[heap] Black allocation.

src/heap/spaces.h

 // Copyright 2011 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.
 
 #ifndef V8_HEAP_SPACES_H_
 #define V8_HEAP_SPACES_H_
 
 #include "src/allocation.h"
 #include "src/atomic-utils.h"
 #include "src/base/atomicops.h"
@@ skipping 185 matching lines @@
   }
 
   inline MarkBit MarkBitFromIndex(uint32_t index) {
     MarkBit::CellType mask = 1u << IndexInCell(index);
     MarkBit::CellType* cell = this->cells() + (index >> kBitsPerCellLog2);
     return MarkBit(cell, mask);
   }
 
   static inline void Clear(MemoryChunk* chunk);
 
+  static inline void SetAllBits(MemoryChunk* chunk);
+
   static void PrintWord(uint32_t word, uint32_t himask = 0) {
     for (uint32_t mask = 1; mask != 0; mask <<= 1) {
       if ((mask & himask) != 0) PrintF("[");
       PrintF((mask & word) ? "1" : "0");
       if ((mask & himask) != 0) PrintF("]");
     }
   }
 
   class CellPrinter {
    public:
@@ skipping 91 matching lines @@
     RESCAN_ON_EVACUATION,
     NEVER_EVACUATE,  // May contain immortal immutables.
     POPULAR_PAGE,    // Slots buffer of this page overflowed on the previous GC.
 
     // Large objects can have a progress bar in their page header. These object
     // are scanned in increments and will be kept black while being scanned.
     // Even if the mutator writes to them they will be kept black and a white
     // to grey transition is performed in the value.
     HAS_PROGRESS_BAR,
 
+    // A black page has all mark bits set to 1 (black). A black page currently
+    // cannot be iterated because it is not swept.

[Michael Lippautz, 2016/02/04 17:59:51]

Add: Live bytes are also not updated on those pages.

[Hannes Payer (out of office), 2016/02/06 08:50:16]

Done.

+    BLACK_PAGE,
+
     // This flag is intended to be used for testing. Works only when both
     // FLAG_stress_compaction and FLAG_manual_evacuation_candidates_selection
     // are set. It forces the page to become an evacuation candidate at next
     // candidates selection cycle.
     FORCE_EVACUATION_CANDIDATE_FOR_TESTING,
 
     // This flag is inteded to be used for testing.
     NEVER_ALLOCATE_ON_PAGE,
 
     // The memory chunk is already logically freed, however the actual freeing
@@ skipping 239 matching lines @@
   // because they are marked black).
   void ResetLiveBytes() {
     if (FLAG_gc_verbose) {
       PrintF("ResetLiveBytes:%p:%x->0\n", static_cast<void*>(this),
              live_byte_count_);
     }
     live_byte_count_ = 0;
   }
 
   void IncrementLiveBytes(int by) {
+    if (IsFlagSet(BLACK_PAGE)) return;
     if (FLAG_gc_verbose) {
       printf("UpdateLiveBytes:%p:%x%c=%x->%x\n", static_cast<void*>(this),
              live_byte_count_, ((by < 0) ? '-' : '+'), ((by < 0) ? -by : by),
              live_byte_count_ + by);
     }
     live_byte_count_ += by;
     DCHECK_GE(live_byte_count_, 0);
     DCHECK_LE(static_cast<unsigned>(live_byte_count_), size_);
   }
 
   int LiveBytes() {
     DCHECK_LE(static_cast<unsigned>(live_byte_count_), size_);
+    DCHECK(!IsFlagSet(BLACK_PAGE) || live_byte_count_ == 0);
     return live_byte_count_;
   }
 
   void SetLiveBytes(int live_bytes) {
+    if (IsFlagSet(BLACK_PAGE)) return;
     DCHECK_GE(live_bytes, 0);
     DCHECK_LE(static_cast<unsigned>(live_bytes), size_);
     live_byte_count_ = live_bytes;
   }
 
   int write_barrier_counter() {
     return static_cast<int>(write_barrier_counter_);
   }
 
   void set_write_barrier_counter(int counter) {
@@ skipping 1572 matching lines @@
 
   // The space's free list.
   FreeList free_list_;
 
   // Normal allocation information.
   AllocationInfo allocation_info_;
 
   // Mutex guarding any concurrent access to the space.
   base::Mutex space_mutex_;
 
+  friend class IncrementalMarking;
   friend class MarkCompactCollector;
   friend class PageIterator;
 
   // Used in cctest.
   friend class HeapTester;
 };
 
 
 class NumberAndSizeInfo BASE_EMBEDDED {
  public:
@@ skipping 923 matching lines @@
     count = 0;
   }
   // Must be small, since an iteration is used for lookup.
   static const int kMaxComments = 64;
 };
 #endif
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_SPACES_H_