1 /*
2 * Copyright (c) 1997, 2010, 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.
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20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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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 oopDesc {
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 int _flags; // a few header bits to describe contents for GC
45 int _length; // number of elements in the array
46 volatile bool _is_conc_safe; // if true, safe for concurrent
47 // GC processing
48 // only set to non-zero if constant pool is merged by RedefineClasses
49 int _orig_length;
50
51 void set_tags(typeArrayOop tags) { oop_store_without_check((oop*)&_tags, tags); }
52 void tag_at_put(int which, jbyte t) { tags()->byte_at_put(which, t); }
53 void release_tag_at_put(int which, jbyte t) { tags()->release_byte_at_put(which, t); }
54
55 enum FlagBit {
56 FB_has_invokedynamic = 1,
57 FB_has_pseudo_string = 2
58 };
59
60 int flags() const { return _flags; }
61 void set_flags(int f) { _flags = f; }
62 bool flag_at(FlagBit fb) const { return (_flags & (1 << (int)fb)) != 0; }
63 void set_flag_at(FlagBit fb);
64 // no clear_flag_at function; they only increase
65
66 private:
67 intptr_t* base() const { return (intptr_t*) (((char*) this) + sizeof(constantPoolOopDesc)); }
68 oop* tags_addr() { return (oop*)&_tags; }
69 oop* cache_addr() { return (oop*)&_cache; }
70
71 oop* obj_at_addr(int which) const {
72 assert(is_within_bounds(which), "index out of bounds");
73 return (oop*) &base()[which];
74 }
75
76 jint* int_at_addr(int which) const {
77 assert(is_within_bounds(which), "index out of bounds");
78 return (jint*) &base()[which];
79 }
80
81 jlong* long_at_addr(int which) const {
82 assert(is_within_bounds(which), "index out of bounds");
83 return (jlong*) &base()[which];
84 }
85
86 jfloat* float_at_addr(int which) const {
87 assert(is_within_bounds(which), "index out of bounds");
88 return (jfloat*) &base()[which];
89 }
90
91 jdouble* double_at_addr(int which) const {
92 assert(is_within_bounds(which), "index out of bounds");
93 return (jdouble*) &base()[which];
94 }
95
96 public:
97 typeArrayOop tags() const { return _tags; }
98
99 bool has_pseudo_string() const { return flag_at(FB_has_pseudo_string); }
100 bool has_invokedynamic() const { return flag_at(FB_has_invokedynamic); }
101 void set_pseudo_string() { set_flag_at(FB_has_pseudo_string); }
102 void set_invokedynamic() { set_flag_at(FB_has_invokedynamic); }
103
104 // Klass holding pool
105 klassOop pool_holder() const { return _pool_holder; }
106 void set_pool_holder(klassOop k) { oop_store_without_check((oop*)&_pool_holder, (oop) k); }
107 oop* pool_holder_addr() { return (oop*)&_pool_holder; }
108
109 // Interpreter runtime support
110 constantPoolCacheOop cache() const { return _cache; }
111 void set_cache(constantPoolCacheOop cache){ oop_store((oop*)&_cache, cache); }
112
113 // Assembly code support
114 static int tags_offset_in_bytes() { return offset_of(constantPoolOopDesc, _tags); }
115 static int cache_offset_in_bytes() { return offset_of(constantPoolOopDesc, _cache); }
116 static int pool_holder_offset_in_bytes() { return offset_of(constantPoolOopDesc, _pool_holder); }
117
118 // Storing constants
119
120 void klass_at_put(int which, klassOop k) {
121 oop_store_without_check((volatile oop *)obj_at_addr(which), oop(k));
122 // The interpreter assumes when the tag is stored, the klass is resolved
123 // and the klassOop is a klass rather than a symbolOop, so we need
124 // hardware store ordering here.
