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8319423: Improve Year.isLeap by checking divisibility by 16

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Reviewed-by: naoto, rriggs
This commit is contained in:
Claes Redestad 2023-11-08 15:18:53 +00:00
parent 59e9981ec2
commit 7d25f1c6cb
6 changed files with 125 additions and 7 deletions
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7
src/java.base/share/classes/java/util/GregorianCalendar.java
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@ -826,7 +826,10 @@ public class GregorianCalendar extends Calendar {
}
if (year > gregorianCutoverYear) {
return (year%100 != 0) || (year%400 == 0); // Gregorian
// A multiple of 100, 200 and 300 is not divisible by 16, but 400 is.
// So for a year that's divisible by 4, checking that it's also divisible by 16
// is sufficient to determine it must be a leap year.
return (year & 15) == 0 || (year % 100 != 0); // Gregorian
}
if (year < gregorianCutoverYearJulian) {
return true; // Julian
@ -840,7 +843,7 @@ public class GregorianCalendar extends Calendar {
} else {
gregorian = year == gregorianCutoverYear;
}
return gregorian ? (year%100 != 0) || (year%400 == 0) : true;
return !gregorian || (year & 15) == 0 || (year % 100 != 0);
}
/**