Ensure that promotion queue does not overlap with objects relocated to ToSpace.

R=erik.corry@gmail.com

Review URL: http://codereview.chromium.org/8477030

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9932 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/heap-inl.h

@@ -40,12 +40,30 @@ namespace v8 {
 namespace internal {
 
 void PromotionQueue::insert(HeapObject* target, int size) {
+  if (emergency_stack_ != NULL) {
+    emergency_stack_->Add(Entry(target, size));
+    return;
+  }
+
   if (NewSpacePage::IsAtStart(reinterpret_cast<Address>(rear_))) {
     NewSpacePage* rear_page =
         NewSpacePage::FromAddress(reinterpret_cast<Address>(rear_));
     ASSERT(!rear_page->prev_page()->is_anchor());
     rear_ = reinterpret_cast<intptr_t*>(rear_page->prev_page()->body_limit());
+    ActivateGuardIfOnTheSamePage();
   }
+
+  if (guard_) {
+    ASSERT(GetHeadPage() ==
+           Page::FromAllocationTop(reinterpret_cast<Address>(limit_)));
+
+    if ((rear_ - 2) < limit_) {
+      RelocateQueueHead();
+      emergency_stack_->Add(Entry(target, size));
+      return;
+    }
+  }
+
   *(--rear_) = reinterpret_cast<intptr_t>(target);
   *(--rear_) = size;
   // Assert no overflow into live objects.
@@ -56,6 +74,13 @@ void PromotionQueue::insert(HeapObject* target, int size) {
 }
 
 
+void PromotionQueue::ActivateGuardIfOnTheSamePage() {
+  guard_ = guard_ ||
+      heap_->new_space()->active_space()->current_page()->address() ==
+      GetHeadPage()->address();
+}
+
+
 int Heap::MaxObjectSizeInPagedSpace() {
   return Page::kMaxHeapObjectSize;
 }

src/heap.cc

@@ -143,6 +143,7 @@ Heap::Heap()
       number_idle_notifications_(0),
       last_idle_notification_gc_count_(0),
       last_idle_notification_gc_count_init_(false),
+      promotion_queue_(this),
       configured_(false),
       chunks_queued_for_free_(NULL) {
   // Allow build-time customization of the max semispace size. Building
@@ -988,6 +989,41 @@ void StoreBufferRebuilder::Callback(MemoryChunk* page, StoreBufferEvent event) {
 }
 
 
+void PromotionQueue::Initialize() {
+  // Assumes that a NewSpacePage exactly fits a number of promotion queue
+  // entries (where each is a pair of intptr_t). This allows us to simplify
+  // the test fpr when to switch pages.
+  ASSERT((Page::kPageSize - MemoryChunk::kBodyOffset) % (2 * kPointerSize)
+         == 0);
+  limit_ = reinterpret_cast<intptr_t*>(heap_->new_space()->ToSpaceStart());
+  front_ = rear_ =
+      reinterpret_cast<intptr_t*>(heap_->new_space()->ToSpaceEnd());
+  emergency_stack_ = NULL;
+  guard_ = false;
+}
+
+
+void PromotionQueue::RelocateQueueHead() {
+  ASSERT(emergency_stack_ == NULL);
+
+  Page* p = Page::FromAllocationTop(reinterpret_cast<Address>(rear_));
+  intptr_t* head_start = rear_;
+  intptr_t* head_end =
+      Min(front_, reinterpret_cast<intptr_t*>(p->body_limit()));
+
+  int entries_count = (head_end - head_start) / kEntrySizeInWords;
+
+  emergency_stack_ = new List<Entry>(2 * entries_count);
+
+  while (head_start != head_end) {
+    int size = *(head_start++);
+    HeapObject* obj = reinterpret_cast<HeapObject*>(*(head_start++));
+    emergency_stack_->Add(Entry(obj, size));
+  }
+  rear_ = head_end;
+}
+
+
 void Heap::Scavenge() {
 #ifdef DEBUG
   if (FLAG_verify_heap) VerifyNonPointerSpacePointers();
@@ -1036,7 +1072,7 @@ void Heap::Scavenge() {
   // frees up its size in bytes from the top of the new space, and
   // objects are at least one pointer in size.
   Address new_space_front = new_space_.ToSpaceStart();
-  promotion_queue_.Initialize(new_space_.ToSpaceEnd());
+  promotion_queue_.Initialize();
 
 #ifdef DEBUG
   store_buffer()->Clean();
@@ -1076,10 +1112,11 @@ void Heap::Scavenge() {
       &scavenge_visitor);
   new_space_front = DoScavenge(&scavenge_visitor, new_space_front);
 
