Java Code Examples for org.objectweb.asm.ClassVisitor#visitMethod()

/**
 * Constructs a new {@link GeneratorAdapter}. <i>Subclasses must not use this constructor</i>.
 * Instead, they must use the {@link #GeneratorAdapter(int, MethodVisitor, int, String, String)}
 * version.
 *
 * @param access access flags of the adapted method.
 * @param method the adapted method.
 * @param signature the signature of the adapted method (may be {@literal null}).
 * @param exceptions the exceptions thrown by the adapted method (may be {@literal null}).
 * @param classVisitor the class visitor to which this adapter delegates calls.
 */
public GeneratorAdapter(
    final int access,
    final Method method,
    final String signature,
    final Type[] exceptions,
    final ClassVisitor classVisitor) {
  this(
      access,
      method,
      classVisitor.visitMethod(
          access,
          method.getName(),
          method.getDescriptor(),
          signature,
          exceptions == null ? null : getInternalNames(exceptions)));
}
 

private static void implementConstructor(ClassVisitor classVisitor,
        Class<? extends ProxyChannelRingBuffer> parentType,
        String generatedName,
        int primitiveMessageSize,
        int referenceMessageSize) {
    MethodVisitor methodVisitor = classVisitor.visitMethod(Opcodes.ACC_PUBLIC,
            "<init>",
            methodDescriptor(void.class,
                    int.class,
                    WaitStrategy.class),
            null,
            null);
    methodVisitor.visitCode();
    
    LocalsHelper locals = LocalsHelper.forInstanceMethod();
    int localIndexOfCapacity = locals.newLocal(int.class);
    int localIndexOfWaitStrategy = locals.newLocal(WaitStrategy.class);

    methodVisitor.visitVarInsn(Opcodes.ALOAD, LOCALS_INDEX_THIS);
    methodVisitor.visitVarInsn(Opcodes.ILOAD, localIndexOfCapacity);
    methodVisitor.visitLdcInsn(primitiveMessageSize);
    methodVisitor.visitLdcInsn(referenceMessageSize);
    
    methodVisitor.visitMethodInsn(Opcodes.INVOKESPECIAL,
            Type.getInternalName(parentType),
            "<init>",
            methodDescriptor(void.class,
                    int.class,
                    int.class,
                    int.class),
            false);
    
    methodVisitor.visitVarInsn(Opcodes.ALOAD, LOCALS_INDEX_THIS);
    methodVisitor.visitVarInsn(Opcodes.ALOAD, localIndexOfWaitStrategy);
    methodVisitor.visitFieldInsn(Opcodes.PUTFIELD, generatedName, "waitStrategy", Type.getDescriptor(WaitStrategy.class));
    
    methodVisitor.visitInsn(Opcodes.RETURN);

    methodVisitor.visitMaxs(-1, -1);
    methodVisitor.visitEnd();
}
 

private static void implementProxy(ClassVisitor classVisitor, Class<?> iFace, String generatedName) {
    MethodVisitor methodVisitor = classVisitor.visitMethod(Opcodes.ACC_PUBLIC,
            "proxy",
            methodDescriptor(iFace),
            null,
            null);

    methodVisitor.visitCode();

    methodVisitor.visitVarInsn(Opcodes.ALOAD, LOCALS_INDEX_THIS);
    methodVisitor.visitInsn(Opcodes.ARETURN);

    methodVisitor.visitMaxs(-1, -1);
    methodVisitor.visitEnd();
    
    implementBridgeMethod(classVisitor, generatedName, "proxy", iFace);
}
 

@Test
public void testInstrumentationLegacyClassOtherType() throws Exception {
    ClassVisitor classVisitor = TypeConstantAdjustment.INSTANCE.wrap(mock(TypeDescription.class),
            this.classVisitor,
            mock(Implementation.Context.class),
            mock(TypePool.class),
            new FieldList.Empty<FieldDescription.InDefinedShape>(),
            new MethodList.Empty<MethodDescription>(),
            IGNORED,
            IGNORED);
    classVisitor.visit(ClassFileVersion.JAVA_V4.getMinorMajorVersion(), FOOBAR, FOO, BAR, QUX, new String[]{BAZ});
    MethodVisitor methodVisitor = classVisitor.visitMethod(FOOBAR, FOO, BAR, QUX, new String[]{BAZ});
    assertThat(methodVisitor, not(this.methodVisitor));
    methodVisitor.visitLdcInsn(FOO);
    verify(this.classVisitor).visit(ClassFileVersion.JAVA_V4.getMinorMajorVersion(), FOOBAR, FOO, BAR, QUX, new String[]{BAZ});
    verify(this.classVisitor).visitMethod(FOOBAR, FOO, BAR, QUX, new String[]{BAZ});
    verifyNoMoreInteractions(this.classVisitor);
    verify(this.methodVisitor).visitLdcInsn(FOO);
    verifyNoMoreInteractions(this.methodVisitor);
}
 

