2 * Copyright (c) 1991-1994 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.
15 * These are checking routines calls to which could be inserted by a
16 * preprocessor to validate C pointer arithmetic.
19 #include "private/gc_pmark.h"
22 void GC_default_same_obj_print_proc(GC_PTR p, GC_PTR q)
24 void GC_default_same_obj_print_proc (p, q)
28 GC_err_printf2("0x%lx and 0x%lx are not in the same object\n",
29 (unsigned long)p, (unsigned long)q);
30 ABORT("GC_same_obj test failed");
33 void (*GC_same_obj_print_proc) GC_PROTO((GC_PTR, GC_PTR))
34 = GC_default_same_obj_print_proc;
36 /* Check that p and q point to the same object. Call */
37 /* *GC_same_obj_print_proc if they don't. */
38 /* Returns the first argument. (Return value may be hard */
39 /* to use,due to typing issues. But if we had a suitable */
40 /* preprocessor ...) */
41 /* Succeeds if neither p nor q points to the heap. */
42 /* We assume this is performance critical. (It shouldn't */
43 /* be called by production code, but this can easily make */
44 /* debugging intolerably slow.) */
46 GC_PTR GC_same_obj(register void *p, register void *q)
48 GC_PTR GC_same_obj(p, q)
52 register struct hblk *h;
54 register ptr_t base, limit;
57 if (!GC_is_initialized) GC_init();
60 if (divHBLKSZ((word)p) != divHBLKSZ((word)q)
61 && HDR((word)q) != 0) {
66 /* If it's a pointer to the middle of a large object, move it */
67 /* to the beginning. */
68 if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
69 h = HBLKPTR(p) - (word)hhdr;
71 while (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
72 h = FORWARDED_ADDR(h, hhdr);
75 limit = (ptr_t)((word *)h + hhdr -> hb_sz);
76 if ((ptr_t)p >= limit || (ptr_t)q >= limit || (ptr_t)q < (ptr_t)h ) {
81 sz = WORDS_TO_BYTES(hhdr -> hb_sz);
82 if (sz > MAXOBJBYTES) {
83 base = (ptr_t)HBLKPTR(p);
85 if ((ptr_t)p >= limit) {
89 register int map_entry;
90 register int pdispl = HBLKDISPL(p);
92 map_entry = MAP_ENTRY((hhdr -> hb_map), pdispl);
93 if (map_entry > CPP_MAX_OFFSET) {
94 map_entry = BYTES_TO_WORDS(pdispl) % BYTES_TO_WORDS(sz);
95 if (HBLKPTR(p) != HBLKPTR(q)) goto fail;
96 /* W/o this check, we might miss an error if */
97 /* q points to the first object on a page, and */
98 /* points just before the page. */
100 base = (char *)((word)p & ~(WORDS_TO_BYTES(1) - 1));
101 base -= WORDS_TO_BYTES(map_entry);
104 /* [base, limit) delimits the object containing p, if any. */
105 /* If p is not inside a valid object, then either q is */
106 /* also outside any valid object, or it is outside */
108 if ((ptr_t)q >= limit || (ptr_t)q < base) {
113 (*GC_same_obj_print_proc)((ptr_t)p, (ptr_t)q);
118 void GC_default_is_valid_displacement_print_proc (GC_PTR p)
120 void GC_default_is_valid_displacement_print_proc (p)
124 GC_err_printf1("0x%lx does not point to valid object displacement\n",
126 ABORT("GC_is_valid_displacement test failed");
129 void (*GC_is_valid_displacement_print_proc) GC_PROTO((GC_PTR)) =
130 GC_default_is_valid_displacement_print_proc;
132 /* Check that if p is a pointer to a heap page, then it points to */
133 /* a valid displacement within a heap object. */
134 /* Uninteresting with GC_all_interior_pointers. */
135 /* Always returns its argument. */
136 /* Note that we don't lock, since nothing relevant about the header */
137 /* should change while we have a valid object pointer to the block. */
139 void * GC_is_valid_displacement(void *p)
141 char *GC_is_valid_displacement(p)
146 register word pdispl;
