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.
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 #include "precompiled.hpp"
26 #include "classfile/javaClasses.hpp"
27 #include "classfile/symbolTable.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "gc_interface/collectedHeap.inline.hpp"
30 #include "memory/filemap.hpp"
31 #include "memory/gcLocker.inline.hpp"
32 #include "oops/oop.inline.hpp"
33 #include "oops/oop.inline2.hpp"
34 #include "runtime/mutexLocker.hpp"
35 #include "utilities/hashtable.inline.hpp"
36
37 // --------------------------------------------------------------------------
38
39 SymbolTable* SymbolTable::_the_table = NULL;
40
41 Symbol* SymbolTable::allocate_symbol(const u1* name, int len, TRAPS) {
42 // Don't allow symbols to be created which cannot fit in a Symbol*.
43 if (len > Symbol::max_length()) {
44 THROW_MSG_0(vmSymbols::java_lang_InternalError(),
45 "name is too long to represent");
46 }
47 Symbol* sym = new (len) Symbol(name, len);
48 assert(sym != NULL, "new should call vm_exit_out_of_memory if C_HEAP is exhausted");
49 return sym;
50 }
51
52 bool SymbolTable::allocate_symbols(int names_count, const u1** names,
53 int* lengths, Symbol** syms, TRAPS) {
54 for (int i = 0; i< names_count; i++) {
55 if (lengths[i] > Symbol::max_length()) {
56 THROW_MSG_0(vmSymbols::java_lang_InternalError(),
57 "name is too long to represent");
58 }
59 }
60
61 for (int i = 0; i< names_count; i++) {
62 int len = lengths[i];
63 syms[i] = new (len) Symbol(names[i], len);
64 assert(syms[i] != NULL, "new should call vm_exit_out_of_memory if "
65 "C_HEAP is exhausted");
66 }
67 return true;
68 }
69
70 // Call function for all symbols in the symbol table.
71 void SymbolTable::symbols_do(SymbolClosure *cl) {
72 const int n = the_table()->table_size();
73 for (int i = 0; i < n; i++) {
74 for (HashtableEntry<Symbol*>* p = the_table()->bucket(i);
75 p != NULL;
76 p = p->next()) {
77 cl->do_symbol(p->literal_addr());
78 }
79 }
80 }
81
82 int SymbolTable::symbols_removed = 0;
83 int SymbolTable::symbols_counted = 0;
84
85 // Remove unreferenced symbols from the symbol table
86 // This is done late during GC. This doesn't use the hash table unlink because
87 // it assumes that the literals are oops.
88 void SymbolTable::unlink() {
89 int removed = 0;
90 int total = 0;
91 size_t memory_total = 0;
92 for (int i = 0; i < the_table()->table_size(); ++i) {
93 for (HashtableEntry<Symbol*>** p = the_table()->bucket_addr(i); *p != NULL; ) {
94 HashtableEntry<Symbol*>* entry = *p;
95 if (entry->is_shared()) {
96 break;
97 }
98 Symbol* s = entry->literal();
99 memory_total += s->object_size();
100 total++;
101 assert(s != NULL, "just checking");
102 // If reference count is zero, remove.
103 if (s->refcount() == 0) {
104 delete s;
105 removed++;
106 *p = entry->next();
107 the_table()->free_entry(entry);
108 } else {
109 p = entry->next_addr();
110 }
111 }
112 }
113 symbols_removed += removed;
114 symbols_counted += total;
115 // Exclude printing for normal PrintGCDetails because people parse
116 // this output.
117 if (PrintGCDetails && Verbose && WizardMode) {
118 gclog_or_tty->print(" [Symbols=%d size=" SIZE_FORMAT "K] ", total,
119 (memory_total*HeapWordSize)/1024);
120 }
121 }
122
123
124 // Lookup a symbol in a bucket.
125
126 Symbol* SymbolTable::lookup(int index, const char* name,
127 int len, unsigned int hash) {
128 for (HashtableEntry<Symbol*>* e = bucket(index); e != NULL; e = e->next()) {
129 if (e->hash() == hash) {
130 Symbol* sym = e->literal();
131 if (sym->equals(name, len)) {
132 // something is referencing this symbol now.
