| 1 | /*
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| 2 | * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
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| 3 | * Copyright (c) 1991-1994 by Xerox Corporation. All rights reserved.
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| 4 | *
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| 5 | * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
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| 6 | * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
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| 7 | *
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| 8 | * Permission is hereby granted to use or copy this program
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| 9 | * for any purpose, provided the above notices are retained on all copies.
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| 10 | * Permission to modify the code and to distribute modified code is granted,
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| 11 | * provided the above notices are retained, and a notice that the code was
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| 12 | * modified is included with the above copyright notice.
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| 13 | */
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| 14 | /* Boehm, July 31, 1995 5:02 pm PDT */
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| 15 |
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| 16 |
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| 17 | #include "private/gc_priv.h"
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| 18 |
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| 19 | # ifdef STUBBORN_ALLOC
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| 20 | /* Stubborn object (hard to change, nearly immutable) allocation. */
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| 21 |
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| 22 | extern ptr_t GC_clear_stack(); /* in misc.c, behaves like identity */
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| 23 |
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| 24 | #define GENERAL_MALLOC(lb,k) \
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| 25 | (GC_PTR)GC_clear_stack(GC_generic_malloc((word)lb, k))
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| 26 |
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| 27 | /* Data structure representing immutable objects that */
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| 28 | /* are still being initialized. */
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| 29 | /* This is a bit baroque in order to avoid acquiring */
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| 30 | /* the lock twice for a typical allocation. */
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| 31 |
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| 32 | GC_PTR * GC_changing_list_start;
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| 33 |
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| 34 | void GC_push_stubborn_structures GC_PROTO((void))
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| 35 | {
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| 36 | GC_push_all((ptr_t)(&GC_changing_list_start),
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| 37 | (ptr_t)(&GC_changing_list_start) + sizeof(GC_PTR *));
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| 38 | }
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| 39 |
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| 40 | # ifdef THREADS
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| 41 | VOLATILE GC_PTR * VOLATILE GC_changing_list_current;
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| 42 | # else
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| 43 | GC_PTR * GC_changing_list_current;
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| 44 | # endif
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| 45 | /* Points at last added element. Also (ab)used for */
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| 46 | /* synchronization. Updates and reads are assumed atomic. */
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| 47 |
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| 48 | GC_PTR * GC_changing_list_limit;
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| 49 | /* Points at the last word of the buffer, which is always 0 */
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| 50 | /* All entries in (GC_changing_list_current, */
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| 51 | /* GC_changing_list_limit] are 0 */
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| 52 |
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| 53 |
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| 54 | void GC_stubborn_init()
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| 55 | {
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| 56 | # define INIT_SIZE 10
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| 57 |
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| 58 | GC_changing_list_start = (GC_PTR *)
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| 59 | GC_INTERNAL_MALLOC(
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| 60 | (word)(INIT_SIZE * sizeof(GC_PTR)),
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| 61 | PTRFREE);
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| 62 | BZERO(GC_changing_list_start,
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| 63 | INIT_SIZE * sizeof(GC_PTR));
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| 64 | if (GC_changing_list_start == 0) {
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| 65 | GC_err_printf0("Insufficient space to start up\n");
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| 66 | ABORT("GC_stubborn_init: put of space");
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| 67 | }
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| 68 | GC_changing_list_current = GC_changing_list_start;
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| 69 | GC_changing_list_limit = GC_changing_list_start + INIT_SIZE - 1;
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| 70 | * GC_changing_list_limit = 0;
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| 71 | }
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| 72 |
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| 73 | /* Compact and possibly grow GC_uninit_list. The old copy is */
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| 74 | /* left alone. Lock must be held. */
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| 75 | /* When called GC_changing_list_current == GC_changing_list_limit */
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| 76 | /* which is one past the current element. */
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| 77 | /* When we finish GC_changing_list_current again points one past last */
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| 78 | /* element. */
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| 79 | /* Invariant while this is running: GC_changing_list_current */
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| 80 | /* points at a word containing 0. */
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| 81 | /* Returns FALSE on failure. */
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| 82 | GC_bool GC_compact_changing_list()
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| 83 | {
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| 84 | register GC_PTR *p, *q;
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| 85 | register word count = 0;
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| 86 | word old_size = (char **)GC_changing_list_limit
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| 87 | - (char **)GC_changing_list_start+1;
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| 88 | /* The casts are needed as a workaround for an Amiga bug */
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| 89 | register word new_size = old_size;
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| 90 | GC_PTR * new_list;
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| 91 |
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| 92 | for (p = GC_changing_list_start; p < GC_changing_list_limit; p++) {
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| 93 | if (*p != 0) count++;
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| 94 | }
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| 95 | if (2 * count > old_size) new_size = 2 * count;
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| 96 | new_list = (GC_PTR *)
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| 97 | GC_INTERNAL_MALLOC(
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| 98 | new_size * sizeof(GC_PTR), PTRFREE);
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| 99 | /* PTRFREE is a lie. But we don't want the collector to */
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| 100 | /* consider these. We do want the list itself to be */
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| 101 | /* collectable. */
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| 102 | if (new_list == 0) return(FALSE);
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| 103 | BZERO(new_list, new_size * sizeof(GC_PTR));
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| 104 | q = new_list;
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| 105 | for (p = GC_changing_list_start; p < GC_changing_list_limit; p++) {
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| 106 | if (*p != 0) *q++ = *p;
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| 107 | }
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| 108 | GC_changing_list_start = new_list;
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| 109 | GC_changing_list_limit = new_list + new_size - 1;
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| 110 | GC_changing_list_current = q;
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| 111 | return(TRUE);
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| 112 | }
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| 113 |
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| 114 | /* Add p to changing list. Clear p on failure. */
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| 115 | # define ADD_CHANGING(p) \
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| 116 | { \
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| 117 | register struct hblk * h = HBLKPTR(p); \
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