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                                 /* Pointer to first (lowest addr) */
  29                                 /* bottom_index.                  */
  30
  31 bottom_index * GC_all_bottom_indices_end = 0;
  32                                 /* Pointer to last (highest addr) */
  33                                 /* bottom_index.                  */
  34
  35 /* Non-macro version of header location routine */
  36 hdr * GC_find_header(h)
  37 ptr_t h;
  38 {
  39 #   ifdef HASH_TL
  40         register hdr * result;
  41         GET_HDR(h, result);
  42         return(result);
  43 #   else
  44         return(HDR_INNER(h));
  45 #   endif
  46 }
  47
  48 /* Routines to dynamically allocate collector data structures that will */
  49 /* never be freed.                                                       */
  50
  51 static ptr_t scratch_free_ptr = 0;
  52
  53 ptr_t GC_scratch_end_ptr = 0;
  54
  55 ptr_t GC_scratch_last_end_ptr = 0;
  56                 /* End point of last obtained scratch area */
  57
  58 ptr_t GC_scratch_alloc(bytes)
  59 register word bytes;
  60 {
  61     register ptr_t result = scratch_free_ptr;
  62
  63 #   ifdef ALIGN_DOUBLE
  64 #       define GRANULARITY (2 * sizeof(word))
  65 #   else
  66 #       define GRANULARITY sizeof(word)
  67 #   endif
  68     bytes += GRANULARITY-1;
  69     bytes &= ~(GRANULARITY-1);
  70     scratch_free_ptr += bytes;
  71     if (scratch_free_ptr <= GC_scratch_end_ptr) {
  72         return(result);
  73     }
  74     {
  75         word bytes_to_get = MINHINCR * HBLKSIZE;
  76
  77         if (bytes_to_get <= bytes) {
  78           /* Undo the damage, and get memory directly */
  79             bytes_to_get = bytes;
  80 #           ifdef USE_MMAP
  81                 bytes_to_get += GC_page_size - 1;
  82                 bytes_to_get &= ~(GC_page_size - 1);
  83 #           endif
  84             result = (ptr_t)GET_MEM(bytes_to_get);
  85             scratch_free_ptr -= bytes;
  86             GC_scratch_last_end_ptr = result + bytes;
  87             return(result);
  88         }
  89         result = (ptr_t)GET_MEM(bytes_to_get);
  90         if (result == 0) {
  91 #           ifdef PRINTSTATS
  92                 GC_printf0("Out of memory - trying to allocate less\n");
  93 #           endif
  94             scratch_free_ptr -= bytes;
  95             bytes_to_get = bytes;
  96 #           ifdef USE_MMAP
  97                 bytes_to_get += GC_page_size - 1;
  98                 bytes_to_get &= ~(GC_page_size - 1);
  99 #           endif
 100             return((ptr_t)GET_MEM(bytes_to_get));
 101         }
 102         scratch_free_ptr = result;
 103         GC_scratch_end_ptr = scratch_free_ptr + bytes_to_get;
 104         GC_scratch_last_end_ptr = GC_scratch_end_ptr;
 105         return(GC_scratch_alloc(bytes));
 106     }
 107 }
 108
 109 static hdr * hdr_free_list = 0;
 110
 111 /* Return an uninitialized header */
 112 static hdr * alloc_hdr()
 113 {
 114     register hdr * result;
 115
 116     if (hdr_free_list == 0) {
 117         result = (hdr *) GC_scratch_alloc((word)(sizeof(hdr)));
 118     } else {
 119         result = hdr_free_list;
 120         hdr_free_list = (hdr *) (result -> hb_next);
 121     }
 122     return(result);
 123 }
 124
 125 static void free_hdr(hhdr)
 126 hdr * hhdr;
 127 {
 128     hhdr -> hb_next = (struct hblk *) hdr_free_list;
 129     hdr_free_list = hhdr;
 130 }
 131
 132 void GC_init_headers()
 133 {
 134     register unsigned i;
 135
 136     GC_all_nils = (bottom_index *)GC_scratch_alloc((word)sizeof(bottom_index));
