Java MethodVisitor.visitCode方法代码示例

import jdk.internal.org.objectweb.asm.MethodVisitor; //导入方法依赖的package包/类
private void emitStaticInitializer() {
    final String className = scriptClassInfo.getJavaName();
    if (! staticInitFound) {
        // no user written <clinit> and so create one
        final MethodVisitor mv = ClassGenerator.makeStaticInitializer(this);
        mv.visitCode();
        mv.visitInsn(RETURN);
        mv.visitMaxs(Short.MAX_VALUE, 0);
        mv.visitEnd();
    }
    // Now generate $clinit$
    final MethodGenerator mi = ClassGenerator.makeStaticInitializer(this, $CLINIT$);
    ClassGenerator.emitStaticInitPrefix(mi, className, memberCount);
    if (memberCount > 0) {
        for (final MemberInfo memInfo : scriptClassInfo.getMembers()) {
            if (memInfo.isInstanceProperty() || memInfo.isInstanceFunction()) {
                ClassGenerator.linkerAddGetterSetter(mi, className, memInfo);
            } else if (memInfo.isInstanceGetter()) {
                final MemberInfo setter = scriptClassInfo.findSetter(memInfo);
                ClassGenerator.linkerAddGetterSetter(mi, className, memInfo, setter);
            }
        }
    }
    ClassGenerator.emitStaticInitSuffix(mi, className);
}
 

import jdk.internal.org.objectweb.asm.MethodVisitor; //导入方法依赖的package包/类
public static byte[] dumpT2() {
    ClassWriter cw = new ClassWriter(0);
    MethodVisitor mv;

    cw.visit(52, ACC_PUBLIC | ACC_SUPER, "p1/T2", null, "p1/T1", null);
    {
        mv = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
        mv.visitCode();
        mv.visitVarInsn(ALOAD, 0);
        mv.visitMethodInsn(INVOKESPECIAL, "p1/T1", "<init>", "()V", false);
        mv.visitInsn(RETURN);
        mv.visitMaxs(1, 1);
        mv.visitEnd();
    }
    {
        mv = cw.visitMethod(ACC_PUBLIC + ACC_ABSTRACT, "m", "()I", null, null);
        mv.visitEnd();
    }
    cw.visitEnd();

    return cw.toByteArray();
}
 

import jdk.internal.org.objectweb.asm.MethodVisitor; //导入方法依赖的package包/类
private Handle generateBootstrapMethod(Handle h) {
    String bootstrapName = "bootstrapMethod";
    MethodType bootstrapType = MethodType.methodType(CallSite.class, MethodHandles.Lookup.class, String.class, MethodType.class);

    MethodVisitor bmv = cv.visitMethod(ACC_PUBLIC | ACC_STATIC, bootstrapName, bootstrapType.toMethodDescriptorString(), null, null);
    bmv.visitCode();

    String constCallSite = "java/lang/invoke/ConstantCallSite";
    bmv.visitTypeInsn(NEW, constCallSite);
    bmv.visitInsn(DUP);

    bmv.visitLdcInsn(h);

    bmv.visitMethodInsn(INVOKESPECIAL, constCallSite, "<init>", "(Ljava/lang/invoke/MethodHandle;)V", false);
    bmv.visitInsn(ARETURN);

    bmv.visitMaxs(0,0);
    bmv.visitEnd();

    return new Handle(H_INVOKESTATIC, ownerClassName, bootstrapName, bootstrapType.toMethodDescriptorString());
}
 

import jdk.internal.org.objectweb.asm.MethodVisitor; //导入方法依赖的package包/类
public static void writeClassFile() throws Exception {
    ClassWriter cw = new ClassWriter(0);
    MethodVisitor mv;

    cw.visit(99, ACC_PUBLIC + ACC_SUPER, "ClassFile", null, "java/lang/Object", null);
    mv = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
    mv.visitCode();
    mv.visitVarInsn(ALOAD, 0);
    mv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "<init>", "()V", false);
    mv.visitInsn(RETURN);
    mv.visitMaxs(1, 1);
    mv.visitEnd();
    cw.visitEnd();

