Version 3.10.3

src/heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1106 matching lines @@
 
   while (head_start != head_end) {
     int size = static_cast<int>(*(head_start++));
     HeapObject* obj = reinterpret_cast<HeapObject*>(*(head_start++));
     emergency_stack_->Add(Entry(obj, size));
   }
   rear_ = head_end;
 }
 
 
+class ScavengeWeakObjectRetainer : public WeakObjectRetainer {
+ public:
+  explicit ScavengeWeakObjectRetainer(Heap* heap) : heap_(heap) { }
+
+  virtual Object* RetainAs(Object* object) {
+    if (!heap_->InFromSpace(object)) {
+      return object;
+    }
+
+    MapWord map_word = HeapObject::cast(object)->map_word();
+    if (map_word.IsForwardingAddress()) {
+      return map_word.ToForwardingAddress();
+    }
+    return NULL;
+  }
+
+ private:
+  Heap* heap_;
+};
+
+
 void Heap::Scavenge() {
 #ifdef DEBUG
   if (FLAG_verify_heap) VerifyNonPointerSpacePointers();
 #endif
 
   gc_state_ = SCAVENGE;
 
   // Implements Cheney's copying algorithm
   LOG(isolate_, ResourceEvent("scavenge", "begin"));
 
@@ skipping 78 matching lines @@
       &UpdateNewSpaceReferenceInExternalStringTableEntry);
 
   promotion_queue_.Destroy();
 
   LiveObjectList::UpdateReferencesForScavengeGC();
   if (!FLAG_watch_ic_patching) {
     isolate()->runtime_profiler()->UpdateSamplesAfterScavenge();
   }
   incremental_marking()->UpdateMarkingDequeAfterScavenge();
 
+  ScavengeWeakObjectRetainer weak_object_retainer(this);
+  ProcessWeakReferences(&weak_object_retainer);
+
   ASSERT(new_space_front == new_space_.top());
 
   // Set age mark.
   new_space_.set_age_mark(new_space_.top());
 
   new_space_.LowerInlineAllocationLimit(
       new_space_.inline_allocation_limit_step());
 
   // Update how much has survived scavenge.
   IncrementYoungSurvivorsCounter(static_cast<int>(
@@ skipping 66 matching lines @@
     Object** end = start + external_string_table_.old_space_strings_.length();
     for (Object** p = start; p < end; ++p) *p = updater_func(this, p);
   }
 
   UpdateNewSpaceReferencesInExternalStringTable(updater_func);
 }
 
 
 static Object* ProcessFunctionWeakReferences(Heap* heap,
                                              Object* function,
-                                             WeakObjectRetainer* retainer) {
+                                             WeakObjectRetainer* retainer,
+                                             bool record_slots) {
   Object* undefined = heap->undefined_value();
   Object* head = undefined;
   JSFunction* tail = NULL;
   Object* candidate = function;
   while (candidate != undefined) {
     // Check whether to keep the candidate in the list.
     JSFunction* candidate_function = reinterpret_cast<JSFunction*>(candidate);
     Object* retain = retainer->RetainAs(candidate);
     if (retain != NULL) {
       if (head == undefined) {
         // First element in the list.
         head = retain;
       } else {
         // Subsequent elements in the list.
         ASSERT(tail != NULL);
         tail->set_next_function_link(retain);
+        if (record_slots) {
+          Object** next_function =
+              HeapObject::RawField(tail, JSFunction::kNextFunctionLinkOffset);
+          heap->mark_compact_collector()->RecordSlot(
+              next_function, next_function, retain);
+        }
       }
       // Retained function is new tail.
       candidate_function = reinterpret_cast<JSFunction*>(retain);
       tail = candidate_function;
 
       ASSERT(retain->IsUndefined() || retain->IsJSFunction());
 
       if (retain == undefined) break;
     }
 
     // Move to next element in the list.
     candidate = candidate_function->next_function_link();
   }
 
