2 * boehm-gc.c: GC implementation using either the installed or included Boehm GC.
7 #define GC_I_HIDE_POINTERS
8 #include <mono/os/gc_wrapper.h>
9 #include <mono/metadata/mono-gc.h>
10 #include <mono/metadata/gc-internal.h>
11 #include <mono/metadata/profiler-private.h>
12 #include <mono/metadata/class-internals.h>
13 #include <mono/metadata/method-builder.h>
14 #include <mono/metadata/opcodes.h>
15 #include <mono/utils/mono-logger.h>
19 #ifdef USE_INCLUDED_LIBGC
22 #define THREAD_LOCAL_ALLOC 1
23 #include "private/pthread_support.h"
26 #define GC_NO_DESCRIPTOR ((gpointer)(0 | GC_DS_LENGTH))
28 static gboolean gc_initialized = FALSE;
31 mono_gc_warning (char *msg, GC_word arg)
33 mono_trace (G_LOG_LEVEL_WARNING, MONO_TRACE_GC, msg, (unsigned long)arg);
37 mono_gc_base_init (void)
43 * Handle the case when we are called from a thread different from the main thread,
45 * FIXME: Move this to libgc where it belongs.
47 * we used to do this only when running on valgrind,
48 * but it happens also in other setups.
50 #if defined(HAVE_PTHREAD_GETATTR_NP) && defined(HAVE_PTHREAD_ATTR_GETSTACK)
55 pthread_getattr_np (pthread_self (), &attr);
56 pthread_attr_getstack (&attr, &sstart, &size);
57 pthread_attr_destroy (&attr);
58 /*g_print ("stackbottom pth is: %p\n", (char*)sstart + size);*/
61 * The calculation above doesn't seem to work on ia64, also we need to set
62 * GC_register_stackbottom as well, but don't know how.
65 /* apparently with some linuxthreads implementations sstart can be NULL,
66 * fallback to the more imprecise method (bug# 78096).
69 GC_stackbottom = (char*)sstart + size;
72 gsize stack_bottom = (gsize)&dummy;
74 stack_bottom &= ~4095;
75 GC_stackbottom = (char*)stack_bottom;
79 #elif defined(HAVE_PTHREAD_GET_STACKSIZE_NP) && defined(HAVE_PTHREAD_GET_STACKADDR_NP)
80 GC_stackbottom = (char*)pthread_get_stackaddr_np (pthread_self ());
84 gsize stack_bottom = (gsize)&dummy;
86 stack_bottom &= ~4095;
87 /*g_print ("stackbottom is: %p\n", (char*)stack_bottom);*/
88 GC_stackbottom = (char*)stack_bottom;
94 GC_oom_fn = mono_gc_out_of_memory;
95 GC_set_warn_proc (mono_gc_warning);
96 GC_finalize_on_demand = 1;
97 GC_finalizer_notifier = mono_gc_finalize_notify;
99 #ifdef HAVE_GC_GCJ_MALLOC
100 GC_init_gcj_malloc (5, NULL);
103 gc_initialized = TRUE;
107 mono_gc_collect (int generation)
113 mono_gc_max_generation (void)
119 mono_gc_get_generation (MonoObject *object)
125 mono_gc_collection_count (int generation)
131 mono_gc_add_memory_pressure (gint64 value)
136 mono_gc_get_used_size (void)
138 return GC_get_heap_size () - GC_get_free_bytes ();
142 mono_gc_get_heap_size (void)
144 return GC_get_heap_size ();
148 mono_gc_disable (void)
150 #ifdef HAVE_GC_ENABLE
153 g_assert_not_reached ();
158 mono_gc_enable (void)
160 #ifdef HAVE_GC_ENABLE
163 g_assert_not_reached ();
168 mono_gc_is_gc_thread (void)
170 #ifdef USE_INCLUDED_LIBGC
171 return GC_thread_is_registered ();
177 extern int GC_thread_register_foreign (void *base_addr);
180 mono_gc_register_thread (void *baseptr)
182 if (mono_gc_is_gc_thread())
184 #if defined(USE_INCLUDED_LIBGC) && !defined(PLATFORM_WIN32)
185 return GC_thread_register_foreign (baseptr);
192 mono_object_is_alive (MonoObject* o)
194 #ifdef USE_INCLUDED_LIBGC
195 return GC_is_marked ((gpointer)o);
201 #ifdef USE_INCLUDED_LIBGC
