Improved `checked_isqrt` and `isqrt` methods #128166

ChaiTRex · 2024-07-25T00:23:29Z

Improved tests of `isqrt` and `checked_isqrt` implementations

Inputs chosen more thoroughly and systematically.
Checks that isqrt and checked_isqrt have equivalent results for signed types, either equivalent numerically or equivalent as a panic and a None.
Checks that isqrt has numerically-equivalent results for unsigned types and their NonZero counterparts.

Added benchmarks for `isqrt` implementations

Greatly sped up `checked_isqrt` and `isqrt` methods

Uses a lookup table for 8-bit integers and then the Karatsuba square root algorithm for larger integers.
Includes optimization hints that give the compiler the exact numeric range of results.

Feature tracking issue

isqrt is an unstable feature tracked at #116226.

Benchmarked improvements

Command used to benchmark

./x bench library/core -- int_sqrt

Before

benchmarks:
    num::int_sqrt::i128::isqrt           439591.65/iter  +/- 6652.70
    num::int_sqrt::i16::isqrt              5302.97/iter   +/- 160.93
    num::int_sqrt::i32::isqrt             62999.11/iter  +/- 2022.05
    num::int_sqrt::i64::isqrt            125248.81/iter  +/- 1674.43
    num::int_sqrt::i8::isqrt                123.56/iter     +/- 1.87
    num::int_sqrt::isize::isqrt          125356.56/iter  +/- 1017.03
    num::int_sqrt::non_zero_u128::isqrt  437443.75/iter  +/- 3535.43
    num::int_sqrt::non_zero_u16::isqrt     8604.58/iter    +/- 94.76
    num::int_sqrt::non_zero_u32::isqrt    62933.33/iter   +/- 517.30
    num::int_sqrt::non_zero_u64::isqrt   125076.38/iter +/- 11340.61
    num::int_sqrt::non_zero_u8::isqrt       221.51/iter     +/- 1.58
    num::int_sqrt::non_zero_usize::isqrt 136005.21/iter  +/- 2020.35
    num::int_sqrt::u128::isqrt           439014.55/iter  +/- 3920.45
    num::int_sqrt::u16::isqrt              8575.08/iter   +/- 148.06
    num::int_sqrt::u32::isqrt             63008.89/iter   +/- 803.67
    num::int_sqrt::u64::isqrt            125088.09/iter   +/- 879.29
    num::int_sqrt::u8::isqrt                230.18/iter     +/- 2.04
    num::int_sqrt::usize::isqrt          125237.51/iter  +/- 4747.83

After

benchmarks:
    num::int_sqrt::i128::isqrt           105184.89/iter +/- 1171.38
    num::int_sqrt::i16::isqrt              1910.26/iter   +/- 78.50
    num::int_sqrt::i32::isqrt             34260.34/iter  +/- 960.84
    num::int_sqrt::i64::isqrt             45939.19/iter +/- 2525.65
    num::int_sqrt::i8::isqrt                 22.87/iter    +/- 0.45
    num::int_sqrt::isize::isqrt           45884.17/iter  +/- 595.49
    num::int_sqrt::non_zero_u128::isqrt  106344.27/iter  +/- 780.99
    num::int_sqrt::non_zero_u16::isqrt     2790.19/iter   +/- 53.43
    num::int_sqrt::non_zero_u32::isqrt    33613.99/iter  +/- 362.96
    num::int_sqrt::non_zero_u64::isqrt    46235.42/iter  +/- 429.69
    num::int_sqrt::non_zero_u8::isqrt        31.78/iter    +/- 0.75
    num::int_sqrt::non_zero_usize::isqrt  46208.75/iter  +/- 375.27
    num::int_sqrt::u128::isqrt           106385.94/iter +/- 1649.95
    num::int_sqrt::u16::isqrt              2747.69/iter   +/- 28.72
    num::int_sqrt::u32::isqrt             33627.09/iter  +/- 475.68
    num::int_sqrt::u64::isqrt             46182.29/iter  +/- 311.16
    num::int_sqrt::u8::isqrt                 33.10/iter    +/- 0.30
    num::int_sqrt::usize::isqrt           46165.00/iter  +/- 388.41

Tracking Issue for {u8,i8,...}::isqrt #116226

try-job: test-various

rustbot · 2024-07-25T00:23:36Z

r? @tgross35

rustbot has assigned @tgross35.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

tgross35 · 2024-07-25T00:35:57Z

I'll take a closer look in a bit but FYI your last commit message has a typo (s/sped/speed)

ChaiTRex · 2024-07-25T00:57:06Z

The last force push added a missing file.

