Simple version of redundant GOTO's removing

compiler/backend/src/org/jetbrains/jet/codegen/optimization/OptimizationMethodVisitor.java

@@ -35,7 +35,8 @@ import java.util.List;
 public class OptimizationMethodVisitor extends MethodVisitor {
     private static final int MEMORY_LIMIT_BY_METHOD_MB = 50;
     private static final MethodTransformer[] TRANSFORMERS = new MethodTransformer[]{
-            new RedundantNullCheckMethodTransformer(), new RedundantBoxingMethodTransformer()
+            new RedundantNullCheckMethodTransformer(), new RedundantBoxingMethodTransformer(),
+            new RedundantGotoMethodTransformer()
     };
 
     private final MethodNode methodNode;

compiler/backend/src/org/jetbrains/jet/codegen/optimization/RedundantGotoMethodTransformer.kt

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2010-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.jet.codegen.optimization
+
+import org.jetbrains.jet.codegen.optimization.transformer.MethodTransformer
+import org.jetbrains.org.objectweb.asm.tree.MethodNode
+import org.jetbrains.org.objectweb.asm.tree.AbstractInsnNode
+import org.jetbrains.org.objectweb.asm.tree.LabelNode
+import org.jetbrains.org.objectweb.asm.Opcodes
+import org.jetbrains.org.objectweb.asm.tree.JumpInsnNode
+
+
+public class RedundantGotoMethodTransformer : MethodTransformer() {
+    /**
+     * Removes redundant GOTO's, i.e. to subsequent labels
+     */
+    override fun transform(internalClassName: String, methodNode: MethodNode) {
+        val insns = methodNode.instructions.toArray()
+        val insnsToRemove = arrayListOf<AbstractInsnNode>()
+
+        val currentLabels = hashSetOf<LabelNode>()
+        for (insn in insns.reverse()) {
+            if (insn.isMeaningful) {
+                if (insn.getOpcode() == Opcodes.GOTO && (insn as JumpInsnNode).label in currentLabels) {
+                    insnsToRemove.add(insn)
+                }
+                else {
+                    currentLabels.clear()
+                }
+                continue
+            }
+
+            if (insn is LabelNode) {
+                currentLabels.add(insn)
+            }
+        }
+
+        for (insnToRemove in insnsToRemove) {
+            methodNode.instructions.remove(insnToRemove)
+        }
+    }
+}
+
+private val AbstractInsnNode.isMeaningful : Boolean get() =
+    when (this.getType()) {
+        AbstractInsnNode.LABEL, AbstractInsnNode.LINE, AbstractInsnNode.FRAME -> false
+        else -> true
+    }