303 lines
11 KiB
C
303 lines
11 KiB
C
/*
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* Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
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* Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
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*
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* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
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* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
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*
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* Permission is hereby granted to use or copy this program
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* for any purpose, provided the above notices are retained on all copies.
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* Permission to modify the code and to distribute modified code is granted,
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* provided the above notices are retained, and a notice that the code was
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* modified is included with the above copyright notice.
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*/
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#include "private/gc_priv.h"
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/*
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* We maintain several hash tables of hblks that have had false hits.
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* Each contains one bit per hash bucket; If any page in the bucket
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* has had a false hit, we assume that all of them have.
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* See the definition of page_hash_table in gc_private.h.
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* False hits from the stack(s) are much more dangerous than false hits
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* from elsewhere, since the former can pin a large object that spans the
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* block, even though it does not start on the dangerous block.
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*/
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/*
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* Externally callable routines are:
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* GC_add_to_black_list_normal
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* GC_add_to_black_list_stack
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* GC_promote_black_lists
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* GC_is_black_listed
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*
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* All require that the allocator lock is held.
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*/
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/* Pointers to individual tables. We replace one table by another by */
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/* switching these pointers. */
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STATIC word * GC_old_normal_bl = NULL;
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/* Nonstack false references seen at last full */
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/* collection. */
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STATIC word * GC_incomplete_normal_bl = NULL;
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/* Nonstack false references seen since last */
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/* full collection. */
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STATIC word * GC_old_stack_bl = NULL;
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STATIC word * GC_incomplete_stack_bl = NULL;
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STATIC word GC_total_stack_black_listed = 0;
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/* Number of bytes on stack blacklist. */
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GC_INNER word GC_black_list_spacing = MINHINCR * HBLKSIZE;
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/* Initial rough guess. */
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STATIC void GC_clear_bl(word *);
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GC_INNER void GC_default_print_heap_obj_proc(ptr_t p)
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{
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ptr_t base = (ptr_t)GC_base(p);
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int kind = HDR(base)->hb_obj_kind;
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GC_err_printf("object at %p of appr. %lu bytes (%s)\n",
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(void *)base, (unsigned long)GC_size(base),
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kind == PTRFREE ? "atomic" :
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IS_UNCOLLECTABLE(kind) ? "uncollectable" : "composite");
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}
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GC_INNER void (*GC_print_heap_obj)(ptr_t p) = GC_default_print_heap_obj_proc;
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#ifdef PRINT_BLACK_LIST
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STATIC void GC_print_blacklisted_ptr(word p, ptr_t source,
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const char *kind_str)
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{
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ptr_t base = (ptr_t)GC_base(source);
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if (0 == base) {
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GC_err_printf("Black listing (%s) %p referenced from %p in %s\n",
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kind_str, (void *)p, (void *)source,
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NULL != source ? "root set" : "register");
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} else {
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/* FIXME: We can't call the debug version of GC_print_heap_obj */
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/* (with PRINT_CALL_CHAIN) here because the lock is held and */
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/* the world is stopped. */
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GC_err_printf("Black listing (%s) %p referenced from %p in"
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" object at %p of appr. %lu bytes\n",
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kind_str, (void *)p, (void *)source,
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(void *)base, (unsigned long)GC_size(base));
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}
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}
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#endif /* PRINT_BLACK_LIST */
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GC_INNER void GC_bl_init_no_interiors(void)
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{
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if (GC_incomplete_normal_bl == 0) {
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GC_old_normal_bl = (word *)GC_scratch_alloc(sizeof(page_hash_table));
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GC_incomplete_normal_bl = (word *)GC_scratch_alloc(
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sizeof(page_hash_table));
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if (GC_old_normal_bl == 0 || GC_incomplete_normal_bl == 0) {
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GC_err_printf("Insufficient memory for black list\n");
