2
* Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
3
* Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
4
* Copyright (c) 1996 by Silicon Graphics. All rights reserved.
6
* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
7
* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
9
* Permission is hereby granted to use or copy this program
10
* for any purpose, provided the above notices are retained on all copies.
11
* Permission to modify the code and to distribute modified code is granted,
12
* provided the above notices are retained, and a notice that the code was
13
* modified is included with the above copyright notice.
18
* 1. allocation of heap block headers
19
* 2. A map from addresses to heap block addresses to heap block headers
21
* Access speed is crucial. We implement an index structure based on a 2
25
# include "private/gc_priv.h"
27
bottom_index * GC_all_bottom_indices = 0;
28
/* Pointer to first (lowest addr) */
31
bottom_index * GC_all_bottom_indices_end = 0;
32
/* Pointer to last (highest addr) */
35
/* Non-macro version of header location routine */
36
hdr * GC_find_header(h)
40
register hdr * result;
48
/* Routines to dynamically allocate collector data structures that will */
51
static ptr_t scratch_free_ptr = 0;
53
/* GC_scratch_last_end_ptr is end point of last obtained scratch area. */
54
/* GC_scratch_end_ptr is end point of current scratch area. */
56
ptr_t GC_scratch_alloc(bytes)
59
register ptr_t result = scratch_free_ptr;
62
# define GRANULARITY (2 * sizeof(word))
64
# define GRANULARITY sizeof(word)
66
bytes += GRANULARITY-1;
67
bytes &= ~(GRANULARITY-1);
68
scratch_free_ptr += bytes;
69
if (scratch_free_ptr <= GC_scratch_end_ptr) {
73
word bytes_to_get = MINHINCR * HBLKSIZE;
75
if (bytes_to_get <= bytes) {
76
/* Undo the damage, and get memory directly */
79
bytes_to_get += GC_page_size - 1;
80
bytes_to_get &= ~(GC_page_size - 1);
82
result = (ptr_t)GET_MEM(bytes_to_get);
83
scratch_free_ptr -= bytes;
84
GC_scratch_last_end_ptr = result + bytes;
87
result = (ptr_t)GET_MEM(bytes_to_get);
90
GC_printf0("Out of memory - trying to allocate less\n");
92
scratch_free_ptr -= bytes;
95
bytes_to_get += GC_page_size - 1;
96
bytes_to_get &= ~(GC_page_size - 1);
98
return((ptr_t)GET_MEM(bytes_to_get));
100
scratch_free_ptr = result;
101
GC_scratch_end_ptr = scratch_free_ptr + bytes_to_get;
102
GC_scratch_last_end_ptr = GC_scratch_end_ptr;
103
return(GC_scratch_alloc(bytes));
107
static hdr * hdr_free_list = 0;
109
/* Return an uninitialized header */
110
static hdr * alloc_hdr()
112
register hdr * result;
114
if (hdr_free_list == 0) {
115
result = (hdr *) GC_scratch_alloc((word)(sizeof(hdr)));
117
result = hdr_free_list;
118
hdr_free_list = (hdr *) (result -> hb_next);
123
static void free_hdr(hhdr)
126
hhdr -> hb_next = (struct hblk *) hdr_free_list;
127
hdr_free_list = hhdr;
130
hdr * GC_invalid_header;
133
word GC_hdr_cache_hits = 0;
134
word GC_hdr_cache_misses = 0;
137
void GC_init_headers()
141
GC_all_nils = (bottom_index *)GC_scratch_alloc((word)sizeof(bottom_index));
142
BZERO(GC_all_nils, sizeof(bottom_index));
143
for (i = 0; i < TOP_SZ; i++) {
144
GC_top_index[i] = GC_all_nils;
146
GC_invalid_header = alloc_hdr();
147
GC_invalidate_map(GC_invalid_header);
150
/* Make sure that there is a bottom level index block for address addr */
151
/* Return FALSE on failure. */
152
static GC_bool get_index(addr)
155
word hi = (word)(addr) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
158
bottom_index ** prev;
162
unsigned i = TL_HASH(hi);
165
old = p = GC_top_index[i];
166
while(p != GC_all_nils) {
167
if (p -> key == hi) return(TRUE);
170
r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
171
