/*
* 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.
*
* 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.
*/
#define DEBUG
#undef DEBUG
#include <stdio.h>
#include "gc_priv.h"
/*
* 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. */
# define N_HBLK_FLS (HUGE_THRESHOLD - UNIQUE_THRESHOLD)/FL_COMPRESSION \
+ UNIQUE_THRESHOLD
struct hblk * GC_hblkfreelist[N_HBLK_FLS+1] = { 0 };
/* Map a number of blocks to the appropriate large block free list index. */
int GC_hblk_fl_from_blocks(blocks_needed)
word blocks_needed;
{
if (blocks_needed <= UNIQUE_THRESHOLD) return blocks_needed;
if (blocks_needed >= HUGE_THRESHOLD) return N_HBLK_FLS;
return (blocks_needed - UNIQUE_THRESHOLD)/FL_COMPRESSION
+ UNIQUE_THRESHOLD;
}
# define HBLK_IS_FREE(hdr) ((hdr) -> hb_map == GC_invalid_map)
# define PHDR(hhdr) HDR(hhdr -> hb_prev)
# define NHDR(hhdr) HDR(hhdr -> hb_next)
# ifdef USE_MUNMAP
# define IS_MAPPED(hhdr) (((hhdr) -> hb_flags & WAS_UNMAPPED) == 0)
# else /* !USE_MMAP */
# define IS_MAPPED(hhdr) 1
# endif /* USE_MUNMAP */
# if !defined(NO_DEBUGGING)
void GC_print_hblkfreelist()
{
struct hblk * h;
word total_free = 0;
hdr * hhdr;
word sz;
int i;
for (i = 0; i <= N_HBLK_FLS; ++i) {
h = GC_hblkfreelist[i];
if (0 != h) GC_printf1("Free list %ld:\n", (unsigned long)i);
while (h != 0) {
hhdr = HDR(h);
sz = hhdr -> hb_sz;
GC_printf2("\t0x%lx size %lu ", (unsigned long)h, (unsigned long)sz);
total_free += sz;
if (GC_is_black_listed(h, HBLKSIZE) != 0) {
GC_printf0("start black listed\n");
} else if (GC_is_black_listed(h, hhdr -> hb_sz) != 0) {
GC_printf0("partially black listed\n");
} else {
GC_printf0("not black listed\n");
}
h = hhdr -> hb_next;
}
}
if (total_free != GC_large_free_bytes) {
GC_printf1("GC_large_free_bytes = %lu (INCONSISTENT!!)\n",
(unsigned long) GC_large_free_bytes);
}
GC_printf1("Total of %lu bytes on free list\n", (unsigned long)total_free);
}
/* Return the free list index on which the block described by the header */
/* appears, or -1 if it appears nowhere. */
int free_list_index_of(wanted)
hdr * wanted;
{
struct hblk * h;
hdr * hhdr;
int i;
for (i = 0; i <= N_HBLK_FLS; ++i) {
h = GC_hblkfreelist[i];
while (h != 0) {
hhdr = HDR(h);
if (hhdr == wanted) return i;
h = hhdr -> hb_next;
}
}
return -1;
}
void GC_dump_regions()
{
int i;
ptr_t start, end;
ptr_t p;
size_t bytes;
hdr *hhdr;
for (i = 0; i < GC_n_heap_sects; ++i) {
start = GC_heap_sects[i].hs_start;
bytes = GC_heap_sects[i].hs_bytes;
end = start + bytes;
/* 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_printf2("***Section from 0x%lx to 0x%lx\n", start, end);
for (p = start; p < end;) {
hhdr = HDR(p);
GC_printf1("\t0x%lx ", (unsigned long)p);
