/*
* Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
* Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
* Copyright (c) 1998-1999 by Silicon Graphics. All rights reserved.
* Copyright (c) 1999 by Hewlett-Packard Company. All rights reserved.
*
* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
*
* Permission is hereby granted to use or copy this program
* for any purpose, provided the above notices are retained on all copies.
* Permission to modify the code and to distribute modified code is granted,
* provided the above notices are retained, and a notice that the code was
* modified is included with the above copyright notice.
*/
#include "private/gc_priv.h"
#include <stdio.h>
#ifdef GC_USE_ENTIRE_HEAP
int GC_use_entire_heap = TRUE;
#else
int GC_use_entire_heap = FALSE;
#endif
/*
* Free heap blocks are kept on one of several free lists,
* depending on the size of the block. Each free list is doubly linked.
* Adjacent free blocks are coalesced.
*/
# define MAX_BLACK_LIST_ALLOC (2*HBLKSIZE)
/* largest block we will allocate starting on a black */
/* listed block. Must be >= HBLKSIZE. */
# define UNIQUE_THRESHOLD 32
/* Sizes up to this many HBLKs each have their own free list */
# define HUGE_THRESHOLD 256
/* Sizes of at least this many heap blocks are mapped to a */
/* single free list. */
# define FL_COMPRESSION 8
/* In between sizes map this many distinct sizes to a single */
/* bin. */
#ifndef GC_GCJ_SUPPORT
STATIC
#endif
struct hblk * GC_hblkfreelist[N_HBLK_FLS+1] = { 0 };
/* List of completely empty heap blocks */
/* Linked through hb_next field of */
/* header structure associated with */
/* block. Remains externally visible */
/* as used by GNU GCJ currently. */
#ifndef GC_GCJ_SUPPORT
STATIC
#endif
word GC_free_bytes[N_HBLK_FLS+1] = { 0 };
/* Number of free bytes on each list. Remains visible to GCJ. */
/* Return the largest n such that the number of free bytes on lists */
/* n .. N_HBLK_FLS is greater or equal to GC_max_large_allocd_bytes */
/* minus GC_large_allocd_bytes. If there is no such n, return 0. */
GC_INLINE int GC_enough_large_bytes_left(void)
{
int n;
word bytes = GC_large_allocd_bytes;
GC_ASSERT(GC_max_large_allocd_bytes <= GC_heapsize);
for (n = N_HBLK_FLS; n >= 0; --n) {
bytes += GC_free_bytes[n];
if (bytes >= GC_max_large_allocd_bytes) return n;
}
return 0;
}
/* Map a number of blocks to the appropriate large block free list index. */
STATIC int GC_hblk_fl_from_blocks(word blocks_needed)
{
if (blocks_needed <= UNIQUE_THRESHOLD) return (int)blocks_needed;
if (blocks_needed >= HUGE_THRESHOLD) return N_HBLK_FLS;
return (int)(blocks_needed - UNIQUE_THRESHOLD)/FL_COMPRESSION
+ UNIQUE_THRESHOLD;
#if !defined(NO_DEBUGGING) || defined(GC_ASSERTIONS)
/* Should return the same value as GC_large_free_bytes. */
GC_INNER word GC_compute_large_free_bytes(void)
{
word total_free = 0;
unsigned i;
for (i = 0; i <= N_HBLK_FLS; ++i) {
struct hblk * h;
hdr * hhdr;
for (h = GC_hblkfreelist[i]; h != 0; h = hhdr->hb_next) {
hhdr = HDR(h);
total_free += hhdr->hb_sz;
}
}
return total_free;
}
#endif /* !NO_DEBUGGING || GC_ASSERTIONS */
# if !defined(NO_DEBUGGING)
void GC_print_hblkfreelist(void)
{
unsigned i;
word total;
for (i = 0; i <= N_HBLK_FLS; ++i) {
struct hblk * h = GC_hblkfreelist[i];
if (0 != h) GC_printf("Free list %u (total size %lu):\n",
