[amd64] Remove the callee saved registers from MonoLMF, save/restore them normally...

[mono-project.git] / mono / metadata / sgen-marksweep.c

/*
 * sgen-marksweep.c: The Mark & Sweep major collector.
 *
 * Author:
 *      Mark Probst <mark.probst@gmail.com>
 *
 * Copyright 2009-2010 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.
 */

#include "config.h"

#ifdef HAVE_SGEN_GC

#include <math.h>
#include <errno.h>

#include "utils/mono-counters.h"
#include "utils/mono-semaphore.h"
#include "utils/mono-time.h"
#include "metadata/object-internals.h"
#include "metadata/profiler-private.h"

#include "metadata/sgen-gc.h"
#include "metadata/sgen-protocol.h"
#include "metadata/sgen-cardtable.h"
#include "metadata/sgen-memory-governor.h"
#include "metadata/sgen-layout-stats.h"
#include "metadata/gc-internal.h"

#if !defined(SGEN_PARALLEL_MARK) && !defined(FIXED_HEAP)
#define SGEN_HAVE_CONCURRENT_MARK
#endif

#define MS_BLOCK_SIZE   (16*1024)
#define MS_BLOCK_SIZE_SHIFT     14
#define MAJOR_SECTION_SIZE      MS_BLOCK_SIZE
#define CARDS_PER_BLOCK (MS_BLOCK_SIZE / CARD_SIZE_IN_BYTES)

#ifdef FIXED_HEAP
#define MS_DEFAULT_HEAP_NUM_BLOCKS      (32 * 1024) /* 512 MB */
#endif

/*
 * Don't allocate single blocks, but alloc a contingent of this many
 * blocks in one swoop.  This must be a power of two.
 */
#define MS_BLOCK_ALLOC_NUM      32

/*
 * Number of bytes before the first object in a block.  At the start
 * of a block is the MSBlockHeader, then opional padding, then come
 * the objects, so this must be >= sizeof (MSBlockHeader).
 */
#ifdef FIXED_HEAP
#define MS_BLOCK_SKIP   0
#else
#define MS_BLOCK_SKIP   16
#endif

#define MS_BLOCK_FREE   (MS_BLOCK_SIZE - MS_BLOCK_SKIP)

#define MS_NUM_MARK_WORDS       ((MS_BLOCK_SIZE / SGEN_ALLOC_ALIGN + sizeof (mword) * 8 - 1) / (sizeof (mword) * 8))

#if SGEN_MAX_SMALL_OBJ_SIZE > MS_BLOCK_FREE / 2
#error MAX_SMALL_OBJ_SIZE must be at most MS_BLOCK_FREE / 2
#endif

typedef struct _MSBlockInfo MSBlockInfo;
struct _MSBlockInfo {
        int obj_size;
        int obj_size_index;
        size_t pin_queue_num_entries;
        unsigned int pinned : 1;
        unsigned int has_references : 1;
        unsigned int has_pinned : 1;    /* means cannot evacuate */
        unsigned int is_to_space : 1;
        unsigned int swept : 1;
#ifdef FIXED_HEAP
        unsigned int used : 1;
        unsigned int zeroed : 1;
#endif
        MSBlockInfo *next;
        char *block;
        void **free_list;
        MSBlockInfo *next_free;
        void **pin_queue_start;
#ifdef SGEN_HAVE_CONCURRENT_MARK
        guint8 *cardtable_mod_union;
#endif
        mword mark_words [MS_NUM_MARK_WORDS];
};

#ifdef FIXED_HEAP
static mword ms_heap_num_blocks = MS_DEFAULT_HEAP_NUM_BLOCKS;

static char *ms_heap_start;
static char *ms_heap_end;

#define MS_PTR_IN_SMALL_MAJOR_HEAP(p)   ((char*)(p) >= ms_heap_start && (char*)(p) < ms_heap_end)

/* array of all all block infos in the system */
static MSBlockInfo *block_infos;
#endif

#define MS_BLOCK_OBJ(b,i)               ((b)->block + MS_BLOCK_SKIP + (b)->obj_size * (i))
#define MS_BLOCK_OBJ_FOR_SIZE(b,i,obj_size)             ((b)->block + MS_BLOCK_SKIP + (obj_size) * (i))
#define MS_BLOCK_DATA_FOR_OBJ(o)        ((char*)((mword)(o) & ~(mword)(MS_BLOCK_SIZE - 1)))

#ifdef FIXED_HEAP
#define MS_BLOCK_FOR_OBJ(o)             (&block_infos [(mword)((char*)(o) - ms_heap_start) >> MS_BLOCK_SIZE_SHIFT])
#else
typedef struct {
        MSBlockInfo *info;
} MSBlockHeader;

#define MS_BLOCK_FOR_OBJ(o)             (((MSBlockHeader*)MS_BLOCK_DATA_FOR_OBJ ((o)))->info)
#endif

/* object index will always be small */
#define MS_BLOCK_OBJ_INDEX(o,b) ((int)(((char*)(o) - ((b)->block + MS_BLOCK_SKIP)) / (b)->obj_size))

//casting to int is fine since blocks are 32k
#define MS_CALC_MARK_BIT(w,b,o)         do {                            \
                int i = ((int)((char*)(o) - MS_BLOCK_DATA_FOR_OBJ ((o)))) >> SGEN_ALLOC_ALIGN_BITS; \
                if (sizeof (mword) == 4) {                              \
                        (w) = i >> 5;                                   \
                        (b) = i & 31;                                   \
                } else {                                                \
                        (w) = i >> 6;                                   \
                        (b) = i & 63;                                   \
                }                                                       \
        } while (0)

#define MS_MARK_BIT(bl,w,b)     ((bl)->mark_words [(w)] & (ONE_P << (b)))
#define MS_SET_MARK_BIT(bl,w,b) ((bl)->mark_words [(w)] |= (ONE_P << (b)))
#define MS_PAR_SET_MARK_BIT(was_marked,bl,w,b)  do {                    \
                mword __old = (bl)->mark_words [(w)];                   \
                mword __bitmask = ONE_P << (b);                         \
                if (__old & __bitmask) {                                \
                        was_marked = TRUE;                              \
                        break;                                          \
                }                                                       \
                if (SGEN_CAS_PTR ((gpointer*)&(bl)->mark_words [(w)],   \
                                                (gpointer)(__old | __bitmask), \
                                                (gpointer)__old) ==     \
                                (gpointer)__old) {                      \
                        was_marked = FALSE;                             \
                        break;                                          \
                }                                                       \
        } while (1)

#define MS_OBJ_ALLOCED(o,b)     (*(void**)(o) && (*(char**)(o) < (b)->block || *(char**)(o) >= (b)->block + MS_BLOCK_SIZE))

#define MS_BLOCK_OBJ_SIZE_FACTOR        (sqrt (2.0))

/*
 * This way we can lookup block object size indexes for sizes up to
 * 256 bytes with a single load.
 */
#define MS_NUM_FAST_BLOCK_OBJ_SIZE_INDEXES      32

static int *block_obj_sizes;
static int num_block_obj_sizes;
static int fast_block_obj_size_indexes [MS_NUM_FAST_BLOCK_OBJ_SIZE_INDEXES];

#define MS_BLOCK_FLAG_PINNED    1
#define MS_BLOCK_FLAG_REFS      2

#define MS_BLOCK_TYPE_MAX       4

#ifdef SGEN_PARALLEL_MARK
static LOCK_DECLARE (ms_block_list_mutex);
#define LOCK_MS_BLOCK_LIST mono_mutex_lock (&ms_block_list_mutex)
#define UNLOCK_MS_BLOCK_LIST mono_mutex_unlock (&ms_block_list_mutex)
#endif

static gboolean *evacuate_block_obj_sizes;
static float evacuation_threshold = 0.666f;
#ifdef SGEN_HAVE_CONCURRENT_MARK
static float concurrent_evacuation_threshold = 0.666f;
static gboolean want_evacuation = FALSE;
#endif

static gboolean lazy_sweep = TRUE;
static gboolean have_swept;

#ifdef SGEN_HAVE_CONCURRENT_MARK
static gboolean concurrent_mark;
#endif

/* all allocated blocks in the system */
static MSBlockInfo *all_blocks;

#ifdef FIXED_HEAP
/* non-allocated block free-list */
static MSBlockInfo *empty_blocks = NULL;
#else
/* non-allocated block free-list */
static void *empty_blocks = NULL;
static size_t num_empty_blocks = 0;
#endif

#define FOREACH_BLOCK(bl)       for ((bl) = all_blocks; (bl); (bl) = (bl)->next) {
#define END_FOREACH_BLOCK       }

static size_t num_major_sections = 0;
/* one free block list for each block object size */
static MSBlockInfo **free_block_lists [MS_BLOCK_TYPE_MAX];

#ifdef SGEN_PARALLEL_MARK
#ifdef HAVE_KW_THREAD
static __thread MSBlockInfo ***workers_free_block_lists;
#else
static MonoNativeTlsKey workers_free_block_lists_key;
#endif
#endif

static long long stat_major_blocks_alloced = 0;
static long long stat_major_blocks_freed = 0;
static long long stat_major_blocks_lazy_swept = 0;
static long long stat_major_objects_evacuated = 0;

#if SIZEOF_VOID_P != 8
static long long stat_major_blocks_freed_ideal = 0;
static long long stat_major_blocks_freed_less_ideal = 0;
static long long stat_major_blocks_freed_individual = 0;
static long long stat_major_blocks_alloced_less_ideal = 0;
#endif

#ifdef SGEN_COUNT_NUMBER_OF_MAJOR_OBJECTS_MARKED
static long long num_major_objects_marked = 0;
#define INC_NUM_MAJOR_OBJECTS_MARKED()  (++num_major_objects_marked)
#else
#define INC_NUM_MAJOR_OBJECTS_MARKED()
#endif

static void
sweep_block (MSBlockInfo *block, gboolean during_major_collection);

static int
ms_find_block_obj_size_index (size_t size)
{
        int i;
        SGEN_ASSERT (9, size <= SGEN_MAX_SMALL_OBJ_SIZE, "size %d is bigger than max small object size %d", size, SGEN_MAX_SMALL_OBJ_SIZE);
        for (i = 0; i < num_block_obj_sizes; ++i)
                if (block_obj_sizes [i] >= size)
                        return i;
        g_error ("no object of size %d\n", size);
}

#define FREE_BLOCKS_FROM(lists,p,r)     (lists [((p) ? MS_BLOCK_FLAG_PINNED : 0) | ((r) ? MS_BLOCK_FLAG_REFS : 0)])
#define FREE_BLOCKS(p,r)                (FREE_BLOCKS_FROM (free_block_lists, (p), (r)))
#ifdef SGEN_PARALLEL_MARK
#ifdef HAVE_KW_THREAD
#define FREE_BLOCKS_LOCAL(p,r)          (FREE_BLOCKS_FROM (workers_free_block_lists, (p), (r)))
#else
#define FREE_BLOCKS_LOCAL(p,r)          (FREE_BLOCKS_FROM (((MSBlockInfo***)(mono_native_tls_get_value (workers_free_block_lists_key))), (p), (r)))
#endif
#else
//#define FREE_BLOCKS_LOCAL(p,r)                (FREE_BLOCKS_FROM (free_block_lists, (p), (r)))
#endif

#define MS_BLOCK_OBJ_SIZE_INDEX(s)                              \
        (((s)+7)>>3 < MS_NUM_FAST_BLOCK_OBJ_SIZE_INDEXES ?      \
         fast_block_obj_size_indexes [((s)+7)>>3] :             \
         ms_find_block_obj_size_index ((s)))