 137     BZERO(GC_all_nils, sizeof(bottom_index));
 138     for (i = 0; i < TOP_SZ; i++) {
 139         GC_top_index[i] = GC_all_nils;
 140     }
 141 }
 142
 143 /* Make sure that there is a bottom level index block for address addr  */
 144 /* Return FALSE on failure.                                             */
 145 static GC_bool get_index(addr)
 146 word addr;
 147 {
 148     word hi = (word)(addr) >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
 149     bottom_index * r;
 150     bottom_index * p;
 151     bottom_index ** prev;
 152     bottom_index *pi;
 153
 154 #   ifdef HASH_TL
 155       unsigned i = TL_HASH(hi);
 156       bottom_index * old;
 157
 158       old = p = GC_top_index[i];
 159       while(p != GC_all_nils) {
 160           if (p -> key == hi) return(TRUE);
 161           p = p -> hash_link;
 162       }
 163       r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
 164       if (r == 0) return(FALSE);
 165       BZERO(r, sizeof (bottom_index));
 166       r -> hash_link = old;
 167       GC_top_index[i] = r;
 168 #   else
 169       if (GC_top_index[hi] != GC_all_nils) return(TRUE);
 170       r = (bottom_index*)GC_scratch_alloc((word)(sizeof (bottom_index)));
 171       if (r == 0) return(FALSE);
 172       GC_top_index[hi] = r;
 173       BZERO(r, sizeof (bottom_index));
 174 #   endif
 175     r -> key = hi;
 176     /* Add it to the list of bottom indices */
 177       prev = &GC_all_bottom_indices;    /* pointer to p */
 178       pi = 0;                           /* bottom_index preceding p */
 179       while ((p = *prev) != 0 && p -> key < hi) {
 180         pi = p;
 181         prev = &(p -> asc_link);
 182       }
 183       r -> desc_link = pi;
 184       if (0 == p) {
 185         GC_all_bottom_indices_end = r;
 186       } else {
 187         p -> desc_link = r;
 188       }
 189       r -> asc_link = p;
 190       *prev = r;
 191     return(TRUE);
 192 }
 193
 194 /* Install a header for block h.  */
 195 /* The header is uninitialized.   */
 196 /* Returns FALSE on failure.      */
 197 GC_bool GC_install_header(h)
 198 register struct hblk * h;
 199 {
 200     hdr * result;
 201
 202     if (!get_index((word) h)) return(FALSE);
 203     result = alloc_hdr();
 204     SET_HDR(h, result);
 205 #   ifdef USE_MUNMAP
 206         result -> hb_last_reclaimed = GC_gc_no;
 207 #   endif
 208     return(result != 0);
 209 }
 210
 211 /* Set up forwarding counts for block h of size sz */
 212 GC_bool GC_install_counts(h, sz)
 213 register struct hblk * h;
 214 register word sz; /* bytes */
 215 {
 216     register struct hblk * hbp;
 217     register int i;
 218
 219     for (hbp = h; (char *)hbp < (char *)h + sz; hbp += BOTTOM_SZ) {
 220         if (!get_index((word) hbp)) return(FALSE);
 221     }
 222     if (!get_index((word)h + sz - 1)) return(FALSE);
 223     for (hbp = h + 1; (char *)hbp < (char *)h + sz; hbp += 1) {
 224         i = HBLK_PTR_DIFF(hbp, h);
 225         SET_HDR(hbp, (hdr *)(i > MAX_JUMP? MAX_JUMP : i));
 226     }
 227     return(TRUE);
 228 }
 229
 230 /* Remove the header for block h */
 231 void GC_remove_header(h)
 232 register struct hblk * h;
 233 {
 234     hdr ** ha;
 235
 236     GET_HDR_ADDR(h, ha);
 237     free_hdr(*ha);
 238     *ha = 0;
 239 }
 240
 241 /* Remove forwarding counts for h */
 242 void GC_remove_counts(h, sz)
 243 register struct hblk * h;
 244 register word sz; /* bytes */
 245 {
 246     register struct hblk * hbp;
 247
 248     for (hbp = h+1; (char *)hbp < (char *)h + sz; hbp += 1) {
 249         SET_HDR(hbp, 0);
 250     }
 251 }
 252
 253 /* Apply fn to all allocated blocks */
