1 /*
2 * Copyright (c) 1999, 2011, 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 *
23 */
24
25 #ifndef SHARE_VM_CI_CIFIELD_HPP
26 #define SHARE_VM_CI_CIFIELD_HPP
27
28 #include "ci/ciClassList.hpp"
29 #include "ci/ciConstant.hpp"
30 #include "ci/ciFlags.hpp"
31 #include "ci/ciInstance.hpp"
32
33 // ciField
34 //
35 // This class represents the result of a field lookup in the VM.
36 // The lookup may not succeed, in which case the information in
37 // the ciField will be incomplete.
38 class ciField : public ResourceObj {
39 CI_PACKAGE_ACCESS
40 friend class ciEnv;
41 friend class ciInstanceKlass;
42 friend class NonStaticFieldFiller;
43
44 private:
45 ciFlags _flags;
46 ciInstanceKlass* _holder;
47 ciSymbol* _name;
48 ciSymbol* _signature;
49 ciType* _type;
50 int _offset;
51 bool _is_constant;
52 ciInstanceKlass* _known_to_link_with;
53 ciConstant _constant_value;
54
55 // Used for will_link
56 int _cp_index;
57
58 ciType* compute_type();
59 ciType* compute_type_impl();
60
61 ciField(ciInstanceKlass* klass, int index);
62 ciField(fieldDescriptor* fd);
63
64 // shared constructor code
65 void initialize_from(fieldDescriptor* fd);
66
67 // The implementation of the print method.
68 void print_impl(outputStream* st);
69
70 public:
71 ciFlags flags() { return _flags; }
72
73 // Of which klass is this field a member?
74 //
75 // Usage note: the declared holder of a field is the class
76 // referenced by name in the bytecodes. The canonical holder
77 // is the most general class which holds the field. This
78 // method returns the canonical holder. The declared holder
79 // can be accessed via a method in ciBytecodeStream.
80 //
81 // Ex.
82 // class A {
83 // public int f = 7;
84 // }
85 // class B extends A {
86 // public void test() {
87 // System.out.println(f);
88 // }
89 // }
90 //
91 // A java compiler is permitted to compile the access to
92 // field f as:
93 //
94 // getfield B.f
95 //
96 // In that case the declared holder of f would be B and
97 // the canonical holder of f would be A.
98 ciInstanceKlass* holder() { return _holder; }
99
100 // Name of this field?
101 ciSymbol* name() { return _name; }
102
103 // Signature of this field?
104 ciSymbol* signature() { return _signature; }
105
106 // Of what type is this field?
107 ciType* type() { return (_type == NULL) ? compute_type() : _type; }
108
109 // How is this field actually stored in memory?
110 BasicType layout_type() { return type2field[(_type == NULL) ? T_OBJECT : _type->basic_type()]; }
111
112 // How big is this field in memory?
113 int size_in_bytes() { return type2aelembytes(layout_type()); }
114
115 // What is the offset of this field?
116 int offset() {
117 assert(_offset >= 1, "illegal call to offset()");
118 return _offset;
119 }
120
121 // Same question, explicit units. (Fields are aligned to the byte level.)
122 int offset_in_bytes() {
123 return offset();
124 }
125
126 // Is this field shared?
127 bool is_shared() {
128 // non-static fields of shared holders are cached
129 return _holder->is_shared() && !is_static();
130 }
131
132 // Is this field a constant?
133 //
134 // Clarification: A field is considered constant if:
135 // 1. The field is both static and final
136 // 2. The canonical holder of the field has undergone
137 // static initialization.
138 // 3. If the field is an object or array, then the oop
139 // in question is allocated in perm space.
140 // 4. The field is not one of the special static/final
141 // non-constant fields. These are java.lang.System.in
142 // and java.lang.System.out. Abomination.
143 //
144 // Note: the check for case 4 is not yet implemented.
145 bool is_constant() { return _is_constant; }
146
147 // Get the constant value of this field.
148 ciConstant constant_value() {
149 assert(is_static() && is_constant(), "illegal call to constant_value()");
150 return _constant_value;
151 }
152
153 // Get the constant value of non-static final field in the given
154 // object.
155 ciConstant constant_value_of(ciObject* object) {
156 assert(!is_static() && is_constant(), "only if field is non-static constant");
157 assert(object->is_instance(), "must be instance");
158 return object->as_instance()->field_value(this);
159 }
160
161 // Check for link time errors. Accessing a field from a
162 // certain class via a certain bytecode may or may not be legal.
163 // This call checks to see if an exception may be raised by
164 // an access of this field.
165 //
166 // Usage note: if the same field is accessed multiple times
167 // in the same compilation, will_link will need to be checked
168 // at each point of access.
169 bool will_link(ciInstanceKlass* accessing_klass,
170 Bytecodes::Code bc);
171
172 // Java access flags
173 bool is_public () { return flags().is_public(); }
174 bool is_private () { return flags().is_private(); }
175 bool is_protected () { return flags().is_protected(); }
176 bool is_static () { return flags().is_static(); }
177 bool is_final () { return flags().is_final(); }
178 bool is_volatile () { return flags().is_volatile(); }
179 bool is_transient () { return flags().is_transient(); }
180
181 bool is_call_site_target() { return ((holder() == CURRENT_ENV->CallSite_klass()) && (name() == ciSymbol::target_name())); }
182
183 // Debugging output
184 void print();
185 void print_name_on(outputStream* st);
186 };
187
188 #endif // SHARE_VM_CI_CIFIELD_HPP