1 files changed, 115 insertions, 0 deletions
diff --git a/src/proguard/optimize/peephole/GotoReturnReplacer.java b/src/proguard/optimize/peephole/GotoReturnReplacer.java
new file mode 100644
index 0000000..5c3eb77
--- /dev/null
+++ b/src/proguard/optimize/peephole/GotoReturnReplacer.java
@@ -0,0 +1,115 @@
+/*
+ * 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 replaces unconditional branches to return instructions
+ * by these same return instructions.
+ *
+ * @author Eric Lafortune
+ */
+public class GotoReturnReplacer
+extends      SimplifiedVisitor
+implements   InstructionVisitor
+{
+    private final CodeAttributeEditor codeAttributeEditor;
+    private final InstructionVisitor  extraInstructionVisitor;
+
+
+    /**
+     * Creates a new GotoReturnReplacer.
+     * @param codeAttributeEditor     a code editor that can be used for
+     *                                accumulating changes to the code.
+     */
+    public GotoReturnReplacer(CodeAttributeEditor codeAttributeEditor)
+    {
+        this(codeAttributeEditor, null);
+    }
+
+
+    /**
+     * Creates a new GotoReturnReplacer.
+     * @param codeAttributeEditor     a code editor that can be used for
+     *                                accumulating changes to the code.
+     * @param extraInstructionVisitor an optional extra visitor for all replaced
+     *                                goto instructions.
+     */
+    public GotoReturnReplacer(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 visitBranchInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, BranchInstruction branchInstruction)
+    {
+        // Check if the instruction is an unconditional goto instruction.
+        byte opcode = branchInstruction.opcode;
+        if (opcode == InstructionConstants.OP_GOTO ||
+            opcode == InstructionConstants.OP_GOTO_W)
+        {
+            // Check if the goto instruction points to a return instruction.
+            int targetOffset = offset + branchInstruction.branchOffset;
+
+            if (!codeAttributeEditor.isModified(offset) &&
+                !codeAttributeEditor.isModified(targetOffset))
+            {
+                Instruction targetInstruction = InstructionFactory.create(codeAttribute.code,
+                                                                          targetOffset);
+                switch (targetInstruction.opcode)
+                {
+                    case InstructionConstants.OP_IRETURN:
+                    case InstructionConstants.OP_LRETURN:
+                    case InstructionConstants.OP_FRETURN:
+                    case InstructionConstants.OP_DRETURN:
+                    case InstructionConstants.OP_ARETURN:
+                    case InstructionConstants.OP_RETURN:
+                        // Replace the goto instruction by the return instruction.
+                        Instruction returnInstruction =
+                             new SimpleInstruction(targetInstruction.opcode);
+                        codeAttributeEditor.replaceInstruction(offset,
+                                                               returnInstruction);
+
+                        // Visit the instruction, if required.
+                        if (extraInstructionVisitor != null)
+                        {
+                            extraInstructionVisitor.visitBranchInstruction(clazz, method, codeAttribute, offset, branchInstruction);
+                        }
+
+                        break;
+                }
+            }
+        }
+    }
+}