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);
104 gc_initialized = TRUE;
108 mono_gc_collect (int generation)
110 MONO_PROBE_GC_BEGIN (generation);
114 MONO_PROBE_GC_END (generation);
115 #if defined(ENABLE_DTRACE) && defined(__sun__)
116 /* This works around a dtrace -G problem on Solaris.
117 Limit its actual use to when the probe is enabled. */
118 if (MONO_PROBE_GC_END_ENABLED ())
124 mono_gc_max_generation (void)
130 mono_gc_get_generation (MonoObject *object)
136 mono_gc_collection_count (int generation)
142 mono_gc_add_memory_pressure (gint64 value)
147 mono_gc_get_used_size (void)
149 return GC_get_heap_size () - GC_get_free_bytes ();
153 mono_gc_get_heap_size (void)
155 return GC_get_heap_size ();
159 mono_gc_disable (void)
161 #ifdef HAVE_GC_ENABLE
164 g_assert_not_reached ();
169 mono_gc_enable (void)
171 #ifdef HAVE_GC_ENABLE
174 g_assert_not_reached ();
179 mono_gc_is_gc_thread (void)
181 #if GC_VERSION_MAJOR >= 7
183 #elif defined(USE_INCLUDED_LIBGC)
184 return GC_thread_is_registered ();
190 extern int GC_thread_register_foreign (void *base_addr);
193 mono_gc_register_thread (void *baseptr)
195 #if GC_VERSION_MAJOR >= 7
196 struct GC_stack_base sb;
199 res = GC_get_stack_base (&sb);
200 if (res != GC_SUCCESS) {
201 sb.mem_base = baseptr;
203 /* Can't determine the register stack bounds */
204 g_error ("mono_gc_register_thread failed ().\n");
207 res = GC_register_my_thread (&sb);
208 if ((res != GC_SUCCESS) && (res != GC_DUPLICATE)) {
209 g_warning ("GC_register_my_thread () failed.\n");
214 if (mono_gc_is_gc_thread())
216 #if defined(USE_INCLUDED_LIBGC) && !defined(PLATFORM_WIN32)
217 return GC_thread_register_foreign (baseptr);
225 mono_object_is_alive (MonoObject* o)
227 #ifdef USE_INCLUDED_LIBGC
228 return GC_is_marked ((gpointer)o);
234 #ifdef USE_INCLUDED_LIBGC
237 on_gc_notification (GCEventType event)
239 mono_profiler_gc_event ((MonoGCEvent) event, 0);
243 on_gc_heap_resize (size_t new_size)
245 mono_profiler_gc_heap_resize (new_size);
249 mono_gc_enable_events (void)
251 GC_notify_event = on_gc_notification;
252 GC_on_heap_resize = on_gc_heap_resize;
258 mono_gc_enable_events (void)
265 mono_gc_register_root (char *start, size_t size, void *descr)
267 /* for some strange reason, they want one extra byte on the end */
268 GC_add_roots (start, start + size + 1);
274 mono_gc_deregister_root (char* addr)
276 #ifndef PLATFORM_WIN32
277 /* FIXME: libgc doesn't define this work win32 for some reason */
278 /* FIXME: No size info */
279 GC_remove_roots (addr, addr + sizeof (gpointer) + 1);
284 mono_gc_weak_link_add (void **link_addr, MonoObject *obj)
286 /* libgc requires that we use HIDE_POINTER... */
287 *link_addr = (void*)HIDE_POINTER (obj);
288 GC_GENERAL_REGISTER_DISAPPEARING_LINK (link_addr, obj);
292 mono_gc_weak_link_remove (void **link_addr)
294 GC_unregister_disappearing_link (link_addr);
299 mono_gc_weak_link_get (void **link_addr)
301 MonoObject *obj = REVEAL_POINTER (*link_addr);
302 if (obj == (MonoObject *) -1)
308 mono_gc_make_descr_for_string (gsize *bitmap, int numbits)
310 return mono_gc_make_descr_from_bitmap (bitmap, numbits);
314 mono_gc_make_descr_for_object (gsize *bitmap, int numbits, size_t obj_size)
316 return mono_gc_make_descr_from_bitmap (bitmap, numbits);
320 mono_gc_make_descr_for_array (int vector, gsize *elem_bitmap, int numbits, size_t elem_size)
322 /* libgc has no usable support for arrays... */
323 return GC_NO_DESCRIPTOR;
327 mono_gc_make_descr_from_bitmap (gsize *bitmap, int numbits)
329 #ifdef HAVE_GC_GCJ_MALLOC
330 /* It seems there are issues when the bitmap doesn't fit: play it safe */
332 return GC_NO_DESCRIPTOR;
334 return (gpointer)GC_make_descriptor ((GC_bitmap)bitmap, numbits);
341 mono_gc_alloc_fixed (size_t size, void *descr)
343 return GC_MALLOC (size);
347 mono_gc_free_fixed (void* addr)
352 mono_gc_invoke_finalizers (void)
354 /* There is a bug in GC_invoke_finalizer () in versions <= 6.2alpha4:
355 * the 'mem_freed' variable is not initialized when there are no
356 * objects to finalize, which leads to strange behavior later on.
