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/*
 * Copyright (c) 2018, 2018, 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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.svm.hosted.phases;

import java.lang.reflect.Method;
import java.util.function.Supplier;

import org.graalvm.compiler.nodes.CallTargetNode.InvokeKind;
import org.graalvm.compiler.nodes.ConstantNode;
import org.graalvm.compiler.nodes.FrameState;
import org.graalvm.compiler.nodes.ValueNode;
import org.graalvm.compiler.nodes.graphbuilderconf.ClassInitializationPlugin;
import org.graalvm.compiler.nodes.graphbuilderconf.GraphBuilderContext;

import com.oracle.svm.core.hub.DynamicHub;
import com.oracle.svm.core.meta.SubstrateObjectConstant;
import com.oracle.svm.core.util.VMError;
import com.oracle.svm.hosted.SVMHost;

import jdk.vm.ci.meta.ConstantPool;
import jdk.vm.ci.meta.JavaConstant;
import jdk.vm.ci.meta.ResolvedJavaType;

public class SubstrateClassInitializationPlugin implements ClassInitializationPlugin {

    public static final Method ENSURE_INITIALIZED_METHOD;

    static {
        try {
            ENSURE_INITIALIZED_METHOD = DynamicHub.class.getDeclaredMethod("ensureInitialized");
        } catch (ReflectiveOperationException ex) {
            throw VMError.shouldNotReachHere(ex);
        }
    }

    private final SVMHost host;

    public SubstrateClassInitializationPlugin(SVMHost host) {
        this.host = host;
    }

    @Override
    public boolean supportsLazyInitialization(ConstantPool cp) {
        return true;
    }

    @Override
    public void loadReferencedType(GraphBuilderContext builder, ConstantPool constantPool, int cpi, int bytecode) {
        constantPool.loadReferencedType(cpi, bytecode);
    }

    @Override
    public boolean apply(GraphBuilderContext builder, ResolvedJavaType type, Supplier frameState, ValueNode[] classInit) {
        if (needsRuntimeInitialization(builder.getMethod().getDeclaringClass(), type)) {
            emitEnsureClassInitialized(builder, SubstrateObjectConstant.forObject(host.dynamicHub(type)));
            /*
             * The classInit value is only registered with Invoke nodes. Since we do not need that,
             * we ensure it is null.
             */
            if (classInit != null) {
                classInit[0] = null;
            }
            return true;
        }
        return false;
    }

    public static void emitEnsureClassInitialized(GraphBuilderContext builder, JavaConstant hubConstant) {
        ValueNode[] args = {ConstantNode.forConstant(hubConstant, builder.getMetaAccess(), builder.getGraph())};
        builder.handleReplacedInvoke(InvokeKind.Special, builder.getMetaAccess().lookupJavaMethod(ENSURE_INITIALIZED_METHOD), args, false);
    }

    /**
     * Return true if the type needs to be initialized at run time, i.e., it has not been already
     * initialized during image generation.
     */
    static boolean needsRuntimeInitialization(ResolvedJavaType declaringClass, ResolvedJavaType type) {
        return !declaringClass.equals(type) && !type.isInitialized() && !type.isArray();
    }
}