/vendor/gc/allchblk.c
C | 887 lines | 639 code | 76 blank | 172 comment | 200 complexity | 24384706407d730d7473bfdc00a3752e MD5 | raw file
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 21GC_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 47struct 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 /* Return the largest n such that */ 55 /* Is GC_large_allocd_bytes + the number of free bytes on lists */ 56 /* n .. N_HBLK_FLS > GC_max_large_allocd_bytes. */ 57 /* If there is no such n, return 0. */ 58# ifdef __GNUC__ 59 __inline__ 60# endif 61 static int GC_enough_large_bytes_left(void) 62 { 63 int n; 64 word bytes = GC_large_allocd_bytes; 65 66 GC_ASSERT(GC_max_large_allocd_bytes <= GC_heapsize); 67 for (n = N_HBLK_FLS; n >= 0; --n) { 68 bytes += GC_free_bytes[n]; 69 if (bytes >= GC_max_large_allocd_bytes) return n; 70 } 71 return 0; 72 } 73 74# define INCR_FREE_BYTES(n, b) GC_free_bytes[n] += (b); 75 76# define FREE_ASSERT(e) GC_ASSERT(e) 77 78#else /* USE_MUNMAP */ 79 80# define INCR_FREE_BYTES(n, b) 81# define FREE_ASSERT(e) 82 83#endif /* USE_MUNMAP */ 84 85/* Map a number of blocks to the appropriate large block free list index. */ 86int GC_hblk_fl_from_blocks(word blocks_needed) 87{ 88 if (blocks_needed <= UNIQUE_THRESHOLD) return (int)blocks_needed; 89 if (blocks_needed >= HUGE_THRESHOLD) return N_HBLK_FLS; 90 return (int)(blocks_needed - UNIQUE_THRESHOLD)/FL_COMPRESSION 91 + UNIQUE_THRESHOLD; 92 93} 94 95# define PHDR(hhdr) HDR(hhdr -> hb_prev) 96# define NHDR(hhdr) HDR(hhdr -> hb_next) 97 98# ifdef USE_MUNMAP 99# define IS_MAPPED(hhdr) (((hhdr) -> hb_flags & WAS_UNMAPPED) == 0) 100# else /* !USE_MMAP */ 101# define IS_MAPPED(hhdr) 1 102# endif /* USE_MUNMAP */ 103 104# if !defined(NO_DEBUGGING) 105void GC_print_hblkfreelist() 106{ 107 struct hblk * h; 108 word total_free = 0; 109 hdr * hhdr; 110 word sz; 111 unsigned i; 112 113 for (i = 0; i <= N_HBLK_FLS; ++i) { 114 h = GC_hblkfreelist[i]; 115# ifdef USE_MUNMAP 116 if (0 != h) GC_printf("Free list %ld:\n", 117 (unsigned long)i); 118# else 119 if (0 != h) GC_printf("Free list %lu (Total size %lu):\n", 120 i, (unsigned long)GC_free_bytes[i]); 121# endif 122 while (h != 0) { 123 hhdr = HDR(h); 124 sz = hhdr -> hb_sz; 125 GC_printf("\t%p size %lu ", h, (unsigned long)sz); 126 total_free += sz; 127 if (GC_is_black_listed(h, HBLKSIZE) != 0) { 128 GC_printf("start black listed\n"); 129 } else if (GC_is_black_listed(h, hhdr -> hb_sz) != 0) { 130 GC_printf("partially black listed\n"); 131 } else { 132 GC_printf("not black listed\n"); 133 } 134 h = hhdr -> hb_next; 135 } 136 } 137# ifndef USE_MUNMAP 138 if (total_free != GC_large_free_bytes) { 139 GC_printf("GC_large_free_bytes = %lu (INCONSISTENT!!)\n", 140 (unsigned long) GC_large_free_bytes); 141 } 142# endif 143 GC_printf("Total of %lu bytes on free list\n", (unsigned long)total_free); 144} 145 146/* Return the free list index on which the block described by the header */ 147/* appears, or -1 if it appears nowhere. */ 148int free_list_index_of(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 165void 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_printf("***Section from %p to %p\n", start, end); 182 for (p = start; p < end;) { 183 hhdr = HDR(p); 184 GC_printf("\t%p ", p); 185 if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) { 186 GC_printf("Missing header!!