mono/sgen/sgen-marksweep-drain-gray-stack.h

   1 /**
   2  * \file
   3  * The copy/mark and gray stack draining functions of the M&S major collector.
   4  *
   5  * Copyright (C) 2014 Xamarin Inc
   6  *
   7  * Licensed under the MIT license. See LICENSE file in the project root for full license information.
   8  */
   9
  10 /*
  11  * COPY_OR_MARK_FUNCTION_NAME must be defined to be the function name of the copy/mark
  12  * function.
  13  *
  14  * SCAN_OBJECT_FUNCTION_NAME must be defined to be the function name of the object scanning
  15  * function.
  16  *
  17  * DRAIN_GRAY_STACK_FUNCTION_NAME must be defined to be the function name of the gray stack
  18  * draining function.
  19  *
  20  * Define COPY_OR_MARK_WITH_EVACUATION to support evacuation.
  21  */
  22
  23 /* Returns whether the object is still in the nursery. */
  24 static inline MONO_ALWAYS_INLINE gboolean
  25 COPY_OR_MARK_FUNCTION_NAME (GCObject **ptr, GCObject *obj, SgenGrayQueue *queue)
  26 {
  27         MSBlockInfo *block;
  28
  29 #ifdef HEAVY_STATISTICS
  30         ++stat_optimized_copy;
  31         {
  32                 GCObject *forwarded;
  33                 SgenDescriptor desc;
  34                 if ((forwarded = SGEN_OBJECT_IS_FORWARDED (obj)))
  35                         desc = sgen_obj_get_descriptor_safe (forwarded);
  36                 else
  37                         desc = sgen_obj_get_descriptor_safe (obj);
  38
  39                 sgen_descriptor_count_copied_object (desc);
  40         }
  41 #endif
  42
  43         SGEN_ASSERT (9, obj, "null object from pointer %p", ptr);
  44 #if !defined(COPY_OR_MARK_CONCURRENT) && !defined(COPY_OR_MARK_CONCURRENT_WITH_EVACUATION)
  45         SGEN_ASSERT (9, current_collection_generation == GENERATION_OLD, "old gen parallel allocator called from a %d collection", current_collection_generation);
  46 #endif
  47
  48         if (sgen_ptr_in_nursery (obj)) {
  49 #if !defined(COPY_OR_MARK_CONCURRENT) && !defined(COPY_OR_MARK_CONCURRENT_WITH_EVACUATION)
  50                 int word, bit;
  51                 gboolean first = TRUE;
  52                 GCObject *forwarded, *old_obj;
  53                 mword vtable_word = *(mword*)obj;
  54
  55                 HEAVY_STAT (++stat_optimized_copy_nursery);
  56
  57 #if SGEN_MAX_DEBUG_LEVEL >= 9
  58                 if (sgen_nursery_is_to_space (obj))
  59                         SGEN_ASSERT (9, !SGEN_VTABLE_IS_PINNED (vtable_word) && !SGEN_VTABLE_IS_FORWARDED (vtable_word), "To-space object can't be pinned or forwarded.");
  60 #endif
  61
  62                 if (SGEN_VTABLE_IS_PINNED (vtable_word)) {
  63                         SGEN_ASSERT (9, !SGEN_VTABLE_IS_FORWARDED (vtable_word), "Cannot be both pinned and forwarded.");
  64                         HEAVY_STAT (++stat_optimized_copy_nursery_pinned);
  65                         return TRUE;
  66                 }
  67                 if ((forwarded = (GCObject *)SGEN_VTABLE_IS_FORWARDED (vtable_word))) {
  68                         HEAVY_STAT (++stat_optimized_copy_nursery_forwarded);
  69                         SGEN_UPDATE_REFERENCE (ptr, forwarded);
  70                         return sgen_ptr_in_nursery (forwarded);
  71                 }
  72
  73                 /* An object in the nursery To Space has already been copied and grayed. Nothing to do. */
  74                 if (sgen_nursery_is_to_space (obj))
  75                         return TRUE;
  76
  77 #ifdef COPY_OR_MARK_WITH_EVACUATION
  78         do_copy_object:
  79 #endif
  80                 old_obj = obj;
  81 #ifdef COPY_OR_MARK_PARALLEL
  82                 obj = copy_object_no_checks_par (obj, queue);
  83 #else
  84                 obj = copy_object_no_checks (obj, queue);
  85 #endif
  86                 if (G_UNLIKELY (old_obj == obj)) {
  87                         /*
  88                          * If we fail to evacuate an object we just stop doing it for a
  89                          * given block size as all other will surely fail too.
