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obj_map.c    91 lines (81 with data), 3.0 kB

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/*
* Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
* Copyright (c) 1991, 1992 by Xerox Corporation. All rights reserved.
* Copyright (c) 1999-2001 by Hewlett-Packard Company. All rights reserved.
*
* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
*
* Permission is hereby granted to use or copy this program
* for any purpose, provided the above notices are retained on all copies.
* Permission to modify the code and to distribute modified code is granted,
* provided the above notices are retained, and a notice that the code was
* modified is included with the above copyright notice.
*/
#include "private/gc_priv.h"
/* Routines for maintaining maps describing heap block
* layouts for various object sizes. Allows fast pointer validity checks
* and fast location of object start locations on machines (such as SPARC)
* with slow division.
*/
/* Consider pointers that are offset bytes displaced from the beginning */
/* of an object to be valid. */
GC_API void GC_CALL GC_register_displacement(size_t offset)
{
DCL_LOCK_STATE;
LOCK();
GC_register_displacement_inner(offset);
UNLOCK();
}
GC_INNER void GC_register_displacement_inner(size_t offset)
{
if (offset >= VALID_OFFSET_SZ) {
ABORT("Bad argument to GC_register_displacement");
}
if (!GC_valid_offsets[offset]) {
GC_valid_offsets[offset] = TRUE;
GC_modws_valid_offsets[offset % sizeof(word)] = TRUE;
}
}
#ifdef MARK_BIT_PER_GRANULE
/* Add a heap block map for objects of size granules to obj_map. */
/* Return FALSE on failure. */
/* A size of 0 granules is used for large objects. */
GC_INNER GC_bool GC_add_map_entry(size_t granules)
{
unsigned displ;
short * new_map;
if (granules > BYTES_TO_GRANULES(MAXOBJBYTES)) granules = 0;
if (GC_obj_map[granules] != 0) {
return(TRUE);
}
new_map = (short *)GC_scratch_alloc(MAP_LEN * sizeof(short));
if (new_map == 0) return(FALSE);
if (GC_print_stats)
GC_log_printf("Adding block map for size of %u granules (%u bytes)\n",
(unsigned)granules, (unsigned)(GRANULES_TO_BYTES(granules)));
if (granules == 0) {
for (displ = 0; displ < BYTES_TO_GRANULES(HBLKSIZE); displ++) {
new_map[displ] = 1; /* Nonzero to get us out of marker fast path. */
}
} else {
for (displ = 0; displ < BYTES_TO_GRANULES(HBLKSIZE); displ++) {
new_map[displ] = (short)(displ % granules);
}
}
GC_obj_map[granules] = new_map;
return(TRUE);
}
#endif
GC_INNER void GC_initialize_offsets(void)
{
int i;
if (GC_all_interior_pointers) {
for (i = 0; i < VALID_OFFSET_SZ; ++i)
GC_valid_offsets[i] = TRUE;
} else {
BZERO(GC_valid_offsets, sizeof(GC_valid_offsets));
for (i = 0; i < sizeof(word); ++i)
GC_modws_valid_offsets[i] = FALSE;
}
}