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)
46 #if defined(__WATCOMC__) && defined(GC_DLL)
48 # define GC_API extern __declspec(dllexport)
50 # define GC_API extern __declspec(dllimport)
58 # if defined(__STDC__) || defined(__cplusplus)
59 # define GC_PROTO(args) args
60 typedef void * GC_PTR;
62 # define GC_PROTO(args) ()
63 typedef char * GC_PTR;
71 /* Define word and signed_word to be unsigned and signed types of the */
72 /* size as char * or void *. There seems to be no way to do this */
73 /* even semi-portably. The following is probably no better/worse */
74 /* than almost anything else. */
75 /* The ANSI standard suggests that size_t and ptr_diff_t might be */
76 /* better choices. But those appear to have incorrect definitions */
77 /* on may systems. Notably "typedef int size_t" seems to be both */
78 /* frequent and WRONG. */
79 typedef unsigned long GC_word;
80 typedef long GC_signed_word;
82 /* Public read-only variables */
84 GC_API GC_word GC_gc_no;/* Counter incremented per collection. */
85 /* Includes empty GCs at startup. */
88 /* Public R/W variables */
90 GC_API GC_PTR (*GC_oom_fn) GC_PROTO((size_t bytes_requested));
91 /* When there is insufficient memory to satisfy */
92 /* an allocation request, we return */
93 /* (*GC_oom_fn)(). By default this just */
95 /* If it returns, it must return 0 or a valid */
96 /* pointer to a previously allocated heap */
99 GC_API int GC_quiet; /* Disable statistics output. Only matters if */
100 /* collector has been compiled with statistics */
101 /* enabled. This involves a performance cost, */
102 /* and is thus not the default. */
104 GC_API int GC_dont_gc; /* Dont collect unless explicitly requested, e.g. */
105 /* because it's not safe. */
107 GC_API int GC_dont_expand;
108 /* Dont expand heap unless explicitly requested */
111 GC_API int GC_full_freq; /* Number of partial collections between */
112 /* full collections. Matters only if */
113 /* GC_incremental is set. */
115 GC_API GC_word GC_non_gc_bytes;
116 /* Bytes not considered candidates for collection. */
117 /* Used only to control scheduling of collections. */
119 GC_API GC_word GC_free_space_divisor;
120 /* We try to make sure that we allocate at */
121 /* least N/GC_free_space_divisor bytes between */
122 /* collections, where N is the heap size plus */
123 /* a rough estimate of the root set size. */
124 /* Initially, GC_free_space_divisor = 4. */
125 /* Increasing its value will use less space */
126 /* but more collection time. Decreasing it */
127 /* will appreciably decrease collection time */
128 /* at the expense of space. */
129 /* GC_free_space_divisor = 1 will effectively */
130 /* disable collections. */
132 GC_API GC_word GC_max_retries;
133 /* The maximum number of GCs attempted before */
134 /* reporting out of memory after heap */
135 /* expansion fails. Initially 0. */
138 GC_API char *GC_stackbottom; /* Cool end of user stack. */
139 /* May be set in the client prior to */
140 /* calling any GC_ routines. This */
141 /* avoids some overhead, and */
142 /* potentially some signals that can */
143 /* confuse debuggers. Otherwise the */
144 /* collector attempts to set it */
146 /* For multithreaded code, this is the */
147 /* cold end of the stack for the */
148 /* primordial thread. */
150 /* Public procedures */
152 * general purpose allocation routines, with roughly malloc calling conv.
153 * The atomic versions promise that no relevant pointers are contained
154 * in the object. The nonatomic versions guarantee that the new object
155 * is cleared. GC_malloc_stubborn promises that no changes to the object
156 * will occur after GC_end_stubborn_change has been called on the
157 * result of GC_malloc_stubborn. GC_malloc_uncollectable allocates an object
158 * that is scanned for pointers to collectable objects, but is not itself
159 * collectable. GC_malloc_uncollectable and GC_free called on the resulting
160 * object implicitly update GC_non_gc_bytes appropriately.
