2010-07-13 Mark Probst <mark.probst@gmail.com>

	* sgen-gc.c: Versions of safe_object_get_size() and
	copy_object_no_checks() that work without the object's vtable
	intact, by passing the correct vtable as an argument.

svn path=/trunk/mono/; revision=160316

diff --git a/mono/metadata/ChangeLog b/mono/metadata/ChangeLog
index 941a632757cb12cfc1c39f92c749f6fd2ebd7ae5..26818312022f99df0b23f4bb14ef2b3cf26ac67c 100644 (file)
--- a/mono/metadata/ChangeLog
+++ b/mono/metadata/ChangeLog
@@ -1,3 +1,9 @@
+2010-07-13  Mark Probst  <mark.probst@gmail.com>
+
+       * sgen-gc.c: Versions of safe_object_get_size() and
+       copy_object_no_checks() that work without the object's vtable
+       intact, by passing the correct vtable as an argument.
+
 2010-07-13  Mark Probst  <mark.probst@gmail.com>
 
        * sgen-marksweep.c: Make allocation of major sections thread-safe.

diff --git a/mono/metadata/sgen-gc.c b/mono/metadata/sgen-gc.c
index 20db918c4d43cc29b5a2181aae0810a164aa77a7..5df9e1f1ebb0424c73399d2168c4611038368e22 100644 (file)
--- a/mono/metadata/sgen-gc.c
+++ b/mono/metadata/sgen-gc.c
@@ -610,10 +610,19 @@ safe_name (void* obj)
        return vt->klass->name;
 }
 
+/*
+ * This function can be called on an object whose first word, the
+ * vtable field, is not intact.  This is necessary for the parallel
+ * collector.
+ */
 static inline guint
-safe_object_get_size (MonoObject* o)
+par_object_get_size (MonoVTable *vtable, MonoObject* o)
 {
-       MonoClass *klass = ((MonoVTable*)LOAD_VTABLE (o))->klass;
+       MonoClass *klass = vtable->klass;
+       /*
+        * We depend on mono_string_length_fast and
+        * mono_array_length_fast not using the object's vtable.
+        */
        if (klass == mono_defaults.string_class) {
                return sizeof (MonoString) + 2 * mono_string_length_fast ((MonoString*) o) + 2;
        } else if (klass->rank) {
@@ -631,6 +640,8 @@ safe_object_get_size (MonoObject* o)
        }
 }
 
+#define safe_object_get_size(o)                par_object_get_size ((MonoVTable*)LOAD_VTABLE ((o)), (o))
+
 /*
  * ######################################################################
  * ########  Global data.
@@ -975,6 +986,7 @@ typedef void (*IterateObjectCallbackFunc) (char*, size_t, void*);
 static void scan_area_with_callback (char *start, char *end, IterateObjectCallbackFunc callback, void *data);
 static void scan_object (char *start, GrayQueue *queue);
 static void major_scan_object (char *start, GrayQueue *queue);
+static void par_copy_object_no_checks (char *destination, MonoVTable *vt, void *obj, mword objsize, GrayQueue *queue);
 static void* copy_object_no_checks (void *obj, GrayQueue *queue);
 static void copy_object (void **obj_slot, GrayQueue *queue);
 static void* get_chunk_freelist (PinnedChunk *chunk, int slot);
@@ -2024,29 +2036,19 @@ add_to_global_remset (gpointer ptr)
 }
 
 /*
- * FIXME: allocate before calling this function and pass the
- * destination address.
+ * This function can be used even if the vtable of obj is not valid
+ * anymore, which is the case in the parallel collector.
  */
-static void*
-copy_object_no_checks (void *obj, GrayQueue *queue)
+static void
+par_copy_object_no_checks (char *destination, MonoVTable *vt, void *obj, mword objsize, GrayQueue *queue)
 {
        static const void *copy_labels [] = { &&LAB_0, &&LAB_1, &&LAB_2, &&LAB_3, &&LAB_4, &&LAB_5, &&LAB_6, &&LAB_7, &&LAB_8 };
 
