2 * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
3 * Copyright (c) 1991-1995 by Xerox Corporation. All rights reserved.
4 * Copyright 1996 by Silicon Graphics. All rights reserved.
6 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
7 * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
9 * Permission is hereby granted to use or copy this program
10 * for any purpose, provided the above notices are retained on all copies.
11 * Permission to modify the code and to distribute modified code is granted,
12 * provided the above notices are retained, and a notice that the code was
13 * modified is included with the above copyright notice.
17 * Note that this defines a large number of tuning hooks, which can
18 * safely be ignored in nearly all cases. For normal use it suffices
19 * to call only GC_MALLOC and perhaps GC_REALLOC.
20 * For better performance, also look at GC_MALLOC_ATOMIC, and
21 * GC_enable_incremental. If you need an action to be performed
22 * immediately before an object is collected, look at GC_register_finalizer.
23 * If you are using Solaris threads, look at the end of this file.
24 * Everything else is best ignored unless you encounter performance
34 #if defined(__CYGWIN32__) && defined(GC_USE_DLL)
35 #include "libgc_globals.h"
38 #if defined(_MSC_VER) && defined(_DLL)
40 #define GC_API __declspec(dllexport)
42 #define GC_API __declspec(dllimport)
50 # if defined(__STDC__) || defined(__cplusplus)
51 # define GC_PROTO(args) args
52 typedef void * GC_PTR;
54 # define GC_PROTO(args) ()
55 typedef char * GC_PTR;
63 /* Define word and signed_word to be unsigned and signed types of the */
64 /* size as char * or void *. There seems to be no way to do this */
65 /* even semi-portably. The following is probably no better/worse */
66 /* than almost anything else. */
67 /* The ANSI standard suggests that size_t and ptr_diff_t might be */
68 /* better choices. But those appear to have incorrect definitions */
69 /* on may systems. Notably "typedef int size_t" seems to be both */
70 /* frequent and WRONG. */
71 typedef unsigned long GC_word;
72 typedef long GC_signed_word;
74 /* Public read-only variables */
76 GC_API GC_word GC_gc_no;/* Counter incremented per collection. */
77 /* Includes empty GCs at startup. */
80 /* Public R/W variables */
82 GC_API GC_PTR (*GC_oom_fn) GC_PROTO((size_t bytes_requested));
83 /* When there is insufficient memory to satisfy */
84 /* an allocation request, we return */
85 /* (*GC_oom_fn)(). By default this just */
87 /* If it returns, it must return 0 or a valid */
88 /* pointer to a previously allocated heap */
91 GC_API int GC_quiet; /* Disable statistics output. Only matters if */
92 /* collector has been compiled with statistics */
93 /* enabled. This involves a performance cost, */
94 /* and is thus not the default. */
96 GC_API int GC_dont_gc; /* Dont collect unless explicitly requested, e.g. */
97 /* because it's not safe. */
99 GC_API int GC_dont_expand;
100 /* Dont expand heap unless explicitly requested */
103 GC_API int GC_full_freq; /* Number of partial collections between */
104 /* full collections. Matters only if */
105 /* GC_incremental is set. */
107 GC_API GC_word GC_non_gc_bytes;
108 /* Bytes not considered candidates for collection. */
109 /* Used only to control scheduling of collections. */
111 GC_API GC_word GC_free_space_divisor;
112 /* We try to make sure that we allocate at */
113 /* least N/GC_free_space_divisor bytes between */
114 /* collections, where N is the heap size plus */
115 /* a rough estimate of the root set size. */
116 /* Initially, GC_free_space_divisor = 4. */
117 /* Increasing its value will use less space */
118 /* but more collection time. Decreasing it */
119 /* will appreciably decrease collection time */
120 /* at the expense of space. */
121 /* GC_free_space_divisor = 1 will effectively */
122 /* disable collections. */
124 GC_API GC_word GC_max_retries;
125 /* The maximum number of GCs attempted before */
126 /* reporting out of memory after heap */
127 /* expansion fails. Initially 0. */
130 /* Public procedures */
132 * general purpose allocation routines, with roughly malloc calling conv.