(%d)\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_printf("\tfree block of size 0x%lx bytes", 196 (unsigned long)(hhdr -> hb_sz)); 197 if (IS_MAPPED(hhdr)) { 198 GC_printf("\n"); 199 } else { 200 GC_printf("(unmapped)\n"); 201 } 202 actual_index = free_list_index_of(hhdr); 203 if (-1 == actual_index) { 204 GC_printf("\t\tBlock not on free list %d!!\n", 205 correct_index); 206 } else if (correct_index != actual_index) { 207 GC_printf("\t\tBlock on list %d, should be on %d!!\n", 208 actual_index, correct_index); 209 } 210 p += hhdr -> hb_sz; 211 } else { 212 GC_printf("\tused for blocks of size 0x%lx bytes\n", 213 (unsigned long)(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. */ 225static GC_bool setup_header(hdr * hhdr, struct hblk *block, size_t byte_sz, 226 int kind, unsigned flags) 227{ 228 word descr; 229 size_t granules; 230 231 /* Set size, kind and mark proc fields */ 232 hhdr -> hb_sz = byte_sz; 233 hhdr -> hb_obj_kind = (unsigned char)kind; 234 hhdr -> hb_flags = (unsigned char)flags; 235 hhdr -> hb_block = block; 236 descr = GC_obj_kinds[kind].ok_descriptor; 237 if (GC_obj_kinds[kind].ok_relocate_descr) descr += byte_sz; 238 hhdr -> hb_descr = descr; 239 240# ifdef MARK_BIT_PER_OBJ 241 /* Set hb_inv_sz as portably as possible. */ 242 /* We set it to the smallest value such that sz * inv_sz > 2**32 */ 243 /* This may be more precision than necessary. */ 244 if (byte_sz > MAXOBJBYTES) { 245 hhdr -> hb_inv_sz = LARGE_INV_SZ; 246 } else { 247 word inv_sz; 248 249# if CPP_WORDSZ == 64 250 inv_sz = ((word)1 << 32)/byte_sz; 251 if (((inv_sz*byte_sz) >> 32) == 0) ++inv_sz; 252# else /* 32 bit words */ 253 GC_ASSERT(byte_sz >= 4); 254 inv_sz = ((unsigned)1 << 31)/byte_sz; 255 inv_sz *= 2; 256 while (inv_sz*byte_sz > byte_sz) ++inv_sz; 257# endif 258 hhdr -> hb_inv_sz = inv_sz; 259 } 260# else /* MARK_BIT_PER_GRANULE */ 261 hhdr -> hb_large_block = (unsigned char)(byte_sz > MAXOBJBYTES); 262 granules = BYTES_TO_GRANULES(byte_sz); 263 if (EXPECT(!GC_add_map_entry(granules), FALSE)) { 264 /* Make it look like a valid block. */ 265 hhdr -> hb_sz = HBLKSIZE; 266 hhdr -> hb_descr = 0; 267 hhdr -> hb_large_block = TRUE; 268 hhdr -> hb_map = 0; 269 return FALSE; 270 } else { 271 size_t index = (hhdr -> hb_large_block? 0 : granules); 272 hhdr -> hb_map = GC_obj_map[index]; 273 } 274# endif /* MARK_BIT_PER_GRANULE */ 275 276 /* Clear mark bits */ 277 GC_clear_hdr_marks(hhdr); 278 279 hhdr -> hb_last_reclaimed = (unsigned short)GC_gc_no; 280 return(TRUE); 281} 282 283#define FL_UNKNOWN -1 284/* 285 * Remove hhdr from the appropriate free list. 286 * We assume it is on the nth free list, or on the size 287 * appropriate free list if n is FL_UNKNOWN. 