f44bd0aee2
It was pointed out in the blog post [Big Integers in Zig] that we don't
have a special case in `num-bigint` for single-digit divisors. While
you can already get this optimization by dividing directly by `u32`,
it's easy to make small `BigUint` divisors work like this too.
$ cargo benchcmp baseline single-div
name baseline ns/iter single-div ns/iter diff ns/iter diff % speedup
factorial_div_biguint 5,638,353 1,005,488 -4,632,865 -82.17% x 5.61
`BigInt` will also gain from this, since it uses `BigUint` division
internally.
Running [zig-bn's facdiv-rs] shows a nice improvement too. My i7-7700K
with Rust 1.26 goes from 4.15 seconds to just 0.65 -- a 6.38x speedup!
[Big Integers in Zig]: https://tiehuis.github.io/big-integers-in-zig#division-test-single-limb
[zig-bn's facdiv-rs]: https://github.com/tiehuis/zig-bn/tree/master/bench/facdiv/crate-facdiv-rs
55 lines
1.0 KiB
TOML
55 lines
1.0 KiB
TOML
[package]
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authors = ["The Rust Project Developers"]
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description = "Big integer implementation for Rust"
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documentation = "https://docs.rs/num-bigint"
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homepage = "https://github.com/rust-num/num-bigint"
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keywords = ["mathematics", "numerics", "bignum"]
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categories = [ "algorithms", "data-structures", "science" ]
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license = "MIT/Apache-2.0"
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name = "num-bigint"
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repository = "https://github.com/rust-num/num-bigint"
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version = "0.1.43"
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readme = "README.md"
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[[bench]]
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name = "bigint"
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[[bench]]
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name = "factorial"
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[[bench]]
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name = "gcd"
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[[bench]]
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harness = false
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name = "shootout-pidigits"
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[dependencies]
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[dependencies.num-integer]
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version = "0.1.36"
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default-features = false
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[dependencies.num-traits]
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version = "0.2.0"
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default-features = false
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features = ["std"]
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[dependencies.rand]
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optional = true
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version = ">= 0.3.14, < 0.5.0"
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[dependencies.rustc-serialize]
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optional = true
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version = "0.3.19"
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[dependencies.serde]
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optional = true
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version = ">= 0.7.0, < 0.9.0"
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[dev-dependencies.rand]
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version = ">= 0.3.14, < 0.5.0"
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[features]
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default = ["rand", "rustc-serialize"]
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