125 release_tag_at_put(which, JVM_CONSTANT_Class);
126 if (UseConcMarkSweepGC) {
127 // In case the earlier card-mark was consumed by a concurrent
128 // marking thread before the tag was updated, redirty the card.
129 oop_store_without_check((volatile oop *)obj_at_addr(which), oop(k));
130 }
131 }
132
133 // For temporary use while constructing constant pool
134 void klass_index_at_put(int which, int name_index) {
135 tag_at_put(which, JVM_CONSTANT_ClassIndex);
136 *int_at_addr(which) = name_index;
137 }
138
139 // Temporary until actual use
140 void unresolved_klass_at_put(int which, symbolOop s) {
141 // Overwrite the old index with a GC friendly value so
142 // that if GC looks during the transition it won't try
143 // to treat a small integer as oop.
144 *obj_at_addr(which) = NULL;
145 release_tag_at_put(which, JVM_CONSTANT_UnresolvedClass);
146 oop_store_without_check(obj_at_addr(which), oop(s));
147 }
148
149 void method_handle_index_at_put(int which, int ref_kind, int ref_index) {
150 tag_at_put(which, JVM_CONSTANT_MethodHandle);
151 *int_at_addr(which) = ((jint) ref_index<<16) | ref_kind;
152 }
153
154 void method_type_index_at_put(int which, int ref_index) {
155 tag_at_put(which, JVM_CONSTANT_MethodType);
156 *int_at_addr(which) = ref_index;
157 }
158
159 void invoke_dynamic_at_put(int which, int bootstrap_method_index, int name_and_type_index) {
160 tag_at_put(which, JVM_CONSTANT_InvokeDynamic);
161 *int_at_addr(which) = ((jint) name_and_type_index<<16) | bootstrap_method_index;
162 }
163
164 // Temporary until actual use
165 void unresolved_string_at_put(int which, symbolOop s) {
166 *obj_at_addr(which) = NULL;
167 release_tag_at_put(which, JVM_CONSTANT_UnresolvedString);
168 oop_store_without_check(obj_at_addr(which), oop(s));
169 }
170
171 void int_at_put(int which, jint i) {
172 tag_at_put(which, JVM_CONSTANT_Integer);
173 *int_at_addr(which) = i;
174 }
175
176 void long_at_put(int which, jlong l) {
177 tag_at_put(which, JVM_CONSTANT_Long);
178 // *long_at_addr(which) = l;
179 Bytes::put_native_u8((address)long_at_addr(which), *((u8*) &l));
180 }
181
182 void float_at_put(int which, jfloat f) {
183 tag_at_put(which, JVM_CONSTANT_Float);
184 *float_at_addr(which) = f;
185 }
186
187 void double_at_put(int which, jdouble d) {
188 tag_at_put(which, JVM_CONSTANT_Double);
189 // *double_at_addr(which) = d;
190 // u8 temp = *(u8*) &d;
191 Bytes::put_native_u8((address) double_at_addr(which), *((u8*) &d));
192 }
193
194 void symbol_at_put(int which, symbolOop s) {
195 tag_at_put(which, JVM_CONSTANT_Utf8);
196 oop_store_without_check(obj_at_addr(which), oop(s));
197 }
198
199 void string_at_put(int which, oop str) {
200 oop_store((volatile oop*)obj_at_addr(which), str);
201 release_tag_at_put(which, JVM_CONSTANT_String);
202 if (UseConcMarkSweepGC) {
203 // In case the earlier card-mark was consumed by a concurrent
204 // marking thread before the tag was updated, redirty the card.
205 oop_store_without_check((volatile oop *)obj_at_addr(which), str);
206 }
207 }
208
209 void object_at_put(int which, oop str) {
210 oop_store((volatile oop*) obj_at_addr(which), str);
211 release_tag_at_put(which, JVM_CONSTANT_Object);
212 if (UseConcMarkSweepGC) {
213 // In case the earlier card-mark was consumed by a concurrent
214 // marking thread before the tag was updated, redirty the card.
215 oop_store_without_check((volatile oop*) obj_at_addr(which), str);
216 }
217 }
218
219 // For temporary use while constructing constant pool
220 void string_index_at_put(int which, int string_index) {
221 tag_at_put(which, JVM_CONSTANT_StringIndex);
222 *int_at_addr(which) = string_index;
223 }
224
225 void field_at_put(int which, int class_index, int name_and_type_index) {
226 tag_at_put(which, JVM_CONSTANT_Fieldref);
227 *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index;
228 }
229
230 void method_at_put(int which, int class_index, int name_and_type_index) {
231 tag_at_put(which, JVM_CONSTANT_Methodref);
232 *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index;
233 }
234
235 void interface_method_at_put(int which, int class_index, int name_and_type_index) {
236 tag_at_put(which, JVM_CONSTANT_InterfaceMethodref);
237 *int_at_addr(which) = ((jint) name_and_type_index<<16) | class_index; // Not so nice
238 }
239
240 void name_and_type_at_put(int which, int name_index, int signature_index) {
241 tag_at_put(which, JVM_CONSTANT_NameAndType);
242 *int_at_addr(which) = ((jint) signature_index<<16) | name_index; // Not so nice
243 }
244
245 // Tag query
246
247 constantTag tag_at(int which) const { return (constantTag)tags()->byte_at_acquire(which); }
248
249 // Whether the entry is a pointer that must be GC'd.
250 bool is_pointer_entry(int which) {
251 constantTag tag = tag_at(which);
252 return tag.is_klass() ||
253 tag.is_unresolved_klass() ||
254 tag.is_symbol() ||
255 tag.is_unresolved_string() ||
256 tag.is_string() ||
257 tag.is_object();
258 }
259
260 // Fetching constants
261
262 klassOop klass_at(int which, TRAPS) {
263 constantPoolHandle h_this(THREAD, this);
264 return klass_at_impl(h_this, which, CHECK_NULL);
265 }
266
267 symbolOop klass_name_at(int which); // Returns the name, w/o resolving.
268
269 klassOop resolved_klass_at(int which) { // Used by Compiler
270 guarantee(tag_at(which).is_klass(), "Corrupted constant pool");
271 // Must do an acquire here in case another thread resolved the klass
272 // behind our back, lest we later load stale values thru the oop.
273 return klassOop((oop)OrderAccess::load_ptr_acquire(obj_at_addr(which)));
274 }
275
276 // This method should only be used with a cpool lock or during parsing or gc
277 symbolOop unresolved_klass_at(int which) { // Temporary until actual use
278 symbolOop s = symbolOop((oop)OrderAccess::load_ptr_acquire(obj_at_addr(which)));
279 // check that the klass is still unresolved.
280 assert(tag_at(which).is_unresolved_klass(), "Corrupted constant pool");
281 return s;
282 }
283
284 // RedefineClasses() API support:
285 symbolOop klass_at_noresolve(int which) { return klass_name_at(which); }
286
287 jint int_at(int which) {
288 assert(tag_at(which).is_int(), "Corrupted constant pool");
289 return *int_at_addr(which);
290 }
291
292 jlong long_at(int which) {
293 assert(tag_at(which).is_long(), "Corrupted constant pool");
294 // return *long_at_addr(which);
295 u8 tmp = Bytes::get_native_u8((address)&base()[which]);
296 return *((jlong*)&tmp);
297 }
298
299 jfloat float_at(int which) {
300 assert(tag_at(which).is_float(), "Corrupted constant pool");
301 return *float_at_addr(which);
302 }
303
304 jdouble double_at(int which) {
305 assert(tag_at(which).is_double(), "Corrupted constant pool");
306 u8 tmp = Bytes::get_native_u8((address)&base()[which]);
307 return *((jdouble*)&tmp);
308 }
309
310 symbolOop symbol_at(int which) {
311 assert(tag_at(which).is_utf8(), "Corrupted constant pool");
312 return symbolOop(*obj_at_addr(which));
313 }
314
315 oop string_at(int which, TRAPS) {
316 constantPoolHandle h_this(THREAD, this);
317 return string_at_impl(h_this, which, CHECK_NULL);
318 }
319
320 oop object_at(int which) {
321 assert(tag_at(which).is_object(), "Corrupted constant pool");
322 return *obj_at_addr(which);
323 }
324
325 // A "pseudo-string" is an non-string oop that has found is way into
326 // a String entry.