/** Emits a bridge method for a field with a {@link Opcodes.PUTSTATIC} access. */
@Override
public MethodVisitor visitPutStatic(FieldKey fieldKey, ClassVisitor cv) {
  MethodKey bridgeMethodKey = fieldKey.bridgeOfStaticWrite();
  MethodVisitor mv =
      cv.visitMethod(
          ACC_SYNTHETIC | ACC_STATIC,
          bridgeMethodKey.name(),
          bridgeMethodKey.descriptor(),
          /* signature= */ null,
          /* exceptions= */ null);
  mv.visitCode();
  Type fieldType = fieldKey.getFieldType();
  mv.visitVarInsn(fieldType.getOpcode(Opcodes.ILOAD), 0);
  mv.visitInsn(
      LangModelHelper.getTypeSizeAlignedDupOpcode(ImmutableList.of(fieldKey.getFieldType())));
  mv.visitFieldInsn(
      Opcodes.PUTSTATIC, fieldKey.ownerName(), fieldKey.name(), fieldKey.descriptor());
  mv.visitInsn(fieldType.getOpcode(Opcodes.IRETURN));
  int fieldTypeSize = fieldType.getSize();
  mv.visitMaxs(fieldTypeSize, fieldTypeSize);
  mv.visitEnd();
  return mv;
}
 

/**
 * Constructs a new {@link GeneratorAdapter}. <i>Subclasses must not use this constructor</i>.
 * Instead, they must use the {@link #GeneratorAdapter(int, MethodVisitor, int, String, String)}
 * version.
 *
 * @param access access flags of the adapted method.
 * @param method the adapted method.
 * @param signature the signature of the adapted method (may be {@literal null}).
 * @param exceptions the exceptions thrown by the adapted method (may be {@literal null}).
 * @param classVisitor the class visitor to which this adapter delegates calls.
 */
public GeneratorAdapter(
    final int access,
    final Method method,
    final String signature,
    final Type[] exceptions,
    final ClassVisitor classVisitor) {
  this(
      access,
      method,
      classVisitor.visitMethod(
          access,
          method.getName(),
          method.getDescriptor(),
          signature,
          getInternalNames(exceptions)));
}
 

/**
 * Constructs a new {@link GeneratorAdapter}. <i>Subclasses must not use this constructor</i>.
 * Instead, they must use the {@link #GeneratorAdapter(int, MethodVisitor, int, String, String)}
 * version.
 *
 * @param access access flags of the adapted method.
 * @param method the adapted method.
 * @param signature the signature of the adapted method (may be <tt>null</tt>).
 * @param exceptions the exceptions thrown by the adapted method (may be <tt>null</tt>).
 * @param classVisitor the class visitor to which this adapter delegates calls.
 */
public GeneratorAdapter(
    final int access,
    final Method method,
    final String signature,
    final Type[] exceptions,
    final ClassVisitor classVisitor) {
  this(
      access,
      method,
      classVisitor.visitMethod(
          access,
          method.getName(),
          method.getDescriptor(),
          signature,
          getInternalNames(exceptions)));
}
 

/**
 * Generate the getter method for each arguments. These getters are not
 * available from consumer code, but instead are called by the injector to
 * retrieve each argument in turn for passing to the method invocation being
 * modified.
 * 
 * @param ref Class ref being generated
 * @param desc Argument descriptor
 * @param args Parsed argument list from descriptor
 * @param writer Class writer
 */
private void generateGetters(ArgsClassInfo info, ClassVisitor writer) {
    byte argIndex = 0;
    for (Type arg : info.args) {
        String name = ArgsClassGenerator.GETTER_PREFIX + argIndex;
        String sig = "()" + arg.getDescriptor();
        MethodVisitorEx get = new MethodVisitorEx(writer.visitMethod(Opcodes.ACC_PUBLIC, name, sig, null, null));
        get.visitCode();
        