133 sym->increment_refcount();
134 return sym;
135 }
136 }
137 }
138 return NULL;
139 }
140
141
142 // We take care not to be blocking while holding the
143 // SymbolTable_lock. Otherwise, the system might deadlock, since the
144 // symboltable is used during compilation (VM_thread) The lock free
145 // synchronization is simplified by the fact that we do not delete
146 // entries in the symbol table during normal execution (only during
147 // safepoints).
148
149 Symbol* SymbolTable::lookup(const char* name, int len, TRAPS) {
150 unsigned int hashValue = hash_symbol(name, len);
151 int index = the_table()->hash_to_index(hashValue);
152
153 Symbol* s = the_table()->lookup(index, name, len, hashValue);
154
155 // Found
156 if (s != NULL) return s;
157
158 // Otherwise, add to symbol to table
159 return the_table()->basic_add(index, (u1*)name, len, hashValue, CHECK_NULL);
160 }
161
162 Symbol* SymbolTable::lookup(const Symbol* sym, int begin, int end, TRAPS) {
163 char* buffer;
164 int index, len;
165 unsigned int hashValue;
166 char* name;
167 {
168 debug_only(No_Safepoint_Verifier nsv;)
169
170 name = (char*)sym->base() + begin;
171 len = end - begin;
172 hashValue = hash_symbol(name, len);
173 index = the_table()->hash_to_index(hashValue);
174 Symbol* s = the_table()->lookup(index, name, len, hashValue);
175
176 // Found
177 if (s != NULL) return s;
178 }
179
180 // Otherwise, add to symbol to table. Copy to a C string first.
181 char stack_buf[128];
182 ResourceMark rm(THREAD);
183 if (len <= 128) {
184 buffer = stack_buf;
185 } else {
186 buffer = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, len);
187 }
188 for (int i=0; i<len; i++) {
189 buffer[i] = name[i];
190 }
191 // Make sure there is no safepoint in the code above since name can't move.
192 // We can't include the code in No_Safepoint_Verifier because of the
193 // ResourceMark.
194
195 return the_table()->basic_add(index, (u1*)buffer, len, hashValue, CHECK_NULL);
196 }
197
198 Symbol* SymbolTable::lookup_only(const char* name, int len,
199 unsigned int& hash) {
200 hash = hash_symbol(name, len);
201 int index = the_table()->hash_to_index(hash);
202
203 Symbol* s = the_table()->lookup(index, name, len, hash);
204 return s;
205 }
206
207 // Suggestion: Push unicode-based lookup all the way into the hashing
208 // and probing logic, so there is no need for convert_to_utf8 until
209 // an actual new Symbol* is created.
210 Symbol* SymbolTable::lookup_unicode(const jchar* name, int utf16_length, TRAPS) {
211 int utf8_length = UNICODE::utf8_length((jchar*) name, utf16_length);
212 char stack_buf[128];
213 if (utf8_length < (int) sizeof(stack_buf)) {
214 char* chars = stack_buf;
215 UNICODE::convert_to_utf8(name, utf16_length, chars);
216 return lookup(chars, utf8_length, THREAD);
217 } else {
218 ResourceMark rm(THREAD);
219 char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1);;
220 UNICODE::convert_to_utf8(name, utf16_length, chars);
221 return lookup(chars, utf8_length, THREAD);
222 }
223 }
224
225 Symbol* SymbolTable::lookup_only_unicode(const jchar* name, int utf16_length,
226 unsigned int& hash) {
227 int utf8_length = UNICODE::utf8_length((jchar*) name, utf16_length);
228 char stack_buf[128];
229 if (utf8_length < (int) sizeof(stack_buf)) {
230 char* chars = stack_buf;
231 UNICODE::convert_to_utf8(name, utf16_length, chars);
232 return lookup_only(chars, utf8_length, hash);
233 } else {
234 ResourceMark rm;
235 char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1);;
236 UNICODE::convert_to_utf8(name, utf16_length, chars);
237 return lookup_only(chars, utf8_length, hash);
238 }
239 }
240
241 void SymbolTable::add(constantPoolHandle cp, int names_count,
242 const char** names, int* lengths, int* cp_indices,
243 unsigned int* hashValues, TRAPS) {
244 SymbolTable* table = the_table();
245 bool added = table->basic_add(cp, names_count, names, lengths,
246 cp_indices, hashValues, CHECK);
247 if (!added) {
248 // do it the hard way
249 for (int i=0; i<names_count; i++) {
250 int index = table->hash_to_index(hashValues[i]);
251 Symbol* sym = table->basic_add(index, (u1*)names[i], lengths[i],
252 hashValues[i], CHECK);
253 cp->symbol_at_put(cp_indices[i], sym);
254 }
255 }
256 }
257
258 Symbol* SymbolTable::basic_add(int index, u1 *name, int len,
259 unsigned int hashValue, TRAPS) {
260 assert(!Universe::heap()->is_in_reserved(name) || GC_locker::is_active(),
261 "proposed name of symbol must be stable");
262
263 // We assume that lookup() has been called already, that it failed,
264 // and symbol was not found. We create the symbol here.
