1 /*
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.
5 *
6 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
7 * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
8 *
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.
14 */
15
16 /*
17 * This implements:
18 * 1. allocation of heap block headers
19 * 2. A map from addresses to heap block addresses to heap block headers
20 *
21 * Access speed is crucial. We implement an index structure based on a 2
22 * level tree.
23 */
24
25 # include "private/gc_priv.h"
26
27 bottom_index * GC_all_bottom_indices = 0;
28 /* Pointer to first (lowest addr) */
29 /* bottom_index. */
30
31 bottom_index * GC_all_bottom_indices_end = 0;
32 /* Pointer to last (highest addr) */
33 /* bottom_index. */
34
35 /* Non-macro version of header location routine */
GC_find_header(h)36 hdr * GC_find_header(h)
37 ptr_t h;
38 {
39 # ifdef HASH_TL
40 register hdr * result;
41 GET_HDR(h, result);
42 return(result);
43 # else
44 return(HDR_INNER(h));
45 # endif
46 }
47
48 /* Routines to dynamically allocate collector data structures that will */
49 /* never be freed. */
50
51 static ptr_t scratch_free_ptr = 0;
52
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. */
55
GC_scratch_alloc(bytes)56 ptr_t GC_scratch_alloc(bytes)
57 register word bytes;
58 {
59 register ptr_t result = scratch_free_ptr;
60
61 # ifdef ALIGN_DOUBLE
62 # define GRANULARITY (2 * sizeof(word))
63 # else
64 # define GRANULARITY sizeof(word)
65 # endif
66 bytes += GRANULARITY-1;
67 bytes &= ~(GRANULARITY-1);
68 scratch_free_ptr += bytes;
69 if (scratch_free_ptr <= GC_scratch_end_ptr) {
70 return(result);
71 }
72 {
73 word bytes_to_get = MINHINCR * HBLKSIZE;
74
75 if (bytes_to_get <= bytes) {
76 /* Undo the damage, and get memory directly */
77 bytes_to_get = bytes;
78 # ifdef USE_MMAP
79 bytes_to_get += GC_page_size - 1;
80 bytes_to_get &= ~(GC_page_size - 1);
81 # endif
82 result = (ptr_t)GET_MEM(bytes_to_get);
83 scratch_free_ptr -= bytes;
84 GC_scratch_last_end_ptr = result + bytes;
85 return(result);
86 }
87 result = (ptr_t)GET_MEM(bytes_to_get);
88 if (result == 0) {
89 # ifdef PRINTSTATS
90 GC_printf0("Out of memory - trying to allocate less\n");
91 # endif
92 scratch_free_ptr -= bytes;
93 bytes_to_get = bytes;
94 # ifdef USE_MMAP
95 bytes_to_get += GC_page_size - 1;
96 bytes_to_get &= ~(GC_page_size - 1);
97 # endif
98 return((ptr_t)GET_MEM(bytes_to_get));
99 }
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));
104 }
105 }
106
107 static hdr * hdr_free_list = 0;
108
109 /* Return an uninitialized header */
alloc_hdr()110 static hdr * alloc_hdr()
111 {
112 register hdr * result;
113
114 if (hdr_free_list == 0) {
115 result = (hdr *) GC_scratch_alloc((word)(sizeof(hdr)));
116 } else {
117 result = hdr_free_list;
118 hdr_free_list = (hdr *) (result -> hb_next);
119 }
120 return(result);
121 }
122
free_hdr(hhdr)123 static void free_hdr(hhdr)
124 hdr * hhdr;
125 {
126 hhdr -> hb_next = (struct hblk *) hdr_free_list;
127 hdr_free_list = hhdr;
128 }
129
130 hdr * GC_invalid_header;
131
132 #ifdef USE_HDR_CACHE
133 word GC_hdr_cache_hits = 0;
134 word GC_hdr_cache_misses = 0;
135 #endif
136
GC_init_headers()137 void GC_init_headers()
138 {
139 register unsigned i;
140
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;
145 }
146 GC_invalid_header = alloc_hdr();
147 GC_invalidate_map(GC_invalid_header);
148 }
149
150 /* Make sure that there is a bottom level index block for address addr */
151 /* Return FALSE on failure. */
get_index(addr)152 static GC_bool get_index(addr)
153 word addr;
154 {
155 word hi = (word)(addr) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
156 bottom_index * r;
157 bottom_index * p;
158 bottom_index ** prev;
159 bottom_index *pi;
160
161 # ifdef HASH_TL
162 unsigned i = TL_HASH(hi);
163 bottom_index * old;
164
165 old = p = GC_top_index[i];
166 while(p != GC_all_nils) {
167 if (p -> key == hi) return(TRUE);
168 p = p -> hash_link;
