Thu, 05 Jun 2008 15:57:56 -0700
6711316: Open source the Garbage-First garbage collector
Summary: First mercurial integration of the code for the Garbage-First garbage collector.
Reviewed-by: apetrusenko, iveresov, jmasa, sgoldman, tonyp, ysr
1 /*
2 * Copyright 1997-2006 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 */
25 # include "incls/_precompiled.incl"
26 # include "incls/_bitMap.cpp.incl"
29 BitMap::BitMap(bm_word_t* map, idx_t size_in_bits) :
30 _map(map), _size(size_in_bits)
31 {
32 assert(sizeof(bm_word_t) == BytesPerWord, "Implementation assumption.");
33 assert(size_in_bits >= 0, "just checking");
34 }
37 BitMap::BitMap(idx_t size_in_bits, bool in_resource_area) :
38 _map(NULL), _size(0)
39 {
40 assert(sizeof(bm_word_t) == BytesPerWord, "Implementation assumption.");
41 resize(size_in_bits, in_resource_area);
42 }
45 void BitMap::verify_index(idx_t index) const {
46 assert(index < _size, "BitMap index out of bounds");
47 }
49 void BitMap::verify_range(idx_t beg_index, idx_t end_index) const {
50 #ifdef ASSERT
51 assert(beg_index <= end_index, "BitMap range error");
52 // Note that [0,0) and [size,size) are both valid ranges.
53 if (end_index != _size) verify_index(end_index);
54 #endif
55 }
57 void BitMap::resize(idx_t size_in_bits, bool in_resource_area) {
58 assert(size_in_bits >= 0, "just checking");
59 idx_t old_size_in_words = size_in_words();
60 bm_word_t* old_map = map();
62 _size = size_in_bits;
63 idx_t new_size_in_words = size_in_words();
64 if (in_resource_area) {
65 _map = NEW_RESOURCE_ARRAY(bm_word_t, new_size_in_words);
66 } else {
67 if (old_map != NULL) FREE_C_HEAP_ARRAY(bm_word_t, _map);
68 _map = NEW_C_HEAP_ARRAY(bm_word_t, new_size_in_words);
69 }
70 Copy::disjoint_words((HeapWord*)old_map, (HeapWord*) _map,
71 MIN2(old_size_in_words, new_size_in_words));
72 if (new_size_in_words > old_size_in_words) {
73 clear_range_of_words(old_size_in_words, size_in_words());
74 }
75 }
77 void BitMap::set_range_within_word(idx_t beg, idx_t end) {
78 // With a valid range (beg <= end), this test ensures that end != 0, as
79 // required by inverted_bit_mask_for_range. Also avoids an unnecessary write.
80 if (beg != end) {
81 bm_word_t mask = inverted_bit_mask_for_range(beg, end);
82 *word_addr(beg) |= ~mask;
83 }
84 }
86 void BitMap::clear_range_within_word(idx_t beg, idx_t end) {
87 // With a valid range (beg <= end), this test ensures that end != 0, as
88 // required by inverted_bit_mask_for_range. Also avoids an unnecessary write.
89 if (beg != end) {
90 bm_word_t mask = inverted_bit_mask_for_range(beg, end);
91 *word_addr(beg) &= mask;
92 }
93 }
95 void BitMap::par_put_range_within_word(idx_t beg, idx_t end, bool value) {
96 assert(value == 0 || value == 1, "0 for clear, 1 for set");
97 // With a valid range (beg <= end), this test ensures that end != 0, as
98 // required by inverted_bit_mask_for_range. Also avoids an unnecessary write.
99 if (beg != end) {
100 intptr_t* pw = (intptr_t*)word_addr(beg);
101 intptr_t w = *pw;
102 intptr_t mr = (intptr_t)inverted_bit_mask_for_range(beg, end);
103 intptr_t nw = value ? (w | ~mr) : (w & mr);
104 while (true) {
105 intptr_t res = Atomic::cmpxchg_ptr(nw, pw, w);
106 if (res == w) break;
107 w = *pw;
108 nw = value ? (w | ~mr) : (w & mr);
109 }
110 }
111 }
113 void BitMap::set_range(idx_t beg, idx_t end) {
114 verify_range(beg, end);
116 idx_t beg_full_word = word_index_round_up(beg);
117 idx_t end_full_word = word_index(end);
119 if (beg_full_word < end_full_word) {
120 // The range includes at least one full word.