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EXIT();
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}
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GC_clear_bl(GC_old_normal_bl);
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GC_clear_bl(GC_incomplete_normal_bl);
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}
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}
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GC_INNER void GC_bl_init(void)
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{
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if (!GC_all_interior_pointers) {
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GC_bl_init_no_interiors();
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}
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GC_ASSERT(NULL == GC_old_stack_bl && NULL == GC_incomplete_stack_bl);
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GC_old_stack_bl = (word *)GC_scratch_alloc(sizeof(page_hash_table));
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GC_incomplete_stack_bl = (word *)GC_scratch_alloc(sizeof(page_hash_table));
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if (GC_old_stack_bl == 0 || GC_incomplete_stack_bl == 0) {
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GC_err_printf("Insufficient memory for black list\n");
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EXIT();
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}
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GC_clear_bl(GC_old_stack_bl);
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GC_clear_bl(GC_incomplete_stack_bl);
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}
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STATIC void GC_clear_bl(word *doomed)
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{
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BZERO(doomed, sizeof(page_hash_table));
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}
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STATIC void GC_copy_bl(word *old, word *dest)
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{
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BCOPY(old, dest, sizeof(page_hash_table));
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}
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static word total_stack_black_listed(void);
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/* Signal the completion of a collection. Turn the incomplete black */
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/* lists into new black lists, etc. */
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GC_INNER void GC_promote_black_lists(void)
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{
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word * very_old_normal_bl = GC_old_normal_bl;
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word * very_old_stack_bl = GC_old_stack_bl;
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GC_old_normal_bl = GC_incomplete_normal_bl;
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GC_old_stack_bl = GC_incomplete_stack_bl;
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if (!GC_all_interior_pointers) {
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GC_clear_bl(very_old_normal_bl);
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}
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GC_clear_bl(very_old_stack_bl);
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GC_incomplete_normal_bl = very_old_normal_bl;
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GC_incomplete_stack_bl = very_old_stack_bl;
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GC_total_stack_black_listed = total_stack_black_listed();
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GC_VERBOSE_LOG_PRINTF(
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"%lu bytes in heap blacklisted for interior pointers\n",
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(unsigned long)GC_total_stack_black_listed);
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if (GC_total_stack_black_listed != 0) {
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GC_black_list_spacing =
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HBLKSIZE*(GC_heapsize/GC_total_stack_black_listed);
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}
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if (GC_black_list_spacing < 3 * HBLKSIZE) {
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GC_black_list_spacing = 3 * HBLKSIZE;
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}
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if (GC_black_list_spacing > MAXHINCR * HBLKSIZE) {
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GC_black_list_spacing = MAXHINCR * HBLKSIZE;
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/* Makes it easier to allocate really huge blocks, which otherwise */
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/* may have problems with nonuniform blacklist distributions. */
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/* This way we should always succeed immediately after growing the */
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/* heap. */
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}
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}
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GC_INNER void GC_unpromote_black_lists(void)
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{
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if (!GC_all_interior_pointers) {
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GC_copy_bl(GC_old_normal_bl, GC_incomplete_normal_bl);
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}
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GC_copy_bl(GC_old_stack_bl, GC_incomplete_stack_bl);
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}
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#if defined(set_pht_entry_from_index_concurrent) && defined(PARALLEL_MARK) \
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&& defined(THREAD_SANITIZER)
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# define backlist_set_pht_entry_from_index(db, index) \
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set_pht_entry_from_index_concurrent(db, index)
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#else
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/* It is safe to set a bit in a blacklist even without */
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/* synchronization, the only drawback is that we might have */
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/* to redo blacklisting sometimes. */
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# define backlist_set_pht_entry_from_index(bl, index) \
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set_pht_entry_from_index(bl, index)
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#endif
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/* P is not a valid pointer reference, but it falls inside */
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/* the plausible heap bounds. */
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/* Add it to the normal incomplete black list if appropriate. */
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#ifdef PRINT_BLACK_LIST
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GC_INNER void GC_add_to_black_list_normal(word p, ptr_t source)
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#else
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GC_INNER void GC_add_to_black_list_normal(word p)
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#endif
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{
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if (GC_modws_valid_offsets[p & (sizeof(word)-1)]) {
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word index = PHT_HASH((word)p);
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if (HDR(p) == 0 || get_pht_entry_from_index(GC_old_normal_bl, index)) {
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# ifdef PRINT_BLACK_LIST
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if (!get_pht_entry_from_index(GC_incomplete_normal_bl, index)) {
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GC_print_blacklisted_ptr(p, source, "normal");
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}
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# endif
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backlist_set_pht_entry_from_index(GC_incomplete_normal_bl, index);
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} /* else this is probably just an interior pointer to an allocated */
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/* object, and isn't worth black listing. */
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}
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}
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/* And the same for false pointers from the stack. */
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#ifdef PRINT_BLACK_LIST
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GC_INNER void GC_add_to_black_list_stack(word p, ptr_t source)
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#else
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GC_INNER void GC_add_to_black_list_stack(word p)
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#endif
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{
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word index = PHT_HASH((word)p);
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if (HDR(p) == 0 || get_pht_entry_from_index(GC_old_stack_bl, index)) {
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# ifdef PRINT_BLACK_LIST
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if (!get_pht_entry_from_index(GC_incomplete_stack_bl, index)) {
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GC_print_blacklisted_ptr(p, source, "stack");
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}
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# endif
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backlist_set_pht_entry_from_index(GC_incomplete_stack_bl, index);
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}
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}
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/*
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* Is the block starting at h of size len bytes black listed? If so,
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* return the address of the next plausible r such that (r, len) might not
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* be black listed. (R may not actually be in the heap. We guarantee only
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* that every smaller value of r after h is also black listed.)
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* If (h,len) is not black listed, return 0.
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* Knows about the structure of the black list hash tables.
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*/
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struct hblk * GC_is_black_listed(struct hblk *h, word len)
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{
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word index = PHT_HASH((word)h);
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word i;
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word nblocks;
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if (!GC_all_interior_pointers
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&& (get_pht_entry_from_index(GC_old_normal_bl, index)
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|| get_pht_entry_from_index(GC_incomplete_normal_bl, index))) {
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return (h+1);
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}
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nblocks = divHBLKSZ(len);
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for (i = 0;;) {
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if (GC_old_stack_bl[divWORDSZ(index)] == 0
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&& GC_incomplete_stack_bl[divWORDSZ(index)] == 0) {
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/* An easy case */
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i += WORDSZ - modWORDSZ(index);
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} else {
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if (get_pht_entry_from_index(GC_old_stack_bl, index)
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|| get_pht_entry_from_index(GC_incomplete_stack_bl, index)) {
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return(h+i+1);
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}
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i++;
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}
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if (i >= nblocks) break;
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index = PHT_HASH((word)(h+i));
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}
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return(0);
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}
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/* Return the number of blacklisted blocks in a given range. */
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/* Used only for statistical purposes. */
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/* Looks only at the GC_incomplete_stack_bl. */
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STATIC word GC_number_stack_black_listed(struct hblk *start,
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struct hblk *endp1)
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{
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struct hblk * h;
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word result = 0;
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for (h = start; (word)h < (word)endp1; h++) {
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word index = PHT_HASH((word)h);
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if (get_pht_entry_from_index(GC_old_stack_bl, index)) result++;
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}
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return(result);
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}
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/* Return the total number of (stack) black-listed bytes. */
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static word total_stack_black_listed(void)
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{
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unsigned i;
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word total = 0;
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for (i = 0; i < GC_n_heap_sects; i++) {
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struct hblk * start = (struct hblk *) GC_heap_sects[i].hs_start;
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struct hblk * endp1 = start + divHBLKSZ(GC_heap_sects[i].hs_bytes);
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total += GC_number_stack_black_listed(start, endp1);
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}
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return(total * HBLKSIZE);
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}
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