   // Terminate the list if there is one or more elements.
   if (tail != NULL) {
     tail->set_next_function_link(undefined);
   }
 
   return head;
 }
 
 
 void Heap::ProcessWeakReferences(WeakObjectRetainer* retainer) {
   Object* undefined = undefined_value();
   Object* head = undefined;
   Context* tail = NULL;
   Object* candidate = global_contexts_list_;
+
+  // We don't record weak slots during marking or scavenges.
+  // Instead we do it once when we complete mark-compact cycle.
+  // Note that write barrier has no effect if we are already in the middle of
+  // compacting mark-sweep cycle and we have to record slots manually.
+  bool record_slots =
+      gc_state() == MARK_COMPACT &&
+      mark_compact_collector()->is_compacting();
+
   while (candidate != undefined) {
     // Check whether to keep the candidate in the list.
     Context* candidate_context = reinterpret_cast<Context*>(candidate);
     Object* retain = retainer->RetainAs(candidate);
     if (retain != NULL) {
       if (head == undefined) {
         // First element in the list.
         head = retain;
       } else {
         // Subsequent elements in the list.
         ASSERT(tail != NULL);
         tail->set_unchecked(this,
                             Context::NEXT_CONTEXT_LINK,
                             retain,
                             UPDATE_WRITE_BARRIER);
+
+        if (record_slots) {
+          Object** next_context =
+              HeapObject::RawField(
+                  tail, FixedArray::SizeFor(Context::NEXT_CONTEXT_LINK));
+          mark_compact_collector()->RecordSlot(
+              next_context, next_context, retain);
+        }
       }
       // Retained context is new tail.
       candidate_context = reinterpret_cast<Context*>(retain);
       tail = candidate_context;
 
       if (retain == undefined) break;
 
       // Process the weak list of optimized functions for the context.
       Object* function_list_head =
           ProcessFunctionWeakReferences(
               this,
               candidate_context->get(Context::OPTIMIZED_FUNCTIONS_LIST),
-              retainer);
+              retainer,
+              record_slots);
       candidate_context->set_unchecked(this,
                                        Context::OPTIMIZED_FUNCTIONS_LIST,
                                        function_list_head,
                                        UPDATE_WRITE_BARRIER);
+      if (record_slots) {
+        Object** optimized_functions =
+            HeapObject::RawField(
+                tail, FixedArray::SizeFor(Context::OPTIMIZED_FUNCTIONS_LIST));
+        mark_compact_collector()->RecordSlot(
+            optimized_functions, optimized_functions, function_list_head);
+      }
     }
 
     // Move to next element in the list.
     candidate = candidate_context->get(Context::NEXT_CONTEXT_LINK);
   }
 
   // Terminate the list if there is one or more elements.
   if (tail != NULL) {
     tail->set_unchecked(this,
                         Context::NEXT_CONTEXT_LINK,
@@ skipping 79 matching lines @@
     }
 
     // Take another spin if there are now unswept objects in new space
     // (there are currently no more unswept promoted objects).
   } while (new_space_front != new_space_.top());
 
   return new_space_front;
 }
 
 
+STATIC_ASSERT((FixedDoubleArray::kHeaderSize & kDoubleAlignmentMask) == 0);
+
+
+INLINE(static HeapObject* EnsureDoubleAligned(Heap* heap,
+                                              HeapObject* object,
+                                              int size));
+
+static HeapObject* EnsureDoubleAligned(Heap* heap,
+                                       HeapObject* object,
+                                       int size) {
+  if ((OffsetFrom(object->address()) & kDoubleAlignmentMask) != 0) {
+    heap->CreateFillerObjectAt(object->address(), kPointerSize);
+    return HeapObject::FromAddress(object->address() + kPointerSize);
+  } else {
+    heap->CreateFillerObjectAt(object->address() + size - kPointerSize,
+                               kPointerSize);
+    return object;
+  }
+}
+
+
 enum LoggingAndProfiling {
   LOGGING_AND_PROFILING_ENABLED,
   LOGGING_AND_PROFILING_DISABLED
 };
 
 
 enum MarksHandling { TRANSFER_MARKS, IGNORE_MARKS };
 
 
 template<MarksHandling marks_handling,
@@ skipping 103 matching lines @@
       }
     }
 
     if (marks_handling == TRANSFER_MARKS) {
       if (Marking::TransferColor(source, target)) {
         MemoryChunk::IncrementLiveBytesFromGC(target->address(), size);
       }
     }
   }
 
-  template<ObjectContents object_contents, SizeRestriction size_restriction>
+
+  template<ObjectContents object_contents,
+           SizeRestriction size_restriction,
+           int alignment>
   static inline void EvacuateObject(Map* map,
                                     HeapObject** slot,
                                     HeapObject* object,
                                     int object_size) {
     SLOW_ASSERT((size_restriction != SMALL) ||
                 (object_size <= Page::kMaxNonCodeHeapObjectSize));
     SLOW_ASSERT(object->Size() == object_size);
 
