Implement caching scheme for Date fields.

src/date.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 29 matching lines @@
 var $Date = global.Date;
 
 // Helper function to throw error.
 function ThrowDateTypeError() {
   throw new $TypeError('this is not a Date object.');
 }
 
 // ECMA 262 - 5.2
 function Modulo(value, remainder) {
   var mod = value % remainder;
-  // Guard against returning -0.
-  if (mod == 0) return 0;
-  return mod >= 0 ? mod : mod + remainder;
+  // All uses of this function for dates should produce a Smi.
+  return (mod >= 0 ? mod : mod + remainder) | 0;
 }
 
 
 function TimeWithinDay(time) {
   return Modulo(time, msPerDay);
 }
 
 
 // ECMA 262 - 15.9.1.3
 function DaysInYear(year) {
@@ skipping 385 matching lines @@
             0 <= TO_INTEGER(year) &&
             TO_INTEGER(year) <= 99) ? 1900 + TO_INTEGER(year) : year;
     var day = MakeDay(year, month, date);
     var time = MakeTime(hours, minutes, seconds, ms);
     value = TimeClip(UTC(MakeDate(day, time)));
   }
   SET_DATE_VALUE(this, value);
 });
 
 
+function ResetDate(date, time) {
+  SET_DATE_VALUE(date, time);
+  // Cache aggressively in case of a reset - we will typically use most fields.
+  if (NUMBER_IS_NAN(time)) {
+    SET_DATE_LOCAL(date, time);
+    SET_DATE_YEAR(date, time);
+    SET_DATE_MONTH(date, time);
+    SET_DATE_DAY(date, time);
+    SET_DATE_HOUR(date, time);
+    SET_DATE_MIN(date, time);
+    SET_DATE_SEC(date, time);
+    SET_DATE_WEEKDAY(date, time);
+  } else {
+    var local = LocalTimeNoCheck(time);
+    SET_DATE_LOCAL(date, local_time_offset);
+    SET_DATE_YEAR(date, YearFromTime(local));
+    SET_DATE_MONTH(date, MonthFromTime(local));
+    SET_DATE_DAY(date, DateFromTime(local));
+    SET_DATE_HOUR(date, HOUR_FROM_TIME(local));
+    SET_DATE_MIN(date, MIN_FROM_TIME(local));
+    SET_DATE_SEC(date, SEC_FROM_TIME(local));
+    SET_DATE_WEEKDAY(date, WeekDay(local));
+  }
+
+  return time;
+}
+
+
 %FunctionSetPrototype($Date, new $Date($NaN));
 
 
 var WeekDays = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'];
 var Months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
               'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];
 
 
 function TwoDigitString(value) {
   return value < 10 ? "0" + value : "" + value;
@@ skipping 163 matching lines @@
 
 
 // ECMA 262 - 15.9.5.9
 function DateGetTime() {
   return DATE_VALUE(this);
 }
 
 
 // ECMA 262 - 15.9.5.10
 function DateGetFullYear() {
-  var t = DATE_VALUE(this);
-  if (NUMBER_IS_NAN(t)) return t;
+  var t = DATE_YEAR(this);
+  if (!IS_UNDEFINED(t) && DATE_LOCAL(this) === local_time_offset) return t;
+  t = DATE_VALUE_UNCHECKED(this);
   var cache = Date_cache;
   if (cache.time === t) return cache.year;
-  return YearFromTime(LocalTimeNoCheck(t));
+  t = LocalTimeNoCheck(t);
+  if (!NUMBER_IS_NAN(t)) t = YearFromTime(t);
+  return t;
 }
 
 
 // ECMA 262 - 15.9.5.11
 function DateGetUTCFullYear() {
   var t = DATE_VALUE(this);
   if (NUMBER_IS_NAN(t)) return t;
   return YearFromTime(t);
 }
 