i, (unsigned long)GC_free_bytes[i]);
while (h /* != NULL */) { /* CPPCHECK */
hdr * hhdr = HDR(h);
if ((total = GC_compute_large_free_bytes()) != GC_large_free_bytes)
GC_err_printf("GC_large_free_bytes INCONSISTENT!! Should be: %lu\n",
(unsigned long)total);
}
/* Return the free list index on which the block described by the header */
/* appears, or -1 if it appears nowhere. */
static int free_list_index_of(hdr *wanted)
{
int i;
for (i = 0; i <= N_HBLK_FLS; ++i) {
struct hblk * h;
hdr * hhdr;
for (h = GC_hblkfreelist[i]; h != 0; h = hhdr -> hb_next) {
hhdr = HDR(h);
if (hhdr == wanted) return i;
}
}
return -1;
}
for (i = 0; i < GC_n_heap_sects; ++i) {
ptr_t start = GC_heap_sects[i].hs_start;
size_t bytes = GC_heap_sects[i].hs_bytes;
ptr_t end = start + bytes;
ptr_t p;
/* Merge in contiguous sections. */
while (i+1 < GC_n_heap_sects && GC_heap_sects[i+1].hs_start == end) {
++i;
end = GC_heap_sects[i].hs_start + GC_heap_sects[i].hs_bytes;
}
GC_printf("***Section from %p to %p\n", (void *)start, (void *)end);
for (p = start; (word)p < (word)end; ) {
hdr *hhdr = HDR(p);
if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
GC_printf("\t%p Missing header!!(%p)\n",
(void *)p, (void *)hhdr);
p += HBLKSIZE;
continue;
}
if (HBLK_IS_FREE(hhdr)) {
int correct_index = GC_hblk_fl_from_blocks(
divHBLKSZ(hhdr -> hb_sz));
int actual_index;
GC_printf("\t%p\tfree block of size 0x%lx bytes%s\n",
(void *)p, (unsigned long)(hhdr -> hb_sz),
IS_MAPPED(hhdr) ? "" : " (unmapped)");
actual_index = free_list_index_of(hhdr);
if (-1 == actual_index) {
GC_printf("\t\tBlock not on free list %d!!\n",
correct_index);
} else if (correct_index != actual_index) {
GC_printf("\t\tBlock on list %d, should be on %d!!\n",
actual_index, correct_index);
}
p += hhdr -> hb_sz;
} else {
GC_printf("\t%p\tused for blocks of size 0x%lx bytes\n",
(void *)p, (unsigned long)(hhdr -> hb_sz));
p += HBLKSIZE * OBJ_SZ_TO_BLOCKS(hhdr -> hb_sz);
}
}
}
}
# endif /* NO_DEBUGGING */
/* Initialize hdr for a block containing the indicated size and */
/* kind of objects. */
/* Return FALSE on failure. */
static GC_bool setup_header(hdr * hhdr, struct hblk *block, size_t byte_sz,
int kind, unsigned flags)
{
word descr;
# ifdef MARK_BIT_PER_GRANULE
if (byte_sz > MAXOBJBYTES)
flags |= LARGE_BLOCK;
# endif
# ifdef ENABLE_DISCLAIM
if (GC_obj_kinds[kind].ok_disclaim_proc)
flags |= HAS_DISCLAIM;
if (GC_obj_kinds[kind].ok_mark_unconditionally)
flags |= MARK_UNCONDITIONALLY;
# endif
# ifdef MARK_BIT_PER_OBJ
/* Set hb_inv_sz as portably as possible. */
/* We set it to the smallest value such that sz * inv_sz >= 2**32 */
/* This may be more precision than necessary. */
if (byte_sz > MAXOBJBYTES) {
hhdr -> hb_inv_sz = LARGE_INV_SZ;
} else {
word inv_sz;
/* Remove hhdr from the free list (it is assumed to specified by index). */
STATIC void GC_remove_from_fl_at(hdr *hhdr, int index)
{
GC_ASSERT(((hhdr -> hb_sz) & (HBLKSIZE-1)) == 0);
if (hhdr -> hb_prev == 0) {
GC_ASSERT(HDR(GC_hblkfreelist[index]) == hhdr);
GC_hblkfreelist[index] = hhdr -> hb_next;
} else {
hdr *phdr;
GET_HDR(hhdr -> hb_prev, phdr);
phdr -> hb_next = hhdr -> hb_next;
}
/* We always need index to maintain free counts. */
GC_ASSERT(GC_free_bytes[index] >= hhdr -> hb_sz);
GC_free_bytes[index] -= hhdr -> hb_sz;
