2 * sgen-bridge.c: Simple generational GC.
4 * Copyright 2011 Novell, Inc (http://www.novell.com)
5 * Copyright 2011 Xamarin Inc (http://www.xamarin.com)
7 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
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13 * provided the above notices are retained, and a notice that the code was
14 * modified is included with the above copyright notice.
17 * Copyright 2001-2003 Ximian, Inc
18 * Copyright 2003-2010 Novell, Inc.
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47 #include "sgen-bridge.h"
48 #include "utils/mono-logger-internal.h"
49 #include "utils/mono-time.h"
59 #define DYN_ARRAY_REF(da,i) ((void*)((da)->data + (i) * (da)->elem_size))
60 #define DYN_ARRAY_PTR_REF(da,i) (((void**)(da)->data) [(i)])
61 #define DYN_ARRAY_INT_REF(da,i) (((int*)(da)->data) [(i)])
62 #define DYN_ARRAY_PTR_STATIC_INITIALIZER { 0, sizeof (void*), 0, NULL }
63 #define DYN_ARRAY_INT_STATIC_INITIALIZER { 0, sizeof (int), 0, NULL }
66 dyn_array_init (DynArray *da, int elem_size)
69 da->elem_size = elem_size;
75 dyn_array_ptr_init (DynArray *da)
77 dyn_array_init (da, sizeof (void*));
81 dyn_array_int_init (DynArray *da)
83 dyn_array_init (da, sizeof (int));
87 dyn_array_uninit (DynArray *da)
89 if (da->capacity <= 0)
92 mono_sgen_free_internal_dynamic (da->data, da->elem_size * da->capacity, INTERNAL_MEM_BRIDGE_DATA);
97 dyn_array_ensure_capacity (DynArray *da, int capacity)
99 int old_capacity = da->capacity;
102 if (capacity <= old_capacity)
105 if (da->capacity == 0)
107 while (capacity > da->capacity)
110 new_data = mono_sgen_alloc_internal_dynamic (da->elem_size * da->capacity, INTERNAL_MEM_BRIDGE_DATA);
111 memcpy (new_data, da->data, da->elem_size * da->size);
112 mono_sgen_free_internal_dynamic (da->data, da->elem_size * old_capacity, INTERNAL_MEM_BRIDGE_DATA);
117 dyn_array_add (DynArray *da)
121 dyn_array_ensure_capacity (da, da->size + 1);
123 p = DYN_ARRAY_REF (da, da->size);
129 dyn_array_ptr_add (DynArray *da, void *ptr)
131 void **p = dyn_array_add (da);
135 #define dyn_array_ptr_push dyn_array_ptr_add
138 dyn_array_ptr_pop (DynArray *da)
141 g_assert (da->size > 0);
142 p = DYN_ARRAY_PTR_REF (da, da->size - 1);
148 dyn_array_int_add (DynArray *da, int x)
150 int *p = dyn_array_add (da);
156 dyn_array_ptr_contains (DynArray *da, void *ptr)
159 for (i = 0; i < da->size; ++i)
160 if (DYN_ARRAY_PTR_REF (da, i) == ptr)
167 dyn_array_int_contains (DynArray *da, int x)
170 for (i = 0; i < da->size; ++i)
171 if (DYN_ARRAY_INT_REF (da, i) == x)
176 static DynArray merge_array;
179 dyn_array_int_merge (DynArray *dst, DynArray *src)
183 dyn_array_ensure_capacity (&merge_array, dst->size + src->size);
184 merge_array.size = 0;
186 for (i = j = 0; i < dst->size || j < src->size; ) {
187 if (i < dst->size && j < src->size) {
188 int a = DYN_ARRAY_INT_REF (dst, i);
189 int b = DYN_ARRAY_INT_REF (src, j);
191 dyn_array_int_add (&merge_array, a);
194 dyn_array_int_add (&merge_array, a);
198 dyn_array_int_add (&merge_array, b);
201 } else if (i < dst->size) {
202 dyn_array_int_add (&merge_array, DYN_ARRAY_INT_REF (dst, i));
205 dyn_array_int_add (&merge_array, DYN_ARRAY_INT_REF (src, j));
210 if (merge_array.size > dst->size) {
211 dyn_array_ensure_capacity (dst, merge_array.size);
212 memcpy (DYN_ARRAY_REF (dst, 0), DYN_ARRAY_REF (&merge_array, 0), merge_array.size * merge_array.elem_size);
213 dst->size = merge_array.size;
218 dyn_array_int_merge_one (DynArray *array, int value)
222 int end = array->size;
224 for (i = 0; i < end; ++i) {
225 if (DYN_ARRAY_INT_REF (array, i) == value)
227 else if (DYN_ARRAY_INT_REF (array, i) > value)
231 dyn_array_ensure_capacity (array, array->size + 1);
234 tmp = DYN_ARRAY_INT_REF (array, i);
235 for (; i <= end; ++i) {
236 DYN_ARRAY_INT_REF (array, i) = value;
238 tmp = DYN_ARRAY_INT_REF (array, i + 1);
240 DYN_ARRAY_INT_REF (array, end + 1) = tmp;
242 DYN_ARRAY_INT_REF (array, end) = value;
248 * FIXME: Optimizations:
250 * Don't allocate a scrs array for just one source. Most objects have
251 * just one source, so use the srcs pointer itself.