 
 // ECMA 262 - 15.9.5.12
 function DateGetMonth() {
-  var t = DATE_VALUE(this);
-  if (NUMBER_IS_NAN(t)) return t;
-  return MonthFromTime(LocalTimeNoCheck(t));
+  var t = DATE_MONTH(this);
+  if (!IS_UNDEFINED(t) && DATE_LOCAL(this) === local_time_offset) return t;
+  ResetDate(this, DATE_VALUE_UNCHECKED(this));
+  return DATE_MONTH(this);
 }
 
 
 // ECMA 262 - 15.9.5.13
 function DateGetUTCMonth() {
   var t = DATE_VALUE(this);
   if (NUMBER_IS_NAN(t)) return t;
   return MonthFromTime(t);
 }
 
 
 // ECMA 262 - 15.9.5.14
 function DateGetDate() {
-  var t = DATE_VALUE(this);
-  if (NUMBER_IS_NAN(t)) return t;
-  return DateFromTime(LocalTimeNoCheck(t));
+  var t = DATE_DAY(this);
+  if (!IS_UNDEFINED(t) && DATE_LOCAL(this) === local_time_offset) return t;
+  ResetDate(this, DATE_VALUE_UNCHECKED(this));
+  return DATE_DAY(this);
 }
 
 
 // ECMA 262 - 15.9.5.15
 function DateGetUTCDate() {
   var t = DATE_VALUE(this);
   return NAN_OR_DATE_FROM_TIME(t);
 }
 
 
 // ECMA 262 - 15.9.5.16
 function DateGetDay() {
-  var t = DATE_VALUE(this);
-  if (NUMBER_IS_NAN(t)) return t;
-  return WeekDay(LocalTimeNoCheck(t));
+  var t = DATE_WEEKDAY(this);
+  if (!IS_UNDEFINED(t) && DATE_LOCAL(this) === local_time_offset) return t;
+  ResetDate(this, DATE_VALUE_UNCHECKED(this));
+  return DATE_WEEKDAY(this);
 }
 
 
 // ECMA 262 - 15.9.5.17
 function DateGetUTCDay() {
   var t = DATE_VALUE(this);
   if (NUMBER_IS_NAN(t)) return t;
   return WeekDay(t);
 }
 
 
 // ECMA 262 - 15.9.5.18
 function DateGetHours() {
-  var t = DATE_VALUE(this);
-  if (NUMBER_IS_NAN(t)) return t;
-  return HOUR_FROM_TIME(LocalTimeNoCheck(t));
+  var t = DATE_HOUR(this);
+  if (!IS_UNDEFINED(t) && DATE_LOCAL(this) === local_time_offset) return t;
+  ResetDate(this, DATE_VALUE_UNCHECKED(this));
+  return DATE_HOUR(this);
 }
 
 
 // ECMA 262 - 15.9.5.19
 function DateGetUTCHours() {
   var t = DATE_VALUE(this);
   if (NUMBER_IS_NAN(t)) return t;
   return HOUR_FROM_TIME(t);
 }
 
 
 // ECMA 262 - 15.9.5.20
 function DateGetMinutes() {
-  var t = DATE_VALUE(this);
-  if (NUMBER_IS_NAN(t)) return t;
-  return MIN_FROM_TIME(LocalTimeNoCheck(t));
+  var t = DATE_MIN(this);
+  if (!IS_UNDEFINED(t) && DATE_LOCAL(this) === local_time_offset) return t;
+  ResetDate(this, DATE_VALUE_UNCHECKED(this));
+  return DATE_MIN(this);
 }
 
 
 // ECMA 262 - 15.9.5.21
 function DateGetUTCMinutes() {
   var t = DATE_VALUE(this);
   return NAN_OR_MIN_FROM_TIME(t);
 }
 
 
 // ECMA 262 - 15.9.5.22
 function DateGetSeconds() {
-  var t = DATE_VALUE(this);
-  if (NUMBER_IS_NAN(t)) return t;
-  return SEC_FROM_TIME(LocalTimeNoCheck(t));
+  var t = DATE_SEC(this);
+  if (!IS_UNDEFINED(t) && DATE_LOCAL(this) === local_time_offset) return t;
+  ResetDate(this, DATE_VALUE_UNCHECKED(this));
+  return DATE_SEC(this);
 }
 