162 GC_API GC_PTR GC_malloc GC_PROTO((size_t size_in_bytes));
163 GC_API GC_PTR GC_malloc_atomic GC_PROTO((size_t size_in_bytes));
164 GC_API GC_PTR GC_malloc_uncollectable GC_PROTO((size_t size_in_bytes));
165 GC_API GC_PTR GC_malloc_stubborn GC_PROTO((size_t size_in_bytes));
167 /* The following is only defined if the library has been suitably */
169 GC_API GC_PTR GC_malloc_atomic_uncollectable GC_PROTO((size_t size_in_bytes));
171 /* Explicitly deallocate an object. Dangerous if used incorrectly. */
172 /* Requires a pointer to the base of an object. */
173 /* If the argument is stubborn, it should not be changeable when freed. */
174 /* An object should not be enable for finalization when it is */
175 /* explicitly deallocated. */
176 /* GC_free(0) is a no-op, as required by ANSI C for free. */
177 GC_API void GC_free GC_PROTO((GC_PTR object_addr));
180 * Stubborn objects may be changed only if the collector is explicitly informed.
181 * The collector is implicitly informed of coming change when such
182 * an object is first allocated. The following routines inform the
183 * collector that an object will no longer be changed, or that it will
184 * once again be changed. Only nonNIL pointer stores into the object
185 * are considered to be changes. The argument to GC_end_stubborn_change
186 * must be exacly the value returned by GC_malloc_stubborn or passed to
187 * GC_change_stubborn. (In the second case it may be an interior pointer
188 * within 512 bytes of the beginning of the objects.)
189 * There is a performance penalty for allowing more than
190 * one stubborn object to be changed at once, but it is acceptable to
191 * do so. The same applies to dropping stubborn objects that are still
194 GC_API void GC_change_stubborn GC_PROTO((GC_PTR));
195 GC_API void GC_end_stubborn_change GC_PROTO((GC_PTR));
197 /* Return a pointer to the base (lowest address) of an object given */
198 /* a pointer to a location within the object. */
199 /* Return 0 if displaced_pointer doesn't point to within a valid */
201 GC_API GC_PTR GC_base GC_PROTO((GC_PTR displaced_pointer));
203 /* Given a pointer to the base of an object, return its size in bytes. */
204 /* The returned size may be slightly larger than what was originally */
206 GC_API size_t GC_size GC_PROTO((GC_PTR object_addr));
208 /* For compatibility with C library. This is occasionally faster than */
209 /* a malloc followed by a bcopy. But if you rely on that, either here */
210 /* or with the standard C library, your code is broken. In my */
211 /* opinion, it shouldn't have been invented, but now we're stuck. -HB */
212 /* The resulting object has the same kind as the original. */
213 /* If the argument is stubborn, the result will have changes enabled. */
214 /* It is an error to have changes enabled for the original object. */
215 /* Follows ANSI comventions for NULL old_object. */
216 GC_API GC_PTR GC_realloc
217 GC_PROTO((GC_PTR old_object, size_t new_size_in_bytes));
219 /* Explicitly increase the heap size. */
220 /* Returns 0 on failure, 1 on success. */
221 GC_API int GC_expand_hp GC_PROTO((size_t number_of_bytes));
223 /* Limit the heap size to n bytes. Useful when you're debugging, */
224 /* especially on systems that don't handle running out of memory well. */
225 /* n == 0 ==> unbounded. This is the default. */
226 GC_API void GC_set_max_heap_size GC_PROTO((GC_word n));
228 /* Inform the collector that a certain section of statically allocated */
229 /* memory contains no pointers to garbage collected memory. Thus it */
230 /* need not be scanned. This is sometimes important if the application */
231 /* maps large read/write files into the address space, which could be */
232 /* mistaken for dynamic library data segments on some systems. */