#ifdef FIXED_HEAP
static void*
major_alloc_heap (mword nursery_size, mword nursery_align, int the_nursery_bits)
{
        char *nursery_start;
        mword major_heap_size = ms_heap_num_blocks * MS_BLOCK_SIZE;
        mword alloc_size = nursery_size + major_heap_size;
        mword i;

        g_assert (ms_heap_num_blocks > 0);
        g_assert (nursery_size % MS_BLOCK_SIZE == 0);
        if (nursery_align)
                g_assert (nursery_align % MS_BLOCK_SIZE == 0);

        nursery_start = sgen_alloc_os_memory_aligned (alloc_size, nursery_align ? nursery_align : MS_BLOCK_SIZE, SGEN_ALLOC_HEAP | SGEN_ALLOC_ACTIVATE, "heap");
        ms_heap_start = nursery_start + nursery_size;
        ms_heap_end = ms_heap_start + major_heap_size;

        block_infos = sgen_alloc_internal_dynamic (sizeof (MSBlockInfo) * ms_heap_num_blocks, INTERNAL_MEM_MS_BLOCK_INFO, TRUE);

        for (i = 0; i < ms_heap_num_blocks; ++i) {
                block_infos [i].block = ms_heap_start + i * MS_BLOCK_SIZE;
                if (i < ms_heap_num_blocks - 1)
                        block_infos [i].next_free = &block_infos [i + 1];
                else
                        block_infos [i].next_free = NULL;
                block_infos [i].zeroed = TRUE;
        }

        empty_blocks = &block_infos [0];

        return nursery_start;
}
#else
static void*
major_alloc_heap (mword nursery_size, mword nursery_align, int the_nursery_bits)
{
        char *start;
        if (nursery_align)
                start = sgen_alloc_os_memory_aligned (nursery_size, nursery_align, SGEN_ALLOC_HEAP | SGEN_ALLOC_ACTIVATE, "nursery");
        else
                start = sgen_alloc_os_memory (nursery_size, SGEN_ALLOC_HEAP | SGEN_ALLOC_ACTIVATE, "nursery");

        return start;
}
#endif

static void
update_heap_boundaries_for_block (MSBlockInfo *block)
{
        sgen_update_heap_boundaries ((mword)block->block, (mword)block->block + MS_BLOCK_SIZE);
}

#ifdef FIXED_HEAP
static MSBlockInfo*
ms_get_empty_block (void)
{
        MSBlockInfo *block;

        g_assert (empty_blocks);

        do {
                block = empty_blocks;
        } while (SGEN_CAS_PTR ((gpointer*)&empty_blocks, block->next_free, block) != block);

        block->used = TRUE;

        if (!block->zeroed)
                memset (block->block, 0, MS_BLOCK_SIZE);

        return block;
}

static void
ms_free_block (MSBlockInfo *block)
{
        block->next_free = empty_blocks;
        empty_blocks = block;
        block->used = FALSE;
        block->zeroed = FALSE;
        sgen_memgov_release_space (MS_BLOCK_SIZE, SPACE_MAJOR);
}
#else
static void*
ms_get_empty_block (void)
{
        char *p;
        int i;
        void *block, *empty, *next;

 retry:
        if (!empty_blocks) {
                /*
                 * We try allocating MS_BLOCK_ALLOC_NUM blocks first.  If that's
                 * unsuccessful, we halve the number of blocks and try again, until we're at
                 * 1.  If that doesn't work, either, we assert.
                 */
                int alloc_num = MS_BLOCK_ALLOC_NUM;
                for (;;) {
                        p = sgen_alloc_os_memory_aligned (MS_BLOCK_SIZE * alloc_num, MS_BLOCK_SIZE, SGEN_ALLOC_HEAP | SGEN_ALLOC_ACTIVATE,
                                        alloc_num == 1 ? "major heap section" : NULL);
                        if (p)
                                break;
                        alloc_num >>= 1;
                }

                for (i = 0; i < alloc_num; ++i) {
                        block = p;
                        /*
                         * We do the free list update one after the
                         * other so that other threads can use the new
                         * blocks as quickly as possible.
                         */
                        do {
                                empty = empty_blocks;
                                *(void**)block = empty;
                        } while (SGEN_CAS_PTR ((gpointer*)&empty_blocks, block, empty) != empty);
                        p += MS_BLOCK_SIZE;
                }

                SGEN_ATOMIC_ADD_P (num_empty_blocks, alloc_num);

                stat_major_blocks_alloced += alloc_num;
#if SIZEOF_VOID_P != 8
                if (alloc_num != MS_BLOCK_ALLOC_NUM)
                        stat_major_blocks_alloced_less_ideal += alloc_num;
#endif
        }

        do {
                empty = empty_blocks;
                if (!empty)
                        goto retry;
                block = empty;
                next = *(void**)block;
        } while (SGEN_CAS_PTR (&empty_blocks, next, empty) != empty);

        SGEN_ATOMIC_ADD_P (num_empty_blocks, -1);

        *(void**)block = NULL;

        g_assert (!((mword)block & (MS_BLOCK_SIZE - 1)));

        return block;
}

static void
ms_free_block (void *block)
{
        void *empty;

        sgen_memgov_release_space (MS_BLOCK_SIZE, SPACE_MAJOR);
        memset (block, 0, MS_BLOCK_SIZE);

        do {
                empty = empty_blocks;
                *(void**)block = empty;
        } while (SGEN_CAS_PTR (&empty_blocks, block, empty) != empty);

        SGEN_ATOMIC_ADD_P (num_empty_blocks, 1);
}
#endif

//#define MARKSWEEP_CONSISTENCY_CHECK

#ifdef MARKSWEEP_CONSISTENCY_CHECK
static void
check_block_free_list (MSBlockInfo *block, int size, gboolean pinned)
{
        MSBlockInfo *b;

        for (; block; block = block->next_free) {
                g_assert (block->obj_size == size);
                g_assert ((pinned && block->pinned) || (!pinned && !block->pinned));

                /* blocks in the free lists must have at least
                   one free slot */
                if (block->swept)
                        g_assert (block->free_list);

#ifdef FIXED_HEAP
                /* the block must not be in the empty_blocks list */
                for (b = empty_blocks; b; b = b->next_free)
                        g_assert (b != block);
#endif
                /* the block must be in the all_blocks list */
                for (b = all_blocks; b; b = b->next) {
                        if (b == block)
                                break;
                }
                g_assert (b == block);
        }
}

static void
check_empty_blocks (void)
{
#ifndef FIXED_HEAP
        void *p;
        size_t i = 0;
        for (p = empty_blocks; p; p = *(void**)p)
                ++i;
        g_assert (i == num_empty_blocks);
#endif
}

static void
consistency_check (void)
{
        MSBlockInfo *block;
        int i;

        /* check all blocks */
        FOREACH_BLOCK (block) {
                int count = MS_BLOCK_FREE / block->obj_size;
                int num_free = 0;
                void **free;

#ifndef FIXED_HEAP
                /* check block header */
                g_assert (((MSBlockHeader*)block->block)->info == block);
#endif

                /* count number of free slots */
                for (i = 0; i < count; ++i) {
                        void **obj = (void**) MS_BLOCK_OBJ (block, i);
                        if (!MS_OBJ_ALLOCED (obj, block))
                                ++num_free;
                }

                /* check free list */
                for (free = block->free_list; free; free = (void**)*free) {
                        g_assert (MS_BLOCK_FOR_OBJ (free) == block);
                        --num_free;
                }
                g_assert (num_free == 0);

                /* check all mark words are zero */
                if (block->swept) {
                        for (i = 0; i < MS_NUM_MARK_WORDS; ++i)
                                g_assert (block->mark_words [i] == 0);
                }
        } END_FOREACH_BLOCK;

        /* check free blocks */
        for (i = 0; i < num_block_obj_sizes; ++i) {
                int j;
                for (j = 0; j < MS_BLOCK_TYPE_MAX; ++j)
                        check_block_free_list (free_block_lists [j][i], block_obj_sizes [i], j & MS_BLOCK_FLAG_PINNED);
        }

        check_empty_blocks ();
}
#endif

static gboolean
ms_alloc_block (int size_index, gboolean pinned, gboolean has_references)
{
        int size = block_obj_sizes [size_index];
        int count = MS_BLOCK_FREE / size;
        MSBlockInfo *info;
#ifdef SGEN_PARALLEL_MARK
        MSBlockInfo *next;
#endif
#ifndef FIXED_HEAP
        MSBlockHeader *header;
#endif
        MSBlockInfo **free_blocks = FREE_BLOCKS (pinned, has_references);
        char *obj_start;
        int i;

        if (!sgen_memgov_try_alloc_space (MS_BLOCK_SIZE, SPACE_MAJOR))
                return FALSE;

#ifdef FIXED_HEAP
        info = ms_get_empty_block ();
#else
        info = sgen_alloc_internal (INTERNAL_MEM_MS_BLOCK_INFO);
#endif

        SGEN_ASSERT (9, count >= 2, "block with %d objects, it must hold at least 2", count);

        info->obj_size = size;
        info->obj_size_index = size_index;
        info->pinned = pinned;
        info->has_references = has_references;
        info->has_pinned = pinned;
        /*
         * Blocks that are to-space are not evacuated from.  During an major collection
         * blocks are allocated for two reasons: evacuating objects from the nursery and
         * evacuating them from major blocks marked for evacuation.  In both cases we don't
         * want further evacuation.
         */
        info->is_to_space = (sgen_get_current_collection_generation () == GENERATION_OLD);
        info->swept = 1;
#ifndef FIXED_HEAP
        info->block = ms_get_empty_block ();

        header = (MSBlockHeader*) info->block;
        header->info = info;
#endif
#ifdef SGEN_HAVE_CONCURRENT_MARK
        info->cardtable_mod_union = NULL;
#endif

        update_heap_boundaries_for_block (info);

        /* build free list */
        obj_start = info->block + MS_BLOCK_SKIP;
        info->free_list = (void**)obj_start;
        /* we're skipping the last one - it must be nulled */
        for (i = 0; i < count - 1; ++i) {
                char *next_obj_start = obj_start + size;
                *(void**)obj_start = next_obj_start;
                obj_start = next_obj_start;
        }
        /* the last one */
        *(void**)obj_start = NULL;

#ifdef SGEN_PARALLEL_MARK
        do {
                next = info->next_free = free_blocks [size_index];
        } while (SGEN_CAS_PTR ((void**)&free_blocks [size_index], info, next) != next);

        do {
                next = info->next = all_blocks;
        } while (SGEN_CAS_PTR ((void**)&all_blocks, info, next) != next);
#else
        info->next_free = free_blocks [size_index];
        free_blocks [size_index] = info;

        info->next = all_blocks;
        all_blocks = info;
#endif

        ++num_major_sections;
        return TRUE;
}

static gboolean
obj_is_from_pinned_alloc (char *ptr)
{
        MSBlockInfo *block;

        FOREACH_BLOCK (block) {
                if (ptr >= block->block && ptr <= block->block + MS_BLOCK_SIZE)
                        return block->pinned;
        } END_FOREACH_BLOCK;
        return FALSE;
}

static void*
unlink_slot_from_free_list_uncontested (MSBlockInfo **free_blocks, int size_index)
{
        MSBlockInfo *block;
        void *obj;

        block = free_blocks [size_index];
        SGEN_ASSERT (9, block, "no free block to unlink from free_blocks %p size_index %d", free_blocks, size_index);

        if (G_UNLIKELY (!block->swept)) {
                stat_major_blocks_lazy_swept ++;
                sweep_block (block, FALSE);
        }

        obj = block->free_list;
        SGEN_ASSERT (9, obj, "block %p in free list had no available object to alloc from", block);

        block->free_list = *(void**)obj;
        if (!block->free_list) {
                free_blocks [size_index] = block->next_free;
                block->next_free = NULL;
        }

        return obj;
}

#ifdef SGEN_PARALLEL_MARK
static gboolean
try_remove_block_from_free_list (MSBlockInfo *block, MSBlockInfo **free_blocks, int size_index)
{
        /*
         * No more free slots in the block, so try to free the block.
         * Don't try again if we don't succeed - another thread will
         * already have done it.
         */
        MSBlockInfo *next_block = block->next_free;
        if (SGEN_CAS_PTR ((void**)&free_blocks [size_index], next_block, block) == block) {
                /*
                void *old = SGEN_CAS_PTR ((void**)&block->next_free, NULL, next_block);
                g_assert (old == next_block);
                */
                block->next_free = NULL;
                return TRUE;
        }
        return FALSE;
}

static void*
alloc_obj_par (MonoVTable *vtable, int size, gboolean pinned, gboolean has_references)
{
        int size_index = MS_BLOCK_OBJ_SIZE_INDEX (size);
        MSBlockInfo **free_blocks_local = FREE_BLOCKS_LOCAL (pinned, has_references);
        MSBlockInfo *block;
        void *obj;