  90                          */
  91                         /* FIXME: test this case somehow. */
  92                         if (!sgen_ptr_in_nursery (obj)) {
  93                                 int size_index;
  94                                 block = MS_BLOCK_FOR_OBJ (obj);
  95                                 size_index = block->obj_size_index;
  96                                 evacuate_block_obj_sizes [size_index] = FALSE;
  97                                 MS_MARK_OBJECT_AND_ENQUEUE (obj, sgen_obj_get_descriptor (obj), block, queue);
  98                                 return FALSE;
  99                         }
 100                         return TRUE;
 101                 }
 102                 HEAVY_STAT (++stat_objects_copied_major);
 103                 SGEN_UPDATE_REFERENCE (ptr, obj);
 104
 105                 if (sgen_ptr_in_nursery (obj))
 106                         return TRUE;
 107
 108                 /*
 109                  * FIXME: See comment for copy_object_no_checks().  If
 110                  * we have that, we can let the allocation function
 111                  * give us the block info, too, and we won't have to
 112                  * re-fetch it.
 113                  *
 114                  * FIXME (2): We should rework this to avoid all those nursery checks.
 115                  */
 116                 /*
 117                  * For the split nursery allocator the object might
 118                  * still be in the nursery despite having being
 119                  * promoted, in which case we can't mark it.
 120                  */
 121                 block = MS_BLOCK_FOR_OBJ (obj);
 122                 MS_CALC_MARK_BIT (word, bit, obj);
 123                 SGEN_ASSERT (9, !MS_MARK_BIT (block, word, bit), "object %p already marked", obj);
 124 #ifdef COPY_OR_MARK_PARALLEL
 125                 MS_SET_MARK_BIT_PAR (block, word, bit, first);
 126 #else
 127                 MS_SET_MARK_BIT (block, word, bit);
 128 #endif
 129                 if (first)
 130                         binary_protocol_mark (obj, (gpointer)SGEN_LOAD_VTABLE (obj), sgen_safe_object_get_size (obj));
 131
 132                 return FALSE;
 133 #endif
 134         } else {
 135                 mword vtable_word = *(mword*)obj;
 136                 SgenDescriptor desc;
 137                 int type;
 138
 139                 HEAVY_STAT (++stat_optimized_copy_major);
 140
 141 #ifdef COPY_OR_MARK_WITH_EVACUATION
 142                 {
 143                         GCObject *forwarded;
 144                         if ((forwarded = (GCObject *)SGEN_VTABLE_IS_FORWARDED (vtable_word))) {
 145                                 HEAVY_STAT (++stat_optimized_copy_major_forwarded);
 146                                 SGEN_UPDATE_REFERENCE (ptr, forwarded);
 147                                 SGEN_ASSERT (9, !sgen_ptr_in_nursery (forwarded), "Cannot be forwarded to nursery.");
 148                                 return FALSE;
 149                         }
 150                 }
 151 #endif
 152
 153                 SGEN_ASSERT (9, !SGEN_VTABLE_IS_PINNED (vtable_word), "Pinned object in non-pinned block?");
 154
 155                 /* We untag the vtable for concurrent M&S, in case bridge is running and it tagged it */
 156                 desc = sgen_vtable_get_descriptor ((GCVTable)SGEN_POINTER_UNTAG_VTABLE (vtable_word));
 157                 type = desc & DESC_TYPE_MASK;
 158
 159                 if (sgen_safe_object_is_small (obj, type)) {
 160 #ifdef HEAVY_STATISTICS
 161                         if (type <= DESC_TYPE_MAX_SMALL_OBJ)
 162                                 ++stat_optimized_copy_major_small_fast;
 163                         else
 164                                 ++stat_optimized_copy_major_small_slow;
 165 #endif
 166
 167                         block = MS_BLOCK_FOR_OBJ (obj);
 168
 169 #ifdef COPY_OR_MARK_CONCURRENT_WITH_EVACUATION
 170                         if (G_UNLIKELY (major_block_is_evacuating (block))) {
 171                                 /*
 172                                  * We don't copy within the concurrent phase. These objects will
 173                                  * be handled below in the finishing pause, by scanning the mod-union
 174                                  * card table.