233 GC_API void GC_exclude_static_roots GC_PROTO((GC_PTR start, GC_PTR finish));
235 /* Clear the set of root segments. Wizards only. */
236 GC_API void GC_clear_roots GC_PROTO((void));
238 /* Add a root segment. Wizards only. */
239 GC_API void GC_add_roots GC_PROTO((char * low_address,
240 char * high_address_plus_1));
242 /* Add a displacement to the set of those considered valid by the */
243 /* collector. GC_register_displacement(n) means that if p was returned */
244 /* by GC_malloc, then (char *)p + n will be considered to be a valid */
245 /* pointer to n. N must be small and less than the size of p. */
246 /* (All pointers to the interior of objects from the stack are */
247 /* considered valid in any case. This applies to heap objects and */
249 /* Preferably, this should be called before any other GC procedures. */
250 /* Calling it later adds to the probability of excess memory */
252 /* This is a no-op if the collector was compiled with recognition of */
253 /* arbitrary interior pointers enabled, which is now the default. */
254 GC_API void GC_register_displacement GC_PROTO((GC_word n));
256 /* The following version should be used if any debugging allocation is */
258 GC_API void GC_debug_register_displacement GC_PROTO((GC_word n));
260 /* Explicitly trigger a full, world-stop collection. */
261 GC_API void GC_gcollect GC_PROTO((void));
263 /* Trigger a full world-stopped collection. Abort the collection if */
264 /* and when stop_func returns a nonzero value. Stop_func will be */
265 /* called frequently, and should be reasonably fast. This works even */
266 /* if virtual dirty bits, and hence incremental collection is not */
267 /* available for this architecture. Collections can be aborted faster */
268 /* than normal pause times for incremental collection. However, */
269 /* aborted collections do no useful work; the next collection needs */
270 /* to start from the beginning. */
271 /* Return 0 if the collection was aborted, 1 if it succeeded. */
272 typedef int (* GC_stop_func) GC_PROTO((void));
273 GC_API int GC_try_to_collect GC_PROTO((GC_stop_func stop_func));
275 /* Return the number of bytes in the heap. Excludes collector private */
276 /* data structures. Includes empty blocks and fragmentation loss. */
277 /* Includes some pages that were allocated but never written. */
278 GC_API size_t GC_get_heap_size GC_PROTO((void));
280 /* Return the number of bytes allocated since the last collection. */
281 GC_API size_t GC_get_bytes_since_gc GC_PROTO((void));
283 /* Enable incremental/generational collection. */
284 /* Not advisable unless dirty bits are */
285 /* available or most heap objects are */
286 /* pointerfree(atomic) or immutable. */
287 /* Don't use in leak finding mode. */
288 /* Ignored if GC_dont_gc is true. */
289 GC_API void GC_enable_incremental GC_PROTO((void));
291 /* Perform some garbage collection work, if appropriate. */
292 /* Return 0 if there is no more work to be done. */
293 /* Typically performs an amount of work corresponding roughly */
294 /* to marking from one page. May do more work if further */
295 /* progress requires it, e.g. if incremental collection is */
296 /* disabled. It is reasonable to call this in a wait loop */
297 /* until it returns 0. */
298 GC_API int GC_collect_a_little GC_PROTO((void));
300 /* Allocate an object of size lb bytes. The client guarantees that */
301 /* as long as the object is live, it will be referenced by a pointer */
302 /* that points to somewhere within the first 256 bytes of the object. */
303 /* (This should normally be declared volatile to prevent the compiler */
304 /* from invalidating this assertion.) This routine is only useful */
305 /* if a large array is being allocated. It reduces the chance of */
