boehm-gc/headers.c

   1 /*
   2  * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
   3  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
   4  * Copyright (c) 1996 by Silicon Graphics.  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 /*
  17  * This implements:
  18  * 1. allocation of heap block headers
  19  * 2. A map from addresses to heap block addresses to heap block headers
  20  *
  21  * Access speed is crucial.  We implement an index structure based on a 2
  22  * level tree.
  23  */
  24
  25 # include "gc_priv.h"
  26
  27 bottom_index * GC_all_bottom_indices = 0;
  28
  29 /* Non-macro version of header location routine */
  30 hdr * GC_find_header(h)
  31 ptr_t h;
  32 {
  33 #   ifdef HASH_TL
  34         register hdr * result;
  35         GET_HDR(h, result);
  36         return(result);
  37 #   else
  38         return(HDR_INNER(h));
  39 #   endif
  40 }
  41
  42 /* Routines to dynamically allocate collector data structures that will */
  43 /* never be freed.                                                       */
  44
  45 static ptr_t scratch_free_ptr = 0;
  46
  47 ptr_t GC_scratch_end_ptr = 0;
  48
  49 ptr_t GC_scratch_last_end_ptr = 0;
  50                 /* End point of last obtained scratch area */
  51
  52 ptr_t GC_scratch_alloc(bytes)
  53 register word bytes;
  54 {
  55     register ptr_t result = scratch_free_ptr;
  56     register word bytes_needed = bytes;
  57
  58 #   ifdef ALIGN_DOUBLE
  59 #       define GRANULARITY (2 * sizeof(word))
  60 #   else
  61 #       define GRANULARITY sizeof(word)
  62 #   endif
  63     bytes += GRANULARITY-1;
  64     bytes &= ~(GRANULARITY-1);
  65     scratch_free_ptr += bytes;
  66     if (scratch_free_ptr <= GC_scratch_end_ptr) {
  67         return(result);
  68     }
  69     {
  70         word bytes_to_get = MINHINCR * HBLKSIZE;
  71
  72         if (bytes_to_get <= bytes) {
  73           /* Undo the damage, and get memory directly */
  74             bytes_to_get = bytes;
  75 #           ifdef USE_MMAP
  76                 bytes_to_get += GC_page_size - 1;
  77                 bytes_to_get &= ~(GC_page_size - 1);
  78 #           endif
  79             result = (ptr_t)GET_MEM(bytes_to_get);
  80             scratch_free_ptr -= bytes;
  81             GC_scratch_last_end_ptr = result + bytes;
  82             return(result);
  83         }
  84         result = (ptr_t)GET_MEM(bytes_to_get);
  85         if (result == 0) {
  86 #           ifdef PRINTSTATS
  87                 GC_printf0("Out of memory - trying to allocate less\n");
  88 #           endif
  89             scratch_free_ptr -= bytes;
  90             bytes_to_get = bytes;
  91 #           ifdef USE_MMAP
  92                 bytes_to_get += GC_page_size - 1;
  93                 bytes_to_get &= (GC_page_size - 1);
  94 #           endif
  95             return((ptr_t)GET_MEM(bytes_to_get));
  96         }
  97         scratch_free_ptr = result;
  98         GC_scratch_end_ptr = scratch_free_ptr + bytes_to_get;
  99         GC_scratch_last_end_ptr = GC_scratch_end_ptr;
 100         return(GC_scratch_alloc(bytes));
 101     }
 102 }
 103
 104 static hdr * hdr_free_list = 0;
 105
 106 /* Return an uninitialized header */
 107 static hdr * alloc_hdr()
 108 {
 109     register hdr * result;
 110
 111     if (hdr_free_list == 0) {
 112         result = (hdr *) GC_scratch_alloc((word)(sizeof(hdr)));
 113     } else {
 114         result = hdr_free_list;
 115         hdr_free_list = (hdr *) (result -> hb_next);
 116     }
 117     return(result);
 118 }
 119
 120 static void free_hdr(hhdr)
 121 hdr * hhdr;
 122 {
 123     hhdr -> hb_next = (struct hblk *) hdr_free_list;
 124     hdr_free_list = hhdr;
 125 }
 126
 127 void GC_init_headers()
 128 {
 129     register int i;
 130
 131     GC_all_nils = (bottom_index *)GC_scratch_alloc((word)sizeof(bottom_index));
 132     BZERO(GC_all_nils, sizeof(bottom_index));
 133     for (i = 0; i < TOP_SZ; i++) {
 134         GC_top_index[i] = GC_all_nils;
 135     }
 136 }
 137
 138 /* Make sure that there is a bottom level index block for address addr  */
 139 /* Return FALSE on failure.                                             */
 140 static GC_bool get_index(addr)
 141 register word addr;
 142 {
 143     register word hi =
 144                 (word)(addr) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
 145     register bottom_index * r;
 146     register bottom_index * p;
 147     register bottom_index ** prev;
 148 #   ifdef HASH_TL
 149       register unsigned i = TL_HASH(hi);
 150       register bottom_index * old;
 151
 152       old = p = GC_top_index[i];
 153       while(p != GC_all_nils) {