+    int allocation_size = object_size;
+    if (alignment != kObjectAlignment) {
+      ASSERT(alignment == kDoubleAlignment);
+      allocation_size += kPointerSize;
+    }
+
     Heap* heap = map->GetHeap();
     if (heap->ShouldBePromoted(object->address(), object_size)) {
       MaybeObject* maybe_result;
 
       if ((size_restriction != SMALL) &&
-          (object_size > Page::kMaxNonCodeHeapObjectSize)) {
-        maybe_result = heap->lo_space()->AllocateRaw(object_size,
+          (allocation_size > Page::kMaxNonCodeHeapObjectSize)) {
+        maybe_result = heap->lo_space()->AllocateRaw(allocation_size,
                                                      NOT_EXECUTABLE);
       } else {
         if (object_contents == DATA_OBJECT) {
-          maybe_result = heap->old_data_space()->AllocateRaw(object_size);
+          maybe_result = heap->old_data_space()->AllocateRaw(allocation_size);
         } else {
-          maybe_result = heap->old_pointer_space()->AllocateRaw(object_size);
+          maybe_result =
+              heap->old_pointer_space()->AllocateRaw(allocation_size);
         }
       }
 
       Object* result = NULL;  // Initialization to please compiler.
       if (maybe_result->ToObject(&result)) {
         HeapObject* target = HeapObject::cast(result);
 
+        if (alignment != kObjectAlignment) {
+          target = EnsureDoubleAligned(heap, target, allocation_size);
+        }
+
         // Order is important: slot might be inside of the target if target
         // was allocated over a dead object and slot comes from the store
         // buffer.
         *slot = target;
         MigrateObject(heap, object, target, object_size);
 
         if (object_contents == POINTER_OBJECT) {
-          heap->promotion_queue()->insert(target, object_size);
+          if (map->instance_type() == JS_FUNCTION_TYPE) {
+            heap->promotion_queue()->insert(
+                target, JSFunction::kNonWeakFieldsEndOffset);
+          } else {
+            heap->promotion_queue()->insert(target, object_size);
+          }
         }
 
         heap->tracer()->increment_promoted_objects_size(object_size);
         return;
       }
     }
-    MaybeObject* allocation = heap->new_space()->AllocateRaw(object_size);
+    MaybeObject* allocation = heap->new_space()->AllocateRaw(allocation_size);
     heap->promotion_queue()->SetNewLimit(heap->new_space()->top());
     Object* result = allocation->ToObjectUnchecked();
     HeapObject* target = HeapObject::cast(result);
 
+    if (alignment != kObjectAlignment) {
+      target = EnsureDoubleAligned(heap, target, allocation_size);
+    }
+
     // Order is important: slot might be inside of the target if target
     // was allocated over a dead object and slot comes from the store
     // buffer.
     *slot = target;
     MigrateObject(heap, object, target, object_size);
     return;
   }
 
 
   static inline void EvacuateJSFunction(Map* map,
@@ skipping 15 matching lines @@
       map->GetHeap()->mark_compact_collector()->
           RecordCodeEntrySlot(code_entry_slot, code);
     }
   }
 
 
   static inline void EvacuateFixedArray(Map* map,
                                         HeapObject** slot,
                                         HeapObject* object) {
     int object_size = FixedArray::BodyDescriptor::SizeOf(map, object);
-    EvacuateObject<POINTER_OBJECT, UNKNOWN_SIZE>(map,
+    EvacuateObject<POINTER_OBJECT, UNKNOWN_SIZE, kObjectAlignment>(map,
                                                  slot,
                                                  object,
                                                  object_size);
   }
 
 
   static inline void EvacuateFixedDoubleArray(Map* map,
                                               HeapObject** slot,
                                               HeapObject* object) {
     int length = reinterpret_cast<FixedDoubleArray*>(object)->length();
     int object_size = FixedDoubleArray::SizeFor(length);
-    EvacuateObject<DATA_OBJECT, UNKNOWN_SIZE>(map,
-                                              slot,
-                                              object,
-                                              object_size);
+    EvacuateObject<DATA_OBJECT, UNKNOWN_SIZE, kDoubleAlignment>(
+        map,
+        slot,
+        object,
+        object_size);
   }
 
 
   static inline void EvacuateByteArray(Map* map,
                                        HeapObject** slot,
                                        HeapObject* object) {
     int object_size = reinterpret_cast<ByteArray*>(object)->ByteArraySize();
-    EvacuateObject<DATA_OBJECT, UNKNOWN_SIZE>(map, slot, object, object_size);
+    EvacuateObject<DATA_OBJECT, UNKNOWN_SIZE, kObjectAlignment>(
+        map, slot, object, object_size);
   }
 
