[heap] Black allocation.

src/heap/heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/heap/heap.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/ast/scopeinfo.h"
 #include "src/base/bits.h"
@@ skipping 1925 matching lines @@
         HeapObject* target;
         int size;
         promotion_queue()->remove(&target, &size);
 
         // Promoted object might be already partially visited
         // during old space pointer iteration. Thus we search specifically
         // for pointers to from semispace instead of looking for pointers
         // to new space.
         DCHECK(!target->IsMap());
 
-        IteratePointersToFromSpace(target, size, &Scavenger::ScavengeObject);
+        IteratePromotedObject(target, size, &Scavenger::ScavengeObject);
       }
     }
 
     // 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;
 }
 
@@ skipping 562 matching lines @@
   DCHECK(capacity > 0);
   HeapObject* raw_array = nullptr;
   {
     AllocationResult allocation = AllocateRawFixedArray(capacity, TENURED);
     if (!allocation.To(&raw_array)) return allocation;
   }
   raw_array->set_map_no_write_barrier(transition_array_map());
   TransitionArray* array = TransitionArray::cast(raw_array);
   array->set_length(capacity);
   MemsetPointer(array->data_start(), undefined_value(), capacity);
+  // Transition arrays are tenured. When black allocation is on we have to
+  // add the transition array to the list of encountered_transition_arrays.
+  if (incremental_marking()->black_allocation()) {
+    array->set_next_link(encountered_transition_arrays(),
+                         UPDATE_WEAK_WRITE_BARRIER);
+    set_encountered_transition_arrays(array);
+  } else {
+    array->set_next_link(undefined_value(), SKIP_WRITE_BARRIER);
+  }
   return array;
 }
 
 
 void Heap::CreateApiObjects() {
   HandleScope scope(isolate());
   Factory* factory = isolate()->factory();
   Handle<Map> new_neander_map =
       factory->NewMap(JS_OBJECT_TYPE, JSObject::kHeaderSize);
 
@@ skipping 743 matching lines @@
   return elements;
 }
 
 
 AllocationResult Heap::AllocateCode(int object_size, bool immovable) {
   DCHECK(IsAligned(static_cast<intptr_t>(object_size), kCodeAlignment));
   AllocationResult allocation = AllocateRaw(object_size, CODE_SPACE);
 
   HeapObject* result = nullptr;
   if (!allocation.To(&result)) return allocation;
-
   if (immovable) {
     Address address = result->address();
     // Code objects which should stay at a fixed address are allocated either
     // in the first page of code space (objects on the first page of each space
     // are never moved) or in large object space.
     if (!code_space_->FirstPage()->Contains(address) &&
         MemoryChunk::FromAddress(address)->owner()->identity() != LO_SPACE) {
       // Discard the first code allocation, which was on a page where it could
       // be moved.
       CreateFillerObjectAt(result->address(), object_size);
@@ skipping 29 matching lines @@
   Address new_addr = result->address();
   CopyBlock(new_addr, old_addr, obj_size);
   Code* new_code = Code::cast(result);
 
   // Relocate the copy.
   DCHECK(IsAligned(bit_cast<intptr_t>(new_code->address()), kCodeAlignment));
   DCHECK(isolate_->code_range() == NULL || !isolate_->code_range()->valid() ||
          isolate_->code_range()->contains(code->address()) ||
          obj_size <= code_space()->AreaSize());
   new_code->Relocate(new_addr - old_addr);
+  // We have to iterate over the object and process its pointers when black
+  // allocation is on.
+  incremental_marking()->IterateBlackObject(new_code);
   return new_code;
 }
 
 
 AllocationResult Heap::CopyCode(Code* code, Vector<byte> reloc_info) {
   // Allocate ByteArray before the Code object, so that we do not risk
   // leaving uninitialized Code object (and breaking the heap).
   ByteArray* reloc_info_array = nullptr;
   {
     AllocationResult allocation =
@@ skipping 27 matching lines @@
   CopyBytes(new_code->relocation_start(), reloc_info.start(),
             static_cast<size_t>(reloc_info.length()));
 