265 Symbol* sym = allocate_symbol(name, len, CHECK_NULL);
266
267 // Allocation must be done before grabbing the SymbolTable_lock lock
268 MutexLocker ml(SymbolTable_lock, THREAD);
269
270 assert(sym->equals((char*)name, len), "symbol must be properly initialized");
271
272 // Since look-up was done lock-free, we need to check if another
273 // thread beat us in the race to insert the symbol.
274
275 Symbol* test = lookup(index, (char*)name, len, hashValue);
276 if (test != NULL) {
277 // A race occurred and another thread introduced the symbol, this one
278 // will be dropped and collected.
279 delete sym;
280 assert(test->refcount() != 0, "lookup should have incremented the count");
281 return test;
282 }
283
284 HashtableEntry<Symbol*>* entry = new_entry(hashValue, sym);
285 sym->increment_refcount();
286 add_entry(index, entry);
287 return sym;
288 }
289
290 bool SymbolTable::basic_add(constantPoolHandle cp, int names_count,
291 const char** names, int* lengths,
292 int* cp_indices, unsigned int* hashValues,
293 TRAPS) {
294 Symbol* syms[symbol_alloc_batch_size];
295 bool allocated = allocate_symbols(names_count, (const u1**)names, lengths,
296 syms, CHECK_false);
297 if (!allocated) {
298 return false;
299 }
300
301 // Allocation must be done before grabbing the SymbolTable_lock lock
302 MutexLocker ml(SymbolTable_lock, THREAD);
303
304 for (int i=0; i<names_count; i++) {
305 assert(syms[i]->equals(names[i], lengths[i]), "symbol must be properly initialized");
306 // Since look-up was done lock-free, we need to check if another
307 // thread beat us in the race to insert the symbol.
308 int index = hash_to_index(hashValues[i]);
309 Symbol* test = lookup(index, names[i], lengths[i], hashValues[i]);
310 if (test != NULL) {
311 // A race occurred and another thread introduced the symbol, this one
312 // will be dropped and collected. Use test instead.
