mono/sgen/sgen-los.c

   1 /*
   2  * sgen-los.c: Large objects space.
   3  *
   4  * Author:
   5  *      Paolo Molaro (lupus@ximian.com)
   6  *
   7  * Copyright 2005-2010 Novell, Inc (http://www.novell.com)
   8  *
   9  * Thread start/stop adapted from Boehm's GC:
  10  * Copyright (c) 1994 by Xerox Corporation.  All rights reserved.
  11  * Copyright (c) 1996 by Silicon Graphics.  All rights reserved.
  12  * Copyright (c) 1998 by Fergus Henderson.  All rights reserved.
  13  * Copyright (c) 2000-2004 by Hewlett-Packard Company.  All rights reserved.
  14  * Copyright 2001-2003 Ximian, Inc
  15  * Copyright 2003-2010 Novell, Inc.
  16  * Copyright (C) 2012 Xamarin Inc
  17  *
  18  * Licensed under the MIT license. See LICENSE file in the project root for full license information.
  19  */
  20
  21 #include "config.h"
  22
  23 #ifdef HAVE_SGEN_GC
  24
  25 #include <string.h>
  26
  27 #include "mono/sgen/sgen-gc.h"
  28 #include "mono/sgen/sgen-protocol.h"
  29 #include "mono/sgen/sgen-cardtable.h"
  30 #include "mono/sgen/sgen-memory-governor.h"
  31 #include "mono/sgen/sgen-client.h"
  32
  33 #define LOS_SECTION_SIZE        (1024 * 1024)
  34
  35 /*
  36  * This shouldn't be much smaller or larger than MAX_SMALL_OBJ_SIZE.
  37  * Must be at least sizeof (LOSSection).
  38  */
  39 #define LOS_CHUNK_SIZE          4096
  40 #define LOS_CHUNK_BITS          12
  41
  42 /* Largest object that can be allocated in a section. */
  43 #define LOS_SECTION_OBJECT_LIMIT        (LOS_SECTION_SIZE - LOS_CHUNK_SIZE - sizeof (LOSObject))
  44 //#define LOS_SECTION_OBJECT_LIMIT      0
  45 #define LOS_SECTION_NUM_CHUNKS          ((LOS_SECTION_SIZE >> LOS_CHUNK_BITS) - 1)
  46
  47 #define LOS_SECTION_FOR_OBJ(obj)        ((LOSSection*)((mword)(obj) & ~(mword)(LOS_SECTION_SIZE - 1)))
  48 #define LOS_CHUNK_INDEX(obj,section)    (((char*)(obj) - (char*)(section)) >> LOS_CHUNK_BITS)
  49
  50 #define LOS_NUM_FAST_SIZES              32
  51
  52 typedef struct _LOSFreeChunks LOSFreeChunks;
  53 struct _LOSFreeChunks {
  54         LOSFreeChunks *next_size;
  55         size_t size;
  56 };
  57
  58 typedef struct _LOSSection LOSSection;
  59 struct _LOSSection {
  60         LOSSection *next;
  61         size_t num_free_chunks;
  62         unsigned char *free_chunk_map;
  63 };
  64
  65 /* We allow read only access on the list while sweep is not running */
  66 LOSObject *los_object_list = NULL;
  67 mword los_memory_usage = 0;
  68
  69 static LOSSection *los_sections = NULL;
  70 static LOSFreeChunks *los_fast_free_lists [LOS_NUM_FAST_SIZES]; /* 0 is for larger sizes */
  71 static mword los_num_objects = 0;
  72 static int los_num_sections = 0;
  73
  74 //#define USE_MALLOC
  75 //#define LOS_CONSISTENCY_CHECK
  76 //#define LOS_DUMMY
  77
  78 #ifdef LOS_DUMMY
  79 #define LOS_SEGMENT_SIZE        (4096 * 1024)
  80
  81 static char *los_segment = NULL;
  82 static int los_segment_index = 0;
  83 #endif
  84
  85 mword
  86 sgen_los_object_size (LOSObject *obj)
  87 {
  88         return obj->size & ~1L;
  89 }
  90
  91 #ifdef LOS_CONSISTENCY_CHECK
  92 static void
  93 los_consistency_check (void)
  94 {
  95         LOSSection *section;
  96         LOSObject *obj;
  97         int i;
  98         mword memory_usage = 0;
  99
 100         for (obj = los_object_list; obj; obj = obj->next) {
 101                 mword obj_size = sgen_los_object_size (obj);
 102                 char *end = obj->data + obj_size;
 103                 int start_index, num_chunks;
 104
 105                 memory_usage += obj_size;
 106
 107                 if (obj_size > LOS_SECTION_OBJECT_LIMIT)
 108                         continue;
 109
 110                 section = LOS_SECTION_FOR_OBJ (obj);
 111
 112                 g_assert (end <= (char*)section + LOS_SECTION_SIZE);
 113
 114                 start_index = LOS_CHUNK_INDEX (obj, section);
 115                 num_chunks = (obj_size + sizeof (LOSObject) + LOS_CHUNK_SIZE - 1) >> LOS_CHUNK_BITS;
 116                 for (i = start_index; i < start_index + num_chunks; ++i)
 117                         g_assert (!section->free_chunk_map [i]);
 118         }
 119
 120         for (i = 0; i < LOS_NUM_FAST_SIZES; ++i) {
 121                 LOSFreeChunks *size_chunks;
 122                 for (size_chunks = los_fast_free_lists [i]; size_chunks; size_chunks = size_chunks->next_size) {
 123                         LOSSection *section = LOS_SECTION_FOR_OBJ (size_chunks);
 124                         int j, num_chunks, start_index;
 125
 126                         if (i == 0)
 127                                 g_assert (size_chunks->size >= LOS_NUM_FAST_SIZES * LOS_CHUNK_SIZE);
 128                         else
 129                                 g_assert (size_chunks->size == i * LOS_CHUNK_SIZE);
 130
 131                         num_chunks = size_chunks->size >> LOS_CHUNK_BITS;
 132                         start_index = LOS_CHUNK_INDEX (size_chunks, section);
 133                         for (j = start_index; j < start_index + num_chunks; ++j)
 134                                 g_assert (section->free_chunk_map [j]);
 135                 }
 136         }
 137
 138         g_assert (los_memory_usage == memory_usage);
 139 }
 140 #endif
 141
 142 static void
 143 add_free_chunk (LOSFreeChunks *free_chunks, size_t size)
 144 {
 145         size_t num_chunks = size >> LOS_CHUNK_BITS;
 146
 147         free_chunks->size = size;
 148
 149         if (num_chunks >= LOS_NUM_FAST_SIZES)
 150                 num_chunks = 0;
 151         free_chunks->next_size = los_fast_free_lists [num_chunks];
 152         los_fast_free_lists [num_chunks] = free_chunks;
 153 }
 154
 155 static LOSFreeChunks*
 156 get_from_size_list (LOSFreeChunks **list, size_t size)
 157 {
 158         LOSFreeChunks *free_chunks = NULL;
 159         LOSSection *section;
 160         size_t i, num_chunks, start_index;
 161
 162
 163         g_assert ((size & (LOS_CHUNK_SIZE - 1)) == 0);
 164
 165         while (*list) {
 166                 free_chunks = *list;
 167                 if (free_chunks->size >= size)
 168                         break;
 169                 list = &(*list)->next_size;
 170         }
 171
 172         if (!*list)
 173                 return NULL;
 174
 175         *list = free_chunks->next_size;
 176
 177         if (free_chunks->size > size)
 178                 add_free_chunk ((LOSFreeChunks*)((char*)free_chunks + size), free_chunks->size - size);
 179
 180         num_chunks = size >> LOS_CHUNK_BITS;
 181
 182         section = LOS_SECTION_FOR_OBJ (free_chunks);
 183
 184         start_index = LOS_CHUNK_INDEX (free_chunks, section);
 185         for (i = start_index; i < start_index + num_chunks; ++i) {
 186                 g_assert (section->free_chunk_map [i]);
 187                 section->free_chunk_map [i] = 0;
 188         }
 189
 190         section->num_free_chunks -= size >> LOS_CHUNK_BITS;
 191         g_assert (section->num_free_chunks >= 0);
 192
 193         return free_chunks;
 194 }
 195
 196 static LOSObject*
 197 randomize_los_object_start (gpointer addr, size_t obj_size, size_t alloced_size, size_t addr_alignment)
 198 {
 199         size_t offset = 0;
 200         if (alloced_size != obj_size) {
 201                 /*
 202                  * We want to get a random offset between 0 and (alloced_size - obj_size)
 203                  * We do a prime multiplication to avoid usage of functions which might not
 204                  * be thread/signal safe (like rand ()). We subtract 1 to avoid common
 205                  * power by 2 factors.
