import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;
import java.lang.StackWalker.StackFrame;

public class LocalLongHelper {
    static StackWalker sw;
    static Method intValue;
    static Method getLocals;
    static Class<?> primitiveValueClass;
    static Method primitiveType;
    static Method getMethodType;
    static Field memberName;
    static Field offset;
    
    public static void main(String[] args) throws Throwable {
        setupReflectionStatics();
        new LocalLongHelper().longArg(0xC0FFEE, 0x1234567890ABCDEFL);
    }

    /*
     * The first 4 local slots should be:
     * 0: this
     * 1: int "i"
     * 2: long "l", first slot
     * 3: long "l", second slot
     */
    public long longArg(int i, long l) throws Throwable {        
        List<StackFrame> frames = sw.walk(s -> s.collect(Collectors.toList()));
        Object[] locals = (Object[]) getLocals.invoke(frames.get(0));
                
        int locals_1 = (int) intValue.invoke(locals[1]); // java.lang.LiveStackFrame$PrimitiveValue.intValue()
        int locals_2 = (int) intValue.invoke(locals[2]);
        int locals_3 = (int) intValue.invoke(locals[3]);
        if (locals_2 != 0){
            throw new RuntimeException("Expected locals_2 == 0");
        }
        return l; // Don't want l to become a dead var
    }
    
    private static void setupReflectionStatics() throws Throwable {
        Class<?> liveStackFrameClass = Class.forName("java.lang.LiveStackFrame");
        primitiveValueClass = Class.forName("java.lang.LiveStackFrame$PrimitiveValue");

        getLocals = liveStackFrameClass.getDeclaredMethod("getLocals");
        getLocals.setAccessible(true);

        intValue = primitiveValueClass.getDeclaredMethod("intValue");
        intValue.setAccessible(true);

        Class<?> stackFrameInfoClass = Class.forName("java.lang.StackFrameInfo");
        memberName = stackFrameInfoClass.getDeclaredField("memberName");
        memberName.setAccessible(true);
        offset = stackFrameInfoClass.getDeclaredField("bci");
        offset.setAccessible(true);
        getMethodType = Class.forName("java.lang.invoke.MemberName").getDeclaredMethod("getMethodType");
        getMethodType.setAccessible(true);
        
        Class<?> extendedOptionClass = Class.forName("java.lang.StackWalker$ExtendedOption");
        Method ewsNI = StackWalker.class.getDeclaredMethod("newInstance", Set.class, extendedOptionClass);
        ewsNI.setAccessible(true);
        Field f = extendedOptionClass.getDeclaredField("LOCALS_AND_OPERANDS");
        f.setAccessible(true);
        Object localsAndOperandsOption = f.get(null);        
        
        primitiveType = primitiveValueClass.getDeclaredMethod("type");
        primitiveType.setAccessible(true);        
        
        sw = (StackWalker) ewsNI.invoke(null, java.util.Collections.emptySet(), localsAndOperandsOption);        
    }

    private static String type(Object o) throws Throwable {
        if (primitiveValueClass.isInstance(o)) {
            final char c = (char) primitiveType.invoke(o);
            return String.valueOf(c);
        } else if (o != null) {
            return o.getClass().getName();
        } else {
            return "null";
        }
    }
}