src/runtime/purify.c

   1 /*
   2  * C-level stuff to implement Lisp-level PURIFY
   3  */
   4
   5 /*
   6  * This software is part of the SBCL system. See the README file for
   7  * more information.
   8  *
   9  * This software is derived from the CMU CL system, which was
  10  * written at Carnegie Mellon University and released into the
  11  * public domain. The software is in the public domain and is
  12  * provided with absolutely no warranty. See the COPYING and CREDITS
  13  * files for more information.
  14  */
  15
  16 #include <stdio.h>
  17 #include <sys/types.h>
  18 #include <stdlib.h>
  19 #include <strings.h>
  20 #include <errno.h>
  21
  22 #include "sbcl.h"
  23 #include "runtime.h"
  24 #include "os.h"
  25 #include "globals.h"
  26 #include "validate.h"
  27 #include "interrupt.h"
  28 #include "purify.h"
  29 #include "interr.h"
  30 #include "gc.h"
  31 #include "gc-internal.h"
  32 #include "thread.h"
  33 #include "genesis/gc-tables.h"
  34 #include "genesis/primitive-objects.h"
  35 #include "genesis/static-symbols.h"
  36 #include "genesis/layout.h"
  37 #include "genesis/defstruct-description.h"
  38 #include "genesis/hash-table.h"
  39 #include "gencgc.h"
  40
  41 /* We don't ever do purification with GENCGC as of 1.0.5.*. There was
  42  * a lot of hairy and fragile ifdeffage in here to support purify on
  43  * x86oids, which has now been removed. So this code can't even be
  44  * compiled with GENCGC any more.  -- JES, 2007-04-30.
  45  */
  46 #ifndef LISP_FEATURE_GENCGC
  47
  48 #define PRINTNOISE
  49
  50 static lispobj *dynamic_space_purify_pointer;
  51
  52 \f
  53 /* These hold the original end of the read_only and static spaces so
  54  * we can tell what are forwarding pointers. */
  55
  56 static lispobj *read_only_end, *static_end;
  57
  58 /* These are private to purify, not to be confused with the external symbols
  59  * named 'read_only_space_free_pointer', respectively 'static_space' */
  60 static lispobj *read_only_free, *static_free;
  61
  62 static lispobj *pscav(lispobj *addr, long nwords, boolean constant);
  63
  64 #define LATERBLOCKSIZE 1020
  65 #define LATERMAXCOUNT 10
  66
  67 static struct
  68 later {
  69     struct later *next;
  70     union {
  71         lispobj *ptr;
  72         long count;
  73     } u[LATERBLOCKSIZE];
  74 } *later_blocks = NULL;
  75 static long later_count = 0;
  76
  77 \f
  78 static boolean
  79 forwarding_pointer_p(lispobj obj)
  80 {
  81     lispobj *ptr = native_pointer(obj);
  82
  83     return ((static_end <= ptr && ptr <= static_free) ||
  84             (read_only_end <= ptr && ptr <= read_only_free));
  85 }
  86
  87 static boolean
  88 dynamic_pointer_p(lispobj ptr)
  89 {
  90     return (ptr >= (lispobj)current_dynamic_space
  91             &&
  92             ptr < (lispobj)dynamic_space_purify_pointer);
  93 }
  94
  95 static inline lispobj *
  96 newspace_alloc(long nwords, int constantp)
  97 {
  98     lispobj *ret;
  99     gc_assert((nwords & 1) == 0);
 100     if(constantp) {
 101         if(read_only_free + nwords >= (lispobj *)READ_ONLY_SPACE_END) {
 102             lose("Ran out of read-only space while purifying!\n");
 103         }
 104         ret=read_only_free;
 105         read_only_free+=nwords;
 106     } else {
 107         if(static_free + nwords >= (lispobj *)STATIC_SPACE_END) {
 108             lose("Ran out of static space while purifying!\n");
 109         }
 110         ret=static_free;
 111         static_free+=nwords;
 112     }
 113     return ret;
 114 }
 115
 116 \f
 117 static void
 118 pscav_later(lispobj *where, long count)
 119 {
 120     struct later *new;
 121
 122     if (count > LATERMAXCOUNT) {
 123         while (count > LATERMAXCOUNT) {
 124             pscav_later(where, LATERMAXCOUNT);
 125             count -= LATERMAXCOUNT;
 126             where += LATERMAXCOUNT;
 127         }
