2 * boehm-gc.c: GC implementation using either the installed or included Boehm GC.
7 #define GC_I_HIDE_POINTERS
8 #include <mono/metadata/gc-internal.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>
16 #include <mono/utils/dtrace.h>
20 #ifdef USE_INCLUDED_LIBGC
23 #define THREAD_LOCAL_ALLOC 1
24 #include "private/pthread_support.h"
27 #define GC_NO_DESCRIPTOR ((gpointer)(0 | GC_DS_LENGTH))
29 static gboolean gc_initialized = FALSE;
32 mono_gc_warning (char *msg, GC_word arg)
34 mono_trace (G_LOG_LEVEL_WARNING, MONO_TRACE_GC, msg, (unsigned long)arg);
38 mono_gc_base_init (void)
44 * Handle the case when we are called from a thread different from the main thread,
46 * FIXME: Move this to libgc where it belongs.
48 * we used to do this only when running on valgrind,
49 * but it happens also in other setups.
51 #if defined(HAVE_PTHREAD_GETATTR_NP) && defined(HAVE_PTHREAD_ATTR_GETSTACK)
56 pthread_getattr_np (pthread_self (), &attr);
57 pthread_attr_getstack (&attr, &sstart, &size);
58 pthread_attr_destroy (&attr);
59 /*g_print ("stackbottom pth is: %p\n", (char*)sstart + size);*/
62 * The calculation above doesn't seem to work on ia64, also we need to set
63 * GC_register_stackbottom as well, but don't know how.
66 /* apparently with some linuxthreads implementations sstart can be NULL,
67 * fallback to the more imprecise method (bug# 78096).
70 GC_stackbottom = (char*)sstart + size;
73 gsize stack_bottom = (gsize)&dummy;
75 stack_bottom &= ~4095;
76 GC_stackbottom = (char*)stack_bottom;
80 #elif defined(HAVE_PTHREAD_GET_STACKSIZE_NP) && defined(HAVE_PTHREAD_GET_STACKADDR_NP)
81 GC_stackbottom = (char*)pthread_get_stackaddr_np (pthread_self ());
85 gsize stack_bottom = (gsize)&dummy;
87 stack_bottom &= ~4095;
88 /*g_print ("stackbottom is: %p\n", (char*)stack_bottom);*/
89 GC_stackbottom = (char*)stack_bottom;
95 GC_oom_fn = mono_gc_out_of_memory;
96 GC_set_warn_proc (mono_gc_warning);
97 GC_finalize_on_demand = 1;
98 GC_finalizer_notifier = mono_gc_finalize_notify;
100 #ifdef HAVE_GC_GCJ_MALLOC
101 GC_init_gcj_malloc (5, NULL);
103 mono_gc_enable_events ();
104 gc_initialized = TRUE;
108 mono_gc_collect (int generation)
110 MONO_PROBE_GC_BEGIN (generation);
112 mono_perfcounters->gc_induced++;
115 MONO_PROBE_GC_END (generation);
116 #if defined(ENABLE_DTRACE) && defined(__sun__)
117 /* This works around a dtrace -G problem on Solaris.
