1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
|
/*
* ProGuard -- shrinking, optimization, obfuscation, and preverification
* of Java bytecode.
*
* Copyright (c) 2002-2013 Eric Lafortune (eric@graphics.cornell.edu)
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package proguard.optimize.info;
import proguard.classfile.*;
import proguard.classfile.attribute.*;
import proguard.classfile.attribute.visitor.AttributeVisitor;
import proguard.classfile.instruction.*;
import proguard.classfile.util.SimplifiedVisitor;
import proguard.classfile.visitor.*;
/**
* This ClassPoolVisitor marks all methods that have side effects.
*
* @see ReadWriteFieldMarker
* @see NoSideEffectMethodMarker
* @author Eric Lafortune
*/
public class SideEffectMethodMarker
extends SimplifiedVisitor
implements ClassPoolVisitor,
ClassVisitor,
MemberVisitor,
AttributeVisitor
{
// Reusable objects for checking whether instructions have side effects.
private final SideEffectInstructionChecker sideEffectInstructionChecker = new SideEffectInstructionChecker(false, true);
private final SideEffectInstructionChecker initializerSideEffectInstructionChecker = new SideEffectInstructionChecker(false, false);
// Parameters and values for visitor methods.
private int newSideEffectCount;
private boolean hasSideEffects;
// Implementations for ClassPoolVisitor.
public void visitClassPool(ClassPool classPool)
{
// Go over all classes and their methods, marking if they have side
// effects, until no new cases can be found.
do
{
newSideEffectCount = 0;
// Go over all classes and their methods once.
classPool.classesAccept(this);
}
while (newSideEffectCount > 0);
}
// Implementations for ClassVisitor.
public void visitProgramClass(ProgramClass programClass)
{
// Go over all methods.
programClass.methodsAccept(this);
}
// Implementations for MemberVisitor.
public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod)
{
if (!hasSideEffects(programMethod) &&
!NoSideEffectMethodMarker.hasNoSideEffects(programMethod))
{
// Initialize the return value.
hasSideEffects =
(programMethod.getAccessFlags() &
(ClassConstants.INTERNAL_ACC_NATIVE |
ClassConstants.INTERNAL_ACC_SYNCHRONIZED)) != 0;
// Look further if the method hasn't been marked yet.
if (!hasSideEffects)
{
// Investigate the actual code.
programMethod.attributesAccept(programClass, this);
}
// Mark the method depending on the return value.
if (hasSideEffects)
{
markSideEffects(programMethod);
newSideEffectCount++;
}
}
}
// Implementations for AttributeVisitor.
public void visitAnyAttribute(Clazz clazz, Attribute attribute) {}
public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute)
{
// Remember whether the code has any side effects.
hasSideEffects = hasSideEffects(clazz, method, codeAttribute);
}
// Small utility methods.
/**
* Returns whether the given code has any side effects.
*/
private boolean hasSideEffects(Clazz clazz,
Method method,
CodeAttribute codeAttribute)
{
byte[] code = codeAttribute.code;
int length = codeAttribute.u4codeLength;
SideEffectInstructionChecker checker =
method.getName(clazz).equals(ClassConstants.INTERNAL_METHOD_NAME_CLINIT) ?
initializerSideEffectInstructionChecker :
sideEffectInstructionChecker;
// Go over all instructions.
int offset = 0;
do
{
// Get the current instruction.
Instruction instruction = InstructionFactory.create(code, offset);
// Check if it may be throwing exceptions.
if (checker.hasSideEffects(clazz,
method,
codeAttribute,
offset,
instruction))
{
return true;
}
// Go to the next instruction.
offset += instruction.length(offset);
}
while (offset < length);
return false;
}
private static void markSideEffects(Method method)
{
MethodOptimizationInfo info = MethodOptimizationInfo.getMethodOptimizationInfo(method);
if (info != null)
{
info.setSideEffects();
}
}
public static boolean hasSideEffects(Method method)
{
MethodOptimizationInfo info = MethodOptimizationInfo.getMethodOptimizationInfo(method);
return info == null ||
info.hasSideEffects();
}
}
|
