deps: upgrade v8 to 3.31.74.1

PR-URL: https://github.com/iojs/io.js/pull/243
Reviewed-By: Fedor Indutny <fedor@indutny.com>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>

1 files changed, 131 insertions, 177 deletions

diff --git a/deps/v8/src/heap/mark-compact.cc b/deps/v8/src/heap/mark-compact.cc
index 2cefebf980..fa127db612 100644
--- a/deps/v8/src/heap/mark-compact.cc
+++ b/deps/v8/src/heap/mark-compact.cc
@@ -47,9 +47,11 @@ MarkCompactCollector::MarkCompactCollector(Heap* heap)
       was_marked_incrementally_(false),
       sweeping_in_progress_(false),
       pending_sweeper_jobs_semaphore_(0),
-      sequential_sweeping_(false),
+      evacuation_(false),
       migration_slots_buffer_(NULL),
       heap_(heap),
+      marking_deque_memory_(NULL),
+      marking_deque_memory_committed_(false),
       code_flusher_(NULL),
       have_code_to_deoptimize_(false) {
 }
@@ -233,7 +235,10 @@ void MarkCompactCollector::SetUp() {
 }
 
 
-void MarkCompactCollector::TearDown() { AbortCompaction(); }
+void MarkCompactCollector::TearDown() {
+  AbortCompaction();
+  delete marking_deque_memory_;
+}
 
 
 void MarkCompactCollector::AddEvacuationCandidate(Page* p) {
@@ -304,6 +309,8 @@ void MarkCompactCollector::CollectGarbage() {
 
   heap_->set_encountered_weak_cells(Smi::FromInt(0));
 
+  isolate()->global_handles()->CollectPhantomCallbackData();
+
 #ifdef VERIFY_HEAP
   if (FLAG_verify_heap) {
     VerifyMarking(heap_);
@@ -378,7 +385,7 @@ void MarkCompactCollector::VerifyWeakEmbeddedObjectsInCode() {
   for (HeapObject* obj = code_iterator.Next(); obj != NULL;
        obj = code_iterator.Next()) {
     Code* code = Code::cast(obj);
-    if (!code->is_optimized_code() && !code->is_weak_stub()) continue;
+    if (!code->is_optimized_code()) continue;
     if (WillBeDeoptimized(code)) continue;
     code->VerifyEmbeddedObjectsDependency();
   }
@@ -441,7 +448,7 @@ class MarkCompactCollector::SweeperTask : public v8::Task {
 
  private:
   // v8::Task overrides.
-  virtual void Run() OVERRIDE {
+  void Run() OVERRIDE {
     heap_->mark_compact_collector()->SweepInParallel(space_, 0);
     heap_->mark_compact_collector()->pending_sweeper_jobs_semaphore_.Signal();
   }
@@ -470,12 +477,12 @@ void MarkCompactCollector::EnsureSweepingCompleted() {
 
   // If sweeping is not completed or not running at all, we try to complete it
   // here.
-  if (FLAG_predictable || !IsSweepingCompleted()) {
+  if (!FLAG_concurrent_sweeping || !IsSweepingCompleted()) {
     SweepInParallel(heap()->paged_space(OLD_DATA_SPACE), 0);
     SweepInParallel(heap()->paged_space(OLD_POINTER_SPACE), 0);
   }
   // Wait twice for both jobs.
-  if (!FLAG_predictable) {
+  if (FLAG_concurrent_sweeping) {
     pending_sweeper_jobs_semaphore_.Wait();
     pending_sweeper_jobs_semaphore_.Wait();
   }
@@ -487,7 +494,7 @@ void MarkCompactCollector::EnsureSweepingCompleted() {
   heap()->paged_space(OLD_POINTER_SPACE)->ResetUnsweptFreeBytes();
 
