1 /*
2 * Copyright 1997-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 // A constantPool is an array containing class constants as described in the
26 // class file.
27 //
28 // Most of the constant pool entries are written during class parsing, which
29 // is safe. For klass and string types, the constant pool entry is
30 // modified when the entry is resolved. If a klass or string constant pool
31 // entry is read without a lock, only the resolved state guarantees that
32 // the entry in the constant pool is a klass or String object and
33 // not a symbolOop.
34
35 class SymbolHashMap;
36
37 class constantPoolOopDesc : public arrayOopDesc {
38 friend class VMStructs;
39 friend class BytecodeInterpreter; // Directly extracts an oop in the pool for fast instanceof/checkcast
40 private:
41 typeArrayOop _tags; // the tag array describing the constant pool's contents
42 constantPoolCacheOop _cache; // the cache holding interpreter runtime information
43 klassOop _pool_holder; // the corresponding class
44 // only set to non-zero if constant pool is merged by RedefineClasses
45 int _orig_length;
46
47 void set_tags(typeArrayOop tags) { oop_store_without_check((oop*)&_tags, tags); }
48 void tag_at_put(int which, jbyte t) { tags()->byte_at_put(which, t); }
49 void release_tag_at_put(int which, jbyte t) { tags()->release_byte_at_put(which, t); }
50
51 private:
52 intptr_t* base() const { return (intptr_t*) (((char*) this) + sizeof(constantPoolOopDesc)); }
53 oop* tags_addr() { return (oop*)&_tags; }
54 oop* cache_addr() { return (oop*)&_cache; }
55
56 oop* obj_at_addr(int which) const {
57 assert(is_within_bounds(which), "index out of bounds");
58 return (oop*) &base()[which];
59 }
60
61 jint* int_at_addr(int which) const {
62 assert(is_within_bounds(which), "index out of bounds");
63 return (jint*) &base()[which];
64 }
65
66 jlong* long_at_addr(int which) const {
67 assert(is_within_bounds(which), "index out of bounds");
68 return (jlong*) &base()[which];
69 }
70
71 jfloat* float_at_addr(int which) const {
72 assert(is_within_bounds(which), "index out of bounds");
73 return (jfloat*) &base()[which];
74 }
75
76 jdouble* double_at_addr(int which) const {
77 assert(is_within_bounds(which), "index out of bounds");
78 return (jdouble*) &base()[which];
79 }
80
81 public:
82 typeArrayOop tags() const { return _tags; }
83
84 // Klass holding pool
85 klassOop pool_holder() const { return _pool_holder; }
86 void set_pool_holder(klassOop k) { oop_store_without_check((oop*)&_pool_holder, (oop) k); }
87 oop* pool_holder_addr() { return (oop*)&_pool_holder; }
88
89 // Interpreter runtime support
90 constantPoolCacheOop cache() const { return _cache; }
91 void set_cache(constantPoolCacheOop cache){ oop_store((oop*)&_cache, cache); }
92
93 // Assembly code support
94 static int tags_offset_in_bytes() { return offset_of(constantPoolOopDesc, _tags); }
95 static int cache_offset_in_bytes() { return offset_of(constantPoolOopDesc, _cache); }
96 static int pool_holder_offset_in_bytes() { return offset_of(constantPoolOopDesc, _pool_holder); }
97
98 // Storing constants
99
100 void klass_at_put(int which, klassOop k) {
101 oop_store_without_check((volatile oop *)obj_at_addr(which), oop(k));
102 // The interpreter assumes when the tag is stored, the klass is resolved
103 // and the klassOop is a klass rather than a symbolOop, so we need
104 // hardware store ordering here.
105 release_tag_at_put(which, JVM_CONSTANT_Class);
106 if (UseConcMarkSweepGC) {
107 // In case the earlier card-mark was consumed by a concurrent
108 // marking thread before the tag was updated, redirty the card.
109 oop_store_without_check((volatile oop *)obj_at_addr(which), oop(k));
110 }
111 }
112
113 // For temporary use while constructing constant pool
114 void klass_index_at_put(int which, int name_index) {
115 tag_at_put(which, JVM_CONSTANT_ClassIndex);
116 *int_at_addr(which) = name_index;
117 }
118
119 // Temporary until actual use
120 void unresolved_klass_at_put(int which, symbolOop s) {
121 // Overwrite the old index with a GC friendly value so
122 // that if GC looks during the transition it won't try
123 // to treat a small integer as oop.