#ifdef SGEN_HAVE_CONCURRENT_MARK
        if (concurrent_mark)
                g_assert_not_reached ();
#endif

        SGEN_ASSERT (9, current_collection_generation == GENERATION_OLD, "old gen parallel allocator called from a %d collection", current_collection_generation);

        if (free_blocks_local [size_index]) {
        get_slot:
                obj = unlink_slot_from_free_list_uncontested (free_blocks_local, size_index);
        } else {
                MSBlockInfo **free_blocks = FREE_BLOCKS (pinned, has_references);

        get_block:
                block = free_blocks [size_index];
                if (block) {
                        if (!try_remove_block_from_free_list (block, free_blocks, size_index))
                                goto get_block;

                        g_assert (block->next_free == NULL);
                        g_assert (block->free_list);
                        block->next_free = free_blocks_local [size_index];
                        free_blocks_local [size_index] = block;

                        goto get_slot;
                } else {
                        gboolean success;

                        LOCK_MS_BLOCK_LIST;
                        success = ms_alloc_block (size_index, pinned, has_references);
                        UNLOCK_MS_BLOCK_LIST;

                        if (G_UNLIKELY (!success))
                                return NULL;

                        goto get_block;
                }
        }

        *(MonoVTable**)obj = vtable;

        return obj;
}

static void*
major_par_alloc_object (MonoVTable *vtable, size_t size, gboolean has_references)
{
        return alloc_obj_par (vtable, size, FALSE, has_references);
}
#endif

static void*
alloc_obj (MonoVTable *vtable, size_t size, gboolean pinned, gboolean has_references)
{
        int size_index = MS_BLOCK_OBJ_SIZE_INDEX (size);
        MSBlockInfo **free_blocks = FREE_BLOCKS (pinned, has_references);
        void *obj;

#ifdef SGEN_PARALLEL_MARK
        SGEN_ASSERT (9, current_collection_generation == GENERATION_OLD, "old gen parallel allocator called from a %d collection", current_collection_generation);

#endif

        if (!free_blocks [size_index]) {
                if (G_UNLIKELY (!ms_alloc_block (size_index, pinned, has_references)))
                        return NULL;
        }

        obj = unlink_slot_from_free_list_uncontested (free_blocks, size_index);

        *(MonoVTable**)obj = vtable;

        return obj;
}

static void*
major_alloc_object (MonoVTable *vtable, size_t size, gboolean has_references)
{
        return alloc_obj (vtable, size, FALSE, has_references);
}

/*
 * We're not freeing the block if it's empty.  We leave that work for
 * the next major collection.
 *
 * This is just called from the domain clearing code, which runs in a
 * single thread and has the GC lock, so we don't need an extra lock.
 */
static void
free_object (char *obj, size_t size, gboolean pinned)
{
        MSBlockInfo *block = MS_BLOCK_FOR_OBJ (obj);
        int word, bit;

        if (!block->swept)
                sweep_block (block, FALSE);
        SGEN_ASSERT (9, (pinned && block->pinned) || (!pinned && !block->pinned), "free-object pinning mixup object %p pinned %d block %p pinned %d", obj, pinned, block, block->pinned);
        SGEN_ASSERT (9, MS_OBJ_ALLOCED (obj, block), "object %p is already free", obj);
        MS_CALC_MARK_BIT (word, bit, obj);
        SGEN_ASSERT (9, !MS_MARK_BIT (block, word, bit), "object %p has mark bit set");
        if (!block->free_list) {
                MSBlockInfo **free_blocks = FREE_BLOCKS (pinned, block->has_references);
                int size_index = MS_BLOCK_OBJ_SIZE_INDEX (size);
                SGEN_ASSERT (9, !block->next_free, "block %p doesn't have a free-list of object but belongs to a free-list of blocks");
                block->next_free = free_blocks [size_index];
                free_blocks [size_index] = block;
        }
        memset (obj, 0, size);
        *(void**)obj = block->free_list;
        block->free_list = (void**)obj;
}

static void
major_free_non_pinned_object (char *obj, size_t size)
{
        free_object (obj, size, FALSE);
}

/* size is a multiple of SGEN_ALLOC_ALIGN */
static void*
major_alloc_small_pinned_obj (MonoVTable *vtable, size_t size, gboolean has_references)
{
        void *res;

        res = alloc_obj (vtable, size, TRUE, has_references);
         /*If we failed to alloc memory, we better try releasing memory
          *as pinned alloc is requested by the runtime.
          */
         if (!res) {
                sgen_perform_collection (0, GENERATION_OLD, "pinned alloc failure", TRUE);
                res = alloc_obj (vtable, size, TRUE, has_references);
         }
         return res;
}

static void
free_pinned_object (char *obj, size_t size)
{
        free_object (obj, size, TRUE);
}

/*
 * size is already rounded up and we hold the GC lock.
 */
static void*
major_alloc_degraded (MonoVTable *vtable, size_t size)
{
        void *obj;
        size_t old_num_sections;

        old_num_sections = num_major_sections;

        obj = alloc_obj (vtable, size, FALSE, SGEN_VTABLE_HAS_REFERENCES (vtable));
        if (G_LIKELY (obj)) {
                HEAVY_STAT (++stat_objects_alloced_degraded);
                HEAVY_STAT (stat_bytes_alloced_degraded += size);
                g_assert (num_major_sections >= old_num_sections);
                sgen_register_major_sections_alloced (num_major_sections - old_num_sections);
        }
        return obj;
}

#define MAJOR_OBJ_IS_IN_TO_SPACE(obj)   FALSE

/*
 * obj is some object.  If it's not in the major heap (i.e. if it's in
 * the nursery or LOS), return FALSE.  Otherwise return whether it's
 * been marked or copied.
 */
static gboolean
major_is_object_live (char *obj)
{
        MSBlockInfo *block;
        int word, bit;
#ifndef FIXED_HEAP
        mword objsize;
#endif

        if (sgen_ptr_in_nursery (obj))
                return FALSE;

#ifdef FIXED_HEAP
        /* LOS */
        if (!MS_PTR_IN_SMALL_MAJOR_HEAP (obj))
                return FALSE;
#else
        objsize = SGEN_ALIGN_UP (sgen_safe_object_get_size ((MonoObject*)obj));

        /* LOS */
        if (objsize > SGEN_MAX_SMALL_OBJ_SIZE)
                return FALSE;
#endif

        /* now we know it's in a major block */
        block = MS_BLOCK_FOR_OBJ (obj);
        SGEN_ASSERT (9, !block->pinned, "block %p is pinned, BTW why is this bad?");
        MS_CALC_MARK_BIT (word, bit, obj);
        return MS_MARK_BIT (block, word, bit) ? TRUE : FALSE;
}

static gboolean
major_ptr_is_in_non_pinned_space (char *ptr, char **start)
{
        MSBlockInfo *block;

        FOREACH_BLOCK (block) {
                if (ptr >= block->block && ptr <= block->block + MS_BLOCK_SIZE) {
                        int count = MS_BLOCK_FREE / block->obj_size;
                        int i;

                        *start = NULL;
                        for (i = 0; i <= count; ++i) {
                                if (ptr >= MS_BLOCK_OBJ (block, i) && ptr < MS_BLOCK_OBJ (block, i + 1)) {
                                        *start = MS_BLOCK_OBJ (block, i);
                                        break;
                                }
                        }
                        return !block->pinned;
                }
        } END_FOREACH_BLOCK;
        return FALSE;
}

static void
major_iterate_objects (IterateObjectsFlags flags, IterateObjectCallbackFunc callback, void *data)
{
        gboolean sweep = flags & ITERATE_OBJECTS_SWEEP;
        gboolean non_pinned = flags & ITERATE_OBJECTS_NON_PINNED;
        gboolean pinned = flags & ITERATE_OBJECTS_PINNED;
        MSBlockInfo *block;

        FOREACH_BLOCK (block) {
                int count = MS_BLOCK_FREE / block->obj_size;
                int i;

                if (block->pinned && !pinned)
                        continue;
                if (!block->pinned && !non_pinned)
                        continue;
                if (sweep && lazy_sweep) {
                        sweep_block (block, FALSE);
                        SGEN_ASSERT (0, block->swept, "Block must be swept after sweeping");
                }

                for (i = 0; i < count; ++i) {
                        void **obj = (void**) MS_BLOCK_OBJ (block, i);
                        if (!block->swept) {
                                int word, bit;
                                MS_CALC_MARK_BIT (word, bit, obj);
                                if (!MS_MARK_BIT (block, word, bit))
                                        continue;
                        }
                        if (MS_OBJ_ALLOCED (obj, block))
                                callback ((char*)obj, block->obj_size, data);
                }
        } END_FOREACH_BLOCK;
}

static gboolean
major_is_valid_object (char *object)
{
        MSBlockInfo *block;

        FOREACH_BLOCK (block) {
                int idx;
                char *obj;

                if ((block->block > object) || ((block->block + MS_BLOCK_SIZE) <= object))
                        continue;

                idx = MS_BLOCK_OBJ_INDEX (object, block);
                obj = (char*)MS_BLOCK_OBJ (block, idx);
                if (obj != object)
                        return FALSE;
                return MS_OBJ_ALLOCED (obj, block);
        } END_FOREACH_BLOCK;

        return FALSE;
}


static MonoVTable*
major_describe_pointer (char *ptr)
{
        MSBlockInfo *block;

        FOREACH_BLOCK (block) {
                int idx;
                char *obj;
                gboolean live;
                MonoVTable *vtable;
                int w, b;
                gboolean marked;

                if ((block->block > ptr) || ((block->block + MS_BLOCK_SIZE) <= ptr))
                        continue;

                SGEN_LOG (0, "major-ptr (block %p sz %d pin %d ref %d)\n",
                        block->block, block->obj_size, block->pinned, block->has_references);

                idx = MS_BLOCK_OBJ_INDEX (ptr, block);
                obj = (char*)MS_BLOCK_OBJ (block, idx);
                live = MS_OBJ_ALLOCED (obj, block);
                vtable = live ? (MonoVTable*)SGEN_LOAD_VTABLE (obj) : NULL;

                MS_CALC_MARK_BIT (w, b, obj);
                marked = MS_MARK_BIT (block, w, b);

                if (obj == ptr) {
                        SGEN_LOG (0, "\t(");
                        if (live)
                                SGEN_LOG (0, "object");
                        else
                                SGEN_LOG (0, "dead-object");
                } else {
                        if (live)
                                SGEN_LOG (0, "interior-ptr offset %td", ptr - obj);
                        else
                                SGEN_LOG (0, "dead-interior-ptr offset %td", ptr - obj);
                }