I'll take a closer look in a bit but FYI your last commit message has a typo (s/sped/speed)

OK, thanks for taking a look. Oh, I was using 'sped' as a past tense of the verb form of 'speed'.

tgross35

I left a very superficial review, will need to take some time to double check the important parts (I think the proposed deduplication will make this a bit more straightforward). At a high level these changes are awesome, thanks for the PR!

library/core/src/num/int_sqrt.rs

library/core/src/num/int_macros.rs

library/core/src/num/int_sqrt.rs

library/core/benches/num/int_sqrt/mod.rs

library/core/src/num/int_macros.rs

library/core/src/num/int_sqrt.rs

tgross35 · 2024-07-25T01:42:13Z

I'll take a closer look in a bit but FYI your last commit message has a typo (s/sped/speed)

OK, thanks for taking a look. Oh, I was using 'sped' as a past tense of the verb form of 'speed'.

Ah, I see you did the same for the other commits too. Commit messages are usually in imperative mood to describe what the change does, i.e. "Improve test", "Add benchmarks" "Greatly speed up". Hence my confusion :)

(Rust has no commit message policy so no need to anything if you don't feel like it).

library/core/src/num/int_sqrt.rs

library/core/tests/num/int_macros.rs

library/core/tests/num/int_sqrt.rs

tgross35 · 2024-07-26T08:21:00Z

Looks pretty reasonable after a more thorough read through, awesome improvements to the tests. I think this should be good after combining some similar code, just to make things a bit easier to understand & maintain.

If you run benchmarks again, could you post your cpu model for a reference?

@rustbot author

ChaiTRex · 2024-08-01T06:32:38Z

If you run benchmarks again, could you post your cpu model for a reference?

I was using aarch64-apple-darwin on a MacBook Air with an M1 processor under macOS 14.5.1 (now 14.6).

After I replaced the benchmarks with equivalents to ilog10's benchmarks (which use an exponential distribution for the random inputs), I get the following:

Benchmarks

Before this pull request

benchmarks:
    num::int_sqrt::u128_sqrt_predictable  108945.82/iter +/- 1673.86
    num::int_sqrt::u128_sqrt_random        16389.17/iter  +/- 231.44
    num::int_sqrt::u128_sqrt_random_small   1290.22/iter   +/- 41.90
    num::int_sqrt::u16_sqrt_predictable     1080.06/iter   +/- 43.44
    num::int_sqrt::u16_sqrt_random          1064.57/iter   +/- 20.79
    num::int_sqrt::u16_sqrt_random_small     579.85/iter   +/- 13.81
    num::int_sqrt::u32_sqrt_predictable     2979.65/iter   +/- 29.79
    num::int_sqrt::u32_sqrt_random          1718.20/iter   +/- 58.86
    num::int_sqrt::u32_sqrt_random_small     480.19/iter   +/- 26.59
    num::int_sqrt::u64_sqrt_predictable    13089.55/iter  +/- 484.72
    num::int_sqrt::u64_sqrt_random          3751.04/iter   +/- 79.66
    num::int_sqrt::u64_sqrt_random_small     498.58/iter    +/- 3.60
    num::int_sqrt::u8_sqrt_predictable       329.07/iter   +/- 12.64
    num::int_sqrt::u8_sqrt_random            576.37/iter   +/- 47.12
    num::int_sqrt::u8_sqrt_random_small      589.01/iter   +/- 22.53

When I first made this pull request

benchmarks:
    num::int_sqrt::u128_sqrt_predictable  30728.33/iter +/- 1093.31
    num::int_sqrt::u128_sqrt_random        4392.30/iter  +/- 149.35
    num::int_sqrt::u128_sqrt_random_small   323.58/iter    +/- 7.26
    num::int_sqrt::u16_sqrt_predictable     304.50/iter   +/- 10.60
    num::int_sqrt::u16_sqrt_random          334.78/iter   +/- 18.02
    num::int_sqrt::u16_sqrt_random_small    139.06/iter    +/- 2.50
    num::int_sqrt::u32_sqrt_predictable    1585.35/iter   +/- 59.03
    num::int_sqrt::u32_sqrt_random          972.40/iter   +/- 38.47
    num::int_sqrt::u32_sqrt_random_small    149.02/iter    +/- 4.50
    num::int_sqrt::u64_sqrt_predictable    5641.28/iter  +/- 136.16
    num::int_sqrt::u64_sqrt_random         1703.97/iter   +/- 43.75
    num::int_sqrt::u64_sqrt_random_small    197.42/iter    +/- 4.03
    num::int_sqrt::u8_sqrt_predictable       42.90/iter    +/- 1.39
    num::int_sqrt::u8_sqrt_random           133.55/iter    +/- 3.92
    num::int_sqrt::u8_sqrt_random_small     133.85/iter    +/- 2.36

