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 bool _is_flattened;
52 ciMethod* _known_to_link_with_put;
53 ciInstanceKlass* _known_to_link_with_get;
54 ciConstant _constant_value;
55
56 ciType* compute_type();
57 ciType* compute_type_impl();
58
59 ciField(ciInstanceKlass* klass, int index);
60 ciField(fieldDescriptor* fd);
61 ciField(ciField* field, ciInstanceKlass* holder, int offset, bool is_final);
62
63 // shared constructor code
64 void initialize_from(fieldDescriptor* fd);
65
66 public:
67 ciFlags flags() const { return _flags; }
68
69 // Of which klass is this field a member?
70 //
71 // Usage note: the declared holder of a field is the class
72 // referenced by name in the bytecodes. The canonical holder
73 // is the most general class which holds the field. This
74 // method returns the canonical holder. The declared holder
75 // can be accessed via a method in ciBytecodeStream.
76 //
77 // Ex.
78 // class A {
79 // public int f = 7;
80 // }
81 // class B extends A {
82 // public void test() {
83 // System.out.println(f);
84 // }
85 // }
86 //
87 // A java compiler is permitted to compile the access to
88 // field f as:
89 //
90 // getfield B.f
91 //
92 // In that case the declared holder of f would be B and
93 // the canonical holder of f would be A.
94 ciInstanceKlass* holder() const { return _holder; }
95
96 // Name of this field?
97 ciSymbol* name() const { return _name; }
98
99 // Signature of this field?
100 ciSymbol* signature() const { return _signature; }
101
102 // Of what type is this field?
103 ciType* type() { return (_type == NULL) ? compute_type() : _type; }
104
105 // How is this field actually stored in memory?
106 BasicType layout_type() { return type2field[(_type == NULL) ? T_OBJECT : _type->basic_type()]; }
107
108 // How big is this field in memory?
109 int size_in_bytes() { return type2aelembytes(layout_type()); }
110
111 // What is the offset of this field?
112 int offset() const {
113 assert(_offset >= 1, "illegal call to offset()");
114 return _offset;
115 }
116
117 // Same question, explicit units. (Fields are aligned to the byte level.)
118 int offset_in_bytes() const {
119 return offset();
120 }
121
122 // Is this field shared?
123 bool is_shared() {
124 // non-static fields of shared holders are cached
125 return _holder->is_shared() && !is_static();
126 }
127
128 // Is this field a constant?
129 //
130 // Clarification: A field is considered constant if:
131 // 1. The field is both static and final
132 // 2. The field is not one of the special static/final
133 // non-constant fields. These are java.lang.System.in
134 // and java.lang.System.out. Abomination.
135 //
136 // A field is also considered constant if
137 // - it is marked @Stable and is non-null (or non-zero, if a primitive) or
138 // - it is trusted or
139 // - it is the target field of a CallSite object.
140 //
141 // See ciField::initialize_from() for more details.
142 //
143 // A user should also check the field value (constant_value().is_valid()), since
144 // constant fields of non-initialized classes don't have values yet.
145 bool is_constant() const { return _is_constant; }
146
147 // Get the constant value of the static field.
148 ciConstant constant_value();
149
150 bool is_static_constant() {
151 return is_static() && is_constant() && constant_value().is_valid();
152 }
153
154 // Get the constant value of non-static final field in the given
155 // object.
156 ciConstant constant_value_of(ciObject* object);
157
158 // Check for link time errors. Accessing a field from a
159 // certain method via a certain bytecode may or may not be legal.
160 // This call checks to see if an exception may be raised by
161 // an access of this field.
162 //
163 // Usage note: if the same field is accessed multiple times
164 // in the same compilation, will_link will need to be checked
165 // at each point of access.
166 bool will_link(ciMethod* accessing_method,
167 Bytecodes::Code bc);
168
169 // Java access flags
170 bool is_public () const { return flags().is_public(); }
171 bool is_private () const { return flags().is_private(); }
172 bool is_protected () const { return flags().is_protected(); }
173 bool is_static () const { return flags().is_static(); }
174 bool is_final () const { return flags().is_final(); }
175 bool is_stable () const { return flags().is_stable(); }
176 bool is_volatile () const { return flags().is_volatile(); }
177 bool is_transient () const { return flags().is_transient(); }
178 bool is_flattened () const { return _is_flattened; }
179 // The field is modified outside of instance initializer methods
180 // (or class/initializer methods if the field is static).
181 bool has_initialized_final_update() const { return flags().has_initialized_final_update(); }
182
183 bool is_call_site_target() {
184 ciInstanceKlass* callsite_klass = CURRENT_ENV->CallSite_klass();
185 if (callsite_klass == NULL)
186 return false;
187 return (holder()->is_subclass_of(callsite_klass) && (name() == ciSymbol::target_name()));
188 }
189
190 bool is_autobox_cache() {
191 ciSymbol* klass_name = holder()->name();
192 return (name() == ciSymbol::cache_field_name() &&
193 holder()->uses_default_loader() &&
194 (klass_name == ciSymbol::java_lang_Character_CharacterCache() ||
195 klass_name == ciSymbol::java_lang_Byte_ByteCache() ||
196 klass_name == ciSymbol::java_lang_Short_ShortCache() ||
197 klass_name == ciSymbol::java_lang_Integer_IntegerCache() ||
198 klass_name == ciSymbol::java_lang_Long_LongCache()));
199 }
200
201 // Debugging output
202 void print();
203 void print_name_on(outputStream* st);
204 };
205
206 #endif // SHARE_VM_CI_CIFIELD_HPP