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1
19
20 package edu.umd.cs.findbugs.ba;
21
22 import java.util.BitSet  ;
23
24 import org.apache.bcel.classfile.Method;
25 import org.apache.bcel.generic.IINC;
26 import org.apache.bcel.generic.IndexedInstruction;
27 import org.apache.bcel.generic.Instruction;
28 import org.apache.bcel.generic.InstructionHandle;
29 import org.apache.bcel.generic.LoadInstruction;
30 import org.apache.bcel.generic.LocalVariableInstruction;
31 import org.apache.bcel.generic.MethodGen;
32 import org.apache.bcel.generic.RET;
33 import org.apache.bcel.generic.StoreInstruction;
34
35
47 public class LiveLocalStoreAnalysis extends BackwardDataflowAnalysis<BitSet >
48 implements Debug {
49 private int topBit ;
50 private int killedByStoreOffset;
51
52 public LiveLocalStoreAnalysis(MethodGen methodGen, ReverseDepthFirstSearch rdfs, DepthFirstSearch dfs) {
53 super(rdfs, dfs);
54 this.topBit = methodGen.getMaxLocals() * 2;
55 this.killedByStoreOffset = methodGen.getMaxLocals();
56 }
57
58 public BitSet createFact() {
59 return new BitSet ();
60 }
61
62 public void copy(BitSet source, BitSet dest) {
63 dest.clear();
64 dest.or(source);
65 }
66
67 public void initEntryFact(BitSet result) throws DataflowAnalysisException {
68 result.clear();
69 }
70
71 public void initResultFact(BitSet result) {
72 makeFactTop(result);
73 }
74
75 public void makeFactTop(BitSet fact) {
76 fact.clear();
77 fact.set(topBit);
78 }
79
80 public boolean same(BitSet fact1, BitSet fact2) {
81 return fact1.equals(fact2);
82 }
83
84 public void meetInto(BitSet fact, Edge edge, BitSet result) throws DataflowAnalysisException {
85 isFactValid(fact);
86 isFactValid(result);
87
88 if (isTop(fact)) {
89 } else if (isTop(result)) {
91 copy(fact, result);
93 } else {
94 result.or(fact);
96 }
97
98 isFactValid(result);
99 }
100
101 @Override
102 public void transferInstruction(InstructionHandle handle, BasicBlock basicBlock, BitSet fact)
103 throws DataflowAnalysisException {
104 isFactValid(fact);
105
106 Instruction ins = handle.getInstruction();
107
108 if (ins instanceof StoreInstruction || ins instanceof IINC) {
109
112 LocalVariableInstruction store = (LocalVariableInstruction) ins;
113 int local = store.getIndex();
114 fact.clear(local);
115 fact.set(local + killedByStoreOffset);
116 }
117
118 if (ins instanceof LoadInstruction || ins instanceof IINC || ins instanceof RET) {
119
122 IndexedInstruction load = (IndexedInstruction) ins;
123 int local = load.getIndex();
124 fact.set(local);
125 fact.clear(local + killedByStoreOffset);
126 }
127
128 isFactValid(fact);
129 }
130
131 @Override
132 public boolean isFactValid(BitSet fact) {
133 if (VERIFY_INTEGRITY) {
134 if (isTop(fact) && fact.nextSetBit(0) < topBit)
135 throw new IllegalStateException ();
136 }
137 return !isTop(fact);
138 }
139
140 @Override
141 public String factToString(BitSet fact) {
142 if (isTop(fact))
143 return "[TOP]";
144 else
145 return fact.toString();
146 }
147
148
151 public boolean isTop(BitSet fact) {
152 return fact.get(topBit);
153 }
154
155
161 public boolean isStoreAlive(BitSet fact, int local) {
162 return fact.get(local);
163 }
164
165
169 public boolean killedByStore(BitSet fact, int local) {
170 return fact.get(local + killedByStoreOffset);
171 }
172
173 public static void main(String [] argv) throws Exception {
174 if (argv.length != 1) {
175 System.err.println("Usage: " + LiveLocalStoreAnalysis.class.getName() +
176 " <classfile>");
177 System.exit(1);
178 }
179
180 String filename = argv[0];
181
182 DataflowTestDriver<BitSet ,LiveLocalStoreAnalysis> driver =
183 new DataflowTestDriver<BitSet , LiveLocalStoreAnalysis>() {
184
185 @Override
186 public Dataflow<BitSet , LiveLocalStoreAnalysis> createDataflow(ClassContext classContext, Method method)
187 throws CFGBuilderException, DataflowAnalysisException {
188 return classContext.getLiveLocalStoreDataflow(method);
189 }
190 };
191
192 driver.execute(filename);
193 }
194 }
195
196 |
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