src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.core.test/src/org/graalvm/compiler/core/test/UnbalancedMonitorsTest.java - platform/libcore - Git at Google

 /*
  * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code 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
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */


 package org.graalvm.compiler.core.test;

 import org.graalvm.compiler.java.GraphBuilderPhase;
 import org.graalvm.compiler.nodes.StructuredGraph;
 import org.graalvm.compiler.nodes.graphbuilderconf.GraphBuilderConfiguration;
 import org.graalvm.compiler.nodes.graphbuilderconf.GraphBuilderConfiguration.Plugins;
 import org.graalvm.compiler.nodes.graphbuilderconf.InvocationPlugins;
 import org.graalvm.compiler.options.OptionValues;
 import org.graalvm.compiler.phases.OptimisticOptimizations;
 import org.junit.Test;
 import org.objectweb.asm.ClassWriter;
 import org.objectweb.asm.Label;
 import org.objectweb.asm.MethodVisitor;
 import org.objectweb.asm.Opcodes;

 import jdk.vm.ci.code.BailoutException;
 import jdk.vm.ci.meta.ResolvedJavaMethod;

 /**
  * Exercise handling of unbalanced monitor operations by the parser. Algorithmically Graal assumes
  * that locks are statically block structured but that isn't something enforced by the bytecodes. In
  * HotSpot a dataflow is performed to ensure they are properly structured and methods with
  * unstructured locking aren't compiled and fall back to the interpreter. Having the Graal parser
  * handle this directly is simplifying for targets of Graal since they don't have to provide a data
  * flow that checks this property.
  */
 public class UnbalancedMonitorsTest extends GraalCompilerTest {
     private static final String CLASS_NAME = UnbalancedMonitorsTest.class.getName();
     private static final String INNER_CLASS_NAME = CLASS_NAME + "$UnbalancedMonitors";
     private static final String CLASS_NAME_INTERNAL = CLASS_NAME.replace('.', '/');
     private static final String INNER_CLASS_NAME_INTERNAL = INNER_CLASS_NAME.replace('.', '/');

     public UnbalancedMonitorsTest() {
         exportPackage(JAVA_BASE, "jdk.internal.org.objectweb.asm");
     }

     private static AsmLoader LOADER = new AsmLoader(UnbalancedMonitorsTest.class.getClassLoader());

     @Test
     public void runWrongOrder() throws Exception {
         checkForBailout("wrongOrder");
     }

     @Test
     public void runTooFewExits() throws Exception {
         checkForBailout("tooFewExits");
     }

     @Test
     public void runTooManyExits() throws Exception {
         checkForBailout("tooManyExits");
     }

     @Test
     public void runTooFewExitsExceptional() throws Exception {
         checkForBailout("tooFewExitsExceptional");
     }

     @Test
     public void runTooManyExitsExceptional() throws Exception {
         checkForBailout("tooManyExitsExceptional");
     }

     private void checkForBailout(String name) throws ClassNotFoundException {
         ResolvedJavaMethod method = getResolvedJavaMethod(LOADER.findClass(INNER_CLASS_NAME), name);
         try {
             OptionValues options = getInitialOptions();
             StructuredGraph graph = new StructuredGraph.Builder(options, getDebugContext(options, null, method)).method(method).build();
             Plugins plugins = new Plugins(new InvocationPlugins());
             GraphBuilderConfiguration graphBuilderConfig = GraphBuilderConfiguration.getDefault(plugins).withEagerResolving(true).withUnresolvedIsError(true);
             OptimisticOptimizations optimisticOpts = OptimisticOptimizations.NONE;

             GraphBuilderPhase.Instance graphBuilder = new GraphBuilderPhase.Instance(getMetaAccess(), getProviders().getStampProvider(), null, null, graphBuilderConfig, optimisticOpts, null);
             graphBuilder.apply(graph);
         } catch (BailoutException e) {
             if (e.getMessage().contains("unbalanced monitors")) {
                 return;
             }
             throw e;
         }
         assertTrue("should have bailed out", false);
     }