253 typedef struct _HashEntry {
254 MonoObject *obj; /* This is a duplicate - it's already stored in the hash table */
266 typedef struct _SCC {
269 int num_bridge_entries;
270 DynArray xrefs; /* these are incoming, not outgoing */
273 static SgenHashTable hash_table = SGEN_HASH_TABLE_INIT (INTERNAL_MEM_BRIDGE_DATA, INTERNAL_MEM_BRIDGE_DATA, sizeof (HashEntry), mono_aligned_addr_hash, NULL);
275 static MonoGCBridgeCallbacks bridge_callbacks;
277 static int current_time;
280 mono_gc_register_bridge_callbacks (MonoGCBridgeCallbacks *callbacks)
282 bridge_callbacks = *callbacks;
286 mono_sgen_is_bridge_object (MonoObject *obj)
288 return bridge_callbacks.is_bridge_object (obj);
292 mono_sgen_need_bridge_processing (void)
294 return bridge_callbacks.cross_references != NULL;
298 get_hash_entry (MonoObject *obj, gboolean *existing)
300 HashEntry *entry = mono_sgen_hash_table_lookup (&hash_table, obj);
311 memset (&new_entry, 0, sizeof (HashEntry));
314 dyn_array_ptr_init (&new_entry.srcs);
315 new_entry.finishing_time = -1;
316 new_entry.scc_index = -1;
318 mono_sgen_hash_table_replace (&hash_table, obj, &new_entry);
320 return mono_sgen_hash_table_lookup (&hash_table, obj);
324 add_source (HashEntry *entry, HashEntry *src)
326 dyn_array_ptr_add (&entry->srcs, src);
337 SGEN_HASH_TABLE_FOREACH (&hash_table, obj, entry) {
338 total_srcs += entry->srcs.size;
339 if (entry->srcs.size > max_srcs)
340 max_srcs = entry->srcs.size;
341 dyn_array_uninit (&entry->srcs);
342 } SGEN_HASH_TABLE_FOREACH_END;
344 mono_sgen_hash_table_clean (&hash_table);
346 dyn_array_uninit (&merge_array);
347 //g_print ("total srcs %d - max %d\n", total_srcs, max_srcs);
351 register_bridge_object (MonoObject *obj)
354 HashEntry *entry = get_hash_entry (obj, &existing);
355 entry->is_bridge = TRUE;
360 register_finishing_time (HashEntry *entry, int t)
362 g_assert (entry->finishing_time < 0);
363 entry->finishing_time = t;
367 object_is_live (MonoObject **objp)
369 MonoObject *obj = *objp;
370 MonoObject *fwd = SGEN_OBJECT_IS_FORWARDED (obj);
373 return mono_sgen_hash_table_lookup (&hash_table, fwd) == NULL;
375 if (!mono_sgen_object_is_live (obj))
377 return mono_sgen_hash_table_lookup (&hash_table, obj) == NULL;
380 static DynArray registered_bridges = DYN_ARRAY_PTR_STATIC_INITIALIZER;
381 static DynArray dfs_stack;
383 static int dsf1_passes, dsf2_passes;
387 #define HANDLE_PTR(ptr,obj) do { \
388 MonoObject *dst = (MonoObject*)*(ptr); \
389 if (dst && !object_is_live (&dst)) { \
390 dyn_array_ptr_push (&dfs_stack, obj_entry); \
391 dyn_array_ptr_push (&dfs_stack, get_hash_entry (dst, NULL)); \
396 dfs1 (HashEntry *obj_entry, HashEntry *src)
398 g_assert (dfs_stack.size == 0);
400 dyn_array_ptr_push (&dfs_stack, src);
401 dyn_array_ptr_push (&dfs_stack, obj_entry);
408 obj_entry = dyn_array_ptr_pop (&dfs_stack);
410 src = dyn_array_ptr_pop (&dfs_stack);
412 obj = obj_entry->obj;
416 //g_print ("link %s -> %s\n", mono_sgen_safe_name (src->obj), mono_sgen_safe_name (obj));
417 add_source (obj_entry, src);
419 //g_print ("starting with %s\n", mono_sgen_safe_name (obj));
422 if (obj_entry->is_visited)
