[libcxx] Add support for benchmark tests using Google Benchmark.
Summary:
This patch does the following:
1. Checks in a copy of the Google Benchmark library into the libc++ repo under `utils/google-benchmark`.
2. Teaches libc++ how to build Google Benchmark against both (A) in-tree libc++ and (B) the platforms native STL.
3. Allows performance benchmarks to be built as part of the libc++ build.
Building the benchmarks (and Google Benchmark) is off by default. It must be enabled using the CMake option `-DLIBCXX_INCLUDE_BENCHMARKS=ON`. When this option is enabled the tests under `libcxx/benchmarks` can be built using the `libcxx-benchmarks` target.
On Linux platforms where libstdc++ is the default STL the CMake option `-DLIBCXX_BUILD_BENCHMARKS_NATIVE_STDLIB=ON` can be used to build each benchmark test against libstdc++ as well. This is useful for comparing performance between standard libraries.
Support for benchmarks is currently very minimal. They must be manually run by the user and there is no mechanism for detecting performance regressions.
Known Issues:
* `-DLIBCXX_INCLUDE_BENCHMARKS=ON` is only supported for Clang, and not GCC, since the `-stdlib=libc++` option is needed to build Google Benchmark.
Reviewers: danalbert, dberlin, chandlerc, mclow.lists, jroelofs
Subscribers: chandlerc, dberlin, tberghammer, danalbert, srhines, hfinkel
Differential Revision: https://reviews.llvm.org/D22240
llvm-svn: 276049
diff --git a/libcxx/utils/google-benchmark/src/internal_macros.h b/libcxx/utils/google-benchmark/src/internal_macros.h
new file mode 100644
index 0000000..1080ac9
--- /dev/null
+++ b/libcxx/utils/google-benchmark/src/internal_macros.h
@@ -0,0 +1,40 @@
+#ifndef BENCHMARK_INTERNAL_MACROS_H_
+#define BENCHMARK_INTERNAL_MACROS_H_
+
+#include "benchmark/macros.h"
+
+#ifndef __has_feature
+# define __has_feature(x) 0
+#endif
+
+#if __has_feature(cxx_attributes)
+# define BENCHMARK_NORETURN [[noreturn]]
+#elif defined(__GNUC__)
+# define BENCHMARK_NORETURN __attribute__((noreturn))
+#else
+# define BENCHMARK_NORETURN
+#endif
+
+#if defined(__CYGWIN__)
+# define BENCHMARK_OS_CYGWIN 1
+#elif defined(_WIN32)
+# define BENCHMARK_OS_WINDOWS 1
+#elif defined(__APPLE__)
+// TODO(ericwf) This doesn't actually check that it is a Mac OSX system. Just
+// that it is an apple system.
+# define BENCHMARK_OS_MACOSX 1
+#elif defined(__FreeBSD__)
+# define BENCHMARK_OS_FREEBSD 1
+#elif defined(__linux__)
+# define BENCHMARK_OS_LINUX 1
+#endif
+
+#if defined(__clang__)
+# define COMPILER_CLANG
+#elif defined(_MSC_VER)
+# define COMPILER_MSVC
+#elif defined(__GNUC__)
+# define COMPILER_GCC
+#endif
+
+#endif // BENCHMARK_INTERNAL_MACROS_H_