path: root/src/gc/gcpriv.h

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
// optimize for speed


#ifndef _DEBUG
#ifdef _MSC_VER
#pragma optimize( "t", on )
#endif
#endif
#define inline __forceinline

#include "gc.h"

//#define DT_LOG

#include "gcrecord.h"

#ifdef _MSC_VER
#pragma warning(disable:4293)
#pragma warning(disable:4477)
#endif //_MSC_VER

inline void FATAL_GC_ERROR()
{
#ifndef DACCESS_COMPILE
    GCToOSInterface::DebugBreak();
#endif // DACCESS_COMPILE
    _ASSERTE(!"Fatal Error in GC.");
    EEPOLICY_HANDLE_FATAL_ERROR(COR_E_EXECUTIONENGINE);
}

#ifdef _MSC_VER
#pragma inline_depth(20)
#endif

/* the following section defines the optional features */

// FEATURE_STRUCTALIGN was added by Midori. In CLR we are not interested
// in supporting custom alignments on LOH. Currently FEATURE_LOH_COMPACTION
// and FEATURE_STRUCTALIGN are mutually exclusive. It shouldn't be much 
// work to make FEATURE_STRUCTALIGN not apply to LOH so they can be both
// turned on.
#define FEATURE_LOH_COMPACTION

#ifdef FEATURE_64BIT_ALIGNMENT
// We need the following feature as part of keeping 64-bit types aligned in the GC heap.
#define RESPECT_LARGE_ALIGNMENT //used to keep "double" objects aligned during
                                //relocation
#endif //FEATURE_64BIT_ALIGNMENT

#define SHORT_PLUGS //used to keep ephemeral plugs short so they fit better into the oldest generation free items

#ifdef SHORT_PLUGS
#define DESIRED_PLUG_LENGTH (1000)
#endif //SHORT_PLUGS

#define FEATURE_PREMORTEM_FINALIZATION
#define GC_HISTORY

#ifndef FEATURE_REDHAWK
#define HEAP_ANALYZE
#define COLLECTIBLE_CLASS
#endif // !FEATURE_REDHAWK

#ifdef HEAP_ANALYZE
#define initial_internal_roots        (1024*16)
#endif // HEAP_ANALYZE

#define MARK_LIST         //used sorted list to speed up plan phase

#define BACKGROUND_GC   //concurrent background GC (requires WRITE_WATCH)

#ifdef SERVER_GC
#define MH_SC_MARK //scalable marking
//#define SNOOP_STATS //diagnostic
#define PARALLEL_MARK_LIST_SORT //do the sorting and merging of the multiple mark lists in server gc in parallel
#endif //SERVER_GC

//This is used to mark some type volatile only when the scalable marking is used. 
#if defined (SERVER_GC) && defined (MH_SC_MARK)
#define SERVER_SC_MARK_VOLATILE(x) VOLATILE(x)
#else //SERVER_GC&&MH_SC_MARK
#define SERVER_SC_MARK_VOLATILE(x) x
#endif //SERVER_GC&&MH_SC_MARK

//#define MULTIPLE_HEAPS         //Allow multiple heaps for servers

#define INTERIOR_POINTERS   //Allow interior pointers in the code manager

#define CARD_BUNDLE         //enable card bundle feature.(requires WRITE_WATCH)

// If this is defined we use a map for segments in order to find the heap for 
// a segment fast. But it does use more memory as we have to cover the whole
// heap range and for each entry we allocate a struct of 5 ptr-size words
// (3 for WKS as there's only one heap). 
#define SEG_MAPPING_TABLE

// If allocating the heap mapping table for the available VA consumes too
// much memory, you can enable this to allocate only the portion that
// corresponds to rw segments and grow it when needed in grow_brick_card_table.
// However in heap_of you will need to always compare the address with
// g_lowest/highest before you can look at the heap mapping table.
#define GROWABLE_SEG_MAPPING_TABLE

#ifdef BACKGROUND_GC
#define MARK_ARRAY      //Mark bit in an array
#endif //BACKGROUND_GC

#if defined(BACKGROUND_GC) || defined (CARD_BUNDLE) || defined(FEATURE_USE_SOFTWARE_WRITE_WATCH_FOR_GC_HEAP)
#define WRITE_WATCH     //Write Watch feature
#endif //BACKGROUND_GC || CARD_BUNDLE

#ifdef WRITE_WATCH
#define array_size 100
#endif //WRITE_WATCH

//#define SHORT_PLUGS           //keep plug short

#define FFIND_OBJECT        //faster find_object, slower allocation
#define FFIND_DECAY  7      //Number of GC for which fast find will be active

//#define NO_WRITE_BARRIER  //no write barrier, use Write Watch feature

//#define DEBUG_WRITE_WATCH //Additional debug for write watch

//#define STRESS_PINNING    //Stress pinning by pinning randomly

//#define TRACE_GC          //debug trace gc operation
//#define SIMPLE_DPRINTF

//#define TIME_GC           //time allocation and garbage collection
//#define TIME_WRITE_WATCH  //time GetWriteWatch and ResetWriteWatch calls
//#define COUNT_CYCLES  //Use cycle counter for timing
//#define JOIN_STATS         //amount of time spent in the join
//also, see TIME_SUSPEND in switches.h.

//#define SYNCHRONIZATION_STATS
//#define SEG_REUSE_STATS

#if defined (SYNCHRONIZATION_STATS) || defined (STAGE_STATS)
#define BEGIN_TIMING(x) \
    int64_t x##_start; \
    x##_start = GCToOSInterface::QueryPerformanceCounter()

#define END_TIMING(x) \
    int64_t x##_end; \
    x##_end = GCToOSInterface::QueryPerformanceCounter(); \
    x += x##_end - x##_start

#else
#define BEGIN_TIMING(x)
#define END_TIMING(x)
#define BEGIN_TIMING_CYCLES(x)
#define END_TIMING_CYCLES(x)
#endif //SYNCHRONIZATION_STATS || STAGE_STATS

/* End of optional features */

#ifdef GC_CONFIG_DRIVEN
void GCLogConfig (const char *fmt, ... );
#define cprintf(x) {GCLogConfig x;}
#endif //GC_CONFIG_DRIVEN

#ifdef _DEBUG
#define TRACE_GC
#endif

#define NUMBERGENERATIONS   4               //Max number of generations

// For the bestfit algorithm when we relocate ephemeral generations into an 
// existing gen2 segment.
// We recorded sizes from 2^6, 2^7, 2^8...up to 2^30 (1GB). So that's 25 sizes total.
#define MIN_INDEX_POWER2 6

#ifdef SERVER_GC

#ifdef BIT64
#define MAX_INDEX_POWER2 30
#else
#define MAX_INDEX_POWER2 26
#endif  // BIT64

#else //SERVER_GC

#ifdef BIT64
#define MAX_INDEX_POWER2 28
#else
#define MAX_INDEX_POWER2 24
#endif  // BIT64

#endif //SERVER_GC

#define MAX_NUM_BUCKETS (MAX_INDEX_POWER2 - MIN_INDEX_POWER2 + 1)

#define MAX_NUM_FREE_SPACES 200 
#define MIN_NUM_FREE_SPACES 5 

//Please leave these definitions intact.

#define CLREvent CLREventStatic

// hosted api
#ifdef memcpy
#undef memcpy
#endif //memcpy

#ifdef FEATURE_STRUCTALIGN
#define REQD_ALIGN_DCL ,int requiredAlignment
#define REQD_ALIGN_ARG ,requiredAlignment
#define REQD_ALIGN_AND_OFFSET_DCL ,int requiredAlignment,size_t alignmentOffset
#define REQD_ALIGN_AND_OFFSET_DEFAULT_DCL ,int requiredAlignment=DATA_ALIGNMENT,size_t alignmentOffset=0
#define REQD_ALIGN_AND_OFFSET_ARG ,requiredAlignment,alignmentOffset
#else // FEATURE_STRUCTALIGN
#define REQD_ALIGN_DCL
#define REQD_ALIGN_ARG
#define REQD_ALIGN_AND_OFFSET_DCL
#define REQD_ALIGN_AND_OFFSET_DEFAULT_DCL
#define REQD_ALIGN_AND_OFFSET_ARG
#endif // FEATURE_STRUCTALIGN

#ifdef MULTIPLE_HEAPS
#define THREAD_NUMBER_DCL ,int thread
#define THREAD_NUMBER_ARG ,thread
#define THREAD_NUMBER_FROM_CONTEXT int thread = sc->thread_number;
#define THREAD_FROM_HEAP  int thread = heap_number;
#define HEAP_FROM_THREAD  gc_heap* hpt = gc_heap::g_heaps[thread];
#else
#define THREAD_NUMBER_DCL
#define THREAD_NUMBER_ARG
#define THREAD_NUMBER_FROM_CONTEXT
#define THREAD_FROM_HEAP
#define HEAP_FROM_THREAD  gc_heap* hpt = 0;
#endif //MULTIPLE_HEAPS

//These constants are ordered
const int policy_sweep = 0;
const int policy_compact = 1;
const int policy_expand  = 2;

#ifdef TRACE_GC


extern int     print_level;
extern BOOL    trace_gc;
extern int    gc_trace_fac;


class hlet
{
    static hlet* bindings;
    int prev_val;
    int* pval;
    hlet* prev_let;
public:
    hlet (int& place, int value)
    {
        prev_val = place;
        pval = &place;
        place = value;
        prev_let = bindings;
        bindings = this;
    }
    ~hlet ()
    {
        *pval = prev_val;
        bindings = prev_let;
    }
};


#define let(p,v) hlet __x = hlet (p, v);

#else //TRACE_GC

#define gc_count    -1
#define let(s,v)

#endif //TRACE_GC

#ifdef TRACE_GC
#define SEG_REUSE_LOG_0 7
#define SEG_REUSE_LOG_1 (SEG_REUSE_LOG_0 + 1)
#define DT_LOG_0 (SEG_REUSE_LOG_1 + 1)
#define BGC_LOG (DT_LOG_0 + 1)
#define GTC_LOG (DT_LOG_0 + 2)
#define GC_TABLE_LOG (DT_LOG_0 + 3)
#define JOIN_LOG (DT_LOG_0 + 4)
#define SPINLOCK_LOG (DT_LOG_0 + 5)
#define SNOOP_LOG (DT_LOG_0 + 6)

#ifndef DACCESS_COMPILE

#ifdef SIMPLE_DPRINTF

//#define dprintf(l,x) {if (trace_gc && ((l<=print_level)||gc_heap::settings.concurrent)) {printf ("\n");printf x ; fflush(stdout);}}
void GCLog (const char *fmt, ... );
//#define dprintf(l,x) {if (trace_gc && (l<=print_level)) {GCLog x;}}
//#define dprintf(l,x) {if ((l==SEG_REUSE_LOG_0) || (l==SEG_REUSE_LOG_1) || (trace_gc && (l<=3))) {GCLog x;}}
//#define dprintf(l,x) {if (l == DT_LOG_0) {GCLog x;}}
//#define dprintf(l,x) {if (trace_gc && ((l <= 2) || (l == BGC_LOG) || (l==GTC_LOG))) {GCLog x;}}
//#define dprintf(l,x) {if ((l == 1) || (l == 2222)) {GCLog x;}}
#define dprintf(l,x) {if ((l <= 1) || (l == GTC_LOG)) {GCLog x;}}
//#define dprintf(l,x) {if ((l==GTC_LOG) || (l <= 1)) {GCLog x;}}
//#define dprintf(l,x) {if (trace_gc && ((l <= print_level) || (l==GTC_LOG))) {GCLog x;}}
//#define dprintf(l,x) {if (l==GTC_LOG) {printf ("\n");printf x ; fflush(stdout);}}
#else //SIMPLE_DPRINTF

// The GCTrace output goes to stdout by default but can get sent to the stress log or the logfile if the
// reg key GCTraceFacility is set.  THe stress log can only take a format string and 4 numbers or
// string literals.
#define dprintf(l,x) {if (trace_gc && (l<=print_level)) { \
      if ( !gc_trace_fac) {printf ("\n");printf x ; fflush(stdout);} \
      else if ( gc_trace_fac == 2) {LogSpewAlways x;LogSpewAlways ("\n");} \
      else if ( gc_trace_fac == 1) {STRESS_LOG_VA(x);}}}

#endif //SIMPLE_DPRINTF

#else //DACCESS_COMPILE
#define dprintf(l,x)
#endif //DACCESS_COMPILE
#else //TRACE_GC
#define dprintf(l,x)
#endif //TRACE_GC

#ifndef FEATURE_REDHAWK
#undef  assert
#define assert _ASSERTE
#undef  ASSERT
#define ASSERT _ASSERTE
#endif // FEATURE_REDHAWK

#ifdef _DEBUG

struct GCDebugSpinLock {
    VOLATILE(int32_t) lock;                   // -1 if free, 0 if held
    VOLATILE(Thread *) holding_thread;     // -1 if no thread holds the lock.
    VOLATILE(BOOL) released_by_gc_p;       // a GC thread released the lock.

    GCDebugSpinLock()
        : lock(-1), holding_thread((Thread*) -1)
    {
    }
};
typedef GCDebugSpinLock GCSpinLock;

#elif defined (SYNCHRONIZATION_STATS)

struct GCSpinLockInstru {
    VOLATILE(int32_t) lock;
    // number of times we went into SwitchToThread in enter_spin_lock.
    unsigned int num_switch_thread;
    // number of times we went into WaitLonger.
    unsigned int num_wait_longer;
    // number of times we went to calling SwitchToThread in WaitLonger.
    unsigned int num_switch_thread_w;
    // number of times we went to calling DisablePreemptiveGC in WaitLonger.
    unsigned int num_disable_preemptive_w;

    GCSpinLockInstru()
        : lock(-1), num_switch_thread(0), num_wait_longer(0), num_switch_thread_w(0), num_disable_preemptive_w(0)
    {
    }

    void init()
    {
        num_switch_thread = 0;
        num_wait_longer = 0;
        num_switch_thread_w = 0;
        num_disable_preemptive_w = 0;
    }
};

typedef GCSpinLockInstru GCSpinLock;

#else

struct GCDebugSpinLock {
    VOLATILE(int32_t) lock;                   // -1 if free, 0 if held

    GCDebugSpinLock()
        : lock(-1)
    {
    }
};
typedef GCDebugSpinLock GCSpinLock;

#endif

class mark;
class heap_segment;
class CObjectHeader;
class l_heap;
class sorted_table;
class c_synchronize;
class seg_free_spaces;
class gc_heap;

#ifdef BACKGROUND_GC
class exclusive_sync;
class recursive_gc_sync;
#endif //BACKGROUND_GC

// The following 2 modes are of the same format as in clr\src\bcl\system\runtime\gcsettings.cs
// make sure you change that one if you change this one!
enum gc_pause_mode
{
    pause_batch = 0, //We are not concerned about pause length
    pause_interactive = 1,     //We are running an interactive app
    pause_low_latency = 2,     //short pauses are essential
    //avoid long pauses from blocking full GCs unless running out of memory
    pause_sustained_low_latency = 3,
    pause_no_gc = 4
};

enum gc_loh_compaction_mode
{
    loh_compaction_default = 1, // the default mode, don't compact LOH.
    loh_compaction_once = 2, // only compact once the next time a blocking full GC happens.
    loh_compaction_auto = 4 // GC decides when to compact LOH, to be implemented.
};

enum set_pause_mode_status
{
    set_pause_mode_success = 0,
    set_pause_mode_no_gc = 1 // NoGCRegion is in progress, can't change pause mode.
};

enum gc_tuning_point
{
    tuning_deciding_condemned_gen,
    tuning_deciding_full_gc,
    tuning_deciding_compaction,
    tuning_deciding_expansion,
    tuning_deciding_promote_ephemeral
};

#if defined(TRACE_GC) && defined(BACKGROUND_GC)
static const char * const str_bgc_state[] =
{
    "not_in_process",
    "mark_handles",
    "mark_stack",
    "revisit_soh",
    "revisit_loh",
    "overflow_soh",
    "overflow_loh",
    "final_marking",
    "sweep_soh",
    "sweep_loh",
    "plan_phase"
};
#endif // defined(TRACE_GC) && defined(BACKGROUND_GC)

enum allocation_state
{
    a_state_start = 0,
    a_state_can_allocate,
    a_state_cant_allocate,
    a_state_try_fit,
    a_state_try_fit_new_seg,
    a_state_try_fit_new_seg_after_cg,
    a_state_try_fit_no_seg,
    a_state_try_fit_after_cg,
    a_state_try_fit_after_bgc,
    a_state_try_free_full_seg_in_bgc, 
    a_state_try_free_after_bgc,
    a_state_try_seg_end,
    a_state_acquire_seg,
    a_state_acquire_seg_after_cg,
    a_state_acquire_seg_after_bgc,
    a_state_check_and_wait_for_bgc,
    a_state_trigger_full_compact_gc,
    a_state_trigger_ephemeral_gc,
    a_state_trigger_2nd_ephemeral_gc,
    a_state_check_retry_seg,
    a_state_max
};

enum gc_type
{
    gc_type_compacting = 0,
    gc_type_blocking = 1,
#ifdef BACKGROUND_GC
    gc_type_background = 2,
#endif //BACKGROUND_GC
    gc_type_max = 3
};