With the changes I'm going to push soon

benchmarks:
    num::int_sqrt::u128_sqrt_predictable  26622.63/iter +/- 386.54
    num::int_sqrt::u128_sqrt_random        3584.59/iter +/- 131.42
    num::int_sqrt::u128_sqrt_random_small   904.23/iter  +/- 22.04
    num::int_sqrt::u16_sqrt_predictable     388.01/iter   +/- 7.85
    num::int_sqrt::u16_sqrt_random          480.00/iter  +/- 16.07
    num::int_sqrt::u16_sqrt_random_small    332.05/iter   +/- 7.46
    num::int_sqrt::u32_sqrt_predictable    1317.23/iter  +/- 25.71
    num::int_sqrt::u32_sqrt_random          783.17/iter   +/- 8.53
    num::int_sqrt::u32_sqrt_random_small    415.10/iter  +/- 14.06
    num::int_sqrt::u64_sqrt_predictable    4563.42/iter +/- 129.48
    num::int_sqrt::u64_sqrt_random         1378.32/iter  +/- 60.46
    num::int_sqrt::u64_sqrt_random_small    658.41/iter   +/- 8.93
    num::int_sqrt::u8_sqrt_predictable       42.90/iter   +/- 0.82
    num::int_sqrt::u8_sqrt_random           132.98/iter   +/- 1.53
    num::int_sqrt::u8_sqrt_random_small     132.94/iter   +/- 2.94

There's a tradeoff here. In the push I'm going to make soon, randomly chosen inputs from the whole input type range get a decent speedup from the initial pull request's code, but randomly chosen small inputs get about 3 times slower. Is that a good tradeoff? Is there another benchmark that should be added?

ChaiTRex · 2024-08-01T07:20:58Z

With a uniform distribution, we get these results:

Uniform distribution benchmarks

original_u8             time:   [9.7782 ns 9.8095 ns 9.8501 ns]
karatsuba_u8            time:   [5.2377 ns 5.2448 ns 5.2531 ns]
karatsuba_2_u8          time:   [5.2304 ns 5.2347 ns 5.2399 ns]

original_u16            time:   [13.415 ns 13.437 ns 13.465 ns]
karatsuba_u16           time:   [6.7425 ns 6.7487 ns 6.7568 ns]
karatsuba_2_u16         time:   [6.3988 ns 6.4035 ns 6.4094 ns]

original_u32            time:   [19.016 ns 19.044 ns 19.078 ns]
karatsuba_u32           time:   [10.162 ns 10.182 ns 10.211 ns]
karatsuba_2_u32         time:   [8.8756 ns 8.8866 ns 8.8993 ns]

original_u64            time:   [44.361 ns 44.413 ns 44.480 ns]
karatsuba_u64           time:   [19.043 ns 19.144 ns 19.276 ns]
karatsuba_2_u64         time:   [16.330 ns 16.359 ns 16.392 ns]

original_u128           time:   [147.14 ns 147.49 ns 147.88 ns]
karatsuba_u128          time:   [51.335 ns 51.455 ns 51.602 ns]
karatsuba_2_u128        time:   [45.447 ns 45.507 ns 45.575 ns]

library/core/src/num/int_sqrt.rs

library/core/src/num/int_macros.rs

library/core/src/num/nonzero.rs

library/core/src/num/int_sqrt.rs

library/core/src/num/int_macros.rs

library/core/src/num/int_sqrt.rs

tgross35 · 2024-08-12T07:26:18Z

Thanks for the changes, this looks a lot tidier with the deduplication. I left a handful of new comments but those are just small things, nothing major.

I'm not sure whether you had been waiting on a review, but comment @rustbot ready whenever you are done. This will need a squash before merge but no need to do that until it is final.

ChaiTRex · 2024-08-19T23:23:13Z

With regard to the squash, would it be alright to have two final commits, one for the testing and benchmarking and the next for the implementation? This would allow the benchmarking at least to be run on the prior implementation for comparison.

ChaiTRex · 2024-08-20T00:42:54Z

@rustbot ready

tgross35 · 2024-08-29T03:41:46Z

Yay

@bors try

bors · 2024-08-29T03:42:57Z

⌛ Trying commit 7af8e21 with merge daf8e6a...

