forked from ivmai/bdwgc
-
Notifications
You must be signed in to change notification settings - Fork 1
/
allchblk.c
1085 lines (963 loc) · 39.2 KB
/
allchblk.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/*
* Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
* Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
* Copyright (c) 1998-1999 by Silicon Graphics. All rights reserved.
* Copyright (c) 1999 by Hewlett-Packard Company. All rights reserved.
* Copyright (c) 2008-2022 Ivan Maidanski
*
* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
*
* Permission is hereby granted to use or copy this program
* for any purpose, provided the above notices are retained on all copies.
* Permission to modify the code and to distribute modified code is granted,
* provided the above notices are retained, and a notice that the code was
* modified is included with the above copyright notice.
*/
#include "private/gc_priv.h"
#ifdef GC_USE_ENTIRE_HEAP
int GC_use_entire_heap = TRUE;
#else
int GC_use_entire_heap = FALSE;
#endif
/* Free heap blocks are kept on one of several free lists, depending on */
/* the size of the block. Each free list is doubly linked. Adjacent */
/* free blocks are coalesced. */
/* Largest block we will allocate starting on a black listed block. */
/* Must be >= HBLKSIZE. */
#define MAX_BLACK_LIST_ALLOC (2*HBLKSIZE)
/* Sizes up to this many HBLKs each have their own free list. */
#define UNIQUE_THRESHOLD 32
/* Sizes of at least this many heap blocks are mapped to a single free */
/* list. */
#define HUGE_THRESHOLD 256
/* In between sizes map this many distinct sizes to a single bin. */
#define FL_COMPRESSION 8
#define N_HBLK_FLS ((HUGE_THRESHOLD - UNIQUE_THRESHOLD) / FL_COMPRESSION \
+ UNIQUE_THRESHOLD)
/* List of completely empty heap blocks. Linked through hb_next field */
/* of header structure associated with block. Remains externally */
/* visible as used by GNU GCJ currently. */
#ifndef GC_GCJ_SUPPORT
STATIC
#endif
struct hblk * GC_hblkfreelist[N_HBLK_FLS+1] = { 0 };
GC_API void GC_CALL GC_iterate_free_hblks(GC_walk_free_blk_fn fn,
void *client_data)
{
int i;
for (i = 0; i <= N_HBLK_FLS; ++i) {
struct hblk *h;
for (h = GC_hblkfreelist[i]; h != NULL; h = HDR(h) -> hb_next) {
fn(h, i, client_data);
}
}
}
/* Number of free bytes on each list. Remains visible to GCJ. */
#ifndef GC_GCJ_SUPPORT
STATIC
#endif
word GC_free_bytes[N_HBLK_FLS+1] = { 0 };
/* Return the largest n such that the number of free bytes on lists */
/* n .. N_HBLK_FLS is greater or equal to GC_max_large_allocd_bytes */
/* minus GC_large_allocd_bytes. If there is no such n, return 0. */
GC_INLINE size_t GC_enough_large_bytes_left(void)
{
size_t n;
word bytes = GC_large_allocd_bytes;
GC_ASSERT(GC_max_large_allocd_bytes <= GC_heapsize);
for (n = N_HBLK_FLS + 1; n > 0;) {
n--;
bytes += GC_free_bytes[n];
if (bytes >= GC_max_large_allocd_bytes) break;
}
return n;
}
/* Map a number of blocks to the appropriate large block free-list index. */
STATIC size_t GC_hblk_fl_from_blocks(size_t blocks_needed)
{
if (blocks_needed <= UNIQUE_THRESHOLD) return blocks_needed;
if (blocks_needed >= HUGE_THRESHOLD) return N_HBLK_FLS;
return (blocks_needed - UNIQUE_THRESHOLD) / FL_COMPRESSION
+ UNIQUE_THRESHOLD;
}
#define PHDR(hhdr) HDR((hhdr) -> hb_prev)
#define NHDR(hhdr) HDR((hhdr) -> hb_next)
#ifdef USE_MUNMAP
# define IS_MAPPED(hhdr) (((hhdr) -> hb_flags & WAS_UNMAPPED) == 0)
#else
# define IS_MAPPED(hhdr) TRUE
#endif /* !USE_MUNMAP */
#if !defined(NO_DEBUGGING) || defined(GC_ASSERTIONS)
static void GC_CALLBACK add_hb_sz(struct hblk *h, int i,
void *total_free_ptr)
{
UNUSED_ARG(i);
*(word *)total_free_ptr += HDR(h) -> hb_sz;
# if defined(CPPCHECK)
GC_noop1_ptr(h);
# endif
}
/* Should return the same value as GC_large_free_bytes. */
GC_INNER word GC_compute_large_free_bytes(void)
