Addressed perf regression in Browsermark2.0 array blur test

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 536 matching lines @@
 
     literals->set(literals_index, *site);
   } else {
     site = Handle<AllocationSite>::cast(literal_site);
   }
 
   return site;
 }
 
 
+static MaybeObject* CreateArrayLiteralImpl(Isolate* isolate,
+                                           Handle<FixedArray> literals,
+                                           int literals_index,
+                                           Handle<FixedArray> elements,
+                                           int flags) {
+  Handle<AllocationSite> site = GetLiteralAllocationSite(isolate, literals,
+      literals_index, elements);
+  RETURN_IF_EMPTY_HANDLE(isolate, site);
+
+  Handle<JSObject> boilerplate(JSObject::cast(site->transition_info()));
+  if ((flags & ArrayLiteral::kShallowElements) != 0) {
+    if (boilerplate->elements()->map() ==
+        isolate->heap()->fixed_cow_array_map()) {
+      isolate->counters()->cow_arrays_created_runtime()->Increment();
+    }
+
+    if ((flags & ArrayLiteral::kDisableMementos) == 0 &&
+        AllocationSite::GetMode(boilerplate->GetElementsKind()) ==
+        TRACK_ALLOCATION_SITE) {
+      return isolate->heap()->CopyJSObject(*boilerplate, *site);
+    }
+
+    return isolate->heap()->CopyJSObject(*boilerplate);
+  } else {
+    AllocationSiteUsageContext usage_context(isolate, site,
+        (flags & ArrayLiteral::kDisableMementos) == 0);
+    usage_context.EnterNewScope();
+    Handle<JSObject> copy = JSObject::DeepCopy(boilerplate, &usage_context);
+    usage_context.ExitScope(site, boilerplate);
+    RETURN_IF_EMPTY_HANDLE(isolate, copy);
+    return *copy;
+  }
+}
+
+
 RUNTIME_FUNCTION(MaybeObject*, Runtime_CreateArrayLiteral) {
   HandleScope scope(isolate);
+  ASSERT(args.length() == 4);
+  CONVERT_ARG_HANDLE_CHECKED(FixedArray, literals, 0);
+  CONVERT_SMI_ARG_CHECKED(literals_index, 1);
+  CONVERT_ARG_HANDLE_CHECKED(FixedArray, elements, 2);
+  CONVERT_SMI_ARG_CHECKED(flags, 3);
+
+  return CreateArrayLiteralImpl(isolate, literals, literals_index, elements,
+                                flags);
+}
+
+
+RUNTIME_FUNCTION(MaybeObject*, Runtime_CreateArrayLiteralStubBailout) {
+  HandleScope scope(isolate);
   ASSERT(args.length() == 3);
   CONVERT_ARG_HANDLE_CHECKED(FixedArray, literals, 0);
   CONVERT_SMI_ARG_CHECKED(literals_index, 1);
   CONVERT_ARG_HANDLE_CHECKED(FixedArray, elements, 2);
 
-  Handle<AllocationSite> site = GetLiteralAllocationSite(isolate, literals,
-      literals_index, elements);
-  RETURN_IF_EMPTY_HANDLE(isolate, site);
-
-  Handle<JSObject> boilerplate(JSObject::cast(site->transition_info()));
-  AllocationSiteUsageContext usage_context(isolate, site, true);
-  usage_context.EnterNewScope();
-  Handle<JSObject> copy = JSObject::DeepCopy(boilerplate, &usage_context);
-  usage_context.ExitScope(site, boilerplate);
-  RETURN_IF_EMPTY_HANDLE(isolate, copy);
-  return *copy;
+  return CreateArrayLiteralImpl(isolate, literals, literals_index, elements,
+                                ArrayLiteral::kShallowElements);
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_CreateSymbol) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 1);
   Handle<Object> name(args[0], isolate);
   RUNTIME_ASSERT(name->IsString() || name->IsUndefined());
   Symbol* symbol;
   MaybeObject* maybe = isolate->heap()->AllocateSymbol();
@@ skipping 14332 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