 206                  */
 207                 offset = SGEN_ALIGN_DOWN ((((size_t)addr - 1) * 2654435761u) % (alloced_size - obj_size));
 208         }
 209         SGEN_ASSERT (0, (alloced_size - obj_size) < addr_alignment, "Why are we wasting one entire chunk for a los object ?");
 210         /* Randomize the location within the reserved chunks to improve cache performance */
 211         return (LOSObject*)((guint8*)addr + offset);
 212
 213 }
 214
 215 static LOSObject*
 216 get_los_section_memory (size_t size)
 217 {
 218         LOSSection *section;
 219         LOSFreeChunks *free_chunks;
 220         size_t num_chunks;
 221         size_t obj_size = size;
 222
 223         size = SGEN_ALIGN_UP_TO (size, LOS_CHUNK_SIZE);
 224
 225         num_chunks = size >> LOS_CHUNK_BITS;
 226
 227         g_assert (size > 0 && size - sizeof (LOSObject) <= LOS_SECTION_OBJECT_LIMIT);
 228         g_assert (num_chunks > 0);
 229
 230  retry:
 231         if (num_chunks >= LOS_NUM_FAST_SIZES) {
 232                 free_chunks = get_from_size_list (&los_fast_free_lists [0], size);
 233         } else {
 234                 size_t i;
 235                 for (i = num_chunks; i < LOS_NUM_FAST_SIZES; ++i) {
 236                         free_chunks = get_from_size_list (&los_fast_free_lists [i], size);
 237                         if (free_chunks)
 238                                 break;
 239                 }
 240                 if (!free_chunks)
 241                         free_chunks = get_from_size_list (&los_fast_free_lists [0], size);
 242         }
 243
 244         if (free_chunks) {
 245                 return randomize_los_object_start (free_chunks, obj_size, size, LOS_CHUNK_SIZE);
 246         }
 247
 248         if (!sgen_memgov_try_alloc_space (LOS_SECTION_SIZE, SPACE_LOS))
 249                 return NULL;
 250
 251         section = (LOSSection *)sgen_alloc_os_memory_aligned (LOS_SECTION_SIZE, LOS_SECTION_SIZE, (SgenAllocFlags)(SGEN_ALLOC_HEAP | SGEN_ALLOC_ACTIVATE), NULL);
 252
 253         if (!section)
 254                 return NULL;
 255
 256         free_chunks = (LOSFreeChunks*)((char*)section + LOS_CHUNK_SIZE);
 257         free_chunks->size = LOS_SECTION_SIZE - LOS_CHUNK_SIZE;
 258         free_chunks->next_size = los_fast_free_lists [0];
 259         los_fast_free_lists [0] = free_chunks;
 260
 261         section->num_free_chunks = LOS_SECTION_NUM_CHUNKS;
 262
 263         section->free_chunk_map = (unsigned char*)section + sizeof (LOSSection);
 264         g_assert (sizeof (LOSSection) + LOS_SECTION_NUM_CHUNKS + 1 <= LOS_CHUNK_SIZE);
 265         section->free_chunk_map [0] = 0;
 266         memset (section->free_chunk_map + 1, 1, LOS_SECTION_NUM_CHUNKS);
 267
 268         section->next = los_sections;
 269         los_sections = section;
 270
 271         ++los_num_sections;
 272
 273         goto retry;
 274 }
 275
 276 static void
 277 free_los_section_memory (LOSObject *obj, size_t size)
 278 {
 279         LOSSection *section = LOS_SECTION_FOR_OBJ (obj);
 280         size_t num_chunks, i, start_index;
 281
 282         size = SGEN_ALIGN_UP_TO (size, LOS_CHUNK_SIZE);
 283
 284         num_chunks = size >> LOS_CHUNK_BITS;
 285
 286         g_assert (size > 0 && size - sizeof (LOSObject) <= LOS_SECTION_OBJECT_LIMIT);
 287         g_assert (num_chunks > 0);
 288
 289         section->num_free_chunks += num_chunks;
 290         g_assert (section->num_free_chunks <= LOS_SECTION_NUM_CHUNKS);
 291
 292         /*
 293          * We could free the LOS section here if it's empty, but we
 294          * can't unless we also remove its free chunks from the fast
 295          * free lists.  Instead, we do it in los_sweep().
