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)
6 * Copyright 2001-2003 Ximian, Inc
7 * Copyright 2003-2010 Novell, Inc.
9 * Licensed under the MIT license. See LICENSE file in the project root for full license information.
19 #include "sgen/sgen-gc.h"
20 #include "sgen-bridge-internals.h"
21 #include "sgen/sgen-hash-table.h"
22 #include "sgen/sgen-qsort.h"
23 #include "sgen/sgen-client.h"
24 #include "tabledefs.h"
25 #include "utils/mono-logger-internals.h"
29 //#define TEST_NEW_XREFS
32 #if !defined(NEW_XREFS) || defined(TEST_NEW_XREFS)
37 #define XREFS new_xrefs
39 #define XREFS old_xrefs
42 #define OPTIMIZATION_COPY
43 #define OPTIMIZATION_FORWARD
44 #define OPTIMIZATION_SINGLETON_DYN_ARRAY
48 int capacity; /* if negative, data points to another DynArray's data */
68 * FIXME: Optimizations:
70 * Don't allocate a scrs array for just one source. Most objects have
71 * just one source, so use the srcs pointer itself.
73 typedef struct _HashEntry {
78 guint32 is_visited : 1;
79 guint32 finishing_time : 31;
80 struct _HashEntry *forwarded_to;
93 } HashEntryWithAccounting;
98 int num_bridge_entries;
101 * New and old xrefs are typically mutually exclusive. Only when TEST_NEW_XREFS is
102 * enabled we do both, and compare the results. This should only be done for
103 * debugging, obviously.
106 DynIntArray old_xrefs; /* these are incoming, not outgoing */
109 DynIntArray new_xrefs;
113 static SgenHashTable hash_table = SGEN_HASH_TABLE_INIT (INTERNAL_MEM_BRIDGE_HASH_TABLE, INTERNAL_MEM_BRIDGE_HASH_TABLE_ENTRY, sizeof (HashEntry), mono_aligned_addr_hash, NULL);
115 static guint32 current_time;
117 static gboolean bridge_accounting_enabled = FALSE;
119 static SgenBridgeProcessor *bridge_processor;
127 dyn_array_init (DynArray *da)
135 dyn_array_uninit (DynArray *da, int elem_size)
137 if (da->capacity < 0) {
142 if (da->capacity == 0)
145 sgen_free_internal_dynamic (da->data, elem_size * da->capacity, INTERNAL_MEM_BRIDGE_DATA);
150 dyn_array_empty (DynArray *da)
152 if (da->capacity < 0)
159 dyn_array_ensure_capacity (DynArray *da, int capacity, int elem_size)
161 int old_capacity = da->capacity;
164 g_assert (capacity > 0);
166 if (capacity <= old_capacity)
169 if (old_capacity <= 0)
171 while (capacity > da->capacity)
174 new_data = (char *)sgen_alloc_internal_dynamic (elem_size * da->capacity, INTERNAL_MEM_BRIDGE_DATA, TRUE);
175 memcpy (new_data, da->data, elem_size * da->size);
176 if (old_capacity > 0)
177 sgen_free_internal_dynamic (da->data, elem_size * old_capacity, INTERNAL_MEM_BRIDGE_DATA);
182 dyn_array_is_copy (DynArray *da)
184 return da->capacity < 0;
188 dyn_array_ensure_independent (DynArray *da, int elem_size)
190 if (!dyn_array_is_copy (da))
192 dyn_array_ensure_capacity (da, da->size, elem_size);
193 g_assert (da->capacity > 0);
197 dyn_array_add (DynArray *da, int elem_size)
201 dyn_array_ensure_capacity (da, da->size + 1, elem_size);
203 p = da->data + da->size * elem_size;
209 dyn_array_copy (DynArray *dst, DynArray *src, int elem_size)
211 dyn_array_uninit (dst, elem_size);
216 dst->size = src->size;
218 dst->data = src->data;
223 dyn_array_int_init (DynIntArray *da)
225 dyn_array_init (&da->array);
229 dyn_array_int_uninit (DynIntArray *da)
231 dyn_array_uninit (&da->array, sizeof (int));
235 dyn_array_int_size (DynIntArray *da)
237 return da->array.size;
242 dyn_array_int_empty (DynIntArray *da)
244 dyn_array_empty (&da->array);
249 dyn_array_int_add (DynIntArray *da, int x)
251 int *p = (int *)dyn_array_add (&da->array, sizeof (int));
256 dyn_array_int_get (DynIntArray *da, int x)
258 return ((int*)da->array.data)[x];
263 dyn_array_int_set (DynIntArray *da, int idx, int val)
265 ((int*)da->array.data)[idx] = val;
270 dyn_array_int_ensure_independent (DynIntArray *da)
272 dyn_array_ensure_independent (&da->array, sizeof (int));
276 dyn_array_int_copy (DynIntArray *dst, DynIntArray *src)
278 dyn_array_copy (&dst->array, &src->array, sizeof (int));
