Improve performance of Array.prototype.join and String.prototype.substring...

src/runtime.js

 // Copyright 2006-2008 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 409 matching lines @@
   // First check whether length is a positive Smi and args is an
   // array. This is the fast case. If this fails, we do the slow case
   // that takes care of more eventualities.
   if (IS_ARRAY(args)) {
     length = args.length;
     if (%_IsSmi(length) && length >= 0 && length < 0x800000 && IS_FUNCTION(this)) {
       return length;
     }
   }
 
-  length = (args == null) ? 0 : %ToUint32(args.length);
+  length = (args == null) ? 0 : TO_UINT32(args.length);
 
   // We can handle any number of apply arguments if the stack is
   // big enough, but sanity check the value to avoid overflow when
   // multiplying with pointer size.
   if (length > 0x800000) {
     throw %MakeRangeError('apply_overflow', [length]);
   }
 
   if (!IS_FUNCTION(this)) {
     throw %MakeTypeError('apply_non_function', [ %ToString(this), typeof this ]);
@@ skipping 162 matching lines @@
   throw %MakeTypeError('cannot_convert_to_primitive', []);
 }
 
 
 // NOTE: Setting the prototype for Array must take place as early as
 // possible due to code generation for array literals.  When
 // generating code for a array literal a boilerplate array is created
 // that is cloned when running the code.  It is essiential that the
 // boilerplate gets the right prototype.
 %FunctionSetPrototype($Array, new $Array(0));