[cxx-interop] Create benchmarks for using std::span in Swift

Also adds test to use-std-span.swift

Author: susmonteiro

benchmark/CMakeLists.txt

@@ -214,6 +214,7 @@ set(SWIFT_BENCH_MODULES
     cxx-source/CxxVectorSum
     # TODO: rdar://92120528
     # cxx-source/ReadAccessor
+    cxx-source/CxxSpanTests
 )
 
 set(SWIFT_MULTISOURCE_SWIFT_BENCHES

benchmark/cxx-source/CxxSpanTests.swift

@@ -0,0 +1,115 @@
+//===--- CxxSpanTests.swift ----------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2023 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
+import CxxStdlibPerformance
+import CxxStdlib
+
+let iterRepeatFactor = 7
+
+public let benchmarks = [
+  BenchmarkInfo(
+    name: "CxxSpanTests.raw.iterator",
+    runFunction: rawIterator,
+    tags: [.validation, .bridging, .cxxInterop],
+    setUpFunction: makeSpanOnce),
+  BenchmarkInfo(
+    name: "CxxSpanTests.index.subscript",
+    runFunction: indexAndSubscript,
+    tags: [.validation, .bridging, .cxxInterop],
+    setUpFunction: makeSpanOnce),
+  BenchmarkInfo(
+    name: "CxxSpanTests.for.loop",
+    runFunction: forInLoop,
+    tags: [.validation, .bridging, .cxxInterop],
+    setUpFunction: makeSpanOnce),
+  BenchmarkInfo(
+    name: "CxxSpanTests.map",
+    runFunction: mapSpan,
+    tags: [.validation, .bridging, .cxxInterop],
+    setUpFunction: makeSpanOnce),
+  BenchmarkInfo(
+    name: "CxxSpanTests.filter",
+    runFunction: filterSpan,
+    tags: [.validation, .bridging, .cxxInterop],
+    setUpFunction: makeSpanOnce),
+  BenchmarkInfo(
+    name: "CxxSpanTests.reduce",
+    runFunction: reduceSpan,
+    tags: [.validation, .bridging, .cxxInterop],
+    setUpFunction: makeSpanOnce)
+]
+
+func makeSpanOnce() {
+  initSpan()
+}
+
+@inline(never)
+public func rawIterator(_ n: Int) {
+  var sum: UInt32 = 0
+  for _ in 0..<(n * iterRepeatFactor) {
+    var b = span.__beginUnsafe()
+    let e = span.__endUnsafe()
+    while b != e {
+      sum = sum &+ b.pointee
+      b = b.successor()
+    }
+  }
+  blackHole(sum)
+}
+
+@inline(never)
+public func indexAndSubscript(_ n: Int) {
+  var sum: UInt32 = 0
+  for _ in 0..<(n * iterRepeatFactor) {
+    for i in 0..<span.size() {
+      sum = sum &+ span[i]
+    }
+  }
+  blackHole(sum)
+}
+
+@inline(never)
+public func forInLoop(_ n: Int) {
+  var sum: UInt32 = 0
+  for _ in 0..<(n * iterRepeatFactor) {
+    for x in span {
+      sum = sum &+ x
+    }
+  }
+  blackHole(sum)
+}
+
+@inline(never)
+public func mapSpan(_ n: Int) {
+  for _ in 0..<(n * iterRepeatFactor) {
+    let result = span.map { $0 + 5 }
+    blackHole(result)
+  }
+}
+
+@inline(never)
+public func filterSpan(_ n: Int) {
+  for _ in 0..<(n * iterRepeatFactor) {
+    let result = span.filter { $0 % 2 == 0 }
+    blackHole(result)
+  }
+}
+
+@inline(never)
+public func reduceSpan(_ n: Int) {
+  var sum: UInt32 = 0
+  for _ in 0..<(n * iterRepeatFactor) {
+    sum = sum &+ span.reduce(sum, &+)
+  }
+  blackHole(sum)
+}

benchmark/utils/CxxTests/CxxStdlibPerformance.h

@@ -3,12 +3,19 @@
 #include <cstdint>
 #include <vector>
 #include <set>
+#include <span>
 
+static const size_t spanSize = 25000;
+
+using ArrayOfU32 = uint32_t[spanSize];
 using VectorOfU32 = std::vector<uint32_t>;
 using SetOfU32 = std::set<uint32_t>;
+using SpanOfU32 = std::span<uint32_t>;
 
+static inline ArrayOfU32 array;
 static inline VectorOfU32 vec;
 static inline SetOfU32 set;
+static inline SpanOfU32 span;
 
 inline void initVector(size_t size) {
     if (!vec.empty()) {
@@ -29,6 +36,16 @@ inline void initSet(size_t size) {
     }
 }
 
+inline void initSpan() {
+    if (!span.empty()) {
+        return;
+    }
+    for (size_t i = 0; i < spanSize; ++i) {
+        array[i] = uint32_t(i);
+    }
+    span = SpanOfU32(array);
+}
+
 inline VectorOfU32 makeVector32(size_t size) {
     initVector(size);
     return vec;

benchmark/utils/main.swift

@@ -60,6 +60,7 @@ import CreateObjects
 import CxxStringConversion
 // rdar://128520766
 // import CxxVectorSum
+import CxxSpanTests
 import DataBenchmarks
 import DeadArray
 import DevirtualizeProtocolComposition
@@ -258,6 +259,7 @@ register(CreateObjects.benchmarks)
 register(CxxStringConversion.benchmarks)
 // rdar://128520766
 // register(CxxVectorSum.benchmarks)
+register(CxxSpanTests.benchmarks)
 register(DataBenchmarks.benchmarks)
 register(DeadArray.benchmarks)
 register(DevirtualizeProtocolComposition.benchmarks)

test/Interop/Cxx/stdlib/Inputs/std-span.h

@@ -50,6 +50,10 @@ inline Span initSpan() {
   return Span(a);
 }
 
+inline Span initSpan(int arr[], size_t size) {
+  return Span(arr, size);
+}
+
 inline struct SpanBox getStructSpanBox() { return {iarray, iarray, sarray, sarray}; }
 
 #endif // TEST_INTEROP_CXX_STDLIB_INPUTS_STD_SPAN_H

test/Interop/Cxx/stdlib/use-std-span.swift

@@ -176,6 +176,18 @@ StdSpanTestSuite.test("Init SpanOfInt") {
   expectFalse(cs.empty())
 }
 
+StdSpanTestSuite.test("Init SpanOfInt from Swift array") {
+  var arr: [Int32] = [1, 2, 3]
+  arr.withUnsafeMutableBufferPointer{ ubpointer in
+    let s = initSpan(ubpointer.baseAddress!, ubpointer.count)
+    expectEqual(s.size(), 3)
+    expectFalse(s.empty())
+    expectEqual(s[0], 1)
+    expectEqual(s[1], 2)
+    expectEqual(s[2], 3)
+  }
+}
+
 StdSpanTestSuite.test("Access static SpanOfInt") {
   expectEqual(icspan.size(), 3)
   expectFalse(icspan.empty())