source: trunk/src/gcc/boehm-gc/blacklst.c@ 75

/* 
 * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
 * Copyright (c) 1991-1994 by Xerox Corporation.  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.
 */
/* Boehm, August 9, 1995 6:09 pm PDT */
# include "private/gc_priv.h"

/*
 * We maintain several hash tables of hblks that have had false hits.
 * Each contains one bit per hash bucket;  If any page in the bucket
 * has had a false hit, we assume that all of them have.
 * See the definition of page_hash_table in gc_private.h.
 * False hits from the stack(s) are much more dangerous than false hits
 * from elsewhere, since the former can pin a large object that spans the
 * block, eventhough it does not start on the dangerous block.
 */
 
/*
 * Externally callable routines are:
 
 * GC_add_to_black_list_normal
 * GC_add_to_black_list_stack
 * GC_promote_black_lists
 * GC_is_black_listed
 *
 * All require that the allocator lock is held.
 */

/* Pointers to individual tables.  We replace one table by another by   */
/* switching these pointers.                                            */
word * GC_old_normal_bl;
                /* Nonstack false references seen at last full          */
                /* collection.                                          */
word * GC_incomplete_normal_bl;
                /* Nonstack false references seen since last            */
                /* full collection.                                     */
word * GC_old_stack_bl;
word * GC_incomplete_stack_bl;

word GC_total_stack_black_listed;

word GC_black_list_spacing = MINHINCR*HBLKSIZE;  /* Initial rough guess */

void GC_clear_bl();

# if defined(__STDC__) || defined(__cplusplus)
    void GC_default_print_heap_obj_proc(ptr_t p)
# else
    void GC_default_print_heap_obj_proc(p)
    ptr_t p;
# endif
{
    ptr_t base = GC_base(p);

    GC_err_printf2("start: 0x%lx, appr. length: %ld", base, GC_size(base));
}

void (*GC_print_heap_obj) GC_PROTO((ptr_t p)) =
                                GC_default_print_heap_obj_proc;

void GC_print_source_ptr(p)
ptr_t p;
{
    ptr_t base = GC_base(p);
    if (0 == base) {
        if (0 == p) {
            GC_err_printf0("in register");
        } else {
            GC_err_printf0("in root set");
        }
    } else {
        GC_err_printf0("in object at ");
        (*GC_print_heap_obj)(base);
    }
}

void GC_bl_init()
{
    if (!GC_all_interior_pointers) {
      GC_old_normal_bl = (word *)
                         GC_scratch_alloc((word)(sizeof (page_hash_table)));
      GC_incomplete_normal_bl = (word *)GC_scratch_alloc
                                        ((word)(sizeof(page_hash_table)));
      if (GC_old_normal_bl == 0 || GC_incomplete_normal_bl == 0) {
        GC_err_printf0("Insufficient memory for black list\n");
        EXIT();
      }
      GC_clear_bl(GC_old_normal_bl);
      GC_clear_bl(GC_incomplete_normal_bl);
    }
    GC_old_stack_bl = (word *)GC_scratch_alloc((word)(sizeof(page_hash_table)));
    GC_incomplete_stack_bl = (word *)GC_scratch_alloc
                                        ((word)(sizeof(page_hash_table)));
    if (GC_old_stack_bl == 0 || GC_incomplete_stack_bl == 0) {
        GC_err_printf0("Insufficient memory for black list\n");
        EXIT();
    }
    GC_clear_bl(GC_old_stack_bl);
    GC_clear_bl(GC_incomplete_stack_bl);
}
                
void GC_clear_bl(doomed)
word *doomed;
{
    BZERO(doomed, sizeof(page_hash_table));
}

void GC_copy_bl(old, new)
word *new, *old;
{
    BCOPY(old, new, sizeof(page_hash_table));
}

static word total_stack_black_listed();

/* Signal the completion of a collection.  Turn the incomplete black    */
/* lists into new black lists, etc.                                     */                       
void GC_promote_black_lists()
{
    word * very_old_normal_bl = GC_old_normal_bl;
    word * very_old_stack_bl = GC_old_stack_bl;
    
    GC_old_normal_bl = GC_incomplete_normal_bl;
    GC_old_stack_bl = GC_incomplete_stack_bl;
    if (!GC_all_interior_pointers) {
      GC_clear_bl(very_old_normal_bl);
    }
    GC_clear_bl(very_old_stack_bl);
    GC_incomplete_normal_bl = very_old_normal_bl;
    GC_incomplete_stack_bl = very_old_stack_bl;
    GC_total_stack_black_listed = total_stack_black_listed();
#   ifdef PRINTSTATS
        GC_printf1("%ld bytes in heap blacklisted for interior pointers\n",
                   (unsigned long)GC_total_stack_black_listed);
#   endif
    if (GC_total_stack_black_listed != 0) {
        GC_black_list_spacing =
                HBLKSIZE*(GC_heapsize/GC_total_stack_black_listed);
    }
    if (GC_black_list_spacing < 3 * HBLKSIZE) {
        GC_black_list_spacing = 3 * HBLKSIZE;
    }
    if (GC_black_list_spacing > MAXHINCR * HBLKSIZE) {
        GC_black_list_spacing = MAXHINCR * HBLKSIZE;
        /* Makes it easier to allocate really huge blocks, which otherwise */
        /* may have problems with nonuniform blacklist distributions.      */
        /* This way we should always succeed immediately after growing the */ 
        /* heap.                                                           */
    }
}

void GC_unpromote_black_lists()
{
    if (!GC_all_interior_pointers) {
      GC_copy_bl(GC_old_normal_bl, GC_incomplete_normal_bl);
    }
    GC_copy_bl(GC_old_stack_bl, GC_incomplete_stack_bl);
}

/* P is not a valid pointer reference, but it falls inside      */
/* the plausible heap bounds.                                   */
/* Add it to the normal incomplete black list if appropriate.   */
#ifdef PRINT_BLACK_LIST
  void GC_add_to_black_list_normal(p, source)
  ptr_t source;
#else
  void GC_add_to_black_list_normal(p)
#endif
word p;
{
    if (!(GC_modws_valid_offsets[p & (sizeof(word)-1)])) return;
    {
        register int index = PHT_HASH(p);
        
        if (HDR(p) == 0 || get_pht_entry_from_index(GC_old_normal_bl, index)) {
#           ifdef PRINT_BLACK_LIST
                if (!get_pht_entry_from_index(GC_incomplete_normal_bl, index)) {
                  GC_err_printf2(
                        "Black listing (normal) 0x%lx referenced from 0x%lx ",
                        (unsigned long) p, (unsigned long) source);
                  GC_print_source_ptr(source);
                  GC_err_puts("\n");
                }
#           endif
            set_pht_entry_from_index(GC_incomplete_normal_bl, index);
        } /* else this is probably just an interior pointer to an allocated */
          /* object, and isn't worth black listing.                         */
    }
}

/* And the same for false pointers from the stack. */
#ifdef PRINT_BLACK_LIST
  void GC_add_to_black_list_stack(p, source)
  ptr_t source;
#else
  void GC_add_to_black_list_stack(p)
#endif
word p;
{
    register int index = PHT_HASH(p);
        
    if (HDR(p) == 0 || get_pht_entry_from_index(GC_old_stack_bl, index)) {
#       ifdef PRINT_BLACK_LIST