     static class Gen implements Opcodes {

     // @formatter:off
     // Template class used with Bytecode Outline to generate ASM code
     //    public static class UnbalancedMonitors {
     //
     //        public UnbalancedMonitors() {
     //        }
     //
     //        public Object wrongOrder(Object a, Object b) {
     //            synchronized (a) {
     //                synchronized (b) {
     //                    return b;
     //                }
     //            }
     //        }
     //
     //        public Object tooFewExits(Object a, Object b) {
     //            synchronized (a) {
     //                synchronized (b) {
     //                    return b;
     //                }
     //            }
     //        }
     //
     //        public boolean tooFewExitsExceptional(Object a, Object b) {
     //            synchronized (a) {
     //                synchronized (b) {
     //                    return b.equals(a);
     //                }
     //            }
     //        }
     //    }
     // @formatter:on

         public static byte[] generateClass() {

             ClassWriter cw = new ClassWriter(0);

             cw.visit(52, ACC_SUPER | ACC_PUBLIC, INNER_CLASS_NAME_INTERNAL, null, "java/lang/Object", null);

             cw.visitSource("UnbalancedMonitorsTest.java", null);

             cw.visitInnerClass(INNER_CLASS_NAME_INTERNAL, CLASS_NAME_INTERNAL, "UnbalancedMonitors", ACC_STATIC);

             visitConstructor(cw);
             visitWrongOrder(cw);
             visitBlockStructured(cw, true, false);
             visitBlockStructured(cw, true, true);
             visitBlockStructured(cw, false, false);
             visitBlockStructured(cw, false, true);
             cw.visitEnd();

             return cw.toByteArray();
         }

         private static void visitBlockStructured(ClassWriter cw, boolean normalReturnError, boolean tooMany) {
             String name = (tooMany ? "tooMany" : "tooFew") + "Exits" + (normalReturnError ? "" : "Exceptional");
             // Generate too many or too few exits down the either the normal or exceptional return
             // paths
             int exceptionalExitCount = normalReturnError ? 1 : (tooMany ? 2 : 0);
             int normalExitCount = normalReturnError ? (tooMany ? 2 : 0) : 1;
             MethodVisitor mv;
             mv = cw.visitMethod(ACC_PUBLIC, name, "(Ljava/lang/Object;Ljava/lang/Object;)Z", null, null);
             mv.visitCode();
             Label l0 = new Label();
             Label l1 = new Label();
             Label l2 = new Label();
             mv.visitTryCatchBlock(l0, l1, l2, null);
             Label l3 = new Label();
             mv.visitTryCatchBlock(l2, l3, l2, null);
             Label l4 = new Label();
             Label l5 = new Label();
             Label l6 = new Label();
             mv.visitTryCatchBlock(l4, l5, l6, null);
             Label l7 = new Label();
             mv.visitTryCatchBlock(l2, l7, l6, null);
             Label l8 = new Label();
             mv.visitLabel(l8);
             mv.visitVarInsn(ALOAD, 1);
             mv.visitInsn(DUP);
             mv.visitVarInsn(ASTORE, 3);
             mv.visitInsn(MONITORENTER);
             mv.visitLabel(l4);
             mv.visitVarInsn(ALOAD, 2);
             mv.visitInsn(DUP);
             mv.visitVarInsn(ASTORE, 4);
             mv.visitInsn(MONITORENTER);
             mv.visitLabel(l0);
             mv.visitVarInsn(ALOAD, 2);
             mv.visitVarInsn(ALOAD, 1);
             mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Object", "equals", "(Ljava/lang/Object;)Z", false);
             mv.visitVarInsn(ALOAD, 4);
             mv.visitInsn(MONITOREXIT);
             mv.visitLabel(l1);
             for (int i = 0; i < normalExitCount; i++) {
                 mv.visitVarInsn(ALOAD, 3);
                 mv.visitInsn(MONITOREXIT);
             }
             mv.visitLabel(l5);
             mv.visitInsn(IRETURN);
             mv.visitLabel(l2);
             mv.visitFrame(Opcodes.F_FULL, 5, new Object[]{INNER_CLASS_NAME_INTERNAL, "java/lang/Object", "java/lang/Object", "java/lang/Object",
                             "java/lang/Object"}, 1, new Object[]{"java/lang/Throwable"});
             mv.visitVarInsn(ALOAD, 4);
             mv.visitInsn(MONITOREXIT);
             mv.visitLabel(l3);
             mv.visitInsn(ATHROW);
             mv.visitLabel(l6);
             mv.visitFrame(Opcodes.F_FULL, 4, new Object[]{INNER_CLASS_NAME_INTERNAL, "java/lang/Object", "java/lang/Object", "java/lang/Object"}, 1,
                             new Object[]{"java/lang/Throwable"});
             for (int i = 0; i < exceptionalExitCount; i++) {
                 mv.visitVarInsn(ALOAD, 3);
                 mv.visitInsn(MONITOREXIT);
             }
             mv.visitLabel(l7);
             mv.visitInsn(ATHROW);
             Label l9 = new Label();
             mv.visitLabel(l9);
             mv.visitMaxs(2, 5);
             mv.visitEnd();
         }

