/*

 * Copyright (c) 2018, 2018, 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 org.graalvm.compiler.nodes.extended;

import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_2;

import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_1;

import org.graalvm.compiler.core.common.type.Stamp;

import org.graalvm.compiler.graph.Node;

import org.graalvm.compiler.graph.NodeClass;

import org.graalvm.compiler.graph.spi.Canonicalizable;

import org.graalvm.compiler.graph.spi.CanonicalizerTool;

import org.graalvm.compiler.nodeinfo.NodeInfo;

import org.graalvm.compiler.nodes.ConstantNode;

import org.graalvm.compiler.nodes.FixedWithNextNode;

import org.graalvm.compiler.nodes.ValueNode;

import org.graalvm.compiler.nodes.spi.Lowerable;

import org.graalvm.compiler.nodes.spi.LoweringTool;

import org.graalvm.compiler.nodes.spi.StampProvider;

import jdk.vm.ci.meta.ConstantReflectionProvider;

import jdk.vm.ci.meta.MetaAccessProvider;

import jdk.vm.ci.meta.ResolvedJavaType;

/**

 * Loads the component hub for of the provided array hub.

 *

 * This is a fixed node because on certain VMs, for example the HotSpot VM, the read is only valid

 * when the provided hub is actually an array hub (and not, e.g., a primitive hub), so this node

 * must not float above a possible type check. Properly guarding this node would be possible too,

 * but it is unlikely that the guard would be more flexible than just fixing the node in the control

 * flow.

 */

@NodeInfo(cycles = CYCLES_2, size = SIZE_1)

public final class LoadArrayComponentHubNode extends FixedWithNextNode implements Lowerable, Canonicalizable.Unary<ValueNode> {

    public static final NodeClass<LoadArrayComponentHubNode> TYPE = NodeClass.create(LoadArrayComponentHubNode.class);

    private @Input ValueNode value;

    public static ValueNode create(ValueNode value, StampProvider stampProvider, MetaAccessProvider metaAccess, ConstantReflectionProvider constantReflection) {

        Stamp stamp = stampProvider.createHubStamp(null);

        return findSynonym(null, value, stamp, metaAccess, constantReflection);

    }

    protected LoadArrayComponentHubNode(Stamp stamp, ValueNode value) {

        super(TYPE, stamp);

        this.value = value;

    }

    @Override

    public ValueNode getValue() {

        return value;

    }

    @Override

    public void lower(LoweringTool tool) {

        tool.getLowerer().lower(this, tool);

    }

    @Override

    public Node canonical(CanonicalizerTool tool, ValueNode forValue) {

        return findSynonym(this, forValue, stamp, tool.getMetaAccess(), tool.getConstantReflection());

    }

    private static ValueNode findSynonym(LoadArrayComponentHubNode self, ValueNode forValue, Stamp stamp, MetaAccessProvider metaAccess, ConstantReflectionProvider constantReflection) {

        if (forValue.isConstant()) {

            ResolvedJavaType type = constantReflection.asJavaType(forValue.asConstant());

            if (type != null) {

                return ConstantNode.forConstant(stamp, constantReflection.asObjectHub(type.getComponentType()), metaAccess);

            }

        }

        return self != null ? self : new LoadArrayComponentHubNode(stamp, forValue);

    }

}