Improved `checked_isqrt` and `isqrt` methods ### Improved tests of `isqrt` and `checked_isqrt` implementations * Inputs chosen more thoroughly and systematically. * Checks that `isqrt` and `checked_isqrt` have equivalent results for signed types, either equivalent numerically or equivalent as a panic and a `None`. * Checks that `isqrt` has numerically-equivalent results for unsigned types and their `NonZero` counterparts. ### Added benchmarks for `isqrt` implementations ### Greatly sped up `checked_isqrt` and `isqrt` methods * Uses a lookup table for 8-bit integers and then the Karatsuba square root algorithm for larger integers. * Includes optimization hints that give the compiler the exact numeric range of results. ### Feature tracking issue `isqrt` is an unstable feature tracked at rust-lang#116226. <details><summary>Benchmarked improvements</summary> ### Command used to benchmark ./x bench library/core -- int_sqrt ### Before benchmarks: num::int_sqrt::i128::isqrt 439591.65/iter +/- 6652.70 num::int_sqrt::i16::isqrt 5302.97/iter +/- 160.93 num::int_sqrt::i32::isqrt 62999.11/iter +/- 2022.05 num::int_sqrt::i64::isqrt 125248.81/iter +/- 1674.43 num::int_sqrt::i8::isqrt 123.56/iter +/- 1.87 num::int_sqrt::isize::isqrt 125356.56/iter +/- 1017.03 num::int_sqrt::non_zero_u128::isqrt 437443.75/iter +/- 3535.43 num::int_sqrt::non_zero_u16::isqrt 8604.58/iter +/- 94.76 num::int_sqrt::non_zero_u32::isqrt 62933.33/iter +/- 517.30 num::int_sqrt::non_zero_u64::isqrt 125076.38/iter +/- 11340.61 num::int_sqrt::non_zero_u8::isqrt 221.51/iter +/- 1.58 num::int_sqrt::non_zero_usize::isqrt 136005.21/iter +/- 2020.35 num::int_sqrt::u128::isqrt 439014.55/iter +/- 3920.45 num::int_sqrt::u16::isqrt 8575.08/iter +/- 148.06 num::int_sqrt::u32::isqrt 63008.89/iter +/- 803.67 num::int_sqrt::u64::isqrt 125088.09/iter +/- 879.29 num::int_sqrt::u8::isqrt 230.18/iter +/- 2.04 num::int_sqrt::usize::isqrt 125237.51/iter +/- 4747.83 ### After benchmarks: num::int_sqrt::i128::isqrt 105184.89/iter +/- 1171.38 num::int_sqrt::i16::isqrt 1910.26/iter +/- 78.50 num::int_sqrt::i32::isqrt 34260.34/iter +/- 960.84 num::int_sqrt::i64::isqrt 45939.19/iter +/- 2525.65 num::int_sqrt::i8::isqrt 22.87/iter +/- 0.45 num::int_sqrt::isize::isqrt 45884.17/iter +/- 595.49 num::int_sqrt::non_zero_u128::isqrt 106344.27/iter +/- 780.99 num::int_sqrt::non_zero_u16::isqrt 2790.19/iter +/- 53.43 num::int_sqrt::non_zero_u32::isqrt 33613.99/iter +/- 362.96 num::int_sqrt::non_zero_u64::isqrt 46235.42/iter +/- 429.69 num::int_sqrt::non_zero_u8::isqrt 31.78/iter +/- 0.75 num::int_sqrt::non_zero_usize::isqrt 46208.75/iter +/- 375.27 num::int_sqrt::u128::isqrt 106385.94/iter +/- 1649.95 num::int_sqrt::u16::isqrt 2747.69/iter +/- 28.72 num::int_sqrt::u32::isqrt 33627.09/iter +/- 475.68 num::int_sqrt::u64::isqrt 46182.29/iter +/- 311.16 num::int_sqrt::u8::isqrt 33.10/iter +/- 0.30 num::int_sqrt::usize::isqrt 46165.00/iter +/- 388.41 </details> Tracking Issue for {u8,i8,...}::isqrt rust-lang#116226 try-job: test-various

bors · 2024-08-29T04:46:51Z

☀️ Try build successful - checks-actions
Build commit: daf8e6a (daf8e6a755a4ccac4f08164a49fff14a2cd7e1d0)

tgross35 · 2024-08-29T04:49:45Z

Great! Thanks for the fix.