{
word total_free = 0;
GC_iterate_free_hblks(add_hb_sz, &total_free);
return total_free;
}
#endif /* !NO_DEBUGGING || GC_ASSERTIONS */
#if !defined(NO_DEBUGGING)
static void GC_CALLBACK print_hblkfreelist_item(struct hblk *h, int i,
void *prev_index_ptr)
{
hdr *hhdr = HDR(h);
# if defined(CPPCHECK)
GC_noop1_ptr(h);
# endif
if (i != *(int *)prev_index_ptr) {
GC_printf("Free list %d (total size %lu):\n",
i, (unsigned long)GC_free_bytes[i]);
*(int *)prev_index_ptr = i;
}
GC_printf("\t%p size %lu %s black listed\n",
(void *)h, (unsigned long)(hhdr -> hb_sz),
GC_is_black_listed(h, HBLKSIZE) != NULL ? "start"
: GC_is_black_listed(h, hhdr -> hb_sz) != NULL ? "partially"
: "not");
}
void GC_print_hblkfreelist(void)
{
word total;
int prev_index = -1;
GC_iterate_free_hblks(print_hblkfreelist_item, &prev_index);
GC_printf("GC_large_free_bytes: %lu\n",
(unsigned long)GC_large_free_bytes);
total = GC_compute_large_free_bytes();
if (total != GC_large_free_bytes)
GC_err_printf("GC_large_free_bytes INCONSISTENT!! Should be: %lu\n",
(unsigned long)total);
}
/* Return the free-list index on which the block described by the header */
/* appears, or -1 if it appears nowhere. */
static int free_list_index_of(const hdr *wanted)
{
int i;
for (i = 0; i <= N_HBLK_FLS; ++i) {
const struct hblk * h;
const hdr * hhdr;
for (h = GC_hblkfreelist[i]; h != NULL; h = hhdr -> hb_next) {
hhdr = HDR(h);
if (hhdr == wanted) return i;
}
}
return -1;
}
GC_API void GC_CALL GC_dump_regions(void)
{
size_t i;
for (i = 0; i < GC_n_heap_sects; ++i) {
ptr_t start = GC_heap_sects[i].hs_start;
size_t bytes = GC_heap_sects[i].hs_bytes;
ptr_t end = start + bytes;
ptr_t p;
/* Merge in contiguous sections. */
while (i+1 < GC_n_heap_sects && GC_heap_sects[i+1].hs_start == end) {
++i;
end = GC_heap_sects[i].hs_start + GC_heap_sects[i].hs_bytes;
}
GC_printf("***Section from %p to %p\n", (void *)start, (void *)end);
for (p = start; ADDR_LT(p, end); ) {
hdr *hhdr = HDR(p);
if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
GC_printf("\t%p Missing header!!(%p)\n",
(void *)p, (void *)hhdr);
p += HBLKSIZE;
continue;
}
if (HBLK_IS_FREE(hhdr)) {
int correct_index = (int)GC_hblk_fl_from_blocks(
divHBLKSZ(hhdr -> hb_sz));
int actual_index;
GC_printf("\t%p\tfree block of size 0x%lx bytes%s\n",
(void *)p, (unsigned long)(hhdr -> hb_sz),
IS_MAPPED(hhdr) ? "" : " (unmapped)");
actual_index = free_list_index_of(hhdr);
if (-1 == actual_index) {
GC_printf("\t\tBlock not on free list %d!!\n",
correct_index);
} else if (correct_index != actual_index) {
GC_printf("\t\tBlock on list %d, should be on %d!!\n",
actual_index, correct_index);
}
p += hhdr -> hb_sz;
} else {
GC_printf("\t%p\tused for blocks of size 0x%lx bytes\n",
(void *)p, (unsigned long)(hhdr -> hb_sz));
p += HBLKSIZE * OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz);
}
}
}
}
#endif /* NO_DEBUGGING */
/* Initialize hdr for a block containing the indicated size and */
/* kind of objects. Return FALSE on failure. */
static GC_bool setup_header(hdr *hhdr, struct hblk *block, size_t lb_adjusted,
int k, unsigned flags)
{
const struct obj_kind *ok;
word descr;
GC_ASSERT(I_HOLD_LOCK());
GC_ASSERT(lb_adjusted >= ALIGNMENT);
# ifndef MARK_BIT_PER_OBJ
if (lb_adjusted > MAXOBJBYTES)
flags |= LARGE_BLOCK;
# endif
ok = &GC_obj_kinds[k];
# ifdef ENABLE_DISCLAIM
if (ok -> ok_disclaim_proc)
flags |= HAS_DISCLAIM;
if (ok -> ok_mark_unconditionally)
flags |= MARK_UNCONDITIONALLY;
# endif
/* Set size, kind and mark proc fields. */
hhdr -> hb_sz = lb_adjusted;
hhdr -> hb_obj_kind = (unsigned char)k;
hhdr -> hb_flags = (unsigned char)flags;
hhdr -> hb_block = block;
descr = ok -> ok_descriptor;
# if ALIGNMENT > GC_DS_TAGS
/* An extra byte is not added in case of ignore-off-page */
/* allocated objects not smaller than HBLKSIZE. */
if (EXTRA_BYTES != 0 && (flags & IGNORE_OFF_PAGE) != 0