118 Limit its actual use to when the probe is enabled. */
119 if (MONO_PROBE_GC_END_ENABLED ())
125 mono_gc_max_generation (void)
131 mono_gc_get_generation (MonoObject *object)
137 mono_gc_collection_count (int generation)
143 mono_gc_add_memory_pressure (gint64 value)
148 mono_gc_get_used_size (void)
150 return GC_get_heap_size () - GC_get_free_bytes ();
154 mono_gc_get_heap_size (void)
156 return GC_get_heap_size ();
160 mono_gc_disable (void)
162 #ifdef HAVE_GC_ENABLE
165 g_assert_not_reached ();
170 mono_gc_enable (void)
172 #ifdef HAVE_GC_ENABLE
175 g_assert_not_reached ();
180 mono_gc_is_gc_thread (void)
182 #if GC_VERSION_MAJOR >= 7
184 #elif defined(USE_INCLUDED_LIBGC)
185 return GC_thread_is_registered ();
191 extern int GC_thread_register_foreign (void *base_addr);
194 mono_gc_register_thread (void *baseptr)
196 #if GC_VERSION_MAJOR >= 7
197 struct GC_stack_base sb;
200 res = GC_get_stack_base (&sb);
201 if (res != GC_SUCCESS) {
202 sb.mem_base = baseptr;
204 /* Can't determine the register stack bounds */
205 g_error ("mono_gc_register_thread failed ().\n");
208 res = GC_register_my_thread (&sb);
209 if ((res != GC_SUCCESS) && (res != GC_DUPLICATE)) {
210 g_warning ("GC_register_my_thread () failed.\n");
215 if (mono_gc_is_gc_thread())
217 #if defined(USE_INCLUDED_LIBGC) && !defined(PLATFORM_WIN32)
218 return GC_thread_register_foreign (baseptr);
226 mono_object_is_alive (MonoObject* o)
228 #ifdef USE_INCLUDED_LIBGC
229 return GC_is_marked ((gpointer)o);
235 #ifdef USE_INCLUDED_LIBGC
238 on_gc_notification (GCEventType event)
240 if (event == MONO_GC_EVENT_START) {
241 mono_perfcounters->gc_collections0++;
242 } else if (event == MONO_GC_EVENT_END) {
243 guint64 heap_size = GC_get_heap_size ();
244 guint64 used_size = heap_size - GC_get_free_bytes ();
245 mono_perfcounters->gc_total_bytes = used_size;
246 mono_perfcounters->gc_committed_bytes = heap_size;
247 mono_perfcounters->gc_reserved_bytes = heap_size;
248 mono_perfcounters->gc_gen0size = heap_size;
250 mono_profiler_gc_event ((MonoGCEvent) event, 0);
254 on_gc_heap_resize (size_t new_size)
256 guint64 heap_size = GC_get_heap_size ();
257 mono_perfcounters->gc_committed_bytes = heap_size;
258 mono_perfcounters->gc_reserved_bytes = heap_size;
259 mono_perfcounters->gc_gen0size = heap_size;
260 mono_profiler_gc_heap_resize (new_size);
264 mono_gc_enable_events (void)
266 GC_notify_event = on_gc_notification;
267 GC_on_heap_resize = on_gc_heap_resize;
273 mono_gc_enable_events (void)
280 mono_gc_register_root (char *start, size_t size, void *descr)
282 /* for some strange reason, they want one extra byte on the end */
283 GC_add_roots (start, start + size + 1);
289 mono_gc_deregister_root (char* addr)
291 #ifndef PLATFORM_WIN32
292 /* FIXME: libgc doesn't define this work win32 for some reason */
293 /* FIXME: No size info */
294 GC_remove_roots (addr, addr + sizeof (gpointer) + 1);
299 mono_gc_weak_link_add (void **link_addr, MonoObject *obj)
301 /* libgc requires that we use HIDE_POINTER... */
302 *link_addr = (void*)HIDE_POINTER (obj);
303 GC_GENERAL_REGISTER_DISAPPEARING_LINK (link_addr, obj);
307 mono_gc_weak_link_remove (void **link_addr)
309 GC_unregister_disappearing_link (link_addr);
314 mono_gc_weak_link_get (void **link_addr)
316 MonoObject *obj = REVEAL_POINTER (*link_addr);
317 if (obj == (MonoObject *) -1)
323 mono_gc_make_descr_for_string (gsize *bitmap, int numbits)
325 return mono_gc_make_descr_from_bitmap (bitmap, numbits);
329 mono_gc_make_descr_for_object (gsize *bitmap, int numbits, size_t obj_size)
331 return mono_gc_make_descr_from_bitmap (bitmap, numbits);
335 mono_gc_make_descr_for_array (int vector, gsize *elem_bitmap, int numbits, size_t elem_size)
337 /* libgc has no usable support for arrays... */
338 return GC_NO_DESCRIPTOR;
342 mono_gc_make_descr_from_bitmap (gsize *bitmap, int numbits)
344 #ifdef HAVE_GC_GCJ_MALLOC
345 /* It seems there are issues when the bitmap doesn't fit: play it safe */
347 return GC_NO_DESCRIPTOR;
349 return (gpointer)GC_make_descriptor ((GC_bitmap)bitmap, numbits);
356 mono_gc_alloc_fixed (size_t size, void *descr)
358 return GC_MALLOC (size);
362 mono_gc_free_fixed (void* addr)
367 mono_gc_invoke_finalizers (void)
369 /* There is a bug in GC_invoke_finalizer () in versions <= 6.2alpha4:
370 * the 'mem_freed' variable is not initialized when there are no
371 * objects to finalize, which leads to strange behavior later on.
