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19 package edu.umd.cs.findbugs.ba.constant;
20
21 import org.apache.bcel.classfile.Method;
22 import org.apache.bcel.generic.InstructionHandle;
23 import org.apache.bcel.generic.MethodGen;
24
25 import edu.umd.cs.findbugs.ba.BasicBlock;
26 import edu.umd.cs.findbugs.ba.CFGBuilderException;
27 import edu.umd.cs.findbugs.ba.ClassContext;
28 import edu.umd.cs.findbugs.ba.Dataflow;
29 import edu.umd.cs.findbugs.ba.DataflowAnalysisException;
30 import edu.umd.cs.findbugs.ba.DataflowTestDriver;
31 import edu.umd.cs.findbugs.ba.DepthFirstSearch;
32 import edu.umd.cs.findbugs.ba.Edge;
33 import edu.umd.cs.findbugs.ba.FrameDataflowAnalysis;
34 import edu.umd.cs.findbugs.ba.Location;
35
36
42 public class ConstantAnalysis extends FrameDataflowAnalysis<Constant, ConstantFrame> {
43 private MethodGen methodGen;
44 private ConstantFrameModelingVisitor visitor;
45
46 public ConstantAnalysis(MethodGen methodGen, DepthFirstSearch dfs) {
47 super(dfs);
48 this.methodGen = methodGen;
49 this.visitor = new ConstantFrameModelingVisitor(methodGen.getConstantPool());
50 }
51
52 public ConstantFrame createFact() {
53 return new ConstantFrame(methodGen.getMaxLocals());
54 }
55
56 public void initEntryFact(ConstantFrame frame) {
57 frame.setValid();
58 frame.clearStack();
59 int numSlots = frame.getNumSlots();
60 for (int i = 0; i < numSlots; ++i) {
61 frame.setValue(i, new Constant("parameter" + i));
62 }
63 }
64
65 @Override 
66 public void transferInstruction(
67 InstructionHandle handle,
68 BasicBlock basicBlock,
69 ConstantFrame frame) throws DataflowAnalysisException {
70 visitor.setFrameAndLocation(frame, new Location(handle, basicBlock));
71 visitor.analyzeInstruction(handle.getInstruction());
72 }
73
74 public void meetInto(
75 ConstantFrame fact,
76 Edge edge,
77 ConstantFrame result) throws DataflowAnalysisException {
78
79 if (fact.isValid()) {
80 ConstantFrame tmpFact = null;
81
82 if (edge.isExceptionEdge()) {
83 tmpFact = modifyFrame(fact, tmpFact);
84 tmpFact.clearStack();
85 tmpFact.pushValue(Constant.NOT_CONSTANT);
86 }
87
88 if (tmpFact != null) {
89 fact = tmpFact;
90 }
91 }
92
93 mergeInto(fact, result);
94 }
95
96 @Override
97 protected void mergeValues(ConstantFrame otherFrame, ConstantFrame resultFrame, int slot)
98 throws DataflowAnalysisException {
99 Constant value = Constant.merge(resultFrame.getValue(slot), otherFrame.getValue(slot));
100 resultFrame.setValue(slot, value);
101 }
102
103
106 public static void main(String [] argv) throws Exception {
107 if (argv.length != 1) {
108 System.err.println("Usage: " + ConstantAnalysis.class.getName() + " <class file>");
109 System.exit(1);
110 }
111
112 DataflowTestDriver<ConstantFrame, ConstantAnalysis> driver =
113 new DataflowTestDriver<ConstantFrame, ConstantAnalysis>() {
114 @Override
115 public Dataflow<ConstantFrame, ConstantAnalysis> createDataflow(
116 ClassContext classContext,
117 Method method) throws CFGBuilderException, DataflowAnalysisException {
118 return classContext.getConstantDataflow(method);
119 }
120 };
121
122 driver.execute(argv[0]);
123 }
124 }
125 |
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