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
|
/*
* 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;
import proguard.classfile.*;
import proguard.classfile.attribute.*;
import proguard.classfile.attribute.visitor.AttributeVisitor;
import proguard.classfile.editor.VariableRemapper;
import proguard.classfile.util.*;
import proguard.classfile.visitor.MemberVisitor;
import proguard.optimize.info.ParameterUsageMarker;
/**
* This MemberVisitor removes unused parameters from the code of the methods
* that it visits.
*
* @see ParameterUsageMarker
* @see MethodStaticizer
* @see MethodDescriptorShrinker
* @author Eric Lafortune
*/
public class ParameterShrinker
extends SimplifiedVisitor
implements AttributeVisitor
{
private static final boolean DEBUG = false;
private final MemberVisitor extraVariableMemberVisitor;
private final VariableRemapper variableRemapper = new VariableRemapper();
/**
* Creates a new ParameterShrinker.
*/
public ParameterShrinker()
{
this(null);
}
/**
* Creates a new ParameterShrinker with an extra visitor.
* @param extraVariableMemberVisitor an optional extra visitor for all
* removed parameters.
*/
public ParameterShrinker(MemberVisitor extraVariableMemberVisitor)
{
this.extraVariableMemberVisitor = extraVariableMemberVisitor;
}
// Implementations for AttributeVisitor.
public void visitAnyAttribute(Clazz clazz, Attribute attribute) {}
public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute)
{
// Get the original parameter size that was saved.
int oldParameterSize = ParameterUsageMarker.getParameterSize(method);
// Compute the new parameter size from the shrunk descriptor.
int newParameterSize =
ClassUtil.internalMethodParameterSize(method.getDescriptor(clazz),
method.getAccessFlags());
if (oldParameterSize > newParameterSize)
{
// Get the total size of the local variable frame.
int maxLocals = codeAttribute.u2maxLocals;
if (DEBUG)
{
System.out.println("ParameterShrinker: "+clazz.getName()+"."+method.getName(clazz)+method.getDescriptor(clazz));
System.out.println(" Old parameter size = " + oldParameterSize);
System.out.println(" New parameter size = " + newParameterSize);
System.out.println(" Max locals = " + maxLocals);
}
// Create a variable map.
int[] variableMap = new int[maxLocals];
// Move unused parameters right after the parameter block.
int usedParameterIndex = 0;
int unusedParameterIndex = newParameterSize;
for (int parameterIndex = 0; parameterIndex < oldParameterSize; parameterIndex++)
{
// Is the variable required as a parameter?
if (ParameterUsageMarker.isParameterUsed(method, parameterIndex))
{
// Keep the variable as a parameter.
variableMap[parameterIndex] = usedParameterIndex++;
}
else
{
if (DEBUG)
{
System.out.println(" Deleting parameter #"+parameterIndex);
}
// Shift the variable to the unused parameter block,
// in case it is still used as a variable.
variableMap[parameterIndex] = unusedParameterIndex++;
// Visit the method, if required.
if (extraVariableMemberVisitor != null)
{
method.accept(clazz, extraVariableMemberVisitor);
}
}
}
// Fill out the remainder of the map.
for (int variableIndex = oldParameterSize; variableIndex < maxLocals; variableIndex++)
{
variableMap[variableIndex] = variableIndex;
}
// Set the map.
variableRemapper.setVariableMap(variableMap);
// Remap the variables.
variableRemapper.visitCodeAttribute(clazz, method, codeAttribute);
}
}
}
|