        // Read the value from the values field
        get.visitVarInsn(Opcodes.ALOAD, 0);
        get.visitFieldInsn(Opcodes.GETFIELD, info.getName(), ArgsClassGenerator.VALUES_FIELD, ArgsClassGenerator.OBJECT_ARRAY);
        get.visitConstant(argIndex);
        get.visitInsn(Opcodes.AALOAD);
        
        // Unbox (if primitive) or cast down the value
        ArgsClassGenerator.unbox(get, arg);
        
        // Return the value
        get.visitInsn(arg.getOpcode(Opcodes.IRETURN));
        
        get.visitMaxs(2, 1);
        get.visitEnd();
        argIndex++;
    }
}
 

private static void enhanceForNewInstanceInner(ClassVisitor cw, String classNm, String enclosingClassNm) {
	MethodVisitor mv = cw.visitMethod(ACC_PUBLIC, "newInstance", "()LLjava/lang/Object;", null, null);
	mv.visitCode();
	mv.visitTypeInsn(NEW, classNm);
	mv.visitInsn(DUP);
	mv.visitTypeInsn(NEW, enclosingClassNm);
	mv.visitInsn(DUP);
	mv.visitMethodInsn(INVOKESPECIAL, enclosingClassNm, "<init>", "()V");
	mv.visitInsn(DUP);
	mv.visitMethodInsn(INVOKEVIRTUAL, classNm, "getClass", "()Ljava/lang/Class;");
	mv.visitInsn(POP);
	mv.visitMethodInsn(INVOKESPECIAL, classNm, "<init>", "(L" + enclosingClassNm + ";)V");
	mv.visitInsn(ARETURN);
	mv.visitMaxs(4, 1);
	mv.visitEnd();
}
 

private static void implementProxyInstance(ClassVisitor classVisitor, Class<?> iFace, String generatedName) {
    MethodVisitor methodVisitor = classVisitor.visitMethod(Opcodes.ACC_PUBLIC,
            "proxyInstance",
            methodDescriptor(iFace, iFace),
            null,
            null);
    methodVisitor.visitCode();

    methodVisitor.visitVarInsn(Opcodes.ALOAD, LOCALS_INDEX_THIS);
    methodVisitor.visitInsn(Opcodes.ARETURN);

    methodVisitor.visitMaxs(-1, -1);
    methodVisitor.visitEnd();
    
    implementBridgeMethod(classVisitor, generatedName, "proxyInstance", iFace, iFace);
}
 

public final MethodVisitor accept(ClassVisitor cv) {
  return cv.visitMethod(
      memberAccess(),
      methodKey().name(),
      methodKey().descriptor(),
      signature(),
      exceptionArray());
}
 

/**
 * Makes the given class visitor visit this method.
 * 
 * @param cv
 *          a class visitor.
 */
public void accept(final ClassVisitor cv) {
  String[] exceptions = new String[this.exceptions.size()];
  this.exceptions.toArray(exceptions);
  MethodVisitor mv = cv.visitMethod(access, name, desc, signature, exceptions);
  if (mv != null) {
    accept(mv);
  }
}
 

private static void enhanceForConstructor(ClassVisitor cw, String accessClassNm, String clazzNm) {
    MethodVisitor mv = cw.visitMethod(ACC_PUBLIC, "<init>", "(Ljava/lang/Class;)V", "(L" + clazzNm + ";)V", null);
    mv.visitCode();
    mv.visitVarInsn(ALOAD, 0);
    mv.visitVarInsn(ALOAD, 1);
    mv.visitMethodInsn(INVOKESPECIAL, INVOKEDYNAMIC_CLASS_ACCESS_NM, "<init>", "(Ljava/lang/Class;)V");
    mv.visitInsn(RETURN);
    mv.visitMaxs(2, 2);
    mv.visitEnd();
}
 

private static void enhanceForGetValuePrimitive(ClassVisitor cw, String accessClassNm, String clazzNm, Field[] fields, Type type) {

