hotspot/src/jdk.vm.ci/share/classes/jdk.vm.ci.hotspot/src/jdk/vm/ci/hotspot/VMField.java

/*
 * 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 jdk.vm.ci.hotspot;

/**
 * Describes a C++ field exposed via {@link HotSpotVMConfigAccess}.
 */
public final class VMField {

    /**
     * Fully qualified name of the represented field (e.g., "Klass::_name").
     */
    public final String name;

    /**
     * The represented field's type (e.g., "Symbol*"). This may be {@code null}.
     */
    public final String type;

    /**
     * If represented field is non-static, this is its offset within the containing structure.
     */
    public final long offset;

    /**
     * If represented field is static, this is its address. Otherwise, this field is 0.
     */
    public final long address;

    /**
     * Value of the field represented as a boxed long; only valid for non-oop static fields. This
     * value is only captured once, during JVMCI initialization. If {@link #type} cannot be
     * meaningfully (e.g., a struct) or safely (e.g., an oop) expressed as a boxed long, this is
     * {@code null}.
     */
    public final Long value;

    /**
     * Determines if the represented field is static.
     */
    public boolean isStatic() {
        return address != 0;
    }

    /**
     * Creates a description of a non-static field.
     */
    public VMField(String name, String type, long offset) {
        this.name = name;
        this.type = type;
        this.offset = offset;
        this.address = 0;
        this.value = null;
    }

    /**
     * Creates a description of a static field.
     */
    public VMField(String name, String type, long address, Long value) {
        this.name = name;
        this.type = type;
        this.offset = 0;
        this.address = address;
        this.value = value;
    }

    @Override
    public String toString() {
        String val = value == null ? "null" : String.format("0x%x", value);
        return String.format("Field[name=%s, type=%s, offset=%d, address=0x%x, value=%s]", name, type, offset, address, val);
    }
}