124 *obj_at_addr(which) = NULL;
125 release_tag_at_put(which, JVM_CONSTANT_UnresolvedClass);
126 oop_store_without_check(obj_at_addr(which), oop(s));
127 }
128
129 // Temporary until actual use
130 void unresolved_string_at_put(int which, symbolOop s) {
131 *obj_at_addr(which) = NULL;
132 release_tag_at_put(which, JVM_CONSTANT_UnresolvedString);
133 oop_store_without_check(obj_at_addr(which), oop(s));
134 }
135
136 void int_at_put(int which, jint i) {
137 tag_at_put(which, JVM_CONSTANT_Integer);
138 *int_at_addr(which) = i;
139 }
140
141 void long_at_put(int which, jlong l) {
142 tag_at_put(which, JVM_CONSTANT_Long);
143 // *long_at_addr(which) = l;
144 Bytes::put_native_u8((address)long_at_addr(which), *((u8*) &l));
145 }
146
147 void float_at_put(int which, jfloat f) {
148 tag_at_put(which, JVM_CONSTANT_Float);
149 *float_at_addr(which) = f;
150 }
151
152 void double_at_put(int which, jdouble d) {
153 tag_at_put(which, JVM_CONSTANT_Double);
154 // *double_at_addr(which) = d;
155 // u8 temp = *(u8*) &d;
156 Bytes::put_native_u8((address) double_at_addr(which), *((u8*) &d));
157 }
158
159 void symbol_at_put(int which, symbolOop s) {
160 tag_at_put(which, JVM_CONSTANT_Utf8);
161 oop_store_without_check(obj_at_addr(which), oop(s));
162 }
163
164 void string_at_put(int which, oop str) {
165 oop_store((volatile oop*)obj_at_addr(which), str);
166 release_tag_at_put(which, JVM_CONSTANT_String);
167 if (UseConcMarkSweepGC) {
168 // In case the earlier card-mark was consumed by a concurrent
169 // marking thread before the tag was updated, redirty the card.
170 oop_store_without_check((volatile oop *)obj_at_addr(which), str);
171 }
172 }
173
174 // For temporary use while constructing constant pool
175 void string_index_at_put(int which, int string_index) {
176 tag_at_put(which, JVM_CONSTANT_StringIndex);
177 *int_at_addr(which) = string_index;
178 }
179
180 void field_at_put(int which, int class_index, int name_and_type_index) {
181 tag_at_put(which, JVM_CONSTANT_Fieldref);
182 *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index;
183 }
184
185 void method_at_put(int which, int class_index, int name_and_type_index) {
186 tag_at_put(which, JVM_CONSTANT_Methodref);
187 *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index;
188 }
189
190 void interface_method_at_put(int which, int class_index, int name_and_type_index) {
191 tag_at_put(which, JVM_CONSTANT_InterfaceMethodref);
192 *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index; // Not so nice
193 }
194
195 void name_and_type_at_put(int which, int name_index, int signature_index) {
196 tag_at_put(which, JVM_CONSTANT_NameAndType);
197 *int_at_addr(which) = ((jint) signature_index<<16) | name_index; // Not so nice
198 }
199
200 // Tag query
201
202 constantTag tag_at(int which) const { return (constantTag)tags()->byte_at_acquire(which); }
203
204 // Whether the entry is a pointer that must be GC'd.
205 bool is_pointer_entry(int which) {
206 constantTag tag = tag_at(which);
207 return tag.is_klass() ||
208 tag.is_unresolved_klass() ||
209 tag.is_symbol() ||
210 tag.is_unresolved_string() ||
211 tag.is_string();
212 }
213
214 // Fetching constants
215
216 klassOop klass_at(int which, TRAPS) {
217 constantPoolHandle h_this(THREAD, this);
218 return klass_at_impl(h_this, which, CHECK_NULL);
219 }
220
221 symbolOop klass_name_at(int which); // Returns the name, w/o resolving.
