Reland of [heap] Simplify distribution of remaining memory during sweeping & compaction

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 2101 matching lines @@
 
   // Return size of allocatable area on a page in this space.
   inline int AreaSize() { return area_size_; }
 
   virtual bool is_local() { return false; }
 
   // Merges {other} into the current space. Note that this modifies {other},
   // e.g., removes its bump pointer area and resets statistics.
   void MergeCompactionSpace(CompactionSpace* other);
 
-  void DivideUponCompactionSpaces(CompactionSpaceCollection** other, int num,
-                                  intptr_t limit = kCompactionMemoryWanted);
-
   // Refills the free list from the corresponding free list filled by the
   // sweeper.
   virtual void RefillFreeList();
 
  protected:
   void AddMemory(Address start, intptr_t size);
 
-  FreeSpace* TryRemoveMemory(intptr_t size_in_bytes);
-
   void MoveOverFreeMemory(PagedSpace* other);
 
   // PagedSpaces that should be included in snapshots have different, i.e.,
   // smaller, initial pages.
   virtual bool snapshotable() { return true; }
 
   FreeList* free_list() { return &free_list_; }
 
   bool HasPages() { return anchor_.next_page() != &anchor_; }
 
@@ skipping 742 matching lines @@
 };
 
 // -----------------------------------------------------------------------------
 // Compaction space that is used temporarily during compaction.
 
 class CompactionSpace : public PagedSpace {
  public:
   CompactionSpace(Heap* heap, AllocationSpace id, Executability executable)
       : PagedSpace(heap, id, executable) {}
 
-  // Adds external memory starting at {start} of {size_in_bytes} to the space.
-  void AddExternalMemory(Address start, int size_in_bytes) {
-    IncreaseCapacity(size_in_bytes);
-    Free(start, size_in_bytes);
-  }
-
   bool is_local() override { return true; }
 
   void RefillFreeList() override;
 
  protected:
   // The space is temporary and not included in any snapshots.
   bool snapshotable() override { return false; }
 
   MUST_USE_RESULT HeapObject* SweepAndRetryAllocation(
       int size_in_bytes) override;
@@ skipping 216 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_