288 */ 289void GC_remove_from_fl(hdr *hhdr, int n) 290{ 291 int index; 292 293 GC_ASSERT(((hhdr -> hb_sz) & (HBLKSIZE-1)) == 0); 294# ifndef USE_MUNMAP 295 /* We always need index to mainatin free counts. */ 296 if (FL_UNKNOWN == n) { 297 index = GC_hblk_fl_from_blocks(divHBLKSZ(hhdr -> hb_sz)); 298 } else { 299 index = n; 300 } 301# endif 302 if (hhdr -> hb_prev == 0) { 303# ifdef USE_MUNMAP 304 if (FL_UNKNOWN == n) { 305 index = GC_hblk_fl_from_blocks(divHBLKSZ(hhdr -> hb_sz)); 306 } else { 307 index = n; 308 } 309# endif 310 GC_ASSERT(HDR(GC_hblkfreelist[index]) == hhdr); 311 GC_hblkfreelist[index] = hhdr -> hb_next; 312 } else { 313 hdr *phdr; 314 GET_HDR(hhdr -> hb_prev, phdr); 315 phdr -> hb_next = hhdr -> hb_next; 316 } 317 FREE_ASSERT(GC_free_bytes[index] >= hhdr -> hb_sz); 318 INCR_FREE_BYTES(index, - (signed_word)(hhdr -> hb_sz)); 319 if (0 != hhdr -> hb_next) { 320 hdr * nhdr; 321 GC_ASSERT(!IS_FORWARDING_ADDR_OR_NIL(NHDR(hhdr))); 322 GET_HDR(hhdr -> hb_next, nhdr); 323 nhdr -> hb_prev = hhdr -> hb_prev; 324 } 325} 326 327/* 328 * Return a pointer to the free block ending just before h, if any. 329 */ 330struct hblk * GC_free_block_ending_at(struct hblk *h) 331{ 332 struct hblk * p = h - 1; 333 hdr * phdr; 334 335 GET_HDR(p, phdr); 336 while (0 != phdr && IS_FORWARDING_ADDR_OR_NIL(phdr)) { 337 p = FORWARDED_ADDR(p,phdr); 338 phdr = HDR(p); 339 } 340 if (0 != phdr) { 341 if(HBLK_IS_FREE(phdr)) { 342 return p; 343 } else { 344 return 0; 345 } 346 } 347 p = GC_prev_block(h - 1); 348 if (0 != p) { 349 phdr = HDR(p); 350 if (HBLK_IS_FREE(phdr) && (ptr_t)p + phdr -> hb_sz == (ptr_t)h) { 351 return p; 352 } 353 } 354 return 0; 355} 356 357/* 358 * Add hhdr to the appropriate free list. 359 * We maintain individual free lists sorted by address. 360 */ 361void GC_add_to_fl(struct hblk *h, hdr *hhdr) 362{ 363 int index = GC_hblk_fl_from_blocks(divHBLKSZ(hhdr -> hb_sz)); 364 struct hblk *second = GC_hblkfreelist[index]; 365 hdr * second_hdr; 366# if defined(GC_ASSERTIONS) && !defined(USE_MUNMAP) 367 struct hblk *next = (struct hblk *)((word)h + hhdr -> hb_sz); 368 hdr * nexthdr = HDR(next); 369 struct hblk *prev = GC_free_block_ending_at(h); 370 hdr * prevhdr = HDR(prev); 371 GC_ASSERT(nexthdr == 0 || !HBLK_IS_FREE(nexthdr) 372 || (signed_word)GC_heapsize < 0); 373 /* In the last case, blocks may be too large to merge. */ 374 GC_ASSERT(prev == 0 || !HBLK_IS_FREE(prevhdr) 375 || (signed_word)GC_heapsize < 0); 376# endif 377 GC_ASSERT(((hhdr -> hb_sz) & (HBLKSIZE-1)) == 0); 378 GC_hblkfreelist[index] = h; 379 INCR_FREE_BYTES(index, hhdr -> hb_sz); 380 FREE_ASSERT(GC_free_bytes[index] <= GC_large_free_bytes) 381 hhdr -> hb_next = second; 382 hhdr -> hb_prev = 0; 383 if (0 != second) { 384 GET_HDR(second, second_hdr); 385 second_hdr -> hb_prev = h; 386 } 387 hhdr -> hb_flags |= FREE_BLK; 388} 389 390#ifdef USE_MUNMAP 391 392/* Unmap blocks that haven't been recently touched. This is the only way */ 393/* way blocks are ever unmapped. */ 394void GC_unmap_old(void) 395{ 396 struct hblk * h; 397 hdr * hhdr; 398 word sz; 399 unsigned short last_rec, threshold; 400 int i; 401# ifndef MUNMAP_THRESHOLD 402# define MUNMAP_THRESHOLD 6 403# endif 404 405 for (i = 0; i <= N_HBLK_FLS; ++i) { 406 