/*

 * 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 org.graalvm.compiler.core.common.spi.JavaConstantFieldProvider;

import org.graalvm.compiler.hotspot.GraalHotSpotVMConfig;

import org.graalvm.compiler.options.OptionValues;

import jdk.vm.ci.hotspot.HotSpotResolvedJavaField;

import jdk.vm.ci.meta.MetaAccessProvider;

import jdk.vm.ci.meta.ResolvedJavaField;

import jdk.vm.ci.meta.ResolvedJavaType;

/**

 * Implements the default constant folding semantics for Java fields in the HotSpot VM.

 */

public class HotSpotConstantFieldProvider extends JavaConstantFieldProvider {

    private final GraalHotSpotVMConfig config;

    public HotSpotConstantFieldProvider(GraalHotSpotVMConfig config, MetaAccessProvider metaAccess) {

        super(metaAccess);

        this.config = config;

    }

    @Override

    protected boolean isStableField(ResolvedJavaField field, ConstantFieldTool<?> tool) {

        if (!config.foldStableValues) {

            return false;

        }

        if (field.isStatic() && !isStaticFieldConstant(field, tool.getOptions())) {

            return false;

        }

        if (((HotSpotResolvedJavaField) field).isStable()) {

            return true;

        }

        return super.isStableField(field, tool);

    }

    @Override

    protected boolean isFinalField(ResolvedJavaField field, ConstantFieldTool<?> tool) {

        if (field.isStatic() && !isStaticFieldConstant(field, tool.getOptions())) {

            return false;

        }

        return super.isFinalField(field, tool);

    }

    private static final String SystemClassName = "Ljava/lang/System;";

    protected boolean isStaticFieldConstant(ResolvedJavaField field, @SuppressWarnings("unused") OptionValues options) {

        ResolvedJavaType declaringClass = field.getDeclaringClass();

        return declaringClass.isInitialized() && !declaringClass.getName().equals(SystemClassName);

    }

}