#define v_high_memory_load_th 97

//encapsulates the mechanism for the current gc
class gc_mechanisms
{
public:
    VOLATILE(size_t) gc_index; // starts from 1 for the first GC, like dd_collection_count
    int condemned_generation;
    BOOL promotion;
    BOOL compaction;
    BOOL loh_compaction;
    BOOL heap_expansion;
    uint32_t concurrent;
    BOOL demotion;
    BOOL card_bundles;
    int  gen0_reduction_count;
    BOOL should_lock_elevation;
    int elevation_locked_count;
    BOOL elevation_reduced;
    BOOL minimal_gc;
    gc_reason reason;
    gc_pause_mode pause_mode;
    BOOL found_finalizers;

#ifdef BACKGROUND_GC
    BOOL background_p;
    bgc_state b_state;
    BOOL allocations_allowed;
#endif //BACKGROUND_GC

#ifdef STRESS_HEAP
    BOOL stress_induced;
#endif // STRESS_HEAP

    uint32_t entry_memory_load;

    void init_mechanisms(); //for each GC
    void first_init(); // for the life of the EE

    void record (gc_history_global* history);
};

// This is a compact version of gc_mechanism that we use to save in the history.
class gc_mechanisms_store
{
public:
    size_t gc_index; 
    bool promotion;
    bool compaction;
    bool loh_compaction;
    bool heap_expansion;
    bool concurrent;
    bool demotion;
    bool card_bundles;
    bool should_lock_elevation;
    int condemned_generation   : 8; 
    int gen0_reduction_count   : 8;
    int elevation_locked_count : 8;
    gc_reason reason           : 8;
    gc_pause_mode pause_mode   : 8;
#ifdef BACKGROUND_GC
    bgc_state b_state          : 8;
#endif //BACKGROUND_GC
    bool found_finalizers;

#ifdef BACKGROUND_GC
    bool background_p;
#endif //BACKGROUND_GC

#ifdef STRESS_HEAP
    bool stress_induced;
#endif // STRESS_HEAP

#ifdef BIT64
    uint32_t entry_memory_load;
#endif // BIT64

    void store (gc_mechanisms* gm)
    {
        gc_index                = gm->gc_index; 
        condemned_generation    = gm->condemned_generation;
        promotion               = (gm->promotion != 0);
        compaction              = (gm->compaction != 0);
        loh_compaction          = (gm->loh_compaction != 0);
        heap_expansion          = (gm->heap_expansion != 0);
        concurrent              = (gm->concurrent != 0);
        demotion                = (gm->demotion != 0);
        card_bundles            = (gm->card_bundles != 0);
        gen0_reduction_count    = gm->gen0_reduction_count;
        should_lock_elevation   = (gm->should_lock_elevation != 0);
        elevation_locked_count  = gm->elevation_locked_count;
        reason                  = gm->reason;
        pause_mode              = gm->pause_mode;
        found_finalizers        = (gm->found_finalizers != 0);

#ifdef BACKGROUND_GC
        background_p            = (gm->background_p != 0);
        b_state                 = gm->b_state;
#endif //BACKGROUND_GC

#ifdef STRESS_HEAP
        stress_induced          = (gm->stress_induced != 0);
#endif // STRESS_HEAP

#ifdef BIT64
        entry_memory_load       = gm->entry_memory_load;
#endif // BIT64        
    }
};

#ifdef GC_STATS

// GC specific statistics, tracking counts and timings for GCs occuring in the system.
// This writes the statistics to a file every 60 seconds, if a file is specified in
// COMPlus_GcMixLog

struct GCStatistics
    : public StatisticsBase
{
    // initialized to the contents of COMPlus_GcMixLog, or NULL, if not present
    static TCHAR* logFileName;
    static FILE*  logFile;

    // number of times we executed a background GC, a foreground GC, or a
    // non-concurrent GC
    int cntBGC, cntFGC, cntNGC;

    // min, max, and total time spent performing BGCs, FGCs, NGCs
    // (BGC time includes everything between the moment the BGC starts until 
    // it completes, i.e. the times of all FGCs occuring concurrently)
    MinMaxTot bgc, fgc, ngc;

    // number of times we executed a compacting GC (sweeping counts can be derived)
    int cntCompactNGC, cntCompactFGC;

    // count of reasons
    int cntReasons[reason_max];

    // count of condemned generation, by NGC and FGC:
    int cntNGCGen[max_generation+1];
    int cntFGCGen[max_generation];
    
    ///////////////////////////////////////////////////////////////////////////////////////////////
    // Internal mechanism:

    virtual void Initialize();
    virtual void DisplayAndUpdate();

    // Public API

    static BOOL Enabled()
    { return logFileName != NULL; }

    void AddGCStats(const gc_mechanisms& settings, size_t timeInMSec);
};

extern GCStatistics g_GCStatistics;
extern GCStatistics g_LastGCStatistics;

#endif // GC_STATS


typedef DPTR(class heap_segment)               PTR_heap_segment;
typedef DPTR(class gc_heap)                    PTR_gc_heap;
typedef DPTR(PTR_gc_heap)                      PTR_PTR_gc_heap;
#ifdef FEATURE_PREMORTEM_FINALIZATION
typedef DPTR(class CFinalize)                  PTR_CFinalize;
#endif // FEATURE_PREMORTEM_FINALIZATION

//-------------------------------------
//generation free list. It is an array of free lists bucketed by size, starting at sizes lower than first_bucket_size 
//and doubling each time. The last bucket (index == num_buckets) is for largest sizes with no limit

#define MAX_BUCKET_COUNT (13)//Max number of buckets for the small generations. 
class alloc_list 
{
    uint8_t* head;
    uint8_t* tail;

    size_t damage_count;
public:
#ifdef FL_VERIFICATION
    size_t item_count;
#endif //FL_VERIFICATION

    uint8_t*& alloc_list_head () { return head;}
    uint8_t*& alloc_list_tail () { return tail;}
    size_t& alloc_list_damage_count(){ return damage_count; }
    alloc_list()
    {
        head = 0; 
        tail = 0; 
        damage_count = 0;
    }
};


class allocator 
{
    size_t num_buckets;
    size_t frst_bucket_size;
    alloc_list first_bucket;
    alloc_list* buckets;
    alloc_list& alloc_list_of (unsigned int bn);
    size_t& alloc_list_damage_count_of (unsigned int bn);

public:
    allocator (unsigned int num_b, size_t fbs, alloc_list* b);
    allocator()
    {
        num_buckets = 1;
        frst_bucket_size = SIZE_T_MAX;
    }
    unsigned int number_of_buckets() {return (unsigned int)num_buckets;}

    size_t first_bucket_size() {return frst_bucket_size;}
    uint8_t*& alloc_list_head_of (unsigned int bn)
    {
        return alloc_list_of (bn).alloc_list_head();
    }
    uint8_t*& alloc_list_tail_of (unsigned int bn)
    {
        return alloc_list_of (bn).alloc_list_tail();
    }
    void clear();
    BOOL discard_if_no_fit_p()
    {
        return (num_buckets == 1);
    }

    // This is when we know there's nothing to repair because this free
    // list has never gone through plan phase. Right now it's only used
    // by the background ephemeral sweep when we copy the local free list
    // to gen0's free list.
    //
    // We copy head and tail manually (vs together like copy_to_alloc_list)
    // since we need to copy tail first because when we get the free items off
    // of each bucket we check head first. We also need to copy the
    // smaller buckets first so when gen0 allocation needs to thread
    // smaller items back that bucket is guaranteed to have been full
    // copied.
    void copy_with_no_repair (allocator* allocator_to_copy)
    {
        assert (num_buckets == allocator_to_copy->number_of_buckets());
        for (unsigned int i = 0; i < num_buckets; i++)
        {
            alloc_list* al = &(allocator_to_copy->alloc_list_of (i));
            alloc_list_tail_of(i) = al->alloc_list_tail();
            alloc_list_head_of(i) = al->alloc_list_head();
        }
    }

    void unlink_item (unsigned int bucket_number, uint8_t* item, uint8_t* previous_item, BOOL use_undo_p);
    void thread_item (uint8_t* item, size_t size);
    void thread_item_front (uint8_t* itme, size_t size);
    void thread_free_item (uint8_t* free_item, uint8_t*& head, uint8_t*& tail);
    void copy_to_alloc_list (alloc_list* toalist);
    void copy_from_alloc_list (alloc_list* fromalist);
    void commit_alloc_list_changes();
};

#define NUM_GEN_POWER2 (20)
#define BASE_GEN_SIZE (1*512)

// group the frequently used ones together (need intrumentation on accessors)
class generation
{
public:
    // Don't move these first two fields without adjusting the references
    // from the __asm in jitinterface.cpp.
    alloc_context   allocation_context;
    heap_segment*   allocation_segment;
    PTR_heap_segment start_segment;
    uint8_t*        allocation_context_start_region;
    uint8_t*        allocation_start;
    allocator       free_list_allocator;
    size_t          free_list_allocated;
    size_t          end_seg_allocated;
    BOOL            allocate_end_seg_p;
    size_t          condemned_allocated;
    size_t          free_list_space;
    size_t          free_obj_space;
    size_t          allocation_size;
    uint8_t*        plan_allocation_start;
    size_t          plan_allocation_start_size;

    // this is the pinned plugs that got allocated into this gen.
    size_t          pinned_allocated;
    size_t          pinned_allocation_compact_size;
    size_t          pinned_allocation_sweep_size;
    int             gen_num;

#ifdef FREE_USAGE_STATS
    size_t          gen_free_spaces[NUM_GEN_POWER2];
    // these are non pinned plugs only
    size_t          gen_plugs[NUM_GEN_POWER2];
    size_t          gen_current_pinned_free_spaces[NUM_GEN_POWER2];
    size_t          pinned_free_obj_space;
    // this is what got allocated into the pinned free spaces.
    size_t          allocated_in_pinned_free;
    size_t          allocated_since_last_pin;
#endif //FREE_USAGE_STATS
};

// The dynamic data fields are grouped into 3 categories:
//
// calculated logical data (like desired_allocation)
// physical data (like fragmentation)
// const data (like min_gc_size), initialized at the beginning
class dynamic_data
{
public:
    ptrdiff_t new_allocation;
    ptrdiff_t gc_new_allocation; // new allocation at beginning of gc
    float     surv;
    size_t    desired_allocation;

    // # of bytes taken by objects (ie, not free space) at the beginning
    // of the GC.
    size_t    begin_data_size;
    // # of bytes taken by survived objects after mark.
    size_t    survived_size;
    // # of bytes taken by survived pinned plugs after mark.
    size_t    pinned_survived_size;
    size_t    artificial_pinned_survived_size;
    size_t    added_pinned_size;

#ifdef SHORT_PLUGS
    size_t    padding_size;
#endif //SHORT_PLUGS
#if defined (RESPECT_LARGE_ALIGNMENT) || defined (FEATURE_STRUCTALIGN)
    // # of plugs that are not pinned plugs.
    size_t    num_npinned_plugs;
#endif //RESPECT_LARGE_ALIGNMENT || FEATURE_STRUCTALIGN
    //total object size after a GC, ie, doesn't include fragmentation
    size_t    current_size; 
    size_t    collection_count;
    size_t    promoted_size;
    size_t    freach_previous_promotion;
    size_t    fragmentation;    //fragmentation when we don't compact
    size_t    gc_clock;         //gc# when last GC happened
    size_t    time_clock;       //time when last gc started
    size_t    gc_elapsed_time;  // Time it took for the gc to complete
    float     gc_speed;         //  speed in bytes/msec for the gc to complete

    // min_size is always the same as min_gc_size..
    size_t    min_gc_size;
    size_t    max_size;
    size_t    min_size;
    size_t    default_new_allocation;
    size_t    fragmentation_limit;
    float     fragmentation_burden_limit;
    float     limit;
    float     max_limit;
};

#define ro_in_entry 0x1

#ifdef SEG_MAPPING_TABLE
// Note that I am storing both h0 and seg0, even though in Server GC you can get to 
// the heap* from the segment info. This is because heap_of needs to be really fast
// and we would not want yet another indirection.
struct seg_mapping
{
    // if an address is > boundary it belongs to h1; else h0.
    // since we init h0 and h1 to 0, if we get 0 it means that
    // address doesn't exist on managed segments. And heap_of 
    // would just return heap0 which is what it does now.
    uint8_t* boundary;
#ifdef MULTIPLE_HEAPS
    gc_heap* h0;
    gc_heap* h1;
#endif //MULTIPLE_HEAPS
    // You could have an address that's inbetween 2 segments and 
    // this would return a seg, the caller then will use 
    // in_range_for_segment to determine if it's on that seg.
    heap_segment* seg0; // this is what the seg for h0 is.
    heap_segment* seg1; // this is what the seg for h1 is.
    // Note that when frozen objects are used we mask seg1
    // with 0x1 to indicate that there is a ro segment for
    // this entry.
};
#endif //SEG_MAPPING_TABLE

// alignment helpers
//Alignment constant for allocation
#define ALIGNCONST (DATA_ALIGNMENT-1)

inline
size_t Align (size_t nbytes, int alignment=ALIGNCONST)
{
    return (nbytes + alignment) & ~alignment;
}

//return alignment constant for small object heap vs large object heap
inline
int get_alignment_constant (BOOL small_object_p)
{
#ifdef FEATURE_STRUCTALIGN
    // If any objects on the large object heap require 8-byte alignment,
    // the compiler will tell us so.  Let's not guess an alignment here.
    return ALIGNCONST;
#else // FEATURE_STRUCTALIGN
    return small_object_p ? ALIGNCONST : 7;
#endif // FEATURE_STRUCTALIGN
}

struct etw_opt_info
{
    size_t desired_allocation;
    size_t new_allocation;
    int    gen_number;
};

enum alloc_wait_reason
{
    // When we don't care about firing an event for
    // this.
    awr_ignored = -1,

    // when we detect we are in low memory
    awr_low_memory = 0,

    // when we detect the ephemeral segment is too full
    awr_low_ephemeral = 1,

    // we've given out too much budget for gen0.
    awr_gen0_alloc = 2,

    // we've given out too much budget for loh.
    awr_loh_alloc = 3,

    // this event is really obsolete - it's for pre-XP
    // OSs where low mem notification is not supported.
    awr_alloc_loh_low_mem = 4,

    // we ran out of VM spaced to reserve on loh.
    awr_loh_oos = 5, 

    // ran out of space when allocating a small object
    awr_gen0_oos_bgc = 6,

    // ran out of space when allocating a large object
    awr_loh_oos_bgc = 7,

    // waiting for BGC to let FGC happen
    awr_fgc_wait_for_bgc = 8,

    // wait for bgc to finish to get loh seg.
    awr_get_loh_seg = 9,

    // we don't allow loh allocation during bgc planning.
    awr_loh_alloc_during_plan = 10,

    // we don't allow too much loh allocation during bgc.
    awr_loh_alloc_during_bgc = 11
};

struct alloc_thread_wait_data
{
    int awr;
};

enum msl_take_state
{
    mt_get_large_seg,
    mt_wait_bgc_plan,
    mt_wait_bgc,
    mt_block_gc,
    mt_clr_mem,
    mt_clr_large_mem,
    mt_t_eph_gc,
    mt_t_full_gc,
    mt_alloc_small,
    mt_alloc_large,
    mt_alloc_small_cant,
    mt_alloc_large_cant,
    mt_try_alloc,
    mt_try_budget
};

enum msl_enter_state
{
    me_acquire,
    me_release
};

struct spinlock_info
{
    msl_enter_state enter_state;
    msl_take_state take_state;
    EEThreadId thread_id;
};

const unsigned HS_CACHE_LINE_SIZE = 128;

#ifdef SNOOP_STATS
struct snoop_stats_data
{
    int heap_index;

    // total number of objects that we called
    // gc_mark on.
    size_t objects_checked_count;
    // total number of time we called gc_mark
    // on a 0 reference.
    size_t zero_ref_count;
    // total objects actually marked.
    size_t objects_marked_count;
    // number of objects written to the mark stack because
    // of mark_stolen.
    size_t stolen_stack_count;
    // number of objects pushed onto the mark stack because
    // of the partial mark code path.
    size_t partial_stack_count;
    // number of objects pushed onto the mark stack because
    // of the non partial mark code path.
    size_t normal_stack_count;
    // number of references marked without mark stack.
    size_t non_stack_count;

    // number of times we detect next heap's mark stack
    // is not busy.
    size_t stack_idle_count;

    // number of times we do switch to thread.
    size_t switch_to_thread_count;

    // number of times we are checking if the next heap's
    // mark stack is busy.
    size_t check_level_count;
    // number of times next stack is busy and level is 
    // at the bottom.
    size_t busy_count;
    // how many interlocked exchange operations we did
    size_t interlocked_count;
    // numer of times parent objects stolen
    size_t partial_mark_parent_count;
    // numer of times we look at a normal stolen entry, 
    // or the beginning/ending PM pair.
    size_t stolen_or_pm_count; 
    // number of times we see 2 for the entry.
    size_t stolen_entry_count; 
    // number of times we see a PM entry that's not ready.
    size_t pm_not_ready_count; 
    // number of stolen normal marked objects and partial mark children.
    size_t normal_count;
    // number of times the bottom of mark stack was cleared.
    size_t stack_bottom_clear_count;
};
#endif //SNOOP_STATS

struct no_gc_region_info
{
    size_t soh_allocation_size;
    size_t loh_allocation_size;
    size_t started;
    size_t num_gcs;
    size_t num_gcs_induced;
    start_no_gc_region_status start_status;
    gc_pause_mode saved_pause_mode;
    size_t saved_gen0_min_size;
    size_t saved_gen3_min_size;
    BOOL minimal_gc_p;
};