133 * The atomic versions promise that no relevant pointers are contained
134 * in the object. The nonatomic versions guarantee that the new object
135 * is cleared. GC_malloc_stubborn promises that no changes to the object
136 * will occur after GC_end_stubborn_change has been called on the
137 * result of GC_malloc_stubborn. GC_malloc_uncollectable allocates an object
138 * that is scanned for pointers to collectable objects, but is not itself
139 * collectable. GC_malloc_uncollectable and GC_free called on the resulting
140 * object implicitly update GC_non_gc_bytes appropriately.
142 GC_API GC_PTR GC_malloc GC_PROTO((size_t size_in_bytes));
143 GC_API GC_PTR GC_malloc_atomic GC_PROTO((size_t size_in_bytes));
144 GC_API GC_PTR GC_malloc_uncollectable GC_PROTO((size_t size_in_bytes));
145 GC_API GC_PTR GC_malloc_stubborn GC_PROTO((size_t size_in_bytes));
147 /* The following is only defined if the library has been suitably */
149 GC_API GC_PTR GC_malloc_atomic_uncollectable GC_PROTO((size_t size_in_bytes));
151 /* Explicitly deallocate an object. Dangerous if used incorrectly. */
152 /* Requires a pointer to the base of an object. */
153 /* If the argument is stubborn, it should not be changeable when freed. */
154 /* An object should not be enable for finalization when it is */
155 /* explicitly deallocated. */
156 /* GC_free(0) is a no-op, as required by ANSI C for free. */
157 GC_API void GC_free GC_PROTO((GC_PTR object_addr));
160 * Stubborn objects may be changed only if the collector is explicitly informed.
161 * The collector is implicitly informed of coming change when such
162 * an object is first allocated. The following routines inform the
163 * collector that an object will no longer be changed, or that it will
164 * once again be changed. Only nonNIL pointer stores into the object
165 * are considered to be changes. The argument to GC_end_stubborn_change
166 * must be exacly the value returned by GC_malloc_stubborn or passed to
167 * GC_change_stubborn. (In the second case it may be an interior pointer
168 * within 512 bytes of the beginning of the objects.)
169 * There is a performance penalty for allowing more than
170 * one stubborn object to be changed at once, but it is acceptable to
171 * do so. The same applies to dropping stubborn objects that are still
174 GC_API void GC_change_stubborn GC_PROTO((GC_PTR));
175 GC_API void GC_end_stubborn_change GC_PROTO((GC_PTR));
177 /* Return a pointer to the base (lowest address) of an object given */
178 /* a pointer to a location within the object. */
179 /* Return 0 if displaced_pointer doesn't point to within a valid */
181 GC_API GC_PTR GC_base GC_PROTO((GC_PTR displaced_pointer));
183 /* Given a pointer to the base of an object, return its size in bytes. */
184 /* The returned size may be slightly larger than what was originally */
186 GC_API size_t GC_size GC_PROTO((GC_PTR object_addr));
188 /* For compatibility with C library. This is occasionally faster than */
189 /* a malloc followed by a bcopy. But if you rely on that, either here */
190 /* or with the standard C library, your code is broken. In my */
191 /* opinion, it shouldn't have been invented, but now we're stuck. -HB */
192 /* The resulting object has the same kind as the original. */
193 /* If the argument is stubborn, the result will have changes enabled. */
194 /* It is an error to have changes enabled for the original object. */
195 /* Follows ANSI comventions for NULL old_object. */
196 GC_API GC_PTR GC_realloc GC_PROTO((GC_PTR old_object,
197 size_t new_size_in_bytes));
199 /* Explicitly increase the heap size. */
200 /* Returns 0 on failure, 1 on success. */
201 GC_API int GC_expand_hp GC_PROTO((size_t number_of_bytes));
203 /* Limit the heap size to n bytes. Useful when you're debugging, */
204 /* especially on systems that don't handle running out of memory well. */