282 dyn_array_int_is_copy (DynIntArray *da)
284 return dyn_array_is_copy (&da->array);
290 dyn_array_ptr_init (DynPtrArray *da)
292 dyn_array_init (&da->array);
296 dyn_array_ptr_uninit (DynPtrArray *da)
298 #ifdef OPTIMIZATION_SINGLETON_DYN_ARRAY
299 if (da->array.capacity == 1)
300 dyn_array_ptr_init (da);
303 dyn_array_uninit (&da->array, sizeof (void*));
307 dyn_array_ptr_size (DynPtrArray *da)
309 return da->array.size;
313 dyn_array_ptr_empty (DynPtrArray *da)
315 #ifdef OPTIMIZATION_SINGLETON_DYN_ARRAY
316 if (da->array.capacity == 1)
317 dyn_array_ptr_init (da);
320 dyn_array_empty (&da->array);
324 dyn_array_ptr_get (DynPtrArray *da, int x)
326 #ifdef OPTIMIZATION_SINGLETON_DYN_ARRAY
327 if (da->array.capacity == 1) {
329 return da->array.data;
332 return ((void**)da->array.data)[x];
336 dyn_array_ptr_add (DynPtrArray *da, void *ptr)
340 #ifdef OPTIMIZATION_SINGLETON_DYN_ARRAY
341 if (da->array.capacity == 0) {
342 da->array.capacity = 1;
344 p = (void**)&da->array.data;
345 } else if (da->array.capacity == 1) {
346 void *ptr0 = da->array.data;
348 dyn_array_init (&da->array);
349 p0 = (void **)dyn_array_add (&da->array, sizeof (void*));
351 p = (void **)dyn_array_add (&da->array, sizeof (void*));
355 p = (void **)dyn_array_add (&da->array, sizeof (void*));
360 #define dyn_array_ptr_push dyn_array_ptr_add
363 dyn_array_ptr_pop (DynPtrArray *da)
365 int size = da->array.size;
368 #ifdef OPTIMIZATION_SINGLETON_DYN_ARRAY
369 if (da->array.capacity == 1) {
370 p = dyn_array_ptr_get (da, 0);
371 dyn_array_init (&da->array);
375 g_assert (da->array.capacity > 1);
376 dyn_array_ensure_independent (&da->array, sizeof (void*));
377 p = dyn_array_ptr_get (da, size - 1);
386 dyn_array_scc_init (DynSCCArray *da)
388 dyn_array_init (&da->array);
392 dyn_array_scc_uninit (DynSCCArray *da)
394 dyn_array_uninit (&da->array, sizeof (SCC));
398 dyn_array_scc_size (DynSCCArray *da)
400 return da->array.size;
404 dyn_array_scc_add (DynSCCArray *da)
406 return (SCC *)dyn_array_add (&da->array, sizeof (SCC));
410 dyn_array_scc_get_ptr (DynSCCArray *da, int x)
412 return &((SCC*)da->array.data)[x];
417 static DynIntArray merge_array;
421 dyn_array_int_contains (DynIntArray *da, int x)
424 for (i = 0; i < dyn_array_int_size (da); ++i)
425 if (dyn_array_int_get (da, i) == x)
432 enable_accounting (void)
434 SgenHashTable table = SGEN_HASH_TABLE_INIT (INTERNAL_MEM_BRIDGE_HASH_TABLE, INTERNAL_MEM_BRIDGE_HASH_TABLE_ENTRY, sizeof (HashEntryWithAccounting), mono_aligned_addr_hash, NULL);
435 bridge_accounting_enabled = TRUE;
439 static MonoGCBridgeObjectKind
440 class_kind (MonoClass *klass)
442 MonoGCBridgeObjectKind res = bridge_callbacks.bridge_class_kind (klass);
444 /* If it's a bridge, nothing we can do about it. */
445 if (res == GC_BRIDGE_TRANSPARENT_BRIDGE_CLASS || res == GC_BRIDGE_OPAQUE_BRIDGE_CLASS)
448 /* Non bridge classes with no pointers will never point to a bridge, so we can savely ignore them. */
449 if (!klass->has_references) {
450 SGEN_LOG (6, "class %s is opaque\n", klass->name);
451 return GC_BRIDGE_OPAQUE_CLASS;
454 /* Some arrays can be ignored */
455 if (klass->rank == 1) {
456 MonoClass *elem_class = klass->element_class;
458 /* FIXME the bridge check can be quite expensive, cache it at the class level. */
459 /* An array of a sealed type that is not a bridge will never get to a bridge */
460 if ((elem_class->flags & TYPE_ATTRIBUTE_SEALED) && !elem_class->has_references && !bridge_callbacks.bridge_class_kind (elem_class)) {
461 SGEN_LOG (6, "class %s is opaque\n", klass->name);
462 return GC_BRIDGE_OPAQUE_CLASS;
466 return GC_BRIDGE_TRANSPARENT_CLASS;
470 get_hash_entry (MonoObject *obj, gboolean *existing)
472 HashEntry *entry = (HashEntry *)sgen_hash_table_lookup (&hash_table, obj);
483 memset (&new_entry, 0, sizeof (HashEntry));
485 dyn_array_ptr_init (&new_entry.srcs);
486 new_entry.v.dfs1.finishing_time = 0;
