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https://github.com/nikolaydubina/go-hackers-delight
"Hacker's Delight" in Go
https://github.com/nikolaydubina/go-hackers-delight
assembly binary bits book c logic risc showcase
Last synced: 7 days ago
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"Hacker's Delight" in Go
- Host: GitHub
- URL: https://github.com/nikolaydubina/go-hackers-delight
- Owner: nikolaydubina
- License: mit
- Created: 2024-05-11T06:20:23.000Z (6 months ago)
- Default Branch: master
- Last Pushed: 2024-09-20T04:37:22.000Z (about 2 months ago)
- Last Synced: 2024-10-23T11:09:07.406Z (15 days ago)
- Topics: assembly, binary, bits, book, c, logic, risc, showcase
- Language: Go
- Homepage:
- Size: 233 KB
- Stars: 93
- Watchers: 1
- Forks: 4
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Funding: .github/FUNDING.yml
- License: LICENSE
- Codeowners: .github/CODEOWNERS
Awesome Lists containing this project
README
# go-hackers-delight
[](https://codecov.io/gh/nikolaydubina/go-hackers-delight)
[](https://hits.sh/github.com/nikolaydubina/go-hackers-delight/)
[](https://pkg.go.dev/github.com/nikolaydubina/go-hackers-delight)
An interactive Go showcase of ["Hacker's Delight"](https://en.wikipedia.org/wiki/Hacker%27s_Delight) 2nd Edition by Henrey S.Warren Jr, 2013.[^1][^2]
> If you write optimizing compilers or high-performance code, you must read this book.
> — [Guy L. Steele](https://en.wikipedia.org/wiki/Guy_L._Steele_Jr.) [PhD, ACM Award, AAAI Fellow, Sun Fellow, core Java design]
> This is the first book that promises to tell the deep, dark secrets of computer arithmetic, and it delivers in spades. It contains every trick I knew plus many, many more.
> A godsend for library developers, compiler writers, and lovers of elegant hacks.
> It deserves a spot on your self right next to Knuth.
> In the ten years since the first edition came out, it's been absolutely invaluable to my work at Sun and Google.
> — [Joshua Bloch](https://en.wikipedia.org/wiki/Joshua_Bloch) [PhD, Distinguished Engineer at Sun, Chief Java Architect at Google 2004~2012]
### Methodology
* extensively fuzzing
* not using any Go packages, not even standard library
* using generics whenever possible
* verifying compiled code via https://godbolt.org
### Observations
* native `Abs` performance is the same
* native `Div` and `Mod` by small constants performance is better
* native `math/bits.Mul32` and `math/bits.Mul64`[^3] performance is the same
* native `math/bits.LeadingZeros` performance is better than `LeadingZeroes` algorithm
* native `math.Sqrt` performance is better
* native `math.Pow(x, 1./3)`[^4] performance is worse than `Cbrt` algorithm 💥
* native `math.Pow(x, 1./3)`[^4][^5] underflows but `Cbrt` algorithm is correct 💥
* native `math.Pow(x, n)`[^4] performance is worse than `Pow` algorithm 💥
* native `math.Log2(x)`[^4] performance is worse than `Log2` algorithm 💥
* native `math.Log10(x)`[^4] performance is worse than `Log10` algorithm 💥
* native `math.Log10(x)` [^4][^5] overflows for `math.MaxUint64` but `Log10` algorithm is correct 💥
* native `1/math.Sqrt(x)` performance is `1.5x` better than `RSqrtFloat32` algorithm
* native `switch` performance is better than `CycleThreeValues` algorithm
* native `crc32.Checksum` performance is `30x`~`500x` better than `CRC32` algorithms
* simplistic `LRUCache` performance is `3x` worse than `LRUCache` algorithm 💥
Appendix: Benchmarks
```bash
$ go test -bench .