204 on_gc_notification (GCEventType event)
206 mono_profiler_gc_event ((MonoGCEvent) event, 0);
210 on_gc_heap_resize (size_t new_size)
212 mono_profiler_gc_heap_resize (new_size);
216 mono_gc_enable_events (void)
218 GC_notify_event = on_gc_notification;
219 GC_on_heap_resize = on_gc_heap_resize;
225 mono_gc_enable_events (void)
232 mono_gc_register_root (char *start, size_t size, void *descr)
234 /* for some strange reason, they want one extra byte on the end */
235 GC_add_roots (start, start + size + 1);
241 mono_gc_weak_link_add (void **link_addr, MonoObject *obj)
243 /* libgc requires that we use HIDE_POINTER... */
244 *link_addr = (void*)HIDE_POINTER (obj);
245 GC_GENERAL_REGISTER_DISAPPEARING_LINK (link_addr, obj);
249 mono_gc_weak_link_remove (void **link_addr)
251 GC_unregister_disappearing_link (link_addr);
256 mono_gc_weak_link_get (void **link_addr)
258 MonoObject *obj = REVEAL_POINTER (*link_addr);
259 if (obj == (MonoObject *) -1)
265 mono_gc_make_descr_for_string (gsize *bitmap, int numbits)
267 return mono_gc_make_descr_from_bitmap (bitmap, numbits);
271 mono_gc_make_descr_for_object (gsize *bitmap, int numbits, size_t obj_size)
273 return mono_gc_make_descr_from_bitmap (bitmap, numbits);
277 mono_gc_make_descr_for_array (int vector, gsize *elem_bitmap, int numbits, size_t elem_size)
279 /* libgc has no usable support for arrays... */
280 return GC_NO_DESCRIPTOR;
284 mono_gc_make_descr_from_bitmap (gsize *bitmap, int numbits)
286 #ifdef HAVE_GC_GCJ_MALLOC
287 /* It seems there are issues when the bitmap doesn't fit: play it safe */
289 return GC_NO_DESCRIPTOR;
291 return (gpointer)GC_make_descriptor ((GC_bitmap)bitmap, numbits);
298 mono_gc_alloc_fixed (size_t size, void *descr)
300 return GC_MALLOC (size);
304 mono_gc_free_fixed (void* addr)
309 mono_gc_invoke_finalizers (void)
311 /* There is a bug in GC_invoke_finalizer () in versions <= 6.2alpha4:
312 * the 'mem_freed' variable is not initialized when there are no
313 * objects to finalize, which leads to strange behavior later on.
314 * The check is necessary to work around that bug.
316 if (GC_should_invoke_finalizers ())
317 return GC_invoke_finalizers ();
322 mono_gc_pending_finalizers (void)
324 return GC_should_invoke_finalizers ();
328 mono_gc_wbarrier_set_field (MonoObject *obj, gpointer field_ptr, MonoObject* value)
330 *(void**)field_ptr = value;
334 mono_gc_wbarrier_set_arrayref (MonoArray *arr, gpointer slot_ptr, MonoObject* value)
336 *(void**)slot_ptr = value;
340 mono_gc_wbarrier_arrayref_copy (MonoArray *arr, gpointer slot_ptr, int count)
342 /* no need to do anything */
346 mono_gc_wbarrier_generic_store (gpointer ptr, MonoObject* value)
348 *(void**)ptr = value;
352 mono_gc_wbarrier_value_copy (gpointer dest, gpointer src, int count, MonoClass *klass)
357 mono_gc_wbarrier_object (MonoObject *object)
361 #if defined(USE_INCLUDED_LIBGC) && defined(USE_COMPILER_TLS) && defined(__linux__) && (defined(__i386__) || defined(__x86_64__))
362 extern __thread MONO_TLS_FAST void* GC_thread_tls;
363 #include "metadata-internals.h"
369 while (!(v & (1 << i)))
376 ATYPE_FREEPTR_FOR_BOX,
384 create_allocator (int atype, int offset)
386 int index_var, bytes_var, my_fl_var, my_entry_var;
387 guint32 no_freelist_branch, not_small_enough_branch = 0;
388 guint32 size_overflow_branch = 0;
389 MonoMethodBuilder *mb;
