Adding upstream version 1.1.1.upstream/1.1.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 65 insertions, 0 deletions

diff --git a/tests/bench.hpp b/tests/bench.hpp
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+++ b/tests/bench.hpp
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+// Copyright 2015 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Extracted from google benchmarks suite
+// c.f. https://github.com/google/benchmark/blob/master/include/benchmark/benchmark_api.h
+//
+// These two functions DoNotOptimize and ClobberMemory prevent the compiler
+// from optimizing in certain ways.
+//
+// There is an excellent talk by Chandler Carruth about this here:
+// https://www.youtube.com/watch?v=nXaxk27zwlk
+
+#ifndef FROZEN_LETITGO_BENCH_HPP
+#define FROZEN_LETITGO_BENCH_HPP
+
+namespace benchmark {
+
+#if defined(__GNUC__)
+#define BENCHMARK_ALWAYS_INLINE __attribute__((always_inline))
+#else
+#define BENCHMARK_ALWAYS_INLINE
+#endif
+
+#if defined(__GNUC__)
+template <class Tp>
+inline BENCHMARK_ALWAYS_INLINE void
+DoNotOptimize(Tp const & value) {
+  asm volatile("" : : "g"(value) : "memory");
+}
+// Force the compiler to flush pending writes to global memory. Acts as an
+// effective read/write barrier
+inline BENCHMARK_ALWAYS_INLINE void
+ClobberMemory() {
+  asm volatile("" : : : "memory");
+}
+
+#else
+
+template <class Tp>
+inline BENCHMARK_ALWAYS_INLINE void
+DoNotOptimize(Tp const & value) {
+    static_cast<volatile void>(&reinterpret_cast<char const volatile&>(value));
+}
+
+// TODO
+template <class Tp>
+inline BENCHMARK_ALWAYS_INLINE void
+ClobberMemory() {}
+
+#endif
+
+} // end namespace benchmark
+
+#endif