src/v8/src/objects-visiting.cc

   1 // Copyright 2011 the V8 project authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "src/v8.h"
   6
   7 #include "src/ic-inl.h"
   8 #include "src/objects-visiting.h"
   9
  10 namespace v8 {
  11 namespace internal {
  12
  13
  14 static inline bool IsShortcutCandidate(int type) {
  15   return ((type & kShortcutTypeMask) == kShortcutTypeTag);
  16 }
  17
  18
  19 StaticVisitorBase::VisitorId StaticVisitorBase::GetVisitorId(
  20     int instance_type,
  21     int instance_size) {
  22   if (instance_type < FIRST_NONSTRING_TYPE) {
  23     switch (instance_type & kStringRepresentationMask) {
  24       case kSeqStringTag:
  25         if ((instance_type & kStringEncodingMask) == kOneByteStringTag) {
  26           return kVisitSeqOneByteString;
  27         } else {
  28           return kVisitSeqTwoByteString;
  29         }
  30
  31       case kConsStringTag:
  32         if (IsShortcutCandidate(instance_type)) {
  33           return kVisitShortcutCandidate;
  34         } else {
  35           return kVisitConsString;
  36         }
  37
  38       case kSlicedStringTag:
  39         return kVisitSlicedString;
  40
  41       case kExternalStringTag:
  42         return GetVisitorIdForSize(kVisitDataObject,
  43                                    kVisitDataObjectGeneric,
  44                                    instance_size);
  45     }
  46     UNREACHABLE();
  47   }
  48
  49   switch (instance_type) {
  50     case BYTE_ARRAY_TYPE:
  51       return kVisitByteArray;
  52
  53     case FREE_SPACE_TYPE:
  54       return kVisitFreeSpace;
  55
  56     case FIXED_ARRAY_TYPE:
  57       return kVisitFixedArray;
  58
  59     case FIXED_DOUBLE_ARRAY_TYPE:
  60       return kVisitFixedDoubleArray;
  61
  62     case CONSTANT_POOL_ARRAY_TYPE:
  63       return kVisitConstantPoolArray;
  64
  65     case ODDBALL_TYPE:
  66       return kVisitOddball;
  67
  68     case MAP_TYPE:
  69       return kVisitMap;
  70
  71     case CODE_TYPE:
  72       return kVisitCode;
  73
  74     case CELL_TYPE:
  75       return kVisitCell;
  76
  77     case PROPERTY_CELL_TYPE:
  78       return kVisitPropertyCell;
  79
  80     case JS_SET_TYPE:
  81       return GetVisitorIdForSize(kVisitStruct,
  82                                  kVisitStructGeneric,
  83                                  JSSet::kSize);
  84
  85     case JS_MAP_TYPE:
  86       return GetVisitorIdForSize(kVisitStruct,
  87                                  kVisitStructGeneric,
  88                                  JSMap::kSize);
  89
  90     case JS_WEAK_MAP_TYPE:
  91     case JS_WEAK_SET_TYPE:
  92       return kVisitJSWeakCollection;
  93
  94     case JS_REGEXP_TYPE:
  95       return kVisitJSRegExp;
  96
  97     case SHARED_FUNCTION_INFO_TYPE:
  98       return kVisitSharedFunctionInfo;
  99
 100     case JS_PROXY_TYPE:
 101       return GetVisitorIdForSize(kVisitStruct,
 102                                  kVisitStructGeneric,
 103                                  JSProxy::kSize);
 104
 105     case JS_FUNCTION_PROXY_TYPE:
 106       return GetVisitorIdForSize(kVisitStruct,
 107                                  kVisitStructGeneric,
 108                                  JSFunctionProxy::kSize);
 109
 110     case FOREIGN_TYPE:
 111       return GetVisitorIdForSize(kVisitDataObject,
 112                                  kVisitDataObjectGeneric,
 113                                  Foreign::kSize);
 114
 115     case SYMBOL_TYPE:
 116       return kVisitSymbol;
 117
 118     case FILLER_TYPE:
 119       return kVisitDataObjectGeneric;
 120
 121     case JS_ARRAY_BUFFER_TYPE:
 122       return kVisitJSArrayBuffer;
 123
 124     case JS_TYPED_ARRAY_TYPE:
 125       return kVisitJSTypedArray;
 126
 127     case JS_DATA_VIEW_TYPE:
 128       return kVisitJSDataView;
 129
 130     case JS_OBJECT_TYPE:
 131     case JS_CONTEXT_EXTENSION_OBJECT_TYPE:
 132     case JS_GENERATOR_OBJECT_TYPE:
 133     case JS_MODULE_TYPE:
 134     case JS_VALUE_TYPE:
 135     case JS_DATE_TYPE:
 136     case JS_ARRAY_TYPE:
 137     case JS_GLOBAL_PROXY_TYPE:
 138     case JS_GLOBAL_OBJECT_TYPE:
 139     case JS_BUILTINS_OBJECT_TYPE:
 140     case JS_MESSAGE_OBJECT_TYPE:
 141     case JS_SET_ITERATOR_TYPE:
 142     case JS_MAP_ITERATOR_TYPE:
 143     case FLOAT32x4_TYPE:
 144     case FLOAT64x2_TYPE:
 145     case INT32x4_TYPE:
 146       return GetVisitorIdForSize(kVisitJSObject,
 147                                  kVisitJSObjectGeneric,
 148                                  instance_size);
 149
 150     case JS_FUNCTION_TYPE:
 151       return kVisitJSFunction;
 152
 153     case HEAP_NUMBER_TYPE:
 154 #define EXTERNAL_ARRAY_CASE(Type, type, TYPE, ctype, size)                     \
 155     case EXTERNAL_##TYPE##_ARRAY_TYPE:
 156
 157     TYPED_ARRAYS(EXTERNAL_ARRAY_CASE)
 158       return GetVisitorIdForSize(kVisitDataObject,
 159                                  kVisitDataObjectGeneric,
 160                                  instance_size);
 161 #undef EXTERNAL_ARRAY_CASE
 162
 163     case FIXED_UINT8_ARRAY_TYPE:
 164     case FIXED_INT8_ARRAY_TYPE:
 165     case FIXED_UINT16_ARRAY_TYPE:
 166     case FIXED_INT16_ARRAY_TYPE:
 167     case FIXED_UINT32_ARRAY_TYPE:
 168     case FIXED_INT32_ARRAY_TYPE:
 169     case FIXED_FLOAT32_ARRAY_TYPE:
 170     case FIXED_INT32x4_ARRAY_TYPE:
 171     case FIXED_FLOAT32x4_ARRAY_TYPE:
 172     case FIXED_FLOAT64x2_ARRAY_TYPE:
 173     case FIXED_UINT8_CLAMPED_ARRAY_TYPE:
 174       return kVisitFixedTypedArray;
 175
 176     case FIXED_FLOAT64_ARRAY_TYPE:
 177       return kVisitFixedFloat64Array;
 178
 179 #define MAKE_STRUCT_CASE(NAME, Name, name) \
 180         case NAME##_TYPE:
 181       STRUCT_LIST(MAKE_STRUCT_CASE)
 182 #undef MAKE_STRUCT_CASE
 183           if (instance_type == ALLOCATION_SITE_TYPE) {
 184             return kVisitAllocationSite;
 185           }
 186
 187           return GetVisitorIdForSize(kVisitStruct,
 188                                      kVisitStructGeneric,
 189                                      instance_size);
 190
 191     default:
 192       UNREACHABLE();
 193       return kVisitorIdCount;
 194   }
 195 }
 196
 197
 198 // We don't record weak slots during marking or scavenges. Instead we do it
 199 // once when we complete mark-compact cycle.  Note that write barrier has no
 200 // effect if we are already in the middle of compacting mark-sweep cycle and we
 201 // have to record slots manually.
 202 static bool MustRecordSlots(Heap* heap) {
 203   return heap->gc_state() == Heap::MARK_COMPACT &&
 204       heap->mark_compact_collector()->is_compacting();
 205 }
 206
 207
 208 template <class T>
 209 struct WeakListVisitor;
 210
 211
 212 template <class T>
 213 Object* VisitWeakList(Heap* heap,
 214                       Object* list,
 215                       WeakObjectRetainer* retainer) {
 216   Object* undefined = heap->undefined_value();
 217   Object* head = undefined;
 218   T* tail = NULL;
 219   MarkCompactCollector* collector = heap->mark_compact_collector();
 220   bool record_slots = MustRecordSlots(heap);
 221   while (list != undefined) {
 222     // Check whether to keep the candidate in the list.
 223     T* candidate = reinterpret_cast<T*>(list);
 224     Object* retained = retainer->RetainAs(list);
 225     if (retained != NULL) {
 226       if (head == undefined) {
 227         // First element in the list.
