1 /*
2 * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
3 * Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
4 * Copyright (c) 1998-1999 by Silicon Graphics. All rights reserved.
5 * Copyright (c) 1999 by Hewlett-Packard Company. All rights reserved.
6 *
7 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
8 * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
9 *
10 * Permission is hereby granted to use or copy this program
11 * for any purpose, provided the above notices are retained on all copies.
12 * Permission to modify the code and to distribute modified code is granted,
13 * provided the above notices are retained, and a notice that the code was
14 * modified is included with the above copyright notice.
15 */
16
17 /* #define DEBUG */
18 #include <stdio.h>
19 #include "private/gc_priv.h"
20
21 GC_bool GC_use_entire_heap = 0;
22
23 /*
24 * Free heap blocks are kept on one of several free lists,
25 * depending on the size of the block. Each free list is doubly linked.
26 * Adjacent free blocks are coalesced.
27 */
28
29
30 # define MAX_BLACK_LIST_ALLOC (2*HBLKSIZE)
31 /* largest block we will allocate starting on a black */
32 /* listed block. Must be >= HBLKSIZE. */
33
34
35 # define UNIQUE_THRESHOLD 32
36 /* Sizes up to this many HBLKs each have their own free list */
37 # define HUGE_THRESHOLD 256
38 /* Sizes of at least this many heap blocks are mapped to a */
39 /* single free list. */
40 # define FL_COMPRESSION 8
41 /* In between sizes map this many distinct sizes to a single */
42 /* bin. */
43
44 # define N_HBLK_FLS (HUGE_THRESHOLD - UNIQUE_THRESHOLD)/FL_COMPRESSION \
45 + UNIQUE_THRESHOLD
46
47 struct hblk * GC_hblkfreelist[N_HBLK_FLS+1] = { 0 };
48
49 #ifndef USE_MUNMAP
50
51 word GC_free_bytes[N_HBLK_FLS+1] = { 0 };
52 /* Number of free bytes on each list. */
53
54 /* Is bytes + the number of free bytes on lists n .. N_HBLK_FLS */
55 /* > GC_max_large_allocd_bytes? */
56 # ifdef __GNUC__
57 __inline__
58 # endif
GC_enough_large_bytes_left(bytes,n)59 static GC_bool GC_enough_large_bytes_left(bytes,n)
60 word bytes;
61 int n;
62 {
63 int i;
64 for (i = N_HBLK_FLS; i >= n; --i) {
65 bytes += GC_free_bytes[i];
66 if (bytes > GC_max_large_allocd_bytes) return TRUE;
67 }
68 return FALSE;
69 }
70
71 # define INCR_FREE_BYTES(n, b) GC_free_bytes[n] += (b);
72
73 # define FREE_ASSERT(e) GC_ASSERT(e)
74
75 #else /* USE_MUNMAP */
76
77 # define INCR_FREE_BYTES(n, b)
78 # define FREE_ASSERT(e)
79
80 #endif /* USE_MUNMAP */
81
82 /* Map a number of blocks to the appropriate large block free list index. */
GC_hblk_fl_from_blocks(blocks_needed)83 int GC_hblk_fl_from_blocks(blocks_needed)
84 word blocks_needed;
85 {
86 if (blocks_needed <= UNIQUE_THRESHOLD) return blocks_needed;
87 if (blocks_needed >= HUGE_THRESHOLD) return N_HBLK_FLS;
88 return (blocks_needed - UNIQUE_THRESHOLD)/FL_COMPRESSION
89 + UNIQUE_THRESHOLD;
90
91 }
92
93 # define PHDR(hhdr) HDR(hhdr -> hb_prev)
94 # define NHDR(hhdr) HDR(hhdr -> hb_next)
95
96 # ifdef USE_MUNMAP
97 # define IS_MAPPED(hhdr) (((hhdr) -> hb_flags & WAS_UNMAPPED) == 0)
98 # else /* !USE_MMAP */
99 # define IS_MAPPED(hhdr) 1
100 # endif /* USE_MUNMAP */