327 // Under AnonymousClasses this can happen if the user patches a live
328 // object into a CONSTANT_String entry of an anonymous class.
329 // Method oops internally created for method handles may also
330 // use pseudo-strings to link themselves to related metaobjects.
331
332 bool is_pseudo_string_at(int which);
333
334 oop pseudo_string_at(int which) {
335 assert(tag_at(which).is_string(), "Corrupted constant pool");
336 return *obj_at_addr(which);
337 }
338
339 void pseudo_string_at_put(int which, oop x) {
340 assert(AnonymousClasses, "");
341 set_pseudo_string(); // mark header
342 assert(tag_at(which).is_string() || tag_at(which).is_unresolved_string(), "Corrupted constant pool");
343 string_at_put(which, x); // this works just fine
344 }
345
346 // only called when we are sure a string entry is already resolved (via an
347 // earlier string_at call.
348 oop resolved_string_at(int which) {
349 assert(tag_at(which).is_string(), "Corrupted constant pool");
350 // Must do an acquire here in case another thread resolved the klass
351 // behind our back, lest we later load stale values thru the oop.
352 return (oop)OrderAccess::load_ptr_acquire(obj_at_addr(which));
353 }
354
355 // This method should only be used with a cpool lock or during parsing or gc
356 symbolOop unresolved_string_at(int which) { // Temporary until actual use
357 symbolOop s = symbolOop((oop)OrderAccess::load_ptr_acquire(obj_at_addr(which)));
358 // check that the string is still unresolved.
359 assert(tag_at(which).is_unresolved_string(), "Corrupted constant pool");
360 return s;
361 }
362
363 // Returns an UTF8 for a CONSTANT_String entry at a given index.
364 // UTF8 char* representation was chosen to avoid conversion of
365 // java_lang_Strings at resolved entries into symbolOops
366 // or vice versa.
367 // Caller is responsible for checking for pseudo-strings.
368 char* string_at_noresolve(int which);
369
370 jint name_and_type_at(int which) {
371 assert(tag_at(which).is_name_and_type(), "Corrupted constant pool");
372 return *int_at_addr(which);
373 }
374
375 int method_handle_ref_kind_at(int which) {
376 assert(tag_at(which).is_method_handle(), "Corrupted constant pool");
377 return extract_low_short_from_int(*int_at_addr(which)); // mask out unwanted ref_index bits
378 }
379 int method_handle_index_at(int which) {
380 assert(tag_at(which).is_method_handle(), "Corrupted constant pool");
381 return extract_high_short_from_int(*int_at_addr(which)); // shift out unwanted ref_kind bits
382 }
383 int method_type_index_at(int which) {
384 assert(tag_at(which).is_method_type(), "Corrupted constant pool");
385 return *int_at_addr(which);
386 }
387 // Derived queries:
388 symbolOop method_handle_name_ref_at(int which) {
389 int member = method_handle_index_at(which);
390 return impl_name_ref_at(member, true);
391 }
392 symbolOop method_handle_signature_ref_at(int which) {
393 int member = method_handle_index_at(which);
394 return impl_signature_ref_at(member, true);
395 }
396 int method_handle_klass_index_at(int which) {
397 int member = method_handle_index_at(which);
398 return impl_klass_ref_index_at(member, true);
399 }
400 symbolOop method_type_signature_at(int which) {
401 int sym = method_type_index_at(which);
402 return symbol_at(sym);
403 }
404 int invoke_dynamic_bootstrap_method_ref_index_at(int which) {
405 assert(tag_at(which).is_invoke_dynamic(), "Corrupted constant pool");
406 jint ref_index = *int_at_addr(which);
407 return extract_low_short_from_int(ref_index);
408 }
409 int invoke_dynamic_name_and_type_ref_index_at(int which) {
410 assert(tag_at(which).is_invoke_dynamic(), "Corrupted constant pool");
411 jint ref_index = *int_at_addr(which);
412 return extract_high_short_from_int(ref_index);
413 }
414
415 // The following methods (name/signature/klass_ref_at, klass_ref_at_noresolve,
416 // name_and_type_ref_index_at) all expect to be passed indices obtained
417 // directly from the bytecode, and extracted according to java byte order.