		String methodName;
		final String typeNm = type.getDescriptor();
		final int instruction;

		switch (type.getSort()) {
		case Type.BOOLEAN:
			methodName = "getBooleanValue";
			instruction = IRETURN;
			break;
		case Type.BYTE:
			methodName = "getByteValue";
			instruction = IRETURN;
			break;
		case Type.CHAR:
			methodName = "getCharValue";
			instruction = IRETURN;
			break;
		case Type.SHORT:
			methodName = "getShortValue";
			instruction = IRETURN;
			break;
		case Type.INT:
			methodName = "getIntValue";
			instruction = IRETURN;
			break;
		case Type.FLOAT:
			methodName = "getFloatValue";
			instruction = FRETURN;
			break;
		case Type.LONG:
			methodName = "getLongValue";
			instruction = LRETURN;
			break;
		case Type.DOUBLE:
			methodName = "getDoubleValue";
			instruction = DRETURN;
			break;
		default:
			methodName = "getValue";
			instruction = ARETURN;
			break;
		}

		MethodVisitor mv = cw.visitMethod(ACC_PUBLIC, methodName, "(Ljava/lang/Object;Ljava/lang/String;)" + typeNm, null, null);

		mv.visitCode();
		mv.visitVarInsn(ALOAD, 0);
		mv.visitFieldInsn(GETFIELD, accessClassNm, "fieldNames", "[Ljava/lang/String;");
		mv.visitVarInsn(ALOAD, 2);
		mv.visitMethodInsn(INVOKESTATIC, "java/util/Arrays", "binarySearch", "([Ljava/lang/Object;Ljava/lang/Object;)I");
		mv.visitVarInsn(ISTORE, 3);
		mv.visitVarInsn(ILOAD, 3);

		final int maxStack;

		if (fields.length > 0) {
			maxStack = 5;
			Label[] labels = constructLabels(fields);

			Label defaultLabel = new Label();
			mv.visitTableSwitchInsn(0, labels.length - 1, defaultLabel, labels);

			for (int i = 0, n = labels.length; i < n; i++) {
				Field field = fields[i];
				mv.visitLabel(labels[i]);
				mv.visitFrame(F_SAME, 0, null, 0, null);
				mv.visitVarInsn(ALOAD, 1);
				mv.visitTypeInsn(CHECKCAST, clazzNm);
				mv.visitFieldInsn(GETFIELD, clazzNm, field.getName(), typeNm);
				mv.visitInsn(instruction);
			}

			mv.visitLabel(defaultLabel);
			mv.visitFrame(F_SAME, 0, null, 0, null);
		} else {
			maxStack = 6;
		}
		enhanceForThrowingException(mv, IllegalArgumentException.class, "Field was not found", "Ljava/lang/Object;", ALOAD, 2);
		mv.visitMaxs(maxStack, 4);
		mv.visitEnd();
	}
 

private MethodVisitor createMethod(ClassVisitor cw) {
    MethodVisitor mv = cw.visitMethod(ACC_PUBLIC, "<init>", createMethodDescriptor(), null, null);
    generateAnnotations(mv);
    mv.visitCode();
    return mv;
}
 

private MethodVisitor declareMethod(Method method, ClassVisitor writer) {
	String name = method.getName();
	String descriptor = Type.getMethodDescriptor(method);
	return writer.visitMethod(ACC_PUBLIC, name, descriptor, null, null);
}
 