101
102 # if !defined(NO_DEBUGGING)
GC_print_hblkfreelist()103 void GC_print_hblkfreelist()
104 {
105 struct hblk * h;
106 word total_free = 0;
107 hdr * hhdr;
108 word sz;
109 int i;
110
111 for (i = 0; i <= N_HBLK_FLS; ++i) {
112 h = GC_hblkfreelist[i];
113 # ifdef USE_MUNMAP
114 if (0 != h) GC_printf1("Free list %ld:\n",
115 (unsigned long)i);
116 # else
117 if (0 != h) GC_printf2("Free list %ld (Total size %ld):\n",
118 (unsigned long)i,
119 (unsigned long)GC_free_bytes[i]);
120 # endif
121 while (h != 0) {
122 hhdr = HDR(h);
123 sz = hhdr -> hb_sz;
124 GC_printf2("\t0x%lx size %lu ", (unsigned long)h, (unsigned long)sz);
125 total_free += sz;
126 if (GC_is_black_listed(h, HBLKSIZE) != 0) {
127 GC_printf0("start black listed\n");
128 } else if (GC_is_black_listed(h, hhdr -> hb_sz) != 0) {
129 GC_printf0("partially black listed\n");
130 } else {
131 GC_printf0("not black listed\n");
132 }
133 h = hhdr -> hb_next;
134 }
135 }
136 # ifndef USE_MUNMAP
137 if (total_free != GC_large_free_bytes) {
138 GC_printf1("GC_large_free_bytes = %lu (INCONSISTENT!!)\n",
139 (unsigned long) GC_large_free_bytes);
140 }
141 # endif
142 GC_printf1("Total of %lu bytes on free list\n", (unsigned long)total_free);
143 }
144
145 /* Return the free list index on which the block described by the header */
146 /* appears, or -1 if it appears nowhere. */
free_list_index_of(wanted)147 int free_list_index_of(wanted)
148 hdr * wanted;
149 {
150 struct hblk * h;
151 hdr * hhdr;
152 int i;
153
154 for (i = 0; i <= N_HBLK_FLS; ++i) {
155 h = GC_hblkfreelist[i];
156 while (h != 0) {
157 hhdr = HDR(h);
158 if (hhdr == wanted) return i;
159 h = hhdr -> hb_next;
160 }
161 }
162 return -1;
163 }
164
GC_dump_regions()165 void GC_dump_regions()
166 {
167 unsigned i;
168 ptr_t start, end;
169 ptr_t p;
170 size_t bytes;
171 hdr *hhdr;
172 for (i = 0; i < GC_n_heap_sects; ++i) {
173 start = GC_heap_sects[i].hs_start;
174 bytes = GC_heap_sects[i].hs_bytes;
175 end = start + bytes;
176 /* Merge in contiguous sections. */
177 while (i+1 < GC_n_heap_sects && GC_heap_sects[i+1].hs_start == end) {
178 ++i;
179 end = GC_heap_sects[i].hs_start + GC_heap_sects[i].hs_bytes;
180 }
181 GC_printf2("***Section from 0x%lx to 0x%lx\n", start, end);
182 for (p = start; p < end;) {
183 hhdr = HDR(p);
184 GC_printf1("\t0x%lx ", (unsigned long)p);
185 if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
186 GC_printf1("Missing header!!(%ld)\n", hhdr);
187 p += HBLKSIZE;
188 continue;
189 }
190 if (HBLK_IS_FREE(hhdr)) {
191 int correct_index = GC_hblk_fl_from_blocks(
192 divHBLKSZ(hhdr -> hb_sz));
193 int actual_index;
194
195 GC_printf1("\tfree block of size 0x%lx bytes",
196 (unsigned long)(hhdr -> hb_sz));
197 if (IS_MAPPED(hhdr)) {
198 GC_printf0("\n");
199 } else {
200 GC_printf0("(unmapped)\n");
201 }
202 actual_index = free_list_index_of(hhdr);
203 if (-1 == actual_index) {
204 GC_printf1("\t\tBlock not on free list %ld!!\n",
205 correct_index);
206 } else if (correct_index != actual_index) {
207 GC_printf2("\t\tBlock on list %ld, should be on %ld!!\n",
208 actual_index, correct_index);
209 }
210 p += hhdr -> hb_sz;
211 } else {
212 GC_printf1("\tused for blocks of size 0x%lx bytes\n",