// if you change these, make sure you update them for sos (strike.cpp) as well.
// 
// !!!NOTE!!!
// Right now I am only recording data from blocking GCs. When recording from BGC,
// it should have its own copy just like gc_data_per_heap.
// for BGCs we will have a very different set of datapoints to record.
enum interesting_data_point
{
    idp_pre_short = 0,
    idp_post_short = 1,
    idp_merged_pin = 2,
    idp_converted_pin = 3,
    idp_pre_pin = 4,
    idp_post_pin = 5,
    idp_pre_and_post_pin = 6,
    idp_pre_short_padded = 7,
    idp_post_short_padded = 8,
    max_idp_count
};

//class definition of the internal class
class gc_heap
{
    friend struct ::_DacGlobals;
#ifdef DACCESS_COMPILE
    friend class ::ClrDataAccess;
    friend class ::DacHeapWalker;
#endif //DACCESS_COMPILE

    friend class GCHeap;
#ifdef FEATURE_PREMORTEM_FINALIZATION
    friend class CFinalize;
#endif // FEATURE_PREMORTEM_FINALIZATION
    friend struct ::alloc_context;
    friend void ProfScanRootsHelper(Object** object, ScanContext *pSC, uint32_t dwFlags);
    friend void GCProfileWalkHeapWorker(BOOL fProfilerPinned, BOOL fShouldWalkHeapRootsForEtw, BOOL fShouldWalkHeapObjectsForEtw);
    friend class t_join;
    friend class gc_mechanisms;
    friend class seg_free_spaces;

#ifdef BACKGROUND_GC
    friend class exclusive_sync;
    friend class recursive_gc_sync;
#endif //BACKGROUND_GC

#if defined (WRITE_BARRIER_CHECK) && !defined (SERVER_GC)
    friend void checkGCWriteBarrier();
    friend void initGCShadow();
#endif //defined (WRITE_BARRIER_CHECK) && !defined (SERVER_GC)

#ifdef MULTIPLE_HEAPS
    typedef void (gc_heap::* card_fn) (uint8_t**, int);
#define call_fn(fn) (this->*fn)
#define __this this
#else
    typedef void (* card_fn) (uint8_t**);
#define call_fn(fn) (*fn)
#define __this (gc_heap*)0
#endif

public:

#ifdef TRACE_GC
    PER_HEAP
    void print_free_list (int gen, heap_segment* seg);
#endif // TRACE_GC

#ifdef SYNCHRONIZATION_STATS

    PER_HEAP_ISOLATED
    void init_sync_stats()
    {
#ifdef MULTIPLE_HEAPS
        for (int i = 0; i < gc_heap::n_heaps; i++)
        {
            gc_heap::g_heaps[i]->init_heap_sync_stats();
        }
#else  //MULTIPLE_HEAPS
        init_heap_sync_stats();
#endif  //MULTIPLE_HEAPS
    }

    PER_HEAP_ISOLATED
    void print_sync_stats(unsigned int gc_count_during_log)
    {
        // bad/good gl acquire is accumulative during the log interval (because the numbers are too small)
        // min/max msl_acquire is the min/max during the log interval, not each GC.
        // Threads is however many allocation threads for the last GC.
        // num of msl acquired, avg_msl, high and low are all for each GC.
        printf("%2s%2s%10s%10s%12s%6s%4s%8s(  st,  wl, stw, dpw)\n",
            "H", "T", "good_sus", "bad_sus", "avg_msl", "high", "low", "num_msl");

#ifdef MULTIPLE_HEAPS
        for (int i = 0; i < gc_heap::n_heaps; i++)
        {
            gc_heap::g_heaps[i]->print_heap_sync_stats(i, gc_count_during_log);
        }
#else  //MULTIPLE_HEAPS
        print_heap_sync_stats(0, gc_count_during_log);
#endif  //MULTIPLE_HEAPS
    }

#endif //SYNCHRONIZATION_STATS

    PER_HEAP
    void verify_soh_segment_list();
    PER_HEAP
    void verify_mark_array_cleared (heap_segment* seg);
    PER_HEAP
    void verify_mark_array_cleared();
    PER_HEAP
    void verify_seg_end_mark_array_cleared();
    PER_HEAP
    void verify_partial();

#ifdef VERIFY_HEAP
    PER_HEAP
    void verify_free_lists(); 
    PER_HEAP
    void verify_heap (BOOL begin_gc_p);
#endif //VERIFY_HEAP

    PER_HEAP_ISOLATED
    void fire_per_heap_hist_event (gc_history_per_heap* current_gc_data_per_heap, int heap_num);

    PER_HEAP_ISOLATED
    void fire_pevents();

#ifdef FEATURE_BASICFREEZE
    static void walk_read_only_segment(heap_segment *seg, void *pvContext, object_callback_func pfnMethodTable, object_callback_func pfnObjRef);
#endif

    static
    heap_segment* make_heap_segment (uint8_t* new_pages,
                                     size_t size, 
                                     int h_number);
    static
    l_heap* make_large_heap (uint8_t* new_pages, size_t size, BOOL managed);

    static
    gc_heap* make_gc_heap(
#if defined (MULTIPLE_HEAPS)
        GCHeap* vm_heap,
        int heap_number
#endif //MULTIPLE_HEAPS
        );

    static
    void destroy_gc_heap(gc_heap* heap);

    static
    HRESULT initialize_gc  (size_t segment_size,
                            size_t heap_size
#ifdef MULTIPLE_HEAPS
                            , unsigned number_of_heaps
#endif //MULTIPLE_HEAPS
        );

    static
    void shutdown_gc();

    PER_HEAP
    CObjectHeader* allocate (size_t jsize,
                             alloc_context* acontext);

#ifdef MULTIPLE_HEAPS
    static void balance_heaps (alloc_context* acontext);
    static 
    gc_heap* balance_heaps_loh (alloc_context* acontext, size_t size);
    static
    void gc_thread_stub (void* arg);
#endif //MULTIPLE_HEAPS

    CObjectHeader* try_fast_alloc (size_t jsize);

    // For LOH allocations we only update the alloc_bytes_loh in allocation
    // context - we don't actually use the ptr/limit from it so I am
    // making this explicit by not passing in the alloc_context.
    PER_HEAP
    CObjectHeader* allocate_large_object (size_t size, int64_t& alloc_bytes);

#ifdef FEATURE_STRUCTALIGN
    PER_HEAP
    uint8_t* pad_for_alignment_large (uint8_t* newAlloc, int requiredAlignment, size_t size);
#endif // FEATURE_STRUCTALIGN

    PER_HEAP_ISOLATED
    void do_pre_gc();

    PER_HEAP_ISOLATED
    void do_post_gc();

    PER_HEAP
    BOOL expand_soh_with_minimal_gc();

    // EE is always suspended when this method is called.
    // returning FALSE means we actually didn't do a GC. This happens
    // when we figured that we needed to do a BGC.
    PER_HEAP
    int garbage_collect (int n);

    PER_HEAP
    void init_records();

    static 
    uint32_t* make_card_table (uint8_t* start, uint8_t* end);

    static
    void set_fgm_result (failure_get_memory f, size_t s, BOOL loh_p);

    static
    int grow_brick_card_tables (uint8_t* start,
                                uint8_t* end,
                                size_t size,
                                heap_segment* new_seg, 
                                gc_heap* hp,
                                BOOL loh_p);

    PER_HEAP
    BOOL is_mark_set (uint8_t* o);

#ifdef FEATURE_BASICFREEZE
    PER_HEAP_ISOLATED
    bool frozen_object_p(Object* obj);
#endif // FEATURE_BASICFREEZE

protected:

    PER_HEAP_ISOLATED
    void walk_heap (walk_fn fn, void* context, int gen_number, BOOL walk_large_object_heap_p);

    PER_HEAP
    void walk_heap_per_heap (walk_fn fn, void* context, int gen_number, BOOL walk_large_object_heap_p);

    struct walk_relocate_args
    {
        uint8_t* last_plug;
        BOOL is_shortened;
        mark* pinned_plug_entry;
        size_t profiling_context;
        record_surv_fn fn;
    };

    PER_HEAP
    void walk_survivors (record_surv_fn fn, size_t context, walk_surv_type type);

    PER_HEAP
    void walk_plug (uint8_t* plug, size_t size, BOOL check_last_object_p,
                    walk_relocate_args* args);

    PER_HEAP
    void walk_relocation (size_t profiling_context, record_surv_fn fn);

    PER_HEAP
    void walk_relocation_in_brick (uint8_t* tree, walk_relocate_args* args);

    PER_HEAP
    void walk_finalize_queue (fq_walk_fn fn);

#if defined(BACKGROUND_GC) && defined(FEATURE_EVENT_TRACE)
    PER_HEAP
    void walk_survivors_for_bgc (size_t profiling_context, record_surv_fn fn);
#endif // defined(BACKGROUND_GC) && defined(FEATURE_EVENT_TRACE)

    // used in blocking GCs after plan phase so this walks the plugs.
    PER_HEAP
    void walk_survivors_relocation (size_t profiling_context, record_surv_fn fn);
    PER_HEAP
    void walk_survivors_for_loh (size_t profiling_context, record_surv_fn fn);

    PER_HEAP
    int generation_to_condemn (int n, 
                               BOOL* blocking_collection_p,
                               BOOL* elevation_requested_p,
                               BOOL check_only_p);

    PER_HEAP_ISOLATED
    int joined_generation_to_condemn (BOOL should_evaluate_elevation, int n_initial, BOOL* blocking_collection
                                        STRESS_HEAP_ARG(int n_original));

    PER_HEAP
    size_t min_reclaim_fragmentation_threshold (uint32_t num_heaps);

    PER_HEAP_ISOLATED
    uint64_t min_high_fragmentation_threshold (uint64_t available_mem, uint32_t num_heaps);

    PER_HEAP
    void concurrent_print_time_delta (const char* msg);
    PER_HEAP
    void free_list_info (int gen_num, const char* msg);

    // in svr GC on entry and exit of this method, the GC threads are not 
    // synchronized
    PER_HEAP
    void gc1();

    PER_HEAP_ISOLATED
    void save_data_for_no_gc();

    PER_HEAP_ISOLATED
    void restore_data_for_no_gc();

    PER_HEAP_ISOLATED
    void update_collection_counts_for_no_gc();

    PER_HEAP_ISOLATED
    BOOL should_proceed_with_gc();

    PER_HEAP_ISOLATED
    void record_gcs_during_no_gc();

    PER_HEAP
    BOOL find_loh_free_for_no_gc();

    PER_HEAP
    BOOL find_loh_space_for_no_gc();

    PER_HEAP
    BOOL commit_loh_for_no_gc (heap_segment* seg);

    PER_HEAP_ISOLATED
    start_no_gc_region_status prepare_for_no_gc_region (uint64_t total_size,
                                                        BOOL loh_size_known,
                                                        uint64_t loh_size,
                                                        BOOL disallow_full_blocking);

    PER_HEAP
    BOOL loh_allocated_for_no_gc();

    PER_HEAP_ISOLATED
    void release_no_gc_loh_segments();    

    PER_HEAP_ISOLATED
    void thread_no_gc_loh_segments();

    PER_HEAP
    void allocate_for_no_gc_after_gc();

    PER_HEAP
    void set_loh_allocations_for_no_gc();

    PER_HEAP
    void set_soh_allocations_for_no_gc();

    PER_HEAP
    void prepare_for_no_gc_after_gc();

    PER_HEAP_ISOLATED
    void set_allocations_for_no_gc();

    PER_HEAP_ISOLATED
    BOOL should_proceed_for_no_gc();

    PER_HEAP_ISOLATED
    start_no_gc_region_status get_start_no_gc_region_status();

    PER_HEAP_ISOLATED
    end_no_gc_region_status end_no_gc_region();

    PER_HEAP_ISOLATED
    void handle_failure_for_no_gc();

    PER_HEAP
    void fire_etw_allocation_event (size_t allocation_amount, int gen_number, uint8_t* object_address);

    PER_HEAP
    void fire_etw_pin_object_event (uint8_t* object, uint8_t** ppObject);

    PER_HEAP
    size_t limit_from_size (size_t size, size_t room, int gen_number,
                            int align_const);
    PER_HEAP
    int try_allocate_more_space (alloc_context* acontext, size_t jsize,
                                 int alloc_generation_number);
    PER_HEAP
    BOOL allocate_more_space (alloc_context* acontext, size_t jsize,
                              int alloc_generation_number);

    PER_HEAP
    size_t get_full_compact_gc_count();

    PER_HEAP
    BOOL short_on_end_of_seg (int gen_number,
                              heap_segment* seg,
                              int align_const);

    PER_HEAP
    BOOL a_fit_free_list_p (int gen_number, 
                            size_t size, 
                            alloc_context* acontext,
                            int align_const);

#ifdef BACKGROUND_GC
    PER_HEAP
    void wait_for_background (alloc_wait_reason awr);

    PER_HEAP
    void wait_for_bgc_high_memory (alloc_wait_reason awr);

    PER_HEAP
    void bgc_loh_alloc_clr (uint8_t* alloc_start,
                            size_t size, 
                            alloc_context* acontext,
                            int align_const, 
                            int lock_index,
                            BOOL check_used_p,
                            heap_segment* seg);
#endif //BACKGROUND_GC
    
#ifdef BACKGROUND_GC
    PER_HEAP
    void wait_for_background_planning (alloc_wait_reason awr);

    PER_HEAP
    BOOL bgc_loh_should_allocate();
#endif //BACKGROUND_GC

#define max_saved_spinlock_info 48

#ifdef SPINLOCK_HISTORY
    PER_HEAP
    int spinlock_info_index;

    PER_HEAP
    spinlock_info last_spinlock_info[max_saved_spinlock_info + 8];
#endif //SPINLOCK_HISTORY

    PER_HEAP
    void add_saved_spinlock_info (
            msl_enter_state enter_state, 
            msl_take_state take_state);

    PER_HEAP
    BOOL a_fit_free_list_large_p (size_t size, 
                                  alloc_context* acontext,
                                  int align_const);

    PER_HEAP
    BOOL a_fit_segment_end_p (int gen_number,
                              heap_segment* seg,
                              size_t size, 
                              alloc_context* acontext,
                              int align_const,
                              BOOL* commit_failed_p);
    PER_HEAP
    BOOL loh_a_fit_segment_end_p (int gen_number,
                                  size_t size, 
                                  alloc_context* acontext,
                                  int align_const,
                                  BOOL* commit_failed_p,
                                  oom_reason* oom_r);
    PER_HEAP
    BOOL loh_get_new_seg (generation* gen,
                          size_t size,
                          int align_const,
                          BOOL* commit_failed_p,
                          oom_reason* oom_r);

    PER_HEAP_ISOLATED
    size_t get_large_seg_size (size_t size);

    PER_HEAP
    BOOL retry_full_compact_gc (size_t size);

    PER_HEAP
    BOOL check_and_wait_for_bgc (alloc_wait_reason awr,
                                 BOOL* did_full_compact_gc);

    PER_HEAP
    BOOL trigger_full_compact_gc (gc_reason gr, 
                                  oom_reason* oom_r);

    PER_HEAP
    BOOL trigger_ephemeral_gc (gc_reason gr);

    PER_HEAP
    BOOL soh_try_fit (int gen_number,
                      size_t size, 
                      alloc_context* acontext,
                      int align_const,
                      BOOL* commit_failed_p,
                      BOOL* short_seg_end_p);
    PER_HEAP
    BOOL loh_try_fit (int gen_number,
                      size_t size, 
                      alloc_context* acontext,
                      int align_const,
                      BOOL* commit_failed_p,
                      oom_reason* oom_r);

    PER_HEAP
    BOOL allocate_small (int gen_number,
                         size_t size, 
                         alloc_context* acontext,
                         int align_const);

    enum c_gc_state
    {
        c_gc_state_marking,
        c_gc_state_planning,
        c_gc_state_free
    };

#ifdef RECORD_LOH_STATE
    #define max_saved_loh_states 12
    PER_HEAP
    int loh_state_index;

    struct loh_state_info
    {
        allocation_state alloc_state;
        EEThreadId thread_id;
    };

    PER_HEAP
    loh_state_info last_loh_states[max_saved_loh_states];
    PER_HEAP
    void add_saved_loh_state (allocation_state loh_state_to_save, EEThreadId thread_id);
#endif //RECORD_LOH_STATE
    PER_HEAP
    BOOL allocate_large (int gen_number,
                         size_t size, 
                         alloc_context* acontext,
                         int align_const);