 128     }
 129     else {
 130         if (later_blocks == NULL || later_count == LATERBLOCKSIZE ||
 131             (later_count == LATERBLOCKSIZE-1 && count > 1)) {
 132             new  = (struct later *)malloc(sizeof(struct later));
 133             new->next = later_blocks;
 134             if (later_blocks && later_count < LATERBLOCKSIZE)
 135                 later_blocks->u[later_count].ptr = NULL;
 136             later_blocks = new;
 137             later_count = 0;
 138         }
 139
 140         if (count != 1)
 141             later_blocks->u[later_count++].count = count;
 142         later_blocks->u[later_count++].ptr = where;
 143     }
 144 }
 145
 146 static lispobj
 147 ptrans_boxed(lispobj thing, lispobj header, boolean constant)
 148 {
 149     /* Allocate it */
 150     lispobj *old = native_pointer(thing);
 151     long nwords = sizetab[widetag_of(header)](old);
 152     lispobj *new = newspace_alloc(nwords,constant);
 153
 154     /* Copy it. */
 155     bcopy(old, new, nwords * sizeof(lispobj));
 156
 157     /* Deposit forwarding pointer. */
 158     lispobj result = make_lispobj(new, lowtag_of(thing));
 159     *old = result;
 160
 161     /* Scavenge it. */
 162     pscav(new, nwords, constant);
 163
 164     return result;
 165 }
 166
 167 /* We need to look at the layout to see whether it is a pure structure
 168  * class, and only then can we transport as constant. If it is pure,
 169  * we can ALWAYS transport as a constant. */
 170 static lispobj
 171 ptrans_instance(lispobj thing, lispobj header, boolean /* ignored */ constant)
 172 {
 173     constant = 0;
 174     lispobj info = LAYOUT(instance_layout(native_pointer(thing)))->info;
 175     if (info != NIL) {
 176         lispobj pure = ((struct defstruct_description*)native_pointer(info))->pure;
 177         if (pure != NIL && pure != T) {
 178             gc_abort();
 179             return NIL; /* dummy value: return something ... */
 180         }
 181         constant = (pure == T);
 182     }
 183     return ptrans_boxed(thing, header, constant);
 184 }
 185
 186 static lispobj
 187 ptrans_fdefn(lispobj thing, lispobj header)
 188 {
 189     /* Allocate it */
 190     lispobj *old = native_pointer(thing);
 191     long nwords = sizetab[widetag_of(header)](old);
 192     lispobj *new = newspace_alloc(nwords, 0);    /* inconstant */
 193
 194     /* Copy it. */
 195     bcopy(old, new, nwords * sizeof(lispobj));
 196
 197     /* Deposit forwarding pointer. */
 198     lispobj result = make_lispobj(new, lowtag_of(thing));
 199     *old = result;
 200
 201     /* Scavenge the function. */
 202     struct fdefn *fdefn = (struct fdefn *)new;
 203     lispobj oldfn = fdefn->fun;
 204     pscav(&fdefn->fun, 1, 0);
 205     if ((char *)oldfn + FUN_RAW_ADDR_OFFSET == fdefn->raw_addr)
 206         fdefn->raw_addr = (char *)fdefn->fun + FUN_RAW_ADDR_OFFSET;
 207
 208     return result;
 209 }
 210
 211 static lispobj
 212 ptrans_unboxed(lispobj thing, lispobj header)
 213 {
 214     /* Allocate it */
 215     lispobj *old = native_pointer(thing);
 216     long nwords = sizetab[widetag_of(header)](old);
 217     lispobj *new = newspace_alloc(nwords, 1);     /* always constant */
 218
 219     /* copy it. */
 220     bcopy(old, new, nwords * sizeof(lispobj));
 221
 222     /* Deposit forwarding pointer. */
 223     lispobj result = make_lispobj(new, lowtag_of(thing));
 224     *old = result;
 225
 226     return result;
 227 }
 228
 229 static lispobj
 230 ptrans_vector(lispobj thing, boolean boxed, boolean constant)
 231 {
 232     struct vector *vector = VECTOR(thing);
 233     long nwords = sizetab[widetag_of(vector->header)]((lispobj*)vector);
 234
 235     lispobj *new = newspace_alloc(nwords, (constant || !boxed));
 236     bcopy(vector, new, nwords * sizeof(lispobj));
 237
 238     lispobj result = make_lispobj(new, lowtag_of(thing));
 239     vector->header = result;
