/mono/metadata/sgen-minor-copy-object.h
C Header | 304 lines | 162 code | 46 blank | 96 comment | 31 complexity | 5ec177c254e0f2a68d49f9422357c392 MD5 | raw file
Possible License(s): Unlicense, Apache-2.0, LGPL-2.0, MPL-2.0-no-copyleft-exception, CC-BY-SA-3.0, GPL-2.0
- /*
- * sgen-minor-copy-object.h: Copy functions for nursery collections.
- *
- * Copyright 2001-2003 Ximian, Inc
- * Copyright 2003-2010 Novell, Inc.
- * Copyright (C) 2012 Xamarin Inc
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Library General Public
- * License 2.0 as published by the Free Software Foundation;
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Library General Public License for more details.
- *
- * You should have received a copy of the GNU Library General Public
- * License 2.0 along with this library; if not, write to the Free
- * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
- */
- #define collector_pin_object(obj, queue) sgen_pin_object (obj, queue);
- #define COLLECTOR_SERIAL_ALLOC_FOR_PROMOTION alloc_for_promotion
- #define COLLECTOR_PARALLEL_ALLOC_FOR_PROMOTION par_alloc_for_promotion
- extern long long stat_nursery_copy_object_failed_to_space; /* from sgen-gc.c */
- #include "sgen-copy-object.h"
- /*
- * This is how the copying happens from the nursery to the old generation.
- * We assume that at this time all the pinned objects have been identified and
- * marked as such.
- * We run scan_object() for each pinned object so that each referenced
- * objects if possible are copied. The new gray objects created can have
- * scan_object() run on them right away, too.
- * Then we run copy_object() for the precisely tracked roots. At this point
- * all the roots are either gray or black. We run scan_object() on the gray
- * objects until no more gray objects are created.
- * At the end of the process we walk again the pinned list and we unmark
- * the pinned flag. As we go we also create the list of free space for use
- * in the next allocation runs.
- *
- * We need to remember objects from the old generation that point to the new one
- * (or just addresses?).
- *
- * copy_object could be made into a macro once debugged (use inline for now).
- */
- #ifdef _MSC_VER
- static __forceinline void
- #else
- static inline void __attribute__((always_inline))
- #endif
- SERIAL_COPY_OBJECT (void **obj_slot, SgenGrayQueue *queue)
- {
- char *forwarded;
- char *obj = *obj_slot;
- SGEN_ASSERT (9, current_collection_generation == GENERATION_NURSERY, "calling minor-serial-copy from a %d generation collection", current_collection_generation);
- HEAVY_STAT (++stat_copy_object_called_nursery);
- if (!sgen_ptr_in_nursery (obj)) {
- HEAVY_STAT (++stat_nursery_copy_object_failed_from_space);
- return;
- }
- SGEN_LOG (9, "Precise copy of %p from %p", obj, obj_slot);
- /*
- * Before we can copy the object we must make sure that we are
- * allowed to, i.e. that the object not pinned, not already
- * forwarded or belongs to the nursery To Space.
- */
- if ((forwarded = SGEN_OBJECT_IS_FORWARDED (obj))) {
- SGEN_ASSERT (9, (*(MonoVTable**)SGEN_LOAD_VTABLE (obj))->gc_descr, "forwarded object %p has no gc descriptor", forwarded);
- SGEN_LOG (9, " (already forwarded to %p)", forwarded);
- HEAVY_STAT (++stat_nursery_copy_object_failed_forwarded);
- *obj_slot = forwarded;
- return;
- }
- if (G_UNLIKELY (SGEN_OBJECT_IS_PINNED (obj))) {
- SGEN_ASSERT (9, ((MonoVTable*)SGEN_LOAD_VTABLE(obj))->gc_descr, "pinned object %p has no gc descriptor", obj);
- SGEN_LOG (9, " (pinned, no change)");
- HEAVY_STAT (++stat_nursery_copy_object_failed_pinned);
- return;
- }
- #ifndef SGEN_SIMPLE_NURSERY
- if (sgen_nursery_is_to_space (obj)) {
- SGEN_ASSERT (9, ((MonoVTable*)SGEN_LOAD_VTABLE(obj))->gc_descr, "to space object %p has no gc descriptor", obj);
- SGEN_LOG (9, " (tospace, no change)");
- HEAVY_STAT (++stat_nursery_copy_object_failed_to_space);
- return;
- }
- #endif
- HEAVY_STAT (++stat_objects_copied_nursery);
- *obj_slot = copy_object_no_checks (obj, queue);
- }
- /*
- * SERIAL_COPY_OBJECT_FROM_OBJ:
- *
- * Similar to SERIAL_COPY_OBJECT, but assumes that OBJ_SLOT is part of an object, so it handles global remsets as well.
