Lazily calculate needed components in dateComponents(:from:in:)
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We are currently eagerly calculating all components in `_GregorianCalendar.dateComponents(:from:in:)` even if they're not needed. Skip all those if they're not being requested at all. Also switch from floating point's `remainder(dividingBy:)` and `truncatingRemainder(dividingBy:)` to integer math. The use case in the original report is essentially the `NextDatesMatchingOnHour` benchmark, where only time components are requested. Here's the result for this one. For other existing benchmarks I'm seeing 1.5-2x of improvement. ``` // NextDatesMatchingOnHour ** BEFORE ** ╒═══════════════════════════╤═════════╤═════════╤═════════╤═════════╤═════════╤═════════╤═════════╤═════════╕ │ Metric │ p0 │ p25 │ p50 │ p75 │ p90 │ p99 │ p100 │ Samples │ ╞═══════════════════════════╪═════════╪═════════╪═════════╪═════════╪═════════╪═════════╪═════════╪═════════╡ │ Malloc (total) * │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 28 │ ├───────────────────────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────┤ │ Throughput (# / s) (K) │ 9 │ 9 │ 9 │ 9 │ 9 │ 9 │ 9 │ 28 │ ├───────────────────────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────┤ │ Time (total CPU) (μs) * │ 108 │ 109 │ 109 │ 109 │ 109 │ 110 │ 110 │ 28 │ ╘═══════════════════════════╧═════════╧═════════╧═════════╧═════════╧═════════╧═════════╧═════════╧═════════╛ ** AFTER ** ╒═══════════════════════════╤═════════╤═════════╤═════════╤═════════╤═════════╤═════════╤═════════╤═════════╕ │ Metric │ p0 │ p25 │ p50 │ p75 │ p90 │ p99 │ p100 │ Samples │ ╞═══════════════════════════╪═════════╪═════════╪═════════╪═════════╪═════════╪═════════╪═════════╪═════════╡ │ Malloc (total) * │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 0 │ 97 │ ├───────────────────────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────┤ │ Throughput (# / s) (K) │ 33 │ 33 │ 32 │ 32 │ 32 │ 31 │ 31 │ 97 │ ├───────────────────────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────┤ │ Time (total CPU) (μs) * │ 30 │ 31 │ 31 │ 31 │ 31 │ 31 │ 31 │ 97 │ ╘═══════════════════════════╧═════════╧═════════╧═════════╧═════════╧═════════╧═════════╧═════════╧═════════╛ ``` Fixes 165794940
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@swift-ci please test |
jmschonfeld
approved these changes
Dec 5, 2025
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We are currently eagerly calculating all components in
_GregorianCalendar.dateComponents(:from:in:)even if they're not needed. Skip all those if they're not being requested at all.Also switch from floating point's
remainder(dividingBy:)andtruncatingRemainder(dividingBy:)to integer math.The use case in the original report is essentially the
NextDatesMatchingOnHourbenchmark, where only time components are requested. Here's the result for this one. For other existing benchmarks I'm seeing 1.5-2x of improvement.Fixes 165794940