121 set_range_within_word(beg, bit_index(beg_full_word));
122 set_range_of_words(beg_full_word, end_full_word);
123 set_range_within_word(bit_index(end_full_word), end);
124 } else {
125 // The range spans at most 2 partial words.
126 idx_t boundary = MIN2(bit_index(beg_full_word), end);
127 set_range_within_word(beg, boundary);
128 set_range_within_word(boundary, end);
129 }
130 }
132 void BitMap::clear_range(idx_t beg, idx_t end) {
133 verify_range(beg, end);
135 idx_t beg_full_word = word_index_round_up(beg);
136 idx_t end_full_word = word_index(end);
138 if (beg_full_word < end_full_word) {
139 // The range includes at least one full word.
140 clear_range_within_word(beg, bit_index(beg_full_word));
141 clear_range_of_words(beg_full_word, end_full_word);
142 clear_range_within_word(bit_index(end_full_word), end);
143 } else {
144 // The range spans at most 2 partial words.
145 idx_t boundary = MIN2(bit_index(beg_full_word), end);
146 clear_range_within_word(beg, boundary);
147 clear_range_within_word(boundary, end);
148 }
149 }
151 void BitMap::set_large_range(idx_t beg, idx_t end) {
152 verify_range(beg, end);
154 idx_t beg_full_word = word_index_round_up(beg);
155 idx_t end_full_word = word_index(end);
157 assert(end_full_word - beg_full_word >= 32,
158 "the range must include at least 32 bytes");
160 // The range includes at least one full word.
161 set_range_within_word(beg, bit_index(beg_full_word));
162 set_large_range_of_words(beg_full_word, end_full_word);
163 set_range_within_word(bit_index(end_full_word), end);
164 }
166 void BitMap::clear_large_range(idx_t beg, idx_t end) {
167 verify_range(beg, end);
169 idx_t beg_full_word = word_index_round_up(beg);
170 idx_t end_full_word = word_index(end);
172 assert(end_full_word - beg_full_word >= 32,
173 "the range must include at least 32 bytes");
175 // The range includes at least one full word.
176 clear_range_within_word(beg, bit_index(beg_full_word));
177 clear_large_range_of_words(beg_full_word, end_full_word);
178 clear_range_within_word(bit_index(end_full_word), end);
179 }
181 void BitMap::mostly_disjoint_range_union(BitMap* from_bitmap,
182 idx_t from_start_index,
183 idx_t to_start_index,
184 size_t word_num) {
185 // Ensure that the parameters are correct.
186 // These shouldn't be that expensive to check, hence I left them as
187 // guarantees.
188 guarantee(from_bitmap->bit_in_word(from_start_index) == 0,
189 "it should be aligned on a word boundary");
190 guarantee(bit_in_word(to_start_index) == 0,
191 "it should be aligned on a word boundary");
192 guarantee(word_num >= 2, "word_num should be at least 2");
194 intptr_t* from = (intptr_t*) from_bitmap->word_addr(from_start_index);
195 intptr_t* to = (intptr_t*) word_addr(to_start_index);
197 if (*from != 0) {
198 // if it's 0, then there's no point in doing the CAS
199 while (true) {
200 intptr_t old_value = *to;
201 intptr_t new_value = old_value | *from;
202 intptr_t res = Atomic::cmpxchg_ptr(new_value, to, old_value);
203 if (res == old_value) break;
204 }
205 }
206 ++from;
207 ++to;
209 for (size_t i = 0; i < word_num - 2; ++i) {
210 if (*from != 0) {
211 // if it's 0, then there's no point in doing the CAS
212 assert(*to == 0, "nobody else should be writing here");
213 intptr_t new_value = *from;
214 *to = new_value;
215 }
217 ++from;
218 ++to;
219 }
221 if (*from != 0) {
222 // if it's 0, then there's no point in doing the CAS
223 while (true) {
224 intptr_t old_value = *to;
225 intptr_t new_value = old_value | *from;
226 intptr_t res = Atomic::cmpxchg_ptr(new_value, to, old_value);
227 if (res == old_value) break;
228 }
229 }
231 // the -1 is because we didn't advance them after the final CAS
232 assert(from ==
233 (intptr_t*) from_bitmap->word_addr(from_start_index) + word_num - 1,
234 "invariant");
235 assert(to == (intptr_t*) word_addr(to_start_index) + word_num - 1,
236 "invariant");
237 }
239 void BitMap::at_put(idx_t offset, bool value) {
240 if (value) {
241 set_bit(offset);
242 } else {
243 clear_bit(offset);
244 }
245 }
247 // Return true to indicate that this thread changed
248 // the bit, false to indicate that someone else did.