for (h = GC_hblkfreelist[i]; 0 != h; h = hhdr -> hb_next) { 407 hhdr = HDR(h); 408 if (!IS_MAPPED(hhdr)) continue; 409 threshold = (unsigned short)(GC_gc_no - MUNMAP_THRESHOLD); 410 last_rec = hhdr -> hb_last_reclaimed; 411 if ((last_rec > GC_gc_no || last_rec < threshold) 412 && threshold < GC_gc_no /* not recently wrapped */) { 413 sz = hhdr -> hb_sz; 414 GC_unmap((ptr_t)h, sz); 415 hhdr -> hb_flags |= WAS_UNMAPPED; 416 } 417 } 418 } 419} 420 421/* Merge all unmapped blocks that are adjacent to other free */ 422/* blocks. This may involve remapping, since all blocks are either */ 423/* fully mapped or fully unmapped. */ 424void GC_merge_unmapped(void) 425{ 426 struct hblk * h, *next; 427 hdr * hhdr, *nexthdr; 428 word size, nextsize; 429 int i; 430 431 for (i = 0; i <= N_HBLK_FLS; ++i) { 432 h = GC_hblkfreelist[i]; 433 while (h != 0) { 434 GET_HDR(h, hhdr); 435 size = hhdr->hb_sz; 436 next = (struct hblk *)((word)h + size); 437 GET_HDR(next, nexthdr); 438 /* Coalesce with successor, if possible */ 439 if (0 != nexthdr && HBLK_IS_FREE(nexthdr) 440 && (signed_word) (size + (nextsize = nexthdr->hb_sz)) > 0 441 /* no pot. overflow */) { 442 if (IS_MAPPED(hhdr)) { 443 GC_ASSERT(!IS_MAPPED(nexthdr)); 444 /* make both consistent, so that we can merge */ 445 if (size > nextsize) { 446 GC_remap((ptr_t)next, nextsize); 447 } else { 448 GC_unmap((ptr_t)h, size); 449 hhdr -> hb_flags |= WAS_UNMAPPED; 450 } 451 } else if (IS_MAPPED(nexthdr)) { 452 GC_ASSERT(!IS_MAPPED(hhdr)); 453 if (size > nextsize) { 454 GC_unmap((ptr_t)next, nextsize); 455 } else { 456 GC_remap((ptr_t)h, size); 457 hhdr -> hb_flags &= ~WAS_UNMAPPED; 458 hhdr -> hb_last_reclaimed = nexthdr -> hb_last_reclaimed; 459 } 460 } else { 461 /* Unmap any gap in the middle */ 462 GC_unmap_gap((ptr_t)h, size, (ptr_t)next, nexthdr -> hb_sz); 463 } 464 /* If they are both unmapped, we merge, but leave unmapped. */ 465 GC_remove_from_fl(hhdr, i); 466 GC_remove_from_fl(nexthdr, FL_UNKNOWN); 467 hhdr -> hb_sz += nexthdr -> hb_sz; 468 GC_remove_header(next); 469 GC_add_to_fl(h, hhdr); 470 /* Start over at beginning of list */ 471 h = GC_hblkfreelist[i]; 472 } else /* not mergable with successor */ { 473 h = hhdr -> hb_next; 474 } 475 } /* while (h != 0) ... */ 476 } /* for ... */ 477} 478 479#endif /* USE_MUNMAP */ 480 481/* 482 * Return a pointer to a block starting at h of length bytes. 483 * Memory for the block is mapped. 484 * Remove the block from its free list, and return the remainder (if any) 485 * to its appropriate free list. 486 * May fail by returning 0. 487 * The header for the returned block must be set up by the caller. 488 * If the return value is not 0, then hhdr is the header for it. 489 */ 490struct hblk * GC_get_first_part(struct hblk *h, hdr *hhdr, 491 size_t bytes, int index) 492{ 493 word total_size = hhdr -> hb_sz; 494 struct hblk * rest; 495 hdr * rest_hdr; 496 497 GC_ASSERT((total_size & (HBLKSIZE-1)) == 0); 498 GC_remove_from_fl(hhdr, index); 499 if (total_size == bytes) return h; 500 rest = (struct hblk *)((word)h + bytes); 501 rest_hdr = GC_install_header(rest); 502 if (0 == rest_hdr) { 503 /* FIXME: This is likely to be very bad news ... */ 504 WARN("Header allocation failed: Dropping block.