fieldInfo.hpp revision 3602:da91efe96a93 
1/*
2 * Copyright (c) 2011, 2012, 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.
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23 */
24
25#ifndef SHARE_VM_OOPS_FIELDINFO_HPP
26#define SHARE_VM_OOPS_FIELDINFO_HPP
27
28#include "oops/constantPool.hpp"
29#include "oops/typeArrayOop.hpp"
30#include "classfile/vmSymbols.hpp"
31
32// This class represents the field information contained in the fields
33// array of an InstanceKlass.  Currently it's laid on top an array of
34// Java shorts but in the future it could simply be used as a real
35// array type.  FieldInfo generally shouldn't be used directly.
36// Fields should be queried either through InstanceKlass or through
37// the various FieldStreams.
38class FieldInfo VALUE_OBJ_CLASS_SPEC {
39  friend class fieldDescriptor;
40  friend class JavaFieldStream;
41  friend class ClassFileParser;
42
43 public:
44  // fields
45  // Field info extracted from the class file and stored
46  // as an array of 7 shorts
47  enum FieldOffset {
48    access_flags_offset      = 0,
49    name_index_offset        = 1,
50    signature_index_offset   = 2,
51    initval_index_offset     = 3,
52    low_offset               = 4,
53    high_offset              = 5,
54    field_slots              = 6
55  };
56
57 private:
58  u2 _shorts[field_slots];
59
60  void set_name_index(u2 val)                    { _shorts[name_index_offset] = val;         }
61  void set_signature_index(u2 val)               { _shorts[signature_index_offset] = val;    }
62  void set_initval_index(u2 val)                 { _shorts[initval_index_offset] = val;      }
63
64  u2 name_index() const                          { return _shorts[name_index_offset];        }
65  u2 signature_index() const                     { return _shorts[signature_index_offset];   }
66  u2 initval_index() const                       { return _shorts[initval_index_offset];     }
67
68 public:
69  static FieldInfo* from_field_array(Array<u2>* fields, int index) {
70    return ((FieldInfo*)fields->adr_at(index * field_slots));
71  }
72  static FieldInfo* from_field_array(u2* fields, int index) {
73    return ((FieldInfo*)(fields + index * field_slots));
74  }
75
76  void initialize(u2 access_flags,
77                  u2 name_index,
78                  u2 signature_index,
79                  u2 initval_index,
80                  u4 offset) {
81    _shorts[access_flags_offset] = access_flags;
82    _shorts[name_index_offset] = name_index;
83    _shorts[signature_index_offset] = signature_index;
84    _shorts[initval_index_offset] = initval_index;
85    set_offset(offset);
86  }
87
88  u2 access_flags() const                        { return _shorts[access_flags_offset];            }
89  u4 offset() const                              { return build_int_from_shorts(_shorts[low_offset], _shorts[high_offset]); }
90
91  Symbol* name(constantPoolHandle cp) const {
92    int index = name_index();
93    if (is_internal()) {
94      return lookup_symbol(index);
95    }
96    return cp->symbol_at(index);
97  }
98
99  Symbol* signature(constantPoolHandle cp) const {
100    int index = signature_index();
101    if (is_internal()) {
102      return lookup_symbol(index);
103    }
104    return cp->symbol_at(index);
105  }
106
107  void set_access_flags(u2 val)                  { _shorts[access_flags_offset] = val;             }
108  void set_offset(u4 val)                        {
109    _shorts[low_offset] = extract_low_short_from_int(val);
110    _shorts[high_offset] = extract_high_short_from_int(val);
111  }
112
113  bool is_internal() const {
114    return (access_flags() & JVM_ACC_FIELD_INTERNAL) != 0;
115  }
116
117  Symbol* lookup_symbol(int symbol_index) const {
118    assert(is_internal(), "only internal fields");
119    return vmSymbols::symbol_at((vmSymbols::SID)symbol_index);
120  }
121};
122
123#endif // SHARE_VM_OOPS_FIELDINFO_HPP
124