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358 lines (322 loc) · 9.71 KB
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/*
* Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
* Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
* Copyright (c) 1996 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.
*/
/*
* This implements:
* 1. allocation of heap block headers
* 2. A map from addresses to heap block addresses to heap block headers
*
* Access speed is crucial. We implement an index structure based on a 2
* level tree.
*/
# include "private/gc_priv.h"
bottom_index * GC_all_bottom_indices = 0;
/* Pointer to first (lowest addr) */
/* bottom_index. */
bottom_index * GC_all_bottom_indices_end = 0;
/* Pointer to last (highest addr) */
/* bottom_index. */
/* Non-macro version of header location routine */
hdr * GC_find_header(h)
ptr_t h;
{
# ifdef HASH_TL
register hdr * result;
GET_HDR(h, result);
return(result);
# else
return(HDR_INNER(h));
# endif
}
/* Routines to dynamically allocate collector data structures that will */
/* never be freed. */
static ptr_t scratch_free_ptr = 0;
/* GC_scratch_last_end_ptr is end point of last obtained scratch area. */
/* GC_scratch_end_ptr is end point of current scratch area. */
ptr_t GC_scratch_alloc(bytes)
register word bytes;
{
register ptr_t result = scratch_free_ptr;
# ifdef ALIGN_DOUBLE
# define GRANULARITY (2 * sizeof(word))
# else
# define GRANULARITY sizeof(word)
# endif
bytes += GRANULARITY-1;
bytes &= ~(GRANULARITY-1);
scratch_free_ptr += bytes;
if (scratch_free_ptr <= GC_scratch_end_ptr) {
return(result);
}
{
word bytes_to_get = MINHINCR * HBLKSIZE;
if (bytes_to_get <= bytes) {
/* Undo the damage, and get memory directly */
bytes_to_get = bytes;
# ifdef USE_MMAP
bytes_to_get += GC_page_size - 1;
bytes_to_get &= ~(GC_page_size - 1);
# endif
result = (ptr_t)GET_MEM(bytes_to_get);
scratch_free_ptr -= bytes;
GC_scratch_last_end_ptr = result + bytes;
return(result);
}
result = (ptr_t)GET_MEM(bytes_to_get);
if (result == 0) {
# ifdef PRINTSTATS
GC_printf0("Out of memory - trying to allocate less\n");
# endif
scratch_free_ptr -= bytes;
bytes_to_get = bytes;
# ifdef USE_MMAP
bytes_to_get += GC_page_size - 1;
bytes_to_get &= ~(GC_page_size - 1);
# endif
return((ptr_t)GET_MEM(bytes_to_get));
}
scratch_free_ptr = result;
GC_scratch_end_ptr = scratch_free_ptr + bytes_to_get;
GC_scratch_last_end_ptr = GC_scratch_end_ptr;
return(GC_scratch_alloc(bytes));
}
}
static hdr * hdr_free_list = 0;
/* Return an uninitialized header */
static hdr * alloc_hdr()
{
register hdr * result;
if (hdr_free_list == 0) {
result = (hdr *) GC_scratch_alloc((word)(sizeof(hdr)));
} else {
result = hdr_free_list;
hdr_free_list = (hdr *) (result -> hb_next);
}
return(result);
}
static void free_hdr(hhdr)
hdr * hhdr;
{
hhdr -> hb_next = (struct hblk *) hdr_free_list;
hdr_free_list = hhdr;
}
hdr * GC_invalid_header;
#ifdef USE_HDR_CACHE
word GC_hdr_cache_hits = 0;
word GC_hdr_cache_misses = 0;
#endif
void GC_init_headers()
{
register unsigned i;
GC_all_nils = (bottom_index *)GC_scratch_alloc((word)sizeof(bottom_index));
BZERO(GC_all_nils, sizeof(bottom_index));
for (i = 0; i < TOP_SZ; i++) {
GC_top_index[i] = GC_all_nils;
}
GC_invalid_header = alloc_hdr();
GC_invalidate_map(GC_invalid_header);
}
/* Make sure that there is a bottom level index block for address addr */
/* Return FALSE on failure. */
static GC_bool get_index(addr)
word addr;
{
word hi = (word)(addr) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
bottom_index * r;
bottom_index * p;
bottom_index ** prev;
bottom_index *pi;
# ifdef HASH_TL
unsigned i = TL_HASH(hi);
bottom_index * old;
old = p = GC_top_index[i];
while(p != GC_all_nils) {
if (p -> key == hi) return(TRUE);
p = p -> hash_link;
}
r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
if (r == 0) return(FALSE);
BZERO(r, sizeof (bottom_index));
r -> hash_link = old;
GC_top_index[i] = r;
# else
if (GC_top_index[hi] != GC_all_nils) return(TRUE);
r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