 228         head = retained;
 229       } else {
 230         // Subsequent elements in the list.
 231         ASSERT(tail != NULL);
 232         WeakListVisitor<T>::SetWeakNext(tail, retained);
 233         if (record_slots) {
 234           Object** next_slot =
 235             HeapObject::RawField(tail, WeakListVisitor<T>::WeakNextOffset());
 236           collector->RecordSlot(next_slot, next_slot, retained);
 237         }
 238       }
 239       // Retained object is new tail.
 240       ASSERT(!retained->IsUndefined());
 241       candidate = reinterpret_cast<T*>(retained);
 242       tail = candidate;
 243
 244
 245       // tail is a live object, visit it.
 246       WeakListVisitor<T>::VisitLiveObject(heap, tail, retainer);
 247     } else {
 248       WeakListVisitor<T>::VisitPhantomObject(heap, candidate);
 249     }
 250
 251     // Move to next element in the list.
 252     list = WeakListVisitor<T>::WeakNext(candidate);
 253   }
 254
 255   // Terminate the list if there is one or more elements.
 256   if (tail != NULL) {
 257     WeakListVisitor<T>::SetWeakNext(tail, undefined);
 258   }
 259   return head;
 260 }
 261
 262
 263 template <class T>
 264 static void ClearWeakList(Heap* heap,
 265                           Object* list) {
 266   Object* undefined = heap->undefined_value();
 267   while (list != undefined) {
 268     T* candidate = reinterpret_cast<T*>(list);
 269     list = WeakListVisitor<T>::WeakNext(candidate);
 270     WeakListVisitor<T>::SetWeakNext(candidate, undefined);
 271   }
 272 }
 273
 274
 275 template<>
 276 struct WeakListVisitor<JSFunction> {
 277   static void SetWeakNext(JSFunction* function, Object* next) {
 278     function->set_next_function_link(next);
 279   }
 280
 281   static Object* WeakNext(JSFunction* function) {
 282     return function->next_function_link();
 283   }
 284
 285   static int WeakNextOffset() {
 286     return JSFunction::kNextFunctionLinkOffset;
 287   }
 288
 289   static void VisitLiveObject(Heap*, JSFunction*, WeakObjectRetainer*) {}
 290
 291   static void VisitPhantomObject(Heap*, JSFunction*) {}
 292 };
 293
 294
 295 template<>
 296 struct WeakListVisitor<Code> {
 297   static void SetWeakNext(Code* code, Object* next) {
 298     code->set_next_code_link(next);
 299   }
 300
 301   static Object* WeakNext(Code* code) {
 302     return code->next_code_link();
 303   }
 304
 305   static int WeakNextOffset() {
 306     return Code::kNextCodeLinkOffset;
 307   }
 308
 309   static void VisitLiveObject(Heap*, Code*, WeakObjectRetainer*) {}
 310
 311   static void VisitPhantomObject(Heap*, Code*) {}
 312 };
 313
 314
 315 template<>
 316 struct WeakListVisitor<Context> {
 317   static void SetWeakNext(Context* context, Object* next) {
 318     context->set(Context::NEXT_CONTEXT_LINK,
 319                  next,
 320                  UPDATE_WRITE_BARRIER);
 321   }
 322
 323   static Object* WeakNext(Context* context) {
 324     return context->get(Context::NEXT_CONTEXT_LINK);
 325   }
 326
 327   static int WeakNextOffset() {
 328     return FixedArray::SizeFor(Context::NEXT_CONTEXT_LINK);
 329   }
 330
 331   static void VisitLiveObject(Heap* heap,
 332                               Context* context,
 333                               WeakObjectRetainer* retainer) {
 334     // Process the three weak lists linked off the context.
 335     DoWeakList<JSFunction>(heap, context, retainer,
 336         Context::OPTIMIZED_FUNCTIONS_LIST);
 337     DoWeakList<Code>(heap, context, retainer, Context::OPTIMIZED_CODE_LIST);
 338     DoWeakList<Code>(heap, context, retainer, Context::DEOPTIMIZED_CODE_LIST);
 339   }
 340
 341   template<class T>
 342   static void DoWeakList(Heap* heap,
 343                          Context* context,
 344                          WeakObjectRetainer* retainer,
 345                          int index) {
 346     // Visit the weak list, removing dead intermediate elements.
 347     Object* list_head = VisitWeakList<T>(heap, context->get(index), retainer);
 348
 349     // Update the list head.