if (0 != hhdr -> hb_next) {
hdr * nhdr;
GC_ASSERT(!IS_FORWARDING_ADDR_OR_NIL(NHDR(hhdr)));
GET_HDR(hhdr -> hb_next, nhdr);
nhdr -> hb_prev = hhdr -> hb_prev;
}
}
/* Remove hhdr from the appropriate free list (we assume it is on the */
/* size-appropriate free list). */
GC_INLINE void GC_remove_from_fl(hdr *hhdr)
{
GC_remove_from_fl_at(hhdr, GC_hblk_fl_from_blocks(divHBLKSZ(hhdr->hb_sz)));
}
/* Return a pointer to the block ending just before h, if any. */
static struct hblk * get_block_ending_at(struct hblk *h)
{
struct hblk * p = h - 1;
hdr * phdr;
GET_HDR(p, phdr);
while (0 != phdr && IS_FORWARDING_ADDR_OR_NIL(phdr)) {
p = FORWARDED_ADDR(p,phdr);
phdr = HDR(p);
}
if (0 != phdr) {
return p;
}
p = GC_prev_block(h - 1);
if (p) {
phdr = HDR(p);
if ((ptr_t)p + phdr -> hb_sz == (ptr_t)h) {
return p;
}
}
return NULL;
}
/* Return a pointer to the free block ending just before h, if any. */
STATIC struct hblk * GC_free_block_ending_at(struct hblk *h)
{
struct hblk * p = get_block_ending_at(h);
GC_INNER int GC_unmap_threshold = MUNMAP_THRESHOLD;
#ifdef COUNT_UNMAPPED_REGIONS
/* GC_unmap_old will avoid creating more than this many unmapped regions, */
/* but an unmapped region may be split again so exceeding the limit. */
/* Return the change in number of unmapped regions if the block h swaps */
/* from its current state of mapped/unmapped to the opposite state. */
static int calc_num_unmapped_regions_delta(struct hblk *h, hdr *hhdr)
{
struct hblk * prev = get_block_ending_at(h);
struct hblk * next;
GC_bool prev_unmapped = FALSE;
GC_bool next_unmapped = FALSE;
next = GC_next_block((struct hblk *)((ptr_t)h + hhdr->hb_sz), TRUE);
/* Ensure next is contiguous with h. */
if ((ptr_t)next != GC_unmap_end((ptr_t)h, (size_t)hhdr->hb_sz)) {
next = NULL;
}
if (prev != NULL) {
hdr * prevhdr = HDR(prev);
prev_unmapped = !IS_MAPPED(prevhdr);
}
if (next != NULL) {
hdr * nexthdr = HDR(next);
next_unmapped = !IS_MAPPED(nexthdr);
}
if (prev_unmapped && next_unmapped) {
/* If h unmapped, merge two unmapped regions into one. */
/* If h remapped, split one unmapped region into two. */
return IS_MAPPED(hhdr) ? -1 : 1;
}
if (!prev_unmapped && !next_unmapped) {
/* If h unmapped, create an isolated unmapped region. */
/* If h remapped, remove it. */
return IS_MAPPED(hhdr) ? 1 : -1;
}
/* If h unmapped, merge it with previous or next unmapped region. */
/* If h remapped, reduce either previous or next unmapped region. */
/* In either way, no change to the number of unmapped regions. */
return 0;
}
#endif /* COUNT_UNMAPPED_REGIONS */
/* Update GC_num_unmapped_regions assuming the block h changes */
/* from its current state of mapped/unmapped to the opposite state. */
GC_INLINE void GC_adjust_num_unmapped(struct hblk *h GC_ATTR_UNUSED,
hdr *hhdr GC_ATTR_UNUSED)
{
# ifdef COUNT_UNMAPPED_REGIONS
GC_num_unmapped_regions += calc_num_unmapped_regions_delta(h, hhdr);
# endif
}
/* Unmap blocks that haven't been recently touched. This is the only */
/* way blocks are ever unmapped. */
GC_INNER void GC_unmap_old(void)
{
int i;
if (GC_unmap_threshold == 0)
return; /* unmapping disabled */
# ifdef COUNT_UNMAPPED_REGIONS
/* Skip unmapping if we have already exceeded the soft limit. */
/* This forgoes any opportunities to merge unmapped regions though. */
