1 /*
2 * Copyright (c) 1999, 2019, 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_CI_CIFIELD_HPP
26 #define SHARE_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 #include "ci/ciUtilities.hpp"
33
34 // ciField
35 //
36 // This class represents the result of a field lookup in the VM.
37 // The lookup may not succeed, in which case the information in
38 // the ciField will be incomplete.
39 class ciField : public ResourceObj {
40 CI_PACKAGE_ACCESS
41 friend class ciEnv;
42 friend class ciInstanceKlass;
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 bool _is_flattened;
53 bool _is_flattenable;
54 ciMethod* _known_to_link_with_put;
55 ciInstanceKlass* _known_to_link_with_get;
56 ciConstant _constant_value;
57
58 ciType* compute_type();
59 ciType* compute_type_impl();
60
61 ciField(ciInstanceKlass* klass, int index);
62 ciField(fieldDescriptor* fd);
63 ciField(ciField* field, ciInstanceKlass* holder, int offset, bool is_final);
64
65 // shared constructor code
66 void initialize_from(fieldDescriptor* fd);
67
68 public:
69 ciFlags flags() const { 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() const { return _holder; }
97
98 // Name of this field?
99 ciSymbol* name() const { return _name; }
100
101 // Signature of this field?
102 ciSymbol* signature() const { 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()->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() const {
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() const {
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 field is not one of the special static/final
135 // non-constant fields. These are java.lang.System.in
136 // and java.lang.System.out. Abomination.
137 //
138 // A field is also considered constant if
139 // - it is marked @Stable and is non-null (or non-zero, if a primitive) or
140 // - it is trusted or
141 // - it is the target field of a CallSite object.
142 //
143 // See ciField::initialize_from() for more details.
144 //
145 // A user should also check the field value (constant_value().is_valid()), since
146 // constant fields of non-initialized classes don't have values yet.
147 bool is_constant() const { return _is_constant; }
148
149 // Get the constant value of the static field.
150 ciConstant constant_value();
151
152 bool is_static_constant() {
153 return is_static() && is_constant() && constant_value().is_valid();
154 }
155
156 // Get the constant value of non-static final field in the given
157 // object.
158 ciConstant constant_value_of(ciObject* object);
159
160 // Check for link time errors. Accessing a field from a
161 // certain method via a certain bytecode may or may not be legal.
162 // This call checks to see if an exception may be raised by
163 // an access of this field.
164 //
165 // Usage note: if the same field is accessed multiple times
166 // in the same compilation, will_link will need to be checked
167 // at each point of access.
168 bool will_link(ciMethod* accessing_method,
169 Bytecodes::Code bc);
170
171 // Java access flags
172 bool is_public () const { return flags().is_public(); }
173 bool is_private () const { return flags().is_private(); }
174 bool is_protected () const { return flags().is_protected(); }
175 bool is_static () const { return flags().is_static(); }
176 bool is_final () const { return flags().is_final(); }
177 bool is_stable () const { return flags().is_stable(); }
178 bool is_volatile () const { return flags().is_volatile(); }
179 bool is_transient () const { return flags().is_transient(); }
180 bool is_flattened () const { return _is_flattened; }
181 bool is_flattenable () const { return _is_flattenable; }
182
183 // The field is modified outside of instance initializer methods
184 // (or class/initializer methods if the field is static).
185 bool has_initialized_final_update() const { return flags().has_initialized_final_update(); }
186
187 bool is_call_site_target() {
188 ciInstanceKlass* callsite_klass = CURRENT_ENV->CallSite_klass();
189 if (callsite_klass == NULL)
190 return false;
191 return (holder()->is_subclass_of(callsite_klass) && (name() == ciSymbol::target_name()));
192 }
193
194 bool is_autobox_cache() {
195 ciSymbol* klass_name = holder()->name();
196 return (name() == ciSymbol::cache_field_name() &&
197 holder()->uses_default_loader() &&
198 (klass_name == ciSymbol::java_lang_Character_CharacterCache() ||
199 klass_name == ciSymbol::java_lang_Byte_ByteCache() ||
200 klass_name == ciSymbol::java_lang_Short_ShortCache() ||
201 klass_name == ciSymbol::java_lang_Integer_IntegerCache() ||
202 klass_name == ciSymbol::java_lang_Long_LongCache()));
203 }
204
205 // Debugging output
206 void print();
207 void print_name_on(outputStream* st);
208 };
209
210 #endif // SHARE_CI_CIFIELD_HPP