205 /* n == 0 ==> unbounded. This is the default. */
206 GC_API void GC_set_max_heap_size GC_PROTO((GC_word n));
208 /* Inform the collector that a certain section of statically allocated */
209 /* memory contains no pointers to garbage collected memory. Thus it */
210 /* need not be scanned. This is sometimes important if the application */
211 /* maps large read/write files into the address space, which could be */
212 /* mistaken for dynamic library data segments on some systems. */
213 GC_API void GC_exclude_static_roots GC_PROTO((GC_PTR start, GC_PTR finish));
215 /* Clear the set of root segments. Wizards only. */
216 GC_API void GC_clear_roots GC_PROTO((void));
218 /* Add a root segment. Wizards only. */
219 GC_API void GC_add_roots GC_PROTO((char * low_address,
220 char * high_address_plus_1));
222 /* Add a displacement to the set of those considered valid by the */
223 /* collector. GC_register_displacement(n) means that if p was returned */
224 /* by GC_malloc, then (char *)p + n will be considered to be a valid */
225 /* pointer to n. N must be small and less than the size of p. */
226 /* (All pointers to the interior of objects from the stack are */
227 /* considered valid in any case. This applies to heap objects and */
229 /* Preferably, this should be called before any other GC procedures. */
230 /* Calling it later adds to the probability of excess memory */
232 /* This is a no-op if the collector was compiled with recognition of */
233 /* arbitrary interior pointers enabled, which is now the default. */
234 GC_API void GC_register_displacement GC_PROTO((GC_word n));
236 /* The following version should be used if any debugging allocation is */
238 GC_API void GC_debug_register_displacement GC_PROTO((GC_word n));
240 /* Explicitly trigger a full, world-stop collection. */
241 GC_API void GC_gcollect GC_PROTO((void));
243 /* Trigger a full world-stopped collection. Abort the collection if */
244 /* and when stop_func returns a nonzero value. Stop_func will be */
245 /* called frequently, and should be reasonably fast. This works even */
246 /* if virtual dirty bits, and hence incremental collection is not */
247 /* available for this architecture. Collections can be aborted faster */
248 /* than normal pause times for incremental collection. However, */
249 /* aborted collections do no useful work; the next collection needs */
250 /* to start from the beginning. */
251 typedef int (* GC_stop_func) GC_PROTO((void));
252 GC_API int GC_try_to_collect GC_PROTO((GC_stop_func stop_func));
254 /* Return the number of bytes in the heap. Excludes collector private */
255 /* data structures. Includes empty blocks and fragmentation loss. */
256 /* Includes some pages that were allocated but never written. */
257 GC_API size_t GC_get_heap_size GC_PROTO((void));
259 /* Return the number of bytes allocated since the last collection. */
260 GC_API size_t GC_get_bytes_since_gc GC_PROTO((void));
262 /* Enable incremental/generational collection. */
263 /* Not advisable unless dirty bits are */
264 /* available or most heap objects are */
265 /* pointerfree(atomic) or immutable. */
266 /* Don't use in leak finding mode. */
267 /* Ignored if GC_dont_gc is true. */
268 GC_API void GC_enable_incremental GC_PROTO((void));
270 /* Perform some garbage collection work, if appropriate. */
271 /* Return 0 if there is no more work to be done. */
272 /* Typically performs an amount of work corresponding roughly */
273 /* to marking from one page. May do more work if further */
274 /* progress requires it, e.g. if incremental collection is */
275 /* disabled. It is reasonable to call this in a wait loop */
276 /* until it returns 0. */
277 GC_API int GC_collect_a_little GC_PROTO((void));
279 /* Allocate an object of size lb bytes. The client guarantees that */
280 /* as long as the object is live, it will be referenced by a pointer */
