1 /*
2 * Copyright (c) 2011, 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_OOPS_FIELDINFO_HPP
26 #define SHARE_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 {
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_TAG_FLATTENED 4
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---------------]F01 - real field offset
62 // ......................[-------type------]F10 - plain field with type
63 // [--contention_group--][-------type------]F11 - contended field with type and contention group
64 //
65 // Bit F indicates if the field has been flattened (F=1) or nor (F=0)
66
67 enum FieldOffset {
68 access_flags_offset = 0,
69 name_index_offset = 1,
70 signature_index_offset = 2,
71 initval_index_offset = 3,
72 low_packed_offset = 4,
73 high_packed_offset = 5,
74 field_slots = 6
75 };
76
77 private:
78 u2 _shorts[field_slots];
79
80 void set_name_index(u2 val) { _shorts[name_index_offset] = val; }
81 void set_signature_index(u2 val) { _shorts[signature_index_offset] = val; }
82 void set_initval_index(u2 val) { _shorts[initval_index_offset] = val; }
83
84 u2 name_index() const { return _shorts[name_index_offset]; }
85 u2 signature_index() const { return _shorts[signature_index_offset]; }
86 u2 initval_index() const { return _shorts[initval_index_offset]; }
87
88 public:
89 static FieldInfo* from_field_array(Array<u2>* fields, int index) {
90 return ((FieldInfo*)fields->adr_at(index * field_slots));
91 }
92 static FieldInfo* from_field_array(u2* fields, int index) {
93 return ((FieldInfo*)(fields + index * field_slots));
94 }
95
96 void initialize(u2 access_flags,
97 u2 name_index,
98 u2 signature_index,
99 u2 initval_index) {
100 _shorts[access_flags_offset] = access_flags;
101 _shorts[name_index_offset] = name_index;
102 _shorts[signature_index_offset] = signature_index;
103 _shorts[initval_index_offset] = initval_index;
104 _shorts[low_packed_offset] = 0;
105 _shorts[high_packed_offset] = 0;
106 }
107
108 u2 access_flags() const { return _shorts[access_flags_offset]; }
109 u4 offset() const {
110 u2 lo = _shorts[low_packed_offset];
111 switch(lo & FIELDINFO_TAG_TYPE_MASK) {
112 case FIELDINFO_TAG_OFFSET:
113 return build_int_from_shorts(_shorts[low_packed_offset], _shorts[high_packed_offset]) >> FIELDINFO_TAG_SIZE;
114 #ifndef PRODUCT
115 case FIELDINFO_TAG_TYPE_PLAIN:
116 fatal("Asking offset for the plain type field");
117 case FIELDINFO_TAG_TYPE_CONTENDED:
118 fatal("Asking offset for the contended type field");
119 case FIELDINFO_TAG_BLANK:
120 fatal("Asking offset for the blank field");
121 #endif
122 }
123 ShouldNotReachHere();
124 return 0;
125 }
126
127 bool is_contended() const {
128 u2 lo = _shorts[low_packed_offset];
129 switch(lo & FIELDINFO_TAG_TYPE_MASK) {
130 case FIELDINFO_TAG_TYPE_PLAIN:
131 return false;
132 case FIELDINFO_TAG_TYPE_CONTENDED:
133 return true;
134 #ifndef PRODUCT
135 case FIELDINFO_TAG_OFFSET:
136 fatal("Asking contended flag for the field with offset");
137 case FIELDINFO_TAG_BLANK:
138 fatal("Asking contended flag for the blank field");
139 #endif
140 }
141 ShouldNotReachHere();
142 return false;
143 }
144
145 u2 contended_group() const {
146 u2 lo = _shorts[low_packed_offset];
147 switch(lo & FIELDINFO_TAG_TYPE_MASK) {
148 case FIELDINFO_TAG_TYPE_PLAIN:
149 return 0;
150 case FIELDINFO_TAG_TYPE_CONTENDED:
151 return _shorts[high_packed_offset];
152 #ifndef PRODUCT
153 case FIELDINFO_TAG_OFFSET:
154 fatal("Asking the contended group for the field with offset");
155 case FIELDINFO_TAG_BLANK:
156 fatal("Asking the contended group for the blank field");
157 #endif
158 }
159 ShouldNotReachHere();
160 return 0;
161 }
162
163 u2 allocation_type() const {
164 u2 lo = _shorts[low_packed_offset];