357 * The check is necessary to work around that bug.
359 if (GC_should_invoke_finalizers ())
360 return GC_invoke_finalizers ();
365 mono_gc_pending_finalizers (void)
367 return GC_should_invoke_finalizers ();
371 mono_gc_wbarrier_set_field (MonoObject *obj, gpointer field_ptr, MonoObject* value)
373 *(void**)field_ptr = value;
377 mono_gc_wbarrier_set_arrayref (MonoArray *arr, gpointer slot_ptr, MonoObject* value)
379 *(void**)slot_ptr = value;
383 mono_gc_wbarrier_arrayref_copy (MonoArray *arr, gpointer slot_ptr, int count)
385 /* no need to do anything */
389 mono_gc_wbarrier_generic_store (gpointer ptr, MonoObject* value)
391 *(void**)ptr = value;
395 mono_gc_wbarrier_value_copy (gpointer dest, gpointer src, int count, MonoClass *klass)
400 mono_gc_wbarrier_object (MonoObject *object)
404 #if defined(USE_INCLUDED_LIBGC) && defined(USE_COMPILER_TLS) && defined(__linux__) && (defined(__i386__) || defined(__x86_64__))
405 extern __thread MONO_TLS_FAST void* GC_thread_tls;
406 #include "metadata-internals.h"
412 while (!(v & (1 << i)))
419 ATYPE_FREEPTR_FOR_BOX,
427 create_allocator (int atype, int offset)
429 int index_var, bytes_var, my_fl_var, my_entry_var;
430 guint32 no_freelist_branch, not_small_enough_branch = 0;
431 guint32 size_overflow_branch = 0;
432 MonoMethodBuilder *mb;
434 MonoMethodSignature *csig;
436 if (atype == ATYPE_STRING) {
437 csig = mono_metadata_signature_alloc (mono_defaults.corlib, 2);
438 csig->ret = &mono_defaults.string_class->byval_arg;
439 csig->params [0] = &mono_defaults.int_class->byval_arg;
440 csig->params [1] = &mono_defaults.int32_class->byval_arg;
442 csig = mono_metadata_signature_alloc (mono_defaults.corlib, 1);
443 csig->ret = &mono_defaults.object_class->byval_arg;
444 csig->params [0] = &mono_defaults.int_class->byval_arg;
447 mb = mono_mb_new (mono_defaults.object_class, "Alloc", MONO_WRAPPER_ALLOC);
448 bytes_var = mono_mb_add_local (mb, &mono_defaults.int32_class->byval_arg);
449 if (atype == ATYPE_STRING) {
450 /* a string alloator method takes the args: (vtable, len) */
451 /* bytes = (sizeof (MonoString) + ((len + 1) * 2)); */
452 mono_mb_emit_ldarg (mb, 1);
453 mono_mb_emit_icon (mb, 1);
454 mono_mb_emit_byte (mb, MONO_CEE_ADD);
455 mono_mb_emit_icon (mb, 1);
456 mono_mb_emit_byte (mb, MONO_CEE_SHL);
457 // sizeof (MonoString) might include padding
458 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoString, chars));
459 mono_mb_emit_byte (mb, MONO_CEE_ADD);
460 mono_mb_emit_stloc (mb, bytes_var);
462 /* bytes = vtable->klass->instance_size */
463 mono_mb_emit_ldarg (mb, 0);
464 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoVTable, klass));
465 mono_mb_emit_byte (mb, MONO_CEE_ADD);
466 mono_mb_emit_byte (mb, MONO_CEE_LDIND_I);
467 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoClass, instance_size));
468 mono_mb_emit_byte (mb, MONO_CEE_ADD);