213 (unsigned long)WORDS_TO_BYTES(hhdr -> hb_sz));
214 p += HBLKSIZE * OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz);
215 }
216 }
217 }
218 }
219
220 # endif /* NO_DEBUGGING */
221
222 /* Initialize hdr for a block containing the indicated size and */
223 /* kind of objects. */
224 /* Return FALSE on failure. */
setup_header(hhdr,sz,kind,flags)225 static GC_bool setup_header(hhdr, sz, kind, flags)
226 register hdr * hhdr;
227 word sz; /* object size in words */
228 int kind;
229 unsigned char flags;
230 {
231 register word descr;
232
233 /* Add description of valid object pointers */
234 if (!GC_add_map_entry(sz)) return(FALSE);
235 hhdr -> hb_map = GC_obj_map[sz > MAXOBJSZ? 0 : sz];
236
237 /* Set size, kind and mark proc fields */
238 hhdr -> hb_sz = sz;
239 hhdr -> hb_obj_kind = kind;
240 hhdr -> hb_flags = flags;
241 descr = GC_obj_kinds[kind].ok_descriptor;
242 if (GC_obj_kinds[kind].ok_relocate_descr) descr += WORDS_TO_BYTES(sz);
243 hhdr -> hb_descr = descr;
244
245 /* Clear mark bits */
246 GC_clear_hdr_marks(hhdr);
247
248 hhdr -> hb_last_reclaimed = (unsigned short)GC_gc_no;
249 return(TRUE);
250 }
251
252 #define FL_UNKNOWN -1
253 /*
254 * Remove hhdr from the appropriate free list.
255 * We assume it is on the nth free list, or on the size
256 * appropriate free list if n is FL_UNKNOWN.
257 */
GC_remove_from_fl(hhdr,n)258 void GC_remove_from_fl(hhdr, n)
259 hdr * hhdr;
260 int n;
261 {
262 int index;
263
264 GC_ASSERT(((hhdr -> hb_sz) & (HBLKSIZE-1)) == 0);
265 # ifndef USE_MUNMAP
266 /* We always need index to mainatin free counts. */
267 if (FL_UNKNOWN == n) {
268 index = GC_hblk_fl_from_blocks(divHBLKSZ(hhdr -> hb_sz));
269 } else {
270 index = n;
271 }
272 # endif
273 if (hhdr -> hb_prev == 0) {
274 # ifdef USE_MUNMAP
275 if (FL_UNKNOWN == n) {
276 index = GC_hblk_fl_from_blocks(divHBLKSZ(hhdr -> hb_sz));
277 } else {
278 index = n;
279 }
280 # endif
281 GC_ASSERT(HDR(GC_hblkfreelist[index]) == hhdr);
282 GC_hblkfreelist[index] = hhdr -> hb_next;
283 } else {
284 hdr *phdr;
285 GET_HDR(hhdr -> hb_prev, phdr);
286 phdr -> hb_next = hhdr -> hb_next;
287 }
288 FREE_ASSERT(GC_free_bytes[index] >= hhdr -> hb_sz);
289 INCR_FREE_BYTES(index, - (signed_word)(hhdr -> hb_sz));
290 if (0 != hhdr -> hb_next) {
291 hdr * nhdr;
292 GC_ASSERT(!IS_FORWARDING_ADDR_OR_NIL(NHDR(hhdr)));
293 GET_HDR(hhdr -> hb_next, nhdr);
294 nhdr -> hb_prev = hhdr -> hb_prev;
295 }
296 }
297
298 /*
299 * Return a pointer to the free block ending just before h, if any.
300 */
GC_free_block_ending_at(h)301 struct hblk * GC_free_block_ending_at(h)
302 struct hblk *h;
303 {
304 struct hblk * p = h - 1;
305 hdr * phdr;
306
307 GET_HDR(p, phdr);
308 while (0 != phdr && IS_FORWARDING_ADDR_OR_NIL(phdr)) {
309 p = FORWARDED_ADDR(p,phdr);
310 phdr = HDR(p);
311 }
312 if (0 != phdr) {
313 if(HBLK_IS_FREE(phdr)) {
314 return p;
315 } else {
316 return 0;
317 }
318 }
319 p = GC_prev_block(h - 1);
320 if (0 != p) {
321 phdr = HDR(p);
322 if (HBLK_IS_FREE(phdr) && (ptr_t)p + phdr -> hb_sz == (ptr_t)h) {
323 return p;
324 }
325 }
326 return 0;
327 }
328
329 /*
330 * Add hhdr to the appropriate free list.