222
223 klassOop resolved_klass_at(int which) { // Used by Compiler
224 guarantee(tag_at(which).is_klass(), "Corrupted constant pool");
225 // Must do an acquire here in case another thread resolved the klass
226 // behind our back, lest we later load stale values thru the oop.
227 return klassOop((oop)OrderAccess::load_ptr_acquire(obj_at_addr(which)));
228 }
229
230 // This method should only be used with a cpool lock or during parsing or gc
231 symbolOop unresolved_klass_at(int which) { // Temporary until actual use
232 symbolOop s = symbolOop((oop)OrderAccess::load_ptr_acquire(obj_at_addr(which)));
233 // check that the klass is still unresolved.
234 assert(tag_at(which).is_unresolved_klass(), "Corrupted constant pool");
235 return s;
236 }
237
238 // RedefineClasses() API support:
239 symbolOop klass_at_noresolve(int which) { return klass_name_at(which); }
240
241 jint int_at(int which) {
242 assert(tag_at(which).is_int(), "Corrupted constant pool");
243 return *int_at_addr(which);
244 }
245
246 jlong long_at(int which) {
247 assert(tag_at(which).is_long(), "Corrupted constant pool");
248 // return *long_at_addr(which);
249 u8 tmp = Bytes::get_native_u8((address)&base()[which]);
250 return *((jlong*)&tmp);
251 }
252
253 jfloat float_at(int which) {
254 assert(tag_at(which).is_float(), "Corrupted constant pool");
255 return *float_at_addr(which);
256 }
257
258 jdouble double_at(int which) {
259 assert(tag_at(which).is_double(), "Corrupted constant pool");
260 u8 tmp = Bytes::get_native_u8((address)&base()[which]);
261 return *((jdouble*)&tmp);
262 }
263
264 symbolOop symbol_at(int which) {
265 assert(tag_at(which).is_utf8(), "Corrupted constant pool");
266 return symbolOop(*obj_at_addr(which));
267 }
268
269 oop string_at(int which, TRAPS) {
270 constantPoolHandle h_this(THREAD, this);
271 return string_at_impl(h_this, which, CHECK_NULL);
272 }
273
274 // only called when we are sure a string entry is already resolved (via an
275 // earlier string_at call.
276 oop resolved_string_at(int which) {
277 assert(tag_at(which).is_string(), "Corrupted constant pool");
278 // Must do an acquire here in case another thread resolved the klass
279 // behind our back, lest we later load stale values thru the oop.
280 return (oop)OrderAccess::load_ptr_acquire(obj_at_addr(which));
281 }
282
283 // This method should only be used with a cpool lock or during parsing or gc
284 symbolOop unresolved_string_at(int which) { // Temporary until actual use
285 symbolOop s = symbolOop((oop)OrderAccess::load_ptr_acquire(obj_at_addr(which)));
286 // check that the string is still unresolved.
287 assert(tag_at(which).is_unresolved_string(), "Corrupted constant pool");
288 return s;
289 }
290
291 // Returns an UTF8 for a CONSTANT_String entry at a given index.
292 // UTF8 char* representation was chosen to avoid conversion of
293 // java_lang_Strings at resolved entries into symbolOops
294 // or vice versa.
295 char* string_at_noresolve(int which);
296
297 jint name_and_type_at(int which) {
298 assert(tag_at(which).is_name_and_type(), "Corrupted constant pool");
299 return *int_at_addr(which);
300 }
301
302 // The following methods (klass_ref_at, klass_ref_at_noresolve, name_ref_at,
303 // signature_ref_at, klass_ref_index_at, name_and_type_ref_index_at,
304 // name_ref_index_at, signature_ref_index_at) all expect constant pool indices
305 // from the bytecodes to be passed in, which are actually potentially byte-swapped
306 // contstant pool cache indices. See field_or_method_at.