                SGEN_LOG (0, " marked %d)\n", marked ? 1 : 0);

                return vtable;
        } END_FOREACH_BLOCK;

        return NULL;
}

static void
major_check_scan_starts (void)
{
}

static void
major_dump_heap (FILE *heap_dump_file)
{
        MSBlockInfo *block;
        int *slots_available = alloca (sizeof (int) * num_block_obj_sizes);
        int *slots_used = alloca (sizeof (int) * num_block_obj_sizes);
        int i;

        for (i = 0; i < num_block_obj_sizes; ++i)
                slots_available [i] = slots_used [i] = 0;

        FOREACH_BLOCK (block) {
                int index = ms_find_block_obj_size_index (block->obj_size);
                int count = MS_BLOCK_FREE / block->obj_size;

                slots_available [index] += count;
                for (i = 0; i < count; ++i) {
                        if (MS_OBJ_ALLOCED (MS_BLOCK_OBJ (block, i), block))
                                ++slots_used [index];
                }
        } END_FOREACH_BLOCK;

        fprintf (heap_dump_file, "<occupancies>\n");
        for (i = 0; i < num_block_obj_sizes; ++i) {
                fprintf (heap_dump_file, "<occupancy size=\"%d\" available=\"%d\" used=\"%d\" />\n",
                                block_obj_sizes [i], slots_available [i], slots_used [i]);
        }
        fprintf (heap_dump_file, "</occupancies>\n");

        FOREACH_BLOCK (block) {
                int count = MS_BLOCK_FREE / block->obj_size;
                int i;
                int start = -1;

                fprintf (heap_dump_file, "<section type=\"%s\" size=\"%zu\">\n", "old", (size_t)MS_BLOCK_FREE);

                for (i = 0; i <= count; ++i) {
                        if ((i < count) && MS_OBJ_ALLOCED (MS_BLOCK_OBJ (block, i), block)) {
                                if (start < 0)
                                        start = i;
                        } else {
                                if (start >= 0) {
                                        sgen_dump_occupied (MS_BLOCK_OBJ (block, start), MS_BLOCK_OBJ (block, i), block->block);
                                        start = -1;
                                }
                        }
                }

                fprintf (heap_dump_file, "</section>\n");
        } END_FOREACH_BLOCK;
}

#define LOAD_VTABLE     SGEN_LOAD_VTABLE

#define MS_MARK_OBJECT_AND_ENQUEUE_CHECKED(obj,block,queue) do {        \
                int __word, __bit;                                      \
                MS_CALC_MARK_BIT (__word, __bit, (obj));                \
                if (!MS_MARK_BIT ((block), __word, __bit) && MS_OBJ_ALLOCED ((obj), (block))) { \
                        MS_SET_MARK_BIT ((block), __word, __bit);       \
                        if ((block)->has_references)                    \
                                GRAY_OBJECT_ENQUEUE ((queue), (obj));   \
                        binary_protocol_mark ((obj), (gpointer)LOAD_VTABLE ((obj)), sgen_safe_object_get_size ((MonoObject*)(obj))); \
                        INC_NUM_MAJOR_OBJECTS_MARKED ();                \
                }                                                       \
        } while (0)
#define MS_MARK_OBJECT_AND_ENQUEUE(obj,block,queue) do {                \
                int __word, __bit;                                      \
                MS_CALC_MARK_BIT (__word, __bit, (obj));                \
                SGEN_ASSERT (9, MS_OBJ_ALLOCED ((obj), (block)), "object %p not allocated", obj);       \
                if (!MS_MARK_BIT ((block), __word, __bit)) {            \
                        MS_SET_MARK_BIT ((block), __word, __bit);       \
                        if ((block)->has_references)                    \
                                GRAY_OBJECT_ENQUEUE ((queue), (obj));   \
                        binary_protocol_mark ((obj), (gpointer)LOAD_VTABLE ((obj)), sgen_safe_object_get_size ((MonoObject*)(obj))); \
                        INC_NUM_MAJOR_OBJECTS_MARKED ();                \
                }                                                       \
        } while (0)
#define MS_PAR_MARK_OBJECT_AND_ENQUEUE(obj,block,queue) do {            \
                int __word, __bit;                                      \
                gboolean __was_marked;                                  \
                SGEN_ASSERT (9, MS_OBJ_ALLOCED ((obj), (block)), "object %p not allocated", obj);       \
                MS_CALC_MARK_BIT (__word, __bit, (obj));                \
                MS_PAR_SET_MARK_BIT (__was_marked, (block), __word, __bit); \
                if (!__was_marked) {                                    \
                        if ((block)->has_references)                    \
                                GRAY_OBJECT_ENQUEUE ((queue), (obj));   \
                        binary_protocol_mark ((obj), (gpointer)LOAD_VTABLE ((obj)), sgen_safe_object_get_size ((MonoObject*)(obj))); \
                        INC_NUM_MAJOR_OBJECTS_MARKED ();                \
                }                                                       \
        } while (0)

static void
pin_major_object (char *obj, SgenGrayQueue *queue)
{
        MSBlockInfo *block;

#ifdef SGEN_HAVE_CONCURRENT_MARK
        if (concurrent_mark)
                g_assert_not_reached ();
#endif

        block = MS_BLOCK_FOR_OBJ (obj);
        block->has_pinned = TRUE;
        MS_MARK_OBJECT_AND_ENQUEUE (obj, block, queue);
}

#include "sgen-major-copy-object.h"

#ifdef SGEN_PARALLEL_MARK
static void
major_copy_or_mark_object (void **ptr, void *obj, SgenGrayQueue *queue)
{
        mword objsize;
        MSBlockInfo *block;
        MonoVTable *vt;

        HEAVY_STAT (++stat_copy_object_called_major);

        SGEN_ASSERT (9, obj, "null object from pointer %p", ptr);
        SGEN_ASSERT (9, current_collection_generation == GENERATION_OLD, "old gen parallel allocator called from a %d collection", current_collection_generation);

        if (sgen_ptr_in_nursery (obj)) {
                int word, bit;
                gboolean has_references;
                void *destination;
                mword vtable_word = *(mword*)obj;
                vt = (MonoVTable*)(vtable_word & ~SGEN_VTABLE_BITS_MASK);

                if (vtable_word & SGEN_FORWARDED_BIT) {
                        *ptr = (void*)vt;
                        return;
                }

                if (vtable_word & SGEN_PINNED_BIT)
                        return;

                /* An object in the nursery To Space has already been copied and grayed. Nothing to do. */
                if (sgen_nursery_is_to_space (obj))
                        return;

                HEAVY_STAT (++stat_objects_copied_major);

        do_copy_object:
                objsize = SGEN_ALIGN_UP (sgen_par_object_get_size (vt, (MonoObject*)obj));
                has_references = SGEN_VTABLE_HAS_REFERENCES (vt);

                destination = sgen_minor_collector.par_alloc_for_promotion (vt, obj, objsize, has_references);
                if (G_UNLIKELY (!destination)) {
                        if (!sgen_ptr_in_nursery (obj)) {
                                int size_index;
                                block = MS_BLOCK_FOR_OBJ (obj);
                                size_index = block->obj_size_index;
                                evacuate_block_obj_sizes [size_index] = FALSE;
                        }

                        sgen_parallel_pin_or_update (ptr, obj, vt, queue);
                        sgen_set_pinned_from_failed_allocation (objsize);
                        return;
                }

                if (SGEN_CAS_PTR (obj, (void*)((mword)destination | SGEN_FORWARDED_BIT), vt) == vt) {
                        gboolean was_marked;

                        par_copy_object_no_checks (destination, vt, obj, objsize, has_references ? queue : NULL);
                        obj = destination;
                        *ptr = obj;

                        /*
                         * FIXME: If we make major_alloc_object() give
                         * us the block info, too, we won't have to
                         * re-fetch it here.
                         *
                         * FIXME (2): We should rework this to avoid all those nursery checks.
                         */
                        /*
                         * For the split nursery allocator the object
                         * might still be in the nursery despite
                         * having being promoted, in which case we
                         * can't mark it.
                         */
                        if (!sgen_ptr_in_nursery (obj)) {
                                block = MS_BLOCK_FOR_OBJ (obj);
                                MS_CALC_MARK_BIT (word, bit, obj);
                                SGEN_ASSERT (9, !MS_MARK_BIT (block, word, bit), "object %p already marked", obj);
                                MS_PAR_SET_MARK_BIT (was_marked, block, word, bit);
                                binary_protocol_mark (obj, vt, sgen_safe_object_get_size ((MonoObject*)obj));
                        }
                } else {
                        /*
                         * FIXME: We have allocated destination, but
                         * we cannot use it.  Give it back to the
                         * allocator.
                         */
                        *(void**)destination = NULL;

                        vtable_word = *(mword*)obj;
                        g_assert (vtable_word & SGEN_FORWARDED_BIT);

                        obj = (void*)(vtable_word & ~SGEN_VTABLE_BITS_MASK);

                        *ptr = obj;

                        HEAVY_STAT (++stat_slots_allocated_in_vain);
                }
        } else {
#ifdef FIXED_HEAP
                if (MS_PTR_IN_SMALL_MAJOR_HEAP (obj))
#else
                mword vtable_word = *(mword*)obj;
                vt = (MonoVTable*)(vtable_word & ~SGEN_VTABLE_BITS_MASK);

                /* see comment in the non-parallel version below */
                if (vtable_word & SGEN_FORWARDED_BIT) {
                        *ptr = (void*)vt;
                        return;
                }
                objsize = SGEN_ALIGN_UP (sgen_par_object_get_size (vt, (MonoObject*)obj));

                if (objsize <= SGEN_MAX_SMALL_OBJ_SIZE)
#endif
                {
                        int size_index;

                        block = MS_BLOCK_FOR_OBJ (obj);
                        size_index = block->obj_size_index;

                        if (!block->has_pinned && evacuate_block_obj_sizes [size_index]) {
                                if (block->is_to_space)
                                        return;

#ifdef FIXED_HEAP
                                {
                                        mword vtable_word = *(mword*)obj;
                                        vt = (MonoVTable*)(vtable_word & ~SGEN_VTABLE_BITS_MASK);

                                        if (vtable_word & SGEN_FORWARDED_BIT) {
                                                *ptr = (void*)vt;
                                                return;
                                        }
                                }
#endif

                                HEAVY_STAT (++stat_major_objects_evacuated);
                                goto do_copy_object;
                        }

                        MS_PAR_MARK_OBJECT_AND_ENQUEUE (obj, block, queue);
                } else {
                        LOSObject *bigobj = sgen_los_header_for_object (obj);
                        mword size_word = bigobj->size;
#ifdef FIXED_HEAP
                        mword vtable_word = *(mword*)obj;
                        vt = (MonoVTable*)(vtable_word & ~SGEN_VTABLE_BITS_MASK);
#endif
                        if (size_word & 1)
                                return;
                        binary_protocol_pin (obj, vt, sgen_safe_object_get_size ((MonoObject*)obj));
                        if (SGEN_CAS_PTR ((void*)&bigobj->size, (void*)(size_word | 1), (void*)size_word) == (void*)size_word) {
                                if (SGEN_VTABLE_HAS_REFERENCES (vt))
                                        GRAY_OBJECT_ENQUEUE (queue, obj);
                        } else {
                                g_assert (sgen_los_object_is_pinned (obj));
                        }
                }
        }
}
#else
#ifdef SGEN_HAVE_CONCURRENT_MARK
static void
major_copy_or_mark_object_concurrent (void **ptr, void *obj, SgenGrayQueue *queue)
{
        g_assert (!SGEN_OBJECT_IS_FORWARDED (obj));

        if (!sgen_ptr_in_nursery (obj)) {
#ifdef FIXED_HEAP
                if (MS_PTR_IN_SMALL_MAJOR_HEAP (obj))
#else
                mword objsize;

                objsize = SGEN_ALIGN_UP (sgen_safe_object_get_size ((MonoObject*)obj));

                if (objsize <= SGEN_MAX_SMALL_OBJ_SIZE)
#endif
                {
                        MSBlockInfo *block = MS_BLOCK_FOR_OBJ (obj);
                        MS_MARK_OBJECT_AND_ENQUEUE (obj, block, queue);
                } else {
                        if (sgen_los_object_is_pinned (obj))
                                return;