 
 // ECMA 262 - 15.9.5.23
 function DateGetUTCSeconds() {
   var t = DATE_VALUE(this);
   return NAN_OR_SEC_FROM_TIME(t);
 }
 
 
@@ skipping 16 matching lines @@
 function DateGetTimezoneOffset() {
   var t = DATE_VALUE(this);
   if (NUMBER_IS_NAN(t)) return t;
   return (t - LocalTimeNoCheck(t)) / msPerMinute;
 }
 
 
 // ECMA 262 - 15.9.5.27
 function DateSetTime(ms) {
   if (!IS_DATE(this)) ThrowDateTypeError();
-  return SET_DATE_VALUE(this, TimeClip(ToNumber(ms)));
+  return ResetDate(this, TimeClip(ToNumber(ms)));
 }
 
 
 // ECMA 262 - 15.9.5.28
 function DateSetMilliseconds(ms) {
   var t = LocalTime(DATE_VALUE(this));
   ms = ToNumber(ms);
   var time = MakeTime(HOUR_FROM_TIME(t),
                       MIN_FROM_TIME(t),
                       SEC_FROM_TIME(t),
                       ms);
-  return SET_DATE_VALUE(this, TimeClip(UTC(MakeDate(DAY(t), time))));
+  return ResetDate(this, TimeClip(UTC(MakeDate(DAY(t), time))));
 }
 
 
 // ECMA 262 - 15.9.5.29
 function DateSetUTCMilliseconds(ms) {
   var t = DATE_VALUE(this);
   ms = ToNumber(ms);
   var time = MakeTime(HOUR_FROM_TIME(t),
                       MIN_FROM_TIME(t),
                       SEC_FROM_TIME(t),
                       ms);
-  return SET_DATE_VALUE(this, TimeClip(MakeDate(DAY(t), time)));
+  return ResetDate(this, TimeClip(MakeDate(DAY(t), time)));
 }
 
 
 // ECMA 262 - 15.9.5.30
 function DateSetSeconds(sec, ms) {
   var t = LocalTime(DATE_VALUE(this));
   sec = ToNumber(sec);
   ms = %_ArgumentsLength() < 2 ? NAN_OR_MS_FROM_TIME(t) : ToNumber(ms);
   var time = MakeTime(HOUR_FROM_TIME(t), MIN_FROM_TIME(t), sec, ms);
-  return SET_DATE_VALUE(this, TimeClip(UTC(MakeDate(DAY(t), time))));
+  return ResetDate(this, TimeClip(UTC(MakeDate(DAY(t), time))));
 }
 
 
 // ECMA 262 - 15.9.5.31
 function DateSetUTCSeconds(sec, ms) {
   var t = DATE_VALUE(this);
   sec = ToNumber(sec);
   ms = %_ArgumentsLength() < 2 ? NAN_OR_MS_FROM_TIME(t) : ToNumber(ms);
   var time = MakeTime(HOUR_FROM_TIME(t), MIN_FROM_TIME(t), sec, ms);
-  return SET_DATE_VALUE(this, TimeClip(MakeDate(DAY(t), time)));
+  return ResetDate(this, TimeClip(MakeDate(DAY(t), time)));
 }
 
 
 // ECMA 262 - 15.9.5.33
 function DateSetMinutes(min, sec, ms) {
   var t = LocalTime(DATE_VALUE(this));
   min = ToNumber(min);
   var argc = %_ArgumentsLength();
   sec = argc < 2 ? NAN_OR_SEC_FROM_TIME(t) : ToNumber(sec);
   ms = argc < 3 ? NAN_OR_MS_FROM_TIME(t) : ToNumber(ms);
   var time = MakeTime(HOUR_FROM_TIME(t), min, sec, ms);
-  return SET_DATE_VALUE(this, TimeClip(UTC(MakeDate(DAY(t), time))));
+  return ResetDate(this, TimeClip(UTC(MakeDate(DAY(t), time))));
 }
 
