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, false, CHECK_NULL);
272 }
273
274 bool is_pseudo_string_at(int which);
275
276 oop pseudo_string_at(int which, TRAPS) {
277 constantPoolHandle h_this(THREAD, this);
278 return string_at_impl(h_this, which, true, CHECK_NULL);
279 }
280
281 // only called when we are sure a string entry is already resolved (via an
282 // earlier string_at call.
283 oop resolved_string_at(int which) {
284 assert(tag_at(which).is_string(), "Corrupted constant pool");
285 // Must do an acquire here in case another thread resolved the klass
286 // behind our back, lest we later load stale values thru the oop.
287 return (oop)OrderAccess::load_ptr_acquire(obj_at_addr(which));
288 }
289
290 // This method should only be used with a cpool lock or during parsing or gc
291 symbolOop unresolved_string_at(int which) { // Temporary until actual use
292 symbolOop s = symbolOop((oop)OrderAccess::load_ptr_acquire(obj_at_addr(which)));
293 // check that the string is still unresolved.
294 assert(tag_at(which).is_unresolved_string(), "Corrupted constant pool");
295 return s;
296 }
297
298 // Returns an UTF8 for a CONSTANT_String entry at a given index.
299 // UTF8 char* representation was chosen to avoid conversion of
300 // java_lang_Strings at resolved entries into symbolOops
301 // or vice versa.
302 // Caller is responsible for checking for pseudo-strings.
303 char* string_at_noresolve(int which);
304
305 jint name_and_type_at(int which) {
306 assert(tag_at(which).is_name_and_type(), "Corrupted constant pool");
307 return *int_at_addr(which);
308 }
309
310 // The following methods (klass_ref_at, klass_ref_at_noresolve, name_ref_at,
311 // signature_ref_at, klass_ref_index_at, name_and_type_ref_index_at,
312 // name_ref_index_at, signature_ref_index_at) all expect constant pool indices
313 // from the bytecodes to be passed in, which are actually potentially byte-swapped
314 // contstant pool cache indices. See field_or_method_at.
315
316 // Lookup for entries consisting of (klass_index, name_and_type index)
317 klassOop klass_ref_at(int which, TRAPS);
318 symbolOop klass_ref_at_noresolve(int which);
319 symbolOop name_ref_at(int which);
320 symbolOop signature_ref_at(int which); // the type descriptor
321
322 int klass_ref_index_at(int which);
323 int name_and_type_ref_index_at(int which);
324
325 // Lookup for entries consisting of (name_index, signature_index)
326 int name_ref_index_at(int which);
327 int signature_ref_index_at(int which);
328
329 BasicType basic_type_for_signature_at(int which);
330
331 // Resolve string constants (to prevent allocation during compilation)
332 void resolve_string_constants(TRAPS) {
333 constantPoolHandle h_this(THREAD, this);
334 resolve_string_constants_impl(h_this, CHECK);
335 }
336
337 // Klass name matches name at offset
338 bool klass_name_at_matches(instanceKlassHandle k, int which);
339
340 // Sizing
341 static int header_size() { return sizeof(constantPoolOopDesc)/HeapWordSize; }
342 static int object_size(int length) { return align_object_size(header_size() + length); }
343 int object_size() { return object_size(length()); }
344
345 friend class constantPoolKlass;
346 friend class ClassFileParser;
347 friend class SystemDictionary;
348
349 // Used by compiler to prevent classloading.
350 static klassOop klass_at_if_loaded (constantPoolHandle this_oop, int which);
351 static klassOop klass_ref_at_if_loaded (constantPoolHandle this_oop, int which);
352 // Same as above - but does LinkResolving.
353 static klassOop klass_ref_at_if_loaded_check(constantPoolHandle this_oop, int which, TRAPS);
354
355 // Routines currently used for annotations (only called by jvm.cpp) but which might be used in the
356 // future by other Java code. These take constant pool indices rather than possibly-byte-swapped
357 // constant pool cache indices as do the peer methods above.
