Experimental: port bleeding_edge r1276 (a grab bag of optimizations)...

src/v8natives.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
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 // ECMA-262 - 15.1.2.2
 function GlobalParseInt(string, radix) {
   if (radix === void 0) {
     radix = 0;
     // Some people use parseInt instead of Math.floor.  This
     // optimization makes parseInt on a Smi 12 times faster (60ns
     // vs 800ns).  The following optimization makes parseInt on a
     // non-Smi number 9 times faster (230ns vs 2070ns).  Together
     // they make parseInt on a string 1.4% slower (274ns vs 270ns).
     if (%_IsSmi(string)) return string;
-    if (IS_NUMBER(string)) {
-      if (string >= 0.01 && string < 1e9)
-        return $floor(string);
-      if (string <= -0.01 && string > -1e9)
-        return - $floor(-string);
+    if (IS_NUMBER(string) &&
+        ((string < -0.01 && -1e9 < string) ||
+            (0.01 < string && string < 1e9))) {
+      // Truncate number.
+      return string | 0;
     }
   } else {
     radix = TO_INT32(radix);
     if (!(radix == 0 || (2 <= radix && radix <= 36)))
       return $NaN;
   }
   return %StringParseInt(ToString(string), radix);
 }
 
 
@@ skipping 432 matching lines @@
 // ----------------------------------------------------------------------------
 
 function SetupFunction() {
   InstallFunctions($Function.prototype, DONT_ENUM, $Array(
     "toString", FunctionToString
   ));
 }
 
 SetupFunction();