- */
- #ifdef _MSC_VER
- static __forceinline void
- #else
- static inline void __attribute__((always_inline))
- #endif
- SERIAL_COPY_OBJECT_FROM_OBJ (void **obj_slot, SgenGrayQueue *queue)
- {
- char *forwarded;
- char *obj = *obj_slot;
- void *copy;
- SGEN_ASSERT (9, current_collection_generation == GENERATION_NURSERY, "calling minor-serial-copy-from-obj from a %d generation collection", current_collection_generation);
- HEAVY_STAT (++stat_copy_object_called_nursery);
- if (!sgen_ptr_in_nursery (obj)) {
- HEAVY_STAT (++stat_nursery_copy_object_failed_from_space);
- return;
- }
- SGEN_LOG (9, "Precise copy of %p from %p", obj, obj_slot);
- /*
- * Before we can copy the object we must make sure that we are
- * allowed to, i.e. that the object not pinned, not already
- * forwarded or belongs to the nursery To Space.
- */
- if ((forwarded = SGEN_OBJECT_IS_FORWARDED (obj))) {
- SGEN_ASSERT (9, (*(MonoVTable**)SGEN_LOAD_VTABLE (obj))->gc_descr, "forwarded object %p has no gc descriptor", forwarded);
- SGEN_LOG (9, " (already forwarded to %p)", forwarded);
- HEAVY_STAT (++stat_nursery_copy_object_failed_forwarded);
- *obj_slot = forwarded;
- #ifndef SGEN_SIMPLE_NURSERY
- if (G_UNLIKELY (sgen_ptr_in_nursery (forwarded) && !sgen_ptr_in_nursery (obj_slot)))
- sgen_add_to_global_remset (obj_slot, forwarded);
- #endif
- return;
- }
- if (G_UNLIKELY (SGEN_OBJECT_IS_PINNED (obj))) {
- SGEN_ASSERT (9, ((MonoVTable*)SGEN_LOAD_VTABLE(obj))->gc_descr, "pinned object %p has no gc descriptor", obj);
- SGEN_LOG (9, " (pinned, no change)");
- HEAVY_STAT (++stat_nursery_copy_object_failed_pinned);
- if (!sgen_ptr_in_nursery (obj_slot))
- sgen_add_to_global_remset (obj_slot, obj);
- return;
- }
- #ifndef SGEN_SIMPLE_NURSERY
- if (sgen_nursery_is_to_space (obj)) {
- SGEN_ASSERT (9, ((MonoVTable*)SGEN_LOAD_VTABLE(obj))->gc_descr, "to space object %p has no gc descriptor", obj);
- SGEN_LOG (9, " (tospace, no change)");
- HEAVY_STAT (++stat_nursery_copy_object_failed_to_space);
- /*
- * FIXME:
- *
- * The card table scanning code sometimes clears cards
- * that have just been set for a global remset. In
- * the split nursery the following situation can
- * occur:
- *
- * Let's say object A starts in card C but continues
- * into C+1. Within A, at offset O there's a
- * reference to a new nursery object X. A+O is in
- * card C+1. Now card C is scanned, and as part of
- * it, object A. The reference at A+O is processed by
- * copying X into nursery to-space at Y. Since it's
- * still in the nursery, a global remset must be added
- * for A+O, so card C+1 is marked. Now, however, card
- * C+1 is scanned, which means that it's cleared
- * first. This wouldn't be terribly bad if reference
- * A+O were re-scanned and the global remset re-added,
- * but since the reference points to to-space, that
- * doesn't happen, and C+1 remains cleared: the remset
- * is lost.
- *
- * There's at least two ways to fix this. The easy
- * one is to re-add the remset on the re-scan. This
- * is that - the following two lines of code.
- *
- * The proper solution appears to be to first make a
- * copy of the cards before scanning a block, then to
- * clear all the cards and scan from the copy, so no
- * remsets will be overwritten. Scanning objects at
- * most once would be the icing on the cake.