 296          */
 297
 298         start_index = LOS_CHUNK_INDEX (obj, section);
 299         for (i = start_index; i < start_index + num_chunks; ++i) {
 300                 g_assert (!section->free_chunk_map [i]);
 301                 section->free_chunk_map [i] = 1;
 302         }
 303
 304         add_free_chunk ((LOSFreeChunks*)SGEN_ALIGN_DOWN_TO ((mword)obj, LOS_CHUNK_SIZE), size);
 305 }
 306
 307 void
 308 sgen_los_free_object (LOSObject *obj)
 309 {
 310         if (obj->cardtable_mod_union)
 311                 sgen_card_table_free_mod_union (obj->cardtable_mod_union, (char*)obj->data, sgen_los_object_size (obj));
 312
 313 #ifndef LOS_DUMMY
 314         mword size = sgen_los_object_size (obj);
 315         SGEN_LOG (4, "Freed large object %p, size %lu", obj->data, (unsigned long)size);
 316         binary_protocol_empty (obj->data, size);
 317
 318         los_memory_usage -= size;
 319         los_num_objects--;
 320
 321 #ifdef USE_MALLOC
 322         free (obj);
 323 #else
 324         if (size > LOS_SECTION_OBJECT_LIMIT) {
 325                 int pagesize = mono_pagesize ();
 326                 size += sizeof (LOSObject);
 327                 size = SGEN_ALIGN_UP_TO (size, pagesize);
 328                 sgen_free_os_memory ((gpointer)SGEN_ALIGN_DOWN_TO ((mword)obj, pagesize), size, SGEN_ALLOC_HEAP);
 329                 sgen_memgov_release_space (size, SPACE_LOS);
 330         } else {
 331                 free_los_section_memory (obj, size + sizeof (LOSObject));
 332 #ifdef LOS_CONSISTENCY_CHECKS
 333                 los_consistency_check ();
 334 #endif
 335         }
 336 #endif
 337 #endif
 338 }
 339
 340 /*
 341  * Objects with size >= MAX_SMALL_SIZE are allocated in the large object space.
 342  * They are currently kept track of with a linked list.
 343  * They don't move, so there is no need to pin them during collection
 344  * and we avoid the memcpy overhead.