&& k == NORMAL && lb_adjusted >= HBLKSIZE)
descr += ALIGNMENT; /* or set to 0 */
# endif
if (ok -> ok_relocate_descr) descr += lb_adjusted;
hhdr -> hb_descr = descr;
# ifdef MARK_BIT_PER_OBJ
/* Set hb_inv_sz as portably as possible. We set it to the */
/* smallest value such that lb_adjusted * inv_sz >= 2**32. */
/* This may be more precision than necessary. */
if (lb_adjusted > MAXOBJBYTES) {
hhdr -> hb_inv_sz = LARGE_INV_SZ;
} else {
unsigned32 inv_sz;
GC_ASSERT(lb_adjusted > 1);
# if CPP_WORDSZ > 32
inv_sz = (unsigned32)(((word)1 << 32) / lb_adjusted);
if (((inv_sz * (word)lb_adjusted) >> 32) == 0) ++inv_sz;
# else
inv_sz = (((unsigned32)1 << 31) / lb_adjusted) << 1;
while ((inv_sz * lb_adjusted) > lb_adjusted)
inv_sz++;
# endif
# if (CPP_WORDSZ == 32) && defined(__GNUC__)
GC_ASSERT(((1ULL << 32) + lb_adjusted - 1) / lb_adjusted == inv_sz);
# endif
hhdr -> hb_inv_sz = inv_sz;
}
# else
{
size_t lg = BYTES_TO_GRANULES(lb_adjusted);
if (EXPECT(!GC_add_map_entry(lg), FALSE)) {
/* Make it look like a valid block. */
hhdr -> hb_sz = HBLKSIZE;
hhdr -> hb_descr = 0;
hhdr -> hb_flags |= LARGE_BLOCK;
hhdr -> hb_map = 0;
return FALSE;
}
hhdr -> hb_map = GC_obj_map[(hhdr -> hb_flags & LARGE_BLOCK) != 0 ?
0 : lg];
}
# endif
/* Clear mark bits. */
GC_clear_hdr_marks(hhdr);
hhdr -> hb_last_reclaimed = (unsigned short)GC_gc_no;
return TRUE;
}
/* Remove hhdr from the free list (it is assumed to specified by index). */
STATIC void GC_remove_from_fl_at(hdr *hhdr, size_t index)
{
GC_ASSERT(modHBLKSZ(hhdr -> hb_sz) == 0);
if (hhdr -> hb_prev == 0) {
GC_ASSERT(HDR(GC_hblkfreelist[index]) == hhdr);
GC_hblkfreelist[index] = hhdr -> hb_next;
} else {
hdr *phdr;
GET_HDR(hhdr -> hb_prev, phdr);
phdr -> hb_next = hhdr -> hb_next;
}
/* We always need index to maintain free counts. */
GC_ASSERT(GC_free_bytes[index] >= hhdr -> hb_sz);
GC_free_bytes[index] -= hhdr -> hb_sz;
if (0 != hhdr -> hb_next) {
hdr *nhdr;
GC_ASSERT(!IS_FORWARDING_ADDR_OR_NIL(NHDR(hhdr)));
GET_HDR(hhdr -> hb_next, nhdr);
nhdr -> hb_prev = hhdr -> hb_prev;
}
}
/* Remove hhdr from the appropriate free list (we assume it is on the */
/* size-appropriate free list). */
GC_INLINE void GC_remove_from_fl(hdr *hhdr)
{
GC_remove_from_fl_at(hhdr, GC_hblk_fl_from_blocks(divHBLKSZ(hhdr -> hb_sz)));
}
/* Return a pointer to the block ending just before h, if any. */
static struct hblk * get_block_ending_at(struct hblk *h)
{
struct hblk *p = h - 1;
hdr *hhdr;
GET_HDR(p, hhdr);
if (hhdr != NULL) {
return GC_find_starting_hblk(p, &hhdr);
}
p = GC_prev_block(p);
if (p != NULL) {
hhdr = HDR(p);
if ((ptr_t)p + hhdr -> hb_sz == (ptr_t)h) {
return p;
}
}
return NULL;
}
/* Return a pointer to the free block ending just before h, if any. */
STATIC struct hblk * GC_free_block_ending_at(struct hblk *h)
{
struct hblk * p = get_block_ending_at(h);
if (p /* != NULL */) { /* CPPCHECK */
const hdr *hhdr = HDR(p);
if (HBLK_IS_FREE(hhdr)) {
return p;
}
}
return 0;
}
/* Add hhdr to the appropriate free list. */
/* We maintain individual free lists sorted by address. */
STATIC void GC_add_to_fl(struct hblk *h, hdr *hhdr)
{
size_t index = GC_hblk_fl_from_blocks(divHBLKSZ(hhdr -> hb_sz));
struct hblk *second = GC_hblkfreelist[index];
# if defined(GC_ASSERTIONS) && !defined(USE_MUNMAP)
{
struct hblk *next = (struct hblk *)((ptr_t)h + hhdr -> hb_sz);
const hdr *nexthdr = HDR(next);
struct hblk *prev = GC_free_block_ending_at(h);
const hdr *prevhdr = HDR(prev);
GC_ASSERT(NULL == nexthdr || !HBLK_IS_FREE(nexthdr)
|| (GC_heapsize & SIGNB) != 0);
/* In the last case, blocks may be too large to be merged. */
GC_ASSERT(NULL == prev || !HBLK_IS_FREE(prevhdr)
|| (GC_heapsize & SIGNB) != 0);
}
# endif
GC_ASSERT(modHBLKSZ(hhdr -> hb_sz) == 0);
GC_hblkfreelist[index] = h;
GC_free_bytes[index] += hhdr -> hb_sz;