@bors r+

bors · 2024-08-29T04:49:47Z

📌 Commit 7af8e21 has been approved by tgross35

It is now in the queue for this repository.

workingjubilee · 2024-08-29T05:19:42Z

Sorry to bother but is there a particular reason that #[should_panic] annotations on a separate test function is not appropriate? Like so: https://doc.rust-lang.org/rust-by-example/testing/unit_testing.html#testing-panics

tgross35 · 2024-08-29T05:23:26Z

I thought about that too - but it runs the tests on a range of numbers, so it's not really feasible. In theory we could spot check a few numbers or we probably don't really need to test this, but it seems pretty harmless.

workingjubilee · 2024-08-29T05:32:12Z

hm, okay!

workingjubilee · 2024-08-29T05:33:39Z

The most useful negative integers to test are usually -1, -2, -10, and i{N}::MIN.

The last often manages to do something clever.

Improved `checked_isqrt` and `isqrt` methods ### Improved tests of `isqrt` and `checked_isqrt` implementations * Inputs chosen more thoroughly and systematically. * Checks that `isqrt` and `checked_isqrt` have equivalent results for signed types, either equivalent numerically or equivalent as a panic and a `None`. * Checks that `isqrt` has numerically-equivalent results for unsigned types and their `NonZero` counterparts. ### Added benchmarks for `isqrt` implementations ### Greatly sped up `checked_isqrt` and `isqrt` methods * Uses a lookup table for 8-bit integers and then the Karatsuba square root algorithm for larger integers. * Includes optimization hints that give the compiler the exact numeric range of results. ### Feature tracking issue `isqrt` is an unstable feature tracked at rust-lang#116226. <details><summary>Benchmarked improvements</summary> ### Command used to benchmark ./x bench library/core -- int_sqrt ### Before benchmarks: num::int_sqrt::i128::isqrt 439591.65/iter +/- 6652.70 num::int_sqrt::i16::isqrt 5302.97/iter +/- 160.93 num::int_sqrt::i32::isqrt 62999.11/iter +/- 2022.05 num::int_sqrt::i64::isqrt 125248.81/iter +/- 1674.43 num::int_sqrt::i8::isqrt 123.56/iter +/- 1.87 num::int_sqrt::isize::isqrt 125356.56/iter +/- 1017.03 num::int_sqrt::non_zero_u128::isqrt 437443.75/iter +/- 3535.43 num::int_sqrt::non_zero_u16::isqrt 8604.58/iter +/- 94.76 num::int_sqrt::non_zero_u32::isqrt 62933.33/iter +/- 517.30 num::int_sqrt::non_zero_u64::isqrt 125076.38/iter +/- 11340.61 num::int_sqrt::non_zero_u8::isqrt 221.51/iter +/- 1.58 num::int_sqrt::non_zero_usize::isqrt 136005.21/iter +/- 2020.35 num::int_sqrt::u128::isqrt 439014.55/iter +/- 3920.45 num::int_sqrt::u16::isqrt 8575.08/iter +/- 148.06 num::int_sqrt::u32::isqrt 63008.89/iter +/- 803.67 num::int_sqrt::u64::isqrt 125088.09/iter +/- 879.29 num::int_sqrt::u8::isqrt 230.18/iter +/- 2.04 num::int_sqrt::usize::isqrt 125237.51/iter +/- 4747.83 ### After benchmarks: num::int_sqrt::i128::isqrt 105184.89/iter +/- 1171.38 num::int_sqrt::i16::isqrt 1910.26/iter +/- 78.50 num::int_sqrt::i32::isqrt 34260.34/iter +/- 960.84 num::int_sqrt::i64::isqrt 45939.19/iter +/- 2525.65 num::int_sqrt::i8::isqrt 22.87/iter +/- 0.45 num::int_sqrt::isize::isqrt 45884.17/iter +/- 595.49 num::int_sqrt::non_zero_u128::isqrt 106344.27/iter +/- 780.99 num::int_sqrt::non_zero_u16::isqrt 2790.19/iter +/- 53.43 num::int_sqrt::non_zero_u32::isqrt 33613.99/iter +/- 362.96 num::int_sqrt::non_zero_u64::isqrt 46235.42/iter +/- 429.69 num::int_sqrt::non_zero_u8::isqrt 31.78/iter +/- 0.75 num::int_sqrt::non_zero_usize::isqrt 46208.75/iter +/- 375.27 num::int_sqrt::u128::isqrt 106385.94/iter +/- 1649.95 num::int_sqrt::u16::isqrt 2747.69/iter +/- 28.72 num::int_sqrt::u32::isqrt 33627.09/iter +/- 475.68 num::int_sqrt::u64::isqrt 46182.29/iter +/- 311.16 num::int_sqrt::u8::isqrt 33.10/iter +/- 0.30 num::int_sqrt::usize::isqrt 46165.00/iter +/- 388.41 </details> Tracking Issue for {u8,i8,...}::isqrt rust-lang#116226 try-job: test-various

tgross35 · 2024-08-29T05:41:09Z

Ah that's actually a good point - I thought we were checking a range but it looks like we are checking MIN https://github.com/rust-lang/rust/pull/128166/files#diff-eef7e7d7a0a129c86de4f1152c95cbbfcdf4dd594cfbf8d4a42c5b7f90746f4dR24.