-       mword objsize;
-       char *destination;
-       MonoVTable *vt = ((MonoObject*)obj)->vtable;
-       gboolean has_references = vt->gc_descr != (void*)DESC_TYPE_RUN_LENGTH;
-
-       objsize = safe_object_get_size ((MonoObject*)obj);
-       objsize += ALLOC_ALIGN - 1;
-       objsize &= ~(ALLOC_ALIGN - 1);
-
        DEBUG (9, g_assert (vt->klass->inited));
-       MAJOR_GET_COPY_OBJECT_SPACE (destination, objsize, has_references);
-
        DEBUG (9, fprintf (gc_debug_file, " (to %p, %s size: %lu)\n", destination, ((MonoObject*)obj)->vtable->klass->name, (unsigned long)objsize));
-       binary_protocol_copy (obj, destination, ((MonoObject*)obj)->vtable, objsize);
+       binary_protocol_copy (obj, destination, vt, objsize);
 
+       *(MonoVTable**)destination = vt;
        if (objsize <= sizeof (gpointer) * 8) {
                mword *dest = (mword*)destination;
                goto *copy_labels [objsize / sizeof (gpointer)];
@@ -2065,25 +2067,11 @@ copy_object_no_checks (void *obj, GrayQueue *queue)
        LAB_2:
                (dest) [1] = ((mword*)obj) [1];
        LAB_1:
-               (dest) [0] = ((mword*)obj) [0];
+               ;
        LAB_0:
                ;
        } else {
-#if 0
-               {
-                       int ecx;
-                       char* esi = obj;
-                       char* edi = destination;
-                       __asm__ __volatile__(
-                               "rep; movsl"
-                               : "=&c" (ecx), "=&D" (edi), "=&S" (esi)
-                               : "0" (objsize/4), "1" (edi),"2" (esi)
-                               : "memory"
-                                            );
-               }
-#else
-               memcpy (destination, obj, objsize);
-#endif
+               memcpy (destination + sizeof (mword), (char*)obj + sizeof (mword), objsize - sizeof (mword));
        }
        /* adjust array->bounds */
        DEBUG (9, g_assert (vt->gc_descr));
@@ -2092,9 +2080,11 @@ copy_object_no_checks (void *obj, GrayQueue *queue)
                array->bounds = (MonoArrayBounds*)((char*)destination + ((char*)((MonoArray*)obj)->bounds - (char*)obj));
                DEBUG (9, fprintf (gc_debug_file, "Array instance %p: size: %lu, rank: %d, length: %lu\n", array, (unsigned long)objsize, vt->rank, (unsigned long)mono_array_length (array)));
        }
-       /* set the forwarding pointer */
-       forward_object (obj, destination);
        if (G_UNLIKELY (mono_profiler_events & MONO_PROFILE_GC_MOVES)) {
+               /* FIXME: handle this for parallel collector */
+#ifdef SGEN_PARALLEL_MARK
+               g_assert_not_reached ();
+#endif
                if (moved_objects_idx == MOVED_OBJECTS_NUM) {
                        mono_profiler_gc_moves (moved_objects, moved_objects_idx);
                        moved_objects_idx = 0;
@@ -2103,11 +2093,28 @@ copy_object_no_checks (void *obj, GrayQueue *queue)
                moved_objects [moved_objects_idx++] = destination;
        }
        obj = destination;
-       if (has_references) {
+       if (queue) {
                DEBUG (9, fprintf (gc_debug_file, "Enqueuing gray object %p (%s)\n", obj, safe_name (obj)));
                GRAY_OBJECT_ENQUEUE (queue, obj);
        }
-       return obj;
+}
+
+static void*
+copy_object_no_checks (void *obj, GrayQueue *queue)
+{
+       MonoVTable *vt = ((MonoObject*)obj)->vtable;
+       gboolean has_references = vt->gc_descr != (void*)DESC_TYPE_RUN_LENGTH;
+       mword objsize = ALIGN_UP (par_object_get_size (vt, (MonoObject*)obj));
+       char *destination;
+
+       MAJOR_GET_COPY_OBJECT_SPACE (destination, objsize, has_references);
+
+       par_copy_object_no_checks (destination, vt, obj, objsize, has_references ? queue : NULL);
+
+       /* set the forwarding pointer */
+       forward_object (obj, destination);
+
+       return destination;
 }
 
 /*