488 sgen_hash_table_replace (&hash_table, obj, &new_entry, NULL);
490 return (HashEntry *)sgen_hash_table_lookup (&hash_table, obj);
494 add_source (HashEntry *entry, HashEntry *src)
496 dyn_array_ptr_add (&entry->srcs, src);
502 MonoObject *obj G_GNUC_UNUSED;
507 SGEN_HASH_TABLE_FOREACH (&hash_table, MonoObject *, obj, HashEntry *, entry) {
508 int entry_size = dyn_array_ptr_size (&entry->srcs);
509 total_srcs += entry_size;
510 if (entry_size > max_srcs)
511 max_srcs = entry_size;
512 dyn_array_ptr_uninit (&entry->srcs);
513 } SGEN_HASH_TABLE_FOREACH_END;
515 sgen_hash_table_clean (&hash_table);
517 dyn_array_int_uninit (&merge_array);
518 //g_print ("total srcs %d - max %d\n", total_srcs, max_srcs);
522 register_bridge_object (MonoObject *obj)
524 HashEntry *entry = get_hash_entry (obj, NULL);
525 entry->is_bridge = TRUE;
530 register_finishing_time (HashEntry *entry, guint32 t)
532 g_assert (entry->v.dfs1.finishing_time == 0);
533 /* finishing_time has 31 bits, so it must be within signed int32 range. */
534 g_assert (t > 0 && t <= G_MAXINT32);
535 entry->v.dfs1.finishing_time = t;
538 static int ignored_objects;
541 is_opaque_object (MonoObject *obj)
543 if ((obj->vtable->gc_bits & SGEN_GC_BIT_BRIDGE_OPAQUE_OBJECT) == SGEN_GC_BIT_BRIDGE_OPAQUE_OBJECT) {
544 SGEN_LOG (6, "ignoring %s\n", obj->vtable->klass->name);
552 object_needs_expansion (MonoObject **objp)
554 MonoObject *obj = *objp;
555 MonoObject *fwd = SGEN_OBJECT_IS_FORWARDED (obj);
558 if (is_opaque_object (fwd))
560 return sgen_hash_table_lookup (&hash_table, fwd) != NULL;
562 if (is_opaque_object (obj))
564 if (!sgen_object_is_live (obj))
566 return sgen_hash_table_lookup (&hash_table, obj) != NULL;
570 follow_forward (HashEntry *entry)
572 #ifdef OPTIMIZATION_FORWARD
573 while (entry->v.dfs1.forwarded_to) {
574 HashEntry *next = entry->v.dfs1.forwarded_to;
575 if (next->v.dfs1.forwarded_to)
576 entry->v.dfs1.forwarded_to = next->v.dfs1.forwarded_to;
580 g_assert (!entry->v.dfs1.forwarded_to);
585 static DynPtrArray registered_bridges;
586 static DynPtrArray dfs_stack;
588 static int dfs1_passes, dfs2_passes;
591 * DFS1 maintains a stack, where each two entries are effectively one entry. (FIXME:
592 * Optimize this via pointer tagging.) There are two different types of entries:
594 * entry, src: entry needs to be expanded via scanning, and linked to from src
595 * NULL, entry: entry has already been expanded and needs to be finished
599 #define HANDLE_PTR(ptr,obj) do { \
600 GCObject *dst = (GCObject*)*(ptr); \
601 if (dst && object_needs_expansion (&dst)) { \
603 dyn_array_ptr_push (&dfs_stack, obj_entry); \
604 dyn_array_ptr_push (&dfs_stack, follow_forward (get_hash_entry (dst, NULL))); \
609 dfs1 (HashEntry *obj_entry)
612 g_assert (dyn_array_ptr_size (&dfs_stack) == 0);
614 dyn_array_ptr_push (&dfs_stack, NULL);
615 dyn_array_ptr_push (&dfs_stack, obj_entry);
622 obj_entry = (HashEntry *)dyn_array_ptr_pop (&dfs_stack);
624 /* obj_entry needs to be expanded */
625 src = (HashEntry *)dyn_array_ptr_pop (&dfs_stack);
628 g_assert (!src->v.dfs1.forwarded_to);
630 obj_entry = follow_forward (obj_entry);
633 g_assert (!obj_entry->v.dfs1.forwarded_to);
634 obj = sgen_hash_table_key_for_value_pointer (obj_entry);
637 if (!obj_entry->v.dfs1.is_visited) {
639 mword desc = sgen_obj_get_descriptor_safe (obj);
641 obj_entry->v.dfs1.is_visited = 1;
643 /* push the finishing entry on the stack */
644 dyn_array_ptr_push (&dfs_stack, obj_entry);
645 dyn_array_ptr_push (&dfs_stack, NULL);
647 #include "sgen/sgen-scan-object.h"
650 * We can remove non-bridge objects with a single outgoing
651 * link by forwarding links going to it.
653 * This is the first time we've encountered this object, so
654 * no links to it have yet been added. We'll keep it that
655 * way by setting the forward pointer, and instead of
656 * continuing processing this object, we start over with the
657 * object it points to.
659 #ifdef OPTIMIZATION_FORWARD
660 if (!obj_entry->is_bridge && num_links == 1) {
661 HashEntry *dst_entry = (HashEntry *)dyn_array_ptr_pop (&dfs_stack);
662 HashEntry *obj_entry_again = (HashEntry *)dyn_array_ptr_pop (&dfs_stack);
663 g_assert (obj_entry_again == obj_entry);
664 g_assert (!dst_entry->v.dfs1.forwarded_to);
665 if (obj_entry != dst_entry) {
666 obj_entry->v.dfs1.forwarded_to = dst_entry;
667 obj_entry = dst_entry;
675 //g_print ("link %s -> %s\n", sgen_safe_name (src->obj), sgen_safe_name (obj));
676 g_assert (!obj_entry->v.dfs1.forwarded_to);
677 add_source (obj_entry, src);
679 //g_print ("starting with %s\n", sgen_safe_name (obj));
682 /* obj_entry needs to be finished */
684 obj_entry = (HashEntry *)dyn_array_ptr_pop (&dfs_stack);
686 //g_print ("finish %s\n", sgen_safe_name (obj_entry->obj));
687 register_finishing_time (obj_entry, ++current_time);
689 } while (dyn_array_ptr_size (&dfs_stack) > 0);
692 static DynSCCArray sccs;
693 static SCC *current_scc;
696 * At the end of bridge processing we need to end up with an (acyclyc) graph of bridge
697 * object SCCs, where the links between the nodes (each one an SCC) in that graph represent
698 * the presence of a direct or indirect link between those SCCs. An example:
703 * A -> B -> c -> e -> F
705 * A, B, D and F are SCCs that contain bridge objects, c and e don't contain bridge objects.
706 * The graph we need to produce from this is:
713 * Note that we don't need to produce an edge from A to F. It's sufficient that F is
714 * indirectly reachable from A.
716 * The old algorithm would create a set, for each SCC, of bridge SCCs that can reach it,
717 * directly or indirectly, by merging the ones sets for those that reach it directly. The
718 * sets it would build up are these:
727 * The merge operations on these sets turned out to be huge time sinks.
729 * The new algorithm proceeds in two passes: During DFS2, it only builds up the sets of SCCs
730 * that directly point to each SCC:
739 * This is the adjacency list for the SCC graph, in other words. In a separate step
740 * afterwards, it does a depth-first traversal of that graph, for each bridge node, to get
741 * to the final list. It uses a flag to avoid traversing any node twice.
744 scc_add_xref (SCC *src, SCC *dst)
746 g_assert (src != dst);
747 g_assert (src->index != dst->index);
751 * FIXME: Right now we don't even unique the direct ancestors, but just add to the
752 * list. Doing a containment check slows this algorithm down to almost the speed of
753 * the old one. Use the flag instead!
755 dyn_array_int_add (&dst->new_xrefs, src->index);
759 if (dyn_array_int_is_copy (&dst->old_xrefs)) {
761 dyn_array_int_ensure_independent (&dst->old_xrefs);
762 for (i = 0; i < dyn_array_int_size (&dst->old_xrefs); ++i) {
763 int j = dyn_array_int_get (&dst->old_xrefs, i);
764 SCC *bridge_scc = dyn_array_scc_get_ptr (&sccs, j);
765 g_assert (!bridge_scc->flag);
766 bridge_scc->flag = TRUE;
770 if (src->num_bridge_entries) {
774 dyn_array_int_add (&dst->old_xrefs, src->index);
775 #ifdef OPTIMIZATION_COPY
776 } else if (dyn_array_int_size (&dst->old_xrefs) == 0) {
777 dyn_array_int_copy (&dst->old_xrefs, &src->old_xrefs);
781 for (i = 0; i < dyn_array_int_size (&src->old_xrefs); ++i) {
782 int j = dyn_array_int_get (&src->old_xrefs, i);
783 SCC *bridge_scc = dyn_array_scc_get_ptr (&sccs, j);
784 g_assert (bridge_scc->num_bridge_entries);
785 if (!bridge_scc->flag) {
786 bridge_scc->flag = TRUE;
787 dyn_array_int_add (&dst->old_xrefs, j);
795 scc_add_entry (SCC *scc, HashEntry *entry)
797 g_assert (entry->v.dfs2.scc_index < 0);
798 entry->v.dfs2.scc_index = scc->index;
799 if (entry->is_bridge)
800 ++scc->num_bridge_entries;
804 dfs2 (HashEntry *entry)
808 g_assert (dyn_array_ptr_size (&dfs_stack) == 0);
810 dyn_array_ptr_push (&dfs_stack, entry);
813 entry = (HashEntry *)dyn_array_ptr_pop (&dfs_stack);
816 if (entry->v.dfs2.scc_index >= 0) {
817 if (entry->v.dfs2.scc_index != current_scc->index)
818 scc_add_xref (dyn_array_scc_get_ptr (&sccs, entry->v.dfs2.scc_index), current_scc);
822 scc_add_entry (current_scc, entry);
824 for (i = 0; i < dyn_array_ptr_size (&entry->srcs); ++i)
