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 GC_register_displacement(size_t offset)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 GC_register_displacement_inner(size_t offset)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. */ GC_add_map_entry(size_t granules)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 79 static GC_bool offsets_initialized = FALSE; 80 GC_initialize_offsets(void)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 } 91