372 * The check is necessary to work around that bug.
374 if (GC_should_invoke_finalizers ())
375 return GC_invoke_finalizers ();
380 mono_gc_pending_finalizers (void)
382 return GC_should_invoke_finalizers ();
386 mono_gc_wbarrier_set_field (MonoObject *obj, gpointer field_ptr, MonoObject* value)
388 *(void**)field_ptr = value;
392 mono_gc_wbarrier_set_arrayref (MonoArray *arr, gpointer slot_ptr, MonoObject* value)
394 *(void**)slot_ptr = value;
398 mono_gc_wbarrier_arrayref_copy (MonoArray *arr, gpointer slot_ptr, int count)
400 /* no need to do anything */
404 mono_gc_wbarrier_generic_store (gpointer ptr, MonoObject* value)
406 *(void**)ptr = value;
410 mono_gc_wbarrier_value_copy (gpointer dest, gpointer src, int count, MonoClass *klass)
415 mono_gc_wbarrier_object (MonoObject *object)
419 #if defined(USE_INCLUDED_LIBGC) && defined(USE_COMPILER_TLS) && defined(__linux__) && (defined(__i386__) || defined(__x86_64__))
420 extern __thread MONO_TLS_FAST void* GC_thread_tls;
421 #include "metadata-internals.h"
427 while (!(v & (1 << i)))
434 ATYPE_FREEPTR_FOR_BOX,
442 create_allocator (int atype, int offset)
444 int index_var, bytes_var, my_fl_var, my_entry_var;
445 guint32 no_freelist_branch, not_small_enough_branch = 0;
446 guint32 size_overflow_branch = 0;
447 MonoMethodBuilder *mb;
449 MonoMethodSignature *csig;
451 if (atype == ATYPE_STRING) {
452 csig = mono_metadata_signature_alloc (mono_defaults.corlib, 2);
453 csig->ret = &mono_defaults.string_class->byval_arg;
454 csig->params [0] = &mono_defaults.int_class->byval_arg;
455 csig->params [1] = &mono_defaults.int32_class->byval_arg;
457 csig = mono_metadata_signature_alloc (mono_defaults.corlib, 1);
458 csig->ret = &mono_defaults.object_class->byval_arg;
459 csig->params [0] = &mono_defaults.int_class->byval_arg;
462 mb = mono_mb_new (mono_defaults.object_class, "Alloc", MONO_WRAPPER_ALLOC);
463 bytes_var = mono_mb_add_local (mb, &mono_defaults.int32_class->byval_arg);
464 if (atype == ATYPE_STRING) {
465 /* a string alloator method takes the args: (vtable, len) */
466 /* bytes = (sizeof (MonoString) + ((len + 1) * 2)); */
467 mono_mb_emit_ldarg (mb, 1);
468 mono_mb_emit_icon (mb, 1);
469 mono_mb_emit_byte (mb, MONO_CEE_ADD);
470 mono_mb_emit_icon (mb, 1);
471 mono_mb_emit_byte (mb, MONO_CEE_SHL);
472 // sizeof (MonoString) might include padding
473 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoString, chars));
474 mono_mb_emit_byte (mb, MONO_CEE_ADD);
475 mono_mb_emit_stloc (mb, bytes_var);
477 /* bytes = vtable->klass->instance_size */
478 mono_mb_emit_ldarg (mb, 0);
479 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoVTable, klass));
480 mono_mb_emit_byte (mb, MONO_CEE_ADD);
481 mono_mb_emit_byte (mb, MONO_CEE_LDIND_I);
482 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoClass, instance_size));
483 mono_mb_emit_byte (mb, MONO_CEE_ADD);