307
308 // Lookup for entries consisting of (klass_index, name_and_type index)
309 klassOop klass_ref_at(int which, TRAPS);
310 symbolOop klass_ref_at_noresolve(int which);
311 symbolOop name_ref_at(int which);
312 symbolOop signature_ref_at(int which); // the type descriptor
313
314 int klass_ref_index_at(int which);
315 int name_and_type_ref_index_at(int which);
316
317 // Lookup for entries consisting of (name_index, signature_index)
318 int name_ref_index_at(int which);
319 int signature_ref_index_at(int which);
320
321 BasicType basic_type_for_signature_at(int which);
322
323 // Resolve string constants (to prevent allocation during compilation)
324 void resolve_string_constants(TRAPS) {
325 constantPoolHandle h_this(THREAD, this);
326 resolve_string_constants_impl(h_this, CHECK);
327 }
328
329 // Klass name matches name at offset
330 bool klass_name_at_matches(instanceKlassHandle k, int which);
331
332 // Sizing
333 static int header_size() { return sizeof(constantPoolOopDesc)/HeapWordSize; }
334 static int object_size(int length) { return align_object_size(header_size() + length); }
335 int object_size() { return object_size(length()); }
336
337 friend class constantPoolKlass;
338 friend class ClassFileParser;
339 friend class SystemDictionary;
340
341 // Used by compiler to prevent classloading.
342 static klassOop klass_at_if_loaded (constantPoolHandle this_oop, int which);
343 static klassOop klass_ref_at_if_loaded (constantPoolHandle this_oop, int which);
344 // Same as above - but does LinkResolving.
345 static klassOop klass_ref_at_if_loaded_check(constantPoolHandle this_oop, int which, TRAPS);
346
347 // Routines currently used for annotations (only called by jvm.cpp) but which might be used in the
348 // future by other Java code. These take constant pool indices rather than possibly-byte-swapped
349 // constant pool cache indices as do the peer methods above.
350 symbolOop uncached_name_ref_at(int which);
351 symbolOop uncached_signature_ref_at(int which);
352 int uncached_klass_ref_index_at(int which);
353 int uncached_name_and_type_ref_index_at(int which);
354
355 // Sharing
356 int pre_resolve_shared_klasses(TRAPS);
357 void shared_symbols_iterate(OopClosure* closure0);
358 void shared_tags_iterate(OopClosure* closure0);
359 void shared_strings_iterate(OopClosure* closure0);
360
361 // Debugging
362 const char* printable_name_at(int which) PRODUCT_RETURN0;
363
364 private:
365
366 // Takes either a constant pool cache index in possibly byte-swapped
367 // byte order (which comes from the bytecodes after rewriting) or,
368 // if "uncached" is true, a vanilla constant pool index
369 jint field_or_method_at(int which, bool uncached) {
370 int i = -1;
371 if (uncached || cache() == NULL) {
372 i = which;
373 } else {
374 // change byte-ordering and go via cache
375 i = cache()->entry_at(Bytes::swap_u2(which))->constant_pool_index();
376 }
377 assert(tag_at(i).is_field_or_method(), "Corrupted constant pool");
378 return *int_at_addr(i);
379 }
380
381 // Used while constructing constant pool (only by ClassFileParser)
382 jint klass_index_at(int which) {
383 assert(tag_at(which).is_klass_index(), "Corrupted constant pool");
384 return *int_at_addr(which);
385 }
386
387 jint string_index_at(int which) {
388 assert(tag_at(which).is_string_index(), "Corrupted constant pool");
389 return *int_at_addr(which);
390 }
391
392 // Performs the LinkResolver checks
393 static void verify_constant_pool_resolve(constantPoolHandle this_oop, KlassHandle klass, TRAPS);
394
395 // Implementation of methods that needs an exposed 'this' pointer, in order to
396 // handle GC while executing the method
397 static klassOop klass_at_impl(constantPoolHandle this_oop, int which, TRAPS);
398 static oop string_at_impl(constantPoolHandle this_oop, int which, TRAPS);
399
400 // Resolve string constants (to prevent allocation during compilation)
401 static void resolve_string_constants_impl(constantPoolHandle this_oop, TRAPS);
402
403 public:
404 // Merging constantPoolOop support:
405 bool compare_entry_to(int index1, constantPoolHandle cp2, int index2, TRAPS);
406 void copy_cp_to(int start_i, int end_i, constantPoolHandle to_cp, int to_i,
407 TRAPS);
408 void copy_entry_to(int from_i, constantPoolHandle to_cp, int to_i, TRAPS);
409 int find_matching_entry(int pattern_i, constantPoolHandle search_cp, TRAPS);
410 int orig_length() const { return _orig_length; }
411 void set_orig_length(int orig_length) { _orig_length = orig_length; }
412
413
414 // JVMTI accesss - GetConstantPool, RetransformClasses, ...