281 /* that points to somewhere within the first 256 bytes of the object. */
282 /* (This should normally be declared volatile to prevent the compiler */
283 /* from invalidating this assertion.) This routine is only useful */
284 /* if a large array is being allocated. It reduces the chance of */
285 /* accidentally retaining such an array as a result of scanning an */
286 /* integer that happens to be an address inside the array. (Actually, */
287 /* it reduces the chance of the allocator not finding space for such */
288 /* an array, since it will try hard to avoid introducing such a false */
289 /* reference.) On a SunOS 4.X or MS Windows system this is recommended */
290 /* for arrays likely to be larger than 100K or so. For other systems, */
291 /* or if the collector is not configured to recognize all interior */
292 /* pointers, the threshold is normally much higher. */
293 GC_API GC_PTR GC_malloc_ignore_off_page GC_PROTO((size_t lb));
294 GC_API GC_PTR GC_malloc_atomic_ignore_off_page GC_PROTO((size_t lb));
296 #if defined(__sgi) && !defined(__GNUC__) && _COMPILER_VERSION >= 720
297 # define GC_ADD_CALLER
298 # define GC_RETURN_ADDR (GC_word)__return_address
302 # define GC_EXTRAS GC_RETURN_ADDR, __FILE__, __LINE__
303 # define GC_EXTRA_PARAMS GC_word ra, char * descr_string, int descr_int
305 # define GC_EXTRAS __FILE__, __LINE__
306 # define GC_EXTRA_PARAMS char * descr_string, int descr_int
309 /* Debugging (annotated) allocation. GC_gcollect will check */
310 /* objects allocated in this way for overwrites, etc. */
311 GC_API GC_PTR GC_debug_malloc
312 GC_PROTO((size_t size_in_bytes, GC_EXTRA_PARAMS));
313 GC_API GC_PTR GC_debug_malloc_atomic
314 GC_PROTO((size_t size_in_bytes, GC_EXTRA_PARAMS));
315 GC_API GC_PTR GC_debug_malloc_uncollectable
316 GC_PROTO((size_t size_in_bytes, GC_EXTRA_PARAMS));
317 GC_API GC_PTR GC_debug_malloc_stubborn
318 GC_PROTO((size_t size_in_bytes, GC_EXTRA_PARAMS));
319 GC_API void GC_debug_free GC_PROTO((GC_PTR object_addr));
320 GC_API GC_PTR GC_debug_realloc
321 GC_PROTO((GC_PTR old_object, size_t new_size_in_bytes,
324 GC_API void GC_debug_change_stubborn GC_PROTO((GC_PTR));
325 GC_API void GC_debug_end_stubborn_change GC_PROTO((GC_PTR));
327 # define GC_MALLOC(sz) GC_debug_malloc(sz, GC_EXTRAS)
328 # define GC_MALLOC_ATOMIC(sz) GC_debug_malloc_atomic(sz, GC_EXTRAS)
329 # define GC_MALLOC_UNCOLLECTABLE(sz) GC_debug_malloc_uncollectable(sz, \
331 # define GC_REALLOC(old, sz) GC_debug_realloc(old, sz, GC_EXTRAS)
332 # define GC_FREE(p) GC_debug_free(p)
333 # define GC_REGISTER_FINALIZER(p, f, d, of, od) \
334 GC_debug_register_finalizer(p, f, d, of, od)
335 # define GC_REGISTER_FINALIZER_IGNORE_SELF(p, f, d, of, od) \
336 GC_debug_register_finalizer_ignore_self(p, f, d, of, od)
337 # define GC_REGISTER_FINALIZER_NO_ORDER(p, f, d, of, od) \
338 GC_debug_register_finalizer_no_order(p, f, d, of, od)
339 # define GC_MALLOC_STUBBORN(sz) GC_debug_malloc_stubborn(sz, GC_EXTRAS);
340 # define GC_CHANGE_STUBBORN(p) GC_debug_change_stubborn(p)
341 # define GC_END_STUBBORN_CHANGE(p) GC_debug_end_stubborn_change(p)
342 # define GC_GENERAL_REGISTER_DISAPPEARING_LINK(link, obj) \
343 GC_general_register_disappearing_link(link, GC_base(obj))
344 # define GC_REGISTER_DISPLACEMENT(n) GC_debug_register_displacement(n)
346 # define GC_MALLOC(sz) GC_malloc(sz)
347 # define GC_MALLOC_ATOMIC(sz) GC_malloc_atomic(sz)
348 # define GC_MALLOC_UNCOLLECTABLE(sz) GC_malloc_uncollectable(sz)
349 # define GC_REALLOC(old, sz) GC_realloc(old, sz)
350 # define GC_FREE(p) GC_free(p)
351 # define GC_REGISTER_FINALIZER(p, f, d, of, od) \
352 GC_register_finalizer(p, f, d, of, od)
353 # define GC_REGISTER_FINALIZER_IGNORE_SELF(p, f, d, of, od) \
354 GC_register_finalizer_ignore_self(p, f, d, of, od)
355 # define GC_REGISTER_FINALIZER_NO_ORDER(p, f, d, of, od) \
356 GC_register_finalizer_no_order(p, f, d, of, od)
