1 files changed, 89 insertions, 0 deletions
diff --git a/src/proguard/optimize/peephole/NopRemover.java b/src/proguard/optimize/peephole/NopRemover.java
new file mode 100644
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+++ b/src/proguard/optimize/peephole/NopRemover.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.peephole;
+
+import proguard.classfile.*;
+import proguard.classfile.attribute.CodeAttribute;
+import proguard.classfile.editor.CodeAttributeEditor;
+import proguard.classfile.instruction.*;
+import proguard.classfile.instruction.visitor.InstructionVisitor;
+import proguard.classfile.util.SimplifiedVisitor;
+
+/**
+ * This InstructionVisitor removes all nop instructions that it encounters.
+ *
+ * @author Eric Lafortune
+ */
+public class NopRemover
+extends      SimplifiedVisitor
+implements   InstructionVisitor
+{
+    private final CodeAttributeEditor codeAttributeEditor;
+    private final InstructionVisitor  extraInstructionVisitor;
+
+
+    /**
+     * Creates a new NopRemover.
+     * @param codeAttributeEditor a code editor that can be used for
+     *                            accumulating changes to the code.
+     */
+    public NopRemover(CodeAttributeEditor codeAttributeEditor)
+    {
+        this(codeAttributeEditor, null);
+    }
+
+
+    /**
+     * Creates a new NopRemover.
+     * @param codeAttributeEditor     a code editor that can be used for
+     *                                accumulating changes to the code.
+     * @param extraInstructionVisitor an optional extra visitor for all removed
+     *                                nop instructions.
+     */
+    public NopRemover(CodeAttributeEditor codeAttributeEditor,
+                      InstructionVisitor  extraInstructionVisitor)
+    {
+        this.codeAttributeEditor     = codeAttributeEditor;
+        this.extraInstructionVisitor = extraInstructionVisitor;
+    }
+
+
+    // Implementations for InstructionVisitor.
+
+    public void visitAnyInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, Instruction instruction) {}
+
+
+    public void visitSimpleInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, SimpleInstruction simpleInstruction)
+    {
+        // Check if the instruction is a nop instruction.
+        if (simpleInstruction.opcode == InstructionConstants.OP_NOP &&
+            !codeAttributeEditor.isModified(offset))
+        {
+            codeAttributeEditor.deleteInstruction(offset);
+
+            // Visit the instruction, if required.
+            if (extraInstructionVisitor != null)
+            {
+                extraInstructionVisitor.visitSimpleInstruction(clazz, method, codeAttribute, offset, simpleInstruction);
+            }
+        }
+    }
+}