GC_ASSERT(GC_free_bytes[index] <= GC_large_free_bytes);
hhdr -> hb_next = second;
hhdr -> hb_prev = 0;
if (second /* != NULL */) { /* CPPCHECK */
hdr * second_hdr;
GET_HDR(second, second_hdr);
second_hdr -> hb_prev = h;
}
hhdr -> hb_flags |= FREE_BLK;
}
#ifdef USE_MUNMAP
#ifdef COUNT_UNMAPPED_REGIONS
/* GC_unmap_old will avoid creating more than this many unmapped regions, */
/* but an unmapped region may be split again so exceeding the limit. */
/* Return the change in number of unmapped regions if the block h swaps */
/* from its current state of mapped/unmapped to the opposite state. */
static int calc_num_unmapped_regions_delta(struct hblk *h, hdr *hhdr)
{
struct hblk * prev = get_block_ending_at(h);
struct hblk * next;
GC_bool prev_unmapped = FALSE;
GC_bool next_unmapped = FALSE;
next = GC_next_block((struct hblk *)((ptr_t)h + hhdr -> hb_sz), TRUE);
/* Ensure next is contiguous with h. */
if (next != HBLK_PAGE_ALIGNED((ptr_t)h + hhdr -> hb_sz)) {
next = NULL;
}
if (prev != NULL) {
const hdr *prevhdr = HDR(prev);
prev_unmapped = !IS_MAPPED(prevhdr);
}
if (next != NULL) {
const hdr *nexthdr = HDR(next);
next_unmapped = !IS_MAPPED(nexthdr);
}
if (prev_unmapped && next_unmapped) {
/* If h unmapped, merge two unmapped regions into one. */
/* If h remapped, split one unmapped region into two. */
return IS_MAPPED(hhdr) ? -1 : 1;
}
if (!prev_unmapped && !next_unmapped) {
/* If h unmapped, create an isolated unmapped region. */
/* If h remapped, remove it. */
return IS_MAPPED(hhdr) ? 1 : -1;
}
/* If h unmapped, merge it with previous or next unmapped region. */
/* If h remapped, reduce either previous or next unmapped region. */
/* In either way, no change to the number of unmapped regions. */
return 0;
}
#endif /* COUNT_UNMAPPED_REGIONS */
/* Update GC_num_unmapped_regions assuming the block h changes */
/* from its current state of mapped/unmapped to the opposite state. */
GC_INLINE void GC_adjust_num_unmapped(struct hblk *h, hdr *hhdr)
{
# ifdef COUNT_UNMAPPED_REGIONS
GC_num_unmapped_regions += calc_num_unmapped_regions_delta(h, hhdr);
# else
UNUSED_ARG(h);
UNUSED_ARG(hhdr);
# endif
}
/* Unmap blocks that haven't been recently touched. This is the only */
/* way blocks are ever unmapped. */
GC_INNER void GC_unmap_old(unsigned threshold)
{
size_t i;
# ifdef COUNT_UNMAPPED_REGIONS
/* Skip unmapping if we have already exceeded the soft limit. */
/* This forgoes any opportunities to merge unmapped regions though. */
if (GC_num_unmapped_regions >= GC_UNMAPPED_REGIONS_SOFT_LIMIT)
return;
# endif
for (i = 0; i <= N_HBLK_FLS; ++i) {
struct hblk * h;
hdr * hhdr;
for (h = GC_hblkfreelist[i]; 0 != h; h = hhdr -> hb_next) {
hhdr = HDR(h);
if (!IS_MAPPED(hhdr)) continue;
/* Check that the interval is not smaller than the threshold. */
/* The truncated counter value wrapping is handled correctly. */
if ((unsigned short)(GC_gc_no - hhdr -> hb_last_reclaimed)
>= (unsigned short)threshold) {
# ifdef COUNT_UNMAPPED_REGIONS
/* Continue with unmapping the block only if it will not */
/* create too many unmapped regions, or if unmapping */
/* reduces the number of regions. */
int delta = calc_num_unmapped_regions_delta(h, hhdr);
signed_word regions = GC_num_unmapped_regions + delta;
if (delta >= 0 && regions >= GC_UNMAPPED_REGIONS_SOFT_LIMIT) {
GC_COND_LOG_PRINTF("Unmapped regions limit reached!\n");
return;
}
GC_num_unmapped_regions = regions;
# endif
GC_unmap((ptr_t)h, hhdr -> hb_sz);
hhdr -> hb_flags |= WAS_UNMAPPED;
}
}
}
}
/* Merge all unmapped blocks that are adjacent to other free */
/* blocks. This may involve remapping, since all blocks are either */
/* fully mapped or fully unmapped. */
GC_INNER void GC_merge_unmapped(void)
{
size_t i;
for (i = 0; i <= N_HBLK_FLS; ++i) {
struct hblk *h = GC_hblkfreelist[i];
while (h != 0) {
struct hblk *next;
hdr *hhdr, *nexthdr;