825 dyn_array_ptr_push (&dfs_stack, dyn_array_ptr_get (&entry->srcs, i));
826 } while (dyn_array_ptr_size (&dfs_stack) > 0);
829 /* If xrefs is a copy then we haven't set a single flag. */
830 if (dyn_array_int_is_copy (¤t_scc->old_xrefs))
832 for (i = 0; i < dyn_array_int_size (¤t_scc->old_xrefs); ++i) {
833 int j = dyn_array_int_get (¤t_scc->old_xrefs, i);
834 SCC *bridge_scc = dyn_array_scc_get_ptr (&sccs, j);
835 g_assert (bridge_scc->flag);
836 bridge_scc->flag = FALSE;
843 gather_xrefs (SCC *scc)
846 for (i = 0; i < dyn_array_int_size (&scc->new_xrefs); ++i) {
847 int index = dyn_array_int_get (&scc->new_xrefs, i);
848 SCC *src = dyn_array_scc_get_ptr (&sccs, index);
852 if (src->num_bridge_entries)
853 dyn_array_int_add (&merge_array, index);
860 reset_flags (SCC *scc)
863 for (i = 0; i < dyn_array_int_size (&scc->new_xrefs); ++i) {
864 int index = dyn_array_int_get (&scc->new_xrefs, i);
865 SCC *src = dyn_array_scc_get_ptr (&sccs, index);
869 if (!src->num_bridge_entries)
875 static char *dump_prefix = NULL;
880 static int counter = 0;
884 size_t prefix_len = strlen (dump_prefix);
885 char *filename = (char *)alloca (prefix_len + 64);
889 sprintf (filename, "%s.%d.gexf", dump_prefix, counter++);
890 file = fopen (filename, "w");
893 fprintf (stderr, "Warning: Could not open bridge dump file `%s` for writing: %s\n", filename, strerror (errno));
897 fprintf (file, "<gexf xmlns=\"http://www.gexf.net/1.2draft\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xsi:schemaLocation=\"http://www.gexf.net/1.2draft http://www.gexf.net/1.2draft/gexf.xsd\" version=\"1.2\">\n");
899 fprintf (file, "<graph defaultedgetype=\"directed\">\n"
900 "<attributes class=\"node\">\n"
901 "<attribute id=\"0\" title=\"class\" type=\"string\"/>\n"
902 "<attribute id=\"1\" title=\"bridge\" type=\"boolean\"/>\n"
905 fprintf (file, "<nodes>\n");
906 SGEN_HASH_TABLE_FOREACH (&hash_table, MonoObject *, obj, HashEntry *, entry) {
907 MonoVTable *vt = SGEN_LOAD_VTABLE (obj);
908 fprintf (file, "<node id=\"%p\"><attvalues><attvalue for=\"0\" value=\"%s.%s\"/><attvalue for=\"1\" value=\"%s\"/></attvalues></node>\n",
909 obj, vt->klass->name_space, vt->klass->name, entry->is_bridge ? "true" : "false");
910 } SGEN_HASH_TABLE_FOREACH_END;
911 fprintf (file, "</nodes>\n");
913 fprintf (file, "<edges>\n");
914 SGEN_HASH_TABLE_FOREACH (&hash_table, MonoObject *, obj, HashEntry *, entry) {
916 for (i = 0; i < dyn_array_ptr_size (&entry->srcs); ++i) {
917 HashEntry *src = (HashEntry *)dyn_array_ptr_get (&entry->srcs, i);
918 fprintf (file, "<edge id=\"%d\" source=\"%p\" target=\"%p\"/>\n", edge_id++, sgen_hash_table_key_for_value_pointer (src), obj);
920 } SGEN_HASH_TABLE_FOREACH_END;
921 fprintf (file, "</edges>\n");
923 fprintf (file, "</graph></gexf>\n");
929 set_dump_prefix (const char *prefix)
931 dump_prefix = strdup (prefix);
935 compare_hash_entries (const HashEntry *e1, const HashEntry *e2)
937 /* We can cast to signed int here because finishing_time has only 31 bits. */
938 return (gint32)e2->v.dfs1.finishing_time - (gint32)e1->v.dfs1.finishing_time;
941 DEF_QSORT_INLINE(hash_entries, HashEntry*, compare_hash_entries)
943 static gint64 step_1, step_2, step_3, step_4, step_5, step_6;
944 static int fist_pass_links, second_pass_links, sccs_links;
945 static int max_sccs_links = 0;
948 register_finalized_object (GCObject *obj)
950 g_assert (sgen_need_bridge_processing ());
951 dyn_array_ptr_push (®istered_bridges, obj);
957 dyn_array_ptr_empty (®istered_bridges);
961 processing_stw_step (void)
965 MonoObject *obj G_GNUC_UNUSED;
967 SGEN_TV_DECLARE (atv);
968 SGEN_TV_DECLARE (btv);
970 if (!dyn_array_ptr_size (®istered_bridges))
973 SGEN_TV_GETTIME (btv);
977 dyn_array_ptr_init (&dfs_stack);
978 dyn_array_int_init (&merge_array);
982 First we insert all bridges into the hash table and then we do dfs1.
984 It must be done in 2 steps since the bridge arrays doesn't come in reverse topological order,
985 which means that we can have entry N pointing to entry N + 1.
987 If we dfs1 entry N before N + 1 is registered we'll not consider N + 1 for this bridge
988 pass and not create the required xref between the two.