@ChaiTRex am I missing something? If not, it would be good to add Jubilee's other suggested spot checks since the machinery is already there. It can just be a follow up since this is already in a rollup, and I don't really expect them to fail.

Improved `checked_isqrt` and `isqrt` methods ### Improved tests of `isqrt` and `checked_isqrt` implementations * Inputs chosen more thoroughly and systematically. * Checks that `isqrt` and `checked_isqrt` have equivalent results for signed types, either equivalent numerically or equivalent as a panic and a `None`. * Checks that `isqrt` has numerically-equivalent results for unsigned types and their `NonZero` counterparts. ### Added benchmarks for `isqrt` implementations ### Greatly sped up `checked_isqrt` and `isqrt` methods * Uses a lookup table for 8-bit integers and then the Karatsuba square root algorithm for larger integers. * Includes optimization hints that give the compiler the exact numeric range of results. ### Feature tracking issue `isqrt` is an unstable feature tracked at rust-lang#116226. <details><summary>Benchmarked improvements</summary> ### Command used to benchmark ./x bench library/core -- int_sqrt ### Before benchmarks: num::int_sqrt::i128::isqrt 439591.65/iter +/- 6652.70 num::int_sqrt::i16::isqrt 5302.97/iter +/- 160.93 num::int_sqrt::i32::isqrt 62999.11/iter +/- 2022.05 num::int_sqrt::i64::isqrt 125248.81/iter +/- 1674.43 num::int_sqrt::i8::isqrt 123.56/iter +/- 1.87 num::int_sqrt::isize::isqrt 125356.56/iter +/- 1017.03 num::int_sqrt::non_zero_u128::isqrt 437443.75/iter +/- 3535.43 num::int_sqrt::non_zero_u16::isqrt 8604.58/iter +/- 94.76 num::int_sqrt::non_zero_u32::isqrt 62933.33/iter +/- 517.30 num::int_sqrt::non_zero_u64::isqrt 125076.38/iter +/- 11340.61 num::int_sqrt::non_zero_u8::isqrt 221.51/iter +/- 1.58 num::int_sqrt::non_zero_usize::isqrt 136005.21/iter +/- 2020.35 num::int_sqrt::u128::isqrt 439014.55/iter +/- 3920.45 num::int_sqrt::u16::isqrt 8575.08/iter +/- 148.06 num::int_sqrt::u32::isqrt 63008.89/iter +/- 803.67 num::int_sqrt::u64::isqrt 125088.09/iter +/- 879.29 num::int_sqrt::u8::isqrt 230.18/iter +/- 2.04 num::int_sqrt::usize::isqrt 125237.51/iter +/- 4747.83 ### After benchmarks: num::int_sqrt::i128::isqrt 105184.89/iter +/- 1171.38 num::int_sqrt::i16::isqrt 1910.26/iter +/- 78.50 num::int_sqrt::i32::isqrt 34260.34/iter +/- 960.84 num::int_sqrt::i64::isqrt 45939.19/iter +/- 2525.65 num::int_sqrt::i8::isqrt 22.87/iter +/- 0.45 num::int_sqrt::isize::isqrt 45884.17/iter +/- 595.49 num::int_sqrt::non_zero_u128::isqrt 106344.27/iter +/- 780.99 num::int_sqrt::non_zero_u16::isqrt 2790.19/iter +/- 53.43 num::int_sqrt::non_zero_u32::isqrt 33613.99/iter +/- 362.96 num::int_sqrt::non_zero_u64::isqrt 46235.42/iter +/- 429.69 num::int_sqrt::non_zero_u8::isqrt 31.78/iter +/- 0.75 num::int_sqrt::non_zero_usize::isqrt 46208.75/iter +/- 375.27 num::int_sqrt::u128::isqrt 106385.94/iter +/- 1649.95 num::int_sqrt::u16::isqrt 2747.69/iter +/- 28.72 num::int_sqrt::u32::isqrt 33627.09/iter +/- 475.68 num::int_sqrt::u64::isqrt 46182.29/iter +/- 311.16 num::int_sqrt::u8::isqrt 33.10/iter +/- 0.30 num::int_sqrt::usize::isqrt 46165.00/iter +/- 388.41 </details> Tracking Issue for {u8,i8,...}::isqrt rust-lang#116226 try-job: test-various

