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
|
/*
* 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.instruction.visitor.InstructionVisitor;
import proguard.classfile.util.SimplifiedVisitor;
import java.util.Arrays;
/**
* This AttributeVisitor marks the local variables that are used in the code
* attributes that it visits.
*
* @author Eric Lafortune
*/
public class VariableUsageMarker
extends SimplifiedVisitor
implements AttributeVisitor,
InstructionVisitor
{
private boolean[] variableUsed = new boolean[ClassConstants.TYPICAL_VARIABLES_SIZE];
/**
* Returns whether the given variable has been marked as being used.
*/
public boolean isVariableUsed(int variableIndex)
{
return variableUsed[variableIndex];
}
// Implementations for AttributeVisitor.
public void visitAnyAttribute(Clazz clazz, Attribute attribute) {}
public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute)
{
int maxLocals = codeAttribute.u2maxLocals;
// Try to reuse the previous array.
if (variableUsed.length < maxLocals)
{
// Create a new array.
variableUsed = new boolean[maxLocals];
}
else
{
// Reset the array.
Arrays.fill(variableUsed, 0, maxLocals, false);
}
codeAttribute.instructionsAccept(clazz, method, this);
}
// Implementations for InstructionVisitor.
public void visitAnyInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, Instruction instruction) {}
public void visitVariableInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, VariableInstruction variableInstruction)
{
// Mark the variable.
variableUsed[variableInstruction.variableIndex] = true;
// Account for Category 2 instructions, which take up two entries.
if (variableInstruction.isCategory2())
{
variableUsed[variableInstruction.variableIndex + 1] = true;
}
}
}
|