\n", 0); 505 return(0); 506 } 507 rest_hdr -> hb_sz = total_size - bytes; 508 rest_hdr -> hb_flags = 0; 509# ifdef GC_ASSERTIONS 510 /* Mark h not free, to avoid assertion about adjacent free blocks. */ 511 hhdr -> hb_flags &= ~FREE_BLK; 512# endif 513 GC_add_to_fl(rest, rest_hdr); 514 return h; 515} 516 517/* 518 * H is a free block. N points at an address inside it. 519 * A new header for n has already been set up. Fix up h's header 520 * to reflect the fact that it is being split, move it to the 521 * appropriate free list. 522 * N replaces h in the original free list. 523 * 524 * Nhdr is not completely filled in, since it is about to allocated. 525 * It may in fact end up on the wrong free list for its size. 526 * (Hence adding it to a free list is silly. But this path is hopefully 527 * rare enough that it doesn't matter. The code is cleaner this way.) 528 */ 529void GC_split_block(struct hblk *h, hdr *hhdr, struct hblk *n, 530 hdr *nhdr, int index /* Index of free list */) 531{ 532 word total_size = hhdr -> hb_sz; 533 word h_size = (word)n - (word)h; 534 struct hblk *prev = hhdr -> hb_prev; 535 struct hblk *next = hhdr -> hb_next; 536 537 /* Replace h with n on its freelist */ 538 nhdr -> hb_prev = prev; 539 nhdr -> hb_next = next; 540 nhdr -> hb_sz = total_size - h_size; 541 nhdr -> hb_flags = 0; 542 if (0 != prev) { 543 HDR(prev) -> hb_next = n; 544 } else { 545 GC_hblkfreelist[index] = n; 546 } 547 if (0 != next) { 548 HDR(next) -> hb_prev = n; 549 } 550 INCR_FREE_BYTES(index, -(signed_word)h_size); 551 FREE_ASSERT(GC_free_bytes[index] > 0); 552# ifdef GC_ASSERTIONS 553 nhdr -> hb_flags &= ~FREE_BLK; 554 /* Don't fail test for consecutive */ 555 /* free blocks in GC_add_to_fl. */ 556# endif 557# ifdef USE_MUNMAP 558 hhdr -> hb_last_reclaimed = (unsigned short)GC_gc_no; 559# endif 560 hhdr -> hb_sz = h_size; 561 GC_add_to_fl(h, hhdr); 562 nhdr -> hb_flags |= FREE_BLK; 563} 564 565struct hblk * 566GC_allochblk_nth(size_t sz/* bytes */, int kind, unsigned flags, int n, 567 GC_bool may_split); 568 569/* 570 * Allocate (and return pointer to) a heap block 571 * for objects of size sz bytes, searching the nth free list. 572 * 573 * NOTE: We set obj_map field in header correctly. 574 * Caller is responsible for building an object freelist in block. 575 * 576 * The client is responsible for clearing the block, if necessary. 577 */ 578struct hblk * 579GC_allochblk(size_t sz, int kind, unsigned flags/* IGNORE_OFF_PAGE or 0 */) 580{ 581 word blocks; 582 int start_list; 583 int i; 584 struct hblk *result; 585 int split_limit; /* Highest index of free list whose blocks we */ 586 /* split. */ 587 588 GC_ASSERT((sz & (GRANULE_BYTES - 1)) == 0); 589 blocks = OBJ_SZ_TO_BLOCKS(sz); 590 if ((signed_word)(blocks * HBLKSIZE) < 0) { 591 return 0; 592 } 593 start_list = GC_hblk_fl_from_blocks(blocks); 594 /* Try for an exact match first. */ 595 result = GC_allochblk_nth(sz, kind, flags, start_list, FALSE); 596 if (0 != result) return