…kingjubilee Rollup of 9 pull requests Successful merges: - rust-lang#120221 (Don't make statement nonterminals match pattern nonterminals) - rust-lang#127912 (std: make `thread::current` available in all `thread_local!` destructors) - rust-lang#128166 (Improved `checked_isqrt` and `isqrt` methods) - rust-lang#129123 (rustdoc-json: Add test for `Self` type) - rust-lang#129366 (linker: Synchronize native library search in rustc and linker) - rust-lang#129527 (Don't use `TyKind` in a lint) - rust-lang#129534 (Deny `wasm_c_abi` lint to nudge the last 25%) - rust-lang#129640 (Re-enable android tests/benches in alloc/core) - rust-lang#129675 (allow BufReader::peek to be called on unsized types) r? `@ghost` `@rustbot` modify labels: rollup

workingjubilee · 2024-08-29T08:50:40Z

library/core/tests/num/int_sqrt.rs

+                    for n in (0..=127)
+                        .chain(<$T>::MAX - 127..=<$T>::MAX)
+                        .chain((0..<$T>::MAX.count_ones()).map(|exponent| (1 << exponent) - 1))
+                        .chain((0..<$T>::MAX.count_ones()).map(|exponent| 1 << exponent))
+                    {
+                        isqrt_consistency_check(n);


this is the range.

Yeah, I meant specifically a range including negative values

ChaiTRex · 2024-08-29T13:40:50Z

@tgross35 @workingjubilee There are several places where isqrt_consistency_check is called, such as six places in the isqrt_extended test. It basically checks i*::MIN and the negative version of every positive value that gets tested (there are thousands of positive values that get checked).

Do #[should_panic] tests run on platforms like Wasm where all panics abort? If they do, I could add a few #[should_panic] tests to also test on those platforms.

…llaumeGomez Rollup of 7 pull requests Successful merges: - rust-lang#123940 (debug-fmt-detail option) - rust-lang#128166 (Improved `checked_isqrt` and `isqrt` methods) - rust-lang#128970 (Add `-Zlint-llvm-ir`) - rust-lang#129316 (riscv64imac: allow shadow call stack sanitizer) - rust-lang#129690 (Add `needs-unwind` compiletest directive to `libtest-thread-limit` and replace some `Path` with `path` in `run-make`) - rust-lang#129732 (Add `unreachable_pub`, round 3) - rust-lang#129743 (Fix rustdoc clippy lints) r? `@ghost` `@rustbot` modify labels: rollup

ChaiTRex · 2024-08-29T15:42:55Z

nemo157 mentioned on the community Discord server that -Zpanic-abort-test can handle should_panic tests on platforms that abort during panic. Since abort-on-panic eliminates my catch_unwind checks, I'll add a few should_panic tests for negative inputs in my next pull request so that panicking is tested on those platforms.

tgross35 · 2024-08-29T17:48:20Z

@tgross35 @workingjubilee There are several places where isqrt_consistency_check is called, such as six places in the isqrt_extended test. It basically checks i*::MIN and the negative version of every positive value that gets tested (there are thousands of positive values that get checked).

I missed that it checked .wrapping_neg() too within that function, all good then.

Do #[should_panic] tests run on platforms like Wasm where all panics abort? If they do, I could add a few #[should_panic] tests to also test on those platforms.

[...]

nemo157 mentioned on the community Discord server that -Zpanic-abort-test can handle should_panic tests on platforms that abort during panic. Since abort-on-panic eliminates my catch_unwind checks, I'll add a few should_panic tests for negative inputs in my next pull request so that panicking is tested on those platforms.

We can pretty reasonably expect that if it panics on one platform and all other tests pass, it will continue on panic on others. So no worries here, I don't think you need a follow up.

