/*

 * Copyright (c) 2013, 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 org.graalvm.compiler.replacements.nodes;

import static org.graalvm.compiler.core.common.GraalOptions.UseGraalStubs;

import static org.graalvm.compiler.nodeinfo.InputType.Memory;

import org.graalvm.compiler.core.common.spi.ForeignCallLinkage;

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

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.NodeCycles;

import org.graalvm.compiler.nodeinfo.NodeInfo;

import org.graalvm.compiler.nodeinfo.NodeSize;

import org.graalvm.compiler.nodes.ConstantNode;

import org.graalvm.compiler.nodes.FixedWithNextNode;

import org.graalvm.compiler.nodes.NamedLocationIdentity;

import org.graalvm.compiler.nodes.NodeView;

import org.graalvm.compiler.nodes.ValueNode;

import org.graalvm.compiler.nodes.ValueNodeUtil;

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

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

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

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

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

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

import org.graalvm.compiler.nodes.util.GraphUtil;

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

import jdk.internal.vm.compiler.word.LocationIdentity;

import jdk.vm.ci.meta.ConstantReflectionProvider;

import jdk.vm.ci.meta.JavaConstant;

import jdk.vm.ci.meta.JavaKind;

import jdk.vm.ci.meta.Value;

// JaCoCo Exclude

/**

 * Compares two arrays with the same length.

 */

@NodeInfo(cycles = NodeCycles.CYCLES_UNKNOWN, size = NodeSize.SIZE_128)

public final class ArrayEqualsNode extends FixedWithNextNode implements LIRLowerable, Canonicalizable, Virtualizable, MemoryAccess {

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

    /** {@link JavaKind} of the arrays to compare. */

    protected final JavaKind kind;

    /** One array to be tested for equality. */

    @Input ValueNode array1;

    /** The other array to be tested for equality. */

    @Input ValueNode array2;

    /** Length of both arrays. */

    @Input ValueNode length;

    @OptionalInput(Memory) MemoryNode lastLocationAccess;

    public ArrayEqualsNode(ValueNode array1, ValueNode array2, ValueNode length, @ConstantNodeParameter JavaKind kind) {

        super(TYPE, StampFactory.forKind(JavaKind.Boolean));

        this.kind = kind;

        this.array1 = array1;

        this.array2 = array2;

        this.length = length;

    }

    private static boolean isNaNFloat(JavaConstant constant) {

        JavaKind kind = constant.getJavaKind();

        return (kind == JavaKind.Float && Float.isNaN(constant.asFloat())) || (kind == JavaKind.Double && Double.isNaN(constant.asDouble()));

    }

    private static boolean arrayEquals(ConstantReflectionProvider constantReflection, JavaConstant a, JavaConstant b, int len) {

        for (int i = 0; i < len; i++) {

            JavaConstant aElem = constantReflection.readArrayElement(a, i);

            JavaConstant bElem = constantReflection.readArrayElement(b, i);

            if (!constantReflection.constantEquals(aElem, bElem) && !(isNaNFloat(aElem) && isNaNFloat(bElem))) {

                return false;

            }

        }

        return true;

    }

    @Override

    public Node canonical(CanonicalizerTool tool) {

        if (tool.allUsagesAvailable() && hasNoUsages()) {

            return null;

        }

        ValueNode a1 = GraphUtil.unproxify(array1);

        ValueNode a2 = GraphUtil.unproxify(array2);

        if (a1 == a2) {

            return ConstantNode.forBoolean(true);

        }

        if (a1.isConstant() && a2.isConstant() && length.isConstant()) {

            ConstantNode c1 = (ConstantNode) a1;

            ConstantNode c2 = (ConstantNode) a2;

            if (c1.getStableDimension() >= 1 && c2.getStableDimension() >= 1) {

                boolean ret = arrayEquals(tool.getConstantReflection(), c1.asJavaConstant(), c2.asJavaConstant(), length.asJavaConstant().asInt());

                return ConstantNode.forBoolean(ret);

            }

        }

        return this;

    }

    @Override

    public void virtualize(VirtualizerTool tool) {

        ValueNode alias1 = tool.getAlias(array1);

        ValueNode alias2 = tool.getAlias(array2);

        if (alias1 == alias2) {

            // the same virtual objects will always have the same contents

            tool.replaceWithValue(ConstantNode.forBoolean(true, graph()));

        } else if (alias1 instanceof VirtualObjectNode && alias2 instanceof VirtualObjectNode) {