    try (FileOutputStream fos = new FileOutputStream(new File("ClassFile.class"))) {
         fos.write(cw.toByteArray());
    }
}
 

import jdk.internal.org.objectweb.asm.MethodVisitor; //导入方法依赖的package包/类
public static byte[] dumpT1() {
    ClassWriter cw = new ClassWriter(0);
    MethodVisitor mv;

    cw.visit(52, ACC_PUBLIC | ACC_SUPER, "p1/T1", null, "java/lang/Object", null);
    {
        mv = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
        mv.visitCode();
        mv.visitVarInsn(ALOAD, 0);
        mv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "<init>", "()V", false);
        mv.visitInsn(RETURN);
        mv.visitMaxs(1, 1);
        mv.visitEnd();
    }
    {
        mv = cw.visitMethod(ACC_PUBLIC, "m", "()I", null, null);
        mv.visitCode();
        mv.visitFieldInsn(GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;");
        mv.visitLdcInsn("p1/T1.m()");
        mv.visitMethodInsn(INVOKEVIRTUAL, "java/io/PrintStream", "print", "(Ljava/lang/String;)V", false);
        mv.visitIntInsn(BIPUSH, 3);
        mv.visitInsn(IRETURN);
        mv.visitMaxs(2, 1);
        mv.visitEnd();
    }
    cw.visitEnd();

    return cw.toByteArray();
}
 

import jdk.internal.org.objectweb.asm.MethodVisitor; //导入方法依赖的package包/类
/**
 * Generate bytecode for moduleHashes method
 */
private void genModuleHashesMethod(ClassWriter cw) {
    MethodVisitor hmv =
        cw.visitMethod(ACC_PUBLIC,
                       "moduleHashes",
                       "()" + MODULE_HASHES_ARRAY_SIGNATURE,
                       "()" + MODULE_HASHES_ARRAY_SIGNATURE,
                       null);
    hmv.visitCode();
    pushInt(hmv, moduleInfos.size());
    hmv.visitTypeInsn(ANEWARRAY, "jdk/internal/module/ModuleHashes");
    hmv.visitVarInsn(ASTORE, MH_VAR);

    for (int index = 0; index < moduleInfos.size(); index++) {
        ModuleInfo minfo = moduleInfos.get(index);
        if (minfo.recordedHashes() != null) {
            new ModuleHashesBuilder(minfo.recordedHashes(),
                                    index,
                                    hmv).build();
        }
    }

    hmv.visitVarInsn(ALOAD, MH_VAR);
    hmv.visitInsn(ARETURN);
    hmv.visitMaxs(0, 0);
    hmv.visitEnd();
}
 

import jdk.internal.org.objectweb.asm.MethodVisitor; //导入方法依赖的package包/类
private static void generateTestMethod(ClassVisitor cv,
        Label unstableIfLocation) {
    MethodVisitor mv = cv.visitMethod(ACC_PUBLIC | ACC_STATIC, METHOD_NAME,
            "(Z)V", null, null);
    mv.visitCode();

    Label end = new Label();
    Label falseBranch = new Label();

    // push "field" field's value and 1 to stack
    mv.visitFieldInsn(GETSTATIC, CLASS_NAME, FIELD_NAME, "I");
    mv.visitInsn(ICONST_1);
    // load argument's value
    mv.visitVarInsn(ILOAD, 0); // alwaysTrue
    // here is our unstable if
    mv.visitLabel(unstableIfLocation);
    mv.visitJumpInsn(IFEQ, falseBranch);
    // increment on "true"
    mv.visitInsn(IADD);
    mv.visitJumpInsn(GOTO, end);
    // decrement on "false"
    mv.visitLabel(falseBranch);
    mv.visitInsn(ISUB);
    mv.visitLabel(end);
    // bye bye
    mv.visitInsn(RETURN);

    mv.visitMaxs(0, 0);
    mv.visitEnd();
}
 

import jdk.internal.org.objectweb.asm.MethodVisitor; //导入方法依赖的package包/类
void defineIndyBootstrapMethodClass(ClassWriter cw) {
    cw.visit(52, ACC_SUPER | ACC_PUBLIC,
             BOOTSTRAP_METHOD_CLASS_NAME, null, "java/lang/Object", null);
    // Bootstrap method is declared to be private
    MethodVisitor mv = cw.visitMethod(ACC_PRIVATE | ACC_STATIC,
                                      BOOTSTRAP_METHOD_NAME, BOOTSTRAP_METHOD_DESC, null, null);
    mv.visitCode();
    defineIndyBootstrapMethodBody(mv);
    mv.visitMaxs(0, 0);
    mv.visitEnd();
}
 