 
 // ECMA 262 - 15.9.5.34
 function DateSetUTCMinutes(min, sec, ms) {
   var t = DATE_VALUE(this);
   min = ToNumber(min);
   var argc = %_ArgumentsLength();
   sec = argc < 2 ? NAN_OR_SEC_FROM_TIME(t) : ToNumber(sec);
   ms = argc < 3 ? NAN_OR_MS_FROM_TIME(t) : ToNumber(ms);
   var time = MakeTime(HOUR_FROM_TIME(t), min, sec, ms);
-  return SET_DATE_VALUE(this, TimeClip(MakeDate(DAY(t), time)));
+  return ResetDate(this, TimeClip(MakeDate(DAY(t), time)));
 }
 
 
 // ECMA 262 - 15.9.5.35
 function DateSetHours(hour, min, sec, ms) {
   var t = LocalTime(DATE_VALUE(this));
   hour = ToNumber(hour);
   var argc = %_ArgumentsLength();
   min = argc < 2 ? NAN_OR_MIN_FROM_TIME(t) : ToNumber(min);
   sec = argc < 3 ? NAN_OR_SEC_FROM_TIME(t) : ToNumber(sec);
   ms = argc < 4 ? NAN_OR_MS_FROM_TIME(t) : ToNumber(ms);
   var time = MakeTime(hour, min, sec, ms);
-  return SET_DATE_VALUE(this, TimeClip(UTC(MakeDate(DAY(t), time))));
+  return ResetDate(this, TimeClip(UTC(MakeDate(DAY(t), time))));
 }
 
 
 // ECMA 262 - 15.9.5.34
 function DateSetUTCHours(hour, min, sec, ms) {
   var t = DATE_VALUE(this);
   hour = ToNumber(hour);
   var argc = %_ArgumentsLength();
   min = argc < 2 ? NAN_OR_MIN_FROM_TIME(t) : ToNumber(min);
   sec = argc < 3 ? NAN_OR_SEC_FROM_TIME(t) : ToNumber(sec);
   ms = argc < 4 ? NAN_OR_MS_FROM_TIME(t) : ToNumber(ms);
   var time = MakeTime(hour, min, sec, ms);
-  return SET_DATE_VALUE(this, TimeClip(MakeDate(DAY(t), time)));
+  return ResetDate(this, TimeClip(MakeDate(DAY(t), time)));
 }
 
 
 // ECMA 262 - 15.9.5.36
 function DateSetDate(date) {
   var t = LocalTime(DATE_VALUE(this));
   date = ToNumber(date);
   var day = MakeDay(YearFromTime(t), MonthFromTime(t), date);
-  return SET_DATE_VALUE(this, TimeClip(UTC(MakeDate(day, TimeWithinDay(t)))));
+  return ResetDate(this, TimeClip(UTC(MakeDate(day, TimeWithinDay(t)))));
 }
 
 
 // ECMA 262 - 15.9.5.37
 function DateSetUTCDate(date) {
   var t = DATE_VALUE(this);
   date = ToNumber(date);
   var day = MakeDay(YearFromTime(t), MonthFromTime(t), date);
-  return SET_DATE_VALUE(this, TimeClip(MakeDate(day, TimeWithinDay(t))));
+  return ResetDate(this, TimeClip(MakeDate(day, TimeWithinDay(t))));
 }
 
 
 // ECMA 262 - 15.9.5.38
 function DateSetMonth(month, date) {
   var t = LocalTime(DATE_VALUE(this));
   month = ToNumber(month);
   date = %_ArgumentsLength() < 2 ? NAN_OR_DATE_FROM_TIME(t) : ToNumber(date);
   var day = MakeDay(YearFromTime(t), month, date);
-  return SET_DATE_VALUE(this, TimeClip(UTC(MakeDate(day, TimeWithinDay(t)))));
+  return ResetDate(this, TimeClip(UTC(MakeDate(day, TimeWithinDay(t)))));
 }
 
 
 // ECMA 262 - 15.9.5.39
 function DateSetUTCMonth(month, date) {
   var t = DATE_VALUE(this);
   month = ToNumber(month);
   date = %_ArgumentsLength() < 2 ? NAN_OR_DATE_FROM_TIME(t) : ToNumber(date);
   var day = MakeDay(YearFromTime(t), month, date);
-  return SET_DATE_VALUE(this, TimeClip(MakeDate(day, TimeWithinDay(t))));
+  return ResetDate(this, TimeClip(MakeDate(day, TimeWithinDay(t))));
 }
 