 240
 241     if (boxed)
 242         pscav(new, nwords, constant);
 243
 244     return result;
 245 }
 246
 247 static lispobj
 248 ptrans_code(lispobj thing)
 249 {
 250     struct code *code = (struct code *)native_pointer(thing);
 251     long nwords = code_header_words(code->header)
 252                 + code_instruction_words(code->code_size);
 253
 254     struct code *new = (struct code *)newspace_alloc(nwords,1); /* constant */
 255
 256     bcopy(code, new, nwords * sizeof(lispobj));
 257
 258     lispobj result = make_lispobj(new, OTHER_POINTER_LOWTAG);
 259
 260     /* Put in forwarding pointers for all the functions. */
 261     uword_t displacement = result - thing;
 262     for_each_simple_fun(i, newfunc, new, 1, {
 263         lispobj* old = (lispobj*)LOW_WORD((char*)newfunc - displacement);
 264         *old = make_lispobj(newfunc, FUN_POINTER_LOWTAG);
 265     });
 266
 267     /* Stick in a forwarding pointer for the code object. */
 268     /* This smashes the header, so do it only after reading n_funs */
 269     *(lispobj *)code = result;
 270
 271     /* Arrange to scavenge the debug info later. */
 272     pscav_later(&new->debug_info, 1);
 273
 274     /* Scavenge the constants. */
 275     pscav(new->constants,
 276           code_header_words(new->header) - (offsetof(struct code, constants) >> WORD_SHIFT),
 277           1);
 278
 279     /* Scavenge all the functions. */
 280     for_each_simple_fun(i, func, new, 1, {
 281         gc_assert(!dynamic_pointer_p((lispobj)func));
 282         pscav(&func->self, 1, 1);
 283         pscav_later(&func->name, 4);
 284     })
 285
 286     return result;
 287 }
 288
 289 static lispobj
 290 ptrans_func(lispobj thing, lispobj header)
 291 {
 292     /* Thing can either be a function header,
 293      * a closure, or a funcallable-instance. If it's a closure
 294      * or a funcallable-instance, we do the same as ptrans_boxed.
 295      * Otherwise we have to do something strange, 'cause it is buried
 296      * inside a code object. */
 297
 298     if (widetag_of(header) == SIMPLE_FUN_WIDETAG) {
 299
 300         /* We can only end up here if the code object has not been
 301          * scavenged, because if it had been scavenged, forwarding pointers
 302          * would have been left behind for all the entry points. */
 303
 304         struct simple_fun *function = (struct simple_fun *)native_pointer(thing);
 305         lispobj code = make_lispobj(native_pointer(thing) - HeaderValue(function->header),
 306                                     OTHER_POINTER_LOWTAG);
 307
 308         /* This will cause the function's header to be replaced with a
 309          * forwarding pointer. */
 310
 311         ptrans_code(code);
 312
 313         /* So we can just return that. */
 314         return function->header;
 315     } else {
 316         /* It's some kind of closure-like thing. */
 317         lispobj *old = native_pointer(thing);
 318         long nwords = sizetab[widetag_of(header)](old);
 319
 320         /* Allocate the new one.  FINs *must* not go in read_only
 321          * space.  Closures can; they never change */
 322
 323         lispobj *new = newspace_alloc
 324             (nwords,(widetag_of(header)!=FUNCALLABLE_INSTANCE_WIDETAG));
 325
 326         /* Copy it. */
 327         bcopy(old, new, nwords * sizeof(lispobj));
 328
 329         /* Deposit forwarding pointer. */
 330         lispobj result = make_lispobj(new, lowtag_of(thing));
 331         *old = result;
 332
 333         /* Scavenge it. */
 334         pscav(new, nwords, 0);
 335
 336         return result;
 337     }
 338 }
 339
 340 static lispobj
 341 ptrans_returnpc(lispobj thing, lispobj header)
 342 {
 343     /* Find the corresponding code object. */
 344     lispobj code = thing - HeaderValue(header)*sizeof(lispobj);
 345
 346     /* Make sure it's been transported. */