   // Relocate the copy.
   DCHECK(IsAligned(bit_cast<intptr_t>(new_code->address()), kCodeAlignment));
   DCHECK(isolate_->code_range() == NULL || !isolate_->code_range()->valid() ||
          isolate_->code_range()->contains(code->address()) ||
          new_obj_size <= code_space()->AreaSize());
 
   new_code->Relocate(new_addr - old_addr);
-
+  // We have to iterate over over the object and process its pointers when
+  // black allocation is on.
+  incremental_marking()->IterateBlackObject(new_code);
 #ifdef VERIFY_HEAP
   if (FLAG_verify_heap) code->ObjectVerify();
 #endif
   return new_code;
 }
 
 
 void Heap::InitializeAllocationMemento(AllocationMemento* memento,
                                        AllocationSite* allocation_site) {
   memento->set_map_no_write_barrier(allocation_memento_map());
@@ skipping 747 matching lines @@
               gc_idle_time_handler_->ShouldDoFinalIncrementalMarkCompact(
                   static_cast<size_t>(idle_time_in_ms), size_of_objects,
                   final_incremental_mark_compact_speed_in_bytes_per_ms))) {
     CollectAllGarbage(current_gc_flags_,
                       "idle notification: finalize incremental marking");
     return true;
   }
   return false;
 }
 
+void Heap::RegisterReservationsForBlackAllocation(Reservation* reservations) {
+  // TODO(hpayer): We do not have to iterate reservations on black objects
+  // for marking. We just have to execute the special visiting side effect
+  // code that adds objects to global data structures, e.g. ifor array buffers.
+  if (incremental_marking()->black_allocation()) {
+    for (int i = OLD_SPACE; i < Serializer::kNumberOfSpaces; i++) {
+      const Heap::Reservation& res = reservations[i];
+      for (auto& chunk : res) {
+        Address addr = chunk.start;
+        while (addr < chunk.end) {
+          HeapObject* obj = HeapObject::FromAddress(addr);
+          incremental_marking()->IterateBlackObject(obj);
+          addr += obj->Size();
+        }
+      }
+    }
+  }
+}
 
 GCIdleTimeHeapState Heap::ComputeHeapState() {
   GCIdleTimeHeapState heap_state;
   heap_state.contexts_disposed = contexts_disposed_;
   heap_state.contexts_disposal_rate =
       tracer()->ContextDisposalRateInMilliseconds();
   heap_state.size_of_objects = static_cast<size_t>(SizeOfObjects());
   heap_state.incremental_marking_stopped = incremental_marking()->IsStopped();
   return heap_state;
 }
@@ skipping 326 matching lines @@
                           new_space_.FromSpaceEnd());
   while (it.has_next()) {
     NewSpacePage* page = it.next();
     for (Address cursor = page->area_start(), limit = page->area_end();
          cursor < limit; cursor += kPointerSize) {
       Memory::Address_at(cursor) = kFromSpaceZapValue;
     }
   }
 }
 
-
-void Heap::IterateAndMarkPointersToFromSpace(HeapObject* object, Address start,
-                                             Address end, bool record_slots,
-                                             ObjectSlotCallback callback) {
+void Heap::IteratePromotedObjectPointers(HeapObject* object, Address start,
+                                         Address end, bool record_slots,
+                                         ObjectSlotCallback callback) {
   Address slot_address = start;
 
   while (slot_address < end) {
     Object** slot = reinterpret_cast<Object**>(slot_address);
     Object* target = *slot;
     // If the store buffer becomes overfull we mark pages as being exempt from
     // the store buffer.  These pages are scanned to find pointers that point
     // to the new space.  In that case we may hit newly promoted objects and
     // fix the pointers before the promotion queue gets to them.  Thus the 'if'.
     if (target->IsHeapObject()) {
       if (Heap::InFromSpace(target)) {
         callback(reinterpret_cast<HeapObject**>(slot),
                  HeapObject::cast(target));
         Object* new_target = *slot;
         if (InNewSpace(new_target)) {
           SLOW_DCHECK(Heap::InToSpace(new_target));
           SLOW_DCHECK(new_target->IsHeapObject());
           store_buffer_.Mark(reinterpret_cast<Address>(slot));
         }
         SLOW_DCHECK(!MarkCompactCollector::IsOnEvacuationCandidate(new_target));
       } else if (record_slots &&
                  MarkCompactCollector::IsOnEvacuationCandidate(target)) {
         mark_compact_collector()->RecordSlot(object, slot, target);
       }
     }
     slot_address += kPointerSize;
   }
 }
 