331 * We maintain individual free lists sorted by address.
332 */
GC_add_to_fl(h,hhdr)333 void GC_add_to_fl(h, hhdr)
334 struct hblk *h;
335 hdr * hhdr;
336 {
337 int index = GC_hblk_fl_from_blocks(divHBLKSZ(hhdr -> hb_sz));
338 struct hblk *second = GC_hblkfreelist[index];
339 hdr * second_hdr;
340 # ifdef GC_ASSERTIONS
341 struct hblk *next = (struct hblk *)((word)h + hhdr -> hb_sz);
342 hdr * nexthdr = HDR(next);
343 struct hblk *prev = GC_free_block_ending_at(h);
344 hdr * prevhdr = HDR(prev);
345 GC_ASSERT(nexthdr == 0 || !HBLK_IS_FREE(nexthdr) || !IS_MAPPED(nexthdr));
346 GC_ASSERT(prev == 0 || !HBLK_IS_FREE(prevhdr) || !IS_MAPPED(prevhdr));
347 # endif
348 GC_ASSERT(((hhdr -> hb_sz) & (HBLKSIZE-1)) == 0);
349 GC_hblkfreelist[index] = h;
350 INCR_FREE_BYTES(index, hhdr -> hb_sz);
351 FREE_ASSERT(GC_free_bytes[index] <= GC_large_free_bytes)
352 hhdr -> hb_next = second;
353 hhdr -> hb_prev = 0;
354 if (0 != second) {
355 GET_HDR(second, second_hdr);
356 second_hdr -> hb_prev = h;
357 }
358 GC_invalidate_map(hhdr);
359 }
360
361 #ifdef USE_MUNMAP
362
363 /* Unmap blocks that haven't been recently touched. This is the only way */
364 /* way blocks are ever unmapped. */
GC_unmap_old(void)365 void GC_unmap_old(void)
366 {
367 struct hblk * h;
368 hdr * hhdr;
369 word sz;
370 unsigned short last_rec, threshold;
371 int i;
372 # define UNMAP_THRESHOLD 6
373
374 for (i = 0; i <= N_HBLK_FLS; ++i) {
375 for (h = GC_hblkfreelist[i]; 0 != h; h = hhdr -> hb_next) {
376 hhdr = HDR(h);
377 if (!IS_MAPPED(hhdr)) continue;
378 threshold = (unsigned short)(GC_gc_no - UNMAP_THRESHOLD);
379 last_rec = hhdr -> hb_last_reclaimed;
380 if ((last_rec > GC_gc_no || last_rec < threshold)
381 && threshold < GC_gc_no /* not recently wrapped */) {
382 sz = hhdr -> hb_sz;
383 GC_unmap((ptr_t)h, sz);
384 hhdr -> hb_flags |= WAS_UNMAPPED;
385 }
386 }
387 }
388 }
389
390 /* Merge all unmapped blocks that are adjacent to other free */
391 /* blocks. This may involve remapping, since all blocks are either */
392 /* fully mapped or fully unmapped. */
GC_merge_unmapped(void)393 void GC_merge_unmapped(void)
394 {
395 struct hblk * h, *next;
396 hdr * hhdr, *nexthdr;
397 word size, nextsize;
398 int i;
399
400 for (i = 0; i <= N_HBLK_FLS; ++i) {
401 h = GC_hblkfreelist[i];
402 while (h != 0) {
403 GET_HDR(h, hhdr);
404 size = hhdr->hb_sz;
405 next = (struct hblk *)((word)h + size);
406 GET_HDR(next, nexthdr);
407 /* Coalesce with successor, if possible */
408 if (0 != nexthdr && HBLK_IS_FREE(nexthdr)) {
409 nextsize = nexthdr -> hb_sz;
410 if (IS_MAPPED(hhdr)) {
411 GC_ASSERT(!IS_MAPPED(nexthdr));
412 /* make both consistent, so that we can merge */
413 if (size > nextsize) {
414 GC_remap((ptr_t)next, nextsize);
415 } else {
416 GC_unmap((ptr_t)h, size);