 254 /*VARARGS1*/
 255 void GC_apply_to_all_blocks(fn, client_data)
 256 void (*fn)(/* struct hblk *h, word client_data */);
 257 word client_data;
 258 {
 259     register int j;
 260     register bottom_index * index_p;
 261
 262     for (index_p = GC_all_bottom_indices; index_p != 0;
 263          index_p = index_p -> asc_link) {
 264         for (j = BOTTOM_SZ-1; j >= 0;) {
 265             if (!IS_FORWARDING_ADDR_OR_NIL(index_p->index[j])) {
 266                 if (index_p->index[j]->hb_map != GC_invalid_map) {
 267                     (*fn)(((struct hblk *)
 268                               (((index_p->key << LOG_BOTTOM_SZ) + (word)j)
 269                                << LOG_HBLKSIZE)),
 270                           client_data);
 271                 }
 272                 j--;
 273              } else if (index_p->index[j] == 0) {
 274                 j--;
 275              } else {
 276                 j -= (word)(index_p->index[j]);
 277              }
 278          }
 279      }
 280 }
 281
 282 /* Get the next valid block whose address is at least h */
 283 /* Return 0 if there is none.                           */
 284 struct hblk * GC_next_used_block(h)
 285 struct hblk * h;
 286 {
 287     register bottom_index * bi;
 288     register word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
 289
 290     GET_BI(h, bi);
 291     if (bi == GC_all_nils) {
 292         register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
 293         bi = GC_all_bottom_indices;
 294         while (bi != 0 && bi -> key < hi) bi = bi -> asc_link;
 295         j = 0;
 296     }
 297     while(bi != 0) {
 298         while (j < BOTTOM_SZ) {
 299             hdr * hhdr = bi -> index[j];
 300             if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
 301                 j++;
 302             } else {
 303                 if (hhdr->hb_map != GC_invalid_map) {
 304                     return((struct hblk *)
 305                               (((bi -> key << LOG_BOTTOM_SZ) + j)
 306                                << LOG_HBLKSIZE));
 307                 } else {
 308                     j += divHBLKSZ(hhdr -> hb_sz);
 309                 }
 310             }
 311         }
 312         j = 0;
 313         bi = bi -> asc_link;
 314     }
 315     return(0);
 316 }
 317
 318 /* Get the last (highest address) block whose address is        */
 319 /* at most h.  Return 0 if there is none.                       */
 320 /* Unlike the above, this may return a free block.              */
 321 struct hblk * GC_prev_block(h)
 322 struct hblk * h;
 323 {
 324     register bottom_index * bi;
 325     register signed_word j = ((word)h >> LOG_HBLKSIZE) & (BOTTOM_SZ-1);
 326
 327     GET_BI(h, bi);
 328     if (bi == GC_all_nils) {
 329         register word hi = (word)h >> (LOG_BOTTOM_SZ + LOG_HBLKSIZE);
 330         bi = GC_all_bottom_indices_end;
 331         while (bi != 0 && bi -> key > hi) bi = bi -> desc_link;
 332         j = BOTTOM_SZ - 1;
 333     }
 334     while(bi != 0) {
 335         while (j >= 0) {
 336             hdr * hhdr = bi -> index[j];
 337             if (0 == hhdr) {
 338                 --j;
 339             } else if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
 340                 j -= (signed_word)hhdr;
 341             } else {
 342                 return((struct hblk *)
 343                           (((bi -> key << LOG_BOTTOM_SZ) + j)
 344                                << LOG_HBLKSIZE));
 345             }
 346         }
 347         j = BOTTOM_SZ - 1;
 348         bi = bi -> desc_link;
 349     }
 350     return(0);
 351 }