if (r == 0) return(FALSE);
GC_top_index[hi] = r;
BZERO(r, sizeof (bottom_index));
# endif
r -> key = hi;
/* Add it to the list of bottom indices */
prev = &GC_all_bottom_indices; /* pointer to p */
pi = 0; /* bottom_index preceding p */
while ((p = *prev) != 0 && p -> key < hi) {
pi = p;
prev = &(p -> asc_link);
}
r -> desc_link = pi;
if (0 == p) {
GC_all_bottom_indices_end = r;
} else {
p -> desc_link = r;
}
CC96
r -> asc_link = p;
*prev = r;
return(TRUE);
}
/* Install a header for block h. */
/* The header is uninitialized. */
/* Returns the header or 0 on failure. */
struct hblkhdr * GC_install_header(h)
register struct hblk * h;
{
hdr * result;
if (!get_index((word) h)) return(0);
result = alloc_hdr();
SET_HDR(h, result);
# ifdef USE_MUNMAP
result -> hb_last_reclaimed = (unsigned short)GC_gc_no;
# endif
return(result);
}
/* Set up forwarding counts for block h of size sz */
GC_bool GC_install_counts(h, sz)
register struct hblk * h;
register word sz; /* bytes */
{
register struct hblk * hbp;
register int i;
for (hbp = h; (char *)hbp < (char *)h + sz; hbp += BOTTOM_SZ) {
if (!get_index((word) hbp)) return(FALSE);
}
if (!get_index((word)h + sz - 1)) return(FALSE);
for (hbp = h + 1; (char *)hbp < (char *)h + sz; hbp += 1) {
i = HBLK_PTR_DIFF(hbp, h);
SET_HDR(hbp, (hdr *)(i > MAX_JUMP? MAX_JUMP : i));
}
return(TRUE);
}
/* Remove the header for block h */
void GC_remove_header(h)
register struct hblk * h;
{
hdr ** ha;
GET_HDR_ADDR(h, ha);
free_hdr(*ha);
*ha = 0;
}
/* Remove forwarding counts for h */
void GC_remove_counts(h, sz)
register struct hblk * h;
register word sz; /* bytes */
{
register struct hblk * hbp;
for (hbp = h+1; (char *)hbp < (char *)h + sz; hbp += 1) {
SET_HDR(hbp, 0);
}
}
/* Apply fn to all allocated blocks */
/*VARARGS1*/
void GC_apply_to_all_blocks(fn, client_data)
void (*fn) GC_PROTO((struct hblk *h, word client_data));
word client_data;
{
register int j;
register bottom_index * index_p;
for (index_p = GC_all_bottom_indices; index_p != 0;
index_p = index_p -> asc_link) {
for (j = BOTTOM_SZ-1; j >= 0;) {
if (!IS_FORWARDING_ADDR_OR_NIL(index_p->index[j])) {
if (index_p->index[j]->hb_map != GC_invalid_map) {
(*fn)(((struct hblk *)
(((index_p->key << LOG_BOTTOM_SZ) + (word)j)
<< LOG_HBLKSIZE)),
client_data);
}
j--;
} else if (index_p->index[j] == 0) {
j--;
} else {
j -= (word)(index_p->index[j]);
}
}
}
}
/* Get the next valid block whose address is at least h */
/* Return 0 if there is none. */
struct hblk * GC_next_used_block(h)
struct hblk * h;
{
register bottom_index * bi;
register word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
GET_BI(h, bi);
if (bi == GC_all_nils) {
register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
bi = GC_all_bottom_indices;
while (bi != 0 && bi -> key < hi) bi = bi -> asc_link;
j = 0;
}
while(bi != 0) {
while (j < BOTTOM_SZ) {
hdr * hhdr = bi -> index[j];
if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
j++;
} else {
if (hhdr->hb_map != GC_invalid_map) {
return((struct hblk *)
(((bi -> key << LOG_BOTTOM_SZ) + j)
<< LOG_HBLKSIZE));
} else {
j += divHBLKSZ(hhdr -> hb_sz);
}
}
}
j = 0;
bi = bi -> asc_link;
}
return(0);
}
/* Get the last (highest address) block whose address is */
/* at most h. Return 0 if there is none. */
/* Unlike the above, this may return a free block. */
struct hblk * GC_prev_block(h)
struct hblk * h;
{
register bottom_index * bi;
register signed_word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
GET_BI(h, bi);
if (bi == GC_all_nils) {
register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
bi = GC_all_bottom_indices_end;
while (bi != 0 && bi -> key > hi) bi = bi -> desc_link;
j = BOTTOM_SZ - 1;
}
while(bi != 0) {
while (j >= 0) {
hdr * hhdr = bi -> index[j];
if (0 == hhdr) {
--j;
} else if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
j -= (signed_word)hhdr;
} else {
return((struct hblk *)
(((bi -> key << LOG_BOTTOM_SZ) + j)
<< LOG_HBLKSIZE));
}
}
j = BOTTOM_SZ - 1;
bi = bi -> desc_link;
}
return(0);
}