[interop] cxx vec benchmark - initialize vector before benchmark

Author: hyp

benchmark/cxx-source/CxxVectorSum.swift

@@ -21,25 +21,34 @@ public let benchmarks = [
   BenchmarkInfo(
       name: "CxxVecU32.Sum.Cxx.RangedForLoop",
       runFunction: run_CxxVectorOfU32_Sum_Cxx_RangedForLoop,
-      tags: [.validation, .bridging, .cxxInterop]),
+      tags: [.validation, .bridging, .cxxInterop],
+      setUpFunction: makeVectorOnce),
   BenchmarkInfo(
     name: "CxxVecU32.Sum.Swift.ForInLoop",
     runFunction: run_CxxVectorOfU32_Sum_Swift_ForInLoop,
-    tags: [.validation, .bridging, .cxxInterop]),
+    tags: [.validation, .bridging, .cxxInterop],
+    setUpFunction: makeVectorOnce),
   BenchmarkInfo(
     name: "CxxVecU32.Sum.Swift.IteratorLoop",
     runFunction: run_CxxVectorOfU32_Sum_Swift_RawIteratorLoop,
-    tags: [.validation, .bridging, .cxxInterop]),
+    tags: [.validation, .bridging, .cxxInterop],
+    setUpFunction: makeVectorOnce),
   BenchmarkInfo(
     name: "CxxVecU32.Sum.Swift.SubscriptLoop",
     runFunction: run_CxxVectorOfU32_Sum_Swift_IndexAndSubscriptLoop,
-    tags: [.validation, .bridging, .cxxInterop]),
+    tags: [.validation, .bridging, .cxxInterop],
+    setUpFunction: makeVectorOnce),
   BenchmarkInfo(
     name: "CxxVecU32.Sum.Swift.Reduce",
     runFunction: run_CxxVectorOfU32_Sum_Swift_Reduce,
-    tags: [.validation, .bridging, .cxxInterop])
+    tags: [.validation, .bridging, .cxxInterop],
+    setUpFunction: makeVectorOnce)
 ]
 
+func makeVectorOnce() {
+    initVector(vectorSize)
+}
+
 // FIXME: compare CxxVectorOfU32SumInCxx to CxxVectorOfU32SumInSwift and
 // establish an expected threshold of performance, which when exceeded should
 // fail the benchmark.

benchmark/utils/CxxTests/CxxStdlibPerformance.h

@@ -5,13 +5,21 @@
 
 using VectorOfU32 = std::vector<uint32_t>;
 
-inline VectorOfU32 makeVector32(size_t size) {
-    auto result = VectorOfU32();
-    result.reserve(size);
+static inline VectorOfU32 vec;
+
+inline void initVector(size_t size) {
+    if (!vec.empty()) {
+        return;
+    }
+    vec.reserve(size);
     for (size_t i = 0; i < size; ++i) {
-        result.push_back(uint32_t(i));
+        vec.push_back(uint32_t(i));
     }
-    return result;
+}
+
+inline VectorOfU32 makeVector32(size_t size) {
+    initVector(size);
+    return vec;
 }
 
 inline uint32_t testVector32Sum(size_t vectorSize, size_t iters) {