if (GC_num_unmapped_regions >= GC_UNMAPPED_REGIONS_SOFT_LIMIT)
return;
# endif
for (i = 0; i <= N_HBLK_FLS; ++i) {
struct hblk * h;
hdr * hhdr;
for (h = GC_hblkfreelist[i]; 0 != h; h = hhdr -> hb_next) {
hhdr = HDR(h);
if (!IS_MAPPED(hhdr)) continue;
/* Check that the interval is larger than the threshold (the */
/* truncated counter value wrapping is handled correctly). */
if ((unsigned short)(GC_gc_no - hhdr->hb_last_reclaimed) >
(unsigned short)GC_unmap_threshold) {
# ifdef COUNT_UNMAPPED_REGIONS
/* Continue with unmapping the block only if it will not */
/* create too many unmapped regions, or if unmapping */
/* reduces the number of regions. */
int delta = calc_num_unmapped_regions_delta(h, hhdr);
signed_word regions = GC_num_unmapped_regions + delta;
/* Merge all unmapped blocks that are adjacent to other free */
/* blocks. This may involve remapping, since all blocks are either */
/* fully mapped or fully unmapped. */
GC_INNER void GC_merge_unmapped(void)
{
int i;
for (i = 0; i <= N_HBLK_FLS; ++i) {
struct hblk *h = GC_hblkfreelist[i];
while (h != 0) {
struct hblk *next;
hdr *hhdr, *nexthdr;
word size, nextsize;
GET_HDR(h, hhdr);
size = hhdr->hb_sz;
next = (struct hblk *)((word)h + size);
GET_HDR(next, nexthdr);
/* Coalesce with successor, if possible */
if (0 != nexthdr && HBLK_IS_FREE(nexthdr)
&& (signed_word) (size + (nextsize = nexthdr->hb_sz)) > 0
/* no pot. overflow */) {
/* Note that we usually try to avoid adjacent free blocks */
/* that are either both mapped or both unmapped. But that */
/* isn't guaranteed to hold since we remap blocks when we */
/* split them, and don't merge at that point. It may also */
/* not hold if the merged block would be too big. */
if (IS_MAPPED(hhdr) && !IS_MAPPED(nexthdr)) {
/* make both consistent, so that we can merge */
if (size > nextsize) {
GC_adjust_num_unmapped(next, nexthdr);
GC_remap((ptr_t)next, nextsize);
} else {
GC_adjust_num_unmapped(h, hhdr);
GC_unmap((ptr_t)h, size);
GC_unmap_gap((ptr_t)h, size, (ptr_t)next, nextsize);
hhdr -> hb_flags |= WAS_UNMAPPED;
}
} else if (IS_MAPPED(nexthdr) && !IS_MAPPED(hhdr)) {
if (size > nextsize) {
GC_adjust_num_unmapped(next, nexthdr);
GC_unmap((ptr_t)next, nextsize);
GC_unmap_gap((ptr_t)h, size, (ptr_t)next, nextsize);
} else {
GC_adjust_num_unmapped(h, hhdr);
GC_remap((ptr_t)h, size);
hhdr -> hb_flags &= ~WAS_UNMAPPED;
hhdr -> hb_last_reclaimed = nexthdr -> hb_last_reclaimed;
}
} else if (!IS_MAPPED(hhdr) && !IS_MAPPED(nexthdr)) {
/* Unmap any gap in the middle */
GC_unmap_gap((ptr_t)h, size, (ptr_t)next, nextsize);
}
/* If they are both unmapped, we merge, but leave unmapped. */
GC_remove_from_fl_at(hhdr, i);
GC_remove_from_fl(nexthdr);
hhdr -> hb_sz += nexthdr -> hb_sz;
GC_remove_header(next);
GC_add_to_fl(h, hhdr);
/* Start over at beginning of list */
h = GC_hblkfreelist[i];
} else /* not mergeable with successor */ {
h = hhdr -> hb_next;
}
} /* while (h != 0) ... */
} /* for ... */
}
#endif /* USE_MUNMAP */
/*
* Return a pointer to a block starting at h of length bytes.
* Memory for the block is mapped.
* Remove the block from its free list, and return the remainder (if any)
* to its appropriate free list.
* May fail by returning 0.
* The header for the returned block must be set up by the caller.
* If the return value is not 0, then hhdr is the header for it.
