BasicInvocationUnit


1   /*
2    * ProGuard -- shrinking, optimization, obfuscation, and preverification
3    *             of Java bytecode.
4    *
5    * Copyright (c) 2002-2007 Eric Lafortune (eric@graphics.cornell.edu)
6    *
7    * This library is free software; you can redistribute it and/or modify it
8    * under the terms of the GNU General Public License as published by the Free
9    * Software Foundation; either version 2 of the License, or (at your option)
10   * any later version.
11   *
12   * This library is distributed in the hope that it will be useful, but WITHOUT
13   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14   * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
15   * for more details.
16   *
17   * You should have received a copy of the GNU Lesser General Public License
18   * along with this library; if not, write to the Free Software Foundation,
19   * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20   */
21  package proguard.evaluation;
22  
23  import proguard.classfile.util.*;
24  import proguard.classfile.constant.visitor.ConstantVisitor;
25  import proguard.classfile.constant.*;
26  import proguard.classfile.visitor.MemberVisitor;
27  import proguard.classfile.*;
28  import proguard.classfile.instruction.*;
29  import proguard.classfile.attribute.CodeAttribute;
30  import proguard.evaluation.value.*;
31  
32  /**
33   * This InvocationUnit sets up the variables for entering a method,
34   * and it updates the stack for the invocation of a class member,
35   * using simple values.
36   *
37   * @author Eric Lafortune
38   */
39  public class BasicInvocationUnit
40  extends      SimplifiedVisitor
41  implements   InvocationUnit,
42               ConstantVisitor,
43               MemberVisitor
44  {
45      private ValueFactory valueFactory = new ValueFactory();
46  
47      // Fields acting as parameters between the visitor methods.
48      private boolean isStatic;
49      private boolean isLoad;
50      private Stack   stack;
51      private Clazz   returnTypeClass;
52  
53  
54      /**
55       * Sets up the given variables for entering the given method.
56       */
57      public void enterMethod(Clazz clazz, Method method, Variables variables)
58      {
59          String   descriptor = method.getDescriptor(clazz);
60  
61          // Initialize the parameters.
62          boolean isStatic =
63              (method.getAccessFlags() & ClassConstants.INTERNAL_ACC_STATIC) != 0;
64  
65          // Count the number of parameters, taking into account their categories.
66          int parameterSize = ClassUtil.internalMethodParameterSize(descriptor);
67          if (!isStatic)
68          {
69              parameterSize++;
70          }
71  
72          // Reuse the existing parameters object, ensuring the right size.
73          variables.reset(parameterSize);
74  
75          // Go over the parameters again.
76          InternalTypeEnumeration internalTypeEnumeration =
77              new InternalTypeEnumeration(descriptor);
78  
79          int parameterIndex = 0;
80          int variableIndex  = 0;
81  
82          // Put the 'this' reference in variable 0.
83          if (!isStatic)
84          {
85              // Get the reference value.
86              Value value = getMethodParameterValue(clazz,
87                                                    method,
88                                                    parameterIndex++,
89                                                    ClassUtil.internalTypeFromClassName(clazz.getName()),
90                                                    clazz);
91  
92              // Store the value in variable 0.
93              variables.store(variableIndex++, value);
94          }
95  
96          Clazz[] referencedClasses = ((ProgramMethod)method).referencedClasses;
97          int referencedClassIndex = 0;
98  
99          // Set up the variables corresponding to the parameter types and values.
100         while (internalTypeEnumeration.hasMoreTypes())
101         {
102             String   type = internalTypeEnumeration.nextType();
103 
104             Clazz referencedClass = referencedClasses != null &&
105                                     ClassUtil.isInternalClassType(type) ?
106                 referencedClasses[referencedClassIndex++] :
107                 null;
108 
109             // Get the parameter value.
110             Value value = getMethodParameterValue(clazz,
111                                                   method,
112                                                   parameterIndex++,
113                                                   type,
114                                                   referencedClass);
115 
116             // Store the value in the corresponding variable.
117             variables.store(variableIndex++, value);
118 
119             // Increment the variable index again for Category 2 values.
120             if (value.isCategory2())
121             {
122                 variableIndex++;
123             }
124         }
125     }
126 
127 
128     /**
129      * Exits the given method with the given return value.
130      */
131     public void exitMethod(Clazz clazz, Method method, Value returnValue)
132     {
133         setMethodReturnValue(clazz, method, returnValue);
134     }
135 
136 
137     /**
138      * Updates the given stack corresponding to the execution of the given
139      * field or method reference instruction.
140      */
141     public void invokeMember(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, ConstantInstruction constantInstruction, Stack stack)
142     {
143         int constantIndex = constantInstruction.constantIndex;
144 
145         switch (constantInstruction.opcode)
146         {
147             case InstructionConstants.OP_GETSTATIC:
148                 isStatic = true;
149                 isLoad   = true;
150                 break;
151 
152             case InstructionConstants.OP_PUTSTATIC:
153                 isStatic = true;
154                 isLoad   = false;
155                 break;
156 
157             case InstructionConstants.OP_GETFIELD:
158                 isStatic = false;
159                 isLoad   = true;
160                 break;
161 
162             case InstructionConstants.OP_PUTFIELD:
163                 isStatic = false;
164                 isLoad   = false;
165                 break;
166 
167             case InstructionConstants.OP_INVOKESTATIC:
168                 isStatic = true;
169                 break;
170 
171             case InstructionConstants.OP_INVOKEVIRTUAL:
172             case InstructionConstants.OP_INVOKESPECIAL:
173             case InstructionConstants.OP_INVOKEINTERFACE:
174                 isStatic = false;
175                 break;
176         }
177 
178         // Pop the parameters and push the return value.
