https://github.com/norio-nomura/swiftbenchmark-indexof

https://github.com/norio-nomura/swiftbenchmark-indexof

Last synced: 3 months ago
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• Host: GitHub
• URL: https://github.com/norio-nomura/swiftbenchmark-indexof
• Owner: norio-nomura
• Created: 2015-01-14T09:23:26.000Z (almost 10 years ago)
• Default Branch: master
• Last Pushed: 2015-01-15T04:54:30.000Z (almost 10 years ago)
• Last Synced: 2024-05-09T16:23:51.669Z (8 months ago)
• Language: Swift
• Size: 285 KB
• Stars: 8
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# SwiftBenchmark-indexOf

### `swiftc -emit-sil -O`にはSwift標準ライブラリの中身も出力される

---

[ここ](https://github.com/katokichisoft/SimpleGaplessPlayer/blob/master/HKLAVGaplessPlayer/misc/HKLStdLibUtils.swift)でこんなコードをみた。

```swift

extension Array {

    /**

    Returns the lowest index whose corresponding array value matches a given condition.

    :discussion: Starting at index 0, each element of the array is passed as the 1st parameter of condition closure until a match is found or the end of the array is reached. Objects are considered equal if the closure returns true.

    :param: condition A closure for finding the target object in the array

    :returns: The lowest index whose corresponding array value matches a given condition. If none of the objects in the array matches the condition, returns nil.

    :refer: http://stackoverflow.com/a/24105493

    */

    func indexOf(condition: T -> Bool) -> Int? {

        for (idx, element) in enumerate(self) {

            if condition(element) {

                return idx

            }

        }

        return nil

    }

}

```

同じ機能を`lazy()`とか使って書いてみた。

```swift

func v1_index_of(domain: C, condition: C.Generator.Element -> Bool) -> C.Index? {

    return find(lazy(domain).map(condition), true)

}

```

うんシンプル。でもどっちを使うべきだろう？で[ベンチマーク](Benchmark/Benchmark.swift)

> :0: Test Case '-[Benchmark.Benchmark testPerformance_v1]' measured [Time, seconds] average: 1.557,…

> :0: Test Case '-[Benchmark.Benchmark testPerformance_v4]' measured [Time, seconds] average: 2.403,…

**おおよそ1.6倍くらいオリジナルが遅い。**

**やっぱ時代はFunctionalなのか！？**で、Swiftがどんなコードを出力してるのか気になったので、こんなコード

```swift

#!/usr/bin/env xcrun swift -i

import Foundation

func v1_index_of(domain: C, condition: C.Generator.Element -> Bool) -> C.Index? {

  return find(lazy(domain).map(condition), true)

}

func v2_index_of(domain: C, condition: C.Generator.Element -> Bool) -> C.Index? {

  for (idx, element) in enumerate(domain) {

    if condition(element) {

      return idx as? C.Index

    }

  }

  return nil

}

let a = [1,2,3]

let c = {(e: Int) -> Bool in e == 1}

let result1 = v1_index_of(a, c)

let result2 = v2_index_of(a, c)

```

を、以前書いた[swift-demangle-filter.py](https://gist.github.com/norio-nomura/121ef3eacbc6dda87dad)に通す。

`swift-demangle-filter.py -g indexof.swift -o indexof.asm`

[indexof.asm](https://gist.github.com/norio-nomura/7c76756f9827d16d40a1)

うーん、、**Swiftのアセンブリ出力は難しい。**　もうちょっと簡単な方法はないか？と`swiftc`の`-emit-sil`を試す。

`swift-demangle-filter.py -emit-sil indexof.swift -o indexof.sil`

[indexof.sil](https://gist.github.com/norio-nomura/f95c5921484da4a55242)

うーん、少し分かりやすくなったかな。あ、最適化オプション-O付け忘れてた。

`swift-demangle-filter.py -emit-sil -O indexof.swift -o indexof-O.sil`

[indexof-O.sil](https://gist.github.com/norio-nomura/e30c5450acfbc0bbf9d9)