    PER_HEAP_ISOLATED
    int init_semi_shared();
    PER_HEAP
    int init_gc_heap (int heap_number);
    PER_HEAP
    void self_destroy();
    PER_HEAP_ISOLATED
    void destroy_semi_shared();
    PER_HEAP
    void repair_allocation_contexts (BOOL repair_p);
    PER_HEAP
    void fix_allocation_contexts (BOOL for_gc_p);
    PER_HEAP
    void fix_youngest_allocation_area (BOOL for_gc_p);
    PER_HEAP
    void fix_allocation_context (alloc_context* acontext, BOOL for_gc_p,
                                 int align_const);
    PER_HEAP
    void fix_large_allocation_area (BOOL for_gc_p);
    PER_HEAP
    void fix_older_allocation_area (generation* older_gen);
    PER_HEAP
    void set_allocation_heap_segment (generation* gen);
    PER_HEAP
    void reset_allocation_pointers (generation* gen, uint8_t* start);
    PER_HEAP
    int object_gennum (uint8_t* o);
    PER_HEAP
    int object_gennum_plan (uint8_t* o);
    PER_HEAP_ISOLATED
    void init_heap_segment (heap_segment* seg);
    PER_HEAP
    void delete_heap_segment (heap_segment* seg, BOOL consider_hoarding=FALSE);
#ifdef FEATURE_BASICFREEZE
    PER_HEAP
    BOOL insert_ro_segment (heap_segment* seg);
    PER_HEAP
    void remove_ro_segment (heap_segment* seg);
#endif //FEATURE_BASICFREEZE
    PER_HEAP
    BOOL set_ro_segment_in_range (heap_segment* seg);
    PER_HEAP
    BOOL unprotect_segment (heap_segment* seg);
    PER_HEAP
    heap_segment* soh_get_segment_to_expand();
    PER_HEAP
    heap_segment* get_segment (size_t size, BOOL loh_p);
    PER_HEAP_ISOLATED
    void seg_mapping_table_add_segment (heap_segment* seg, gc_heap* hp);
    PER_HEAP_ISOLATED
    void seg_mapping_table_remove_segment (heap_segment* seg);
    PER_HEAP
    heap_segment* get_large_segment (size_t size, BOOL* did_full_compact_gc);
    PER_HEAP
    void thread_loh_segment (heap_segment* new_seg);
    PER_HEAP_ISOLATED
    heap_segment* get_segment_for_loh (size_t size
#ifdef MULTIPLE_HEAPS
                                      , gc_heap* hp
#endif //MULTIPLE_HEAPS
                                      );
    PER_HEAP
    void reset_heap_segment_pages (heap_segment* seg);
    PER_HEAP
    void decommit_heap_segment_pages (heap_segment* seg, size_t extra_space);
    PER_HEAP
    void decommit_heap_segment (heap_segment* seg);
    PER_HEAP
    void clear_gen0_bricks();
#ifdef BACKGROUND_GC
    PER_HEAP
    void rearrange_small_heap_segments();
#endif //BACKGROUND_GC
    PER_HEAP
    void rearrange_large_heap_segments();
    PER_HEAP
    void rearrange_heap_segments(BOOL compacting);

    PER_HEAP_ISOLATED
    void reset_write_watch_for_gc_heap(void* base_address, size_t region_size);
    PER_HEAP_ISOLATED
    void get_write_watch_for_gc_heap(bool reset, void *base_address, size_t region_size, void** dirty_pages, uintptr_t* dirty_page_count_ref, bool is_runtime_suspended);

    PER_HEAP
    void switch_one_quantum();
    PER_HEAP
    void reset_ww_by_chunk (uint8_t* start_address, size_t total_reset_size);
    PER_HEAP
    void switch_on_reset (BOOL concurrent_p, size_t* current_total_reset_size, size_t last_reset_size);
    PER_HEAP
    void reset_write_watch (BOOL concurrent_p);
    PER_HEAP
    void adjust_ephemeral_limits ();
    PER_HEAP
    void make_generation (generation& gen, heap_segment* seg,
                          uint8_t* start, uint8_t* pointer);


#define USE_PADDING_FRONT 1
#define USE_PADDING_TAIL  2

    PER_HEAP
    BOOL size_fit_p (size_t size REQD_ALIGN_AND_OFFSET_DCL, uint8_t* alloc_pointer, uint8_t* alloc_limit,
                     uint8_t* old_loc=0, int use_padding=USE_PADDING_TAIL);
    PER_HEAP
    BOOL a_size_fit_p (size_t size, uint8_t* alloc_pointer, uint8_t* alloc_limit,
                       int align_const);

    PER_HEAP
    void handle_oom (int heap_num, oom_reason reason, size_t alloc_size, 
                     uint8_t* allocated, uint8_t* reserved);

    PER_HEAP
    size_t card_of ( uint8_t* object);
    PER_HEAP
    uint8_t* brick_address (size_t brick);
    PER_HEAP
    size_t brick_of (uint8_t* add);
    PER_HEAP
    uint8_t* card_address (size_t card);
    PER_HEAP
    size_t card_to_brick (size_t card);
    PER_HEAP
    void clear_card (size_t card);
    PER_HEAP
    void set_card (size_t card);
    PER_HEAP
    BOOL  card_set_p (size_t card);
    PER_HEAP
    void card_table_set_bit (uint8_t* location);

#ifdef CARD_BUNDLE
    PER_HEAP
    void update_card_table_bundle();
    PER_HEAP
    void reset_card_table_write_watch();
    PER_HEAP
    void card_bundle_clear(size_t cardb);
    PER_HEAP
    void card_bundles_set (size_t start_cardb, size_t end_cardb);
    PER_HEAP
    BOOL card_bundle_set_p (size_t cardb);
    PER_HEAP
    BOOL find_card_dword (size_t& cardw, size_t cardw_end);
    PER_HEAP
    void enable_card_bundles();
    PER_HEAP_ISOLATED
    BOOL card_bundles_enabled();

#endif //CARD_BUNDLE

    PER_HEAP
    BOOL find_card (uint32_t* card_table, size_t& card,
                    size_t card_word_end, size_t& end_card);
    PER_HEAP
    BOOL grow_heap_segment (heap_segment* seg, uint8_t* high_address);
    PER_HEAP
    int grow_heap_segment (heap_segment* seg, uint8_t* high_address, uint8_t* old_loc, size_t size, BOOL pad_front_p REQD_ALIGN_AND_OFFSET_DCL);
    PER_HEAP
    void copy_brick_card_range (uint8_t* la, uint32_t* old_card_table,
                                short* old_brick_table,
                                heap_segment* seg,
                                uint8_t* start, uint8_t* end);
    PER_HEAP
    void init_brick_card_range (heap_segment* seg);
    PER_HEAP
    void copy_brick_card_table_l_heap ();
    PER_HEAP
    void copy_brick_card_table();
    PER_HEAP
    void clear_brick_table (uint8_t* from, uint8_t* end);
    PER_HEAP
    void set_brick (size_t index, ptrdiff_t val);
    PER_HEAP
    int brick_entry (size_t index);
#ifdef MARK_ARRAY
    PER_HEAP
    unsigned int mark_array_marked (uint8_t* add);
    PER_HEAP
    void mark_array_set_marked (uint8_t* add);
    PER_HEAP
    BOOL is_mark_bit_set (uint8_t* add);
    PER_HEAP
    void gmark_array_set_marked (uint8_t* add);
    PER_HEAP
    void set_mark_array_bit (size_t mark_bit);
    PER_HEAP
    BOOL mark_array_bit_set (size_t mark_bit);
    PER_HEAP
    void mark_array_clear_marked (uint8_t* add);
    PER_HEAP
    void clear_mark_array (uint8_t* from, uint8_t* end, BOOL check_only=TRUE
#ifdef FEATURE_BASICFREEZE
        , BOOL read_only=FALSE
#endif // FEATURE_BASICFREEZE
        );
#ifdef BACKGROUND_GC
    PER_HEAP
    void seg_clear_mark_array_bits_soh (heap_segment* seg);
    PER_HEAP
    void clear_batch_mark_array_bits (uint8_t* start, uint8_t* end);
    PER_HEAP
    void bgc_clear_batch_mark_array_bits (uint8_t* start, uint8_t* end);
    PER_HEAP
    void clear_mark_array_by_objects (uint8_t* from, uint8_t* end, BOOL loh_p);
#ifdef VERIFY_HEAP
    PER_HEAP
    void set_batch_mark_array_bits (uint8_t* start, uint8_t* end);
    PER_HEAP
    void check_batch_mark_array_bits (uint8_t* start, uint8_t* end);
#endif //VERIFY_HEAP
#endif //BACKGROUND_GC
#endif //MARK_ARRAY

    PER_HEAP
    BOOL large_object_marked (uint8_t* o, BOOL clearp);

#ifdef BACKGROUND_GC
    PER_HEAP
    BOOL background_allowed_p();
#endif //BACKGROUND_GC

    PER_HEAP_ISOLATED
    void send_full_gc_notification (int gen_num, BOOL due_to_alloc_p);

    PER_HEAP
    void check_for_full_gc (int gen_num, size_t size);

    PER_HEAP
    void adjust_limit (uint8_t* start, size_t limit_size, generation* gen,
                       int gen_number);
    PER_HEAP
    void adjust_limit_clr (uint8_t* start, size_t limit_size,
                           alloc_context* acontext, heap_segment* seg,
                           int align_const, int gen_number);
    PER_HEAP
    void  leave_allocation_segment (generation* gen);

    PER_HEAP
    void init_free_and_plug();

    PER_HEAP
    void print_free_and_plug (const char* msg);

    PER_HEAP
    void add_gen_plug (int gen_number, size_t plug_size);

    PER_HEAP
    void add_gen_free (int gen_number, size_t free_size);

    PER_HEAP
    void add_item_to_current_pinned_free (int gen_number, size_t free_size);
    
    PER_HEAP
    void remove_gen_free (int gen_number, size_t free_size);

    PER_HEAP
    uint8_t* allocate_in_older_generation (generation* gen, size_t size,
                                        int from_gen_number,
                                        uint8_t* old_loc=0
                                        REQD_ALIGN_AND_OFFSET_DEFAULT_DCL);
    PER_HEAP
    generation*  ensure_ephemeral_heap_segment (generation* consing_gen);
    PER_HEAP
    uint8_t* allocate_in_condemned_generations (generation* gen,
                                             size_t size,
                                             int from_gen_number,
#ifdef SHORT_PLUGS
                                             BOOL* convert_to_pinned_p=NULL,
                                             uint8_t* next_pinned_plug=0,
                                             heap_segment* current_seg=0,
#endif //SHORT_PLUGS
                                             uint8_t* old_loc=0
                                             REQD_ALIGN_AND_OFFSET_DEFAULT_DCL);
#ifdef INTERIOR_POINTERS
    // Verifies that interior is actually in the range of seg; otherwise 
    // returns 0.
    PER_HEAP_ISOLATED
    heap_segment* find_segment (uint8_t* interior, BOOL small_segment_only_p);

    PER_HEAP
    heap_segment* find_segment_per_heap (uint8_t* interior, BOOL small_segment_only_p);

    PER_HEAP
    uint8_t* find_object_for_relocation (uint8_t* o, uint8_t* low, uint8_t* high);
#endif //INTERIOR_POINTERS

    PER_HEAP_ISOLATED
    gc_heap* heap_of (uint8_t* object);

    PER_HEAP_ISOLATED
    gc_heap* heap_of_gc (uint8_t* object);

    PER_HEAP_ISOLATED
    size_t&  promoted_bytes (int);

    PER_HEAP
    uint8_t* find_object (uint8_t* o, uint8_t* low);

    PER_HEAP
    dynamic_data* dynamic_data_of (int gen_number);
    PER_HEAP
    ptrdiff_t  get_desired_allocation (int gen_number);
    PER_HEAP
    ptrdiff_t  get_new_allocation (int gen_number);
    PER_HEAP
    ptrdiff_t  get_allocation (int gen_number);
    PER_HEAP
    bool new_allocation_allowed (int gen_number);
#ifdef BACKGROUND_GC
    PER_HEAP_ISOLATED
    void allow_new_allocation (int gen_number);
    PER_HEAP_ISOLATED
    void disallow_new_allocation (int gen_number);
#endif //BACKGROUND_GC
    PER_HEAP
    void reset_pinned_queue();
    PER_HEAP
    void reset_pinned_queue_bos();
    PER_HEAP
    void set_allocator_next_pin (generation* gen);
    PER_HEAP
    void set_allocator_next_pin (uint8_t* alloc_pointer, uint8_t*& alloc_limit);
    PER_HEAP
    void enque_pinned_plug (generation* gen, uint8_t* plug, size_t len);
    PER_HEAP
    void enque_pinned_plug (uint8_t* plug,
                            BOOL save_pre_plug_info_p,
                            uint8_t* last_object_in_last_plug);
    PER_HEAP
    void merge_with_last_pinned_plug (uint8_t* last_pinned_plug, size_t plug_size);
    PER_HEAP
    void set_pinned_info (uint8_t* last_pinned_plug,
                          size_t plug_len,
                          uint8_t* alloc_pointer,
                          uint8_t*& alloc_limit);
    PER_HEAP
    void set_pinned_info (uint8_t* last_pinned_plug, size_t plug_len, generation* gen);
    PER_HEAP
    void save_post_plug_info (uint8_t* last_pinned_plug, uint8_t* last_object_in_last_plug, uint8_t* post_plug);
    PER_HEAP
    size_t deque_pinned_plug ();
    PER_HEAP
    mark* pinned_plug_of (size_t bos);
    PER_HEAP
    mark* oldest_pin ();
    PER_HEAP
    mark* before_oldest_pin();
    PER_HEAP
    BOOL pinned_plug_que_empty_p ();
    PER_HEAP
    void make_mark_stack (mark* arr);
#ifdef MH_SC_MARK
    PER_HEAP
    int& mark_stack_busy();
    PER_HEAP
    VOLATILE(uint8_t*)& ref_mark_stack (gc_heap* hp, int index);
#endif
#ifdef BACKGROUND_GC
    PER_HEAP_ISOLATED
    size_t&  bpromoted_bytes (int);
    PER_HEAP
    void make_background_mark_stack (uint8_t** arr);
    PER_HEAP
    void make_c_mark_list (uint8_t** arr);
#endif //BACKGROUND_GC
    PER_HEAP
    generation* generation_of (int  n);
    PER_HEAP
    BOOL gc_mark1 (uint8_t* o);
    PER_HEAP
    BOOL gc_mark (uint8_t* o, uint8_t* low, uint8_t* high);
    PER_HEAP
    uint8_t* mark_object(uint8_t* o THREAD_NUMBER_DCL);
#ifdef HEAP_ANALYZE
    PER_HEAP
    void ha_mark_object_simple (uint8_t** o THREAD_NUMBER_DCL);
#endif //HEAP_ANALYZE
    PER_HEAP
    void mark_object_simple (uint8_t** o THREAD_NUMBER_DCL);
    PER_HEAP
    void mark_object_simple1 (uint8_t* o, uint8_t* start THREAD_NUMBER_DCL);

#ifdef MH_SC_MARK
    PER_HEAP
    void mark_steal ();
#endif //MH_SC_MARK

#ifdef BACKGROUND_GC

    PER_HEAP
    BOOL background_marked (uint8_t* o);
    PER_HEAP
    BOOL background_mark1 (uint8_t* o);
    PER_HEAP
    BOOL background_mark (uint8_t* o, uint8_t* low, uint8_t* high);
    PER_HEAP
    uint8_t* background_mark_object (uint8_t* o THREAD_NUMBER_DCL);
    PER_HEAP
    void background_mark_simple (uint8_t* o THREAD_NUMBER_DCL);
    PER_HEAP
    void background_mark_simple1 (uint8_t* o THREAD_NUMBER_DCL);
    PER_HEAP_ISOLATED
    void background_promote (Object**, ScanContext* , uint32_t);
    PER_HEAP
    BOOL background_object_marked (uint8_t* o, BOOL clearp);
    PER_HEAP
    void init_background_gc();
    PER_HEAP
    uint8_t* background_next_end (heap_segment*, BOOL);
    PER_HEAP
    void generation_delete_heap_segment (generation*, 
                                         heap_segment*, heap_segment*, heap_segment*);
    PER_HEAP
    void set_mem_verify (uint8_t*, uint8_t*, uint8_t);
    PER_HEAP
    void process_background_segment_end (heap_segment*, generation*, uint8_t*,
                                     heap_segment*, BOOL*);
    PER_HEAP
    void process_n_background_segments (heap_segment*, heap_segment*, generation* gen);
    PER_HEAP
    BOOL fgc_should_consider_object (uint8_t* o,
                                     heap_segment* seg,
                                     BOOL consider_bgc_mark_p,
                                     BOOL check_current_sweep_p,
                                     BOOL check_saved_sweep_p);
    PER_HEAP
    void should_check_bgc_mark (heap_segment* seg, 
                                BOOL* consider_bgc_mark_p, 
                                BOOL* check_current_sweep_p,
                                BOOL* check_saved_sweep_p);
    PER_HEAP
    void background_ephemeral_sweep();
    PER_HEAP
    void background_sweep ();
    PER_HEAP
    void background_mark_through_object (uint8_t* oo THREAD_NUMBER_DCL);
    PER_HEAP
    uint8_t* background_seg_end (heap_segment* seg, BOOL concurrent_p);
    PER_HEAP
    uint8_t* background_first_overflow (uint8_t* min_add,
                                     heap_segment* seg,
                                     BOOL concurrent_p, 
                                     BOOL small_object_p);
    PER_HEAP
    void background_process_mark_overflow_internal (int condemned_gen_number,
                                                    uint8_t* min_add, uint8_t* max_add,
                                                    BOOL concurrent_p);
    PER_HEAP
    BOOL background_process_mark_overflow (BOOL concurrent_p);

    // for foreground GC to get hold of background structures containing refs
    PER_HEAP
    void
    scan_background_roots (promote_func* fn, int hn, ScanContext *pSC);

    PER_HEAP
    BOOL bgc_mark_array_range (heap_segment* seg, 
                               BOOL whole_seg_p,
                               uint8_t** range_beg,
                               uint8_t** range_end);
    PER_HEAP
    void bgc_verify_mark_array_cleared (heap_segment* seg);
    PER_HEAP
    void verify_mark_bits_cleared (uint8_t* obj, size_t s);
    PER_HEAP
    void clear_all_mark_array();
#endif //BACKGROUND_GC