*/
STATIC struct hblk * GC_get_first_part(struct hblk *h, hdr *hhdr,
size_t bytes, int index)
{
word total_size = hhdr -> hb_sz;
struct hblk * rest;
hdr * rest_hdr;
GC_ASSERT((total_size & (HBLKSIZE-1)) == 0);
GC_remove_from_fl_at(hhdr, index);
if (total_size == bytes) return h;
rest = (struct hblk *)((word)h + bytes);
rest_hdr = GC_install_header(rest);
if (0 == rest_hdr) {
/* FIXME: This is likely to be very bad news ... */
WARN("Header allocation failed: dropping block\n", 0);
return(0);
}
rest_hdr -> hb_sz = total_size - bytes;
rest_hdr -> hb_flags = 0;
# ifdef GC_ASSERTIONS
/* Mark h not free, to avoid assertion about adjacent free blocks. */
hhdr -> hb_flags &= ~FREE_BLK;
# endif
GC_add_to_fl(rest, rest_hdr);
return h;
}
/*
* H is a free block. N points at an address inside it.
* A new header for n has already been set up. Fix up h's header
* to reflect the fact that it is being split, move it to the
* appropriate free list.
* N replaces h in the original free list.
*
* Nhdr is not completely filled in, since it is about to be allocated.
* It may in fact end up on the wrong free list for its size.
* That's not a disaster, since n is about to be allocated
* by our caller.
* (Hence adding it to a free list is silly. But this path is hopefully
* rare enough that it doesn't matter. The code is cleaner this way.)
*/
STATIC void GC_split_block(struct hblk *h, hdr *hhdr, struct hblk *n,
hdr *nhdr, int index /* Index of free list */)
{
word total_size = hhdr -> hb_sz;
word h_size = (word)n - (word)h;
struct hblk *prev = hhdr -> hb_prev;
struct hblk *next = hhdr -> hb_next;
STATIC struct hblk *
GC_allochblk_nth(size_t sz /* bytes */, int kind, unsigned flags, int n,
int may_split);
#define AVOID_SPLIT_REMAPPED 2
/*
* Allocate (and return pointer to) a heap block
* for objects of size sz bytes, searching the nth free list.
*
* NOTE: We set obj_map field in header correctly.
* Caller is responsible for building an object freelist in block.
*
* The client is responsible for clearing the block, if necessary.
*/
GC_INNER struct hblk *
GC_allochblk(size_t sz, int kind, unsigned flags/* IGNORE_OFF_PAGE or 0 */)
{
word blocks;
int start_list;
struct hblk *result;
int may_split;
int split_limit; /* Highest index of free list whose blocks we */
/* split. */
GC_ASSERT(I_HOLD_LOCK());
GC_ASSERT((sz & (GRANULE_BYTES - 1)) == 0);
blocks = OBJ_SZ_TO_BLOCKS_CHECKED(sz);
if ((signed_word)(blocks * HBLKSIZE) < 0) {
return 0;
}
start_list = GC_hblk_fl_from_blocks(blocks);
/* Try for an exact match first. */
result = GC_allochblk_nth(sz, kind, flags, start_list, FALSE);
if (0 != result) return result;
may_split = TRUE;
if (GC_use_entire_heap || GC_dont_gc
|| USED_HEAP_SIZE < GC_requested_heapsize
|| GC_incremental || !GC_should_collect()) {
/* Should use more of the heap, even if it requires splitting. */
split_limit = N_HBLK_FLS;
} else if (GC_finalizer_bytes_freed > (GC_heapsize >> 4)) {
/* If we are deallocating lots of memory from */
/* finalizers, fail and collect sooner rather */
/* than later. */
split_limit = 0;
} else {
/* If we have enough large blocks left to cover any */
/* previous request for large blocks, we go ahead */
/* and split. Assuming a steady state, that should */
/* be safe. It means that we can use the full */
/* heap if we allocate only small objects. */
split_limit = GC_enough_large_bytes_left();
# ifdef USE_MUNMAP
if (split_limit > 0)
may_split = AVOID_SPLIT_REMAPPED;
# endif
}
if (start_list < UNIQUE_THRESHOLD) {
/* No reason to try start_list again, since all blocks are exact */
/* matches. */
++start_list;