…llaumeGomez Rollup of 7 pull requests Successful merges: - rust-lang#123940 (debug-fmt-detail option) - rust-lang#128166 (Improved `checked_isqrt` and `isqrt` methods) - rust-lang#128970 (Add `-Zlint-llvm-ir`) - rust-lang#129316 (riscv64imac: allow shadow call stack sanitizer) - rust-lang#129690 (Add `needs-unwind` compiletest directive to `libtest-thread-limit` and replace some `Path` with `path` in `run-make`) - rust-lang#129732 (Add `unreachable_pub`, round 3) - rust-lang#129743 (Fix rustdoc clippy lints) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#128166 - ChaiTRex:isqrt, r=tgross35 Improved `checked_isqrt` and `isqrt` methods ### Improved tests of `isqrt` and `checked_isqrt` implementations * Inputs chosen more thoroughly and systematically. * Checks that `isqrt` and `checked_isqrt` have equivalent results for signed types, either equivalent numerically or equivalent as a panic and a `None`. * Checks that `isqrt` has numerically-equivalent results for unsigned types and their `NonZero` counterparts. ### Added benchmarks for `isqrt` implementations ### Greatly sped up `checked_isqrt` and `isqrt` methods * Uses a lookup table for 8-bit integers and then the Karatsuba square root algorithm for larger integers. * Includes optimization hints that give the compiler the exact numeric range of results. ### Feature tracking issue `isqrt` is an unstable feature tracked at rust-lang#116226. <details><summary>Benchmarked improvements</summary> ### Command used to benchmark ./x bench library/core -- int_sqrt ### Before benchmarks: num::int_sqrt::i128::isqrt 439591.65/iter +/- 6652.70 num::int_sqrt::i16::isqrt 5302.97/iter +/- 160.93 num::int_sqrt::i32::isqrt 62999.11/iter +/- 2022.05 num::int_sqrt::i64::isqrt 125248.81/iter +/- 1674.43 num::int_sqrt::i8::isqrt 123.56/iter +/- 1.87 num::int_sqrt::isize::isqrt 125356.56/iter +/- 1017.03 num::int_sqrt::non_zero_u128::isqrt 437443.75/iter +/- 3535.43 num::int_sqrt::non_zero_u16::isqrt 8604.58/iter +/- 94.76 num::int_sqrt::non_zero_u32::isqrt 62933.33/iter +/- 517.30 num::int_sqrt::non_zero_u64::isqrt 125076.38/iter +/- 11340.61 num::int_sqrt::non_zero_u8::isqrt 221.51/iter +/- 1.58 num::int_sqrt::non_zero_usize::isqrt 136005.21/iter +/- 2020.35 num::int_sqrt::u128::isqrt 439014.55/iter +/- 3920.45 num::int_sqrt::u16::isqrt 8575.08/iter +/- 148.06 num::int_sqrt::u32::isqrt 63008.89/iter +/- 803.67 num::int_sqrt::u64::isqrt 125088.09/iter +/- 879.29 num::int_sqrt::u8::isqrt 230.18/iter +/- 2.04 num::int_sqrt::usize::isqrt 125237.51/iter +/- 4747.83 ### After benchmarks: num::int_sqrt::i128::isqrt 105184.89/iter +/- 1171.38 num::int_sqrt::i16::isqrt 1910.26/iter +/- 78.50 num::int_sqrt::i32::isqrt 34260.34/iter +/- 960.84 num::int_sqrt::i64::isqrt 45939.19/iter +/- 2525.65 num::int_sqrt::i8::isqrt 22.87/iter +/- 0.45 num::int_sqrt::isize::isqrt 45884.17/iter +/- 595.49 num::int_sqrt::non_zero_u128::isqrt 106344.27/iter +/- 780.99 num::int_sqrt::non_zero_u16::isqrt 2790.19/iter +/- 53.43 num::int_sqrt::non_zero_u32::isqrt 33613.99/iter +/- 362.96 num::int_sqrt::non_zero_u64::isqrt 46235.42/iter +/- 429.69 num::int_sqrt::non_zero_u8::isqrt 31.78/iter +/- 0.75 num::int_sqrt::non_zero_usize::isqrt 46208.75/iter +/- 375.27 num::int_sqrt::u128::isqrt 106385.94/iter +/- 1649.95 num::int_sqrt::u16::isqrt 2747.69/iter +/- 28.72 num::int_sqrt::u32::isqrt 33627.09/iter +/- 475.68 num::int_sqrt::u64::isqrt 46182.29/iter +/- 311.16 num::int_sqrt::u8::isqrt 33.10/iter +/- 0.30 num::int_sqrt::usize::isqrt 46165.00/iter +/- 388.41 </details> Tracking Issue for {u8,i8,...}::isqrt rust-lang#116226 try-job: test-various

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Improved `checked_isqrt` and `isqrt` methods #128166

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Improved checked_isqrt and isqrt methods #128166

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Improved tests of isqrt and checked_isqrt implementations

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Improved `checked_isqrt` and `isqrt` methods #128166

Improved `checked_isqrt` and `isqrt` methods #128166

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Improved tests of `isqrt` and `checked_isqrt` implementations

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