            VirtualObjectNode virtual1 = (VirtualObjectNode) alias1;

            VirtualObjectNode virtual2 = (VirtualObjectNode) alias2;

            if (virtual1.entryCount() == virtual2.entryCount()) {

                int entryCount = virtual1.entryCount();

                boolean allEqual = true;

                for (int i = 0; i < entryCount; i++) {

                    ValueNode entry1 = tool.getEntry(virtual1, i);

                    ValueNode entry2 = tool.getEntry(virtual2, i);

                    if (entry1 != entry2) {

                        if (entry1 instanceof ConstantNode && entry2 instanceof ConstantNode) {

                            // Float NaN constants are different constant nodes but treated as

                            // equal in Arrays.equals([F[F) or Arrays.equals([D[D).

                            if (entry1.getStackKind() == JavaKind.Float && entry2.getStackKind() == JavaKind.Float) {

                                float value1 = ((JavaConstant) entry1.asConstant()).asFloat();

                                float value2 = ((JavaConstant) entry2.asConstant()).asFloat();

                                if (Float.floatToIntBits(value1) != Float.floatToIntBits(value2)) {

                                    allEqual = false;

                                }

                            } else if (entry1.getStackKind() == JavaKind.Double && entry2.getStackKind() == JavaKind.Double) {

                                double value1 = ((JavaConstant) entry1.asConstant()).asDouble();

                                double value2 = ((JavaConstant) entry2.asConstant()).asDouble();

                                if (Double.doubleToLongBits(value1) != Double.doubleToLongBits(value2)) {

                                    allEqual = false;

                                }

                            } else {

                                allEqual = false;

                            }

                        } else {

                            // the contents might be different

                            allEqual = false;

                        }

                    }

                    if (entry1.stamp(NodeView.DEFAULT).alwaysDistinct(entry2.stamp(NodeView.DEFAULT))) {

                        // the contents are different

                        tool.replaceWithValue(ConstantNode.forBoolean(false, graph()));

                        return;

                    }

                }

                if (allEqual) {

                    tool.replaceWithValue(ConstantNode.forBoolean(true, graph()));

                }

            }

        }

    }

    @NodeIntrinsic

    public static native boolean equals(Object array1, Object array2, int length, @ConstantNodeParameter JavaKind kind);

    public static boolean equals(boolean[] array1, boolean[] array2, int length) {

        return equals(array1, array2, length, JavaKind.Boolean);

    }

    public static boolean equals(byte[] array1, byte[] array2, int length) {

        return equals(array1, array2, length, JavaKind.Byte);

    }

    public static boolean equals(char[] array1, char[] array2, int length) {

        return equals(array1, array2, length, JavaKind.Char);

    }

    public static boolean equals(short[] array1, short[] array2, int length) {

        return equals(array1, array2, length, JavaKind.Short);

    }

    public static boolean equals(int[] array1, int[] array2, int length) {

        return equals(array1, array2, length, JavaKind.Int);

    }

    public static boolean equals(long[] array1, long[] array2, int length) {

        return equals(array1, array2, length, JavaKind.Long);

    }

    public static boolean equals(float[] array1, float[] array2, int length) {

        return equals(array1, array2, length, JavaKind.Float);

    }

    public static boolean equals(double[] array1, double[] array2, int length) {

        return equals(array1, array2, length, JavaKind.Double);

    }

    public ValueNode getLength() {

        return length;

    }

    public JavaKind getKind() {

        return kind;

    }

    @Override

    public void generate(NodeLIRBuilderTool gen) {

        if (UseGraalStubs.getValue(graph().getOptions())) {

            ForeignCallLinkage linkage = gen.lookupGraalStub(this);

            if (linkage != null) {

                Value result = gen.getLIRGeneratorTool().emitForeignCall(linkage, null, gen.operand(array1), gen.operand(array2), gen.operand(length));

                gen.setResult(this, result);

                return;

            }

        }

        gen.setResult(this, result);

    }

    @Override

    public LocationIdentity getLocationIdentity() {

        return NamedLocationIdentity.getArrayLocation(kind);

    }

    @Override

    public MemoryNode getLastLocationAccess() {

        return lastLocationAccess;

    }

    @Override

    public void setLastLocationAccess(MemoryNode lla) {

        updateUsages(ValueNodeUtil.asNode(lastLocationAccess), ValueNodeUtil.asNode(lla));

        lastLocationAccess = lla;

    }

}