417 hhdr -> hb_flags |= WAS_UNMAPPED;
418 }
419 } else if (IS_MAPPED(nexthdr)) {
420 GC_ASSERT(!IS_MAPPED(hhdr));
421 if (size > nextsize) {
422 GC_unmap((ptr_t)next, nextsize);
423 } else {
424 GC_remap((ptr_t)h, size);
425 hhdr -> hb_flags &= ~WAS_UNMAPPED;
426 hhdr -> hb_last_reclaimed = nexthdr -> hb_last_reclaimed;
427 }
428 } else {
429 /* Unmap any gap in the middle */
430 GC_unmap_gap((ptr_t)h, size, (ptr_t)next, nexthdr -> hb_sz);
431 }
432 /* If they are both unmapped, we merge, but leave unmapped. */
433 GC_remove_from_fl(hhdr, i);
434 GC_remove_from_fl(nexthdr, FL_UNKNOWN);
435 hhdr -> hb_sz += nexthdr -> hb_sz;
436 GC_remove_header(next);
437 GC_add_to_fl(h, hhdr);
438 /* Start over at beginning of list */
439 h = GC_hblkfreelist[i];
440 } else /* not mergable with successor */ {
441 h = hhdr -> hb_next;
442 }
443 } /* while (h != 0) ... */
444 } /* for ... */
445 }
446
447 #endif /* USE_MUNMAP */
448
449 /*
450 * Return a pointer to a block starting at h of length bytes.
451 * Memory for the block is mapped.
452 * Remove the block from its free list, and return the remainder (if any)
453 * to its appropriate free list.
454 * May fail by returning 0.
455 * The header for the returned block must be set up by the caller.
456 * If the return value is not 0, then hhdr is the header for it.
457 */
GC_get_first_part(h,hhdr,bytes,index)458 struct hblk * GC_get_first_part(h, hhdr, bytes, index)
459 struct hblk *h;
460 hdr * hhdr;
461 word bytes;
462 int index;
463 {
464 word total_size = hhdr -> hb_sz;
465 struct hblk * rest;
466 hdr * rest_hdr;
467
468 GC_ASSERT((total_size & (HBLKSIZE-1)) == 0);
469 GC_remove_from_fl(hhdr, index);
470 if (total_size == bytes) return h;
471 rest = (struct hblk *)((word)h + bytes);
472 rest_hdr = GC_install_header(rest);
473 if (0 == rest_hdr) {
474 /* This may be very bad news ... */
475 WARN("Header allocation failed: Dropping block.\n", 0);
476 return(0);
477 }
478 rest_hdr -> hb_sz = total_size - bytes;
479 rest_hdr -> hb_flags = 0;
480 # ifdef GC_ASSERTIONS
481 /* Mark h not free, to avoid assertion about adjacent free blocks. */
482 hhdr -> hb_map = 0;
483 # endif
484 GC_add_to_fl(rest, rest_hdr);
485 return h;
486 }
487
488 /*
489 * H is a free block. N points at an address inside it.
490 * A new header for n has already been set up. Fix up h's header
491 * to reflect the fact that it is being split, move it to the
492 * appropriate free list.
493 * N replaces h in the original free list.
494 *
495 * Nhdr is not completely filled in, since it is about to allocated.
496 * It may in fact end up on the wrong free list for its size.
497 * (Hence adding it to a free list is silly. But this path is hopefully
498 * rare enough that it doesn't matter. The code is cleaner this way.)