 #ifdef VERIFY_HEAP
-  if (FLAG_verify_heap) {
+  if (FLAG_verify_heap && !evacuation()) {
     VerifyEvacuation(heap_);
   }
 #endif
@@ -1206,7 +1213,6 @@ static inline HeapObject* ShortCircuitConsString(Object** p) {
   // except the maps for the object and its possible substrings might be
   // marked.
   HeapObject* object = HeapObject::cast(*p);
-  if (!FLAG_clever_optimizations) return object;
   Map* map = object->map();
   InstanceType type = map->instance_type();
   if (!IsShortcutCandidate(type)) return object;
@@ -1945,11 +1951,6 @@ void MarkCompactCollector::MarkAllocationSite(AllocationSite* site) {
 }
 
 
-bool MarkCompactCollector::IsMarkingDequeEmpty() {
-  return marking_deque_.IsEmpty();
-}
-
-
 void MarkCompactCollector::MarkRoots(RootMarkingVisitor* visitor) {
   // Mark the heap roots including global variables, stack variables,
   // etc., and all objects reachable from them.
@@ -2015,13 +2016,18 @@ void MarkCompactCollector::MarkWeakObjectToCodeTable() {
 // After: the marking stack is empty, and all objects reachable from the
 // marking stack have been marked, or are overflowed in the heap.
 void MarkCompactCollector::EmptyMarkingDeque() {
+  Map* filler_map = heap_->one_pointer_filler_map();
   while (!marking_deque_.IsEmpty()) {
     HeapObject* object = marking_deque_.Pop();
+    // Explicitly skip one word fillers. Incremental markbit patterns are
+    // correct only for objects that occupy at least two words.
+    Map* map = object->map();
+    if (map == filler_map) continue;
+
     DCHECK(object->IsHeapObject());
     DCHECK(heap()->Contains(object));
-    DCHECK(Marking::IsBlack(Marking::MarkBitFrom(object)));
+    DCHECK(!Marking::IsWhite(Marking::MarkBitFrom(object)));
 
-    Map* map = object->map();
     MarkBit map_mark = Marking::MarkBitFrom(map);
     MarkObject(map, map_mark);
 
@@ -2084,13 +2090,16 @@ void MarkCompactCollector::ProcessMarkingDeque() {
 
 // Mark all objects reachable (transitively) from objects on the marking
 // stack including references only considered in the atomic marking pause.
-void MarkCompactCollector::ProcessEphemeralMarking(ObjectVisitor* visitor) {
+void MarkCompactCollector::ProcessEphemeralMarking(
+    ObjectVisitor* visitor, bool only_process_harmony_weak_collections) {
   bool work_to_do = true;
-  DCHECK(marking_deque_.IsEmpty());
+  DCHECK(marking_deque_.IsEmpty() && !marking_deque_.overflowed());
   while (work_to_do) {
-    isolate()->global_handles()->IterateObjectGroups(
-        visitor, &IsUnmarkedHeapObjectWithHeap);
-    MarkImplicitRefGroups();
+    if (!only_process_harmony_weak_collections) {
+      isolate()->global_handles()->IterateObjectGroups(
+          visitor, &IsUnmarkedHeapObjectWithHeap);
+      MarkImplicitRefGroups();
+    }
     ProcessWeakCollections();
     work_to_do = !marking_deque_.IsEmpty();
     ProcessMarkingDeque();
@@ -2116,6 +2125,43 @@ void MarkCompactCollector::ProcessTopOptimizedFrame(ObjectVisitor* visitor) {
 }
 