import jdk.internal.org.objectweb.asm.MethodVisitor; //导入方法依赖的package包/类
/** Produces byte code for a class that is used as an injected invoker. */
private static byte[] generateInvokerTemplate() {
    ClassWriter cw = new ClassWriter(0);

    // private static class InjectedInvoker {
    //     @Hidden
    //     static Object invoke_V(MethodHandle vamh, Object[] args) throws Throwable {
    //        return vamh.invokeExact(args);
    //     }
    // }
    cw.visit(52, ACC_PRIVATE | ACC_SUPER, "InjectedInvoker", null, "java/lang/Object", null);

    MethodVisitor mv = cw.visitMethod(ACC_STATIC, "invoke_V",
                  "(Ljava/lang/invoke/MethodHandle;[Ljava/lang/Object;)Ljava/lang/Object;",
                  null, null);

    // Suppress invoker method in stack traces.
    AnnotationVisitor av0 = mv.visitAnnotation("Ljava/lang/invoke/LambdaForm$Hidden;", true);
    av0.visitEnd();

    mv.visitCode();
    mv.visitVarInsn(ALOAD, 0);
    mv.visitVarInsn(ALOAD, 1);
    mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/invoke/MethodHandle", "invokeExact",
                       "([Ljava/lang/Object;)Ljava/lang/Object;", false);
    mv.visitInsn(ARETURN);
    mv.visitMaxs(2, 2);
    mv.visitEnd();

    cw.visitEnd();
    return cw.toByteArray();
}
 

import jdk.internal.org.objectweb.asm.MethodVisitor; //导入方法依赖的package包/类
public static void writeClassFile(int cfv) throws Exception {
    ClassWriter cw = new ClassWriter(0);
    MethodVisitor mv;

    cw.visit(cfv, ACC_PUBLIC + ACC_SUPER, "ClassFile", null, "java/lang/Object", null);
    mv = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
    mv.visitCode();
    mv.visitVarInsn(ALOAD, 0);
    mv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "<init>", "()V", false);
    mv.visitInsn(RETURN);
    mv.visitMaxs(1, 1);
    mv.visitEnd();

    mv = cw.visitMethod(ACC_PUBLIC + ACC_STATIC, "main", "([Ljava/lang/String;)V", null, null);
    mv.visitCode();
    mv.visitInsn(ICONST_1);
    mv.visitInsn(ICONST_2);
    mv.visitMultiANewArrayInsn("[I", 2);
    mv.visitVarInsn(ASTORE, 1);
    mv.visitInsn(RETURN);
    mv.visitMaxs(2, 2);
    mv.visitEnd();

    cw.visitEnd();

    try (FileOutputStream fos = new FileOutputStream(new File("ClassFile.class"))) {
         fos.write(cw.toByteArray());
    }
}
 

import jdk.internal.org.objectweb.asm.MethodVisitor; //导入方法依赖的package包/类
private static byte[] loadC(boolean redefine) {
    ClassWriter cw = new ClassWriter(0);

    cw.visit(52, ACC_SUPER | ACC_PUBLIC, "C", null, "java/lang/Object", null);
    {
        MethodVisitor mv;

        mv = cw.visitMethod(ACC_PUBLIC | ACC_STATIC, "m", "()V", null, null);
        mv.visitCode();

        // First time we run we will:
        // 1) Cache resolution errors
        // 2) Redefine the class / method
        // 3) Try to read the resolution errors that were cached
        //
        // The redefined method will never run, throw error to be sure
        if (redefine) {
            createThrowRuntimeExceptionCode(mv, "The redefined method was called");
        } else {
            createMethodBody(mv);
        }
        mv.visitMaxs(3, 0);
        mv.visitEnd();
    }
    cw.visitEnd();
    return cw.toByteArray();
}
 

import jdk.internal.org.objectweb.asm.MethodVisitor; //导入方法依赖的package包/类
public static byte[] dumpP1A() {

