Synopsis - Cross-Reference

 1/* 
 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.
 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/* Routines for maintaining maps describing heap block
17 * layouts for various object sizes.  Allows fast pointer validity checks
18 * and fast location of object start locations on machines (such as SPARC)
19 * with slow division.
20 */
21 
22# include "private/gc_priv.h"
23
24/* Consider pointers that are offset bytes displaced from the beginning */
25/* of an object to be valid.                                            */
26
27void GC_register_displacement(size_t offset)
28{
29    DCL_LOCK_STATE;
30    
31    LOCK();
32    GC_register_displacement_inner(offset);
33    UNLOCK();
34}
35
36void GC_register_displacement_inner(size_t offset) 
37{
38    if (offset >= VALID_OFFSET_SZ) {
39        ABORT("Bad argument to GC_register_displacement");
40    }
41    if (!GC_valid_offsets[offset]) {
42      GC_valid_offsets[offset] = TRUE;
43      GC_modws_valid_offsets[offset % sizeof(word)] = TRUE;
44    }
45}
46
47#ifdef MARK_BIT_PER_GRANULE
48/* Add a heap block map for objects of size granules to obj_map.	*/
49/* Return FALSE on failure.						*/
50/* A size of 0 granules is used for large objects.			*/
51GC_bool GC_add_map_entry(size_t granules)
52{
53    unsigned displ;
54    short * new_map;
55    
56    if (granules > BYTES_TO_GRANULES(MAXOBJBYTES)) granules = 0;
57    if (GC_obj_map[granules] != 0) {
58        return(TRUE);
59    }
60    new_map = (short *)GC_scratch_alloc(MAP_LEN * sizeof(short));
61    if (new_map == 0) return(FALSE);
62    if (GC_print_stats)
63        GC_printf("Adding block map for size of %u granules (%u bytes)\n",
64		  (unsigned)granules, (unsigned)(GRANULES_TO_BYTES(granules)));
65    if (granules == 0) {
66      for (displ = 0; displ < BYTES_TO_GRANULES(HBLKSIZE); displ++) {
67        new_map[displ] = 1;  /* Nonzero to get us out of marker fast path. */
68      }
69    } else {
70      for (displ = 0; displ < BYTES_TO_GRANULES(HBLKSIZE); displ++) {
71	new_map[displ] = (short)(displ % granules);
72      }
73    }
74    GC_obj_map[granules] = new_map;
75    return(TRUE);
76}
77#endif
78
79static GC_bool offsets_initialized = FALSE;
80
81void GC_initialize_offsets(void)
82{
83    if (!offsets_initialized) {
84      int i;
85      if (GC_all_interior_pointers) {
86	for (i = 0; i < VALID_OFFSET_SZ; ++i) GC_valid_offsets[i] = TRUE;
87      }
88      offsets_initialized = TRUE;
89    }
90}