/*

 * Copyright (c) 2011, 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 org.graalvm.compiler.nodes.calc;

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

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

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

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

import org.graalvm.compiler.debug.GraalError;

import org.graalvm.compiler.graph.NodeClass;

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

import org.graalvm.compiler.nodeinfo.NodeInfo;

import org.graalvm.compiler.nodes.ConstantNode;

import org.graalvm.compiler.nodes.LogicConstantNode;

import org.graalvm.compiler.nodes.LogicNode;

import org.graalvm.compiler.nodes.NodeView;

import org.graalvm.compiler.nodes.ValueNode;

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

import org.graalvm.compiler.nodes.java.InstanceOfNode;

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

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

import org.graalvm.compiler.nodes.virtual.VirtualBoxingNode;

import org.graalvm.compiler.nodes.virtual.VirtualObjectNode;

import jdk.vm.ci.meta.Constant;

import jdk.vm.ci.meta.ConstantReflectionProvider;

import jdk.vm.ci.meta.JavaConstant;

import jdk.vm.ci.meta.JavaKind;

import jdk.vm.ci.meta.MetaAccessProvider;

import jdk.vm.ci.meta.ResolvedJavaType;

@NodeInfo(shortName = "==")

public final class ObjectEqualsNode extends PointerEqualsNode implements Virtualizable {

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

    private static final ObjectEqualsOp OP = new ObjectEqualsOp();

    public ObjectEqualsNode(ValueNode x, ValueNode y) {

        super(TYPE, x, y);

        assert x.stamp(NodeView.DEFAULT) instanceof AbstractObjectStamp;

        assert y.stamp(NodeView.DEFAULT) instanceof AbstractObjectStamp;

    }

    public static LogicNode create(ValueNode x, ValueNode y, ConstantReflectionProvider constantReflection, NodeView view) {

        if (result != null) {

            return result;

        } else {

            result = findSynonym(x, y, view);

            if (result != null) {

                return result;

            }

            return new ObjectEqualsNode(x, y);

        }

    }

    public static LogicNode create(ConstantReflectionProvider constantReflection, MetaAccessProvider metaAccess, OptionValues options, ValueNode x, ValueNode y, NodeView view) {

        if (result != null) {

            return result;

        }

        return create(x, y, constantReflection, view);

    }

    @Override

    public ValueNode canonical(CanonicalizerTool tool, ValueNode forX, ValueNode forY) {

        NodeView view = NodeView.from(tool);

        if (value != null) {

            return value;

        }

        return this;

    }

    public static class ObjectEqualsOp extends PointerEqualsOp {

        @Override

        protected LogicNode canonicalizeSymmetricConstant(ConstantReflectionProvider constantReflection, MetaAccessProvider metaAccess, OptionValues options, Integer smallestCompareWidth,

            ResolvedJavaType type = constantReflection.asJavaType(constant);

            if (type != null && nonConstant instanceof GetClassNode) {

                GetClassNode getClassNode = (GetClassNode) nonConstant;

                ValueNode object = getClassNode.getObject();

                assert ((ObjectStamp) object.stamp(view)).nonNull();

                if (!type.isPrimitive() && (type.isConcrete() || type.isArray())) {

                    return InstanceOfNode.create(TypeReference.createExactTrusted(type), object);

                }

                return LogicConstantNode.forBoolean(false);

            }

            return super.canonicalizeSymmetricConstant(constantReflection, metaAccess, options, smallestCompareWidth, condition, constant, nonConstant, mirrored, unorderedIsTrue, view);

        }

        @Override

        protected CompareNode duplicateModified(ValueNode newX, ValueNode newY, boolean unorderedIsTrue, NodeView view) {

            if (newX.stamp(view) instanceof ObjectStamp && newY.stamp(view) instanceof ObjectStamp) {

                return new ObjectEqualsNode(newX, newY);

            } else if (newX.stamp(view) instanceof AbstractPointerStamp && newY.stamp(view) instanceof AbstractPointerStamp) {

                return new PointerEqualsNode(newX, newY);

            }

            throw GraalError.shouldNotReachHere();

        }

    }

    private void virtualizeNonVirtualComparison(VirtualObjectNode virtual, ValueNode other, VirtualizerTool tool) {

        if (virtual instanceof VirtualBoxingNode && other.isConstant()) {

            VirtualBoxingNode virtualBoxingNode = (VirtualBoxingNode) virtual;

            if (virtualBoxingNode.getBoxingKind() == JavaKind.Boolean) {

                JavaConstant otherUnboxed = tool.getConstantReflectionProvider().unboxPrimitive(other.asJavaConstant());

                if (otherUnboxed != null && otherUnboxed.getJavaKind() == JavaKind.Boolean) {

                    int expectedValue = otherUnboxed.asBoolean() ? 1 : 0;

                    IntegerEqualsNode equals = new IntegerEqualsNode(virtualBoxingNode.getBoxedValue(tool), ConstantNode.forInt(expectedValue, graph()));

                    tool.addNode(equals);

                    tool.replaceWithValue(equals);

                } else {

                    tool.replaceWithValue(LogicConstantNode.contradiction(graph()));

                }

            }

        }

        if (virtual.hasIdentity()) {

            // one of them is virtual: they can never be the same objects

            tool.replaceWithValue(LogicConstantNode.contradiction(graph()));

        }

    }

    @Override

    public void virtualize(VirtualizerTool tool) {

        ValueNode xAlias = tool.getAlias(getX());

        ValueNode yAlias = tool.getAlias(getY());

        VirtualObjectNode xVirtual = xAlias instanceof VirtualObjectNode ? (VirtualObjectNode) xAlias : null;

        VirtualObjectNode yVirtual = yAlias instanceof VirtualObjectNode ? (VirtualObjectNode) yAlias : null;

        if (xVirtual != null && yVirtual == null) {

            virtualizeNonVirtualComparison(xVirtual, yAlias, tool);

        } else if (xVirtual == null && yVirtual != null) {

            virtualizeNonVirtualComparison(yVirtual, xAlias, tool);

        } else if (xVirtual != null && yVirtual != null) {

            if (xVirtual.hasIdentity() ^ yVirtual.hasIdentity()) {

                /*

                 * One of the two objects has identity, the other doesn't. In code, this looks like

                 * "Integer.valueOf(a) == new Integer(b)", which is always false.

                 *

                 * In other words: an object created via valueOf can never be equal to one created

                 * by new in the same compilation unit.

                 */

                tool.replaceWithValue(LogicConstantNode.contradiction(graph()));

            } else if (!xVirtual.hasIdentity() && !yVirtual.hasIdentity()) {

                ResolvedJavaType type = xVirtual.type();

                if (type.equals(yVirtual.type())) {

                    MetaAccessProvider metaAccess = tool.getMetaAccessProvider();

                    if (type.equals(metaAccess.lookupJavaType(Integer.class)) || type.equals(metaAccess.lookupJavaType(Long.class))) {

                        // both are virtual without identity: check contents

                        assert xVirtual.entryCount() == 1 && yVirtual.entryCount() == 1;

                        assert xVirtual.entryKind(0).getStackKind() == JavaKind.Int || xVirtual.entryKind(0) == JavaKind.Long;

                        IntegerEqualsNode equals = new IntegerEqualsNode(tool.getEntry(xVirtual, 0), tool.getEntry(yVirtual, 0));

                        tool.addNode(equals);

                        tool.replaceWithValue(equals);

                    }

                }

            } else {

                // both are virtual with identity: check if they refer to the same object

                tool.replaceWithValue(LogicConstantNode.forBoolean(xVirtual == yVirtual, graph()));

            }

        }

    }

}