990 bridge_count = dyn_array_ptr_size (®istered_bridges);
991 for (i = 0; i < bridge_count ; ++i)
992 register_bridge_object ((MonoObject *)dyn_array_ptr_get (®istered_bridges, i));
994 for (i = 0; i < bridge_count; ++i)
995 dfs1 (get_hash_entry ((MonoObject *)dyn_array_ptr_get (®istered_bridges, i), NULL));
997 /* Remove all forwarded objects. */
998 SGEN_HASH_TABLE_FOREACH (&hash_table, MonoObject *, obj, HashEntry *, entry) {
999 if (entry->v.dfs1.forwarded_to) {
1000 g_assert (dyn_array_ptr_size (&entry->srcs) == 0);
1001 SGEN_HASH_TABLE_FOREACH_REMOVE (TRUE);
1004 } SGEN_HASH_TABLE_FOREACH_END;
1006 SGEN_TV_GETTIME (atv);
1007 step_2 = SGEN_TV_ELAPSED (btv, atv);
1013 static int num_registered_bridges, hash_table_size;
1016 processing_build_callback_data (int generation)
1019 int num_sccs, num_xrefs;
1020 int max_entries, max_xrefs;
1021 MonoObject *obj G_GNUC_UNUSED;
1023 HashEntry **all_entries;
1024 MonoGCBridgeSCC **api_sccs;
1025 MonoGCBridgeXRef *api_xrefs;
1026 SGEN_TV_DECLARE (atv);
1027 SGEN_TV_DECLARE (btv);
1029 g_assert (bridge_processor->num_sccs == 0 && bridge_processor->num_xrefs == 0);
1030 g_assert (!bridge_processor->api_sccs && !bridge_processor->api_xrefs);
1032 if (!dyn_array_ptr_size (®istered_bridges))
1035 g_assert (bridge_processing_in_progress);
1037 SGEN_TV_GETTIME (atv);
1039 /* alloc and fill array of all entries */
1041 all_entries = (HashEntry **)sgen_alloc_internal_dynamic (sizeof (HashEntry*) * hash_table.num_entries, INTERNAL_MEM_BRIDGE_DATA, TRUE);
1044 SGEN_HASH_TABLE_FOREACH (&hash_table, MonoObject *, obj, HashEntry *, entry) {
1045 g_assert (entry->v.dfs1.finishing_time > 0);
1046 all_entries [j++] = entry;
1047 fist_pass_links += dyn_array_ptr_size (&entry->srcs);
1048 } SGEN_HASH_TABLE_FOREACH_END;
1049 g_assert (j == hash_table.num_entries);
1050 hash_table_size = hash_table.num_entries;
1052 /* sort array according to decreasing finishing time */
1053 qsort_hash_entries (all_entries, hash_table.num_entries);
1055 SGEN_HASH_TABLE_FOREACH (&hash_table, MonoObject *, obj, HashEntry *, entry) {
1056 entry->v.dfs2.scc_index = -1;
1057 } SGEN_HASH_TABLE_FOREACH_END;
1059 SGEN_TV_GETTIME (btv);
1060 step_3 = SGEN_TV_ELAPSED (atv, btv);
1062 /* second DFS pass */
1064 dyn_array_scc_init (&sccs);
1065 for (i = 0; i < hash_table.num_entries; ++i) {
1066 HashEntry *entry = all_entries [i];
1067 if (entry->v.dfs2.scc_index < 0) {
1068 int index = dyn_array_scc_size (&sccs);
1069 current_scc = dyn_array_scc_add (&sccs);
1070 current_scc->index = index;
1071 current_scc->num_bridge_entries = 0;
1073 current_scc->flag = FALSE;
1074 dyn_array_int_init (¤t_scc->new_xrefs);
1077 dyn_array_int_init (¤t_scc->old_xrefs);
1079 current_scc->api_index = -1;
1085 * If a node has only one incoming edge, we just copy the source's
1086 * xrefs array, effectively removing the source from the graph.
1087 * This takes care of long linked lists.
1089 if (!current_scc->num_bridge_entries && dyn_array_int_size (¤t_scc->new_xrefs) == 1) {
1091 j = dyn_array_int_get (¤t_scc->new_xrefs, 0);
1092 src = dyn_array_scc_get_ptr (&sccs, j);
1093 if (src->num_bridge_entries)
1094 dyn_array_int_set (¤t_scc->new_xrefs, 0, j);
1096 dyn_array_int_copy (¤t_scc->new_xrefs, &src->new_xrefs);
1103 #ifdef TEST_NEW_XREFS
1104 for (j = 0; j < dyn_array_scc_size (&sccs); ++j) {
1105 SCC *scc = dyn_array_scc_get_ptr (&sccs, j);
1106 g_assert (!scc->flag);
1110 for (i = 0; i < dyn_array_scc_size (&sccs); ++i) {
1111 SCC *scc = dyn_array_scc_get_ptr (&sccs, i);
1112 g_assert (scc->index == i);
1113 if (!scc->num_bridge_entries)
1116 dyn_array_int_empty (&merge_array);
1119 dyn_array_int_copy (&scc->new_xrefs, &merge_array);
1120 dyn_array_int_ensure_independent (&scc->new_xrefs);
1122 #ifdef TEST_NEW_XREFS
1123 for (j = 0; j < dyn_array_scc_size (&sccs); ++j) {
1124 SCC *scc = dyn_array_scc_get_ptr (&sccs, j);
1125 g_assert (!scc->flag);
1130 #ifdef TEST_NEW_XREFS
1131 for (i = 0; i < dyn_array_scc_size (&sccs); ++i) {
1132 SCC *scc = dyn_array_scc_get_ptr (&sccs, i);
1133 g_assert (scc->index == i);
1134 if (!scc->num_bridge_entries)
1137 g_assert (dyn_array_int_size (&scc->new_xrefs) == dyn_array_int_size (&scc->old_xrefs));
1138 for (j = 0; j < dyn_array_int_size (&scc->new_xrefs); ++j)
1139 g_assert (dyn_array_int_contains (&scc->old_xrefs, dyn_array_int_get (&scc->new_xrefs, j)));
1145 * Compute the weight of each object. The weight of an object is its size plus the size of all
1146 * objects it points do. When the an object is pointed by multiple objects we distribute it's weight
1147 * equally among them. This distribution gives a rough estimate of the real impact of making the object
1150 * The reasoning for this model is that complex graphs with single roots will have a bridge with very high
1151 * value in comparison to others.