}
for (; start_list <= split_limit; ++start_list) {
result = GC_allochblk_nth(sz, kind, flags, start_list, may_split);
if (0 != result)
break;
}
return result;
}
STATIC long GC_large_alloc_warn_suppressed = 0;
/* Number of warnings suppressed so far. */
/* The same, but with search restricted to nth free list. Flags is */
/* IGNORE_OFF_PAGE or zero. sz is in bytes. The may_split flag */
/* indicates whether it is OK to split larger blocks (if set to */
/* AVOID_SPLIT_REMAPPED then memory remapping followed by splitting */
/* should be generally avoided). */
STATIC struct hblk *
GC_allochblk_nth(size_t sz, int kind, unsigned flags, int n, int may_split)
{
struct hblk *hbp;
hdr * hhdr; /* Header corr. to hbp */
struct hblk *thishbp;
hdr * thishdr; /* Header corr. to thishbp */
signed_word size_needed = HBLKSIZE * OBJ_SZ_TO_BLOCKS_CHECKED(sz);
/* number of bytes in requested objects */
/* search for a big enough block in free list */
for (hbp = GC_hblkfreelist[n];; hbp = hhdr -> hb_next) {
signed_word size_avail; /* bytes available in this block */
if (hbp /* != NULL */) {
/* CPPCHECK */
} else {
return NULL;
}
GET_HDR(hbp, hhdr); /* set hhdr value */
size_avail = (signed_word)hhdr->hb_sz;
if (size_avail < size_needed) continue;
if (size_avail != size_needed) {
if (!may_split) continue;
/* If the next heap block is obviously better, go on. */
/* This prevents us from disassembling a single large */
/* block to get tiny blocks. */
thishbp = hhdr -> hb_next;
if (thishbp /* != NULL */) { /* CPPCHECK */
signed_word next_size;
while ((word)lasthbp <= (word)search_end
&& (thishbp = GC_is_black_listed(lasthbp,
(word)eff_size_needed)) != 0) {
lasthbp = thishbp;
}
size_avail -= (ptr_t)lasthbp - (ptr_t)hbp;
thishbp = lasthbp;
if (size_avail >= size_needed) {
if (thishbp != hbp) {
# ifdef USE_MUNMAP
/* Avoid remapping followed by splitting. */
if (may_split == AVOID_SPLIT_REMAPPED && !IS_MAPPED(hhdr))
continue;
# endif
thishdr = GC_install_header(thishbp);
if (0 != thishdr) {
/* Make sure it's mapped before we mangle it. */
# ifdef USE_MUNMAP
if (!IS_MAPPED(hhdr)) {
GC_adjust_num_unmapped(hbp, hhdr);
GC_remap((ptr_t)hbp, (size_t)hhdr->hb_sz);
hhdr -> hb_flags &= ~WAS_UNMAPPED;
}
# endif
/* Split the block at thishbp */
GC_split_block(hbp, hhdr, thishbp, thishdr, n);
/* Advance to thishbp */
hbp = thishbp;
hhdr = thishdr;
/* We must now allocate thishbp, since it may */
/* be on the wrong free list. */
}
}
} else if (size_needed > (signed_word)BL_LIMIT
&& orig_avail - size_needed
> (signed_word)BL_LIMIT) {
/* Punt, since anything else risks unreasonable heap growth. */
if (++GC_large_alloc_warn_suppressed
>= GC_large_alloc_warn_interval) {
WARN("Repeated allocation of very large block "
"(appr. size %" WARN_PRIuPTR " KiB):\n"
"\tMay lead to memory leak and poor performance\n",
(word)size_needed >> 10);
GC_large_alloc_warn_suppressed = 0;
}
size_avail = orig_avail;
} else if (size_avail == 0
&& size_needed == (signed_word)HBLKSIZE
&& IS_MAPPED(hhdr)) {
if (!GC_find_leak) {
static unsigned count = 0;
/* The block is completely blacklisted. We need */
/* to drop some such blocks, since otherwise we spend */
/* all our time traversing them if pointer-free */
/* blocks are unpopular. */
/* A dropped block will be reconsidered at next GC. */
if ((++count & 3) == 0) {
/* Allocate and drop the block in small chunks, to */
/* maximize the chance that we will recover some */
/* later. */
word total_size = hhdr -> hb_sz;
struct hblk * limit = hbp + divHBLKSZ(total_size);
struct hblk * h;
struct hblk * prev = hhdr -> hb_prev;
