1 /*
2 * Copyright (c) 2011, 2015, 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_OOPS_FIELDINFO_HPP
26 #define SHARE_VM_OOPS_FIELDINFO_HPP
27
28 #include "oops/constantPool.hpp"
29 #include "oops/typeArrayOop.hpp"
30 #include "classfile/vmSymbols.hpp"
31
32 // This class represents the field information contained in the fields
33 // array of an InstanceKlass. Currently it's laid on top an array of
34 // Java shorts but in the future it could simply be used as a real
35 // array type. FieldInfo generally shouldn't be used directly.
36 // Fields should be queried either through InstanceKlass or through
37 // the various FieldStreams.
38 class FieldInfo VALUE_OBJ_CLASS_SPEC {
39 friend class fieldDescriptor;
40 friend class JavaFieldStream;
41 friend class ClassFileParser;
42
43 public:
44 // fields
45 // Field info extracted from the class file and stored
46 // as an array of 6 shorts.
47
48 #define FIELDINFO_TAG_SIZE 3
49 #define FIELDINFO_TAG_BLANK 0
50 #define FIELDINFO_TAG_OFFSET 1
51 #define FIELDINFO_TAG_TYPE_PLAIN 2
52 #define FIELDINFO_TAG_TYPE_CONTENDED 3
53 #define FIELDINFO_TAG_TYPE_MASK 3
54 #define FIELDINFO_TAG_MASK 7
55 #define FIELDINFO_FLATTENING_OFFSET 2
56
57 // Packed field has the tag, and can be either of:
58 // hi bits <--------------------------- lo bits
59 // |---------high---------|---------low---------|
60 // ..........................................00 - blank
61 // [------------------offset----------------]01 - real field offset
62 // ......................[-------type-------]10 - plain field with type
63 // [--contention_group--][-------type-------]11 - contended field with type and contention group
64 enum FieldOffset {
65 access_flags_offset = 0,
66 name_index_offset = 1,
67 signature_index_offset = 2,
68 initval_index_offset = 3,
69 low_packed_offset = 4,
70 high_packed_offset = 5,
71 field_slots = 6
72 };
73
74 private:
75 u2 _shorts[field_slots];
76
77 void set_name_index(u2 val) { _shorts[name_index_offset] = val; }
78 void set_signature_index(u2 val) { _shorts[signature_index_offset] = val; }
79 void set_initval_index(u2 val) { _shorts[initval_index_offset] = val; }
80
81 u2 name_index() const { return _shorts[name_index_offset]; }
82 u2 signature_index() const { return _shorts[signature_index_offset]; }
83 u2 initval_index() const { return _shorts[initval_index_offset]; }
84
85 public:
86 static FieldInfo* from_field_array(Array<u2>* fields, int index) {
87 return ((FieldInfo*)fields->adr_at(index * field_slots));
88 }
89 static FieldInfo* from_field_array(u2* fields, int index) {
90 return ((FieldInfo*)(fields + index * field_slots));
91 }
92
93 void initialize(u2 access_flags,
94 u2 name_index,
95 u2 signature_index,
96 u2 initval_index) {
97 _shorts[access_flags_offset] = access_flags;
98 _shorts[name_index_offset] = name_index;
99 _shorts[signature_index_offset] = signature_index;
100 _shorts[initval_index_offset] = initval_index;
101 _shorts[low_packed_offset] = 0;
102 _shorts[high_packed_offset] = 0;
103 }
104
105 u2 access_flags() const { return _shorts[access_flags_offset]; }
106 u4 offset() const {
107 u2 lo = _shorts[low_packed_offset];
108 switch(lo & FIELDINFO_TAG_TYPE_MASK) {
109 case FIELDINFO_TAG_OFFSET:
110 return build_int_from_shorts(_shorts[low_packed_offset], _shorts[high_packed_offset]) >> FIELDINFO_TAG_SIZE;
111 #ifndef PRODUCT
112 case FIELDINFO_TAG_TYPE_PLAIN:
113 fatal("Asking offset for the plain type field");
114 case FIELDINFO_TAG_TYPE_CONTENDED:
115 fatal("Asking offset for the contended type field");
116 case FIELDINFO_TAG_BLANK:
117 fatal("Asking offset for the blank field");
118 #endif
119 }
120 ShouldNotReachHere();
121 return 0;
122 }
123
124 bool is_contended() const {
125 u2 lo = _shorts[low_packed_offset];
126 switch(lo & FIELDINFO_TAG_TYPE_MASK) {
127 case FIELDINFO_TAG_TYPE_PLAIN:
128 return false;
129 case FIELDINFO_TAG_TYPE_CONTENDED:
130 return true;
131 #ifndef PRODUCT
132 case FIELDINFO_TAG_OFFSET:
133 fatal("Asking contended flag for the field with offset");
134 case FIELDINFO_TAG_BLANK:
135 fatal("Asking contended flag for the blank field");
136 #endif
137 }
138 ShouldNotReachHere();
139 return false;
140 }
141