size_t size, next_size;
GET_HDR(h, hhdr);
size = hhdr -> hb_sz;
next = (struct hblk *)((ptr_t)h + size);
GET_HDR(next, nexthdr);
/* Coalesce with successor, if possible. */
if (nexthdr != NULL && HBLK_IS_FREE(nexthdr)
&& ((size + (next_size = nexthdr -> hb_sz)) & SIZET_SIGNB) == 0
/* no overflow */) {
/* Note that we usually try to avoid adjacent free blocks */
/* that are either both mapped or both unmapped. But that */
/* isn't guaranteed to hold since we remap blocks when we */
/* split them, and don't merge at that point. It may also */
/* not hold if the merged block would be too big. */
if (IS_MAPPED(hhdr) && !IS_MAPPED(nexthdr)) {
/* Make both consistent, so that we can merge. */
if (size > next_size) {
GC_adjust_num_unmapped(next, nexthdr);
GC_remap((ptr_t)next, next_size);
} else {
GC_adjust_num_unmapped(h, hhdr);
GC_unmap((ptr_t)h, size);
GC_unmap_gap((ptr_t)h, size, (ptr_t)next, next_size);
hhdr -> hb_flags |= WAS_UNMAPPED;
}
} else if (IS_MAPPED(nexthdr) && !IS_MAPPED(hhdr)) {
if (size > next_size) {
GC_adjust_num_unmapped(next, nexthdr);
GC_unmap((ptr_t)next, next_size);
GC_unmap_gap((ptr_t)h, size, (ptr_t)next, next_size);
} else {
GC_adjust_num_unmapped(h, hhdr);
GC_remap((ptr_t)h, size);
hhdr -> hb_flags &= (unsigned char)~WAS_UNMAPPED;
hhdr -> hb_last_reclaimed = nexthdr -> hb_last_reclaimed;
}
} else if (!IS_MAPPED(hhdr) && !IS_MAPPED(nexthdr)) {
/* Unmap any gap in the middle. */
GC_unmap_gap((ptr_t)h, size, (ptr_t)next, next_size);
}
/* If they are both unmapped, we merge, but leave unmapped. */
GC_remove_from_fl_at(hhdr, i);
GC_remove_from_fl(nexthdr);
hhdr -> hb_sz += nexthdr -> hb_sz;
GC_remove_header(next);
GC_add_to_fl(h, hhdr);
/* Start over at beginning of list. */
h = GC_hblkfreelist[i];
} else /* not mergeable with successor */ {
h = hhdr -> hb_next;
}
} /* while (h != 0) ... */
} /* for ... */
}
#endif /* USE_MUNMAP */
/* Return a pointer to a block starting at h of length bytes. Memory */
/* for the block is mapped. Remove the block from its free list, and */
/* return the remainder (if any) to its appropriate free list. */
/* May fail by returning 0. The header for the returned block must */
/* be set up by the caller. If the return value is not 0, then hhdr is */
/* the header for it. */
STATIC struct hblk * GC_get_first_part(struct hblk *h, hdr *hhdr,
size_t size_needed, size_t index)
{
size_t total_size;
struct hblk * rest;
hdr * rest_hdr;
GC_ASSERT(I_HOLD_LOCK());
GC_ASSERT(modHBLKSZ(size_needed) == 0);
total_size = hhdr -> hb_sz;
GC_ASSERT(modHBLKSZ(total_size) == 0);
GC_remove_from_fl_at(hhdr, index);
if (total_size == size_needed) return h;
rest = (struct hblk *)((ptr_t)h + size_needed);
rest_hdr = GC_install_header(rest);
if (EXPECT(NULL == rest_hdr, FALSE)) {
/* FIXME: This is likely to be very bad news ... */
WARN("Header allocation failed: dropping block\n", 0);
return NULL;
}
rest_hdr -> hb_block = rest;
rest_hdr -> hb_sz = total_size - size_needed;
rest_hdr -> hb_flags = 0;
# ifdef GC_ASSERTIONS
/* Mark h not free, to avoid assertion about adjacent free blocks. */
hhdr -> hb_flags &= (unsigned char)~FREE_BLK;
# endif
GC_add_to_fl(rest, rest_hdr);
return h;
}
/* Split the block. hbp is a free block; last_hbp points at an address */
/* inside it; a new header for last_hbp is assumed to be already set */
/* up. Fix up the header of hbp to reflect the fact that it is being */
/* split, move it to the appropriate free list. last_hbp replaces hbp */
/* in the original free list. last_hdr is not completely filled in, */
/* since it is about to be allocated. It may in fact end up on the */
/* wrong free list for its size. That is not a disaster, since */
/* last_hbp is to be allocated by our caller. (Hence adding it to */
/* a free list is silly. But this path is hopefully rare enough that */
