[benchmark] add removeAll(keepingCapacity: true) benchmark for non-unique arrays

benchmark/CMakeLists.txt

@@ -37,6 +37,7 @@ set(SWIFT_BENCH_MODULES
     single-source/ArrayOfGenericRef
     single-source/ArrayOfPOD
     single-source/ArrayOfRef
+    single-source/ArrayRemoveAll
     single-source/ArraySetElement
     single-source/ArraySubscript
     single-source/BinaryFloatingPointConversionFromBinaryInteger

benchmark/single-source/ArrayRemoveAll.swift

@@ -0,0 +1,55 @@
+// This test checks the performance of removeAll
+// on a non-uniquely referenced array.
+
+import TestsUtils
+
+public let benchmarks = [
+  BenchmarkInfo(
+    name: "Array.removeAll.keepingCapacity.Int",
+    runFunction: run_ArrayRemoveAll_Class,
+    tags: [.validation, .api, .Array],
+    setUpFunction: { blackHole(inputArray_Class) }
+  ),
+  BenchmarkInfo(
+    name: "Array.removeAll.keepingCapacity.Object",
+    runFunction: run_ArrayRemoveAll_Int,
+    tags: [.validation, .api, .Array],
+    setUpFunction: { blackHole(inputArray_Int) }
+  )
+]
+
+class Slow {
+  public var num: Int
+
+  init(num: Int) {
+    self.num = num
+  }
+}
+
+let inputArray_Int: [Int] = Array(0..<500_000)
+let inputArray_Class: [Slow] = (0..<50_000).map(Slow.init(num:))
+
+@inline(never)
+func removeAll<T>(_ arr: [T]) -> [T] {
+  var copy = arr
+  copy.removeAll(keepingCapacity: true)
+  return copy
+}
+
+@inline(never)
+func run_ArrayRemoveAll_Class(_ n: Int) {
+  var copy = removeAll(inputArray_Class);
+  for _ in 1..<n {
+    copy = removeAll(inputArray_Class)
+  }
+  check(copy.capacity == inputArray_Class.capacity)
+}
+
+@inline(never)
+func run_ArrayRemoveAll_Int(_ n: Int) {
+  var copy = removeAll(inputArray_Int);
+  for _ in 1..<n {
+    copy = removeAll(inputArray_Int)
+  }
+  check(copy.capacity == inputArray_Int.capacity)
+}

benchmark/utils/main.swift

@@ -25,6 +25,7 @@ import ArrayOfGenericPOD
 import ArrayOfGenericRef
 import ArrayOfPOD
 import ArrayOfRef
+import ArrayRemoveAll
 import ArraySetElement
 import ArraySubscript
 import BinaryFloatingPointConversionFromBinaryInteger
@@ -217,6 +218,7 @@ register(ArrayOfGenericPOD.benchmarks)
 register(ArrayOfGenericRef.benchmarks)
 register(ArrayOfPOD.benchmarks)
 register(ArrayOfRef.benchmarks)
+register(ArrayRemoveAll.benchmarks)
 register(ArraySetElement.benchmarks)
 register(ArraySubscript.benchmarks)
 register(BinaryFloatingPointConversionFromBinaryInteger.benchmarks)