165 switch(lo & FIELDINFO_TAG_TYPE_MASK) {
166 case FIELDINFO_TAG_TYPE_PLAIN:
167 case FIELDINFO_TAG_TYPE_CONTENDED:
168 return (lo >> FIELDINFO_TAG_SIZE);
169 #ifndef PRODUCT
170 case FIELDINFO_TAG_OFFSET:
171 fatal("Asking the field type for field with offset");
172 case FIELDINFO_TAG_BLANK:
173 fatal("Asking the field type for the blank field");
174 #endif
175 }
176 ShouldNotReachHere();
177 return 0;
178 }
179
180 bool is_offset_set() const {
181 return (_shorts[low_packed_offset] & FIELDINFO_TAG_TYPE_MASK) == FIELDINFO_TAG_OFFSET;
182 }
183
184 Symbol* name(const constantPoolHandle& cp) const {
185 int index = name_index();
186 if (is_internal()) {
187 return lookup_symbol(index);
188 }
189 return cp->symbol_at(index);
190 }
191
192 Symbol* signature(const constantPoolHandle& cp) const {
193 int index = signature_index();
194 if (is_internal()) {
195 return lookup_symbol(index);
196 }
197 return cp->symbol_at(index);
198 }
199
200 void set_access_flags(u2 val) { _shorts[access_flags_offset] = val; }
201 void set_offset(u4 val) {
202 val = val << FIELDINFO_TAG_SIZE; // make room for tag
203 bool flattened = is_flattened();
204 _shorts[low_packed_offset] = extract_low_short_from_int(val) | FIELDINFO_TAG_OFFSET;
205 if (flattened) set_flattened(true);
206 _shorts[high_packed_offset] = extract_high_short_from_int(val);
207 assert(is_flattened() || !flattened, "just checking");
208 }
209
210 void set_allocation_type(int type) {
211 bool b = is_flattened();
212 u2 lo = _shorts[low_packed_offset];
213 switch(lo & FIELDINFO_TAG_TYPE_MASK) {
214 case FIELDINFO_TAG_BLANK:
215 _shorts[low_packed_offset] |= ((type << FIELDINFO_TAG_SIZE)) & 0xFFFF;
216 _shorts[low_packed_offset] &= ~FIELDINFO_TAG_TYPE_MASK;
217 _shorts[low_packed_offset] |= FIELDINFO_TAG_TYPE_PLAIN;
218 assert(is_flattened() || !b, "Just checking");
219 return;
220 #ifndef PRODUCT
221 case FIELDINFO_TAG_TYPE_PLAIN:
222 case FIELDINFO_TAG_TYPE_CONTENDED:
223 case FIELDINFO_TAG_OFFSET:
224 fatal("Setting the field type with overwriting");
225 #endif
226 }
227 ShouldNotReachHere();
228 }
229
230 void set_flattened(bool b) {
231 if (b) {
232 _shorts[low_packed_offset] |= FIELDINFO_TAG_FLATTENED;
233 } else {
234 _shorts[low_packed_offset] &= ~FIELDINFO_TAG_FLATTENED;
235 }
236 }
237
238 bool is_flattened() {
239 return (_shorts[low_packed_offset] & FIELDINFO_TAG_FLATTENED) != 0;
240 }
241
242 void set_contended_group(u2 val) {
243 u2 lo = _shorts[low_packed_offset];
244 switch(lo & FIELDINFO_TAG_TYPE_MASK) {
245 case FIELDINFO_TAG_TYPE_PLAIN:
246 _shorts[low_packed_offset] |= FIELDINFO_TAG_TYPE_CONTENDED;
247 _shorts[high_packed_offset] = val;
248 return;
249 #ifndef PRODUCT
250 case FIELDINFO_TAG_TYPE_CONTENDED:
251 fatal("Overwriting contended group");
252 case FIELDINFO_TAG_BLANK:
253 fatal("Setting contended group for the blank field");
254 case FIELDINFO_TAG_OFFSET:
255 fatal("Setting contended group for field with offset");
256 #endif
257 }
258 ShouldNotReachHere();
259 }
260
261 bool is_internal() const {
262 return (access_flags() & JVM_ACC_FIELD_INTERNAL) != 0;
263 }
264
265 bool is_stable() const {
266 return (access_flags() & JVM_ACC_FIELD_STABLE) != 0;
267 }
268 void set_stable(bool z) {
269 if (z) _shorts[access_flags_offset] |= JVM_ACC_FIELD_STABLE;
270 else _shorts[access_flags_offset] &= ~JVM_ACC_FIELD_STABLE;
271 }
272
273 bool is_flattenable() const {
274 return (access_flags() & JVM_ACC_FLATTENABLE) != 0;
275 }
276
277 Symbol* lookup_symbol(int symbol_index) const {
278 assert(is_internal(), "only internal fields");
279 return vmSymbols::symbol_at((vmSymbols::SID)symbol_index);
280 }
281 };
282
283 #endif // SHARE_OOPS_FIELDINFO_HPP