 345  */
 346 void*
 347 sgen_los_alloc_large_inner (GCVTable vtable, size_t size)
 348 {
 349         LOSObject *obj = NULL;
 350         void **vtslot;
 351
 352         g_assert (size > SGEN_MAX_SMALL_OBJ_SIZE);
 353         g_assert ((size & 1) == 0);
 354
 355         /*
 356          * size + sizeof (LOSObject) <= SSIZE_MAX - (mono_pagesize () - 1)
 357          *
 358          * therefore:
 359          *
 360          * size <= SSIZE_MAX - (mono_pagesize () - 1) - sizeof (LOSObject)
 361          */
 362         if (size > SSIZE_MAX - (mono_pagesize () - 1) - sizeof (LOSObject))
 363                 return NULL;
 364
 365 #ifdef LOS_DUMMY
 366         if (!los_segment)
 367                 los_segment = sgen_alloc_os_memory (LOS_SEGMENT_SIZE, SGEN_ALLOC_HEAP | SGEN_ALLOC_ACTIVATE, NULL);
 368         los_segment_index = ALIGN_UP (los_segment_index);
 369
 370         obj = (LOSObject*)(los_segment + los_segment_index);
 371         los_segment_index += size + sizeof (LOSObject);
 372         g_assert (los_segment_index <= LOS_SEGMENT_SIZE);
 373 #else
 374         sgen_ensure_free_space (size, GENERATION_OLD);
 375
 376 #ifdef USE_MALLOC
 377         obj = malloc (size + sizeof (LOSObject));
 378         memset (obj, 0, size + sizeof (LOSObject));
 379 #else
 380         if (size > LOS_SECTION_OBJECT_LIMIT) {
 381                 size_t obj_size = size + sizeof (LOSObject);
 382                 int pagesize = mono_pagesize ();
 383                 size_t alloc_size = SGEN_ALIGN_UP_TO (obj_size, pagesize);
 384                 if (sgen_memgov_try_alloc_space (alloc_size, SPACE_LOS)) {
 385                         obj = (LOSObject *)sgen_alloc_os_memory (alloc_size, (SgenAllocFlags)(SGEN_ALLOC_HEAP | SGEN_ALLOC_ACTIVATE), NULL);
 386                         if (obj)
 387                                 obj = randomize_los_object_start (obj, obj_size, alloc_size, pagesize);
 388                 }
 389         } else {
 390                 obj = get_los_section_memory (size + sizeof (LOSObject));
 391                 if (obj)
 392                         memset (obj, 0, size + sizeof (LOSObject));
 393         }
 394 #endif
 395 #endif
 396         if (!obj)
 397                 return NULL;
 398         g_assert (!((mword)obj->data & (SGEN_ALLOC_ALIGN - 1)));
 399         obj->size = size;
 400         vtslot = (void**)obj->data;
 401         *vtslot = vtable;
 402         sgen_update_heap_boundaries ((mword)obj->data, (mword)obj->data + size);
 403         obj->next = los_object_list;
 404         /*
 405          * We need a memory barrier so we don't expose as head of the los object list
 406          * a LOSObject that doesn't have its fields initialized.
 407          */
 408         mono_memory_write_barrier ();
 409         los_object_list = obj;
 410         los_memory_usage += size;
 411         los_num_objects++;
 412         SGEN_LOG (4, "Allocated large object %p, vtable: %p (%s), size: %zd", obj->data, vtable, sgen_client_vtable_get_name (vtable), size);
 413         binary_protocol_alloc (obj->data, vtable, size, sgen_client_get_provenance ());
 414
 415 #ifdef LOS_CONSISTENCY_CHECK
 416         los_consistency_check ();
 417 #endif
 418
 419         return obj->data;
 420 }
 421
 422 static void sgen_los_unpin_object (GCObject *data);
 423
 424 void
 425 sgen_los_sweep (void)
 426 {
 427         LOSObject *bigobj, *prevbo;
 428         LOSSection *section, *prev;
 429         int i;
 430         int num_sections = 0;
 431
 432         /* sweep the big objects list */
 433         prevbo = NULL;
 434         for (bigobj = los_object_list; bigobj;) {
 435                 SGEN_ASSERT (0, !SGEN_OBJECT_IS_PINNED (bigobj->data), "Who pinned a LOS object?");
 436
 437                 if (sgen_los_object_is_pinned (bigobj->data)) {
 438                         if (bigobj->cardtable_mod_union) {
 439                                 mword obj_size = sgen_los_object_size (bigobj);
 440                                 mword num_cards = sgen_card_table_number_of_cards_in_range ((mword) bigobj->data, obj_size);