1153 * The all_entries array has all objects topologically sorted. To correctly propagate the weights it must be
1154 * done in reverse topological order - so we calculate the weight of the pointed-to objects before processing
1155 * pointer-from objects.
1157 * We log those objects in the opposite order for no particular reason. The other constrain is that it should use the same
1158 * direction as the other logging loop that records live/dead information.
1160 if (bridge_accounting_enabled) {
1161 for (i = hash_table.num_entries - 1; i >= 0; --i) {
1163 HashEntryWithAccounting *entry = (HashEntryWithAccounting*)all_entries [i];
1165 entry->weight += (double)sgen_safe_object_get_size (sgen_hash_table_key_for_value_pointer (entry));
1166 w = entry->weight / dyn_array_ptr_size (&entry->entry.srcs);
1167 for (j = 0; j < dyn_array_ptr_size (&entry->entry.srcs); ++j) {
1168 HashEntryWithAccounting *other = (HashEntryWithAccounting *)dyn_array_ptr_get (&entry->entry.srcs, j);
1172 for (i = 0; i < hash_table.num_entries; ++i) {
1173 HashEntryWithAccounting *entry = (HashEntryWithAccounting*)all_entries [i];
1174 if (entry->entry.is_bridge) {
1175 MonoObject *obj = sgen_hash_table_key_for_value_pointer (entry);
1176 MonoClass *klass = SGEN_LOAD_VTABLE (obj)->klass;
1177 mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_GC, "OBJECT %s::%s (%p) weight %f", klass->name_space, klass->name, obj, entry->weight);
1182 for (i = 0; i < hash_table.num_entries; ++i) {
1183 HashEntry *entry = all_entries [i];
1184 second_pass_links += dyn_array_ptr_size (&entry->srcs);
1187 SGEN_TV_GETTIME (atv);
1188 step_4 = SGEN_TV_ELAPSED (btv, atv);
1190 //g_print ("%d sccs\n", sccs.size);
1192 dyn_array_ptr_uninit (&dfs_stack);
1194 /* init data for callback */
1197 for (i = 0; i < dyn_array_scc_size (&sccs); ++i) {
1198 SCC *scc = dyn_array_scc_get_ptr (&sccs, i);
1199 g_assert (scc->index == i);
1200 if (scc->num_bridge_entries)
1202 sccs_links += dyn_array_int_size (&scc->XREFS);
1203 max_sccs_links = MAX (max_sccs_links, dyn_array_int_size (&scc->XREFS));
1206 api_sccs = (MonoGCBridgeSCC **)sgen_alloc_internal_dynamic (sizeof (MonoGCBridgeSCC*) * num_sccs, INTERNAL_MEM_BRIDGE_DATA, TRUE);
1209 for (i = 0; i < dyn_array_scc_size (&sccs); ++i) {
1210 SCC *scc = dyn_array_scc_get_ptr (&sccs, i);
1211 if (!scc->num_bridge_entries)
1214 api_sccs [j] = (MonoGCBridgeSCC *)sgen_alloc_internal_dynamic (sizeof (MonoGCBridgeSCC) + sizeof (MonoObject*) * scc->num_bridge_entries, INTERNAL_MEM_BRIDGE_DATA, TRUE);
1215 api_sccs [j]->is_alive = FALSE;
1216 api_sccs [j]->num_objs = scc->num_bridge_entries;
1217 scc->num_bridge_entries = 0;
1218 scc->api_index = j++;
1220 num_xrefs += dyn_array_int_size (&scc->XREFS);
1223 SGEN_HASH_TABLE_FOREACH (&hash_table, MonoObject *, obj, HashEntry *, entry) {
1224 if (entry->is_bridge) {
1225 SCC *scc = dyn_array_scc_get_ptr (&sccs, entry->v.dfs2.scc_index);
1226 api_sccs [scc->api_index]->objs [scc->num_bridge_entries++] = sgen_hash_table_key_for_value_pointer (entry);
1228 } SGEN_HASH_TABLE_FOREACH_END;
1230 api_xrefs = (MonoGCBridgeXRef *)sgen_alloc_internal_dynamic (sizeof (MonoGCBridgeXRef) * num_xrefs, INTERNAL_MEM_BRIDGE_DATA, TRUE);
1232 for (i = 0; i < dyn_array_scc_size (&sccs); ++i) {
1234 SCC *scc = dyn_array_scc_get_ptr (&sccs, i);
1235 if (!scc->num_bridge_entries)
1237 for (k = 0; k < dyn_array_int_size (&scc->XREFS); ++k) {
1238 SCC *src_scc = dyn_array_scc_get_ptr (&sccs, dyn_array_int_get (&scc->XREFS, k));
1239 if (!src_scc->num_bridge_entries)
