mirror of
https://github.com/apple/swift.git
synced 2025-12-14 20:36:38 +01:00
6ef5908bdc
The `getFalse` utility function was not excluded from cross-module-optimization, which led the optimizer to completely eliminate the main loop body Also, the passed `N` was shadowed by a local `n`.
53 lines
1.6 KiB
Swift
53 lines
1.6 KiB
Swift
//===--- Ackermann.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
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
// This test is based on test Ackermann from utils/benchmark, with modifications
|
|
// for performance measuring.
|
|
import TestsUtils
|
|
|
|
public let benchmarks =
|
|
BenchmarkInfo(
|
|
name: "Ackermann2",
|
|
runFunction: run_Ackermann,
|
|
tags: [.algorithm])
|
|
|
|
func _ackermann(_ m: Int, _ n : Int) -> Int {
|
|
if (m == 0) { return n + 1 }
|
|
if (n == 0) { return _ackermann(m - 1, 1) }
|
|
return _ackermann(m - 1, _ackermann(m, n - 1))
|
|
}
|
|
|
|
@inline(never)
|
|
func ackermann(_ m: Int, _ n : Int) -> Int {
|
|
// This if prevents optimizer from computing return value of Ackermann(3,9)
|
|
// at compile time.
|
|
if getFalse() { return 0 }
|
|
if (m == 0) { return n + 1 }
|
|
if (n == 0) { return _ackermann(m - 1, 1) }
|
|
return _ackermann(m - 1, _ackermann(m, n - 1))
|
|
}
|
|
|
|
let ref_result = [5, 13, 29, 61, 125, 253, 509, 1021, 2045, 4093, 8189, 16381, 32765, 65533, 131069]
|
|
|
|
@inline(never)
|
|
public func run_Ackermann(_ N: Int) {
|
|
let (m, n) = (3, 6)
|
|
var result = 0
|
|
for _ in 1...N {
|
|
result = ackermann(m, n)
|
|
if result != ref_result[n] {
|
|
break
|
|
}
|
|
}
|
|
check(result == ref_result[n])
|
|
}
|