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;
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 ptr_t GC_scratch_end_ptr = 0;
55 ptr_t GC_scratch_last_end_ptr = 0;
56 /* End point of last obtained scratch area */
58 ptr_t GC_scratch_alloc(bytes)
61 register ptr_t result = scratch_free_ptr;
64 # define GRANULARITY (2 * sizeof(word))
66 # define GRANULARITY sizeof(word)
68 bytes += GRANULARITY-1;
69 bytes &= ~(GRANULARITY-1);
70 scratch_free_ptr += bytes;
71 if (scratch_free_ptr <= GC_scratch_end_ptr) {
75 word bytes_to_get = MINHINCR * HBLKSIZE;
77 if (bytes_to_get <= bytes) {
78 /* Undo the damage, and get memory directly */
81 bytes_to_get += GC_page_size - 1;
82 bytes_to_get &= ~(GC_page_size - 1);
84 result = (ptr_t)GET_MEM(bytes_to_get);
85 scratch_free_ptr -= bytes;
86 GC_scratch_last_end_ptr = result + bytes;
89 result = (ptr_t)GET_MEM(bytes_to_get);
92 GC_printf0("Out of memory - trying to allocate less\n");
94 scratch_free_ptr -= bytes;
97 bytes_to_get += GC_page_size - 1;
98 bytes_to_get &= ~(GC_page_size - 1);
100 return((ptr_t)GET_MEM(bytes_to_get));
102 scratch_free_ptr = result;
103 GC_scratch_end_ptr = scratch_free_ptr + bytes_to_get;
104 GC_scratch_last_end_ptr = GC_scratch_end_ptr;
105 return(GC_scratch_alloc(bytes));
109 static hdr * hdr_free_list = 0;
111 /* Return an uninitialized header */
112 static hdr * alloc_hdr()
114 register hdr * result;
116 if (hdr_free_list == 0) {
117 result = (hdr *) GC_scratch_alloc((word)(sizeof(hdr)));
119 result = hdr_free_list;
120 hdr_free_list = (hdr *) (result -> hb_next);
125 static void free_hdr(hhdr)
128 hhdr -> hb_next = (struct hblk *) hdr_free_list;
129 hdr_free_list = hhdr;
132 void GC_init_headers()
136 GC_all_nils = (bottom_index *)GC_scratch_alloc((word)sizeof(bottom_index));
137 BZERO(GC_all_nils, sizeof(bottom_index));
138 for (i = 0; i < TOP_SZ; i++) {
139 GC_top_index[i] = GC_all_nils;
143 /* Make sure that there is a bottom level index block for address addr */
144 /* Return FALSE on failure. */
145 static GC_bool get_index(addr)
148 word hi = (word)(addr) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
151 bottom_index ** prev;
155 unsigned i = TL_HASH(hi);
158 old = p = GC_top_index[i];
159 while(p != GC_all_nils) {
160 if (p -> key == hi) return(TRUE);
163 r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
164 if (r == 0) return(FALSE);
165 BZERO(r, sizeof (bottom_index));
166 r -> hash_link = old;
169 if (GC_top_index[hi] != GC_all_nils) return(TRUE);
170 r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
171 if (r == 0) return(FALSE);
172 GC_top_index[hi] = r;
173 BZERO(r, sizeof (bottom_index));
176 /* Add it to the list of bottom indices */
177 prev = &GC_all_bottom_indices; /* pointer to p */
178 pi = 0; /* bottom_index preceding p */
179 while ((p = *prev) != 0 && p -> key < hi) {
181 prev = &(p -> asc_link);
185 GC_all_bottom_indices_end = r;
194 /* Install a header for block h. */
195 /* The header is uninitialized. */
196 /* Returns FALSE on failure. */
197 GC_bool GC_install_header(h)
198 register struct hblk * h;
202 if (!get_index((word) h)) return(FALSE);
203 result = alloc_hdr();
206 result -> hb_last_reclaimed = GC_gc_no;
211 /* Set up forwarding counts for block h of size sz */
212 GC_bool GC_install_counts(h, sz)
213 register struct hblk * h;
214 register word sz; /* bytes */
216 register struct hblk * hbp;
219 for (hbp = h; (char *)hbp < (char *)h + sz; hbp += BOTTOM_SZ) {
220 if (!get_index((word) hbp)) return(FALSE);
222 if (!get_index((word)h + sz - 1)) return(FALSE);
223 for (hbp = h + 1; (char *)hbp < (char *)h + sz; hbp += 1) {
224 i = HBLK_PTR_DIFF(hbp, h);
225 SET_HDR(hbp, (hdr *)(i > MAX_JUMP? MAX_JUMP : i));
230 /* Remove the header for block h */
231 void GC_remove_header(h)
232 register struct hblk * h;
241 /* Remove forwarding counts for h */
242 void GC_remove_counts(h, sz)
243 register struct hblk * h;
244 register word sz; /* bytes */
246 register struct hblk * hbp;
248 for (hbp = h+1; (char *)hbp < (char *)h + sz; hbp += 1) {
253 /* Apply fn to all allocated blocks */
255 void GC_apply_to_all_blocks(fn, client_data)
256 void (*fn)(/* struct hblk *h, word client_data */);
260 register bottom_index * index_p;
262 for (index_p = GC_all_bottom_indices; index_p != 0;
263 index_p = index_p -> asc_link) {
264 for (j = BOTTOM_SZ-1; j >= 0;) {
265 if (!IS_FORWARDING_ADDR_OR_NIL(index_p->index[j])) {
266 if (index_p->index[j]->hb_map != GC_invalid_map) {
267 (*fn)(((struct hblk *)
268 (((index_p->key << LOG_BOTTOM_SZ) + (word)j)
273 } else if (index_p->index[j] == 0) {
276 j -= (word)(index_p->index[j]);
282 /* Get the next valid block whose address is at least h */
283 /* Return 0 if there is none. */
284 struct hblk * GC_next_used_block(h)
287 register bottom_index * bi;
288 register word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
291 if (bi == GC_all_nils) {
292 register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
293 bi = GC_all_bottom_indices;
294 while (bi != 0 && bi -> key < hi) bi = bi -> asc_link;
298 while (j < BOTTOM_SZ) {
299 hdr * hhdr = bi -> index[j];
300 if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
303 if (hhdr->hb_map != GC_invalid_map) {
304 return((struct hblk *)
305 (((bi -> key << LOG_BOTTOM_SZ) + j)
308 j += divHBLKSZ(hhdr -> hb_sz);
318 /* Get the last (highest address) block whose address is */
319 /* at most h. Return 0 if there is none. */
320 /* Unlike the above, this may return a free block. */
321 struct hblk * GC_prev_block(h)
324 register bottom_index * bi;
325 register signed_word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
328 if (bi == GC_all_nils) {
329 register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
330 bi = GC_all_bottom_indices_end;
331 while (bi != 0 && bi -> key > hi) bi = bi -> desc_link;
336 hdr * hhdr = bi -> index[j];
339 } else if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
340 j -= (signed_word)hhdr;
342 return((struct hblk *)
343 (((bi -> key << LOG_BOTTOM_SZ) + j)
348 bi = bi -> desc_link;