357 # define GC_MALLOC_STUBBORN(sz) GC_malloc_stubborn(sz)
358 # define GC_CHANGE_STUBBORN(p) GC_change_stubborn(p)
359 # define GC_END_STUBBORN_CHANGE(p) GC_end_stubborn_change(p)
360 # define GC_GENERAL_REGISTER_DISAPPEARING_LINK(link, obj) \
361 GC_general_register_disappearing_link(link, obj)
362 # define GC_REGISTER_DISPLACEMENT(n) GC_register_displacement(n)
364 /* The following are included because they are often convenient, and */
365 /* reduce the chance for a misspecifed size argument. But calls may */
366 /* expand to something syntactically incorrect if t is a complicated */
367 /* type expression. */
368 # define GC_NEW(t) (t *)GC_MALLOC(sizeof (t))
369 # define GC_NEW_ATOMIC(t) (t *)GC_MALLOC_ATOMIC(sizeof (t))
370 # define GC_NEW_STUBBORN(t) (t *)GC_MALLOC_STUBBORN(sizeof (t))
371 # define GC_NEW_UNCOLLECTABLE(t) (t *)GC_MALLOC_UNCOLLECTABLE(sizeof (t))
373 /* Finalization. Some of these primitives are grossly unsafe. */
374 /* The idea is to make them both cheap, and sufficient to build */
375 /* a safer layer, closer to PCedar finalization. */
376 /* The interface represents my conclusions from a long discussion */
377 /* with Alan Demers, Dan Greene, Carl Hauser, Barry Hayes, */
378 /* Christian Jacobi, and Russ Atkinson. It's not perfect, and */
379 /* probably nobody else agrees with it. Hans-J. Boehm 3/13/92 */
380 typedef void (*GC_finalization_proc)
381 GC_PROTO((GC_PTR obj, GC_PTR client_data));
383 GC_API void GC_register_finalizer
384 GC_PROTO((GC_PTR obj, GC_finalization_proc fn, GC_PTR cd,
385 GC_finalization_proc *ofn, GC_PTR *ocd));
386 GC_API void GC_debug_register_finalizer
387 GC_PROTO((GC_PTR obj, GC_finalization_proc fn, GC_PTR cd,
388 GC_finalization_proc *ofn, GC_PTR *ocd));
389 /* When obj is no longer accessible, invoke */
390 /* (*fn)(obj, cd). If a and b are inaccessible, and */
391 /* a points to b (after disappearing links have been */
392 /* made to disappear), then only a will be */
393 /* finalized. (If this does not create any new */
394 /* pointers to b, then b will be finalized after the */
395 /* next collection.) Any finalizable object that */
396 /* is reachable from itself by following one or more */
397 /* pointers will not be finalized (or collected). */
398 /* Thus cycles involving finalizable objects should */
399 /* be avoided, or broken by disappearing links. */
400 /* All but the last finalizer registered for an object */
402 /* Finalization may be removed by passing 0 as fn. */
403 /* Finalizers are implicitly unregistered just before */
404 /* they are invoked. */
405 /* The old finalizer and client data are stored in */
407 /* Fn is never invoked on an accessible object, */
408 /* provided hidden pointers are converted to real */
409 /* pointers only if the allocation lock is held, and */
410 /* such conversions are not performed by finalization */
412 /* If GC_register_finalizer is aborted as a result of */
413 /* a signal, the object may be left with no */
414 /* finalization, even if neither the old nor new */
415 /* finalizer were NULL. */
416 /* Obj should be the nonNULL starting address of an */
417 /* object allocated by GC_malloc or friends. */
418 /* Note that any garbage collectable object referenced */
419 /* by cd will be considered accessible until the */
420 /* finalizer is invoked. */
422 /* Another versions of the above follow. It ignores */
423 /* self-cycles, i.e. pointers from a finalizable object to */
424 /* itself. There is a stylistic argument that this is wrong, */
425 /* but it's unavoidable for C++, since the compiler may */
426 /* silently introduce these. It's also benign in that specific */
428 GC_API void GC_register_finalizer_ignore_self
429 GC_PROTO((GC_PTR obj, GC_finalization_proc fn, GC_PTR cd,
430 GC_finalization_proc *ofn, GC_PTR *ocd));
431 GC_API void GC_debug_register_finalizer_ignore_self