if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
GC_printf1("Missing header!!\n", 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_printf1("\tfree block of size 0x%lx bytes",
(unsigned long)(hhdr -> hb_sz));
if (IS_MAPPED(hhdr)) {
GC_printf0("\n");
} else {
GC_printf0("(unmapped)\n");
}
actual_index = free_list_index_of(hhdr);
if (-1 == actual_index) {
GC_printf1("\t\tBlock not on free list %ld!!\n",
correct_index);
} else if (correct_index != actual_index) {
GC_printf2("\t\tBlock on list %ld, should be on %ld!!\n",
actual_index, correct_index);
}
p += hhdr -> hb_sz;
} else {
GC_printf1("\tused for blocks of size 0x%lx bytes\n",
(unsigned long)WORDS_TO_BYTES(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(hhdr, sz, kind, flags)
register hdr * hhdr;
word sz; /* object size in words */
int kind;
unsigned char flags;
{
register word descr;
/* Add description of valid object pointers */
if (!GC_add_map_entry(sz)) return(FALSE);
hhdr -> hb_map = GC_obj_map[sz > MAXOBJSZ? 0 : sz];
/* Set size, kind and mark proc fields */
hhdr -> hb_sz = sz;
hhdr -> hb_obj_kind = kind;
hhdr -> hb_flags = flags;
descr = GC_obj_kinds[kind].ok_descriptor;
if (GC_obj_kinds[kind].ok_relocate_descr) descr += WORDS_TO_BYTES(sz);
hhdr -> hb_descr = descr;
/* Clear mark bits */
GC_clear_hdr_marks(hhdr);
hhdr -> hb_last_reclaimed = (unsigned short)GC_gc_no;
return(TRUE);
}
#define FL_UNKNOWN -1
/*
* Remove hhdr from the appropriate free list.
* We assume it is on the nth free list, or on the size
* appropriate free list if n is FL_UNKNOWN.
*/
void GC_remove_from_fl(hhdr, n)
hdr * hhdr;
int n;
{
GC_ASSERT(((hhdr -> hb_sz) & (HBLKSIZE-1)) == 0);
if (hhdr -> hb_prev == 0) {
int index;
if (FL_UNKNOWN == n) {
index = GC_hblk_fl_from_blocks(divHBLKSZ(hhdr -> hb_sz));
} else {
index = n;
}
GC_ASSERT(HDR(GC_hblkfreelist[index]) == hhdr);
GC_hblkfreelist[index] = hhdr -> hb_next;
} else {
PHDR(hhdr) -> hb_next = hhdr -> hb_next;
}
if (0 != hhdr -> hb_next) {
GC_ASSERT(!IS_FORWARDING_ADDR_OR_NIL(NHDR(hhdr)));
NHDR(hhdr) -> hb_prev = hhdr -> hb_prev;
}
}
/*
* Return a pointer to the free block ending just before h, if any.
*/
struct hblk * GC_free_block_ending_at(h)
struct hblk *h;
{
struct hblk * p = h - 1;
hdr * phdr = HDR(p);
while (0 != phdr && IS_FORWARDING_ADDR_OR_NIL(phdr)) {
p = FORWARDED_ADDR(p,phdr);
phdr = HDR(p);
}
if (0 != phdr && HBLK_IS_FREE(phdr)) return p;
p = GC_prev_block(h - 1);
if (0 != p) {
phdr = HDR(p);
if (HBLK_IS_FREE(phdr) && (ptr_t)p + phdr -> hb_sz == (ptr_t)h) {
return p;
}
}
return 0;
}
/*
* Add hhdr to the appropriate free list.
* We maintain individual free lists sorted by address.