147 register struct hblk *h;
148 register map_entry_type map_entry;
151 if (!GC_is_initialized) GC_init();
153 if (hhdr == 0) return(p);
155 if (GC_all_interior_pointers) {
156 while (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
157 h = FORWARDED_ADDR(h, hhdr);
161 if (IS_FORWARDING_ADDR_OR_NIL(hhdr)) {
164 sz = WORDS_TO_BYTES(hhdr -> hb_sz);
165 pdispl = HBLKDISPL(p);
166 map_entry = MAP_ENTRY((hhdr -> hb_map), pdispl);
167 if (map_entry == OBJ_INVALID
168 || sz > MAXOBJBYTES && (ptr_t)p >= (ptr_t)h + sz) {
173 (*GC_is_valid_displacement_print_proc)((ptr_t)p);
178 void GC_default_is_visible_print_proc(GC_PTR p)
180 void GC_default_is_visible_print_proc(p)
184 GC_err_printf1("0x%lx is not a GC visible pointer location\n",
186 ABORT("GC_is_visible test failed");
189 void (*GC_is_visible_print_proc) GC_PROTO((GC_PTR p)) =
190 GC_default_is_visible_print_proc;
192 /* Could p be a stack address? */
193 GC_bool GC_on_stack(p)
200 # ifdef STACK_GROWS_DOWN
201 if ((ptr_t)p >= (ptr_t)(&dummy) && (ptr_t)p < GC_stackbottom ) {
205 if ((ptr_t)p <= (ptr_t)(&dummy) && (ptr_t)p > GC_stackbottom ) {
213 /* Check that p is visible */
214 /* to the collector as a possibly pointer containing location. */
215 /* If it isn't invoke *GC_is_visible_print_proc. */
216 /* Returns the argument in all cases. May erroneously succeed */
217 /* in hard cases. (This is intended for debugging use with */
218 /* untyped allocations. The idea is that it should be possible, though */
219 /* slow, to add such a call to all indirect pointer stores.) */
220 /* Currently useless for multithreaded worlds. */
222 void * GC_is_visible(void *p)
224 char *GC_is_visible(p)
230 if ((word)p & (ALIGNMENT - 1)) goto fail;
231 if (!GC_is_initialized) GC_init();
234 if (hhdr != 0 && GC_base(p) == 0) {
237 /* May be inside thread stack. We can't do much. */
241 /* Check stack first: */
242 if (GC_on_stack(p)) return(p);
247 if (GC_is_static_root(p)) return(p);
248 /* Else do it again correctly: */
249 # if (defined(DYNAMIC_LOADING) || defined(MSWIN32) || \
250 defined(MSWINCE) || defined (CYGWIN32) || defined(PCR)) \
253 GC_register_dynamic_libraries();
254 result = GC_is_static_root(p);
256 if (result) return(p);
260 /* p points to the heap. */
262 ptr_t base = GC_base(p); /* Should be manually inlined? */
264 if (base == 0) goto fail;
265 if (HBLKPTR(base) != HBLKPTR(p)) hhdr = HDR((word)p);
266 descr = hhdr -> hb_descr;
268 switch(descr & GC_DS_TAGS) {
270 if ((word)((ptr_t)p - (ptr_t)base) > (word)descr) goto fail;
273 if ((ptr_t)p - (ptr_t)base
274 >= WORDS_TO_BYTES(BITMAP_BITS)
275 || ((word)p & (sizeof(word) - 1))) goto fail;
276 if (!((1 << (WORDSZ - ((ptr_t)p - (ptr_t)base) - 1))
280 /* We could try to decipher this partially. */
281 /* For now we just punt. */
283 case GC_DS_PER_OBJECT:
284 if ((signed_word)descr >= 0) {
285 descr = *(word *)((ptr_t)base + (descr & ~GC_DS_TAGS));
287 ptr_t type_descr = *(ptr_t *)base;
288 descr = *(word *)(type_descr
289 - (descr - (GC_DS_PER_OBJECT
290 - GC_INDIR_PER_OBJ_BIAS)));
298 (*GC_is_visible_print_proc)((ptr_t)p);
303 GC_PTR GC_pre_incr (p, how_much)
308 GC_PTR result = GC_same_obj((GC_PTR)((word)initial + how_much), initial);
310 if (!GC_all_interior_pointers) {
311 (void) GC_is_valid_displacement(result);
313 return (*p = result);
316 GC_PTR GC_post_incr (p, how_much)
321 GC_PTR result = GC_same_obj((GC_PTR)((word)initial + how_much), initial);
323 if (!GC_all_interior_pointers) {
324 (void) GC_is_valid_displacement(result);