Use a per-isolate cache for the date object JS bits

src/runtime.cc

 // 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 9596 matching lines @@
   SealHandleScope shs(isolate);
   ASSERT(args.length() == 1);
 
   CONVERT_DOUBLE_ARG_CHECKED(x, 0);
   int64_t time = isolate->date_cache()->ToUTC(static_cast<int64_t>(x));
 
   return isolate->heap()->NumberFromDouble(static_cast<double>(time));
 }
 
 
+RUNTIME_FUNCTION(MaybeObject*, Runtime_DateCacheVersion) {
+  HandleScope hs(isolate);
+  ASSERT(args.length() == 0);
+  if (!isolate->eternal_handles()->Exists(EternalHandles::DATE_CACHE_VERSION)) {
+    Handle<FixedArray> date_cache_version =
+        isolate->factory()->NewFixedArray(1, TENURED);
+    date_cache_version->set(0, Smi::FromInt(0));
+    isolate->eternal_handles()->CreateSingleton(
+        isolate, *date_cache_version, EternalHandles::DATE_CACHE_VERSION);
+  }
+  Handle<FixedArray> date_cache_version =
+      Handle<FixedArray>::cast(isolate->eternal_handles()->GetSingleton(
+          EternalHandles::DATE_CACHE_VERSION));
+  // Return result as a JS array.
+  Handle<JSObject> result =
+      isolate->factory()->NewJSObject(isolate->array_function());
+  isolate->factory()->SetContent(Handle<JSArray>::cast(result),
+                                 date_cache_version);
+  return *result;
+}
+
+
 RUNTIME_FUNCTION(MaybeObject*, Runtime_GlobalReceiver) {
   SealHandleScope shs(isolate);
   ASSERT(args.length() == 1);
   Object* global = args[0];
   if (!global->IsJSGlobalObject()) return isolate->heap()->null_value();
   return JSGlobalObject::cast(global)->global_receiver();
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_IsAttachedGlobal) {
@@ skipping 5342 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal