1/*
2 * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23package jdk.vm.ci.hotspot;
24
25/**
26 * Describes a C++ field exposed via {@link HotSpotVMConfigAccess}.
27 */
28public final class VMField {
29
30    /**
31     * Fully qualified name of the represented field (e.g., "Klass::_name").
32     */
33    public final String name;
34
35    /**
36     * The represented field's type (e.g., "Symbol*"). This may be {@code null}.
37     */
38    public final String type;
39
40    /**
41     * If the represented field is non-static, this is its offset within the containing structure.
42     */
43    public final long offset;
44
45    /**
46     * If the represented field is static, this is its address. Otherwise, this is 0.
47     */
48    public final long address;
49
50    /**
51     * Value of the field represented as a boxed boolean if its C++ type is bool otherwise as a
52     * boxed long; only valid for non-oop static fields. This value is only captured once, during
53     * JVMCI initialization. If {@link #type} cannot be meaningfully (e.g., a struct) or safely
54     * (e.g., an oop) expressed as a boxed object, this is {@code null}.
55     */
56    public final Object value;
57
58    /**
59     * Determines if the represented field is static.
60     */
61    public boolean isStatic() {
62        return address != 0;
63    }
64
65    /**
66     * Creates a description of a non-static field.
67     */
68    public VMField(String name, String type, long offset) {
69        this.name = name;
70        this.type = type;
71        this.offset = offset;
72        this.address = 0;
73        this.value = null;
74    }
75
76    /**
77     * Creates a description of a static field.
78     */
79    public VMField(String name, String type, long address, Long value) {
80        this.name = name;
81        this.type = type;
82        this.offset = 0;
83        this.address = address;
84        this.value = value;
85    }
86
87    @Override
88    public String toString() {
89        String val = value == null ? "null" : String.format("0x%x", value);
90        return String.format("Field[name=%s, type=%s, offset=%d, address=0x%x, value=%s]", name, type, offset, address, val);
91    }
92}
93