484 /* FIXME: assert instance_size stays a 4 byte integer */
485 mono_mb_emit_byte (mb, MONO_CEE_LDIND_U4);
486 mono_mb_emit_stloc (mb, bytes_var);
489 /* this is needed for strings/arrays only as the other big types are never allocated with this method */
490 if (atype == ATYPE_STRING) {
492 /* if (!SMALL_ENOUGH (bytes)) jump slow_path;*/
493 mono_mb_emit_ldloc (mb, bytes_var);
494 mono_mb_emit_icon (mb, (NFREELISTS-1) * GRANULARITY);
495 not_small_enough_branch = mono_mb_emit_short_branch (mb, MONO_CEE_BGT_UN_S);
496 /* check for overflow */
497 mono_mb_emit_ldloc (mb, bytes_var);
498 mono_mb_emit_icon (mb, sizeof (MonoString));
499 size_overflow_branch = mono_mb_emit_short_branch (mb, MONO_CEE_BLE_UN_S);
502 /* int index = INDEX_FROM_BYTES(bytes); */
503 index_var = mono_mb_add_local (mb, &mono_defaults.int32_class->byval_arg);
505 mono_mb_emit_ldloc (mb, bytes_var);
506 mono_mb_emit_icon (mb, GRANULARITY - 1);
507 mono_mb_emit_byte (mb, MONO_CEE_ADD);
508 mono_mb_emit_icon (mb, shift_amount (GRANULARITY));
509 mono_mb_emit_byte (mb, MONO_CEE_SHR_UN);
510 mono_mb_emit_icon (mb, shift_amount (sizeof (gpointer)));
511 mono_mb_emit_byte (mb, MONO_CEE_SHL);
512 /* index var is already adjusted into bytes */
513 mono_mb_emit_stloc (mb, index_var);
515 my_fl_var = mono_mb_add_local (mb, &mono_defaults.int_class->byval_arg);
516 my_entry_var = mono_mb_add_local (mb, &mono_defaults.int_class->byval_arg);
517 /* my_fl = ((GC_thread)tsd) -> ptrfree_freelists + index; */
518 mono_mb_emit_byte (mb, MONO_CUSTOM_PREFIX);
519 mono_mb_emit_byte (mb, 0x0D); /* CEE_MONO_TLS */
520 mono_mb_emit_i4 (mb, offset);
521 if (atype == ATYPE_FREEPTR || atype == ATYPE_FREEPTR_FOR_BOX || atype == ATYPE_STRING)
522 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (struct GC_Thread_Rep, ptrfree_freelists));
523 else if (atype == ATYPE_NORMAL)
524 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (struct GC_Thread_Rep, normal_freelists));
525 else if (atype == ATYPE_GCJ)
526 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (struct GC_Thread_Rep, gcj_freelists));
528 g_assert_not_reached ();
529 mono_mb_emit_byte (mb, MONO_CEE_ADD);
530 mono_mb_emit_ldloc (mb, index_var);
531 mono_mb_emit_byte (mb, MONO_CEE_ADD);
532 mono_mb_emit_stloc (mb, my_fl_var);
534 /* my_entry = *my_fl; */
535 mono_mb_emit_ldloc (mb, my_fl_var);
536 mono_mb_emit_byte (mb, MONO_CEE_LDIND_I);
537 mono_mb_emit_stloc (mb, my_entry_var);
539 /* if (EXPECT((word)my_entry >= HBLKSIZE, 1)) { */
540 mono_mb_emit_ldloc (mb, my_entry_var);
541 mono_mb_emit_icon (mb, HBLKSIZE);
542 no_freelist_branch = mono_mb_emit_short_branch (mb, MONO_CEE_BLT_UN_S);
544 /* ptr_t next = obj_link(my_entry); *my_fl = next; */
545 mono_mb_emit_ldloc (mb, my_fl_var);
546 mono_mb_emit_ldloc (mb, my_entry_var);
547 mono_mb_emit_byte (mb, MONO_CEE_LDIND_I);
