Java Opcodes.H_INVOKESTATIC属性代码示例

@Override
public void visitInvokeDynamicInsn(String name, String desc, Handle bsm,
        Object... bsmArgs) {
    checkStartCode();
    checkEndCode();
    checkMethodIdentifier(version, name, "name");
    checkMethodDesc(desc);
    if (bsm.getTag() != Opcodes.H_INVOKESTATIC
            && bsm.getTag() != Opcodes.H_NEWINVOKESPECIAL) {
        throw new IllegalArgumentException("invalid handle tag "
                + bsm.getTag());
    }
    for (int i = 0; i < bsmArgs.length; i++) {
        checkLDCConstant(bsmArgs[i]);
    }
    super.visitInvokeDynamicInsn(name, desc, bsm, bsmArgs);
    ++insnCount;
}
 

/**
 * Appends the information about the given handle to {@link #buf buf}.
 *
 * @param h
 *            a handle, non null.
 */
protected void appendHandle(final Handle h) {
    int tag = h.getTag();
    buf.append("// handle kind 0x").append(Integer.toHexString(tag))
            .append(" : ");
    boolean isMethodHandle = false;
    switch (tag) {
    case Opcodes.H_GETFIELD:
        buf.append("GETFIELD");
        break;
    case Opcodes.H_GETSTATIC:
        buf.append("GETSTATIC");
        break;
    case Opcodes.H_PUTFIELD:
        buf.append("PUTFIELD");
        break;
    case Opcodes.H_PUTSTATIC:
        buf.append("PUTSTATIC");
        break;
    case Opcodes.H_INVOKEINTERFACE:
        buf.append("INVOKEINTERFACE");
        isMethodHandle = true;
        break;
    case Opcodes.H_INVOKESPECIAL:
        buf.append("INVOKESPECIAL");
        isMethodHandle = true;
        break;
    case Opcodes.H_INVOKESTATIC:
        buf.append("INVOKESTATIC");
        isMethodHandle = true;
        break;
    case Opcodes.H_INVOKEVIRTUAL:
        buf.append("INVOKEVIRTUAL");
        isMethodHandle = true;
        break;
    case Opcodes.H_NEWINVOKESPECIAL:
        buf.append("NEWINVOKESPECIAL");
        isMethodHandle = true;
        break;
    }
    buf.append('\n');
    buf.append(tab3);
    appendDescriptor(INTERNAL_NAME, h.getOwner());
    buf.append('.');
    buf.append(h.getName());
    if(!isMethodHandle){
        buf.append('(');
    }
    appendDescriptor(HANDLE_DESCRIPTOR, h.getDesc());
    if(!isMethodHandle){
        buf.append(')');
    }
}
 

@Override
public MethodVisitor visitMethod(final int access, final String name,
        final String desc, final String signature,
        final String[] exceptions) {
    /* a code generate looks like
     *  0: aload_0
     *  1: ldc           #125  // int 1
     *  3: ldc2_w        #126  // long 2l
     *  6: ldc           #128  // float 3.0f
     *  8: ldc2_w        #129  // double 4.0d
     * 11: ldc           #132  // String 5
     * 13: aload_0
     * 14: getfield      #135  // Field nativeCallee:Z
     * 17: ifeq          28
     * 20: invokedynamic #181,  0            // InvokeDynamic #1:calleeNative:(Lcompiler/calls/common/InvokeDynamic;IJFDLjava/lang/String;)Z
     * 25: goto          33
     * 28: invokedynamic #183,  0            // InvokeDynamic #1:callee:(Lcompiler/calls/common/InvokeDynamic;IJFDLjava/lang/String;)Z
     * 33: ldc           #185                // String Call insuccessfull
     * 35: invokestatic  #191                // Method jdk/test/lib/Asserts.assertTrue:(ZLjava/lang/String;)V
     * 38: return
     *
     * or, using java-like pseudo-code
     * if (this.nativeCallee == false) {
     *     invokedynamic-call-return-value = invokedynamic-of-callee
     * } else {
     *     invokedynamic-call-return-value = invokedynamic-of-nativeCallee
     * }
     * Asserts.assertTrue(invokedynamic-call-return-value, error-message);
     * return;
     */
    if (name.equals(CALLER_METHOD_NAME)) {
        MethodVisitor mv = cv.visitMethod(access, name, desc,
                signature, exceptions);
        Label nonNativeLabel = new Label();
        Label checkLabel = new Label();
        MethodType mtype = MethodType.methodType(CallSite.class,
                MethodHandles.Lookup.class, String.class, MethodType.class);
        Handle bootstrap = new Handle(Opcodes.H_INVOKESTATIC, CLASS,
                BOOTSTRAP_METHOD_NAME, mtype.toMethodDescriptorString());
        mv.visitCode();
        // push callee parameters onto stack
        mv.visitVarInsn(Opcodes.ALOAD, 0);//push "this"
        mv.visitLdcInsn(1);
        mv.visitLdcInsn(2L);
        mv.visitLdcInsn(3.0f);
        mv.visitLdcInsn(4.0d);
        mv.visitLdcInsn("5");
        // params loaded. let's decide what method to call
        mv.visitVarInsn(Opcodes.ALOAD, 0); // push "this"
        // get nativeCallee field
        mv.visitFieldInsn(Opcodes.GETFIELD, CLASS, CALL_NATIVE_FIELD,
                CALL_NATIVE_FIELD_DESC);
        // if nativeCallee == false goto nonNativeLabel
        mv.visitJumpInsn(Opcodes.IFEQ, nonNativeLabel);
        // invokedynamic nativeCalleeMethod using bootstrap method
        mv.visitInvokeDynamicInsn(NATIVE_CALLEE_METHOD_NAME,
                CALLEE_METHOD_DESC, bootstrap);
        // goto checkLabel
        mv.visitJumpInsn(Opcodes.GOTO, checkLabel);
        // label: nonNativeLabel
        mv.visitLabel(nonNativeLabel);
        // invokedynamic calleeMethod using bootstrap method
        mv.visitInvokeDynamicInsn(CALLEE_METHOD_NAME, CALLEE_METHOD_DESC,
                bootstrap);
        mv.visitLabel(checkLabel);
        mv.visitLdcInsn(CallsBase.CALL_ERR_MSG);
        mv.visitMethodInsn(Opcodes.INVOKESTATIC, ASSERTS_CLASS,
                ASSERTTRUE_METHOD_NAME, ASSERTTRUE_METHOD_DESC, false);
        // label: return
        mv.visitInsn(Opcodes.RETURN);
        mv.visitMaxs(0, 0);
        mv.visitEnd();
        return null;
    }
    return super.visitMethod(access, name, desc, signature, exceptions);
}