1 files changed, 95 insertions, 0 deletions
diff --git a/src/proguard/optimize/info/VariableUsageMarker.java b/src/proguard/optimize/info/VariableUsageMarker.java
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+++ b/src/proguard/optimize/info/VariableUsageMarker.java
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+/*
+ * ProGuard -- shrinking, optimization, obfuscation, and preverification
+ *             of Java bytecode.
+ *
+ * Copyright (c) 2002-2009 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;
+
+/**
+ * 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)
+        {
+            variableUsed = new boolean[maxLocals];
+        }
+        else
+        {
+            for (int index = 0; index < maxLocals; index++)
+            {
+                variableUsed[index] = 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;
+        }
+    }
+}