 
   static inline void EvacuateSeqAsciiString(Map* map,
                                             HeapObject** slot,
                                             HeapObject* object) {
     int object_size = SeqAsciiString::cast(object)->
         SeqAsciiStringSize(map->instance_type());
-    EvacuateObject<DATA_OBJECT, UNKNOWN_SIZE>(map, slot, object, object_size);
+    EvacuateObject<DATA_OBJECT, UNKNOWN_SIZE, kObjectAlignment>(
+        map, slot, object, object_size);
   }
 
 
   static inline void EvacuateSeqTwoByteString(Map* map,
                                               HeapObject** slot,
                                               HeapObject* object) {
     int object_size = SeqTwoByteString::cast(object)->
         SeqTwoByteStringSize(map->instance_type());
-    EvacuateObject<DATA_OBJECT, UNKNOWN_SIZE>(map, slot, object, object_size);
+    EvacuateObject<DATA_OBJECT, UNKNOWN_SIZE, kObjectAlignment>(
+        map, slot, object, object_size);
   }
 
 
   static inline bool IsShortcutCandidate(int type) {
     return ((type & kShortcutTypeMask) == kShortcutTypeTag);
   }
 
   static inline void EvacuateShortcutCandidate(Map* map,
                                                HeapObject** slot,
                                                HeapObject* object) {
@@ skipping 22 matching lines @@
         object->set_map_word(MapWord::FromForwardingAddress(target));
         return;
       }
 
       heap->DoScavengeObject(first->map(), slot, first);
       object->set_map_word(MapWord::FromForwardingAddress(*slot));
       return;
     }
 
     int object_size = ConsString::kSize;
-    EvacuateObject<POINTER_OBJECT, SMALL>(map, slot, object, object_size);
+    EvacuateObject<POINTER_OBJECT, SMALL, kObjectAlignment>(
+        map, slot, object, object_size);
   }
 
   template<ObjectContents object_contents>
   class ObjectEvacuationStrategy {
    public:
     template<int object_size>
     static inline void VisitSpecialized(Map* map,
                                         HeapObject** slot,
                                         HeapObject* object) {
-      EvacuateObject<object_contents, SMALL>(map, slot, object, object_size);
+      EvacuateObject<object_contents, SMALL, kObjectAlignment>(
+          map, slot, object, object_size);
     }
 
     static inline void Visit(Map* map,
                              HeapObject** slot,
                              HeapObject* object) {
       int object_size = map->instance_size();
-      EvacuateObject<object_contents, SMALL>(map, slot, object, object_size);
+      EvacuateObject<object_contents, SMALL, kObjectAlignment>(
+          map, slot, object, object_size);
     }
   };
 
   static VisitorDispatchTable<ScavengingCallback> table_;
 };
 
 
 template<MarksHandling marks_handling,
          LoggingAndProfiling logging_and_profiling_mode>
 VisitorDispatchTable<ScavengingCallback>
@@ skipping 2015 matching lines @@
       constructor->initial_map(), pretenure);
 #ifdef DEBUG
   // Make sure result is NOT a global object if valid.
   Object* non_failure;
   ASSERT(!result->ToObject(&non_failure) || !non_failure->IsGlobalObject());
 #endif
   return result;
 }
 
 
+MaybeObject* Heap::AllocateJSModule() {
+  // Allocate a fresh map. Modules do not have a prototype.
+  Map* map;
+  MaybeObject* maybe_map = AllocateMap(JS_MODULE_TYPE, JSModule::kSize);
+  if (!maybe_map->To(&map)) return maybe_map;
+  // Allocate the object based on the map.
+  return AllocateJSObjectFromMap(map, TENURED);
+}
+
+
 MaybeObject* Heap::AllocateJSArrayAndStorage(
     ElementsKind elements_kind,
     int length,
     int capacity,
     ArrayStorageAllocationMode mode,
     PretenureFlag pretenure) {
   ASSERT(capacity >= length);
   MaybeObject* maybe_array = AllocateJSArray(elements_kind, pretenure);
   JSArray* array;
   if (!maybe_array->To(&array)) return maybe_array;
@@ skipping 116 matching lines @@
         StringDictionary::Allocate(
             map->NumberOfDescribedProperties() * 2 + initial_size);
     if (!maybe_obj->ToObject(&obj)) return maybe_obj;
   }
   StringDictionary* dictionary = StringDictionary::cast(obj);
 
