/*

 * Copyright (c) 2016, 2019, Oracle and/or its affiliates. All rights reserved.

 * 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.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package org.graalvm.compiler.core.test;

import java.lang.ref.Reference;

import java.lang.ref.ReferenceQueue;

import java.lang.ref.WeakReference;

import org.junit.Test;

import org.graalvm.compiler.graph.Node;

import org.graalvm.compiler.loop.LoopEx;

import org.graalvm.compiler.loop.LoopsData;

import org.graalvm.compiler.nodes.FieldLocationIdentity;

import org.graalvm.compiler.nodes.StructuredGraph;

import org.graalvm.compiler.nodes.memory.Access;

import jdk.internal.vm.compiler.word.LocationIdentity;

import jdk.vm.ci.meta.ResolvedJavaField;

public class ReferenceGetLoopTest extends GraalCompilerTest {

    @Override

    protected void checkMidTierGraph(StructuredGraph graph) {

        final LoopsData loops = new LoopsData(graph);

        boolean found = false;

        for (LoopEx loop : loops.loops()) {

            for (Node node : loop.inside().nodes()) {

                if (node instanceof Access) {

                    Access access = (Access) node;

                    LocationIdentity location = access.getLocationIdentity();

                    if (location instanceof FieldLocationIdentity) {

                        ResolvedJavaField field = ((FieldLocationIdentity) location).getField();

                        if (field.getName().equals("referent") && field.getDeclaringClass().equals(getMetaAccess().lookupJavaType(Reference.class))) {

                            found = true;

                        }

                    }

                }

            }

        }

        if (!found) {

            assertTrue(false, "Reference.referent not found in loop: " + getCanonicalGraphString(graph, true, false));

        }

    }

    public volatile Object referent;

    public final FinalWeakReference<Object> ref;

    public final ReferenceQueue<Object> refQueue;

    /*

     * Ensure that the Reference.get invoke is statically bindable.

     */

    public static final class FinalWeakReference<T> extends WeakReference<T> {

        public FinalWeakReference(T referent, ReferenceQueue<? super T> q) {

            super(referent, q);

        }

    }

    public ReferenceGetLoopTest() {

        referent = new Object();

        refQueue = new ReferenceQueue<>();

        ref = new FinalWeakReference<>(referent, refQueue);

    }

    @Test

    public void test() {

        getCode(getMetaAccess().lookupJavaMethod(getMethod("testSnippet")));

    }

    public void testSnippet() {

        while (ref.get() != null) {

            // burn!

        }

    }

}