#ifdef ENABLE_DTRACE
                        if (G_UNLIKELY (MONO_GC_OBJ_PINNED_ENABLED ())) {
                                MonoVTable *vt = (MonoVTable*)SGEN_LOAD_VTABLE (obj);
                                MONO_GC_OBJ_PINNED ((mword)obj, sgen_safe_object_get_size (obj), vt->klass->name_space, vt->klass->name, GENERATION_OLD);
                        }
#endif

                        sgen_los_pin_object (obj);
                        if (SGEN_OBJECT_HAS_REFERENCES (obj))
                                GRAY_OBJECT_ENQUEUE (queue, obj);
                        INC_NUM_MAJOR_OBJECTS_MARKED ();
                }
        }
}
#endif

static void
major_copy_or_mark_object (void **ptr, void *obj, SgenGrayQueue *queue)
{
        MSBlockInfo *block;

        HEAVY_STAT (++stat_copy_object_called_major);

        SGEN_ASSERT (9, obj, "null object from pointer %p", ptr);
        SGEN_ASSERT (9, current_collection_generation == GENERATION_OLD, "old gen parallel allocator called from a %d collection", current_collection_generation);

        if (sgen_ptr_in_nursery (obj)) {
                int word, bit;
                char *forwarded, *old_obj;

                if ((forwarded = SGEN_OBJECT_IS_FORWARDED (obj))) {
                        *ptr = forwarded;
                        return;
                }
                if (SGEN_OBJECT_IS_PINNED (obj))
                        return;

                /* An object in the nursery To Space has already been copied and grayed. Nothing to do. */
                if (sgen_nursery_is_to_space (obj))
                        return;

                HEAVY_STAT (++stat_objects_copied_major);

        do_copy_object:
                old_obj = obj;
                obj = copy_object_no_checks (obj, queue);
                if (G_UNLIKELY (old_obj == obj)) {
                        /*If we fail to evacuate an object we just stop doing it for a given block size as all other will surely fail too.*/
                        if (!sgen_ptr_in_nursery (obj)) {
                                int size_index;
                                block = MS_BLOCK_FOR_OBJ (obj);
                                size_index = block->obj_size_index;
                                evacuate_block_obj_sizes [size_index] = FALSE;
                                MS_MARK_OBJECT_AND_ENQUEUE (obj, block, queue);
                        }
                        return;
                }
                *ptr = obj;

                /*
                 * FIXME: See comment for copy_object_no_checks().  If
                 * we have that, we can let the allocation function
                 * give us the block info, too, and we won't have to
                 * re-fetch it.
                 *
                 * FIXME (2): We should rework this to avoid all those nursery checks.
                 */
                /*
                 * For the split nursery allocator the object might
                 * still be in the nursery despite having being
                 * promoted, in which case we can't mark it.
                 */
                if (!sgen_ptr_in_nursery (obj)) {
                        block = MS_BLOCK_FOR_OBJ (obj);
                        MS_CALC_MARK_BIT (word, bit, obj);
                        SGEN_ASSERT (9, !MS_MARK_BIT (block, word, bit), "object %p already marked", obj);
                        MS_SET_MARK_BIT (block, word, bit);
                        binary_protocol_mark (obj, (gpointer)LOAD_VTABLE (obj), sgen_safe_object_get_size ((MonoObject*)obj));
                }
        } else {
                char *forwarded;
#ifdef FIXED_HEAP
                if (MS_PTR_IN_SMALL_MAJOR_HEAP (obj))
#else
                mword objsize;

                /*
                 * If we have don't have a fixed heap we cannot know
                 * whether an object is in the LOS or in the small
                 * object major heap without checking its size.  To do
                 * that, however, we need to know that we actually
                 * have a valid object, not a forwarding pointer, so
                 * we have to do this check first.
                 */
                if ((forwarded = SGEN_OBJECT_IS_FORWARDED (obj))) {
                        *ptr = forwarded;
                        return;
                }

                objsize = SGEN_ALIGN_UP (sgen_safe_object_get_size ((MonoObject*)obj));

                if (objsize <= SGEN_MAX_SMALL_OBJ_SIZE)
#endif
                {
                        int size_index;
                        gboolean evacuate;

                        block = MS_BLOCK_FOR_OBJ (obj);
                        size_index = block->obj_size_index;
                        evacuate = evacuate_block_obj_sizes [size_index];

#ifdef FIXED_HEAP
                        /*
                         * We could also check for !block->has_pinned
                         * here, but it would only make an uncommon case
                         * faster, namely objects that are in blocks
                         * whose slot sizes are evacuated but which have
                         * pinned objects.
                         */
                        if (evacuate && (forwarded = SGEN_OBJECT_IS_FORWARDED (obj))) {
                                *ptr = forwarded;
                                return;
                        }
#endif

                        if (evacuate && !block->has_pinned) {
                                g_assert (!SGEN_OBJECT_IS_PINNED (obj));
                                if (block->is_to_space)
                                        return;
                                HEAVY_STAT (++stat_major_objects_evacuated);
                                goto do_copy_object;
                        } else {
                                MS_MARK_OBJECT_AND_ENQUEUE (obj, block, queue);
                        }
                } else {
                        if (sgen_los_object_is_pinned (obj))
                                return;
                        binary_protocol_pin (obj, (gpointer)SGEN_LOAD_VTABLE (obj), sgen_safe_object_get_size ((MonoObject*)obj));

#ifdef ENABLE_DTRACE
                        if (G_UNLIKELY (MONO_GC_OBJ_PINNED_ENABLED ())) {
                                MonoVTable *vt = (MonoVTable*)SGEN_LOAD_VTABLE (obj);
                                MONO_GC_OBJ_PINNED ((mword)obj, sgen_safe_object_get_size (obj), vt->klass->name_space, vt->klass->name, GENERATION_OLD);
                        }
#endif

                        sgen_los_pin_object (obj);
                        if (SGEN_OBJECT_HAS_REFERENCES (obj))
                                GRAY_OBJECT_ENQUEUE (queue, obj);
                }
        }
}
#endif

static void
major_copy_or_mark_object_canonical (void **ptr, SgenGrayQueue *queue)
{
        major_copy_or_mark_object (ptr, *ptr, queue);
}

#ifdef SGEN_HAVE_CONCURRENT_MARK
static void
major_copy_or_mark_object_concurrent_canonical (void **ptr, SgenGrayQueue *queue)
{
        major_copy_or_mark_object_concurrent (ptr, *ptr, queue);
}

static long long
major_get_and_reset_num_major_objects_marked (void)
{
#ifdef SGEN_COUNT_NUMBER_OF_MAJOR_OBJECTS_MARKED
        long long num = num_major_objects_marked;
        num_major_objects_marked = 0;
        return num;
#else
        return 0;
#endif
}
#endif

#include "sgen-major-scan-object.h"

#ifdef SGEN_HAVE_CONCURRENT_MARK
#define SCAN_FOR_CONCURRENT_MARK
#include "sgen-major-scan-object.h"
#undef SCAN_FOR_CONCURRENT_MARK
#endif

static void
mark_pinned_objects_in_block (MSBlockInfo *block, SgenGrayQueue *queue)
{
        int i;
        int last_index = -1;

        if (!block->pin_queue_num_entries)
                return;

        block->has_pinned = TRUE;

        for (i = 0; i < block->pin_queue_num_entries; ++i) {
                int index = MS_BLOCK_OBJ_INDEX (block->pin_queue_start [i], block);
                SGEN_ASSERT (9, index >= 0 && index < MS_BLOCK_FREE / block->obj_size, "invalid object %p index %d max-index %d", block->pin_queue_start [i], index, MS_BLOCK_FREE / block->obj_size);
                if (index == last_index)
                        continue;
                MS_MARK_OBJECT_AND_ENQUEUE_CHECKED (MS_BLOCK_OBJ (block, index), block, queue);
                last_index = index;
        }
}

static inline void
sweep_block_for_size (MSBlockInfo *block, int count, int obj_size)
{
        int obj_index;

        for (obj_index = 0; obj_index < count; ++obj_index) {
                int word, bit;
                void *obj = MS_BLOCK_OBJ_FOR_SIZE (block, obj_index, obj_size);

                MS_CALC_MARK_BIT (word, bit, obj);
                if (MS_MARK_BIT (block, word, bit)) {
                        SGEN_ASSERT (9, MS_OBJ_ALLOCED (obj, block), "object %p not allocated", obj);
                } else {
                        /* an unmarked object */
                        if (MS_OBJ_ALLOCED (obj, block)) {
                                /*
                                 * FIXME: Merge consecutive
                                 * slots for lower reporting
                                 * overhead.  Maybe memset
                                 * will also benefit?
                                 */
                                binary_protocol_empty (obj, obj_size);
                                MONO_GC_MAJOR_SWEPT ((mword)obj, obj_size);
                                memset (obj, 0, obj_size);
                        }
                        *(void**)obj = block->free_list;
                        block->free_list = obj;
                }
        }
}

/*
 * sweep_block:
 *
 *   Traverse BLOCK, freeing and zeroing unused objects.
 */
static void
sweep_block (MSBlockInfo *block, gboolean during_major_collection)
{
        int count;
        void *reversed = NULL;

        if (!during_major_collection)
                g_assert (!sgen_concurrent_collection_in_progress ());

        if (block->swept)
                return;

        count = MS_BLOCK_FREE / block->obj_size;

        block->free_list = NULL;

        /* Use inline instances specialized to constant sizes, this allows the compiler to replace the memset calls with inline code */
        // FIXME: Add more sizes
        switch (block->obj_size) {
        case 16:
                sweep_block_for_size (block, count, 16);
                break;
        default:
                sweep_block_for_size (block, count, block->obj_size);
                break;
        }

        /* reset mark bits */
        memset (block->mark_words, 0, sizeof (mword) * MS_NUM_MARK_WORDS);

        /* Reverse free list so that it's in address order */
        reversed = NULL;
        while (block->free_list) {
                void *next = *(void**)block->free_list;
                *(void**)block->free_list = reversed;
                reversed = block->free_list;
                block->free_list = next;
        }
        block->free_list = reversed;

        block->swept = 1;
}

static inline int
bitcount (mword d)
{
        int count = 0;

#ifdef __GNUC__
        if (sizeof (mword) == sizeof (unsigned long))
                count += __builtin_popcountl (d);
        else
                count += __builtin_popcount (d);
#else
        while (d) {
                count ++;
                d &= (d - 1);
        }
#endif
        return count;
}

static void
ms_sweep (void)
{
        int i;
        MSBlockInfo **iter;

        /* statistics for evacuation */
        int *slots_available = alloca (sizeof (int) * num_block_obj_sizes);
        int *slots_used = alloca (sizeof (int) * num_block_obj_sizes);
        int *num_blocks = alloca (sizeof (int) * num_block_obj_sizes);

#ifdef SGEN_HAVE_CONCURRENT_MARK
        mword total_evacuate_heap = 0;
        mword total_evacuate_saved = 0;
#endif

        for (i = 0; i < num_block_obj_sizes; ++i)
                slots_available [i] = slots_used [i] = num_blocks [i] = 0;

        /* clear all the free lists */
        for (i = 0; i < MS_BLOCK_TYPE_MAX; ++i) {
                MSBlockInfo **free_blocks = free_block_lists [i];
                int j;
                for (j = 0; j < num_block_obj_sizes; ++j)
                        free_blocks [j] = NULL;
        }