         private static void visitWrongOrder(ClassWriter cw) {
             MethodVisitor mv;
             mv = cw.visitMethod(ACC_PUBLIC, "wrongOrder", "(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;", null, null);
             mv.visitCode();
             Label l0 = new Label();
             Label l1 = new Label();
             Label l2 = new Label();
             mv.visitTryCatchBlock(l0, l1, l2, null);
             Label l3 = new Label();
             mv.visitTryCatchBlock(l2, l3, l2, null);
             Label l4 = new Label();
             Label l5 = new Label();
             Label l6 = new Label();
             mv.visitTryCatchBlock(l4, l5, l6, null);
             Label l7 = new Label();
             mv.visitTryCatchBlock(l2, l7, l6, null);
             Label l8 = new Label();
             mv.visitLabel(l8);
             mv.visitVarInsn(ALOAD, 1);
             mv.visitInsn(DUP);
             mv.visitVarInsn(ASTORE, 3);
             mv.visitInsn(MONITORENTER);
             mv.visitLabel(l4);
             mv.visitVarInsn(ALOAD, 2);
             mv.visitInsn(DUP);
             mv.visitVarInsn(ASTORE, 4);
             mv.visitInsn(MONITORENTER);
             mv.visitLabel(l0);
             mv.visitVarInsn(ALOAD, 2);
             mv.visitVarInsn(ALOAD, 3);
             mv.visitInsn(MONITOREXIT);
             mv.visitLabel(l1);
             // Swapped exit order with exit above
             mv.visitVarInsn(ALOAD, 4);
             mv.visitInsn(MONITOREXIT);
             mv.visitLabel(l5);
             mv.visitInsn(ARETURN);
             mv.visitLabel(l2);
             mv.visitFrame(Opcodes.F_FULL, 5, new Object[]{INNER_CLASS_NAME_INTERNAL, "java/lang/Object", "java/lang/Object", "java/lang/Object",
                             "java/lang/Object"}, 1, new Object[]{"java/lang/Throwable"});
             mv.visitVarInsn(ALOAD, 4);
             mv.visitInsn(MONITOREXIT);
             mv.visitLabel(l3);
             mv.visitInsn(ATHROW);
             mv.visitLabel(l6);
             mv.visitFrame(Opcodes.F_FULL, 4, new Object[]{INNER_CLASS_NAME_INTERNAL, "java/lang/Object", "java/lang/Object", "java/lang/Object"}, 1,
                             new Object[]{"java/lang/Throwable"});
             mv.visitVarInsn(ALOAD, 3);
             mv.visitInsn(MONITOREXIT);
             mv.visitLabel(l7);
             mv.visitInsn(ATHROW);
             Label l9 = new Label();
             mv.visitLabel(l9);
             mv.visitMaxs(2, 5);
             mv.visitEnd();
         }

         private static void visitConstructor(ClassWriter cw) {
             MethodVisitor mv;
             mv = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
             mv.visitCode();
             Label l0 = new Label();
             mv.visitLabel(l0);
             mv.visitVarInsn(ALOAD, 0);
             mv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "<init>", "()V", false);
             Label l1 = new Label();
             mv.visitLabel(l1);
             mv.visitInsn(RETURN);
             Label l2 = new Label();
             mv.visitLabel(l2);
             mv.visitMaxs(1, 1);
             mv.visitEnd();
         }
     }

     public static class AsmLoader extends ClassLoader {
         Class<?> loaded;

         public AsmLoader(ClassLoader parent) {
             super(parent);
         }

         @Override
         protected Class<?> findClass(String name) throws ClassNotFoundException {
             if (name.equals(INNER_CLASS_NAME)) {
                 if (loaded != null) {
                     return loaded;
                 }
                 byte[] bytes = Gen.generateClass();
                 return (loaded = defineClass(name, bytes, 0, bytes.length));
             } else {
                 return super.findClass(name);
             }
         }
     }
 }
	/*
	* Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation.
	*
	* This code 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
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/