 154           if (p -> key == hi) return(TRUE);
 155           p = p -> hash_link;
 156       }
 157       r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
 158       if (r == 0) return(FALSE);
 159       BZERO(r, sizeof (bottom_index));
 160       r -> hash_link = old;
 161       GC_top_index[i] = r;
 162 #   else
 163       if (GC_top_index[hi] != GC_all_nils) return(TRUE);
 164       r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
 165       if (r == 0) return(FALSE);
 166       GC_top_index[hi] = r;
 167       BZERO(r, sizeof (bottom_index));
 168 # endif
 169     r -> key = hi;
 170     /* Add it to the list of bottom indices */
 171       prev = &GC_all_bottom_indices;
 172       while ((p = *prev) != 0 && p -> key < hi) prev = &(p -> asc_link);
 173       r -> asc_link = p;
 174       *prev = r;
 175     return(TRUE);
 176 }
 177
 178 /* Install a header for block h.  */
 179 /* The header is uninitialized.   */
 180 /* Returns FALSE on failure.      */
 181 GC_bool GC_install_header(h)
 182 register struct hblk * h;
 183 {
 184     hdr * result;
 185
 186     if (!get_index((word) h)) return(FALSE);
 187     result = alloc_hdr();
 188     SET_HDR(h, result);
 189     return(result != 0);
 190 }
 191
 192 /* Set up forwarding counts for block h of size sz */
 193 GC_bool GC_install_counts(h, sz)
 194 register struct hblk * h;
 195 register word sz; /* bytes */
 196 {
 197     register struct hblk * hbp;
 198     register int i;
 199
 200     for (hbp = h; (char *)hbp < (char *)h + sz; hbp += BOTTOM_SZ) {
 201         if (!get_index((word) hbp)) return(FALSE);
 202     }
 203     if (!get_index((word)h + sz - 1)) return(FALSE);
 204     for (hbp = h + 1; (char *)hbp < (char *)h + sz; hbp += 1) {
 205         i = HBLK_PTR_DIFF(hbp, h);
 206         SET_HDR(hbp, (hdr *)(i > MAX_JUMP? MAX_JUMP : i));
 207     }
 208     return(TRUE);
 209 }
 210
 211 /* Remove the header for block h */
 212 void GC_remove_header(h)
 213 register struct hblk * h;
 214 {
 215     hdr ** ha;
 216
 217     GET_HDR_ADDR(h, ha);
 218     free_hdr(*ha);
 219     *ha = 0;
 220 }
 221
 222 /* Remove forwarding counts for h */
 223 void GC_remove_counts(h, sz)
 224 register struct hblk * h;
 225 register word sz; /* bytes */
 226 {
 227     register struct hblk * hbp;
 228
 229     for (hbp = h+1; (char *)hbp < (char *)h + sz; hbp += 1) {
 230         SET_HDR(hbp, 0);
 231     }
 232 }
 233
 234 /* Apply fn to all allocated blocks */
 235 /*VARARGS1*/
 236 void GC_apply_to_all_blocks(fn, client_data)
 237 void (*fn)(/* struct hblk *h, word client_data */);
 238 word client_data;
 239 {
 240     register int j;
 241     register bottom_index * index_p;
 242
 243     for (index_p = GC_all_bottom_indices; index_p != 0;
 244          index_p = index_p -> asc_link) {
 245         for (j = BOTTOM_SZ-1; j >= 0;) {
 246             if (!IS_FORWARDING_ADDR_OR_NIL(index_p->index[j])) {
 247                 if (index_p->index[j]->hb_map != GC_invalid_map) {
 248                     (*fn)(((struct hblk *)
 249                               (((index_p->key << LOG_BOTTOM_SZ) + (word)j)
 250                                << LOG_HBLKSIZE)),
 251                           client_data);
 252                 }
 253                 j--;
 254              } else if (index_p->index[j] == 0) {
 255                 j--;
 256              } else {
 257                 j -= (word)(index_p->index[j]);
 258              }
 259          }
 260      }
 261 }
 262
 263 /* Get the next valid block whose address is at least h */
 264 /* Return 0 if there is none.                           */
 265 struct hblk * GC_next_block(h)
 266 struct hblk * h;
 267 {
 268     register bottom_index * bi;
 269     register word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
 270
 271     GET_BI(h, bi);
 272     if (bi == GC_all_nils) {
 273         register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
 274         bi = GC_all_bottom_indices;
 275         while (bi != 0 && bi -> key < hi) bi = bi -> asc_link;
 276         j = 0;
 277     }
 278     while(bi != 0) {
 279         while (j < BOTTOM_SZ) {
 280             if (IS_FORWARDING_ADDR_OR_NIL(bi -> index[j])) {
 281                 j++;
 282             } else {
 283                 if (bi->index[j]->hb_map != GC_invalid_map) {
 284                     return((struct hblk *)
 285                               (((bi -> key << LOG_BOTTOM_SZ) + j)
 286                                << LOG_HBLKSIZE));
 287                 } else {
 288                     j += divHBLKSZ(bi->index[j] -> hb_sz);
 289                 }
 290             }
 291         }
 292         j = 0;
 293         bi = bi -> asc_link;
 294     }
 295     return(0);
 296 }