 350     context->set(index, list_head, UPDATE_WRITE_BARRIER);
 351
 352     if (MustRecordSlots(heap)) {
 353       // Record the updated slot if necessary.
 354       Object** head_slot = HeapObject::RawField(
 355           context, FixedArray::SizeFor(index));
 356       heap->mark_compact_collector()->RecordSlot(
 357           head_slot, head_slot, list_head);
 358     }
 359   }
 360
 361   static void VisitPhantomObject(Heap* heap, Context* context) {
 362     ClearWeakList<JSFunction>(heap,
 363         context->get(Context::OPTIMIZED_FUNCTIONS_LIST));
 364     ClearWeakList<Code>(heap, context->get(Context::OPTIMIZED_CODE_LIST));
 365     ClearWeakList<Code>(heap, context->get(Context::DEOPTIMIZED_CODE_LIST));
 366   }
 367 };
 368
 369
 370 template<>
 371 struct WeakListVisitor<JSArrayBufferView> {
 372   static void SetWeakNext(JSArrayBufferView* obj, Object* next) {
 373     obj->set_weak_next(next);
 374   }
 375
 376   static Object* WeakNext(JSArrayBufferView* obj) {
 377     return obj->weak_next();
 378   }
 379
 380   static int WeakNextOffset() {
 381     return JSArrayBufferView::kWeakNextOffset;
 382   }
 383
 384   static void VisitLiveObject(Heap*, JSArrayBufferView*, WeakObjectRetainer*) {}
 385
 386   static void VisitPhantomObject(Heap*, JSArrayBufferView*) {}
 387 };
 388
 389
 390 template<>
 391 struct WeakListVisitor<JSArrayBuffer> {
 392   static void SetWeakNext(JSArrayBuffer* obj, Object* next) {
 393     obj->set_weak_next(next);
 394   }
 395
 396   static Object* WeakNext(JSArrayBuffer* obj) {
 397     return obj->weak_next();
 398   }
 399
 400   static int WeakNextOffset() {
 401     return JSArrayBuffer::kWeakNextOffset;
 402   }
 403
 404   static void VisitLiveObject(Heap* heap,
 405                               JSArrayBuffer* array_buffer,
 406                               WeakObjectRetainer* retainer) {
 407     Object* typed_array_obj =
 408         VisitWeakList<JSArrayBufferView>(
 409             heap,
 410             array_buffer->weak_first_view(),
 411             retainer);
 412     array_buffer->set_weak_first_view(typed_array_obj);
 413     if (typed_array_obj != heap->undefined_value() && MustRecordSlots(heap)) {
 414       Object** slot = HeapObject::RawField(
 415           array_buffer, JSArrayBuffer::kWeakFirstViewOffset);
 416       heap->mark_compact_collector()->RecordSlot(slot, slot, typed_array_obj);
 417     }
 418   }
 419
 420   static void VisitPhantomObject(Heap* heap, JSArrayBuffer* phantom) {
 421     Runtime::FreeArrayBuffer(heap->isolate(), phantom);
 422   }
 423 };
 424
 425
 426 template<>
 427 struct WeakListVisitor<AllocationSite> {
 428   static void SetWeakNext(AllocationSite* obj, Object* next) {
 429     obj->set_weak_next(next);
 430   }
 431
 432   static Object* WeakNext(AllocationSite* obj) {
 433     return obj->weak_next();
 434   }
 435
 436   static int WeakNextOffset() {
 437     return AllocationSite::kWeakNextOffset;
 438   }
 439
 440   static void VisitLiveObject(Heap*, AllocationSite*, WeakObjectRetainer*) {}
 441
 442   static void VisitPhantomObject(Heap*, AllocationSite*) {}
 443 };
 444
 445
 446 template Object* VisitWeakList<Code>(
 447     Heap* heap, Object* list, WeakObjectRetainer* retainer);
 448
 449
 450 template Object* VisitWeakList<JSFunction>(
 451     Heap* heap, Object* list, WeakObjectRetainer* retainer);
 452
 453
 454 template Object* VisitWeakList<Context>(
 455     Heap* heap, Object* list, WeakObjectRetainer* retainer);
 456
 457
 458 template Object* VisitWeakList<JSArrayBuffer>(
 459     Heap* heap, Object* list, WeakObjectRetainer* retainer);
 460
 461
 462 template Object* VisitWeakList<AllocationSite>(
 463     Heap* heap, Object* list, WeakObjectRetainer* retainer);
 464
 465 } }  // namespace v8::internal