-
   UpdateNewSpaceReferencesInExternalStringTable(
       &UpdateNewSpaceReferenceInExternalStringTableEntry);
 
+  promotion_queue_.Destroy();
+
   LiveObjectList::UpdateReferencesForScavengeGC();
   isolate()->runtime_profiler()->UpdateSamplesAfterScavenge();
   incremental_marking()->UpdateMarkingDequeAfterScavenge();
@@ -1486,6 +1523,7 @@ class ScavengingVisitor : public StaticVisitorBase {
       }
     }
     MaybeObject* allocation = heap->new_space()->AllocateRaw(object_size);
+    heap->promotion_queue()->SetNewLimit(heap->new_space()->top());
     Object* result = allocation->ToObjectUnchecked();
 
     *slot = MigrateObject(heap, object, HeapObject::cast(result), object_size);

src/heap.h

@@ -282,24 +282,58 @@ class HeapDebugUtils;
 // by it's size to avoid dereferencing a map pointer for scanning.
 class PromotionQueue {
  public:
-  PromotionQueue() : front_(NULL), rear_(NULL) { }
+  PromotionQueue(Heap* heap)
+      : front_(NULL),
+        rear_(NULL),
+        limit_(NULL),
+        emergency_stack_(0),
+        heap_(heap) { }
 
-  void Initialize(Address start_address) {
-    // Assumes that a NewSpacePage exactly fits a number of promotion queue
-    // entries (where each is a pair of intptr_t). This allows us to simplify
-    // the test fpr when to switch pages.
-    ASSERT((Page::kPageSize - MemoryChunk::kBodyOffset) % (2 * kPointerSize)
-           == 0);
-    ASSERT(NewSpacePage::IsAtEnd(start_address));
-    front_ = rear_ = reinterpret_cast<intptr_t*>(start_address);
+  void Initialize();
+
+  void Destroy() {
+    ASSERT(is_empty());
+    delete emergency_stack_;
+    emergency_stack_ = NULL;
   }
 
-  bool is_empty() { return front_ == rear_; }
+  inline void ActivateGuardIfOnTheSamePage();
+
+  Page* GetHeadPage() {
+    return Page::FromAllocationTop(reinterpret_cast<Address>(rear_));
+  }
+
+  void SetNewLimit(Address limit) {
+    if (!guard_) {
+      return;
+    }
+
+    ASSERT(GetHeadPage() == Page::FromAllocationTop(limit));
+    limit_ = reinterpret_cast<intptr_t*>(limit);
+
+    if (limit_ <= rear_) {
+      return;
+    }
+
+    RelocateQueueHead();
+  }
+
+  bool is_empty() {
+    return (front_ == rear_) &&
+        (emergency_stack_ == NULL || emergency_stack_->length() == 0);
+  }
 
   inline void insert(HeapObject* target, int size);
 
   void remove(HeapObject** target, int* size) {
     ASSERT(!is_empty());
+    if (front_ == rear_) {
+      Entry e = emergency_stack_->RemoveLast();
+      *target = e.obj_;
+      *size = e.size_;
+      return;
+    }
+
     if (NewSpacePage::IsAtStart(reinterpret_cast<Address>(front_))) {
       NewSpacePage* front_page =
           NewSpacePage::FromAddress(reinterpret_cast<Address>(front_));
@@ -318,6 +352,23 @@ class PromotionQueue {
   // The front of the queue is higher in the memory page chain than the rear.
   intptr_t* front_;
   intptr_t* rear_;
+  intptr_t* limit_;
+
+  bool guard_;
+
+  static const int kEntrySizeInWords = 2;
+
+  struct Entry {
+    Entry(HeapObject* obj, int size) : obj_(obj), size_(size) { }
+
+    HeapObject* obj_;
+    int size_;
+  };
+  List<Entry>* emergency_stack_;
+
+  Heap* heap_;
+
+  void RelocateQueueHead();
 
   DISALLOW_COPY_AND_ASSIGN(PromotionQueue);
 };