 
+void MarkCompactCollector::EnsureMarkingDequeIsCommittedAndInitialize() {
+  if (marking_deque_memory_ == NULL) {
+    marking_deque_memory_ = new base::VirtualMemory(4 * MB);
+  }
+  if (!marking_deque_memory_committed_) {
+    bool success = marking_deque_memory_->Commit(
+        reinterpret_cast<Address>(marking_deque_memory_->address()),
+        marking_deque_memory_->size(),
+        false);  // Not executable.
+    CHECK(success);
+    marking_deque_memory_committed_ = true;
+    InitializeMarkingDeque();
+  }
+}
+
+
+void MarkCompactCollector::InitializeMarkingDeque() {
+  if (marking_deque_memory_committed_) {
+    Address addr = static_cast<Address>(marking_deque_memory_->address());
+    size_t size = marking_deque_memory_->size();
+    if (FLAG_force_marking_deque_overflows) size = 64 * kPointerSize;
+    marking_deque_.Initialize(addr, addr + size);
+  }
+}
+
+
+void MarkCompactCollector::UncommitMarkingDeque() {
+  if (marking_deque_memory_committed_) {
+    bool success = marking_deque_memory_->Uncommit(
+        reinterpret_cast<Address>(marking_deque_memory_->address()),
+        marking_deque_memory_->size());
+    CHECK(success);
+    marking_deque_memory_committed_ = false;
+  }
+}
+
+
 void MarkCompactCollector::MarkLiveObjects() {
   GCTracer::Scope gc_scope(heap()->tracer(), GCTracer::Scope::MC_MARK);
   double start_time = 0.0;
@@ -2127,42 +2173,21 @@ void MarkCompactCollector::MarkLiveObjects() {
   // with the C stack limit check.
   PostponeInterruptsScope postpone(isolate());
 
-  bool incremental_marking_overflowed = false;
   IncrementalMarking* incremental_marking = heap_->incremental_marking();
   if (was_marked_incrementally_) {
-    // Finalize the incremental marking and check whether we had an overflow.
-    // Both markers use grey color to mark overflowed objects so
-    // non-incremental marker can deal with them as if overflow
-    // occured during normal marking.
-    // But incremental marker uses a separate marking deque
-    // so we have to explicitly copy its overflow state.
     incremental_marking->Finalize();
-    incremental_marking_overflowed =
-        incremental_marking->marking_deque()->overflowed();
-    incremental_marking->marking_deque()->ClearOverflowed();
   } else {
     // Abort any pending incremental activities e.g. incremental sweeping.
     incremental_marking->Abort();
+    InitializeMarkingDeque();
   }
 
 #ifdef DEBUG
   DCHECK(state_ == PREPARE_GC);
   state_ = MARK_LIVE_OBJECTS;
 #endif
-  // The to space contains live objects, a page in from space is used as a
-  // marking stack.
-  Address marking_deque_start = heap()->new_space()->FromSpacePageLow();
-  Address marking_deque_end = heap()->new_space()->FromSpacePageHigh();
-  if (FLAG_force_marking_deque_overflows) {
-    marking_deque_end = marking_deque_start + 64 * kPointerSize;
-  }
-  marking_deque_.Initialize(marking_deque_start, marking_deque_end);
-  DCHECK(!marking_deque_.overflowed());
 
-  if (incremental_marking_overflowed) {
-    // There are overflowed objects left in the heap after incremental marking.
-    marking_deque_.SetOverflowed();
-  }
+  EnsureMarkingDequeIsCommittedAndInitialize();
 
   PrepareForCodeFlushing();
 
@@ -2199,30 +2224,35 @@ void MarkCompactCollector::MarkLiveObjects() {
 
   ProcessTopOptimizedFrame(&root_visitor);
 
-  // The objects reachable from the roots are marked, yet unreachable
-  // objects are unmarked.  Mark objects reachable due to host
-  // application specific logic or through Harmony weak maps.
-  ProcessEphemeralMarking(&root_visitor);
+  {
+    GCTracer::Scope gc_scope(heap()->tracer(), GCTracer::Scope::MC_WEAKCLOSURE);
+
+    // The objects reachable from the roots are marked, yet unreachable
+    // objects are unmarked.  Mark objects reachable due to host
+    // application specific logic or through Harmony weak maps.
+    ProcessEphemeralMarking(&root_visitor, false);
+
+    // The objects reachable from the roots, weak maps or object groups
+    // are marked. Objects pointed to only by weak global handles cannot be
+    // immediately reclaimed. Instead, we have to mark them as pending and mark
+    // objects reachable from them.
+    //
+    // First we identify nonlive weak handles and mark them as pending
+    // destruction.
+    heap()->isolate()->global_handles()->IdentifyWeakHandles(
+        &IsUnmarkedHeapObject);
+    // Then we mark the objects.
+    heap()->isolate()->global_handles()->IterateWeakRoots(&root_visitor);
+    ProcessMarkingDeque();
 