499 */
GC_split_block(h,hhdr,n,nhdr,index)500 void GC_split_block(h, hhdr, n, nhdr, index)
501 struct hblk *h;
502 hdr * hhdr;
503 struct hblk *n;
504 hdr * nhdr;
505 int index; /* Index of free list */
506 {
507 word total_size = hhdr -> hb_sz;
508 word h_size = (word)n - (word)h;
509 struct hblk *prev = hhdr -> hb_prev;
510 struct hblk *next = hhdr -> hb_next;
511
512 /* Replace h with n on its freelist */
513 nhdr -> hb_prev = prev;
514 nhdr -> hb_next = next;
515 nhdr -> hb_sz = total_size - h_size;
516 nhdr -> hb_flags = 0;
517 if (0 != prev) {
518 HDR(prev) -> hb_next = n;
519 } else {
520 GC_hblkfreelist[index] = n;
521 }
522 if (0 != next) {
523 HDR(next) -> hb_prev = n;
524 }
525 INCR_FREE_BYTES(index, -(signed_word)h_size);
526 FREE_ASSERT(GC_free_bytes[index] > 0);
527 # ifdef GC_ASSERTIONS
528 nhdr -> hb_map = 0; /* Don't fail test for consecutive */
529 /* free blocks in GC_add_to_fl. */
530 # endif
531 # ifdef USE_MUNMAP
532 hhdr -> hb_last_reclaimed = GC_gc_no;
533 # endif
534 hhdr -> hb_sz = h_size;
535 GC_add_to_fl(h, hhdr);
536 GC_invalidate_map(nhdr);
537 }
538
539 struct hblk * GC_allochblk_nth();
540
541 /*
542 * Allocate (and return pointer to) a heap block
543 * for objects of size sz words, searching the nth free list.
544 *
545 * NOTE: We set obj_map field in header correctly.
546 * Caller is responsible for building an object freelist in block.
547 *
548 * Unlike older versions of the collectors, the client is responsible
549 * for clearing the block, if necessary.
550 */
551 struct hblk *
GC_allochblk(sz,kind,flags)552 GC_allochblk(sz, kind, flags)
553 word sz;
554 int kind;
555 unsigned flags; /* IGNORE_OFF_PAGE or 0 */
556 {
557 word blocks = OBJ_SZ_TO_BLOCKS(sz);
558 int start_list = GC_hblk_fl_from_blocks(blocks);
559 int i;
560 for (i = start_list; i <= N_HBLK_FLS; ++i) {
561 struct hblk * result = GC_allochblk_nth(sz, kind, flags, i);
562 if (0 != result) {
563 return result;
564 }
565 }
566 return 0;
567 }
568 /*
569 * The same, but with search restricted to nth free list.
570 */
571 struct hblk *
GC_allochblk_nth(sz,kind,flags,n)572 GC_allochblk_nth(sz, kind, flags, n)
573 word sz;
574 int kind;
575 unsigned char flags; /* IGNORE_OFF_PAGE or 0 */
576 int n;
577 {
578 register struct hblk *hbp;
579 register hdr * hhdr; /* Header corr. to hbp */
580 register struct hblk *thishbp;
581 register hdr * thishdr; /* Header corr. to hbp */
582 signed_word size_needed; /* number of bytes in requested objects */
583 signed_word size_avail; /* bytes available in this block */
584
585 size_needed = HBLKSIZE * OBJ_SZ_TO_BLOCKS(sz);
586
587 /* search for a big enough block in free list */
588 hbp = GC_hblkfreelist[n];
589 for(; 0 != hbp; hbp = hhdr -> hb_next) {
590 GET_HDR(hbp, hhdr);
591 size_avail = hhdr->hb_sz;
592 if (size_avail < size_needed) continue;
593 if (size_avail != size_needed
594 && !GC_use_entire_heap
595 && !GC_dont_gc
596 && USED_HEAP_SIZE >= GC_requested_heapsize
597 && !TRUE_INCREMENTAL && GC_should_collect()) {
598 # ifdef USE_MUNMAP
599 continue;
600 # else
601 /* If we have enough large blocks left to cover any */
602 /* previous request for large blocks, we go ahead */
603 /* and split. Assuming a steady state, that should */
604 /* be safe. It means that we can use the full */
605 /* heap if we allocate only small objects. */
606 if (!GC_enough_large_bytes_left(GC_large_allocd_bytes, n)) {
607 continue;
608 }
609 /* If we are deallocating lots of memory from */
610 /* finalizers, fail and collect sooner rather */
611 /* than later. */
612 if (WORDS_TO_BYTES(GC_finalizer_mem_freed)
613 > (GC_heapsize >> 4)) {
614 continue;
615 }
616 # endif /* !USE_MUNMAP */
617 }
618 /* If the next heap block is obviously better, go on. */
619 /* This prevents us from disassembling a single large block */
620 /* to get tiny blocks. */
621 {
622 signed_word next_size;
623
624 thishbp = hhdr -> hb_next;
625 if (thishbp != 0) {
626 GET_HDR(thishbp, thishdr);
627 next_size = (signed_word)(thishdr -> hb_sz);
628 if (next_size < size_avail
629 && next_size >= size_needed
630 && !GC_is_black_listed(thishbp, (word)size_needed)) {
631 continue;
632 }
633 }
634 }
635 if ( !IS_UNCOLLECTABLE(kind) &&
636 (kind != PTRFREE || size_needed > MAX_BLACK_LIST_ALLOC)) {
637 struct hblk * lasthbp = hbp;
638 ptr_t search_end = (ptr_t)hbp + size_avail - size_needed;
639 signed_word orig_avail = size_avail;
640 signed_word eff_size_needed = ((flags & IGNORE_OFF_PAGE)?