313 cp->symbol_at_put(cp_indices[i], test);
314 assert(test->refcount() != 0, "lookup should have incremented the count");
315 delete syms[i];
316 } else {
317 Symbol* sym = syms[i];
318 HashtableEntry<Symbol*>* entry = new_entry(hashValues[i], sym);
319 sym->increment_refcount(); // increment refcount in external hashtable
320 add_entry(index, entry);
321 cp->symbol_at_put(cp_indices[i], sym);
322 }
323 }
324
325 return true;
326 }
327
328
329 void SymbolTable::verify() {
330 for (int i = 0; i < the_table()->table_size(); ++i) {
331 HashtableEntry<Symbol*>* p = the_table()->bucket(i);
332 for ( ; p != NULL; p = p->next()) {
333 Symbol* s = (Symbol*)(p->literal());
334 guarantee(s != NULL, "symbol is NULL");
335 unsigned int h = hash_symbol((char*)s->bytes(), s->utf8_length());
336 guarantee(p->hash() == h, "broken hash in symbol table entry");
337 guarantee(the_table()->hash_to_index(h) == i,
338 "wrong index in symbol table");
339 }
340 }
341 }
342
343
344 //---------------------------------------------------------------------------
345 // Non-product code
346
347 #ifndef PRODUCT
348
349 void SymbolTable::print_histogram() {
350 MutexLocker ml(SymbolTable_lock);
351 const int results_length = 100;
352 int results[results_length];
353 int i,j;
354
355 // initialize results to zero
356 for (j = 0; j < results_length; j++) {
357 results[j] = 0;
358 }
359
360 int total = 0;
361 int max_symbols = 0;
362 int out_of_range = 0;
363 int memory_total = 0;
364 int count = 0;
365 for (i = 0; i < the_table()->table_size(); i++) {
366 HashtableEntry<Symbol*>* p = the_table()->bucket(i);
367 for ( ; p != NULL; p = p->next()) {
368 memory_total += p->literal()->object_size();
369 count++;
370 int counter = p->literal()->utf8_length();
371 total += counter;
372 if (counter < results_length) {
373 results[counter]++;
374 } else {
375 out_of_range++;
376 }
377 max_symbols = MAX2(max_symbols, counter);
378 }
379 }
380 tty->print_cr("Symbol Table:");
381 tty->print_cr("Total number of symbols %5d", count);
382 tty->print_cr("Total size in memory %5dK",
383 (memory_total*HeapWordSize)/1024);
384 tty->print_cr("Total counted %5d", symbols_counted);
385 tty->print_cr("Total removed %5d", symbols_removed);
386 if (symbols_counted > 0) {
387 tty->print_cr("Percent removed %3.2f",
388 ((float)symbols_removed/(float)symbols_counted)* 100);
389 }
390 tty->print_cr("Reference counts %5d", Symbol::_total_count);
391 tty->print_cr("Histogram of symbol length:");
392 tty->print_cr("%8s %5d", "Total ", total);
393 tty->print_cr("%8s %5d", "Maximum", max_symbols);
394 tty->print_cr("%8s %3.2f", "Average",
395 ((float) total / (float) the_table()->table_size()));
396 tty->print_cr("%s", "Histogram:");
397 tty->print_cr(" %s %29s", "Length", "Number chains that length");
398 for (i = 0; i < results_length; i++) {
399 if (results[i] > 0) {
400 tty->print_cr("%6d %10d", i, results[i]);
401 }
402 }
403 if (Verbose) {
404 int line_length = 70;
405 tty->print_cr("%s %30s", " Length", "Number chains that length");
406 for (i = 0; i < results_length; i++) {
407 if (results[i] > 0) {
408 tty->print("%4d", i);
409 for (j = 0; (j < results[i]) && (j < line_length); j++) {
410 tty->print("%1s", "*");
411 }
412 if (j == line_length) {
413 tty->print("%1s", "+");
414 }
415 tty->cr();
416 }
417 }
418 }
419 tty->print_cr(" %s %d: %d\n", "Number chains longer than",
420 results_length, out_of_range);
421 }
422
423 void SymbolTable::print() {
424 for (int i = 0; i < the_table()->table_size(); ++i) {
425 HashtableEntry<Symbol*>** p = the_table()->bucket_addr(i);
426 HashtableEntry<Symbol*>* entry = the_table()->bucket(i);
427 if (entry != NULL) {