1241 api_xrefs [j].src_scc_index = src_scc->api_index;
1242 api_xrefs [j].dst_scc_index = scc->api_index;
1247 SGEN_TV_GETTIME (btv);
1248 step_5 = SGEN_TV_ELAPSED (atv, btv);
1253 max_entries = max_xrefs = 0;
1254 for (i = 0; i < dyn_array_scc_size (&sccs); ++i) {
1255 SCC *scc = dyn_array_scc_get_ptr (&sccs, i);
1256 if (scc->num_bridge_entries)
1258 if (scc->num_bridge_entries > max_entries)
1259 max_entries = scc->num_bridge_entries;
1260 if (dyn_array_int_size (&scc->XREFS) > max_xrefs)
1261 max_xrefs = dyn_array_int_size (&scc->XREFS);
1263 dyn_array_int_uninit (&scc->new_xrefs);
1266 dyn_array_int_uninit (&scc->old_xrefs);
1270 dyn_array_scc_uninit (&sccs);
1272 sgen_free_internal_dynamic (all_entries, sizeof (HashEntry*) * hash_table.num_entries, INTERNAL_MEM_BRIDGE_DATA);
1275 /* Empty the registered bridges array */
1276 num_registered_bridges = dyn_array_ptr_size (®istered_bridges);
1277 dyn_array_ptr_empty (®istered_bridges);
1279 SGEN_TV_GETTIME (atv);
1280 step_6 = SGEN_TV_ELAPSED (btv, atv);
1282 //g_print ("%d sccs containing bridges - %d max bridge objects - %d max xrefs\n", j, max_entries, max_xrefs);
1284 bridge_processor->num_sccs = num_sccs;
1285 bridge_processor->api_sccs = api_sccs;
1286 bridge_processor->num_xrefs = num_xrefs;
1287 bridge_processor->api_xrefs = api_xrefs;
1291 processing_after_callback (int generation)
1294 int num_sccs = bridge_processor->num_sccs;
1295 MonoGCBridgeSCC **api_sccs = bridge_processor->api_sccs;
1297 if (bridge_accounting_enabled) {
1298 for (i = 0; i < num_sccs; ++i) {
1299 for (j = 0; j < api_sccs [i]->num_objs; ++j) {
1300 GCVTable vtable = SGEN_LOAD_VTABLE (api_sccs [i]->objs [j]);
1301 mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_GC,
1302 "OBJECT %s (%p) SCC [%d] %s",
1303 sgen_client_vtable_get_namespace (vtable), sgen_client_vtable_get_name (vtable), api_sccs [i]->objs [j],
1305 api_sccs [i]->is_alive ? "ALIVE" : "DEAD");
1310 mono_trace (G_LOG_LEVEL_INFO, MONO_TRACE_GC, "GC_NEW_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 links %d/%d/%d/%d dfs passes %d/%d ignored %d",
1311 num_registered_bridges, hash_table_size, dyn_array_scc_size (&sccs),
1318 fist_pass_links, second_pass_links, sccs_links, max_sccs_links,
1319 dfs1_passes, dfs2_passes, ignored_objects);
1321 step_1 = 0; /* We must cleanup since this value is used as an accumulator. */
1322 fist_pass_links = second_pass_links = sccs_links = max_sccs_links = 0;
1323 dfs1_passes = dfs2_passes = ignored_objects = 0;
1327 describe_pointer (GCObject *obj)
1332 for (i = 0; i < dyn_array_ptr_size (®istered_bridges); ++i) {
1333 if (obj == dyn_array_ptr_get (®istered_bridges, i)) {
1334 printf ("Pointer is a registered bridge object.\n");
1339 entry = (HashEntry *)sgen_hash_table_lookup (&hash_table, obj);
1343 printf ("Bridge hash table entry %p:\n", entry);
1344 printf (" is bridge: %d\n", (int)entry->is_bridge);
1345 printf (" is visited: %d\n", (int)entry->v.dfs1.is_visited);
1349 sgen_new_bridge_init (SgenBridgeProcessor *collector)
1351 collector->reset_data = reset_data;
1352 collector->processing_stw_step = processing_stw_step;
1353 collector->processing_build_callback_data = processing_build_callback_data;
1354 collector->processing_after_callback = processing_after_callback;
1355 collector->class_kind = class_kind;
1356 collector->register_finalized_object = register_finalized_object;
1357 collector->describe_pointer = describe_pointer;
1358 collector->enable_accounting = enable_accounting;
1359 collector->set_dump_prefix = set_dump_prefix;
1361 bridge_processor = collector;