    PER_HEAP
    uint8_t* next_end (heap_segment* seg, uint8_t* f);
    PER_HEAP
    void fix_card_table ();
    PER_HEAP
    void mark_through_object (uint8_t* oo, BOOL mark_class_object_p THREAD_NUMBER_DCL);
    PER_HEAP
    BOOL process_mark_overflow (int condemned_gen_number);
    PER_HEAP
    void process_mark_overflow_internal (int condemned_gen_number,
                                         uint8_t* min_address, uint8_t* max_address);

#ifdef SNOOP_STATS
    PER_HEAP
    void print_snoop_stat();
#endif //SNOOP_STATS

#ifdef MH_SC_MARK

    PER_HEAP
    BOOL check_next_mark_stack (gc_heap* next_heap);

#endif //MH_SC_MARK

    PER_HEAP
    void scan_dependent_handles (int condemned_gen_number, ScanContext *sc, BOOL initial_scan_p);

    PER_HEAP
    void mark_phase (int condemned_gen_number, BOOL mark_only_p);

    PER_HEAP
    void pin_object (uint8_t* o, uint8_t** ppObject, uint8_t* low, uint8_t* high);

#if defined(ENABLE_PERF_COUNTERS) || defined(FEATURE_EVENT_TRACE)
    PER_HEAP_ISOLATED
    size_t get_total_pinned_objects();
#endif //ENABLE_PERF_COUNTERS || FEATURE_EVENT_TRACE

    PER_HEAP
    void reset_mark_stack ();
    PER_HEAP
    uint8_t* insert_node (uint8_t* new_node, size_t sequence_number,
                       uint8_t* tree, uint8_t* last_node);
    PER_HEAP
    size_t update_brick_table (uint8_t* tree, size_t current_brick,
                               uint8_t* x, uint8_t* plug_end);

    PER_HEAP
    void plan_generation_start (generation* gen, generation* consing_gen, uint8_t* next_plug_to_allocate);

    PER_HEAP
    void realloc_plan_generation_start (generation* gen, generation* consing_gen);

    PER_HEAP
    void plan_generation_starts (generation*& consing_gen);

    PER_HEAP
    void advance_pins_for_demotion (generation* gen);

    PER_HEAP
    void process_ephemeral_boundaries(uint8_t* x, int& active_new_gen_number,
                                      int& active_old_gen_number,
                                      generation*& consing_gen,
                                      BOOL& allocate_in_condemned);
    PER_HEAP
    void seg_clear_mark_bits (heap_segment* seg);
    PER_HEAP
    void sweep_ro_segments (heap_segment* start_seg);
    PER_HEAP
    void convert_to_pinned_plug (BOOL& last_npinned_plug_p, 
                                 BOOL& last_pinned_plug_p, 
                                 BOOL& pinned_plug_p,
                                 size_t ps,
                                 size_t& artificial_pinned_size);
    PER_HEAP
    void store_plug_gap_info (uint8_t* plug_start,
                              uint8_t* plug_end,
                              BOOL& last_npinned_plug_p, 
                              BOOL& last_pinned_plug_p, 
                              uint8_t*& last_pinned_plug,
                              BOOL& pinned_plug_p,
                              uint8_t* last_object_in_last_plug,
                              BOOL& merge_with_last_pin_p,
                              // this is only for verification purpose
                              size_t last_plug_len);
    PER_HEAP
    void plan_phase (int condemned_gen_number);

    PER_HEAP
    void record_interesting_data_point (interesting_data_point idp);

#ifdef GC_CONFIG_DRIVEN
    PER_HEAP
    void record_interesting_info_per_heap();
    PER_HEAP_ISOLATED
    void record_global_mechanisms();
    PER_HEAP_ISOLATED
    BOOL should_do_sweeping_gc (BOOL compact_p);
#endif //GC_CONFIG_DRIVEN

#ifdef FEATURE_LOH_COMPACTION
    // plan_loh can allocate memory so it can fail. If it fails, we will
    // fall back to sweeping.  
    PER_HEAP
    BOOL plan_loh();

    PER_HEAP
    void compact_loh();

    PER_HEAP
    void relocate_in_loh_compact();

    PER_HEAP
    void walk_relocation_for_loh (size_t profiling_context, record_surv_fn fn);

    PER_HEAP
    BOOL loh_enque_pinned_plug (uint8_t* plug, size_t len);

    PER_HEAP
    void loh_set_allocator_next_pin();

    PER_HEAP
    BOOL loh_pinned_plug_que_empty_p();

    PER_HEAP
    size_t loh_deque_pinned_plug();

    PER_HEAP
    mark* loh_pinned_plug_of (size_t bos);

    PER_HEAP
    mark* loh_oldest_pin();

    PER_HEAP
    BOOL loh_size_fit_p (size_t size, uint8_t* alloc_pointer, uint8_t* alloc_limit);

    PER_HEAP
    uint8_t* loh_allocate_in_condemned (uint8_t* old_loc, size_t size);

    PER_HEAP_ISOLATED
    BOOL loh_object_p (uint8_t* o);

    PER_HEAP_ISOLATED
    BOOL should_compact_loh();

    // If the LOH compaction mode is just to compact once,
    // we need to see if we should reset it back to not compact.
    // We would only reset if every heap's LOH was compacted.
    PER_HEAP_ISOLATED
    void check_loh_compact_mode  (BOOL all_heaps_compacted_p);
#endif //FEATURE_LOH_COMPACTION

    PER_HEAP
    void decommit_ephemeral_segment_pages (int condemned_gen_number);
    PER_HEAP
    void fix_generation_bounds (int condemned_gen_number,
                                generation* consing_gen);
    PER_HEAP
    uint8_t* generation_limit (int gen_number);

    struct make_free_args
    {
        int free_list_gen_number;
        uint8_t* current_gen_limit;
        generation* free_list_gen;
        uint8_t* highest_plug;
    };
    PER_HEAP
    uint8_t* allocate_at_end (size_t size);
    PER_HEAP
    BOOL ensure_gap_allocation (int condemned_gen_number);
    // make_free_lists is only called by blocking GCs.
    PER_HEAP
    void make_free_lists (int condemned_gen_number);
    PER_HEAP
    void make_free_list_in_brick (uint8_t* tree, make_free_args* args);
    PER_HEAP
    void thread_gap (uint8_t* gap_start, size_t size, generation*  gen);
    PER_HEAP
    void loh_thread_gap_front (uint8_t* gap_start, size_t size, generation*  gen);
    PER_HEAP
    void make_unused_array (uint8_t* x, size_t size, BOOL clearp=FALSE, BOOL resetp=FALSE);
    PER_HEAP
    void clear_unused_array (uint8_t* x, size_t size);
    PER_HEAP
    void relocate_address (uint8_t** old_address THREAD_NUMBER_DCL);
    struct relocate_args
    {
        uint8_t* last_plug;
        uint8_t* low;
        uint8_t* high;
        BOOL is_shortened;
        mark* pinned_plug_entry;
    };

    PER_HEAP
    void reloc_survivor_helper (uint8_t** pval);
    PER_HEAP
    void check_class_object_demotion (uint8_t* obj);
    PER_HEAP
    void check_class_object_demotion_internal (uint8_t* obj);

    PER_HEAP 
    void check_demotion_helper (uint8_t** pval, uint8_t* parent_obj);

    PER_HEAP
    void relocate_survivor_helper (uint8_t* plug, uint8_t* plug_end);

    PER_HEAP
    void verify_pins_with_post_plug_info (const char* msg);

#ifdef COLLECTIBLE_CLASS
    PER_HEAP
    void unconditional_set_card_collectible (uint8_t* obj);
#endif //COLLECTIBLE_CLASS

    PER_HEAP
    void relocate_shortened_survivor_helper (uint8_t* plug, uint8_t* plug_end, mark* pinned_plug_entry);
    
    PER_HEAP
    void relocate_obj_helper (uint8_t* x, size_t s);

    PER_HEAP
    void reloc_ref_in_shortened_obj (uint8_t** address_to_set_card, uint8_t** address_to_reloc);

    PER_HEAP
    void relocate_pre_plug_info (mark* pinned_plug_entry);

    PER_HEAP
    void relocate_shortened_obj_helper (uint8_t* x, size_t s, uint8_t* end, mark* pinned_plug_entry, BOOL is_pinned);

    PER_HEAP
    void relocate_survivors_in_plug (uint8_t* plug, uint8_t* plug_end,
                                     BOOL check_last_object_p, 
                                     mark* pinned_plug_entry);
    PER_HEAP
    void relocate_survivors_in_brick (uint8_t* tree, relocate_args* args);

    PER_HEAP
    void update_oldest_pinned_plug();

    PER_HEAP
    void relocate_survivors (int condemned_gen_number,
                             uint8_t* first_condemned_address );
    PER_HEAP
    void relocate_phase (int condemned_gen_number,
                         uint8_t* first_condemned_address);

    struct compact_args
    {
        BOOL copy_cards_p;
        uint8_t* last_plug;
        ptrdiff_t last_plug_relocation;
        uint8_t* before_last_plug;
        size_t current_compacted_brick;
        BOOL is_shortened;
        mark* pinned_plug_entry;
        BOOL check_gennum_p;
        int src_gennum;

        void print()
        {
            dprintf (3, ("last plug: %Ix, last plug reloc: %Ix, before last: %Ix, b: %Ix",
                last_plug, last_plug_relocation, before_last_plug, current_compacted_brick));
        }
    };

    PER_HEAP
    void copy_cards_range (uint8_t* dest, uint8_t* src, size_t len, BOOL copy_cards_p);
    PER_HEAP
    void  gcmemcopy (uint8_t* dest, uint8_t* src, size_t len, BOOL copy_cards_p);
    PER_HEAP
    void compact_plug (uint8_t* plug, size_t size, BOOL check_last_object_p, compact_args* args);
    PER_HEAP
    void compact_in_brick (uint8_t* tree, compact_args* args);

    PER_HEAP
    mark* get_next_pinned_entry (uint8_t* tree,
                                 BOOL* has_pre_plug_info_p,
                                 BOOL* has_post_plug_info_p,
                                 BOOL deque_p=TRUE);

    PER_HEAP
    mark* get_oldest_pinned_entry (BOOL* has_pre_plug_info_p, BOOL* has_post_plug_info_p);

    PER_HEAP
    void recover_saved_pinned_info();

    PER_HEAP
    void compact_phase (int condemned_gen_number, uint8_t*
                        first_condemned_address, BOOL clear_cards);
    PER_HEAP
    void clear_cards (size_t start_card, size_t end_card);
    PER_HEAP
    void clear_card_for_addresses (uint8_t* start_address, uint8_t* end_address);
    PER_HEAP
    void copy_cards (size_t dst_card, size_t src_card,
                     size_t end_card, BOOL nextp);
    PER_HEAP
    void copy_cards_for_addresses (uint8_t* dest, uint8_t* src, size_t len);

#ifdef BACKGROUND_GC
    PER_HEAP
    void copy_mark_bits (size_t dst_mark_bit, size_t src_mark_bit, size_t end_mark_bit);
    PER_HEAP
    void copy_mark_bits_for_addresses (uint8_t* dest, uint8_t* src, size_t len);
#endif //BACKGROUND_GC


    PER_HEAP
    BOOL ephemeral_pointer_p (uint8_t* o);
    PER_HEAP
    void fix_brick_to_highest (uint8_t* o, uint8_t* next_o);
    PER_HEAP
    uint8_t* find_first_object (uint8_t* start_address, uint8_t* first_object);
    PER_HEAP
    uint8_t* compute_next_boundary (uint8_t* low, int gen_number, BOOL relocating);
    PER_HEAP
    void keep_card_live (uint8_t* o, size_t& n_gen,
                         size_t& cg_pointers_found);
    PER_HEAP
    void mark_through_cards_helper (uint8_t** poo, size_t& ngen,
                                    size_t& cg_pointers_found,
                                    card_fn fn, uint8_t* nhigh,
                                    uint8_t* next_boundary);

    PER_HEAP
    BOOL card_transition (uint8_t* po, uint8_t* end, size_t card_word_end,
                               size_t& cg_pointers_found, 
                               size_t& n_eph, size_t& n_card_set,
                               size_t& card, size_t& end_card,
                               BOOL& foundp, uint8_t*& start_address,
                               uint8_t*& limit, size_t& n_cards_cleared);
    PER_HEAP
    void mark_through_cards_for_segments (card_fn fn, BOOL relocating);

    PER_HEAP
    void repair_allocation_in_expanded_heap (generation* gen);
    PER_HEAP
    BOOL can_fit_in_spaces_p (size_t* ordered_blocks, int small_index, size_t* ordered_spaces, int big_index);
    PER_HEAP
    BOOL can_fit_blocks_p (size_t* ordered_blocks, int block_index, size_t* ordered_spaces, int* space_index);
    PER_HEAP
    BOOL can_fit_all_blocks_p (size_t* ordered_blocks, size_t* ordered_spaces, int count);
#ifdef SEG_REUSE_STATS
    PER_HEAP
    size_t dump_buckets (size_t* ordered_indices, int count, size_t* total_size);
#endif //SEG_REUSE_STATS
    PER_HEAP
    void build_ordered_free_spaces (heap_segment* seg);
    PER_HEAP
    void count_plug (size_t last_plug_size, uint8_t*& last_plug);
    PER_HEAP
    void count_plugs_in_brick (uint8_t* tree, uint8_t*& last_plug);
    PER_HEAP
    void build_ordered_plug_indices ();
    PER_HEAP
    void init_ordered_free_space_indices ();
    PER_HEAP
    void trim_free_spaces_indices ();
    PER_HEAP
    BOOL try_best_fit (BOOL end_of_segment_p);
    PER_HEAP
    BOOL best_fit (size_t free_space, size_t largest_free_space, size_t additional_space, BOOL* use_additional_space);
    PER_HEAP
    BOOL process_free_space (heap_segment* seg, 
                             size_t free_space,
                             size_t min_free_size, 
                             size_t min_cont_size,
                             size_t* total_free_space,
                             size_t* largest_free_space);
    PER_HEAP
    size_t compute_eph_gen_starts_size();
    PER_HEAP
    void compute_new_ephemeral_size();
    PER_HEAP
    BOOL expand_reused_seg_p();
    PER_HEAP
    BOOL can_expand_into_p (heap_segment* seg, size_t min_free_size,
                            size_t min_cont_size, allocator* al);
    PER_HEAP
    uint8_t* allocate_in_expanded_heap (generation* gen, size_t size,
                                     BOOL& adjacentp, uint8_t* old_loc,
#ifdef SHORT_PLUGS
                                     BOOL set_padding_on_saved_p,
                                     mark* pinned_plug_entry,
#endif //SHORT_PLUGS
                                     BOOL consider_bestfit, int active_new_gen_number
                                     REQD_ALIGN_AND_OFFSET_DEFAULT_DCL);
    PER_HEAP
    void realloc_plug (size_t last_plug_size, uint8_t*& last_plug,
                       generation* gen, uint8_t* start_address,
                       unsigned int& active_new_gen_number,
                       uint8_t*& last_pinned_gap, BOOL& leftp,
                       BOOL shortened_p
#ifdef SHORT_PLUGS
                       , mark* pinned_plug_entry
#endif //SHORT_PLUGS
                       );
    PER_HEAP
    void realloc_in_brick (uint8_t* tree, uint8_t*& last_plug, uint8_t* start_address,
                           generation* gen,
                           unsigned int& active_new_gen_number,
                           uint8_t*& last_pinned_gap, BOOL& leftp);
    PER_HEAP
    void realloc_plugs (generation* consing_gen, heap_segment* seg,
                        uint8_t* start_address, uint8_t* end_address,
                        unsigned active_new_gen_number);

    PER_HEAP
    void set_expand_in_full_gc (int condemned_gen_number);

    PER_HEAP
    void verify_no_pins (uint8_t* start, uint8_t* end);

    PER_HEAP
    generation* expand_heap (int condemned_generation,
                             generation* consing_gen,
                             heap_segment* new_heap_segment);

    PER_HEAP
    void save_ephemeral_generation_starts();

    PER_HEAP
    bool init_dynamic_data ();
    PER_HEAP
    float surv_to_growth (float cst, float limit, float max_limit);
    PER_HEAP
    size_t desired_new_allocation (dynamic_data* dd, size_t out,
                                   int gen_number, int pass);

    PER_HEAP
    void trim_youngest_desired_low_memory();

    PER_HEAP
    void decommit_ephemeral_segment_pages();

#ifdef BIT64
    PER_HEAP_ISOLATED
    size_t trim_youngest_desired (uint32_t memory_load,
                                  size_t total_new_allocation,
                                  size_t total_min_allocation);
    PER_HEAP_ISOLATED
    size_t joined_youngest_desired (size_t new_allocation);
#endif // BIT64
    PER_HEAP_ISOLATED
    size_t get_total_heap_size ();
    PER_HEAP_ISOLATED
    size_t get_total_committed_size();