306 /* accidentally retaining such an array as a result of scanning an */
307 /* integer that happens to be an address inside the array. (Actually, */
308 /* it reduces the chance of the allocator not finding space for such */
309 /* an array, since it will try hard to avoid introducing such a false */
310 /* reference.) On a SunOS 4.X or MS Windows system this is recommended */
311 /* for arrays likely to be larger than 100K or so. For other systems, */
312 /* or if the collector is not configured to recognize all interior */
313 /* pointers, the threshold is normally much higher. */
314 GC_API GC_PTR GC_malloc_ignore_off_page GC_PROTO((size_t lb));
315 GC_API GC_PTR GC_malloc_atomic_ignore_off_page GC_PROTO((size_t lb));
317 #if defined(__sgi) && !defined(__GNUC__) && _COMPILER_VERSION >= 720
318 # define GC_ADD_CALLER
319 # define GC_RETURN_ADDR (GC_word)__return_address
323 # define GC_EXTRAS GC_RETURN_ADDR, __FILE__, __LINE__
324 # define GC_EXTRA_PARAMS GC_word ra, char * descr_string, int descr_int
326 # define GC_EXTRAS __FILE__, __LINE__
327 # define GC_EXTRA_PARAMS char * descr_string, int descr_int
330 /* Debugging (annotated) allocation. GC_gcollect will check */
331 /* objects allocated in this way for overwrites, etc. */
332 GC_API GC_PTR GC_debug_malloc
333 GC_PROTO((size_t size_in_bytes, GC_EXTRA_PARAMS));
334 GC_API GC_PTR GC_debug_malloc_atomic
335 GC_PROTO((size_t size_in_bytes, GC_EXTRA_PARAMS));
336 GC_API GC_PTR GC_debug_malloc_uncollectable
337 GC_PROTO((size_t size_in_bytes, GC_EXTRA_PARAMS));
338 GC_API GC_PTR GC_debug_malloc_stubborn
339 GC_PROTO((size_t size_in_bytes, GC_EXTRA_PARAMS));
340 GC_API void GC_debug_free GC_PROTO((GC_PTR object_addr));
341 GC_API GC_PTR GC_debug_realloc
342 GC_PROTO((GC_PTR old_object, size_t new_size_in_bytes,
345 GC_API void GC_debug_change_stubborn GC_PROTO((GC_PTR));
346 GC_API void GC_debug_end_stubborn_change GC_PROTO((GC_PTR));
348 # define GC_MALLOC(sz) GC_debug_malloc(sz, GC_EXTRAS)
349 # define GC_MALLOC_ATOMIC(sz) GC_debug_malloc_atomic(sz, GC_EXTRAS)
350 # define GC_MALLOC_UNCOLLECTABLE(sz) GC_debug_malloc_uncollectable(sz, \
352 # define GC_REALLOC(old, sz) GC_debug_realloc(old, sz, GC_EXTRAS)
353 # define GC_FREE(p) GC_debug_free(p)
354 # define GC_REGISTER_FINALIZER(p, f, d, of, od) \
355 GC_debug_register_finalizer(p, f, d, of, od)
356 # define GC_REGISTER_FINALIZER_IGNORE_SELF(p, f, d, of, od) \
357 GC_debug_register_finalizer_ignore_self(p, f, d, of, od)
358 # define GC_MALLOC_STUBBORN(sz) GC_debug_malloc_stubborn(sz, GC_EXTRAS);
359 # define GC_CHANGE_STUBBORN(p) GC_debug_change_stubborn(p)
360 # define GC_END_STUBBORN_CHANGE(p) GC_debug_end_stubborn_change(p)
361 # define GC_GENERAL_REGISTER_DISAPPEARING_LINK(link, obj) \
362 GC_general_register_disappearing_link(link, GC_base(obj))
363 # define GC_REGISTER_DISPLACEMENT(n) GC_debug_register_displacement(n)
365 # define GC_MALLOC(sz) GC_malloc(sz)
366 # define GC_MALLOC_ATOMIC(sz) GC_malloc_atomic(sz)
367 # define GC_MALLOC_UNCOLLECTABLE(sz) GC_malloc_uncollectable(sz)
368 # define GC_REALLOC(old, sz) GC_realloc(old, sz)
369 # define GC_FREE(p) GC_free(p)
370 # define GC_REGISTER_FINALIZER(p, f, d, of, od) \
371 GC_register_finalizer(p, f, d, of, od)
372 # define GC_REGISTER_FINALIZER_IGNORE_SELF(p, f, d, of, od) \
373 GC_register_finalizer_ignore_self(p, f, d, of, od)
374 # define GC_MALLOC_STUBBORN(sz) GC_malloc_stubborn(sz)
375 # define GC_CHANGE_STUBBORN(p) GC_change_stubborn(p)
376 # define GC_END_STUBBORN_CHANGE(p) GC_end_stubborn_change(p)
377 # define GC_GENERAL_REGISTER_DISAPPEARING_LINK(link, obj) \
378 GC_general_register_disappearing_link(link, obj)
379 # define GC_REGISTER_DISPLACEMENT(n) GC_register_displacement(n)
381 /* The following are included because they are often convenient, and */