469 /* FIXME: assert instance_size stays a 4 byte integer */
470 mono_mb_emit_byte (mb, MONO_CEE_LDIND_U4);
471 mono_mb_emit_stloc (mb, bytes_var);
474 /* this is needed for strings/arrays only as the other big types are never allocated with this method */
475 if (atype == ATYPE_STRING) {
477 /* if (!SMALL_ENOUGH (bytes)) jump slow_path;*/
478 mono_mb_emit_ldloc (mb, bytes_var);
479 mono_mb_emit_icon (mb, (NFREELISTS-1) * GRANULARITY);
480 not_small_enough_branch = mono_mb_emit_short_branch (mb, MONO_CEE_BGT_UN_S);
481 /* check for overflow */
482 mono_mb_emit_ldloc (mb, bytes_var);
483 mono_mb_emit_icon (mb, sizeof (MonoString));
484 size_overflow_branch = mono_mb_emit_short_branch (mb, MONO_CEE_BLE_UN_S);
487 /* int index = INDEX_FROM_BYTES(bytes); */
488 index_var = mono_mb_add_local (mb, &mono_defaults.int32_class->byval_arg);
490 mono_mb_emit_ldloc (mb, bytes_var);
491 mono_mb_emit_icon (mb, GRANULARITY - 1);
492 mono_mb_emit_byte (mb, MONO_CEE_ADD);
493 mono_mb_emit_icon (mb, shift_amount (GRANULARITY));
494 mono_mb_emit_byte (mb, MONO_CEE_SHR_UN);
495 mono_mb_emit_icon (mb, shift_amount (sizeof (gpointer)));
496 mono_mb_emit_byte (mb, MONO_CEE_SHL);
497 /* index var is already adjusted into bytes */
498 mono_mb_emit_stloc (mb, index_var);
500 my_fl_var = mono_mb_add_local (mb, &mono_defaults.int_class->byval_arg);
501 my_entry_var = mono_mb_add_local (mb, &mono_defaults.int_class->byval_arg);
502 /* my_fl = ((GC_thread)tsd) -> ptrfree_freelists + index; */
503 mono_mb_emit_byte (mb, MONO_CUSTOM_PREFIX);
504 mono_mb_emit_byte (mb, 0x0D); /* CEE_MONO_TLS */
505 mono_mb_emit_i4 (mb, offset);
506 if (atype == ATYPE_FREEPTR || atype == ATYPE_FREEPTR_FOR_BOX || atype == ATYPE_STRING)
507 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (struct GC_Thread_Rep, ptrfree_freelists));
508 else if (atype == ATYPE_NORMAL)
509 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (struct GC_Thread_Rep, normal_freelists));
510 else if (atype == ATYPE_GCJ)
511 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (struct GC_Thread_Rep, gcj_freelists));
513 g_assert_not_reached ();
514 mono_mb_emit_byte (mb, MONO_CEE_ADD);
515 mono_mb_emit_ldloc (mb, index_var);
516 mono_mb_emit_byte (mb, MONO_CEE_ADD);
517 mono_mb_emit_stloc (mb, my_fl_var);
519 /* my_entry = *my_fl; */
520 mono_mb_emit_ldloc (mb, my_fl_var);
521 mono_mb_emit_byte (mb, MONO_CEE_LDIND_I);
522 mono_mb_emit_stloc (mb, my_entry_var);
524 /* if (EXPECT((word)my_entry >= HBLKSIZE, 1)) { */
525 mono_mb_emit_ldloc (mb, my_entry_var);
526 mono_mb_emit_icon (mb, HBLKSIZE);
527 no_freelist_branch = mono_mb_emit_short_branch (mb, MONO_CEE_BLT_UN_S);
529 /* ptr_t next = obj_link(my_entry); *my_fl = next; */
530 mono_mb_emit_ldloc (mb, my_fl_var);
531 mono_mb_emit_ldloc (mb, my_entry_var);
532 mono_mb_emit_byte (mb, MONO_CEE_LDIND_I);