        /* traverse all blocks, free and zero unmarked objects */
        iter = &all_blocks;
        while (*iter) {
                MSBlockInfo *block = *iter;
                int count;
                gboolean have_live = FALSE;
                gboolean has_pinned;
                gboolean have_free = FALSE;
                int obj_size_index;
                int nused = 0;

                obj_size_index = block->obj_size_index;

                has_pinned = block->has_pinned;
                block->has_pinned = block->pinned;

                block->is_to_space = FALSE;
                block->swept = 0;

                count = MS_BLOCK_FREE / block->obj_size;

#ifdef SGEN_HAVE_CONCURRENT_MARK
                if (block->cardtable_mod_union) {
                        sgen_free_internal_dynamic (block->cardtable_mod_union, CARDS_PER_BLOCK, INTERNAL_MEM_CARDTABLE_MOD_UNION);
                        block->cardtable_mod_union = NULL;
                }
#endif

                /* Count marked objects in the block */
                for (i = 0; i < MS_NUM_MARK_WORDS; ++i) {
                        nused += bitcount (block->mark_words [i]);
                }
                if (nused) {
                        have_live = TRUE;
                }
                if (nused < count)
                        have_free = TRUE;

                if (!lazy_sweep)
                        sweep_block (block, TRUE);

                if (have_live) {
                        if (!has_pinned) {
                                ++num_blocks [obj_size_index];
                                slots_used [obj_size_index] += nused;
                                slots_available [obj_size_index] += count;
                        }

                        iter = &block->next;

                        /*
                         * If there are free slots in the block, add
                         * the block to the corresponding free list.
                         */
                        if (have_free) {
                                MSBlockInfo **free_blocks = FREE_BLOCKS (block->pinned, block->has_references);
                                int index = MS_BLOCK_OBJ_SIZE_INDEX (block->obj_size);
                                block->next_free = free_blocks [index];
                                free_blocks [index] = block;
                        }

                        update_heap_boundaries_for_block (block);
                } else {
                        /*
                         * Blocks without live objects are removed from the
                         * block list and freed.
                         */
                        *iter = block->next;

                        binary_protocol_empty (MS_BLOCK_OBJ (block, 0), (char*)MS_BLOCK_OBJ (block, count) - (char*)MS_BLOCK_OBJ (block, 0));
#ifdef FIXED_HEAP
                        ms_free_block (block);
#else
                        ms_free_block (block->block);

                        sgen_free_internal (block, INTERNAL_MEM_MS_BLOCK_INFO);
#endif

                        --num_major_sections;
                }
        }

        for (i = 0; i < num_block_obj_sizes; ++i) {
                float usage = (float)slots_used [i] / (float)slots_available [i];
                if (num_blocks [i] > 5 && usage < evacuation_threshold) {
                        evacuate_block_obj_sizes [i] = TRUE;
                        /*
                        g_print ("slot size %d - %d of %d used\n",
                                        block_obj_sizes [i], slots_used [i], slots_available [i]);
                        */
                } else {
                        evacuate_block_obj_sizes [i] = FALSE;
                }
#ifdef SGEN_HAVE_CONCURRENT_MARK
                {
                        mword total_bytes = block_obj_sizes [i] * slots_available [i];
                        total_evacuate_heap += total_bytes;
                        if (evacuate_block_obj_sizes [i])
                                total_evacuate_saved += total_bytes - block_obj_sizes [i] * slots_used [i];
                }
#endif
        }

#ifdef SGEN_HAVE_CONCURRENT_MARK
        want_evacuation = (float)total_evacuate_saved / (float)total_evacuate_heap > (1 - concurrent_evacuation_threshold);
#endif

        have_swept = TRUE;
}

static void
major_sweep (void)
{
        ms_sweep ();
}

static int count_pinned_ref;
static int count_pinned_nonref;
static int count_nonpinned_ref;
static int count_nonpinned_nonref;

static void
count_nonpinned_callback (char *obj, size_t size, void *data)
{
        MonoVTable *vtable = (MonoVTable*)LOAD_VTABLE (obj);

        if (vtable->klass->has_references)
                ++count_nonpinned_ref;
        else
                ++count_nonpinned_nonref;
}

static void
count_pinned_callback (char *obj, size_t size, void *data)
{
        MonoVTable *vtable = (MonoVTable*)LOAD_VTABLE (obj);

        if (vtable->klass->has_references)
                ++count_pinned_ref;
        else
                ++count_pinned_nonref;
}

static G_GNUC_UNUSED void
count_ref_nonref_objs (void)
{
        int total;

        count_pinned_ref = 0;
        count_pinned_nonref = 0;
        count_nonpinned_ref = 0;
        count_nonpinned_nonref = 0;

        major_iterate_objects (ITERATE_OBJECTS_SWEEP_NON_PINNED, count_nonpinned_callback, NULL);
        major_iterate_objects (ITERATE_OBJECTS_SWEEP_PINNED, count_pinned_callback, NULL);

        total = count_pinned_nonref + count_nonpinned_nonref + count_pinned_ref + count_nonpinned_ref;

        g_print ("ref: %d pinned %d non-pinned   non-ref: %d pinned %d non-pinned  --  %.1f\n",
                        count_pinned_ref, count_nonpinned_ref,
                        count_pinned_nonref, count_nonpinned_nonref,
                        (count_pinned_nonref + count_nonpinned_nonref) * 100.0 / total);
}

static int
ms_calculate_block_obj_sizes (double factor, int *arr)
{
        double target_size = sizeof (MonoObject);
        int num_sizes = 0;
        int last_size = 0;

        do {
                int target_count = (int)ceil (MS_BLOCK_FREE / target_size);
                int size = MIN ((MS_BLOCK_FREE / target_count) & ~(SGEN_ALLOC_ALIGN - 1), SGEN_MAX_SMALL_OBJ_SIZE);

                if (size != last_size) {
                        if (arr)
                                arr [num_sizes] = size;
                        ++num_sizes;
                        last_size = size;
                }

                target_size *= factor;
        } while (last_size < SGEN_MAX_SMALL_OBJ_SIZE);

        return num_sizes;
}

/* only valid during minor collections */
static mword old_num_major_sections;

static void
major_start_nursery_collection (void)
{
#ifdef MARKSWEEP_CONSISTENCY_CHECK
        consistency_check ();
#endif

        old_num_major_sections = num_major_sections;
}

static void
major_finish_nursery_collection (void)
{
#ifdef MARKSWEEP_CONSISTENCY_CHECK
        consistency_check ();
#endif
        sgen_register_major_sections_alloced (num_major_sections - old_num_major_sections);
}

static void
major_start_major_collection (void)
{
        int i;

        /* clear the free lists */
        for (i = 0; i < num_block_obj_sizes; ++i) {
                if (!evacuate_block_obj_sizes [i])
                        continue;

                free_block_lists [0][i] = NULL;
                free_block_lists [MS_BLOCK_FLAG_REFS][i] = NULL;
        }

        // Sweep all unswept blocks
        if (lazy_sweep) {
                MSBlockInfo **iter;

                MONO_GC_SWEEP_BEGIN (GENERATION_OLD, TRUE);

                iter = &all_blocks;
                while (*iter) {
                        MSBlockInfo *block = *iter;

                        sweep_block (block, TRUE);

                        iter = &block->next;
                }

                MONO_GC_SWEEP_END (GENERATION_OLD, TRUE);
        }
}

static void
major_finish_major_collection (void)
{
}

#if !defined(FIXED_HEAP) && SIZEOF_VOID_P != 8
static int
compare_pointers (const void *va, const void *vb) {
        char *a = *(char**)va, *b = *(char**)vb;
        if (a < b)
                return -1;
        if (a > b)
                return 1;
        return 0;
}
#endif

static void
major_have_computer_minor_collection_allowance (void)
{
#ifndef FIXED_HEAP
        size_t section_reserve = sgen_get_minor_collection_allowance () / MS_BLOCK_SIZE;

        g_assert (have_swept);

#if SIZEOF_VOID_P != 8
        {
                int i, num_empty_blocks_orig, num_blocks, arr_length;
                void *block;
                void **empty_block_arr;
                void **rebuild_next;

#ifdef TARGET_WIN32
                /*
                 * sgen_free_os_memory () asserts in mono_vfree () because windows doesn't like freeing the middle of
                 * a VirtualAlloc ()-ed block.
                 */
                return;
#endif

                if (num_empty_blocks <= section_reserve)
                        return;
                SGEN_ASSERT (0, num_empty_blocks > 0, "section reserve can't be negative");

                num_empty_blocks_orig = num_empty_blocks;
                empty_block_arr = (void**)sgen_alloc_internal_dynamic (sizeof (void*) * num_empty_blocks_orig,
                                INTERNAL_MEM_MS_BLOCK_INFO_SORT, FALSE);
                if (!empty_block_arr)
                        goto fallback;

                i = 0;
                for (block = empty_blocks; block; block = *(void**)block)
                        empty_block_arr [i++] = block;
                SGEN_ASSERT (0, i == num_empty_blocks, "empty block count wrong");

                sgen_qsort (empty_block_arr, num_empty_blocks, sizeof (void*), compare_pointers);

                /*
                 * We iterate over the free blocks, trying to find MS_BLOCK_ALLOC_NUM
                 * contiguous ones.  If we do, we free them.  If that's not enough to get to
                 * section_reserve, we halve the number of contiguous blocks we're looking
                 * for and have another go, until we're done with looking for pairs of
                 * blocks, at which point we give up and go to the fallback.
                 */
                arr_length = num_empty_blocks_orig;
                num_blocks = MS_BLOCK_ALLOC_NUM;
                while (num_empty_blocks > section_reserve && num_blocks > 1) {
                        int first = -1;
                        int dest = 0;

                        dest = 0;
                        for (i = 0; i < arr_length; ++i) {
                                int d = dest;
                                void *block = empty_block_arr [i];
                                SGEN_ASSERT (0, block, "we're not shifting correctly");
                                if (i != dest) {
                                        empty_block_arr [dest] = block;
                                        /*
                                         * This is not strictly necessary, but we're
                                         * cautious.
                                         */
                                        empty_block_arr [i] = NULL;
                                }
                                ++dest;

                                if (first < 0) {
                                        first = d;
                                        continue;
                                }

                                SGEN_ASSERT (0, first >= 0 && d > first, "algorithm is wrong");

                                if ((char*)block != ((char*)empty_block_arr [d-1]) + MS_BLOCK_SIZE) {
                                        first = d;
                                        continue;
                                }

                                if (d + 1 - first == num_blocks) {
                                        /*
                                         * We found num_blocks contiguous blocks.  Free them
                                         * and null their array entries.  As an optimization
                                         * we could, instead of nulling the entries, shift
                                         * the following entries over to the left, while
                                         * we're iterating.
                                         */
                                        int j;
                                        sgen_free_os_memory (empty_block_arr [first], MS_BLOCK_SIZE * num_blocks, SGEN_ALLOC_HEAP);
                                        for (j = first; j <= d; ++j)
                                                empty_block_arr [j] = NULL;
                                        dest = first;
                                        first = -1;

                                        num_empty_blocks -= num_blocks;

                                        stat_major_blocks_freed += num_blocks;
                                        if (num_blocks == MS_BLOCK_ALLOC_NUM)
                                                stat_major_blocks_freed_ideal += num_blocks;
                                        else
                                                stat_major_blocks_freed_less_ideal += num_blocks;

                                }
                        }

                        SGEN_ASSERT (0, dest <= i && dest <= arr_length, "array length is off");
                        arr_length = dest;
                        SGEN_ASSERT (0, arr_length == num_empty_blocks, "array length is off");

                        num_blocks >>= 1;
                }

                /* rebuild empty_blocks free list */
                rebuild_next = (void**)&empty_blocks;
                for (i = 0; i < arr_length; ++i) {
                        void *block = empty_block_arr [i];
                        SGEN_ASSERT (0, block, "we're missing blocks");
                        *rebuild_next = block;
                        rebuild_next = (void**)block;
                }
                *rebuild_next = NULL;