 175                                  */
 176                                 return FALSE;
 177                         }
 178 #endif
 179
 180 #ifdef COPY_OR_MARK_WITH_EVACUATION
 181                         if (major_block_is_evacuating (block)) {
 182                                 HEAVY_STAT (++stat_optimized_copy_major_small_evacuate);
 183                                 goto do_copy_object;
 184                         }
 185 #endif
 186
 187 #ifdef COPY_OR_MARK_PARALLEL
 188                         MS_MARK_OBJECT_AND_ENQUEUE_PAR (obj, desc, block, queue);
 189 #else
 190                         MS_MARK_OBJECT_AND_ENQUEUE (obj, desc, block, queue);
 191 #endif
 192                 } else {
 193                         gboolean first = TRUE;
 194                         HEAVY_STAT (++stat_optimized_copy_major_large);
 195 #ifdef COPY_OR_MARK_PARALLEL
 196                         first = sgen_los_pin_object_par (obj);
 197 #else
 198                         if (sgen_los_object_is_pinned (obj))
 199                                 first = FALSE;
 200                         else
 201                                 sgen_los_pin_object (obj);
 202 #endif
 203
 204                         if (first) {
 205                                 binary_protocol_pin (obj, (gpointer)SGEN_LOAD_VTABLE (obj), sgen_safe_object_get_size (obj));
 206                                 if (SGEN_OBJECT_HAS_REFERENCES (obj))
 207 #ifdef COPY_OR_MARK_PARALLEL
 208                                         GRAY_OBJECT_ENQUEUE_PARALLEL (queue, obj, desc);
 209 #else
 210                                         GRAY_OBJECT_ENQUEUE_SERIAL (queue, obj, desc);
 211 #endif
 212                         }
 213                 }
 214                 return FALSE;
 215         }
 216
 217         return TRUE;
 218 }
 219
 220 static void
 221 SCAN_OBJECT_FUNCTION_NAME (GCObject *full_object, SgenDescriptor desc, SgenGrayQueue *queue)
 222 {
 223         char *start = (char*)full_object;
 224
 225 #ifdef HEAVY_STATISTICS
 226         ++stat_optimized_major_scan;
 227         if (!sgen_gc_descr_has_references (desc))
 228                 ++stat_optimized_major_scan_no_refs;
 229         sgen_descriptor_count_scanned_object (desc);
 230 #endif
 231 #ifdef SGEN_HEAVY_BINARY_PROTOCOL
 232         add_scanned_object (start);
 233 #endif
 234
 235         /* Now scan the object. */
 236
 237 #undef HANDLE_PTR
 238 #if defined(COPY_OR_MARK_CONCURRENT_WITH_EVACUATION)
 239 #define HANDLE_PTR(ptr,obj)     do {                                    \
 240                 GCObject *__old = *(ptr);                               \
 241                 binary_protocol_scan_process_reference ((full_object), (ptr), __old); \
 242                 if (__old && !sgen_ptr_in_nursery (__old)) {            \
 243                         if (G_UNLIKELY (full_object && !sgen_ptr_in_nursery (ptr) && \
 244                                         sgen_safe_object_is_small (__old, sgen_obj_get_descriptor (__old) & DESC_TYPE_MASK) && \
 245                                         major_block_is_evacuating (MS_BLOCK_FOR_OBJ (__old)))) { \
 246                                 mark_mod_union_card ((full_object), (void**)(ptr), __old); \
 247                         } else {                                        \
 248                                 PREFETCH_READ (__old);                  \
 249                                 COPY_OR_MARK_FUNCTION_NAME ((ptr), __old, queue); \
 250                         }                                               \
 251                 } else {                                                \
 252                         if (G_UNLIKELY (full_object && sgen_ptr_in_nursery (__old) && !sgen_ptr_in_nursery ((ptr)) && !sgen_cement_is_forced (__old))) \
 253                                 mark_mod_union_card ((full_object), (void**)(ptr), __old); \
 254                         }                                               \
 255                 } while (0)
 256 #elif defined(COPY_OR_MARK_CONCURRENT)
 257 #define HANDLE_PTR(ptr,obj)     do {                                    \
 258                 GCObject *__old = *(ptr);                               \
 259                 binary_protocol_scan_process_reference ((full_object), (ptr), __old); \
 260                 if (__old && !sgen_ptr_in_nursery (__old)) {            \
