/*
* Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
* Copyright (c) 1991-1994 by Xerox Corporation. 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.
*/
/* Boehm, August 9, 1995 6:09 pm PDT */
# include "gc_priv.h"
/*
* We maintain several hash tables of hblks that have had false hits.
* Each contains one bit per hash bucket; If any page in the bucket
* has had a false hit, we assume that all of them have.
* See the definition of page_hash_table in gc_private.h.
* False hits from the stack(s) are much more dangerous than false hits
* from elsewhere, since the former can pin a large object that spans the
* block, eventhough it does not start on the dangerous block.
*/
/*
* Externally callable routines are:
* GC_add_to_black_list_normal
* GC_add_to_black_list_stack
* GC_promote_black_lists
* GC_is_black_listed
*
* All require that the allocator lock is held.
*/
/* Pointers to individual tables. We replace one table by another by */
/* switching these pointers. */
word * GC_old_normal_bl;
/* Nonstack false references seen at last full */
/* collection. */
word * GC_incomplete_normal_bl;
/* Nonstack false references seen since last */
/* full collection. */
word * GC_old_stack_bl;
word * GC_incomplete_stack_bl;
word GC_total_stack_black_listed;
word GC_black_list_spacing = MINHINCR*HBLKSIZE; /* Initial rough guess */
void GC_clear_bl();
void GC_default_print_heap_obj_proc(p)
ptr_t p;
{
ptr_t base = GC_base(p);
GC_err_printf2("start: 0x%lx, appr. length: %ld", base, GC_size(base));
}
void (*GC_print_heap_obj)(/* char * s, ptr_t p */) =
GC_default_print_heap_obj_proc;
void GC_print_source_ptr(p)
ptr_t p;
{
ptr_t base = GC_base(p);
if (0 == base) {
if (0 == p) {
GC_err_printf0("in register");
} else {
GC_err_printf0("in root set");
}
} else {
GC_err_printf0("in object at ");
(*GC_print_heap_obj)(base);
}
}
void GC_bl_init()
{
# ifndef ALL_INTERIOR_POINTERS
GC_old_normal_bl = (word *)
GC_scratch_alloc((word)(sizeof (page_hash_table)));
GC_incomplete_normal_bl = (word *)GC_scratch_alloc
((word)(sizeof(page_hash_table)));
if (GC_old_normal_bl == 0 || GC_incomplete_normal_bl == 0) {
GC_err_printf0("Insufficient memory for black list\n");
EXIT();
}
GC_clear_bl(GC_old_normal_bl);
GC_clear_bl(GC_incomplete_normal_bl);
# endif
GC_old_stack_bl = (word *)GC_scratch_alloc((word)(sizeof(page_hash_table)));
GC_incomplete_stack_bl = (word *)GC_scratch_alloc
((word)(sizeof(page_hash_table)));
if (GC_old_stack_bl == 0 || GC_incomplete_stack_bl == 0) {
GC_err_printf0("Insufficient memory for black list\n");
EXIT();
}
GC_clear_bl(GC_old_stack_bl);
GC_clear_bl(GC_incomplete_stack_bl);
}
void GC_clear_bl(doomed)
word *doomed;
{
BZERO(doomed, sizeof(page_hash_table));
}
void GC_copy_bl(old, new)
word *new, *old;
{
BCOPY(old, new, sizeof(page_hash_table));
}
static word total_stack_black_listed();
/* Signal the completion of a collection. Turn the incomplete black */
/* lists into new black lists, etc. */
void GC_promote_black_lists()
{
word * very_old_normal_bl = GC_old_normal_bl;
word * very_old_stack_bl = GC_old_stack_bl;
GC_old_normal_bl = GC_incomplete_normal_bl;
GC_old_stack_bl = GC_incomplete_stack_bl;
# ifndef ALL_INTERIOR_POINTERS
GC_clear_bl(very_old_normal_bl);
# endif
GC_clear_bl(very_old_stack_bl);
GC_incomplete_normal_bl = very_old_normal_bl;
GC_incomplete_stack_bl = very_old_stack_bl;
GC_total_stack_black_listed = total_stack_black_listed();
# ifdef PRINTSTATS
GC_printf1("%ld bytes in heap blacklisted for interior pointers\n",
(unsigned long)GC_total_stack_black_listed);
# endif
if (GC_total_stack_black_listed != 0) {
GC_black_list_spacing =
HBLKSIZE*(GC_heapsize/GC_total_stack_black_listed);
}
if (GC_black_list_spacing < 3 * HBLKSIZE) {