 347     lispobj new = *native_pointer(code);
 348     if (!forwarding_pointer_p(new))
 349         new = ptrans_code(code);
 350
 351     /* Maintain the offset: */
 352     return new + (thing - code);
 353 }
 354
 355 #define WORDS_PER_CONS CEILING(sizeof(struct cons) / sizeof(lispobj), 2)
 356
 357 static lispobj
 358 ptrans_list(lispobj thing, boolean constant)
 359 {
 360     struct cons *old, *new, *orig;
 361     long length;
 362
 363     orig = (struct cons *) newspace_alloc(0,constant);
 364     length = 0;
 365
 366     do {
 367         /* Allocate a new cons cell. */
 368         old = (struct cons *)native_pointer(thing);
 369         new = (struct cons *) newspace_alloc(WORDS_PER_CONS,constant);
 370
 371         /* Copy the cons cell and keep a pointer to the cdr. */
 372         new->car = old->car;
 373         thing = new->cdr = old->cdr;
 374
 375         /* Set up the forwarding pointer. */
 376         *(lispobj *)old = make_lispobj(new, LIST_POINTER_LOWTAG);
 377
 378         /* And count this cell. */
 379         length++;
 380     } while (lowtag_of(thing) == LIST_POINTER_LOWTAG &&
 381              dynamic_pointer_p(thing) &&
 382              !(forwarding_pointer_p(*native_pointer(thing))));
 383
 384     /* Scavenge the list we just copied. */
 385     pscav((lispobj *)orig, length * WORDS_PER_CONS, constant);
 386
 387     return make_lispobj(orig, LIST_POINTER_LOWTAG);
 388 }
 389
 390 static lispobj
 391 ptrans_otherptr(lispobj thing, lispobj header, boolean constant)
 392 {
 393     int widetag = widetag_of(header);
 394     switch (widetag) {
 395         /* FIXME: this needs a reindent */
 396       case BIGNUM_WIDETAG:
 397       case SINGLE_FLOAT_WIDETAG:
 398       case DOUBLE_FLOAT_WIDETAG:
 399 #ifdef LONG_FLOAT_WIDETAG
 400       case LONG_FLOAT_WIDETAG:
 401 #endif
 402 #ifdef COMPLEX_SINGLE_FLOAT_WIDETAG
 403       case COMPLEX_SINGLE_FLOAT_WIDETAG:
 404 #endif
 405 #ifdef COMPLEX_DOUBLE_FLOAT_WIDETAG
 406       case COMPLEX_DOUBLE_FLOAT_WIDETAG:
 407 #endif
 408 #ifdef COMPLEX_LONG_FLOAT_WIDETAG
 409       case COMPLEX_LONG_FLOAT_WIDETAG:
 410 #endif
 411       case SAP_WIDETAG:
 412           return ptrans_unboxed(thing, header);
 413       case RATIO_WIDETAG:
 414       case COMPLEX_WIDETAG:
 415       case SIMPLE_ARRAY_WIDETAG:
 416       case COMPLEX_BASE_STRING_WIDETAG:
 417 #ifdef COMPLEX_CHARACTER_STRING_WIDETAG
 418     case COMPLEX_CHARACTER_STRING_WIDETAG:
 419 #endif
 420       case COMPLEX_BIT_VECTOR_WIDETAG:
 421       case COMPLEX_VECTOR_NIL_WIDETAG:
 422       case COMPLEX_VECTOR_WIDETAG:
 423       case COMPLEX_ARRAY_WIDETAG:
 424         return ptrans_boxed(thing, header, constant);
 425
 426       case VALUE_CELL_WIDETAG:
 427       case WEAK_POINTER_WIDETAG:
 428         return ptrans_boxed(thing, header, 0);
 429
 430       case SYMBOL_WIDETAG:
 431         return ptrans_boxed(thing, header, 0);
 432
 433       case SIMPLE_VECTOR_WIDETAG:
 434         return ptrans_vector(thing, 1, constant);
 435
 436       case CODE_HEADER_WIDETAG:
 437         return ptrans_code(thing);
 438
 439       case RETURN_PC_WIDETAG:
 440         return ptrans_returnpc(thing, header);
 441
 442       case FDEFN_WIDETAG:
 443         return ptrans_fdefn(thing, header);
 444
 445       default:
 446         if (other_immediate_lowtag_p(widetag) &&
 447             specialized_vector_widetag_p(widetag))
 448             return ptrans_vector(thing, 0, constant);
 449         fprintf(stderr, "Invalid widetag: %d\n", widetag_of(header));
 450         /* Should only come across other pointers to the above stuff. */
 451         gc_abort();
 452         return NIL;
 453     }
 454 }
 455
 456 static long
 457 pscav_fdefn(struct fdefn *fdefn)
 458 {
 459     boolean fix_func;
 460
 461     fix_func = ((char *)(fdefn->fun+FUN_RAW_ADDR_OFFSET) == fdefn->raw_addr);
 462     pscav(&fdefn->name, 1, 1);
 463     pscav(&fdefn->fun, 1, 0);