result; 597 if (GC_use_entire_heap || GC_dont_gc 598 || USED_HEAP_SIZE < GC_requested_heapsize 599 || TRUE_INCREMENTAL || !GC_should_collect()) { 600 /* Should use more of the heap, even if it requires splitting. */ 601 split_limit = N_HBLK_FLS; 602 } else { 603# ifdef USE_MUNMAP 604 /* avoid splitting, since that might require remapping */ 605 split_limit = 0; 606# else 607 if (GC_finalizer_bytes_freed > (GC_heapsize >> 4)) { 608 /* If we are deallocating lots of memory from */ 609 /* finalizers, fail and collect sooner rather */ 610 /* than later. */ 611 split_limit = 0; 612 } else { 613 /* If we have enough large blocks left to cover any */ 614 /* previous request for large blocks, we go ahead */ 615 /* and split. Assuming a steady state, that should */ 616 /* be safe. It means that we can use the full */ 617 /* heap if we allocate only small objects. */ 618 split_limit = GC_enough_large_bytes_left(); 619 } 620# endif 621 } 622 if (start_list < UNIQUE_THRESHOLD) { 623 /* No reason to try start_list again, since all blocks are exact */ 624 /* matches. */ 625 ++start_list; 626 } 627 for (i = start_list; i <= split_limit; ++i) { 628 struct hblk * result = GC_allochblk_nth(sz, kind, flags, i, TRUE); 629 if (0 != result) return result; 630 } 631 return 0; 632} 633/* 634 * The same, but with search restricted to nth free list. 635 * Flags is IGNORE_OFF_PAGE or zero. 636 * Unlike the above, sz is in bytes. 637 * The may_split flag indicates whether it's OK to split larger blocks. 638 */ 639struct hblk * 640GC_allochblk_nth(size_t sz, int kind, unsigned flags, int n, GC_bool may_split) 641{ 642 struct hblk *hbp; 643 hdr * hhdr; /* Header corr. to hbp */ 644 /* Initialized after loop if hbp !=0 */ 645 /* Gcc uninitialized use warning is bogus. */ 646 struct hblk *thishbp; 647 hdr * thishdr; /* Header corr. to hbp */ 648 signed_word size_needed; /* number of bytes in requested objects */ 649 signed_word size_avail; /* bytes available in this block */ 650 651 size_needed = HBLKSIZE * OBJ_SZ_TO_BLOCKS(sz); 652 653 /* search for a big enough block in free list */ 654 hbp = GC_hblkfreelist[n]; 655 for(; 0 != hbp; hbp = hhdr -> hb_next) { 656 GET_HDR(hbp, hhdr); 657 size_avail = hhdr->hb_sz; 658 if (size_avail < size_needed) continue; 659 if (size_avail != size_needed) { 660 signed_word next_size; 661 662 if (!may_split) continue; 663 /* If the next heap block is obviously better, go on. */ 664 /* This prevents us from disassembling a single large block */ 665 /* to get tiny blocks. */ 666 thishbp = hhdr -> hb_next; 667 if (thishbp != 0) { 668 GET_HDR(thishbp, thishdr); 669 next_size = (signed_word)(thishdr -> hb_sz); 670 if (next_size < size_avail 671 && next_size >= size_needed 672 && !GC_is_black_listed(thishbp, (word)size_needed)) { 673 continue; 674 } 675 } 676 } 677 if ( !IS_UNCOLLECTABLE(kind) && 678 (kind != PTRFREE || size_needed > MAX_BLACK_LIST_ALLOC)) { 679 struct hblk * lasthbp = hbp; 680 ptr_t search_end = (ptr_t)hbp + size_avail - size_needed; 681 signed_word orig_avail = size_avail; 682 signed_word eff_size_needed = ((flags & IGNORE_OFF_PAGE)? 