 261                         PREFETCH_READ (__old);                  \
 262                         COPY_OR_MARK_FUNCTION_NAME ((ptr), __old, queue); \
 263                 } else {                                                \
 264                         if (G_UNLIKELY (full_object && sgen_ptr_in_nursery (__old) && !sgen_ptr_in_nursery ((ptr)) && !sgen_cement_is_forced (__old))) \
 265                                 mark_mod_union_card ((full_object), (void**)(ptr), __old); \
 266                         }                                               \
 267                 } while (0)
 268 #else
 269 #define HANDLE_PTR(ptr,obj)     do {                                    \
 270                 GCObject *__old = *(ptr);                                       \
 271                 binary_protocol_scan_process_reference ((full_object), (ptr), __old); \
 272                 if (__old) {                                            \
 273                         gboolean __still_in_nursery = COPY_OR_MARK_FUNCTION_NAME ((ptr), __old, queue); \
 274                         if (G_UNLIKELY (__still_in_nursery && !sgen_ptr_in_nursery ((ptr)) && !SGEN_OBJECT_IS_CEMENTED (*(ptr)))) { \
 275                                 GCObject *__copy = *(ptr);                      \
 276                                 sgen_add_to_global_remset ((ptr), __copy); \
 277                         }                                               \
 278                 }                                                       \
 279         } while (0)
 280 #endif
 281
 282 #define SCAN_OBJECT_PROTOCOL
 283 #include "sgen-scan-object.h"
 284 }
 285
 286 #ifdef SCAN_VTYPE_FUNCTION_NAME
 287 static void
 288 SCAN_VTYPE_FUNCTION_NAME (GCObject *full_object, char *start, SgenDescriptor desc, SgenGrayQueue *queue BINARY_PROTOCOL_ARG (size_t size))
 289 {
 290         SGEN_OBJECT_LAYOUT_STATISTICS_DECLARE_BITMAP;
 291
 292 #ifdef HEAVY_STATISTICS
 293         /* FIXME: We're half scanning this object.  How do we account for that? */
 294         //add_scanned_object (start);
 295 #endif
 296
 297         /* The descriptors include info about the object header as well */
 298         start -= SGEN_CLIENT_OBJECT_HEADER_SIZE;
 299
 300         /* We use the same HANDLE_PTR from the obj scan function */
 301 #define SCAN_OBJECT_NOVTABLE
 302 #define SCAN_OBJECT_PROTOCOL
 303 #include "sgen-scan-object.h"
 304
 305         SGEN_OBJECT_LAYOUT_STATISTICS_COMMIT_BITMAP;
 306 }
 307 #endif
 308
 309 #ifdef SCAN_PTR_FIELD_FUNCTION_NAME
 310 static void
 311 SCAN_PTR_FIELD_FUNCTION_NAME (GCObject *full_object, GCObject **ptr, SgenGrayQueue *queue)
 312 {
 313         /*
 314          * full_object is NULL if we scan unmanaged memory. This means we can't mark
 315          * mod unions for it, so these types of roots currently don't have support
 316          * for the concurrent collector (aka they need to be scanned as normal roots
 317          * both in the start and finishing pause)
 318          */
 319         HANDLE_PTR (ptr, NULL);
 320 }
 321 #endif
 322
 323 static gboolean
 324 DRAIN_GRAY_STACK_FUNCTION_NAME (SgenGrayQueue *queue)
 325 {
 326 #if defined(COPY_OR_MARK_CONCURRENT) || defined(COPY_OR_MARK_CONCURRENT_WITH_EVACUATION) || defined(COPY_OR_MARK_PARALLEL)
 327         int i;
 328         for (i = 0; i < 32; i++) {
 329 #else
 330         for (;;) {
 331 #endif
 332                 GCObject *obj;
 333                 SgenDescriptor desc;
 334
 335                 HEAVY_STAT (++stat_drain_loops);
 336
 337 #if defined(COPY_OR_MARK_PARALLEL)
 338                 GRAY_OBJECT_DEQUEUE_PARALLEL (queue, &obj, &desc);
 339 #else
 340                 GRAY_OBJECT_DEQUEUE_SERIAL (queue, &obj, &desc);
 341 #endif
 342                 if (!obj)
 343                         return TRUE;
 344
 345                 SCAN_OBJECT_FUNCTION_NAME (obj, desc, queue);
 346         }
 347         return FALSE;
 348 }
 349
 350 #undef COPY_OR_MARK_PARALLEL
 351 #undef COPY_OR_MARK_FUNCTION_NAME
 352 #undef COPY_OR_MARK_WITH_EVACUATION
 353 #undef COPY_OR_MARK_CONCURRENT
 354 #undef COPY_OR_MARK_CONCURRENT_WITH_EVACUATION
 355 #undef SCAN_OBJECT_FUNCTION_NAME
 356 #undef SCAN_VTYPE_FUNCTION_NAME
 357 #undef SCAN_PTR_FIELD_FUNCTION_NAME
 358 #undef DRAIN_GRAY_STACK_FUNCTION_NAME