src/spaces-inl.h

@@ -293,30 +293,12 @@ MaybeObject* PagedSpace::AllocateRaw(int size_in_bytes) {
 
 // -----------------------------------------------------------------------------
 // NewSpace
-MaybeObject* NewSpace::AllocateRawInternal(int size_in_bytes) {
+
+
+MaybeObject* NewSpace::AllocateRaw(int size_in_bytes) {
   Address old_top = allocation_info_.top;
   if (allocation_info_.limit - old_top < size_in_bytes) {
-    Address new_top = old_top + size_in_bytes;
-    Address high = to_space_.page_high();
-    if (allocation_info_.limit < high) {
-      // Incremental marking has lowered the limit to get a
-      // chance to do a step.
-      allocation_info_.limit = Min(
-          allocation_info_.limit + inline_allocation_limit_step_,
-          high);
-      int bytes_allocated = static_cast<int>(new_top - top_on_previous_step_);
-      heap()->incremental_marking()->Step(bytes_allocated);
-      top_on_previous_step_ = new_top;
-      return AllocateRawInternal(size_in_bytes);
-    } else if (AddFreshPage()) {
-      // Switched to new page. Try allocating again.
-      int bytes_allocated = static_cast<int>(old_top - top_on_previous_step_);
-      heap()->incremental_marking()->Step(bytes_allocated);
-      top_on_previous_step_ = to_space_.page_low();
-      return AllocateRawInternal(size_in_bytes);
-    } else {
-      return Failure::RetryAfterGC();
-    }
+    return SlowAllocateRaw(size_in_bytes);
   }
 
   Object* obj = HeapObject::FromAddress(allocation_info_.top);

src/spaces.cc

@@ -1012,16 +1012,49 @@ bool NewSpace::AddFreshPage() {
     // Failed to get a new page in to-space.
     return false;
   }
+
   // Clear remainder of current page.
-  int remaining_in_page =
-    static_cast<int>(NewSpacePage::FromLimit(top)->body_limit() - top);
+  Address limit = NewSpacePage::FromLimit(top)->body_limit();
+  if (heap()->gc_state() == Heap::SCAVENGE) {
+    heap()->promotion_queue()->SetNewLimit(limit);
+    heap()->promotion_queue()->ActivateGuardIfOnTheSamePage();
+  }
+
+  int remaining_in_page = static_cast<int>(limit - top);
   heap()->CreateFillerObjectAt(top, remaining_in_page);
   pages_used_++;
   UpdateAllocationInfo();
+
   return true;
 }
 
 
+MaybeObject* NewSpace::SlowAllocateRaw(int size_in_bytes) {
+  Address old_top = allocation_info_.top;
+  Address new_top = old_top + size_in_bytes;
+  Address high = to_space_.page_high();
+  if (allocation_info_.limit < high) {
+    // Incremental marking has lowered the limit to get a
+    // chance to do a step.
+    allocation_info_.limit = Min(
+        allocation_info_.limit + inline_allocation_limit_step_,
+        high);
+    int bytes_allocated = static_cast<int>(new_top - top_on_previous_step_);
+    heap()->incremental_marking()->Step(bytes_allocated);
+    top_on_previous_step_ = new_top;
+    return AllocateRaw(size_in_bytes);
+  } else if (AddFreshPage()) {
+    // Switched to new page. Try allocating again.
+    int bytes_allocated = static_cast<int>(old_top - top_on_previous_step_);
+    heap()->incremental_marking()->Step(bytes_allocated);
+    top_on_previous_step_ = to_space_.page_low();
+    return AllocateRaw(size_in_bytes);
+  } else {
+    return Failure::RetryAfterGC();
+  }
+}
+
+
 #ifdef DEBUG
 // We do not use the SemiSpaceIterator because verification doesn't assume
 // that it works (it depends on the invariants we are checking).
@@ -1904,7 +1937,7 @@ bool NewSpace::ReserveSpace(int bytes) {
   // marking.  The most reliable way to ensure that there is linear space is
   // to do the allocation, then rewind the limit.
   ASSERT(bytes <= InitialCapacity());
-  MaybeObject* maybe = AllocateRawInternal(bytes);
+  MaybeObject* maybe = AllocateRaw(bytes);
   Object* object = NULL;
   if (!maybe->ToObject(&object)) return false;
   HeapObject* allocation = HeapObject::cast(object);

src/spaces.h

@@ -2140,9 +2140,7 @@ class NewSpace : public Space {
   Address* allocation_top_address() { return &allocation_info_.top; }
   Address* allocation_limit_address() { return &allocation_info_.limit; }
 
-  MUST_USE_RESULT MaybeObject* AllocateRaw(int size_in_bytes) {
-    return AllocateRawInternal(size_in_bytes);
-  }
+  MUST_USE_RESULT INLINE(MaybeObject* AllocateRaw(int size_in_bytes));
 
   // Reset the allocation pointer to the beginning of the active semispace.
   void ResetAllocationInfo();
@@ -2268,8 +2266,7 @@ class NewSpace : public Space {
   HistogramInfo* allocated_histogram_;
   HistogramInfo* promoted_histogram_;
 
-  // Implementation of AllocateRaw.
-  MUST_USE_RESULT inline MaybeObject* AllocateRawInternal(int size_in_bytes);
+  MUST_USE_RESULT MaybeObject* SlowAllocateRaw(int size_in_bytes);
 
   friend class SemiSpaceIterator;