/*

 * Copyright (c) 2018, 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package jdk.vm.ci.hotspot;

import static jdk.vm.ci.hotspot.HotSpotJVMCIRuntime.runtime;

import jdk.vm.ci.meta.JavaConstant;

final class IndirectHotSpotObjectConstantImpl extends HotSpotObjectConstantImpl {

    /**

     * An object handle in {@code JVMCI::_jvmci_handles}.

     */

    final long objectHandle;

    private int hashCode;

    final IndirectHotSpotObjectConstantImpl base;

    @VMEntryPoint

    private IndirectHotSpotObjectConstantImpl(long objectHandle, boolean compressed, boolean skipRegister) {

        super(compressed);

        assert objectHandle != 0 && UnsafeAccess.UNSAFE.getLong(objectHandle) != 0;

        this.objectHandle = objectHandle;

        this.base = null;

        if (!skipRegister) {

            HandleCleaner.create(this, objectHandle);

        }

    }

    private IndirectHotSpotObjectConstantImpl(IndirectHotSpotObjectConstantImpl base, boolean compressed) {

        super(compressed);

        // This is a variant of an original object that only varies in compress vs uncompressed.

        // Instead of creating a new handle, reference that object and objectHandle.

        this.objectHandle = base.objectHandle;

        // There should only be on level of indirection to the base object.

        assert base.base == null || base.base.base == null;

        this.base = base.base != null ? base.base : base;

    }

    @Override

    public JavaConstant compress() {

        assert !compressed;

        return new IndirectHotSpotObjectConstantImpl(this, true);

    }

    @Override

    public JavaConstant uncompress() {

        assert compressed;

        return new IndirectHotSpotObjectConstantImpl(this, false);

    }

    @Override

    public int getIdentityHashCode() {

        int hash = hashCode;

        if (hash == 0) {

            hash = runtime().compilerToVm.getIdentityHashCode(this);

            if (hash == 0) {

                hash = 31;

            }

            hashCode = hash;

        }

        return hash;

    }

}