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 * 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.
 *
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 */
package runtime.valhalla.valuetypes;

import jdk.test.lib.Asserts;

import java.lang.reflect.Field;

/*
 * @test
 * @summary Test support for empty value types (no instance fields)
 * @library /test/lib
 * @compile -XDallowEmptyValues EmptyValueTest.java
 * @run main/othervm -XX:+EnableValhalla runtime.valhalla.valuetypes.EmptyValueTest
 
 */

public class EmptyValueTest {

    static inline class EmptyValue {
	public boolean isEmpty() {
	    return true;
	}
    }

    static inline class EmptyField {
	EmptyValue empty;

	EmptyField() {
	    this.empty = new EmptyValue();
	}
    }

    static class WithInt {
	int i;
    }
    
    static class WithEmptyField extends WithInt  {
	// With current layout strategy for reference classs, the empty
	// value field would be placed between the int and the Object
	// fields, along with some padding.
	Object o;
	EmptyValue empty;
    }
    
    public static void main(String[] args) {
	// Create an empty value
	EmptyValue empty = new EmptyValue();
	Asserts.assertTrue(empty.isEmpty());

	// Create a value with a empty value field
	EmptyField emptyField = new EmptyField();
	Asserts.assertEquals(emptyField.empty.getClass(), EmptyValue.class);
	Asserts.assertTrue(emptyField.empty.isEmpty());
	System.out.println(emptyField.empty.isEmpty());

	// Regular instance with an empty field inside
	WithEmptyField w = new WithEmptyField();
	Asserts.assertEquals(w.empty.getClass(), EmptyValue.class);
	Asserts.assertTrue(w.empty.isEmpty());
	w.empty = new EmptyValue();
	Asserts.assertEquals(w.empty.getClass(), EmptyValue.class);
	Asserts.assertTrue(w.empty.isEmpty());
	
	// Create an array of empty values
	EmptyValue[] emptyArray = new EmptyValue[100];
	for(EmptyValue element : emptyArray) {
	    Asserts.assertEquals(element.getClass(), EmptyValue.class);
	    Asserts.assertTrue(element.isEmpty());
	}

	// Testing arrayCopy
	EmptyValue[] array2 = new EmptyValue[100];
	// with two arrays
	System.arraycopy(emptyArray, 10, array2, 20, 50);
	for(EmptyValue element : array2) {
	    Asserts.assertEquals(element.getClass(), EmptyValue.class);
	    Asserts.assertTrue(element.isEmpty());
	}
	// single array, no overlap
	System.arraycopy(emptyArray, 10, emptyArray, 50, 20);
        for(EmptyValue element : emptyArray) {
	    Asserts.assertEquals(element.getClass(), EmptyValue.class);
	    Asserts.assertTrue(element.isEmpty());
	}
	// single array with overlap
	System.arraycopy(emptyArray, 10, emptyArray, 20, 50);
	for(EmptyValue element : emptyArray) {
	    Asserts.assertEquals(element.getClass(), EmptyValue.class);
	    Asserts.assertTrue(element.isEmpty());
	}
	
	// Passing an empty value in argument
	assert isEmpty(empty);

	// Returning an empty value
	assert getEmpty().isEmpty();

	// Checking fields with reflection
	Class<?> c = empty.getClass();
	try {
	    Field[] fields = c.getDeclaredFields();
	    Asserts.assertTrue(fields.length == 0);
	} catch (Throwable t) {
	    t.printStackTrace();
	    throw t;
	}
	WithEmptyField w0 = new WithEmptyField();
	Class<?> c2 = w0.getClass();
	try {
	    Field emptyfield = c2.getDeclaredField("empty");
	    EmptyValue e = (EmptyValue)emptyfield.get(w0);
	    Asserts.assertEquals(e.getClass(), EmptyValue.class);
	    Asserts.assertTrue(e.isEmpty());
	    emptyfield.set(w0, new EmptyValue());
	    e = (EmptyValue)emptyfield.get(w0);
	    Asserts.assertEquals(e.getClass(), EmptyValue.class);
	    Asserts.assertTrue(e.isEmpty());
	} catch(Throwable t) {
	    t.printStackTrace();
	    throw new RuntimeException("Reflection tests failed: " + t);
	}

	// Testing JIT compiler
	// for(int i=0; i < 100000; i++) {
	//     test();
	// }
    }

    static boolean isEmpty(EmptyValue empty) {
	return empty.isEmpty();
    }

    static EmptyValue getEmpty() {
	return new EmptyValue();
    }

    static void test() {
	for(int i=0; i < 10000; i++) {
	    Asserts.assertTrue(getEmpty().isEmpty());
	}
    }
}