Shrink new space on compacting collections.

src/spaces.h

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 992 matching lines @@
 
   // True if the space has been set up but not torn down.
   bool HasBeenSetup() { return start_ != NULL; }
 
   // Grow the size of the semispace by committing extra virtual memory.
   // Assumes that the caller has checked that the semispace has not reached
   // its maximum capacity (and thus there is space available in the reserved
   // address range to grow).
   bool Grow();
 
+  // Grow the semispace to the new capacity.  The new capacity
+  // requested must be larger than the current capacity.
+  bool GrowTo(int new_capacity);
+
+  // Shrinks the semispace to the new capacity.  The new capacity
+  // requested must be more than the amount of used memory in the
+  // semispace and less than the current capacity.
+  bool ShrinkTo(int new_capacity);
+
   // Returns the start address of the space.
   Address low() { return start_; }
   // Returns one past the end address of the space.
   Address high() { return low() + capacity_; }
 
   // Age mark accessors.
   Address age_mark() { return age_mark_; }
   void set_age_mark(Address mark) { age_mark_ = mark; }
 
   // True if the address is in the address range of this semispace (not
@@ skipping 27 matching lines @@
   virtual void Print();
   virtual void Verify();
 #endif
 
   // Returns the current capacity of the semi space.
   int Capacity() { return capacity_; }
 
   // Returns the maximum capacity of the semi space.
   int MaximumCapacity() { return maximum_capacity_; }
 
+  // Returns the initial capacity of the semi space.
+  int InitialCapacity() { return initial_capacity_; }
 
  private:
   // The current and maximum capacity of the space.
   int capacity_;
   int maximum_capacity_;
+  int initial_capacity_;
 
   // The start address of the space.
   Address start_;
   // Used to govern object promotion during mark-compact collection.
   Address age_mark_;
 
   // Masks and comparison values to test for containment in this semispace.
   uintptr_t address_mask_;
   uintptr_t object_mask_;
   uintptr_t object_expected_;
@@ skipping 70 matching lines @@
 
   // True if the space has been set up but not torn down.
   bool HasBeenSetup() {
     return to_space_.HasBeenSetup() && from_space_.HasBeenSetup();
   }
 
   // Flip the pair of spaces.
   void Flip();
 
   // Grow the capacity of the semispaces.  Assumes that they are not at
-  // their maximum capacity.  Returns a flag indicating success or failure.
-  bool Grow();
+  // their maximum capacity.
+  void Grow();
+
+  // Shrink the capacity of the semispaces.
+  void Shrink();
 
   // True if the address or object lies in the address range of either
   // semispace (not necessarily below the allocation pointer).
   bool Contains(Address a) {
     return (reinterpret_cast<uintptr_t>(a) & address_mask_)
         == reinterpret_cast<uintptr_t>(start_);
   }
   bool Contains(Object* o) {
     return (reinterpret_cast<uintptr_t>(o) & object_mask_) == object_expected_;
   }
 
   // Return the allocated bytes in the active semispace.
   virtual int Size() { return top() - bottom(); }
   // Return the current capacity of a semispace.
   int Capacity() {
     ASSERT(to_space_.Capacity() == from_space_.Capacity());
     return to_space_.Capacity();
   }
   // Return the available bytes without growing in the active semispace.
   int Available() { return Capacity() - Size(); }
 
   // Return the maximum capacity of a semispace.
   int MaximumCapacity() {
     ASSERT(to_space_.MaximumCapacity() == from_space_.MaximumCapacity());
     return to_space_.MaximumCapacity();
   }
 
+  // Returns the initial capacity of a semispace.
+  int InitialCapacity() {
+    ASSERT(to_space_.InitialCapacity() == from_space_.InitialCapacity());
+    return to_space_.InitialCapacity();
+  }
+
   // Return the address of the allocation pointer in the active semispace.
   Address top() { return allocation_info_.top; }
   // Return the address of the first object in the active semispace.
   Address bottom() { return to_space_.low(); }
 
   // Get the age mark of the inactive semispace.
   Address age_mark() { return from_space_.age_mark(); }
   // Set the age mark in the active semispace.
   void set_age_mark(Address mark) { to_space_.set_age_mark(mark); }
 
@@ skipping 648 matching lines @@
 
  private:
   LargeObjectChunk* current_;
   HeapObjectCallback size_func_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_SPACES_H_