   // The global object might be created from an object template with accessors.
   // Fill these accessors into the dictionary.
   DescriptorArray* descs = map->instance_descriptors();
   for (int i = 0; i < descs->number_of_descriptors(); i++) {
-    PropertyDetails details(descs->GetDetails(i));
+    PropertyDetails details = descs->GetDetails(i);
     ASSERT(details.type() == CALLBACKS);  // Only accessors are expected.
     PropertyDetails d =
         PropertyDetails(details.attributes(), CALLBACKS, details.index());
     Object* value = descs->GetCallbacksObject(i);
     { MaybeObject* maybe_value = AllocateJSGlobalPropertyCell(value);
       if (!maybe_value->ToObject(&value)) return maybe_value;
     }
 
     Object* result;
     { MaybeObject* maybe_result = dictionary->Add(descs->GetKey(i), value, d);
@@ skipping 672 matching lines @@
 
 MaybeObject* Heap::AllocateRawFixedDoubleArray(int length,
                                                PretenureFlag pretenure) {
   if (length < 0 || length > FixedDoubleArray::kMaxLength) {
     return Failure::OutOfMemoryException();
   }
 
   AllocationSpace space =
       (pretenure == TENURED) ? OLD_DATA_SPACE : NEW_SPACE;
   int size = FixedDoubleArray::SizeFor(length);
+
+#ifndef V8_HOST_ARCH_64_BIT
+  size += kPointerSize;
+#endif
+
   if (space == NEW_SPACE && size > kMaxObjectSizeInNewSpace) {
     // Too big for new space.
     space = LO_SPACE;
   } else if (space == OLD_DATA_SPACE &&
              size > Page::kMaxNonCodeHeapObjectSize) {
     // Too big for old data space.
     space = LO_SPACE;
   }
 
   AllocationSpace retry_space =
       (size <= Page::kMaxNonCodeHeapObjectSize) ? OLD_DATA_SPACE : LO_SPACE;
 
-  return AllocateRaw(size, space, retry_space);
+  HeapObject* object;
+  { MaybeObject* maybe_object = AllocateRaw(size, space, retry_space);
+    if (!maybe_object->To<HeapObject>(&object)) return maybe_object;
+  }
+
+  return EnsureDoubleAligned(this, object, size);
 }
 
 
 MaybeObject* Heap::AllocateHashTable(int length, PretenureFlag pretenure) {
   Object* result;
   { MaybeObject* maybe_result = AllocateFixedArray(length, pretenure);
     if (!maybe_result->ToObject(&result)) return maybe_result;
   }
   reinterpret_cast<HeapObject*>(result)->set_map_no_write_barrier(
       hash_table_map());
@@ skipping 12 matching lines @@
   context->set_map_no_write_barrier(global_context_map());
   context->set_smi_js_array_map(undefined_value());
   context->set_double_js_array_map(undefined_value());
   context->set_object_js_array_map(undefined_value());
   ASSERT(context->IsGlobalContext());
   ASSERT(result->IsContext());
   return result;
 }
 
 
+MaybeObject* Heap::AllocateModuleContext(Context* previous,
+                                         ScopeInfo* scope_info) {
+  Object* result;
+  { MaybeObject* maybe_result =
+        AllocateFixedArrayWithHoles(scope_info->ContextLength(), TENURED);
+    if (!maybe_result->ToObject(&result)) return maybe_result;
+  }
+  Context* context = reinterpret_cast<Context*>(result);
+  context->set_map_no_write_barrier(module_context_map());
+  context->set_previous(previous);
+  context->set_extension(scope_info);
+  context->set_global(previous->global());
+  return context;
+}
+
+
 MaybeObject* Heap::AllocateFunctionContext(int length, JSFunction* function) {
   ASSERT(length >= Context::MIN_CONTEXT_SLOTS);
   Object* result;
   { MaybeObject* maybe_result = AllocateFixedArray(length);
     if (!maybe_result->ToObject(&result)) return maybe_result;
   }
   Context* context = reinterpret_cast<Context*>(result);
   context->set_map_no_write_barrier(function_context_map());
   context->set_closure(function);
   context->set_previous(function->context());
@@ skipping 2266 matching lines @@
   } else {
     p ^= 0x1d1ed & (Page::kPageSize - 1);  // I died.
   }
   remembered_unmapped_pages_[remembered_unmapped_pages_index_] =
       reinterpret_cast<Address>(p);
   remembered_unmapped_pages_index_++;
   remembered_unmapped_pages_index_ %= kRememberedUnmappedPages;
 }
 
 } }  // namespace v8::internal