/*
 * Copyright (c) 2012, 2015, 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 com.oracle.graal.nodes;

//JaCoCo Exclude

import jdk.internal.jvmci.meta.JavaKind;
import jdk.internal.jvmci.meta.ResolvedJavaType;

import com.oracle.graal.compiler.common.type.Stamp;
import com.oracle.graal.compiler.common.type.StampFactory;
import com.oracle.graal.graph.IterableNodeType;
import com.oracle.graal.graph.Node;
import com.oracle.graal.graph.NodeClass;
import com.oracle.graal.graph.spi.Canonicalizable;
import com.oracle.graal.graph.spi.CanonicalizerTool;
import com.oracle.graal.nodeinfo.NodeInfo;
import com.oracle.graal.nodes.extended.GuardingNode;
import com.oracle.graal.nodes.spi.LIRLowerable;
import com.oracle.graal.nodes.spi.NodeLIRBuilderTool;
import com.oracle.graal.nodes.spi.ValueProxy;
import com.oracle.graal.nodes.spi.Virtualizable;
import com.oracle.graal.nodes.spi.VirtualizerTool;
import com.oracle.graal.nodes.type.StampTool;
import com.oracle.graal.nodes.virtual.VirtualObjectNode;

/**
 * A node that changes the type of its input, usually narrowing it. For example, a {@link PiNode}
 * refines the type of a receiver during type-guarded inlining to be the type tested by the guard.
 *
 * In contrast to a {@link GuardedValueNode}, a {@link PiNode} is useless as soon as the type of its
 * input is as narrow or narrower than the {@link PiNode}'s type. The {@link PiNode}, and therefore
 * also the scheduling restriction enforced by the anchor, will go away.
 */
@NodeInfo
public class PiNode extends FloatingGuardedNode implements LIRLowerable, Virtualizable, IterableNodeType, Canonicalizable, ValueProxy {

    public static final NodeClass<PiNode> TYPE = NodeClass.create(PiNode.class);
    @Input ValueNode object;
    protected final Stamp piStamp;

    public ValueNode object() {
        return object;
    }

    protected PiNode(NodeClass<? extends PiNode> c, ValueNode object, Stamp stamp) {
        super(c, stamp, null);
        this.object = object;
        this.piStamp = stamp;
    }

    public PiNode(ValueNode object, Stamp stamp) {
        this(object, stamp, null);
    }

    public PiNode(ValueNode object, Stamp stamp, ValueNode anchor) {
        super(TYPE, stamp, (GuardingNode) anchor);
        this.object = object;
        this.piStamp = stamp;
    }

    public PiNode(ValueNode object, ResolvedJavaType toType, boolean exactType, boolean nonNull) {
        this(object, StampFactory.object(toType, exactType, nonNull || StampTool.isPointerNonNull(object.stamp()), true));
    }

    @Override
    public void generate(NodeLIRBuilderTool generator) {
        if (object.getStackKind() != JavaKind.Void && object.getStackKind() != JavaKind.Illegal) {
            generator.setResult(this, generator.operand(object));
        }
    }

    @Override
    public boolean inferStamp() {
        if (piStamp == StampFactory.forNodeIntrinsic()) {
            return false;
        }
        return updateStamp(piStamp.improveWith(object().stamp()));
    }

    @Override
    public void virtualize(VirtualizerTool tool) {
        ValueNode alias = tool.getAlias(object());
        if (alias instanceof VirtualObjectNode) {
            VirtualObjectNode virtual = (VirtualObjectNode) alias;
            if (StampTool.typeOrNull(this) != null && StampTool.typeOrNull(this).isAssignableFrom(virtual.type())) {
                tool.replaceWithVirtual(virtual);
            }
        }
    }

    @Override
    public Node canonical(CanonicalizerTool tool) {
        if (stamp() == StampFactory.forNodeIntrinsic()) {
            /* The actual stamp has not been set yet. */
            return this;
        }
        inferStamp();
        if (stamp().equals(object().stamp())) {
            return object();
        }
        if (getGuard() != null) {
            for (PiNode otherPi : getGuard().asNode().usages().filter(PiNode.class)) {
                if (object() == otherPi.object() && stamp().equals(otherPi.stamp())) {
                    /*
                     * Two PiNodes with the same guard and same result, so return the one with the
                     * more precise piStamp.
                     */
                    Stamp newStamp = piStamp.join(otherPi.piStamp);
                    if (newStamp.equals(otherPi.piStamp)) {
                        return otherPi;
                    }
                }
            }
        }
        return this;
    }

    @Override
    public ValueNode getOriginalNode() {
        return object;
    }

    /**
     * Casts an object to have an exact, non-null stamp representing {@link Class}.
     */
    public static Class<?> asNonNullClass(Object object) {
        return asNonNullClassIntrinsic(object, Class.class, true, true);
    }

    @NodeIntrinsic(PiNode.class)
    private static native Class<?> asNonNullClassIntrinsic(Object object, @ConstantNodeParameter Class<?> toType, @ConstantNodeParameter boolean exactType, @ConstantNodeParameter boolean nonNull);

    /**
     * Changes the stamp of an object.
     */
    @NodeIntrinsic
    public static native Object piCast(Object object, @ConstantNodeParameter Stamp stamp);

    /**
     * Changes the stamp of an object and ensures the newly stamped value does float above a given
     * anchor.
     */
    @NodeIntrinsic
    public static native Object piCast(Object object, @ConstantNodeParameter Stamp stamp, GuardingNode anchor);

    /**
     * Changes the stamp of an object to represent a given type and to indicate that the object is
     * not null.
     */
    public static Object piCastNonNull(Object object, @ConstantNodeParameter Class<?> toType) {
        return piCast(object, toType, false, true);
    }

    @NodeIntrinsic
    public static native Object piCast(Object object, @ConstantNodeParameter Class<?> toType, @ConstantNodeParameter boolean exactType, @ConstantNodeParameter boolean nonNull);
}