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Avoid unnecessary division in interval_cmp_value().

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Splitting the time field into days and microseconds is pretty
useless when we're just going to recombine those values.
It's unclear if anyone will notice the speedup in real-world
cases, but a cycle shaved is a cycle earned.

Discussion: https://postgr.es/m/2629129.1632675713@sss.pgh.pa.us
This commit is contained in:
Tom Lane 2021-09-26 14:24:03 -04:00
parent 7c1d8a243f
commit e94c1a55da
1 changed files with 5 additions and 8 deletions
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13
src/backend/utils/adt/timestamp.c
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@ -2352,20 +2352,17 @@ static inline INT128
interval_cmp_value(const Interval *interval)
{
INT128 span;
int64 dayfraction;
int64 days;
/*
* Separate time field into days and dayfraction, then add the month and
* day fields to the days part. We cannot overflow int64 days here.
* Combine the month and day fields into an integral number of days.
* Because the inputs are int32, int64 arithmetic suffices here.
*/
dayfraction = interval->time % USECS_PER_DAY;
days = interval->time / USECS_PER_DAY;
days += interval->month * INT64CONST(30);
days = interval->month * INT64CONST(30);
days += interval->day;
/* Widen dayfraction to 128 bits */
span = int64_to_int128(dayfraction);
/* Widen time field to 128 bits */
span = int64_to_int128(interval->time);
/* Scale up days to microseconds, forming a 128-bit product */
int128_add_int64_mul_int64(&span, days, USECS_PER_DAY);