.getLockCount(lockNumber);
125 if (value < 0) return;
127 value += delta;
128 if (value < 0)
129 value = LockSet.BOTTOM;
130 if (DEBUG) System.out.println("Setting " + lockNumber + " to " + value + " in " + methodGen.getClassName() + "." + methodGen.getName());
131 fact.setLockCount(lockNumber, value);
132 }
133
134 @Override
135 public boolean isFactValid(LockSet fact) {
136 return true;
137 }
138
139 public static void main(String [] argv) throws Exception {
140 if (argv.length != 1) {
141 System.err.println("Usage: " + LockAnalysis.class.getName() + " <classfile>");
142 System.exit(1);
143 }
144
145 DataflowTestDriver<LockSet, LockAnalysis> driver = new DataflowTestDriver<LockSet, LockAnalysis>() {
146 @Override
147 public Dataflow<LockSet, LockAnalysis> createDataflow(ClassContext classContext, Method method)
148 throws CFGBuilderException, DataflowAnalysisException {
149 return classContext.getLockDataflow(method);
150 }
151 };
152
153 driver.execute(argv[0]);
154 }
155 }
156
157 |
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