*/
void GC_add_to_fl(h, hhdr)
struct hblk *h;
hdr * hhdr;
{
int index = GC_hblk_fl_from_blocks(divHBLKSZ(hhdr -> hb_sz));
struct hblk *second = GC_hblkfreelist[index];
# ifdef GC_ASSERTIONS
struct hblk *next = (struct hblk *)((word)h + hhdr -> hb_sz);
hdr * nexthdr = HDR(next);
struct hblk *prev = GC_free_block_ending_at(h);
hdr * prevhdr = HDR(prev);
GC_ASSERT(nexthdr == 0 || !HBLK_IS_FREE(nexthdr) || !IS_MAPPED(nexthdr));
GC_ASSERT(prev == 0 || !HBLK_IS_FREE(prevhdr) || !IS_MAPPED(prevhdr));
# endif
GC_ASSERT(((hhdr -> hb_sz) & (HBLKSIZE-1)) == 0);
GC_hblkfreelist[index] = h;
hhdr -> hb_next = second;
hhdr -> hb_prev = 0;
if (0 != second) HDR(second) -> hb_prev = h;
GC_invalidate_map(hhdr);
}
#ifdef USE_MUNMAP
/* Unmap blocks that haven't been recently touched. This is the only way */
/* way blocks are ever unmapped. */
void GC_unmap_old(void)
{
struct hblk * h;
hdr * hhdr;
word sz;
unsigned short last_rec, threshold;
int i;
# define UNMAP_THRESHOLD 6
for (i = 0; i <= N_HBLK_FLS; ++i) {
for (h = GC_hblkfreelist[i]; 0 != h; h = hhdr -> hb_next) {
hhdr = HDR(h);
if (!IS_MAPPED(hhdr)) continue;
threshold = (unsigned short)(GC_gc_no - UNMAP_THRESHOLD);
last_rec = hhdr -> hb_last_reclaimed;
if (last_rec > GC_gc_no
|| last_rec < threshold && threshold < GC_gc_no
/* not recently wrapped */) {
sz = hhdr -> hb_sz;
GC_unmap((ptr_t)h, sz);
hhdr -> hb_flags |= WAS_UNMAPPED;
}
}
}
}
/* 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. */
void GC_merge_unmapped(void)
{
struct hblk * h, *next;
hdr * hhdr, *nexthdr;
word size, nextsize;
int i;
for (i = 0; i <= N_HBLK_FLS; ++i) {
h = GC_hblkfreelist[i];
while (h != 0) {
hhdr = HDR(h);
size = hhdr->hb_sz;
next = (struct hblk *)((word)h + size);
nexthdr = HDR(next);
/* Coalesce with successor, if possible */
if (0 != nexthdr && HBLK_IS_FREE(nexthdr)) {
nextsize = nexthdr -> hb_sz;
if (IS_MAPPED(hhdr)) {
GC_ASSERT(!IS_MAPPED(nexthdr));
/* make both consistent, so that we can merge */
if (size > nextsize) {
GC_remap((ptr_t)next, nextsize);
} else {
GC_unmap((ptr_t)h, size);
hhdr -> hb_flags |= WAS_UNMAPPED;
}
} else if (IS_MAPPED(nexthdr)) {
GC_ASSERT(!IS_MAPPED(hhdr));
if (size > nextsize) {
GC_unmap((ptr_t)next, nextsize);
} else {
GC_remap((ptr_t)h, size);
hhdr -> hb_flags &= ~WAS_UNMAPPED;
}
} else {
/* Unmap any gap in the middle */
GC_unmap_gap((ptr_t)h, size, (ptr_t)next, nexthdr -> hb_sz);
}
/* If they are both unmapped, we merge, but leave unmapped. */
GC_remove_from_fl(hhdr, i);
GC_remove_from_fl(nexthdr, FL_UNKNOWN);
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 mergable 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.
*/
struct hblk * GC_get_first_part(h, hhdr, bytes, index)
struct hblk *h;
hdr * hhdr;
word 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(hhdr, index);
if (total_size == bytes) return h;
rest = (struct hblk *)((word)h + bytes);
if (!GC_install_header(rest)) return(0);
rest_hdr = HDR(rest);
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_map = 0;
# 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 allocated.
* It may in fact end up on the wrong free list for its size.
* (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.)