-  // The objects reachable from the roots, weak maps or object groups
-  // are marked, yet unreachable objects are unmarked.  Mark objects
-  // reachable only from weak global handles.
-  //
-  // First we identify nonlive weak handles and mark them as pending
-  // destruction.
-  heap()->isolate()->global_handles()->IdentifyWeakHandles(
-      &IsUnmarkedHeapObject);
-  // Then we mark the objects and process the transitive closure.
-  heap()->isolate()->global_handles()->IterateWeakRoots(&root_visitor);
-  while (marking_deque_.overflowed()) {
-    RefillMarkingDeque();
-    EmptyMarkingDeque();
+    // Repeat Harmony weak maps marking to mark unmarked objects reachable from
+    // the weak roots we just marked as pending destruction.
+    //
+    // We only process harmony collections, as all object groups have been fully
+    // processed and no weakly reachable node can discover new objects groups.
+    ProcessEphemeralMarking(&root_visitor, true);
   }
 
-  // Repeat host application specific and Harmony weak maps marking to
-  // mark unmarked objects reachable from the weak roots.
-  ProcessEphemeralMarking(&root_visitor);
-
   AfterMarking();
 
   if (FLAG_print_cumulative_gc_stat) {
@@ -2232,12 +2262,6 @@ void MarkCompactCollector::MarkLiveObjects() {
 
 
 void MarkCompactCollector::AfterMarking() {
-  // Object literal map caches reference strings (cache keys) and maps
-  // (cache values). At this point still useful maps have already been
-  // marked. Mark the keys for the alive values before we process the
-  // string table.
-  ProcessMapCaches();
-
   // Prune the string table removing all strings only pointed to by the
   // string table.  Cannot use string_table() here because the string
   // table is marked.
@@ -2274,57 +2298,6 @@ void MarkCompactCollector::AfterMarking() {
 }
 
 
-void MarkCompactCollector::ProcessMapCaches() {
-  Object* raw_context = heap()->native_contexts_list();
-  while (raw_context != heap()->undefined_value()) {
-    Context* context = reinterpret_cast<Context*>(raw_context);
-    if (IsMarked(context)) {
-      HeapObject* raw_map_cache =
-          HeapObject::cast(context->get(Context::MAP_CACHE_INDEX));
-      // A map cache may be reachable from the stack. In this case
-      // it's already transitively marked and it's too late to clean
-      // up its parts.
-      if (!IsMarked(raw_map_cache) &&
-          raw_map_cache != heap()->undefined_value()) {
-        MapCache* map_cache = reinterpret_cast<MapCache*>(raw_map_cache);
-        int existing_elements = map_cache->NumberOfElements();
-        int used_elements = 0;
-        for (int i = MapCache::kElementsStartIndex; i < map_cache->length();
-             i += MapCache::kEntrySize) {
-          Object* raw_key = map_cache->get(i);
-          if (raw_key == heap()->undefined_value() ||
-              raw_key == heap()->the_hole_value())
-            continue;
-          STATIC_ASSERT(MapCache::kEntrySize == 2);
-          Object* raw_map = map_cache->get(i + 1);
-          if (raw_map->IsHeapObject() && IsMarked(raw_map)) {
-            ++used_elements;
-          } else {
-            // Delete useless entries with unmarked maps.
-            DCHECK(raw_map->IsMap());
-            map_cache->set_the_hole(i);
-            map_cache->set_the_hole(i + 1);
-          }
-        }
-        if (used_elements == 0) {
-          context->set(Context::MAP_CACHE_INDEX, heap()->undefined_value());
-        } else {
-          // Note: we don't actually shrink the cache here to avoid
-          // extra complexity during GC. We rely on subsequent cache
-          // usages (EnsureCapacity) to do this.
-          map_cache->ElementsRemoved(existing_elements - used_elements);
-          MarkBit map_cache_markbit = Marking::MarkBitFrom(map_cache);
-          MarkObject(map_cache, map_cache_markbit);
-        }
-      }
-    }
-    // Move to next element in the list.
-    raw_context = context->get(Context::NEXT_CONTEXT_LINK);
-  }
-  ProcessMarkingDeque();
-}
-
-
 void MarkCompactCollector::ClearNonLiveReferences() {
   // Iterate over the map space, setting map transitions that go from
   // a marked map to an unmarked map to null transitions.  This action
@@ -2572,34 +2545,12 @@ void MarkCompactCollector::TrimEnumCache(Map* map,
 }
 
