[heap] Reland "Remove black pages and use black areas instead."

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 3048 matching lines @@
         reinterpret_cast<Map*>(root(kTwoPointerFillerMapRootIndex)));
   } else {
     DCHECK_GT(size, 2 * kPointerSize);
     filler->set_map_no_write_barrier(
         reinterpret_cast<Map*>(root(kFreeSpaceMapRootIndex)));
     FreeSpace::cast(filler)->nobarrier_set_size(size);
   }
   if (mode == ClearRecordedSlots::kYes) {
     ClearRecordedSlotRange(addr, addr + size);
   }
+
+  // If the location where the filler is created is within a black area we have
+  // to clear the mark bits of the filler space.
+  if (incremental_marking()->black_allocation() &&
+      Marking::IsBlackOrGrey(ObjectMarking::MarkBitFrom(addr))) {
+    Page* page = Page::FromAddress(addr);
+    page->markbits()->ClearRange(page->AddressToMarkbitIndex(addr),
+                                 page->AddressToMarkbitIndex(addr + size));
+  }
+
   // At this point, we may be deserializing the heap from a snapshot, and
   // none of the maps have been created yet and are NULL.
   DCHECK((filler->map() == NULL && !deserialization_complete_) ||
          filler->map()->IsMap());
 }
 
 
 bool Heap::CanMoveObjectStart(HeapObject* object) {
   if (!FLAG_move_object_start) return false;
 
@@ skipping 50 matching lines @@
   DCHECK(object->map() != fixed_cow_array_map());
 
   STATIC_ASSERT(FixedArrayBase::kMapOffset == 0);
   STATIC_ASSERT(FixedArrayBase::kLengthOffset == kPointerSize);
   STATIC_ASSERT(FixedArrayBase::kHeaderSize == 2 * kPointerSize);
 
   const int len = object->length();
   DCHECK(elements_to_trim <= len);
 
   // Calculate location of new array start.
-  Address new_start = object->address() + bytes_to_trim;
+  Address old_start = object->address();
+  Address new_start = old_start + bytes_to_trim;
+
+  // Transfer the mark bits to their new location if the object is not within
+  // a black area.
+  if (!incremental_marking()->black_allocation() ||
+      !Marking::IsBlack(ObjectMarking::MarkBitFrom(new_start))) {
+    IncrementalMarking::TransferMark(this, old_start, new_start);
+  }
 
   // Technically in new space this write might be omitted (except for
   // debug mode which iterates through the heap), but to play safer
   // we still do it.
-  CreateFillerObjectAt(object->address(), bytes_to_trim,
-                       ClearRecordedSlots::kYes);
+  CreateFillerObjectAt(old_start, bytes_to_trim, ClearRecordedSlots::kYes);
   // Initialize header of the trimmed array. Since left trimming is only
   // performed on pages which are not concurrently swept creating a filler
   // object does not require synchronization.
   DCHECK(CanMoveObjectStart(object));
   Object** former_start = HeapObject::RawField(object, 0);
   int new_start_index = elements_to_trim * (element_size / kPointerSize);
   former_start[new_start_index] = map;
   former_start[new_start_index + 1] = Smi::FromInt(len - elements_to_trim);
+
   FixedArrayBase* new_object =
       FixedArrayBase::cast(HeapObject::FromAddress(new_start));
 
+  // Maintain consistency of live bytes during incremental marking
+  AdjustLiveBytes(new_object, -bytes_to_trim, Heap::CONCURRENT_TO_SWEEPER);
+
   // Remove recorded slots for the new map and length offset.
   ClearRecordedSlot(new_object, HeapObject::RawField(new_object, 0));
   ClearRecordedSlot(new_object, HeapObject::RawField(
                                     new_object, FixedArrayBase::kLengthOffset));
 
-  // Maintain consistency of live bytes during incremental marking
-  IncrementalMarking::TransferMark(this, object->address(), new_start);
-  AdjustLiveBytes(new_object, -bytes_to_trim, Heap::CONCURRENT_TO_SWEEPER);
-
   // Notify the heap profiler of change in object layout.
   OnMoveEvent(new_object, object, new_object->Size());
   return new_object;
 }
 
 
 // Force instantiation of templatized method.
 template void Heap::RightTrimFixedArray<Heap::SEQUENTIAL_TO_SWEEPER>(
     FixedArrayBase*, int);
 template void Heap::RightTrimFixedArray<Heap::CONCURRENT_TO_SWEEPER>(
@@ skipping 994 matching lines @@
 
 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. for array buffers.
 
   // Code space, map space, and large object space do not use black pages.
   // Hence we have to color all objects of the reservation first black to avoid
   // unnecessary marking deque load.
   if (incremental_marking()->black_allocation()) {
-    for (int i = CODE_SPACE; i < Serializer::kNumberOfSpaces; i++) {
+    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);
           Marking::MarkBlack(ObjectMarking::MarkBitFrom(obj));
-          MemoryChunk::IncrementLiveBytesFromGC(obj, obj->Size());
           addr += obj->Size();
         }
       }
     }
     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);
@@ skipping 2240 matching lines @@
 }
 
 
 // static
 int Heap::GetStaticVisitorIdForMap(Map* map) {
   return StaticVisitorBase::GetVisitorId(map);
 }
 
 }  // namespace internal
 }  // namespace v8