428 while (entry != NULL) {
429 tty->print(PTR_FORMAT " ", entry->literal());
430 entry->literal()->print();
431 tty->print(" %d", entry->literal()->refcount());
432 p = entry->next_addr();
433 entry = (HashtableEntry<Symbol*>*)HashtableEntry<Symbol*>::make_ptr(*p);
434 }
435 tty->cr();
436 }
437 }
438 }
439
440 #endif // PRODUCT
441
442 // --------------------------------------------------------------------------
443
444 #ifdef ASSERT
445 class StableMemoryChecker : public StackObj {
446 enum { _bufsize = wordSize*4 };
447
448 address _region;
449 jint _size;
450 u1 _save_buf[_bufsize];
451
452 int sample(u1* save_buf) {
453 if (_size <= _bufsize) {
454 memcpy(save_buf, _region, _size);
455 return _size;
456 } else {
457 // copy head and tail
458 memcpy(&save_buf[0], _region, _bufsize/2);
459 memcpy(&save_buf[_bufsize/2], _region + _size - _bufsize/2, _bufsize/2);
460 return (_bufsize/2)*2;
461 }
462 }
463
464 public:
465 StableMemoryChecker(const void* region, jint size) {
466 _region = (address) region;
467 _size = size;
468 sample(_save_buf);
469 }
470
471 bool verify() {
472 u1 check_buf[sizeof(_save_buf)];
473 int check_size = sample(check_buf);
474 return (0 == memcmp(_save_buf, check_buf, check_size));
475 }
476
477 void set_region(const void* region) { _region = (address) region; }
478 };
479 #endif
480
481
482 // --------------------------------------------------------------------------
483
484
485 // Compute the hash value for a java.lang.String object which would
486 // contain the characters passed in. This hash value is used for at
487 // least two purposes.
488 //
489 // (a) As the hash value used by the StringTable for bucket selection
490 // and comparison (stored in the HashtableEntry structures). This
491 // is used in the String.intern() method.
492 //
493 // (b) As the hash value used by the String object itself, in
494 // String.hashCode(). This value is normally calculate in Java code
495 // in the String.hashCode method(), but is precomputed for String
496 // objects in the shared archive file.
497 //
498 // For this reason, THIS ALGORITHM MUST MATCH String.hashCode().
499
500 int StringTable::hash_string(jchar* s, int len) {
501 unsigned h = 0;
502 while (len-- > 0) {
503 h = 31*h + (unsigned) *s;
504 s++;
505 }
506 return h;
507 }
508
509
510 StringTable* StringTable::_the_table = NULL;
511
512 oop StringTable::lookup(int index, jchar* name,
513 int len, unsigned int hash) {
514 for (HashtableEntry<oop>* l = bucket(index); l != NULL; l = l->next()) {
515 if (l->hash() == hash) {
516 if (java_lang_String::equals(l->literal(), name, len)) {
517 return l->literal();
518 }
519 }
520 }
521 return NULL;
522 }
523
524
525 oop StringTable::basic_add(int index, Handle string_or_null, jchar* name,
526 int len, unsigned int hashValue, TRAPS) {
527 debug_only(StableMemoryChecker smc(name, len * sizeof(name[0])));
528 assert(!Universe::heap()->is_in_reserved(name) || GC_locker::is_active(),
529 "proposed name of symbol must be stable");
530
531 Handle string;
532 // try to reuse the string if possible
533 if (!string_or_null.is_null() && (!JavaObjectsInPerm || string_or_null()->is_perm())) {
534 string = string_or_null;
535 } else {
536 string = java_lang_String::create_tenured_from_unicode(name, len, CHECK_NULL);
537 }
538
539 // Allocation must be done before grapping the SymbolTable_lock lock
540 MutexLocker ml(StringTable_lock, THREAD);
541
542 assert(java_lang_String::equals(string(), name, len),
543 "string must be properly initialized");
544
545 // Since look-up was done lock-free, we need to check if another
546 // thread beat us in the race to insert the symbol.
