Create ReadAccessor benchmark

Create a benchmark to test the
performance of synthesized read
accessors generated to interop
with C++ [] operators.

benchmark/CMakeLists.txt

@@ -196,6 +196,7 @@ set(SWIFT_BENCH_MODULES
     single-source/WordCount
     single-source/XorLoop
     cxx-source/CreateObjects
+    cxx-source/ReadAccessor
 )
 
 set(SWIFT_MULTISOURCE_SWIFT_BENCHES

benchmark/cxx-source/ReadAccessor.swift

@@ -0,0 +1,52 @@
+// Subscripts.swift - Very brief description
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2022 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 is a simple test that reads a non trivial C++ struct using an imported
+/// subscript thousands of times.
+///
+// -----------------------------------------------------------------------------
+
+import TestsUtils
+import CxxSubscripts
+
+var vec : TwoDimensionalVector?
+
+public let benchmarks = [
+  BenchmarkInfo(
+    name: "ReadAccessor",
+    runFunction: run_ReadAccessor,
+    tags: [.validation, .bridging],
+    setUpFunction: {
+        vec = initVector()
+    })
+]
+
+@inline(never)
+public func run_ReadAccessor(_ N: Int) {
+  for i in 0...N {
+    for j in 0..<100 {
+#if os(Linux)
+      let row = vec![UInt(j)];
+#else
+      let row = vec![j];
+#endif
+      for k in 0..<1_000 {
+#if os(Linux)
+        let element = row[UInt(k)];
+#else
+        let element = row[k];
+#endif
+        blackHole(element)
+      }
+    }
+  }
+}

benchmark/utils/CxxTests/Subscripts.h

@@ -0,0 +1,10 @@
+#ifndef BENCHMARK_SUBSCRIPTS_H
+#define BENCHMARK_SUBSCRIPTS_H
+#include <vector>
+
+using TwoDimensionalVector = std::vector<std::vector<int>>;
+
+inline TwoDimensionalVector initVector() { return {100, std::vector<int>{1000, 0}}; }
+
+#endif
+

benchmark/utils/CxxTests/module.modulemap

@@ -2,3 +2,8 @@ module CxxCreateObjects {
   header "CreateObjects.h"
   requires cplusplus
 }
+
+module CxxSubscripts {
+  header "Subscripts.h"
+  requires cplusplus
+}

benchmark/utils/main.swift

@@ -152,6 +152,7 @@ import RangeAssignment
 import RangeIteration
 import RangeOverlaps
 import RangeReplaceableCollectionPlusDefault
+import ReadAccessor
 import RecursiveOwnedParameter
 import ReduceInto
 import RemoveWhere
@@ -332,6 +333,7 @@ register(RangeAssignment.benchmarks)
 register(RangeIteration.benchmarks)
 register(RangeOverlaps.benchmarks)
 register(RangeReplaceableCollectionPlusDefault.benchmarks)
+register(ReadAccessor.benchmarks)
 register(RecursiveOwnedParameter.benchmarks)
 register(ReduceInto.benchmarks)
 register(RemoveWhere.benchmarks)