 441                                 memset (bigobj->cardtable_mod_union, 0, num_cards);
 442                         }
 443
 444                         sgen_los_unpin_object (bigobj->data);
 445                         sgen_update_heap_boundaries ((mword)bigobj->data, (mword)bigobj->data + sgen_los_object_size (bigobj));
 446                 } else {
 447                         LOSObject *to_free;
 448                         /* not referenced anywhere, so we can free it */
 449                         if (prevbo)
 450                                 prevbo->next = bigobj->next;
 451                         else
 452                                 los_object_list = bigobj->next;
 453                         to_free = bigobj;
 454                         bigobj = bigobj->next;
 455                         sgen_los_free_object (to_free);
 456                         continue;
 457                 }
 458                 prevbo = bigobj;
 459                 bigobj = bigobj->next;
 460         }
 461
 462         /* Try to free memory */
 463         for (i = 0; i < LOS_NUM_FAST_SIZES; ++i)
 464                 los_fast_free_lists [i] = NULL;
 465
 466         prev = NULL;
 467         section = los_sections;
 468         while (section) {
 469                 if (section->num_free_chunks == LOS_SECTION_NUM_CHUNKS) {
 470                         LOSSection *next = section->next;
 471                         if (prev)
 472                                 prev->next = next;
 473                         else
 474                                 los_sections = next;
 475                         sgen_free_os_memory (section, LOS_SECTION_SIZE, SGEN_ALLOC_HEAP);
 476                         sgen_memgov_release_space (LOS_SECTION_SIZE, SPACE_LOS);
 477                         section = next;
 478                         --los_num_sections;
 479                         continue;
 480                 }
 481
 482                 for (i = 0; i <= LOS_SECTION_NUM_CHUNKS; ++i) {
 483                         if (section->free_chunk_map [i]) {
 484                                 int j;
 485                                 for (j = i + 1; j <= LOS_SECTION_NUM_CHUNKS && section->free_chunk_map [j]; ++j)
 486                                         ;
 487                                 add_free_chunk ((LOSFreeChunks*)((char*)section + (i << LOS_CHUNK_BITS)), (j - i) << LOS_CHUNK_BITS);
 488                                 i = j - 1;
 489                         }
 490                 }
 491
 492                 prev = section;
 493                 section = section->next;
 494
 495                 ++num_sections;
 496         }
 497
 498 #ifdef LOS_CONSISTENCY_CHECK
 499         los_consistency_check ();
 500 #endif
 501
 502         /*
 503         g_print ("LOS sections: %d  objects: %d  usage: %d\n", num_sections, los_num_objects, los_memory_usage);
 504         for (i = 0; i < LOS_NUM_FAST_SIZES; ++i) {
 505                 int num_chunks = 0;
 506                 LOSFreeChunks *free_chunks;
 507                 for (free_chunks = los_fast_free_lists [i]; free_chunks; free_chunks = free_chunks->next_size)
 508                         ++num_chunks;
 509                 g_print ("  %d: %d\n", i, num_chunks);
 510         }
 511         */
 512
 513         g_assert (los_num_sections == num_sections);
 514 }
 515
 516 gboolean
 517 sgen_ptr_is_in_los (char *ptr, char **start)
 518 {
 519         LOSObject *obj;
 520
 521         *start = NULL;
 522         for (obj = los_object_list; obj; obj = obj->next) {
 523                 char *end = (char*)obj->data + sgen_los_object_size (obj);
 524
 525                 if (ptr >= (char*)obj->data && ptr < end) {
 526                         *start = (char*)obj->data;
 527                         return TRUE;
 528                 }
 529         }
 530         return FALSE;
 531 }
 532
 533 void
 534 sgen_los_iterate_objects (IterateObjectCallbackFunc cb, void *user_data)
 535 {
 536         LOSObject *obj;
 537