432 GC_PROTO((GC_PTR obj, GC_finalization_proc fn, GC_PTR cd,
433 GC_finalization_proc *ofn, GC_PTR *ocd));
435 /* Another version of the above. It ignores all cycles. */
436 /* It should probably only be used by Java implementations. */
437 GC_API void GC_register_finalizer_no_order
438 GC_PROTO((GC_PTR obj, GC_finalization_proc fn, GC_PTR cd,
439 GC_finalization_proc *ofn, GC_PTR *ocd));
440 GC_API void GC_debug_register_finalizer_no_order
441 GC_PROTO((GC_PTR obj, GC_finalization_proc fn, GC_PTR cd,
442 GC_finalization_proc *ofn, GC_PTR *ocd));
444 /* The following routine may be used to break cycles between */
445 /* finalizable objects, thus causing cyclic finalizable */
446 /* objects to be finalized in the correct order. Standard */
447 /* use involves calling GC_register_disappearing_link(&p), */
448 /* where p is a pointer that is not followed by finalization */
449 /* code, and should not be considered in determining */
450 /* finalization order. */
451 GC_API int GC_register_disappearing_link GC_PROTO((GC_PTR * /* link */));
452 /* Link should point to a field of a heap allocated */
453 /* object obj. *link will be cleared when obj is */
454 /* found to be inaccessible. This happens BEFORE any */
455 /* finalization code is invoked, and BEFORE any */
456 /* decisions about finalization order are made. */
457 /* This is useful in telling the finalizer that */
458 /* some pointers are not essential for proper */
459 /* finalization. This may avoid finalization cycles. */
460 /* Note that obj may be resurrected by another */
461 /* finalizer, and thus the clearing of *link may */
462 /* be visible to non-finalization code. */
463 /* There's an argument that an arbitrary action should */
464 /* be allowed here, instead of just clearing a pointer. */
465 /* But this causes problems if that action alters, or */
466 /* examines connectivity. */
467 /* Returns 1 if link was already registered, 0 */
469 /* Only exists for backward compatibility. See below: */
471 GC_API int GC_general_register_disappearing_link
472 GC_PROTO((GC_PTR * /* link */, GC_PTR obj));
473 /* A slight generalization of the above. *link is */
474 /* cleared when obj first becomes inaccessible. This */
475 /* can be used to implement weak pointers easily and */
476 /* safely. Typically link will point to a location */
477 /* holding a disguised pointer to obj. (A pointer */
478 /* inside an "atomic" object is effectively */
479 /* disguised.) In this way soft */
480 /* pointers are broken before any object */
481 /* reachable from them are finalized. Each link */
482 /* May be registered only once, i.e. with one obj */
483 /* value. This was added after a long email discussion */
484 /* with John Ellis. */
485 /* Obj must be a pointer to the first word of an object */
486 /* we allocated. It is unsafe to explicitly deallocate */
487 /* the object containing link. Explicitly deallocating */
488 /* obj may or may not cause link to eventually be */
490 GC_API int GC_unregister_disappearing_link GC_PROTO((GC_PTR * /* link */));
491 /* Returns 0 if link was not actually registered. */
492 /* Undoes a registration by either of the above two */
495 /* Auxiliary fns to make finalization work correctly with displaced */
496 /* pointers introduced by the debugging allocators. */
497 GC_API GC_PTR GC_make_closure GC_PROTO((GC_finalization_proc fn, GC_PTR data));
498 GC_API void GC_debug_invoke_finalizer GC_PROTO((GC_PTR obj, GC_PTR data));
500 GC_API int GC_invoke_finalizers GC_PROTO((void));
501 /* Run finalizers for all objects that are ready to */
502 /* be finalized. Return the number of finalizers */
503 /* that were run. Normally this is also called */
504 /* implicitly during some allocations. If */
505 /* FINALIZE_ON_DEMAND is defined, it must be called */
508 /* GC_set_warn_proc can be used to redirect or filter warning messages. */
509 /* p may not be a NULL pointer. */