static void addLogError(ClassVisitor cw) {
  MethodVisitor mv;
  mv = cw.visitMethod(ACC_PUBLIC + ACC_STATIC + ACC_VARARGS, "$$error", "(Ljava/lang/String;[Ljava/lang/Object;)V",
      null, null);
  mv.visitCode();
  Label l0 = new Label();
  mv.visitLabel(l0);
  mv.visitLineNumber(433, l0);
  mv.visitFieldInsn(GETSTATIC, "java/lang/System", "err", "Ljava/io/PrintStream;");
  mv.visitLdcInsn("SessionAgent: [ERROR] %s");
  mv.visitInsn(ICONST_1);
  mv.visitTypeInsn(ANEWARRAY, "java/lang/Object");
  mv.visitInsn(DUP);
  mv.visitInsn(ICONST_0);
  mv.visitVarInsn(ALOAD, 0);
  mv.visitVarInsn(ALOAD, 1);
  mv.visitMethodInsn(INVOKESTATIC, "java/lang/String", "format",
      "(Ljava/lang/String;[Ljava/lang/Object;)Ljava/lang/String;", false);
  mv.visitInsn(AASTORE);
  mv.visitMethodInsn(INVOKESTATIC, "java/lang/String", "format",
      "(Ljava/lang/String;[Ljava/lang/Object;)Ljava/lang/String;", false);
  mv.visitMethodInsn(INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V", false);
  Label l1 = new Label();
  mv.visitLabel(l1);
  mv.visitLineNumber(434, l1);
  mv.visitVarInsn(ALOAD, 1);
  Label l2 = new Label();
  mv.visitJumpInsn(IFNULL, l2);
  mv.visitVarInsn(ALOAD, 1);
  mv.visitInsn(ARRAYLENGTH);
  mv.visitInsn(ICONST_1);
  mv.visitJumpInsn(IF_ICMPLE, l2);
  mv.visitVarInsn(ALOAD, 1);
  mv.visitVarInsn(ALOAD, 1);
  mv.visitInsn(ARRAYLENGTH);
  mv.visitInsn(ICONST_1);
  mv.visitInsn(ISUB);
  mv.visitInsn(AALOAD);
  mv.visitTypeInsn(INSTANCEOF, "java/lang/Throwable");
  mv.visitJumpInsn(IFEQ, l2);
  Label l3 = new Label();
  mv.visitLabel(l3);
  mv.visitLineNumber(435, l3);
  mv.visitVarInsn(ALOAD, 1);
  mv.visitVarInsn(ALOAD, 1);
  mv.visitInsn(ARRAYLENGTH);
  mv.visitInsn(ICONST_1);
  mv.visitInsn(ISUB);
  mv.visitInsn(AALOAD);
  mv.visitTypeInsn(CHECKCAST, "java/lang/Throwable");
  mv.visitFieldInsn(GETSTATIC, "java/lang/System", "err", "Ljava/io/PrintStream;");
  mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Throwable", "printStackTrace", "(Ljava/io/PrintStream;)V", false);
  mv.visitLabel(l2);
  mv.visitLineNumber(437, l2);
  mv.visitFrame(Opcodes.F_SAME, 0, null, 0, null);
  mv.visitInsn(RETURN);
  Label l4 = new Label();
  mv.visitLabel(l4);
  mv.visitLocalVariable("format", "Ljava/lang/String;", null, l0, l4, 0);
  mv.visitLocalVariable("args", "[Ljava/lang/Object;", null, l0, l4, 1);
  mv.visitMaxs(7, 2);
  mv.visitEnd();
}
 

public MethodVisitor visitMethod(ClassVisitor visitor, int access, String[] exceptions) {
    return visitor.visitMethod(access, s_name, s_desc, null, exceptions);
}
 

/**
 * 生成格式如下的代码，其中ServiceInit_xxx由注解生成器生成。
 * <pre>
 * package com.sankuai.waimai.router.generated;
 *
 * public class ServiceLoaderInit {
 *
 *     public static void init() {
 *         ServiceInit_xxx1.init();
 *         ServiceInit_xxx2.init();
 *     }
 * }
 * </pre>
 */
private void generateServiceInitClass(String directory, Set<String> classes) {

    if (classes.isEmpty()) {
        WMRouterLogger.info(GENERATE_INIT + "skipped, no service found");
        return;
    }

    try {
        WMRouterLogger.info(GENERATE_INIT + "start...");
        long ms = System.currentTimeMillis();

        ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_FRAMES | ClassWriter.COMPUTE_MAXS);
        ClassVisitor cv = new ClassVisitor(Opcodes.ASM5, writer) {
        };
        String className = Const.SERVICE_LOADER_INIT.replace('.', '/');
        cv.visit(50, Opcodes.ACC_PUBLIC, className, null, "java/lang/Object", null);

        MethodVisitor mv = cv.visitMethod(Opcodes.ACC_PUBLIC | Opcodes.ACC_STATIC,
                Const.INIT_METHOD, "()V", null, null);

        mv.visitCode();

        for (String clazz : classes) {
            mv.visitMethodInsn(Opcodes.INVOKESTATIC, clazz.replace('.', '/'),
                    "init",
                    "()V",
                    false);
        }
        mv.visitMaxs(0, 0);
        mv.visitInsn(Opcodes.RETURN);
        mv.visitEnd();
        cv.visitEnd();