 
 // ECMA 262 - 15.9.5.40
 function DateSetFullYear(year, month, date) {
   var t = DATE_VALUE(this);
   t = NUMBER_IS_NAN(t) ? 0 : LocalTimeNoCheck(t);
   year = ToNumber(year);
   var argc = %_ArgumentsLength();
   month = argc < 2 ? MonthFromTime(t) : ToNumber(month);
   date = argc < 3 ? DateFromTime(t) : ToNumber(date);
   var day = MakeDay(year, month, date);
-  return SET_DATE_VALUE(this, TimeClip(UTC(MakeDate(day, TimeWithinDay(t)))));
+  return ResetDate(this, TimeClip(UTC(MakeDate(day, TimeWithinDay(t)))));
 }
 
 
 // ECMA 262 - 15.9.5.41
 function DateSetUTCFullYear(year, month, date) {
   var t = DATE_VALUE(this);
   if (NUMBER_IS_NAN(t)) t = 0;
   var argc = %_ArgumentsLength();
   year = ToNumber(year);
   month = argc < 2 ? MonthFromTime(t) : ToNumber(month);
   date = argc < 3 ? DateFromTime(t) : ToNumber(date);
   var day = MakeDay(year, month, date);
-  return SET_DATE_VALUE(this, TimeClip(MakeDate(day, TimeWithinDay(t))));
+  return ResetDate(this, TimeClip(MakeDate(day, TimeWithinDay(t))));
 }
 
 
 // ECMA 262 - 15.9.5.42
 function DateToUTCString() {
   var t = DATE_VALUE(this);
   if (NUMBER_IS_NAN(t)) return kInvalidDate;
   // Return UTC string of the form: Sat, 31 Jan 1970 23:00:00 GMT
   return WeekDays[WeekDay(t)] + ', '
       + TwoDigitString(DateFromTime(t)) + ' '
       + Months[MonthFromTime(t)] + ' '
       + YearFromTime(t) + ' '
       + TimeString(t) + ' GMT';
 }
 
 
 // ECMA 262 - B.2.4
 function DateGetYear() {
   var t = DATE_VALUE(this);
   if (NUMBER_IS_NAN(t)) return $NaN;
   return YearFromTime(LocalTimeNoCheck(t)) - 1900;
 }
 
 
 // ECMA 262 - B.2.5
 function DateSetYear(year) {
   var t = LocalTime(DATE_VALUE(this));
   if (NUMBER_IS_NAN(t)) t = 0;
   year = ToNumber(year);
-  if (NUMBER_IS_NAN(year)) return SET_DATE_VALUE(this, $NaN);
+  if (NUMBER_IS_NAN(year)) return ResetDate(this, $NaN);
   year = (0 <= TO_INTEGER(year) && TO_INTEGER(year) <= 99)
       ? 1900 + TO_INTEGER(year) : year;
   var day = MakeDay(year, MonthFromTime(t), DateFromTime(t));
-  return SET_DATE_VALUE(this, TimeClip(UTC(MakeDate(day, TimeWithinDay(t)))));
+  return ResetDate(this, TimeClip(UTC(MakeDate(day, TimeWithinDay(t)))));
 }
 
 
 // ECMA 262 - B.2.6
 //
 // Notice that this does not follow ECMA 262 completely.  ECMA 262
 // says that toGMTString should be the same Function object as
 // toUTCString.  JSC does not do this, so for compatibility we do not
 // do that either.  Instead, we create a new function whose name
 // property will return toGMTString.
@@ skipping 137 matching lines @@
     "toGMTString", DateToGMTString,
     "toUTCString", DateToUTCString,
     "getYear", DateGetYear,
     "setYear", DateSetYear,
     "toISOString", DateToISOString,
     "toJSON", DateToJSON
   ));
 }
 
 SetUpDate();