/*

 * Copyright (c) 2014, 2016, 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.hotspot.replacements;

import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_1;

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.hotspot.nodes.type.KlassPointerStamp;

import org.graalvm.compiler.hotspot.word.KlassPointer;

import org.graalvm.compiler.nodeinfo.NodeInfo;

import org.graalvm.compiler.nodes.ConstantNode;

import org.graalvm.compiler.nodes.NodeView;

import org.graalvm.compiler.nodes.PiNode;

import org.graalvm.compiler.nodes.ValueNode;

import org.graalvm.compiler.nodes.calc.ConvertNode;

import org.graalvm.compiler.nodes.calc.FloatingNode;

import org.graalvm.compiler.nodes.extended.GetClassNode;

import org.graalvm.compiler.nodes.extended.GuardingNode;

import org.graalvm.compiler.nodes.extended.LoadHubNode;

import org.graalvm.compiler.nodes.graphbuilderconf.GraphBuilderContext;

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

import org.graalvm.compiler.nodes.memory.address.AddressNode;

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

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

import org.graalvm.word.LocationIdentity;

import jdk.vm.ci.meta.Constant;

import jdk.vm.ci.meta.ConstantReflectionProvider;

import jdk.vm.ci.meta.JavaConstant;

import jdk.vm.ci.meta.MetaAccessProvider;

import jdk.vm.ci.meta.ResolvedJavaType;

/**

 * Read {@code Class::_klass} to get the hub for a {@link java.lang.Class}. This node mostly exists

 * to replace {@code _klass._java_mirror._klass} with {@code _klass}. The constant folding could be

 * handled by

 * {@link ReadNode#canonicalizeRead(ValueNode, AddressNode, LocationIdentity, CanonicalizerTool)}.

 */

@NodeInfo(cycles = CYCLES_1, size = SIZE_1)

public final class ClassGetHubNode extends FloatingNode implements Lowerable, Canonicalizable, ConvertNode {

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

    @Input protected ValueNode clazz;

    public ClassGetHubNode(ValueNode clazz) {

        super(TYPE, KlassPointerStamp.klass());

        this.clazz = clazz;

    }

    public static ValueNode create(ValueNode clazz, MetaAccessProvider metaAccess, ConstantReflectionProvider constantReflection, boolean allUsagesAvailable) {

        return canonical(null, metaAccess, constantReflection, allUsagesAvailable, KlassPointerStamp.klass(), clazz);

    }

    @SuppressWarnings("unused")

    public static boolean intrinsify(GraphBuilderContext b, ResolvedJavaMethod method, ValueNode clazz) {

        ValueNode clazzValue = create(clazz, b.getMetaAccess(), b.getConstantReflection(), false);

        b.push(JavaKind.Object, b.append(clazzValue));

        return true;

    }

    public static ValueNode canonical(ClassGetHubNode classGetHubNode, MetaAccessProvider metaAccess, ConstantReflectionProvider constantReflection, boolean allUsagesAvailable, Stamp stamp,

                    ValueNode clazz) {

        ClassGetHubNode self = classGetHubNode;

        if (allUsagesAvailable && self != null && self.hasNoUsages()) {

            return null;

        } else {

            if (clazz.isConstant()) {

                if (metaAccess != null) {

                    ResolvedJavaType exactType = constantReflection.asJavaType(clazz.asJavaConstant());

                    if (exactType.isPrimitive()) {

                        return ConstantNode.forConstant(stamp, JavaConstant.NULL_POINTER, metaAccess);

                    } else {

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

                    }

                }

            }

            if (clazz instanceof GetClassNode) {

                GetClassNode getClass = (GetClassNode) clazz;

                return new LoadHubNode(KlassPointerStamp.klassNonNull(), getClass.getObject());

            }

            if (clazz instanceof HubGetClassNode) {

                // Replace: _klass._java_mirror._klass -> _klass

                return ((HubGetClassNode) clazz).getHub();

            }

            if (self == null) {

                self = new ClassGetHubNode(clazz);

            }

            return self;

        }

    }

    @Override

    public Node canonical(CanonicalizerTool tool) {

        return canonical(this, tool.getMetaAccess(), tool.getConstantReflection(), tool.allUsagesAvailable(), stamp(NodeView.DEFAULT), clazz);

    }

    @Override

    public void lower(LoweringTool tool) {

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

    }

    @NodeIntrinsic

    public static native KlassPointer readClass(Class<?> clazzNonNull);

    @NodeIntrinsic(PiNode.class)

    public static native KlassPointer piCastNonNull(Object object, GuardingNode anchor);

    @Override

    public ValueNode getValue() {

        return clazz;

    }

    @Override

    public Constant convert(Constant c, ConstantReflectionProvider constantReflection) {

        ResolvedJavaType exactType = constantReflection.asJavaType(c);

        if (exactType.isPrimitive()) {

            return JavaConstant.NULL_POINTER;

        } else {

            return constantReflection.asObjectHub(exactType);

        }

    }

    @Override

    public Constant reverse(Constant c, ConstantReflectionProvider constantReflection) {

        assert !c.equals(JavaConstant.NULL_POINTER);

        ResolvedJavaType objectType = constantReflection.asJavaType(c);

        return constantReflection.asJavaClass(objectType);

    }

    @Override

    public boolean isLossless() {

        return false;

    }

    /**

     * There is more than one {@link java.lang.Class} value that has a NULL hub.

     */

    @Override

    public boolean mayNullCheckSkipConversion() {

        return false;

    }

    @Override

        ResolvedJavaType exactType = constantReflection.asJavaType(value);

        return !exactType.isPrimitive();

    }

}