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
27 bottom_index * GC_all_bottom_indices = 0;
29 /* Non-macro version of header location routine */
30 hdr * GC_find_header(h)
34 register hdr * result;
42 /* Routines to dynamically allocate collector data structures that will */
45 static ptr_t scratch_free_ptr = 0;
47 ptr_t GC_scratch_end_ptr = 0;
49 ptr_t GC_scratch_last_end_ptr = 0;
50 /* End point of last obtained scratch area */
52 ptr_t GC_scratch_alloc(bytes)
55 register ptr_t result = scratch_free_ptr;
56 register word bytes_needed = bytes;
59 # define GRANULARITY (2 * sizeof(word))
61 # define GRANULARITY sizeof(word)
63 bytes += GRANULARITY-1;
64 bytes &= ~(GRANULARITY-1);
65 scratch_free_ptr += bytes;
66 if (scratch_free_ptr <= GC_scratch_end_ptr) {
70 word bytes_to_get = MINHINCR * HBLKSIZE;
72 if (bytes_to_get <= bytes) {
73 /* Undo the damage, and get memory directly */
76 bytes_to_get += GC_page_size - 1;
77 bytes_to_get &= ~(GC_page_size - 1);
79 result = (ptr_t)GET_MEM(bytes_to_get);
80 scratch_free_ptr -= bytes;
81 GC_scratch_last_end_ptr = result + bytes;
84 result = (ptr_t)GET_MEM(bytes_to_get);
87 GC_printf0("Out of memory - trying to allocate less\n");
89 scratch_free_ptr -= bytes;
92 bytes_to_get += GC_page_size - 1;
93 bytes_to_get &= (GC_page_size - 1);
95 return((ptr_t)GET_MEM(bytes_to_get));
97 scratch_free_ptr = result;
98 GC_scratch_end_ptr = scratch_free_ptr + bytes_to_get;
99 GC_scratch_last_end_ptr = GC_scratch_end_ptr;
100 return(GC_scratch_alloc(bytes));
104 static hdr * hdr_free_list = 0;
106 /* Return an uninitialized header */
107 static hdr * alloc_hdr()
109 register hdr * result;
111 if (hdr_free_list == 0) {
112 result = (hdr *) GC_scratch_alloc((word)(sizeof(hdr)));
114 result = hdr_free_list;
115 hdr_free_list = (hdr *) (result -> hb_next);
120 static void free_hdr(hhdr)
123 hhdr -> hb_next = (struct hblk *) hdr_free_list;
124 hdr_free_list = hhdr;
127 void GC_init_headers()
131 GC_all_nils = (bottom_index *)GC_scratch_alloc((word)sizeof(bottom_index));
132 BZERO(GC_all_nils, sizeof(bottom_index));
133 for (i = 0; i < TOP_SZ; i++) {
134 GC_top_index[i] = GC_all_nils;
138 /* Make sure that there is a bottom level index block for address addr */
139 /* Return FALSE on failure. */
140 static GC_bool get_index(addr)
144 (word)(addr) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
145 register bottom_index * r;
146 register bottom_index * p;
147 register bottom_index ** prev;
149 register unsigned i = TL_HASH(hi);
150 register bottom_index * old;
152 old = p = GC_top_index[i];
153 while(p != GC_all_nils) {
154 if (p -> key == hi) return(TRUE);
157 r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
158 if (r == 0) return(FALSE);
159 BZERO(r, sizeof (bottom_index));
160 r -> hash_link = old;
163 if (GC_top_index[hi] != GC_all_nils) return(TRUE);
164 r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
165 if (r == 0) return(FALSE);
166 GC_top_index[hi] = r;
167 BZERO(r, sizeof (bottom_index));
170 /* Add it to the list of bottom indices */
171 prev = &GC_all_bottom_indices;
172 while ((p = *prev) != 0 && p -> key < hi) prev = &(p -> asc_link);
178 /* Install a header for block h. */
179 /* The header is uninitialized. */
180 /* Returns FALSE on failure. */
181 GC_bool GC_install_header(h)
182 register struct hblk * h;
186 if (!get_index((word) h)) return(FALSE);
187 result = alloc_hdr();
192 /* Set up forwarding counts for block h of size sz */
193 GC_bool GC_install_counts(h, sz)
194 register struct hblk * h;
195 register word sz; /* bytes */
197 register struct hblk * hbp;
200 for (hbp = h; (char *)hbp < (char *)h + sz; hbp += BOTTOM_SZ) {
201 if (!get_index((word) hbp)) return(FALSE);
203 if (!get_index((word)h + sz - 1)) return(FALSE);
204 for (hbp = h + 1; (char *)hbp < (char *)h + sz; hbp += 1) {
205 i = HBLK_PTR_DIFF(hbp, h);
206 SET_HDR(hbp, (hdr *)(i > MAX_JUMP? MAX_JUMP : i));
211 /* Remove the header for block h */
212 void GC_remove_header(h)
213 register struct hblk * h;
222 /* Remove forwarding counts for h */
223 void GC_remove_counts(h, sz)
224 register struct hblk * h;
225 register word sz; /* bytes */
227 register struct hblk * hbp;
229 for (hbp = h+1; (char *)hbp < (char *)h + sz; hbp += 1) {
234 /* Apply fn to all allocated blocks */
236 void GC_apply_to_all_blocks(fn, client_data)
237 void (*fn)(/* struct hblk *h, word client_data */);
241 register bottom_index * index_p;
243 for (index_p = GC_all_bottom_indices; index_p != 0;
244 index_p = index_p -> asc_link) {
245 for (j = BOTTOM_SZ-1; j >= 0;) {
246 if (!IS_FORWARDING_ADDR_OR_NIL(index_p->index[j])) {
247 if (index_p->index[j]->hb_map != GC_invalid_map) {
248 (*fn)(((struct hblk *)
249 (((index_p->key << LOG_BOTTOM_SZ) + (word)j)
254 } else if (index_p->index[j] == 0) {
257 j -= (word)(index_p->index[j]);
263 /* Get the next valid block whose address is at least h */
264 /* Return 0 if there is none. */
265 struct hblk * GC_next_block(h)
268 register bottom_index * bi;
269 register word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
272 if (bi == GC_all_nils) {
273 register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
274 bi = GC_all_bottom_indices;
275 while (bi != 0 && bi -> key < hi) bi = bi -> asc_link;
279 while (j < BOTTOM_SZ) {
280 if (IS_FORWARDING_ADDR_OR_NIL(bi -> index[j])) {
283 if (bi->index[j]->hb_map != GC_invalid_map) {
284 return((struct hblk *)
285 (((bi -> key << LOG_BOTTOM_SZ) + j)
288 j += divHBLKSZ(bi->index[j] -> hb_sz);