/* it does not matter. The code is cleaner this way.) */
STATIC void GC_split_block(struct hblk *hbp, hdr *hhdr, struct hblk *last_hbp,
hdr *last_hdr, size_t index /* of free list */)
{
size_t h_size = (size_t)((ptr_t)last_hbp - (ptr_t)hbp);
struct hblk *prev = hhdr -> hb_prev;
struct hblk *next = hhdr -> hb_next;
/* Replace hbp with last_hbp on its free list. */
last_hdr -> hb_prev = prev;
last_hdr -> hb_next = next;
last_hdr -> hb_sz = hhdr -> hb_sz - h_size;
last_hdr -> hb_flags = 0;
if (prev /* != NULL */) { /* CPPCHECK */
HDR(prev) -> hb_next = last_hbp;
} else {
GC_hblkfreelist[index] = last_hbp;
}
if (next /* != NULL */) {
HDR(next) -> hb_prev = last_hbp;
}
GC_ASSERT(GC_free_bytes[index] > h_size);
GC_free_bytes[index] -= h_size;
# ifdef USE_MUNMAP
hhdr -> hb_last_reclaimed = (unsigned short)GC_gc_no;
# endif
hhdr -> hb_sz = h_size;
GC_add_to_fl(hbp, hhdr);
last_hdr -> hb_flags |= FREE_BLK;
}
STATIC struct hblk *GC_allochblk_nth(size_t lb_adjusted, int k, unsigned flags,
size_t index, int may_split,
size_t align_m1);
#ifdef USE_MUNMAP
# define AVOID_SPLIT_REMAPPED 2
#endif
GC_INNER struct hblk *GC_allochblk(size_t lb_adjusted, int k,
unsigned flags /* IGNORE_OFF_PAGE or 0 */,
size_t align_m1)
{
size_t blocks, start_list;
struct hblk *result;
int may_split;
size_t split_limit; /* highest index of free list whose blocks we split */
GC_ASSERT(I_HOLD_LOCK());
GC_ASSERT((lb_adjusted & (GC_GRANULE_BYTES-1)) == 0);
blocks = OBJ_SZ_TO_BLOCKS_CHECKED(lb_adjusted);
if (EXPECT(SIZET_SAT_ADD(blocks * HBLKSIZE, align_m1)
>= (GC_SIZE_MAX >> 1), FALSE))
return NULL; /* overflow */
start_list = GC_hblk_fl_from_blocks(blocks);
/* Try for an exact match first. */
result = GC_allochblk_nth(lb_adjusted, k, flags, start_list, FALSE,
align_m1);
if (result != NULL) return result;
may_split = TRUE;
if (GC_use_entire_heap || GC_dont_gc
|| GC_heapsize - GC_large_free_bytes < GC_requested_heapsize
|| GC_incremental || !GC_should_collect()) {
/* Should use more of the heap, even if it requires splitting. */
split_limit = N_HBLK_FLS;
} else if (GC_finalizer_bytes_freed > (GC_heapsize >> 4)) {
/* If we are deallocating lots of memory from finalizers, */
/* fail and collect sooner rather than later. */
split_limit = 0;
} else {
/* If we have enough large blocks left to cover any */
/* previous request for large blocks, we go ahead */
/* and split. Assuming a steady state, that should */
/* be safe. It means that we can use the full */
/* heap if we allocate only small objects. */
split_limit = GC_enough_large_bytes_left();
# ifdef USE_MUNMAP
if (split_limit > 0)
may_split = AVOID_SPLIT_REMAPPED;
# endif
}
if (start_list < UNIQUE_THRESHOLD && 0 == align_m1) {
/* No reason to try start_list again, since all blocks are exact */
/* matches. */
++start_list;
}
for (; start_list <= split_limit; ++start_list) {
result = GC_allochblk_nth(lb_adjusted, k, flags, start_list, may_split,
align_m1);
if (result != NULL) break;
}
return result;
}
/* Number of warnings suppressed so far. */
STATIC long GC_large_alloc_warn_suppressed = 0;
/* Counter of the cases when found block by GC_allochblk_nth is */
/* blacklisted completely. */
STATIC unsigned GC_drop_blacklisted_count = 0;
#define ALIGN_PAD_SZ(p, align_m1) \
(((align_m1) + 1 - (size_t)ADDR(p)) & (align_m1))
static GC_bool next_hblk_fits_better(const hdr *hhdr, size_t size_avail,
size_t size_needed, size_t align_m1)
{
const hdr *nexthdr;
size_t next_size;
size_t next_ofs;
struct hblk *next_hbp = hhdr -> hb_next;
if (NULL == next_hbp) return FALSE; /* no next block */
GET_HDR(next_hbp, nexthdr);
next_size = nexthdr -> hb_sz;
if (size_avail <= next_size) return FALSE; /* not enough size */
next_ofs = ALIGN_PAD_SZ(next_hbp, align_m1);
return next_size >= size_needed + next_ofs
&& !GC_is_black_listed(next_hbp + divHBLKSZ(next_ofs), size_needed);
}
