1 /*
2 * Copyright (c) 1999, 2013, 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
43 private:
44 ciFlags _flags;
45 ciInstanceKlass* _holder;
46 ciSymbol* _name;
47 ciSymbol* _signature;
48 ciType* _type;
49 int _offset;
50 bool _is_constant;
51 ciMethod* _known_to_link_with_put;
52 ciInstanceKlass* _known_to_link_with_get;
53 ciConstant _constant_value;
54
55 ciType* compute_type();
56 ciType* compute_type_impl();
57
58 ciField(ciInstanceKlass* klass, int index);
59 ciField(fieldDescriptor* fd);
60
61 // shared constructor code
62 void initialize_from(fieldDescriptor* fd);
63
64 public:
65 ciFlags flags() const { return _flags; }
66
67 // Of which klass is this field a member?
68 //
69 // Usage note: the declared holder of a field is the class
70 // referenced by name in the bytecodes. The canonical holder
71 // is the most general class which holds the field. This
72 // method returns the canonical holder. The declared holder
73 // can be accessed via a method in ciBytecodeStream.
74 //
75 // Ex.
76 // class A {
77 // public int f = 7;
78 // }
79 // class B extends A {
80 // public void test() {
81 // System.out.println(f);
82 // }
83 // }
84 //
85 // A java compiler is permitted to compile the access to
86 // field f as:
87 //
88 // getfield B.f
89 //
90 // In that case the declared holder of f would be B and
91 // the canonical holder of f would be A.
92 ciInstanceKlass* holder() const { return _holder; }
93
94 // Name of this field?
95 ciSymbol* name() const { return _name; }
96
97 // Signature of this field?
98 ciSymbol* signature() const { return _signature; }
99
100 // Of what type is this field?
101 ciType* type() { return (_type == NULL) ? compute_type() : _type; }
102
103 // How is this field actually stored in memory?
104 BasicType layout_type() { return type2field[(_type == NULL) ? T_OBJECT : _type->basic_type()]; }
105
106 // How big is this field in memory?
107 int size_in_bytes() { return type2aelembytes(layout_type()); }
108
109 // What is the offset of this field?
110 int offset() const {
111 assert(_offset >= 1, "illegal call to offset()");
112 return _offset;
113 }
114
115 // Same question, explicit units. (Fields are aligned to the byte level.)
116 int offset_in_bytes() const {
117 return offset();
118 }
119
120 // Is this field shared?
121 bool is_shared() {
122 // non-static fields of shared holders are cached
123 return _holder->is_shared() && !is_static();
124 }
125
126 // Is this field a constant?
127 //
128 // Clarification: A field is considered constant if:
129 // 1. The field is both static and final
130 // 2. The field is not one of the special static/final
131 // non-constant fields. These are java.lang.System.in
132 // and java.lang.System.out. Abomination.
133 //
134 // A field is also considered constant if
135 // - it is marked @Stable and is non-null (or non-zero, if a primitive) or
136 // - it is trusted or
137 // - it is the target field of a CallSite object.
138 //
139 // See ciField::initialize_from() for more details.
140 //
141 // A user should also check the field value (constant_value().is_valid()), since
142 // constant fields of non-initialized classes don't have values yet.
143 bool is_constant() const { return _is_constant; }
144
145 // Get the constant value of the static field.
146 ciConstant constant_value();
147
148 bool is_static_constant() {
149 return is_static() && is_constant() && constant_value().is_valid();
150 }
151
152 // Get the constant value of non-static final field in the given
153 // object.
154 ciConstant constant_value_of(ciObject* object);
155
156 // Check for link time errors. Accessing a field from a
157 // certain method via a certain bytecode may or may not be legal.
158 // This call checks to see if an exception may be raised by
159 // an access of this field.
160 //
161 // Usage note: if the same field is accessed multiple times
162 // in the same compilation, will_link will need to be checked
163 // at each point of access.
164 bool will_link(ciMethod* accessing_method,
165 Bytecodes::Code bc);
166
167 // Java access flags
168 bool is_public () const { return flags().is_public(); }
169 bool is_private () const { return flags().is_private(); }
170 bool is_protected () const { return flags().is_protected(); }
171 bool is_static () const { return flags().is_static(); }
172 bool is_final () const { return flags().is_final(); }
173 bool is_stable () const { return flags().is_stable(); }
174 bool is_volatile () const { return flags().is_volatile(); }
175 bool is_transient () const { return flags().is_transient(); }
176 // The field is modified outside of instance initializer methods
177 // (or class/initializer methods if the field is static).
178 bool has_initialized_final_update() const { return flags().has_initialized_final_update(); }
179
180 bool is_call_site_target() {
181 ciInstanceKlass* callsite_klass = CURRENT_ENV->CallSite_klass();
182 if (callsite_klass == NULL)
183 return false;
184 return (holder()->is_subclass_of(callsite_klass) && (name() == ciSymbol::target_name()));
185 }
186
187 bool is_autobox_cache() {
188 ciSymbol* klass_name = holder()->name();
189 return (name() == ciSymbol::cache_field_name() &&
190 holder()->uses_default_loader() &&
191 (klass_name == ciSymbol::java_lang_Character_CharacterCache() ||
192 klass_name == ciSymbol::java_lang_Byte_ByteCache() ||
193 klass_name == ciSymbol::java_lang_Short_ShortCache() ||
194 klass_name == ciSymbol::java_lang_Integer_IntegerCache() ||
195 klass_name == ciSymbol::java_lang_Long_LongCache()));
196 }
197
198 // Debugging output
199 void print();
200 void print_name_on(outputStream* st);
201 };
202
203 #endif // SHARE_VM_CI_CIFIELD_HPP