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721 |
jeremybenn |
/*
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* Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
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* Copyright (c) 1991, 1992 by Xerox Corporation. All rights reserved.
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* Copyright (c) 1999-2001 by Hewlett-Packard Company. All rights reserved.
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*
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* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
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* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
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*
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* Permission is hereby granted to use or copy this program
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* for any purpose, provided the above notices are retained on all copies.
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* Permission to modify the code and to distribute modified code is granted,
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* provided the above notices are retained, and a notice that the code was
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* modified is included with the above copyright notice.
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*/
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/* Routines for maintaining maps describing heap block
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* layouts for various object sizes. Allows fast pointer validity checks
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* and fast location of object start locations on machines (such as SPARC)
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* with slow division.
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*/
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# include "private/gc_priv.h"
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map_entry_type * GC_invalid_map = 0;
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/* Invalidate the object map associated with a block. Free blocks */
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/* are identified by invalid maps. */
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void GC_invalidate_map(hhdr)
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hdr *hhdr;
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{
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register int displ;
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if (GC_invalid_map == 0) {
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GC_invalid_map = (map_entry_type *)GC_scratch_alloc(MAP_SIZE);
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if (GC_invalid_map == 0) {
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GC_err_printf0(
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"Cant initialize GC_invalid_map: insufficient memory\n");
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EXIT();
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}
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for (displ = 0; displ < HBLKSIZE; displ++) {
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MAP_ENTRY(GC_invalid_map, displ) = OBJ_INVALID;
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}
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}
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hhdr -> hb_map = GC_invalid_map;
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}
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/* Consider pointers that are offset bytes displaced from the beginning */
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/* of an object to be valid. */
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# if defined(__STDC__) || defined(__cplusplus)
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void GC_register_displacement(GC_word offset)
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# else
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void GC_register_displacement(offset)
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GC_word offset;
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# endif
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{
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DCL_LOCK_STATE;
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DISABLE_SIGNALS();
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LOCK();
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GC_register_displacement_inner(offset);
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UNLOCK();
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ENABLE_SIGNALS();
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}
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void GC_register_displacement_inner(offset)
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word offset;
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{
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register unsigned i;
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word map_entry = BYTES_TO_WORDS(offset);
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if (offset >= VALID_OFFSET_SZ) {
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ABORT("Bad argument to GC_register_displacement");
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}
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if (map_entry > MAX_OFFSET) map_entry = OFFSET_TOO_BIG;
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if (!GC_valid_offsets[offset]) {
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GC_valid_offsets[offset] = TRUE;
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GC_modws_valid_offsets[offset % sizeof(word)] = TRUE;
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if (!GC_all_interior_pointers) {
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for (i = 0; i <= MAXOBJSZ; i++) {
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if (GC_obj_map[i] != 0) {
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if (i == 0) {
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GC_obj_map[i][offset] = (map_entry_type)map_entry;
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} else {
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register unsigned j;
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register unsigned lb = WORDS_TO_BYTES(i);
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if (offset < lb) {
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for (j = offset; j < HBLKSIZE; j += lb) {
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GC_obj_map[i][j] = (map_entry_type)map_entry;
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}
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}
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}
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}
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}
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}
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}
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}
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/* Add a heap block map for objects of size sz to obj_map. */
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/* Return FALSE on failure. */
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GC_bool GC_add_map_entry(sz)
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word sz;
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{
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register unsigned obj_start;
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register unsigned displ;
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register map_entry_type * new_map;
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word map_entry;
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if (sz > MAXOBJSZ) sz = 0;
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if (GC_obj_map[sz] != 0) {
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return(TRUE);
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}
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new_map = (map_entry_type *)GC_scratch_alloc(MAP_SIZE);
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if (new_map == 0) return(FALSE);
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# ifdef PRINTSTATS
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GC_printf1("Adding block map for size %lu\n", (unsigned long)sz);
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# endif
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for (displ = 0; displ < HBLKSIZE; displ++) {
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MAP_ENTRY(new_map,displ) = OBJ_INVALID;
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}
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if (sz == 0) {
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for(displ = 0; displ <= HBLKSIZE; displ++) {
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if (OFFSET_VALID(displ)) {
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map_entry = BYTES_TO_WORDS(displ);
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if (map_entry > MAX_OFFSET) map_entry = OFFSET_TOO_BIG;
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MAP_ENTRY(new_map,displ) = (map_entry_type)map_entry;
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}
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}
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} else {
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for (obj_start = 0;
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obj_start + WORDS_TO_BYTES(sz) <= HBLKSIZE;
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obj_start += WORDS_TO_BYTES(sz)) {
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for (displ = 0; displ < WORDS_TO_BYTES(sz); displ++) {
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if (OFFSET_VALID(displ)) {
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map_entry = BYTES_TO_WORDS(displ);
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if (map_entry > MAX_OFFSET) map_entry = OFFSET_TOO_BIG;
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MAP_ENTRY(new_map, obj_start + displ) =
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(map_entry_type)map_entry;
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}
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}
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}
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}
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GC_obj_map[sz] = new_map;
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return(TRUE);
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}
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