    PER_HEAP_ISOLATED
    void get_memory_info (uint32_t* memory_load, 
                          uint64_t* available_physical=NULL,
                          uint64_t* available_page_file=NULL);
    PER_HEAP
    size_t generation_size (int gen_number);
    PER_HEAP_ISOLATED
    size_t get_total_survived_size();
    PER_HEAP
    size_t get_current_allocated();
    PER_HEAP_ISOLATED
    size_t get_total_allocated();
    PER_HEAP
    size_t current_generation_size (int gen_number);
    PER_HEAP
    size_t generation_plan_size (int gen_number);
    PER_HEAP
    void  compute_promoted_allocation (int gen_number);
    PER_HEAP
    size_t  compute_in (int gen_number);
    PER_HEAP
    void compute_new_dynamic_data (int gen_number);
    PER_HEAP
    gc_history_per_heap* get_gc_data_per_heap();
    PER_HEAP
    size_t new_allocation_limit (size_t size, size_t free_size, int gen_number);
    PER_HEAP
    size_t generation_fragmentation (generation* gen,
                                     generation* consing_gen,
                                     uint8_t* end);
    PER_HEAP
    size_t generation_sizes (generation* gen);
    PER_HEAP
    size_t committed_size();
    PER_HEAP
    size_t approximate_new_allocation();
    PER_HEAP
    size_t end_space_after_gc();
    PER_HEAP
    BOOL decide_on_compacting (int condemned_gen_number,
                               size_t fragmentation,
                               BOOL& should_expand);
    PER_HEAP
    BOOL ephemeral_gen_fit_p (gc_tuning_point tp);
    PER_HEAP
    void reset_large_object (uint8_t* o);
    PER_HEAP
    void sweep_large_objects ();
    PER_HEAP
    void relocate_in_large_objects ();
    PER_HEAP
    void mark_through_cards_for_large_objects (card_fn fn, BOOL relocating);
    PER_HEAP
    void descr_segment (heap_segment* seg);
    PER_HEAP
    void descr_card_table ();
    PER_HEAP
    void descr_generations (BOOL begin_gc_p);

    PER_HEAP_ISOLATED
    void descr_generations_to_profiler (gen_walk_fn fn, void *context);

    /*------------ Multiple non isolated heaps ----------------*/
#ifdef MULTIPLE_HEAPS
    PER_HEAP_ISOLATED
    BOOL   create_thread_support (unsigned number_of_heaps);
    PER_HEAP_ISOLATED
    void destroy_thread_support ();
    PER_HEAP
    bool create_gc_thread();
    PER_HEAP
    void gc_thread_function();
#ifdef MARK_LIST
#ifdef PARALLEL_MARK_LIST_SORT
    PER_HEAP
    void sort_mark_list();
    PER_HEAP
    void merge_mark_lists();
    PER_HEAP
    void append_to_mark_list(uint8_t **start, uint8_t **end);
#else //PARALLEL_MARK_LIST_SORT
    PER_HEAP_ISOLATED
    void combine_mark_lists();
#endif //PARALLEL_MARK_LIST_SORT
#endif
#endif //MULTIPLE_HEAPS

    /*------------ End of Multiple non isolated heaps ---------*/

#ifndef SEG_MAPPING_TABLE
    PER_HEAP_ISOLATED
    heap_segment* segment_of (uint8_t* add,  ptrdiff_t & delta,
                              BOOL verify_p = FALSE);
#endif //SEG_MAPPING_TABLE

#ifdef BACKGROUND_GC

    //this is called by revisit....
    PER_HEAP
    uint8_t* high_page (heap_segment* seg, BOOL concurrent_p);

    PER_HEAP
    void revisit_written_page (uint8_t* page, uint8_t* end, BOOL concurrent_p,
                               heap_segment* seg,  uint8_t*& last_page,
                               uint8_t*& last_object, BOOL large_objects_p,
                               size_t& num_marked_objects);
    PER_HEAP
    void revisit_written_pages (BOOL concurrent_p, BOOL reset_only_p=FALSE);

    PER_HEAP
    void concurrent_scan_dependent_handles (ScanContext *sc);

    PER_HEAP_ISOLATED
    void suspend_EE ();

    PER_HEAP_ISOLATED
    void bgc_suspend_EE ();

    PER_HEAP_ISOLATED
    void restart_EE ();

    PER_HEAP
    void background_verify_mark (Object*& object, ScanContext* sc, uint32_t flags);

    PER_HEAP
    void background_scan_dependent_handles (ScanContext *sc);

    PER_HEAP
    void allow_fgc();

    // Restores BGC settings if necessary.
    PER_HEAP_ISOLATED
    void recover_bgc_settings();

    PER_HEAP
    void save_bgc_data_per_heap();

    PER_HEAP
    BOOL should_commit_mark_array();

    PER_HEAP
    void clear_commit_flag();

    PER_HEAP_ISOLATED
    void clear_commit_flag_global();

    PER_HEAP_ISOLATED
    void verify_mark_array_cleared (heap_segment* seg, uint32_t* mark_array_addr);

    PER_HEAP_ISOLATED
    void verify_mark_array_cleared (uint8_t* begin, uint8_t* end, uint32_t* mark_array_addr);

    PER_HEAP_ISOLATED
    BOOL commit_mark_array_by_range (uint8_t* begin,
                                     uint8_t* end,
                                     uint32_t* mark_array_addr);

    PER_HEAP_ISOLATED
    BOOL commit_mark_array_new_seg (gc_heap* hp, 
                                    heap_segment* seg,
                                    uint32_t* new_card_table = 0,
                                    uint8_t* new_lowest_address = 0);

    PER_HEAP_ISOLATED
    BOOL commit_mark_array_with_check (heap_segment* seg, uint32_t* mark_array_addr);

    // commit the portion of the mark array that corresponds to 
    // this segment (from beginning to reserved).
    // seg and heap_segment_reserved (seg) are guaranteed to be 
    // page aligned.
    PER_HEAP_ISOLATED
    BOOL commit_mark_array_by_seg (heap_segment* seg, uint32_t* mark_array_addr);

    // During BGC init, we commit the mark array for all in range
    // segments whose mark array hasn't been committed or fully
    // committed. All rw segments are in range, only ro segments
    // can be partial in range.
    PER_HEAP
    BOOL commit_mark_array_bgc_init (uint32_t* mark_array_addr);

    PER_HEAP
    BOOL commit_new_mark_array (uint32_t* new_mark_array);

    // We need to commit all segments that intersect with the bgc
    // range. If a segment is only partially in range, we still
    // should commit the mark array for the whole segment as 
    // we will set the mark array commit flag for this segment.
    PER_HEAP_ISOLATED
    BOOL commit_new_mark_array_global (uint32_t* new_mark_array);

    // We can't decommit the first and the last page in the mark array
    // if the beginning and ending don't happen to be page aligned.
    PER_HEAP
    void decommit_mark_array_by_seg (heap_segment* seg);

    PER_HEAP
    void background_mark_phase();

    PER_HEAP
    void background_drain_mark_list (int thread);

    PER_HEAP
    void background_grow_c_mark_list();

    PER_HEAP_ISOLATED
    void background_promote_callback(Object** object, ScanContext* sc, uint32_t flags);

    PER_HEAP
    void mark_absorb_new_alloc();

    PER_HEAP
    void restart_vm();

    PER_HEAP
    BOOL prepare_bgc_thread(gc_heap* gh);
    PER_HEAP
    BOOL create_bgc_thread(gc_heap* gh);
    PER_HEAP_ISOLATED
    BOOL create_bgc_threads_support (int number_of_heaps);
    PER_HEAP
    BOOL create_bgc_thread_support();
    PER_HEAP_ISOLATED
    int check_for_ephemeral_alloc();
    PER_HEAP_ISOLATED
    void wait_to_proceed();
    PER_HEAP_ISOLATED
    void fire_alloc_wait_event_begin (alloc_wait_reason awr);
    PER_HEAP_ISOLATED
    void fire_alloc_wait_event_end (alloc_wait_reason awr);
    PER_HEAP
    void background_gc_wait_lh (alloc_wait_reason awr = awr_ignored);
    PER_HEAP
    uint32_t background_gc_wait (alloc_wait_reason awr = awr_ignored, int time_out_ms = INFINITE);
    PER_HEAP_ISOLATED
    void start_c_gc();
    PER_HEAP
    void kill_gc_thread();
    PER_HEAP
    uint32_t bgc_thread_function();
    PER_HEAP_ISOLATED
    void do_background_gc();
    static
    uint32_t __stdcall bgc_thread_stub (void* arg);

#endif //BACKGROUND_GC
 
public:

    PER_HEAP_ISOLATED
    VOLATILE(bool) internal_gc_done;

#ifdef BACKGROUND_GC
    PER_HEAP_ISOLATED
    uint32_t cm_in_progress;

    PER_HEAP
    BOOL expanded_in_fgc;

    // normally this is FALSE; we set it to TRUE at the end of the gen1 GC
    // we do right before the bgc starts.
    PER_HEAP_ISOLATED
    BOOL     dont_restart_ee_p;

    PER_HEAP_ISOLATED
    CLREvent bgc_start_event;
#endif //BACKGROUND_GC

    PER_HEAP_ISOLATED
    uint32_t wait_for_gc_done(int32_t timeOut = INFINITE);

    // Returns TRUE if the thread used to be in cooperative mode 
    // before calling this function.
    PER_HEAP_ISOLATED
    BOOL enable_preemptive (Thread* current_thread);
    PER_HEAP_ISOLATED
    void disable_preemptive (Thread* current_thread, BOOL restore_cooperative);

    /* ------------------- per heap members --------------------------*/

    PER_HEAP
#ifndef MULTIPLE_HEAPS
    CLREvent gc_done_event;
#else // MULTIPLE_HEAPS
    CLREvent gc_done_event;
#endif // MULTIPLE_HEAPS

    PER_HEAP
    VOLATILE(int32_t) gc_done_event_lock;

    PER_HEAP
    VOLATILE(bool) gc_done_event_set;

    PER_HEAP 
    void set_gc_done();

    PER_HEAP 
    void reset_gc_done();

    PER_HEAP
    void enter_gc_done_event_lock();

    PER_HEAP
    void exit_gc_done_event_lock();

    PER_HEAP
    uint8_t*  ephemeral_low;      //lowest ephemeral address

    PER_HEAP
    uint8_t*  ephemeral_high;     //highest ephemeral address

    PER_HEAP
    uint32_t* card_table;

    PER_HEAP
    short* brick_table;

#ifdef MARK_ARRAY
#ifdef MULTIPLE_HEAPS
    PER_HEAP
    uint32_t* mark_array;
#else
    SPTR_DECL(uint32_t, mark_array);
#endif //MULTIPLE_HEAPS
#endif //MARK_ARRAY

#ifdef CARD_BUNDLE
    PER_HEAP
    uint32_t* card_bundle_table;
#endif //CARD_BUNDLE

#if !defined(SEG_MAPPING_TABLE) || defined(FEATURE_BASICFREEZE)
    PER_HEAP_ISOLATED
    sorted_table* seg_table;
#endif //!SEG_MAPPING_TABLE || FEATURE_BASICFREEZE

    PER_HEAP_ISOLATED
    VOLATILE(BOOL) gc_started;

    // The following 2 events are there to support the gen2 
    // notification feature which is only enabled if concurrent
    // GC is disabled.
    PER_HEAP_ISOLATED
    CLREvent full_gc_approach_event;

    PER_HEAP_ISOLATED
    CLREvent full_gc_end_event;

    // Full GC Notification percentages.
    PER_HEAP_ISOLATED
    uint32_t fgn_maxgen_percent;

    PER_HEAP_ISOLATED
    uint32_t fgn_loh_percent;

    PER_HEAP_ISOLATED
    VOLATILE(bool) full_gc_approach_event_set;

#ifdef BACKGROUND_GC
    PER_HEAP_ISOLATED
    BOOL fgn_last_gc_was_concurrent;
#endif //BACKGROUND_GC

    PER_HEAP
    size_t fgn_last_alloc;

    static uint32_t user_thread_wait (CLREvent *event, BOOL no_mode_change, int time_out_ms=INFINITE);

    static wait_full_gc_status full_gc_wait (CLREvent *event, int time_out_ms);

    PER_HEAP
    uint8_t* demotion_low;

    PER_HEAP
    uint8_t* demotion_high;

    PER_HEAP
    BOOL demote_gen1_p;

    PER_HEAP
    uint8_t* last_gen1_pin_end;

    PER_HEAP
    gen_to_condemn_tuning gen_to_condemn_reasons;

    PER_HEAP
    size_t etw_allocation_running_amount[2];

    PER_HEAP
    int gc_policy;  //sweep, compact, expand

#ifdef MULTIPLE_HEAPS
    PER_HEAP_ISOLATED
    bool gc_thread_no_affinitize_p;

    PER_HEAP_ISOLATED
    CLREvent gc_start_event;

    PER_HEAP_ISOLATED
    CLREvent ee_suspend_event;

    PER_HEAP
    heap_segment* new_heap_segment;

#define alloc_quantum_balance_units (16)

    PER_HEAP_ISOLATED
    size_t min_balance_threshold;
#else //MULTIPLE_HEAPS

    PER_HEAP
    size_t allocation_running_time;

    PER_HEAP
    size_t allocation_running_amount;

#endif //MULTIPLE_HEAPS

    PER_HEAP_ISOLATED
    gc_mechanisms settings;

    PER_HEAP_ISOLATED
    gc_history_global gc_data_global;

    PER_HEAP_ISOLATED
    size_t gc_last_ephemeral_decommit_time;

    PER_HEAP_ISOLATED
    size_t gc_gen0_desired_high;

    PER_HEAP
    size_t gen0_big_free_spaces;

#ifdef SHORT_PLUGS
    PER_HEAP_ISOLATED
    double short_plugs_pad_ratio;
#endif //SHORT_PLUGS

#ifdef BIT64
    PER_HEAP_ISOLATED
    size_t youngest_gen_desired_th;
#endif //BIT64

    PER_HEAP_ISOLATED
    uint32_t high_memory_load_th;

    PER_HEAP_ISOLATED
    uint64_t mem_one_percent;

    PER_HEAP_ISOLATED
    uint64_t total_physical_mem;

    PER_HEAP_ISOLATED
    uint64_t entry_available_physical_mem;

    PER_HEAP_ISOLATED
    size_t last_gc_index;

    PER_HEAP_ISOLATED
    size_t min_segment_size;

    PER_HEAP
    uint8_t* lowest_address;

    PER_HEAP
    uint8_t* highest_address;

    PER_HEAP
    BOOL ephemeral_promotion;
    PER_HEAP
    uint8_t* saved_ephemeral_plan_start[NUMBERGENERATIONS-1];
    PER_HEAP
    size_t saved_ephemeral_plan_start_size[NUMBERGENERATIONS-1];

protected:
#ifdef MULTIPLE_HEAPS
    PER_HEAP
    GCHeap* vm_heap;
    PER_HEAP
    int heap_number;
    PER_HEAP
    VOLATILE(int) alloc_context_count;
#else //MULTIPLE_HEAPS
#define vm_heap ((GCHeap*) g_theGCHeap)
#define heap_number (0)
#endif //MULTIPLE_HEAPS

#ifndef MULTIPLE_HEAPS
    SPTR_DECL(heap_segment,ephemeral_heap_segment);
#else
    PER_HEAP
    heap_segment* ephemeral_heap_segment;
#endif // !MULTIPLE_HEAPS

    PER_HEAP
    size_t time_bgc_last;

    PER_HEAP
    uint8_t*       gc_low; // lowest address being condemned

    PER_HEAP
    uint8_t*       gc_high; //highest address being condemned

    PER_HEAP
    size_t      mark_stack_tos;

    PER_HEAP
    size_t      mark_stack_bos;

    PER_HEAP
    size_t      mark_stack_array_length;

    PER_HEAP
    mark*       mark_stack_array;

    PER_HEAP
    BOOL        verify_pinned_queue_p;

    PER_HEAP
    uint8_t*    oldest_pinned_plug;

#if defined(ENABLE_PERF_COUNTERS) || defined(FEATURE_EVENT_TRACE)
    PER_HEAP
    size_t      num_pinned_objects;
#endif //ENABLE_PERF_COUNTERS || FEATURE_EVENT_TRACE

#ifdef FEATURE_LOH_COMPACTION
    PER_HEAP
    size_t      loh_pinned_queue_tos;

    PER_HEAP
    size_t      loh_pinned_queue_bos;

    PER_HEAP
    size_t      loh_pinned_queue_length;

    PER_HEAP_ISOLATED
    int         loh_pinned_queue_decay;

    PER_HEAP
    mark*       loh_pinned_queue;

    // This is for forced LOH compaction via the complus env var
    PER_HEAP_ISOLATED
    BOOL        loh_compaction_always_p;

    // This is set by the user.
    PER_HEAP_ISOLATED
    gc_loh_compaction_mode loh_compaction_mode;

    // We may not compact LOH on every heap if we can't
    // grow the pinned queue. This is to indicate whether
    // this heap's LOH is compacted or not. So even if
    // settings.loh_compaction is TRUE this may not be TRUE.
    PER_HEAP
    BOOL        loh_compacted_p;
#endif //FEATURE_LOH_COMPACTION

#ifdef BACKGROUND_GC

    PER_HEAP
    EEThreadId bgc_thread_id;

#ifdef WRITE_WATCH
    PER_HEAP
    uint8_t* background_written_addresses [array_size+2];
#endif //WRITE_WATCH