641 HBLKSIZE
642 : size_needed);
643
644
645 while ((ptr_t)lasthbp <= search_end
646 && (thishbp = GC_is_black_listed(lasthbp,
647 (word)eff_size_needed))
648 != 0) {
649 lasthbp = thishbp;
650 }
651 size_avail -= (ptr_t)lasthbp - (ptr_t)hbp;
652 thishbp = lasthbp;
653 if (size_avail >= size_needed) {
654 if (thishbp != hbp &&
655 0 != (thishdr = GC_install_header(thishbp))) {
656 /* Make sure it's mapped before we mangle it. */
657 # ifdef USE_MUNMAP
658 if (!IS_MAPPED(hhdr)) {
659 GC_remap((ptr_t)hbp, hhdr -> hb_sz);
660 hhdr -> hb_flags &= ~WAS_UNMAPPED;
661 }
662 # endif
663 /* Split the block at thishbp */
664 GC_split_block(hbp, hhdr, thishbp, thishdr, n);
665 /* Advance to thishbp */
666 hbp = thishbp;
667 hhdr = thishdr;
668 /* We must now allocate thishbp, since it may */
669 /* be on the wrong free list. */
670 }
671 } else if (size_needed > (signed_word)BL_LIMIT
672 && orig_avail - size_needed
673 > (signed_word)BL_LIMIT) {
674 /* Punt, since anything else risks unreasonable heap growth. */
675 if (++GC_large_alloc_warn_suppressed
676 >= GC_large_alloc_warn_interval) {
677 WARN("Repeated allocation of very large block "
678 "(appr. size %ld):\n"
679 "\tMay lead to memory leak and poor performance.\n",
680 size_needed);
681 GC_large_alloc_warn_suppressed = 0;
682 }
683 size_avail = orig_avail;
684 } else if (size_avail == 0 && size_needed == HBLKSIZE
685 && IS_MAPPED(hhdr)) {
686 if (!GC_find_leak) {
687 static unsigned count = 0;
688
689 /* The block is completely blacklisted. We need */
690 /* to drop some such blocks, since otherwise we spend */
691 /* all our time traversing them if pointerfree */
692 /* blocks are unpopular. */
693 /* A dropped block will be reconsidered at next GC. */
694 if ((++count & 3) == 0) {
695 /* Allocate and drop the block in small chunks, to */
696 /* maximize the chance that we will recover some */
697 /* later. */
698 word total_size = hhdr -> hb_sz;
699 struct hblk * limit = hbp + divHBLKSZ(total_size);
700 struct hblk * h;
701 struct hblk * prev = hhdr -> hb_prev;
702
703 GC_words_wasted += BYTES_TO_WORDS(total_size);
704 GC_large_free_bytes -= total_size;
705 GC_remove_from_fl(hhdr, n);
706 for (h = hbp; h < limit; h++) {
707 if (h == hbp || 0 != (hhdr = GC_install_header(h))) {
708 (void) setup_header(
709 hhdr,
710 BYTES_TO_WORDS(HBLKSIZE),
711 PTRFREE, 0); /* Cant fail */
712 if (GC_debugging_started) {
713 BZERO(h, HBLKSIZE);
714 }
715 }
716 }
717 /* Restore hbp to point at free block */
718 hbp = prev;
719 if (0 == hbp) {
720 return GC_allochblk_nth(sz, kind, flags, n);
721 }
722 hhdr = HDR(hbp);
723 }
724 }
725 }
726 }
727 if( size_avail >= size_needed ) {
728 # ifdef USE_MUNMAP
729 if (!IS_MAPPED(hhdr)) {
730 GC_remap((ptr_t)hbp, hhdr -> hb_sz);
731 hhdr -> hb_flags &= ~WAS_UNMAPPED;
732 }
733 # endif
734 /* hbp may be on the wrong freelist; the parameter n */
735 /* is important. */
