/*
+ * sgen-minor-copy-object.h: Copy functions for nursery collections.
+ *
* Copyright 2001-2003 Ximian, Inc
* Copyright 2003-2010 Novell, Inc.
- *
- * Permission is hereby granted, free of charge, to any person obtaining
- * a copy of this software and associated documentation files (the
- * "Software"), to deal in the Software without restriction, including
- * without limitation the rights to use, copy, modify, merge, publish,
- * distribute, sublicense, and/or sell copies of the Software, and to
- * permit persons to whom the Software is furnished to do so, subject to
- * the following conditions:
- *
- * The above copyright notice and this permission notice shall be
- * included in all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
- * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
- * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
- * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
- * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
- * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
- * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ * 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
-
-#define GENERATE_COPY_FUNCTIONS 1
+#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; \
+ (collector)->serial_ops.copy_or_mark_object = SERIAL_COPY_OBJECT; \
+ (collector)->parallel_ops.copy_or_mark_object = PARALLEL_COPY_OBJECT; \
} while (0)
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