goos: darwin
goarch: arm64
pkg: github.com/nikolaydubina/go-hackers-delight
BenchmarkNoop/---------------------------------16 1000000000 0.0000001 ns/op
BenchmarkAbs/basic-16 1000000000 0.9826 ns/op
BenchmarkAbs/Abs-16 1000000000 0.9647 ns/op
BenchmarkAbs/Abs2-16 1000000000 0.9943 ns/op
BenchmarkAbs/Abs3-16 1000000000 0.9819 ns/op
BenchmarkAbs/Abs4-16 1000000000 1.003 ns/op
BenchmarkAbs/AbsFastMul-16 1000000000 0.9598 ns/op
BenchmarkAvg/basic-16 973716225 2.045 ns/op
BenchmarkAvg/AvgFloor-16 602586224 2.050 ns/op
BenchmarkAvg/AvgCeil-16 582029594 2.054 ns/op
BenchmarkCycleThree/basic-16 767160418 1.560 ns/op
BenchmarkCycleThree/CycleThreeValues-16 438818894 2.729 ns/op
BenchmarkLeadingZeros/uint32/basic-16 1000000000 0.9419 ns/op
BenchmarkLeadingZeros/uint32/LeadingZerosUint32-16 1000000000 1.124 ns/op
BenchmarkLeadingZeros/uint64/basic-16 1000000000 0.9230 ns/op
BenchmarkLeadingZeros/uint64/LeadingZerosUint64-16 898095195 1.336 ns/op
BenchmarkCompress/Compress-16 100000000 10.60 ns/op
BenchmarkCompress/Compress2-16 55584826 21.52 ns/op
BenchmarkLRU/basic-16 246358870 4.870 ns/op
BenchmarkLRU/LRUCache-16 960896830 1.239 ns/op
BenchmarkMul/uint32/basic-16 593555838 1.892 ns/op
BenchmarkMul/uint32/MultiplyHighOrder32-16 951445552 2.046 ns/op
BenchmarkMul/uint64/basic-16 977065424 1.220 ns/op
BenchmarkMul/uint64/MultiplyHighOrder64-16 675693746 2.042 ns/op
BenchmarkDivMod/DivMod/3/basic-16 1000000000 0.8500 ns/op
BenchmarkDivMod/DivMod/3/DivMod3Signed-16 605588445 1.970 ns/op
BenchmarkDivMod/DivMod/3/DivMod3Signed2-16 1000000000 1.078 ns/op
BenchmarkDivMod/DivMod/7/basic-16 1000000000 0.8311 ns/op
BenchmarkDivMod/DivMod/7/DivMod7Signed-16 582087586 2.105 ns/op
BenchmarkDivMod/Div/3/basic-16 1000000000 0.8325 ns/op
BenchmarkDivMod/Div/3/Div3Signed-16 793883130 1.509 ns/op
BenchmarkDivMod/Div/3/Div3ShiftSigned-16 907116610 1.320 ns/op
BenchmarkDivMod/Div/7/basic-16 1000000000 0.8344 ns/op
BenchmarkDivMod/Div/7/Div7Signed-16 755509315 1.590 ns/op
BenchmarkDivMod/Div/7/Div7ShiftSigned-16 841563656 1.424 ns/op
BenchmarkDivMod/Mod/3/basic-16 1000000000 0.8309 ns/op
BenchmarkDivMod/Mod/3/Mod3Signed-16 812136249 1.466 ns/op
BenchmarkDivMod/Mod/3/Mod3Signed2-16 1000000000 0.8410 ns/op
BenchmarkDivMod/Mod/7/basic-16 1000000000 0.8332 ns/op
BenchmarkDivMod/Mod/7/Mod7Signed-16 766677633 1.564 ns/op
BenchmarkDivMod/Mod/7/Mod7Signed2-16 1000000000 1.095 ns/op
BenchmarkDivMod/Mod/10/basic-16 1000000000 0.8318 ns/op
BenchmarkDivMod/Mod/10/Mod10Signed-16 868932930 1.441 ns/op
BenchmarkDivMod/DivExact/7/basic-16 1000000000 0.9247 ns/op
BenchmarkDivMod/DivExact/7/DivExact7-16 1000000000 0.9238 ns/op
BenchmarkDivMod/DivExact/7/Div7Signed-16 718667949 1.668 ns/op
BenchmarkDivMod/DivExact/7/Div7ShiftSigned-16 802988229 1.490 ns/op
BenchmarkCbrt/basic-16 47340079 26.01 ns/op
BenchmarkCbrt/Cbrt-16 85196262 14.55 ns/op
BenchmarkPow/basic-16 24005180 48.25 ns/op
BenchmarkPow/Pow-16 65121390 19.08 ns/op
BenchmarkLog/uint32/2/basic-16 99810775 12.06 ns/op
BenchmarkLog/uint32/2/Log2-16 984283590 1.223 ns/op
BenchmarkLog/uint32/10/basic-16 140540709 8.516 ns/op
BenchmarkLog/uint32/10/Log10-16 539441811 2.220 ns/op
BenchmarkLog/uint64/2/basic-16 100000000 11.73 ns/op
BenchmarkLog/uint64/2/Log2-16 839779903 1.419 ns/op
BenchmarkLog/uint64/10/basic-16 142679388 8.419 ns/op
BenchmarkLog/uint64/10/Log10-16 538269764 2.228 ns/op
BenchmarkSqrt/basic-16 1000000000 1.019 ns/op
BenchmarkSqrt/SqrtNewton-16 188142513 6.538 ns/op
BenchmarkSqrt/SqrtBinarySearch-16 74752382 15.71 ns/op
BenchmarkSqrt/SqrtShiftAndSubtract-16 136426688 8.834 ns/op
BenchmarkCRC32/basic-16 220094371 5.395 ns/op
BenchmarkCRC32/CRC32Basic-16 448540 2510 ns/op
BenchmarkCRC32/CRC32TableLookup-16 8108901 147.5 ns/op
BenchmarkRSqrtFloat32/basic-16 1000000000 0.9354 ns/op
BenchmarkRSqrtFloat32/RSqrtFloat32-16 828149971 1.448 ns/op
PASS
ok github.com/nikolaydubina/go-hackers-delight 91.183s
```
[^1]: showcase in `C` — https://github.com/hcs0/Hackers-Delight
[^2]: showcase in `Rust` — https://github.com/victoryang00/Delight
[^3]: given manual inlining of generic type, which produces equivalent Go code
[^4]: we are comparing native float64 result converted to uint32, as there is no better standard function
[^5]: which is due to `float64` not having enough precision