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Diffstat (limited to '')
| -rw-r--r-- | gc/blacklst.c | 291 |
1 files changed, 291 insertions, 0 deletions
diff --git a/gc/blacklst.c b/gc/blacklst.c new file mode 100644 index 0000000..0d623c0 --- /dev/null +++ b/gc/blacklst.c @@ -0,0 +1,291 @@ +/* + * 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 "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(); + +void GC_default_print_heap_obj_proc(p) +ptr_t p; +{ + ptr_t base = GC_base(p); + + GC_err_printf2("start: 0x%lx, appr. length: %ld", base, GC_size(base)); +} + +void (*GC_print_heap_obj)(/* char * s, 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() +{ +# ifndef 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); +# endif + 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; +# ifndef ALL_INTERIOR_POINTERS + GC_clear_bl(very_old_normal_bl); +# endif + 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; + } +} + +void GC_unpromote_black_lists() +{ +# ifndef ALL_INTERIOR_POINTERS + GC_copy_bl(GC_old_normal_bl, GC_incomplete_normal_bl); +# endif + GC_copy_bl(GC_old_stack_bl, GC_incomplete_stack_bl); +} + +# ifndef ALL_INTERIOR_POINTERS +/* 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. */ + } +} +# endif + +/* 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 + if (!get_pht_entry_from_index(GC_incomplete_stack_bl, index)) { + GC_err_printf2( + "Black listing (stack) 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_stack_bl, index); + } +} + +/* + * Is the block starting at h of size len bytes black listed? If so, + * return the address of the next plausible r such that (r, len) might not + * be black listed. (R may not actually be in the heap. We guarantee only + * that every smaller value of r after h is also black listed.) + * If (h,len) is not black listed, return 0. + * Knows about the structure of the black list hash tables. + */ +struct hblk * GC_is_black_listed(h, len) +struct hblk * h; +word len; +{ + register int index = PHT_HASH((word)h); + register word i; + word nblocks = divHBLKSZ(len); + +# ifndef ALL_INTERIOR_POINTERS + if (get_pht_entry_from_index(GC_old_normal_bl, index) + || get_pht_entry_from_index(GC_incomplete_normal_bl, index)) { + return(h+1); + } +# endif + + for (i = 0; ; ) { + if (GC_old_stack_bl[divWORDSZ(index)] == 0 + && GC_incomplete_stack_bl[divWORDSZ(index)] == 0) { + /* An easy case */ + i += WORDSZ - modWORDSZ(index); + } else { + if (get_pht_entry_from_index(GC_old_stack_bl, index) + || get_pht_entry_from_index(GC_incomplete_stack_bl, index)) { + return(h+i+1); + } + i++; + } + if (i >= nblocks) break; + index = PHT_HASH((word)(h+i)); + } + return(0); +} + + +/* Return the number of blacklisted blocks in a given range. */ +/* Used only for statistical purposes. */ +/* Looks only at the GC_incomplete_stack_bl. */ +word GC_number_stack_black_listed(start, endp1) +struct hblk *start, *endp1; +{ + register struct hblk * h; + word result = 0; + + for (h = start; h < endp1; h++) { + register int index = PHT_HASH((word)h); + + if (get_pht_entry_from_index(GC_old_stack_bl, index)) result++; + } + return(result); +} + + +/* Return the total number of (stack) black-listed bytes. */ +static word total_stack_black_listed() +{ + register unsigned i; + word total = 0; + + for (i = 0; i < GC_n_heap_sects; i++) { + struct hblk * start = (struct hblk *) GC_heap_sects[i].hs_start; + word len = (word) GC_heap_sects[i].hs_bytes; + struct hblk * endp1 = start + len/HBLKSIZE; + + total += GC_number_stack_black_listed(start, endp1); + } + return(total * HBLKSIZE); +} + |