*/
void GC_split_block(h, hhdr, n, nhdr, index)
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;
/* Replace h with n on its freelist */
nhdr -> hb_prev = prev;
nhdr -> hb_next = next;
nhdr -> hb_sz = total_size - h_size;
nhdr -> hb_flags = 0;
if (0 != prev) {
HDR(prev) -> hb_next = n;
} else {
GC_hblkfreelist[index] = n;
}
if (0 != next) {
HDR(next) -> hb_prev = n;
}
# ifdef GC_ASSERTIONS
nhdr -> hb_map = 0; /* Don't fail test for consecutive */
/* free blocks in GC_add_to_fl. */
# endif
# ifdef USE_MUNMAP
hhdr -> hb_last_reclaimed = GC_gc_no;
# endif
hhdr -> hb_sz = h_size;
GC_add_to_fl(h, hhdr);
GC_invalidate_map(nhdr);
}
struct hblk * GC_allochblk_nth();
/*
* Allocate (and return pointer to) a heap block
* for objects of size sz words, searching the nth free list.
*
* NOTE: We set obj_map field in header correctly.
* Caller is responsible for building an object freelist in block.
*
* We clear the block if it is destined for large objects, and if
* kind requires that newly allocated objects be cleared.
*/
struct hblk *
GC_allochblk(sz, kind, flags)
word sz;
int kind;
unsigned char flags; /* IGNORE_OFF_PAGE or 0 */
{
int start_list = GC_hblk_fl_from_blocks(OBJ_SZ_TO_BLOCKS(sz));
int i;
for (i = start_list; i <= N_HBLK_FLS; ++i) {
struct hblk * result = GC_allochblk_nth(sz, kind, flags, i);
if (0 != result) return result;
}
return 0;
}
/*
* The same, but with search restricted to nth free list.
*/
struct hblk *
GC_allochblk_nth(sz, kind, flags, n)
word sz;
int kind;
unsigned char flags; /* IGNORE_OFF_PAGE or 0 */
int n;
{
register struct hblk *hbp;
register hdr * hhdr; /* Header corr. to hbp */
register struct hblk *thishbp;
register hdr * thishdr; /* Header corr. to hbp */
signed_word size_needed; /* number of bytes in requested objects */
signed_word size_avail; /* bytes available in this block */
size_needed = HBLKSIZE * OBJ_SZ_TO_BLOCKS(sz);
/* search for a big enough block in free list */
hbp = GC_hblkfreelist[n];
hhdr = HDR(hbp);
for(; 0 != hbp; hbp = hhdr -> hb_next, hhdr = HDR(hbp)) {
size_avail = hhdr->hb_sz;
if (size_avail < size_needed) continue;
# ifdef PRESERVE_LAST
if (size_avail != size_needed
&& !GC_incremental && GC_should_collect()) {
continue;
}
# endif
/* If the next heap block is obviously better, go on. */
/* This prevents us from disassembling a single large block */
/* to get tiny blocks. */
{
signed_word next_size;
thishbp = hhdr -> hb_next;
if (thishbp != 0) {
thishdr = HDR(thishbp);
next_size = (signed_word)(thishdr -> hb_sz);
if (next_size < size_avail
&& next_size >= size_needed
&& !GC_is_black_listed(thishbp, (word)size_needed)) {
continue;
}
}
}
if ( !IS_UNCOLLECTABLE(kind) &&
(kind != PTRFREE || size_needed > MAX_BLACK_LIST_ALLOC)) {
struct hblk * lasthbp = hbp;
ptr_t search_end = (ptr_t)hbp + size_avail - size_needed;
signed_word orig_avail = size_avail;
signed_word eff_size_needed = ((flags & IGNORE_OFF_PAGE)?