#if defined (DACCESS_COMPILE) && !defined (MULTIPLE_HEAPS)
    // doesn't need to be volatile for DAC.
    SVAL_DECL(c_gc_state, current_c_gc_state);
#else
    PER_HEAP_ISOLATED
    VOLATILE(c_gc_state) current_c_gc_state;     //tells the large object allocator to
    //mark the object as new since the start of gc.
#endif //DACCESS_COMPILE && !MULTIPLE_HEAPS

    PER_HEAP_ISOLATED
    gc_mechanisms saved_bgc_settings;

    PER_HEAP
    gc_history_per_heap bgc_data_per_heap;

    PER_HEAP
    BOOL bgc_thread_running; // gc thread is its main loop

    PER_HEAP_ISOLATED
    BOOL keep_bgc_threads_p;

    // This event is used by BGC threads to do something on 
    // one specific thread while other BGC threads have to 
    // wait. This is different from a join 'cause you can't
    // specify which thread should be doing some task
    // while other threads have to wait.
    // For example, to make the BGC threads managed threads 
    // we need to create them on the thread that called 
    // SuspendEE which is heap 0.
    PER_HEAP_ISOLATED
    CLREvent bgc_threads_sync_event;

    PER_HEAP
    Thread* bgc_thread;

    PER_HEAP
    CLRCriticalSection bgc_threads_timeout_cs;

    PER_HEAP_ISOLATED
    CLREvent background_gc_done_event;

    PER_HEAP_ISOLATED
    CLREvent ee_proceed_event;

    PER_HEAP
    CLREvent gc_lh_block_event;

    PER_HEAP_ISOLATED
    bool gc_can_use_concurrent;

    PER_HEAP_ISOLATED
    bool temp_disable_concurrent_p;

    PER_HEAP_ISOLATED
    BOOL do_ephemeral_gc_p;

    PER_HEAP_ISOLATED
    BOOL do_concurrent_p;

    PER_HEAP
    VOLATILE(bgc_state) current_bgc_state;

    struct gc_history
    {
        size_t gc_index;
        bgc_state current_bgc_state;
        uint32_t gc_time_ms;
        // This is in bytes per ms; consider breaking it 
        // into the efficiency per phase.
        size_t gc_efficiency; 
        uint8_t* eph_low;
        uint8_t* gen0_start;
        uint8_t* eph_high;
        uint8_t* bgc_highest;
        uint8_t* bgc_lowest;
        uint8_t* fgc_highest;
        uint8_t* fgc_lowest;
        uint8_t* g_highest;
        uint8_t* g_lowest;
    };

#define max_history_count 64

    PER_HEAP
    int gchist_index_per_heap;

    PER_HEAP
    gc_history gchist_per_heap[max_history_count];

    PER_HEAP_ISOLATED
    int gchist_index;

    PER_HEAP_ISOLATED
    gc_mechanisms_store gchist[max_history_count];

    PER_HEAP
    void add_to_history_per_heap();

    PER_HEAP_ISOLATED
    void add_to_history();

    PER_HEAP
    size_t total_promoted_bytes;

    PER_HEAP
    size_t     bgc_overflow_count;

    PER_HEAP
    size_t     bgc_begin_loh_size;
    PER_HEAP
    size_t     end_loh_size;

    // We need to throttle the LOH allocations during BGC since we can't
    // collect LOH when BGC is in progress. 
    // We allow the LOH heap size to double during a BGC. So for every
    // 10% increase we will have the LOH allocating thread sleep for one more
    // ms. So we are already 30% over the original heap size the thread will
    // sleep for 3ms.
    PER_HEAP
    uint32_t   bgc_alloc_spin_loh;

    // This includes what we allocate at the end of segment - allocating
    // in free list doesn't increase the heap size.
    PER_HEAP
    size_t     bgc_loh_size_increased;

    PER_HEAP
    size_t     bgc_loh_allocated_in_free;

    PER_HEAP
    size_t     background_soh_alloc_count;

    PER_HEAP
    size_t     background_loh_alloc_count;

    PER_HEAP
    uint8_t**  background_mark_stack_tos;

    PER_HEAP
    uint8_t**  background_mark_stack_array;

    PER_HEAP
    size_t    background_mark_stack_array_length;

    PER_HEAP
    uint8_t*  background_min_overflow_address;

    PER_HEAP
    uint8_t*  background_max_overflow_address;

    // We can't process the soh range concurrently so we
    // wait till final mark to process it.
    PER_HEAP
    BOOL      processed_soh_overflow_p;

    PER_HEAP
    uint8_t*  background_min_soh_overflow_address;

    PER_HEAP
    uint8_t*  background_max_soh_overflow_address;

    PER_HEAP
    heap_segment* saved_overflow_ephemeral_seg;

#ifndef MULTIPLE_HEAPS
    SPTR_DECL(heap_segment, saved_sweep_ephemeral_seg);

    SPTR_DECL(uint8_t, saved_sweep_ephemeral_start);

    SPTR_DECL(uint8_t, background_saved_lowest_address);

    SPTR_DECL(uint8_t, background_saved_highest_address);
#else

    PER_HEAP
    heap_segment* saved_sweep_ephemeral_seg;

    PER_HEAP
    uint8_t* saved_sweep_ephemeral_start;

    PER_HEAP
    uint8_t* background_saved_lowest_address;

    PER_HEAP
    uint8_t* background_saved_highest_address;
#endif //!MULTIPLE_HEAPS

    // This is used for synchronization between the bgc thread
    // for this heap and the user threads allocating on this
    // heap.
    PER_HEAP
    exclusive_sync* bgc_alloc_lock;

#ifdef SNOOP_STATS
    PER_HEAP
    snoop_stats_data snoop_stat;
#endif //SNOOP_STATS


    PER_HEAP
    uint8_t**          c_mark_list;

    PER_HEAP
    size_t          c_mark_list_length;

    PER_HEAP
    size_t          c_mark_list_index;
#endif //BACKGROUND_GC

#ifdef MARK_LIST
    PER_HEAP
    uint8_t** mark_list;

    PER_HEAP_ISOLATED
    size_t mark_list_size;

    PER_HEAP
    uint8_t** mark_list_end;

    PER_HEAP
    uint8_t** mark_list_index;

    PER_HEAP_ISOLATED
    uint8_t** g_mark_list;
#ifdef PARALLEL_MARK_LIST_SORT
    PER_HEAP_ISOLATED
    uint8_t** g_mark_list_copy;
    PER_HEAP
    uint8_t*** mark_list_piece_start;
    uint8_t*** mark_list_piece_end;
#endif //PARALLEL_MARK_LIST_SORT
#endif //MARK_LIST

    PER_HEAP
    uint8_t*  min_overflow_address;

    PER_HEAP
    uint8_t*  max_overflow_address;

    PER_HEAP
    uint8_t*  shigh; //keeps track of the highest marked object

    PER_HEAP
    uint8_t*  slow; //keeps track of the lowest marked object

    PER_HEAP
    size_t allocation_quantum;

    PER_HEAP
    size_t alloc_contexts_used;

    PER_HEAP_ISOLATED
    no_gc_region_info current_no_gc_region_info;

    PER_HEAP
    size_t soh_allocation_no_gc;

    PER_HEAP
    size_t loh_allocation_no_gc;

    PER_HEAP
    heap_segment* saved_loh_segment_no_gc;

    PER_HEAP_ISOLATED
    BOOL proceed_with_gc_p;

#define youngest_generation (generation_of (0))
#define large_object_generation (generation_of (max_generation+1))

#ifndef MULTIPLE_HEAPS
    SPTR_DECL(uint8_t,alloc_allocated);
#else
    PER_HEAP
    uint8_t* alloc_allocated; //keeps track of the highest
    //address allocated by alloc
#endif // !MULTIPLE_HEAPS

    // The more_space_lock and gc_lock is used for 3 purposes:
    //
    // 1) to coordinate threads that exceed their quantum (UP & MP) (more_space_lock)
    // 2) to synchronize allocations of large objects (more_space_lock)
    // 3) to synchronize the GC itself (gc_lock)
    //
    PER_HEAP_ISOLATED
    GCSpinLock gc_lock; //lock while doing GC

    PER_HEAP
    GCSpinLock more_space_lock; //lock while allocating more space

#ifdef SYNCHRONIZATION_STATS

    PER_HEAP
    unsigned int good_suspension;

    PER_HEAP
    unsigned int bad_suspension;

    // Number of times when msl_acquire is > 200 cycles.
    PER_HEAP
    unsigned int num_high_msl_acquire;

    // Number of times when msl_acquire is < 200 cycles.
    PER_HEAP
    unsigned int num_low_msl_acquire;

    // Number of times the more_space_lock is acquired.
    PER_HEAP
    unsigned int num_msl_acquired;

    // Total cycles it takes to acquire the more_space_lock.
    PER_HEAP
    uint64_t total_msl_acquire;

    PER_HEAP
    void init_heap_sync_stats()
    {
        good_suspension = 0;
        bad_suspension = 0;
        num_msl_acquired = 0;
        total_msl_acquire = 0;
        num_high_msl_acquire = 0;
        num_low_msl_acquire = 0;
        more_space_lock.init();
        gc_lock.init();
    }

    PER_HEAP
    void print_heap_sync_stats(unsigned int heap_num, unsigned int gc_count_during_log)
    {
        printf("%2d%2d%10u%10u%12u%6u%4u%8u(%4u,%4u,%4u,%4u)\n",
            heap_num,
            alloc_contexts_used,
            good_suspension,
            bad_suspension,
            (unsigned int)(total_msl_acquire / gc_count_during_log),
            num_high_msl_acquire / gc_count_during_log,
            num_low_msl_acquire / gc_count_during_log,
            num_msl_acquired / gc_count_during_log,
            more_space_lock.num_switch_thread / gc_count_during_log,
            more_space_lock.num_wait_longer / gc_count_during_log,
            more_space_lock.num_switch_thread_w / gc_count_during_log,
            more_space_lock.num_disable_preemptive_w / gc_count_during_log);
    }

#endif //SYNCHRONIZATION_STATS

#ifdef MULTIPLE_HEAPS
    PER_HEAP
    generation generation_table [NUMBERGENERATIONS+1];
#endif


#define NUM_LOH_ALIST (7)
#define BASE_LOH_ALIST (64*1024)
    PER_HEAP 
    alloc_list loh_alloc_list[NUM_LOH_ALIST-1];

#define NUM_GEN2_ALIST (12)
#ifdef BIT64
#define BASE_GEN2_ALIST (1*256)
#else
#define BASE_GEN2_ALIST (1*128)
#endif // BIT64
    PER_HEAP
    alloc_list gen2_alloc_list[NUM_GEN2_ALIST-1];

//------------------------------------------    

    PER_HEAP
    dynamic_data dynamic_data_table [NUMBERGENERATIONS+1];

    PER_HEAP
    gc_history_per_heap gc_data_per_heap;

    PER_HEAP
    size_t maxgen_pinned_compact_before_advance;

    // dynamic tuning.
    PER_HEAP
    BOOL dt_low_ephemeral_space_p (gc_tuning_point tp);
    // if elevate_p is FALSE, it means we are determining fragmentation for a generation
    // to see if we should condemn this gen; otherwise it means we are determining if
    // we should elevate to doing max_gen from an ephemeral gen.
    PER_HEAP
    BOOL dt_high_frag_p (gc_tuning_point tp, int gen_number, BOOL elevate_p=FALSE);
    PER_HEAP
    BOOL 
    dt_estimate_reclaim_space_p (gc_tuning_point tp, int gen_number);
    PER_HEAP
    BOOL dt_estimate_high_frag_p (gc_tuning_point tp, int gen_number, uint64_t available_mem);
    PER_HEAP
    BOOL dt_low_card_table_efficiency_p (gc_tuning_point tp);

    PER_HEAP
    int generation_skip_ratio;//in %

    PER_HEAP
    BOOL gen0_bricks_cleared;
#ifdef FFIND_OBJECT
    PER_HEAP
    int gen0_must_clear_bricks;
#endif //FFIND_OBJECT
    
    PER_HEAP_ISOLATED
    size_t full_gc_counts[gc_type_max];

    // the # of bytes allocates since the last full compacting GC.
    PER_HEAP
    uint64_t loh_alloc_since_cg;

    PER_HEAP
    BOOL elevation_requested;

    // if this is TRUE, we should always guarantee that we do a 
    // full compacting GC before we OOM.
    PER_HEAP
    BOOL last_gc_before_oom;

    PER_HEAP_ISOLATED
    BOOL should_expand_in_full_gc;

#ifdef BACKGROUND_GC
    PER_HEAP_ISOLATED
    size_t ephemeral_fgc_counts[max_generation];

    PER_HEAP_ISOLATED
    BOOL alloc_wait_event_p;

#ifndef MULTIPLE_HEAPS
    SPTR_DECL(uint8_t, next_sweep_obj);
#else
    PER_HEAP
    uint8_t* next_sweep_obj;
#endif //MULTIPLE_HEAPS

    PER_HEAP
    uint8_t* current_sweep_pos;

#endif //BACKGROUND_GC

#ifndef MULTIPLE_HEAPS
    SVAL_DECL(oom_history, oom_info);
#ifdef FEATURE_PREMORTEM_FINALIZATION
    SPTR_DECL(CFinalize,finalize_queue);
#endif //FEATURE_PREMORTEM_FINALIZATION
#else

    PER_HEAP
    oom_history oom_info;

#ifdef FEATURE_PREMORTEM_FINALIZATION
    PER_HEAP
    PTR_CFinalize finalize_queue;
#endif //FEATURE_PREMORTEM_FINALIZATION
#endif // !MULTIPLE_HEAPS

    PER_HEAP
    fgm_history fgm_result;

    PER_HEAP_ISOLATED
    size_t eph_gen_starts_size;

#ifdef GC_CONFIG_DRIVEN
    PER_HEAP_ISOLATED
    size_t time_init;

    PER_HEAP_ISOLATED
    size_t time_since_init;

    // 0 stores compacting GCs;
    // 1 stores sweeping GCs;
    PER_HEAP_ISOLATED
    size_t compact_or_sweep_gcs[2];

    PER_HEAP
    size_t interesting_data_per_gc[max_idp_count];

#ifdef MULTIPLE_HEAPS
    PER_HEAP
    size_t interesting_data_per_heap[max_idp_count];

    PER_HEAP
    size_t compact_reasons_per_heap[max_compact_reasons_count];

    PER_HEAP
    size_t expand_mechanisms_per_heap[max_expand_mechanisms_count];

    PER_HEAP
    size_t interesting_mechanism_bits_per_heap[max_gc_mechanism_bits_count];
#endif //MULTIPLE_HEAPS
#endif //GC_CONFIG_DRIVEN

    PER_HEAP
    BOOL        ro_segments_in_range;

#ifdef BACKGROUND_GC
    PER_HEAP
    heap_segment* freeable_small_heap_segment;
#endif //BACKGROUND_GC

    PER_HEAP
    heap_segment* freeable_large_heap_segment;

    PER_HEAP_ISOLATED
    heap_segment* segment_standby_list;

    PER_HEAP
    size_t ordered_free_space_indices[MAX_NUM_BUCKETS];

    PER_HEAP
    size_t saved_ordered_free_space_indices[MAX_NUM_BUCKETS];

    PER_HEAP
    size_t ordered_plug_indices[MAX_NUM_BUCKETS];

    PER_HEAP
    size_t saved_ordered_plug_indices[MAX_NUM_BUCKETS];

    PER_HEAP
    BOOL ordered_plug_indices_init;

    PER_HEAP
    BOOL use_bestfit;

    PER_HEAP
    uint8_t* bestfit_first_pin;

    PER_HEAP
    BOOL commit_end_of_seg;

    PER_HEAP
    size_t max_free_space_items; // dynamically adjusted.