 464     if (fix_func)
 465         fdefn->raw_addr = (char *)(fdefn->fun + FUN_RAW_ADDR_OFFSET);
 466     return sizeof(struct fdefn) / sizeof(lispobj);
 467 }
 468
 469 static lispobj *
 470 pscav(lispobj *addr, long nwords, boolean constant)
 471 {
 472     lispobj thing, *thingp, header;
 473     long count = 0; /* (0 = dummy init value to stop GCC warning) */
 474
 475     while (nwords > 0) {
 476         thing = *addr;
 477         int widetag = widetag_of(thing);
 478         if (is_lisp_pointer(thing)) {
 479             /* It's a pointer. Is it something we might have to move? */
 480             if (dynamic_pointer_p(thing)) {
 481                 /* Maybe. Have we already moved it? */
 482                 thingp = native_pointer(thing);
 483                 header = *thingp;
 484                 if (is_lisp_pointer(header) && forwarding_pointer_p(header))
 485                     /* Yep, so just copy the forwarding pointer. */
 486                     thing = header;
 487                 else {
 488                     /* Nope, copy the object. */
 489                     switch (lowtag_of(thing)) {
 490                       case FUN_POINTER_LOWTAG:
 491                         thing = ptrans_func(thing, header);
 492                         break;
 493
 494                       case LIST_POINTER_LOWTAG:
 495                         thing = ptrans_list(thing, constant);
 496                         break;
 497
 498                       case INSTANCE_POINTER_LOWTAG:
 499                         thing = ptrans_instance(thing, header, constant);
 500                         break;
 501
 502                       case OTHER_POINTER_LOWTAG:
 503                         thing = ptrans_otherptr(thing, header, constant);
 504                         break;
 505
 506                       default:
 507                         /* It was a pointer, but not one of them? */
 508                         gc_abort();
 509                     }
 510                 }
 511                 *addr = thing;
 512             }
 513             count = 1;
 514         }
 515 #if N_WORD_BITS == 64
 516         else if (widetag == SINGLE_FLOAT_WIDETAG) {
 517             count = 1;
 518         }
 519 #endif
 520         else if (thing & FIXNUM_TAG_MASK) {
 521             /* It's an other immediate. Maybe the header for an unboxed */
 522             /* object. */
 523             switch (widetag) {
 524               case BIGNUM_WIDETAG:
 525               case SINGLE_FLOAT_WIDETAG:
 526               case DOUBLE_FLOAT_WIDETAG:
 527 #ifdef LONG_FLOAT_WIDETAG
 528               case LONG_FLOAT_WIDETAG:
 529 #endif
 530               case SAP_WIDETAG:
 531                 /* It's an unboxed simple object. */
 532                 count = CEILING(HeaderValue(thing)+1, 2);
 533                 break;
 534
 535               case SIMPLE_VECTOR_WIDETAG:
 536                   if (HeaderValue(thing) == subtype_VectorValidHashing) {
 537                     struct hash_table *hash_table =
 538                         (struct hash_table *)native_pointer(addr[2]);
 539                     hash_table->needs_rehash_p = T;
 540                   }
 541                 count = 2;
 542                 break;
 543
 544               case CODE_HEADER_WIDETAG:
 545                 gc_abort(); /* no code headers in static space */
 546                 break;
 547
 548               case SIMPLE_FUN_WIDETAG:
 549               case RETURN_PC_WIDETAG:
 550                 /* We should never hit any of these, 'cause they occur
 551                  * buried in the middle of code objects. */
 552                 gc_abort();
 553                 break;
 554
 555               case WEAK_POINTER_WIDETAG:
 556                 /* Weak pointers get preserved during purify, 'cause I
 557                  * don't feel like figuring out how to break them. */
 558                 pscav(addr+1, 2, constant);