GC_large_free_bytes -= total_size;
GC_bytes_dropped += total_size;
GC_remove_from_fl_at(hhdr, n);
for (h = hbp; (word)h < (word)limit; h++) {
if (h != hbp) {
hhdr = GC_install_header(h);
}
if (NULL != hhdr) {
(void)setup_header(hhdr, h, HBLKSIZE, PTRFREE, 0);
/* Can't fail. */
if (GC_debugging_started) {
BZERO(h, HBLKSIZE);
}
}
}
/* Restore hbp to point at free block */
hbp = prev;
if (0 == hbp) {
return GC_allochblk_nth(sz, kind, flags, n, may_split);
}
hhdr = HDR(hbp);
}
}
}
}
if( size_avail >= size_needed ) {
# ifdef USE_MUNMAP
if (!IS_MAPPED(hhdr)) {
GC_adjust_num_unmapped(hbp, hhdr);
GC_remap((ptr_t)hbp, (size_t)hhdr->hb_sz);
hhdr -> hb_flags &= ~WAS_UNMAPPED;
/* Note: This may leave adjacent, mapped free blocks. */
}
# endif
/* hbp may be on the wrong freelist; the parameter n */
/* is important. */
hbp = GC_get_first_part(hbp, hhdr, size_needed, n);
break;
}
}
if (0 == hbp) return 0;
/* Add it to map of valid blocks */
if (!GC_install_counts(hbp, (word)size_needed)) return(0);
/* This leaks memory under very rare conditions. */
/* Set up header */
if (!setup_header(hhdr, hbp, sz, kind, flags)) {
GC_remove_counts(hbp, (word)size_needed);
return(0); /* ditto */
}
# ifndef GC_DISABLE_INCREMENTAL
/* Notify virtual dirty bit implementation that we are about to */
/* write. Ensure that pointer-free objects are not protected */
/* if it is avoidable. This also ensures that newly allocated */
/* blocks are treated as dirty. Necessary since we don't */
/* protect free blocks. */
GC_ASSERT((size_needed & (HBLKSIZE-1)) == 0);
GC_remove_protection(hbp, divHBLKSZ(size_needed),
(hhdr -> hb_descr == 0) /* pointer-free */);
# endif
/* We just successfully allocated a block. Restart count of */
/* consecutive failures. */
GC_fail_count = 0;
/*
* Free a heap block.
*
* Coalesce the block with its neighbors if possible.
*
* All mark words are assumed to be cleared.
*/
GC_INNER void GC_freehblk(struct hblk *hbp)
{
struct hblk *next, *prev;
hdr *hhdr, *prevhdr, *nexthdr;
word size;
GET_HDR(hbp, hhdr);
size = HBLKSIZE * OBJ_SZ_TO_BLOCKS(hhdr->hb_sz);
if ((size & SIGNB) != 0)
ABORT("Deallocating excessively large block. Too large an allocation?");
/* Probably possible if we try to allocate more than half the address */
/* space at once. If we don't catch it here, strange things happen */
/* later. */
GC_remove_counts(hbp, size);
hhdr->hb_sz = size;
# ifdef USE_MUNMAP
hhdr -> hb_last_reclaimed = (unsigned short)GC_gc_no;
# endif
/* Check for duplicate deallocation in the easy case */
if (HBLK_IS_FREE(hhdr)) {
ABORT_ARG1("Duplicate large block deallocation",
" of %p", (void *)hbp);
}
GC_ASSERT(IS_MAPPED(hhdr));
hhdr -> hb_flags |= FREE_BLK;
next = (struct hblk *)((ptr_t)hbp + size);
GET_HDR(next, nexthdr);
prev = GC_free_block_ending_at(hbp);
/* Coalesce with successor, if possible */
if(0 != nexthdr && HBLK_IS_FREE(nexthdr) && IS_MAPPED(nexthdr)
&& (signed_word)(hhdr -> hb_sz + nexthdr -> hb_sz) > 0
/* no overflow */) {
GC_remove_from_fl(nexthdr);
hhdr -> hb_sz += nexthdr -> hb_sz;
GC_remove_header(next);
}
/* Coalesce with predecessor, if possible. */
if (prev /* != NULL */) { /* CPPCHECK */
prevhdr = HDR(prev);
if (IS_MAPPED(prevhdr)
&& (signed_word)(hhdr -> hb_sz + prevhdr -> hb_sz) > 0) {
GC_remove_from_fl(prevhdr);
prevhdr -> hb_sz += hhdr -> hb_sz;
# ifdef USE_MUNMAP
prevhdr -> hb_last_reclaimed = (unsigned short)GC_gc_no;
# endif
GC_remove_header(hbp);
hbp = prev;
hhdr = prevhdr;
}
}
/* FIXME: It is not clear we really always want to do these merges */
/* with USE_MUNMAP, since it updates ages and hence prevents */
/* unmapping. */