    PER_HEAP
    size_t free_space_buckets;

    PER_HEAP
    size_t free_space_items;

    // -1 means we are using all the free
    // spaces we have (not including
    // end of seg space).
    PER_HEAP
    int trimmed_free_space_index;

    PER_HEAP
    size_t total_ephemeral_plugs;

    PER_HEAP
    seg_free_spaces* bestfit_seg;

    // Note: we know this from the plan phase.
    // total_ephemeral_plugs actually has the same value
    // but while we are calculating its value we also store
    // info on how big the plugs are for best fit which we
    // don't do in plan phase.
    // TODO: get rid of total_ephemeral_plugs.
    PER_HEAP
    size_t total_ephemeral_size;

public:

#ifdef HEAP_ANALYZE

    PER_HEAP_ISOLATED
    BOOL heap_analyze_enabled;

    PER_HEAP
    size_t internal_root_array_length;

#ifndef MULTIPLE_HEAPS
    SPTR_DECL(PTR_uint8_t, internal_root_array);
    SVAL_DECL(size_t, internal_root_array_index);
    SVAL_DECL(BOOL,   heap_analyze_success);
#else
    PER_HEAP
    uint8_t** internal_root_array;

    PER_HEAP
    size_t internal_root_array_index;

    PER_HEAP
    BOOL   heap_analyze_success;
#endif // !MULTIPLE_HEAPS

    // next two fields are used to optimize the search for the object 
    // enclosing the current reference handled by ha_mark_object_simple.
    PER_HEAP
    uint8_t*  current_obj;

    PER_HEAP
    size_t current_obj_size;

#endif //HEAP_ANALYZE

    /* ----------------------- global members ----------------------- */
public:

    PER_HEAP
    int         condemned_generation_num;

    PER_HEAP
    BOOL        blocking_collection;

#ifdef MULTIPLE_HEAPS
    SVAL_DECL(int, n_heaps);
    SPTR_DECL(PTR_gc_heap, g_heaps);

    static
    size_t*   g_promoted;
#ifdef BACKGROUND_GC
    static
    size_t*   g_bpromoted;
#endif //BACKGROUND_GC
#ifdef MH_SC_MARK
    PER_HEAP_ISOLATED
    int*  g_mark_stack_busy;
#endif //MH_SC_MARK
#else
    static
    size_t    g_promoted;
#ifdef BACKGROUND_GC
    static
    size_t    g_bpromoted;
#endif //BACKGROUND_GC
#endif //MULTIPLE_HEAPS
    
    static
    size_t reserved_memory;
    static
    size_t reserved_memory_limit;
    static
    BOOL      g_low_memory_status;

protected:
    PER_HEAP
    void update_collection_counts ();

}; // class gc_heap


#ifdef FEATURE_PREMORTEM_FINALIZATION
class CFinalize
{
#ifdef DACCESS_COMPILE
    friend class ::ClrDataAccess;
#endif // DACCESS_COMPILE
private:

    //adjust the count and add a constant to add a segment
    static const int ExtraSegCount = 2;
    static const int FinalizerListSeg = NUMBERGENERATIONS+1;
    static const int CriticalFinalizerListSeg = NUMBERGENERATIONS;
    //Does not correspond to a segment
    static const int FreeList = NUMBERGENERATIONS+ExtraSegCount;

    PTR_PTR_Object m_Array;
    PTR_PTR_Object m_FillPointers[NUMBERGENERATIONS+ExtraSegCount];
    PTR_PTR_Object m_EndArray;
    size_t   m_PromotedCount;
    
    VOLATILE(int32_t) lock;
#ifdef _DEBUG
    EEThreadId lockowner_threadid;
#endif // _DEBUG

    BOOL GrowArray();
    void MoveItem (Object** fromIndex,
                   unsigned int fromSeg,
                   unsigned int toSeg);

    inline PTR_PTR_Object& SegQueue (unsigned int Seg)
    {
        return (Seg ? m_FillPointers [Seg-1] : m_Array);
    }
    inline PTR_PTR_Object& SegQueueLimit (unsigned int Seg)
    {
        return m_FillPointers [Seg];
    }

    BOOL IsSegEmpty ( unsigned int i)
    {
        ASSERT ( (int)i < FreeList);
        return (SegQueueLimit(i) == SegQueue (i));

    }

    BOOL FinalizeSegForAppDomain (AppDomain *pDomain, 
                                  BOOL fRunFinalizers, 
                                  unsigned int Seg);

public:
    ~CFinalize();
    bool Initialize();
    void EnterFinalizeLock();
    void LeaveFinalizeLock();
    bool RegisterForFinalization (int gen, Object* obj, size_t size=0);
    Object* GetNextFinalizableObject (BOOL only_non_critical=FALSE);
    BOOL ScanForFinalization (promote_func* fn, int gen,BOOL mark_only_p, gc_heap* hp);
    void RelocateFinalizationData (int gen, gc_heap* hp);
    void WalkFReachableObjects (fq_walk_fn fn);
    void GcScanRoots (promote_func* fn, int hn, ScanContext *pSC);
    void UpdatePromotedGenerations (int gen, BOOL gen_0_empty_p);
    size_t GetPromotedCount();

    //Methods used by the shutdown code to call every finalizer
    void SetSegForShutDown(BOOL fHasLock);
    size_t GetNumberFinalizableObjects();
    void DiscardNonCriticalObjects();

    //Methods used by the app domain unloading call to finalize objects in an app domain
    BOOL FinalizeAppDomain (AppDomain *pDomain, BOOL fRunFinalizers);

    void CheckFinalizerObjects();
};
#endif // FEATURE_PREMORTEM_FINALIZATION

inline
 size_t& dd_begin_data_size (dynamic_data* inst)
{
  return inst->begin_data_size;
}
inline
 size_t& dd_survived_size (dynamic_data* inst)
{
  return inst->survived_size;
}
#if defined (RESPECT_LARGE_ALIGNMENT) || defined (FEATURE_STRUCTALIGN)
inline
 size_t& dd_num_npinned_plugs(dynamic_data* inst)
{
  return inst->num_npinned_plugs;
}
#endif //RESPECT_LARGE_ALIGNMENT || FEATURE_STRUCTALIGN
inline
size_t& dd_pinned_survived_size (dynamic_data* inst)
{
  return inst->pinned_survived_size;
}
inline
size_t& dd_added_pinned_size (dynamic_data* inst)
{
  return inst->added_pinned_size;
}
inline
size_t& dd_artificial_pinned_survived_size (dynamic_data* inst)
{
  return inst->artificial_pinned_survived_size;
}
#ifdef SHORT_PLUGS
inline
size_t& dd_padding_size (dynamic_data* inst)
{
  return inst->padding_size;
}
#endif //SHORT_PLUGS
inline
 size_t& dd_current_size (dynamic_data* inst)
{
  return inst->current_size;
}
inline
float& dd_surv (dynamic_data* inst)
{
  return inst->surv;
}
inline
size_t& dd_freach_previous_promotion (dynamic_data* inst)
{
  return inst->freach_previous_promotion;
}
inline
size_t& dd_desired_allocation (dynamic_data* inst)
{
  return inst->desired_allocation;
}
inline
size_t& dd_collection_count (dynamic_data* inst)
{
    return inst->collection_count;
}
inline
size_t& dd_promoted_size (dynamic_data* inst)
{
    return inst->promoted_size;
}
inline
float& dd_limit (dynamic_data* inst)
{
  return inst->limit;
}
inline
float& dd_max_limit (dynamic_data* inst)
{
  return inst->max_limit;
}
inline
size_t& dd_min_gc_size (dynamic_data* inst)
{
  return inst->min_gc_size;
}
inline
size_t& dd_max_size (dynamic_data* inst)
{
  return inst->max_size;
}
inline
size_t& dd_min_size (dynamic_data* inst)
{
  return inst->min_size;
}
inline
ptrdiff_t& dd_new_allocation (dynamic_data* inst)
{
  return inst->new_allocation;
}
inline
ptrdiff_t& dd_gc_new_allocation (dynamic_data* inst)
{
  return inst->gc_new_allocation;
}
inline
size_t& dd_default_new_allocation (dynamic_data* inst)
{
  return inst->default_new_allocation;
}
inline
size_t& dd_fragmentation_limit (dynamic_data* inst)
{
  return inst->fragmentation_limit;
}
inline
float& dd_fragmentation_burden_limit (dynamic_data* inst)
{
  return inst->fragmentation_burden_limit;
}
inline
float dd_v_fragmentation_burden_limit (dynamic_data* inst)
{
  return (min (2*dd_fragmentation_burden_limit (inst), 0.75f));
}
inline
size_t& dd_fragmentation (dynamic_data* inst)
{
  return inst->fragmentation;
}

inline
size_t& dd_gc_clock (dynamic_data* inst)
{
  return inst->gc_clock;
}
inline
size_t& dd_time_clock (dynamic_data* inst)
{
  return inst->time_clock;
}

inline
size_t& dd_gc_elapsed_time (dynamic_data* inst)
{
    return inst->gc_elapsed_time;
}

inline
float& dd_gc_speed (dynamic_data* inst)
{
    return inst->gc_speed;
}

inline
alloc_context* generation_alloc_context (generation* inst)
{
    return &(inst->allocation_context);
}

inline
uint8_t*& generation_allocation_start (generation* inst)
{
  return inst->allocation_start;
}
inline
uint8_t*& generation_allocation_pointer (generation* inst)
{
  return inst->allocation_context.alloc_ptr;
}
inline
uint8_t*& generation_allocation_limit (generation* inst)
{
  return inst->allocation_context.alloc_limit;
}
inline 
allocator* generation_allocator (generation* inst)
{
    return &inst->free_list_allocator;
}

inline
PTR_heap_segment& generation_start_segment (generation* inst)
{
  return inst->start_segment;
}
inline
heap_segment*& generation_allocation_segment (generation* inst)
{
  return inst->allocation_segment;
}
inline
uint8_t*& generation_plan_allocation_start (generation* inst)
{
  return inst->plan_allocation_start;
}
inline
size_t& generation_plan_allocation_start_size (generation* inst)
{
  return inst->plan_allocation_start_size;
}
inline
uint8_t*& generation_allocation_context_start_region (generation* inst)
{
  return inst->allocation_context_start_region;
}
inline
size_t& generation_free_list_space (generation* inst)
{
  return inst->free_list_space;
}
inline
size_t& generation_free_obj_space (generation* inst)
{
  return inst->free_obj_space;
}
inline
size_t& generation_allocation_size (generation* inst)
{
  return inst->allocation_size;
}

inline
size_t& generation_pinned_allocated (generation* inst)
{
    return inst->pinned_allocated;
}
inline
size_t& generation_pinned_allocation_sweep_size (generation* inst)
{
    return inst->pinned_allocation_sweep_size;
}
inline
size_t& generation_pinned_allocation_compact_size (generation* inst)
{
    return inst->pinned_allocation_compact_size;
}
inline
size_t&  generation_free_list_allocated (generation* inst)
{
    return inst->free_list_allocated;
}
inline
size_t&  generation_end_seg_allocated (generation* inst)
{
    return inst->end_seg_allocated;
}
inline
BOOL&  generation_allocate_end_seg_p (generation* inst)
{
    return inst->allocate_end_seg_p;
}
inline
size_t& generation_condemned_allocated (generation* inst)
{
    return inst->condemned_allocated;
}
#ifdef FREE_USAGE_STATS
inline
size_t& generation_pinned_free_obj_space (generation* inst)
{
    return inst->pinned_free_obj_space;
}
inline
size_t& generation_allocated_in_pinned_free (generation* inst)
{
    return inst->allocated_in_pinned_free;
}
inline
size_t& generation_allocated_since_last_pin (generation* inst)
{
    return inst->allocated_since_last_pin;
}
#endif //FREE_USAGE_STATS
inline 
float generation_allocator_efficiency (generation* inst)
{
    if ((generation_free_list_allocated (inst) + generation_free_obj_space (inst)) != 0)
    {
        return ((float) (generation_free_list_allocated (inst)) / (float)(generation_free_list_allocated (inst) + generation_free_obj_space (inst)));
    }
    else
        return 0;
}
inline
size_t generation_unusable_fragmentation (generation* inst)
{
    return (size_t)(generation_free_obj_space (inst) + 
                    (1.0f-generation_allocator_efficiency(inst))*generation_free_list_space (inst));
}

#define plug_skew           sizeof(ObjHeader)
// We always use USE_PADDING_TAIL when fitting so items on the free list should be
// twice the min_obj_size.
#define min_free_list       (2*min_obj_size)
struct plug
{
    uint8_t *  skew[plug_skew / sizeof(uint8_t *)];
};

class pair
{
public:
    short left;
    short right;
};

//Note that these encode the fact that plug_skew is a multiple of uint8_t*.
// Each of new field is prepended to the prior struct.

struct plug_and_pair
{
    pair        m_pair;
    plug        m_plug;
};

struct plug_and_reloc
{
    ptrdiff_t   reloc;
    pair        m_pair;
    plug        m_plug;
};

struct plug_and_gap
{
    ptrdiff_t   gap;
    ptrdiff_t   reloc;
    union
    {
        pair    m_pair;
        int     lr;  //for clearing the entire pair in one instruction
    };
    plug        m_plug;
};

struct gap_reloc_pair
{
    size_t gap;
    size_t   reloc;
    pair        m_pair;
};

#define min_pre_pin_obj_size (sizeof (gap_reloc_pair) + min_obj_size)

struct DECLSPEC_ALIGN(8) aligned_plug_and_gap
{
    plug_and_gap plugandgap;
};

struct loh_obj_and_pad
{
    ptrdiff_t   reloc;    
    plug        m_plug;
};

struct loh_padding_obj
{
    uint8_t*    mt;
    size_t      len;
    ptrdiff_t   reloc;
    plug        m_plug;
};
#define loh_padding_obj_size (sizeof(loh_padding_obj))

//flags description
#define heap_segment_flags_readonly     1
#define heap_segment_flags_inrange      2
#define heap_segment_flags_unmappable   4
#define heap_segment_flags_loh          8
#ifdef BACKGROUND_GC
#define heap_segment_flags_swept        16
#define heap_segment_flags_decommitted  32
#define heap_segment_flags_ma_committed 64
// for segments whose mark array is only partially committed.
#define heap_segment_flags_ma_pcommitted 128
#endif //BACKGROUND_GC

//need to be careful to keep enough pad items to fit a relocation node
//padded to QuadWord before the plug_skew

class heap_segment
{
public:
    uint8_t*        allocated;
    uint8_t*        committed;
    uint8_t*        reserved;
    uint8_t*        used;
    uint8_t*        mem;
    size_t          flags;
    PTR_heap_segment next;
    uint8_t*        plan_allocated;
#ifdef BACKGROUND_GC
    uint8_t*        background_allocated;
    uint8_t*        saved_bg_allocated;
#endif //BACKGROUND_GC

#ifdef MULTIPLE_HEAPS
    gc_heap*        heap;
#endif //MULTIPLE_HEAPS

#ifdef _MSC_VER
// Disable this warning - we intentionally want __declspec(align()) to insert padding for us
#pragma warning(disable:4324)  // structure was padded due to __declspec(align())
#endif
    aligned_plug_and_gap padandplug;
#ifdef _MSC_VER
#pragma warning(default:4324)  // structure was padded due to __declspec(align())
#endif
};

inline
uint8_t*& heap_segment_reserved (heap_segment* inst)
{
  return inst->reserved;
}
inline
uint8_t*& heap_segment_committed (heap_segment* inst)
{
  return inst->committed;
}
inline
uint8_t*& heap_segment_used (heap_segment* inst)
{
  return inst->used;
}
inline
uint8_t*& heap_segment_allocated (heap_segment* inst)
{
  return inst->allocated;
}

inline
BOOL heap_segment_read_only_p (heap_segment* inst)
{
    return ((inst->flags & heap_segment_flags_readonly) != 0);
}

inline
BOOL heap_segment_in_range_p (heap_segment* inst)
{
    return (!(inst->flags & heap_segment_flags_readonly) ||
            ((inst->flags & heap_segment_flags_inrange) != 0));
}

inline
BOOL heap_segment_unmappable_p (heap_segment* inst)
{
    return (!(inst->flags & heap_segment_flags_readonly) ||
            ((inst->flags & heap_segment_flags_unmappable) != 0));
}

inline
BOOL heap_segment_loh_p (heap_segment * inst)
{
    return !!(inst->flags & heap_segment_flags_loh);
}

#ifdef BACKGROUND_GC
inline
BOOL heap_segment_decommitted_p (heap_segment * inst)
{
    return !!(inst->flags & heap_segment_flags_decommitted);
}
#endif //BACKGROUND_GC

inline
PTR_heap_segment & heap_segment_next (heap_segment* inst)
{
  return inst->next;
}
inline
uint8_t*& heap_segment_mem (heap_segment* inst)
{
  return inst->mem;
}
inline
uint8_t*& heap_segment_plan_allocated (heap_segment* inst)
{
  return inst->plan_allocated;
}

#ifdef BACKGROUND_GC
inline
uint8_t*& heap_segment_background_allocated (heap_segment* inst)
{
  return inst->background_allocated;
}
inline
uint8_t*& heap_segment_saved_bg_allocated (heap_segment* inst)
{
  return inst->saved_bg_allocated;
}
#endif //BACKGROUND_GC

#ifdef MULTIPLE_HEAPS
inline
gc_heap*& heap_segment_heap (heap_segment* inst)
{
    return inst->heap;
}
#endif //MULTIPLE_HEAPS

#ifndef MULTIPLE_HEAPS

#ifndef DACCESS_COMPILE
extern "C" {
#endif //!DACCESS_COMPILE

GARY_DECL(generation,generation_table,NUMBERGENERATIONS+1);

#ifdef GC_CONFIG_DRIVEN
GARY_DECL(size_t, interesting_data_per_heap, max_idp_count);
GARY_DECL(size_t, compact_reasons_per_heap, max_compact_reasons_count);
GARY_DECL(size_t, expand_mechanisms_per_heap, max_expand_mechanisms_count);
GARY_DECL(size_t, interesting_mechanism_bits_per_heap, max_gc_mechanism_bits_count);
#endif //GC_CONFIG_DRIVEN

#ifndef DACCESS_COMPILE
}
#endif //!DACCESS_COMPILE

#endif //MULTIPLE_HEAPS

inline
generation* gc_heap::generation_of (int  n)
{
    assert (((n <= max_generation+1) && (n >= 0)));
    return &generation_table [ n ];
}

inline
dynamic_data* gc_heap::dynamic_data_of (int gen_number)
{
    return &dynamic_data_table [ gen_number ];
}

#define card_word_width ((size_t)32)

//
// The value of card_size is determined empirically according to the average size of an object
// In the code we also rely on the assumption that one card_table entry (uint32_t) covers an entire os page
//
#if defined (BIT64)
#define card_size ((size_t)(2*OS_PAGE_SIZE/card_word_width))
#else
#define card_size ((size_t)(OS_PAGE_SIZE/card_word_width))
#endif // BIT64

inline
size_t card_word (size_t card)
{
    return card / card_word_width;
}

inline
unsigned card_bit (size_t card)
{
    return (unsigned)(card % card_word_width);
}

inline
size_t gcard_of (uint8_t* object)
{
    return (size_t)(object) / card_size;
}