 538         for (obj = los_object_list; obj; obj = obj->next)
 539                 cb (obj->data, sgen_los_object_size (obj), user_data);
 540 }
 541
 542 gboolean
 543 sgen_los_is_valid_object (char *object)
 544 {
 545         LOSObject *obj;
 546
 547         for (obj = los_object_list; obj; obj = obj->next) {
 548                 if ((char*)obj->data == object)
 549                         return TRUE;
 550         }
 551         return FALSE;
 552 }
 553
 554 gboolean
 555 mono_sgen_los_describe_pointer (char *ptr)
 556 {
 557         LOSObject *obj;
 558
 559         for (obj = los_object_list; obj; obj = obj->next) {
 560                 const char *los_kind;
 561                 mword size;
 562                 gboolean pinned;
 563
 564                 if ((char*)obj->data > ptr || (char*)obj->data + sgen_los_object_size (obj) <= ptr)
 565                         continue;
 566
 567                 size = sgen_los_object_size (obj);
 568                 pinned = sgen_los_object_is_pinned (obj->data);
 569
 570                 if (size > LOS_SECTION_OBJECT_LIMIT)
 571                         los_kind = "huge-los-ptr";
 572                 else
 573                         los_kind = "los-ptr";
 574
 575                 if ((char*)obj->data == ptr) {
 576                         SGEN_LOG (0, "%s (size %d pin %d)\n", los_kind, (int)size, pinned ? 1 : 0);
 577                 } else {
 578                         SGEN_LOG (0, "%s (interior-ptr offset %zd size %d pin %d)",
 579                                         los_kind, ptr - (char*)obj->data, (int)size, pinned ? 1 : 0);
 580                 }
 581
 582                 return TRUE;
 583         }
 584         return FALSE;
 585 }
 586
 587 void
 588 sgen_los_iterate_live_block_ranges (sgen_cardtable_block_callback callback)
 589 {
 590         LOSObject *obj;
 591         for (obj = los_object_list; obj; obj = obj->next) {
 592                 GCVTable vt = SGEN_LOAD_VTABLE (obj->data);
 593                 if (SGEN_VTABLE_HAS_REFERENCES (vt))
 594                         callback ((mword)obj->data, sgen_los_object_size (obj));
 595         }
 596 }
 597
 598 static guint8*
 599 get_cardtable_mod_union_for_object (LOSObject *obj)
 600 {
 601         mword size = sgen_los_object_size (obj);
 602         guint8 *mod_union = obj->cardtable_mod_union;
 603         guint8 *other;
 604         if (mod_union)
 605                 return mod_union;
 606         mod_union = sgen_card_table_alloc_mod_union ((char*)obj->data, size);
 607         other = (guint8 *)SGEN_CAS_PTR ((gpointer*)&obj->cardtable_mod_union, mod_union, NULL);
 608         if (!other) {
 609                 SGEN_ASSERT (0, obj->cardtable_mod_union == mod_union, "Why did CAS not replace?");
 610                 return mod_union;
 611         }
 612         sgen_card_table_free_mod_union (mod_union, (char*)obj->data, size);
 613         return other;
 614 }
 615
 616 void
 617 sgen_los_scan_card_table (CardTableScanType scan_type, ScanCopyContext ctx)
 618 {
 619         LOSObject *obj;
 620
 621         binary_protocol_los_card_table_scan_start (sgen_timestamp (), scan_type & CARDTABLE_SCAN_MOD_UNION);
 622         for (obj = los_object_list; obj; obj = obj->next) {
 623                 mword num_cards = 0;
 624                 guint8 *cards;
 625
 626                 if (!SGEN_OBJECT_HAS_REFERENCES (obj->data))
 627                         continue;
 628
 629                 if (scan_type & CARDTABLE_SCAN_MOD_UNION) {
 630                         if (!sgen_los_object_is_pinned (obj->data))
 631                                 continue;
 632
 633                         cards = get_cardtable_mod_union_for_object (obj);
 634                         g_assert (cards);
 635                         if (scan_type == CARDTABLE_SCAN_MOD_UNION_PRECLEAN) {
 636                                 guint8 *cards_preclean;
 637                                 mword obj_size = sgen_los_object_size (obj);
 638                                 num_cards = sgen_card_table_number_of_cards_in_range ((mword) obj->data, obj_size);