510 typedef void (*GC_warn_proc) GC_PROTO((char *msg, GC_word arg));
511 GC_API GC_warn_proc GC_set_warn_proc GC_PROTO((GC_warn_proc p));
512 /* Returns old warning procedure. */
514 /* The following is intended to be used by a higher level */
515 /* (e.g. cedar-like) finalization facility. It is expected */
516 /* that finalization code will arrange for hidden pointers to */
517 /* disappear. Otherwise objects can be accessed after they */
518 /* have been collected. */
519 /* Note that putting pointers in atomic objects or in */
520 /* nonpointer slots of "typed" objects is equivalent to */
521 /* disguising them in this way, and may have other advantages. */
522 # if defined(I_HIDE_POINTERS) || defined(GC_I_HIDE_POINTERS)
523 typedef GC_word GC_hidden_pointer;
524 # define HIDE_POINTER(p) (~(GC_hidden_pointer)(p))
525 # define REVEAL_POINTER(p) ((GC_PTR)(HIDE_POINTER(p)))
526 /* Converting a hidden pointer to a real pointer requires verifying */
527 /* that the object still exists. This involves acquiring the */
528 /* allocator lock to avoid a race with the collector. */
529 # endif /* I_HIDE_POINTERS */
531 typedef GC_PTR (*GC_fn_type) GC_PROTO((GC_PTR client_data));
532 GC_API GC_PTR GC_call_with_alloc_lock
533 GC_PROTO((GC_fn_type fn, GC_PTR client_data));
535 /* Check that p and q point to the same object. */
536 /* Fail conspicuously if they don't. */
537 /* Returns the first argument. */
538 /* Succeeds if neither p nor q points to the heap. */
539 /* May succeed if both p and q point to between heap objects. */
540 GC_API GC_PTR GC_same_obj GC_PROTO((GC_PTR p, GC_PTR q));
542 /* Checked pointer pre- and post- increment operations. Note that */
543 /* the second argument is in units of bytes, not multiples of the */
544 /* object size. This should either be invoked from a macro, or the */
545 /* call should be automatically generated. */
546 GC_API GC_PTR GC_pre_incr GC_PROTO((GC_PTR *p, size_t how_much));
547 GC_API GC_PTR GC_post_incr GC_PROTO((GC_PTR *p, size_t how_much));
549 /* Check that p is visible */
550 /* to the collector as a possibly pointer containing location. */
551 /* If it isn't fail conspicuously. */
552 /* Returns the argument in all cases. May erroneously succeed */
553 /* in hard cases. (This is intended for debugging use with */
554 /* untyped allocations. The idea is that it should be possible, though */
555 /* slow, to add such a call to all indirect pointer stores.) */
556 /* Currently useless for multithreaded worlds. */
557 GC_API GC_PTR GC_is_visible GC_PROTO((GC_PTR p));
559 /* Check that if p is a pointer to a heap page, then it points to */
560 /* a valid displacement within a heap object. */
561 /* Fail conspicuously if this property does not hold. */
562 /* Uninteresting with ALL_INTERIOR_POINTERS. */
563 /* Always returns its argument. */
564 GC_API GC_PTR GC_is_valid_displacement GC_PROTO((GC_PTR p));
566 /* Safer, but slow, pointer addition. Probably useful mainly with */
567 /* a preprocessor. Useful only for heap pointers. */
569 # define GC_PTR_ADD3(x, n, type_of_result) \
570 ((type_of_result)GC_same_obj((x)+(n), (x)))
571 # define GC_PRE_INCR3(x, n, type_of_result) \
572 ((type_of_result)GC_pre_incr(&(x), (n)*sizeof(*x))
573 # define GC_POST_INCR2(x, type_of_result) \
574 ((type_of_result)GC_post_incr(&(x), sizeof(*x))
576 # define GC_PTR_ADD(x, n) \
577 GC_PTR_ADD3(x, n, typeof(x))
578 # define GC_PRE_INCR(x, n) \
579 GC_PRE_INCR3(x, n, typeof(x))
580 # define GC_POST_INCR(x, n) \
581 GC_POST_INCR3(x, typeof(x))
583 /* We can't do this right without typeof, which ANSI */
584 /* decided was not sufficiently useful. Repeatedly */
585 /* mentioning the arguments seems too dangerous to be */
586 /* useful. So does not casting the result. */
587 # define GC_PTR_ADD(x, n) ((x)+(n))
589 #else /* !GC_DEBUG */
590 # define GC_PTR_ADD3(x, n, type_of_result) ((x)+(n))