548 mono_mb_emit_byte (mb, MONO_CEE_STIND_I);
550 /* set the vtable and clear the words in the object */
551 mono_mb_emit_ldloc (mb, my_entry_var);
552 mono_mb_emit_ldarg (mb, 0);
553 mono_mb_emit_byte (mb, MONO_CEE_STIND_I);
555 if (atype == ATYPE_FREEPTR) {
556 int start_var, end_var, start_loop;
557 /* end = my_entry + bytes; start = my_entry + sizeof (gpointer);
559 start_var = mono_mb_add_local (mb, &mono_defaults.int_class->byval_arg);
560 end_var = mono_mb_add_local (mb, &mono_defaults.int_class->byval_arg);
561 mono_mb_emit_ldloc (mb, my_entry_var);
562 mono_mb_emit_ldloc (mb, bytes_var);
563 mono_mb_emit_byte (mb, MONO_CEE_ADD);
564 mono_mb_emit_stloc (mb, end_var);
565 mono_mb_emit_ldloc (mb, my_entry_var);
566 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoObject, synchronisation));
567 mono_mb_emit_byte (mb, MONO_CEE_ADD);
568 mono_mb_emit_stloc (mb, start_var);
572 * } while (start < end);
574 start_loop = mono_mb_get_label (mb);
575 mono_mb_emit_ldloc (mb, start_var);
576 mono_mb_emit_icon (mb, 0);
577 mono_mb_emit_byte (mb, MONO_CEE_STIND_I);
578 mono_mb_emit_ldloc (mb, start_var);
579 mono_mb_emit_icon (mb, sizeof (gpointer));
580 mono_mb_emit_byte (mb, MONO_CEE_ADD);
581 mono_mb_emit_stloc (mb, start_var);
583 mono_mb_emit_ldloc (mb, start_var);
584 mono_mb_emit_ldloc (mb, end_var);
585 mono_mb_emit_byte (mb, MONO_CEE_BLT_UN_S);
586 mono_mb_emit_byte (mb, start_loop - (mono_mb_get_label (mb) + 1));
587 } else if (atype == ATYPE_FREEPTR_FOR_BOX || atype == ATYPE_STRING) {
588 /* need to clear just the sync pointer */
589 mono_mb_emit_ldloc (mb, my_entry_var);
590 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoObject, synchronisation));
591 mono_mb_emit_byte (mb, MONO_CEE_ADD);
592 mono_mb_emit_icon (mb, 0);
593 mono_mb_emit_byte (mb, MONO_CEE_STIND_I);
596 if (atype == ATYPE_STRING) {
597 /* need to set length and clear the last char */
598 /* s->length = len; */
599 mono_mb_emit_ldloc (mb, my_entry_var);
600 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoString, length));
601 mono_mb_emit_byte (mb, MONO_CEE_ADD);
602 mono_mb_emit_ldarg (mb, 1);
603 mono_mb_emit_byte (mb, MONO_CEE_STIND_I4);
604 /* s->chars [len] = 0; */
605 mono_mb_emit_ldloc (mb, my_entry_var);
606 mono_mb_emit_ldloc (mb, bytes_var);
607 mono_mb_emit_icon (mb, 2);
608 mono_mb_emit_byte (mb, MONO_CEE_SUB);
609 mono_mb_emit_byte (mb, MONO_CEE_ADD);
610 mono_mb_emit_icon (mb, 0);
611 mono_mb_emit_byte (mb, MONO_CEE_STIND_I2);
614 /* return my_entry; */
615 mono_mb_emit_ldloc (mb, my_entry_var);
616 mono_mb_emit_byte (mb, MONO_CEE_RET);
618 mono_mb_patch_short_branch (mb, no_freelist_branch);
619 if (not_small_enough_branch > 0)
620 mono_mb_patch_short_branch (mb, not_small_enough_branch);
621 if (size_overflow_branch > 0)
622 mono_mb_patch_short_branch (mb, size_overflow_branch);
623 /* the slow path: we just call back into the runtime */
624 if (atype == ATYPE_STRING) {
625 mono_mb_emit_ldarg (mb, 1);
626 mono_mb_emit_icall (mb, mono_string_alloc);
628 mono_mb_emit_ldarg (mb, 0);
629 mono_mb_emit_icall (mb, mono_object_new_specific);
632 mono_mb_emit_byte (mb, MONO_CEE_RET);
634 res = mono_mb_create_method (mb, csig, 8);
636 mono_method_get_header (res)->init_locals = FALSE;
640 static MonoMethod* alloc_method_cache [ATYPE_NUM];
643 * If possible, generate a managed method that can quickly allocate objects in class
644 * @klass. The method will typically have an thread-local inline allocation sequence.
645 * The signature of the called method is:
646 * object allocate (MonoVTable *vtable)
647 * Some of the logic here is similar to mono_class_get_allocation_ftn () i object.c,
649 * The thread local alloc logic is taken from libgc/pthread_support.c.
653 mono_gc_get_managed_allocator (MonoVTable *vtable, gboolean for_box)
657 MonoClass *klass = vtable->klass;
658 MONO_THREAD_VAR_OFFSET (GC_thread_tls, offset);
660 /*g_print ("thread tls: %d\n", offset);*/
663 if (!SMALL_ENOUGH (klass->instance_size))
665 if (klass->has_finalize || klass->marshalbyref || (mono_profiler_get_events () & MONO_PROFILE_ALLOCATIONS))
669 if (klass->byval_arg.type == MONO_TYPE_STRING) {
670 atype = ATYPE_STRING;
671 } else if (!klass->has_references) {
673 atype = ATYPE_FREEPTR_FOR_BOX;
675 atype = ATYPE_FREEPTR;
679 * disabled because we currently do a runtime choice anyway, to
680 * deal with multiple appdomains.
681 if (vtable->gc_descr != GC_NO_DESCRIPTOR)
684 atype = ATYPE_NORMAL;
687 return mono_gc_get_managed_allocator_by_type (atype);
691 * mono_gc_get_managed_allocator_id:
693 * Return a type for the managed allocator method MANAGED_ALLOC which can later be passed
694 * to mono_gc_get_managed_allocator_by_type () to get back this allocator method. This can be
695 * used by the AOT code to encode references to managed allocator methods.
698 mono_gc_get_managed_allocator_type (MonoMethod *managed_alloc)
703 for (i = 0; i < ATYPE_NUM; ++i) {
704 if (alloc_method_cache [i] == managed_alloc) {
705 mono_loader_unlock ();
709 mono_loader_unlock ();
715 * mono_gc_get_managed_allocator_by_type:
717 * Return a managed allocator method corresponding to allocator type ATYPE.
720 mono_gc_get_managed_allocator_by_type (int atype)
724 MONO_THREAD_VAR_OFFSET (GC_thread_tls, offset);
727 res = alloc_method_cache [atype];
729 res = alloc_method_cache [atype] = create_allocator (atype, offset);
730 mono_loader_unlock ();
735 mono_gc_get_managed_allocator_types (void)
743 mono_gc_get_managed_allocator (MonoVTable *vtable, gboolean for_box)
749 mono_gc_get_managed_allocator_type (MonoMethod *managed_alloc)
755 mono_gc_get_managed_allocator_by_type (int atype)
761 mono_gc_get_managed_allocator_types (void)
768 #endif /* no Boehm GC */