[heap] Divide available memory upon compaction tasks

src/heap/spaces.h

Index: src/heap/spaces.h
diff --git a/src/heap/spaces.h b/src/heap/spaces.h
index 69a8d89fccba5c5aa06f91d2a1995870b70ef033..79cb9a4b4cef2c8e8c8301e56378885ee1ce27a8 100644
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -19,6 +19,7 @@
 namespace v8 {
 namespace internal {
 
+class CompactionSpaceCollection;
 class Isolate;
 
 // -----------------------------------------------------------------------------
@@ -1726,6 +1727,15 @@ class FreeList {
   // The size should be a non-zero multiple of the word size.
   MUST_USE_RESULT HeapObject* Allocate(int size_in_bytes);
 
+  // The method tries to find a {FreeSpace} node of at least {size_in_bytes}
+  // size in the appropriate free list category. If no suitable node could be
+  // found, the method falls back to retrieving the largest possible {FreeSpace}
+  // node in the free list. Upon returning nullptr the free list is observed as
+  // empty.
+  //
+  // Can be used concurrently.
+  MUST_USE_RESULT FreeSpace* TryRemoveMemory(intptr_t hint_size_in_bytes);
+
   bool IsEmpty() {
     return small_list_.IsEmpty() && medium_list_.IsEmpty() &&
            large_list_.IsEmpty() && huge_list_.IsEmpty();
@@ -1780,7 +1790,6 @@ class FreeList {
     return nullptr;
   }
 
-
   PagedSpace* owner_;
   Heap* heap_;
   base::Mutex mutex_;
@@ -2040,15 +2049,22 @@ class PagedSpace : public Space {
   // 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 MoveOverFreeMemory(PagedSpace* other);
-
-  virtual bool is_local() { return false; }
+  void DivideUponCompactionSpaces(CompactionSpaceCollection** other, int num,
+                                  intptr_t limit);
 
  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; }
@@ -2109,6 +2125,9 @@ class PagedSpace : public Space {
 
   friend class MarkCompactCollector;
   friend class PageIterator;
+
+  // Used in cctest.
+  friend class HeapTester;
 };