/*

 * Copyright (c) 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.meta;

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

import java.util.ArrayList;

import java.util.List;

import org.graalvm.compiler.debug.GraalError;

import org.graalvm.compiler.graph.NodeClass;

import org.graalvm.compiler.hotspot.GraalHotSpotVMConfig;

import org.graalvm.compiler.options.OptionValues;

import org.graalvm.compiler.replacements.SnippetCounter;

import jdk.vm.ci.meta.JavaConstant;

import jdk.vm.ci.meta.MetaAccessProvider;

import jdk.vm.ci.meta.ResolvedJavaField;

import jdk.vm.ci.meta.ResolvedJavaType;

/**

 * Extends {@link HotSpotConstantFieldProvider} to override the implementation of

 * {@link #readConstantField} with Graal specific semantics.

 */

public class HotSpotGraalConstantFieldProvider extends HotSpotConstantFieldProvider {

    public HotSpotGraalConstantFieldProvider(GraalHotSpotVMConfig config, MetaAccessProvider metaAccess) {

        super(config, metaAccess);

        this.metaAccess = metaAccess;

    }

    @Override

    protected boolean isStaticFieldConstant(ResolvedJavaField field, OptionValues options) {

        return super.isStaticFieldConstant(field, options) && (!ImmutableCode.getValue(options) || isEmbeddableField(field));

    }

    /**

     * The set of fields whose values cannot be constant folded in ImmutableCode mode. This is

     * volatile to support double-checked locking lazy initialization.

     */

    private volatile List<ResolvedJavaField> nonEmbeddableFields;

    protected boolean isEmbeddableField(ResolvedJavaField field) {

        if (nonEmbeddableFields == null) {

            synchronized (this) {

                if (nonEmbeddableFields == null) {

                    List<ResolvedJavaField> fields = new ArrayList<>();

                    try {

                        fields.add(metaAccess.lookupJavaField(Boolean.class.getDeclaredField("TRUE")));

                        fields.add(metaAccess.lookupJavaField(Boolean.class.getDeclaredField("FALSE")));

                        Class<?> characterCacheClass = Character.class.getDeclaredClasses()[0];

                        assert "java.lang.Character$CharacterCache".equals(characterCacheClass.getName());

                        fields.add(metaAccess.lookupJavaField(characterCacheClass.getDeclaredField("cache")));

                        Class<?> byteCacheClass = Byte.class.getDeclaredClasses()[0];

                        assert "java.lang.Byte$ByteCache".equals(byteCacheClass.getName());

                        fields.add(metaAccess.lookupJavaField(byteCacheClass.getDeclaredField("cache")));

                        Class<?> shortCacheClass = Short.class.getDeclaredClasses()[0];

                        assert "java.lang.Short$ShortCache".equals(shortCacheClass.getName());

                        fields.add(metaAccess.lookupJavaField(shortCacheClass.getDeclaredField("cache")));

                        Class<?> integerCacheClass = Integer.class.getDeclaredClasses()[0];

                        assert "java.lang.Integer$IntegerCache".equals(integerCacheClass.getName());

                        fields.add(metaAccess.lookupJavaField(integerCacheClass.getDeclaredField("cache")));

                        Class<?> longCacheClass = Long.class.getDeclaredClasses()[0];

                        assert "java.lang.Long$LongCache".equals(longCacheClass.getName());

                        fields.add(metaAccess.lookupJavaField(longCacheClass.getDeclaredField("cache")));

                        fields.add(metaAccess.lookupJavaField(Throwable.class.getDeclaredField("UNASSIGNED_STACK")));

                        fields.add(metaAccess.lookupJavaField(Throwable.class.getDeclaredField("SUPPRESSED_SENTINEL")));

                    } catch (SecurityException | NoSuchFieldException e) {

                        throw new GraalError(e);

                    }

                    nonEmbeddableFields = fields;

                }

            }

        }

        return !nonEmbeddableFields.contains(field);

    }

    @Override

    protected boolean isFinalFieldValueConstant(ResolvedJavaField field, JavaConstant value, ConstantFieldTool<?> tool) {

        if (super.isFinalFieldValueConstant(field, value, tool)) {

            return true;

        }

        if (!field.isStatic()) {

            JavaConstant receiver = tool.getReceiver();

            if (getSnippetCounterType().isInstance(receiver) || getNodeClassType().isInstance(receiver)) {

                return true;

            }

        }

        return false;

    }

    @Override

    protected boolean isStableFieldValueConstant(ResolvedJavaField field, JavaConstant value, ConstantFieldTool<?> tool) {

        if (super.isStableFieldValueConstant(field, value, tool)) {

            return true;

        }

        if (!field.isStatic()) {

            JavaConstant receiver = tool.getReceiver();

            if (getHotSpotVMConfigType().isInstance(receiver)) {

                return true;

            }

        }

        return false;

    }

    private final MetaAccessProvider metaAccess;

    private ResolvedJavaType cachedHotSpotVMConfigType;

    private ResolvedJavaType cachedSnippetCounterType;

    private ResolvedJavaType cachedNodeClassType;

    private ResolvedJavaType getHotSpotVMConfigType() {

        if (cachedHotSpotVMConfigType == null) {

            cachedHotSpotVMConfigType = metaAccess.lookupJavaType(GraalHotSpotVMConfig.class);

        }

        return cachedHotSpotVMConfigType;

    }

    private ResolvedJavaType getSnippetCounterType() {

        if (cachedSnippetCounterType == null) {

            cachedSnippetCounterType = metaAccess.lookupJavaType(SnippetCounter.class);

        }

        return cachedSnippetCounterType;

    }

    private ResolvedJavaType getNodeClassType() {

        if (cachedNodeClassType == null) {

            cachedNodeClassType = metaAccess.lookupJavaType(NodeClass.class);

        }

        return cachedNodeClassType;

    }

}