391 MonoMethodSignature *csig;
393 if (atype == ATYPE_STRING) {
394 csig = mono_metadata_signature_alloc (mono_defaults.corlib, 2);
395 csig->ret = &mono_defaults.string_class->byval_arg;
396 csig->params [0] = &mono_defaults.int_class->byval_arg;
397 csig->params [1] = &mono_defaults.int32_class->byval_arg;
399 csig = mono_metadata_signature_alloc (mono_defaults.corlib, 1);
400 csig->ret = &mono_defaults.object_class->byval_arg;
401 csig->params [0] = &mono_defaults.int_class->byval_arg;
404 mb = mono_mb_new (mono_defaults.object_class, "Alloc", MONO_WRAPPER_ALLOC);
405 bytes_var = mono_mb_add_local (mb, &mono_defaults.int32_class->byval_arg);
406 if (atype == ATYPE_STRING) {
407 /* a string alloator method takes the args: (vtable, len) */
408 /* bytes = (sizeof (MonoString) + ((len + 1) * 2)); */
409 mono_mb_emit_ldarg (mb, 1);
410 mono_mb_emit_icon (mb, 1);
411 mono_mb_emit_byte (mb, MONO_CEE_ADD);
412 mono_mb_emit_icon (mb, 1);
413 mono_mb_emit_byte (mb, MONO_CEE_SHL);
414 // sizeof (MonoString) might include padding
415 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoString, chars));
416 mono_mb_emit_byte (mb, MONO_CEE_ADD);
417 mono_mb_emit_stloc (mb, bytes_var);
419 /* bytes = vtable->klass->instance_size */
420 mono_mb_emit_ldarg (mb, 0);
421 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoVTable, klass));
422 mono_mb_emit_byte (mb, MONO_CEE_ADD);
423 mono_mb_emit_byte (mb, MONO_CEE_LDIND_I);
424 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoClass, instance_size));
425 mono_mb_emit_byte (mb, MONO_CEE_ADD);
426 /* FIXME: assert instance_size stays a 4 byte integer */
427 mono_mb_emit_byte (mb, MONO_CEE_LDIND_U4);
428 mono_mb_emit_stloc (mb, bytes_var);
431 /* this is needed for strings/arrays only as the other big types are never allocated with this method */
432 if (atype == ATYPE_STRING) {
434 /* if (!SMALL_ENOUGH (bytes)) jump slow_path;*/
435 mono_mb_emit_ldloc (mb, bytes_var);
436 mono_mb_emit_icon (mb, (NFREELISTS-1) * GRANULARITY);
437 not_small_enough_branch = mono_mb_emit_short_branch (mb, MONO_CEE_BGT_UN_S);
438 /* check for overflow */
439 mono_mb_emit_ldloc (mb, bytes_var);
440 mono_mb_emit_icon (mb, sizeof (MonoString));
441 size_overflow_branch = mono_mb_emit_short_branch (mb, MONO_CEE_BLE_UN_S);
444 /* int index = INDEX_FROM_BYTES(bytes); */
445 index_var = mono_mb_add_local (mb, &mono_defaults.int32_class->byval_arg);
447 mono_mb_emit_ldloc (mb, bytes_var);
448 mono_mb_emit_icon (mb, GRANULARITY - 1);
449 mono_mb_emit_byte (mb, MONO_CEE_ADD);
450 mono_mb_emit_icon (mb, shift_amount (GRANULARITY));
451 mono_mb_emit_byte (mb, MONO_CEE_SHR_UN);
452 mono_mb_emit_icon (mb, shift_amount (sizeof (gpointer)));
453 mono_mb_emit_byte (mb, MONO_CEE_SHL);
454 /* index var is already adjusted into bytes */
455 mono_mb_emit_stloc (mb, index_var);
457 my_fl_var = mono_mb_add_local (mb, &mono_defaults.int_class->byval_arg);
458 my_entry_var = mono_mb_add_local (mb, &mono_defaults.int_class->byval_arg);
459 /* my_fl = ((GC_thread)tsd) -> ptrfree_freelists + index; */
460 mono_mb_emit_byte (mb, MONO_CUSTOM_PREFIX);
461 mono_mb_emit_byte (mb, 0x0D); /* CEE_MONO_TLS */
462 mono_mb_emit_i4 (mb, offset);
463 if (atype == ATYPE_FREEPTR || atype == ATYPE_FREEPTR_FOR_BOX || atype == ATYPE_STRING)
464 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (struct GC_Thread_Rep, ptrfree_freelists));