	package org.graalvm.compiler.core.test;

	import org.graalvm.compiler.java.GraphBuilderPhase;
	import org.graalvm.compiler.nodes.StructuredGraph;
	import org.graalvm.compiler.nodes.graphbuilderconf.GraphBuilderConfiguration;
	import org.graalvm.compiler.nodes.graphbuilderconf.GraphBuilderConfiguration.Plugins;
	import org.graalvm.compiler.nodes.graphbuilderconf.InvocationPlugins;
	import org.graalvm.compiler.options.OptionValues;
	import org.graalvm.compiler.phases.OptimisticOptimizations;
	import org.junit.Test;
	import org.objectweb.asm.ClassWriter;
	import org.objectweb.asm.Label;
	import org.objectweb.asm.MethodVisitor;
	import org.objectweb.asm.Opcodes;

	import jdk.vm.ci.code.BailoutException;
	import jdk.vm.ci.meta.ResolvedJavaMethod;

	/**
	* Exercise handling of unbalanced monitor operations by the parser. Algorithmically Graal assumes
	* that locks are statically block structured but that isn't something enforced by the bytecodes. In
	* HotSpot a dataflow is performed to ensure they are properly structured and methods with
	* unstructured locking aren't compiled and fall back to the interpreter. Having the Graal parser
	* handle this directly is simplifying for targets of Graal since they don't have to provide a data
	* flow that checks this property.
	*/
	public class UnbalancedMonitorsTest extends GraalCompilerTest {
	private static final String CLASS_NAME = UnbalancedMonitorsTest.class.getName();
	private static final String INNER_CLASS_NAME = CLASS_NAME + "$UnbalancedMonitors";
	private static final String CLASS_NAME_INTERNAL = CLASS_NAME.replace('.', '/');
	private static final String INNER_CLASS_NAME_INTERNAL = INNER_CLASS_NAME.replace('.', '/');

	public UnbalancedMonitorsTest() {
	exportPackage(JAVA_BASE, "jdk.internal.org.objectweb.asm");
	}

	private static AsmLoader LOADER = new AsmLoader(UnbalancedMonitorsTest.class.getClassLoader());

	@Test
	public void runWrongOrder() throws Exception {
	checkForBailout("wrongOrder");
	}

	@Test
	public void runTooFewExits() throws Exception {
	checkForBailout("tooFewExits");
	}

	@Test
	public void runTooManyExits() throws Exception {
	checkForBailout("tooManyExits");
	}

	@Test
	public void runTooFewExitsExceptional() throws Exception {
	checkForBailout("tooFewExitsExceptional");
	}

	@Test
	public void runTooManyExitsExceptional() throws Exception {
	checkForBailout("tooManyExitsExceptional");
	}

	private void checkForBailout(String name) throws ClassNotFoundException {
	ResolvedJavaMethod method = getResolvedJavaMethod(LOADER.findClass(INNER_CLASS_NAME), name);
	try {
	OptionValues options = getInitialOptions();
	StructuredGraph graph = new StructuredGraph.Builder(options, getDebugContext(options, null, method)).method(method).build();
	Plugins plugins = new Plugins(new InvocationPlugins());
	GraphBuilderConfiguration graphBuilderConfig = GraphBuilderConfiguration.getDefault(plugins).withEagerResolving(true).withUnresolvedIsError(true);
	OptimisticOptimizations optimisticOpts = OptimisticOptimizations.NONE;

	GraphBuilderPhase.Instance graphBuilder = new GraphBuilderPhase.Instance(getMetaAccess(), getProviders().getStampProvider(), null, null, graphBuilderConfig, optimisticOpts, null);
	graphBuilder.apply(graph);
	} catch (BailoutException e) {
	if (e.getMessage().contains("unbalanced monitors")) {
	return;
	}
	throw e;
	}
	assertTrue("should have bailed out", false);
	}

