[heap] Non-contiguous young generation

src/heap/heap.h

 // Copyright 2012 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_HEAP_H_
 #define V8_HEAP_HEAP_H_
 
 #include <cmath>
 #include <map>
 
@@ skipping 1156 matching lines @@
   size_t ObjectSizeAtLastGC(size_t index);
 
   // Retrieves names of buckets used by object statistics tracking.
   bool GetObjectTypeName(size_t index, const char** object_type,
                          const char** object_sub_type);
 
   // ===========================================================================
   // GC statistics. ============================================================
   // ===========================================================================
 
-  // Returns the maximum amount of memory reserved for the heap.  For
-  // the young generation, we reserve 4 times the amount needed for a
-  // semi space.  The young generation consists of two semi spaces and
-  // we reserve twice the amount needed for those in order to ensure
-  // that new space can be aligned to its size.
+  // Returns the maximum amount of memory reserved for the heap.
   intptr_t MaxReserved() {
-    return 4 * reserved_semispace_size_ + max_old_generation_size_;
+    return 2 * max_semi_space_size_ + max_old_generation_size_;
   }
   int MaxSemiSpaceSize() { return max_semi_space_size_; }
-  int ReservedSemiSpaceSize() { return reserved_semispace_size_; }
   int InitialSemiSpaceSize() { return initial_semispace_size_; }
   intptr_t MaxOldGenerationSize() { return max_old_generation_size_; }
   intptr_t MaxExecutableSize() { return max_executable_size_; }
 
   // Returns the capacity of the heap in bytes w/o growing. Heap grows when
   // more spaces are needed until it reaches the limit.
   intptr_t Capacity();
 
   // Returns the amount of memory currently committed for the heap.
   intptr_t CommittedMemory();
@@ skipping 791 matching lines @@
   // Caches the amount of external memory registered at the last global gc.
   int64_t amount_of_external_allocated_memory_at_last_global_gc_;
 
   // This can be calculated directly from a pointer to the heap; however, it is
   // more expedient to get at the isolate directly from within Heap methods.
   Isolate* isolate_;
 
   Object* roots_[kRootListLength];
 
   size_t code_range_size_;
-  int reserved_semispace_size_;
   int max_semi_space_size_;
   int initial_semispace_size_;
-  int target_semispace_size_;
   intptr_t max_old_generation_size_;
   intptr_t initial_old_generation_size_;
   bool old_generation_size_configured_;
   intptr_t max_executable_size_;
   intptr_t maximum_committed_;
 
   // For keeping track of how much data has survived
   // scavenge since last new space expansion.
   intptr_t survived_since_last_expansion_;
 
@@ skipping 647 matching lines @@
   friend class LargeObjectSpace;
   friend class NewSpace;
   friend class PagedSpace;
   DISALLOW_COPY_AND_ASSIGN(AllocationObserver);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_HEAP_H_