465 else if (atype == ATYPE_NORMAL)
466 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (struct GC_Thread_Rep, normal_freelists));
467 else if (atype == ATYPE_GCJ)
468 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (struct GC_Thread_Rep, gcj_freelists));
470 g_assert_not_reached ();
471 mono_mb_emit_byte (mb, MONO_CEE_ADD);
472 mono_mb_emit_ldloc (mb, index_var);
473 mono_mb_emit_byte (mb, MONO_CEE_ADD);
474 mono_mb_emit_stloc (mb, my_fl_var);
476 /* my_entry = *my_fl; */
477 mono_mb_emit_ldloc (mb, my_fl_var);
478 mono_mb_emit_byte (mb, MONO_CEE_LDIND_I);
479 mono_mb_emit_stloc (mb, my_entry_var);
481 /* if (EXPECT((word)my_entry >= HBLKSIZE, 1)) { */
482 mono_mb_emit_ldloc (mb, my_entry_var);
483 mono_mb_emit_icon (mb, HBLKSIZE);
484 no_freelist_branch = mono_mb_emit_short_branch (mb, MONO_CEE_BLT_UN_S);
486 /* ptr_t next = obj_link(my_entry); *my_fl = next; */
487 mono_mb_emit_ldloc (mb, my_fl_var);
488 mono_mb_emit_ldloc (mb, my_entry_var);
489 mono_mb_emit_byte (mb, MONO_CEE_LDIND_I);
490 mono_mb_emit_byte (mb, MONO_CEE_STIND_I);
492 /* set the vtable and clear the words in the object */
493 mono_mb_emit_ldloc (mb, my_entry_var);
494 mono_mb_emit_ldarg (mb, 0);
495 mono_mb_emit_byte (mb, MONO_CEE_STIND_I);
497 if (atype == ATYPE_FREEPTR) {
498 int start_var, end_var, start_loop;
499 /* end = my_entry + bytes; start = my_entry + sizeof (gpointer);
501 start_var = mono_mb_add_local (mb, &mono_defaults.int_class->byval_arg);
502 end_var = mono_mb_add_local (mb, &mono_defaults.int_class->byval_arg);
503 mono_mb_emit_ldloc (mb, my_entry_var);
504 mono_mb_emit_ldloc (mb, bytes_var);
505 mono_mb_emit_byte (mb, MONO_CEE_ADD);
506 mono_mb_emit_stloc (mb, end_var);
507 mono_mb_emit_ldloc (mb, my_entry_var);
508 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoObject, synchronisation));
509 mono_mb_emit_byte (mb, MONO_CEE_ADD);
510 mono_mb_emit_stloc (mb, start_var);
514 * } while (start < end);
516 start_loop = mono_mb_get_label (mb);
517 mono_mb_emit_ldloc (mb, start_var);
518 mono_mb_emit_icon (mb, 0);
519 mono_mb_emit_byte (mb, MONO_CEE_STIND_I);
520 mono_mb_emit_ldloc (mb, start_var);
521 mono_mb_emit_icon (mb, sizeof (gpointer));
522 mono_mb_emit_byte (mb, MONO_CEE_ADD);
523 mono_mb_emit_stloc (mb, start_var);
525 mono_mb_emit_ldloc (mb, start_var);
526 mono_mb_emit_ldloc (mb, end_var);
527 mono_mb_emit_byte (mb, MONO_CEE_BLT_UN_S);
528 mono_mb_emit_byte (mb, start_loop - (mono_mb_get_label (mb) + 1));
529 } else if (atype == ATYPE_FREEPTR_FOR_BOX || atype == ATYPE_STRING) {
530 /* need to clear just the sync pointer */
531 mono_mb_emit_ldloc (mb, my_entry_var);
532 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoObject, synchronisation));
533 mono_mb_emit_byte (mb, MONO_CEE_ADD);
534 mono_mb_emit_icon (mb, 0);
535 mono_mb_emit_byte (mb, MONO_CEE_STIND_I);
538 if (atype == ATYPE_STRING) {
539 /* need to set length and clear the last char */
540 /* s->length = len; */
541 mono_mb_emit_ldloc (mb, my_entry_var);
542 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoString, length));
543 mono_mb_emit_byte (mb, MONO_CEE_ADD);
544 mono_mb_emit_ldarg (mb, 1);
545 mono_mb_emit_byte (mb, MONO_CEE_STIND_I4);
546 /* s->chars [len] = 0; */
547 mono_mb_emit_ldloc (mb, my_entry_var);
548 mono_mb_emit_ldloc (mb, bytes_var);