179         this.stack = stack;
180         clazz.constantPoolEntryAccept(constantIndex, this);
181         this.stack = null;
182     }
183 
184 
185     // Implementations for ConstantVisitor.
186 
187     public void visitFieldrefConstant(Clazz clazz, FieldrefConstant fieldrefConstant)
188     {
189         // Pop the field value, if applicable.
190         if (!isLoad)
191         {
192             setFieldValue(clazz, fieldrefConstant, stack.pop());
193         }
194 
195         // Pop the reference value, if applicable.
196         if (!isStatic)
197         {
198             setFieldClassValue(clazz, fieldrefConstant, stack.apop());
199         }
200 
201         // Push the field value, if applicable.
202         if (isLoad)
203         {
204             String   type = fieldrefConstant.getType(clazz);
205 
206             stack.push(getFieldValue(clazz, fieldrefConstant, type));
207         }
208     }
209 
210 
211     public void visitAnyMethodrefConstant(Clazz clazz, RefConstant methodrefConstant)
212     {
213         String   type = methodrefConstant.getType(clazz);
214 
215         // Count the number of parameters.
216         int parameterCount = ClassUtil.internalMethodParameterCount(type);
217         if (!isStatic)
218         {
219             parameterCount++;
220         }
221 
222         // Pop the parameters and the class reference, in reverse order.
223         for (int parameterIndex = parameterCount-1; parameterIndex >= 0; parameterIndex--)
224         {
225             setMethodParameterValue(clazz, methodrefConstant, parameterIndex, stack.pop());
226         }
227 
228         // Pop the reference value, if applicable.
229         // Push the return value, if applicable.
230         String   returnType = ClassUtil.internalMethodReturnType(type);
231         if (returnType.charAt(0) != ClassConstants.INTERNAL_TYPE_VOID)
232         {
233             stack.push(getMethodReturnValue(clazz, methodrefConstant, returnType));
234         }
235     }
236 
237 
238     protected void setFieldClassValue(Clazz          clazz,
239                                       RefConstant    refConstant,
240                                       ReferenceValue value)
241     {
242         // We don't care about the new value.
243     }
244 
245 
246     protected Value getFieldClassValue(Clazz       clazz,
247                                        RefConstant refConstant,
248                                        String        type)
249     {
250         // Try to figure out the class of the return type.
251         returnTypeClass = null;
252         refConstant.referencedMemberAccept(this);
253 
254         return valueFactory.createValue(type,
255                                         returnTypeClass,
256                                         true);
257     }
258 
259 
260     protected void setFieldValue(Clazz       clazz,
261                                  RefConstant refConstant,
262                                  Value       value)
263     {
264         // We don't care about the new field value.
265     }
266 
267 
268     protected Value getFieldValue(Clazz       clazz,
269                                   RefConstant refConstant,
270                                   String        type)
271     {
272         // Try to figure out the class of the return type.
273         returnTypeClass = null;
274         refConstant.referencedMemberAccept(this);
275 
276         return valueFactory.createValue(type,
277                                         returnTypeClass,
278                                         true);
279     }
280 
281 
282     protected void setMethodParameterValue(Clazz       clazz,
283                                            RefConstant refConstant,
284                                            int         parameterIndex,
285                                            Value       value)
286     {
287         // We don't care about the parameter value.
288     }
289 
290 
291     protected Value getMethodParameterValue(Clazz  clazz,
292                                             Method method,
293                                             int    parameterIndex,
294                                             String   type,
295                                             Clazz  referencedClass)
296     {
297         return valueFactory.createValue(type, referencedClass, true);
298     }
299 
300 
301     protected void setMethodReturnValue(Clazz  clazz,
302                                         Method method,
303                                         Value  value)
304     {
305         // We don't care about the return value.
306     }
307 
308 
309     protected Value getMethodReturnValue(Clazz       clazz,
310                                          RefConstant refConstant,
311                                          String        type)
312     {
313         // Try to figure out the class of the return type.
314         returnTypeClass = null;
315         refConstant.referencedMemberAccept(this);
316 
317         return valueFactory.createValue(type,
318                                         returnTypeClass,
319                                         true);
320     }
321 
322 
323     // Implementations for MemberVisitor.
324 
325     public void visitProgramField(ProgramClass programClass, ProgramField programField)
326     {
327         returnTypeClass = programField.referencedClass;
328     }
329 
330 
331     public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod)
332     {
333         Clazz[] referencedClasses = programMethod.referencedClasses;
334         if (referencedClasses != null)
335         {
336             returnTypeClass = referencedClasses[referencedClasses.length - 1];
337         }
338     }
339 
340 
341     public void visitLibraryMember(LibraryClass libraryClass, LibraryMember libraryMember)
342     {
343         // Library members don't store the referenced classes.
344     }
345 }
346
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