Bug 585866 - Avoid unnecessary calls to YearFromTime(). r=jwalden.

js/src/jsdate.cpp

@@ -189,8 +189,23 @@ TimeWithinDay(jsdouble t)
     return result;
 }
 
-#define DaysInYear(y)   ((y) % 4 == 0 && ((y) % 100 || ((y) % 400 == 0))  \
+static inline bool
-                         ? 366 : 365)
+IsLeapYear(jsint year)
+{
+    return year % 4 == 0 && (year % 100 || (year % 400 == 0));
+}
+
+static inline jsint
+DaysInYear(jsint year) 
+{
+    return IsLeapYear(year) ? 366 : 365;
+}
+
+static inline jsint
+DaysInFebruary(jsint year)
+{
+    return IsLeapYear(year) ? 29 : 28;
+}
 
 /* math here has to be f.p, because we need
  *  floor((1968 - 1969) / 4) == -1
@@ -219,8 +234,6 @@ YearFromTime(jsdouble t)
     return y;
 }
 
-#define InLeapYear(t)   (JSBool) (DaysInYear(YearFromTime(t)) == 366)
-
 #define DayWithinYear(t, year) ((intN) (Day(t) - DayFromYear(year)))
 
 /*
@@ -237,7 +250,7 @@ static jsdouble firstDayOfMonth[2][13] = {
 static intN
 DaysInMonth(jsint year, jsint month)
 {
-    JSBool leap = (DaysInYear(year) == 366);
+    JSBool leap = IsLeapYear(year);
     intN result = intN(DayFromMonth(month, leap) - DayFromMonth(month-1, leap));
     return result;
 }
@@ -251,8 +264,7 @@ MonthFromTime(jsdouble t)
 
     if (d < (step = 31))
         return 0;
-    step += (InLeapYear(t) ? 29 : 28);
+    if (d < (step += DaysInFebruary(year)))
-    if (d < step)
         return 1;
     if (d < (step += 31))
         return 2;
@@ -285,8 +297,7 @@ DateFromTime(jsdouble t)
     if (d <= (next = 30))
         return d + 1;
     step = next;
-    next += (InLeapYear(t) ? 29 : 28);
+    if (d <= (next += DaysInFebruary(year)))
-    if (d <= next)
         return d - step;
     step = next;
     if (d <= (next += 31))
@@ -346,7 +357,7 @@ MakeDay(jsdouble year, jsdouble month, jsdouble date)
     if (month < 0)
         month += 12;
 
-    leap = (DaysInYear((jsint) year) == 366);
+    leap = IsLeapYear((jsint) year);
 
     yearday = floor(TimeFromYear(year) / msPerDay);
     monthday = DayFromMonth(month, leap);
@@ -381,16 +392,13 @@ static jsint
 EquivalentYearForDST(jsint year)
 {
     jsint day;
-    JSBool isLeapYear;
 
     day = (jsint) DayFromYear(year) + 4;
     day = day % 7;
     if (day < 0)
         day += 7;
 
-    isLeapYear = (DaysInYear(year) == 366);
+    return yearStartingWith[IsLeapYear(year)][day];
-
-    return yearStartingWith[isLeapYear][day];
 }
 
 /* LocalTZA gets set by js_InitDateClass() */