あれ？なんか出力がやたら長くない？

```

// Swift.find (A, A.Generator.Element) -> Swift.Optional

sil public_external Swift.find (A, A.Generator.Element) -> A.Index? : $@thin  (@out Optional, @in C, @in C.Generator.Element) -> () {

  bb0(%0 : $*Optional, %1 : $*C, %2 : $*C.Generator.Element):

  %3 = alloc_stack $RangeGenerator       // users: %10, %16, %38, %51, %55, %61

  // function_ref Swift.Range.generate (Swift.Range)() -> Swift.RangeGenerator

  %4 = function_ref Swift.Range.generate (Swift.Range)() -> Swift.RangeGenerator : $@cc(method) @thin <τ_0_0 where τ_0_0 : ForwardIndexType, τ_0_0.Distance : _SignedIntegerType, τ_0_0.Distance.IntegerLiteralType : _BuiltinIntegerLiteralConvertible> (@out RangeGenerator<τ_0_0>, @in Range<τ_0_0>) -> () // user: %10

  %5 = alloc_stack $Range                // users: %9, %10, %12

  // function_ref Swift.indices (A) -> Swift.Range

  %6 = function_ref Swift.indices (A) -> Swift.Range : $@thin <τ_0_0 where τ_0_0 : CollectionType, τ_0_0.Generator : GeneratorType, τ_0_0.Index : ForwardIndexType, τ_0_0.Index.Distance : _SignedIntegerType, τ_0_0.Index.Distance.IntegerLiteralType : _BuiltinIntegerLiteralConvertible> (@out Range<τ_0_0.Index>, @in τ_0_0) -> () // user: %9

  %7 = alloc_stack $C                             // users: %8, %9, %11

  copy_addr %1 to [initialization] %7#1 : $*C     // id: %8

  %9 = apply %6(%5#1, %7#1) : $@thin <τ_0_0 where τ_0_0 : CollectionType, τ_0_0.Generator : GeneratorType, τ_0_0.Index : ForwardIndexType, τ_0_0.Index.Distance : _SignedIntegerType, τ_0_0.Index.Distance.IntegerLiteralType : _BuiltinIntegerLiteralConvertible> (@out Range<τ_0_0.Index>, @in τ_0_0) -> ()

  %10 = apply %4(%3#1, %5#1) : $@cc(method) @thin <τ_0_0 where τ_0_0 : ForwardIndexType, τ_0_0.Distance : _SignedIntegerType, τ_0_0.Distance.IntegerLiteralType : _BuiltinIntegerLiteralConvertible> (@out RangeGenerator<τ_0_0>, @in Range<τ_0_0>) -> ()

  dealloc_stack %7#0 : $*@local_storage C         // id: %11

  dealloc_stack %5#0 : $*@local_storage Range // id: %12

  %13 = alloc_stack $Optional            // users: %16, %17, %21, %37, %50, %55, %56

  // function_ref Swift.RangeGenerator.next (inout Swift.RangeGenerator)() -> Swift.Optional

  %14 = function_ref Swift.RangeGenerator.next (inout Swift.RangeGenerator)() -> A? : $@cc(method) @thin <τ_0_0 where τ_0_0 : ForwardIndexType, τ_0_0.Distance : _SignedIntegerType, τ_0_0.Distance.IntegerLiteralType : _BuiltinIntegerLiteralConvertible> (@out Optional<τ_0_0>, @inout RangeGenerator<τ_0_0>) -> () // users: %16, %55

  // function_ref Swift._doesOptionalHaveValue (inout Swift.Optional) -> Builtin.Int1

  %15 = function_ref Swift._doesOptionalHaveValue (inout A?) -> Builtin.Int1 : $@thin <τ_0_0> (@inout Optional<τ_0_0>) -> Builtin.Int1 // users: %17, %56

  %16 = apply %14(%13#1, %3#1) : $@cc(method) @thin <τ_0_0 where τ_0_0 : ForwardIndexType, τ_0_0.Distance : _SignedIntegerType, τ_0_0.Distance.IntegerLiteralType : _BuiltinIntegerLiteralConvertible> (@out Optional<τ_0_0>, @inout RangeGenerator<τ_0_0>) -> ()

  %17 = apply [transparent] %15(%13#1) : $@thin <τ_0_0> (@inout Optional<τ_0_0>) -> Builtin.Int1 // user: %18

  cond_br %17, bb1, bb2                           // id: %18


  bb1:                                              // Preds: bb0 bb4

```

これって、**Swift標準ライブラリの中身も[出力](https://gist.github.com/norio-nomura/e30c5450acfbc0bbf9d9#file-indexof-o-sil-L684-L764)されてる！**

ふむふむ、なるほど。で`find()`の実装を参考にしたらこうなった。

```swift

func v2_1_index_of(domain: C, condition: C.Generator.Element -> Bool) -> C.Index? {

  for idx in indices(domain) {

    if condition(domain[idx]) {

      return idx

    }

  }

  return nil

}

```

で、ベンチマークは

> :0: Test Case '-[Benchmark.Benchmark testPerformance_v1]' measured [Time, seconds] average: 1.557,…

> :0: Test Case '-[Benchmark.Benchmark testPerformance_v2_1]' measured [Time, seconds] average: 1.057,…

> :0: Test Case '-[Benchmark.Benchmark testPerformance_v4]' measured [Time, seconds] average: 2.403,…

**おお！`lazy()`版より速くなった！**

# まとめ

**`swiftc -emit-sil -O`にはSwift標準ライブラリの中身も出力されるので、暇な人は読んでみよう！**

---

[@norio_nomura](https:/twitter.com/norio_nomura)