Small optimizations to parseInt

src/v8natives.js

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
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 // 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 77 matching lines @@
 // ECMA-262 - 15.1.2.2
 function GlobalParseInt(string, radix) {
   if (radix === void 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) &&
-        ((string < -0.01 && -1e9 < string) ||
-            (0.01 < string && string < 1e9))) {
+        ((0.01 < string && string < 1e9) ||
+            (string < -0.01 && -1e9 < string))) {

[Lasse Reichstein, 2009/11/11 11:43:34]

Just for readability, could you swap the terms of the last '&&'?
It's probably safe to assume that positive numbers outweigh negative numbers as
argument to parseInt, so it's a fine optimization (although I doubt it will make
a measureable difference in practice).

       // Truncate number.
       return string | 0;
     }
     radix = 0;
   } else {
     radix = TO_INT32(radix);
     if (!(radix == 0 || (2 <= radix && radix <= 36)))
       return $NaN;
   }
   return %StringParseInt(ToString(string), radix);
@@ skipping 463 matching lines @@
 
 // ----------------------------------------------------------------------------
 
 function SetupFunction() {
   InstallFunctions($Function.prototype, DONT_ENUM, $Array(
     "toString", FunctionToString
   ));
 }
 
 SetupFunction();