425 obj_entry->is_visited = TRUE;
427 dyn_array_ptr_push (&dfs_stack, obj_entry);
428 /* NULL marks that the next entry is to be finished */
429 dyn_array_ptr_push (&dfs_stack, NULL);
431 #include "sgen-scan-object.h"
433 obj_entry = dyn_array_ptr_pop (&dfs_stack);
435 //g_print ("finish %s\n", mono_sgen_safe_name (obj_entry->obj));
436 register_finishing_time (obj_entry, current_time++);
438 } while (dfs_stack.size > 0);
442 scc_add_xref (SCC *src, SCC *dst)
444 g_assert (src != dst);
445 g_assert (src->index != dst->index);
447 if (dyn_array_int_contains (&dst->xrefs, src->index))
449 if (src->num_bridge_entries) {
450 dyn_array_int_merge_one (&dst->xrefs, src->index);
453 dyn_array_int_merge (&dst->xrefs, &src->xrefs);
454 for (i = 0; i < dst->xrefs.size; ++i)
455 g_assert (DYN_ARRAY_INT_REF (&dst->xrefs, i) != dst->index);
460 scc_add_entry (SCC *scc, HashEntry *entry)
462 g_assert (entry->scc_index < 0);
463 entry->scc_index = scc->index;
464 if (entry->is_bridge)
465 ++scc->num_bridge_entries;
468 static DynArray sccs;
469 static SCC *current_scc;
472 dfs2 (HashEntry *entry)
476 g_assert (dfs_stack.size == 0);
478 dyn_array_ptr_push (&dfs_stack, entry);
481 entry = dyn_array_ptr_pop (&dfs_stack);
484 if (entry->scc_index >= 0) {
485 if (entry->scc_index != current_scc->index)
486 scc_add_xref (DYN_ARRAY_REF (&sccs, entry->scc_index), current_scc);
490 scc_add_entry (current_scc, entry);
492 for (i = 0; i < entry->srcs.size; ++i)
493 dyn_array_ptr_push (&dfs_stack, DYN_ARRAY_PTR_REF (&entry->srcs, i));
494 } while (dfs_stack.size > 0);
498 compare_hash_entries (const void *ep1, const void *ep2)
500 HashEntry *e1 = *(HashEntry**)ep1;
501 HashEntry *e2 = *(HashEntry**)ep2;
502 return e2->finishing_time - e1->finishing_time;
505 static unsigned long step_1, step_2, step_3, step_4, step_5, step_6, step_7, step_8;
506 static int fist_pass_links, second_pass_links, sccs_links;
507 static int max_sccs_links = 0;
510 mono_sgen_bridge_register_finalized_object (MonoObject *obj)
512 g_assert (mono_sgen_need_bridge_processing ());
514 if (register_bridge_object (obj))
515 dyn_array_ptr_push (®istered_bridges, obj);
519 mono_sgen_bridge_processing_stw_step (void)
522 SGEN_TV_DECLARE (atv);
523 SGEN_TV_DECLARE (btv);
525 if (!registered_bridges.size)
528 SGEN_TV_GETTIME (btv);
532 dyn_array_ptr_init (&dfs_stack);
533 dyn_array_int_init (&merge_array);
536 for (i = 0; i < registered_bridges.size; ++i)
537 dfs1 (get_hash_entry (DYN_ARRAY_PTR_REF (®istered_bridges, i), NULL), NULL);
539 SGEN_TV_GETTIME (atv);
540 step_2 = SGEN_TV_ELAPSED (btv, atv);
544 mono_sgen_bridge_processing_finish (void)
547 int num_sccs, num_xrefs;
548 int max_entries, max_xrefs;
549 int hash_table_size, sccs_size;
552 int num_registered_bridges;
553 HashEntry **all_entries;
554 MonoGCBridgeSCC **api_sccs;
555 MonoGCBridgeXRef *api_xrefs;
556 SGEN_TV_DECLARE (atv);
557 SGEN_TV_DECLARE (btv);
559 if (!registered_bridges.size)
562 SGEN_TV_GETTIME (atv);
564 /* alloc and fill array of all entries */
566 all_entries = mono_sgen_alloc_internal_dynamic (sizeof (HashEntry*) * hash_table.num_entries, INTERNAL_MEM_BRIDGE_DATA);