        ClassWriter cw = new ClassWriter(0);
        MethodVisitor mv;

        cw.visit(V1_7, ACC_PUBLIC + ACC_SUPER, "P1/A", null, "java/lang/Object", null);

        {
            mv = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
            mv.visitCode();
            mv.visitVarInsn(ALOAD, 0);
            mv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "<init>", "()V", false);
            mv.visitInsn(RETURN);
            mv.visitMaxs(1, 1);
            mv.visitEnd();
        }
        {
            mv = cw.visitMethod(ACC_PUBLIC, "m", "()I", null, null);
            mv.visitCode();
            mv.visitFieldInsn(GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;");
            mv.visitLdcInsn("A.m");
            mv.visitMethodInsn(INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V", false);
            mv.visitIntInsn(BIPUSH, 1);
            mv.visitInsn(IRETURN);
            mv.visitMaxs(2, 1);
            mv.visitEnd();
        }
        cw.visitEnd();

        return cw.toByteArray();
    }
 

import jdk.internal.org.objectweb.asm.MethodVisitor; //导入方法依赖的package包/类
public static byte[] dumpP1B() {

        ClassWriter cw = new ClassWriter(0);
        MethodVisitor mv;

        cw.visit(V1_8, ACC_PUBLIC + ACC_SUPER, "P1/B", null, "P1/A", null);

        {
            mv = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
            mv.visitCode();
            mv.visitVarInsn(ALOAD, 0);
            mv.visitMethodInsn(INVOKESPECIAL, "P1/A", "<init>", "()V", false);
            mv.visitInsn(RETURN);
            mv.visitMaxs(1, 1);
            mv.visitEnd();
        }
        {
            mv = cw.visitMethod(0, "m", "()I", null, null);
            mv.visitCode();
            mv.visitFieldInsn(GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;");
            mv.visitLdcInsn("B.m");
            mv.visitMethodInsn(INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V", false);
            mv.visitIntInsn(BIPUSH, 2);
            mv.visitInsn(IRETURN);
            mv.visitMaxs(2, 1);
            mv.visitEnd();
        }
        cw.visitEnd();

        return cw.toByteArray();
    }
 

import jdk.internal.org.objectweb.asm.MethodVisitor; //导入方法依赖的package包/类
private static void generateConstructor(ClassWriter classWriter) {
    MethodVisitor mv = classWriter.visitMethod(ACC_PUBLIC, "<init>", "()V",
            null, null);

    mv.visitCode();

    mv.visitVarInsn(ALOAD, 0);
    mv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "<init>", "()V",
            false);
    mv.visitInsn(RETURN);

    mv.visitMaxs(0, 0);
    mv.visitEnd();
}
 

import jdk.internal.org.objectweb.asm.MethodVisitor; //导入方法依赖的package包/类
private byte[] loadClassData(String name) throws Exception {
    ClassWriter cw = new ClassWriter(0);
    MethodVisitor mv;
    switch (name) {
        case INTERFACE_NAME:
            cw.visit(V1_8, ACC_ABSTRACT | ACC_INTERFACE | ACC_PUBLIC, INTERFACE_NAME, null, "java/lang/Object", null);
            {
                mv = cw.visitMethod(ACC_PRIVATE, "privInstance", "()I", null, null);
                mv.visitCode();
                mv.visitLdcInsn(EXPECTED);
                mv.visitInsn(IRETURN);
                mv.visitMaxs(1, 1);
                mv.visitEnd();
            }
            break;
        case CLASS_NAME:
            cw.visit(52, ACC_SUPER | ACC_PUBLIC, CLASS_NAME, null, "java/lang/Object", new String[]{INTERFACE_NAME});
            {
                mv = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
                mv.visitCode();
                mv.visitVarInsn(ALOAD, 0);
                mv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "<init>", "()V");
                mv.visitInsn(RETURN);
                mv.visitMaxs(1, 1);
                mv.visitEnd();
            }
            break;
        default:
            break;
    }
    cw.visitEnd();

    return cw.toByteArray();
}