Extracted from Substring.swift benchmark

substring_benchmark.swift

print("start")

public var i = 0

// @inline(never)
// public func blackHole<T>(_ x: T) {
//   i += 1  
// }
@inline(never)
public func blackHole(_ x: Bool) {
  i += x ? 1 : 0
}
@inline(never)
public func blackHole<C: Collection>(_ x: C) {
  i += x.isEmpty ? 1 : 0
}
@inline(never)
public func blackHole<T>(_ x: UnsafeMutablePointer<T>) {
  i += UInt(bitPattern: x) % 2 == 0 ? 1 : 0
}

@inline(never)
public func CheckResults(_ x: Bool) {
  guard x else { fatalError() }  
}




// import TestsUtils

// public let SubstringTest = [
//   BenchmarkInfo(name: "EqualStringSubstring", runFunction: run_EqualStringSubstring, tags: [.validation, .api, .String]),
//   BenchmarkInfo(name: "EqualSubstringString", runFunction: run_EqualSubstringString, tags: [.validation, .api, .String]),
//   BenchmarkInfo(name: "EqualSubstringSubstring", runFunction: run_EqualSubstringSubstring, tags: [.validation, .api, .String]),
//   BenchmarkInfo(name: "EqualSubstringSubstringGenericEquatable", runFunction: run_EqualSubstringSubstringGenericEquatable, tags: [.validation, .api, .String]),
//   BenchmarkInfo(name: "LessSubstringSubstring", runFunction: run_LessSubstringSubstring, tags: [.validation, .api, .String]),
//   BenchmarkInfo(name: "LessSubstringSubstringGenericComparable", runFunction: run_LessSubstringSubstringGenericComparable, tags: [.validation, .api, .String]),
//   BenchmarkInfo(name: "StringFromLongWholeSubstring", runFunction: run_StringFromLongWholeSubstring, tags: [.validation, .api, .String]),
//   BenchmarkInfo(name: "StringFromLongWholeSubstringGeneric", runFunction: run_StringFromLongWholeSubstringGeneric, tags: [.validation, .api, .String]),
//   BenchmarkInfo(name: "SubstringComparable", runFunction: run_SubstringComparable, tags: [.validation, .api, .String]),
//   BenchmarkInfo(name: "SubstringEqualString", runFunction: run_SubstringEqualString, tags: [.validation, .api, .String]),
//   BenchmarkInfo(name: "SubstringEquatable", runFunction: run_SubstringEquatable, tags: [.validation, .api, .String]),
//   BenchmarkInfo(name: "SubstringFromLongString", runFunction: run_SubstringFromLongString, tags: [.validation, .api, .String]),
//   BenchmarkInfo(name: "SubstringFromLongStringGeneric", runFunction: run_SubstringFromLongStringGeneric, tags: [.validation, .api, .String]),
// ]

// A string that doesn't fit in small string storage and doesn't fit in Latin-1
let longWide = "fὢasὢodὢijὢadὢolὢsjὢalὢsdὢjlὢasὢdfὢijὢliὢsdὢjøὢslὢdiὢalὢiὢ"

@inline(never)
public func run_SubstringFromLongString(_ N: Int) {
  var s = longWide
  s += "!" // ensure the string has a real buffer
  for _ in 1...N*500 {
    blackHole(Substring(s))
  }
}

func create<T : RangeReplaceableCollection, U : Collection>(
  _: T.Type, from source: U
) where T.Element == U.Element {
  blackHole(T(source))
}

@inline(never)
public func run_SubstringFromLongStringGeneric(_ N: Int) {
  var s = longWide
  s += "!" // ensure the string has a real buffer
  for _ in 1...N*500 {
    create(Substring.self, from: s)
  }
}

@inline(never)
public func run_StringFromLongWholeSubstring(_ N: Int) {
  var s0 = longWide
  s0 += "!" // ensure the string has a real buffer
  let s = Substring(s0)
  for _ in 1...N*500 {
    blackHole(String(s))
  }
}

@inline(never)
public func run_StringFromLongWholeSubstringGeneric(_ N: Int) {
  var s0 = longWide
  s0 += "!" // ensure the string has a real buffer
  let s = Substring(s0)
  for _ in 1...N*500 {
    create(String.self, from: s)
  }
}

private func equivalentWithDistinctBuffers() -> (String, Substring) {
  var s0 = longWide
  withUnsafeMutablePointer(to: &s0) { blackHole($0) }
  s0 += "!"
  
  // These two should be equal but with distinct buffers, both refcounted.
  let a = Substring(s0).dropFirst()
  let b = String(a)
  return (b, a)
}

@inline(never)
public func run_EqualStringSubstring(_ N: Int) {
  let (a, b) = equivalentWithDistinctBuffers()
  for _ in 1...N*500 {
    blackHole(a == b)
  }
}

@inline(never)
public func run_EqualSubstringString(_ N: Int) {
  let (a, b) = equivalentWithDistinctBuffers()
  for _ in 1...N*500 {
    blackHole(b == a)
  }
}

@inline(never)
public func run_EqualSubstringSubstring(_ N: Int) {
  let (_, a) = equivalentWithDistinctBuffers()
  let (_, b) = equivalentWithDistinctBuffers()
  for _ in 1...N*500 {
    blackHole(a == b)
  }
}

@inline(never)
public func run_EqualSubstringSubstringGenericEquatable(_ N: Int) {
  let (_, a) = equivalentWithDistinctBuffers()
  let (_, b) = equivalentWithDistinctBuffers()
  func check<T>(_ x: T, _ y: T) where T : Equatable {
    blackHole(x == y)
  }
  for _ in 1...N*500 {
    check(a, b)
  }
}

/*
func checkEqual<T, U>(_ x: T, _ y: U)
where T : StringProtocol, U : StringProtocol {
  blackHole(x == y)
}