569 SGEN_HASH_TABLE_FOREACH (&hash_table, obj, entry) {
570 g_assert (entry->finishing_time >= 0);
571 all_entries [j++] = entry;
572 fist_pass_links += entry->srcs.size;
573 } SGEN_HASH_TABLE_FOREACH_END;
574 g_assert (j == hash_table.num_entries);
575 hash_table_size = hash_table.num_entries;
577 /* sort array according to decreasing finishing time */
579 qsort (all_entries, hash_table.num_entries, sizeof (HashEntry*), compare_hash_entries);
581 SGEN_TV_GETTIME (btv);
582 step_3 = SGEN_TV_ELAPSED (atv, btv);
584 /* second DFS pass */
586 dyn_array_init (&sccs, sizeof (SCC));
587 for (i = 0; i < hash_table.num_entries; ++i) {
588 HashEntry *entry = all_entries [i];
589 if (entry->scc_index < 0) {
590 int index = sccs.size;
591 current_scc = dyn_array_add (&sccs);
592 current_scc->index = index;
593 current_scc->num_bridge_entries = 0;
594 current_scc->api_index = -1;
595 dyn_array_int_init (¤t_scc->xrefs);
601 sccs_size = sccs.size;
603 for (i = 0; i < hash_table.num_entries; ++i) {
604 HashEntry *entry = all_entries [i];
605 second_pass_links += entry->srcs.size;
608 SGEN_TV_GETTIME (atv);
609 step_4 = SGEN_TV_ELAPSED (btv, atv);
611 //g_print ("%d sccs\n", sccs.size);
613 dyn_array_uninit (&dfs_stack);
615 /* init data for callback */
618 for (i = 0; i < sccs.size; ++i) {
619 SCC *scc = DYN_ARRAY_REF (&sccs, i);
620 g_assert (scc->index == i);
621 if (scc->num_bridge_entries)
623 sccs_links += scc->xrefs.size;
624 max_sccs_links = MAX (max_sccs_links, scc->xrefs.size);
627 api_sccs = mono_sgen_alloc_internal_dynamic (sizeof (MonoGCBridgeSCC*) * num_sccs, INTERNAL_MEM_BRIDGE_DATA);
630 for (i = 0; i < sccs.size; ++i) {
631 SCC *scc = DYN_ARRAY_REF (&sccs, i);
632 if (!scc->num_bridge_entries)
635 api_sccs [j] = mono_sgen_alloc_internal_dynamic (sizeof (MonoGCBridgeSCC) + sizeof (MonoObject*) * scc->num_bridge_entries, INTERNAL_MEM_BRIDGE_DATA);
636 api_sccs [j]->num_objs = scc->num_bridge_entries;
637 scc->num_bridge_entries = 0;
638 scc->api_index = j++;
640 num_xrefs += scc->xrefs.size;
643 SGEN_HASH_TABLE_FOREACH (&hash_table, obj, entry) {
644 if (entry->is_bridge) {
645 SCC *scc = DYN_ARRAY_REF (&sccs, entry->scc_index);
646 api_sccs [scc->api_index]->objs [scc->num_bridge_entries++] = entry->obj;
648 } SGEN_HASH_TABLE_FOREACH_END;
650 api_xrefs = mono_sgen_alloc_internal_dynamic (sizeof (MonoGCBridgeXRef) * num_xrefs, INTERNAL_MEM_BRIDGE_DATA);
652 for (i = 0; i < sccs.size; ++i) {
654 SCC *scc = DYN_ARRAY_REF (&sccs, i);
655 if (!scc->num_bridge_entries)
657 for (k = 0; k < scc->xrefs.size; ++k) {
658 SCC *src_scc = DYN_ARRAY_REF (&sccs, DYN_ARRAY_INT_REF (&scc->xrefs, k));
659 if (!src_scc->num_bridge_entries)
661 api_xrefs [j].src_scc_index = src_scc->api_index;
662 api_xrefs [j].dst_scc_index = scc->api_index;
667 SGEN_TV_GETTIME (btv);
668 step_5 = SGEN_TV_ELAPSED (atv, btv);
673 max_entries = max_xrefs = 0;
674 for (i = 0; i < sccs.size; ++i) {
675 SCC *scc = DYN_ARRAY_REF (&sccs, i);
676 if (scc->num_bridge_entries)
678 if (scc->num_bridge_entries > max_entries)
679 max_entries = scc->num_bridge_entries;
680 if (scc->xrefs.size > max_xrefs)