249 // In either case, the requested bit is in the
250 // requested state some time during the period that
251 // this thread is executing this call. More importantly,
252 // if no other thread is executing an action to
253 // change the requested bit to a state other than
254 // the one that this thread is trying to set it to,
255 // then the the bit is in the expected state
256 // at exit from this method. However, rather than
257 // make such a strong assertion here, based on
258 // assuming such constrained use (which though true
259 // today, could change in the future to service some
260 // funky parallel algorithm), we encourage callers
261 // to do such verification, as and when appropriate.
262 bool BitMap::par_at_put(idx_t bit, bool value) {
263 return value ? par_set_bit(bit) : par_clear_bit(bit);
264 }
266 void BitMap::at_put_grow(idx_t offset, bool value) {
267 if (offset >= size()) {
268 resize(2 * MAX2(size(), offset));
269 }
270 at_put(offset, value);
271 }
273 void BitMap::at_put_range(idx_t start_offset, idx_t end_offset, bool value) {
274 if (value) {
275 set_range(start_offset, end_offset);
276 } else {
277 clear_range(start_offset, end_offset);
278 }
279 }
281 void BitMap::par_at_put_range(idx_t beg, idx_t end, bool value) {
282 verify_range(beg, end);
284 idx_t beg_full_word = word_index_round_up(beg);
285 idx_t end_full_word = word_index(end);
287 if (beg_full_word < end_full_word) {
288 // The range includes at least one full word.
289 par_put_range_within_word(beg, bit_index(beg_full_word), value);
290 if (value) {
291 set_range_of_words(beg_full_word, end_full_word);
292 } else {
293 clear_range_of_words(beg_full_word, end_full_word);
294 }
295 par_put_range_within_word(bit_index(end_full_word), end, value);
296 } else {
297 // The range spans at most 2 partial words.
298 idx_t boundary = MIN2(bit_index(beg_full_word), end);
299 par_put_range_within_word(beg, boundary, value);
300 par_put_range_within_word(boundary, end, value);
301 }
303 }
305 void BitMap::at_put_large_range(idx_t beg, idx_t end, bool value) {
306 if (value) {
307 set_large_range(beg, end);
308 } else {
309 clear_large_range(beg, end);
310 }
311 }
313 void BitMap::par_at_put_large_range(idx_t beg, idx_t end, bool value) {
314 verify_range(beg, end);
316 idx_t beg_full_word = word_index_round_up(beg);
317 idx_t end_full_word = word_index(end);
319 assert(end_full_word - beg_full_word >= 32,
320 "the range must include at least 32 bytes");
322 // The range includes at least one full word.
323 par_put_range_within_word(beg, bit_index(beg_full_word), value);
324 if (value) {
325 set_large_range_of_words(beg_full_word, end_full_word);
326 } else {
327 clear_large_range_of_words(beg_full_word, end_full_word);
328 }
329 par_put_range_within_word(bit_index(end_full_word), end, value);
330 }
332 bool BitMap::contains(const BitMap other) const {
333 assert(size() == other.size(), "must have same size");
334 bm_word_t* dest_map = map();
335 bm_word_t* other_map = other.map();
336 idx_t size = size_in_words();
337 for (idx_t index = 0; index < size_in_words(); index++) {
338 bm_word_t word_union = dest_map[index] | other_map[index];
339 // If this has more bits set than dest_map[index], then other is not a
340 // subset.
341 if (word_union != dest_map[index]) return false;
342 }
343 return true;
344 }
346 bool BitMap::intersects(const BitMap other) const {
347 assert(size() == other.size(), "must have same size");
348 bm_word_t* dest_map = map();
349 bm_word_t* other_map = other.map();
350 idx_t size = size_in_words();
351 for (idx_t index = 0; index < size_in_words(); index++) {
352 if ((dest_map[index] & other_map[index]) != 0) return true;
353 }
354 // Otherwise, no intersection.