142 u2 contended_group() const {
143 u2 lo = _shorts[low_packed_offset];
144 switch(lo & FIELDINFO_TAG_TYPE_MASK) {
145 case FIELDINFO_TAG_TYPE_PLAIN:
146 return 0;
147 case FIELDINFO_TAG_TYPE_CONTENDED:
148 return _shorts[high_packed_offset];
149 #ifndef PRODUCT
150 case FIELDINFO_TAG_OFFSET:
151 fatal("Asking the contended group for the field with offset");
152 case FIELDINFO_TAG_BLANK:
153 fatal("Asking the contended group for the blank field");
154 #endif
155 }
156 ShouldNotReachHere();
157 return 0;
158 }
159
160 u2 allocation_type() const {
161 u2 lo = _shorts[low_packed_offset];
162 switch(lo & FIELDINFO_TAG_TYPE_MASK) {
163 case FIELDINFO_TAG_TYPE_PLAIN:
164 case FIELDINFO_TAG_TYPE_CONTENDED:
165 return (lo >> FIELDINFO_TAG_SIZE);
166 #ifndef PRODUCT
167 case FIELDINFO_TAG_OFFSET:
168 fatal("Asking the field type for field with offset");
169 case FIELDINFO_TAG_BLANK:
170 fatal("Asking the field type for the blank field");
171 #endif
172 }
173 ShouldNotReachHere();
174 return 0;
175 }
176
177 bool is_offset_set() const {
178 return (_shorts[low_packed_offset] & FIELDINFO_TAG_TYPE_MASK) == FIELDINFO_TAG_OFFSET;
179 }
180
181 Symbol* name(const constantPoolHandle& cp) const {
182 int index = name_index();
183 if (is_internal()) {
184 return lookup_symbol(index);
185 }
186 return cp->symbol_at(index);
187 }
188
189 Symbol* signature(const constantPoolHandle& cp) const {
190 int index = signature_index();
191 if (is_internal()) {
192 return lookup_symbol(index);
193 }
194 return cp->symbol_at(index);
195 }
196
197 void set_access_flags(u2 val) { _shorts[access_flags_offset] = val; }
198 void set_offset(u4 val) {
199 val = val << FIELDINFO_TAG_SIZE; // make room for tag
200 bool flatten = is_flatten();
201 _shorts[low_packed_offset] = extract_low_short_from_int(val) | FIELDINFO_TAG_OFFSET;
202 if (flatten) set_flattening(true);
203 _shorts[high_packed_offset] = extract_high_short_from_int(val);
204 assert(is_flatten() || !flatten, "just checking");
205 }
206
207 void set_allocation_type(int type) {
208 bool b = is_flatten();
209 u2 lo = _shorts[low_packed_offset];
210 switch(lo & FIELDINFO_TAG_TYPE_MASK) {
211 case FIELDINFO_TAG_BLANK:
212 _shorts[low_packed_offset] |= ((type << FIELDINFO_TAG_SIZE)) & 0xFFFF;
213 _shorts[low_packed_offset] &= ~FIELDINFO_TAG_TYPE_MASK;
214 _shorts[low_packed_offset] |= FIELDINFO_TAG_TYPE_PLAIN;
215 assert(is_flatten() || !b, "Just checking");
216 return;
217 #ifndef PRODUCT
218 case FIELDINFO_TAG_TYPE_PLAIN:
219 case FIELDINFO_TAG_TYPE_CONTENDED:
220 case FIELDINFO_TAG_OFFSET:
221 fatal("Setting the field type with overwriting");
222 #endif
223 }
224 ShouldNotReachHere();
225 }
226
227 void set_flattening(bool b) {
228 if (b) {
229 _shorts[low_packed_offset] |= 1 << FIELDINFO_FLATTENING_OFFSET;
230 } else {
231 _shorts[low_packed_offset] &= ~(1 << FIELDINFO_FLATTENING_OFFSET);
232 }
233 }
234
235 bool is_flatten() {
236 return ((_shorts[low_packed_offset] >> FIELDINFO_FLATTENING_OFFSET) & 1) != 0;
237 }
238
239 void set_contended_group(u2 val) {
240 u2 lo = _shorts[low_packed_offset];
241 switch(lo & FIELDINFO_TAG_TYPE_MASK) {
242 case FIELDINFO_TAG_TYPE_PLAIN:
243 _shorts[low_packed_offset] |= FIELDINFO_TAG_TYPE_CONTENDED;
244 _shorts[high_packed_offset] = val;
245 return;
246 #ifndef PRODUCT
247 case FIELDINFO_TAG_TYPE_CONTENDED:
248 fatal("Overwriting contended group");
249 case FIELDINFO_TAG_BLANK:
250 fatal("Setting contended group for the blank field");
251 case FIELDINFO_TAG_OFFSET:
252 fatal("Setting contended group for field with offset");
253 #endif
254 }
255 ShouldNotReachHere();
256 }
257
258 bool is_internal() const {
259 return (access_flags() & JVM_ACC_FIELD_INTERNAL) != 0;
260 }
261
262 bool is_stable() const {
263 return (access_flags() & JVM_ACC_FIELD_STABLE) != 0;
264 }
265 void set_stable(bool z) {
266 if (z) _shorts[access_flags_offset] |= JVM_ACC_FIELD_STABLE;
267 else _shorts[access_flags_offset] &= ~JVM_ACC_FIELD_STABLE;
268 }
269
270 Symbol* lookup_symbol(int symbol_index) const {
271 assert(is_internal(), "only internal fields");
272 return vmSymbols::symbol_at((vmSymbols::SID)symbol_index);
273 }
274 };
275
276 #endif // SHARE_VM_OOPS_FIELDINFO_HPP