 
-void MarkCompactCollector::ClearDependentICList(Object* head) {
-  Object* current = head;
-  Object* undefined = heap()->undefined_value();
-  while (current != undefined) {
-    Code* code = Code::cast(current);
-    if (IsMarked(code)) {
-      DCHECK(code->is_weak_stub());
-      IC::InvalidateMaps(code);
-    }
-    current = code->next_code_link();
-    code->set_next_code_link(undefined);
-  }
-}
-
-
 void MarkCompactCollector::ClearDependentCode(DependentCode* entries) {
   DisallowHeapAllocation no_allocation;
   DependentCode::GroupStartIndexes starts(entries);
   int number_of_entries = starts.number_of_entries();
   if (number_of_entries == 0) return;
-  int g = DependentCode::kWeakICGroup;
-  if (starts.at(g) != starts.at(g + 1)) {
-    int i = starts.at(g);
-    DCHECK(i + 1 == starts.at(g + 1));
-    Object* head = entries->object_at(i);
-    ClearDependentICList(head);
-  }
-  g = DependentCode::kWeakCodeGroup;
+  int g = DependentCode::kWeakCodeGroup;
   for (int i = starts.at(g); i < starts.at(g + 1); i++) {
     // If the entry is compilation info then the map must be alive,
     // and ClearDependentCode shouldn't be called.
@@ -2621,34 +2572,17 @@ void MarkCompactCollector::ClearDependentCode(DependentCode* entries) {
 int MarkCompactCollector::ClearNonLiveDependentCodeInGroup(
     DependentCode* entries, int group, int start, int end, int new_start) {
   int survived = 0;
-  if (group == DependentCode::kWeakICGroup) {
-    // Dependent weak IC stubs form a linked list and only the head is stored
-    // in the dependent code array.
-    if (start != end) {
-      DCHECK(start + 1 == end);
-      Object* old_head = entries->object_at(start);
-      MarkCompactWeakObjectRetainer retainer;
-      Object* head = VisitWeakList<Code>(heap(), old_head, &retainer);
-      entries->set_object_at(new_start, head);
-      Object** slot = entries->slot_at(new_start);
-      RecordSlot(slot, slot, head);
-      // We do not compact this group even if the head is undefined,
-      // more dependent ICs are likely to be added later.
-      survived = 1;
-    }
-  } else {
-    for (int i = start; i < end; i++) {
-      Object* obj = entries->object_at(i);
-      DCHECK(obj->IsCode() || IsMarked(obj));
-      if (IsMarked(obj) &&
-          (!obj->IsCode() || !WillBeDeoptimized(Code::cast(obj)))) {
-        if (new_start + survived != i) {
-          entries->set_object_at(new_start + survived, obj);
-        }
-        Object** slot = entries->slot_at(new_start + survived);
-        RecordSlot(slot, slot, obj);
-        survived++;
+  for (int i = start; i < end; i++) {
+    Object* obj = entries->object_at(i);
+    DCHECK(obj->IsCode() || IsMarked(obj));
+    if (IsMarked(obj) &&
+        (!obj->IsCode() || !WillBeDeoptimized(Code::cast(obj)))) {
+      if (new_start + survived != i) {
+        entries->set_object_at(new_start + survived, obj);
       }
+      Object** slot = entries->slot_at(new_start + survived);
+      RecordSlot(slot, slot, obj);
+      survived++;
     }
   }
   entries->set_number_of_entries(
@@ -2810,12 +2744,24 @@ void MarkCompactCollector::MigrateObject(HeapObject* dst, HeapObject* src,
     Address dst_slot = dst_addr;
     DCHECK(IsAligned(size, kPointerSize));
 