static struct hblk *find_nonbl_hblk(struct hblk *last_hbp, size_t size_remain,
size_t eff_size_needed, size_t align_m1)
{
ptr_t search_end = PTR_ALIGN_DOWN((ptr_t)last_hbp + size_remain,
align_m1 + 1);
do {
struct hblk *next_hbp;
last_hbp += divHBLKSZ(ALIGN_PAD_SZ(last_hbp, align_m1));
next_hbp = GC_is_black_listed(last_hbp, eff_size_needed);
if (NULL == next_hbp) return last_hbp; /* not black-listed */
last_hbp = next_hbp;
} while (ADDR_GE(search_end, (ptr_t)last_hbp));
return NULL;
}
/* Allocate and drop the block in small chunks, to maximize the chance */
/* that we will recover some later. hhdr should correspond to hbp. */
static void drop_hblk_in_chunks(size_t n, struct hblk *hbp, hdr *hhdr)
{
size_t total_size = hhdr -> hb_sz;
const struct hblk *limit = hbp + divHBLKSZ(total_size);
GC_ASSERT(HDR(hbp) == hhdr);
GC_ASSERT(modHBLKSZ(total_size) == 0 && total_size > 0);
GC_large_free_bytes -= total_size;
GC_bytes_dropped += total_size;
GC_remove_from_fl_at(hhdr, n);
do {
(void)setup_header(hhdr, hbp, HBLKSIZE, PTRFREE, 0); /* cannot fail */
if (GC_debugging_started) BZERO(hbp, HBLKSIZE);
hbp++;
if (ADDR_GE(hbp, limit)) break;
hhdr = GC_install_header(hbp);
} while (EXPECT(hhdr != NULL, TRUE)); /* no header allocation failure? */
}
#if defined(MPROTECT_VDB) && defined(DONT_PROTECT_PTRFREE)
static GC_bool is_hblks_mix_in_page(struct hblk *hbp, GC_bool is_ptrfree)
{
struct hblk *h = HBLK_PAGE_ALIGNED(hbp);
size_t i, cnt = divHBLKSZ(GC_page_size);
/* Iterate over blocks in the page to check if all the */
/* occupied blocks are pointer-free if we are going to */
/* allocate a pointer-free one, and vice versa. */
for (i = 0; i < cnt; i++) {
hdr *hhdr;
GET_HDR(&h[i], hhdr);
if (NULL == hhdr) continue;
(void)GC_find_starting_hblk(&h[i], &hhdr);
if (!HBLK_IS_FREE(hhdr)) {
/* It is OK to check only the first found occupied block. */
return IS_PTRFREE(hhdr) != is_ptrfree;
}
}
return FALSE; /* all blocks are free */
}
#endif /* MPROTECT_VDB && DONT_PROTECT_PTRFREE */
/* The same as GC_allochblk, but with search restricted to the index-th */
/* free list. flags should be IGNORE_OFF_PAGE or zero; may_split */
/* indicates whether it is OK to split larger blocks; size is in bytes. */
/* If may_split is set to AVOID_SPLIT_REMAPPED, then memory remapping */
/* followed by splitting should be generally avoided. Rounded-up */
/* lb_adjusted plus align_m1 value should be less than GC_SIZE_MAX / 2. */
STATIC struct hblk *GC_allochblk_nth(size_t lb_adjusted, int k, unsigned flags,
size_t index, int may_split,
size_t align_m1)
{
struct hblk *hbp, *last_hbp;
/* The header corresponding to hbp. */
hdr *hhdr;
/* Number of bytes in requested objects. */
size_t size_needed = (lb_adjusted + HBLKSIZE-1) & ~(HBLKSIZE-1);
GC_ASSERT(I_HOLD_LOCK());
GC_ASSERT(((align_m1 + 1) & align_m1) == 0 && lb_adjusted > 0);
GC_ASSERT(0 == align_m1 || modHBLKSZ(align_m1 + 1) == 0);
retry:
/* Search for a big enough block in free list. */
for (hbp = GC_hblkfreelist[index];; hbp = hhdr -> hb_next) {
size_t size_avail; /* bytes available in this block */
size_t align_ofs;
if (hbp /* != NULL */) {
/* CPPCHECK */
} else {
return NULL;
}
GET_HDR(hbp, hhdr); /* set hhdr value */
size_avail = hhdr -> hb_sz;
if (!may_split && size_avail != size_needed) continue;
align_ofs = ALIGN_PAD_SZ(hbp, align_m1);
if (size_avail < size_needed + align_ofs)
continue; /* the block is too small */
if (size_avail != size_needed) {
/* If the next heap block is obviously better, go on. */
/* This prevents us from disassembling a single large */
/* block to get tiny blocks. */
if (next_hblk_fits_better(hhdr, size_avail, size_needed, align_m1))
continue;
}
# if defined(MPROTECT_VDB) && defined(DONT_PROTECT_PTRFREE)
/* Avoid write-protecting pointer-free blocks (only the */
/* case if page size is larger than the block size). */