                /* free array */
                sgen_free_internal_dynamic (empty_block_arr, sizeof (void*) * num_empty_blocks_orig, INTERNAL_MEM_MS_BLOCK_INFO_SORT);
        }

        SGEN_ASSERT (0, num_empty_blocks >= 0, "we freed more blocks than we had in the first place?");

 fallback:
        /*
         * This is our threshold.  If there's not more empty than used blocks, we won't
         * release uncontiguous blocks, in fear of fragmenting the address space.
         */
        if (num_empty_blocks <= num_major_sections)
                return;
#endif

        while (num_empty_blocks > section_reserve) {
                void *next = *(void**)empty_blocks;
                sgen_free_os_memory (empty_blocks, MS_BLOCK_SIZE, SGEN_ALLOC_HEAP);
                empty_blocks = next;
                /*
                 * Needs not be atomic because this is running
                 * single-threaded.
                 */
                --num_empty_blocks;

                ++stat_major_blocks_freed;
#if SIZEOF_VOID_P != 8
                ++stat_major_blocks_freed_individual;
#endif
        }
#endif
}

static void
major_find_pin_queue_start_ends (SgenGrayQueue *queue)
{
        MSBlockInfo *block;

        FOREACH_BLOCK (block) {
                block->pin_queue_start = sgen_find_optimized_pin_queue_area (block->block + MS_BLOCK_SKIP, block->block + MS_BLOCK_SIZE,
                                &block->pin_queue_num_entries);
        } END_FOREACH_BLOCK;
}

static void
major_pin_objects (SgenGrayQueue *queue)
{
        MSBlockInfo *block;

        FOREACH_BLOCK (block) {
                mark_pinned_objects_in_block (block, queue);
        } END_FOREACH_BLOCK;
}

static void
major_init_to_space (void)
{
}

static void
major_report_pinned_memory_usage (void)
{
        g_assert_not_reached ();
}

static gint64
major_get_used_size (void)
{
        gint64 size = 0;
        MSBlockInfo *block;

        FOREACH_BLOCK (block) {
                int count = MS_BLOCK_FREE / block->obj_size;
                void **iter;
                size += count * block->obj_size;
                for (iter = block->free_list; iter; iter = (void**)*iter)
                        size -= block->obj_size;
        } END_FOREACH_BLOCK;

        return size;
}

static size_t
get_num_major_sections (void)
{
        return num_major_sections;
}

static gboolean
major_handle_gc_param (const char *opt)
{
#ifdef FIXED_HEAP
        if (g_str_has_prefix (opt, "major-heap-size=")) {
                const char *arg = strchr (opt, '=') + 1;
                size_t size;
                if (!mono_gc_parse_environment_string_extract_number (arg, &size))
                        return FALSE;
                ms_heap_num_blocks = (size + MS_BLOCK_SIZE - 1) / MS_BLOCK_SIZE;
                g_assert (ms_heap_num_blocks > 0);
                return TRUE;
        } else
#endif
        if (g_str_has_prefix (opt, "evacuation-threshold=")) {
                const char *arg = strchr (opt, '=') + 1;
                int percentage = atoi (arg);
                if (percentage < 0 || percentage > 100) {
                        fprintf (stderr, "evacuation-threshold must be an integer in the range 0-100.\n");
                        exit (1);
                }
                evacuation_threshold = (float)percentage / 100.0f;
                return TRUE;
        } else if (!strcmp (opt, "lazy-sweep")) {
                lazy_sweep = TRUE;
                return TRUE;
        } else if (!strcmp (opt, "no-lazy-sweep")) {
                lazy_sweep = FALSE;
                return TRUE;
        }

        return FALSE;
}

static void
major_print_gc_param_usage (void)
{
        fprintf (stderr,
                        ""
#ifdef FIXED_HEAP
                        "  major-heap-size=N (where N is an integer, possibly with a k, m or a g suffix)\n"
#endif
                        "  evacuation-threshold=P (where P is a percentage, an integer in 0-100)\n"
                        "  (no-)lazy-sweep\n"
                        );
}

static void
major_iterate_live_block_ranges (sgen_cardtable_block_callback callback)
{
        MSBlockInfo *block;

        FOREACH_BLOCK (block) {
                if (block->has_references)
                        callback ((mword)block->block, MS_BLOCK_SIZE);
        } END_FOREACH_BLOCK;
}

#ifdef HEAVY_STATISTICS
extern long long marked_cards;
extern long long scanned_cards;
extern long long scanned_objects;
extern long long remarked_cards;
#endif

#define CARD_WORDS_PER_BLOCK (CARDS_PER_BLOCK / SIZEOF_VOID_P)
/*
 * MS blocks are 16K aligned.
 * Cardtables are 4K aligned, at least.
 * This means that the cardtable of a given block is 32 bytes aligned.
 */
static guint8*
initial_skip_card (guint8 *card_data)
{
        mword *cards = (mword*)card_data;
        mword card;
        int i;
        for (i = 0; i < CARD_WORDS_PER_BLOCK; ++i) {
                card = cards [i];
                if (card)
                        break;
        }

        if (i == CARD_WORDS_PER_BLOCK)
                return card_data + CARDS_PER_BLOCK;

#if defined(__i386__) && defined(__GNUC__)
        return card_data + i * 4 +  (__builtin_ffs (card) - 1) / 8;
#elif defined(__x86_64__) && defined(__GNUC__)
        return card_data + i * 8 +  (__builtin_ffsll (card) - 1) / 8;
#elif defined(__s390x__) && defined(__GNUC__)
        return card_data + i * 8 +  (__builtin_ffsll (GUINT64_TO_LE(card)) - 1) / 8;
#else
        for (i = i * SIZEOF_VOID_P; i < CARDS_PER_BLOCK; ++i) {
                if (card_data [i])
                        return &card_data [i];
        }
        return card_data;
#endif
}


static G_GNUC_UNUSED guint8*
skip_card (guint8 *card_data, guint8 *card_data_end)
{
        while (card_data < card_data_end && !*card_data)
                ++card_data;
        return card_data;
}

#define MS_BLOCK_OBJ_INDEX_FAST(o,b,os) (((char*)(o) - ((b) + MS_BLOCK_SKIP)) / (os))
#define MS_BLOCK_OBJ_FAST(b,os,i)                       ((b) + MS_BLOCK_SKIP + (os) * (i))
#define MS_OBJ_ALLOCED_FAST(o,b)                (*(void**)(o) && (*(char**)(o) < (b) || *(char**)(o) >= (b) + MS_BLOCK_SIZE))

static void
major_scan_card_table (gboolean mod_union, SgenGrayQueue *queue)
{
        MSBlockInfo *block;
        ScanObjectFunc scan_func = sgen_get_current_object_ops ()->scan_object;

#ifdef SGEN_HAVE_CONCURRENT_MARK
        if (!concurrent_mark)
                g_assert (!mod_union);
#else
        g_assert (!mod_union);
#endif

        FOREACH_BLOCK (block) {
                int block_obj_size;
                char *block_start;

                if (!block->has_references)
                        continue;

                block_obj_size = block->obj_size;
                block_start = block->block;

                if (block_obj_size >= CARD_SIZE_IN_BYTES) {
                        guint8 *cards;
#ifndef SGEN_HAVE_OVERLAPPING_CARDS
                        guint8 cards_data [CARDS_PER_BLOCK];
#endif
                        char *obj, *end, *base;

                        if (mod_union) {
#ifdef SGEN_HAVE_CONCURRENT_MARK
                                cards = block->cardtable_mod_union;
                                /*
                                 * This happens when the nursery
                                 * collection that precedes finishing
                                 * the concurrent collection allocates
                                 * new major blocks.
                                 */
                                if (!cards)
                                        continue;
#endif
                        } else {
                        /*We can avoid the extra copy since the remark cardtable was cleaned before */
#ifdef SGEN_HAVE_OVERLAPPING_CARDS
                                cards = sgen_card_table_get_card_scan_address ((mword)block_start);
#else
                                cards = cards_data;
                                if (!sgen_card_table_get_card_data (cards_data, (mword)block_start, CARDS_PER_BLOCK))
                                        continue;
#endif
                        }

                        obj = (char*)MS_BLOCK_OBJ_FAST (block_start, block_obj_size, 0);
                        end = block_start + MS_BLOCK_SIZE;
                        base = sgen_card_table_align_pointer (obj);

                        while (obj < end) {
                                size_t card_offset;

                                if (!block->swept)
                                        sweep_block (block, FALSE);

                                if (!MS_OBJ_ALLOCED_FAST (obj, block_start))
                                        goto next_large;

                                if (mod_union) {
                                        /* FIXME: do this more efficiently */
                                        int w, b;
                                        MS_CALC_MARK_BIT (w, b, obj);
                                        if (!MS_MARK_BIT (block, w, b))
                                                goto next_large;
                                }

                                card_offset = (obj - base) >> CARD_BITS;
                                sgen_cardtable_scan_object (obj, block_obj_size, cards + card_offset, mod_union, queue);

                        next_large:
                                obj += block_obj_size;
                        }
                } else {
                        guint8 *card_data, *card_base;
                        guint8 *card_data_end;

                        /*
                         * This is safe in face of card aliasing for the following reason:
                         *
                         * Major blocks are 16k aligned, or 32 cards aligned.
                         * Cards aliasing happens in powers of two, so as long as major blocks are aligned to their
                         * sizes, they won't overflow the cardtable overlap modulus.
                         */
                        if (mod_union) {
#ifdef SGEN_HAVE_CONCURRENT_MARK
                                card_data = card_base = block->cardtable_mod_union;
                                /*
                                 * This happens when the nursery
                                 * collection that precedes finishing
                                 * the concurrent collection allocates
                                 * new major blocks.
                                 */
                                if (!card_data)
                                        continue;
#else
                                g_assert_not_reached ();
                                card_data = NULL;
#endif
                        } else {
                                card_data = card_base = sgen_card_table_get_card_scan_address ((mword)block_start);
                        }
                        card_data_end = card_data + CARDS_PER_BLOCK;

                        for (card_data = initial_skip_card (card_data); card_data < card_data_end; ++card_data) { //card_data = skip_card (card_data + 1, card_data_end)) {
                                size_t index;
                                size_t idx = card_data - card_base;
                                char *start = (char*)(block_start + idx * CARD_SIZE_IN_BYTES);
                                char *end = start + CARD_SIZE_IN_BYTES;
                                char *first_obj, *obj;

                                HEAVY_STAT (++scanned_cards);

                                if (!*card_data)
                                        continue;

                                if (!block->swept)
                                        sweep_block (block, FALSE);

                                HEAVY_STAT (++marked_cards);

                                sgen_card_table_prepare_card_for_scanning (card_data);

                                if (idx == 0)
                                        index = 0;
                                else
                                        index = MS_BLOCK_OBJ_INDEX_FAST (start, block_start, block_obj_size);

                                obj = first_obj = (char*)MS_BLOCK_OBJ_FAST (block_start, block_obj_size, index);
                                while (obj < end) {
                                        if (!MS_OBJ_ALLOCED_FAST (obj, block_start))
                                                goto next_small;

                                        if (mod_union) {
                                                /* FIXME: do this more efficiently */
                                                int w, b;
                                                MS_CALC_MARK_BIT (w, b, obj);
                                                if (!MS_MARK_BIT (block, w, b))
                                                        goto next_small;
                                        }

                                        HEAVY_STAT (++scanned_objects);
                                        scan_func (obj, queue);
                                next_small:
                                        obj += block_obj_size;
                                }
                                HEAVY_STAT (if (*card_data) ++remarked_cards);
                                binary_protocol_card_scan (first_obj, obj - first_obj);
                        }
                }
        } END_FOREACH_BLOCK;
}

static void
major_count_cards (long long *num_total_cards, long long *num_marked_cards)
{
        MSBlockInfo *block;
        long long total_cards = 0;
        long long marked_cards = 0;