355 return false;
356 }
358 void BitMap::set_union(BitMap other) {
359 assert(size() == other.size(), "must have same size");
360 bm_word_t* dest_map = map();
361 bm_word_t* other_map = other.map();
362 idx_t size = size_in_words();
363 for (idx_t index = 0; index < size_in_words(); index++) {
364 dest_map[index] = dest_map[index] | other_map[index];
365 }
366 }
369 void BitMap::set_difference(BitMap other) {
370 assert(size() == other.size(), "must have same size");
371 bm_word_t* dest_map = map();
372 bm_word_t* other_map = other.map();
373 idx_t size = size_in_words();
374 for (idx_t index = 0; index < size_in_words(); index++) {
375 dest_map[index] = dest_map[index] & ~(other_map[index]);
376 }
377 }
380 void BitMap::set_intersection(BitMap other) {
381 assert(size() == other.size(), "must have same size");
382 bm_word_t* dest_map = map();
383 bm_word_t* other_map = other.map();
384 idx_t size = size_in_words();
385 for (idx_t index = 0; index < size; index++) {
386 dest_map[index] = dest_map[index] & other_map[index];
387 }
388 }
391 void BitMap::set_intersection_at_offset(BitMap other, idx_t offset) {
392 assert(other.size() >= offset, "offset not in range");
393 assert(other.size() - offset >= size(), "other not large enough");
394 // XXX Ideally, we would remove this restriction.
395 guarantee((offset % (sizeof(bm_word_t) * BitsPerByte)) == 0,
396 "Only handle aligned cases so far.");
397 bm_word_t* dest_map = map();
398 bm_word_t* other_map = other.map();
399 idx_t offset_word_ind = word_index(offset);
400 idx_t size = size_in_words();
401 for (idx_t index = 0; index < size; index++) {
402 dest_map[index] = dest_map[index] & other_map[offset_word_ind + index];
403 }
404 }
406 bool BitMap::set_union_with_result(BitMap other) {
407 assert(size() == other.size(), "must have same size");
408 bool changed = false;
409 bm_word_t* dest_map = map();
410 bm_word_t* other_map = other.map();
411 idx_t size = size_in_words();
412 for (idx_t index = 0; index < size; index++) {
413 idx_t temp = map(index) | other_map[index];
414 changed = changed || (temp != map(index));
415 map()[index] = temp;
416 }
417 return changed;
418 }
421 bool BitMap::set_difference_with_result(BitMap other) {
422 assert(size() == other.size(), "must have same size");
423 bool changed = false;
424 bm_word_t* dest_map = map();
425 bm_word_t* other_map = other.map();
426 idx_t size = size_in_words();
427 for (idx_t index = 0; index < size; index++) {
428 bm_word_t temp = dest_map[index] & ~(other_map[index]);
429 changed = changed || (temp != dest_map[index]);
430 dest_map[index] = temp;
431 }
432 return changed;
433 }
436 bool BitMap::set_intersection_with_result(BitMap other) {
437 assert(size() == other.size(), "must have same size");
438 bool changed = false;
439 bm_word_t* dest_map = map();
440 bm_word_t* other_map = other.map();
441 idx_t size = size_in_words();
442 for (idx_t index = 0; index < size; index++) {
443 bm_word_t orig = dest_map[index];
444 bm_word_t temp = orig & other_map[index];
445 changed = changed || (temp != orig);
446 dest_map[index] = temp;
447 }
448 return changed;
449 }
452 void BitMap::set_from(BitMap other) {
453 assert(size() == other.size(), "must have same size");
454 bm_word_t* dest_map = map();
455 bm_word_t* other_map = other.map();
456 idx_t size = size_in_words();
457 for (idx_t index = 0; index < size; index++) {
458 dest_map[index] = other_map[index];
459 }
460 }
463 bool BitMap::is_same(BitMap other) {
464 assert(size() == other.size(), "must have same size");
465 bm_word_t* dest_map = map();
466 bm_word_t* other_map = other.map();
467 idx_t size = size_in_words();
468 for (idx_t index = 0; index < size; index++) {
469 if (dest_map[index] != other_map[index]) return false;
470 }
471 return true;
472 }
474 bool BitMap::is_full() const {
475 bm_word_t* word = map();
476 idx_t rest = size();
477 for (; rest >= (idx_t) BitsPerWord; rest -= BitsPerWord) {
478 if (*word != (bm_word_t) AllBits) return false;
479 word++;
480 }
481 return rest == 0 || (*word | ~right_n_bits((int)rest)) == (bm_word_t) AllBits;
482 }
485 bool BitMap::is_empty() const {
486 bm_word_t* word = map();
487 idx_t rest = size();
488 for (; rest >= (idx_t) BitsPerWord; rest -= BitsPerWord) {
489 if (*word != (bm_word_t) NoBits) return false;
490 word++;
491 }
492 return rest == 0 || (*word & right_n_bits((int)rest)) == (bm_word_t) NoBits;
493 }
495 void BitMap::clear_large() {
496 clear_large_range_of_words(0, size_in_words());
497 }
499 // Note that if the closure itself modifies the bitmap
500 // then modifications in and to the left of the _bit_ being
501 // currently sampled will not be seen. Note also that the
502 // interval [leftOffset, rightOffset) is right open.
