1 #ifdef USE_PRAGMA_IDENT_HDR
2 #pragma ident "@(#)ciField.hpp 1.23 07/09/28 10:23:24 JVM"
3 #endif
4 /*
5 * Copyright 1999-2006 Sun Microsystems, Inc. All Rights Reserved.
6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
7 *
8 * This code is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 only, as
10 * published by the Free Software Foundation.
11 *
12 * This code is distributed in the hope that it will be useful, but WITHOUT
13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 * version 2 for more details (a copy is included in the LICENSE file that
16 * accompanied this code).
17 *
18 * You should have received a copy of the GNU General Public License version
19 * 2 along with this work; if not, write to the Free Software Foundation,
20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
21 *
22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
23 * CA 95054 USA or visit www.sun.com if you need additional information or
24 * have any questions.
25 *
26 */
27
28 // ciField
29 //
30 // This class represents the result of a field lookup in the VM.
31 // The lookup may not succeed, in which case the information in
32 // the ciField will be incomplete.
33 class ciField : public ResourceObj {
34 CI_PACKAGE_ACCESS
35 friend class ciEnv;
36 friend class ciInstanceKlass;
37 friend class NonStaticFieldFiller;
38
39 private:
40 ciFlags _flags;
41 ciInstanceKlass* _holder;
42 ciSymbol* _name;
43 ciSymbol* _signature;
44 ciType* _type;
45 int _offset;
46 bool _is_constant;
47 ciInstanceKlass* _known_to_link_with;
48 ciConstant _constant_value;
49
50 // Used for will_link
51 int _cp_index;
52
53 ciType* compute_type();
54 ciType* compute_type_impl();
55
56 ciField(ciInstanceKlass* klass, int index);
57 ciField(fieldDescriptor* fd);
58
59 // shared constructor code
60 void initialize_from(fieldDescriptor* fd);
61
62 // The implementation of the print method.
63 void print_impl(outputStream* st);
64
65 public:
66 ciFlags flags() { return _flags; }
67
68 // Of which klass is this field a member?
69 //
70 // Usage note: the declared holder of a field is the class
71 // referenced by name in the bytecodes. The canonical holder
72 // is the most general class which holds the field. This
73 // method returns the canonical holder. The declared holder
74 // can be accessed via a method in ciBytecodeStream.
75 //
76 // Ex.
77 // class A {
78 // public int f = 7;
79 // }
80 // class B extends A {
81 // public void test() {
82 // System.out.println(f);
83 // }
84 // }
85 //
86 // A java compiler is permitted to compile the access to
87 // field f as:
88 //
89 // getfield B.f
90 //
91 // In that case the declared holder of f would be B and
92 // the canonical holder of f would be A.
93 ciInstanceKlass* holder() { return _holder; }
94
95 // Name of this field?
96 ciSymbol* name() { return _name; }
97
98 // Signature of this field?
99 ciSymbol* signature() { return _signature; }
100
101 // Of what type is this field?
102 ciType* type() { return (_type == NULL) ? compute_type() : _type; }
103
104 // How is this field actually stored in memory?
105 BasicType layout_type() { return type2field[(_type == NULL) ? T_OBJECT : _type->basic_type()]; }
106
107 // How big is this field in memory?
108 int size_in_bytes() { return type2aelembytes[layout_type()]; }
109
110 // What is the offset of this field?
111 int offset() {
112 assert(_offset >= 1, "illegal call to offset()");
113 return _offset;
114 }
115
116 // Same question, explicit units. (Fields are aligned to the byte level.)
117 int offset_in_bytes() {
118 return offset();
119 }
120
121 // Is this field shared?
122 bool is_shared() {
123 // non-static fields of shared holders are cached
124 return _holder->is_shared() && !is_static();
125 }
126
127 // Is this field a constant?
128 //
129 // Clarification: A field is considered constant if:
130 // 1. The field is both static and final
131 // 2. The canonical holder of the field has undergone
132 // static initialization.
133 // 3. If the field is an object or array, then the oop
134 // in question is allocated in perm space.
135 // 4. The field is not one of the special static/final
136 // non-constant fields. These are java.lang.System.in
137 // and java.lang.System.out. Abomination.
138 //
139 // Note: the check for case 4 is not yet implemented.
140 bool is_constant() { return _is_constant; }
141
142 // Get the constant value of this field.
143 ciConstant constant_value() {
144 assert(is_constant(), "illegal call to constant_value()");
145 return _constant_value;
146 }
147
148 // Check for link time errors. Accessing a field from a
149 // certain class via a certain bytecode may or may not be legal.
150 // This call checks to see if an exception may be raised by
151 // an access of this field.
152 //
153 // Usage note: if the same field is accessed multiple times
154 // in the same compilation, will_link will need to be checked
155 // at each point of access.
156 bool will_link(ciInstanceKlass* accessing_klass,
157 Bytecodes::Code bc);
158
159 // Java access flags
160 bool is_public () { return flags().is_public(); }
161 bool is_private () { return flags().is_private(); }
162 bool is_protected () { return flags().is_protected(); }
163 bool is_static () { return flags().is_static(); }
164 bool is_final () { return flags().is_final(); }
165 bool is_volatile () { return flags().is_volatile(); }
166 bool is_transient () { return flags().is_transient(); }
167
168 // Debugging output
169 void print();
170 void print_name_on(outputStream* st);
171 };