415 friend class JvmtiConstantPoolReconstituter;
416
417 private:
418 jint cpool_entry_size(jint idx);
419 jint hash_entries_to(SymbolHashMap *symmap, SymbolHashMap *classmap);
420
421 // Copy cpool bytes into byte array.
422 // Returns:
423 // int > 0, count of the raw cpool bytes that have been copied
424 // 0, OutOfMemory error
425 // -1, Internal error
426 int copy_cpool_bytes(int cpool_size,
427 SymbolHashMap* tbl,
428 unsigned char *bytes);
429 };
430
431 class SymbolHashMapEntry : public CHeapObj {
432 private:
433 unsigned int _hash; // 32-bit hash for item
434 SymbolHashMapEntry* _next; // Next element in the linked list for this bucket
435 symbolOop _symbol; // 1-st part of the mapping: symbol => value
436 u2 _value; // 2-nd part of the mapping: symbol => value
437
438 public:
439 unsigned int hash() const { return _hash; }
440 void set_hash(unsigned int hash) { _hash = hash; }
441
442 SymbolHashMapEntry* next() const { return _next; }
443 void set_next(SymbolHashMapEntry* next) { _next = next; }
444
445 symbolOop symbol() const { return _symbol; }
446 void set_symbol(symbolOop sym) { _symbol = sym; }
447
448 u2 value() const { return _value; }
449 void set_value(u2 value) { _value = value; }
450
451 SymbolHashMapEntry(unsigned int hash, symbolOop symbol, u2 value)
452 : _hash(hash), _symbol(symbol), _value(value), _next(NULL) {}
453
454 }; // End SymbolHashMapEntry class
455
456
457 class SymbolHashMapBucket : public CHeapObj {
458
459 private:
460 SymbolHashMapEntry* _entry;
461
462 public:
463 SymbolHashMapEntry* entry() const { return _entry; }
464 void set_entry(SymbolHashMapEntry* entry) { _entry = entry; }
465 void clear() { _entry = NULL; }
466
467 }; // End SymbolHashMapBucket class
468
469
470 class SymbolHashMap: public CHeapObj {
471
472 private:
473 // Default number of entries in the table
474 enum SymbolHashMap_Constants {
475 _Def_HashMap_Size = 256
476 };
477
478 int _table_size;
479 SymbolHashMapBucket* _buckets;
480
481 void initialize_table(int table_size) {
482 _table_size = table_size;
483 _buckets = NEW_C_HEAP_ARRAY(SymbolHashMapBucket, table_size);
484 for (int index = 0; index < table_size; index++) {
485 _buckets[index].clear();
486 }
487 }
488
489 public:
490
491 int table_size() const { return _table_size; }
492
493 SymbolHashMap() { initialize_table(_Def_HashMap_Size); }
494 SymbolHashMap(int table_size) { initialize_table(table_size); }
495
496 // hash P(31) from Kernighan & Ritchie
497 static unsigned int compute_hash(const char* str, int len) {
498 unsigned int hash = 0;
499 while (len-- > 0) {
500 hash = 31*hash + (unsigned) *str;
501 str++;
502 }
503 return hash;
504 }
505
506 SymbolHashMapEntry* bucket(int i) {
507 return _buckets[i].entry();
508 }
509
510 void add_entry(symbolOop sym, u2 value);
511 SymbolHashMapEntry* find_entry(symbolOop sym);
512
513 u2 symbol_to_value(symbolOop sym) {
514 SymbolHashMapEntry *entry = find_entry(sym);
515 return (entry == NULL) ? 0 : entry->value();
516 }
517
518 ~SymbolHashMap() {
519 SymbolHashMapEntry* next;
520 for (int i = 0; i < _table_size; i++) {
521 for (SymbolHashMapEntry* cur = bucket(i); cur != NULL; cur = next) {
522 next = cur->next();
523 delete(cur);
524 }
525 }
526 delete _buckets;
527 }
528 }; // End SymbolHashMap class