	static class Gen implements Opcodes {

	// @formatter:off
	// Template class used with Bytecode Outline to generate ASM code
	// public static class UnbalancedMonitors {
	//
	// public UnbalancedMonitors() {
	// }
	//
	// public Object wrongOrder(Object a, Object b) {
	// synchronized (a) {
	// synchronized (b) {
	// return b;
	// }
	// }
	// }
	//
	// public Object tooFewExits(Object a, Object b) {
	// synchronized (a) {
	// synchronized (b) {
	// return b;
	// }
	// }
	// }
	//
	// public boolean tooFewExitsExceptional(Object a, Object b) {
	// synchronized (a) {
	// synchronized (b) {
	// return b.equals(a);
	// }
	// }
	// }
	// }
	// @formatter:on

	public static byte[] generateClass() {

	ClassWriter cw = new ClassWriter(0);

	cw.visit(52, ACC_SUPER \| ACC_PUBLIC, INNER_CLASS_NAME_INTERNAL, null, "java/lang/Object", null);

	cw.visitSource("UnbalancedMonitorsTest.java", null);

	cw.visitInnerClass(INNER_CLASS_NAME_INTERNAL, CLASS_NAME_INTERNAL, "UnbalancedMonitors", ACC_STATIC);

	visitConstructor(cw);
	visitWrongOrder(cw);
	visitBlockStructured(cw, true, false);
	visitBlockStructured(cw, true, true);
	visitBlockStructured(cw, false, false);
	visitBlockStructured(cw, false, true);
	cw.visitEnd();

	return cw.toByteArray();
	}

	private static void visitBlockStructured(ClassWriter cw, boolean normalReturnError, boolean tooMany) {
	String name = (tooMany ? "tooMany" : "tooFew") + "Exits" + (normalReturnError ? "" : "Exceptional");
	// Generate too many or too few exits down the either the normal or exceptional return
	// paths
	int exceptionalExitCount = normalReturnError ? 1 : (tooMany ? 2 : 0);
	int normalExitCount = normalReturnError ? (tooMany ? 2 : 0) : 1;
	MethodVisitor mv;
	mv = cw.visitMethod(ACC_PUBLIC, name, "(Ljava/lang/Object;Ljava/lang/Object;)Z", null, null);
	mv.visitCode();
	Label l0 = new Label();
	Label l1 = new Label();
	Label l2 = new Label();
	mv.visitTryCatchBlock(l0, l1, l2, null);
	Label l3 = new Label();
	mv.visitTryCatchBlock(l2, l3, l2, null);
	Label l4 = new Label();
	Label l5 = new Label();
	Label l6 = new Label();
	mv.visitTryCatchBlock(l4, l5, l6, null);
	Label l7 = new Label();
	mv.visitTryCatchBlock(l2, l7, l6, null);
	Label l8 = new Label();
	mv.visitLabel(l8);
	mv.visitVarInsn(ALOAD, 1);
	mv.visitInsn(DUP);
	mv.visitVarInsn(ASTORE, 3);
	mv.visitInsn(MONITORENTER);
	mv.visitLabel(l4);
	mv.visitVarInsn(ALOAD, 2);
	mv.visitInsn(DUP);
	mv.visitVarInsn(ASTORE, 4);
	mv.visitInsn(MONITORENTER);
	mv.visitLabel(l0);
	mv.visitVarInsn(ALOAD, 2);
	mv.visitVarInsn(ALOAD, 1);
	mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Object", "equals", "(Ljava/lang/Object;)Z", false);
	mv.visitVarInsn(ALOAD, 4);
	mv.visitInsn(MONITOREXIT);
	mv.visitLabel(l1);
	for (int i = 0; i < normalExitCount; i++) {
	mv.visitVarInsn(ALOAD, 3);
	mv.visitInsn(MONITOREXIT);
	}
	mv.visitLabel(l5);
	mv.visitInsn(IRETURN);
	mv.visitLabel(l2);
	mv.visitFrame(Opcodes.F_FULL, 5, new Object[]{INNER_CLASS_NAME_INTERNAL, "java/lang/Object", "java/lang/Object", "java/lang/Object",
	"java/lang/Object"}, 1, new Object[]{"java/lang/Throwable"});
	mv.visitVarInsn(ALOAD, 4);
	mv.visitInsn(MONITOREXIT);
	mv.visitLabel(l3);
	mv.visitInsn(ATHROW);
	mv.visitLabel(l6);
	mv.visitFrame(Opcodes.F_FULL, 4, new Object[]{INNER_CLASS_NAME_INTERNAL, "java/lang/Object", "java/lang/Object", "java/lang/Object"}, 1,
	new Object[]{"java/lang/Throwable"});
	for (int i = 0; i < exceptionalExitCount; i++) {
	mv.visitVarInsn(ALOAD, 3);
	mv.visitInsn(MONITOREXIT);
	}
	mv.visitLabel(l7);
	mv.visitInsn(ATHROW);
	Label l9 = new Label();
	mv.visitLabel(l9);
	mv.visitMaxs(2, 5);
	mv.visitEnd();
	}

