Fix issue 397 and issue 399.

src/date-delay.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 @@
 
 
 // ECMA 262 - 15.9.1.14
 function TimeClip(time) {
   if (!$isFinite(time)) return $NaN;
   if ($abs(time) > 8.64E15) return $NaN;
   return TO_INTEGER(time);
 }
 
 
+// The Date cache is used to limit the cost of parsing the same Date
+// strings over and over again.
+var Date_cache = {
+  // Cached time value.
+  time: $NaN,
+  // Cached year. Only valid when the time matches cached time.

[bak, 2009/07/07 11:54:02]

Year when interpreting time as a local time.

+  year: $NaN,
+  // String input for which the cached time is valid.
+  string: null
+};
+
+
 %SetCode($Date, function(year, month, date, hours, minutes, seconds, ms) {
   if (!%_IsConstructCall()) {
     // ECMA 262 - 15.9.2
     return (new $Date()).toString();
   }
 
   // ECMA 262 - 15.9.3
   var argc = %_ArgumentsLength();
   var value;
   if (argc == 0) {
     value = %DateCurrentTime();
 
   } else if (argc == 1) {
     if (IS_NUMBER(year)) {
       value = TimeClip(year);
+
+    } else if (IS_STRING(year)) {
+      // Probe the Date cache. If we already have a time value for the
+      // given time, we re-use that instead of parsing the string again.
+      var cache = Date_cache;
+      if (cache.string === year) {
+        value = cache.time;
+      } else {
+        value = DateParse(year);
+        cache.time = value;
+        cache.year = YearFromTime(LocalTimeNoCheck(value));
+        cache.string = year;
+      }
+
     } else {
       // According to ECMA 262, no hint should be given for this
       // conversion. However, ToPrimitive defaults to STRING_HINT for
       // Date objects which will lose precision when the Date
       // constructor is called with another Date object as its
       // argument. We therefore use NUMBER_HINT for the conversion,
       // which is the default for everything else than Date objects.
       // This makes us behave like KJS and SpiderMonkey.
       var time = ToPrimitive(year, NUMBER_HINT);
       value = IS_STRING(time) ? DateParse(time) : TimeClip(ToNumber(time));
@@ skipping 75 matching lines @@
 function GetUTCHoursFrom(aDate) {
   var t = DATE_VALUE(aDate);
   if (NUMBER_IS_NAN(t)) return t;
   return HourFromTime(t);
 }
 
 
 function GetFullYearFrom(aDate) {
   var t = DATE_VALUE(aDate);
   if (NUMBER_IS_NAN(t)) return t;
-  // Ignore the DST offset for year computations.
-  return YearFromTime(t + local_time_offset);
+  var cache = Date_cache;
+  if (cache.time === t) return cache.year;
+  return YearFromTime(LocalTimeNoCheck(t));
 }
 
 
 function GetUTCFullYearFrom(aDate) {
   var t = DATE_VALUE(aDate);
   if (NUMBER_IS_NAN(t)) return t;
   return YearFromTime(t);
 }
 
 
@@ skipping 75 matching lines @@
   return gmt + ' (' +  LocalTimezone(time) + ')';
 }
 
 
 function DatePrintString(time) {
   return DateString(time) + ' ' + TimeString(time);
 }
 
 // -------------------------------------------------------------------
 
-// Reused output buffer.
+// Reused output buffer. Used when parsing date strings.
 var parse_buffer = $Array(7);
 
 // ECMA 262 - 15.9.4.2
 function DateParse(string) {
   var arr = %DateParseString(ToString(string), parse_buffer);
   if (IS_NULL(arr)) return $NaN;
 
   var day = MakeDay(arr[0], arr[1], arr[2]);
   var time = MakeTime(arr[3], arr[4], arr[5], 0);
   var date = MakeDate(day, time);
@@ skipping 482 matching lines @@
     "toGMTString", DateToGMTString,
     "toUTCString", DateToUTCString,
     "getYear", DateGetYear,
     "setYear", DateSetYear,
     "toISOString", DateToISOString,
     "toJSON", DateToJSON
   ));
 }
 
 SetupDate();