681 max_xrefs = scc->xrefs.size;
682 dyn_array_uninit (&scc->xrefs);
685 dyn_array_uninit (&sccs);
687 mono_sgen_free_internal_dynamic (all_entries, sizeof (HashEntry*) * hash_table.num_entries, INTERNAL_MEM_BRIDGE_DATA);
690 /* Empty the registered bridges array */
691 num_registered_bridges = registered_bridges.size;
692 registered_bridges.size = 0;
694 SGEN_TV_GETTIME (atv);
695 step_6 = SGEN_TV_ELAPSED (btv, atv);
697 //g_print ("%d sccs containing bridges - %d max bridge objects - %d max xrefs\n", j, max_entries, max_xrefs);
701 bridge_callbacks.cross_references (num_sccs, api_sccs, num_xrefs, api_xrefs);
703 /*Release for finalization those objects we no longer care. */
704 SGEN_TV_GETTIME (btv);
705 step_7 = SGEN_TV_ELAPSED (atv, btv);
707 for (i = 0; i < num_sccs; ++i) {
708 if (!api_sccs [i]->objs [0])
710 for (j = 0; j < api_sccs [i]->num_objs; ++j)
711 mono_sgen_mark_bridge_object (api_sccs [i]->objs [j]);
714 /* free callback data */
716 for (i = 0; i < num_sccs; ++i) {
717 mono_sgen_free_internal_dynamic (api_sccs [i],
718 sizeof (MonoGCBridgeSCC) + sizeof (MonoObject*) * api_sccs [i]->num_objs,
719 INTERNAL_MEM_BRIDGE_DATA);
721 mono_sgen_free_internal_dynamic (api_sccs, sizeof (MonoGCBridgeSCC*) * num_sccs, INTERNAL_MEM_BRIDGE_DATA);
723 mono_sgen_free_internal_dynamic (api_xrefs, sizeof (MonoGCBridgeXRef) * num_xrefs, INTERNAL_MEM_BRIDGE_DATA);
725 SGEN_TV_GETTIME (atv);
726 step_8 = SGEN_TV_ELAPSED (btv, atv);
728 mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_GC, "GC_BRIDGE num-objects %d num_hash_entries %d sccs size %d init %.2fms df1 %.2fms sort %.2fms dfs2 %.2fms setup-cb %.2fms free-data %.2fms user-cb %.2fms clenanup %.2fms links %d/%d/%d/%d dfs passes %d/%d",
729 num_registered_bridges, hash_table_size, sccs.size,
738 fist_pass_links, second_pass_links, sccs_links, max_sccs_links,
739 dsf1_passes, dsf2_passes);
741 step_1 = 0; /* We must cleanup since this value is used as an accumulator. */
744 static const char *bridge_class;
747 bridge_test_is_bridge_object (MonoObject *obj)
749 return !strcmp (bridge_class, obj->vtable->klass->name);
753 bridge_test_cross_reference (int num_sccs, MonoGCBridgeSCC **sccs, int num_xrefs, MonoGCBridgeXRef *xrefs)
756 for (i = 0; i < num_sccs; ++i) {
758 // g_print ("--- SCC %d\n", i);
759 for (j = 0; j < sccs [i]->num_objs; ++j) {
760 // g_print (" %s\n", mono_sgen_safe_name (sccs [i]->objs [j]));
761 if (i & 1) /*retain half of the bridged objects */
762 sccs [i]->objs [0] = NULL;
765 for (i = 0; i < num_xrefs; ++i) {
766 g_assert (xrefs [i].src_scc_index >= 0 && xrefs [i].src_scc_index < num_sccs);
767 g_assert (xrefs [i].dst_scc_index >= 0 && xrefs [i].dst_scc_index < num_sccs);
768 // g_print ("%d -> %d\n", xrefs [i].src_scc_index, xrefs [i].dst_scc_index);
774 mono_sgen_register_test_bridge_callbacks (const char *bridge_class_name)
776 MonoGCBridgeCallbacks callbacks;
777 callbacks.is_bridge_object = bridge_test_is_bridge_object;
778 callbacks.cross_references = bridge_test_cross_reference;
779 mono_gc_register_bridge_callbacks (&callbacks);
780 bridge_class = bridge_class_name;