Skip expensive hasInstance() type-checks in overloads

Source/bindings/scripts/v8_methods.py

 # Copyright (C) 2013 Google Inc. 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
@@ skipping 179 matching lines @@
     extended_attributes = argument.extended_attributes
     idl_type = argument.idl_type
     this_cpp_value = cpp_value(interface, method, index)
     is_variadic_wrapper_type = argument.is_variadic and idl_type.is_wrapper_type
 
     type_checking_interface = (
         (has_extended_attribute_value(interface, 'TypeChecking', 'Interface') or
          has_extended_attribute_value(method, 'TypeChecking', 'Interface')) and
         idl_type.is_wrapper_type)
 
-    type_checked = (type_checking_interface and
-                    # These allow null and undefined values, so a type-check is still required.
-                    not idl_type.is_nullable and
-                    not (argument.is_optional and
-                         'Default' in extended_attributes))
-
     if ('ImplementedInPrivateScript' in extended_attributes and
         not idl_type.is_wrapper_type and
         not idl_type.is_basic_type):
         raise Exception('Private scripts supports only primitive types and DOM wrappers.')
 
+    convert_v8_value_to_local_cpp_value = v8_value_to_local_cpp_value(
+        argument, index, return_promise=method.returns_promise)
+
+    # "Unsafe" conversion, to use when the argument's type has already been
+    # checked.  Set to None if same as regular conversion, to avoid emitting
+    # duplicate copies of the same code.
+    convert_v8_value_to_local_cpp_value_without_type_check = v8_value_to_local_cpp_value(
+        argument, index, needs_type_check=False, return_promise=method.returns_promise)
+    if convert_v8_value_to_local_cpp_value == convert_v8_value_to_local_cpp_value_without_type_check:
+        convert_v8_value_to_local_cpp_value_without_type_check = None
+
     default_cpp_value = argument.default_cpp_value
     return {
         'cpp_type': idl_type.cpp_type_args(extended_attributes=extended_attributes,
                                            raw_type=True,
                                            used_as_variadic_argument=argument.is_variadic),
         'cpp_value': this_cpp_value,
         # FIXME: check that the default value's type is compatible with the argument's
         'default_value': default_cpp_value,
         'enum_validation_expression': idl_type.enum_validation_expression,
         'handle': '%sHandle' % argument.name,
@@ skipping 14 matching lines @@
         'is_nullable': idl_type.is_nullable,
         'is_optional': argument.is_optional,
         'is_variadic_wrapper_type': is_variadic_wrapper_type,
         'is_wrapper_type': idl_type.is_wrapper_type,
         'name': argument.name,
         'private_script_cpp_value_to_v8_value': idl_type.cpp_value_to_v8_value(
             argument.name, isolate='scriptState->isolate()',
             creation_context='scriptState->context()->Global()'),
         'v8_set_return_value': v8_set_return_value(interface.name, method, this_cpp_value),
         'v8_set_return_value_for_main_world': v8_set_return_value(interface.name, method, this_cpp_value, for_main_world=True),
-        'v8_value_to_local_cpp_value': v8_value_to_local_cpp_value(argument, index, type_checked, return_promise=method.returns_promise),
+        'v8_value_to_local_cpp_value': convert_v8_value_to_local_cpp_value,
+        'v8_value_to_local_cpp_value_without_type_check': convert_v8_value_to_local_cpp_value_without_type_check,
         'vector_type': v8_types.cpp_ptr_type('Vector', 'HeapVector', idl_type.gc_type),
     }
 
 
 def argument_declarations_for_private_script(interface, method):
     argument_declarations = ['LocalFrame* frame']
     argument_declarations.append('%s* holderImpl' % interface.name)
     argument_declarations.extend(['%s %s' % (argument.idl_type.cpp_type_args(
         used_as_rvalue_type=True), argument.name) for argument in method.arguments])
     if method.idl_type.name != 'void':
@@ skipping 107 matching lines @@
 
     if return_promise:
         suffix += '_PROMISE'
         macro_args.extend(['info', 'ScriptState::current(info.GetIsolate())'])
 
     suffix += '_INTERNAL'
 
     return '%s%s(%s)' % (macro, suffix, ', '.join(macro_args))
 
 
-def v8_value_to_local_cpp_value(argument, index, type_checked, return_promise=False):
+def v8_value_to_local_cpp_value(argument, index, needs_type_check=True, return_promise=False):
     extended_attributes = argument.extended_attributes
     idl_type = argument.idl_type
     name = argument.name
     if argument.is_variadic:
         return v8_value_to_local_cpp_variadic_value(argument, index, return_promise)
-    return idl_type.v8_value_to_local_cpp_value(extended_attributes, 'info[%s]' % index,
-                                                name, needs_type_check=not type_checked, index=index, declare_variable=False, return_promise=return_promise)
+    return idl_type.v8_value_to_local_cpp_value(
+        extended_attributes, 'info[%s]' % index, name, needs_type_check=needs_type_check,
+        index=index, declare_variable=False, return_promise=return_promise)
 
 
 ################################################################################
 # Auxiliary functions
 ################################################################################
 
 # [NotEnumerable]
 def property_attributes(method):
     extended_attributes = method.extended_attributes
     property_attributes_list = []
@@ skipping 58 matching lines @@
 
 IdlOperation.returns_promise = property(method_returns_promise)
 
 
 def argument_conversion_needs_exception_state(method, argument):
     idl_type = argument.idl_type
     return (idl_type.v8_conversion_needs_exception_state or
             argument.is_variadic or
             (method.returns_promise and (idl_type.is_string_type or
                                          idl_type.is_enum)))