+    bool may_contain_raw_values = src->MayContainRawValues();
+#if V8_DOUBLE_FIELDS_UNBOXING
+    LayoutDescriptorHelper helper(src->map());
+    bool has_only_tagged_fields = helper.all_fields_tagged();
+#endif
     for (int remaining = size / kPointerSize; remaining > 0; remaining--) {
       Object* value = Memory::Object_at(src_slot);
 
       Memory::Object_at(dst_slot) = value;
 
-      if (!src->MayContainRawValues()) {
+#if V8_DOUBLE_FIELDS_UNBOXING
+      if (!may_contain_raw_values &&
+          (has_only_tagged_fields ||
+           helper.IsTagged(static_cast<int>(src_slot - src_addr))))
+#else
+      if (!may_contain_raw_values)
+#endif
+      {
         RecordMigratedSlot(value, dst_slot);
       }
 
@@ -2928,7 +2874,8 @@ class PointersUpdatingVisitor : public ObjectVisitor {
   }
 
   static inline void UpdateSlot(Heap* heap, Object** slot) {
-    Object* obj = *slot;
+    Object* obj = reinterpret_cast<Object*>(
+        base::NoBarrier_Load(reinterpret_cast<base::AtomicWord*>(slot)));
 
     if (!obj->IsHeapObject()) return;
 
@@ -2939,7 +2886,10 @@ class PointersUpdatingVisitor : public ObjectVisitor {
       DCHECK(heap->InFromSpace(heap_obj) ||
              MarkCompactCollector::IsOnEvacuationCandidate(heap_obj));
       HeapObject* target = map_word.ToForwardingAddress();
-      *slot = target;
+      base::NoBarrier_CompareAndSwap(
+          reinterpret_cast<base::AtomicWord*>(slot),
+          reinterpret_cast<base::AtomicWord>(obj),
+          reinterpret_cast<base::AtomicWord>(target));
       DCHECK(!heap->InFromSpace(target) &&
              !MarkCompactCollector::IsOnEvacuationCandidate(target));
     }
@@ -3256,7 +3206,7 @@ static int Sweep(PagedSpace* space, FreeList* free_list, Page* p,
       }
       HeapObject* live_object = HeapObject::FromAddress(free_end);
       DCHECK(Marking::IsBlack(Marking::MarkBitFrom(live_object)));
-      Map* map = live_object->map();
+      Map* map = live_object->synchronized_map();
       int size = live_object->SizeFromMap(map);
       if (sweeping_mode == SWEEP_AND_VISIT_LIVE_OBJECTS) {
         live_object->IterateBody(map->instance_type(), size, v);
@@ -3436,6 +3386,7 @@ void MarkCompactCollector::EvacuateNewSpaceAndCandidates() {
   {
     GCTracer::Scope gc_scope(heap()->tracer(),
                              GCTracer::Scope::MC_EVACUATE_PAGES);
+    EvacuationScope evacuation_scope(this);
     EvacuatePages();
   }
 
@@ -4182,12 +4133,11 @@ void MarkCompactCollector::SweepSpaces() {
     GCTracer::Scope sweep_scope(heap()->tracer(),
                                 GCTracer::Scope::MC_SWEEP_OLDSPACE);
     {
-      SequentialSweepingScope scope(this);
       SweepSpace(heap()->old_pointer_space(), CONCURRENT_SWEEPING);
       SweepSpace(heap()->old_data_space(), CONCURRENT_SWEEPING);
     }
     sweeping_in_progress_ = true;
-    if (!FLAG_predictable) {
+    if (FLAG_concurrent_sweeping) {
       StartSweeperThreads();
     }
   }
@@ -4222,6 +4172,10 @@ void MarkCompactCollector::SweepSpaces() {
 
   // Deallocate evacuated candidate pages.
   ReleaseEvacuationCandidates();
+  CodeRange* code_range = heap()->isolate()->code_range();
+  if (code_range != NULL && code_range->valid()) {
+    code_range->ReserveEmergencyBlock();
+  }
 
   if (FLAG_print_cumulative_gc_stat) {
     heap_->tracer()->AddSweepingTime(base::OS::TimeCurrentMillis() -