533 mono_mb_emit_byte (mb, MONO_CEE_STIND_I);
535 /* set the vtable and clear the words in the object */
536 mono_mb_emit_ldloc (mb, my_entry_var);
537 mono_mb_emit_ldarg (mb, 0);
538 mono_mb_emit_byte (mb, MONO_CEE_STIND_I);
540 if (atype == ATYPE_FREEPTR) {
541 int start_var, end_var, start_loop;
542 /* end = my_entry + bytes; start = my_entry + sizeof (gpointer);
544 start_var = mono_mb_add_local (mb, &mono_defaults.int_class->byval_arg);
545 end_var = mono_mb_add_local (mb, &mono_defaults.int_class->byval_arg);
546 mono_mb_emit_ldloc (mb, my_entry_var);
547 mono_mb_emit_ldloc (mb, bytes_var);
548 mono_mb_emit_byte (mb, MONO_CEE_ADD);
549 mono_mb_emit_stloc (mb, end_var);
550 mono_mb_emit_ldloc (mb, my_entry_var);
551 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoObject, synchronisation));
552 mono_mb_emit_byte (mb, MONO_CEE_ADD);
553 mono_mb_emit_stloc (mb, start_var);
557 * } while (start < end);
559 start_loop = mono_mb_get_label (mb);
560 mono_mb_emit_ldloc (mb, start_var);
561 mono_mb_emit_icon (mb, 0);
562 mono_mb_emit_byte (mb, MONO_CEE_STIND_I);
563 mono_mb_emit_ldloc (mb, start_var);
564 mono_mb_emit_icon (mb, sizeof (gpointer));
565 mono_mb_emit_byte (mb, MONO_CEE_ADD);
566 mono_mb_emit_stloc (mb, start_var);
568 mono_mb_emit_ldloc (mb, start_var);
569 mono_mb_emit_ldloc (mb, end_var);
570 mono_mb_emit_byte (mb, MONO_CEE_BLT_UN_S);
571 mono_mb_emit_byte (mb, start_loop - (mono_mb_get_label (mb) + 1));
572 } else if (atype == ATYPE_FREEPTR_FOR_BOX || atype == ATYPE_STRING) {
573 /* need to clear just the sync pointer */
574 mono_mb_emit_ldloc (mb, my_entry_var);
575 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoObject, synchronisation));
576 mono_mb_emit_byte (mb, MONO_CEE_ADD);
577 mono_mb_emit_icon (mb, 0);
578 mono_mb_emit_byte (mb, MONO_CEE_STIND_I);
581 if (atype == ATYPE_STRING) {
582 /* need to set length and clear the last char */
583 /* s->length = len; */
584 mono_mb_emit_ldloc (mb, my_entry_var);
585 mono_mb_emit_icon (mb, G_STRUCT_OFFSET (MonoString, length));
586 mono_mb_emit_byte (mb, MONO_CEE_ADD);
587 mono_mb_emit_ldarg (mb, 1);
588 mono_mb_emit_byte (mb, MONO_CEE_STIND_I4);
589 /* s->chars [len] = 0; */
590 mono_mb_emit_ldloc (mb, my_entry_var);
591 mono_mb_emit_ldloc (mb, bytes_var);
592 mono_mb_emit_icon (mb, 2);
593 mono_mb_emit_byte (mb, MONO_CEE_SUB);
594 mono_mb_emit_byte (mb, MONO_CEE_ADD);
595 mono_mb_emit_icon (mb, 0);
596 mono_mb_emit_byte (mb, MONO_CEE_STIND_I2);
599 /* return my_entry; */
600 mono_mb_emit_ldloc (mb, my_entry_var);
601 mono_mb_emit_byte (mb, MONO_CEE_RET);
603 mono_mb_patch_short_branch (mb, no_freelist_branch);
604 if (not_small_enough_branch > 0)
605 mono_mb_patch_short_branch (mb, not_small_enough_branch);
606 if (size_overflow_branch > 0)
607 mono_mb_patch_short_branch (mb, size_overflow_branch);
