Hydrogen array constructor cleanup and improvements

src/bootstrapper.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 848 matching lines @@
                         isolate->initial_object_prototype(),
                         Builtins::kArrayCode, true, true);
     array_function->shared()->DontAdaptArguments();
     array_function->shared()->set_function_data(Smi::FromInt(kArrayCode));
 
     // This seems a bit hackish, but we need to make sure Array.length
     // is 1.
     array_function->shared()->set_length(1);
 
     Handle<Map> initial_map(array_function->initial_map());
+
+    // This assert protects an optimization in
+    // HGraphBuilder::JSArrayBuilder::EmitMapCode()
+    ASSERT(initial_map->elements_kind() == GetInitialFastElementsKind());
+
     Handle<DescriptorArray> array_descriptors(
         factory->NewDescriptorArray(0, 1));
     DescriptorArray::WhitenessWitness witness(*array_descriptors);
 
     Handle<Foreign> array_length(factory->NewForeign(&Accessors::ArrayLength));
     PropertyAttributes attribs = static_cast<PropertyAttributes>(
         DONT_ENUM | DONT_DELETE);
     initial_map->set_instance_descriptors(*array_descriptors);
 
     {  // Add length.
@@ skipping 1761 matching lines @@
   return from + sizeof(NestingCounterType);
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   ASSERT(!IsActive());
 }
 
 } }  // namespace v8::internal