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+/*
+ * 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
+ 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);
+
+ if (!GC_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);
+ }
+ }
+
+ 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);
+}
+
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