169 }
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;
174 GC_top_index[i] = r;
175 # else
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));
181 # endif
182 r -> key = hi;
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) {
187 pi = p;
188 prev = &(p -> asc_link);
189 }
190 r -> desc_link = pi;
191 if (0 == p) {
192 GC_all_bottom_indices_end = r;
193 } else {
194 p -> desc_link = r;
195 }
196 r -> asc_link = p;
197 *prev = r;
198 return(TRUE);
199 }
200
201 /* Install a header for block h. */
202 /* The header is uninitialized. */
203 /* Returns the header or 0 on failure. */
GC_install_header(h)204 struct hblkhdr * GC_install_header(h)
205 register struct hblk * h;
206 {
207 hdr * result;
208
209 if (!get_index((word) h)) return(0);
210 result = alloc_hdr();
211 SET_HDR(h, result);
212 # ifdef USE_MUNMAP
213 result -> hb_last_reclaimed = GC_gc_no;
214 # endif
215 return(result);
216 }
217
218 /* Set up forwarding counts for block h of size sz */
GC_install_counts(h,sz)219 GC_bool GC_install_counts(h, sz)
220 register struct hblk * h;
221 register word sz; /* bytes */
222 {
223 register struct hblk * hbp;
224 register int i;
225
226 for (hbp = h; (char *)hbp < (char *)h + sz; hbp += BOTTOM_SZ) {
227 if (!get_index((word) hbp)) return(FALSE);
228 }
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));
233 }
234 return(TRUE);
235 }
236
237 /* Remove the header for block h */
GC_remove_header(h)238 void GC_remove_header(h)
239 register struct hblk * h;
240 {
241 hdr ** ha;
242
243 GET_HDR_ADDR(h, ha);
244 free_hdr(*ha);
245 *ha = 0;
246 }
247
248 /* Remove forwarding counts for h */
GC_remove_counts(h,sz)249 void GC_remove_counts(h, sz)
250 register struct hblk * h;
251 register word sz; /* bytes */
252 {
253 register struct hblk * hbp;
254
255 for (hbp = h+1; (char *)hbp < (char *)h + sz; hbp += 1) {
256 SET_HDR(hbp, 0);
257 }
258 }
259
260 /* Apply fn to all allocated blocks */
261 /*VARARGS1*/
262 void GC_apply_to_all_blocks(fn, client_data)
263 void (*fn) GC_PROTO((struct hblk *h, word client_data));
264 word client_data;
265 {
266 register int j;
267 register bottom_index * index_p;
268
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)
276 << LOG_HBLKSIZE)),
277 client_data);
278 }
279 j--;
280 } else if (index_p->index[j] == 0) {
281 j--;
282 } else {
283 j -= (word)(index_p->index[j]);
284 }
285 }
286 }
287 }
288
289 /* Get the next valid block whose address is at least h */
290 /* Return 0 if there is none. */
GC_next_used_block(h)291 struct hblk * GC_next_used_block(h)
292 struct hblk * h;
293 {
294 register bottom_index * bi;
295 register word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
296
297 GET_BI(h, bi);
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;
302 j = 0;
303 }
304 while(bi != 0) {
305 while (j < BOTTOM_SZ) {
306 hdr * hhdr = bi -> index[j];
307 if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
308 j++;
309 } else {
310 if (hhdr->hb_map != GC_invalid_map) {
311 return((struct hblk *)
312 (((bi -> key << LOG_BOTTOM_SZ) + j)
313 << LOG_HBLKSIZE));
314 } else {
315 j += divHBLKSZ(hhdr -> hb_sz);
316 }
317 }
318 }
319 j = 0;
320 bi = bi -> asc_link;
321 }
322 return(0);
323 }
324
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. */
GC_prev_block(h)328 struct hblk * GC_prev_block(h)
329 struct hblk * h;
330 {
331 register bottom_index * bi;
332 register signed_word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
333
334 GET_BI(h, bi);
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;
339 j = BOTTOM_SZ - 1;
340 }
341 while(bi != 0) {
342 while (j >= 0) {
343 hdr * hhdr = bi -> index[j];
344 if (0 == hhdr) {
345 --j;
346 } else if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
347 j -= (signed_word)hhdr;
348 } else {
349 return((struct hblk *)
350 (((bi -> key << LOG_BOTTOM_SZ) + j)
351 << LOG_HBLKSIZE));
352 }
353 }
354 j = BOTTOM_SZ - 1;
355 bi = bi -> desc_link;
356 }
357 return(0);
358 }
359