-
-class IteratePointersToFromSpaceVisitor final : public ObjectVisitor {
+class IteratePromotedObjectsVisitor final : public ObjectVisitor {
  public:
-  IteratePointersToFromSpaceVisitor(Heap* heap, HeapObject* target,
-                                    bool record_slots,
-                                    ObjectSlotCallback callback)
+  IteratePromotedObjectsVisitor(Heap* heap, HeapObject* target,
+                                bool record_slots, ObjectSlotCallback callback)
       : heap_(heap),
         target_(target),
         record_slots_(record_slots),
         callback_(callback) {}
 
   V8_INLINE void VisitPointers(Object** start, Object** end) override {
-    heap_->IterateAndMarkPointersToFromSpace(
+    heap_->IteratePromotedObjectPointers(
         target_, reinterpret_cast<Address>(start),
         reinterpret_cast<Address>(end), record_slots_, callback_);
+    // When black allocations is on, we have to visit objects promoted to
+    // black pages to keep their references alive.
+    // TODO(hpayer): Implement a special promotion visitor that incorporates
+    // regular visiting and IteratePromotedObjectPointers.
+    // TODO(hpayer): Right now we are also going to process black objects

[ulan, 2016/02/16 10:38:09]

This could be a problem if the non-pure marking visitor is not idempotent. For
example, this could lead to registering the same object twice in the same list.

[Hannes Payer (out of office), 2016/03/11 14:20:48]

As discussed offline, we are not going to process already marked black objects
(in new space). Done.

+    // that got promoted to black pages. Filter them out to avoid unecessary
+    // work.
+    heap_->incremental_marking()->IterateBlackObject(target_);

[ulan, 2016/02/16 10:38:09]

I think this should be called in line 4546, not here, because we want to invoke
marking visitor once per promoted object if black allocation is on.

[Hannes Payer (out of office), 2016/03/11 14:20:48]

Done.

   }
 
-  V8_INLINE void VisitCodeEntry(Address code_entry_slot) override {}
+  V8_INLINE void VisitCodeEntry(Address code_entry_slot) override {
+    // Black allocation requires us to process objects referenced by
+    // promoted objects.
+    if (heap_->incremental_marking()->black_allocation()) {
+      Code* code = Code::cast(Code::GetObjectFromEntryAddress(code_entry_slot));
+      IncrementalMarking::MarkObject(heap_, code);
+    }
+  }
 
  private:
   Heap* heap_;
   HeapObject* target_;
   bool record_slots_;
   ObjectSlotCallback callback_;
 };
 
-
-void Heap::IteratePointersToFromSpace(HeapObject* target, int size,
-                                      ObjectSlotCallback callback) {
+void Heap::IteratePromotedObject(HeapObject* target, int size,
+                                 ObjectSlotCallback callback) {
   // We are not collecting slots on new space objects during mutation
   // thus we have to scan for pointers to evacuation candidates when we
   // promote objects. But we should not record any slots in non-black
   // objects. Grey object's slots would be rescanned.
   // White object might not survive until the end of collection
   // it would be a violation of the invariant to record it's slots.
   bool record_slots = false;
   if (incremental_marking()->IsCompacting()) {
     MarkBit mark_bit = Marking::MarkBitFrom(target);
     record_slots = Marking::IsBlack(mark_bit);
   }
 
-  IteratePointersToFromSpaceVisitor visitor(this, target, record_slots,
-                                            callback);
+  IteratePromotedObjectsVisitor visitor(this, target, record_slots, callback);
   target->IterateBody(target->map()->instance_type(), size, &visitor);
+
+  // Black allocation requires us to process objects referenced by
+  // promoted objects.
+  if (incremental_marking()->black_allocation()) {
+    Map* map = target->map();
+    IncrementalMarking::MarkObject(this, map);
+  }
 }
 
 
 void Heap::IterateRoots(ObjectVisitor* v, VisitMode mode) {
   IterateStrongRoots(v, mode);
   IterateWeakRoots(v, mode);
 }
 
 
 void Heap::IterateWeakRoots(ObjectVisitor* v, VisitMode mode) {
@@ skipping 1643 matching lines @@
 }
 
 
 // static
 int Heap::GetStaticVisitorIdForMap(Map* map) {
   return StaticVisitorBase::GetVisitorId(map);
 }
 
 }  // namespace internal
 }  // namespace v8