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1
19
20 package edu.umd.cs.findbugs.detect;
21
22 import edu.umd.cs.findbugs.*;
23
24 import org.apache.bcel.classfile.Method;
25
26 public class FindNonShortCircuit extends BytecodeScanningDetector implements
27 StatelessDetector {
28
29 int stage1 = 0;
30 int stage2 = 0;
31 int distance = 0;
32 int operator;
33
34 boolean sawDanger;
35 boolean sawNullTestOld;
36 boolean sawNullTestVeryOld;
37 boolean sawNullTest;
38 boolean sawDangerOld;
39 boolean sawArrayIndex;
40 boolean sawArrayIndexOld;
41 boolean sawNumericTest, sawNumericTestOld, sawNumericTestVeryOld;
42 boolean sawArrayDanger, sawArrayDangerOld;
43
44 private BugReporter bugReporter;
45
46 public FindNonShortCircuit(BugReporter bugReporter) {
47 this.bugReporter = bugReporter;
48 }
49
50 OpcodeStack stack = new OpcodeStack();
51
52 @Override 
53 public void visit(Method obj) {
54 stack.resetForMethodEntry(this);
55 stage1 = 0;
56 stage2 = 0;
57 distance = 1000000;
58 sawArrayDanger = sawArrayDangerOld = false;
59 sawDanger = sawDangerOld = false;
60 sawNullTest = sawNullTestOld = sawNullTestVeryOld = false;
61 sawNumericTest = sawNumericTestOld = sawNumericTestVeryOld = false;
62 prevOpcode = NOP;
63 }
64
65 int prevOpcode;
66 @Override
67 public void sawOpcode(int seen) {
68 stack.mergeJumps(this);
69 distance++;
72 scanForBooleanValue(seen);
73 scanForDanger(seen);
74 scanForShortCircuit(seen);
75 stack.sawOpcode(this, seen);
76 prevOpcode = seen;
77 }
78
79 private void scanForDanger(int seen) {
80 switch (seen) {
81 case AALOAD:
82 case BALOAD:
83 case SALOAD:
84 case CALOAD:
85 case IALOAD:
86 case LALOAD:
87 case FALOAD:
88 case DALOAD:
89 sawArrayDanger = true;
90 sawDanger = true;
91 break;
92
93 case INVOKEINTERFACE:
94 case INVOKESPECIAL:
95 case INVOKEVIRTUAL:
96 case INVOKESTATIC:
97 case ARRAYLENGTH:
98 case IDIV:
99 case IREM:
100 case GETFIELD:
101 sawDanger = true;
102 break;
103 default:
104 break;
105 }
106
107 }
108
109 private void scanForShortCircuit(int seen) {
110 switch (seen) {
111 case IAND:
112 case IOR:
113 OpcodeStack.Item item0 = stack.getStackItem(0);
115 OpcodeStack.Item item1 = stack.getStackItem(1);
116 if (item0.getConstant() == null && item1.getConstant() == null && distance < 4) {
117 operator = seen;
118 stage2 = 1;
119 } else
120 stage2 = 0;
121 break;
122 case IFEQ:
123 case IFNE:
124 if (stage2 == 1) {
125 reportBug();
127 }
128 stage2 = 0;
129 break;
130 case PUTFIELD:
131 case PUTSTATIC:
132 case IRETURN:
133 if (operator == IAND && stage2 == 1) {
134 reportBug();
135 }
136 stage2 = 0;
137 break;
138 default:
139 stage2 = 0;
140 break;
141 }
142 }
143
144 private void reportBug() {
145 int priority = LOW_PRIORITY;
146 if (sawDangerOld)
147 if (sawNullTestVeryOld) priority = HIGH_PRIORITY;
148 else if (sawNumericTestVeryOld && sawArrayDangerOld) priority = HIGH_PRIORITY;
149 else priority = NORMAL_PRIORITY;
150
151 bugReporter.reportBug(new BugInstance(this, "NS_NON_SHORT_CIRCUIT",
152 priority)
153 .addClassAndMethod(this).addSourceLine(this, getPC()));
154 }
155
156
157 private void scanForBooleanValue(int seen) {
158 switch (seen) {
159
160 case ICONST_1:
161 stage1 = 1;
162 switch(prevOpcode) {
163 case IFNONNULL:
164 case IFNULL:
165 sawNullTest = true;
166 break;
167 case IF_ICMPGT:
168 case IF_ICMPGE:
169 case IF_ICMPLT:
170 case IF_ICMPLE:
171 sawNumericTest = true;
172 break;
173 }
174
175 break;
176 case GOTO:
177 if (stage1 == 1)
178 stage1 = 2;
179 else
180 stage1 = 0;
181 break;
182 case ICONST_0:
183 if (stage1 == 2)
184 sawBooleanValue();
185 stage1 = 0;
186 break;
187 case INVOKEINTERFACE:
188 case INVOKEVIRTUAL:
189 case INVOKESPECIAL:
190 case INVOKESTATIC:
191 String sig = getSigConstantOperand();
192 if (sig.endsWith(")Z"))
193 sawBooleanValue();
194 stage1 = 0;
195 break;
196 default:
197 stage1 = 0;
198 }
199 }
200
201 private void sawBooleanValue() {
202 sawDangerOld = sawDanger;
203 sawArrayDangerOld = sawArrayDanger;
204 sawNullTestVeryOld = sawNullTestOld;
205 sawNullTestOld = sawNullTest;
206 sawNumericTestVeryOld = sawNumericTestOld;
207 sawNumericTestOld = sawNumericTest;
208 sawNumericTest = false;
209 sawDanger = false;
210 sawArrayDanger = false;
211 distance = 0;
212 stage1 = 0;
213
214 }
215 }
216 |
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