382 /* reduce the chance for a misspecifed size argument. But calls may */
383 /* expand to something syntactically incorrect if t is a complicated */
384 /* type expression. */
385 # define GC_NEW(t) (t *)GC_MALLOC(sizeof (t))
386 # define GC_NEW_ATOMIC(t) (t *)GC_MALLOC_ATOMIC(sizeof (t))
387 # define GC_NEW_STUBBORN(t) (t *)GC_MALLOC_STUBBORN(sizeof (t))
388 # define GC_NEW_UNCOLLECTABLE(t) (t *)GC_MALLOC_UNCOLLECTABLE(sizeof (t))
390 /* Finalization. Some of these primitives are grossly unsafe. */
391 /* The idea is to make them both cheap, and sufficient to build */
392 /* a safer layer, closer to PCedar finalization. */
393 /* The interface represents my conclusions from a long discussion */
394 /* with Alan Demers, Dan Greene, Carl Hauser, Barry Hayes, */
395 /* Christian Jacobi, and Russ Atkinson. It's not perfect, and */
396 /* probably nobody else agrees with it. Hans-J. Boehm 3/13/92 */
397 typedef void (*GC_finalization_proc)
398 GC_PROTO((GC_PTR obj, GC_PTR client_data));
400 GC_API void GC_register_finalizer
401 GC_PROTO((GC_PTR obj, GC_finalization_proc fn, GC_PTR cd,
402 GC_finalization_proc *ofn, GC_PTR *ocd));
403 GC_API void GC_debug_register_finalizer
404 GC_PROTO((GC_PTR obj, GC_finalization_proc fn, GC_PTR cd,
405 GC_finalization_proc *ofn, GC_PTR *ocd));
406 /* When obj is no longer accessible, invoke */
407 /* (*fn)(obj, cd). If a and b are inaccessible, and */
408 /* a points to b (after disappearing links have been */
409 /* made to disappear), then only a will be */
410 /* finalized. (If this does not create any new */
411 /* pointers to b, then b will be finalized after the */
412 /* next collection.) Any finalizable object that */
413 /* is reachable from itself by following one or more */
414 /* pointers will not be finalized (or collected). */
415 /* Thus cycles involving finalizable objects should */
416 /* be avoided, or broken by disappearing links. */
417 /* All but the last finalizer registered for an object */
419 /* Finalization may be removed by passing 0 as fn. */
420 /* Finalizers are implicitly unregistered just before */
421 /* they are invoked. */
422 /* The old finalizer and client data are stored in */
424 /* Fn is never invoked on an accessible object, */
425 /* provided hidden pointers are converted to real */
426 /* pointers only if the allocation lock is held, and */
427 /* such conversions are not performed by finalization */
429 /* If GC_register_finalizer is aborted as a result of */
430 /* a signal, the object may be left with no */
431 /* finalization, even if neither the old nor new */
432 /* finalizer were NULL. */
433 /* Obj should be the nonNULL starting address of an */
434 /* object allocated by GC_malloc or friends. */
435 /* Note that any garbage collectable object referenced */
436 /* by cd will be considered accessible until the */
437 /* finalizer is invoked. */
439 /* Another versions of the above follow. It ignores */
440 /* self-cycles, i.e. pointers from a finalizable object to */
441 /* itself. There is a stylistic argument that this is wrong, */
442 /* but it's unavoidable for C++, since the compiler may */
443 /* silently introduce these. It's also benign in that specific */
445 GC_API void GC_register_finalizer_ignore_self
446 GC_PROTO((GC_PTR obj, GC_finalization_proc fn, GC_PTR cd,
447 GC_finalization_proc *ofn, GC_PTR *ocd));
448 GC_API void GC_debug_register_finalizer_ignore_self
449 GC_PROTO((GC_PTR obj, GC_finalization_proc fn, GC_PTR cd,
450 GC_finalization_proc *ofn, GC_PTR *ocd));
452 /* The following routine may be used to break cycles between */
453 /* finalizable objects, thus causing cyclic finalizable */
454 /* objects to be finalized in the correct order. Standard */
455 /* use involves calling GC_register_disappearing_link(&p), */