683 HBLKSIZE 684 : size_needed); 685 686 687 while ((ptr_t)lasthbp <= search_end 688 && (thishbp = GC_is_black_listed(lasthbp, 689 (word)eff_size_needed)) 690 != 0) { 691 lasthbp = thishbp; 692 } 693 size_avail -= (ptr_t)lasthbp - (ptr_t)hbp; 694 thishbp = lasthbp; 695 if (size_avail >= size_needed) { 696 if (thishbp != hbp && 697 0 != (thishdr = GC_install_header(thishbp))) { 698 /* Make sure it's mapped before we mangle it. */ 699# ifdef USE_MUNMAP 700 if (!IS_MAPPED(hhdr)) { 701 GC_remap((ptr_t)hbp, hhdr -> hb_sz); 702 hhdr -> hb_flags &= ~WAS_UNMAPPED; 703 } 704# endif 705 /* Split the block at thishbp */ 706 GC_split_block(hbp, hhdr, thishbp, thishdr, n); 707 /* Advance to thishbp */ 708 hbp = thishbp; 709 hhdr = thishdr; 710 /* We must now allocate thishbp, since it may */ 711 /* be on the wrong free list. */ 712 } 713 } else if (size_needed > (signed_word)BL_LIMIT 714 && orig_avail - size_needed 715 > (signed_word)BL_LIMIT) { 716 /* Punt, since anything else risks unreasonable heap growth. */ 717 if (++GC_large_alloc_warn_suppressed 718 >= GC_large_alloc_warn_interval) { 719 WARN("Repeated allocation of very large block " 720 "(appr. size %ld):\n" 721 "\tMay lead to memory leak and poor performance.\n", 722 size_needed); 723 GC_large_alloc_warn_suppressed = 0; 724 } 725 size_avail = orig_avail; 726 } else if (size_avail == 0 && size_needed == HBLKSIZE 727 && IS_MAPPED(hhdr)) { 728 if (!GC_find_leak) { 729 static unsigned count = 0; 730 731 /* The block is completely blacklisted. We need */ 732 /* to drop some such blocks, since otherwise we spend */ 733 /* all our time traversing them if pointerfree */ 734 /* blocks are unpopular. */ 735 /* A dropped block will be reconsidered at next GC. */ 736 if ((++count & 3) == 0) { 737 /* Allocate and drop the block in small chunks, to */ 738 /* maximize the chance that we will recover some */ 739 /* later. */ 740 word total_size = hhdr -> hb_sz; 741 struct hblk * limit = hbp + divHBLKSZ(total_size); 742 struct hblk * h; 743 struct hblk * prev = hhdr -> hb_prev; 744 745 GC_large_free_bytes -= total_size; 746 GC_bytes_dropped += total_size; 747 GC_remove_from_fl(hhdr, n); 748 for (h = hbp; h < limit; h++) { 749 if (h == hbp || 0 != (hhdr = GC_install_header(h))) { 750 (void) setup_header( 751 hhdr, h, 752 HBLKSIZE, 753 PTRFREE, 0); /* Cant fail */ 754 if (GC_debugging_started) { 755 BZERO(h, HBLKSIZE); 756 } 757 } 758 } 759 /* Restore hbp to point at free block */ 760 hbp = prev; 761 if (0 == hbp) { 762 return GC_allochblk_nth(sz, kind, flags, n, may_split); 763 } 764 hhdr = HDR(hbp); 765 } 766 } 767 } 768 } 769 if( size_avail >= size_needed ) { 770# ifdef USE_MUNMAP 771 if (!IS_MAPPED(hhdr)) { 772 GC_remap((ptr_t)hbp, hhdr -> hb_sz); 773 hhdr -> hb_flags &= ~WAS_UNMAPPED; 774 /* Note: This may leave adjacent, mapped free blocks. */ 775 } 776# endif 777 /* hbp may be on the wrong freelist; the parameter n */ 778 /* is important. */ 779 hbp = GC_get_first_part(hbp, hhdr, size_needed, n); 780 break; 781 } 782 } 783 784 if (0 == hbp) return 0; 785 786 /* Add it to map of valid blocks */ 787 if (!GC_install_counts(hbp, (word)size_needed)) return(0); 788 /* This leaks memory under very rare conditions. */ 789 790 /* Set up header */ 791 if (!setup_header(hhdr, hbp, sz, kind, flags)) { 792 GC_remove_counts(hbp, (word)size_needed); 793 return(0); /* ditto */ 794 } 795 796 /* Notify virtual dirty bit implementation that we are about to write. */ 797 /* Ensure that pointerfree objects are not protected if it's avoidable. */ 798 GC_remove_protection(hbp, divHBLKSZ(size_needed), 799 (hhdr -> hb_descr == 0) /* pointer-free */); 800 801 /* We just successfully allocated a block. Restart count of */ 802 /* consecutive failures. */ 803 { 804 extern unsigned GC_fail_count; 805 806 GC_fail_count = 0; 807 } 808 809 GC_large_free_bytes -= size_needed; 810 811 GC_ASSERT(IS_MAPPED(hhdr)); 812 return( hbp ); 813} 814 815struct hblk * GC_freehblk_ptr = 0; /* Search position hint for GC_freehblk */ 816 817/* 818 * Free a heap block. 819 * 820 * Coalesce the block with its neighbors if possible. 821 * 822 * All mark words are assumed to be cleared. 823 */ 824void 825GC_freehblk(struct hblk *hbp) 826{ 827struct hblk *next, *prev; 828hdr *hhdr, *prevhdr, *nexthdr; 829signed_word size; 830 831 832 GET_HDR(hbp, hhdr); 833 size = hhdr->hb_sz; 834 size = HBLKSIZE * OBJ_SZ_TO_BLOCKS(size); 835 if (size <= 0) 836 ABORT("Deallocating excessively large block. Too large an allocation?"); 837 /* Probably possible if we try to allocate more than half the address */ 838 /* space at once. If we dont catch it here, strange things happen */ 839 /* later. */ 840 GC_remove_counts(hbp, (word)size); 841 hhdr->hb_sz = size; 842# ifdef USE_MUNMAP 843 hhdr -> hb_last_reclaimed = (unsigned short)GC_gc_no; 844# endif 845 846 /* Check for duplicate deallocation in the easy case */ 847 if (HBLK_IS_FREE(hhdr)) { 848 GC_printf("Duplicate large block deallocation of %p\n", hbp); 849 ABORT("Duplicate large block deallocation"); 850 } 851 852 GC_ASSERT(IS_MAPPED(hhdr)); 853 hhdr -> hb_flags |= FREE_BLK; 854 next = (struct hblk *)((word)hbp + size); 855 GET_HDR(next, nexthdr); 856 prev = GC_free_block_ending_at(hbp); 857 /* Coalesce with successor, if possible */ 858 if(0 != nexthdr && HBLK_IS_FREE(nexthdr) && IS_MAPPED(nexthdr) 859 && (signed_word)(hhdr -> hb_sz + nexthdr -> hb_sz) > 0 860 /* no overflow */) { 861 GC_remove_from_fl(nexthdr, FL_UNKNOWN); 862 hhdr -> hb_sz += nexthdr -> hb_sz; 863 GC_remove_header(next); 864 } 865 /* Coalesce with predecessor, if possible. */ 866 if (0 != prev) { 867 prevhdr = HDR(prev); 868 if (IS_MAPPED(prevhdr) 869 && (signed_word)(hhdr -> hb_sz + prevhdr -> hb_sz) > 0) { 870 GC_remove_from_fl(prevhdr, FL_UNKNOWN); 871 prevhdr -> hb_sz += hhdr -> hb_sz; 872# ifdef USE_MUNMAP 873 prevhdr -> hb_last_reclaimed = (unsigned short)GC_gc_no; 874# endif 875 GC_remove_header(hbp); 876 hbp = prev; 877 hhdr = prevhdr; 878 } 879 } 880 /* FIXME: It is not clear we really always want to do these merges */ 881 /* with -DUSE_MUNMAP, since it updates ages and hence prevents */ 882 /* unmapping. */ 883 884 GC_large_free_bytes += size; 885 GC_add_to_fl(hbp, hhdr); 886} 887