591 # define GC_PTR_ADD(x, n) ((x)+(n))
592 # define GC_PRE_INCR3(x, n, type_of_result) ((x) += (n))
593 # define GC_PRE_INCR(x, n) ((x) += (n))
594 # define GC_POST_INCR2(x, n, type_of_result) ((x)++)
595 # define GC_POST_INCR(x, n) ((x)++)
598 /* Safer assignment of a pointer to a nonstack location. */
601 # define GC_PTR_STORE(p, q) \
602 (*(void **)GC_is_visible(p) = GC_is_valid_displacement(q))
604 # define GC_PTR_STORE(p, q) \
605 (*(char **)GC_is_visible(p) = GC_is_valid_displacement(q))
607 #else /* !GC_DEBUG */
608 # define GC_PTR_STORE(p, q) *((p) = (q))
611 /* Fynctions called to report pointer checking errors */
612 GC_API void (*GC_same_obj_print_proc) GC_PROTO((GC_PTR p, GC_PTR q));
614 GC_API void (*GC_is_valid_displacement_print_proc)
615 GC_PROTO((GC_PTR p));
617 GC_API void (*GC_is_visible_print_proc)
618 GC_PROTO((GC_PTR p));
620 #ifdef SOLARIS_THREADS
621 /* We need to intercept calls to many of the threads primitives, so */
622 /* that we can locate thread stacks and stop the world. */
623 /* Note also that the collector cannot see thread specific data. */
624 /* Thread specific data should generally consist of pointers to */
625 /* uncollectable objects, which are deallocated using the destructor */
626 /* facility in thr_keycreate. */
629 int GC_thr_create(void *stack_base, size_t stack_size,
630 void *(*start_routine)(void *), void *arg, long flags,
631 thread_t *new_thread);
632 int GC_thr_join(thread_t wait_for, thread_t *departed, void **status);
633 int GC_thr_suspend(thread_t target_thread);
634 int GC_thr_continue(thread_t target_thread);
635 void * GC_dlopen(const char *path, int mode);
637 # ifdef _SOLARIS_PTHREADS
638 # include <pthread.h>
639 extern int GC_pthread_create(pthread_t *new_thread,
640 const pthread_attr_t *attr,
641 void * (*thread_execp)(void *), void *arg);
642 extern int GC_pthread_join(pthread_t wait_for, void **status);
646 # define pthread_join GC_pthread_join
647 # define pthread_create GC_pthread_create
650 # define thr_create GC_thr_create
651 # define thr_join GC_thr_join
652 # define thr_suspend GC_thr_suspend
653 # define thr_continue GC_thr_continue
654 # define dlopen GC_dlopen
656 # endif /* SOLARIS_THREADS */
659 #if defined(IRIX_THREADS) || defined(LINUX_THREADS)
660 /* We treat these similarly. */
661 # include <pthread.h>
664 int GC_pthread_create(pthread_t *new_thread,
665 const pthread_attr_t *attr,
666 void *(*start_routine)(void *), void *arg);
667 int GC_pthread_sigmask(int how, const sigset_t *set, sigset_t *oset);
668 int GC_pthread_join(pthread_t thread, void **retval);
670 # define pthread_create GC_pthread_create
671 # define pthread_sigmask GC_pthread_sigmask
672 # define pthread_join GC_pthread_join
674 #endif /* IRIX_THREADS || LINUX_THREADS */
676 #if defined(THREADS) && !defined(SRC_M3)
677 /* This returns a list of objects, linked through their first */
678 /* word. Its use can greatly reduce lock contention problems, since */
679 /* the allocation lock can be acquired and released many fewer times. */
680 GC_PTR GC_malloc_many(size_t lb);
681 #define GC_NEXT(p) (*(GC_PTR *)(p)) /* Retrieve the next element */
682 /* in returned list. */
683 extern void GC_thr_init(); /* Needed for Solaris/X86 */
685 #endif /* THREADS && !SRC_M3 */
688 * If you are planning on putting
689 * the collector in a SunOS 5 dynamic library, you need to call GC_INIT()
690 * from the statically loaded program section.
691 * This circumvents a Solaris 2.X (X<=4) linker bug.
693 #if defined(sparc) || defined(__sparc)
694 # define GC_INIT() { extern end, etext; \
695 GC_noop(&end, &etext); }
697 # if defined(__CYGWIN32__) && defined(GC_USE_DLL)
699 * Similarly gnu-win32 DLLs need explicit initialization
701 # define GC_INIT() { GC_add_roots(DATASTART, DATAEND); }
708 } /* end of extern "C" */
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