Canvas2D Performance: fix the bottleneck of hasInstance during JS binding -- overloading

Source/bindings/scripts/v8_interface.py

 # Copyright (C) 2013 Google Inc. All rights reserved.
 # coding=utf-8
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@@ skipping 735 matching lines @@
     # • an interface type that V implements
     # (Unlike most of these tests, this can return multiple methods, since we
     #  test if it implements an interface. Thus we need a for loop, not a next.)
     # (We distinguish wrapper types from built-in interface types.)
     for idl_type, method in ((idl_type, method)
                              for idl_type, method in idl_types_methods
                              if idl_type.is_wrapper_type):
         test = 'V8{idl_type}::hasInstance({cpp_value}, info.GetIsolate())'.format(idl_type=idl_type.base_type, cpp_value=cpp_value)
         yield test, method
 
+    for argument, method in arguments_methods:

[Jens Widell, 2014/10/10 10:14:53]

Could you add a comment before this code explaining what we're doing, and
specifically under what circumstances it's safe/not safe to say "type already
checked"?

[yunchao, 2014/10/10 11:40:48]

Done.

+        if argument['idl_type_object'].is_wrapper_type and method['number_of_required_arguments'] == method['number_of_arguments']:

[Jens Widell, 2014/10/10 10:14:53]

You can use argument['is_wrapper_type'] here instead.

[yunchao, 2014/10/10 11:40:48]

Acknowledged.

+            argument['type_checked_already'] = True
+
+
     # 8. Otherwise: if V is any kind of object except for a native Date object,
     # a native RegExp object, and there is an entry in S that has one of the
     # following types at position i of its type list,
     # • an array type
     # • a sequence type
     # ...
     # • a dictionary
     #
     # FIXME:
     # We don't strictly follow the algorithm here. The algorithm says "remove
@@ skipping 139 matching lines @@
                 'ConstructorCallWith', 'Document'),
         'is_call_with_execution_context':
             # [ConstructorCallWith=ExecutionContext]
             has_extended_attribute_value(interface,
                 'ConstructorCallWith', 'ExecutionContext'),
         'is_constructor': True,
         'is_named_constructor': False,
         'is_raises_exception': is_constructor_raises_exception,
         'number_of_required_arguments':
             number_of_required_arguments(constructor),
+        'number_of_arguments': len(constructor.arguments),

[Jens Widell, 2014/10/10 10:14:53]

Move up a bit; the list should be sorted alphabetically.

[yunchao, 2014/10/10 11:40:48]

Done.

     }
 
 
 # [NamedConstructor]
 def named_constructor_context(interface):
     extended_attributes = interface.extended_attributes
     if 'NamedConstructor' not in extended_attributes:
         return None
     # FIXME: parser should return named constructor separately;
     # included in constructors (and only name stored in extended attribute)
@@ skipping 208 matching lines @@
         deleter = next(
             method
             for method in interface.operations
             if ('deleter' in method.specials and
                 len(method.arguments) == 1 and
                 str(method.arguments[0].idl_type) == 'DOMString'))
     except StopIteration:
         return None
 
     return property_deleter(deleter)