418 // If the indices are meant to refer to fields or methods, they are
419 // actually potentially byte-swapped, rewritten constant pool cache indices.
420 // The routine remap_instruction_operand_from_cache manages the adjustment
421 // of these values back to constant pool indices.
422
423 // There are also "uncached" versions which do not adjust the operand index; see below.
424
425 // Lookup for entries consisting of (klass_index, name_and_type index)
426 klassOop klass_ref_at(int which, TRAPS);
427 symbolOop klass_ref_at_noresolve(int which);
428 symbolOop name_ref_at(int which) { return impl_name_ref_at(which, false); }
429 symbolOop signature_ref_at(int which) { return impl_signature_ref_at(which, false); }
430
431 int klass_ref_index_at(int which) { return impl_klass_ref_index_at(which, false); }
432 int name_and_type_ref_index_at(int which) { return impl_name_and_type_ref_index_at(which, false); }
433
434 // Lookup for entries consisting of (name_index, signature_index)
435 int name_ref_index_at(int which_nt); // == low-order jshort of name_and_type_at(which_nt)
436 int signature_ref_index_at(int which_nt); // == high-order jshort of name_and_type_at(which_nt)
437
438 BasicType basic_type_for_signature_at(int which);
439
440 // Resolve string constants (to prevent allocation during compilation)
441 void resolve_string_constants(TRAPS) {
442 constantPoolHandle h_this(THREAD, this);
443 resolve_string_constants_impl(h_this, CHECK);
444 }
445
446 // Resolve late bound constants.
447 oop resolve_constant_at(int index, TRAPS) {
448 constantPoolHandle h_this(THREAD, this);
449 return resolve_constant_at_impl(h_this, index, -1, THREAD);
450 }
451
452 oop resolve_cached_constant_at(int cache_index, TRAPS) {
453 constantPoolHandle h_this(THREAD, this);
454 return resolve_constant_at_impl(h_this, -1, cache_index, THREAD);
455 }
456
457 // Klass name matches name at offset
458 bool klass_name_at_matches(instanceKlassHandle k, int which);
459
460 // Sizing
461 int length() const { return _length; }
462 void set_length(int length) { _length = length; }
463
464 // Tells whether index is within bounds.
465 bool is_within_bounds(int index) const {
466 return 0 <= index && index < length();
467 }
468
469 static int header_size() { return sizeof(constantPoolOopDesc)/HeapWordSize; }
470 static int object_size(int length) { return align_object_size(header_size() + length); }
471 int object_size() { return object_size(length()); }
472
473 bool is_conc_safe() { return _is_conc_safe; }
474 void set_is_conc_safe(bool v) { _is_conc_safe = v; }
475
476 friend class constantPoolKlass;
477 friend class ClassFileParser;
478 friend class SystemDictionary;
479
480 // Used by compiler to prevent classloading.
481 static klassOop klass_at_if_loaded (constantPoolHandle this_oop, int which);
482 static klassOop klass_ref_at_if_loaded (constantPoolHandle this_oop, int which);
483 // Same as above - but does LinkResolving.
