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1
19
20 package edu.umd.cs.findbugs.detect;
21
22 import org.apache.bcel.classfile.Code;
23 import org.apache.bcel.classfile.JavaClass;
24 import org.apache.bcel.classfile.Method;
25
26 import edu.umd.cs.findbugs.BugInstance;
27 import edu.umd.cs.findbugs.BugReporter;
28 import edu.umd.cs.findbugs.BytecodeScanningDetector;
29 import edu.umd.cs.findbugs.FieldAnnotation;
30 import edu.umd.cs.findbugs.LocalVariableAnnotation;
31 import edu.umd.cs.findbugs.OpcodeStack;
32 import edu.umd.cs.findbugs.ba.SignatureParser;
33 import edu.umd.cs.findbugs.ba.XField;
34
35 public class FindSelfComparison extends BytecodeScanningDetector {
36
37 BugReporter bugReporter;
38
39 OpcodeStack stack = new OpcodeStack();
40
41 public FindSelfComparison(BugReporter bugReporter) {
42 this.bugReporter = bugReporter;
43 }
44
45 @Override 
46 public void visit(JavaClass obj) {
47 }
48
49 @Override
50 public void visit(Method obj) {
51 }
52
53 @Override
54 public void visit(Code obj) {
55 whichRegister = -1;
56 registerLoadCount = 0;
57 stack.resetForMethodEntry(this);
58 super.visit(obj);
59 }
60
61 @Override
62 public void sawOpcode(int seen) {
63 stack.mergeJumps(this);
65
66 switch (seen) {
67 case INVOKEVIRTUAL:
68 case INVOKEINTERFACE:
69 if (getClassName().toLowerCase().indexOf("test") >= 0) break;
70 if (getMethodName().toLowerCase().indexOf("test") >= 0) break;
71 if (getSuperclassName().toLowerCase().indexOf("test") >= 0) break;
72
73 String name = getNameConstantOperand();
74 if (name.equals("equals") ||
75 name.equals("compareTo")) {
76 String sig = getSigConstantOperand();
77 SignatureParser parser = new SignatureParser(sig);
78 if (parser.getNumParameters() == 1 &&
79 (name.equals("equals") && sig.endsWith(";)Z")
80 || name.equals("compareTo") && sig.endsWith(";)I")))
81 checkForSelfOperation(seen, "COMPARISON");
82 }
83 break;
84
85 case LOR:
86 case LAND:
87 case LXOR:
88 case LSUB:
89 case IOR:
90 case IAND:
91 case IXOR:
92 case ISUB:
93 checkForSelfOperation(seen, "COMPUTATION");
94 break;
95 case FCMPG:
96 case DCMPG:
97 case DCMPL:
98 case FCMPL:
99 break;
100 case LCMP:
101 case IF_ACMPEQ:
102 case IF_ACMPNE:
103 case IF_ICMPNE:
104 case IF_ICMPEQ:
105 case IF_ICMPGT:
106 case IF_ICMPLE:
107 case IF_ICMPLT:
108 case IF_ICMPGE:
109 checkForSelfOperation(seen, "COMPARISON");
110 }
111 stack.sawOpcode(this, seen);
112 if (isRegisterLoad() && seen != IINC) {
113 if (getRegisterOperand() == whichRegister) registerLoadCount++;
114 else {
115 whichRegister = getRegisterOperand();
116 registerLoadCount = 1;
117 }
118 } else {
119 whichRegister = -1;
120 registerLoadCount = 0;
121 }
122 }
123 int whichRegister;
124 int registerLoadCount;
125
126
127
128 private void checkForSelfOperation(int opCode, String op) {
129 {
130
131 OpcodeStack.Item item0 = stack.getStackItem(0);
132 OpcodeStack.Item item1 = stack.getStackItem(1);
133
134 if (item0.getSignature().equals("D")
135 || item0.getSignature().equals("F"))
136 return;
137 if (item1.getSignature().equals("D")
138 || item1.getSignature().equals("F"))
139 return;
140
141 XField field0 = item0.getXField();
142 XField field1 = item1.getXField();
143 int fr0 = item0.getFieldLoadedFromRegister();
144 int fr1 = item1.getFieldLoadedFromRegister();
145 if (field0 != null && field0.equals(field1) && fr0 != -1 && fr0 == fr1)
146 bugReporter.reportBug(new BugInstance(this,
147 "SA_FIELD_SELF_" + op, NORMAL_PRIORITY)
148 .addClassAndMethod(this).addField(field0)
149 .addSourceLine(this));
150
151 else if (opCode == ISUB && registerLoadCount >= 2) { bugReporter.reportBug(new BugInstance(this,
153 "SA_LOCAL_SELF_" + op, (opCode == ISUB || opCode == LSUB || opCode == INVOKEINTERFACE || opCode == INVOKEVIRTUAL) ? NORMAL_PRIORITY : HIGH_PRIORITY)
154 .addClassAndMethod(this).add(
155 LocalVariableAnnotation
156 .getLocalVariableAnnotation(
157 getMethod(), whichRegister, getPC(),
158 getPC() - 1))
159 .addSourceLine(this));
160 }
161 }
162 }
163 } |
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