503 bool BitMap::iterate(BitMapClosure* blk, idx_t leftOffset, idx_t rightOffset) {
504 verify_range(leftOffset, rightOffset);
506 idx_t startIndex = word_index(leftOffset);
507 idx_t endIndex = MIN2(word_index(rightOffset) + 1, size_in_words());
508 for (idx_t index = startIndex, offset = leftOffset;
509 offset < rightOffset && index < endIndex;
510 offset = (++index) << LogBitsPerWord) {
511 idx_t rest = map(index) >> (offset & (BitsPerWord - 1));
512 for (; offset < rightOffset && rest != (bm_word_t)NoBits; offset++) {
513 if (rest & 1) {
514 if (!blk->do_bit(offset)) return false;
515 // resample at each closure application
516 // (see, for instance, CMS bug 4525989)
517 rest = map(index) >> (offset & (BitsPerWord -1));
518 }
519 rest = rest >> 1;
520 }
521 }
522 return true;
523 }
525 BitMap::idx_t* BitMap::_pop_count_table = NULL;
527 void BitMap::init_pop_count_table() {
528 if (_pop_count_table == NULL) {
529 BitMap::idx_t *table = NEW_C_HEAP_ARRAY(idx_t, 256);
530 for (uint i = 0; i < 256; i++) {
531 table[i] = num_set_bits(i);
532 }
534 intptr_t res = Atomic::cmpxchg_ptr((intptr_t) table,
535 (intptr_t*) &_pop_count_table,
536 (intptr_t) NULL_WORD);
537 if (res != NULL_WORD) {
538 guarantee( _pop_count_table == (void*) res, "invariant" );
539 FREE_C_HEAP_ARRAY(bm_word_t, table);
540 }
541 }
542 }
544 BitMap::idx_t BitMap::num_set_bits(bm_word_t w) {
545 idx_t bits = 0;
547 while (w != 0) {
548 while ((w & 1) == 0) {
549 w >>= 1;
550 }
551 bits++;
552 w >>= 1;
553 }
554 return bits;
555 }
557 BitMap::idx_t BitMap::num_set_bits_from_table(unsigned char c) {
558 assert(_pop_count_table != NULL, "precondition");
559 return _pop_count_table[c];
560 }
562 BitMap::idx_t BitMap::count_one_bits() const {
563 init_pop_count_table(); // If necessary.
564 idx_t sum = 0;
565 typedef unsigned char uchar;
566 for (idx_t i = 0; i < size_in_words(); i++) {
567 bm_word_t w = map()[i];
568 for (size_t j = 0; j < sizeof(bm_word_t); j++) {
569 sum += num_set_bits_from_table(uchar(w & 255));
570 w >>= 8;
571 }
572 }
573 return sum;
574 }
577 #ifndef PRODUCT
579 void BitMap::print_on(outputStream* st) const {
580 tty->print("Bitmap(%d):", size());
581 for (idx_t index = 0; index < size(); index++) {
582 tty->print("%c", at(index) ? '1' : '0');
583 }
584 tty->cr();
585 }
587 #endif
590 BitMap2D::BitMap2D(bm_word_t* map, idx_t size_in_slots, idx_t bits_per_slot)
591 : _bits_per_slot(bits_per_slot)
592 , _map(map, size_in_slots * bits_per_slot)
593 {
594 }
597 BitMap2D::BitMap2D(idx_t size_in_slots, idx_t bits_per_slot)
598 : _bits_per_slot(bits_per_slot)
599 , _map(size_in_slots * bits_per_slot)
600 {
601 }