	private static void visitWrongOrder(ClassWriter cw) {
	MethodVisitor mv;
	mv = cw.visitMethod(ACC_PUBLIC, "wrongOrder", "(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;", null, null);
	mv.visitCode();
	Label l0 = new Label();
	Label l1 = new Label();
	Label l2 = new Label();
	mv.visitTryCatchBlock(l0, l1, l2, null);
	Label l3 = new Label();
	mv.visitTryCatchBlock(l2, l3, l2, null);
	Label l4 = new Label();
	Label l5 = new Label();
	Label l6 = new Label();
	mv.visitTryCatchBlock(l4, l5, l6, null);
	Label l7 = new Label();
	mv.visitTryCatchBlock(l2, l7, l6, null);
	Label l8 = new Label();
	mv.visitLabel(l8);
	mv.visitVarInsn(ALOAD, 1);
	mv.visitInsn(DUP);
	mv.visitVarInsn(ASTORE, 3);
	mv.visitInsn(MONITORENTER);
	mv.visitLabel(l4);
	mv.visitVarInsn(ALOAD, 2);
	mv.visitInsn(DUP);
	mv.visitVarInsn(ASTORE, 4);
	mv.visitInsn(MONITORENTER);
	mv.visitLabel(l0);
	mv.visitVarInsn(ALOAD, 2);
	mv.visitVarInsn(ALOAD, 3);
	mv.visitInsn(MONITOREXIT);
	mv.visitLabel(l1);
	// Swapped exit order with exit above
	mv.visitVarInsn(ALOAD, 4);
	mv.visitInsn(MONITOREXIT);
	mv.visitLabel(l5);
	mv.visitInsn(ARETURN);
	mv.visitLabel(l2);
	mv.visitFrame(Opcodes.F_FULL, 5, new Object[]{INNER_CLASS_NAME_INTERNAL, "java/lang/Object", "java/lang/Object", "java/lang/Object",
	"java/lang/Object"}, 1, new Object[]{"java/lang/Throwable"});
	mv.visitVarInsn(ALOAD, 4);
	mv.visitInsn(MONITOREXIT);
	mv.visitLabel(l3);
	mv.visitInsn(ATHROW);
	mv.visitLabel(l6);
	mv.visitFrame(Opcodes.F_FULL, 4, new Object[]{INNER_CLASS_NAME_INTERNAL, "java/lang/Object", "java/lang/Object", "java/lang/Object"}, 1,
	new Object[]{"java/lang/Throwable"});
	mv.visitVarInsn(ALOAD, 3);
	mv.visitInsn(MONITOREXIT);
	mv.visitLabel(l7);
	mv.visitInsn(ATHROW);
	Label l9 = new Label();
	mv.visitLabel(l9);
	mv.visitMaxs(2, 5);
	mv.visitEnd();
	}

	private static void visitConstructor(ClassWriter cw) {
	MethodVisitor mv;
	mv = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
	mv.visitCode();
	Label l0 = new Label();
	mv.visitLabel(l0);
	mv.visitVarInsn(ALOAD, 0);
	mv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "<init>", "()V", false);
	Label l1 = new Label();
	mv.visitLabel(l1);
	mv.visitInsn(RETURN);
	Label l2 = new Label();
	mv.visitLabel(l2);
	mv.visitMaxs(1, 1);
	mv.visitEnd();
	}
	}

	public static class AsmLoader extends ClassLoader {
	Class<?> loaded;

	public AsmLoader(ClassLoader parent) {
	super(parent);
	}

	@Override
	protected Class<?> findClass(String name) throws ClassNotFoundException {
	if (name.equals(INNER_CLASS_NAME)) {
	if (loaded != null) {
	return loaded;
	}
	byte[] bytes = Gen.generateClass();
	return (loaded = defineClass(name, bytes, 0, bytes.length));
	} else {
	return super.findClass(name);
	}
	}
	}
	}