358 symbolOop uncached_name_ref_at(int which);
359 symbolOop uncached_signature_ref_at(int which);
360 int uncached_klass_ref_index_at(int which);
361 int uncached_name_and_type_ref_index_at(int which);
362
363 // Sharing
364 int pre_resolve_shared_klasses(TRAPS);
365 void shared_symbols_iterate(OopClosure* closure0);
366 void shared_tags_iterate(OopClosure* closure0);
367 void shared_strings_iterate(OopClosure* closure0);
368
369 // Debugging
370 const char* printable_name_at(int which) PRODUCT_RETURN0;
371
372 private:
373
374 // Takes either a constant pool cache index in possibly byte-swapped
375 // byte order (which comes from the bytecodes after rewriting) or,
376 // if "uncached" is true, a vanilla constant pool index
377 jint field_or_method_at(int which, bool uncached) {
378 int i = -1;
379 if (uncached || cache() == NULL) {
380 i = which;
381 } else {
382 // change byte-ordering and go via cache
383 i = cache()->entry_at(Bytes::swap_u2(which))->constant_pool_index();
384 }
385 assert(tag_at(i).is_field_or_method(), "Corrupted constant pool");
386 return *int_at_addr(i);
387 }
388
389 // Used while constructing constant pool (only by ClassFileParser)
390 jint klass_index_at(int which) {
391 assert(tag_at(which).is_klass_index(), "Corrupted constant pool");
392 return *int_at_addr(which);
393 }
394
395 jint string_index_at(int which) {
396 assert(tag_at(which).is_string_index(), "Corrupted constant pool");
397 return *int_at_addr(which);
398 }
399
400 // Performs the LinkResolver checks
401 static void verify_constant_pool_resolve(constantPoolHandle this_oop, KlassHandle klass, TRAPS);
402
403 // Implementation of methods that needs an exposed 'this' pointer, in order to
404 // handle GC while executing the method
405 static klassOop klass_at_impl(constantPoolHandle this_oop, int which, TRAPS);
406 static oop string_at_impl(constantPoolHandle this_oop, int which, bool pseudo_ok, TRAPS);
407
408 // Resolve string constants (to prevent allocation during compilation)
409 static void resolve_string_constants_impl(constantPoolHandle this_oop, TRAPS);
410
411 public:
412 // Merging constantPoolOop support:
413 bool compare_entry_to(int index1, constantPoolHandle cp2, int index2, TRAPS);
414 void copy_cp_to(int start_i, int end_i, constantPoolHandle to_cp, int to_i,
415 TRAPS);
416 void copy_entry_to(int from_i, constantPoolHandle to_cp, int to_i, TRAPS);
417 int find_matching_entry(int pattern_i, constantPoolHandle search_cp, TRAPS);
418 int orig_length() const { return _orig_length; }
419 void set_orig_length(int orig_length) { _orig_length = orig_length; }
420
421
422 // JVMTI accesss - GetConstantPool, RetransformClasses, ...
423 friend class JvmtiConstantPoolReconstituter;
424
425 private:
426 jint cpool_entry_size(jint idx);
427 jint hash_entries_to(SymbolHashMap *symmap, SymbolHashMap *classmap);
428
429 // Copy cpool bytes into byte array.
430 // Returns:
431 // int > 0, count of the raw cpool bytes that have been copied
432 // 0, OutOfMemory error
433 // -1, Internal error
434 int copy_cpool_bytes(int cpool_size,
435 SymbolHashMap* tbl,
436 unsigned char *bytes);
437 };
438
439 class SymbolHashMapEntry : public CHeapObj {
440 private:
441 unsigned int _hash; // 32-bit hash for item
442 SymbolHashMapEntry* _next; // Next element in the linked list for this bucket
443 symbolOop _symbol; // 1-st part of the mapping: symbol => value
444 u2 _value; // 2-nd part of the mapping: symbol => value
445
446 public:
447 unsigned int hash() const { return _hash; }
448 void set_hash(unsigned int hash) { _hash = hash; }
449
450 SymbolHashMapEntry* next() const { return _next; }
451 void set_next(SymbolHashMapEntry* next) { _next = next; }
452
453 symbolOop symbol() const { return _symbol; }
454 void set_symbol(symbolOop sym) { _symbol = sym; }
455
456 u2 value() const { return _value; }
457 void set_value(u2 value) { _value = value; }
458
459 SymbolHashMapEntry(unsigned int hash, symbolOop symbol, u2 value)
460 : _hash(hash), _symbol(symbol), _value(value), _next(NULL) {}
461
462 }; // End SymbolHashMapEntry class
463
464
465 class SymbolHashMapBucket : public CHeapObj {
466
467 private:
468 SymbolHashMapEntry* _entry;
469
470 public:
471 SymbolHashMapEntry* entry() const { return _entry; }
472 void set_entry(SymbolHashMapEntry* entry) { _entry = entry; }
473 void clear() { _entry = NULL; }
474
475 }; // End SymbolHashMapBucket class
476
477
478 class SymbolHashMap: public CHeapObj {
479
480 private:
481 // Default number of entries in the table
482 enum SymbolHashMap_Constants {
483 _Def_HashMap_Size = 256
484 };
485
486 int _table_size;
487 SymbolHashMapBucket* _buckets;
488
489 void initialize_table(int table_size) {
490 _table_size = table_size;
491 _buckets = NEW_C_HEAP_ARRAY(SymbolHashMapBucket, table_size);
492 for (int index = 0; index < table_size; index++) {
493 _buckets[index].clear();
494 }
495 }
496
497 public:
498
499 int table_size() const { return _table_size; }
500
501 SymbolHashMap() { initialize_table(_Def_HashMap_Size); }
502 SymbolHashMap(int table_size) { initialize_table(table_size); }
503
504 // hash P(31) from Kernighan & Ritchie
505 static unsigned int compute_hash(const char* str, int len) {
506 unsigned int hash = 0;
507 while (len-- > 0) {
508 hash = 31*hash + (unsigned) *str;
509 str++;
510 }
511 return hash;
512 }
513
514 SymbolHashMapEntry* bucket(int i) {
515 return _buckets[i].entry();
516 }
517
518 void add_entry(symbolOop sym, u2 value);
519 SymbolHashMapEntry* find_entry(symbolOop sym);
520
521 u2 symbol_to_value(symbolOop sym) {
522 SymbolHashMapEntry *entry = find_entry(sym);
523 return (entry == NULL) ? 0 : entry->value();
524 }
525
526 ~SymbolHashMap() {
527 SymbolHashMapEntry* next;
528 for (int i = 0; i < _table_size; i++) {
529 for (SymbolHashMapEntry* cur = bucket(i); cur != NULL; cur = next) {
530 next = cur->next();
531 delete(cur);
532 }
533 }
534 delete _buckets;
535 }
536 }; // End SymbolHashMap class