GC_ASSERT(GC_page_size != 0);
if (GC_page_size != HBLKSIZE
&& (!GC_incremental /* not enabled yet */
|| GC_incremental_protection_needs() != GC_PROTECTS_NONE)
&& is_hblks_mix_in_page(hbp, k == PTRFREE))
continue;
# endif
if (IS_UNCOLLECTABLE(k)
|| (k == PTRFREE && size_needed <= MAX_BLACK_LIST_ALLOC)) {
last_hbp = hbp + divHBLKSZ(align_ofs);
break;
}
last_hbp = find_nonbl_hblk(hbp, size_avail - size_needed,
(flags & IGNORE_OFF_PAGE) != 0 ? HBLKSIZE : size_needed,
align_m1);
/* Is non-blacklisted part of enough size? */
if (last_hbp != NULL) {
# ifdef USE_MUNMAP
/* Avoid remapping followed by splitting. */
if (may_split == AVOID_SPLIT_REMAPPED && last_hbp != hbp
&& !IS_MAPPED(hhdr))
continue;
# endif
break;
}
/* The block is completely blacklisted. If so, we need to */
/* drop some such blocks, since otherwise we spend all our */
/* time traversing them if pointer-free blocks are unpopular. */
/* A dropped block will be reconsidered at next GC. */
if (size_needed == HBLKSIZE && 0 == align_m1
&& !GC_find_leak && IS_MAPPED(hhdr)
&& (++GC_drop_blacklisted_count & 3) == 0) {
const struct hblk *prev = hhdr -> hb_prev;
drop_hblk_in_chunks(index, hbp, hhdr);
if (NULL == prev) goto retry;
/* Restore hhdr to point at free block. */
hhdr = HDR(prev);
continue;
}
if (size_needed > BL_LIMIT && size_avail - size_needed > BL_LIMIT) {
/* Punt, since anything else risks unreasonable heap growth. */
if (++GC_large_alloc_warn_suppressed
>= GC_large_alloc_warn_interval) {
WARN("Repeated allocation of very large block"
" (appr. size %" WARN_PRIuPTR " KiB):\n"
"\tMay lead to memory leak and poor performance\n",
size_needed >> 10);
GC_large_alloc_warn_suppressed = 0;
}
last_hbp = hbp + divHBLKSZ(align_ofs);
break;
}
}
GC_ASSERT((ADDR(last_hbp) & align_m1) == 0);
if (last_hbp != hbp) {
hdr *last_hdr = GC_install_header(last_hbp);
if (EXPECT(NULL == last_hdr, FALSE)) return NULL;
/* Make sure it's mapped before we mangle it. */
# ifdef USE_MUNMAP
if (!IS_MAPPED(hhdr)) {
GC_adjust_num_unmapped(hbp, hhdr);
GC_remap((ptr_t)hbp, hhdr -> hb_sz);
hhdr -> hb_flags &= (unsigned char)~WAS_UNMAPPED;
}
# endif
/* Split the block at last_hbp. */
GC_split_block(hbp, hhdr, last_hbp, last_hdr, index);
/* We must now allocate last_hbp, since it may be on the */
/* wrong free list. */
hbp = last_hbp;
hhdr = last_hdr;
}
GC_ASSERT(hhdr -> hb_sz >= size_needed);
# ifdef USE_MUNMAP
if (!IS_MAPPED(hhdr)) {
GC_adjust_num_unmapped(hbp, hhdr);
GC_remap((ptr_t)hbp, hhdr -> hb_sz);
hhdr -> hb_flags &= (unsigned char)~WAS_UNMAPPED;
/* Note: This may leave adjacent, mapped free blocks. */
}
# endif
/* hbp may be on the wrong free list; the parameter index is important. */
hbp = GC_get_first_part(hbp, hhdr, size_needed, index);
if (EXPECT(NULL == hbp, FALSE)) return NULL;
/* Add it to map of valid blocks. */
if (EXPECT(!GC_install_counts(hbp, size_needed), FALSE))
return NULL; /* This leaks memory under very rare conditions. */
/* Set up the header. */
GC_ASSERT(HDR(hbp) == hhdr);
# ifdef MARK_BIT_PER_OBJ
(void)setup_header(hhdr, hbp, lb_adjusted, k, flags);
/* Result is always true, not checked to avoid a cppcheck warning. */
# else
if (EXPECT(!setup_header(hhdr, hbp, lb_adjusted, k, flags), FALSE)) {
GC_remove_counts(hbp, size_needed);
return NULL; /* ditto */
}
# endif
# ifndef GC_DISABLE_INCREMENTAL
/* Notify virtual dirty bit implementation that we are about to */
/* write. Ensure that pointer-free objects are not protected */
/* if it is avoidable. This also ensures that newly allocated */
/* blocks are treated as dirty - it is necessary since we do not */
/* protect free blocks. */
GC_ASSERT(modHBLKSZ(size_needed) == 0);
GC_remove_protection(hbp, divHBLKSZ(size_needed), IS_PTRFREE(hhdr));
# endif
/* We just successfully allocated a block. Restart count of */
/* consecutive failures. */