Create missing boilerplate for array literals instead of deoptimizing

src/hydrogen.cc

 // Copyright 2011 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 3449 matching lines @@
   ASSERT(!HasStackOverflow());
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
   ZoneList<Expression*>* subexprs = expr->values();
   int length = subexprs->length();
   HValue* context = environment()->LookupContext();
 
   Handle<FixedArray> literals(environment()->closure()->literals());
   Handle<Object> raw_boilerplate(literals->get(expr->literal_index()));
 
-  // For now, no boilerplate causes a deopt.
   if (raw_boilerplate->IsUndefined()) {
-    AddInstruction(new(zone()) HSoftDeoptimize);
-    return ast_context()->ReturnValue(graph()->GetConstantUndefined());
+    raw_boilerplate = Runtime::CreateArrayLiteralBoilerplate(
+        isolate(), literals, expr->constant_elements());
+    if (raw_boilerplate.is_null()) {
+      return Bailout("array boilerplate creation failed");
+    }
+    literals->set(expr->literal_index(), *raw_boilerplate);
+    if (JSObject::cast(*raw_boilerplate)->elements()->map() ==
+        isolate()->heap()->fixed_cow_array_map()) {
+      isolate()->counters()->cow_arrays_created_runtime()->Increment();
+    }
   }
 
-  Handle<JSObject> boilerplate(Handle<JSObject>::cast(raw_boilerplate));
-  ElementsKind boilerplate_elements_kind = boilerplate->GetElementsKind();
+  Handle<JSObject> boilerplate = Handle<JSObject>::cast(raw_boilerplate);
+  ElementsKind boilerplate_elements_kind =
+        Handle<JSObject>::cast(boilerplate)->GetElementsKind();
 
   HArrayLiteral* literal = new(zone()) HArrayLiteral(
       context,
       boilerplate,
       length,
       expr->literal_index(),
       expr->depth());
 
   // The array is expected in the bailout environment during computation
   // of the property values and is the value of the entire expression.
@@ skipping 3778 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify(false);  // No full verify.
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal