/*
 * 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
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package org.graalvm.compiler.hotspot.replacements;

import static org.graalvm.compiler.hotspot.GraalHotSpotVMConfig.INJECTED_METAACCESS;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.referentOffset;
import static org.graalvm.compiler.replacements.SnippetTemplate.DEFAULT_REPLACER;

import org.graalvm.compiler.api.replacements.Snippet;
import org.graalvm.compiler.debug.DebugHandlersFactory;
import org.graalvm.compiler.hotspot.meta.HotSpotProviders;
import org.graalvm.compiler.nodes.extended.FixedValueAnchorNode;
import org.graalvm.compiler.nodes.extended.RawLoadNode;
import org.graalvm.compiler.nodes.memory.HeapAccess.BarrierType;
import org.graalvm.compiler.nodes.spi.LoweringTool;
import org.graalvm.compiler.options.OptionValues;
import org.graalvm.compiler.replacements.SnippetTemplate.AbstractTemplates;
import org.graalvm.compiler.replacements.SnippetTemplate.Arguments;
import org.graalvm.compiler.replacements.SnippetTemplate.SnippetInfo;
import org.graalvm.compiler.replacements.Snippets;
import org.graalvm.compiler.word.Word;

import jdk.vm.ci.code.TargetDescription;

public class UnsafeLoadSnippets implements Snippets {

    @Snippet
    public static Object lowerUnsafeLoad(Object object, long offset) {
        Object fixedObject = FixedValueAnchorNode.getObject(object);
        if (object instanceof java.lang.ref.Reference && referentOffset(INJECTED_METAACCESS) == offset) {
            return Word.objectToTrackedPointer(fixedObject).readObject((int) offset, BarrierType.WEAK_FIELD);
        } else {
            return Word.objectToTrackedPointer(fixedObject).readObject((int) offset, BarrierType.NONE);
        }
    }

    public static class Templates extends AbstractTemplates {

        private final SnippetInfo unsafeLoad = snippet(UnsafeLoadSnippets.class, "lowerUnsafeLoad");

        public Templates(OptionValues options, Iterable<DebugHandlersFactory> factories, HotSpotProviders providers, TargetDescription target) {
            super(options, factories, providers, providers.getSnippetReflection(), target);
        }

        public void lower(RawLoadNode load, LoweringTool tool) {
            Arguments args = new Arguments(unsafeLoad, load.graph().getGuardsStage(), tool.getLoweringStage());
            args.add("object", load.object());
            args.add("offset", load.offset());
            template(load, args).instantiate(providers.getMetaAccess(), load, DEFAULT_REPLACER, args);
        }
    }
}