484 static klassOop klass_ref_at_if_loaded_check(constantPoolHandle this_oop, int which, TRAPS);
485
486 // Routines currently used for annotations (only called by jvm.cpp) but which might be used in the
487 // future by other Java code. These take constant pool indices rather than possibly-byte-swapped
488 // constant pool cache indices as do the peer methods above.
489 symbolOop uncached_klass_ref_at_noresolve(int which);
490 symbolOop uncached_name_ref_at(int which) { return impl_name_ref_at(which, true); }
491 symbolOop uncached_signature_ref_at(int which) { return impl_signature_ref_at(which, true); }
492 int uncached_klass_ref_index_at(int which) { return impl_klass_ref_index_at(which, true); }
493 int uncached_name_and_type_ref_index_at(int which) { return impl_name_and_type_ref_index_at(which, true); }
494
495 // Sharing
496 int pre_resolve_shared_klasses(TRAPS);
497 void shared_symbols_iterate(OopClosure* closure0);
498 void shared_tags_iterate(OopClosure* closure0);
499 void shared_strings_iterate(OopClosure* closure0);
500
501 // Debugging
502 const char* printable_name_at(int which) PRODUCT_RETURN0;
503
504 #ifdef ASSERT
505 enum { CPCACHE_INDEX_TAG = 0x10000 }; // helps keep CP cache indices distinct from CP indices
506 #else
507 enum { CPCACHE_INDEX_TAG = 0 }; // in product mode, this zero value is a no-op
508 #endif //ASSERT
509
510 private:
511
512 symbolOop impl_name_ref_at(int which, bool uncached);
513 symbolOop impl_signature_ref_at(int which, bool uncached);
514 int impl_klass_ref_index_at(int which, bool uncached);
515 int impl_name_and_type_ref_index_at(int which, bool uncached);
516
517 int remap_instruction_operand_from_cache(int operand); // operand must be biased by CPCACHE_INDEX_TAG
518
519 // Used while constructing constant pool (only by ClassFileParser)
520 jint klass_index_at(int which) {
521 assert(tag_at(which).is_klass_index(), "Corrupted constant pool");
522 return *int_at_addr(which);
523 }
524
525 jint string_index_at(int which) {
526 assert(tag_at(which).is_string_index(), "Corrupted constant pool");
527 return *int_at_addr(which);
528 }
529
530 // Performs the LinkResolver checks
531 static void verify_constant_pool_resolve(constantPoolHandle this_oop, KlassHandle klass, TRAPS);
532
533 // Implementation of methods that needs an exposed 'this' pointer, in order to
534 // handle GC while executing the method
535 static klassOop klass_at_impl(constantPoolHandle this_oop, int which, TRAPS);
536 static oop string_at_impl(constantPoolHandle this_oop, int which, TRAPS);
537
538 // Resolve string constants (to prevent allocation during compilation)
539 static void resolve_string_constants_impl(constantPoolHandle this_oop, TRAPS);
540
541 static oop resolve_constant_at_impl(constantPoolHandle this_oop, int index, int cache_index, TRAPS);
542
543 public:
544 // Merging constantPoolOop support:
545 bool compare_entry_to(int index1, constantPoolHandle cp2, int index2, TRAPS);
546 void copy_cp_to(int start_i, int end_i, constantPoolHandle to_cp, int to_i,
547 TRAPS);
548 void copy_entry_to(int from_i, constantPoolHandle to_cp, int to_i, TRAPS);
549 int find_matching_entry(int pattern_i, constantPoolHandle search_cp, TRAPS);
550 int orig_length() const { return _orig_length; }
551 void set_orig_length(int orig_length) { _orig_length = orig_length; }
552
553
554 // JVMTI accesss - GetConstantPool, RetransformClasses, ...
