1 files changed, 135 insertions, 0 deletions
diff --git a/src/proguard/classfile/editor/VariableCleaner.java b/src/proguard/classfile/editor/VariableCleaner.java
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+++ b/src/proguard/classfile/editor/VariableCleaner.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.classfile.editor;
+
+import proguard.classfile.*;
+import proguard.classfile.attribute.*;
+import proguard.classfile.attribute.visitor.*;
+import proguard.classfile.instruction.*;
+import proguard.classfile.instruction.visitor.InstructionVisitor;
+import proguard.classfile.util.SimplifiedVisitor;
+import proguard.optimize.info.VariableUsageMarker;
+
+/**
+ * This AttributeVisitor cleans up unused variables in all attributes that it
+ * visits.
+ *
+ * @author Eric Lafortune
+ */
+public class VariableCleaner
+extends      SimplifiedVisitor
+implements   AttributeVisitor
+{
+    private final VariableUsageMarker variableUsageMarker = new VariableUsageMarker();
+
+
+    // Implementations for AttributeVisitor.
+
+    public void visitAnyAttribute(Clazz clazz, Attribute attribute) {}
+
+
+    public void visitCodeAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute)
+    {
+        // Figure out the local variables that are used by the code.
+        variableUsageMarker.visitCodeAttribute(clazz, method, codeAttribute);
+
+        // Clean up the variables of the attributes.
+        codeAttribute.attributesAccept(clazz, method, this);
+    }
+
+
+    public void visitLocalVariableTableAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute, LocalVariableTableAttribute localVariableTableAttribute)
+    {
+        // Clean up local variables that aren't used.
+        localVariableTableAttribute.u2localVariableTableLength =
+            removeEmptyLocalVariables(localVariableTableAttribute.localVariableTable,
+                                      localVariableTableAttribute.u2localVariableTableLength,
+                                      codeAttribute.u2maxLocals);
+    }
+
+
+    public void visitLocalVariableTypeTableAttribute(Clazz clazz, Method method, CodeAttribute codeAttribute, LocalVariableTypeTableAttribute localVariableTypeTableAttribute)
+    {
+        // Clean up local variables that aren't used.
+        localVariableTypeTableAttribute.u2localVariableTypeTableLength =
+            removeEmptyLocalVariableTypes(localVariableTypeTableAttribute.localVariableTypeTable,
+                                          localVariableTypeTableAttribute.u2localVariableTypeTableLength,
+                                          codeAttribute.u2maxLocals);
+    }
+
+
+    // Small utility methods.
+
+    /**
+     * Returns the given list of local variables, without the ones that aren't
+     * used
+     */
+    private int removeEmptyLocalVariables(LocalVariableInfo[] localVariableInfos,
+                                          int                 localVariableInfoCount,
+                                          int                 maxLocals)
+    {
+        // Overwrite all empty local variable entries.
+        int newIndex = 0;
+        for (int index = 0; index < localVariableInfoCount && index < maxLocals; index++)
+        {
+            if (variableUsageMarker.isVariableUsed(index))
+            {
+                localVariableInfos[newIndex++] = localVariableInfos[index];
+            }
+        }
+
+        // Clean up any remaining array elements.
+        for (int index = newIndex; index < localVariableInfoCount; index++)
+        {
+            localVariableInfos[index] = null;
+        }
+
+        return newIndex;
+    }
+
+
+    /**
+     * Returns the given list of local variable types, without the ones that
+     * aren't used
+     */
+    private int removeEmptyLocalVariableTypes(LocalVariableTypeInfo[] localVariableTypeInfos,
+                                              int                     localVariableTypeInfoCount,
+                                              int                     maxLocals)
+    {
+        // Overwrite all empty local variable type entries.
+        int newIndex = 0;
+        for (int index = 0; index < localVariableTypeInfoCount && index < maxLocals; index++)
+        {
+            if (variableUsageMarker.isVariableUsed(index))
+            {
+                localVariableTypeInfos[newIndex++] = localVariableTypeInfos[index];
+            }
+        }
+
+        // Clean up any remaining array elements.
+        for (int index = newIndex; index < localVariableTypeInfoCount; index++)
+        {
+            localVariableTypeInfos[index] = null;
+        }
+
+        return newIndex;
+    }
+}
+\ No newline at end of file