        File dest = new File(directory, className + SdkConstants.DOT_CLASS);
        dest.getParentFile().mkdirs();
        new FileOutputStream(dest).write(writer.toByteArray());

        WMRouterLogger.info(GENERATE_INIT + "cost %s ms", System.currentTimeMillis() - ms);

    } catch (IOException e) {
        WMRouterLogger.fatal(e);
    }
}
 

/**
 * Generate the varargs <tt>set</tt> method body. The <tt>set</tt> method
 * performs a <tt>CHECKCAST</tt> on all incoming arguments, and also ensures
 * that primitive types are not assigned <tt>null</tt> by the consumer code.
 * 
 * @param ref Class ref being generated
 * @param desc Argument descriptor
 * @param args Parsed argument list from descriptor
 * @param writer Class writer
 */
private void generateMultiSetter(ArgsClassInfo info, ClassVisitor writer) {
    MethodVisitorEx set = new MethodVisitorEx(writer.visitMethod(Opcodes.ACC_PUBLIC,
            ArgsClassGenerator.SETALL, ArgsClassGenerator.SETALL_DESC, null, null));
    set.visitCode();
    
    Label lengthOk = new Label(), nullPrimitive = new Label();
    int maxStack = 6;
    
    // Compare the length of the varargs array to the expected argument count
    set.visitVarInsn(Opcodes.ALOAD, 1);
    set.visitInsn(Opcodes.ARRAYLENGTH);
    set.visitInsn(Opcodes.DUP);
    set.visitConstant((byte)info.args.length);
    
    // If the lengths are the same, proceed with assignment
    set.visitJumpInsn(Opcodes.IF_ICMPEQ, lengthOk);
    
    // Otherwise prepare and throw an ArgumentCountException
    set.visitTypeInsn(Opcodes.NEW, ArgsClassGenerator.ACE);
    set.visitInsn(Opcodes.DUP);
    set.visitInsn(Opcodes.DUP2_X1);
    set.visitInsn(Opcodes.POP2);
    set.visitConstant((byte)info.args.length);
    set.visitLdcInsn(info.getSignature());

    set.visitMethodInsn(Opcodes.INVOKESPECIAL, ArgsClassGenerator.ACE, Constants.CTOR, ArgsClassGenerator.ACE_CTOR_DESC, false);
    set.visitInsn(Opcodes.ATHROW);
    
    set.visitLabel(lengthOk);
    set.visitInsn(Opcodes.POP); // Pop the remaining length value
    
    // Put the values array on the stack to begin with
    set.visitVarInsn(Opcodes.ALOAD, 0);
    set.visitFieldInsn(Opcodes.GETFIELD, info.getName(), ArgsClassGenerator.VALUES_FIELD, ArgsClassGenerator.OBJECT_ARRAY);

    for (byte index = 0; index < info.args.length; index++) {
        // Dup the member array reference and target index
        set.visitInsn(Opcodes.DUP);
        set.visitConstant(index);
        
        // Read the value from the varargs array
        set.visitVarInsn(Opcodes.ALOAD, 1);
        set.visitConstant(index);
        set.visitInsn(Opcodes.AALOAD);
        
        // Check the argument type
        String boxingType = Bytecode.getBoxingType(info.args[index]);
        set.visitTypeInsn(Opcodes.CHECKCAST, boxingType != null ? boxingType : info.args[index].getInternalName());
        
        // For primitives, check the value is not null
        if (boxingType != null) {
            set.visitInsn(Opcodes.DUP);
            set.visitJumpInsn(Opcodes.IFNULL, nullPrimitive);
            maxStack = 7;
        }
 
        // Everything succeeded, assign the value
        set.visitInsn(Opcodes.AASTORE);
    }

    set.visitInsn(Opcodes.RETURN);
    
    set.visitLabel(nullPrimitive);
    ArgsClassGenerator.throwNPE(set, "Argument with primitive type cannot be set to NULL");
    set.visitInsn(Opcodes.RETURN);
    
    set.visitMaxs(maxStack, 2);
    set.visitEnd();
}