2 * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
3 * Copyright (c) 1991, 1992 by Xerox Corporation. All rights reserved.
4 * Copyright (c) 1999-2001 by Hewlett-Packard Company. 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.
16 #include "private/gc_priv.h"
18 /* Routines for maintaining maps describing heap block
19 * layouts for various object sizes. Allows fast pointer validity checks
20 * and fast location of object start locations on machines (such as SPARC)
24 /* Consider pointers that are offset bytes displaced from the beginning */
25 /* of an object to be valid. */
27 GC_API void GC_CALL GC_register_displacement(size_t offset)
32 GC_register_displacement_inner(offset);
36 GC_INNER void GC_register_displacement_inner(size_t offset)
38 GC_ASSERT(I_HOLD_LOCK());
39 if (offset >= VALID_OFFSET_SZ) {
40 ABORT("Bad argument to GC_register_displacement");
42 if (!GC_valid_offsets[offset]) {
43 GC_valid_offsets[offset] = TRUE;
44 GC_modws_valid_offsets[offset % sizeof(word)] = TRUE;
48 #ifdef MARK_BIT_PER_GRANULE
49 /* Add a heap block map for objects of size granules to obj_map. */
50 /* Return FALSE on failure. */
51 /* A size of 0 granules is used for large objects. */
52 GC_INNER GC_bool GC_add_map_entry(size_t granules)
55 unsigned short * new_map;
57 if (granules > BYTES_TO_GRANULES(MAXOBJBYTES)) granules = 0;
58 if (GC_obj_map[granules] != 0) {
61 new_map = (unsigned short *)GC_scratch_alloc(MAP_LEN * sizeof(short));
62 if (new_map == 0) return(FALSE);
64 "Adding block map for size of %u granules (%u bytes)\n",
65 (unsigned)granules, (unsigned)GRANULES_TO_BYTES(granules));
67 for (displ = 0; displ < BYTES_TO_GRANULES(HBLKSIZE); displ++) {
68 new_map[displ] = 1; /* Nonzero to get us out of marker fast path. */
71 for (displ = 0; displ < BYTES_TO_GRANULES(HBLKSIZE); displ++) {
72 new_map[displ] = (unsigned short)(displ % granules);
75 GC_obj_map[granules] = new_map;
78 #endif /* MARK_BIT_PER_GRANULE */
80 GC_INNER void GC_initialize_offsets(void)
83 if (GC_all_interior_pointers) {
84 for (i = 0; i < VALID_OFFSET_SZ; ++i)
85 GC_valid_offsets[i] = TRUE;
87 BZERO(GC_valid_offsets, sizeof(GC_valid_offsets));
88 for (i = 0; i < sizeof(word); ++i)
89 GC_modws_valid_offsets[i] = FALSE;