- */
- if (!sgen_ptr_in_nursery (obj_slot))
- sgen_add_to_global_remset (obj_slot, obj);
- return;
- }
- #endif
- HEAVY_STAT (++stat_objects_copied_nursery);
- copy = copy_object_no_checks (obj, queue);
- *obj_slot = copy;
- #ifndef SGEN_SIMPLE_NURSERY
- if (G_UNLIKELY (sgen_ptr_in_nursery (copy) && !sgen_ptr_in_nursery (obj_slot)))
- sgen_add_to_global_remset (obj_slot, copy);
- #else
- /* copy_object_no_checks () can return obj on OOM */
- if (G_UNLIKELY (obj == copy)) {
- if (G_UNLIKELY (sgen_ptr_in_nursery (copy) && !sgen_ptr_in_nursery (obj_slot)))
- sgen_add_to_global_remset (obj_slot, copy);
- }
- #endif
- }
- static void
- PARALLEL_COPY_OBJECT (void **obj_slot, SgenGrayQueue *queue)
- {
- char *obj = *obj_slot;
- mword vtable_word, objsize;
- MonoVTable *vt;
- void *destination;
- gboolean has_references;
- SGEN_ASSERT (9, current_collection_generation == GENERATION_NURSERY, "calling minor-par-copy from a %d generation collection", current_collection_generation);
- HEAVY_STAT (++stat_copy_object_called_nursery);
- if (!sgen_ptr_in_nursery (obj)) {
- HEAVY_STAT (++stat_nursery_copy_object_failed_from_space);
- return;
- }
- vtable_word = *(mword*)obj;
- vt = (MonoVTable*)(vtable_word & ~SGEN_VTABLE_BITS_MASK);
- /*
- * Before we can copy the object we must make sure that we are
- * allowed to, i.e. that the object not pinned, not already
- * forwarded and not in the nursery To Space.
- */
- if (vtable_word & SGEN_FORWARDED_BIT) {
- HEAVY_STAT (++stat_nursery_copy_object_failed_forwarded);
- *obj_slot = vt;
- return;
- }
- if (vtable_word & SGEN_PINNED_BIT) {
- HEAVY_STAT (++stat_nursery_copy_object_failed_pinned);
- return;
- }
- if (sgen_nursery_is_to_space (obj)) {
- HEAVY_STAT (++stat_nursery_copy_object_failed_to_space);
- return;
- }
- HEAVY_STAT (++stat_objects_copied_nursery);
- objsize = SGEN_ALIGN_UP (sgen_par_object_get_size (vt, (MonoObject*)obj));
- has_references = SGEN_VTABLE_HAS_REFERENCES (vt);
- destination = COLLECTOR_PARALLEL_ALLOC_FOR_PROMOTION (vt, obj, objsize, has_references);
- if (G_UNLIKELY (!destination)) {
- sgen_parallel_pin_or_update (obj_slot, obj, vt, queue);
- return;
- }
- *(MonoVTable**)destination = vt;
- if (SGEN_CAS_PTR ((void*)obj, (void*)((mword)destination | SGEN_FORWARDED_BIT), vt) == vt) {
- par_copy_object_no_checks (destination, vt, obj, objsize, has_references ? queue : NULL);
- obj = destination;
- *obj_slot = obj;
- } else {
- /* FIXME: unify with code in major_copy_or_mark_object() */
- /* FIXME: Give destination back to the allocator. */
- /*The major collector only needs the first word zeroed and nursery requires all bits to be. */
- if (!sgen_ptr_in_nursery (destination))
- *(void**)destination = NULL;
- else
- memset (destination, 0, objsize);
- vtable_word = *(mword*)obj;
- g_assert (vtable_word & SGEN_FORWARDED_BIT);
- obj = (void*)(vtable_word & ~SGEN_VTABLE_BITS_MASK);
- *obj_slot = obj;
- HEAVY_STAT (++stat_slots_allocated_in_vain);
- }
- }
- #define FILL_MINOR_COLLECTOR_COPY_OBJECT(collector) do { \
- (collector)->serial_ops.copy_or_mark_object = SERIAL_COPY_OBJECT; \
- (collector)->parallel_ops.copy_or_mark_object = PARALLEL_COPY_OBJECT; \
- } while (0)