GC_black_list_spacing = 3 * HBLKSIZE;
}
}
void GC_unpromote_black_lists()
{
# ifndef ALL_INTERIOR_POINTERS
GC_copy_bl(GC_old_normal_bl, GC_incomplete_normal_bl);
# endif
GC_copy_bl(GC_old_stack_bl, GC_incomplete_stack_bl);
}
# ifndef ALL_INTERIOR_POINTERS
/* P is not a valid pointer reference, but it falls inside */
/* the plausible heap bounds. */
/* Add it to the normal incomplete black list if appropriate. */
#ifdef PRINT_BLACK_LIST
void GC_add_to_black_list_normal(p, source)
ptr_t source;
#else
void GC_add_to_black_list_normal(p)
#endif
word p;
{
if (!(GC_modws_valid_offsets[p & (sizeof(word)-1)])) return;
{
register int index = PHT_HASH(p);
if (HDR(p) == 0 || get_pht_entry_from_index(GC_old_normal_bl, index)) {
# ifdef PRINT_BLACK_LIST
if (!get_pht_entry_from_index(GC_incomplete_normal_bl, index)) {
GC_err_printf2(
"Black listing (normal) 0x%lx referenced from 0x%lx ",
(unsigned long) p, (unsigned long) source);
GC_print_source_ptr(source);
GC_err_puts("\n");
}
# endif
set_pht_entry_from_index(GC_incomplete_normal_bl, index);
} /* else this is probably just an interior pointer to an allocated */
/* object, and isn't worth black listing. */
}
}
# endif
/* And the same for false pointers from the stack. */
#ifdef PRINT_BLACK_LIST
void GC_add_to_black_list_stack(p, source)
ptr_t source;
#else
void GC_add_to_black_list_stack(p)
#endif
word p;
{
register int index = PHT_HASH(p);
if (HDR(p) == 0 || get_pht_entry_from_index(GC_old_stack_bl, index)) {
# ifdef PRINT_BLACK_LIST
if (!get_pht_entry_from_index(GC_incomplete_stack_bl, index)) {
GC_err_printf2(
"Black listing (stack) 0x%lx referenced from 0x%lx ",
(unsigned long)p, (unsigned long)source);
GC_print_source_ptr(source);
GC_err_puts("\n");
}
# endif
set_pht_entry_from_index(GC_incomplete_stack_bl, index);
}
}
/*
* Is the block starting at h of size len bytes black listed? If so,
* return the address of the next plausible r such that (r, len) might not
* be black listed. (R may not actually be in the heap. We guarantee only
* that every smaller value of r after h is also black listed.)
* If (h,len) is not black listed, return 0.
* Knows about the structure of the black list hash tables.
*/
struct hblk * GC_is_black_listed(h, len)
struct hblk * h;
word len;
{
register int index = PHT_HASH((word)h);
register word i;
word nblocks = divHBLKSZ(len);
# ifndef ALL_INTERIOR_POINTERS
if (get_pht_entry_from_index(GC_old_normal_bl, index)
|| get_pht_entry_from_index(GC_incomplete_normal_bl, index)) {
return(h+1);
}
# endif
for (i = 0; ; ) {
if (GC_old_stack_bl[divWORDSZ(index)] == 0
&& GC_incomplete_stack_bl[divWORDSZ(index)] == 0) {
/* An easy case */
i += WORDSZ - modWORDSZ(index);
} else {
if (get_pht_entry_from_index(GC_old_stack_bl, index)
|| get_pht_entry_from_index(GC_incomplete_stack_bl, index)) {
return(h+i+1);
}
i++;
}
if (i >= nblocks) break;
index = PHT_HASH((word)(h+i));
}
return(0);
}
/* Return the number of blacklisted blocks in a given range. */
/* Used only for statistical purposes. */
/* Looks only at the GC_incomplete_stack_bl. */
word GC_number_stack_black_listed(start, endp1)
struct hblk *start, *endp1;
{
register struct hblk * h;
word result = 0;
for (h = start; h < endp1; h++) {
register int index = PHT_HASH((word)h);
if (get_pht_entry_from_index(GC_old_stack_bl, index)) result++;
}
return(result);
}
/* Return the total number of (stack) black-listed bytes. */
static word total_stack_black_listed()
{
register unsigned i;
word total = 0;
for (i = 0; i < GC_n_heap_sects; i++) {
struct hblk * start = (struct hblk *) GC_heap_sects[i].hs_start;
word len = (word) GC_heap_sects[i].hs_bytes;
struct hblk * endp1 = start + len/HBLKSIZE;
total += GC_number_stack_black_listed(start, endp1);
}
return(total * HBLKSIZE);
}