736 hbp = GC_get_first_part(hbp, hhdr, size_needed, n);
737 break;
738 }
739 }
740
741 if (0 == hbp) return 0;
742
743 /* Add it to map of valid blocks */
744 if (!GC_install_counts(hbp, (word)size_needed)) return(0);
745 /* This leaks memory under very rare conditions. */
746
747 /* Set up header */
748 if (!setup_header(hhdr, sz, kind, flags)) {
749 GC_remove_counts(hbp, (word)size_needed);
750 return(0); /* ditto */
751 }
752
753 /* Notify virtual dirty bit implementation that we are about to write. */
754 /* Ensure that pointerfree objects are not protected if it's avoidable. */
755 GC_remove_protection(hbp, divHBLKSZ(size_needed),
756 (hhdr -> hb_descr == 0) /* pointer-free */);
757
758 /* We just successfully allocated a block. Restart count of */
759 /* consecutive failures. */
760 {
761 extern unsigned GC_fail_count;
762
763 GC_fail_count = 0;
764 }
765
766 GC_large_free_bytes -= size_needed;
767
768 GC_ASSERT(IS_MAPPED(hhdr));
769 return( hbp );
770 }
771
772 struct hblk * GC_freehblk_ptr = 0; /* Search position hint for GC_freehblk */
773
774 /*
775 * Free a heap block.
776 *
777 * Coalesce the block with its neighbors if possible.
778 *
779 * All mark words are assumed to be cleared.
780 */
781 void
GC_freehblk(hbp)782 GC_freehblk(hbp)
783 struct hblk *hbp;
784 {
785 struct hblk *next, *prev;
786 hdr *hhdr, *prevhdr, *nexthdr;
787 signed_word size;
788
789
790 GET_HDR(hbp, hhdr);
791 size = hhdr->hb_sz;
792 size = HBLKSIZE * OBJ_SZ_TO_BLOCKS(size);
793 GC_remove_counts(hbp, (word)size);
794 hhdr->hb_sz = size;
795 # ifdef USE_MUNMAP
796 hhdr -> hb_last_reclaimed = GC_gc_no;
797 # endif
798
799 /* Check for duplicate deallocation in the easy case */
800 if (HBLK_IS_FREE(hhdr)) {
801 GC_printf1("Duplicate large block deallocation of 0x%lx\n",
802 (unsigned long) hbp);
803 ABORT("Duplicate large block deallocation");
804 }
805
806 GC_ASSERT(IS_MAPPED(hhdr));
807 GC_invalidate_map(hhdr);
808 next = (struct hblk *)((word)hbp + size);
809 GET_HDR(next, nexthdr);
810 prev = GC_free_block_ending_at(hbp);
811 /* Coalesce with successor, if possible */
812 if(0 != nexthdr && HBLK_IS_FREE(nexthdr) && IS_MAPPED(nexthdr)) {
813 GC_remove_from_fl(nexthdr, FL_UNKNOWN);
814 hhdr -> hb_sz += nexthdr -> hb_sz;
815 GC_remove_header(next);
816 }
817 /* Coalesce with predecessor, if possible. */
818 if (0 != prev) {
819 prevhdr = HDR(prev);
820 if (IS_MAPPED(prevhdr)) {
821 GC_remove_from_fl(prevhdr, FL_UNKNOWN);
822 prevhdr -> hb_sz += hhdr -> hb_sz;
823 # ifdef USE_MUNMAP
824 prevhdr -> hb_last_reclaimed = GC_gc_no;
825 # endif
826 GC_remove_header(hbp);
827 hbp = prev;
828 hhdr = prevhdr;
829 }
830 }
831 /* FIXME: It is not clear we really always want to do these merges */
832 /* with -DUSE_MUNMAP, since it updates ages and hence prevents */
833 /* unmapping. */
834
835 GC_large_free_bytes += size;
836 GC_add_to_fl(hbp, hhdr);
837 }
838
839