 559                 count = WEAK_POINTER_NWORDS;
 560                 break;
 561
 562               case FDEFN_WIDETAG:
 563                 /* We have to handle fdefn objects specially, so we
 564                  * can fix up the raw function address. */
 565                 count = pscav_fdefn((struct fdefn *)addr);
 566                 break;
 567
 568               case INSTANCE_WIDETAG:
 569                 {
 570                     lispobj lbitmap = LAYOUT(instance_layout(addr))->bitmap;
 571                     lispobj* slots = addr + 1;
 572                     long nslots = instance_length(*addr) | 1;
 573                     int index;
 574                     if (fixnump(lbitmap)) {
 575                       sword_t bitmap = (sword_t)lbitmap >> N_FIXNUM_TAG_BITS;
 576                       for (index = 0; index < nslots ; index++, bitmap >>= 1)
 577                         if (bitmap & 1)
 578                           pscav(slots + index, 1, constant);
 579                     } else {
 580                       struct bignum * bitmap;
 581                       bitmap = (struct bignum*)native_pointer(lbitmap);
 582                       for (index = 0; index < nslots ; index++)
 583                         if (positive_bignum_logbitp(index, bitmap))
 584                           pscav(slots + index, 1, constant);
 585                     }
 586                     count = 1 + nslots;
 587                 }
 588                 break;
 589
 590               default:
 591                 if (other_immediate_lowtag_p(widetag) &&
 592                     specialized_vector_widetag_p(widetag))
 593                     count = sizetab[widetag_of(thing)](addr);
 594                 else
 595                     count = 1;
 596                 break;
 597             }
 598         }
 599         else {
 600             /* It's a fixnum. */
 601             count = 1;
 602         }
 603
 604         addr += count;
 605         nwords -= count;
 606     }
 607
 608     return addr;
 609 }
 610
 611 int
 612 purify(lispobj static_roots, lispobj read_only_roots)
 613 {
 614     lispobj *clean;
 615     long count, i;
 616     struct later *laters, *next;
 617     struct thread *thread;
 618
 619     if(all_threads->next) {
 620         /* FIXME: there should be _some_ sensible error reporting
 621          * convention.  See following comment too */
 622         fprintf(stderr,"Can't purify when more than one thread exists\n");
 623         fflush(stderr);
 624         return 0;
 625     }
 626
 627 #ifdef PRINTNOISE
 628     printf("[doing purification:");
 629     fflush(stdout);
 630 #endif
 631
 632     for_each_thread(thread)
 633         if (fixnum_value(SymbolValue(FREE_INTERRUPT_CONTEXT_INDEX,thread)) != 0) {
 634         /* FIXME: 1. What does this mean? 2. It shouldn't be reporting
 635          * its error simply by a. printing a string b. to stdout instead
 636          * of stderr. */
 637         printf(" Ack! Can't purify interrupt contexts. ");
 638         fflush(stdout);
 639         return 0;
 640     }
 641
 642     dynamic_space_purify_pointer = dynamic_space_free_pointer;
 643
 644     read_only_end = read_only_free = read_only_space_free_pointer;
 645     static_end = static_free = static_space_free_pointer;
 646
 647 #ifdef PRINTNOISE
 648     printf(" roots");
 649     fflush(stdout);
 650 #endif
 651
 652     pscav(&static_roots, 1, 0);
 653     pscav(&read_only_roots, 1, 1);
 654
 655 #ifdef PRINTNOISE
 656     printf(" handlers");
 657     fflush(stdout);
 658 #endif
 659     pscav((lispobj *) interrupt_handlers,
 660           sizeof(interrupt_handlers) / sizeof(lispobj),
 661           0);
 662
 663 #ifdef PRINTNOISE
 664     printf(" stack");
 665     fflush(stdout);
 666 #endif
 667     pscav((lispobj *)all_threads->control_stack_start,
 668           access_control_stack_pointer(all_threads) -