456 /* where p is a pointer that is not followed by finalization */
457 /* code, and should not be considered in determining */
458 /* finalization order. */
459 GC_API int GC_register_disappearing_link GC_PROTO((GC_PTR * /* link */));
460 /* Link should point to a field of a heap allocated */
461 /* object obj. *link will be cleared when obj is */
462 /* found to be inaccessible. This happens BEFORE any */
463 /* finalization code is invoked, and BEFORE any */
464 /* decisions about finalization order are made. */
465 /* This is useful in telling the finalizer that */
466 /* some pointers are not essential for proper */
467 /* finalization. This may avoid finalization cycles. */
468 /* Note that obj may be resurrected by another */
469 /* finalizer, and thus the clearing of *link may */
470 /* be visible to non-finalization code. */
471 /* There's an argument that an arbitrary action should */
472 /* be allowed here, instead of just clearing a pointer. */
473 /* But this causes problems if that action alters, or */
474 /* examines connectivity. */
475 /* Returns 1 if link was already registered, 0 */
477 /* Only exists for backward compatibility. See below: */
479 GC_API int GC_general_register_disappearing_link
480 GC_PROTO((GC_PTR * /* link */, GC_PTR obj));
481 /* A slight generalization of the above. *link is */
482 /* cleared when obj first becomes inaccessible. This */
483 /* can be used to implement weak pointers easily and */
484 /* safely. Typically link will point to a location */
485 /* holding a disguised pointer to obj. (A pointer */
486 /* inside an "atomic" object is effectively */
487 /* disguised.) In this way soft */
488 /* pointers are broken before any object */
489 /* reachable from them are finalized. Each link */
490 /* May be registered only once, i.e. with one obj */
491 /* value. This was added after a long email discussion */
492 /* with John Ellis. */
493 /* Obj must be a pointer to the first word of an object */
494 /* we allocated. It is unsafe to explicitly deallocate */
495 /* the object containing link. Explicitly deallocating */
496 /* obj may or may not cause link to eventually be */
498 GC_API int GC_unregister_disappearing_link GC_PROTO((GC_PTR * /* link */));
499 /* Returns 0 if link was not actually registered. */
500 /* Undoes a registration by either of the above two */
503 /* Auxiliary fns to make finalization work correctly with displaced */
504 /* pointers introduced by the debugging allocators. */
505 GC_API GC_PTR GC_make_closure GC_PROTO((GC_finalization_proc fn, GC_PTR data));
506 GC_API void GC_debug_invoke_finalizer GC_PROTO((GC_PTR obj, GC_PTR data));
508 GC_API int GC_invoke_finalizers GC_PROTO((void));
509 /* Run finalizers for all objects that are ready to */
510 /* be finalized. Return the number of finalizers */
511 /* that were run. Normally this is also called */
512 /* implicitly during some allocations. If */
513 /* FINALIZE_ON_DEMAND is defined, it must be called */
516 /* GC_set_warn_proc can be used to redirect or filter warning messages. */
517 /* p may not be a NULL pointer. */
518 typedef void (*GC_warn_proc) GC_PROTO((char *msg, GC_word arg));
519 GC_API GC_warn_proc GC_set_warn_proc GC_PROTO((GC_warn_proc p));
520 /* Returns old warning procedure. */
522 /* The following is intended to be used by a higher level */
523 /* (e.g. cedar-like) finalization facility. It is expected */
524 /* that finalization code will arrange for hidden pointers to */
525 /* disappear. Otherwise objects can be accessed after they */
526 /* have been collected. */
527 /* Note that putting pointers in atomic objects or in */
528 /* nonpointer slots of "typed" objects is equivalent to */
529 /* disguising them in this way, and may have other advantages. */
