[heap] Non-contiguous young generation

src/base/platform/platform.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.
 
 // This module contains the platform-specific code. This make the rest of the
 // code less dependent on operating system, compilers and runtime libraries.
 // This module does specifically not deal with differences between different
 // processor architecture.
 // The platform classes have the same definition for all platforms. The
 // implementation for a particular platform is put in platform_<os>.cc.
@@ skipping 273 matching lines @@
   VirtualMemory();
 
   // Reserves virtual memory with size.
   explicit VirtualMemory(size_t size);
 
   // Reserves virtual memory containing an area of the given size that
   // is aligned per alignment. This may not be at the position returned
   // by address().
   VirtualMemory(size_t size, size_t alignment);
 
+  // Construct a virtual memory by assigning it some already mapped address
+  // and size.
+  VirtualMemory(void* address, size_t size) : address_(address), size_(size) {}
+
   // Releases the reserved memory, if any, controlled by this VirtualMemory
   // object.
   ~VirtualMemory();
 
   // Returns whether the memory has been reserved.
   bool IsReserved();
 
   // Initialize or resets an embedded VirtualMemory object.
   void Reset();
 
@@ skipping 173 matching lines @@
   int stack_size_;
   Semaphore* start_semaphore_;
 
   DISALLOW_COPY_AND_ASSIGN(Thread);
 };
 
 }  // namespace base
 }  // namespace v8
 
 #endif  // V8_BASE_PLATFORM_PLATFORM_H_