1 /*
2 * Copyright (c) 1999, 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.
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_put;
53 ciInstanceKlass* _known_to_link_with_get;
54 ciConstant _constant_value;
55
56 // Used for will_link
57 int _cp_index;
58
59 ciType* compute_type();
60 ciType* compute_type_impl();
61
62 ciField(ciInstanceKlass* klass, int index);
63 ciField(fieldDescriptor* fd);
64
65 // shared constructor code
66 void initialize_from(fieldDescriptor* fd);
67
68 public:
69 ciFlags flags() { return _flags; }
70
71 // Of which klass is this field a member?
72 //
73 // Usage note: the declared holder of a field is the class
74 // referenced by name in the bytecodes. The canonical holder
75 // is the most general class which holds the field. This
76 // method returns the canonical holder. The declared holder
77 // can be accessed via a method in ciBytecodeStream.
78 //
79 // Ex.
80 // class A {
81 // public int f = 7;
82 // }
83 // class B extends A {
84 // public void test() {
85 // System.out.println(f);
86 // }
87 // }
88 //
89 // A java compiler is permitted to compile the access to
90 // field f as:
91 //
92 // getfield B.f
93 //
94 // In that case the declared holder of f would be B and
95 // the canonical holder of f would be A.
96 ciInstanceKlass* holder() { return _holder; }
97
98 // Name of this field?
99 ciSymbol* name() { return _name; }
100
101 // Signature of this field?
102 ciSymbol* signature() { return _signature; }
103
104 // Of what type is this field?
105 ciType* type() { return (_type == NULL) ? compute_type() : _type; }
106
107 // How is this field actually stored in memory?
108 BasicType layout_type() { return type2field[(_type == NULL) ? T_OBJECT : _type->basic_type()]; }
109
110 // How big is this field in memory?
111 int size_in_bytes() { return type2aelembytes(layout_type()); }
112
113 // What is the offset of this field?
114 int offset() {
115 assert(_offset >= 1, "illegal call to offset()");
116 return _offset;
117 }
118
119 // Same question, explicit units. (Fields are aligned to the byte level.)
120 int offset_in_bytes() {
121 return offset();
122 }
123
124 // Is this field shared?
125 bool is_shared() {
126 // non-static fields of shared holders are cached
127 return _holder->is_shared() && !is_static();
128 }
129
130 // Is this field a constant?
131 //
132 // Clarification: A field is considered constant if:
133 // 1. The field is both static and final
134 // 2. The canonical holder of the field has undergone
135 // static initialization.
136 // 3. If the field is an object or array, then the oop
137 // in question is allocated in perm space.
138 // 4. The field is not one of the special static/final
139 // non-constant fields. These are java.lang.System.in
140 // and java.lang.System.out. Abomination.
141 //
142 // Note: the check for case 4 is not yet implemented.
143 bool is_constant() { return _is_constant; }
144
145 // Get the constant value of this field.
146 ciConstant constant_value() {
147 assert(is_static() && is_constant(), "illegal call to constant_value()");
148 return _constant_value;
149 }
150
151 // Get the constant value of non-static final field in the given
152 // object.
153 ciConstant constant_value_of(ciObject* object) {
154 assert(!is_static() && is_constant(), "only if field is non-static constant");
155 assert(object->is_instance(), "must be instance");
156 return object->as_instance()->field_value(this);
157 }
158
159 // Check for link time errors. Accessing a field from a
160 // certain class via a certain bytecode may or may not be legal.
161 // This call checks to see if an exception may be raised by
162 // an access of this field.
163 //
164 // Usage note: if the same field is accessed multiple times
165 // in the same compilation, will_link will need to be checked
166 // at each point of access.
167 bool will_link(ciInstanceKlass* accessing_klass,
168 Bytecodes::Code bc);
169
170 // Java access flags
171 bool is_public () { return flags().is_public(); }
172 bool is_private () { return flags().is_private(); }
173 bool is_protected () { return flags().is_protected(); }
174 bool is_static () { return flags().is_static(); }
175 bool is_final () { return flags().is_final(); }
176 bool is_volatile () { return flags().is_volatile(); }
177 bool is_transient () { return flags().is_transient(); }
178
179 bool is_call_site_target() {
180 ciInstanceKlass* callsite_klass = CURRENT_ENV->CallSite_klass();
181 if (callsite_klass == NULL)
182 return false;
183 return (holder()->is_subclass_of(callsite_klass) && (name() == ciSymbol::target_name()));
184 }
185
186 // Debugging output
187 void print();
188 void print_name_on(outputStream* st);
189 };
190
191 #endif // SHARE_VM_CI_CIFIELD_HPP