549 mono_mb_emit_icon (mb, 2);
550 mono_mb_emit_byte (mb, MONO_CEE_SUB);
551 mono_mb_emit_byte (mb, MONO_CEE_ADD);
552 mono_mb_emit_icon (mb, 0);
553 mono_mb_emit_byte (mb, MONO_CEE_STIND_I2);
556 /* return my_entry; */
557 mono_mb_emit_ldloc (mb, my_entry_var);
558 mono_mb_emit_byte (mb, MONO_CEE_RET);
560 mono_mb_patch_short_branch (mb, no_freelist_branch);
561 if (not_small_enough_branch > 0)
562 mono_mb_patch_short_branch (mb, not_small_enough_branch);
563 if (size_overflow_branch > 0)
564 mono_mb_patch_short_branch (mb, size_overflow_branch);
565 /* the slow path: we just call back into the runtime */
566 if (atype == ATYPE_STRING) {
567 mono_mb_emit_ldarg (mb, 1);
568 mono_mb_emit_icall (mb, mono_string_alloc);
570 mono_mb_emit_ldarg (mb, 0);
571 mono_mb_emit_icall (mb, mono_object_new_specific);
574 mono_mb_emit_byte (mb, MONO_CEE_RET);
576 res = mono_mb_create_method (mb, csig, 8);
578 mono_method_get_header (res)->init_locals = FALSE;
582 static MonoMethod* alloc_method_cache [ATYPE_NUM];
585 * If possible, generate a managed method that can quickly allocate objects in class
586 * @klass. The method will typically have an thread-local inline allocation sequence.
587 * The signature of the called method is:
588 * object allocate (MonoVTable *vtable)
589 * Some of the logic here is similar to mono_class_get_allocation_ftn () i object.c,
591 * The thread local alloc logic is taken from libgc/pthread_support.c.
595 mono_gc_get_managed_allocator (MonoVTable *vtable, gboolean for_box)
599 MonoClass *klass = vtable->klass;
600 MONO_THREAD_VAR_OFFSET (GC_thread_tls, offset);
602 /*g_print ("thread tls: %d\n", offset);*/
605 if (!SMALL_ENOUGH (klass->instance_size))
607 if (klass->has_finalize || klass->marshalbyref || (mono_profiler_get_events () & MONO_PROFILE_ALLOCATIONS))
611 if (klass->byval_arg.type == MONO_TYPE_STRING) {
612 atype = ATYPE_STRING;
613 } else if (!klass->has_references) {
615 atype = ATYPE_FREEPTR_FOR_BOX;
617 atype = ATYPE_FREEPTR;
621 * disabled because we currently do a runtime choice anyway, to
622 * deal with multiple appdomains.
623 if (vtable->gc_descr != GC_NO_DESCRIPTOR)
626 atype = ATYPE_NORMAL;
629 return mono_gc_get_managed_allocator_by_type (atype);
633 * mono_gc_get_managed_allocator_id:
635 * Return a type for the managed allocator method MANAGED_ALLOC which can later be passed
636 * to mono_gc_get_managed_allocator_by_type () to get back this allocator method. This can be
637 * used by the AOT code to encode references to managed allocator methods.
640 mono_gc_get_managed_allocator_type (MonoMethod *managed_alloc)
645 for (i = 0; i < ATYPE_NUM; ++i) {
646 if (alloc_method_cache [i] == managed_alloc) {
647 mono_loader_unlock ();
651 mono_loader_unlock ();
657 * mono_gc_get_managed_allocator_by_type:
659 * Return a managed allocator method corresponding to allocator type ATYPE.
662 mono_gc_get_managed_allocator_by_type (int atype)
666 MONO_THREAD_VAR_OFFSET (GC_thread_tls, offset);
669 res = alloc_method_cache [atype];
671 res = alloc_method_cache [atype] = create_allocator (atype, offset);
672 mono_loader_unlock ();
679 mono_gc_get_managed_allocator (MonoVTable *vtable, gboolean for_box)
685 mono_gc_get_managed_allocator_type (MonoMethod *managed_alloc)
691 mono_gc_get_managed_allocator_by_type (int atype)
698 #endif /* no Boehm GC */