 669           all_threads->control_stack_start,
 670           0);
 671
 672 #ifdef PRINTNOISE
 673     printf(" bindings");
 674     fflush(stdout);
 675 #endif
 676
 677     pscav( (lispobj *)all_threads->binding_stack_start,
 678            (lispobj *)get_binding_stack_pointer(all_threads) -
 679            all_threads->binding_stack_start,
 680           0);
 681
 682     /* The original CMU CL code had scavenge-read-only-space code
 683      * controlled by the Lisp-level variable
 684      * *SCAVENGE-READ-ONLY-SPACE*. It was disabled by default, and it
 685      * wasn't documented under what circumstances it was useful or
 686      * safe to turn it on, so it's been turned off in SBCL. If you
 687      * want/need this functionality, and can test and document it,
 688      * please submit a patch. */
 689 #if 0
 690     if (SymbolValue(SCAVENGE_READ_ONLY_SPACE) != UNBOUND_MARKER_WIDETAG
 691         && SymbolValue(SCAVENGE_READ_ONLY_SPACE) != NIL) {
 692       unsigned  read_only_space_size =
 693           read_only_space_free_pointer - (lispobj *)READ_ONLY_SPACE_START;
 694       fprintf(stderr,
 695               "scavenging read only space: %d bytes\n",
 696               read_only_space_size * sizeof(lispobj));
 697       pscav( (lispobj *)READ_ONLY_SPACE_START, read_only_space_size, 0);
 698     }
 699 #endif
 700
 701 #ifdef PRINTNOISE
 702     printf(" static");
 703     fflush(stdout);
 704 #endif
 705     clean = (lispobj *)STATIC_SPACE_START;
 706     do {
 707         while (clean != static_free)
 708             clean = pscav(clean, static_free - clean, 0);
 709         laters = later_blocks;
 710         count = later_count;
 711         later_blocks = NULL;
 712         later_count = 0;
 713         while (laters != NULL) {
 714             for (i = 0; i < count; i++) {
 715                 if (laters->u[i].count == 0) {
 716                     ;
 717                 } else if (laters->u[i].count <= LATERMAXCOUNT) {
 718                     pscav(laters->u[i+1].ptr, laters->u[i].count, 1);
 719                     i++;
 720                 } else {
 721                     pscav(laters->u[i].ptr, 1, 1);
 722                 }
 723             }
 724             next = laters->next;
 725             free(laters);
 726             laters = next;
 727             count = LATERBLOCKSIZE;
 728         }
 729     } while (clean != static_free || later_blocks != NULL);
 730
 731 #ifdef PRINTNOISE
 732     printf(" cleanup");
 733     fflush(stdout);
 734 #endif
 735 #ifdef LISP_FEATURE_HPUX
 736     clear_auto_gc_trigger(); /* restore mmap as it was given by os */
 737 #endif
 738
 739     os_zero((os_vm_address_t) current_dynamic_space, dynamic_space_size);
 740
 741     /* Zero the stack. */
 742     os_zero((os_vm_address_t) access_control_stack_pointer(all_threads),
 743             (os_vm_size_t)
 744             ((all_threads->control_stack_end -
 745               access_control_stack_pointer(all_threads)) * sizeof(lispobj)));
 746
 747     /* It helps to update the heap free pointers so that free_heap can
 748      * verify after it's done. */
 749     read_only_space_free_pointer = read_only_free;
 750     static_space_free_pointer = static_free;
 751
 752     dynamic_space_free_pointer = current_dynamic_space;
 753     set_auto_gc_trigger(bytes_consed_between_gcs);
 754
 755     /* Blast away instruction cache */
 756     os_flush_icache((os_vm_address_t)READ_ONLY_SPACE_START, READ_ONLY_SPACE_SIZE);
 757     os_flush_icache((os_vm_address_t)STATIC_SPACE_START, STATIC_SPACE_SIZE);
 758
 759 #ifdef PRINTNOISE
 760     printf(" done]\n");
 761     fflush(stdout);
 762 #endif
 763     return 0;
 764 }
 765 #else /* LISP_FEATURE_GENCGC */
 766 int
 767 purify(lispobj static_roots, lispobj read_only_roots)
 768 {
 769     lose("purify called for GENCGC. This should not happen.");
 770 }
 771 #endif /* LISP_FEATURE_GENCGC */