[heap] Reland uncommit unused large object page memory.

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 <list>
 
 #include "src/allocation.h"
@@ skipping 610 matching lines @@
 
   int write_barrier_counter() {
     return static_cast<int>(write_barrier_counter_);
   }
 
   void set_write_barrier_counter(int counter) {
     write_barrier_counter_ = counter;
   }
 
   size_t size() const { return size_; }
+  void set_size(size_t size) { size_ = size; }
 
   inline Heap* heap() const { return heap_; }
 
   inline SkipList* skip_list() { return skip_list_; }
 
   inline void set_skip_list(SkipList* skip_list) { skip_list_ = skip_list; }
 
   inline SlotSet* old_to_new_slots() { return old_to_new_slots_; }
   inline SlotSet* old_to_old_slots() { return old_to_old_slots_; }
   inline TypedSlotSet* typed_old_to_new_slots() {
@@ skipping 15 matching lines @@
   void AllocateLocalTracker();
   void ReleaseLocalTracker();
 
   Address area_start() { return area_start_; }
   Address area_end() { return area_end_; }
   int area_size() { return static_cast<int>(area_end() - area_start()); }
 
   bool CommitArea(size_t requested);
 
   // Approximate amount of physical memory committed for this chunk.
-  size_t CommittedPhysicalMemory() { return high_water_mark_.Value(); }
+  size_t CommittedPhysicalMemory();
 
   Address HighWaterMark() { return address() + high_water_mark_.Value(); }
 
   int progress_bar() {
     DCHECK(IsFlagSet(HAS_PROGRESS_BAR));
     return progress_bar_;
   }
 
   void set_progress_bar(int progress_bar) {
     DCHECK(IsFlagSet(HAS_PROGRESS_BAR));
@@ skipping 319 matching lines @@
 class LargePage : public MemoryChunk {
  public:
   HeapObject* GetObject() { return HeapObject::FromAddress(area_start()); }
 
   inline LargePage* next_page() {
     return static_cast<LargePage*>(next_chunk());
   }
 
   inline void set_next_page(LargePage* page) { set_next_chunk(page); }
 
+  // Uncommit memory that is not in use anymore by the object. If the object
+  // cannot be shrunk 0 is returned.
+  Address GetAddressToShrink();
+
+  void ClearOutOfLiveRangeSlots(Address free_start);
+
   // A limit to guarantee that we do not overflow typed slot offset in
   // the old to old remembered set.
   // Note that this limit is higher than what assembler already imposes on
   // x64 and ia32 architectures.
   static const int kMaxCodePageSize = 512 * MB;
 
  private:
   static inline LargePage* Initialize(Heap* heap, MemoryChunk* chunk,
                                       Executability executable, Space* owner);
 
@@ skipping 431 matching lines @@
 
   Address ReserveAlignedMemory(size_t requested, size_t alignment,
                                base::VirtualMemory* controller);
   Address AllocateAlignedMemory(size_t reserve_size, size_t commit_size,
                                 size_t alignment, Executability executable,
                                 base::VirtualMemory* controller);
 
   bool CommitMemory(Address addr, size_t size, Executability executable);
 
   void FreeMemory(base::VirtualMemory* reservation, Executability executable);
+  void PartialFreeMemory(MemoryChunk* chunk, Address start_free);
   void FreeMemory(Address addr, size_t size, Executability executable);
 
   // Commit a contiguous block of memory from the initial chunk.  Assumes that
   // the address is not NULL, the size is greater than zero, and that the
   // block is contained in the initial chunk.  Returns true if it succeeded
   // and false otherwise.
   bool CommitBlock(Address start, size_t size, Executability executable);
 
   // Uncommit a contiguous block of memory [start..(start+size)[.
   // start is not NULL, the size is greater than zero, and the
@@ skipping 1601 matching lines @@
   // Finds a large object page containing the given address, returns NULL
   // if such a page doesn't exist.
   LargePage* FindPage(Address a);
 
   // Clears the marking state of live objects.
   void ClearMarkingStateOfLiveObjects();
 
   // Frees unmarked objects.
   void FreeUnmarkedObjects();
 
+  void InsertChunkMapEntries(LargePage* page);
+  void RemoveChunkMapEntries(LargePage* page);
+  void RemoveChunkMapEntries(LargePage* page, Address free_start);
+
   // Checks whether a heap object is in this space; O(1).
   bool Contains(HeapObject* obj);
   // Checks whether an address is in the object area in this space. Iterates
   // all objects in the space. May be slow.
   bool ContainsSlow(Address addr) { return FindObject(addr)->IsHeapObject(); }
 
   // Checks whether the space is empty.
   bool IsEmpty() { return first_page_ == NULL; }
 
   void AdjustLiveBytes(int by) { objects_size_ += by; }
@@ skipping 74 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_