One Zone per CompilationInfo.

src/zone.h

 // Copyright 2012 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 46 matching lines @@
 
 // Note: There is no need to initialize the Zone; the first time an
 // allocation is attempted, a segment of memory will be requested
 // through a call to malloc().
 
 // Note: The implementation is inherently not thread safe. Do not use
 // from multi-threaded code.
 
 class Zone {
  public:
+  explicit Zone(Isolate* isolate);
+  ~Zone() { DeleteKeptSegment(); }
   // Allocate 'size' bytes of memory in the Zone; expands the Zone by
   // allocating new segments of memory on demand using malloc().
   inline void* New(int size);
 
   template <typename T>
   inline T* NewArray(int length);
 
   // Deletes all objects and free all memory allocated in the Zone. Keeps one
   // small (size <= kMaximumKeptSegmentSize) segment around if it finds one.
   void DeleteAll();
@@ skipping 30 matching lines @@
   static const int kMaximumKeptSegmentSize = 64 * KB;
 
   // Report zone excess when allocation exceeds this limit.
   int zone_excess_limit_;
 
   // The number of bytes allocated in segments.  Note that this number
   // includes memory allocated from the OS but not yet allocated from
   // the zone.
   int segment_bytes_allocated_;
 
-  // Each isolate gets its own zone.
-  Zone();
-
   // Expand the Zone to hold at least 'size' more bytes and allocate
   // the bytes. Returns the address of the newly allocated chunk of
   // memory in the Zone. Should only be called if there isn't enough
   // room in the Zone already.
   Address NewExpand(int size);
 
   // Creates a new segment, sets it size, and pushes it to the front
   // of the segment chain. Returns the new segment.
   Segment* NewSegment(int size);
 
@@ skipping 98 matching lines @@
   void operator delete(void* pointer) { UNREACHABLE(); }
   void operator delete(void* pointer, Zone* zone) { UNREACHABLE(); }
 };
 
 
 // ZoneScopes keep track of the current parsing and compilation
 // nesting and cleans up generated ASTs in the Zone when exiting the
 // outer-most scope.
 class ZoneScope BASE_EMBEDDED {
  public:
-  INLINE(ZoneScope(Isolate* isolate, ZoneScopeMode mode));
+  INLINE(ZoneScope(Zone* zone, ZoneScopeMode mode));
 
   virtual ~ZoneScope();
 
   inline bool ShouldDeleteOnExit();
 
   // For ZoneScopes that do not delete on exit by default, call this
   // method to request deletion on exit.
   void DeleteOnExit() {
     mode_ = DELETE_ON_EXIT;
   }
 
   inline static int nesting();
 
  private:
-  Isolate* isolate_;
+  Zone* zone_;
   ZoneScopeMode mode_;
 };
 
 
 // A zone splay tree.  The config type parameter encapsulates the
 // different configurations of a concrete splay tree (see splay-tree.h).
 // The tree itself and all its elements are allocated in the Zone.
 template <typename Config>
 class ZoneSplayTree: public SplayTree<Config, ZoneAllocationPolicy> {
  public:
   explicit ZoneSplayTree(Zone* zone)
       : SplayTree<Config, ZoneAllocationPolicy>(ZoneAllocationPolicy(zone)) {}
   ~ZoneSplayTree();
 };
 
 
 typedef TemplateHashMapImpl<ZoneAllocationPolicy> ZoneHashMap;
 
 } }  // namespace v8::internal
 
 #endif  // V8_ZONE_H_