New page local store buffer.

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 268 matching lines @@
     }
     // Clear all bits in the last cell till the last bit before index.
     uint32_t clear_mask = ~((1u << IndexInCell(index)) - 1);
     cells()[end_cell_index] &= clear_mask;
   }
 };
 
 
 class SkipList;
 class SlotsBuffer;
+class SlotSet;
 
 // MemoryChunk represents a memory region owned by a specific space.
 // It is divided into the header and the body. Chunk start is always
 // 1MB aligned. Start of the body is aligned so it can accommodate
 // any heap object.
 class MemoryChunk {
  public:
   enum MemoryChunkFlags {
     IS_EXECUTABLE,
     ABOUT_TO_BE_FREED,
     POINTERS_TO_HERE_ARE_INTERESTING,
     POINTERS_FROM_HERE_ARE_INTERESTING,
-    SCAN_ON_SCAVENGE,
     IN_FROM_SPACE,  // Mutually exclusive with IN_TO_SPACE.
     IN_TO_SPACE,    // All pages in new space has one of these two set.
     NEW_SPACE_BELOW_AGE_MARK,
     EVACUATION_CANDIDATE,
     RESCAN_ON_EVACUATION,
     NEVER_EVACUATE,  // May contain immortal immutables.
     POPULAR_PAGE,    // Slots buffer of this page overflowed on the previous GC.
 
     // WAS_SWEPT indicates that marking bits have been cleared by the sweeper,
     // otherwise marking bits are still intact.
@@ skipping 84 matching lines @@
       + 2 * kPointerSize          // base::VirtualMemory reservation_
       + kPointerSize              // Address owner_
       + kPointerSize              // Heap* heap_
       + kIntSize;                 // int progress_bar_
 
   static const size_t kSlotsBufferOffset =
       kLiveBytesOffset + kIntSize;  // int live_byte_count_
 
   static const size_t kWriteBarrierCounterOffset =
       kSlotsBufferOffset + kPointerSize  // SlotsBuffer* slots_buffer_;
+      + kPointerSize                     // SlotSet* old_to_new_slots_;
       + kPointerSize;                    // SkipList* skip_list_;
 
   static const size_t kMinHeaderSize =
       kWriteBarrierCounterOffset +
       kIntptrSize         // intptr_t write_barrier_counter_
       + kPointerSize      // AtomicValue high_water_mark_
       + kPointerSize      // base::Mutex* mutex_
       + kPointerSize      // base::AtomicWord parallel_sweeping_
       + kPointerSize      // AtomicValue parallel_compaction_
       + 5 * kPointerSize  // AtomicNumber free-list statistics
@@ skipping 85 matching lines @@
            kPageHeaderTag);
   }
 
   base::VirtualMemory* reserved_memory() { return &reservation_; }
 
   void set_reserved_memory(base::VirtualMemory* reservation) {
     DCHECK_NOT_NULL(reservation);
     reservation_.TakeControl(reservation);
   }
 
-  bool scan_on_scavenge() { return IsFlagSet(SCAN_ON_SCAVENGE); }
-  void initialize_scan_on_scavenge(bool scan) {
-    if (scan) {
-      SetFlag(SCAN_ON_SCAVENGE);
-    } else {
-      ClearFlag(SCAN_ON_SCAVENGE);
-    }
-  }
-  inline void set_scan_on_scavenge(bool scan);
-
   bool Contains(Address addr) {
     return addr >= area_start() && addr < area_end();
   }
 
   // Checks whether addr can be a limit of addresses in this page.
   // It's a limit if it's in the page, or if it's just after the
   // last byte of the page.
   bool ContainsLimit(Address addr) {
     return addr >= area_start() && addr <= area_end();
   }
@@ skipping 166 matching lines @@
   }
 
   inline SkipList* skip_list() { return skip_list_; }
 
   inline void set_skip_list(SkipList* skip_list) { skip_list_ = skip_list; }
 
   inline SlotsBuffer* slots_buffer() { return slots_buffer_; }
 
   inline SlotsBuffer** slots_buffer_address() { return &slots_buffer_; }
 
+  inline SlotSet* old_to_new_slots() { return old_to_new_slots_; }
+
+  void AllocateOldToNewSlots();
+  void ReleaseOldToNewSlots();
+
   void MarkEvacuationCandidate() {
     DCHECK(!IsFlagSet(NEVER_EVACUATE));
     DCHECK(slots_buffer_ == NULL);
     SetFlag(EVACUATION_CANDIDATE);
   }
 
   void ClearEvacuationCandidate() {
     DCHECK(slots_buffer_ == NULL);
     ClearFlag(EVACUATION_CANDIDATE);
   }
@@ skipping 27 matching lines @@
   // no failure can be in an object, so this can be distinguished from any entry
   // in a fixed array.
   Address owner_;
   Heap* heap_;
   // Used by the incremental marker to keep track of the scanning progress in
   // large objects that have a progress bar and are scanned in increments.
   int progress_bar_;
   // Count of bytes marked black on page.
   int live_byte_count_;
   SlotsBuffer* slots_buffer_;
+  // A single slot set for small pages (of size kPageSize) or an array of slot
+  // set for large pages. In the latter case the number of entries in the array
+  // is ceil(size() / kPageSize).
+  SlotSet* old_to_new_slots_;
   SkipList* skip_list_;
   intptr_t write_barrier_counter_;
   // Assuming the initial allocation on a page is sequential,
   // count highest number of bytes ever allocated on the page.
   AtomicValue<intptr_t> high_water_mark_;
 
   base::Mutex* mutex_;
   AtomicValue<ParallelSweepingState> parallel_sweeping_;
   AtomicValue<ParallelCompactingState> parallel_compaction_;
 
@@ skipping 1495 matching lines @@
 
 class SemiSpace;
 
 
 class NewSpacePage : public MemoryChunk {
  public:
   // GC related flags copied from from-space to to-space when
   // flipping semispaces.
   static const intptr_t kCopyOnFlipFlagsMask =
       (1 << MemoryChunk::POINTERS_TO_HERE_ARE_INTERESTING) |
-      (1 << MemoryChunk::POINTERS_FROM_HERE_ARE_INTERESTING) |
-      (1 << MemoryChunk::SCAN_ON_SCAVENGE);
+      (1 << MemoryChunk::POINTERS_FROM_HERE_ARE_INTERESTING);
 
   static const int kAreaSize = Page::kAllocatableMemory;
 
   inline NewSpacePage* next_page() {
     return static_cast<NewSpacePage*>(next_chunk());
   }
 
   inline void set_next_page(NewSpacePage* page) { set_next_chunk(page); }
 
   inline NewSpacePage* prev_page() {
@@ skipping 939 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_