547
548 oop test = lookup(index, name, len, hashValue); // calls lookup(u1*, int)
549 if (test != NULL) {
550 // Entry already added
551 return test;
552 }
553
554 HashtableEntry<oop>* entry = new_entry(hashValue, string());
555 add_entry(index, entry);
556 return string();
557 }
558
559
560 oop StringTable::lookup(Symbol* symbol) {
561 ResourceMark rm;
562 int length;
563 jchar* chars = symbol->as_unicode(length);
564 unsigned int hashValue = hash_string(chars, length);
565 int index = the_table()->hash_to_index(hashValue);
566 return the_table()->lookup(index, chars, length, hashValue);
567 }
568
569
570 oop StringTable::intern(Handle string_or_null, jchar* name,
571 int len, TRAPS) {
572 unsigned int hashValue = hash_string(name, len);
573 int index = the_table()->hash_to_index(hashValue);
574 oop string = the_table()->lookup(index, name, len, hashValue);
575
576 // Found
577 if (string != NULL) return string;
578
579 // Otherwise, add to symbol to table
580 return the_table()->basic_add(index, string_or_null, name, len,
581 hashValue, CHECK_NULL);
582 }
583
584 oop StringTable::intern(Symbol* symbol, TRAPS) {
585 if (symbol == NULL) return NULL;
586 ResourceMark rm(THREAD);
587 int length;
588 jchar* chars = symbol->as_unicode(length);
589 Handle string;
590 oop result = intern(string, chars, length, CHECK_NULL);
591 return result;
592 }
593
594
595 oop StringTable::intern(oop string, TRAPS)
596 {
597 if (string == NULL) return NULL;
598 ResourceMark rm(THREAD);
599 int length;
600 Handle h_string (THREAD, string);
601 jchar* chars = java_lang_String::as_unicode_string(string, length);
602 oop result = intern(h_string, chars, length, CHECK_NULL);
603 return result;
604 }
605
606
607 oop StringTable::intern(const char* utf8_string, TRAPS) {
608 if (utf8_string == NULL) return NULL;
609 ResourceMark rm(THREAD);
610 int length = UTF8::unicode_length(utf8_string);
611 jchar* chars = NEW_RESOURCE_ARRAY(jchar, length);
612 UTF8::convert_to_unicode(utf8_string, chars, length);
613 Handle string;
614 oop result = intern(string, chars, length, CHECK_NULL);
615 return result;
616 }
617
618 void StringTable::unlink(BoolObjectClosure* is_alive) {
619 // Readers of the table are unlocked, so we should only be removing
620 // entries at a safepoint.
621 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
622 for (int i = 0; i < the_table()->table_size(); ++i) {
623 for (HashtableEntry<oop>** p = the_table()->bucket_addr(i); *p != NULL; ) {
624 HashtableEntry<oop>* entry = *p;
625 if (entry->is_shared()) {
626 break;
627 }
628 assert(entry->literal() != NULL, "just checking");
629 if (is_alive->do_object_b(entry->literal())) {
630 p = entry->next_addr();
631 } else {
632 *p = entry->next();
633 the_table()->free_entry(entry);
634 }
635 }
636 }
637 }
638
639 void StringTable::oops_do(OopClosure* f) {
640 for (int i = 0; i < the_table()->table_size(); ++i) {
641 HashtableEntry<oop>** p = the_table()->bucket_addr(i);
642 HashtableEntry<oop>* entry = the_table()->bucket(i);
643 while (entry != NULL) {
644 f->do_oop((oop*)entry->literal_addr());
645
646 // Did the closure remove the literal from the table?
647 if (entry->literal() == NULL) {
648 assert(!entry->is_shared(), "immutable hashtable entry?");
649 *p = entry->next();
650 the_table()->free_entry(entry);
651 } else {
652 p = entry->next_addr();
653 }
654 entry = (HashtableEntry<oop>*)HashtableEntry<oop>::make_ptr(*p);
655 }
656 }
657 }
658
659 void StringTable::verify() {
660 for (int i = 0; i < the_table()->table_size(); ++i) {
661 HashtableEntry<oop>* p = the_table()->bucket(i);
662 for ( ; p != NULL; p = p->next()) {
663 oop s = p->literal();
664 guarantee(s != NULL, "interned string is NULL");
665 guarantee(s->is_perm() || !JavaObjectsInPerm, "interned string not in permspace");
666
667 int length;
668 jchar* chars = java_lang_String::as_unicode_string(s, length);
669 unsigned int h = hash_string(chars, length);
670 guarantee(p->hash() == h, "broken hash in string table entry");
671 guarantee(the_table()->hash_to_index(h) == i,
672 "wrong index in string table");
673 }
674 }
675 }