if (r == 0) return(FALSE);
172
BZERO(r, sizeof (bottom_index));
173
r -> hash_link = old;
176
if (GC_top_index[hi] != GC_all_nils) return(TRUE);
177
r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
178
if (r == 0) return(FALSE);
179
GC_top_index[hi] = r;
180
BZERO(r, sizeof (bottom_index));
183
/* Add it to the list of bottom indices */
184
prev = &GC_all_bottom_indices; /* pointer to p */
185
pi = 0; /* bottom_index preceding p */
186
while ((p = *prev) != 0 && p -> key < hi) {
188
prev = &(p -> asc_link);
192
GC_all_bottom_indices_end = r;
201
/* Install a header for block h. */
202
/* The header is uninitialized. */
203
/* Returns the header or 0 on failure. */
204
struct hblkhdr * GC_install_header(h)
205
register struct hblk * h;
209
if (!get_index((word) h)) return(FALSE);
210
result = alloc_hdr();
213
result -> hb_last_reclaimed = GC_gc_no;
218
/* Set up forwarding counts for block h of size sz */
219
GC_bool GC_install_counts(h, sz)
220
register struct hblk * h;
221
register word sz; /* bytes */
223
register struct hblk * hbp;
226
for (hbp = h; (char *)hbp < (char *)h + sz; hbp += BOTTOM_SZ) {
227
if (!get_index((word) hbp)) return(FALSE);
229
if (!get_index((word)h + sz - 1)) return(FALSE);
230
for (hbp = h + 1; (char *)hbp < (char *)h + sz; hbp += 1) {
231
i = HBLK_PTR_DIFF(hbp, h);
232
SET_HDR(hbp, (hdr *)(i > MAX_JUMP? MAX_JUMP : i));
237
/* Remove the header for block h */
238
void GC_remove_header(h)
239
register struct hblk * h;
248
/* Remove forwarding counts for h */
249
void GC_remove_counts(h, sz)
250
register struct hblk * h;
251
register word sz; /* bytes */
253
register struct hblk * hbp;
255
for (hbp = h+1; (char *)hbp < (char *)h + sz; hbp += 1) {
260
/* Apply fn to all allocated blocks */
262
void GC_apply_to_all_blocks(fn, client_data)
263
void (*fn) GC_PROTO((struct hblk *h, word client_data));
267
register bottom_index * index_p;
269
for (index_p = GC_all_bottom_indices; index_p != 0;
270
index_p = index_p -> asc_link) {
271
for (j = BOTTOM_SZ-1; j >= 0;) {
272
if (!IS_FORWARDING_ADDR_OR_NIL(index_p->index[j])) {
273
if (index_p->index[j]->hb_map != GC_invalid_map) {
274
(*fn)(((struct hblk *)
275
(((index_p->key << LOG_BOTTOM_SZ) + (word)j)
280
} else if (index_p->index[j] == 0) {
283
j -= (word)(index_p->index[j]);
289
/* Get the next valid block whose address is at least h */
290
/* Return 0 if there is none. */
291
struct hblk * GC_next_used_block(h)
294
register bottom_index * bi;
295
register word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
298
if (bi == GC_all_nils) {
299
register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
300
bi = GC_all_bottom_indices;
301
while (bi != 0 && bi -> key < hi) bi = bi -> asc_link;
305
while (j < BOTTOM_SZ) {
306
hdr * hhdr = bi -> index[j];
307
if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
310
if (hhdr->hb_map != GC_invalid_map) {
311
return((struct hblk *)
312
(((bi -> key << LOG_BOTTOM_SZ) + j)
315
j += divHBLKSZ(hhdr -> hb_sz);
325
/* Get the last (highest address) block whose address is */
326
/* at most h. Return 0 if there is none. */
327
/* Unlike the above, this may return a free block. */
328
struct hblk * GC_prev_block(h)
331
register bottom_index * bi;
332
register signed_word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
335
if (bi == GC_all_nils) {
336
register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
337
bi = GC_all_bottom_indices_end;
338
while (bi != 0 && bi -> key > hi) bi = bi -> desc_link;
343
hdr * hhdr = bi -> index[j];
346
} else if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
347
j -= (signed_word)hhdr;
349
return((struct hblk *)
350
(((bi -> key << LOG_BOTTOM_SZ) + j)
355
bi = bi -> desc_link;