 639                                 cards_preclean = (guint8 *)sgen_alloc_internal_dynamic (num_cards, INTERNAL_MEM_CARDTABLE_MOD_UNION, TRUE);
 640
 641                                 sgen_card_table_preclean_mod_union (cards, cards_preclean, num_cards);
 642
 643                                 cards = cards_preclean;
 644                         }
 645                 } else {
 646                         cards = NULL;
 647                 }
 648
 649                 sgen_cardtable_scan_object (obj->data, sgen_los_object_size (obj), cards, ctx);
 650
 651                 if (scan_type == CARDTABLE_SCAN_MOD_UNION_PRECLEAN)
 652                         sgen_free_internal_dynamic (cards, num_cards, INTERNAL_MEM_CARDTABLE_MOD_UNION);
 653         }
 654         binary_protocol_los_card_table_scan_end (sgen_timestamp (), scan_type & CARDTABLE_SCAN_MOD_UNION);
 655 }
 656
 657 void
 658 sgen_los_count_cards (long long *num_total_cards, long long *num_marked_cards)
 659 {
 660         LOSObject *obj;
 661         long long total_cards = 0;
 662         long long marked_cards = 0;
 663
 664         for (obj = los_object_list; obj; obj = obj->next) {
 665                 int i;
 666                 guint8 *cards = sgen_card_table_get_card_scan_address ((mword) obj->data);
 667                 guint8 *cards_end = sgen_card_table_get_card_scan_address ((mword) obj->data + sgen_los_object_size (obj) - 1);
 668                 mword num_cards = (cards_end - cards) + 1;
 669
 670                 if (!SGEN_OBJECT_HAS_REFERENCES (obj->data))
 671                         continue;
 672
 673                 total_cards += num_cards;
 674                 for (i = 0; i < num_cards; ++i) {
 675                         if (cards [i])
 676                                 ++marked_cards;
 677                 }
 678         }
 679
 680         *num_total_cards = total_cards;
 681         *num_marked_cards = marked_cards;
 682 }
 683
 684 void
 685 sgen_los_update_cardtable_mod_union (void)
 686 {
 687         LOSObject *obj;
 688
 689         for (obj = los_object_list; obj; obj = obj->next) {
 690                 if (!SGEN_OBJECT_HAS_REFERENCES (obj->data))
 691                         continue;
 692                 sgen_card_table_update_mod_union (get_cardtable_mod_union_for_object (obj),
 693                                 (char*)obj->data, sgen_los_object_size (obj), NULL);
 694         }
 695 }
 696
 697 LOSObject*
 698 sgen_los_header_for_object (GCObject *data)
 699 {
 700 #if _MSC_VER
 701         return (LOSObject*)((char*)data - (int)(&(((LOSObject*)0)->data)));
 702 #else
 703         return (LOSObject*)((char*)data - sizeof (LOSObject));
 704 #endif
 705 }
 706
 707 void
 708 sgen_los_pin_object (GCObject *data)
 709 {
 710         LOSObject *obj = sgen_los_header_for_object (data);
 711         obj->size = obj->size | 1;
 712         binary_protocol_pin (data, (gpointer)SGEN_LOAD_VTABLE (data), sgen_safe_object_get_size (data));
 713 }
 714
 715 static void
 716 sgen_los_unpin_object (GCObject *data)
 717 {
 718         LOSObject *obj = sgen_los_header_for_object (data);
 719         obj->size = sgen_los_object_size (obj);
 720 }
 721
 722 gboolean
 723 sgen_los_object_is_pinned (GCObject *data)
 724 {
 725         LOSObject *obj = sgen_los_header_for_object (data);
 726         return obj->size & 1;
 727 }
 728
 729 void
 730 sgen_los_mark_mod_union_card (GCObject *mono_obj, void **ptr)
 731 {
 732         LOSObject *obj = sgen_los_header_for_object (mono_obj);
 733         guint8 *mod_union = get_cardtable_mod_union_for_object (obj);
 734         /* The LOSObject structure is not represented within the card space */
 735         size_t offset = sgen_card_table_get_card_offset ((char*)ptr, (char*)sgen_card_table_align_pointer((char*)mono_obj));
 736         SGEN_ASSERT (0, mod_union, "FIXME: optionally allocate the mod union if it's not here and CAS it in.");
 737         mod_union [offset] = 1;
 738 }
 739
 740 #endif /* HAVE_SGEN_GC */