Fibonacci.swift

//===--- Fibonacci.swift --------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2021 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

import TestsUtils

public let benchmarks =
  BenchmarkInfo(
    name: "Fibonacci2",
    runFunction: run_Fibonacci,
    tags: [.algorithm])

func _fibonacci(_ n: Int) -> Int {
  if (n <= 2) { return 1 }
  return _fibonacci(n - 2) + _fibonacci(n - 1)
}

@inline(never)
func fibonacci(_ n: Int) -> Int {
  // This if prevents optimizer from computing return value of fibonacci(32)
  // at compile time.
  if getFalse() { return 0 }

  if (n <= 2) { return 1 }
  return _fibonacci(n - 2) + _fibonacci(n - 1)
}

@inline(never)
public func run_Fibonacci(_ N: Int) {
  let n = 24
  let ref_result = 46368
  var result = 0
  for _ in 1...N {
    result = fibonacci(n)
    if result != ref_result {
      break
    }
  }
  check(result == ref_result)
}