HBLKSIZE
: size_needed);
while ((ptr_t)lasthbp <= search_end
&& (thishbp = GC_is_black_listed(lasthbp,
(word)eff_size_needed))) {
lasthbp = thishbp;
}
size_avail -= (ptr_t)lasthbp - (ptr_t)hbp;
thishbp = lasthbp;
if (size_avail >= size_needed) {
if (thishbp != hbp && GC_install_header(thishbp)) {
/* Make sure it's mapped before we mangle it. */
# ifdef USE_MUNMAP
if (!IS_MAPPED(hhdr)) {
GC_remap((ptr_t)hbp, size_avail);
hhdr -> hb_flags &= ~WAS_UNMAPPED;
}
# endif
/* Split the block at thishbp */
thishdr = HDR(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. */
WARN("Needed to allocate blacklisted block at 0x%lx\n",
(word)hbp);
size_avail = orig_avail;
} else if (size_avail == 0 && size_needed == 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 pointerfree */
/* 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_words_wasted += total_size;
GC_large_free_bytes -= total_size;
GC_remove_from_fl(hhdr, n);
for (h = hbp; h < limit; h++) {
if (h == hbp || GC_install_header(h)) {
hhdr = HDR(h);
(void) setup_header(
hhdr,
BYTES_TO_WORDS(HBLKSIZE - HDR_BYTES),
PTRFREE, 0); /* Cant fail */
if (GC_debugging_started) {
BZERO(h + HDR_BYTES, HBLKSIZE - HDR_BYTES);
}
}
}
/* Restore hbp to point at free block */
hbp = prev;
if (0 == hbp) {
return GC_allochblk_nth(sz, kind, flags, n);
}
hhdr = HDR(hbp);
}
}
}
}
if( size_avail >= size_needed ) {
# ifdef USE_MUNMAP
if (!IS_MAPPED(hhdr)) {
GC_remap((ptr_t)hbp, size_avail);
hhdr -> hb_flags &= ~WAS_UNMAPPED;
}
# 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;
/* Notify virtual dirty bit implementation that we are about to write. */
GC_write_hint(hbp);
/* 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, sz, kind, flags)) {
GC_remove_counts(hbp, (word)size_needed);
return(0); /* ditto */
}
/* Clear block if necessary */
if (GC_debugging_started
|| sz > MAXOBJSZ && GC_obj_kinds[kind].ok_init) {
BZERO(hbp + HDR_BYTES, size_needed - HDR_BYTES);
}
/* We just successfully allocated a block. Restart count of */
/* consecutive failures. */
{
extern unsigned GC_fail_count;
GC_fail_count = 0;
}
GC_large_free_bytes -= size_needed;
GC_ASSERT(IS_MAPPED(hhdr));
return( hbp );
}
struct hblk * GC_freehblk_ptr = 0; /* Search position hint for GC_freehblk */
/*
* Free a heap block.
*
* Coalesce the block with its neighbors if possible.
*
* All mark words are assumed to be cleared.
*/
void
GC_freehblk(hbp)
struct hblk *hbp;
{
struct hblk *next, *prev;
hdr *hhdr, *prevhdr, *nexthdr;
signed_word size;
hhdr = HDR(hbp);
size = hhdr->hb_sz;
size = HBLKSIZE * OBJ_SZ_TO_BLOCKS(size);
GC_remove_counts(hbp, (word)size);
hhdr->hb_sz = size;
/* Check for duplicate deallocation in the easy case */
if (HBLK_IS_FREE(hhdr)) {
GC_printf1("Duplicate large block deallocation of 0x%lx\n",
(unsigned long) hbp);
}
GC_ASSERT(IS_MAPPED(hhdr));
GC_invalidate_map(hhdr);
next = (struct hblk *)((word)hbp + size);
nexthdr = HDR(next);
prev = GC_free_block_ending_at(hbp);
/* Coalesce with successor, if possible */
if(0 != nexthdr && HBLK_IS_FREE(nexthdr) && IS_MAPPED(nexthdr)) {
GC_remove_from_fl(nexthdr, FL_UNKNOWN);
hhdr -> hb_sz += nexthdr -> hb_sz;
GC_remove_header(next);
}
/* Coalesce with predecessor, if possible. */
if (0 != prev) {
prevhdr = HDR(prev);
if (IS_MAPPED(prevhdr)) {
GC_remove_from_fl(prevhdr, FL_UNKNOWN);
prevhdr -> hb_sz += hhdr -> hb_sz;
GC_remove_header(hbp);
hbp = prev;
hhdr = prevhdr;
}
}
GC_large_free_bytes += size;
GC_add_to_fl(hbp, hhdr);
}
