2 * Copyright (c) 1992-1994 by Xerox Corporation. All rights reserved.
4 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
5 * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
7 * Permission is hereby granted to use or copy this program
8 * for any purpose, provided the above notices are retained on all copies.
9 * Permission to modify the code and to distribute modified code is granted,
10 * provided the above notices are retained, and a notice that the code was
11 * modified is included with the above copyright notice.
13 /* Boehm, March 29, 1995 12:51 pm PST */
16 # include "private/gc_priv.h"
18 /* This is debugging code intended to verify the results of dirty bit */
19 /* computations. Works only in a single threaded environment. */
20 /* We assume that stubborn objects are changed only when they are */
21 /* enabled for writing. (Certain kinds of writing are actually */
22 /* safe under other conditions.) */
25 # define OFFSET 0x10000
31 struct hblk * block; /* Block to which this refers + OFFSET */
32 /* to hide it from collector. */
35 page_entry GC_sums [NSUMS];
37 STATIC word GC_faulted[NSUMS]; /* Record of pages on which we saw a write */
39 STATIC size_t GC_n_faulted = 0;
41 void GC_record_fault(struct hblk * h)
45 page += GC_page_size - 1;
46 page &= ~(GC_page_size - 1);
47 if (GC_n_faulted >= NSUMS) ABORT("write fault log overflowed");
48 GC_faulted[GC_n_faulted++] = page;
51 STATIC GC_bool GC_was_faulted(struct hblk *h)
56 page += GC_page_size - 1;
57 page &= ~(GC_page_size - 1);
58 for (i = 0; i < GC_n_faulted; ++i) {
59 if (GC_faulted[i] == page) return TRUE;
64 STATIC word GC_checksum(struct hblk *h)
66 register word *p = (word *)h;
67 register word *lim = (word *)(h+1);
68 register word result = 0;
73 return(result | 0x80000000 /* doesn't look like pointer */);
76 # ifdef STUBBORN_ALLOC
77 /* Check whether a stubborn object from the given block appears on */
78 /* the appropriate free list. */
79 STATIC GC_bool GC_on_free_list(struct hblk *h)
82 size_t sz = BYTES_TO_WORDS(hhdr -> hb_sz);
85 if (sz > MAXOBJWORDS) return(FALSE);
86 for (p = GC_sobjfreelist[sz]; p != 0; p = obj_link(p)) {
87 if (HBLKPTR(p) == h) return(TRUE);
93 int GC_n_dirty_errors;
94 int GC_n_faulted_dirty_errors;
95 int GC_n_changed_errors;
99 STATIC void GC_update_check_page(struct hblk *h, int index)
101 page_entry *pe = GC_sums + index;
102 register hdr * hhdr = HDR(h);
105 if (pe -> block != 0 && pe -> block != h + OFFSET) ABORT("goofed");
106 pe -> old_sum = pe -> new_sum;
107 pe -> new_sum = GC_checksum(h);
108 # if !defined(MSWIN32) && !defined(MSWINCE)
109 if (pe -> new_sum != 0x80000000 && !GC_page_was_ever_dirty(h)) {
110 GC_printf("GC_page_was_ever_dirty(%p) is wrong\n", h);
113 if (GC_page_was_dirty(h)) {
119 while (IS_FORWARDING_ADDR_OR_NIL(hhdr) && hhdr != 0) {
124 && hhdr != 0 && hhdr -> hb_descr != 0 /* may contain pointers */
125 && pe -> old_sum != pe -> new_sum) {
126 if (!GC_page_was_dirty(h) || !GC_page_was_ever_dirty(h)) {
127 GC_bool was_faulted = GC_was_faulted(h);
128 /* Set breakpoint here */GC_n_dirty_errors++;
129 if (was_faulted) GC_n_faulted_dirty_errors++;
131 # ifdef STUBBORN_ALLOC
132 if (!HBLK_IS_FREE(hhdr)
133 && hhdr -> hb_obj_kind == STUBBORN
134 && !GC_page_was_changed(h)
135 && !GC_on_free_list(h)) {
136 /* if GC_on_free_list(h) then reclaim may have touched it */
137 /* without any allocations taking place. */
138 /* Set breakpoint here */GC_n_changed_errors++;
142 pe -> new_valid = TRUE;
143 pe -> block = h + OFFSET;
146 word GC_bytes_in_used_blocks;
149 STATIC void GC_add_block(struct hblk *h, word dummy)
152 size_t bytes = hhdr -> hb_sz;
155 bytes &= ~(HBLKSIZE-1);
156 GC_bytes_in_used_blocks += bytes;
159 STATIC void GC_check_blocks(void)
161 word bytes_in_free_blocks = GC_large_free_bytes;
163 GC_bytes_in_used_blocks = 0;
164 GC_apply_to_all_blocks(GC_add_block, (word)0);
165 GC_printf("GC_bytes_in_used_blocks = %lu, bytes_in_free_blocks = %lu ",
166 (unsigned long)GC_bytes_in_used_blocks,
167 (unsigned long)bytes_in_free_blocks);
168 GC_printf("GC_heapsize = %lu\n", (unsigned long)GC_heapsize);
169 if (GC_bytes_in_used_blocks + bytes_in_free_blocks != GC_heapsize) {
170 GC_printf("LOST SOME BLOCKS!!\n");
174 /* Should be called immediately after GC_read_dirty and GC_read_changed. */
175 void GC_check_dirty(void)
184 GC_n_dirty_errors = 0;
185 GC_n_faulted_dirty_errors = 0;
186 GC_n_changed_errors = 0;
191 for (i = 0; i < GC_n_heap_sects; i++) {
192 start = GC_heap_sects[i].hs_start;
193 for (h = (struct hblk *)start;
194 h < (struct hblk *)(start + GC_heap_sects[i].hs_bytes);
196 GC_update_check_page(h, index);
198 if (index >= NSUMS) goto out;
202 GC_printf("Checked %lu clean and %lu dirty pages\n",
203 (unsigned long) GC_n_clean, (unsigned long) GC_n_dirty);
204 if (GC_n_dirty_errors > 0) {
205 GC_printf("Found %d dirty bit errors (%d were faulted)\n",
206 GC_n_dirty_errors, GC_n_faulted_dirty_errors);
208 if (GC_n_changed_errors > 0) {
209 GC_printf("Found %lu changed bit errors\n",
210 (unsigned long)GC_n_changed_errors);
211 GC_printf("These may be benign (provoked by nonpointer changes)\n");
214 "Also expect 1 per thread currently allocating a stubborn obj.\n");
217 for (i = 0; i < GC_n_faulted; ++i) {
218 GC_faulted[i] = 0; /* Don't expose block pointers to GC */
226 /* ANSI C doesn't allow translation units to be empty. */
227 /* So we guarantee this one is nonempty. */
229 # endif /* CHECKSUMS */