        FOREACH_BLOCK (block) {
                guint8 *cards = sgen_card_table_get_card_scan_address ((mword) block->block);
                int i;

                if (!block->has_references)
                        continue;

                total_cards += CARDS_PER_BLOCK;
                for (i = 0; i < CARDS_PER_BLOCK; ++i) {
                        if (cards [i])
                                ++marked_cards;
                }
        } END_FOREACH_BLOCK;

        *num_total_cards = total_cards;
        *num_marked_cards = marked_cards;
}

#ifdef SGEN_HAVE_CONCURRENT_MARK
static void
update_cardtable_mod_union (void)
{
        MSBlockInfo *block;

        FOREACH_BLOCK (block) {
                size_t num_cards;

                block->cardtable_mod_union = sgen_card_table_update_mod_union (block->cardtable_mod_union,
                                block->block, MS_BLOCK_SIZE, &num_cards);

                SGEN_ASSERT (0, num_cards == CARDS_PER_BLOCK, "Number of cards calculation is wrong");
        } END_FOREACH_BLOCK;
}

static guint8*
major_get_cardtable_mod_union_for_object (char *obj)
{
        MSBlockInfo *block = MS_BLOCK_FOR_OBJ (obj);
        return &block->cardtable_mod_union [(obj - (char*)sgen_card_table_align_pointer (block->block)) >> CARD_BITS];
}
#endif

static void
alloc_free_block_lists (MSBlockInfo ***lists)
{
        int i;
        for (i = 0; i < MS_BLOCK_TYPE_MAX; ++i)
                lists [i] = sgen_alloc_internal_dynamic (sizeof (MSBlockInfo*) * num_block_obj_sizes, INTERNAL_MEM_MS_TABLES, TRUE);
}

#ifdef SGEN_PARALLEL_MARK
static void*
major_alloc_worker_data (void)
{
        /* FIXME: free this when the workers come down */
        MSBlockInfo ***lists = malloc (sizeof (MSBlockInfo**) * MS_BLOCK_TYPE_MAX);
        alloc_free_block_lists (lists);
        return lists;
}

static void
major_init_worker_thread (void *data)
{
        MSBlockInfo ***lists = data;
        int i;

        g_assert (lists && lists != free_block_lists);
        for (i = 0; i < MS_BLOCK_TYPE_MAX; ++i) {
                int j;
                for (j = 0; j < num_block_obj_sizes; ++j)
                        g_assert (!lists [i][j]);
        }

#ifdef HAVE_KW_THREAD
        workers_free_block_lists = data;
#else
        mono_native_tls_set_value (workers_free_block_lists_key, data);
#endif
}

static void
major_reset_worker_data (void *data)
{
        MSBlockInfo ***lists = data;
        int i;
        for (i = 0; i < MS_BLOCK_TYPE_MAX; ++i) {
                int j;
                for (j = 0; j < num_block_obj_sizes; ++j)
                        lists [i][j] = NULL;
        }
}
#endif

#undef pthread_create

static void
post_param_init (SgenMajorCollector *collector)
{
        collector->sweeps_lazily = lazy_sweep;
}

#ifdef SGEN_HAVE_CONCURRENT_MARK
static void
sgen_marksweep_init_internal (SgenMajorCollector *collector, gboolean is_concurrent)
#else // SGEN_HAVE_CONCURRENT_MARK
#ifdef SGEN_PARALLEL_MARK
#ifdef FIXED_HEAP
void
sgen_marksweep_fixed_par_init (SgenMajorCollector *collector)
#else // FIXED_HEAP
void
sgen_marksweep_par_init (SgenMajorCollector *collector)
#endif // FIXED_HEAP
#else // SGEN_PARALLEL_MARK
#ifdef FIXED_HEAP
void
sgen_marksweep_fixed_init (SgenMajorCollector *collector)
#else // FIXED_HEAP
#error unknown configuration
#endif // FIXED_HEAP
#endif // SGEN_PARALLEL_MARK
#endif // SGEN_HAVE_CONCURRENT_MARK
{
        int i;

#ifndef FIXED_HEAP
        sgen_register_fixed_internal_mem_type (INTERNAL_MEM_MS_BLOCK_INFO, sizeof (MSBlockInfo));
#endif

        num_block_obj_sizes = ms_calculate_block_obj_sizes (MS_BLOCK_OBJ_SIZE_FACTOR, NULL);
        block_obj_sizes = sgen_alloc_internal_dynamic (sizeof (int) * num_block_obj_sizes, INTERNAL_MEM_MS_TABLES, TRUE);
        ms_calculate_block_obj_sizes (MS_BLOCK_OBJ_SIZE_FACTOR, block_obj_sizes);

        evacuate_block_obj_sizes = sgen_alloc_internal_dynamic (sizeof (gboolean) * num_block_obj_sizes, INTERNAL_MEM_MS_TABLES, TRUE);
        for (i = 0; i < num_block_obj_sizes; ++i)
                evacuate_block_obj_sizes [i] = FALSE;

        /*
        {
                int i;
                g_print ("block object sizes:\n");
                for (i = 0; i < num_block_obj_sizes; ++i)
                        g_print ("%d\n", block_obj_sizes [i]);
        }
        */

        alloc_free_block_lists (free_block_lists);

        for (i = 0; i < MS_NUM_FAST_BLOCK_OBJ_SIZE_INDEXES; ++i)
                fast_block_obj_size_indexes [i] = ms_find_block_obj_size_index (i * 8);
        for (i = 0; i < MS_NUM_FAST_BLOCK_OBJ_SIZE_INDEXES * 8; ++i)
                g_assert (MS_BLOCK_OBJ_SIZE_INDEX (i) == ms_find_block_obj_size_index (i));

#ifdef SGEN_PARALLEL_MARK
        LOCK_INIT (ms_block_list_mutex);
#endif

        mono_counters_register ("# major blocks allocated", MONO_COUNTER_GC | MONO_COUNTER_LONG, &stat_major_blocks_alloced);
        mono_counters_register ("# major blocks freed", MONO_COUNTER_GC | MONO_COUNTER_LONG, &stat_major_blocks_freed);
        mono_counters_register ("# major blocks lazy swept", MONO_COUNTER_GC | MONO_COUNTER_LONG, &stat_major_blocks_lazy_swept);
        mono_counters_register ("# major objects evacuated", MONO_COUNTER_GC | MONO_COUNTER_LONG, &stat_major_objects_evacuated);
#if SIZEOF_VOID_P != 8
        mono_counters_register ("# major blocks freed ideally", MONO_COUNTER_GC | MONO_COUNTER_LONG, &stat_major_blocks_freed_ideal);
        mono_counters_register ("# major blocks freed less ideally", MONO_COUNTER_GC | MONO_COUNTER_LONG, &stat_major_blocks_freed_less_ideal);
        mono_counters_register ("# major blocks freed individually", MONO_COUNTER_GC | MONO_COUNTER_LONG, &stat_major_blocks_freed_individual);
        mono_counters_register ("# major blocks allocated less ideally", MONO_COUNTER_GC | MONO_COUNTER_LONG, &stat_major_blocks_alloced_less_ideal);
#endif

#ifdef SGEN_PARALLEL_MARK
#ifndef HAVE_KW_THREAD
        mono_native_tls_alloc (&workers_free_block_lists_key, NULL);
#endif
#endif

        collector->section_size = MAJOR_SECTION_SIZE;
#ifdef SGEN_PARALLEL_MARK
        collector->is_parallel = TRUE;
        collector->alloc_worker_data = major_alloc_worker_data;
        collector->init_worker_thread = major_init_worker_thread;
        collector->reset_worker_data = major_reset_worker_data;
#else
        collector->is_parallel = FALSE;
#endif
#ifdef SGEN_HAVE_CONCURRENT_MARK
        concurrent_mark = is_concurrent;
        if (is_concurrent) {
                collector->is_concurrent = TRUE;
                collector->want_synchronous_collection = &want_evacuation;
                collector->get_and_reset_num_major_objects_marked = major_get_and_reset_num_major_objects_marked;
        } else
#endif
        {
                collector->is_concurrent = FALSE;
                collector->want_synchronous_collection = NULL;
        }
        collector->supports_cardtable = TRUE;

        collector->have_swept = &have_swept;

        collector->alloc_heap = major_alloc_heap;
        collector->is_object_live = major_is_object_live;
        collector->alloc_small_pinned_obj = major_alloc_small_pinned_obj;
        collector->alloc_degraded = major_alloc_degraded;

        collector->alloc_object = major_alloc_object;
#ifdef SGEN_PARALLEL_MARK
        collector->par_alloc_object = major_par_alloc_object;
#endif
        collector->free_pinned_object = free_pinned_object;
        collector->iterate_objects = major_iterate_objects;
        collector->free_non_pinned_object = major_free_non_pinned_object;
        collector->find_pin_queue_start_ends = major_find_pin_queue_start_ends;
        collector->pin_objects = major_pin_objects;
        collector->pin_major_object = pin_major_object;
        collector->scan_card_table = major_scan_card_table;
        collector->iterate_live_block_ranges = (void*)(void*) major_iterate_live_block_ranges;
#ifdef SGEN_HAVE_CONCURRENT_MARK
        if (is_concurrent) {
                collector->update_cardtable_mod_union = update_cardtable_mod_union;
                collector->get_cardtable_mod_union_for_object = major_get_cardtable_mod_union_for_object;
        }
#endif
        collector->init_to_space = major_init_to_space;
        collector->sweep = major_sweep;
        collector->check_scan_starts = major_check_scan_starts;
        collector->dump_heap = major_dump_heap;
        collector->get_used_size = major_get_used_size;
        collector->start_nursery_collection = major_start_nursery_collection;
        collector->finish_nursery_collection = major_finish_nursery_collection;
        collector->start_major_collection = major_start_major_collection;
        collector->finish_major_collection = major_finish_major_collection;
        collector->have_computed_minor_collection_allowance = major_have_computer_minor_collection_allowance;
        collector->ptr_is_in_non_pinned_space = major_ptr_is_in_non_pinned_space;
        collector->obj_is_from_pinned_alloc = obj_is_from_pinned_alloc;
        collector->report_pinned_memory_usage = major_report_pinned_memory_usage;
        collector->get_num_major_sections = get_num_major_sections;
        collector->handle_gc_param = major_handle_gc_param;
        collector->print_gc_param_usage = major_print_gc_param_usage;
        collector->post_param_init = post_param_init;
        collector->is_valid_object = major_is_valid_object;
        collector->describe_pointer = major_describe_pointer;
        collector->count_cards = major_count_cards;

        collector->major_ops.copy_or_mark_object = major_copy_or_mark_object_canonical;
        collector->major_ops.scan_object = major_scan_object;
#ifdef SGEN_HAVE_CONCURRENT_MARK
        if (is_concurrent) {
                collector->major_concurrent_ops.copy_or_mark_object = major_copy_or_mark_object_concurrent_canonical;
                collector->major_concurrent_ops.scan_object = major_scan_object_concurrent;
                collector->major_concurrent_ops.scan_vtype = major_scan_vtype_concurrent;
        }
#endif

        /*cardtable requires major pages to be 8 cards aligned*/
        g_assert ((MS_BLOCK_SIZE % (8 * CARD_SIZE_IN_BYTES)) == 0);
}

#ifdef SGEN_HAVE_CONCURRENT_MARK
void
sgen_marksweep_init (SgenMajorCollector *collector)
{
        sgen_marksweep_init_internal (collector, FALSE);
}

void
sgen_marksweep_conc_init (SgenMajorCollector *collector)
{
        sgen_marksweep_init_internal (collector, TRUE);
}
#endif

#endif