Use Object::null_instance and Object::null_function and do not create Handles everytime.

runtime/vm/object.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/cpu.h"
@@ skipping 76 matching lines @@
 // These are initialized to a value that will force a illegal memory access if
 // they are being used.
 #if defined(RAW_NULL)
 #error RAW_NULL should not be defined.
 #endif
 #define RAW_NULL kHeapObjectTag
 Object* Object::null_object_ = NULL;
 Array* Object::null_array_ = NULL;
 String* Object::null_string_ = NULL;
 Instance* Object::null_instance_ = NULL;
+Function* Object::null_function_ = NULL;
 TypeArguments* Object::null_type_arguments_ = NULL;
 Array* Object::empty_array_ = NULL;
 Array* Object::zero_array_ = NULL;
 ObjectPool* Object::empty_object_pool_ = NULL;
 PcDescriptors* Object::empty_descriptors_ = NULL;
 LocalVarDescriptors* Object::empty_var_descriptors_ = NULL;
 ExceptionHandlers* Object::empty_exception_handlers_ = NULL;
 Array* Object::extractor_parameter_types_ = NULL;
 Array* Object::extractor_parameter_names_ = NULL;
 Instance* Object::sentinel_ = NULL;
@@ skipping 309 matching lines @@
     Smi::handle_vtable_ = fake_smi.vtable();
   }
 
   Heap* heap = isolate->heap();
 
   // Allocate the read only object handles here.
   null_object_ = Object::ReadOnlyHandle();
   null_array_ = Array::ReadOnlyHandle();
   null_string_ = String::ReadOnlyHandle();
   null_instance_ = Instance::ReadOnlyHandle();
+  null_function_ = Function::ReadOnlyHandle();
   null_type_arguments_ = TypeArguments::ReadOnlyHandle();
   empty_array_ = Array::ReadOnlyHandle();
   zero_array_ = Array::ReadOnlyHandle();
   empty_object_pool_ = ObjectPool::ReadOnlyHandle();
   empty_descriptors_ = PcDescriptors::ReadOnlyHandle();
   empty_var_descriptors_ = LocalVarDescriptors::ReadOnlyHandle();
   empty_exception_handlers_ = ExceptionHandlers::ReadOnlyHandle();
   extractor_parameter_types_ = Array::ReadOnlyHandle();
   extractor_parameter_names_ = Array::ReadOnlyHandle();
   sentinel_ = Instance::ReadOnlyHandle();
   transition_sentinel_ = Instance::ReadOnlyHandle();
   unknown_constant_ =  Instance::ReadOnlyHandle();
   non_constant_ =  Instance::ReadOnlyHandle();
   bool_true_ = Bool::ReadOnlyHandle();
   bool_false_ = Bool::ReadOnlyHandle();
   smi_illegal_cid_ = Smi::ReadOnlyHandle();
   snapshot_writer_error_ = LanguageError::ReadOnlyHandle();
   branch_offset_error_ = LanguageError::ReadOnlyHandle();
   vm_isolate_snapshot_object_table_ = Array::ReadOnlyHandle();
 
   *null_object_ = Object::null();
   *null_array_ = Array::null();
   *null_string_ = String::null();
   *null_instance_ = Instance::null();
+  *null_function_ = Function::null();
   *null_type_arguments_ = TypeArguments::null();
 
   // Initialize the empty and zero array handles to null_ in order to be able to
   // check if the empty and zero arrays were allocated (RAW_NULL is not
   // available).
   *empty_array_ = Array::null();
   *zero_array_ = Array::null();
 
   Class& cls = Class::Handle();
 
@@ skipping 302 matching lines @@
                                              Report::kBailout,
                                              Heap::kOld);
 
   ASSERT(!null_object_->IsSmi());
   ASSERT(!null_array_->IsSmi());
   ASSERT(null_array_->IsArray());
   ASSERT(!null_string_->IsSmi());
   ASSERT(null_string_->IsString());
   ASSERT(!null_instance_->IsSmi());
   ASSERT(null_instance_->IsInstance());
+  ASSERT(!null_function_->IsSmi());
+  ASSERT(null_function_->IsFunction());
   ASSERT(!null_type_arguments_->IsSmi());
   ASSERT(null_type_arguments_->IsTypeArguments());
   ASSERT(!empty_array_->IsSmi());
   ASSERT(empty_array_->IsArray());
   ASSERT(!zero_array_->IsSmi());
   ASSERT(zero_array_->IsArray());
   ASSERT(!empty_descriptors_->IsSmi());
   ASSERT(empty_descriptors_->IsPcDescriptors());
   ASSERT(!empty_var_descriptors_->IsSmi());
   ASSERT(empty_var_descriptors_->IsLocalVarDescriptors());
@@ skipping 6460 matching lines @@
   } else {
     result.SetOffset(0);
   }
   result.set_is_final(is_final);
   result.set_is_const(is_const);
   result.set_is_reflectable(is_reflectable);
   result.set_is_double_initialized(false);
   result.set_owner(owner);
   result.set_token_pos(token_pos);
   result.set_has_initializer(false);
-  result.set_initializer(Function::Handle());
+  result.set_initializer(Object::null_function());

[srdjan, 2015/08/13 15:49:01]

Is this necessary at all, since all data is initialized to Object::null() at
allocation.

[siva, 2015/08/13 16:52:02]

That is a good point, not sure why it was there in the first place, I should
other ::New functions to see if we have a pattern of people initializing with
null object.

   result.set_is_unboxing_candidate(true);
   result.set_guarded_cid(FLAG_use_field_guards ? kIllegalCid : kDynamicCid);
   result.set_is_nullable(FLAG_use_field_guards ? false : true);
   result.set_guarded_list_length_in_object_offset(Field::kUnknownLengthOffset);
   // Presently, we only attempt to remember the list length for final fields.
   if (is_final && FLAG_use_field_guards) {
     result.set_guarded_list_length(Field::kUnknownFixedLength);
   } else {
     result.set_guarded_list_length(Field::kNoFixedLength);
   }
@@ skipping 14105 matching lines @@
   return tag_label.ToCString();
 }
 
 
 void UserTag::PrintJSONImpl(JSONStream* stream, bool ref) const {
   Instance::PrintJSONImpl(stream, ref);
 }
 
 
 }  // namespace dart