608 /* the slow path: we just call back into the runtime */
609 if (atype == ATYPE_STRING) {
610 mono_mb_emit_ldarg (mb, 1);
611 mono_mb_emit_icall (mb, mono_string_alloc);
613 mono_mb_emit_ldarg (mb, 0);
614 mono_mb_emit_icall (mb, mono_object_new_specific);
617 mono_mb_emit_byte (mb, MONO_CEE_RET);
619 res = mono_mb_create_method (mb, csig, 8);
621 mono_method_get_header (res)->init_locals = FALSE;
625 static MonoMethod* alloc_method_cache [ATYPE_NUM];
628 * If possible, generate a managed method that can quickly allocate objects in class
629 * @klass. The method will typically have an thread-local inline allocation sequence.
630 * The signature of the called method is:
631 * object allocate (MonoVTable *vtable)
632 * Some of the logic here is similar to mono_class_get_allocation_ftn () i object.c,
634 * The thread local alloc logic is taken from libgc/pthread_support.c.
638 mono_gc_get_managed_allocator (MonoVTable *vtable, gboolean for_box)
642 MonoClass *klass = vtable->klass;
643 MONO_THREAD_VAR_OFFSET (GC_thread_tls, offset);
645 /*g_print ("thread tls: %d\n", offset);*/
648 if (!SMALL_ENOUGH (klass->instance_size))
650 if (klass->has_finalize || klass->marshalbyref || (mono_profiler_get_events () & MONO_PROFILE_ALLOCATIONS))
654 if (klass->byval_arg.type == MONO_TYPE_STRING) {
655 atype = ATYPE_STRING;
656 } else if (!klass->has_references) {
658 atype = ATYPE_FREEPTR_FOR_BOX;
660 atype = ATYPE_FREEPTR;
664 * disabled because we currently do a runtime choice anyway, to
665 * deal with multiple appdomains.
666 if (vtable->gc_descr != GC_NO_DESCRIPTOR)
669 atype = ATYPE_NORMAL;
672 return mono_gc_get_managed_allocator_by_type (atype);
676 * mono_gc_get_managed_allocator_id:
678 * Return a type for the managed allocator method MANAGED_ALLOC which can later be passed
679 * to mono_gc_get_managed_allocator_by_type () to get back this allocator method. This can be
680 * used by the AOT code to encode references to managed allocator methods.
683 mono_gc_get_managed_allocator_type (MonoMethod *managed_alloc)
688 for (i = 0; i < ATYPE_NUM; ++i) {
689 if (alloc_method_cache [i] == managed_alloc) {
690 mono_loader_unlock ();
694 mono_loader_unlock ();
700 * mono_gc_get_managed_allocator_by_type:
702 * Return a managed allocator method corresponding to allocator type ATYPE.
705 mono_gc_get_managed_allocator_by_type (int atype)
709 MONO_THREAD_VAR_OFFSET (GC_thread_tls, offset);
712 res = alloc_method_cache [atype];
714 res = alloc_method_cache [atype] = create_allocator (atype, offset);
715 mono_loader_unlock ();
720 mono_gc_get_managed_allocator_types (void)
728 mono_gc_get_managed_allocator (MonoVTable *vtable, gboolean for_box)
734 mono_gc_get_managed_allocator_type (MonoMethod *managed_alloc)
740 mono_gc_get_managed_allocator_by_type (int atype)
746 mono_gc_get_managed_allocator_types (void)
753 #endif /* no Boehm GC */