Allow FastCloneShallowObjectStub to use AllocationMementos.

src/hydrogen.cc

 // Copyright 2013 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 4317 matching lines @@
 
 void HOptimizedGraphBuilder::VisitObjectLiteral(ObjectLiteral* expr) {
   ASSERT(!HasStackOverflow());
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
   Handle<JSFunction> closure = function_state()->compilation_info()->closure();
   HInstruction* literal;
 
   // Check whether to use fast or slow deep-copying for boilerplate.
   int max_properties = kMaxFastLiteralProperties;
-  Handle<Object> boilerplate(closure->literals()->get(
-      expr->literal_index()), isolate());
-  if (boilerplate->IsJSObject() &&
-      IsFastLiteral(Handle<JSObject>::cast(boilerplate),
-                    kMaxFastLiteralDepth,
-                    &max_properties)) {
-    Handle<JSObject> boilerplate_object = Handle<JSObject>::cast(boilerplate);
+  Handle<Object> literals_cell(closure->literals()->get(expr->literal_index()),
+                               isolate());
+  Handle<AllocationSite> site;
+  Handle<JSObject> boilerplate;
+  if (!literals_cell->IsUndefined()) {
+    // Retrieve the boilerplate
+    site = Handle<AllocationSite>::cast(literals_cell);
+    boilerplate = Handle<JSObject>(JSObject::cast(site->transition_info()),
+                                   isolate());
+  }
 
-    literal = BuildFastLiteral(boilerplate_object);
+  if (!boilerplate.is_null() &&
+      IsFastLiteral(boilerplate, kMaxFastLiteralDepth, &max_properties)) {
+    literal = BuildFastLiteral(boilerplate);
   } else {
     NoObservableSideEffectsScope no_effects(this);
     Handle<FixedArray> closure_literals(closure->literals(), isolate());
     Handle<FixedArray> constant_properties = expr->constant_properties();
     int literal_index = expr->literal_index();
     int flags = expr->fast_elements()
         ? ObjectLiteral::kFastElements : ObjectLiteral::kNoFlags;
     flags |= expr->has_function()
         ? ObjectLiteral::kHasFunction : ObjectLiteral::kNoFlags;
 
@@ skipping 5518 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal