Addressed perf regression in Browsermark2.0 array blur test

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index b5a108159ad81bac2a1ef8a7e28a287751e712c0..ba0bbc3963dafd02b1ce32c59c33220d77687043 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -554,24 +554,63 @@ static Handle<AllocationSite> GetLiteralAllocationSite(
 }
 
 
+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() == 3);
+  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);
 
-  Handle<AllocationSite> site = GetLiteralAllocationSite(isolate, literals,
-      literals_index, elements);
-  RETURN_IF_EMPTY_HANDLE(isolate, site);
+  return CreateArrayLiteralImpl(isolate, literals, literals_index, elements,
+                                flags);
+}
 
-  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;
+
+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);
+
+  return CreateArrayLiteralImpl(isolate, literals, literals_index, elements,
+                                ArrayLiteral::kShallowElements);
 }