530 # if defined(I_HIDE_POINTERS) || defined(GC_I_HIDE_POINTERS)
531 typedef GC_word GC_hidden_pointer;
532 # define HIDE_POINTER(p) (~(GC_hidden_pointer)(p))
533 # define REVEAL_POINTER(p) ((GC_PTR)(HIDE_POINTER(p)))
534 /* Converting a hidden pointer to a real pointer requires verifying */
535 /* that the object still exists. This involves acquiring the */
536 /* allocator lock to avoid a race with the collector. */
537 # endif /* I_HIDE_POINTERS */
539 typedef GC_PTR (*GC_fn_type) GC_PROTO((GC_PTR client_data));
540 GC_API GC_PTR GC_call_with_alloc_lock
541 GC_PROTO((GC_fn_type fn, GC_PTR client_data));
543 /* Check that p and q point to the same object. */
544 /* Fail conspicuously if they don't. */
545 /* Returns the first argument. */
546 /* Succeeds if neither p nor q points to the heap. */
547 /* May succeed if both p and q point to between heap objects. */
548 GC_API GC_PTR GC_same_obj GC_PROTO((GC_PTR p, GC_PTR q));
550 /* Checked pointer pre- and post- increment operations. Note that */
551 /* the second argument is in units of bytes, not multiples of the */
552 /* object size. This should either be invoked from a macro, or the */
553 /* call should be automatically generated. */
554 GC_API GC_PTR GC_pre_incr GC_PROTO((GC_PTR *p, size_t how_much));
555 GC_API GC_PTR GC_post_incr GC_PROTO((GC_PTR *p, size_t how_much));
557 /* Check that p is visible */
558 /* to the collector as a possibly pointer containing location. */
559 /* If it isn't fail conspicuously. */
560 /* Returns the argument in all cases. May erroneously succeed */
561 /* in hard cases. (This is intended for debugging use with */
562 /* untyped allocations. The idea is that it should be possible, though */
563 /* slow, to add such a call to all indirect pointer stores.) */
564 /* Currently useless for multithreaded worlds. */
565 GC_API GC_PTR GC_is_visible GC_PROTO((GC_PTR p));
567 /* Check that if p is a pointer to a heap page, then it points to */
568 /* a valid displacement within a heap object. */
569 /* Fail conspicuously if this property does not hold. */
570 /* Uninteresting with ALL_INTERIOR_POINTERS. */
571 /* Always returns its argument. */
572 GC_API GC_PTR GC_is_valid_displacement GC_PROTO((GC_PTR p));
574 /* Safer, but slow, pointer addition. Probably useful mainly with */
575 /* a preprocessor. Useful only for heap pointers. */
577 # define GC_PTR_ADD3(x, n, type_of_result) \
578 ((type_of_result)GC_same_obj((x)+(n), (x)))
579 # define GC_PRE_INCR3(x, n, type_of_result) \
580 ((type_of_result)GC_pre_incr(&(x), (n)*sizeof(*x))
581 # define GC_POST_INCR2(x, type_of_result) \
582 ((type_of_result)GC_post_incr(&(x), sizeof(*x))
584 # define GC_PTR_ADD(x, n) \
585 GC_PTR_ADD3(x, n, typeof(x))
586 # define GC_PRE_INCR(x, n) \
587 GC_PRE_INCR3(x, n, typeof(x))
588 # define GC_POST_INCR(x, n) \
589 GC_POST_INCR3(x, typeof(x))
591 /* We can't do this right without typeof, which ANSI */
592 /* decided was not sufficiently useful. Repeatedly */
593 /* mentioning the arguments seems too dangerous to be */
594 /* useful. So does not casting the result. */
595 # define GC_PTR_ADD(x, n) ((x)+(n))
597 #else /* !GC_DEBUG */
598 # define GC_PTR_ADD3(x, n, type_of_result) ((x)+(n))
599 # define GC_PTR_ADD(x, n) ((x)+(n))
600 # define GC_PRE_INCR3(x, n, type_of_result) ((x) += (n))
601 # define GC_PRE_INCR(x, n) ((x) += (n))
602 # define GC_POST_INCR2(x, n, type_of_result) ((x)++)
603 # define GC_POST_INCR(x, n) ((x)++)
606 /* Safer assignment of a pointer to a nonstack location. */
609 # define GC_PTR_STORE(p, q) \
610 (*(void **)GC_is_visible(p) = GC_is_valid_displacement(q))
612 # define GC_PTR_STORE(p, q) \
613 (*(char **)GC_is_visible(p) = GC_is_valid_displacement(q))
615 #else /* !GC_DEBUG */
616 # define GC_PTR_STORE(p, q) *((p) = (q))
619 /* Fynctions called to report pointer checking errors */
620 GC_API void (*GC_same_obj_print_proc) GC_PROTO((GC_PTR p, GC_PTR q));
622 GC_API void (*GC_is_valid_displacement_print_proc)
623 GC_PROTO((GC_PTR p));
625 GC_API void (*GC_is_visible_print_proc)
626 GC_PROTO((GC_PTR p));
628 #if defined(_SOLARIS_PTHREADS) && !defined(SOLARIS_THREADS)
629 # define SOLARIS_THREADS
632 #ifdef SOLARIS_THREADS
633 /* We need to intercept calls to many of the threads primitives, so */
634 /* that we can locate thread stacks and stop the world. */
635 /* Note also that the collector cannot see thread specific data. */
636 /* Thread specific data should generally consist of pointers to */
637 /* uncollectable objects, which are deallocated using the destructor */
638 /* facility in thr_keycreate. */
641 int GC_thr_create(void *stack_base, size_t stack_size,
642 void *(*start_routine)(void *), void *arg, long flags,
643 thread_t *new_thread);
644 int GC_thr_join(thread_t wait_for, thread_t *departed, void **status);
645 int GC_thr_suspend(thread_t target_thread);
646 int GC_thr_continue(thread_t target_thread);
647 void * GC_dlopen(const char *path, int mode);
649 # ifdef _SOLARIS_PTHREADS
650 # include <pthread.h>
651 extern int GC_pthread_create(pthread_t *new_thread,
652 const pthread_attr_t *attr,
653 void * (*thread_execp)(void *), void *arg);
654 extern int GC_pthread_join(pthread_t wait_for, void **status);
658 # define pthread_join GC_pthread_join
659 # define pthread_create GC_pthread_create
662 # define thr_create GC_thr_create
663 # define thr_join GC_thr_join
664 # define thr_suspend GC_thr_suspend
665 # define thr_continue GC_thr_continue
666 # define dlopen GC_dlopen
668 # endif /* SOLARIS_THREADS */
671 #if defined(IRIX_THREADS) || defined(LINUX_THREADS)
672 /* We treat these similarly. */
673 # include <pthread.h>
676 int GC_pthread_create(pthread_t *new_thread,
677 const pthread_attr_t *attr,
678 void *(*start_routine)(void *), void *arg);
679 int GC_pthread_sigmask(int how, const sigset_t *set, sigset_t *oset);
680 int GC_pthread_join(pthread_t thread, void **retval);
682 # define pthread_create GC_pthread_create
683 # define pthread_sigmask GC_pthread_sigmask
684 # define pthread_join GC_pthread_join
686 #endif /* IRIX_THREADS || LINUX_THREADS */
688 # if defined(PCR) || defined(SOLARIS_THREADS) || defined(WIN32_THREADS) || \
689 defined(IRIX_THREADS) || defined(LINUX_THREADS) || \
690 defined(IRIX_JDK_THREADS)
691 /* Any flavor of threads except SRC_M3. */
692 /* This returns a list of objects, linked through their first */
693 /* word. Its use can greatly reduce lock contention problems, since */
694 /* the allocation lock can be acquired and released many fewer times. */
695 GC_PTR GC_malloc_many(size_t lb);
696 #define GC_NEXT(p) (*(GC_PTR *)(p)) /* Retrieve the next element */
697 /* in returned list. */
698 extern void GC_thr_init(); /* Needed for Solaris/X86 */
700 #endif /* THREADS && !SRC_M3 */
703 * If you are planning on putting
704 * the collector in a SunOS 5 dynamic library, you need to call GC_INIT()
705 * from the statically loaded program section.
706 * This circumvents a Solaris 2.X (X<=4) linker bug.
708 #if defined(sparc) || defined(__sparc)
709 # define GC_INIT() { extern end, etext; \
710 GC_noop(&end, &etext); }
712 # if defined(__CYGWIN32__) && defined(GC_USE_DLL)
714 * Similarly gnu-win32 DLLs need explicit initialization
716 # define GC_INIT() { GC_add_roots(DATASTART, DATAEND); }
722 #if (defined(_MSDOS) || defined(_MSC_VER)) && (_M_IX86 >= 300) \
724 /* win32S may not free all resources on process exit. */
725 /* This explicitly deallocates the heap. */
726 GC_API void GC_win32_free_heap ();
730 } /* end of extern "C" */
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