@inline(never)
public func run _EqualStringSubstringGenericStringProtocol(_ N: Int) {
  let (a, b) = equivalentWithDistinctBuffers()
  for _ in 1...N*500 {
    checkEqual(a, b)
  }
}

@inline(never)
public func run _EqualSubstringStringGenericStringProtocol(_ N: Int) {
  let (a, b) = equivalentWithDistinctBuffers()
  for _ in 1...N*500 {
    checkEqual(b, a)
  }
}

@inline(never)
public func run _EqualSubstringSubstringGenericStringProtocol(_ N: Int) {
  let (_, a) = equivalentWithDistinctBuffers()
  let (_, b) = equivalentWithDistinctBuffers()
  for _ in 1...N*500 {
    checkEqual(a, b)
  }
}
*/

//===----------------------------------------------------------------------===//

/*
@inline(never)
public func run _LessStringSubstring(_ N: Int) {
  let (a, b) = equivalentWithDistinctBuffers()
  for _ in 1...N*500 {
    blackHole(a < b)
  }
}

@inline(never)
public func run _LessSubstringString(_ N: Int) {
  let (a, b) = equivalentWithDistinctBuffers()
  for _ in 1...N*500 {
    blackHole(b < a)
  }
}
*/

@inline(never)
public func run_LessSubstringSubstring(_ N: Int) {
  let (_, a) = equivalentWithDistinctBuffers()
  let (_, b) = equivalentWithDistinctBuffers()
  for _ in 1...N*500 {
    blackHole(a < b)
  }
}

@inline(never)
public func run_LessSubstringSubstringGenericComparable(_ N: Int) {
  let (_, a) = equivalentWithDistinctBuffers()
  let (_, b) = equivalentWithDistinctBuffers()
  func check<T>(_ x: T, _ y: T) where T : Comparable {
    blackHole(x < y)
  }
  for _ in 1...N*500 {
    check(a, b)
  }
}

@inline(never)
public func run_SubstringEquatable(_ N: Int) {
  var string = "pen,pineapple,apple,pen"
  string += ",✒️,🍍,🍏,✒️"
  let substrings = string.split(separator: ",")
  var count = 0
  for _ in 1...N*500 {
    for s in substrings {
      if substrings.contains(s) { count = count &+ 1 }
    }
  }
  CheckResults(count == 8*N*500)
}

@inline(never)
public func run_SubstringEqualString(_ N: Int) {
  var string = "pen,pineapple,apple,pen"
  string += ",✒️,🍍,🍏,✒️"
  let substrings = string.split(separator: ",")
  let pineapple = "pineapple"
  let apple = "🍏"
  var count = 0
  for _ in 1...N*500 {
    for s in substrings {
      if s == pineapple || s == apple { count = count &+ 1 }
    }
  }
  CheckResults(count == 2*N*500)
}

@inline(never)
public func run_SubstringComparable(_ N: Int) {
  var string = "pen,pineapple,apple,pen"
  string += ",✒️,🍍,🍏,✒️"
  let substrings = string.split(separator: ",")
  let comparison = substrings + ["PPAP"]
  var count = 0
  for _ in 1...N*500 {
    if substrings.lexicographicallyPrecedes(comparison) {
      count = count &+ 1
    }
  }
  CheckResults(count == N*500)
}

/*
func checkLess<T, U>(_ x: T, _ y: U)
where T : StringProtocol, U : StringProtocol {
  blackHole(x < y)
}

@inline(never)
public func run _LessStringSubstringGenericStringProtocol(_ N: Int) {
  let (a, b) = equivalentWithDistinctBuffers()
  for _ in 1...N*500 {
    checkLess(a, b)
  }
}

@inline(never)
public func run _LessSubstringStringGenericStringProtocol(_ N: Int) {
  let (a, b) = equivalentWithDistinctBuffers()
  for _ in 1...N*500 {
    checkLess(b, a)
  }
}

@inline(never)
public func run _LessSubstringSubstringGenericStringProtocol(_ N: Int) {
  let (_, a) = equivalentWithDistinctBuffers()
  let (_, b) = equivalentWithDistinctBuffers()
  for _ in 1...N*500 {
    checkLess(a, b)
  }
}
*/


import Dispatch

func time<T>(_ _caller : String = #function, _ block: () -> T) -> T {
  let start = DispatchTime.now()
  let res = block()
  let end = DispatchTime.now()
  let milliseconds = (end.uptimeNanoseconds - start.uptimeNanoseconds) / 1_000_000
  print("\(_caller)\t\(milliseconds)")
  // print("result: \(res)")
  return res
}

let N = 1_000

print("Running...")



time("EqualStringSubstring") {
  run_EqualStringSubstring(N * 32)
}
time("EqualSubstringString") {
  run_EqualSubstringString(N * 20)
}
time("EqualSubstringSubstring") {
  run_EqualSubstringSubstring(N * 20)
}
time("EqualSubstringSubstringGenericEquatable") {
  run_EqualSubstringSubstringGenericEquatable(N * 20)
}
time("LessSubstringSubstring") {
  run_LessSubstringSubstring(N * 20)
}
time("LessSubstringSubstringGenericComparable") {
  run_LessSubstringSubstringGenericComparable(N * 20)
}
time("SubstringComparable") {
  run_SubstringComparable(N * 8)
}
time("SubstringEqualString") {
  run_SubstringEqualString(N / 4)
}
time("SubstringEquatable") {
  run_SubstringEquatable(N / 8)
}

time("StringFromLongWholeSubstringGeneric") {
  run_StringFromLongWholeSubstringGeneric(N * 4)
}
time("StringFromLongWholeSubstring ") {
  run_StringFromLongWholeSubstring(N * 4)
}