555 friend class JvmtiConstantPoolReconstituter;
556
557 private:
558 jint cpool_entry_size(jint idx);
559 jint hash_entries_to(SymbolHashMap *symmap, SymbolHashMap *classmap);
560
561 // Copy cpool bytes into byte array.
562 // Returns:
563 // int > 0, count of the raw cpool bytes that have been copied
564 // 0, OutOfMemory error
565 // -1, Internal error
566 int copy_cpool_bytes(int cpool_size,
567 SymbolHashMap* tbl,
568 unsigned char *bytes);
569 };
570
571 class SymbolHashMapEntry : public CHeapObj {
572 private:
573 unsigned int _hash; // 32-bit hash for item
574 SymbolHashMapEntry* _next; // Next element in the linked list for this bucket
575 symbolOop _symbol; // 1-st part of the mapping: symbol => value
576 u2 _value; // 2-nd part of the mapping: symbol => value
577
578 public:
579 unsigned int hash() const { return _hash; }
580 void set_hash(unsigned int hash) { _hash = hash; }
581
582 SymbolHashMapEntry* next() const { return _next; }
583 void set_next(SymbolHashMapEntry* next) { _next = next; }
584
585 symbolOop symbol() const { return _symbol; }
586 void set_symbol(symbolOop sym) { _symbol = sym; }
587
588 u2 value() const { return _value; }
589 void set_value(u2 value) { _value = value; }
590
591 SymbolHashMapEntry(unsigned int hash, symbolOop symbol, u2 value)
592 : _hash(hash), _symbol(symbol), _value(value), _next(NULL) {}
593
594 }; // End SymbolHashMapEntry class
595
596
597 class SymbolHashMapBucket : public CHeapObj {
598
599 private:
600 SymbolHashMapEntry* _entry;
601
602 public:
603 SymbolHashMapEntry* entry() const { return _entry; }
604 void set_entry(SymbolHashMapEntry* entry) { _entry = entry; }
605 void clear() { _entry = NULL; }
606
607 }; // End SymbolHashMapBucket class
608
609
610 class SymbolHashMap: public CHeapObj {
611
612 private:
613 // Default number of entries in the table
614 enum SymbolHashMap_Constants {
615 _Def_HashMap_Size = 256
616 };
617
618 int _table_size;
619 SymbolHashMapBucket* _buckets;
620
621 void initialize_table(int table_size) {
622 _table_size = table_size;
623 _buckets = NEW_C_HEAP_ARRAY(SymbolHashMapBucket, table_size);
624 for (int index = 0; index < table_size; index++) {
625 _buckets[index].clear();
626 }
627 }
628
629 public:
630
631 int table_size() const { return _table_size; }
632
633 SymbolHashMap() { initialize_table(_Def_HashMap_Size); }
634 SymbolHashMap(int table_size) { initialize_table(table_size); }
635
636 // hash P(31) from Kernighan & Ritchie
637 static unsigned int compute_hash(const char* str, int len) {
638 unsigned int hash = 0;
639 while (len-- > 0) {
640 hash = 31*hash + (unsigned) *str;
641 str++;
642 }
643 return hash;
644 }
645
646 SymbolHashMapEntry* bucket(int i) {
647 return _buckets[i].entry();
648 }
649
650 void add_entry(symbolOop sym, u2 value);
651 SymbolHashMapEntry* find_entry(symbolOop sym);
652
653 u2 symbol_to_value(symbolOop sym) {
654 SymbolHashMapEntry *entry = find_entry(sym);
655 return (entry == NULL) ? 0 : entry->value();
656 }
657
658 ~SymbolHashMap() {
659 SymbolHashMapEntry* next;
660 for (int i = 0; i < _table_size; i++) {
661 for (SymbolHashMapEntry* cur = bucket(i); cur != NULL; cur = next) {
662 next = cur->next();
663 delete(cur);
664 }
665 }
666 delete _buckets;
667 }
668 }; // End SymbolHashMap class