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[benchmark] Breadcrumbs: swap PRNG implementations #24367

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merged 1 commit into from
Apr 30, 2019
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[benchmark] Breadcrumbs: swap PRNG implementations #24367

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31 changes: 7 additions & 24 deletions benchmark/single-source/Breadcrumbs.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -45,23 +45,6 @@ extension String {
}
}

let seed = 0x12345678

/// A linear congruential PRNG.
struct LCRNG: RandomNumberGenerator {
private var state: UInt64

init(seed: Int) {
state = UInt64(truncatingIfNeeded: seed)
for _ in 0..<10 { _ = next() }
}

mutating func next() -> UInt64 {
state = 2862933555777941757 &* state &+ 3037000493
return state
}
}

extension Collection {
/// Returns a randomly ordered array of random non-overlapping index ranges
/// that cover this collection entirely.
Expand Down Expand Up @@ -254,7 +237,7 @@ class UTF16ToIdx: BenchmarkBase {

override func setUp() {
super.setUp()
var rng = LCRNG(seed: seed)
var rng = SplitMix64(seed: 42)
let range = 0 ..< inputString.utf16.count
inputOffsets = Array(range.shuffled(using: &rng).prefix(count))
}
Expand Down Expand Up @@ -286,7 +269,7 @@ class IdxToUTF16: BenchmarkBase {

override func setUp() {
super.setUp()
var rng = LCRNG(seed: seed)
var rng = SplitMix64(seed: 42)
inputIndices = Array(inputString.indices.shuffled(using: &rng).prefix(count))
}

Expand Down Expand Up @@ -318,7 +301,7 @@ class UTF16ToIdxRange: BenchmarkBase {

override func setUp() {
super.setUp()
var rng = LCRNG(seed: seed)
var rng = SplitMix64(seed: 42)
inputOffsets = (
0 ..< inputString.utf16.count
).randomIndexRanges(count: count, using: &rng)
Expand Down Expand Up @@ -352,7 +335,7 @@ class IdxToUTF16Range: BenchmarkBase {

override func setUp() {
super.setUp()
var rng = LCRNG(seed: seed)
var rng = SplitMix64(seed: 42)
inputIndices = self.inputString.randomIndexRanges(count: count, using: &rng)
}

Expand Down Expand Up @@ -384,7 +367,7 @@ class CopyUTF16CodeUnits: BenchmarkBase {

override func setUp() {
super.setUp()
var rng = LCRNG(seed: seed)
var rng = SplitMix64(seed: 42)
inputIndices = (
0 ..< inputString.utf16.count
).randomIndexRanges(count: count, using: &rng)
Expand Down Expand Up @@ -425,7 +408,7 @@ class MutatedUTF16ToIdx: BenchmarkBase {

override func setUp() {
super.setUp()
var generator = LCRNG(seed: seed)
var generator = SplitMix64(seed: 42)
let range = 0 ..< inputString.utf16.count
inputOffsets = Array(range.shuffled(using: &generator).prefix(count))
}
Expand Down Expand Up @@ -469,7 +452,7 @@ class MutatedIdxToUTF16: BenchmarkBase {

override func setUp() {
super.setUp()
var rng = LCRNG(seed: seed)
var rng = SplitMix64(seed: 42)
inputIndices = Array(inputString.indices.shuffled(using: &rng).prefix(count))
}

Expand Down